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Sample records for cells confers resistance

  1. HDAC6 promotes cell proliferation and confers resistance to temozolomide in glioblastoma.

    Science.gov (United States)

    Wang, Zhihao; Hu, Pengchao; Tang, Fang; Lian, Haiwei; Chen, Xiong; Zhang, Yingying; He, Xiaohua; Liu, Wanhong; Xie, Conghua

    2016-08-28

    Histone deacetylases are considered to be among the most promising targets in drug development for cancer therapy. Histone deacetylase 6 (HDAC6) is a unique cytoplasmic enzyme that regulates many biological processes involved in tumorigenesis through its deacetylase and ubiquitin-binding activities. Here, we report that HDAC6 is overexpressed in glioblastoma tissues and cell lines. Overexpression of HDAC6 promotes the proliferation and spheroid formation of glioblastoma cells. HDAC6 overexpression confers resistance to temozolomide (TMZ) mediated cell proliferation inhibition and apoptosis induction. Conversely, knockdown of HDAC6 inhibits cell proliferation, impairs spheroid formation and sensitizes glioblastoma cells to TMZ. The inhibition of HDAC6 deacetylase activity by selective inhibitors inhibits the proliferation of glioblastoma cells and induces apoptosis. HDAC6 selective inhibitors can sensitize glioblastoma cells to TMZ. Moreover, we showed that HDAC6 mediated EGFR stabilization might partly account for its oncogenic role in glioblastoma. TMZ resistant glioblastoma cells showed higher expression of HDAC6 and more activation of EGFR. HDAC6 inhibitors decrease EGFR protein levels and impair the activation of the EGFR pathway. Taken together, our results suggest that the inhibition of HDAC6 may be a promising strategy for the treatment of glioblastoma.

  2. Disruptive environmental chemicals and cellular mechanisms that confer resistance to cell death.

    Science.gov (United States)

    Narayanan, Kannan Badri; Ali, Manaf; Barclay, Barry J; Cheng, Qiang Shawn; D'Abronzo, Leandro; Dornetshuber-Fleiss, Rita; Ghosh, Paramita M; Gonzalez Guzman, Michael J; Lee, Tae-Jin; Leung, Po Sing; Li, Lin; Luanpitpong, Suidjit; Ratovitski, Edward; Rojanasakul, Yon; Romano, Maria Fiammetta; Romano, Simona; Sinha, Ranjeet K; Yedjou, Clement; Al-Mulla, Fahd; Al-Temaimi, Rabeah; Amedei, Amedeo; Brown, Dustin G; Ryan, Elizabeth P; Colacci, Annamaria; Hamid, Roslida A; Mondello, Chiara; Raju, Jayadev; Salem, Hosni K; Woodrick, Jordan; Scovassi, A Ivana; Singh, Neetu; Vaccari, Monica; Roy, Rabindra; Forte, Stefano; Memeo, Lorenzo; Kim, Seo Yun; Bisson, William H; Lowe, Leroy; Park, Hyun Ho

    2015-06-01

    Cell death is a process of dying within biological cells that are ceasing to function. This process is essential in regulating organism development, tissue homeostasis, and to eliminate cells in the body that are irreparably damaged. In general, dysfunction in normal cellular death is tightly linked to cancer progression. Specifically, the up-regulation of pro-survival factors, including oncogenic factors and antiapoptotic signaling pathways, and the down-regulation of pro-apoptotic factors, including tumor suppressive factors, confers resistance to cell death in tumor cells, which supports the emergence of a fully immortalized cellular phenotype. This review considers the potential relevance of ubiquitous environmental chemical exposures that have been shown to disrupt key pathways and mechanisms associated with this sort of dysfunction. Specifically, bisphenol A, chlorothalonil, dibutyl phthalate, dichlorvos, lindane, linuron, methoxychlor and oxyfluorfen are discussed as prototypical chemical disruptors; as their effects relate to resistance to cell death, as constituents within environmental mixtures and as potential contributors to environmental carcinogenesis. PMID:26106145

  3. Loss of RASSF2 Enhances Tumorigencity of Lung Cancer Cells and Confers Resistance to Chemotherapy

    Directory of Open Access Journals (Sweden)

    Jennifer Clark

    2012-01-01

    Full Text Available RASSF2 is a novel pro-apoptotic effector of K-Ras that is frequently inactivated in a variety of primary tumors by promoter methylation. Inactivation of RASSF2 enhances K-Ras-mediated transformation and overexpression of RASSF2 suppresses tumor cell growth. In this study, we confirm that RASSF2 and K-Ras form an endogenous complex, validating that RASSF2 is a bona fide K-Ras effector. We adopted an RNAi approach to determine the effects of inactivation of RASSF2 on the transformed phenotype of lung cancer cells containing an oncogenic K-Ras. Loss of RASSF2 expression resulted in a more aggressive phenotype that was characterized by enhanced cell proliferation and invasion, decreased cell adhesion, the ability to grow in an anchorage-independent manner and cell morphological changes. This enhanced transformed phenotype of the cells correlated with increased levels of activated AKT, indicating that RASSF2 can modulate Ras signaling pathways. Loss of RASSF2 expression also confers resistance to taxol and cisplatin, two frontline therapeutics for the treatment of lung cancer. Thus we have shown that inactivation of RASSF2, a process that occurs frequently in primary tumors, enhances the transforming potential of activated K-Ras and our data suggests that RASSF2 may be a novel candidate for epigenetic-based therapy in lung cancer.

  4. Actin remodeling confers BRAF inhibitor resistance to melanoma cells through YAP/TAZ activation.

    Science.gov (United States)

    Kim, Min Hwan; Kim, Jongshin; Hong, Hyowon; Lee, Si-Hyung; Lee, June-Koo; Jung, Eunji; Kim, Joon

    2016-03-01

    The activation of transcriptional coactivators YAP and its paralog TAZ has been shown to promote resistance to anti-cancer therapies. YAP/TAZ activity is tightly coupled to actin cytoskeleton architecture. However, the influence of actin remodeling on cancer drug resistance remains largely unexplored. Here, we report a pivotal role of actin remodeling in YAP/TAZ-dependent BRAF inhibitor resistance in BRAF V600E mutant melanoma cells. Melanoma cells resistant to the BRAF inhibitor PLX4032 exhibit an increase in actin stress fiber formation, which appears to promote the nuclear accumulation of YAP/TAZ. Knockdown of YAP/TAZ reduces the viability of resistant melanoma cells, whereas overexpression of constitutively active YAP induces resistance. Moreover, inhibition of actin polymerization and actomyosin tension in melanoma cells suppresses both YAP/TAZ activation and PLX4032 resistance. Our siRNA library screening identifies actin dynamics regulator TESK1 as a novel vulnerable point of the YAP/TAZ-dependent resistance pathway. These results suggest that inhibition of actin remodeling is a potential strategy to suppress resistance in BRAF inhibitor therapies.

  5. Exosomes derived from human mesenchymal stem cells confer drug resistance in gastric cancer.

    Science.gov (United States)

    Ji, Runbi; Zhang, Bin; Zhang, Xu; Xue, Jianguo; Yuan, Xiao; Yan, Yongmin; Wang, Mei; Zhu, Wei; Qian, Hui; Xu, Wenrong

    2015-08-01

    Mesenchymal stem cells (MSCs) play an important role in chemoresistance. Exosomes have been reported to modify cellular phenotype and function by mediating cell-cell communication. In this study, we aimed to investigate whether exosomes derived from MSCs (MSC-exosomes) are involved in mediating the resistance to chemotherapy in gastric cancer and to explore the underlying molecular mechanism. We found that MSC-exosomes significantly induced the resistance of gastric cancer cells to 5-fluorouracil both in vivo and ex vivo. MSC-exosomes antagonized 5-fluorouracil-induced apoptosis and enhanced the expression of multi-drug resistance associated proteins, including MDR, MRP and LRP. Mechanistically, MSC-exosomes triggered the activation of calcium/calmodulin-dependent protein kinases (CaM-Ks) and Raf/MEK/ERK kinase cascade in gastric cancer cells. Blocking the CaM-Ks/Raf/MEK/ERK pathway inhibited the promoting role of MSC-exosomes in chemoresistance. Collectively, MSC-exosomes could induce drug resistance in gastric cancer cells by activating CaM-Ks/Raf/MEK/ERK pathway. Our findings suggest that MSC-exosomes have profound effects on modifying gastric cancer cells in the development of drug resistance. Targeting the interaction between MSC-exosomes and cancer cells may help improve the efficacy of chemotherapy in gastric cancer.

  6. Transient elevation of glycolysis confers radio-resistance by facilitating DNA repair in cells

    OpenAIRE

    Bhatt, Anant Narayan; Chauhan, Ankit; Khanna, Suchit; Rai, Yogesh; Singh, Saurabh; Soni, Ravi; Kalra, Namita; Bilikere S Dwarakanath

    2015-01-01

    Background Cancer cells exhibit increased glycolysis for ATP production (the Warburg effect) and macromolecular biosynthesis; it is also linked with therapeutic resistance that is generally associated with compromised respiratory metabolism. Molecular mechanisms underlying radio-resistance linked to elevated glycolysis remain incompletely understood. Methods We stimulated glycolysis using mitochondrial respiratory modifiers (MRMs viz. di-nitro phenol, DNP; Photosan-3, PS3; Methylene blue, MB)...

  7. Transient elevation of glycolysis confers radio-resistance by facilitating DNA repair in cells

    International Nuclear Information System (INIS)

    Cancer cells exhibit increased glycolysis for ATP production (the Warburg effect) and macromolecular biosynthesis; it is also linked with therapeutic resistance that is generally associated with compromised respiratory metabolism. Molecular mechanisms underlying radio-resistance linked to elevated glycolysis remain incompletely understood. We stimulated glycolysis using mitochondrial respiratory modifiers (MRMs viz. di-nitro phenol, DNP; Photosan-3, PS3; Methylene blue, MB) in established human cell lines (HEK293, BMG-1 and OCT-1). Glucose utilization and lactate production, levels of glucose transporters and glycolytic enzymes were investigated as indices of glycolysis. Clonogenic survival, DNA repair and cytogenetic damage were studied as parameters of radiation response. MRMs induced the glycolysis by enhancing the levels of two important regulators of glucose metabolism GLUT-1 and HK-II and resulted in 2 fold increase in glucose consumption and lactate production. This increase in glycolysis resulted in resistance against radiation-induced cell death (clonogenic survival) in different cell lines at an absorbed dose of 5 Gy. Inhibition of glucose uptake and glycolysis (using fasentin, 2-deoxy-D-glucose and 3-bromopyruvate) in DNP treated cells failed to increase the clonogenic survival of irradiated cells, suggesting that radio-resistance linked to inhibition of mitochondrial respiration is glycolysis dependent. Elevated glycolysis also facilitated rejoining of radiation-induced DNA strand breaks by activating both non-homologous end joining (NHEJ) and homologous recombination (HR) pathways of DNA double strand break repair leading to a reduction in radiation-induced cytogenetic damage (micronuclei formation) in these cells. These findings suggest that enhanced glycolysis generally observed in cancer cells may be responsible for the radio-resistance, partly by enhancing the repair of DNA damage

  8. STAT6 Activation Confers upon T Helper Cells Resistance to Suppression by Regulatory T Cells

    NARCIS (Netherlands)

    Pillemer, Brendan B. L.; Qi, Zengbiao; Melgert, Barbro; Oriss, Timothy B.; Ray, Prabir; Ray, Anuradha

    2009-01-01

    Recent studies have highlighted characteristics of T regulatory cells (Tregs) that underlie their suppressive function. However, mechanisms that override their suppressive function in the context of an adaptive immune response are not well understood. In the lungs of mice undergoing allergic inflamm

  9. Glioma cell VEGFR-2 confers resistance to chemotherapeutic and antiangiogenic treatments in PTEN-deficient glioblastoma.

    Science.gov (United States)

    Kessler, Tobias; Sahm, Felix; Blaes, Jonas; Osswald, Matthias; Rübmann, Petra; Milford, David; Urban, Severino; Jestaedt, Leonie; Heiland, Sabine; Bendszus, Martin; Hertenstein, Anne; Pfenning, Philipp-Niclas; Ruiz de Almodóvar, Carmen; Wick, Antje; Winkler, Frank; von Deimling, Andreas; Platten, Michael; Wick, Wolfgang; Weiler, Markus

    2015-10-13

    Loss of the tumor suppressor phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a prerequisite for tumor cell-specific expression of vascular endothelial growth factor receptor (VEGFR)-2 in glioblastoma defining a subgroup prone to develop evasive resistance towards antiangiogenic treatments. Immunohistochemical analysis of human tumor tissues showed VEGFR-2 expression in glioma cells in 19% of specimens examined, mainly in the infiltration zone. Glioma cell VEGFR-2 positivity was restricted to PTEN-deficient tumor specimens. PTEN overexpression reduced VEGFR-2 expression in vitro, as well as knock-down of raptor or rictor. Genetic interference with VEGFR-2 revealed proproliferative, antiinvasive and chemoprotective functions for VEGFR-2 in glioma cells. VEGFR-2-dependent cellular effects were concomitant with activation of 'kappa-light-chain-enhancer' of activated B-cells, protein kinase B, and N-myc downstream regulated gene 1. Two-photon in vivo microscopy revealed that expression of VEGFR-2 in glioma cells hampers antiangiogenesis. Bevacizumab induces a proinvasive response in VEGFR-2-positive glioma cells. Patients with PTEN-negative glioblastomas had a shorter survival after initiation of bevacizumab therapy compared with PTEN-positive glioblastomas. Conclusively, expression of VEGFR-2 in glioma cells indicates an aggressive glioblastoma subgroup developing early resistance to temozolomide or bevacizumab. Loss of PTEN may serve as a biomarker identifying those tumors upfront by routine neuropathological methods.

  10. Retroviral transfer of a murine cDNA for multidrug resistance confers pleiotropic drug resistance to cells without prior drug selection

    International Nuclear Information System (INIS)

    The authors have constructed a retrovirus expression vector that carries the murine mdr cDNA transcribed under the control of the human H4 histone promoter to examine the feasibility of efficiently transferring a multidrug resistance phenotype to cells without requiring drug selection. This approach will facilitate the transfer of mdr cDNA to hematopoietic progenitor cells for the study of multidrug resistance in vivo. The retrovirus vector pHmdr has been used for transmission and expression of the mdr cDNA in initially drug-sensitive NIH 3T3 fibroblasts. Selection of pHmdr infectants in the cytotoxic agents colchicine or doxorubicin gave rise to highly multidrug-resistant colonies containing a single gene copy of the vector. Moreover, in the analysis of 12 cloned unselected NIH 3T3 cell infectants, a multidrug resistance phenotype was conferred by as few as two copies of the pHmdr vector. Overexpression of the mdr cDNA in drug-selected and unselected pHmdr infectants was directly related to cell survival in three cytotoxic agents tested. These results hold significant implications for the study of multidrug resistance in vivo

  11. Inhibition of TGF-β signaling in normal lung epithelial cells confers resistance to ionizing radiation

    Science.gov (United States)

    Reeves, Anna; Zagurovskaya, Marianna; Gupta, Seema; Shareef, Mohammed M.; Mohiuddin, Mohammed; Ahmed, Mansoor M.

    2007-01-01

    Purpose To address the functional role of radiation-induced TGF-β signaling in normal epithelial background, we selected spontaneously immortalized lung epithelial cell line derived from the normal lung tissue of dominant-negative mutant of TGF-β RII (ΔRII) transgenic mouse that expressed conditionally ΔRII under the control of metallothionein promoter (MT-1) and assessed it's impact on radio-sensitivity. Method and Materials Spontaneously immortalized lung epithelial cell culture (SILECC) was established and all analyses were performed within 50 passages. Colony-forming and TUNEL assays were used to assess the clonogenic inhibition and apoptosis respectively. Western blot analysis was performed to assess the kinetics of p21, bax and RII proteins. TGF-β responsive promoter activity was measured using dual-luciferase reporter assay. Results Exposure to ZnSO4 inhibited TGF-β signaling induced either by recombinant TGF-β1 or ionizing radiation. SILECC treated either with ZnSO4 or neutralizing antibody against TGF-β showed a significant increase in radio-resistance when compared to untreated cells. Furthermore, the expression of the ΔRII inhibited the radiation-induced up-regulation of the TGF-β effector gene p21waf1/cip1.. Conclusions Our findings imply that inhibition of radiation-induced TGF-β signaling via abrogation of RII function enhances radio-resistance of the normal lung epithelial cells, and this can be directly attributed to the loss of TGF-β signaling function. PMID:17448872

  12. 14-3-3σ confers cisplatin resistance in esophageal squamous cell carcinoma cells via regulating DNA repair molecules.

    Science.gov (United States)

    Lai, Kenneth K Y; Chan, Kin Tak; Choi, Mei Yuk; Wang, Hector K; Fung, Eva Y M; Lam, Ho Yu; Tan, Winnie; Tung, Lai Nar; Tong, Daniel K H; Sun, Raymond W Y; Lee, Nikki P; Law, Simon

    2016-02-01

    Esophageal squamous cell carcinoma (ESCC) is the predominant type of esophageal cancer in Asia. Cisplatin is commonly used in chemoradiation for unresectable ESCC patients. However, the treatment efficacy is diminished in patients with established cisplatin resistance. To understand the mechanism leading to the development of cisplatin resistance in ESCC, we compared the proteomes from a cisplatin-resistant HKESC-2R cell line with its parental-sensitive counterpart HKESC-2 to identify key molecule involved in this process. Mass spectrometry analysis detected 14-3-3σ as the most abundant molecule expressed exclusively in HKESC-2R cells, while western blot result further validated it to be highly expressed in HKESC-2R cells when compared to HKESC-2 cells. Ectopic expression of 14-3-3σ increased cisplatin resistance in HKESC-2 cells, while its suppression sensitized SLMT-1 cells to cisplatin. Among the molecules involved in drug detoxification, drug transportation, and DNA repair, the examined DNA repair molecules HMGB1 and XPA were found to be highly expressed in HKESC-2R cells with high 14-3-3σ expression. Subsequent manipulation of 14-3-3σ by both overexpression and knockdown approaches concurrently altered the expression of HMGB1 and XPA. 14-3-3σ, HMGB1, and XPA were preferentially expressed in cisplatin-resistant SLMT-1 cells when compared to those more sensitive to cisplatin. In ESCC patients with poor response to cisplatin-based chemoradiation, their pre-treatment tumors expressed higher expression of HMGB1 than those with response to such treatment. In summary, our results demonstrate that 14-3-3σ induces cisplatin resistance in ESCC cells and that 14-3-3σ-mediated cisplatin resistance involves DNA repair molecules HMGB1 and XPA. Results from this study provide evidences for further work in researching the potential use of 14-3-3σ and DNA repair molecules HMGB1 and XPA as biomarkers and therapeutic targets for ESCC.

  13. Pancreatic adenocarcinoma upregulated factor (PAUF) confers resistance to pancreatic cancer cells against oncolytic parvovirus H-1 infection through IFNA receptor-mediated signaling

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    Kaowinn, Sirichat; Cho, Il-Rae; Moon, Jeong; Jun, Seung Won; Kim, Chang Seok [BK21+, Department of Cogno-Mechatronics Engineering, Pusan National University, Busan 609-736 (Korea, Republic of); Kang, Ho Young [Department of Microbiology, Pusan National University, Busan 609-736 (Korea, Republic of); Kim, Manbok [Department of Medical Science, Dankook University College of Medicine, Cheonan 330-714 (Korea, Republic of); Koh, Sang Seok [Department of Biological Sciences, Dong-A University, Busan 604-714 (Korea, Republic of); Chung, Young-Hwa, E-mail: younghc@pusan.ac.kr [BK21+, Department of Cogno-Mechatronics Engineering, Pusan National University, Busan 609-736 (Korea, Republic of)

    2015-04-03

    Pancreatic adenocarcinoma upregulated factor (PAUF), a novel oncogene, plays a crucial role in the development of pancreatic cancer, including its metastasis and proliferation. Therefore, PAUF-expressing pancreatic cancer cells could be important targets for oncolytic virus-mediated treatment. Panc-1 cells expressing PAUF (Panc-PAUF) showed relative resistance to parvovirus H-1 infection compared with Panc-1 cells expressing an empty vector (Panc-Vec). Of interest, expression of type I IFN-α receptor (IFNAR) was higher in Panc-PAUF cells than in Panc-Vec cells. Increased expression of IFNAR in turn increased the activation of Stat1 and Tyk2 in Panc-PAUF cells compared with that in Panc-Vec cells. Suppression of Tyk2 and Stat1, which are important downstream molecules for IFN-α signaling, sensitized pancreatic cancer cells to parvovirus H-1-mediated apoptosis. Further, constitutive suppression of PAUF sensitized Bxpc3 pancreatic cancer cells to parvovirus H-1 infection. Taken together, these results suggested that PAUF conferred resistance to pancreatic cancer cells against oncolytic parvovirus H-1 infection through IFNAR-mediated signaling. - Highlights: • PAUF confers resistance against oncolytic parvovirus H-1 infection. • PAUF enhances the expression of IFNAR in Panc-1 cells. • Increased activation of Tyk2 or Stat1 by PAUF provides resistance to parvovirus H-1-mediated apoptosis. • Constitutive inhibition of PAUF enhances parvovirus H-1-mediated oncolysis of Bxpc3 pancreatic cancer cells.

  14. Pancreatic adenocarcinoma upregulated factor (PAUF) confers resistance to pancreatic cancer cells against oncolytic parvovirus H-1 infection through IFNA receptor-mediated signaling

    International Nuclear Information System (INIS)

    Pancreatic adenocarcinoma upregulated factor (PAUF), a novel oncogene, plays a crucial role in the development of pancreatic cancer, including its metastasis and proliferation. Therefore, PAUF-expressing pancreatic cancer cells could be important targets for oncolytic virus-mediated treatment. Panc-1 cells expressing PAUF (Panc-PAUF) showed relative resistance to parvovirus H-1 infection compared with Panc-1 cells expressing an empty vector (Panc-Vec). Of interest, expression of type I IFN-α receptor (IFNAR) was higher in Panc-PAUF cells than in Panc-Vec cells. Increased expression of IFNAR in turn increased the activation of Stat1 and Tyk2 in Panc-PAUF cells compared with that in Panc-Vec cells. Suppression of Tyk2 and Stat1, which are important downstream molecules for IFN-α signaling, sensitized pancreatic cancer cells to parvovirus H-1-mediated apoptosis. Further, constitutive suppression of PAUF sensitized Bxpc3 pancreatic cancer cells to parvovirus H-1 infection. Taken together, these results suggested that PAUF conferred resistance to pancreatic cancer cells against oncolytic parvovirus H-1 infection through IFNAR-mediated signaling. - Highlights: • PAUF confers resistance against oncolytic parvovirus H-1 infection. • PAUF enhances the expression of IFNAR in Panc-1 cells. • Increased activation of Tyk2 or Stat1 by PAUF provides resistance to parvovirus H-1-mediated apoptosis. • Constitutive inhibition of PAUF enhances parvovirus H-1-mediated oncolysis of Bxpc3 pancreatic cancer cells

  15. Elevated Cell Wall Chitin in Candida albicans Confers Echinocandin Resistance In Vivo

    OpenAIRE

    Lee, K K; MacCallum, D.M; Jacobsen, M.D.; Walker, L A; Odds, F C; Gow, N. A. R.; Munro, C.A.

    2012-01-01

    Candida albicans cells with increased cell wall chitin have reduced echinocandin susceptibility in vitro. The aim of this study was to investigate whether C. albicans cells with elevated chitin levels have reduced echinocandin susceptibility in vivo. BALB/c mice were infected with C. albicans cells with normal chitin levels and compared to mice infected with high-chitin cells. Caspofungin therapy was initiated at 24 h postinfection. Mice infected with chitin-normal cells were successfully tre...

  16. Resistance to intestinal Entamoeba histolytica infection is conferred by innate immunity and Gr-1+ cells.

    Science.gov (United States)

    Asgharpour, Amon; Gilchrist, Carol; Baba, Duza; Hamano, Shinjiro; Houpt, Eric

    2005-08-01

    Establishment of intestinal infection with Entamoeba histolytica depends on the mouse strain; C57BL/6 mice are highly resistant, and C3H/HeJ mice are relatively susceptible. We found that resistance to intestinal infection was independent of lymphocyte activity or H-2 haplotype and occurred in the first hours to days postchallenge according to in vivo imaging. At 18 h postchallenge, the ceca of resistant C57BL/6 mice were histologically unremarkable, in contrast to the severe inflammation observed in susceptible C3H/HeJ mice. Comparison of cecal gene expression in C3H/HeJ and C57BL/6 mice demonstrated that there was parasite-induced upregulation of proinflammatory and neutrophil chemotaxis transcripts and there was downregulation of transforming growth factor beta signaling molecules. Pretreatment with dexamethasone abrogated the partial resistance of C3H/HeJ or CBA mice through an innate, lymphocyte-independent mechanism, but it had no effect on the high-level resistance of C57BL/6 mice. Similarly, administration of a neutrophil-depleting anti-Gr-1 monoclonal antibody (RB6-8C5) decreased the partial resistance of CBA mice and led to severe pathology compared to control antibody-treated mice, but it had no effect on C57BL/6 resistance. These data indicate that there are discrete mechanisms of innate resistance to E. histolytica depending on the host background and, in contrast to other reports, imply that neutrophils are protective and not damaging in intestinal amebiasis.

  17. Connexin43 confers Temozolomide resistance in human glioma cells by modulating the mitochondrial apoptosis pathway

    NARCIS (Netherlands)

    Gielen, P.R.; Aftab, Q.; Ma, N.; Chen, V.C.; Hong, X.; Lozinsky, S.; Naus, C.C.; Sin, W.C.

    2013-01-01

    Glioblastoma multiforme (GBM) is the most aggressive astrocytoma, and therapeutic options are generally limited to surgical resection, radiotherapy, and Temozolomide (TMZ) chemotherapy. TMZ is a DNA alkylating agent that causes DNA damage and induces cell death. Unfortunately, glioma cells often dev

  18. Activating Transcription Factor 4 Confers a Multidrug Resistance Phenotype to Gastric Cancer Cells through Transactivation of SIRT1 Expression

    OpenAIRE

    Hongwu Zhu; Limin Xia; Yongguo Zhang; Honghong Wang; Wenjing Xu; Hao Hu; Jing Wang; Jing Xin; Yi Gang; Sumei Sha; Bin Xu; Daiming Fan; Yongzhan Nie; Kaichun Wu

    2012-01-01

    BACKGROUND: Multidrug resistance (MDR) in gastric cancer remains a major challenge to clinical treatment. Activating transcription factor 4 (ATF4) is a stress response gene involved in homeostasis and cellular protection. However, the expression and function of ATF4 in gastric cancer MDR remains unknown. In this study, we investigate whether ATF4 play a role in gastric cancer MDR and its potential mechanisms. METHODOLOGY/PRINCIPAL FINDINGS: We demonstrated that ATF4 overexpression confered th...

  19. The targeted inhibition of mitochondrial Hsp90 overcomes the apoptosis resistance conferred by Bcl-2 in Hep3B cells via necroptosis

    International Nuclear Information System (INIS)

    Previous studies have reported that a Gamitrinib variant containing triphenylphosphonium (G-TPP) binds to mitochondrial Hsp90 and rapidly inhibits its activity, thus inducing the apoptotic pathway in the cells. Accordingly, G-TPP shows a potential as a promising drug for the treatment of cancer. A cell can die from different types of cell death such as apoptosis, necrosis, necroptosis, and autophagic cell death. In this study, we further investigated the mechanisms and modes of cell death in the G-TPP-treated Hep3B and U937 cell lines. We discovered that G-TPP kills the U937 cells through the apoptotic pathway and the overexpression of Bcl-2 significantly inhibits U937 cell death to G-TPP. We further discovered that G-TPP kills the Hep3B cells by activating necroptosis in combination with the partial activation of caspase-dependent apoptosis. Importantly, G-TPP overcomes the apoptosis resistance conferred by Bcl-2 in Hep3B cells via necroptosis. We also observed that G-TPP induces compensatory autophagy in the Hep3B cell line. We further found that whereas there is a Bcl-2-Beclin 1 interaction in response to G-TPP, silencing the beclin 1 gene failed to block LC3-II accumulation in the Hep3B cells, indicating that G-TPP triggers Beclin 1-independent protective autophagy in Hep3B cells. Taken together, these data reveal that G-TPP induces cell death through a combination of death pathways, including necroptosis and apoptosis, and overcomes the apoptosis resistance conferred by Bcl-2 in Hep3B cells via necroptosis. These findings are important for the therapeutic exploitation of necroptosis as an alternative cell death program to bypass the resistance to apoptosis. Highlights: ► G-TPP binds to mitochondrial Hsp90. ► G-TPP induces apoptosis in U937 human leukemia cancer cells. ► G-TPP induces combination of death pathways in Hep3B cell. ► G-TPP overcomes the resistance conferred by Bcl-2 in Hep3B cells via necroptosis. ► G-TPP triggers Beclin 1-independent

  20. Pancreatic adenocarcinoma upregulated factor (PAUF) confers resistance to pancreatic cancer cells against oncolytic parvovirus H-1 infection through IFNA receptor-mediated signaling.

    Science.gov (United States)

    Kaowinn, Sirichat; Cho, Il-Rae; Moon, Jeong; Jun, Seung Won; Kim, Chang Seok; Kang, Ho Young; Kim, Manbok; Koh, Sang Seok; Chung, Young-Hwa

    2015-04-01

    Pancreatic adenocarcinoma upregulated factor (PAUF), a novel oncogene, plays a crucial role in the development of pancreatic cancer, including its metastasis and proliferation. Therefore, PAUF-expressing pancreatic cancer cells could be important targets for oncolytic virus-mediated treatment. Panc-1 cells expressing PAUF (Panc-PAUF) showed relative resistance to parvovirus H-1 infection compared with Panc-1 cells expressing an empty vector (Panc-Vec). Of interest, expression of type I IFN-α receptor (IFNAR) was higher in Panc-PAUF cells than in Panc-Vec cells. Increased expression of IFNAR in turn increased the activation of Stat1 and Tyk2 in Panc-PAUF cells compared with that in Panc-Vec cells. Suppression of Tyk2 and Stat1, which are important downstream molecules for IFN-α signaling, sensitized pancreatic cancer cells to parvovirus H-1-mediated apoptosis. Further, constitutive suppression of PAUF sensitized Bxpc3 pancreatic cancer cells to parvovirus H-1 infection. Taken together, these results suggested that PAUF conferred resistance to pancreatic cancer cells against oncolytic parvovirus H-1 infection through IFNAR-mediated signaling.

  1. Pancreatic adenocarcinoma upregulated factor (PAUF) confers resistance to pancreatic cancer cells against oncolytic parvovirus H-1 infection through IFNA receptor-mediated signaling.

    Science.gov (United States)

    Kaowinn, Sirichat; Cho, Il-Rae; Moon, Jeong; Jun, Seung Won; Kim, Chang Seok; Kang, Ho Young; Kim, Manbok; Koh, Sang Seok; Chung, Young-Hwa

    2015-04-01

    Pancreatic adenocarcinoma upregulated factor (PAUF), a novel oncogene, plays a crucial role in the development of pancreatic cancer, including its metastasis and proliferation. Therefore, PAUF-expressing pancreatic cancer cells could be important targets for oncolytic virus-mediated treatment. Panc-1 cells expressing PAUF (Panc-PAUF) showed relative resistance to parvovirus H-1 infection compared with Panc-1 cells expressing an empty vector (Panc-Vec). Of interest, expression of type I IFN-α receptor (IFNAR) was higher in Panc-PAUF cells than in Panc-Vec cells. Increased expression of IFNAR in turn increased the activation of Stat1 and Tyk2 in Panc-PAUF cells compared with that in Panc-Vec cells. Suppression of Tyk2 and Stat1, which are important downstream molecules for IFN-α signaling, sensitized pancreatic cancer cells to parvovirus H-1-mediated apoptosis. Further, constitutive suppression of PAUF sensitized Bxpc3 pancreatic cancer cells to parvovirus H-1 infection. Taken together, these results suggested that PAUF conferred resistance to pancreatic cancer cells against oncolytic parvovirus H-1 infection through IFNAR-mediated signaling. PMID:25727013

  2. Retroviral transfer of a murine cDNA for multidrug resistance confers pleiotropic drug resistance to cells without prior drug selection.

    OpenAIRE

    Guild, B C; Mulligan, R C; Gros, P.; Housman, D.E.

    1988-01-01

    We have constructed a retrovirus expression vector that carries the murine mdr cDNA transcribed under the control of the human H4 histone promoter to examine the feasibility of efficiently transferring a multidrug resistance phenotype to cells without requiring drug selection. This approach will facilitate the transfer of mdr cDNA to hematopoietic progenitor cells for the study of multidrug resistance in vivo. The retrovirus vector pHmdr has been used for transmission and expression of the md...

  3. Identification and analysis of CD133(+) melanoma stem-like cells conferring resistance to taxol: An insight into the mechanisms of their resistance and response.

    Science.gov (United States)

    El-Khattouti, Abdelouahid; Selimovic, Denis; Haïkel, Youssef; Megahed, Mosaad; Gomez, Christian R; Hassan, Mohamed

    2014-02-01

    The presence and the involvement of cancer stem-like cells (CSCs) in tumor initiation and progression, and chemo-resistance are documented. Herein, we functionally analyzed melanoma stem-like cells (MSC)/CD133(+) cells on their resistance and response to taxol-induced apoptosis. Besides being taxol resistant, the CD133(+) cells demonstrated a growth advantage over the CD133(-) subpopulation. Taxol induced apoptosis on CD133(-) cells, but not on CD133(+) cells. In the CD133(-) subpopulation, the exposure to taxol induced the activation of apoptosis signal-regulating kinase1 (ASK1)/c-jun-N-terminal kinase (JNK), p38, extracellular signal regulated kinase (ERK) pathways and Bax expression, while in CD133(+) cells taxol was able only to enhance the activity of the ERK pathway. In CD133(+) cells, the direct gene transfer of Bax overcame the acquired resistance to taxol. Taken together, our data provide an insight into the mechanistic cascade of melanoma resistance to taxol and suggest Bax gene transfer as a complementary approach to chemotherapy.

  4. CIAPIN1 confers multidrug resistance through up-regulation of MDR-1 and Bcl-L in LoVo/Adr cells and is independent of p53.

    Science.gov (United States)

    Zhang, Ya-Fei; Li, Xiao-Hua; Shi, Yong-Quan; Wu, Yu-Yun; Li, Ning; He, Qiang; Ji, Qing; Wang, Rong-Quan; Yang, Shi-Ming; Fang, Dian-Chun

    2011-04-01

    Recent investigations discovered that CIAPIN1 might be another drug resistance-associated molecule in cancer cells. However, the underlying mechanisms of CIAPIN1-related multidrug resistance (MDR) remain elusive. In the present study, we investigated the role and possible mechanisms of CIAPIN1 in MDR of human colon carcinoma LoVo/Adr cells which express the wild-type p53 gene. By using small interference RNA and gene transfection techniques, we found that knockdown of CIAPIN1 expression re-sensitized LoVo/Adr cells to anti-cancer drugs and up-regulation of CIAPIN1 in sensitive LoVo cells resulted in a distinct MDR phenotype. We further revealed that CIAPIN1 conferred the MDR phenotype in LoVo/Adr cells through up-regulating expression of MDR-1 (P-gp) and Bcl-xL. Finally, by analyzing the effect of inactivation of wild-type p53 on CIAPIN1-induced up-regulation of P-gp and Bcl-xL, we determined that CIAPIN1 could exhibit its MDR-related function independently of the p53 signaling pathway. Overall, the results presented here further suggest that over-expression of CIAPIN1 is an important mechanism of drug resistance in human cancers, even if not the sole one.

  5. Dysbiosis caused by vitamin D receptor deficiency confers colonization resistance to Citrobacter rodentium through modulation of innate lymphoid cells.

    Science.gov (United States)

    Chen, J; Waddell, A; Lin, Y-D; Cantorna, M T

    2015-05-01

    Vitamin D receptor (VDR) knockout (KO) mice had fewer Citrobacter rodentium in the feces than wild-type (WT) mice and the kinetics of clearance was faster in VDR KO than WT mice. VDR KO mice had more interleukin-22 (IL-22)-producing innate lymphoid cells (ILCs) and more antibacterial peptides than WT mice. The increased ILCs in the VDR KO mice was a cell-autonomous effect of VDR deficiency on ILC frequencies. Bone marrow (BM) transplantation from VDR KO mice into WT resulted in higher ILCs and colonization resistance of the WT mice. Disruption of the gut microbiota using antibiotics in VDR KO mice reversed colonization resistance to C. rodentium infection. Confirming the role of the microbiota in the colonization resistance of VDR KO mice, transfer of the VDR KO microbiota to WT germ-free mice resulted in colonization resistance. Once colonization resistance was overcome, VDR KO mice had increased susceptibility to C. rodentium. VDR expression is a regulator of ILC frequencies, IL-22, dysbiosis, and C. rodentium susceptibility.

  6. Rice RING protein OSBBI1 with E3 ligase activity confers broad-spectrum resistance against Magnaporthe oryzae by modifying the cell wall defence

    Institute of Scientific and Technical Information of China (English)

    Wei Li; Zuhua He; Sihui Zhong; Guojun Li; Qun Li; Bizeng Mao; Yiwen Deng; Huijuan Zhang; Longjun Zeng; Fengming Song

    2011-01-01

    Emerging evidence suggests that E3 ligases play critical roles in diverse biological processes, including innate immune responses in plants. However, the mechanism of the E3 ligase involvement in plant innate immunity is unclear.We report that a rice gene, OsBBI1, encoding a RING finger protein with E3 ligase activity, mediates broad-spectrum disease resistance. The expression of OSBBI1 was induced by rice blast fungus Magnaporthe oryzae, as well as chemical inducers, benzothiadiazole and salicylic acid. Biochemical analysis revealed that OsBBI1 protein possesses E3ubiquitin ligase activity in vitro. Genetic analysis revealed that the loss of OsBBI1 function in a Tos17-insertion line increased susceptibility, while the overexpression of OsBBI1 in transgenic plants conferred enhanced resistance to multiple races of M.oryzae. This indicates that OsBBI1 modulates broad-spectrum resistance against the blast fungus. The OsBBII-overexpressing plants showed higher levels of H,O, accumulation in cells and higher levels of phenolic compounds and cross-linking of proteins in cell walls at infection sites by M. Oryzae compared with wild-type(WT)plants. The cell walls were thicker in the OsBB11-overexpressing plants and thinner in the mutant plants than in the WT plants. Our results suggest that OsBBH modulates broad-spectrum resistance to blast fungus by modifying cell wall defence responses. The functional characterization of OsBBI1 provides insight into the E3 ligase-mediated innate immunity, and a practical tool for constructing broad-spectrum resistance against the most destructive disease in rice.

  7. Up-regulation of Hsp27 by ERα/Sp1 facilitates proliferation and confers resistance to apoptosis in human papillary thyroid cancer cells.

    Science.gov (United States)

    Mo, Xiao-Mei; Li, Li; Zhu, Ping; Dai, Yu-Jie; Zhao, Ting-Ting; Liao, Ling-Yao; Chen, George G; Liu, Zhi-Min

    2016-08-15

    17β-estradiol (E2) has been suggested to play a role in the development and progression of papillary thyroid cancer. Heat shock protein 27 (Hsp27) is a member of the Hsp family that is responsible for cell survival under stressful conditions. Previous studies have shown that the 5'-promoter region of Hsp27 gene contains a specificity protein-1 (Spl) and estrogen response element half-site (ERE-half), which contributes to Hsp27 induction by E2 in breast cancer cells. However, it is unclear whether Hsp27 can be up-regulated by E2 and which estrogen receptor (ER) isoform and tethered transcription factor are involved in this regulation in papillary thyroid cancer cells. In the present study, we demonstrated that Hsp27 can be effectively up-regulated by E2 at mRNA and protein levels in human K1 and BCPAP papillary thyroid cancer cells which have more than two times higher level of ERα than that of ERβ. The up-regulation of Hsp27 by E2 is mediated by ERα/Sp1 and ERβ has repressive effect on this ERα/Sp1-mediated up-regulation of Hsp27. Moreover, we showed that the up-regulation of Hsp27 by ERα/Sp1 facilitates proliferation and confers resistance to apoptosis through interaction with procaspase-3. Targeting this pathway may be a potential strategy for therapy of papillary thyroid cancer. PMID:27179757

  8. Chromosomal Instability Confers Intrinsic Multidrug Resistance

    DEFF Research Database (Denmark)

    Lee, Alvin J. X.; Endesfelder, David; Rowan, Andrew J.;

    2011-01-01

    their diploid parental cells only with increasing chromosomal heterogeneity and isogenic cell line models of CIN+ displayed multidrug resistance relative to their CIN- parental cancer cell line derivatives. In a meta-analysis of CRC outcome following cytotoxic treatment, CIN+ predicted worse progression...

  9. Heterologously expressed bacterial and human multidrug resistance proteins confer cadmium resistance to Escherichia coli

    OpenAIRE

    Achard-Joris, M; van Saparoea, HBV; Driessen, AJM; Bourdineaud, JP; Bourdineaud, Jean-Paul

    2005-01-01

    The human MDR1 gene is induced by cadmium exposure although no resistance to this metal is observed in human cells overexpressing hMDR1. To access the role of MDR proteins in cadmium resistance, human MDR1, Lactococcus lactis lmrA, and Oenococcus oeni omrA were expressed in an Escherichia coli tolC mutant strain which proved to be hypersensitive to cadmium. Both the human and bacterial MDR genes conferred cadmium resistance to E. coli up to 0.4 mM concentration. Protection was abolished by 10...

  10. Baculovirus-mediated Expression of p35 Confers Resistance to Apoptosis in Human Embryo Kidney 293 cells

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Baculovirus has many advantages as vectors for gene transfer. We demonstrated that recombinant baculovirus vectors expressing p35 (Ac-CMV-p35) and eGFP (Ac-CMV-GFP) could be transduced into human kidney 293 cells efficiently. The level of transgene expression was viral dose dependent and high-level expression of the target gene could be achieved under the heterogonous promoter. MTT assay suggested that both Ac-CMV-p35 and Ac-CMV-GFP did not have cytotoxic effect on human embryo kidney 293 cells. Cell growth curve showed the Ac-CMV-p35 and Ac- CMV-GFP transduced and non-transduced cells had similar proliferation rate, so baculovirus-mediated p35expression had no adverse effect on cell proliferation. In addition, baculovirus-mediated p35 gene expression protected human embryo kidney 293 cells against apoptosis induced by various apoptosis inducers such as Actinomycin D, UV or serum-free media. These results suggested that the baculovirus vector mediated p35 gene expression was functional and it could be widely used in molecular research and even gene therapy.

  11. Elevated STAT3 Signaling-Mediated Upregulation of MMP-2/9 Confers Enhanced Invasion Ability in Multidrug-Resistant Breast Cancer Cells

    Directory of Open Access Journals (Sweden)

    Fei Zhang

    2015-10-01

    Full Text Available The development of multidrug resistance greatly impedes effective cancer therapy. Recent advances in cancer research have demonstrated that acquisition of multidrug resistance by cancer cells is usually accompanied by enhanced cell invasiveness. Several lines of evidence indicated that cross activation of other signaling pathways during development of drug resistance may increase invasive potential of multidrug-resistant (MDR cancer cells. However, the accurate mechanism of this process is largely undefined. In this study, to better understand the associated molecular pathways responsible for cancer progression induced by drug resistance, a MDR human breast cancer cell line SK-BR-3/EPR with P-glycoprotein overexpression was established using stepwise long-term exposure to increasing concentration of epirubicin. The SK-BR-3/EPR cell line exhibited decreased cell proliferative activity, but enhanced cell invasive capacity. We showed that the expression of metastasis-related matrix metalloproteinase (MMP-2/9 was elevated in SK-BR-3/EPR cells. Moreover, SK-BR-3/EPR cells showed elevated activation of STAT3. Activation of STAT3 signaling is responsible for enhanced invasiveness of SK-BR-3/EPR cells through upregulation of MMP-2/9. STAT3 is a well-known oncogene and is frequently implicated in tumorigenesis and chemotherapeutic resistance. Our findings augment insight into the mechanism underlying the functional association between MDR and cancer invasiveness.

  12. miR-222 confers the resistance of breast cancer cells to Adriamycin through suppression of p27(kip1) expression.

    Science.gov (United States)

    Wang, Dan-Dan; Li, Jian; Sha, Huan-Huan; Chen, Xiu; Yang, Su-Jin; Shen, Hong-Yu; Zhong, Shan-Liang; Zhao, Jian-Hua; Tang, Jin-Hai

    2016-09-15

    Adriamycin (Adr) is a potent chemotherapeutic agent for chemotherapy of breast cancer patients. Despite impressive initial clinical responses, some developed drug resistance to Adr-based therapy and the mechanisms underlying breast cancer cells resistance to Adr are not well known. In our previous study, in vitro, we verified that miR-222 was upregulated in Adr-resistant breast cancer cells (MCF-7/Adr) compared with the sensitive parental cells (MCF-7/S). Here, miR-222 inhibitors or mimics were transfected into MCF-7 cell lines. RT-qPCR and western blot were used to detect the expression of p27(kip1). Immunofluorescence showed that miR-222 altered the subcellular location of p27(kip1) in nucleus. MTT was employed to verify the sensitivity of breast cancer cell lines to Adr. Flow cytometry showed the apoptosis and cell cycles of the cells after adding Adr. The results showed that downregulation of miR-222 in MCF-7/Adr increased sensitivity to Adr and Adr-induced apoptosis, and arrested the cells in G1 phase, accompanied by more expressions of p27(kip1), especially in nucleus. Furthermore, overexpressed miR-222 in MCF-7/S had the inverse results. Taken together, the results found that miR-222 induced Adr-resistance at least in part via suppressing p27(kip1) expression and altering its subcellular localization, and miR-222 inhibitors could reverse Adr-resistance of breast cancer cells. These results disclosed that the future holds much promise for the targeted therapeutic in the treatment of Adr-resistant breast cancer. PMID:27282281

  13. NF-{kappa}B signaling is activated and confers resistance to apoptosis in three-dimensionally cultured EGFR-mutant lung adenocarcinoma cells

    Energy Technology Data Exchange (ETDEWEB)

    Sakuma, Yuji, E-mail: ysakuma@gancen.asahi.yokohama.jp [Molecular Pathology and Genetics Division, Kanagawa Cancer Center Research Institute, Yokohama (Japan); Yamazaki, Yukiko; Nakamura, Yoshiyasu; Yoshihara, Mitsuyo; Matsukuma, Shoichi; Koizume, Shiro; Miyagi, Yohei [Molecular Pathology and Genetics Division, Kanagawa Cancer Center Research Institute, Yokohama (Japan)

    2012-07-13

    Highlights: Black-Right-Pointing-Pointer EGFR-mutant cells in 3D culture resist EGFR inhibition compared with suspended cells. Black-Right-Pointing-Pointer Degradation of I{kappa}B and activation of NF-{kappa}B are observed in 3D-cultured cells. Black-Right-Pointing-Pointer Inhibiting NF-{kappa}B enhances the efficacy of the EGFR inhibitor in 3D-cultured cells. -- Abstract: Epidermal growth factor receptor (EGFR)-mutant lung adenocarcinoma cells in suspension undergo apoptosis to a greater extent than adherent cells in a monolayer when EGFR autophosphorylation is inhibited by EGFR tyrosine kinase inhibitors (TKIs). This suggests that cell adhesion to a culture dish may activate an anti-apoptotic signaling pathway other than the EGFR pathway. Since the microenvironment of cells cultured in a monolayer are substantially different to that of cells existing in three-dimension (3D) in vivo, we assessed whether two EGFR-mutant lung adenocarcinoma cell lines, HCC827 and H1975, were more resistant to EGFR TKI-induced apoptosis when cultured in a 3D extracellular matrix (ECM) as compared with in suspension. The ECM-adherent EGFR-mutant cells in 3D were significantly less sensitive to treatment with WZ4002, an EGFR TKI, than the suspended cells. Further, a marked degradation of I{kappa}B{alpha}, the inhibitor of nuclear factor (NF)-{kappa}B, was observed only in the 3D-cultured cells, leading to an increase in the activation of NF-{kappa}B. Moreover, the inhibition of NF-{kappa}B with pharmacological inhibitors enhanced EGFR TKI-induced apoptosis in 3D-cultured EGFR-mutant cells. These results suggest that inhibition of NF-{kappa}B signaling would render ECM-adherent EGFR-mutant lung adenocarcinoma cells in vivo more susceptible to EGFR TKI-induced cell death.

  14. The wheat durable, multipathogen resistance gene Lr34 confers partial blast resistance in rice.

    Science.gov (United States)

    Krattinger, Simon G; Sucher, Justine; Selter, Liselotte L; Chauhan, Harsh; Zhou, Bo; Tang, Mingzhi; Upadhyaya, Narayana M; Mieulet, Delphine; Guiderdoni, Emmanuel; Weidenbach, Denise; Schaffrath, Ulrich; Lagudah, Evans S; Keller, Beat

    2016-05-01

    The wheat gene Lr34 confers durable and partial field resistance against the obligate biotrophic, pathogenic rust fungi and powdery mildew in adult wheat plants. The resistant Lr34 allele evolved after wheat domestication through two gain-of-function mutations in an ATP-binding cassette transporter gene. An Lr34-like fungal disease resistance with a similar broad-spectrum specificity and durability has not been described in other cereals. Here, we transformed the resistant Lr34 allele into the japonica rice cultivar Nipponbare. Transgenic rice plants expressing Lr34 showed increased resistance against multiple isolates of the hemibiotrophic pathogen Magnaporthe oryzae, the causal agent of rice blast disease. Host cell invasion during the biotrophic growth phase of rice blast was delayed in Lr34-expressing rice plants, resulting in smaller necrotic lesions on leaves. Lines with Lr34 also developed a typical, senescence-based leaf tip necrosis (LTN) phenotype. Development of LTN during early seedling growth had a negative impact on formation of axillary shoots and spikelets in some transgenic lines. One transgenic line developed LTN only at adult plant stage which was correlated with lower Lr34 expression levels at seedling stage. This line showed normal tiller formation and more importantly, disease resistance in this particular line was not compromised. Interestingly, Lr34 in rice is effective against a hemibiotrophic pathogen with a lifestyle and infection strategy that is different from obligate biotrophic rusts and mildew fungi. Lr34 might therefore be used as a source in rice breeding to improve broad-spectrum disease resistance against the most devastating fungal disease of rice.

  15. Major QTL Conferring Resistance to Rice Bacterial Leaf Streak

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Bacterial leaf streak (BLS) is one of the important limiting factors to rice production in southern China and other tropical and sub-tropical areas in Asia. Resistance to BLS was found to be a quantitative trait and no major resistant gene was located in rice until date. In the present study, a new major quantitative trait locus (QTL) conferring resistance to BLS was identified from a highly resistant variety Dular by the employment of Dular/Balilla (DB) and Dular/IR24 (DI) segregation populations and was designated qBLSR-11-1. This QTL was located between the simple sequence repeat (SSR) markers RM120 and RM441 on chromosome 11 and could account for 18.1-21.7% and 36.3% of the variance in DB and DI populations, respectively. The genetic pattern of rice resistance to BLS was discussed.

  16. Estrogen-Related Receptor Alpha Confers Methotrexate Resistance via Attenuation of Reactive Oxygen Species Production and P53 Mediated Apoptosis in Osteosarcoma Cells

    Directory of Open Access Journals (Sweden)

    Peng Chen

    2014-01-01

    Full Text Available Osteosarcoma (OS is a malignant tumor mainly occurring in children and adolescents. Methotrexate (MTX, a chemotherapy agent, is widely used in treating OS. However, treatment failures are common due to acquired chemoresistance, for which the underlying molecular mechanisms are still unclear. In this study, we report that overexpression of estrogen-related receptor alpha (ERRα, an orphan nuclear receptor, promoted cell survival and blocked MTX-induced cell death in U2OS cells. We showed that MTX induced ROS production in MTX-sensitive U2OS cells while ERRα effectively blocked the ROS production and ROS associated cell apoptosis. Our further studies demonstrated that ERRα suppressed ROS induction of tumor suppressor P53 and its target genes NOXA and XAF1 which are mediators of P53-dependent apoptosis. In conclusion, this study demonstrated that ERRα plays an important role in the development of MTX resistance through blocking MTX-induced ROS production and attenuating the activation of p53 mediated apoptosis signaling pathway, and points to ERRα as a novel target for improving osteosarcoma therapy.

  17. Targeting PCDH20 gene by microRNA-122 confers 5-FU resistance in hepatic carcinoma.

    Science.gov (United States)

    Wang, Wei; Liu, Wen Bin; Huang, Da Bing; Jia, Wei; Ji, Chu Shu; Hu, Bing

    2016-01-01

    Drug resistance is one of the main hurdles for the successful treatment of hepatic carcinoma. However, the detailed mechanisms underlying resistance remain largely unknown and therapeutic approaches are limited. In the present study, we show that miR-122 confers resistance to 5-fluorouracil induced hepatocellular carcinoma cell apoptosis in vitro and reduces the potency of 5-fluorouracil in the inhibition of tumor growth in a mouse xenograft model in vivo. Further studies indicate that miR-122 modulates drug resistance through down-regulation of expression of PCDH20, which belongs to the protocadherin gene family and negatively regulates Akt activation. Knockdown of PCDH20 expression increases Akt phosphorylation, which leads to elevated mTOR activity and enhanced 5-fluorouracil resistance; whereas rescue of PCDH20 expression in miR-122-expressing cells decreases Akt and mTOR phosphorylation, re-sensitizing hepatocellular carcinoma cell to 5-fluorouracil induced apoptosis. Moreover, a specific and potent Akt inhibitor reverses miR-122-conferred 5-fluorouracil resistance. These findings indicate that the miR-122/PCDH20/Akt/mTOR signaling axis has an important role in mediating response to chemotherapy in human hepatocellular carcinoma. A major implication of our study is that inhibition of miR-122 or restoration of PCDH20 expression may have significant therapeutic potential to overcome drug resistance in hepatocellular carcinoma and that the combined use of an Akt inhibitor with 5-fluorouracil may increase efficacy in liver cancer treatment. PMID:27648358

  18. EXPRESSION OF HUMAN α-GALACTOSIDASE AND α1,2-FUCOSYL-TRANSFERASE GENES MODIFIES THE CELL SURFACE GALα1,3GAL ANTIGEN AND CONFERS RESISTANCE TO HUMAN SERUM-MEDIATED CYTOLYSIS

    Institute of Scientific and Technical Information of China (English)

    贾延军; 任会明; 高新; 季守平; 杨军; 刘泽鹏; 李素波; 章扬培

    2004-01-01

    Objective To explore the strategies which reduce the amount of xenoantigen Galα1, 3 Gal. Methods Human α-galactosidase gene and α 1,2-fucosyltransferase gene were transferred into cultured porcine vascular endothelial cells PEDSV.15 and human α-galactosidase transgenic mice were produced. The Galα 1,3Gal on the cell surface and susceptibility of cells to human antibody-mediated lysis were analyzed. Results Human α-galactosidase gene alone reduced 78% of Galα1,3Gal on PEDSV.15 cell surface while human α-galactosidase combined with α 1,2-fucosyltransferase genes removed Galα 1,3Gal completely. Decrease of Galα1,3Gal could reduce susceptibility of cells to human antibody-mediated lysis, especially during co-expression of α-galactosidase gene and α1,2-fucosyltransferase gene. RT-PCR indicated positive human α-galactosidase gene expression in all organs of positive human α-galactosidase transgenic F1 mice including heart, liver, kidney, lung, and spleen, the amount of Galα1,3Gal antigens on which was reduced largely. 58% of spleen cells from F1 mice were destroyed by complement-mediated lysis compared with 24% of those from normal mice. Conclusions Human α-galactosidase gene and α1,2-fucosyltransferase gene effectively reduce the expression of Galα1,3Gal antigens on endothelial cell surface and confers resistance to human serummediated cytolysis. The expression of human α-galactosidase in mice can also eliminate the Galα1,3Gal antigens in most tissues and decrease the susceptibility of spleen cells to human serum-mediated cytolysis.

  19. Crizotinib-resistant NPM-ALK mutants confer differential sensitivity to unrelated Alk inhibitors.

    Science.gov (United States)

    Ceccon, Monica; Mologni, Luca; Bisson, William; Scapozza, Leonardo; Gambacorti-Passerini, Carlo

    2013-02-01

    The dual ALK/MET inhibitor crizotinib was recently approved for the treatment of metastatic and late-stage ALK+ NSCLC, and is currently in clinical trial for other ALK-related diseases. As predicted after other tyrosine kinase inhibitors' clinical experience, the first mutations that confer resistance to crizotinib have been described in patients with non-small cell lung cancer (NSCLC) and in one patient inflammatory myofibroblastic tumor (IMT). Here, we focused our attention on the anaplastic large cell lymphoma (ALCL), where the oncogenic fusion protein NPM-ALK, responsible for 70% to 80% of cases, represents an ideal crizotinib target. We selected and characterized 2 human NPM-ALK+ ALCL cell lines, KARPAS-299 and SUP-M2, able to survive and proliferate at different crizotinib concentrations. Sequencing of ALK kinase domain revealed that a single mutation became predominant at high crizotinib doses in each cell line, namely L1196Q and I1171N in Karpas-299 and SUP-M2 cells, respectively. These mutations also conferred resistance to crizotinib in Ba/F3 cells expressing human NPM-ALK. The resistant cell populations, as well as mutated Ba/F3 cells, were characterized for sensitivity to two additional ALK inhibitors: the dual ALK/EGFR inhibitor AP26113 and NVP-TAE684. While L1196Q-positive cell lines were sensitive to both inhibitors, cells carrying I1171N substitution showed cross-resistance to all ALK inhibitors tested. This study provides potentially relevant information for the management of patients with ALCL that may relapse after crizotinib treatment.

  20. Bacterial glyphosate resistance conferred by overexpression of an E. coli membrane efflux transporter.

    Science.gov (United States)

    Staub, Jeffrey M; Brand, Leslie; Tran, Minhtien; Kong, Yifei; Rogers, Stephen G

    2012-04-01

    Glyphosate herbicide-resistant crop plants, introduced commercially in 1994, now represent approximately 85% of the land area devoted to transgenic crops. Herbicide resistance in commercial glyphosate-resistant crops is due to expression of a variant form of a bacterial 5-enolpyruvylshikimate-3-phosphate synthase with a significantly decreased binding affinity for glyphosate at the target site of the enzyme. As a result of widespread and recurrent glyphosate use, often as the only herbicide used for weed management, increasing numbers of weedy species have evolved resistance to glyphosate. Weed resistance is most often due to changes in herbicide translocation patterns, presumed to be through the activity of an as yet unidentified membrane transporter in plants. To provide insight into glyphosate resistance mechanisms and identify a potential glyphosate transporter, we screened Escherichia coli genomic DNA for alternate sources of glyphosate resistance genes. Our search identified a single non-target gene that, when overexpressed in E. coli and Pseudomonas, confers high-level glyphosate resistance. The gene, yhhS, encodes a predicted membrane transporter of the major facilitator superfamily involved in drug efflux. We report here that an alternative mode of glyphosate resistance in E. coli is due to reduced accumulation of glyphosate in cells that overexpress this membrane transporter and discuss the implications for potential alternative resistance mechanisms in other organisms such as plants.

  1. Advances in Mapping Loci Conferring Resistance to Rice Sheath Blight and Mining Rhizoctonia solani Resistant Resources

    Institute of Scientific and Technical Information of China (English)

    ZENG Yu-xiang; JI Zhi-juan; MA Liang-yong; LI Xi-ming; YANG Chang-deng

    2011-01-01

    Sheath blight (SB) caused by Rhizoctonia solani is one of the three major diseases of rice,and now has become the most severe disease causing rice yield loss in China.Breeding and use of varieties resistant to SB is crucial in controlling the disease,but the advances achieved have been limited due to the lack of highly SB-resistant rice germplasm.Genetic analysis revealed that the SB resistance in rice was a typical quantitative trait controlled by multi-genes.Although many QTLs conferring resistance to SB have been identified in recent years,most of the QTLs only showed small effects and few of them have been evaluated for utilization potential.Many R.solani-resistant resources have been found in wild rice species,microorganisms and other plant species.It is already known that the SB-resistance could be improved in transgenic rice plants by genetic transformation.This paper reviewed the genetic mapping of loci associated with resistance to rice SB,the evaluation of the potential of resistance QTLs,and the resistant resources found in various organisms besides rice.To develop SB-resistant rice varieties,it is important to develop and explore new resistant rice germplasms,fine map and evaluate resistance QTLs,and also to pay attention to various bio-resources showing resistance to R.solani.

  2. Food supply confers calcifiers resistance to ocean acidification

    KAUST Repository

    Ramajo, Laura

    2016-01-18

    Invasion of ocean surface waters by anthropogenic CO2 emitted to the atmosphere is expected to reduce surface seawater pH to 7.8 by the end of this century compromising marine calcifiers. A broad range of biological and mineralogical mechanisms allow marine calcifiers to cope with ocean acidification, however these mechanisms are energetically demanding which affect other biological processes (trade-offs) with important implications for the resilience of the organisms against stressful conditions. Hence, food availability may play a critical role in determining the resistance of calcifiers to OA. Here we show, based on a meta-analysis of existing experimental results assessing the role of food supply in the response of organisms to OA, that food supply consistently confers calcifiers resistance to ocean acidification.

  3. The overexpression and nuclear translocation of Trx-1 during hypoxia confers on HepG2 cells resistance to DDP, and GL-V9 reverses the resistance by suppressing the Trx-1/Ref-1 axis.

    Science.gov (United States)

    Zhao, Li; Li, Wei; Zhou, Yuxin; Zhang, Yi; Huang, Shaoliang; Xu, Xuefen; Li, Zhiyu; Guo, Qinglong

    2015-05-01

    Microenvironmental hypoxia gives many tumor cells the capacity for drug resistance. Thioredoxin family members play critical roles in the regulation of cellular redox homeostasis in a stressed environment. In this study, we established a hypoxia-drug resistance (hypoxia-DR) model using HepG2 cells and discovered that the overexpression and nuclear translocation of thioredoxin-1 (Trx-1) are closely associated with this resistance through the regulation of the metabolism by the oxidative stress response to glycolysis. Intranuclear Trx-1 enhances the DNA-binding activity of HIF-1α via its interaction with and reducing action on Ref-1, resulting in increased expression of glycolysis-related proteins (PDHK1, HKII, and LDHA), glucose uptake, and lactate generation under hypoxia. Meanwhile, we found that GL-V9, a newly synthesized flavonoid derivative, shows an ability to reverse the hypoxia-DR and has low toxicity both in vivo and in vitro. GL-V9 could inhibit the expression and nuclear translocation of Trx-1 and then suppress HIF-1α DNA-binding activity by inhibiting the Trx-1/Ref-1 axis. As a result, glycolysis is weakened and oxidative phosphorylation is enhanced. Thus, GL-V9 leads to an increment in intracellular ROS generation and consequently intensified apoptosis induced by DDP.

  4. Functional analysis of androgen receptor mutations that confer anti-androgen resistance identified in circulating cell-free DNA from prostate cancer patients

    OpenAIRE

    Lallous, Nada; Volik, Stanislav V.; Awrey, Shannon; LeBlanc, Eric; Tse, Ronnie; Murillo, Josef; Singh, Kriti; Azad, Arun A.; Wyatt, Alexander W.; LeBihan, Stephane; Chi, Kim N.; Gleave, Martin E.; Paul S. Rennie; Collins, Colin C; Cherkasov, Artem

    2016-01-01

    Background The androgen receptor (AR) is a pivotal drug target for the treatment of prostate cancer, including its lethal castration-resistant (CRPC) form. All current non-steroidal AR antagonists, such as hydroxyflutamide, bicalutamide, and enzalutamide, target the androgen binding site of the receptor, competing with endogenous androgenic steroids. Several AR mutations in this binding site have been associated with poor prognosis and resistance to conventional prostate cancer drugs. In orde...

  5. Spectrum of Resistance Conferred by ml-o Powdery Mildew Resistance Genes in Barley

    DEFF Research Database (Denmark)

    Jørgensen, Jørgen Helms

    1977-01-01

    /(4) in all tests. They were also resistant to field populations of the pathogen when scored in disease nurseries at more than 78 locations in 29 countries in Europe, the Near East, North and South America. New Zealand, and Japan. This indicates that the 11 genes confer the same, world-wide spectrum......Ten barley mutants and five Ethiopian barley lines representing 11 independently arisen powdery mildew resistance genes in the ml-o locus were tested at the seedling stage to cultures of the powdery mildew fungus from Europe, Israel, USA. Canada, and Japan. They were resistant with infection type 0...

  6. Gli1-Mediated Regulation of Sox2 Facilitates Self-Renewal of Stem-Like Cells and Confers Resistance to EGFR Inhibitors in Non–Small Cell Lung Cancer 1

    OpenAIRE

    Namrata Bora-Singhal; Deepak Perumal; Jonathan Nguyen; Srikumar Chellappan

    2015-01-01

    Non–small cell lung cancer (NSCLC) patients have very low survival rates because the current therapeutic strategies are not fully effective. Although EGFR tyrosine kinase inhibitors are effective for NSCLC patients harboring EGFR mutations, patients invariably develop resistance to these agents. Alterations in multiple signaling cascades have been associated with the development of resistance to EGFR inhibitors. Sonic Hedgehog and associated Gli transcription factors play a major role in embr...

  7. 2003 Plant Cell Walls Gordon Conference

    Energy Technology Data Exchange (ETDEWEB)

    Daniel J. Cosgrove

    2004-09-21

    This conference will address recent progress in many aspects of cell wall biology. Molecular, genetic, and genomic approaches are yielding major advances in our understanding of the composition, synthesis, and architecture of plant cell walls and their dynamics during growth, and are identifying the genes that encode the machinery needed to make their biogenesis possible. This meeting will bring together international scientists from academia, industry and government labs to share the latest breakthroughs and perspectives on polysaccharide biosynthesis, wood formation, wall modification, expansion and interaction with other organisms, and genomic & evolutionary analyses of wall-related genes, as well as to discuss recent ''nanotechnological'' advances that take wall analysis to the level of a single cell.

  8. Loss of the SxxSS motif in a human T-cell factor-4 isoform confers hypoxia resistance to liver cancer: an oncogenic switch in Wnt signaling.

    Directory of Open Access Journals (Sweden)

    Hironori Koga

    Full Text Available PURPOSE: Aberrantly activated Wnt/β-catenin signaling is important in hepatocellular carcinoma (HCC development. Downstream gene expressions involving the Wnt/β-catenin cascade occur through T-cell factor (TCF proteins. Here, we show the oncogenic potential of human TCF-4 isoforms based on the expression of a single conserved SxxSS motif. METHODS: We investigated the TCF-4J and K isoform pair characterized by the presence (K or absence (J of the SxxSS motif. The mRNA expression profiles were examined in 47 pairs of human HCCs and adjacent non-cancerous liver tissues by RT-PCR. Proliferation, sphere assays and immunoblot analysis were performed under normoxia and hypoxia conditions. The ability of HCC cells overexpressing TCF-4J (J cells and K (K cells to grow as solid tumors in nude mice was explored. RESULTS: TCF-4J expression was significantly upregulated in HCC tumors compared to corresponding peritumor and normal liver and was preferentially expressed in poorly differentiated HCCs. In contrast, TCF-4K was downregulated in those same HCC tumors. TCF-4J-overexpressing HCC cells (J cells revealed a survival advantage under hypoxic conditions, high proliferation rate and formation of aggregates/spheres compared to overexpression of TCF-4K (K cells. The hypoxic J cells had high expression levels of HIF-2α and EGFR as possible mechanisms to promote tumorigenesis. Increased stability of HIF-2α under hypoxia in J cells was associated with a decreased level of von Hippel-Lindau (VHL protein, a known E3 ligase for HIF-αs. In a xenograft model, the J cells rapidly developed tumors compared to K cells. Tumor tissues derived from J cells exhibited high expression levels of HIF-2α and EGFR compared to the slow developing and small K cell derived tumors. CONCLUSIONS: Our results suggest that the specific TCF-4J isoform, which lacks a regulatory SxxSS motif, has robust tumor-initiating potential under hypoxic conditions.

  9. Exosomal transfer of stroma-derived miR21 confers paclitaxel resistance in ovarian cancer cells through targeting APAF1

    OpenAIRE

    Au Yeung, Chi Lam; Co, Ngai-Na; Tsuruga, Tetsushi; Yeung, Tsz-Lun; Kwan, Suet-Ying; Leung, Cecilia S.; LI, YONG; Lu, Edward S.; Kwan, Kenny; Wong, Kwong-Kwok; Schmandt, Rosemarie; Lu, Karen H.; Mok, Samuel C.

    2016-01-01

    Advanced ovarian cancer usually spreads to the visceral adipose tissue of the omentum. However, the omental stromal cell-derived molecular determinants that modulate ovarian cancer growth have not been characterized. Here, using next-generation sequencing technology, we identify significantly higher levels of microRNA-21 (miR21) isomiRNAs in exosomes and tissue lysates isolated from cancer-associated adipocytes (CAAs) and fibroblasts (CAFs) than in those from ovarian cancer cells. Functional ...

  10. Clustering of Major Genes Conferring Blast Resistance in a Durable Resistance Rice Cultivar Gumei 2

    Institute of Scientific and Technical Information of China (English)

    WU Jian-li; CHAI Rong-yao; FAN Ye-yang; LI De-bao; ZHENG Kang-le; Hei LEUNG; ZHUANG Jie-yun

    2004-01-01

    By using 304 recombinant inbred lines derived from indica rice cross Zhong 156/Gumei 2, a linkage map consisting of 177 marker loci and covering 12 rice chromosomes was constructed and employed for mapping genes conferring blast resistance in rice. Genomic location of gene Pi25(t) conferring neck blast resistance to the Chinese isolate 92-183 (race ZC15) was verified to be located between markers A7 and RG456 on chromosome 6, with genetic distances of 1.7 cM and 1.5 cM to A7 and RG456,respectively. Leaf blast resistance of Gumei 2 to the Philippine isolate Ca89 (lineage 4) was found to be controlled by a single gene. The gene tentatively designated as Pi26(t) was located between makers B10 and R674 on chromosome 6, with genetic distances of 5.7 cM and 25.8 cM to B10 and R674 respectively. Resistant alleles at both gene loci were derived from Gumei 2,indicating an existence of resistance gene cluster in Gumei 2.

  11. Drug resistance. K13-propeller mutations confer artemisinin resistance in Plasmodium falciparum clinical isolates.

    Science.gov (United States)

    Straimer, Judith; Gnädig, Nina F; Witkowski, Benoit; Amaratunga, Chanaki; Duru, Valentine; Ramadani, Arba Pramundita; Dacheux, Mélanie; Khim, Nimol; Zhang, Lei; Lam, Stephen; Gregory, Philip D; Urnov, Fyodor D; Mercereau-Puijalon, Odile; Benoit-Vical, Françoise; Fairhurst, Rick M; Ménard, Didier; Fidock, David A

    2015-01-23

    The emergence of artemisinin resistance in Southeast Asia imperils efforts to reduce the global malaria burden. We genetically modified the Plasmodium falciparum K13 locus using zinc-finger nucleases and measured ring-stage survival rates after drug exposure in vitro; these rates correlate with parasite clearance half-lives in artemisinin-treated patients. With isolates from Cambodia, where resistance first emerged, survival rates decreased from 13 to 49% to 0.3 to 2.4% after the removal of K13 mutations. Conversely, survival rates in wild-type parasites increased from ≤0.6% to 2 to 29% after the insertion of K13 mutations. These mutations conferred elevated resistance to recent Cambodian isolates compared with that of reference lines, suggesting a contemporary contribution of additional genetic factors. Our data provide a conclusive rationale for worldwide K13-propeller sequencing to identify and eliminate artemisinin-resistant parasites.

  12. Identification of Bone-Derived Factors Conferring De Novo Therapeutic Resistance in Metastatic Prostate Cancer.

    Science.gov (United States)

    Lee, Yu-Chen; Lin, Song-Chang; Yu, Guoyu; Cheng, Chien-Jui; Liu, Bin; Liu, Hsuan-Chen; Hawke, David H; Parikh, Nila U; Varkaris, Andreas; Corn, Paul; Logothetis, Christopher; Satcher, Robert L; Yu-Lee, Li-Yuan; Gallick, Gary E; Lin, Sue-Hwa

    2015-11-15

    Resistance to currently available targeted therapies significantly hampers the survival of patients with prostate cancer with bone metastasis. Here we demonstrate an important resistance mechanism initiated from tumor-induced bone. Studies using an osteogenic patient-derived xenograft, MDA-PCa-118b, revealed that tumor cells resistant to cabozantinib, a Met and VEGFR-2 inhibitor, reside in a "resistance niche" adjacent to prostate cancer-induced bone. We performed secretome analysis of the conditioned medium from tumor-induced bone to identify proteins (termed "osteocrines") found within this resistance niche. In accordance with previous reports demonstrating that activation of integrin signaling pathways confers therapeutic resistance, 27 of the 90 osteocrines identified were integrin ligands. We found that following cabozantinib treatment, only tumor cells positioned adjacent to the newly formed woven bone remained viable and expressed high levels of pFAK-Y397 and pTalin-S425, mediators of integrin signaling. Accordingly, treatment of C4-2B4 cells with integrin ligands resulted in increased pFAK-Y397 expression and cell survival, whereas targeting integrins with FAK inhibitors PF-562271 or defactinib inhibited FAK phosphorylation and reduced the survival of PC3-mm2 cells. Moreover, treatment of MDA-PCa-118b tumors with PF-562271 led to decreased tumor growth, irrespective of initial tumor size. Finally, we show that upon treatment cessation, the combination of PF-562271 and cabozantinib delayed tumor recurrence in contrast to cabozantinib treatment alone. Our studies suggest that identifying paracrine de novo resistance mechanisms may significantly contribute to the generation of a broader set of potent therapeutic tools that act combinatorially to inhibit metastatic prostate cancer.

  13. Overexpression of glutamine synthetases confers transgenic rice herbicide resistance

    Institute of Scientific and Technical Information of China (English)

    Sun Hui; Huang Qiman; Su Jin

    2005-01-01

    Glutamine synthetase (GS, E.C.6.3.1.2) is a key enzyme involved in the assimilation of inorganic nitrogen in higher plants and gram-negative microorganisms. GS is the targeting enzyme of a herbicide phosphinothricin (PPT) or Basta. In order to generate PPT-resistant transgenic rice via overexpression of GS, we constructed a plant expression vector p2GS harboring two different isoenzymes GS1 and GS2 cDNAs under the control of constitutive promoters of rice Act1 and maize Ubiquitin(Ubi) genes. The p2GS was introduced into rice genome by Agrobacterium-mediated transformation and confirmed by PCR and Southern blot hybridization. GS-transgene expression was first detected by Northern blot analyses. Results from Basta test indicated that GS-transgenic plants can tolerate as high as 0.3% Basta solution. In addition, our results also demonstrated that GS overexpression conferred transformed rice calli PPT resistance. Thus, GS cassette can serve as a selective marker gene instead of bar cassette for selection of PPT transformants.

  14. Academic Conferences: Representative and Resistant Sites for Higher Education Research

    Science.gov (United States)

    Henderson, Emily F.

    2015-01-01

    The overarching argument made in this article is twofold. Firstly, academic conferences are posited as sites for higher education research. Secondly, the well-recognised emotional and social processes of conferences are used to make space at the boundaries of higher education research for psychosocial analysis. The article theorises conferences in…

  15. Gli1-Mediated Regulation of Sox2 Facilitates Self-Renewal of Stem-Like Cells and Confers Resistance to EGFR Inhibitors in Non–Small Cell Lung Cancer

    Directory of Open Access Journals (Sweden)

    Namrata Bora-Singhal

    2015-07-01

    Full Text Available Non–small cell lung cancer (NSCLC patients have very low survival rates because the current therapeutic strategies are not fully effective. Although EGFR tyrosine kinase inhibitors are effective for NSCLC patients harboring EGFR mutations, patients invariably develop resistance to these agents. Alterations in multiple signaling cascades have been associated with the development of resistance to EGFR inhibitors. Sonic Hedgehog and associated Gli transcription factors play a major role in embryonic development and have recently been found to be reactivated in NSCLC, and elevated Gli1 levels correlate with poor prognosis. The Hedgehog pathway has been implicated in the functions of cancer stem cells, although the underlying molecular mechanisms are not clear. In this context, we demonstrate that Gli1 is a strong regulator of embryonic stem cell transcription factor Sox2. Depletion of Gli1 or inhibition of the Hedgehog signaling significantly abrogated the self-renewal of stem-like side-population cells from NSCLCs as well as vascular mimicry of such cells. Gli1 was found to transcriptionally regulate Sox2 through its promoter region, and Gli1 could be detected on the Sox2 promoter. Inhibition of Hedgehog signaling appeared to work cooperatively with EGFR inhibitors in markedly reducing the viability of NSCLC cells as well as the self-renewal of stem-like cells. Thus, our study demonstrates a cooperative functioning of the EGFR signaling and Hedgehog pathways in governing the stem-like functions of NSCLC cancer stem cells and presents a novel therapeutic strategy to combat NSCLC harboring EGFR mutations.

  16. Elevated Levels of Uterine Anti-Apoptotic Signaling May Activate NFKB and Potentially Confer Resistance to Caspase 3-Mediated Apoptotic Cell Death During Pregnancy in Mice1

    Science.gov (United States)

    Jeyasuria, Pancharatnam; Subedi, Kalpana; Suresh, Arvind; Condon, Jennifer C.

    2011-01-01

    Preserving the uterus in a state of relative quiescence is vital to the maintenance of a successful pregnancy. Elevated cytoplasmic levels of uterine caspase 3 during pregnancy have been proposed as a potential regulator of uterine quiescence through direct targeting and disabling of the uterine contractile architecture. However, despite highly elevated levels of uterine caspase 3 during pregnancy, there is minimal evidence of apoptosis. This current study defines the mechanism whereby the pregnant uterine myocyte may harness the tocolytic activity of active caspases while avoiding apoptotic cell death. Using the pregnant mouse model, we have analyzed the uterus for changes in pro- and antiapoptotic signaling patterns associated with the advancing stages of pregnancy. Briefly, we have found that members of the IAP family, such as SURVIVIN and XIAP, and the Bcl2 family members, such as MCL1, are elevated in the uterine myocyte during late gestation. The IAP family members are the only endogenous inhibitors of active caspase 3, and MCL1 limits activation of caspase 3 by suppressing proapoptotic signaling. Elevated XIAP levels partner with SURVIVIN, resulting in increased levels of the antiapoptotic MCL1 via NFKB activation; these together have the potential to limit both the activity and level of active caspase 3 in the pregnant uterus as term approaches. We propose that modification of these antiapoptotic signaling partners allows the pregnant uterus to escape the apoptotic action of elevated active caspase 3 levels but also functions to limit the levels of active uterine caspase 3 near term. PMID:21566000

  17. Heterologously expressed bacterial and human multidrug resistance proteins confer cadmium resistance to Escherichia coli

    NARCIS (Netherlands)

    Achard-Joris, M; van Saparoea, HBV; Driessen, AJM; Bourdineaud, JP; Bourdineaud, Jean-Paul

    2005-01-01

    The human MDR1 gene is induced by cadmium exposure although no resistance to this metal is observed in human cells overexpressing hMDR1. To access the role of MDR proteins in cadmium resistance, human MDR1, Lactococcus lactis lmrA, and Oenococcus oeni omrA were expressed in an Escherichia coli tolC

  18. Mutations in the Plasmodium falciparum Cyclic Amine Resistance Locus (PfCARL Confer Multidrug Resistance

    Directory of Open Access Journals (Sweden)

    Gregory LaMonte

    2016-07-01

    Full Text Available Mutations in the Plasmodium falciparum cyclic amine resistance locus (PfCARL are associated with parasite resistance to the imidazolopiperazines, a potent class of novel antimalarial compounds that display both prophylactic and transmission-blocking activity, in addition to activity against blood-stage parasites. Here, we show that pfcarl encodes a protein, with a predicted molecular weight of 153 kDa, that localizes to the cis-Golgi apparatus of the parasite in both asexual and sexual blood stages. Utilizing clustered regularly interspaced short palindromic repeat (CRISPR-mediated gene introduction of 5 variants (L830V, S1076N/I, V1103L, and I1139K, we demonstrate that mutations in pfcarl are sufficient to generate resistance against the imidazolopiperazines in both asexual and sexual blood-stage parasites. We further determined that the mutant PfCARL protein confers resistance to several structurally unrelated compounds. These data suggest that PfCARL modulates the levels of small-molecule inhibitors that affect Golgi-related processes, such as protein sorting or membrane trafficking, and is therefore an important mechanism of resistance in malaria parasites.

  19. Multiple resistance to sulfonylureas and imidazolinones conferred by an acetohydroxyacid synthase gene with separate mutations for selective resistance.

    Science.gov (United States)

    Hattori, J; Rutledge, R; Labbé, H; Brown, D; Sunohara, G; Miki, B

    1992-03-01

    The acetohydroxyacid synthase (AHAS) gene from the Arabidopsis thaliana mutant line GH90 carrying the imidazolinone resistance allele imr1 was cloned. Expression of the AHAS gene under the control of the CaMV 35S promoter in transgenic tobacco resulted in selective imidazolinone resistance, confirming that the single base-pair change found near the 3' end of the coding region of this gene is responsible for imidazolinone resistance. A chimeric AHAS gene containing both the imr1 mutation and the csr1 mutation, responsible for selective resistance to sulfonylurea herbicides, was constructed. It conferred on transgenic tobacco plants resistance to both sulfonylurea and imidazolinone herbicides. The data illustrate that a multiple-resistance phenotype can be achieved in an AHAS gene through combinations of separate mutations, each of which individually confers resistance to only one class of herbicides. PMID:1557022

  20. Measuring The Contact Resistances Of Photovoltaic Cells

    Science.gov (United States)

    Burger, D. R.

    1985-01-01

    Simple method devised to measure contact resistances of photovoltaic solar cells. Method uses readily available equipment and applicable at any time during life of cell. Enables evaluation of cell contact resistance, contact-end resistance, contact resistivity, sheet resistivity, and sheet resistivity under contact.

  1. NALP3 inflammasome upregulation and CASP1 cleavage of the glucocorticoid receptor cause glucocorticoid resistance in leukemia cells

    NARCIS (Netherlands)

    S.W. Paugh (Steven); E.J. Bonten (Erik J.); D. Savic (Daniel); L.B. Ramsey (Laura B.); W.E. Thierfelder (William E.); P. Gurung (Prajwal); R.K.S. Malireddi (R. K. Subbarao); M. Actis (Marcelo); A. Mayasundari (Anand); J. Min (Jaeki); D.R. Coss (David R.); L.T. Laudermilk (Lucas T.); J.C. Panetta (John); J.R. McCorkle (J. Robert); Y. Fan (Yiping); K.R. Crews (Kristine R.); G. Stocco (Gabriele); M.R. Wilkinson (Mark R.); A.M. Ferreira (Antonio M.); C. Cheng (Cheng); W. Yang (Wenjian); S.E. Karol (Seth E.); C.A. Fernandez (Christian A.); B. Diouf (Barthelemy); C. Smith (Colton); J.K. Hicks (J Kevin); A. Zanut (Alessandra); A. Giordanengo (Audrey); D.J. Crona; J.J. Bianchi (Joy J.); L. Holmfeldt (Linda); C.G. Mullighan (Charles); M.L. den Boer (Monique); R. Pieters (Rob); S. Jeha (Sima); T.L. Dunwell (Thomas L.); F. Latif (Farida); D. Bhojwani (Deepa); W.L. Carroll (William L.); C.-H. Pui (Ching-Hon); R.M. Myers (Richard M.); R.K. Guy (R Kiplin); T.-D. Kanneganti (Thirumala-Devi); M.V. Relling (Mary); W.E. Evans (William)

    2015-01-01

    textabstractGlucocorticoids are universally used in the treatment of acute lymphoblastic leukemia (ALL), and resistance to glucocorticoids in leukemia cells confers poor prognosis. To elucidate mechanisms of glucocorticoid resistance, we determined the prednisolone sensitivity of primary leukemia ce

  2. Cellular robustness conferred by genetic crosstalk underlies resistance against chemotherapeutic drug doxorubicin in fission yeast.

    Science.gov (United States)

    Tay, Zoey; Eng, Ru Jun; Sajiki, Kenichi; Lim, Kim Kiat; Tang, Ming Yi; Yanagida, Mitsuhiro; Chen, Ee Sin

    2013-01-01

    Doxorubicin is an anthracycline antibiotic that is among one of the most commonly used chemotherapeutic agents in the clinical setting. The usage of doxorubicin is faced with many problems including severe side effects and chemoresistance. To overcome these challenges, it is important to gain an understanding of the underlying molecular mechanisms with regards to the mode of action of doxorubicin. To facilitate this aim, we identified the genes that are required for doxorubicin resistance in the fission yeast Schizosaccharomyces pombe. We further demonstrated interplay between factors controlling various aspects of chromosome metabolism, mitochondrial respiration and membrane transport. In the nucleus we observed that the subunits of the Ino80, RSC, and SAGA complexes function in the similar epistatic group that shares significant overlap with the homologous recombination genes. However, these factors generally act in synergistic manner with the chromosome segregation regulator DASH complex proteins, possibly forming two major arms for regulating doxorubicin resistance in the nucleus. Simultaneous disruption of genes function in membrane efflux transport or the mitochondrial respiratory chain integrity in the mutants defective in either Ino80 or HR function resulted in cumulative upregulation of drug-specific growth defects, suggesting a rewiring of pathways that synergize only when the cells is exposed to the cytotoxic stress. Taken together, our work not only identified factors that are required for survival of the cells in the presence of doxorubicin but has further demonstrated that an extensive molecular crosstalk exists between these factors to robustly confer doxorubicin resistance.

  3. Cellular robustness conferred by genetic crosstalk underlies resistance against chemotherapeutic drug doxorubicin in fission yeast.

    Directory of Open Access Journals (Sweden)

    Zoey Tay

    Full Text Available Doxorubicin is an anthracycline antibiotic that is among one of the most commonly used chemotherapeutic agents in the clinical setting. The usage of doxorubicin is faced with many problems including severe side effects and chemoresistance. To overcome these challenges, it is important to gain an understanding of the underlying molecular mechanisms with regards to the mode of action of doxorubicin. To facilitate this aim, we identified the genes that are required for doxorubicin resistance in the fission yeast Schizosaccharomyces pombe. We further demonstrated interplay between factors controlling various aspects of chromosome metabolism, mitochondrial respiration and membrane transport. In the nucleus we observed that the subunits of the Ino80, RSC, and SAGA complexes function in the similar epistatic group that shares significant overlap with the homologous recombination genes. However, these factors generally act in synergistic manner with the chromosome segregation regulator DASH complex proteins, possibly forming two major arms for regulating doxorubicin resistance in the nucleus. Simultaneous disruption of genes function in membrane efflux transport or the mitochondrial respiratory chain integrity in the mutants defective in either Ino80 or HR function resulted in cumulative upregulation of drug-specific growth defects, suggesting a rewiring of pathways that synergize only when the cells is exposed to the cytotoxic stress. Taken together, our work not only identified factors that are required for survival of the cells in the presence of doxorubicin but has further demonstrated that an extensive molecular crosstalk exists between these factors to robustly confer doxorubicin resistance.

  4. Corrosion resistant PEM fuel cell

    Science.gov (United States)

    Fronk, Matthew Howard; Borup, Rodney Lynn; Hulett, Jay S.; Brady, Brian K.; Cunningham, Kevin M.

    2002-01-01

    A PEM fuel cell having electrical contact elements comprising a corrosion-susceptible substrate metal coated with an electrically conductive, corrosion-resistant polymer containing a plurality of electrically conductive, corrosion-resistant filler particles. The substrate may have an oxidizable metal first layer (e.g., stainless steel) underlying the polymer coating.

  5. Targeted therapy against multi-resistant bacteria in leukemic and hematopoietic stem cell transplant recipients: guidelines of the 4th European Conference on Infections in Leukemia (ECIL-4, 2011)

    NARCIS (Netherlands)

    Averbuch, D.; Cordonnier, C.; Livermore, D.M.; Mikulska, M.; Orasch, C.; Viscoli, C.; Gyssens, I.C.J.; Kern, W.V.; Klyasova, G.; Marchetti, O.; Engelhard, D.; Akova, M.; Ecil, a.j.v.o.E.E.I.E.E.; Eln, .

    2013-01-01

    The detection of multi-resistant bacterial pathogens, particularly those to carbapenemases, in leukemic and stem cell transplant patients forces the use of old or non-conventional agents as the only remaining treatment options. These include colistin/polymyxin B, tigecycline, fosfomycin and various

  6. SU-C-303-01: Activation-Induced Cytidine Deaminase Confers Cancer Resistance to Radiation Therapy

    International Nuclear Information System (INIS)

    Purpose: To study the role of activation-induced cytidine deaminase (AID) in malignant cell resistance to radiation therapy. Methods: We first developed several small devices that could be used to adopt radiation beams from clinical high dose rate brachy therapy (HDR) or linac-based megavoltage machines to perform pre-clinical cell and mouse experiments. Then we used these devices to deliver radiation to AID-positive and AID-silenced cancer cells or tumors formed by these cells in mice. Cells and mice bearing tumors received the same dose under the same experimental conditions. For cells, we observed the apoptosis and the cell survival rate over time. For mice bearing tumors, we measured and recorded the tumor sizes every other day for 4 weeks. Results: For cell experiments, we found that the AID-positive cells underwent much less apoptosis compared with AID-silenced cells upon radiation. And for mouse experiments, we found that AID-positive tumors grew significantly faster than the AID-silenced tumors despite of receiving the same doses of radiation. Conclusion: Our study suggests that AID may confer cancer resistance to radiation therapy, and AID may be a significant biomarker predicting cancer resistance to radiation therapy for certain cancer types

  7. SU-C-303-01: Activation-Induced Cytidine Deaminase Confers Cancer Resistance to Radiation Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Yi, S [Sun Yat-Sen University, Guangzhou, Guangdong (China); La Count, S [Wittenberg University, Springfield, OH (United States); Liu, J; Bai, X; Lu, L [The Ohio State University, Columbus, OH (United States)

    2015-06-15

    Purpose: To study the role of activation-induced cytidine deaminase (AID) in malignant cell resistance to radiation therapy. Methods: We first developed several small devices that could be used to adopt radiation beams from clinical high dose rate brachy therapy (HDR) or linac-based megavoltage machines to perform pre-clinical cell and mouse experiments. Then we used these devices to deliver radiation to AID-positive and AID-silenced cancer cells or tumors formed by these cells in mice. Cells and mice bearing tumors received the same dose under the same experimental conditions. For cells, we observed the apoptosis and the cell survival rate over time. For mice bearing tumors, we measured and recorded the tumor sizes every other day for 4 weeks. Results: For cell experiments, we found that the AID-positive cells underwent much less apoptosis compared with AID-silenced cells upon radiation. And for mouse experiments, we found that AID-positive tumors grew significantly faster than the AID-silenced tumors despite of receiving the same doses of radiation. Conclusion: Our study suggests that AID may confer cancer resistance to radiation therapy, and AID may be a significant biomarker predicting cancer resistance to radiation therapy for certain cancer types.

  8. Proceedings of the 1999 Review Conference on Fuel Cell Technology

    Energy Technology Data Exchange (ETDEWEB)

    None Available

    2000-06-05

    The 1999 Review Conference on Fuel Cell Technology was jointly sponsored by the U.S. Department of Energy, Federal Energy Technology Center (FETC), the Gas Research Institute (GRI), and the Electric Power Research Institute (EPRI). It was held August 3 to 5 in Chicago, Illinois. The goal of this conference was to provide a forum for reviewing fuel cell research and development (R&D) programs, assist in strategic R&D planning, promote awareness of sponsor activities, and enhance interactions between manufacturers, researchers, and stakeholders. This conference was attended by over 250 representatives from industry, academia, national laboratories, gas and electric utilities, DOE, and other Government agencies. The conference agenda included a keynote session, five presentation sessions, a poster presentation reception, and three breakout sessions. The presentation session topics were DOD Fuel Cell Applications, Low-Temperature Fuel Cell Manufacturers, Low-Temperature Component Research, High-Temperature Fuel Cell Manufacturers, and High-Temperature Component Research; the breakout session topics were Future R&D Directions for Low-Temperature Fuel Cells, Future R&D Directions for High-Temperature Fuel Cells, and a plenary summary session. All sessions were well attended.

  9. Interferon-gamma confers resistance to experimental allergic encephalomyelitis

    DEFF Research Database (Denmark)

    Krakowski, M; Owens, T

    1996-01-01

    strains of mice are resistant to EAE. We have studied the effect of deletion of IFN-gamma on the ability to induce EAE in resistant BALB/c-backcrossed mice. As expected, only 0-6% of BALB/c or BALB/c-backcrossed mice developed EAE when immunized with myelin basic protein in adjuvant. Strikingly...

  10. A pigeonpea gene confers resistance to Asian soybean rust in soybean.

    Science.gov (United States)

    Kawashima, Cintia G; Guimarães, Gustavo Augusto; Nogueira, Sônia Regina; MacLean, Dan; Cook, Doug R; Steuernagel, Burkhard; Baek, Jongmin; Bouyioukos, Costas; Melo, Bernardo do V A; Tristão, Gustavo; de Oliveira, Jamile Camargos; Rauscher, Gilda; Mittal, Shipra; Panichelli, Lisa; Bacot, Karen; Johnson, Ebony; Iyer, Geeta; Tabor, Girma; Wulff, Brande B H; Ward, Eric; Rairdan, Gregory J; Broglie, Karen E; Wu, Gusui; van Esse, H Peter; Jones, Jonathan D G; Brommonschenkel, Sérgio H

    2016-06-01

    Asian soybean rust (ASR), caused by the fungus Phakopsora pachyrhizi, is one of the most economically important crop diseases, but is only treatable with fungicides, which are becoming less effective owing to the emergence of fungicide resistance. There are no commercial soybean cultivars with durable resistance to P. pachyrhizi, and although soybean resistance loci have been mapped, no resistance genes have been cloned. We report the cloning of a P. pachyrhizi resistance gene CcRpp1 (Cajanus cajan Resistance against Phakopsora pachyrhizi 1) from pigeonpea (Cajanus cajan) and show that CcRpp1 confers full resistance to P. pachyrhizi in soybean. Our findings show that legume species related to soybean such as pigeonpea, cowpea, common bean and others could provide a valuable and diverse pool of resistance traits for crop improvement. PMID:27111723

  11. Physiological, biochemical and molecular characterization of an induced mutation conferring imidazolinone resistance in wheat.

    Science.gov (United States)

    Jimenez, Francisco; Rojano-Delgado, Antonia M; Fernández, Pablo Tomas; Rodríguez-Suárez, Cristina; Atienza, Sergio G; De Prado, Rafael

    2016-09-01

    The Clearfield(®) wheat cultivars possessing imidazolinone (IMI)-resistant traits provide an efficient option for controlling weeds. The imazamox-resistant cultivar Pantera (Clearfield(®) ) was compared with a susceptible cultivar (Gazul). Target and non-target mechanisms of resistance were studied to characterize the resistance of Pantera and to identify the importance of each mechanism involved in this resistance. Pantera is resistant to imazamox as was determined in previous experiments. The molecular study confirmed that it carries a mutation Ser-Asn627 conferring resistance to imazamox in two out of three acetolactate synthase (ALS) genes (imi1 and imi2), located in wheat on chromosomes 6B and 6D, respectively. However, the last gene (imi3) located on chromosome 6A does not carry any mutation conferring resistance. As a result, photosynthetic activity and chlorophyll content were reduced after imazamox treatment. Detoxification was higher in the resistant biotype as shown by metabolomic study while imazamox translocation was higher in the susceptible cultivar. Interestingly, imazamox metabolism was higher at higher doses of herbicide, which suggests that the detoxification process is an inducible mechanism in which the upregulation of key gene coding for detoxification enzymes could play an important role. Thus, the identification of cultivars with a higher detoxification potential would allow the development of more resistant varieties. PMID:26991509

  12. Characterization of Halomonas Varabilis Strain HTG7 Conferring Glyphosate Resistance

    Institute of Scientific and Technical Information of China (English)

    Liu Zhu(刘柱); Liang Aimin; Ping Shuzhen; Zhang Wei; Chen Ming; Yang Zhirong; Lin Min

    2004-01-01

    Bcterial strain HTG7 is isolated from extremely glyphosate-polluted soil. It is identified as Halomonas Varabilis. It can tolerate in 500 m mol/L glyphosate concentration. Physiological characterization of strain HTG7 shows that the optimum pH and temperature are 7.0 and 30℃, respectively. It grows well in the NaCl concentrations ranging from 0% to 10%. A plasmid pACYC184 carrying a 3.5 kb DNA fragment, which confers increased glyphosate tolerance, is cloned. The DNA fragment is able to complement with an E.coli auxotrophic aroA mutant.

  13. Lung-specific loss of the laminin α3 subunit confers resistance to mechanical injury.

    Science.gov (United States)

    Urich, Daniela; Eisenberg, Jessica L; Hamill, Kevin J; Takawira, Desire; Chiarella, Sergio E; Soberanes, Saul; Gonzalez, Angel; Koentgen, Frank; Manghi, Tomas; Hopkinson, Susan B; Misharin, Alexander V; Perlman, Harris; Mutlu, Gokhan M; Budinger, G R Scott; Jones, Jonathan C R

    2011-09-01

    Laminins are heterotrimeric glycoproteins of the extracellular matrix that are secreted by epithelial cells and which are crucial for the normal structure and function of the basement membrane. We have generated a mouse harboring a conditional knockout of α3 laminin (Lama3(fl/fl)), one of the main laminin subunits in the lung basement membrane. At 60 days after intratracheal treatment of adult Lama3(fl/fl) mice with an adenovirus encoding Cre recombinase (Ad-Cre), the protein abundance of α3 laminin in whole lung homogenates was more than 50% lower than that in control-treated mice, suggesting a relatively long half-life for the protein in the lung. Upon exposure to an injurious ventilation strategy (tidal volume of 35 ml per kg of body weight for 2 hours), the mice with a knockdown of the α3 laminin subunit had less severe injury, as shown by lung mechanics, histology, alveolar capillary permeability and survival when compared with Ad-Null-treated mice. Knockdown of the α3 laminin subunit resulted in evidence of lung inflammation. However, this did not account for their resistance to mechanical ventilation. Rather, the loss of α3 laminin was associated with a significant increase in the collagen content of the lungs. We conclude that the loss of α3 laminin in the alveolar epithelium results in an increase in lung collagen, which confers resistance to mechanical injury. PMID:21878500

  14. Identification of wheat-Thinopyrum intermedium alien disomic addition lines conferring resistance to stripe rust

    Science.gov (United States)

    Thinopyrum intermedium carries many useful traits for wheat genetic improvement. To identify genes conferring resistance to stripe rust caused by Puccinia striiformis f. sp. tritici in Zhong 4 (Z4) derived from a cross between common wheat and Th. intermedium, a cross was made between Z4 and a ‘Chin...

  15. Proceedings of the CERI 2005 electricity conference : markets, integration, resistance

    International Nuclear Information System (INIS)

    This conference was attended by power industry decision makers who face continuing challenges regarding changes in electricity market mechanisms, pricing options, and power generation and transmission alternatives. It provided an opportunity to review energy markets in North American with particular reference to supply and demand and opportunities for traditional or new generation technologies based on renewable energy sources including wind powered generation. The presentations focused on transmission issues, market design and capacity issues as well as market power and pricing. The integration of wind energy into the power grid as a measure to diversity the power generation portfolio in North America was also discussed along with hydrothermal synergies and interconnections. The role of wind, coal and nuclear power in future North American energy markets was also discussed along with their environmental consequences. tabs., figs

  16. Elicitin recognition confers enhanced resistance to Phytophthora infestans in potato

    NARCIS (Netherlands)

    Du, J.; Verzaux, E.C.; Chaparro-Garcia, A.; Bijsterbosch, G.; Keizer, L.C.P.; Zhou, J.; Liebrand, T.W.H.; Xie, C.; Govers, F.; Robatzek, S.; Vossen, van der E.A.G.; Jacobsen, E.; Visser, R.G.F.; Kamoun, S.; Vleeshouwers, V.G.A.A.

    2015-01-01

    Potato late blight, caused by the destructive Irish famine pathogen Phytophthora infestans, is a major threat to global food security1,2. All late blight resistance genes identified to date belong to the coiled-coil, nucleotide-binding, leucine-rich repeat class of intracellular immune receptors3. H

  17. Conference scene: pharmacogenomics: from cell to clinic (part 2).

    Science.gov (United States)

    Siest, Gérard; Medeiros, Rui; Melichar, Bohuslav; Stathopoulou, Maria; Van Schaik, Ron Hn; Cacabelos, Ramon; Abt, Peter Meier; Monteiro, Carolino; Gurwitz, David; Queiroz, Jao; Mota-Filipe, Helder; Ndiaye, Ndeye Coumba; Visvikis-Siest, Sophie

    2014-04-01

    Second International ESPT Meeting Lisbon, Portugal, 26-28 September 2013 The second European Society of Pharmacogenomics and Theranostics (ESPT) conference was organized in Lisbon, Portugal, and attracted 250 participants from 37 different countries. The participants could listen to 50 oral presentations, participate in five lunch symposia and were able to view 83 posters and an exhibition. Part 1 of this Conference Scene was presented in the previous issue of Pharmacogenomics. This second part will focus on: clinical implementation of pharmacogenomics tests; transporters and pharmacogenomics; stem cells and other new tools for pharmacogenomics and drug discovery; from system pharmacogenomics to personalized medicine; and, finally, we will discuss the Posters and Awards that were presented at the conference.

  18. The 2NS Translocation from Aegilops ventricosa Confers Resistance to the Triticum Pathotype of Magnaporthe oryzae

    Science.gov (United States)

    Cruz, C.D.; Peterson, G.L.; Bockus, W.W.; Kankanala, P.; Dubcovsky, J.; Jordan, K.W.; Akhunov, E.; Chumley, F.; Baldelomar, F.D.; Valent, B.

    2016-01-01

    Wheat blast is a serious disease caused by the fungus Magnaporthe oryzae (Triticum pathotype) (MoT). The objective of this study was to determine the effect of the 2NS translocation from Aegilops ventricosa (Zhuk.) Chennav on wheat head and leaf blast resistance. Disease phenotyping experiments were conducted in growth chamber, greenhouse, and field environments. Among 418 cultivars of wheat (Triticum aestivum L.), those with 2NS had 50.4 to 72.3% less head blast than those without 2NS when inoculated with an older MoT isolate under growth chamber conditions. When inoculated with recently collected isolates, cultivars with 2NS had 64.0 to 80.5% less head blast. Under greenhouse conditions when lines were inoculated with an older MoT isolate, those with 2NS had a significant head blast reduction. With newer isolates, not all lines with 2NS showed a significant reduction in head blast, suggesting that the genetic background and/or environment may influence the expression of any resistance conferred by 2NS. However, when near-isogenic lines (NILs) with and without 2NS were planted in the field, there was strong evidence that 2NS conferred resistance to head blast. Results from foliar inoculations suggest that the resistance to head infection that is imparted by the 2NS translocation does not confer resistance to foliar disease. In conclusion, the 2NS translocation was associated with significant reductions in head blast in both spring and winter wheat.

  19. Conference on the structure and model of the first cell. The Alexander Ivanovich Oparin 100th Anniversary Conference

    International Nuclear Information System (INIS)

    The report includes 17 summaries of the papers presented at the Third Trieste Conference on Chemical Evolution concerning the structure and model of the first cell which was the central theme of the conference. A separate indexing is provided for each summary. Refs and figs

  20. The Batten disease gene CLN3 confers resistance to endoplasmic reticulum stress induced by tunicamycin

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Dan, E-mail: danw@bjmu.edu.cn [Department of Medical Genetics, Peking University Health Science Center, No 38 Xueyuan Road, Haidian district, Beijing 100191 (China); Liu, Jing; Wu, Baiyan [Department of Medical Genetics, Peking University Health Science Center, No 38 Xueyuan Road, Haidian district, Beijing 100191 (China); Tu, Bo; Zhu, Weiguo [Department of Biochemistry and Molecular Biology, Peking University Health Science Center, No 38 Xueyuan Road, Haidian district, Beijing 100191 (China); Luo, Jianyuan, E-mail: jluo@som.umaryland.edu [Department of Medical Genetics, Peking University Health Science Center, No 38 Xueyuan Road, Haidian district, Beijing 100191 (China); Department of Medical and Research Technology, School of Medicine, University of Maryland, Baltimore 21201 (United States)

    2014-04-25

    Highlights: • The work reveals a protective properties of CLN3 towards TM-induced apoptosis. • CLN3 regulates expression of the GRP78 and the CHOP in response to the ER stress. • CLN3 plays a specific role in the ERS response. - Abstract: Mutations in CLN3 gene cause juvenile neuronal ceroid lipofuscinosis (JNCL or Batten disease), an early-onset neurodegenerative disorder that is characterized by the accumulation of ceroid lipofuscin within lysosomes. The function of the CLN3 protein remains unclear and is presumed to be related to Endoplasmic reticulum (ER) stress. To investigate the function of CLN3 in the ER stress signaling pathway, we measured proliferation and apoptosis in cells transfected with normal and mutant CLN3 after treatment with the ER stress inducer tunicamycin (TM). We found that overexpression of CLN3 was sufficient in conferring increased resistance to ER stress. Wild-type CLN3 protected cells from TM-induced apoptosis and increased cell proliferation. Overexpression of wild-type CLN3 enhanced expression of the ER chaperone protein, glucose-regulated protein 78 (GRP78), and reduced expression of the proapoptotic protein CCAAT/-enhancer-binding protein homologous protein (CHOP). In contrast, overexpression of mutant CLN3 or siRNA knockdown of CLN3 produced the opposite effect. Together, our data suggest that the lack of CLN3 function in cells leads to a failure of management in the response to ER stress and this may be the key deficit in JNCL that causes neuronal degeneration.

  1. Angiotensin II Removes Kidney Resistance Conferred by Ischemic Preconditioning

    Directory of Open Access Journals (Sweden)

    Hee-Seong Jang

    2014-01-01

    Full Text Available Ischemic preconditioning (IPC by ischemia/reperfusion (I/R renders resistance to the kidney. Strong IPC triggers kidney fibrosis, which is involved in angiotensin II (AngII and its type 1 receptor (AT1R signaling. Here, we investigated the role of AngII/AT1R signal pathway in the resistance of IPC kidneys to subsequent I/R injury. IPC of kidneys was generated by 30 minutes of bilateral renal ischemia and 8 days of reperfusion. Sham-operation was performed to generate control (non-IPC mice. To examine the roles of AngII and AT1R in IPC kidneys to subsequent I/R, IPC kidneys were subjected to either 30 minutes of bilateral kidney ischemia or sham-operation following treatment with AngII, losartan (AT1R blocker, or AngII plus losartan. IPC kidneys showed fibrotic changes, decreased AngII, and increased AT1R expression. I/R dramatically increased plasma creatinine concentrations in non-IPC mice, but not in IPC mice. AngII treatment in IPC mice resulted in enhanced morphological damage, oxidative stress, and inflammatory responses, with functional impairment, whereas losartan treatment reversed these effects. However, AngII treatment in non-IPC mice did not change I/R-induced injury. AngII abolished the resistance of IPC kidneys to subsequent I/R via the enhancement of oxidative stress and inflammatory responses, suggesting that the AngII/AT1R signaling pathway is associated with outcome in injury-experienced kidney.

  2. Mast cells control insulitis and increase Treg cells to confer protection against STZ-induced type 1 diabetes in mice.

    Science.gov (United States)

    Carlos, Daniela; Yaochite, Juliana N U; Rocha, Fernanda A; Toso, Vanina D; Malmegrim, Kelen C R; Ramos, Simone G; Jamur, Maria C; Oliver, Constance; Camara, Niels O; Andrade, Marcus V M; Cunha, Fernando Q; Silva, João S

    2015-10-01

    Quantitative alterations in mast cell numbers in pancreatic lymph nodes (PLNs) have been reported to be associated with type 1 diabetes (T1D) progression, but their potential role during T1D remains unclear. In this study, we evaluated the role of mast cells in T1D induced by multiple low-dose streptozotocin (MLD-STZ) treatments, using two strains of mast cell-deficient mice (W/W(v) or Wsh/Wsh) and the adoptive transfer of mast cells. Mast cell deficient mice developed severe insulitis and accelerated hyperglycemia, with 100% of mice becoming diabetic compared to their littermates. In parallel, these diabetic mice had decreased numbers of T regulatory (Treg) cells in the PLNs. Additionally, mast cell deficiency caused a significant reduction in IL-10, TGF-β, and IL-6 expression in the pancreatic tissue. Interestingly, IL-6-deficient mice are more susceptible to T1D associated with reduced Treg-cell numbers in the PLNs, but mast cell transfer from wild-type mice induced protection to T1D in these mice. Finally, mast cell adoptive transfer prior to MLD-STZ administration conferred resistance to T1D, promoted increased Treg cells, and decreased IL-17-producing T cells in the PLNs. Taken together, our results indicate that mast cells are implicated in resistance to STZ-induced T1D via an immunological tolerance mechanism mediated by Treg cells. PMID:26234742

  3. Non-recessive Bt toxin resistance conferred by an intracellular cadherin mutation in field-selected populations of cotton bollworm.

    Directory of Open Access Journals (Sweden)

    Haonan Zhang

    Full Text Available Transgenic crops producing Bacillus thuringiensis (Bt toxins have been planted widely to control insect pests, yet evolution of resistance by the pests can reduce the benefits of this approach. Recessive mutations in the extracellular domain of toxin-binding cadherin proteins that confer resistance to Bt toxin Cry1Ac by disrupting toxin binding have been reported previously in three major lepidopteran pests, including the cotton bollworm, Helicoverpa armigera. Here we report a novel allele from cotton bollworm with a deletion in the intracellular domain of cadherin that is genetically linked with non-recessive resistance to Cry1Ac. We discovered this allele in each of three field-selected populations we screened from northern China where Bt cotton producing Cry1Ac has been grown intensively. We expressed four types of cadherin alleles in heterologous cell cultures: susceptible, resistant with the intracellular domain mutation, and two complementary chimeric alleles with and without the mutation. Cells transfected with each of the four cadherin alleles bound Cry1Ac and were killed by Cry1Ac. However, relative to cells transfected with either the susceptible allele or the chimeric allele lacking the intracellular domain mutation, cells transfected with the resistant allele or the chimeric allele containing the intracellular domain mutation were less susceptible to Cry1Ac. These results suggest that the intracellular domain of cadherin is involved in post-binding events that affect toxicity of Cry1Ac. This evidence is consistent with the vital role of the intracellular region of cadherin proposed by the cell signaling model of the mode of action of Bt toxins. Considered together with previously reported data, the results suggest that both pore formation and cell signaling pathways contribute to the efficacy of Bt toxins.

  4. Dissection of two soybean QTL conferring partial resistance to Phytophthora sojae through sequence and gene expression analysis

    Directory of Open Access Journals (Sweden)

    Wang Hehe

    2012-08-01

    Full Text Available Abstract Background Phytophthora sojae is the primary pathogen of soybeans that are grown on poorly drained soils. Race-specific resistance to P. sojae in soybean is gene-for-gene, although in many areas of the US and worldwide there are populations that have adapted to the most commonly deployed resistance to P. sojae ( Rps genes. Hence, this system has received increased attention towards identifying mechanisms and molecular markers associated with partial resistance to this pathogen. Several quantitative trait loci (QTL have been identified in the soybean cultivar ‘Conrad’ that contributes to the expression of partial resistance to multiple P. sojae isolates. Results In this study, two of the Conrad QTL on chromosome 19 were dissected through sequence and expression analysis of genes in both resistant (Conrad and susceptible (‘Sloan’ genotypes. There were 1025 single nucleotide polymorphisms (SNPs in 87 of 153 genes sequenced from Conrad and Sloan. There were 304 SNPs in 54 genes sequenced from Conrad compared to those from both Sloan and Williams 82, of which 11 genes had SNPs unique to Conrad. Eleven of 19 genes in these regions analyzed with qRT-PCR had significant differences in fold change of transcript abundance in response to infection with P. sojae in lines with QTL haplotype from the resistant parent compared to those with the susceptible parent haplotype. From these, 8 of the 11 genes had SNPs in the upstream, untranslated region, exon, intron, and/or downstream region. These 11 candidate genes encode proteins potentially involved in signal transduction, hormone-mediated pathways, plant cell structural modification, ubiquitination, and basal resistance. Conclusions These findings may indicate a complex defense network with multiple mechanisms underlying these two soybean QTL conferring resistance to P. sojae. SNP markers derived from these candidate genes can contribute to fine mapping of QTL and marker assisted breeding for

  5. Mitochondrial respiratory modifiers confer survival advantage by facilitating DNA repair in cancer cells

    International Nuclear Information System (INIS)

    High rate of aerobic glycolysis (Warburg effect), one of the primary hallmarks of cancer cells, acquired during the multistep development of tumors is also responsible for therapeutic resistance. Underlying this hallmark is the compromised respiratory metabolism that contributes to the acquisition of the glycolytic phenotype for sustained ATP production and cell proliferation. Nevertheless, the exact mechanisms underlying the glycolysis-linked radio-resistance in cancer cells remain elusive. In this study, we transiently elevated glycolysis by treating human cell lines (HEK293, BMG-1 and OCT-1) with mitochondrial respiratory modifiers (MRMs) viz. 2,4-dinitrophenol, Photosan-3, and Methylene blue to examine if transient stimulation of glycolysis before irradiation using MRMs is sufficient to confer radioresistance. Treatment with MRMs led to a significant (two-fold) increase in glucose consumption and lactate production together with a robust increase in the protein levels of two key regulators of glucose metabolism, i.e. GLUT-1 and HK-II. MRMs also enhanced the clonogenic survival and facilitated DNA repair by activating both non-homologous end joining (NHEJ) and homologous recombination (HR) pathways of DNA double strand break repair leading to reduction in radiation-induced cytogenetic damage (micronuclei formation) in these cells. Inhibition of glucose uptake by inhibitors like 2-deoxy-D-glucose (2-DG), 3-bromo pyruvate (3-BP) and fasentin under conditions of stimulated glycolysis not only reversed the effect but also sensitized the cells to radiation more profoundly. The inhibition of glycolysis using 2-DG also reduced the levels of Ku 70 (NHEJ) and Rad-51 (HR) proteins. Thus, our results suggest that enhanced glycolysis in cancer cells may confer radio-resistance and offers survival advantage partly by enhancing the repair of DNA damage. (author)

  6. A Novel Glycolipid Biosurfactant Confers Grazing Resistance upon Pantoea ananatis BRT175 against the Social Amoeba Dictyostelium discoideum.

    Science.gov (United States)

    Smith, Derek D N; Nickzad, Arvin; Déziel, Eric; Stavrinides, John

    2016-01-01

    Pantoea is a versatile genus of bacteria with both plant- and animal-pathogenic strains, some of which have been suggested to cause human infections. There is, however, limited knowledge on the potential determinants used for host association and pathogenesis in animal systems. In this study, we used the model host Dictyostelium discoideum to show that isolates of Pantoea ananatis exhibit differential grazing susceptibility, with some being resistant to grazing by the amoebae. We carried out a high-throughput genetic screen of one grazing-resistant isolate, P. ananatis BRT175, using the D. discoideum pathosystem to identify genes responsible for the resistance phenotype. Among the 26 candidate genes involved in grazing resistance, we identified rhlA and rhlB, which we show are involved in the biosynthesis of a biosurfactant that enables swarming motility in P. ananatis BRT175. Using liquid chromatography-mass spectrometry (LC-MS), the biosurfactant was shown to be a glycolipid with monohexose-C10-C10 as the primary congener. We show that this novel glycolipid biosurfactant is cytotoxic to the amoebae and is capable of compromising cellular integrity, leading to cell lysis. The production of this biosurfactant may be important for bacterial survival in the environment and could contribute to the establishment of opportunistic infections. IMPORTANCE The genetic factors used for host interaction by the opportunistic human pathogen Pantoea ananatis are largely unknown. We identified two genes that are important for the production of a biosurfactant that confers grazing resistance against the social amoeba Dictyostelium discoideum. We show that the biosurfactant, which exhibits cytotoxicity toward the amoebae, is a glycolipid that incorporates a hexose rather than rhamnose. The production of this biosurfactant may confer a competitive advantage in the environment and could potentially contribute to the establishment of opportunistic infections. PMID:27303689

  7. Genetic transformation of deciduous fruit trees conferring resistance against diseases

    International Nuclear Information System (INIS)

    Long breeding cycles make cultivar development a lengthy process in deciduous fruit species. Gene transfer is, accordingly, a goal with significant commercial value. In many plant species, especially in woody plants, a prerequisite for genetic engineering is the ability to regenerate plants from transformed cells. Development of single cell regeneration is the first step towards exploration of gene transfer techniques. In this investigation media for plum and apple leaf disk regeneration were developed. Transformation experiments were performed. The vector EHA105 containing the gus-intron gene was found to be effective for gene transfer. Induction of the virG genes with aceto-syringone did not enhance transformation. Cefotaxime that was supplemented in the plum selection medium to suppress the Agrobacterium vector seriously inhibited leaf disk regeneration. However, in applies it was not detrimental. With further apple transformation experiments, factors such as preculturing, age of leaves, sucrose and cefotaxime concentrations did not increase the transformation efficiency of the marker gene. The harpin protein, essential for the pathogenicity of Pseudomonas syringae pv. syringae which incites bacterial canker of stone fruit, ws amplified and cloned into an expression vector. The fusion protein was purified. This will be used in future studies to elucidate the host-pathogen interaction, and to identify antibacterial genes. (author)

  8. Non-injurious neonatal hypoxia confers resistance to brain senescence in aged male rats.

    Directory of Open Access Journals (Sweden)

    Nicolas Martin

    Full Text Available Whereas brief acute or intermittent episodes of hypoxia have been shown to exert a protective role in the central nervous system and to stimulate neurogenesis, other studies suggest that early hypoxia may constitute a risk factor that influences the future development of mental disorders. We therefore investigated the effects of a neonatal "conditioning-like" hypoxia (100% N₂, 5 min on the brain and the cognitive outcomes of rats until 720 days of age (physiologic senescence. We confirmed that such a short hypoxia led to brain neurogenesis within the ensuing weeks, along with reduced apoptosis in the hippocampus involving activation of Erk1/2 and repression of p38 and death-associated protein (DAP kinase. At 21 days of age, increased thicknesses and cell densities were recorded in various subregions, with strong synapsin activation. During aging, previous exposure to neonatal hypoxia was associated with enhanced memory retrieval scores specifically in males, better preservation of their brain integrity than controls, reduced age-related apoptosis, larger hippocampal cell layers, and higher expression of glutamatergic and GABAergic markers. These changes were accompanied with a marked expression of synapsin proteins, mainly of their phosphorylated active forms which constitute major players of synapse function and plasticity, and with increases of their key regulators, i.e. Erk1/2, the transcription factor EGR-1/Zif-268 and Src kinase. Moreover, the significantly higher interactions between PSD-95 scaffolding protein and NMDA receptors measured in the hippocampus of 720-day-old male animals strengthen the conclusion of increased synaptic functional activity and plasticity associated with neonatal hypoxia. Thus, early non-injurious hypoxia may trigger beneficial long term effects conferring higher resistance to senescence in aged male rats, with a better preservation of cognitive functions.

  9. An atypical kinase under balancing selection confers broad-spectrum disease resistance in Arabidopsis.

    Directory of Open Access Journals (Sweden)

    Carine Huard-Chauveau

    Full Text Available The failure of gene-for-gene resistance traits to provide durable and broad-spectrum resistance in an agricultural context has led to the search for genes underlying quantitative resistance in plants. Such genes have been identified in only a few cases, all for fungal or nematode resistance, and encode diverse molecular functions. However, an understanding of the molecular mechanisms of quantitative resistance variation to other enemies and the associated evolutionary forces shaping this variation remain largely unknown. We report the identification, map-based cloning and functional validation of QRX3 (RKS1, Resistance related KinaSe 1, conferring broad-spectrum resistance to Xanthomonas campestris (Xc, a devastating worldwide bacterial vascular pathogen of crucifers. RKS1 encodes an atypical kinase that mediates a quantitative resistance mechanism in plants by restricting bacterial spread from the infection site. Nested Genome-Wide Association mapping revealed a major locus corresponding to an allelic series at RKS1 at the species level. An association between variation in resistance and RKS1 transcription was found using various transgenic lines as well as in natural accessions, suggesting that regulation of RKS1 expression is a major component of quantitative resistance to Xc. The co-existence of long lived RKS1 haplotypes in A. thaliana is shared with a variety of genes involved in pathogen recognition, suggesting common selective pressures. The identification of RKS1 constitutes a starting point for deciphering the mechanisms underlying broad spectrum quantitative disease resistance that is effective against a devastating and vascular crop pathogen. Because putative RKS1 orthologous have been found in other Brassica species, RKS1 provides an exciting opportunity for plant breeders to improve resistance to black rot in crops.

  10. Heterologous expression of a Tpo1 homolog from Arabidopsis thaliana confers resistance to the herbicide 2,4-D and other chemical stresses in yeast.

    Science.gov (United States)

    Cabrito, Tânia R; Teixeira, Miguel C; Duarte, Alexandra A; Duque, Paula; Sá-Correia, Isabel

    2009-10-01

    The understanding of the molecular mechanisms underlying acquired herbicide resistance is crucial in dealing with the emergence of resistant weeds. Saccharomyces cerevisiae has been used as a model system to gain insights into the mechanisms underlying resistance to the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). The TPO1 gene, encoding a multidrug resistance (MDR) plasma membrane transporter of the major facilitator superfamily (MFS), was previously found to confer resistance to 2,4-D in yeast and to be transcriptionally activated in response to the herbicide. In this work, we demonstrate that Tpo1p is required to reduce the intracellular concentration of 2,4-D. ScTpo1p homologs encoding putative plasma membrane MFS transporters from the plant model Arabidopsis thaliana were analyzed for a possible role in 2,4-D resistance. At5g13750 was chosen for further analysis, as its transcript levels were found to increase in 2,4-D stressed plants. The functional heterologous expression of this plant open reading frame in yeast was found to confer increased resistance to the herbicide in Deltatpo1 and wild-type cells, through the reduction of the intracellular concentration of 2,4-D. Heterologous expression of At5g13750 in yeast also leads to increased resistance to indole-3-acetic acid (IAA), Al(3+) and Tl(3+). At5g13750 is the first plant putative MFS transporter to be suggested as possibly involved in MDR.

  11. Upregulation of AKT3 Confers Resistance to the AKT Inhibitor MK2206 in Breast Cancer.

    Science.gov (United States)

    Stottrup, Casey; Tsang, Tiffany; Chin, Y Rebecca

    2016-08-01

    Acquired resistance to molecular targeted therapy represents a major challenge for the effective treatment of cancer. Hyperactivation of the PI3K/AKT pathway is frequently observed in virtually all human malignancies, and numerous PI3K and AKT inhibitors are currently under clinical evaluation. However, mechanisms of acquired resistance to AKT inhibitors have yet to be described. Here, we use a breast cancer preclinical model to identify resistance mechanisms to a small molecule allosteric AKT inhibitor, MK2206. Using a step-wise and chronic high-dose exposure, breast cancer cell lines harboring oncogenic PI3K resistant to MK2206 were established. Using this model, we reveal that AKT3 expression is markedly upregulated in AKT inhibitor-resistant cells. Induction of AKT3 is regulated epigenetically by the bromodomain and extra terminal domain proteins. Importantly, knockdown of AKT3, but not AKT1 or AKT2, in resistant cells restores sensitivity to MK2206. AKT inhibitor-resistant cells also display an epithelial to mesenchymal transition phenotype as assessed by alterations in the levels of E-Cadherin, N-Cadherin, and vimentin, as well as enhanced invasiveness of tumor spheroids. Notably, the invasive morphology of resistant spheroids is diminished upon AKT3 depletion. We also show that resistance to MK2206 is reversible because upon drug removal resistant cells regain sensitivity to AKT inhibition, accompanied by reexpression of epithelial markers and reduction of AKT3 expression, implying that epigenetic reprogramming contributes to acquisition of resistance. These findings provide a rationale for developing therapeutics targeting AKT3 to circumvent acquired resistance in breast cancer. Mol Cancer Ther; 15(8); 1964-74. ©2016 AACR. PMID:27297869

  12. Activation tagging of ATHB13 in Arabidopsis thaliana confers broad-spectrum disease resistance.

    Science.gov (United States)

    Gao, Dongli; Appiano, Michela; Huibers, Robin P; Chen, Xi; Loonen, Annelies E H M; Visser, Richard G F; Wolters, Anne-Marie A; Bai, Yuling

    2014-12-01

    Powdery mildew species Oidium neolycopersici (On) can cause serious yield losses in tomato production worldwide. Besides on tomato, On is able to grow and reproduce on Arabidopsis. In this study we screened a collection of activation-tagged Arabidopsis mutants and identified one mutant, 3221, which displayed resistance to On, and in addition showed a reduced stature and serrated leaves. Additional disease tests demonstrated that the 3221 mutant exhibited resistance to downy mildew (Hyaloperonospora arabidopsidis) and green peach aphid (Myzus persicae), but retained susceptibility to bacterial pathogen Pseudomonas syringae pv tomato DC3000. The resistance trait and morphological alteration were mutually linked in 3221. Identification of the activation tag insertion site and microarray analysis revealed that ATHB13, a homeodomain-leucine zipper (HD-Zip) transcription factor, was constitutively overexpressed in 3221. Silencing of ATHB13 in 3221 resulted in the loss of both the morphological alteration and resistance, whereas overexpression of the cloned ATHB13 in Col-0 and Col-eds1-2 backgrounds resulted in morphological alteration and resistance. Microarray analysis further revealed that overexpression of ATHB13 influenced the expression of a large number of genes. Previously, it was reported that ATHB13-overexpressing lines conferred tolerance to abiotic stress. Together with our results, it appears that ATHB13 is involved in the crosstalk between abiotic and biotic stress resistance pathways.

  13. Toward genetic transformation of mitochondria in mammalian cells using a recoded drug-resistant selection marker

    Institute of Scientific and Technical Information of China (English)

    Young Geol Yoon; Michael Duane Koob

    2011-01-01

    Due to technical difficulties, the genetic transformation of mitochondria in mammalian cells is still a challenge. In this report, we described our attempts to transform mammalian mitochondria with an engineered mitochondrial genome based on selection using a drug resistance gene. Because the standard drug-resistant neomycin phosphotransferase confers resistance to high concentrations of G418 when targeted to the mitochondria, we generated a recoded neomycin resistance gene that uses the mammalian mitochondrial genetic code to direct the synthesis of this protein in the mitochondria, but not in the nucleus (mitochondrial version). We also generated a universal version of the recoded neomycin resistance gene that allows synthesis of the drug-resistant proteins both in the mitochondria and nucleus. When we transfected these recoded neomycin resistance genes that were incorporated into the mouse mitochondrial genome clones into mouse tissue culture cells by electroporation, no DNA constructs were delivered into the mitochondria. We found that the universal version of the recoded neomycin resistance gene was expressed in the nucleus and thus conferred drug resistance to G418 selection, while the synthetic mitochondrial version of the gene produced no background drug-resistant cells from nuclear transformation. These recoded synthetic drug-resistant genes could be a useful tool for selecting mitochondrial genetic transformants as a precise technology for mitochondrial transformation is developed.

  14. Genetic variation in plant CYP51s confers resistance against voriconazole, a novel inhibitor of brassinosteroid-dependent sterol biosynthesis.

    Directory of Open Access Journals (Sweden)

    Wilfried Rozhon

    Full Text Available Brassinosteroids (BRs are plant steroid hormones with structural similarity to mammalian sex steroids and ecdysteroids from insects. The BRs are synthesized from sterols and are essential regulators of cell division, cell elongation and cell differentiation. In this work we show that voriconazole, an antifungal therapeutic drug used in human and veterinary medicine, severely impairs plant growth by inhibiting sterol-14α-demethylation and thereby interfering with BR production. The plant growth regulatory properties of voriconazole and related triazoles were identified in a screen for compounds with the ability to alter BR homeostasis. Voriconazole suppressed growth of the model plant Arabidopsis thaliana and of a wide range of both monocotyledonous and dicotyledonous plants. We uncover that voriconazole toxicity in plants is a result of a deficiency in BRs that stems from an inhibition of the cytochrome P450 CYP51, which catalyzes a step of BR-dependent sterol biosynthesis. Interestingly, we found that the woodland strawberry Fragaria vesca, a member of the Rosaceae, is naturally voriconazole resistant and that this resistance is conferred by the specific CYP51 variant of F. vesca. The potential of voriconazole as a novel tool for plant research is discussed.

  15. Activation of RAS family members confers resistance to ROS1 targeting drugs.

    OpenAIRE

    Cargnelutti, Marilisa; Corso, Simona; Pergolizzi, Margherita; Mévellec, Laurence; Aisner, Dara L.; Dziadziuszko, Rafal; Varella-Garcia, Marileila; Comoglio, Paolo M.; Doebele, Robert C.; Vialard, Jorge; Giordano, Silvia

    2014-01-01

    The ROS1 tyrosine kinase is activated in lung cancer as a consequence of chromosomal rearrangement. Although high response rates and disease control have been observed in lung cancer patients bearing rearranged ROS1 tumors (ROS1+) treated with the kinase inhibitor crizotinib, many of these patients eventually relapse. To identify mechanisms of resistance to ROS1 inhibitors we generated resistant cells from HCC78 lung cancer cells bearing the SLC34A2-ROS1 rearrangement. We found that activatio...

  16. A Pid3 allele from rice cultivar Gumei2 confers resistance to Magnaporthe oryzae

    Institute of Scientific and Technical Information of China (English)

    Jie Chen; Yongfeng Shi; Wenzheng Liu; Rongyao Chai; Yaping Fu; Jieyun Zhuang; Jianli Wu

    2011-01-01

    Rice blast, caused by Magnaporthe oryzae, is one of the most devastating diseases. Using map-based strategy and in silico approach we isolated a new rice (Oryza sativa L.) blast resistance allele of Pid3, designated Pi25, from a stable blast resistance cultivar Gumei2. Overexpression analysis and complementation test showed that Pi25 conferred blast resistance to M. oryzae isolate js001-20. Sequence analysis showed that Pi25 was an intronless gene of 2772 nucleotides with single nucleotide substitution in comparison to Pid3 at the nucleotide position 459 and predicatively encoded a typical coiled coil-nucleotide binding site-leucine rich repeat (CC--NBS--LRR) protein of 924 amino acid residuals with 100% identity to Pid3 putative protein. The susceptible allele pi25 in Nipponbare contained a nonsense mutation at the nucleotide position 2209 resulting in a truncated protein with 736 amino acid residuals. In addition, 14 nucleotide substitutions resulting in 10 amino acid substitutions were identified between Pi25 and pi25 upstream the premature stop codon in the susceptible allele. Although the mechanism of Pi25/Pid3-mediated resistance needs to be further investigated, the isolation of the allele would facilitate the utilization of Pi25/Pid3 in rice blast resistance breeding program via transgenic approach and marker assisted selection.

  17. Vat, an Amazing Gene Conferring Resistance to Aphids and Viruses They Carry: From Molecular Structure to Field Effects

    Science.gov (United States)

    Boissot, Nathalie; Schoeny, Alexandra; Vanlerberghe-Masutti, Flavie

    2016-01-01

    We review half a century of research on Cucumis melo resistance to Aphis gossypii from molecular to field levels. The Vat gene is unique in conferring resistance to both A. gossypii and the viruses it transmits. This double phenotype is aphid clone-dependent and has been observed in 25 melon accessions, mostly from Asia. It is controlled by a cluster of genes including CC-NLR, which has been characterized in detail. Copy-number polymorphisms (for the whole gene and for a domain that stands out in the LLR region) and single-nucleotide polymorphisms have been identified in the Vat cluster. The role of these polymorphisms in plant/aphid interactions remains unclear. The Vat gene structure suggests a functioning with separate recognition and response phases. During the recognition phase, the VAT protein is thought to interact (likely indirectly) with an aphid effector introduced during cell puncture by the aphid. A few hours later, several miRNAs are upregulated in Vat plants. Peroxidase activity increases, and callose and lignin are deposited in the walls of the cells adjacent to the stylet path, disturbing aphid behavior. In aphids feeding on Vat plants, Piwi-interacting RNA-like sequences are abundant and the levels of other miRNAs are modified. At the plant level, resistance to aphids is quantitative (aphids escape the plant and display low rates of reproduction). Resistance to viruses is qualitative and local. Durability of NLR genes is highly variable. A. gossypii clones are adapted to Vat resistance, either by introducing a new effector that interferes with the deployment of plant defenses, or by adapting to the defenses it triggered. Viruses transmitted in a non-persistent manner cannot adapt to Vat resistance. At population level, Vat reduces aphid density and genetic diversity. The durability of Vat resistance to A. gossypii populations depends strongly on the agro-ecosystem, including, in particular, the presence of other cucurbit crops serving as

  18. Genetic engineering in insects: Cloning and transformation of genes conferring resistance to insecticides

    International Nuclear Information System (INIS)

    Genetic engineering and transformation offer the possibility of modifying the genetic material of insects. These techniques will make it possible, for example, to transfer genes conferring resistance to insecticides into the genome of beneficial species, or to develop new methods of combating insect pests and disease carrying insects. We cloned two genes which contain the code for proteins that detoxify insecticides. The first, esterase B1 from Culex quinquefasciatus, is amplified approximately 250 times in Californian mosquitoes resistant to organic phosphate insecticides. A second esterase gene was cloned from bacteria which break down various organic phosphates. Experiments are in progress to transfer these genes to Drosophila and beneficial insects. These same genes could also serve as selection markers for the purpose of developing transformation techniques for different insects whose genome one wishes to modify using genetic engineering techniques. (author). 5 refs

  19. Hepatitis B virus mutations potentially conferring adefovir/ tenofovir resistance in treatment-naive patients

    Institute of Scientific and Technical Information of China (English)

    Rebecca Pastor; Fran(c)ois Habersetzer; Samira Fafi-Kremer; Michel Doffo(e)l; Thomas F Baumert; Jean-Pierre Gut; Fran(c)oise Stoll-Keller; Evelyne Schvoerer

    2009-01-01

    Anti-hepatitis B virus (HBV) therapy leads to the emergence of mutant viral strains during the treatment of chronic hepatitis B with nucleos(t)ides analogues. The existence of HBV variants with primary antiviral resistance may be important for treatment choice. We studied two patients with chronic HBV infection by sequencing the HBV polymerase gene. They had adefovir- and tenofovir-related mutations in the viral polymerase, although they had never been treated. These mutations were rtV214A/rtN238T in one patient and rtA194T in the other. Thus, mutations in untreated patients deserve cautious surveillance. These data indicate that mutations that can theoretically confer adefovir or tenofovir resistance may emerge in treatmentnaive patients.

  20. Draft genome sequences of two Aeromonas salmonicida subsp. salmonicida isolates harboring plasmids conferring antibiotic resistance.

    Science.gov (United States)

    Vincent, Antony T; Tanaka, Katherine H; Trudel, Melanie V; Frenette, Michel; Derome, Nicolas; Charette, Steve J

    2015-02-01

    The bacterium Aeromonas salmonicida is the etiological agent of furunculosis, a widespread fish disease causing important economic losses to the fish farming industry. Antibiotic treatments in fish farms may be challenging given the existence of multidrug-resistant isolates of this bacterium. Here, we report the draft genome sequences of the 2004-05MF26 and 2009-144K3 isolates, which harbor plasmids conferring antibiotic resistance. Both isolates also carry the large plasmid pAsa5, which is known to encode a type three secretion system (TTSS) and the pAsal1 plasmid which has the aopP gene producing a TTSS effector. These two isolates are good representatives of the plasmid diversity in A. salmonicida subsp. salmonicida. PMID:25724776

  1. Potato R1 resistance gene confers resistance against Phytophthora infestans in transgenic tomato plants

    NARCIS (Netherlands)

    Faino, L.; Carli, P.; Testa, A.; Cristinzio, G.; Frusciante, L.; Ercolano, M.R.

    2010-01-01

    Tomato is challenged by several pathogens which cause loss of production. One such pathogen is the oomycete Phytophthora infestans which is able to attack all the aerial parts of the plant. Although a wide range of resistance sources are available, genetic control of this disease is not yet successf

  2. Multiple origins of resistance-conferring mutations in Plasmodium vivax dihydrofolate reductase

    Directory of Open Access Journals (Sweden)

    O'Neil Michael T

    2008-04-01

    Full Text Available Abstract Background In order to maximize the useful therapeutic life of antimalarial drugs, it is crucial to understand the mechanisms by which parasites resistant to antimalarial drugs are selected and spread in natural populations. Recent work has demonstrated that pyrimethamine-resistance conferring mutations in Plasmodium falciparum dihydrofolate reductase (dhfr have arisen rarely de novo, but spread widely in Asia and Africa. The origin and spread of mutations in Plasmodium vivax dhfr were assessed by constructing haplotypes based on sequencing dhfr and its flanking regions. Methods The P. vivax dhfr coding region, 792 bp upstream and 683 bp downstream were amplified and sequenced from 137 contemporary patient isolates from Colombia, India, Indonesia, Papua New Guinea, Sri Lanka, Thailand, and Vanuatu. A repeat motif located 2.6 kb upstream of dhfr was also sequenced from 75 of 137 patient isolates, and mutational relationships among the haplotypes were visualized using the programme Network. Results Synonymous and non-synonymous single nucleotide polymorphisms (SNPs within the dhfr coding region were identified, as was the well-documented in-frame insertion/deletion (indel. SNPs were also identified upstream and downstream of dhfr, with an indel and a highly polymorphic repeat region identified upstream of dhfr. The regions flanking dhfr were highly variable. The double mutant (58R/117N dhfr allele has evolved from several origins, because the 58R is encoded by at least 3 different codons. The triple (58R/61M/117T and quadruple (57L/61M/117T/173F, 57I/58R/61M/117T and 57L/58R/61M/117T mutant alleles had at least three independent origins in Thailand, Indonesia, and Papua New Guinea/Vanuatu. Conclusion It was found that the P. vivax dhfr coding region and its flanking intergenic regions are highly polymorphic and that mutations in P. vivax dhfr that confer antifolate resistance have arisen several times in the Asian region. This contrasts

  3. A Brachypodium UDP-Glycosyltransferase Confers Root Tolerance to Deoxynivalenol and Resistance to Fusarium Infection.

    Science.gov (United States)

    Pasquet, Jean-Claude; Changenet, Valentin; Macadré, Catherine; Boex-Fontvieille, Edouard; Soulhat, Camille; Bouchabké-Coussa, Oumaya; Dalmais, Marion; Atanasova-Pénichon, Vessela; Bendahmane, Abdelhafid; Saindrenan, Patrick; Dufresne, Marie

    2016-09-01

    Fusarium head blight (FHB) is a cereal disease caused by Fusarium graminearum, a fungus able to produce type B trichothecenes on cereals, including deoxynivalenol (DON), which is harmful for humans and animals. Resistance to FHB is quantitative, and the mechanisms underlying resistance are poorly understood. Resistance has been related to the ability to conjugate DON into a glucosylated form, deoxynivalenol-3-O-glucose (D3G), by secondary metabolism UDP-glucosyltransferases (UGTs). However, functional analyses have never been performed within a single host species. Here, using the model cereal species Brachypodium distachyon, we show that the Bradi5g03300 UGT converts DON into D3G in planta. We present evidence that a mutation in Bradi5g03300 increases root sensitivity to DON and the susceptibility of spikes to F. graminearum, while overexpression confers increased root tolerance to the mycotoxin and spike resistance to the fungus. The dynamics of expression and conjugation suggest that the speed of DON conjugation rather than the increase of D3G per se is a critical factor explaining the higher resistance of the overexpressing lines. A detached glumes assay showed that overexpression but not mutation of the Bradi5g03300 gene alters primary infection by F. graminearum, highlighting the involvement of DON in early steps of infection. Together, these results indicate that early and efficient UGT-mediated conjugation of DON is necessary and sufficient to establish resistance to primary infection by F. graminearum and highlight a novel strategy to promote FHB resistance in cereals. PMID:27378816

  4. Cell shunt resistance and photovoltaic module performance

    Energy Technology Data Exchange (ETDEWEB)

    McMahon, T.J.; Basso, T.S.; Rummel, S.R. [National Renewable Energy Lab., Golden, CO (United States)

    1996-05-01

    Shunt resistance of cells in photovoltaic modules can affect module power output and could indicate flawed manufacturing processes and reliability problems. The authors describe a two-terminal diagnostic method to directly measure the shunt resistance of individual cells in a series-connected module non-intrusively, without deencapsulation. Peak power efficiency vs. light intensity was measured on a 12-cell, series-connected, single crystalline module having relatively high cell shunt resistances. The module was remeasured with 0.5-, 1-, and 2-ohm resistors attached across each cell to simulate shunt resistances of several emerging technologies. Peak power efficiencies decreased dramatically at lower light levels. Using the PSpice circuit simulator, the authors verified that cell shunt and series resistances can indeed be responsible for the observed peak power efficiency vs. intensity behavior. The authors discuss the effect of basic cell diode parameters, i.e., shunt resistance, series resistance, and recombination losses, on PV module performance as a function of light intensity.

  5. Overcoming of multidrug resistance by introducing the apoptosis gene, bcl-Xs, into MRP-overexpressing drug resistant cells.

    Science.gov (United States)

    Ohi, Y; Kim, R; Toge, T

    2000-05-01

    Multidrug resistance associated protein (MRP) is one of drug transport membranes that confer multidrug resistance in cancer cells. Multidrug resistance has been known to be associated with resistance to apoptosis. In this study, using MRP overexpressing multidrug resistant nasopharyngeal cancer cells, we examined the expression of apoptosis related genes including p53, p21WAF1, bax and bcl-Xs between drug sensitive KB and its resistant KB/7D cells. We also examined whether the introduction of apoptosis related gene could increase the sensitivity to anticancer drugs in association with apoptotic cell death. The relative resistances to anticancer drugs in KB/7D cells evaluated by IC50 values were 3.6, 61.3, 10.4 and 10.5 to adriamycin (ADM), etoposide (VP-16), vincristine (VCR) and vindesine (VDS), respectively. The resistance to anticancer drugs in KB/7D cells was associated with the attenuation of internucleosomal DNA ladder formation in apoptosis. Of important, the mRNA expression of bcl-Xs gene in KB/7D cells was decreased in one-fourth as compared to that of KB cells among the apoptosis genes. The mRNA expression of bcl-Xs gene in a bcl-Xs transfected clone (KB/7Dbcl-Xs) was increased about 2-fold compared to that of KB/7Dneo cells, while the mRNA expression of MRP gene was not significantly different in KB/7bcl-Xs and KB/7Dneo cells. The sensitivities to anticancer drugs including ADM, VCR and VDS except VP-16 were increased in KB/7Dbcl-Xs cells, in turn, the relative resistance in KB/7Dbcl-Xs cells was decreased to 1.4, 4.0, and 3.0 in ADM, VCR and VDS, respectively, as compared to those of KB/7Dneo cells. Of interest, the studies on the accumulation of [3H]VCR showed that the decrease of [3H]VCR accumulation in KB/7Dbcl-Xs was not significantly different from that of KB/7Dneo cells. Collectively, these results indicated that the mechanism(s) of drug resistance in KB/7D cells could be explained at least by two factors: a) reduced drug accumulation mediated by

  6. RAD18 mediates resistance to ionizing radiation in human glioma cells

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Chen; Wang, Hongwei; Cheng, Hongbin; Li, Jianhua; Wang, Zhi, E-mail: drzwang@gmail.com; Yue, Wu, E-mail: drwuyue@gmail.com

    2014-02-28

    Highlights: • RAD18 is an important mediator of the IR-induced resistance in glioma cell lines. • RAD18 overexpression confers resistance to IR-mediated apoptosis. • The elevated expression of RAD18 is associated with recurrent GBM who underwent IR therapy. - Abstract: Radioresistance remains a major challenge in the treatment of glioblastoma multiforme (GBM). RAD18 a central regulator of translesion DNA synthesis (TLS), has been shown to play an important role in regulating genomic stability and DNA damage response. In the present study, we investigate the relationship between RAD18 and resistance to ionizing radiation (IR) and examined the expression levels of RAD18 in primary and recurrent GBM specimens. Our results showed that RAD18 is an important mediator of the IR-induced resistance in GBM. The expression level of RAD18 in glioma cells correlates with their resistance to IR. Ectopic expression of RAD18 in RAD18-low A172 glioma cells confers significant resistance to IR treatment. Conversely, depletion of endogenous RAD18 in RAD18-high glioma cells sensitized these cells to IR treatment. Moreover, RAD18 overexpression confers resistance to IR-mediated apoptosis in RAD18-low A172 glioma cells, whereas cells deficient in RAD18 exhibit increased apoptosis induced by IR. Furthermore, knockdown of RAD18 in RAD18-high glioma cells disrupts HR-mediated repair, resulting in increased accumulation of DSB. In addition, clinical data indicated that RAD18 was significantly higher in recurrent GBM samples that were exposed to IR compared with the corresponding primary GBM samples. Collectively, our findings reveal that RAD18 may serve as a key mediator of the IR response and may function as a potential target for circumventing IR resistance in human GBM.

  7. Combination of essential oils and antibiotics reduce antibiotic resistance in plasmid-conferred multidrug resistant bacteria.

    Science.gov (United States)

    Yap, Polly Soo Xi; Lim, Swee Hua Erin; Hu, Cai Ping; Yiap, Beow Chin

    2013-06-15

    In this study we investigated the relationship between several selected commercially available essential oils and beta-lactam antibiotics on their antibacterial effect against multidrug resistant bacteria. The antibacterial activity of essential oils and antibiotics was assessed using broth microdilution. The combined effects between essential oils of cinnamon bark, lavender, marjoram, tea tree, peppermint and ampicillin, piperacillin, cefazolin, cefuroxime, carbenicillin, ceftazidime, meropenem, were evaluated by means of the checkerboard method against beta-lactamase-producing Escherichia coli. In the latter assays, fractional inhibitory concentration (FIC) values were calculated to characterize interaction between the combinations. Substantial susceptibility of the bacteria toward natural antibiotics and a considerable reduction in the minimum inhibitory concentrations (MIC) of the antibiotics were noted in some paired combinations of antibiotics and essential oils. Out of 35 antibiotic-essential oil pairs tested, four of them showed synergistic effect (FIC≤0.5) and 31 pairs showed no interaction (FIC>0.5-4.0). The preliminary results obtained highlighted the occurrence of a pronounced synergistic relationship between piperacillin/cinnamon bark oil, piperacillin/lavender oil, piperacillin/peppermint oil as well as meropenem/peppermint oil against two of the three bacteria under study with a FIC index in the range 0.26-0.5. The finding highlighted the potential of peppermint, cinnamon bark and lavender essential oils being as antibiotic resistance modifying agent. Reduced usage of antibiotics could be employed as a treatment strategy to decrease the adverse effects and possibly to reverse the beta-lactam antibiotic resistance. PMID:23537749

  8. Expression of a full-length cDNA for the human MDR1 gene confers resistance to colchicine, doxorubicin, and vinblastine

    International Nuclear Information System (INIS)

    Intrinsic and acquired multidrug resistance (MDR) is an important problem in cancer therapy. MDR in human KB carcinoma cells selected for resistance to colchicine, vinblastine, or doxorubicin (former generic name adriamycin) is associated with overexpression of the MDR1 gene, which encodes P-glycoprotein. The authors previously have isolated an overlapping set of cDNA clones for the human MDR1 gene from multidrug-resistant KB cells. Here they report the construction of a full-length cDNA for the human MDR1 gene and show that this reconstructed cDNA, when inserted into a retroviral expression vector containing the long terminal repeats of Moloney leukemia virus or Harvey sarcoma virus, functions in mouse NIH 3T3 and human KB cells to confer the complete multidrug-resistance phenotype. These results suggest that the human MDR1 gene may be used as a positive selectable marker to introduce genes into human cells and to transform human cells to multidrug resistance without introducing nonhuman antigens

  9. A shift to organismal stress resistance in programmed cell death mutants.

    Directory of Open Access Journals (Sweden)

    Meredith E Judy

    Full Text Available Animals have many ways of protecting themselves against stress; for example, they can induce animal-wide, stress-protective pathways and they can kill damaged cells via apoptosis. We have discovered an unexpected regulatory relationship between these two types of stress responses. We find that C. elegans mutations blocking the normal course of programmed cell death and clearance confer animal-wide resistance to a specific set of environmental stressors; namely, ER, heat and osmotic stress. Remarkably, this pattern of stress resistance is induced by mutations that affect cell death in different ways, including ced-3 (cell death defective mutations, which block programmed cell death, ced-1 and ced-2 mutations, which prevent the engulfment of dying cells, and progranulin (pgrn-1 mutations, which accelerate the clearance of apoptotic cells. Stress resistance conferred by ced and pgrn-1 mutations is not additive and these mutants share altered patterns of gene expression, suggesting that they may act within the same pathway to achieve stress resistance. Together, our findings demonstrate that programmed cell death effectors influence the degree to which C. elegans tolerates environmental stress. While the mechanism is not entirely clear, it is intriguing that animals lacking the ability to efficiently and correctly remove dying cells should switch to a more global animal-wide system of stress resistance.

  10. MiR-197 induces Taxol resistance in human ovarian cancer cells by regulating NLK.

    Science.gov (United States)

    Zou, Dongling; Wang, Dong; Li, Rong; Tang, Ying; Yuan, Li; Long, Xingtao; Zhou, Qi

    2015-09-01

    Chemotherapy is the preferred therapeutic approach for the therapy of advanced ovarian cancer, but 5-year survival rate remains low due to the development of drug resistance. Increasing evidence has documented that microRNAs (miRNAs) act important roles in drug resistance in a variety types of cancer. However, the roles of miRNA in regulating Taxol resistance in ovarian cancer and the detailed mechanism are less reported. We used Taqman probe stem loop real-time PCR to accurately measure the levels of miR-197 in normal ovarian cells, ovarian cancer cells, and Taxol-resistant ovarian cancer cells and found that miR-197 was significantly increased in Taxol-resistant ovarian cancer cells. Enforced expression of miR-197 can promote Taxol resistance, cell proliferation, and invasion of ovarian cancer cells. Meanwhile, repression of miR-197 in ovarian cancer cells can sensitize its response to Taxol and also induced attenuated cell proliferation and invasion ability. Furthermore, investigation of the detailed mechanism showed that the promotion of miR-197 on drug resistance in ovarian cancer cells was partially mediated by downregulating NLK, a negative regulator of WNT signaling pathway. Taken together, our work first demonstrated that miR-197 can confer drug resistance to Taxol, by regulating tumor suppressor, NLK expression in ovarian cancer cells.

  11. Ultraviolet light-resistant primary transfectants of xeroderma pigmentosum cells are also DNA repair-proficient

    International Nuclear Information System (INIS)

    In a previous work, an immortal xeroderma pigmentosum cell line belonging to complementation group C was complemented to a UV-resistant phenotype by transfection with a human cDNA clone library. We now report that the primary transformants selected for UV-resistance also acquired normal levels of DNA repair. This was assessed both by measurement of UV-induced [3H]thymidine incorporation and by equilibrium sedimentation analysis of repair-DNA synthesis. Therefore, the transduced DNA element which confers normal UV-resistance also corrects the excision repair defect of the xeroderma pigmentosum group C cell line

  12. Distributed series resistance effects in solar cells

    DEFF Research Database (Denmark)

    Nielsen, Lars Drud

    1982-01-01

    A mathematical treatment is presented of the effects of one-dimensional distributed series resistance in solar cells. A general perturbation theory is developed, including consistently the induced spatial variation of diode current density and leading to a first-order equivalent lumped resistance...... to cause an effective doubling of the "diode quality factor."...

  13. Stable gene transfer of CCR5 and CXCR4 siRNAs by sleeping beauty transposon system to confer HIV-1 resistance

    Directory of Open Access Journals (Sweden)

    Akkina Ramesh

    2008-07-01

    Full Text Available Abstract Background Thus far gene therapy strategies for HIV/AIDS have used either conventional retroviral vectors or lentiviral vectors for gene transfer. Although highly efficient, their use poses a certain degree of risk in terms of viral mediated oncogenesis. Sleeping Beauty (SB transposon system offers a non-viral method of gene transfer to avoid this possible risk. With respect to conferring HIV resistance, stable knock down of HIV-1 coreceptors CCR5 and CXCR4 by the use of lentiviral vector delivered siRNAs has proved to be a promising strategy to protect cells from HIV-1 infection. In the current studies our aim is to evaluate the utility of SB system for stable gene transfer of CCR5 and CXCR4 siRNA genes to derive HIV resistant cells as a first step towards using this system for gene therapy. Results Two well characterized siRNAs against the HIV-1 coreceptors CCR5 and CXCR4 were chosen based on their previous efficacy for the SB transposon gene delivery. The siRNA transgenes were incorporated individually into a modified SB transfer plasmid containing a FACS sortable red fluorescence protein (RFP reporter and a drug selectable neomycin resistance gene. Gene transfer was achieved by co-delivery with a construct expressing a hyperactive transposase (HSB5 into the GHOST-R3/X4/R5 cell line, which expresses the major HIV receptor CD4 and and the co-receptors CCR5 and CXCR4. SB constructs expressing CCR5 or CXCR4 siRNAs were also transfected into MAGI-CCR5 or MAGI-CXCR4 cell lines, respectively. Near complete downregulation of CCR5 and CXCR4 surface expression was observed in transfected cells. During viral challenge with X4-tropic (NL4.3 or R5-tropic (BaL HIV-1 strains, the respective transposed cells showed marked viral resistance. Conclusion SB transposon system can be used to deliver siRNA genes for stable gene transfer. The siRNA genes against HIV-1 coreceptors CCR5 and CXCR4 are able to downregulate the respective cell surface proteins

  14. EmtA, a rRNA methyltransferase conferring high-level evernimicin resistance

    DEFF Research Database (Denmark)

    Mann, P. A.; Xiong, L.; Mankin, A. S.;

    2001-01-01

    Enterococcus faecium strain 9631355 was isolated from animal sources on the basis of its resistance to the growth promotant avilamycin. The strain also exhibited high-level resistance to evernimicin, a drug undergoing evaluation as a therapeutic agent in humans. Ribosomes from strain 9631355...... exhibited a dramatic reduction in evernimicin binding, shown by both cell-free translation assays and direct-binding assays. The resistance determinant was cloned from strain 9631355; sequence alignments suggested it was a methyltransferase and therefore it was designated emtA for evernimicin...

  15. Live-cell luciferase assay of drug resistant cells

    OpenAIRE

    sprotocols

    2015-01-01

    To date, multiplexing cell-based assay is essential for high-throughput screening of molecular targets. Measuring multiple parameters of a single sample increases consistency and decrease time and cost of assay. Functional assay of living cell is useful as a first step of multiplexing assay, because live-cell assay allows following second assay using cell lysate or stained cell. However, live-cell assay of drug resistant cells that are highly activated of drug efflux mechanisms is sometimes u...

  16. Molecular mechanisms of bortezomib resistant adenocarcinoma cells.

    Directory of Open Access Journals (Sweden)

    Erika Suzuki

    Full Text Available Bortezomib (Velcade™ is a reversible proteasome inhibitor that is approved for the treatment of multiple myeloma (MM. Despite its demonstrated clinical success, some patients are deprived of treatment due to primary refractoriness or development of resistance during therapy. To investigate the role of the duration of proteasome inhibition in the anti-tumor response of bortezomib, we established clonal isolates of HT-29 adenocarcinoma cells adapted to continuous exposure of bortezomib. These cells were ~30-fold resistant to bortezomib. Two novel and distinct mutations in the β5 subunit, Cys63Phe, located distal to the binding site in a helix critical for drug binding, and Arg24Cys, found in the propeptide region were found in all resistant clones. The latter mutation is a natural variant found to be elevated in frequency in patients with MM. Proteasome activity and levels of both the constitutive and immunoproteasome were increased in resistant cells, which correlated to an increase in subunit gene expression. These changes correlated with a more rapid recovery of proteasome activity following brief exposure to bortezomib. Increased recovery rate was not due to increased proteasome turnover as similar findings were seen in cells co-treated with cycloheximide. When we exposed resistant cells to the irreversible proteasome inhibitor carfilzomib we noted a slower rate of recovery of proteasome activity as compared to bortezomib in both parental and resistant cells. Importantly, carfilzomib maintained its cytotoxic potential in the bortezomib resistant cell lines. Therefore, resistance to bortezomib, can be overcome with irreversible inhibitors, suggesting prolonged proteasome inhibition induces a more potent anti-tumor response.

  17. Expression of an insulin/interleukin-1 receptor antagonist hybrid gene in insulin-producing cell lines (HIT-T15 and NIT-1) confers resistance against interleukin-1-induced nitric oxide production.

    OpenAIRE

    Welsh, N; K. Bendtzen; Welsh, M.

    1995-01-01

    A hybrid gene consisting of the insulin gene enhancer/promoter region, the signal sequence, the insulin B- and C-chains, and the human interleukin-1 receptor antagonist (IL-1ra) gene was constructed. This hybrid gene was transfected together with the pSV2-neo construct into the insulin-producing cell lines HIT-T15 and NIT-1. One of the geneticin-selected clones, HITra2, expressed a 1.4-kb mRNA, which hybridized both to insulin and IL-1ra-cDNA in Northern blot analysis. Three proteins, with th...

  18. The overexpression of MRP4 is related to multidrug resistance in osteosarcoma cells

    Directory of Open Access Journals (Sweden)

    Zhonghui He

    2015-01-01

    Full Text Available Doxorubicin (Adriamycin, ADM is an antimitotic drug used in the treatment of a wide range of malignant tumors, including acute leukemia, lymphoma, osteosarcoma, breast cancer, and lung cancer. Multidrug resistance-associated proteins (MRPs are members of a superfamily of ATP-binding cassette (ABC transporters, which can transport various molecules across extra- and intra-cellular membranes. The aim of this study was to investigate whether there was a correlation between MRP4 and primary ADM resistance in osteosarcoma cells. In this paper, we chose the human osteosarcoma cell line MG63, ADM resistant cell line MG63/DOX, and the patient′s primary cell GSF-0686. We checked the ADM sensitivity and cytotoxicity of all the three cells by cell proliferation assay. The intracellular drug concentrations were measured by using LC-MS/MS. We also examined MRP4 gene expression by RT-PCR and Western Blot. We found that the intracellular ADM concentration of the parent osteosarcoma cell line MG63 was higher than the ADM resistant osteosarcoma MG63/DOX cell line or the GSF-0686 cell after ADM treatment (P < 0.05. In addition, MRP4 mRNA and protein levels in ADM resistant osteosarcoma cells were higher than in MG63 cell (P < 0.05. Taking together, this work suggests that overexpression of MRP4 may confer ADM resistance in osteosarcoma cells.

  19. Molecular genetic characterisation of the Asc locus of tomato conferring resistance to the fungal pathogen Alternaria alternata f. sp. lycopersici

    NARCIS (Netherlands)

    Biezen, E.A. van der; Overduin, B.; Kneppers, T.J.A.; Mesbah, L.A.; Nijkamp, H.J.J.; Hille, J.

    1994-01-01

    The Alternaria stem canker disease of tomato is caused by the fungal pathogen Alternaria alternata f. sp. lycopersici and its host-selective AAL-toxins. Resistance to the pathogen and insensitivity to the toxins are conferred by the Asc locus on chromosome 3L. Sensitivity to AAL-toxins is a relative

  20. Molecular mapping and characterization of two genes conferring resistance to Phytophthora sojae in a soybean landrace PI 567139B

    Science.gov (United States)

    Phytophthora root and stem rot (PRR), caused by the soil-borne oomycete pathogen Phytophthora sojae, is one of the most destructive diseases of soybean. PRR can be effectively controlled by race-specific genes conferring resistance to P. sojae (Rps). However, the Rps genes are usually non-durable, a...

  1. A truncating mutation of HDAC2 in human cancers confers resistance to histone deacetylase inhibition

    DEFF Research Database (Denmark)

    Ropero, S; Fraga, MF; Ballestar, E;

    2006-01-01

    arising in individuals with hereditary nonpolyposis colorectal cancer syndrome. The presence of the HDAC2 frameshift mutation causes a loss of HDAC2 protein expression and enzymatic activity and renders these cells more resistant to the usual antiproliferative and proapoptotic effects of histone...

  2. A high Mr factor in human blood which confers serum resistance on gonococci: some properties and synergism with CMP-NANA.

    Science.gov (United States)

    Constantinidou, C; Beadle, D; Zhou, X H; Parsons, N J; Sammons, C C; Cole, J A; Smith, H

    1992-06-01

    A high relative molecular mass (M(r)) component which confers serum resistance on gonococci has been purified about 300-fold from a dialysed sonicate of human blood cells. Serum resistance conferred by the high M(r) factor (RIF), like that induced by cytidine-5' monophospho-N acetyl neuraminic acid (CMP-NANA), decreased when gonococci were incubated with neuraminidase. Also, the resistance-inducing activities of both high M(r) RIF and CMP-NANA were inhibited by CMP and inactivated at pH 4.0. These activities were not additive but synergistic. Neuraminidase decreased the activity of high M(r) RIF but not CMP-NANA. In tests with 14C CMP-NANA and gonococcal lipopolysaccharide, no sialyltransferase activity was detected, even in highly active samples of high M(r) RIF under conditions in which low activities of rat liver sialyltransferase were readily detected. Conversely, rat liver sialyltransferase was neither active in the RIF assay nor able to enhance the RIF activity of CMP-NANA. Nevertheless, high M(r) RIF greatly enhanced the sialyltransferase activity of a gonococcal extract; this enhancement suggests an explanation for the synergism between CMP-NANA and high M(r) RIF in inducing serum resistance in gonococci.

  3. Stable expression and functional characterisation of the diamondback moth ryanodine receptor G4946E variant conferring resistance to diamide insecticides.

    Science.gov (United States)

    Troczka, Bartlomiej J; Williams, Alan J; Williamson, Martin S; Field, Linda M; Lüemmen, Peter; Davies, T G Emyr

    2015-10-01

    Diamides, such as flubendiamide and chlorantraniliprole, belong to a new chemical class of insecticides that act as conformation-sensitive activators of insect ryanodine receptors (RyRs). Both compounds are registered for use against lepidopteran species such as the diamondback moth, Plutella xylostella, a notorious global pest of cruciferous crops. Recently acquired resistance to diamide insecticides in this species is thought to be due to a target-site mutation conferring an amino acid substitution (G4946E), located within the trans-membrane domain of the RyR, though the exact role of this mutation has not yet been fully determined. To address this we have cloned a full-length cDNA encoding the P. xylostella RyR and established clonal Sf9 cell lines stably expressing either the wildtype RyR or the G4946E variant, in order to test the sensitivity to flubendiamide and chlorantraniliprole on the recombinant receptor. We report that the efficacy of both diamides was dramatically reduced in clonal Sf9 cells stably expressing the G4946E modified RyR, providing clear functional evidence that the G4946E RyR mutation impairs diamide insecticide binding.

  4. Proteophosphoglycan confers resistance of Leishmania major to midgut digestive enzymes induced by blood feeding in vector sand flies.

    Science.gov (United States)

    Secundino, Nagila; Kimblin, Nicola; Peters, Nathan C; Lawyer, Phillip; Capul, Althea A; Beverley, Stephen M; Turco, Salvatore J; Sacks, David

    2010-07-01

    Leishmania synthesize abundant phosphoglycan-containing molecules made up of [Gal-Man-PO(4)] repeating units, including the surface lipophosphoglycan (LPG), and the surface and secreted proteophosphoglycan (PPG). The vector competence of Phlebotomus duboscqi and Lutzomyia longipalpis sand flies was tested using L. major knockout mutants deficient in either total phosphoglycans (lpg2(-) or lpg5A(-)/5B(-)) or LPG alone (lpg1(-)) along with their respective gene add-back controls. Our results confirm that LPG, the major cell surface molecule of Leishmania promastigotes known to mediate attachment to the vector midgut, is necessary to prevent the loss of infection during excretion of the blood meal remnants from a natural vector, P. duboscqi, but not an unnatural vector, L. longipalpis. Midgut digestive enzymes induced by blood feeding pose another potential barrier to parasite survival. Our results show that 36-72 h after the infective feed, all parasites developed well except the lpg2(-) and lpg5A(-)/5B(-) mutants, which showed significantly reduced survival and growth. Protease inhibitors promoted the early survival and growth of lpg2(-) in the blood meal. PPG was shown to be the key molecule conferring resistance to midgut digestive enzymes, as it prevented killing of lpg2(-) promastigotes exposed to midgut lysates prepared from blood-fed flies. The protection was not associated with inhibition of enzyme activities, but with cell surface acquisition of the PPG, which appears to function similar to mammalian mucins to protect the surface of developing promastigotes against proteolytic damage. PMID:20088949

  5. Loss of the RNA polymerase III repressor MAF1 confers obesity resistance.

    Science.gov (United States)

    Bonhoure, Nicolas; Byrnes, Ashlee; Moir, Robyn D; Hodroj, Wassim; Preitner, Frédéric; Praz, Viviane; Marcelin, Genevieve; Chua, Streamson C; Martinez-Lopez, Nuria; Singh, Rajat; Moullan, Norman; Auwerx, Johan; Willemin, Gilles; Shah, Hardik; Hartil, Kirsten; Vaitheesvaran, Bhavapriya; Kurland, Irwin; Hernandez, Nouria; Willis, Ian M

    2015-05-01

    MAF1 is a global repressor of RNA polymerase III transcription that regulates the expression of highly abundant noncoding RNAs in response to nutrient availability and cellular stress. Thus, MAF1 function is thought to be important for metabolic economy. Here we show that a whole-body knockout of Maf1 in mice confers resistance to diet-induced obesity and nonalcoholic fatty liver disease by reducing food intake and increasing metabolic inefficiency. Energy expenditure in Maf1(-/-) mice is increased by several mechanisms. Precursor tRNA synthesis was increased in multiple tissues without significant effects on mature tRNA levels, implying increased turnover in a futile tRNA cycle. Elevated futile cycling of hepatic lipids was also observed. Metabolite profiling of the liver and skeletal muscle revealed elevated levels of many amino acids and spermidine, which links the induction of autophagy in Maf1(-/-) mice with their extended life span. The increase in spermidine was accompanied by reduced levels of nicotinamide N-methyltransferase, which promotes polyamine synthesis, enables nicotinamide salvage to regenerate NAD(+), and is associated with obesity resistance. Consistent with this, NAD(+) levels were increased in muscle. The importance of MAF1 for metabolic economy reveals the potential for MAF1 modulators to protect against obesity and its harmful consequences. PMID:25934505

  6. Mutations in the RAM network confer resistance to the thiol oxidant 4,4'-dipyridyl disulfide

    DEFF Research Database (Denmark)

    López-Mirabal, H Reynaldo; Winther, Jakob R; Thorsen, Michael;

    2008-01-01

    -specific oxidant dipyridyl disulfide (DPS) yielded tao3-516, which is impaired in the function of the RAM signaling network protein Tao3/Pag1p. We suggest that the DPS-resistance of the tao3-516 mutant might be due to deficient cell-cycle-regulated production of the chitinase Cts1p, which functions in post......-mitotic cell separation and depends on Tao3p and the RAM network for regulated expression. Consistent with this, deletion of other RAM genes or CTS1 also resulted in increased resistance to DPS. Exposure to DPS caused extensive depolarization of the actin cytoskeleton. We found that tao3-516 is resistant...... to latrunculin, a specific inhibitor of actin polymerization, and that ram, Deltaace2, and Deltacts1 mutants are resistant to benomyl, a microtubule-destabilizing drug. Since septum build-up depends on the organization of cytoskeletal proteins, the resistance to cytoskeletal stress of Cts1p-deficient mutants...

  7. Drug resistance is conferred on the model yeast Saccharomyces cerevisiae by expression of full-length melanoma-associated human ATP-binding cassette transporter ABCB5.

    Science.gov (United States)

    Keniya, Mikhail V; Holmes, Ann R; Niimi, Masakazu; Lamping, Erwin; Gillet, Jean-Pierre; Gottesman, Michael M; Cannon, Richard D

    2014-10-01

    ABCB5, an ATP-binding cassette (ABC) transporter, is highly expressed in melanoma cells, and may contribute to the extreme resistance of melanomas to chemotherapy by efflux of anti-cancer drugs. Our goal was to determine whether we could functionally express human ABCB5 in the model yeast Saccharomyces cerevisiae, in order to demonstrate an efflux function for ABCB5 in the absence of background pump activity from other human transporters. Heterologous expression would also facilitate drug discovery for this important target. DNAs encoding ABCB5 sequences were cloned into the chromosomal PDR5 locus of a S. cerevisiae strain in which seven endogenous ABC transporters have been deleted. Protein expression in the yeast cells was monitored by immunodetection using both a specific anti-ABCB5 antibody and a cross-reactive anti-ABCB1 antibody. ABCB5 function in recombinant yeast cells was measured by determining whether the cells possessed increased resistance to known pump substrates, compared to the host yeast strain, in assays of yeast growth. Three ABCB5 constructs were made in yeast. One was derived from the ABCB5-β mRNA, which is highly expressed in human tissues but is a truncation of a canonical full-size ABC transporter. Two constructs contained full-length ABCB5 sequences: either a native sequence from cDNA or a synthetic sequence codon-harmonized for S. cerevisiae. Expression of all three constructs in yeast was confirmed by immunodetection. Expression of the codon-harmonized full-length ABCB5 DNA conferred increased resistance, relative to the host yeast strain, to the putative substrates rhodamine 123, daunorubicin, tetramethylrhodamine, FK506, or clorgyline. We conclude that full-length ABCB5 can be functionally expressed in S. cerevisiae and confers drug resistance.

  8. Overexpression of a soybean salicylic acid methyltransferase gene confers resistance to soybean cyst nematode.

    Science.gov (United States)

    Lin, Jingyu; Mazarei, Mitra; Zhao, Nan; Zhu, Junwei J; Zhuang, Xiaofeng; Liu, Wusheng; Pantalone, Vincent R; Arelli, Prakash R; Stewart, Charles N; Chen, Feng

    2013-12-01

    Salicylic acid plays a critical role in activating plant defence responses after pathogen attack. Salicylic acid methyltransferase (SAMT) modulates the level of salicylic acid by converting salicylic acid to methyl salicylate. Here, we report that a SAMT gene from soybean (GmSAMT1) plays a role in soybean defence against soybean cyst nematode (Heterodera glycines Ichinohe, SCN). GmSAMT1 was identified as a candidate SCN defence-related gene in our previous analysis of soybean defence against SCN using GeneChip microarray experiments. The current study started with the isolation of the full-length cDNAs of GmSAMT1 from a SCN-resistant soybean line and from a SCN-susceptible soybean line. The two cDNAs encode proteins of identical sequences. The GmSAMT1 cDNA was expressed in Escherichia coli. Using in vitro enzyme assays, E. coli-expressed GmSAMT1 was confirmed to function as salicylic acid methyltransferase. The apparent Km value of GmSAMT1 for salicylic acid was approximately 46 μM. To determine the role of GmSAMT1 in soybean defence against SCN, transgenic hairy roots overexpressing GmSAMT1 were produced and tested for SCN resistance. Overexpression of GmSAMT1 in SCN-susceptible backgrounds significantly reduced the development of SCN, indicating that overexpression of GmSAMT1 in the transgenic hairy root system could confer resistance to SCN. Overexpression of GmSAMT1 in transgenic hairy roots was also found to affect the expression of selected genes involved in salicylic acid biosynthesis and salicylic acid signal transduction.

  9. Transgenic banana expressing Pflp gene confers enhanced resistance to Xanthomonas wilt disease.

    Science.gov (United States)

    Namukwaya, B; Tripathi, L; Tripathi, J N; Arinaitwe, G; Mukasa, S B; Tushemereirwe, W K

    2012-08-01

    Banana Xanthomonas wilt (BXW), caused by Xanthomonas campestris pv. musacearum, is one of the most important diseases of banana (Musa sp.) and currently considered as the biggest threat to banana production in Great Lakes region of East and Central Africa. The pathogen is highly contagious and its spread has endangered the livelihood of millions of farmers who rely on banana for food and income. The development of disease resistant banana cultivars remains a high priority since farmers are reluctant to employ labor-intensive disease control measures and there is no host plant resistance among banana cultivars. In this study, we demonstrate that BXW can be efficiently controlled using transgenic technology. Transgenic bananas expressing the plant ferredoxin-like protein (Pflp) gene under the regulation of the constitutive CaMV35S promoter were generated using embryogenic cell suspensions of banana. These transgenic lines were characterized by molecular analysis. After challenge with X. campestris pv. musacearum transgenic lines showed high resistance. About 67% of transgenic lines evaluated were completely resistant to BXW. These transgenic lines did not show any disease symptoms after artificial inoculation of in vitro plants under laboratory conditions as well as potted plants in the screen-house, whereas non-transgenic control plants showed severe symptoms resulting in complete wilting. This study confirms that expression of the Pflp gene in banana results in enhanced resistance to BXW. This transgenic technology can provide a timely solution to the BXW pandemic.

  10. Epigenetic mechanisms of cell adhesion-mediated drug resistance in multiple myeloma.

    Science.gov (United States)

    Furukawa, Yusuke; Kikuchi, Jiro

    2016-09-01

    Multiple myeloma cells acquire the resistance to anti-cancer drugs through physical and functional interactions with the bone marrow microenvironment via two overlapping mechanisms. First, bone marrow stromal cells (BMSCs) produce soluble factors, such as interleukin-6 and insulin-like growth factor-1, to activate signal transduction pathways leading to drug resistance (soluble factor-mediated drug resistance). Second, BMSCs up-regulate the expression of cell cycle inhibitors, anti-apoptotic members of the Bcl-2 family and ABC drug transporters in myeloma cells upon direct adhesion [cell adhesion-mediated drug resistance (CAM-DR)]. Elucidation of the mechanisms underlying drug resistance may greatly contribute to the advancement of cancer therapies. Recent investigations, including ours, have revealed the involvement of epigenetic alterations in drug resistance especially CAM-DR. For example, we found that class I histone deacetylases (HDACs) determine the sensitivity of proteasome inhibitors and the histone methyltransferase EZH2 regulates the transcription of anti-apoptotic genes during the acquisition of CAM-DR by myeloma cells. In addition, another histone methyltransferase MMSET was shown to confer drug resistance to myeloma cells by facilitating DNA repair. These findings provide a rationale for the inclusion of epigenetic drugs, such as HDAC inhibitors and histone methylation modifiers, in combination chemotherapy for MM patients to increase the therapeutic index. PMID:27411688

  11. Proceedings of the joint contractors meeting: FE/EE Advanced Turbine Systems conference FE fuel cells and coal-fired heat engines conference

    Energy Technology Data Exchange (ETDEWEB)

    Geiling, D.W. [ed.

    1993-08-01

    The joint contractors meeting: FE/EE Advanced Turbine Systems conference FEE fuel cells and coal-fired heat engines conference; was sponsored by the US Department of Energy Office of Fossil Energy and held at the Morgantown Energy Technology Center, P.O. Box 880, Morgantown, West Virginia 26507-0880, August 3--5, 1993. Individual papers have been entered separately.

  12. The 3rd CARISMA international conference on medium and high temperature proton exchange membrane fuel cells: Three approaches to better platinum catalysts at biannual conference

    DEFF Research Database (Denmark)

    Jensen, Jens Oluf; Cleemann, Lars Nilausen; Li, Qingfeng

    2013-01-01

    The 3rd CARISMA International Conference was held at the Axelborg venue in Copenhagen, Denmark, from September 3-5, 2012. The CARISMA conference series was specifically devoted to challenges in the development and testing of fuel cell materials and membrane electrode assemblies (MEAs) for proton...

  13. NBS Proifling Identiifes Potential Novel Locus from Solanum demissum That Confers Broad-Spectrum Resistance to Phytophthora infestans

    Institute of Scientific and Technical Information of China (English)

    ZHANG Kun; XU Jian-fei; DUAN Shao-guang; PANG Wan-fu; BIAN Chun-song; LIU Jie; JIN Li-ping

    2014-01-01

    Potato late blight, caused by the oomycete pathogen Phytophthora infestans, is the most serious disease of potato worldwide. The adoption of varieties with resistance genes, especially broad-spectrum resistance genes, is the most efifcient approach to control late blight. Solanum demissum is a well-known wild potato species from which 11 race-speciifc resistance genes have been identiifed, however, no broad-spectrum resistance genes like RB have been reported in this species. Here, we report a novel reisistance locus from S. demissum that potentially confer broad-spectrum resistance to late blight. A small segregating population of S. demissum were assessed for resistance to aggressive P. infestans isolates (race 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, and 11). This coupled with nucleotide binding site (NBS) proifling analyses, led to the identiifcation of three fragments that linked to the potential candidate resistance gene(s). Cloning and sequence analysis of these fragments suggested that the identiifed resistance gene locus is located in the region containing R2 resistance gene at chromosome 4. Based on the sequences of the cloned fragments, a co-segregating sequence characterized ampliifed region (SCAR) marker, RDSP, was developed. The newly identiifed marker RDSP will be useful for marker assisted breeding and further cloning of this potential resistance gene locus.

  14. A new point mutation in the iron-sulfur subunit of succinate dehydrogenase confers resistance to boscalid in Sclerotinia sclerotiorum.

    Science.gov (United States)

    Wang, Yong; Duan, Yabing; Wang, Jianxin; Zhou, Mingguo

    2015-09-01

    Research has established that mutations in highly conserved amino acids of the succinate dehydrogenase (SDH) complex in various fungi confer SDH inhibitor (SDHI) resistance. For Sclerotinia sclerotiorum (Lib.) de Bary, a necrotrophic fungus with a broad host range and a worldwide distribution, boscalid resistance has been attributed to the mutation H132R in the highly conserved SdhD subunit protein of the SDH complex. In our previous study, however, only one point mutation, A11V in SdhB (GCA to GTA change in SdhB), was detected in S. sclerotiorum boscalid-resistant (BR) mutants. In the current study, replacement of the SdhB gene in a boscalid-sensitive (BS) S. sclerotiorum strain with the mutant SdhB gene conferred resistance. Compared with wild-type strains, BR and GSM (SdhB gene in the wild-type strain replaced by the mutant SdhB gene) mutants were more sensitive to osmotic stress, lacked the ability to produce sclerotia and exhibited lower expression of the pac1 gene. Importantly, the point mutation was not located in the highly conserved sequence of the iron-sulfur subunit of SDH. These results suggest that resistance based on non-conserved vs. conserved protein domains differs in mechanism. In addition to increasing our understanding of boscalid resistance in S. sclerotiorum, the new information will be useful for the development of alternative antifungal drugs. PMID:25441450

  15. Agrobacterium mediated transformation of brassica juncea (l.) czern with chitinase gene conferring resistance against fungal infections

    International Nuclear Information System (INIS)

    Brassica juncea (Czern and Coss., L.) is an important oilseed crop. Since it is attacked by several bacterial and fungal diseases, therefore, we developed an easy and simple protocol for the regeneration and transformation of B. juncea variety RAYA ANMOL to give rise to transgenic plants conferring resistance against various fungal diseases. The transformation was carried out using Agrobacterium with Chitinase gene. This gene was isolated from Streptomyces griseus HUT6037. We used two types of explants for transformation i.e. hypocotyls and cotyledons. Only hypocotyls explants showed good results regarding callus initiation. Different hormonal concentrations were applied i.e. BAP 2, 4 and 6 mgL-1 and NAA 0.1, 0.2 and 0.3 mgL-1. However, high transformation efficiency was observed by supplementing the medium with combination of 2 mgL-1 BAP and 0.2 mgL-1 for initiation of callus. Similarly 10 mgL-1 kanamycin and 200 mgL-1 cefotaxime also proved successful for the selection of transformed callus. In order to confirm the presence of transgenic callus Polymerase chain reaction was performed using specific primers for Chitinase gene. (author)

  16. Expression of snowdrop lectin (GNA) in transgenic rice plants confers resistance to rice brown planthopper.

    Science.gov (United States)

    Rao, K V; Rathore, K S; Hodges, T K; Fu, X; Stoger, E; Sudhakar, D; Williams, S; Christou, P; Bharathi, M; Bown, D P; Powell, K S; Spence, J; Gatehouse, A M; Gatehouse, J A

    1998-08-01

    Snowdrop lectin (Galanthus nivalis agglutinin; GNA) has been shown previously to be toxic towards rice brown planthopper (Nilaparvata lugens; BPH) when administered in artificial diet. BPH feeds by phloem abstraction, and causes 'hopper burn', as well as being an important virus vector. To evaluate the potential of the gna gene to confer resistance towards BPH, transgenic rice (Oryza sativa L.) plants were produced, containing the gna gene in constructs where its expression was driven by a phloem-specific promoter (from the rice sucrose synthase RSs1 gene) and by a constitutive promoter (from the maize ubiquitin ubi1 gene). PCR and Southern analyses on DNA from these plants confirmed their transgenic status, and that the transgenes were transmitted to progeny after self-fertilization. Western blot analyses revealed expression of GNA at levels of up to 2.0% of total protein in some of the transgenic plants. GNA expression driven by the RSs1 promoter was tissue-specific, as shown by immunohistochemical localization of the protein in the non-lignified vascular tissue of transgenic plants. Insect bioassays and feeding studies showed that GNA expressed in the transgenic rice plants decreased survival and overall fecundity (production of offspring) of the insects, retarded insect development, and had a deterrent effect on BPH feeding. gna is the first transgene to exhibit insecticidal activity towards sap-sucking insects in an important cereal crop plant.

  17. Resistance to Bacillus thuringiensis Toxin Cry2Ab in Trichoplusia ni Is Conferred by a Novel Genetic Mechanism.

    Science.gov (United States)

    Song, Xiaozhao; Kain, Wendy; Cassidy, Douglas; Wang, Ping

    2015-08-01

    The resistance to the Bacillus thuringiensis (Bt) toxin Cry2Ab in a greenhouse-originated Trichoplusia ni strain resistant to both Bt toxins Cry1Ac and Cry2Ab was characterized. Biological assays determined that the Cry2Ab resistance in the T. ni strain was a monogenic recessive trait independent of Cry1Ac resistance, and there existed no significant cross-resistance between Cry1Ac and Cry2Ab in T. ni. From the dual-toxin-resistant T. ni strain, a strain resistant to Cry2Ab only was isolated, and the Cry2Ab resistance trait was introgressed into a susceptible laboratory strain to facilitate comparative analysis of the Cry2Ab resistance with the susceptible T. ni strain. Results from biochemical analysis showed no significant difference between the Cry2Ab-resistant and -susceptible T. ni larvae in midgut proteases, including caseinolytic proteolytic activity and zymogram profile and serine protease activities, in midgut aminopeptidase and alkaline phosphatase activity, and in midgut esterases and hemolymph plasma melanization activity. For analysis of genetic linkage of Cry2Ab resistance with potential Cry toxin receptor genes, molecular markers for the midgut cadherin, alkaline phosphatase (ALP), and aminopeptidase N (APN) genes were identified between the original greenhouse-derived dual-toxin-resistant and the susceptible laboratory T. ni strains. Genetic linkage analysis showed that the Cry2Ab resistance in T. ni was not genetically associated with the midgut genes coding for the cadherin, ALP, and 6 APNs (APN1 to APN6) nor associated with the ABC transporter gene ABCC2. Therefore, the Cry2Ab resistance in T. ni is conferred by a novel but unknown genetic mechanism. PMID:26025894

  18. Nuclear PIM1 confers resistance to rapamycin-impaired endothelial proliferation

    Energy Technology Data Exchange (ETDEWEB)

    Walpen, Thomas; Kalus, Ina [Research Unit, Division Internal Medicine, University Hospital Zuerich, 8091 Zuerich (Switzerland); Schwaller, Juerg [Department of Biomedicine, University of Basel, 4031 Basel (Switzerland); Peier, Martin A. [Research Unit, Division Internal Medicine, University Hospital Zuerich, 8091 Zuerich (Switzerland); Battegay, Edouard J. [Research Unit, Division Internal Medicine, University Hospital Zuerich, 8091 Zuerich (Switzerland); Zurich Center for Integrative Human Physiology (ZIHP), 8057 Zuerich (Switzerland); Humar, Rok, E-mail: Rok.Humar@usz.ch [Research Unit, Division Internal Medicine, University Hospital Zuerich, 8091 Zuerich (Switzerland); Zurich Center for Integrative Human Physiology (ZIHP), 8057 Zuerich (Switzerland)

    2012-12-07

    Highlights: Black-Right-Pointing-Pointer Pim1{sup -/-} endothelial cell proliferation displays increased sensitivity to rapamycin. Black-Right-Pointing-Pointer mTOR inhibition by rapamycin enhances PIM1 cytosolic and nuclear protein levels. Black-Right-Pointing-Pointer Truncation of Pim1 beyond serine 276 results in nuclear localization of the kinase. Black-Right-Pointing-Pointer Nuclear PIM1 increases endothelial proliferation independent of rapamycin. -- Abstract: The PIM serine/threonine kinases and the mTOR/AKT pathway integrate growth factor signaling and promote cell proliferation and survival. They both share phosphorylation targets and have overlapping functions, which can partially substitute for each other. In cancer cells PIM kinases have been reported to produce resistance to mTOR inhibition by rapamycin. Tumor growth depends highly on blood vessel infiltration into the malignant tissue and therefore on endothelial cell proliferation. We therefore investigated how the PIM1 kinase modulates growth inhibitory effects of rapamycin in mouse aortic endothelial cells (MAEC). We found that proliferation of MAEC lacking Pim1 was significantly more sensitive to rapamycin inhibition, compared to wildtype cells. Inhibition of mTOR and AKT in normal MAEC resulted in significantly elevated PIM1 protein levels in the cytosol and in the nucleus. We observed that truncation of the C-terminal part of Pim1 beyond Ser 276 resulted in almost exclusive nuclear localization of the protein. Re-expression of this Pim1 deletion mutant significantly increased the proliferation of Pim1{sup -/-} cells when compared to expression of the wildtype Pim1 cDNA. Finally, overexpression of the nuclear localization mutant and the wildtype Pim1 resulted in complete resistance to growth inhibition by rapamycin. Thus, mTOR inhibition-induced nuclear accumulation of PIM1 or expression of a nuclear C-terminal PIM1 truncation mutant is sufficient to increase endothelial cell proliferation

  19. IL-27 Found to Play Significant Role in Conferring HIV Resistance | Poster

    Science.gov (United States)

    By Nancy Parrish, Staff Writer The human immunodeficiency virus (HIV) targets specific immune cells in the body known as macrophages because these are the cells that eliminate foreign material such as bacteria or viruses. HIV is able to reproduce and spread throughout the body if it can avoid destruction by macrophages. A recent study by Lue Dai, Ph.D., and colleagues revealed that the human cytokine IL-27 helps promote the body’s production of macrophages that are resistant to HIV. The study further found that IL-27 suppresses a gene known as SPTBN1, which facilitates the survival of HIV cells. This breakthrough research was recently published in the Journal of Experimental Medicine.

  20. Identification of 8-methyladenosine as the modification catalyzed by the radical SAM methyltransferase Cfr that confers antibiotic resistance in bacteria

    DEFF Research Database (Denmark)

    Giessing, Anders; Jensen, Søren Skov; Rasmussen, Anette;

    2009-01-01

    The Cfr methyltransferase confers combined resistance to five different classes of antibiotics that bind to the peptidyl transferase center of bacterial ribosomes. The Cfr-mediated modification has previously been shown to occur on nucleotide A2503 of 23S rRNA and has a mass corresponding......,8-dimethyladenosine. The mutation of single conserved cysteine residues in the radical SAM motif CxxxCxxC of Cfr abolishes its activity, lending support to the notion that the Cfr modification reaction occurs via a radical-based mechanism. Antibiotic susceptibility data confirm that the antibiotic resistance...

  1. A stilbene synthase allele from a Chinese wild grapevine confers resistance to powdery mildew by recruiting salicylic acid signalling for efficient defence

    Science.gov (United States)

    Jiao, Yuntong; Xu, Weirong; Duan, Dong; Wang, Yuejin; Nick, Peter

    2016-01-01

    Stilbenes are central phytoalexins in Vitis, and induction of the key enzyme stilbene synthase (STS) is pivotal for disease resistance. Here, we address the potential for breeding resistance using an STS allele isolated from Chinese wild grapevine Vitis pseudoreticulata (VpSTS) by comparison with its homologue from Vitis vinifera cv. ‘Carigane’ (VvSTS). Although the coding regions of both alleles are very similar (>99% identity on the amino acid level), the promoter regions are significantly different. By expression in Arabidopsis as a heterologous system, we show that the allele from the wild Chinese grapevine can confer accumulation of stilbenes and resistance against the powdery mildew Golovinomyces cichoracearum, whereas the allele from the vinifera cultivar cannot. To dissect the upstream signalling driving the activation of this promoter, we used a dual-luciferase reporter system in a grapevine cell culture. We show elevated responsiveness of the promoter from the wild grape to salicylic acid (SA) and to the pathogen-associated molecular pattern (PAMP) flg22, equal induction of both alleles by jasmonic acid (JA), and a lack of response to the cell death-inducing elicitor Harpin. This elevated SA response of the VpSTS promoter depends on calcium influx, oxidative burst by RboH, mitogen-activated protein kinase (MAPK) signalling, and JA synthesis. We integrate the data in the context of a model where the resistance of V. pseudoreticulata is linked to a more efficient recruitment of SA signalling for phytoalexin synthesis. PMID:27702992

  2. Identification of yeast genes that confer resistance to chitosan oligosaccharide (COS using chemogenomics

    Directory of Open Access Journals (Sweden)

    Jaime Maria DLA

    2012-06-01

    Full Text Available Abstract Background Chitosan oligosaccharide (COS, a deacetylated derivative of chitin, is an abundant, and renewable natural polymer. COS has higher antimicrobial properties than chitosan and is presumed to act by disrupting/permeabilizing the cell membranes of bacteria, yeast and fungi. COS is relatively non-toxic to mammals. By identifying the molecular and genetic targets of COS, we hope to gain a better understanding of the antifungal mode of action of COS. Results Three different chemogenomic fitness assays, haploinsufficiency (HIP, homozygous deletion (HOP, and multicopy suppression (MSP profiling were combined with a transcriptomic analysis to gain insight in to the mode of action and mechanisms of resistance to chitosan oligosaccharides. The fitness assays identified 39 yeast deletion strains sensitive to COS and 21 suppressors of COS sensitivity. The genes identified are involved in processes such as RNA biology (transcription, translation and regulatory mechanisms, membrane functions (e.g. signalling, transport and targeting, membrane structural components, cell division, and proteasome processes. The transcriptomes of control wild type and 5 suppressor strains overexpressing ARL1, BCK2, ERG24, MSG5, or RBA50, were analyzed in the presence and absence of COS. Some of the up-regulated transcripts in the suppressor overexpressing strains exposed to COS included genes involved in transcription, cell cycle, stress response and the Ras signal transduction pathway. Down-regulated transcripts included those encoding protein folding components and respiratory chain proteins. The COS-induced transcriptional response is distinct from previously described environmental stress responses (i.e. thermal, salt, osmotic and oxidative stress and pre-treatment with these well characterized environmental stressors provided little or any resistance to COS. Conclusions Overexpression of the ARL1 gene, a member of the Ras superfamily that regulates membrane

  3. The cold-induced defensin TAD1 confers resistance against snow mold and Fusarium head blight in transgenic wheat.

    Science.gov (United States)

    Sasaki, Kentaro; Kuwabara, Chikako; Umeki, Natsuki; Fujioka, Mari; Saburi, Wataru; Matsui, Hirokazu; Abe, Fumitaka; Imai, Ryozo

    2016-06-20

    TAD1 (Triticum aestivum defensin 1) is induced during cold acclimation in winter wheat and encodes a plant defensin with antimicrobial activity. In this study, we demonstrated that recombinant TAD1 protein inhibits hyphal growth of the snow mold fungus, Typhula ishikariensis in vitro. Transgenic wheat plants overexpressing TAD1 were created and tested for resistance against T. ishikariensis. Leaf inoculation assays revealed that overexpression of TAD1 confers resistance against the snow mold. In addition, the TAD1-overexpressors showed resistance against Fusarium graminearum, which causes Fusarium head blight, a devastating disease in wheat and barley. These results indicate that TAD1 is a candidate gene to improve resistance against multiple fungal diseases in cereal crops.

  4. Agrobacterium mediated transfer of a mutant Arabidopsis acetolactate synthase gene confers resistance to chlorsulfuron in chicory (Cichorium intybus L.).

    Science.gov (United States)

    Vermeulen, A; Vaucheret, H; Pautot, V; Chupeau, Y

    1992-06-01

    Leaf discs of C. intybus were inoculated with an Agrobacterium tumefaciens strain harboring a neomycin phosphotransferase (neo) gene for kanamycin resistance and a mutant acetolactate synthase gene (csr1-1) from Arabidopsis thaliana conferring resistance to sulfonylurea herbicides. A regeneration medium was optimized which permitted an efficient shoot regeneration from leaf discs. Transgenic shoots were selected on rooting medium containing 100 mg/l kanamycin sulfate. Integration of the csr1-1 gene into genomic DNA of kanamycin resistant chicory plants was confirmed by Southern blot hybridizations. Analysis of the selfed progenies (S1 and S2) of two independent transformed clones showed that kanamycin and chlorsulfuron resistances were inherited as dominant Mendelian traits. The method described here for producing transformed plants will allow new opportunities for chicory breeding. PMID:24203132

  5. Modelling and analysis of dynamics of viral infection of cells and of interferon resistance

    Science.gov (United States)

    Getto, Ph.; Kimmel, M.; Marciniak-Czochra, A.

    2008-08-01

    Interferons are active biomolecules, which help fight viral infections by spreading from infected to uninfected cells and activate effector molecules, which confer resistance from the virus on cells. We propose a new model of dynamics of viral infection, including endocytosis, cell death, production of interferon and development of resistance. The novel element is a specific biologically justified mechanism of interferon action, which results in dynamics different from other infection models. The model reflects conditions prevailing in liquid cultures (ideal mixing), and the absence of cells or virus influx from outside. The basic model is a nonlinear system of five ordinary differential equations. For this variant, it is possible to characterise global behaviour, using a conservation law. Analytic results are supplemented by computational studies. The second variant of the model includes age-of-infection structure of infected cells, which is described by a transport-type partial differential equation for infected cells. The conclusions are: (i) If virus mortality is included, the virus becomes eventually extinct and subpopulations of uninfected and resistant cells are established. (ii) If virus mortality is not included, the dynamics may lead to extinction of uninfected cells. (iii) Switching off the interferon defense results in a decrease of the sum total of uninfected and resistant cells. (iv) Infection-age structure of infected cells may result in stabilisation or destabilisation of the system, depending on detailed assumptions. Our work seems to constitute the first comprehensive mathematical analysis of the cell-virus-interferon system based on biologically plausible hypotheses.

  6. Radiosensitization conferred by oxygen and hypoxic cell sensitizers on human cells cultivated in vitro

    International Nuclear Information System (INIS)

    The main purpose was to provide additional information on two questions; (1) How does the radiosensitising effect of oxygen depend on oxygen concentration and cellular age, and (2) How does the radiosensitising effect of hypoxic cell sensitisers depend on concentration of sensitiser and cellular age. The general conclusions reached were as follows. The radiosensitising effect of oxygen on NHIK 3025 cells in G1 increased with increasing dose of radiation. For cells irradiated in S oxygen acted as a dose-modifying agent. For small doses of radiation the sensitising effect of oxygen was weaker for cells irradiated in G1 than for cells irradiated in S. The capacity of NHIK 3025 cells to repair sublethal damage after irradiation under extremely hypoxic conditions was low or even lost (even though the cells were subsequently incubated under aerobic conditions). The radiosensitising effect conferred by TMPN, diamide and misonidazole on NHIK 3025 cells was higher at high doses of radiation than at small doses of radiation (except for the dose-modifying radiosensitisation of cells in S by misonidazole). This observation supports arguments for using high dose fractions in fractionated radiotherapy where such chemicals are involved. (JIW)

  7. Overexpression of Salmonella enterica serovar Typhi recA gene confers fluoroquinolone resistance in Escherichia coli DH5α.

    Science.gov (United States)

    Yassien, M A M; Elfaky, M A

    2015-11-01

    A spontaneous fluoroquinolone-resistant mutant (STM1) was isolated from its parent Salmonella enterica serovar Typhi (S. Typhi) clinical isolate. Unlike its parent isolate, this mutant has selective resistance to fluoroquinolones without any change in its sensitivity to various other antibiotics. DNA gyrase assays revealed that the fluoroquinolone resistance phenotype of the STM1 mutant did not result from alteration of the fluoroquinolone sensitivity of the DNA gyrase isolated from it. To study the mechanism of fluoroquinolone resistance, a genomic library from the STM1 mutant was constructed in Escherichia coli DH5α and two recombinant plasmids were obtained. Only one of these plasmids (STM1-A) conferred the selective fluoroquinolone resistance phenotype to E. coli DH5α. The chromosomal insert from STM1-A, digested with EcoRI and HindIII restriction endonucleases, produced two DNA fragments and these were cloned separately into pUC19 thereby generating two new plasmids, STM1-A1 and STM1-A2. Only STM1-A1 conferred the selective fluoroquinolone resistance phenotype to E. coli DH5α. Sequence and subcloning analyses of STM1-A1 showed the presence of an intact RecA open reading frame. Unlike that of the wild-type E. coli DH5α, protein analysis of a crude STM1-A1 extract showed overexpression of a 40 kDa protein. Western blotting confirmed the 40 kDa protein band to be RecA. When a RecA PCR product was cloned into pGEM-T and introduced into E. coli DH5α, the STM1-A11 subclone retained fluoroquinolone resistance. These results suggest that overexpression of RecA causes selective fluoroquinolone resistance in E. coli DH5α. PMID:26375447

  8. Overexpression of Salmonella enterica serovar Typhi recA gene confers fluoroquinolone resistance in Escherichia coli DH5α

    Directory of Open Access Journals (Sweden)

    M.A.M. Yassien

    2015-11-01

    Full Text Available A spontaneous fluoroquinolone-resistant mutant (STM1 was isolated from its parent Salmonella enterica serovar Typhi (S. Typhi clinical isolate. Unlike its parent isolate, this mutant has selective resistance to fluoroquinolones without any change in its sensitivity to various other antibiotics. DNA gyrase assays revealed that the fluoroquinolone resistance phenotype of the STM1 mutant did not result from alteration of the fluoroquinolone sensitivity of the DNA gyrase isolated from it. To study the mechanism of fluoroquinolone resistance, a genomic library from the STM1 mutant was constructed in Escherichia coli DH5α and two recombinant plasmids were obtained. Only one of these plasmids (STM1-A conferred the selective fluoroquinolone resistance phenotype to E. coli DH5α. The chromosomal insert from STM1-A, digested with EcoRI and HindIII restriction endonucleases, produced two DNA fragments and these were cloned separately into pUC19 thereby generating two new plasmids, STM1-A1 and STM1-A2. Only STM1-A1 conferred the selective fluoroquinolone resistance phenotype to E. coli DH5α. Sequence and subcloning analyses of STM1-A1 showed the presence of an intact RecA open reading frame. Unlike that of the wild-type E. coli DH5α, protein analysis of a crude STM1-A1 extract showed overexpression of a 40 kDa protein. Western blotting confirmed the 40 kDa protein band to be RecA. When a RecA PCR product was cloned into pGEM-T and introduced into E. coli DH5α, the STM1-A11 subclone retained fluoroquinolone resistance. These results suggest that overexpression of RecA causes selective fluoroquinolone resistance in E. coli DH5α.

  9. Resistant bacteria in stem cell transplant recipients

    Directory of Open Access Journals (Sweden)

    Nucci Marcio

    2002-01-01

    Full Text Available Bacterial infections account for most infections in hematopoietic stem cell transplant recipients. While early mortality reduced dramatically with the introduction of the concept of empirical antibiotic therapy in neutropenic patients, no effect of prophylaxis on the mortality was observed in many studies. On the other hand, antibiotic prophylaxis has resulted in the emergence of resistance among bacteria. In addition, the choice of the antibiotic regimen for empirical therapy and the practices of antibiotic therapy during neutropenia may result in a significant shift in the pattern of bacterial infections. The use of quinolones and vancomycin as prophylaxis, and of carbapenems and vancomycin in the empirical antibiotic therapy, are associated with the appearance of resistant Gram-positive and Gram-negative bacteria. Therefore, hematologists must be aware of the impact of these practices on the emergence of infections due to multi-resistant pathogens, since these infections may be associated with increased mortality.

  10. Overcoming Multidrug Resistance in Cancer Stem Cells

    Directory of Open Access Journals (Sweden)

    Karobi Moitra

    2015-01-01

    Full Text Available The principle mechanism of protection of stem cells is through the expression of ATP-binding cassette (ABC transporters. These transporters serve as the guardians of the stem cell population in the body. Unfortunately these very same ABC efflux pumps afford protection to cancer stem cells in tumors, shielding them from the adverse effects of chemotherapy. A number of strategies to circumvent the function of these transporters in cancer stem cells are currently under investigation. These strategies include the development of competitive and allosteric modulators, nanoparticle mediated delivery of inhibitors, targeted transcriptional regulation of ABC transporters, miRNA mediated inhibition, and targeting of signaling pathways that modulate ABC transporters. The role of ABC transporters in cancer stem cells will be explored in this paper and strategies aimed at overcoming drug resistance caused by these particular transporters will also be discussed.

  11. High Radiation Resistance IMM Solar Cell

    Science.gov (United States)

    Pan, Noren

    2015-01-01

    Due to high launch costs, weight reduction is a key driver for the development of new solar cell technologies suitable for space applications. This project is developing a unique triple-junction inverted metamorphic multijunction (IMM) technology that enables the manufacture of very lightweight, low-cost InGaAsP-based multijunction solar cells. This IMM technology consists of indium (In) and phosphorous (P) solar cell active materials, which are designed to improve the radiation-resistant properties of the triple-junction solar cell while maintaining high efficiency. The intrinsic radiation hardness of InP materials makes them of great interest for building solar cells suitable for deployment in harsh radiation environments, such as medium Earth orbit and missions to the outer planets. NASA Glenn's recently developed epitaxial lift-off (ELO) process also will be applied to this new structure, which will enable the fabrication of the IMM structure without the substrate.

  12. EXPRESSION AND REVERSION OF DRUG RESISTANCE-AND APOPTOSIS-RELATED GENES OF A DDP-RESISTANT LUNG ADENOCARCINOMA CELL LINE

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Objective: To investigate the co-expression of drug resistance- and apoptosis-related genes of cisplatin (CDDP)-selected lung adenocarcinoma cell line A549DDP for compared to the parental cell line A549, and reverse of drug resistance by antisense s-oligodeoxynucleotides (S-ODNs) of differentially expressed genes. Methods: Sense and antisense S-ODN were transferred into A549DDP cells by lipofectin. The expression of drug resistance and apoptosis related genes was examined by RT-PCR, immunocytochemistry and flow cytometry, respectively. Apoptostic cells were identified by DNA electrophoresis and terminal deoxynucleotidyl transferase (TdT)-mediated biotin dUTP nick end-labeling(TUNEL). Drug resistance of tumor cells was detected by a cell viability (MTT) assay. Results: The expression of bc1-2 was positive and that of multidrug resistance-associated protein (MRP) at mRNA and protein level was increased in A549DDP compared to A549 cells. MDR1, c-myc and topoisomeras II (TOPO II) were similarly co-expressed in two cell lines. Both cell lines were negative for c-erbB-2 expression. In A549DDP cells, the expression of bc1-2 and MRP was significantly inhibited by their respective antisense S-ODNs. Antisense S-ODNs could also decrease significantly drug resistance of A549DDP cells to CDDP by promoting cell apoptosis. Conclusion: Both intrinsic and acquired drug resistance were involved in co-expression of multiple MDR-related genes in lung adenocarcinoma. Co- operation of bc1-2 and MRP genes appeared to play an important action to confer the resistance of A549DDP cells to CDDP. Their antisense S-ODNs are responsible for the decrease of drug resistance of this cell line by promoting apoptosis.

  13. Resistance to the novel fungicide pyrimorph in Phytophthora capsici: risk assessment and detection of point mutations in CesA3 that confer resistance.

    Science.gov (United States)

    Pang, Zhili; Shao, Jingpeng; Chen, Lei; Lu, Xiaohong; Hu, Jian; Qin, Zhaohai; Liu, Xili

    2013-01-01

    Pyrimorph is a novel fungicide with high activity against the plant pathogen Phytophthora capsici. We investigated the risk that P. capsici can develop resistance to pyrimorph. The baseline sensitivities of 226 P. capsici isolates, tested by mycelial growth inhibition, showed a unimodal distribution with a mean EC(50) value of 1.4261 (± 0.4002) µg/ml. Twelve pyrimorph-resistant mutants were obtained by repeated exposure to pyrimorph in vitro with a frequency of approximately 1 × 10(-4). The resistance factors of the mutants ranged from 10.67 to 56.02. Pyrimorph resistance of the mutants was stable after 10 transfers on pyrimorph-free medium. Fitness in sporulation, cystospore germination, and pathogenicity in the pyrimorph-resistant mutants was similar to or less than that in the parental wild-type isolates. On detached pepper leaves and pepper plants treated with the recommended maximum dose of pyrimorph, however, virulence was greater for mutants with a high level of pyrimorph resistance than for the wild type. The results suggest that the risk of P. capsici developing resistance to pyrimorph is low to moderate. Among mutants with a high level of pyrimorph resistance, EC(50) values for pyrimorph and CAA fungicides flumorph, dimethomorph, and mandipropamid were positively correlated. This indicated that point mutations in cellulose synthase 3 (CesA3) may confer resistance to pyrimorph. Comparison of CesA3 in isolates with a high level of pyrimorph resistance and parental isolates showed that an amino acid change from glutamine to lysine at position 1077 resulted in stable, high resistance in the mutants. Based on the point mutations, an allele-specific PCR method was developed to detect pyrimorph resistance in P. capsici populations.

  14. Resistance to the novel fungicide pyrimorph in Phytophthora capsici: risk assessment and detection of point mutations in CesA3 that confer resistance.

    Directory of Open Access Journals (Sweden)

    Zhili Pang

    Full Text Available Pyrimorph is a novel fungicide with high activity against the plant pathogen Phytophthora capsici. We investigated the risk that P. capsici can develop resistance to pyrimorph. The baseline sensitivities of 226 P. capsici isolates, tested by mycelial growth inhibition, showed a unimodal distribution with a mean EC(50 value of 1.4261 (± 0.4002 µg/ml. Twelve pyrimorph-resistant mutants were obtained by repeated exposure to pyrimorph in vitro with a frequency of approximately 1 × 10(-4. The resistance factors of the mutants ranged from 10.67 to 56.02. Pyrimorph resistance of the mutants was stable after 10 transfers on pyrimorph-free medium. Fitness in sporulation, cystospore germination, and pathogenicity in the pyrimorph-resistant mutants was similar to or less than that in the parental wild-type isolates. On detached pepper leaves and pepper plants treated with the recommended maximum dose of pyrimorph, however, virulence was greater for mutants with a high level of pyrimorph resistance than for the wild type. The results suggest that the risk of P. capsici developing resistance to pyrimorph is low to moderate. Among mutants with a high level of pyrimorph resistance, EC(50 values for pyrimorph and CAA fungicides flumorph, dimethomorph, and mandipropamid were positively correlated. This indicated that point mutations in cellulose synthase 3 (CesA3 may confer resistance to pyrimorph. Comparison of CesA3 in isolates with a high level of pyrimorph resistance and parental isolates showed that an amino acid change from glutamine to lysine at position 1077 resulted in stable, high resistance in the mutants. Based on the point mutations, an allele-specific PCR method was developed to detect pyrimorph resistance in P. capsici populations.

  15. TIMP-1 increases expression and phosphorylation of proteins associated with drug resistance in breast cancer cells

    DEFF Research Database (Denmark)

    Hekmat, Omid; Munk, Stephanie; Fogh, Louise;

    2013-01-01

    spectrometry to analyze global proteome and phosphoproteome differences of MCF-7 breast cancer cells expressing high or low levels of TIMP-1. In TIMP-1 high expressing cells, 312 proteins and 452 phosphorylation sites were up-regulated. Among these were the cancer drug targets topoisomerase 1, 2A and 2B, which...... high expressing cells may be part of the mechanisms by which TIMP-1 confers resistance to treatment with the widely-used topoisomerase inhibitors in breast- and colorectal cancer.......Tissue inhibitor of metalloproteinase 1 (TIMP-1) is a protein with a potential biological role in drug resistance. To elucidate the unknown molecular mechanisms underlying the association between high TIMP-1 levels and increased chemotherapy resistance, we employed SILAC-based quantitative mass...

  16. Discovering naturally processed antigenic determinants that confer protective T cell immunity

    DEFF Research Database (Denmark)

    Gilchuk, Pavlo; Spencer, Charles T; Conant, Stephanie B;

    2013-01-01

    CD8+ T cells (TCD8) confer protective immunity against many infectious diseases, suggesting that microbial TCD8 determinants are promising vaccine targets. Nevertheless, current T cell antigen identification approaches do not discern which epitopes drive protective immunity during active infectio...

  17. Multidrug resistance in tumour cells: characterisation of the multidrug resistant cell line K562-Lucena 1

    Directory of Open Access Journals (Sweden)

    VIVIAN M. RUMJANEK

    2001-03-01

    Full Text Available Multidrug resistance to chemotherapy is a major obstacle in the treatment of cancer patients. The best characterised mechanism responsible for multidrug resistance involves the expression of the MDR-1 gene product, P-glycoprotein. However, the resistance process is multifactorial. Studies of multidrug resistance mechanisms have relied on the analysis of cancer cell lines that have been selected and present cross-reactivity to a broad range of anticancer agents. This work characterises a multidrug resistant cell line, originally selected for resistance to the Vinca alkaloid vincristine and derived from the human erythroleukaemia cell K562. This cell line, named Lucena 1, overexpresses P-glycoprotein and have its resistance reversed by the chemosensitisers verapamil, trifluoperazine and cyclosporins A, D and G. Furthermore, we demonstrated that methylene blue was capable of partially reversing the resistance in this cell line. On the contrary, the use of 5-fluorouracil increased the resistance of Lucena 1. In addition to chemotherapics, Lucena 1 cells were resistant to ultraviolet A radiation and hydrogen peroxide and failed to mobilise intracellular calcium when thapsigargin was used. Changes in the cytoskeleton of this cell line were also observed.A resistência a múltiplos fármacos é o principal obstáculo no tratamento de pacientes com câncer. O mecanismo responsável pela resistência múltipla mais bem caracterizado envolve a expressão do produto do gene MDR-1, a glicoproteína P. Entretanto, o processo de resistência tem fatores múltiplos. Estudos de mecanismos de resistência m��ltipla a fármacos têm dependido da análise de linhagens celulares tumorais que foram selecionadas e apresentam reatividade cruzada a uma ampla faixa de agentes anti-tumorais. Este trabalho caracteriza uma linhagem celular com múltipla resistência a fármacos, selecionada originalmente pela resistência ao alcalóide de Vinca vincristina e derivado

  18. Identification of regulated genes conferring resistance to high concentrations of glyphosate in a new strain of Enterobacter.

    Science.gov (United States)

    Fei, Yun-Yan; Gai, Jun-Yi; Zhao, Tuan-Jie

    2013-12-01

    Glyphosate is a widely used herbicide that inhibits 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) activity. Most plants and microbes are sensitive to glyphosate. However, transgenic-resistant crops that contain a modified epsps obtained from the resistant microbes have been commercially successful and therefore, new resistance genes and their adaptive regulatory mechanisms are of great interest. In this study, a soil-borne, glyphosate-resistant bacterium was selected and identified as Enterobacter. The EPSPS in this strain was found to have been altered to a resistant one. A total of 42 differentially expressed genes (DEGs) in the glyphosate were screened using microarray techniques. Under treatment, argF, sdhA, ivbL, rrfA-H were downregulated, whereas the transcripts of speA, osmY, pflB, ahpC, fusA, deoA, uxaC, rpoD and a few ribosomal protein genes were upregulated. Data were verified by quantitative real-time PCR on selected genes. All transcriptional changes appeared to protect the bacteria from glyphosate and associated osmotic, acidic and oxidative stresses. Many DEGs may have the potential to confer resistance to glyphosate alone, and some may be closely related to the shikimate pathway, reflecting the complex gene interaction network for glyphosate resistance.

  19. Tandem amplification of a chromosomal segment harboring 5-enolpyruvylshikimate-3-phosphate synthase locus confers glyphosate resistance in Kochia scoparia.

    Science.gov (United States)

    Jugulam, Mithila; Niehues, Kindsey; Godar, Amar S; Koo, Dal-Hoe; Danilova, Tatiana; Friebe, Bernd; Sehgal, Sunish; Varanasi, Vijay K; Wiersma, Andrew; Westra, Philip; Stahlman, Phillip W; Gill, Bikram S

    2014-11-01

    Recent rapid evolution and spread of resistance to the most extensively used herbicide, glyphosate, is a major threat to global crop production. Genetic mechanisms by which weeds evolve resistance to herbicides largely determine the level of resistance and the rate of evolution of resistance. In a previous study, we determined that glyphosate resistance in Kochia scoparia is due to the amplification of the 5-Enolpyruvylshikimate-3-Phosphate Synthase (EPSPS) gene, the enzyme target of glyphosate. Here, we investigated the genomic organization of the amplified EPSPS copies using fluorescence in situ hybridization (FISH) and extended DNA fiber (Fiber FISH) on K. scoparia chromosomes. In both glyphosate-resistant K. scoparia populations tested (GR1 and GR2), FISH results displayed a single and prominent hybridization site of the EPSPS gene localized on the distal end of one pair of homologous metaphase chromosomes compared with a faint hybridization site in glyphosate-susceptible samples (GS1 and GS2). Fiber FISH displayed 10 copies of the EPSPS gene (approximately 5 kb) arranged in tandem configuration approximately 40 to 70 kb apart, with one copy in an inverted orientation in GR2. In agreement with FISH results, segregation of EPSPS copies followed single-locus inheritance in GR1 population. This is the first report of tandem target gene amplification conferring field-evolved herbicide resistance in weed populations.

  20. Tandem amplification of a chromosomal segment harboring 5-enolpyruvylshikimate-3-phosphate synthase locus confers glyphosate resistance in Kochia scoparia.

    Science.gov (United States)

    Jugulam, Mithila; Niehues, Kindsey; Godar, Amar S; Koo, Dal-Hoe; Danilova, Tatiana; Friebe, Bernd; Sehgal, Sunish; Varanasi, Vijay K; Wiersma, Andrew; Westra, Philip; Stahlman, Phillip W; Gill, Bikram S

    2014-11-01

    Recent rapid evolution and spread of resistance to the most extensively used herbicide, glyphosate, is a major threat to global crop production. Genetic mechanisms by which weeds evolve resistance to herbicides largely determine the level of resistance and the rate of evolution of resistance. In a previous study, we determined that glyphosate resistance in Kochia scoparia is due to the amplification of the 5-Enolpyruvylshikimate-3-Phosphate Synthase (EPSPS) gene, the enzyme target of glyphosate. Here, we investigated the genomic organization of the amplified EPSPS copies using fluorescence in situ hybridization (FISH) and extended DNA fiber (Fiber FISH) on K. scoparia chromosomes. In both glyphosate-resistant K. scoparia populations tested (GR1 and GR2), FISH results displayed a single and prominent hybridization site of the EPSPS gene localized on the distal end of one pair of homologous metaphase chromosomes compared with a faint hybridization site in glyphosate-susceptible samples (GS1 and GS2). Fiber FISH displayed 10 copies of the EPSPS gene (approximately 5 kb) arranged in tandem configuration approximately 40 to 70 kb apart, with one copy in an inverted orientation in GR2. In agreement with FISH results, segregation of EPSPS copies followed single-locus inheritance in GR1 population. This is the first report of tandem target gene amplification conferring field-evolved herbicide resistance in weed populations. PMID:25037215

  1. The Fd-GOGAT1 mutant gene lc7 confers resistance to Xanthomonas oryzae pv. Oryzae in rice.

    Science.gov (United States)

    Chen, Honglin; Li, Chunrong; Liu, Liping; Zhao, Jiying; Cheng, Xuzhen; Jiang, Guanghuai; Zhai, Wenxue

    2016-01-01

    Disease resistance is an important goal of crop improvement. The molecular mechanism of resistance requires further study. Here, we report the identification of a rice leaf color mutant, lc7, which is defective in chlorophyll synthesis and photosynthesis but confers resistance to Xanthomonas oryzae pv. Oryzae (Xoo). Map-based cloning revealed that lc7 encodes a mutant ferredoxin-dependent glutamate synthase1 (Fd-GOGAT1). Fd-GOGAT1 has been proposed to have great potential for improving nitrogen-use efficiency, but its function in bacterial resistance has not been reported. The lc7 mutant accumulates excessive levels of ROS (reactive oxygen species) in the leaves, causing the leaf color to become yellow after the four-leaf stage. Compared to the wild type, lc7 mutants have a broad-spectrum high resistance to seven Xoo strains. Differentially expressed genes (DEGs) and qRT-PCR analysis indicate that many defense pathways that are involved in this broad-spectrum resistance are activated in the lc7 mutant. These results suggest that Fd-GOGAT1 plays an important role in broad-spectrum bacterial blight resistance, in addition to modulating nitrogen assimilation and chloroplast development. PMID:27211925

  2. Evaluation of dihydrofolate reductase and dihydropteroate synthetase genotypes that confer resistance to sulphadoxine-pyrimethamine in Plasmodium falciparum in Haiti

    Directory of Open Access Journals (Sweden)

    Carter Tamar E

    2012-08-01

    Full Text Available Abstract Background Malaria caused by Plasmodium falciparum infects roughly 30,000 individuals in Haiti each year. Haiti has used chloroquine (CQ as a first-line treatment for malaria for many years and as a result there are concerns that malaria parasites may develop resistance to CQ over time. Therefore it is important to prepare for alternative malaria treatment options should CQ resistance develop. In many other malaria-endemic regions, antifolates, particularly pyrimethamine (PYR and sulphadoxine (SDX treatment combination (SP, have been used as an alternative when CQ resistance has developed. This study evaluated mutations in the dihydrofolate reductase (dhfr and dihydropteroate synthetase (dhps genes that confer PYR and SDX resistance, respectively, in P. falciparum to provide baseline data in Haiti. This study is the first comprehensive study to examine PYR and SDX resistance genotypes in P. falciparum in Haiti. Methods DNA was extracted from dried blood spots and genotyped for PYR and SDX resistance mutations in P. falciparum using PCR and DNA sequencing methods. Sixty-one samples were genotyped for PYR resistance in codons 51, 59, 108 and 164 of the dhfr gene and 58 samples were genotyped for SDX resistance codons 436, 437, 540 of the dhps gene in P. falciparum. Results Thirty-three percent (20/61 of the samples carried a mutation at codon 108 (S108N of the dhfr gene. No mutations in dhfr at codons 51, 59, 164 were observed in any of the samples. In addition, no mutations were observed in dhps at the three codons (436, 437, 540 examined. No significant difference was observed between samples collected in urban vs rural sites (Welch’s T-test p-value = 0.53 and permutations p-value = 0.59. Conclusion This study has shown the presence of the S108N mutation in P. falciparum that confers low-level PYR resistance in Haiti. However, the absence of SDX resistance mutations suggests that SP resistance may not be present in Haiti. These

  3. P-Glycoprotein-Mediated Efflux and Drug Sequestration in Lysosomes Confer Advantages of K562 Multidrug Resistance Sublines to Survive Prolonged Exposure to Cytotoxic Agents

    Directory of Open Access Journals (Sweden)

    Nathupakorn Dechsupa

    2009-01-01

    Full Text Available Problem statement: Cellular drug resistance to anticancer agents is major obstacle in cancer chemotherapy and the mechanisms by which these MDR cells possess for protecting themselves to survive prolonged exposure to cytotoxic agents still debating. The study aimed to clarify the role of P-glycoprotein (Pgp and enhanced drug sequestration in lysosomes to confer the multidrug resistance K562 cells with varied degree of Pgp expression. Approach: Erythromyelogenous leukemic K562 and its corresponding Pgp-over expression K562/adr (RF = 26.5 and K562/10000 (RF = 39.6 cells were used. The transport of intrinsic fluorescence molecules including acridine orange and pirarubicin across plasma membrane of living cells was performed by using spectrofluorometric and flow cytometric analysis. Results: Pirarubicin passively diffused through the plasma membrane of K562, K562/adr and K562/10000 cells with the same values of k+ = 3.4±0.3 pL. s-1.cell-1. Similar results were found for acridine orange, which passively diffused through plasma membrane of these cell lines about 30-fold faster than pirarubicin. The mean rate of Pgp-mediated efflux coefficient (ka of pirarubicin was equal to 2.6 ± 0.9 pL.s-1.cell-1 for K562/adr and 4.7 ± 1.0 pL.s-1.cell-1 for K562/10000 cells. The Pgp-mediated efflux of acridine orange could not be determined for K562/adr cells while an enhancement of exocytosis in K562/10000 cells was characterized. The acridine orange exhibited antiproliferative activity and IC50 for K562, K562/adr and K562/10000 cells was 447±40, 715±19 and 1,719±258 nM, respectively. Cytotoxicity of acridine orange was increased by 2-fold in the presence of and 25 nM monensin. Conclusion: The results clearly demonstrated for the first time that by using the same methods and cell lines. The predominant cellular defense mechanism determined in multidrug resistant cells depends upon the nature of molecular probes used. As molecular probe, pirarubicin clearly

  4. Host-induced post-transcriptional hairpin RNA-mediated gene silencing of vital fungal genes confers efficient resistance against Fusarium wilt in banana.

    Science.gov (United States)

    Ghag, Siddhesh B; Shekhawat, Upendra K S; Ganapathi, Thumballi R

    2014-06-01

    Fusarium wilt, caused by Fusarium oxysporum f. sp. cubense (Foc), is among the most destructive diseases of banana (Musa spp.). Because no credible control measures are available, development of resistant cultivars through genetic engineering is the only option. We investigated whether intron hairpin RNA (ihpRNA)-mediated expression of small interfering RNAs (siRNAs) targeted against vital fungal genes (velvet and Fusarium transcription factor 1) in transgenic banana could achieve effective resistance against Foc. Partial sequences of these two genes were assembled as ihpRNAs in suitable binary vectors (ihpRNA-VEL and ihpRNA-FTF1) and transformed into embryogenic cell suspensions of banana cv. Rasthali by Agrobacterium-mediated genetic transformation. Eleven transformed lines derived from ihpRNA-VEL and twelve lines derived from ihpRNA-FTF1 were found to be free of external and internal symptoms of Foc after 6-week-long greenhouse bioassays. The five selected transgenic lines for each construct continued to resist Foc at 8 months postinoculation. Presence of specific siRNAs derived from the two ihpRNAs in transgenic banana plants was confirmed by Northern blotting and Illumina sequencing of small RNAs derived from the transgenic banana plants. The present study represents an important effort in proving that host-induced post-transcriptional ihpRNA-mediated gene silencing of vital fungal genes can confer efficient resistance against debilitating pathogens in crop plants.

  5. Host-induced post-transcriptional hairpin RNA-mediated gene silencing of vital fungal genes confers efficient resistance against Fusarium wilt in banana.

    Science.gov (United States)

    Ghag, Siddhesh B; Shekhawat, Upendra K S; Ganapathi, Thumballi R

    2014-06-01

    Fusarium wilt, caused by Fusarium oxysporum f. sp. cubense (Foc), is among the most destructive diseases of banana (Musa spp.). Because no credible control measures are available, development of resistant cultivars through genetic engineering is the only option. We investigated whether intron hairpin RNA (ihpRNA)-mediated expression of small interfering RNAs (siRNAs) targeted against vital fungal genes (velvet and Fusarium transcription factor 1) in transgenic banana could achieve effective resistance against Foc. Partial sequences of these two genes were assembled as ihpRNAs in suitable binary vectors (ihpRNA-VEL and ihpRNA-FTF1) and transformed into embryogenic cell suspensions of banana cv. Rasthali by Agrobacterium-mediated genetic transformation. Eleven transformed lines derived from ihpRNA-VEL and twelve lines derived from ihpRNA-FTF1 were found to be free of external and internal symptoms of Foc after 6-week-long greenhouse bioassays. The five selected transgenic lines for each construct continued to resist Foc at 8 months postinoculation. Presence of specific siRNAs derived from the two ihpRNAs in transgenic banana plants was confirmed by Northern blotting and Illumina sequencing of small RNAs derived from the transgenic banana plants. The present study represents an important effort in proving that host-induced post-transcriptional ihpRNA-mediated gene silencing of vital fungal genes can confer efficient resistance against debilitating pathogens in crop plants. PMID:24476152

  6. 1st ESMO Consensus Conference in lung cancer; Lugano 2010: small-cell lung cancer

    DEFF Research Database (Denmark)

    Stahel, R; Thatcher, N; Früh, M;

    2011-01-01

    , the expert panel prepared clinically relevant questions concerning five areas as follows: early and locally advanced non-small-cell lung cancer (NSCLC), first-line metastatic NSCLC, second-/third-line NSCLC, NSCLC pathology and molecular testing, and small-cell lung cancer (SCLC) to be addressed through......The 1st ESMO Consensus Conference on lung cancer was held in Lugano, Switzerland on 21st and 22nd May 2010 with the participation of a multidisciplinary panel of leading professionals in pathology and molecular diagnostics and medical, surgical and radiation oncology. Before the conference...

  7. Genes that confer the identity of the renin cell.

    Science.gov (United States)

    Brunskill, Eric W; Sequeira-Lopez, Maria Luisa S; Pentz, Ellen S; Lin, Eugene; Yu, Jing; Aronow, Bruce J; Potter, S Steven; Gomez, R Ariel

    2011-12-01

    Renin-expressing cells modulate BP, fluid-electrolyte homeostasis, and kidney development, but remarkably little is known regarding the genetic regulatory network that governs the identity of these cells. Here we compared the gene expression profiles of renin cells with most cells in the kidney at various stages of development as well as after a physiologic challenge known to induce the transformation of arteriolar smooth muscle cells into renin-expressing cells. At all stages, renin cells expressed a distinct set of genes characteristic of the renin phenotype, which was vastly different from other cell types in the kidney. For example, cells programmed to exhibit the renin phenotype expressed Akr1b7, and maturing cells expressed angiogenic factors necessary for the development of the kidney vasculature and RGS (regulator of G-protein signaling) genes, suggesting a potential relationship between renin cells and pericytes. Contrary to the plasticity of arteriolar smooth muscle cells upstream from the glomerulus, which can transiently acquire the embryonic phenotype in the adult under physiologic stress, the adult juxtaglomerular cell always possessed characteristics of both smooth muscle and renin cells. Taken together, these results identify the gene expression profile of renin-expressing cells at various stages of maturity, and suggest that juxtaglomerular cells maintain properties of both smooth muscle and renin-expressing cells, likely to allow the rapid control of body fluids and BP through both contractile and endocrine functions. PMID:22034642

  8. A Locus at 5q33.3 Confers Resistance to Tuberculosis in Highly Susceptible Individuals

    Science.gov (United States)

    Sobota, Rafal S.; Stein, Catherine M.; Kodaman, Nuri; Scheinfeldt, Laura B.; Maro, Isaac; Wieland-Alter, Wendy; Igo, Robert P.; Magohe, Albert; Malone, LaShaunda L.; Chervenak, Keith; Hall, Noemi B.; Modongo, Chawangwa; Zetola, Nicola; Matee, Mecky; Joloba, Moses; Froment, Alain; Nyambo, Thomas B.; Moore, Jason H.; Scott, William K.; Lahey, Timothy; Boom, W. Henry; von Reyn, C. Fordham; Tishkoff, Sarah A.; Sirugo, Giorgio; Williams, Scott M.

    2016-01-01

    Immunosuppression resulting from HIV infection increases the risk of progression to active tuberculosis (TB) both in individuals newly exposed to Mycobacterium tuberculosis (MTB) and in those with latent infections. We hypothesized that HIV-positive individuals who do not develop TB, despite living in areas where it is hyperendemic, provide a model of natural resistance. We performed a genome-wide association study of TB resistance by using 581 HIV-positive Ugandans and Tanzanians enrolled in prospective cohort studies of TB; 267 of these individuals developed active TB, and 314 did not. A common variant, rs4921437 at 5q33.3, was significantly associated with TB (odds ratio = 0.37, p = 2.11 × 10−8). This variant lies within a genomic region that includes IL12B and is embedded in an H3K27Ac histone mark. The locus also displays consistent patterns of linkage disequilibrium across African populations and has signals of strong selection in populations from equatorial Africa. Along with prior studies demonstrating that therapy with IL-12 (the cytokine encoded in part by IL12B, associated with longer survival following MTB infection in mice deficient in CD4 T cells), our results suggest that this pathway might be an excellent target for the development of new modalities for treating TB, especially for HIV-positive individuals. Our results also indicate that studying extreme disease resistance in the face of extensive exposure can increase the power to detect associations in complex infectious disease. PMID:26942285

  9. The B-cell receptor orchestrates environment-mediated lymphoma survival and drug resistance in B-cell malignancies.

    Science.gov (United States)

    Shain, K H; Tao, J

    2014-08-01

    Specific niches within the lymphoma tumor microenvironment (TME) provide sanctuary for subpopulations of tumor cells through stromal cell-tumor cell interactions. These interactions notably dictate growth, response to therapy and resistance of residual malignant B cells to therapeutic agents. This minimal residual disease (MRD) remains a major challenge in the treatment of B-cell malignancies and contributes to subsequent disease relapse. B-cell receptor (BCR) signaling has emerged as essential mediator of B-cell homing, survival and environment-mediated drug resistance (EMDR). Central to EMDR are chemokine- and integrin-mediated interactions between lymphoma and the TME. Further, stromal cell-B cell adhesion confers a sustained BCR signaling leading to chemokine and integrin activation. Recently, the inhibitors of BCR signaling have garnered a substantial clinical interest because of their effectiveness in B-cell disorders. The efficacy of these agents is, at least in part, attributed to attenuation of BCR-dependent lymphoma-TME interactions. In this review, we discuss the pivotal role of BCR signaling in the integration of intrinsic and extrinsic determinants of TME-mediated lymphoma survival and drug resistance. PMID:24037527

  10. Mutation of Rv2887, a marR-like gene, confers Mycobacterium tuberculosis resistance to an imidazopyridine-based agent.

    Science.gov (United States)

    Winglee, Kathryn; Lun, Shichun; Pieroni, Marco; Kozikowski, Alan; Bishai, William

    2015-11-01

    Drug resistance is a major problem in Mycobacterium tuberculosis control, and it is critical to identify novel drug targets and new antimycobacterial compounds. We have previously identified an imidazo[1,2-a]pyridine-4-carbonitrile-based agent, MP-III-71, with strong activity against M. tuberculosis. In this study, we evaluated mechanisms of resistance to MP-III-71. We derived three independent M. tuberculosis mutants resistant to MP-III-71 and conducted whole-genome sequencing of these mutants. Loss-of-function mutations in Rv2887 were common to all three MP-III-71-resistant mutants, and we confirmed the role of Rv2887 as a gene required for MP-III-71 susceptibility using complementation. The Rv2887 protein was previously unannotated, but domain and homology analyses suggested it to be a transcriptional regulator in the MarR (multiple antibiotic resistance repressor) family, a group of proteins first identified in Escherichia coli to negatively regulate efflux pumps and other mechanisms of multidrug resistance. We found that two efflux pump inhibitors, verapamil and chlorpromazine, potentiate the action of MP-III-71 and that mutation of Rv2887 abrogates their activity. We also used transcriptome sequencing (RNA-seq) to identify genes which are differentially expressed in the presence and absence of a functional Rv2887 protein. We found that genes involved in benzoquinone and menaquinone biosynthesis were repressed by functional Rv2887. Thus, inactivating mutations of Rv2887, encoding a putative MarR-like transcriptional regulator, confer resistance to MP-III-71, an effective antimycobacterial compound that shows no cross-resistance to existing antituberculosis drugs. The mechanism of resistance of M. tuberculosis Rv2887 mutants may involve efflux pump upregulation and also drug methylation. PMID:26303802

  11. Gene-specific markers for the wheat gene Lr34/Yr18/Pm38 which confers resistance to multiple fungal pathogens

    Science.gov (United States)

    The locus Lr34/Yr18/Pm38 confers partial and durable resistance against the devastating fungal pathogens leaf rust, stripe rust, and powdery mildew. In previous studies, this broad-spectrum resistance was shown to be controlled by a single gene which encodes a putative ATP-binding cassette transport...

  12. Mutations in pepQ Confer Low-Level Resistance to Bedaquiline and Clofazimine in Mycobacterium tuberculosis.

    Science.gov (United States)

    Almeida, Deepak; Ioerger, Thomas; Tyagi, Sandeep; Li, Si-Yang; Mdluli, Khisimuzi; Andries, Koen; Grosset, Jacques; Sacchettini, Jim; Nuermberger, Eric

    2016-08-01

    The novel ATP synthase inhibitor bedaquiline recently received accelerated approval for treatment of multidrug-resistant tuberculosis and is currently being studied as a component of novel treatment-shortening regimens for drug-susceptible and multidrug-resistant tuberculosis. In a limited number of bedaquiline-treated patients reported to date, ≥4-fold upward shifts in bedaquiline MIC during treatment have been attributed to non-target-based mutations in Rv0678 that putatively increase bedaquiline efflux through the MmpS5-MmpL5 pump. These mutations also confer low-level clofazimine resistance, presumably by a similar mechanism. Here, we describe a new non-target-based determinant of low-level bedaquiline and clofazimine cross-resistance in Mycobacterium tuberculosis: loss-of-function mutations in pepQ (Rv2535c), which corresponds to a putative Xaa-Pro aminopeptidase. pepQ mutants were selected in mice by treatment with clinically relevant doses of bedaquiline, with or without clofazimine, and were shown to have bedaquiline and clofazimine MICs 4 times higher than those for the parental H37Rv strain. Coincubation with efflux inhibitors verapamil and reserpine lowered bedaquiline MICs against both mutant and parent strains to a level below the MIC against H37Rv in the absence of efflux pump inhibitors. However, quantitative PCR (qPCR) revealed no significant differences in expression of Rv0678, mmpS5, or mmpL5 between mutant and parent strains. Complementation of a pepQ mutant with the wild-type gene restored susceptibility, indicating that loss of PepQ function is sufficient for reduced susceptibility both in vitro and in mice. Although the mechanism by which mutations in pepQ confer bedaquiline and clofazimine cross-resistance remains unclear, these results may have clinical implications and warrant further evaluation of clinical isolates with reduced susceptibility to either drug for mutations in this gene. PMID:27185800

  13. Establishment of hepatitis C virus RNA-replicating cell lines possessing ribavirin-resistant phenotype.

    Directory of Open Access Journals (Sweden)

    Shinya Satoh

    Full Text Available Ribavirin (RBV is a potential partner of interferon-based therapy and recently approved therapy using direct acting antivirals for patients with chronic hepatitis C. However, the precise mechanisms underlying RBV action against hepatitis C virus (HCV replication are not yet understood. To clarify this point, we attempted to develop RBV-resistant cells from RBV-sensitive HCV RNA-replicating cells.By repetitive RBV (100 μM treatment (10 weeks of 3.5-year-cultured OL8 cells, in which genome-length HCV RNA (O strain of genotype 1b efficiently replicates, dozens of colonies that survived RBV treatment were obtained. These colonies were mixed together and further treated with high doses of RBV (up to 200 μM. By such RBV treatment, we successfully established 12 RBV-survived genome-length HCV RNA-replicating cell lines. Among them, three representative cell lines were characterized. HCV RNA replication in these cells resisted RBV significantly more than that in the parental OL8 cells. Genetic analysis of HCV found several common and conserved amino acid substitutions in HCV proteins among the three RBV-resistant cell species. Furthermore, using cDNA microarray and quantitative RT-PCR analyses, we identified 5 host genes whose expression levels were commonly altered by more than four-fold among these RBV-resistant cells compared with the parental cells. Moreover, to determine whether viral or host factor contributes to RBV resistance, we developed newly HCV RNA-replicating cells by introducing total RNAs isolated from RBV-sensitive parental cells or RBV-resistant cells into the HCV RNA-cured-parental or -RBV-resistant cells using an electroporation method, and evaluated the degrees of RBV resistance of these developed cells. Consequently, we found that RBV-resistant phenotype was conferred mainly by host factor and partially by viral factor.These newly established HCV RNA-replicating cell lines should become useful tools for further understanding the

  14. Overexpression of a rice heme activator protein gene (OsHAP2E) confers resistance to pathogens, salinity and drought, and increases photosynthesis and tiller number.

    Science.gov (United States)

    Alam, Md Mahfuz; Tanaka, Toru; Nakamura, Hidemitsu; Ichikawa, Hiroaki; Kobayashi, Kappei; Yaeno, Takashi; Yamaoka, Naoto; Shimomoto, Kota; Takayama, Kotaro; Nishina, Hiroshige; Nishiguchi, Masamichi

    2015-01-01

    Heme activator protein (HAP), also known as nuclear factor Y or CCAAT binding factor (HAP/NF-Y/CBF), has important functions in regulating plant growth, development and stress responses. The expression of rice HAP gene (OsHAP2E) was induced by probenazole (PBZ), a chemical inducer of disease resistance. To characterize the gene, the chimeric gene (OsHAP2E::GUS) engineered to carry the structural gene encoding β-glucuronidase (GUS) driven by the promoter from OsHAP2E was introduced into rice. The transgenic lines of OsHAP2Ein::GUS with the intron showed high GUS activity in the wounds and surrounding tissues. When treated by salicylic acid (SA), isonicotinic acid (INA), abscisic acid (ABA) and hydrogen peroxide (H2 O2 ), the lines showed GUS activity exclusively in vascular tissues and mesophyll cells. This activity was enhanced after inoculation with Magnaporthe oryzae or Xanthomonas oryzae pv. oryzae. The OsHAP2E expression level was also induced after inoculation of rice with M. oryzae and X. oryzae pv. oryzae and after treatment with SA, INA, ABA and H2 O2, respectively. We further produced transgenic rice overexpressing OsHAP2E. These lines conferred resistance to M. oryzae or X. oryzae pv. oryzae and to salinity and drought. Furthermore, they showed a higher photosynthetic rate and an increased number of tillers. Microarray analysis showed up-regulation of defence-related genes. These results suggest that this gene could contribute to conferring biotic and abiotic resistances and increasing photosynthesis and tiller numbers. PMID:25168932

  15. Transactivation of the TIEG1 confers growth inhibition of transforming growth factor-β-susceptible hepatocellular carcinoma cells

    Institute of Scientific and Technical Information of China (English)

    Lei Jiang; Yiu-Kay Lai; Jin-Fang Zhang; Chu-Yan Chan; Gang Lu; Marie CM Lin; Ming-Liang He; Ji-Cheng Li; Hsiang-Fu Kung

    2012-01-01

    AIM:To investigate the role of transforming growth factor (TGF)-β-inducible early gene 1 (TIEG1) in TGF-β-induced growth inhibition in hepatocellular carcinoma (HCC) cells.METHODS:Human hepatocyte and HCC cell lines with varied susceptibilities to TGF-β1 were tested by methylthiazoletetrazolium (MTT) assay.The expression changes of Smad2,Smad3,Smad4,Smad7,TIEG1 and TIEG2 gene following treatment with TGF-β1 in a TGF-β-sensitive hepatocyte cell line (MIHA),a TGF-β-sensitive hepatoma cell line (Hep3B) and two TGF-β-insensitive hepatoma cell lines (HepG2 and Bel7404)were examined.SiRNA targeting TIEG1 was transfected into Hep3B cells and the sensitivity of cells to TGF-β1 was examined.Overexpression of TIEG1 was induced by lentiviral-mediated transduction in TGF-β1-resistant hepatoma cell lines (Bel7404 and HepG2).MTT assay and 4',6-Diamidino-2-phenylindole staining were used to identify cell viability and apoptosis,respectively.The expression level of stathmin was measured by reverse transcriptase polymerase chain reaction and Western-blotting analysis,and stathmin promoter activity by TIEG1 was monitored by a luciferase reporter gene system.RESULTS:TIEG1 was significantly upregulated by TGF-β1 in the TGF-β1-sensitive HCC cell line,Hep3B,but not in the resistant cell lines.The suppression of TIEG1 by siRNAs decreased the sensitivity of Hep3B cells to TGF-β1,whereas the overexpression of TIEG1 mediated growth inhibition and apoptosis in TGF-β1-resistant HCC cell lines,which resembled those of TGF-β1-sensitive HCC cells treated with TGF-β1.Our data further suggested that stathmin was a direct target of TIEG1,as stathmin was significantly downregulated by TIEG1 overexpression,and stathmin promoter activity was inhibited by TIEG1 in a dose-dependent manner.CONCLUSION:Our data suggest that transactivation of TIEG1 conferred growth inhibition of TGF-β-susceptible human HCC cells.

  16. Expression, purification, crystallization, and preliminary X-ray crystallographic analysis of OXA-17, an extended-spectrum {beta}-lactamase conferring severe antibiotic resistance

    Energy Technology Data Exchange (ETDEWEB)

    Lee, J. H., E-mail: msgjhlee@mju.ac.kr; Sohn, S. G., E-mail: sgsohn@mju.ac.kr; Jung, H. I., E-mail: jhinumber1@hanmail.net; An, Y. J., E-mail: anyj0120@hanmail.net; Lee, S. H., E-mail: sangheelee@mju.ac.kr [Myongji University, Drug Resistance Proteomics Laboratory, Department of Biological Sciences (Korea, Republic of)

    2013-07-15

    OXA-17, an extended-spectrum {beta}-lactamase (ESBL) conferring severe antibiotic resistance, hydrolytically inactivates {beta}-lactam antibiotics, inducing a lack of eradication of pathogenic bacteria by oxyimino {beta}-lactams and not helping hospital infection control. Thus, the enzyme is a potential target for developing antimicrobial agents against pathogens producing ESBLs. OXA-17 was purified and crystallized at 298 K. X-ray diffraction data from OXA-17 crystal have been collected to 1.85 A resolution using synchrotron radiation. The crystal of OXA-17 belongs to space group P2{sub 1}2{sub 1}2{sub 1}, with unit-cell parameters a = 48.37, b = 101.12, and c = 126.07 A. Analysis of the packing density shows that the asymmetric unit probably contains two molecules with a solvent content of 54.6%.

  17. Insect Resistance to Bacillus thuringiensis Toxin Cry2Ab Is Conferred by Mutations in an ABC Transporter Subfamily A Protein.

    Directory of Open Access Journals (Sweden)

    Wee Tek Tay

    2015-11-01

    Full Text Available The use of conventional chemical insecticides and bacterial toxins to control lepidopteran pests of global agriculture has imposed significant selection pressure leading to the rapid evolution of insecticide resistance. Transgenic crops (e.g., cotton expressing the Bt Cry toxins are now used world wide to control these pests, including the highly polyphagous and invasive cotton bollworm Helicoverpa armigera. Since 2004, the Cry2Ab toxin has become widely used for controlling H. armigera, often used in combination with Cry1Ac to delay resistance evolution. Isolation of H. armigera and H. punctigera individuals heterozygous for Cry2Ab resistance in 2002 and 2004, respectively, allowed aspects of Cry2Ab resistance (level, fitness costs, genetic dominance, complementation tests to be characterised in both species. However, the gene identity and genetic changes conferring this resistance were unknown, as was the detailed Cry2Ab mode of action. No cross-resistance to Cry1Ac was observed in mutant lines. Biphasic linkage analysis of a Cry2Ab-resistant H. armigera family followed by exon-primed intron-crossing (EPIC marker mapping and candidate gene sequencing identified three independent resistance-associated INDEL mutations in an ATP-Binding Cassette (ABC transporter gene we named HaABCA2. A deletion mutation was also identified in the H. punctigera homolog from the resistant line. All mutations truncate the ABCA2 protein. Isolation of further Cry2Ab resistance alleles in the same gene from field H. armigera populations indicates unequal resistance allele frequencies and the potential for Bt resistance evolution. Identification of the gene involved in resistance as an ABC transporter of the A subfamily adds to the body of evidence on the crucial role this gene family plays in the mode of action of the Bt Cry toxins. The structural differences between the ABCA2, and that of the C subfamily required for Cry1Ac toxicity, indicate differences in the

  18. Insect Resistance to Bacillus thuringiensis Toxin Cry2Ab Is Conferred by Mutations in an ABC Transporter Subfamily A Protein.

    Science.gov (United States)

    Tay, Wee Tek; Mahon, Rod J; Heckel, David G; Walsh, Thomas K; Downes, Sharon; James, William J; Lee, Sui-Fai; Reineke, Annette; Williams, Adam K; Gordon, Karl H J

    2015-11-01

    The use of conventional chemical insecticides and bacterial toxins to control lepidopteran pests of global agriculture has imposed significant selection pressure leading to the rapid evolution of insecticide resistance. Transgenic crops (e.g., cotton) expressing the Bt Cry toxins are now used world wide to control these pests, including the highly polyphagous and invasive cotton bollworm Helicoverpa armigera. Since 2004, the Cry2Ab toxin has become widely used for controlling H. armigera, often used in combination with Cry1Ac to delay resistance evolution. Isolation of H. armigera and H. punctigera individuals heterozygous for Cry2Ab resistance in 2002 and 2004, respectively, allowed aspects of Cry2Ab resistance (level, fitness costs, genetic dominance, complementation tests) to be characterised in both species. However, the gene identity and genetic changes conferring this resistance were unknown, as was the detailed Cry2Ab mode of action. No cross-resistance to Cry1Ac was observed in mutant lines. Biphasic linkage analysis of a Cry2Ab-resistant H. armigera family followed by exon-primed intron-crossing (EPIC) marker mapping and candidate gene sequencing identified three independent resistance-associated INDEL mutations in an ATP-Binding Cassette (ABC) transporter gene we named HaABCA2. A deletion mutation was also identified in the H. punctigera homolog from the resistant line. All mutations truncate the ABCA2 protein. Isolation of further Cry2Ab resistance alleles in the same gene from field H. armigera populations indicates unequal resistance allele frequencies and the potential for Bt resistance evolution. Identification of the gene involved in resistance as an ABC transporter of the A subfamily adds to the body of evidence on the crucial role this gene family plays in the mode of action of the Bt Cry toxins. The structural differences between the ABCA2, and that of the C subfamily required for Cry1Ac toxicity, indicate differences in the detailed mode

  19. Antisense expression of peach mildew resistance locus O (PpMlo1) gene confers cross-species resistance to powdery mildew in Fragaria x ananassa.

    Science.gov (United States)

    Jiwan, Derick; Roalson, Eric H; Main, Dorrie; Dhingra, Amit

    2013-12-01

    Powdery mildew (PM) is one of the major plant pathogens. The conventional method of PM control includes frequent use of sulfur-based fungicides adding to production costs and potential harm to the environment. PM remains a major scourge for Rosaceae crops where breeding approaches mainly resort to gene-for-gene resistance. We have tested an alternate source of PM resistance in Rosaceae. Mildew resistance locus O (MLO) has been well studied in barley due to its role in imparting broad spectrum resistance to PM. We identified PpMlo1 (Prunus persica Mlo) in peach and characterized it further to test if a similar mechanism of resistance is conserved in Rosaceae. Due to its recalcitrance in tissue culture, reverse genetic studies involving PpMloI were not feasible in peach. Therefore, Fragaria x ananassa LF9 line, a taxonomic surrogate, was used for functional analysis of PpMlo1. Agrobacterium-mediated transformation yielded transgenic strawberry plants expressing PpMlo1 in sense and antisense orientation. Antisense expression of PpMlo1 in transgenic strawberry plants conferred resistance to Fragaria-specific powdery mildew, Podosphaera macularis. Phylogenetic analysis of 208 putative Mlo gene copies from 35 plant species suggests a large number of duplications of this gene family prior to the divergence of monocots and eudicots, early in eudicot diversification. Our results indicate that the Mlo-based resistance mechanism is functional in Rosaceae, and that Fragaria can be used as a host to test mechanistic function of genes derived from related tree species. To the best of our knowledge, this work is one of the first attempts at testing the potential of using a Mlo-based resistance strategy to combat powdery mildew in Rosaceae.

  20. Decreased drug accumulation and increased tolerance to DNA damage in tumor cells with a low level of cisplatin resistance.

    Science.gov (United States)

    Lanzi, C; Perego, P; Supino, R; Romanelli, S; Pensa, T; Carenini, N; Viano, I; Colangelo, D; Leone, R; Apostoli, P; Cassinelli, G; Gambetta, R A; Zunino, F

    1998-04-15

    In an attempt to examine the cellular changes associated with cisplatin resistance, we selected a cisplatin-resistant (A43 1/Pt) human cervix squamous cell carcinoma cell line following continuous in vitro drug exposure. The resistant subline was characterized by a 2.5-fold degree of resistance. In particular, we investigated the expression of cellular defence systems and other cellular factors probably involved in dealing with cisplatin-induced DNA damage. Resistant cells exhibited decreased platinum accumulation and reduced levels of DNA-bound platinum and interstrand cross-link frequency after short-term drug exposure. Analysis of the effect of cisplatin on cell cycle progression revealed a cisplatin-induced G2M arrest in sensitive and resistant cells. Interestingly, a slowdown in S-phase transit was found in A431/Pt cells. A comparison of the ability of sensitive and resistant cells to repair drug-induced DNA damage suggested that resistant cells were able to tolerate higher levels of cisplatin-induced DNA damage than their parental counterparts. Analysis of the expression of proteins involved in DNA mismatch repair showed a decreased level of MSH2 in resistant cells. Since MSH2 seems to be involved in recognition of drug-induced DNA damage, this change may account for the increased tolerance to DNA damage observed in the resistant subline. In conclusion, the involvement of accumulation defects and the increased tolerance to cisplatin-induced DNA damage in these cisplatin-resistant cells support the notion that multiple changes contribute to confer a low level of cisplatin resistance. PMID:9719480

  1. Stem cells and cancer immunotherapy: Arrowhead’s 2nd annual cancer immunotherapy conference

    OpenAIRE

    Bot, Adrian; Chiriva-Internati, Maurizio; Cornforth, Andrew; Brian J Czerniecki; Ferrone, Soldano; Geles, Kenneth; Greenberg, Philip D.; Hurt, Elaine; Koya, Richard C.; Masoud H Manjili; Matsui, William; Morgan, Richard A.; Palena, Claudia M; Powell Jr, Daniel J; Restifo, Nicholas P

    2014-01-01

    Investigators from academia and industry gathered on April 4 and 5, 2013, in Washington DC at the Arrowhead’s 2nd Annual Cancer Immunotherapy Conference. Two complementary concepts were discussed: cancer “stem cells” as targets and therapeutic platforms based on stem cells.

  2. An AFLP marker linked to the Pm-1 gene that confers resistance to Podosphaera xanthii race 1 in Cucumis melo

    Directory of Open Access Journals (Sweden)

    Ana Paula Matoso Teixeira

    2008-01-01

    Full Text Available Brazil produced 330,000 metric tons of melons in 2005, principally in the Northeast region where one of the most important melon pathogens is the powdery mildew fungus Podosphaera xanthii. The disease is controlled mainly by incorporating single dominant resistance genes into commercial hybrids. We report on linkage analysis of the Pm-1 resistance gene, introgressed from the AF125Pm-1 Cantalupensis Charentais-type breeding line into the yellow-fleshed melon (Group Inodorus breeding line AF426-S by backcrossing to produce the resistant line AF426-R, and the amplified fragment length polymorphism (AFLP marker M75/H35_155 reported to be polymorphic between AF426-S and AF426-R. Segregation analysis of M75/H35_155 using a backcross population of 143 plants derived from [AF426-R x AF426-S] x AF426-S and screened for resistance to P. xanthii race 1 produced a recombination frequency of 4.9%, indicating close linkage between M75/H35_155 and Pm-1. Using the same segregating population, the M75/H35_155 marker had previously been reported to be distantly linked to Prv¹, a gene conferring resistance to papaya ringspot virus-type W. Since M75/H35_155 is linked to Prv¹ at a distance of 40.9 cM it is possible that Pm-1 and Prv¹ are also linked.

  3. FabH Mutations Confer Resistance to FabF-Directed Antibiotics in Staphylococcus aureus

    OpenAIRE

    Parsons, Joshua B.; Yao, Jiangwei; Frank, Matthew W.; Rock, Charles O.

    2014-01-01

    Delineating the mechanisms for genetically acquired antibiotic resistance is a robust approach to target validation and anticipates the evolution of clinical drug resistance. This study defines a spectrum of mutations in fabH that render Staphylococcus aureus resistant to multiple natural products known to inhibit the elongation condensing enzyme (FabF) of bacterial type II fatty acid synthesis. Twenty independently isolated clones resistant to platensimycin, platencin, or thiolactomycin were...

  4. Constitutively-active androgen receptor variants function independently of the HSP90 chaperone but do not confer resistance to HSP90 inhibitors.

    Science.gov (United States)

    Gillis, Joanna L; Selth, Luke A; Centenera, Margaret M; Townley, Scott L; Sun, Shihua; Plymate, Stephen R; Tilley, Wayne D; Butler, Lisa M

    2013-05-01

    The development of lethal, castration resistant prostate cancer is associated with adaptive changes to the androgen receptor (AR), including the emergence of mutant receptors and truncated, constitutively active AR variants. AR relies on the molecular chaperone HSP90 for its function in both normal and malignant prostate cells, but the requirement for HSP90 in environments with aberrant AR expression is largely unknown. Here, we investigated the efficacy of three HSP90 inhibitors, 17-AAG, HSP990 and AUY922, against clinically-relevant AR missense mutants and truncated variants. HSP90 inhibition effectively suppressed the signaling of wild-type AR and all AR missense mutants tested. By contrast, two truncated AR variants, AR-V7 and ARv567es, exhibited marked resistance to HSP90 inhibitors. Supporting this observation, nuclear localization of the truncated AR variants was not affected by HSP90 inhibition and AR variant:HSP90 complexes could not be detected in prostate cancer cells. Interestingly, HSP90 inhibition resulted in accumulation of AR-V7 and ARv567es in both cell lines and human tumor explants. Despite the apparent independence of AR variants from HSP90 and their treatment-associated induction, the growth of cell lines with endogenous or enforced expression of AR-V7 or ARv567es remained highly sensitive to AUY922. This study demonstrates that functional AR variant signaling does not confer resistance to HSP90 inhibition, yields insight into the interaction between AR and HSP90 and provides further impetus for the clinical application of HSP90 inhibitors in advanced prostate cancer.

  5. Phloem-specific expression of the lectin gene from Allium sativum confers resistance to the sap-sucker Nilaparvata lugens.

    Science.gov (United States)

    Chandrasekhar, Kottakota; Vijayalakshmi, Muvva; Vani, Kalasamudramu; Kaul, Tanushri; Reddy, Malireddy K

    2014-05-01

    Rice production is severely hampered by insect pests. Garlic lectin gene (ASAL) holds great promise in conferring protection against chewing (lepidopteran) and sap-sucking (homopteran) insect pests. We have developed transgenic rice lines resistant to sap-sucking brown hopper (Nilaparvata lugens) by ectopic expression of ASAL in their phloem tissues. Molecular analyses of T0 lines confirmed stable integration of transgene. T1 lines (NP 1-2, 4-3, 11-6 & 17-7) showed active transcription and translation of ASAL transgene. ELISA revealed ASAL expression was as high as 0.95% of total soluble protein. Insect bioassays on T2 homozygous lines (NP 18 & 32) revealed significant reduction (~74-83%) in survival rate, development and fecundity of brown hoppers in comparison to wild type. Transgenics exhibited enhanced resistance (1-2 score) against brown hoppers, minimal plant damage and no growth penalty or phenotypic abnormalities. PMID:24563293

  6. Activation of cells using femtosecond laser beam (Conference Presentation)

    Science.gov (United States)

    Batabyal, Subrata; Satpathy, Sarmishtha; Kim, Young-tae; Mohanty, Samarendra K.

    2016-03-01

    Study of communication in cellular systems requires precise activation of targeted cell(s) in the network. In contrast to chemical, electrical, thermal, mechanical stimulation, optical stimulation is non-invasive and is better suited for stimulation of targeted cells. As compared to visible lasers, the near infrared (NIR) microsecond/nanosecond pulsed laser beams are being used as preferred stimulation tool as they provide higher penetration depth in tissues. Femotosecond (FS) laser beams in NIR are also being used for direct and indirect (i.e. via two-photon optogenetics) stimulation of cells. Here, we present a comparative evaluation of efficacy of NIR FS laser beam for direct (no optogenetic sensitization) and 2ph optogenetic stimulation of cells. Further, for the first time, we demonstrate the use of blue (~450 nm, obtained by second harmonic generation) FS laser beam for stimulation of cells with and without Channelrhodopisn-2 (ChR2) expression. Comparative analysis of photocurrent generated by blue FS laser beam and continuous wave blue light for optogenetics stimulation of ChR2 transfected HEK cells will be presented. The use of ultrafast laser micro-beam for focal, non-contact, and repeated stimulation of single cells in a cellular circuitry allowed us to study the communication between different cell types.

  7. GSK-3β inhibition by lithium confers resistance to chemotherapy-induced apoptosis through the repression of CD95 (Fas/APO-1) expression

    International Nuclear Information System (INIS)

    Lithium exerts neuroprotective actions that involve the inhibition of glycogen synthase kinase-3β (GSK-3β). Otherwise, recent studies suggest that sustained GSK-3β inhibition is a hallmark of tumorigenesis. In this context, the present study was undertaken to examine whether lithium modulated cancer cell sensitivity to apoptosis induced by chemotherapy agents. We observed that, in different human cancer cell lines, lithium significantly reduced etoposide- and camptothecin-induced apoptosis. In HepG2 cells, lithium repressed drug induction of CD95 expression and clustering at the cell surface as well as caspase-8 activation. Lithium acted through deregulation of GSK-3β signaling since (1) it provoked a rapid and sustained phosphorylation of GSK-3β on the inhibitory serine 9 residue; (2) the GSK-3β inhibitor SB-415286 mimicked lithium effects by repressing drug-induced apoptosis and CD95 membrane expression; and (3) lithium promoted the disruption of nuclear GSK-3β/p53 complexes. Moreover, the overexpression of an inactivated GSK-3β mutant counteracted the stimulatory effects of etoposide and camptothecin on a luciferase reporter plasmid driven by a p53-responsive sequence from the CD95 gene. In conclusion, we provide the first evidence that lithium confers resistance to apoptosis in cancer cells through GSK-3β inhibition and subsequent repression of CD95 gene expression. Our study also highlights the concerted action of GSK-3β and p53 on CD95 gene expression

  8. HLA-DRB1-DQB1 haplotypes confer susceptibility and resistance to multiple sclerosis in Sardinia.

    Directory of Open Access Journals (Sweden)

    Eleonora Cocco

    :02, *06:01 alleles. CONCLUSIONS: These findings show that the association of specific, independent DRB1*-DQB1* haplotypes confers susceptibility or resistance to MS in the MS-prone Sardinian population. The data also supports a functional role for specific residues of the DRB1 and DQB1 proteins in predisposing patients to MS.

  9. Multiple Patterns of Regulation and Overexpression of a Ribonuclease-Like Pathogenesis-Related Protein Gene, OsPR10a, Conferring Disease Resistance in Rice and Arabidopsis

    Science.gov (United States)

    He, Siou-Luan; Chen, Jyh-Lang; Jiang, Jian-Zhi; Chen, Bo-Hong; Hou, Yi-Syuan; Chen, Ruey-Shyang; Hong, Chwan-Yang; Ho, Shin-Lon

    2016-01-01

    An abundant 17 kDa RNase, encoded by OsPR10a (also known as PBZ1), was purified from Pi-starved rice suspension-cultured cells. Biochemical analysis showed that the range of optimal temperature for its RNase activity was 40–70°C and the optimum pH was 5.0. Disulfide bond formation and divalent metal ion Mg2+ were required for the RNase activity. The expression of OsPR10a::GUS in transgenic rice was induced upon phosphate (Pi) starvation, wounding, infection by the pathogen Xanthomonas oryzae pv. oryzae (Xoo), leaf senescence, anther, style, the style-ovary junction, germinating embryo and shoot. We also provide first evidence in whole-plant system, demonstrated that OsPR10a-overexpressing in rice and Arabidopsis conferred significant level of enhanced resistance to infection by the pathogen Xoo and Xanthomona campestris pv. campestris (Xcc), respectively. Transgenic rice and Arabidopsis overexpressing OsPR10a significantly increased the length of primary root under phosphate deficiency (-Pi) condition. These results showed that OsPR10a might play multiple roles in phosphate recycling in phosphate-starved cells and senescing leaves, and could improve resistance to pathogen infection and/or against chewing insect pests. It is possible that Pi acquisition or homeostasis is associated with plant disease resistance. Our findings suggest that gene regulation of OsPR10a could act as a good model system to unravel the mechanisms behind the correlation between Pi starvation and plant-pathogen interactions, and also provides a potential application in crops disease resistance. PMID:27258121

  10. Bordetella pertussis lipid A glucosamine modification confers resistance to cationic antimicrobial peptides and increases resistance to outer membrane perturbation.

    Science.gov (United States)

    Shah, Nita R; Hancock, Robert E W; Fernandez, Rachel C

    2014-08-01

    Bordetella pertussis, the causative agent of whooping cough, has many strategies for evading the human immune system. Lipopolysaccharide (LPS) is an important Gram-negative bacterial surface structure that activates the immune system via Toll-like receptor 4 and enables susceptibility to cationic antimicrobial peptides (CAMPs). We show modification of the lipid A region of LPS with glucosamine increased resistance to numerous CAMPs, including LL-37. Furthermore, we demonstrate that this glucosamine modification increased resistance to outer membrane perturbation.

  11. The bacterial DNA repair protein Mfd confers resistance to the host nitrogen immune response.

    Science.gov (United States)

    Guillemet, Elisabeth; Leréec, Alain; Tran, Seav-Ly; Royer, Corinne; Barbosa, Isabelle; Sansonetti, Philippe; Lereclus, Didier; Ramarao, Nalini

    2016-01-01

    Production of reactive nitrogen species (NO) is a key step in the immune response following infections. NO induces lesions to bacterial DNA, thus limiting bacterial growth within hosts. Using two pathogenic bacteria, Bacillus cereus and Shigella flexneri, we show that the DNA-repair protein Mfd (Mutation-Frequency-Decline) is required for bacterial resistance to the host-NO-response. In both species, a mutant deficient for mfd does not survive to NO, produced in vitro or by phagocytic cells. In vivo, the ∆mfd mutant is avirulent and unable to survive the NO-stress. Moreover, NO induces DNA-double-strand-breaks and point mutations in the Δmfd mutant. In overall, these observations demonstrate that NO damages bacterial DNA and that Mfd is required to maintain bacterial genomic integrity. This unexpected discovery reveals that Mfd, a typical housekeeping gene, turns out to be a true virulence factor allowing survival and growth of the pathogen in its host, due to its capacity to protect the bacterium against NO, a key molecule of the innate immune defense. As Mfd is widely conserved in the bacterial kingdom, these data highlight a mechanism that may be used by a large spectrum of bacteria to overcome the host immune response and especially the mutagenic properties of NO. PMID:27435260

  12. Suppression of phospholipase Dγs confers increased aluminum resistance in Arabidopsis thaliana.

    Directory of Open Access Journals (Sweden)

    Jian Zhao

    Full Text Available Aluminum (Al toxicity is the major stress in acidic soil that comprises about 50% of the world's arable land. The complex molecular mechanisms of Al toxicity have yet to be fully determined. As a barrier to Al entrance, plant cell membranes play essential roles in plant interaction with Al, and lipid composition and membrane integrity change significantly under Al stress. Here, we show that phospholipase Dγs (PLDγs are induced by Al stress and contribute to Al-induced membrane lipid alterations. RNAi suppression of PLDγ resulted in a decrease in both PLDγ1 and PLDγ2 expression and an increase in Al resistance. Genetic disruption of PLDγ1 also led to an increased tolerance to Al while knockout of PLDγ2 did not. Both RNAi-suppressed and pldγ1-1 mutants displayed better root growth than wild-type under Al stress conditions, and PLDγ1-deficient plants had less accumulation of callose, less oxidative damage, and less lipid peroxidation compared to wild-type plants. Most phospholipids and glycolipids were altered in response to Al treatment of wild-type plants, whereas fewer changes in lipids occurred in response to Al stress in PLDγ mutant lines. Our results suggest that PLDγs play a role in membrane lipid modulation under Al stress and that high activities of PLDγs negatively modulate plant tolerance to Al.

  13. Resistance to Onchocerca lienalis microfilariae in mice conferred by egg antigens of homologous and heterologous Onchocerca species.

    Science.gov (United States)

    Carlow, C K; Bianco, A E

    1987-06-01

    Embryonic stages of various Onchocerca species have been used to stimulate resistance in CBA mice to challenge injections with the microfilariae of Onchocerca lienalis. Comparable levels of resistance to challenge (29-37% reductions) were conferred by living, freeze-killed, or sonicated organisms administered with Freunds' Complete Adjuvant (FCA). Antigens extracted in saline, or with the detergent sodium deoxycholate, were also protective. Adjuvants enhanced the protective effect, particularly FCA (78% reduction), Freunds' Incomplete Adjuvant (74% reduction), aluminum hydroxide (70% reduction) and Bordetella pertussis (70% reduction). Detergent extracts prepared from intact embryos with n-octyl glucoside also stimulated significant levels of protection against microfilarial challenge when given with FCA (37-45% reductions). Levels of resistance induced by immunizations with intact organisms were greatest following subcutaneous (s.c.) injection over the neck or by intramuscular inoculation. Soluble extracts were also particially effective given by s.c. inguinal or intraperitoneal injection. A time-interval of greater than 3 weeks between the completion of immunization and challenge was required for the expression of immunity. Cross-protection against challenge with O. lienalis microfilariae was also afforded to mice by immunization with intact embryos or detergent extracts of Onchocerca gutturosa (45 and 34% reductions), Onchocerca gibsoni (66 and 47% reductions) or Onchocerca volvulus (58 and 41% reductions). It is concluded that the embryonic stages of both human and animal parasites provide a source of cross-protective antigens of value in studies on resistance to Onchocerca microfilariae in experimental hosts.

  14. Treatment Resistance Mechanisms of Malignant Glioma Tumor Stem Cells

    International Nuclear Information System (INIS)

    Malignant gliomas are highly lethal because of their resistance to conventional treatments. Recent evidence suggests that a minor subpopulation of cells with stem cell properties reside within these tumors. These tumor stem cells are more resistant to radiation and chemotherapies than their counterpart differentiated tumor cells and may underlie the persistence and recurrence of tumors following treatment. The various mechanisms by which tumor stem cells avoid or repair the damaging effects of cancer therapies are discussed

  15. Treatment Resistance Mechanisms of Malignant Glioma Tumor Stem Cells

    Energy Technology Data Exchange (ETDEWEB)

    Schmalz, Philip G.R. [Surgical and Molecular Neuro-Oncology Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892 (United States); Howard Hughes Medical Institute, National Institutes of Health Research Scholars Program, Bethesda, MD 20892 (United States); Shen, Michael J.; Park, John K., E-mail: parkjk@ninds.nih.gov [Surgical and Molecular Neuro-Oncology Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892 (United States)

    2011-02-10

    Malignant gliomas are highly lethal because of their resistance to conventional treatments. Recent evidence suggests that a minor subpopulation of cells with stem cell properties reside within these tumors. These tumor stem cells are more resistant to radiation and chemotherapies than their counterpart differentiated tumor cells and may underlie the persistence and recurrence of tumors following treatment. The various mechanisms by which tumor stem cells avoid or repair the damaging effects of cancer therapies are discussed.

  16. Bone marrow stromal cells from multiple myeloma patients uniquely induce bortezomib resistant NF-κB activity in myeloma cells

    Directory of Open Access Journals (Sweden)

    Kim KyungMann

    2010-07-01

    Full Text Available Abstract Background Components of the microenvironment such as bone marrow stromal cells (BMSCs are well known to support multiple myeloma (MM disease progression and resistance to chemotherapy including the proteasome inhibitor bortezomib. However, functional distinctions between BMSCs in MM patients and those in disease-free marrow are not completely understood. We and other investigators have recently reported that NF-κB activity in primary MM cells is largely resistant to the proteasome inhibitor bortezomib, and that further enhancement of NF-κB by BMSCs is similarly resistant to bortezomib and may mediate resistance to this therapy. The mediating factor(s of this bortezomib-resistant NF-κB activity is induced by BMSCs is not currently understood. Results Here we report that BMSCs specifically derived from MM patients are capable of further activating bortezomib-resistant NF-κB activity in MM cells. This induced activity is mediated by soluble proteinaceous factors secreted by MM BMSCs. Among the multiple factors evaluated, interleukin-8 was secreted by BMSCs from MM patients at significantly higher levels compared to those from non-MM sources, and we found that IL-8 contributes to BMSC-induced NF-κB activity. Conclusions BMSCs from MM patients uniquely enhance constitutive NF-κB activity in MM cells via a proteinaceous secreted factor in part in conjunction with IL-8. Since NF-κB is known to potentiate MM cell survival and confer resistance to drugs including bortezomib, further identification of the NF-κB activating factors produced specifically by MM-derived BMSCs may provide a novel biomarker and/or drug target for the treatment of this commonly fatal disease.

  17. Quiescent cells: A natural way to resist chemotherapy

    Science.gov (United States)

    Menchón, S. A.; Condat, C. A.

    2011-10-01

    Most chemotherapeutic treatments use drugs that target proliferating cancer cells. Therefore, they do not affect quiescent cells which are naturally resistant. Surviving cancer cells can reactivate their cell cycles in the intervals between doses, becoming proliferative again and thus restarting tumor growth. In this work, we present a mathematical model to study the impact of quiescent cells on chemotherapy effectiveness. Our simulations show that, although tumor growth is delayed after the beginning of each dose, the resistance of quiescent cells is enough to reactivate it due to accelerated repopulation, eventually causing therapy failure even in the absence of acquired resistance.

  18. Mutations in 23S rRNA Confer Resistance against Azithromycin in Pseudomonas aeruginosa

    DEFF Research Database (Denmark)

    Marvig, Rasmus Lykke; Søndergaard, Mette S. R.; Pedersen, Søren Damkiær;

    2012-01-01

    The emergence of antibiotic-resistant Pseudomonas aeruginosa is an important concern in the treatment of long-term airway infections in cystic fibrosis patients. In this study, we report the occurrence of azithromycin resistance among clinical P. aeruginosa DK2 isolates. We demonstrate...... that resistance is associated with specific mutations (A2058G, A2059G, and C2611T in Escherichia coli numbering) in domain V of 23S rRNA and that introduction of A2058G and C2611T into strain PAO1 results in azithromycin resistance....

  19. Inhibition of autophagy overcomes glucocorticoid resistance in lymphoid malignant cells.

    Science.gov (United States)

    Jiang, Lei; Xu, Lingzhi; Xie, Jiajun; Li, Sisi; Guan, Yanchun; Zhang, Yan; Hou, Zhijie; Guo, Tao; Shu, Xin; Wang, Chang; Fan, Wenjun; Si, Yang; Yang, Ya; Kang, Zhijie; Fang, Meiyun; Liu, Quentin

    2015-01-01

    Glucocorticoid (GC) resistance remains a major obstacle to successful treatment of lymphoid malignancies. Till now, the precise mechanism of GC resistance remains unclear. In the present study, dexamethasone (Dex) inhibited cell proliferation, arrested cell cycle in G0/G1-phase, and induced apoptosis in Dex-sensitive acute lymphoblastic leukemia cells. However, Dex failed to cause cell death in Dex-resistant lymphoid malignant cells. Intriguingly, we found that autophagy was induced by Dex in resistant cells, as indicated by autophagosomes formation, LC3-I to LC3-II conversion, p62 degradation, and formation of acidic autophagic vacuoles. Moreover, the results showed that Dex reduced the activity of mTOR pathway, as determined by decreased phosphorylation levels of mTOR, Akt, P70S6K and 4E-BP1 in resistant cells. Inhibition of autophagy by either chloroquine (CQ) or 3-methyladenine (3-MA) overcame Dex-resistance in lymphoid malignant cells by increasing apoptotic cell death in vitro. Consistently, inhibition of autophagy by stably knockdown of Beclin1 sensitized Dex-resistant lymphoid malignant cells to induction of apoptosis in vivo. Thus, inhibition of autophagy has the potential to improve lymphoid malignancy treatment by overcoming GC resistance.

  20. Replication fork stability confers chemoresistance in BRCA-deficient cells

    DEFF Research Database (Denmark)

    Chaudhuri, Arnab Ray; Callen, Elsa; Ding, Xia;

    2016-01-01

    Cells deficient in the Brca1 and Brca2 genes have reduced capacity to repair DNA double-strand breaks by homologous recombination and consequently are hypersensitive to DNA-damaging agents, including cisplatin and poly(ADP-ribose) polymerase (PARP) inhibitors. Here we show that loss of the MLL3/4...

  1. Nano-enhanced optical delivery into targeted cells (Conference Presentation)

    Science.gov (United States)

    Wright, Weldon; Pradhan, Sanjay

    2016-03-01

    Nano-enhanced optical field of gold nanoparticles allowed the use of a continuous wave (cw) laser beam for efficient delivery of exogenous impermeable materials into targeted cells. Using this Nano-enhanced Optical Delivery (NOD) method, we show that large molecules could be delivered with low power cw laser with exposure time ~ 1sec. At such low power (and exposure), the non-targeted cells (not bound to gold nanoparticles) were not adversely affected by the laser beam. Further, by varying the size of the gold nanoparticles, cells could be exclusively sensitized to selective wavelengths of laser beam. In contrast other nanoparticles, gold nanoparticles were found to have lower cytotoxicity, making it better suited for clinical NOD. Further, as compared with pulsed lasers, cw (diode) lasers are compact, easy-to-use and therefore, NOD using cw laser beam has significant translational potential for delivery of impermeable bio-molecules to tissues in different organs. We will present optimization of NOD parameters for delivering different molecules to different cells. Success of this NOD method may lead to a new clinical approach for treating AMD and RP patients with geographic atrophy in retina.

  2. RAPD markers linked to a block of genes conferring rust resistance to the common bean

    Directory of Open Access Journals (Sweden)

    Faleiro Fábio Gelape

    2000-01-01

    Full Text Available Rust, caused by the fungus Uromyces appendiculatus, may cause a significant loss to common bean (Phaseolus vulgaris L. yield. RAPD markers tightly linked to the resistance genes may be used in breeding programs to aid the development of rust-resistant bean cultivars. In this sense, the objective of the present work was to identify RAPD markers linked to a rust resistance gene block present in the cultivar Ouro Negro. Two hundred and fourteen F2 individuals from a cross between the resistant cultivar Ouro Negro and the susceptible cultivar US Pinto 111 were inoculated with a mixture of eight races of U. appendiculatus. The segregation ratio obtained suggested that resistance is monogenic and dominant. Bulked segregant analysis was used in conjunction with the RAPD technique to search for markers linked to rust resistance genes. Two molecular markers flanking the rust resistance gene block were identified, one at 5.8 ± 1.6 cM (OX11(630 and the other at 7.7 ± 1.7 cM (OF10(1,050 of the gene. Simulated indirect selection efficiency in the F2 population using the two markers was 100%. The molecular markers identified in this work are currently being used for the selection of disease-resistant plants in the commom bean breeding program of the Federal University of Viçosa.

  3. The lactococcal secondary multidrug transporter LmrP confers resistance to lincosamides, macrolides, streptogramins and tetracyclines

    NARCIS (Netherlands)

    Putman, M; van Veen, HW; Degener, JE; Konings, WN

    2001-01-01

    The active efflux of toxic compounds by (multi)drug transporters is one of the mechanisms that bacteria have developed to resist cytotoxic drugs. The authors describe the role of the lactococcal secondary multidrug transporter LmrP in the resistance to a broad range of clinically important antibioti

  4. JNK1 in hematopoietically derived cells contributes to diet-induced inflammation and insulin resistance without affecting obesity.

    Science.gov (United States)

    Solinas, Giovanni; Vilcu, Cristian; Neels, Jaap G; Bandyopadhyay, Gautam K; Luo, Jun-Li; Naugler, Willscott; Grivennikov, Sergei; Wynshaw-Boris, Anthony; Scadeng, Miriam; Olefsky, Jerrold M; Karin, Michael

    2007-11-01

    Obesity-induced insulin resistance is a major factor in the etiology of type 2 diabetes, and Jun kinases (JNKs) are key negative regulators of insulin sensitivity in the obese state. Activation of JNKs (mainly JNK1) in insulin target cells results in phosphorylation of insulin receptor substrates (IRSs) at serine and threonine residues that inhibit insulin signaling. JNK1 activation is also required for accumulation of visceral fat. Here we used reciprocal adoptive transfer experiments to determine whether JNK1 in myeloid cells, such as macrophages, also contributes to insulin resistance and central adiposity. Our results show that deletion of Jnk1 in the nonhematopoietic compartment protects mice from high-fat diet (HFD)-induced insulin resistance, in part through decreased adiposity. By contrast, Jnk1 removal from hematopoietic cells has no effect on adiposity but confers protection against HFD-induced insulin resistance by decreasing obesity-induced inflammation. PMID:17983584

  5. Local hyperthermia treatment of tumors induces CD8+ T cell-mediated resistance against distal and secondary tumors

    Science.gov (United States)

    Zhang, Peisheng; Chen, Lei; Baird, Jason R.; Demidenko, Eugene; Turk, Mary Jo; Hoopes, P. Jack; Conejo-Garcia, Jose R.; Fiering, Steven

    2014-01-01

    Combinatorial use of iron oxide nanoparticles (IONPs) and an alternating magnetic filed (AMF) can induce local hyperthermia in tumors in a controlled and uniform manner. Heating B16 primary tumors at 43°C for 30 minutes activated dendritic cells (DCs) and subsequently CD8+ T cells in the draining lymph node (dLN) and conferred resistance against rechallenge with B16 (but not unrelated Lewis Lung carcinoma) given 7 days post hyperthermia on both the primary tumor side and the contralateral side in a CD8+ T cell-dependent manner. Mice with heated primary tumors also resisted rechallenge given 30 days post hyperthermia. Mice with larger heated primary tumors had greater resistance to secondary tumors. No rechallenge resistance occurred when tumors were heated at 45°C. Our results demonstrate the promising potential of local hyperthermia treatment applied to identified tumors in inducing anti-tumor immune responses that reduce the risk of recurrence and metastasis. PMID:24566274

  6. Hepatitis C virus cell-cell transmission and resistance to direct-acting antiviral agents.

    Directory of Open Access Journals (Sweden)

    Fei Xiao

    2014-05-01

    Full Text Available Hepatitis C virus (HCV is transmitted between hepatocytes via classical cell entry but also uses direct cell-cell transfer to infect neighboring hepatocytes. Viral cell-cell transmission has been shown to play an important role in viral persistence allowing evasion from neutralizing antibodies. In contrast, the role of HCV cell-cell transmission for antiviral resistance is unknown. Aiming to address this question we investigated the phenotype of HCV strains exhibiting resistance to direct-acting antivirals (DAAs in state-of-the-art model systems for cell-cell transmission and spread. Using HCV genotype 2 as a model virus, we show that cell-cell transmission is the main route of viral spread of DAA-resistant HCV. Cell-cell transmission of DAA-resistant viruses results in viral persistence and thus hampers viral eradication. We also show that blocking cell-cell transmission using host-targeting entry inhibitors (HTEIs was highly effective in inhibiting viral dissemination of resistant genotype 2 viruses. Combining HTEIs with DAAs prevented antiviral resistance and led to rapid elimination of the virus in cell culture model. In conclusion, our work provides evidence that cell-cell transmission plays an important role in dissemination and maintenance of resistant variants in cell culture models. Blocking virus cell-cell transmission prevents emergence of drug resistance in persistent viral infection including resistance to HCV DAAs.

  7. Modified cellulose synthase gene from Arabidopsis thaliana confers herbicide resistance to plants

    Science.gov (United States)

    Somerville, Chris R.; Scheible, Wolf

    2007-07-10

    Cellulose synthase ("CS"), a key enzyme in the biosynthesis of cellulose in plants is inhibited by herbicides comprising thiazolidinones such as 5-tert-butyl-carbamoyloxy-3-(3-trifluromethyl)phenyl-4-thiazolidinone (TZ), isoxaben and 2,6-dichlorobenzonitrile (DCB). Two mutant genes encoding isoxaben and TZ-resistant cellulose synthase have been isolated from isoxaben and TZ-resistant Arabidopsis thaliana mutants. When compared with the gene coding for isoxaben or TZ-sensitive cellulose synthase, one of the resistant CS genes contains a point mutation, wherein glycine residue 998 is replaced by an aspartic acid. The other resistant mutation is due to a threonine to isoleucine change at amino acid residue 942. The mutant CS gene can be used to impart herbicide resistance to a plant; thereby permitting the utilization of the herbicide as a single application at a concentration which ensures the complete or substantially complete killing of weeds, while leaving the transgenic crop plant essentially undamaged.

  8. Insensitive Acetylcholine Receptor Conferring Resistance of Plutella xylostella to Nereistoxin Insecticides

    Institute of Scientific and Technical Information of China (English)

    CHENG Luo-gen; YU Guang; CHEN Zi-hao; LI Zhong-yin

    2008-01-01

    The combinative rate measurement of (3-[Ⅰ125] iodotyrosyl) α-bungarotoxin was applied in the analysis of the relation between nerve acetylcholine receptor and three types of insecticide resistance in diamondback moth, Plutella xylostella (L.). In the dimehypo-resistant strain and in the cartap-resistant strain, the nerve acetylcholine receptor showed the remarkable insensitivity to dimehypo and cartap, of which the binding rate to ligand was approximately 66 and 60%, respectively, of the susceptible strain. The sensitivity to deltamethrin in the deltamethrin-resistant strain did not show visible change. These results indicated that the decline in the sensitivity of nerve acetylcholine receptor to insecticide might be a potential mechanism to nereistoxin insecticides resistance in the diamondback moth.

  9. Reduction of MLH1 and PMS2 confers temozolomide resistance and is associated with recurrence of glioblastoma

    OpenAIRE

    Shinsato, Yoshinari; Furukawa, Tatsuhiko; Yunoue, Shunji; Yonezawa, Hajime; Minami, Kentarou; Nishizawa, Yukihiko; IKEDA, Ryuji; Kawahara, Kohichi; YAMAMOTO, Masatatsu; Hirano, Hirofumi; Tokimura, Hiroshi; Arita, Kazunori

    2013-01-01

    Although there is a relationship between DNA repair deficiency and temozolomide (TMZ) resistance in glioblastoma (GBM), it remains unclear which molecule is associated with GBM recurrence. We isolated three TMZ-resistant human GBM cell lines and examined the expression of O6-methylguanine-DNA methyltransferase (MGMT) and mismatch repair (MMR) components. We used immunohistochemical analysis to compare MutL homolog 1 (MLH1), postmeiotic segregation increased 2 (PMS2) and MGMT expression in pri...

  10. Limitations of fitting angular scattering from single cells (Conference Presentation)

    Science.gov (United States)

    Fan, Xing; Cannaday, Ashley E.; Berger, Andrew J.

    2016-04-01

    The literature contains several reports of Mie-like fits to angular-domain elastic scattering measurements from multiple cells or isolated mitochondria. In these studies, the sampling volume typically contains hundreds or thousands of mitochondria, allowing for the size distribution of mitochondria to be modeled as a smooth function, (e.g. Gaussian or log-normal) with a small number of free parameters. In the case of a single-cell volume containing significantly fewer mitochondria, the true size distribution will no longer be as smooth. Increasing the number of free parameters can lead to unstable fits, however, as the forward-directed angular scattering pattern from such a population illuminated with 785 nm light is a monotonically decaying radial function with few distinct features. Using simulations, we have investigated the limitations of modeling single-cell mitochondrial scattering using smooth population distributions of Mie scatterers. In different instances, the fidelity of the estimated size information can be limited by the number of organelles, the angular detection range, or the non-ideality of the data (both speckle and shot noise). We will describe the conditions under which each of these effects dominates. We will also discuss whether mean and standard deviation are the best sizes to report from such Mie modeling, or if there are other size parameters that have greater fidelity to the true, non-smooth size distributions.

  11. Cancer Stem Cells: Targeting the Roots of Cancer, Seeds of Metastasis, and Sources of Therapy Resistance

    Science.gov (United States)

    Adorno-Cruz, Valery; Kibria, Golam; Liu, Xia; Doherty, Mary; Junk, Damian J.; Guan, Dongyin; Hubert, Chris; Venere, Monica; Mulkearns-Hubert, Erin; Sinyuk, Maksim; Alvarado, Alvaro; Caplan, Arnold I.; Rich, Jeremy; Gerson, Stanton L.; Lathia, Justin; Liu, Huiping

    2015-01-01

    With the goal to remove the roots of cancer, eliminate metastatic seeds, and overcome therapy resistance, the 2014 inaugural International Cancer Stem Cell (CSC) Conference at Cleveland, OH, convened together over 320 investigators, including 55 invited world-class speakers, 25 short oral presenters, and 100 poster presenters, to gain an in-depth understanding of CSCs and explore therapeutic opportunities targeting CSCs. The meeting enabled intriguing discussions on several topics including: genetics and epigenetics; cancer origin and evolution; microenvironment and exosomes; metabolism and inflammation; metastasis and therapy resistance; single cell and heterogeneity; plasticity and reprogramming; as well as other new concepts. Reports of clinical trials targeting CSCs emphasized the urgent need for strategically designing combinational CSC-targeting therapies against cancer. PMID:25604264

  12. ESTABLISHMENT OF K562/ADM/VER CELL SUBLINE RESISTANT TO VERAPAMIL AND ITS RESISTANT MECHANISM

    Institute of Scientific and Technical Information of China (English)

    谢佐福; 周冬梅; 林贤东; 林声; 吴允昆

    2001-01-01

    Objective: To understand whether verapamil (VER) resistance development in the multidrug-resistant cell line and its mechanism. Methods: K562/ADM/VER cell subline resistant to verapamil was established through a gradual increase of VER concentration in the media. MTT method was used to assay resistance to VER, cross resistance to dipyriamole (DPM), cyclosporin A (CsA) in the cells, and HPLC and spectrofluorometer to detect intracellular accumulation of VER or ADM respectively, as well as S-P immunocytochemical technique for detection of genes expression. Results: It were observed that 7.9-fold increase in VER resistance, significantly reduced intracellular accumulation of VER or ADM and also develop across resistance to DPM and CsA in K562/ADM/VER cells, compared with its parent cell, K562/ADM. High-level of p-glycoprotein(pgp), middle-level of p53, p16, was present in two cell lines without expression of GSTPI, C-myc, C-myc, C-fos and C-erbB-2. Bc1-2 protein expression was found only in K562/ADM cells. Conclusion: K562/ADM cells were capable of being induced to develop resistance to VER.

  13. Hepatic Stellate Cell Coculture Enables Sorafenib Resistance in Huh7 Cells through HGF/c-Met/Akt and Jak2/Stat3 Pathways

    Directory of Open Access Journals (Sweden)

    Weibo Chen

    2014-01-01

    Full Text Available Purpose. Tumor microenvironment confers drug resistance to kinase inhibitors by increasing RKT ligand levels that result in the activation of cell-survival signaling including PI3K and MAPK signals. We assessed whether HSC-LX2 coculture conferred sorafenib resistance in Huh7 and revealed the mechanism underlying the drug resistance. Experimental Design. The effect of LX2 on sorafenib resistance was determined by coculture system with Huh7 cells. The rescue function of LX2 supernatants was assessed by MTT assay and fluorescence microscopy. The underlying mechanism was tested by administration of pathway inhibitors and manifested by Western blotting. Results. LX2 coculture significantly induced sorafenib resistance in Huh7 by activating p-Akt that led to reactivation of p-ERK. LX2 secreted HGF into the culture medium that triggered drug resistance, and exogenous HGF could also induce sorafenib resistance. The inhibition of p-Akt blocked sorafenib resistance caused by LX2 coculture. Increased phosphorylation of Jak2 and Stat3 was also detected in LX2 cocultured Huh7 cells. The Jak inhibitor tofacitinib reversed sorafenib resistance by blocking Jak2 and Stat3 activation. The combined administration of sorafenib and p-Stat3 inhibitor S3I-201 augmented induced apoptosis even in the presence of sorafenib resistance. Conclusions. HSC-LX2 coculture induced sorafenib resistance in Huh7 through multiple pathways: HGF/c-Met/Akt pathway and Jak2/Stat3 pathway. A combined administration of sorafenib and S3I-201 was able to augment sorafenib-induced apoptosis even in the presence of LX2 coculture.

  14. Pathogen-induced expression of a cecropin A-melittin antimicrobial peptide gene confers antifungal resistance in transgenic tobacco.

    Science.gov (United States)

    Yevtushenko, Dmytro P; Romero, Rafael; Forward, Benjamin S; Hancock, Robert E; Kay, William W; Misra, Santosh

    2005-06-01

    Expression of defensive genes from a promoter that is specifically activated in response to pathogen invasion is highly desirable for engineering disease-resistant plants. A plant transformation vector was constructed with transcriptional fusion between the pathogen-responsive win3.12T promoter from poplar and the gene encoding the novel cecropin A-melittin hybrid peptide (CEMA) with strong antimicrobial activity. This promoter-transgene combination was evaluated in transgenic tobacco (Nicotiana tabacum L. cv. Xanthi) for enhanced plant resistance against a highly virulent pathogenic fungus Fusarium solani. Transgene expression in leaves was strongly increased after fungal infection or mechanical wounding, and the accumulation of CEMA transcripts was found to be systemic and positively correlated with the number of transgene insertions. A simple and efficient in vitro regeneration bioassay for preliminary screening of transgenic lines against pathogenic fungi was developed. CEMA had strong antifungal activity in vitro, inhibiting conidia germination at concentrations that were non-toxic to tobacco protoplasts. Most importantly, the expression level of the CEMA peptide in vivo, regulated by the win3.12T promoter, was sufficient to confer resistance against F. solani in transgenic tobacco. The antifungal resistance of plants with high CEMA expression was strong and reproducible. In addition, leaf tissue extracts from transgenic plants significantly reduced the number of fungal colonies arising from germinated conidia. Accumulation of CEMA peptide in transgenic tobacco had no deleterious effect on plant growth and development. This is the first report showing the application of a heterologous pathogen-inducible promoter to direct the expression of an antimicrobial peptide in plants, and the feasibility of this approach to provide disease resistance in tobacco and, possibly, other crops. PMID:15863447

  15. Carboplatin treatment of antiestrogen-resistant breast cancer cells

    DEFF Research Database (Denmark)

    Larsen, Mathilde S; Yde, Christina Westmose; Christensen, Ib J;

    2012-01-01

    Antiestrogen resistance is a major clinical problem in current breast cancer treatment. Therefore, biomarkers and new treatment options for antiestrogen-resistant breast cancer are needed. In this study, we investigated whether antiestrogen‑resistant breast cancer cell lines have increased...... sensitivity to carboplatin, as it was previously shown with cisplatin, and whether low Bcl-2 expression levels have a potential value as marker for increased carboplatin sensitivity. Breast cancer cells resistant to the pure antiestrogen fulvestrant, and two out of four cell lines resistant...... to the antiestrogen tamoxifen, were more sensitive to carboplatin treatment compared to the parental MCF-7 cell line. This indicates that carboplatin may be an advantageous treatment in antiestrogen‑resistant breast cancer; however, a marker for increased sensitivity would be needed. Low Bcl-2 expression...

  16. Impairment of O-antigen production confers resistance to grazing in a model amoeba-cyanobacterium predator-prey system.

    Science.gov (United States)

    Simkovsky, Ryan; Daniels, Emy F; Tang, Karen; Huynh, Stacey C; Golden, Susan S; Brahamsha, Bianca

    2012-10-01

    The grazing activity of predators on photosynthetic organisms is a major mechanism of mortality and population restructuring in natural environments. Grazing is also one of the primary difficulties in growing cyanobacteria and other microalgae in large, open ponds for the production of biofuels, as contaminants destroy valuable biomass and prevent stable, continuous production of biofuel crops. To address this problem, we have isolated a heterolobosean amoeba, HGG1, that grazes upon unicellular and filamentous freshwater cyanobacterial species. We have established a model predator-prey system using this amoeba and Synechococcus elongatus PCC 7942. Application of amoebae to a library of mutants of S. elongatus led to the identification of a grazer-resistant knockout mutant of the wzm ABC O-antigen transporter gene, SynPCC7942_1126. Mutations in three other genes involved in O-antigen synthesis and transport also prevented the expression of O-antigen and conferred resistance to HGG1. Complementation of these rough mutants returned O-antigen expression and susceptibility to amoebae. Rough mutants are easily identifiable by appearance, are capable of autoflocculation, and do not display growth defects under standard laboratory growth conditions, all of which are desired traits for a biofuel production strain. Thus, preventing the production of O-antigen is a pathway for producing resistance to grazing by certain amoebae.

  17. Agrobacterium tumefaciens-mediated transformation of rice with the spider insecticidal gene conferring resistance to leaffolder and striped stem borer

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Immature embryos of rice varieties “Xiushui11” and “Chunjiang 11” precultured for 4d were infected and transformed by Agrobacterium tumefaciens strain EHA101/pExT7(containing the spider insecticidal gene).The resistant calli were transferred onto the differentiation medium and plants were regenerated.The transformation frequency reached 56%~72% measured as numbers of Geneticin(G418)-resistant calli produced and 36%~60% measured as numbers of transgenic plants regenerated,respectively.PCR and Southern blot analysis of transgenic plants confirmed that the T-DNA had been integrated into the rice genome.Insect bioassays using T1 transgenic plants indicated that the mortality of the leaffolder(Cnaphalocrasis medinalis)after 7d of leaf feeding reached 38%~61% and the corrected mortality of the striped stem borer(Chilo suppressalis)after 7d of leaf feeding reached 16%~75%.The insect bioassay results demonstrated that the transgenic plants expressing the spider insecticidal protein conferred enhanced resistance to these pests.

  18. Diminished representation of HIV-1 variants containing select drug resistance-conferring mutations in primary HIV-1 infection.

    Science.gov (United States)

    Turner, Dan; Brenner, Bluma; Routy, Jean-Pierre; Moisi, Daniela; Rosberger, Zeev; Roger, Michel; Wainberg, Mark A

    2004-12-15

    This study compared the incidence of HIV-1 variants harboring mutations conferring resistance to thymidine analogues, ie, thymidine analogue mutations (TAMs), nonnucleoside reverse transcriptase (RT) inhibitors (NNMs), lamivudine (3TC) (ie, M184V), and protease inhibitors (PIs) acquired in primary HIV infection (PHI) (n = 59) to their observed prevalence in a corresponding potential transmitter (PT) population of persons harboring resistant infections (n = 380). Both of these populations in the context of this cohort analysis possessed similar demographics. Whereas the frequencies of observed TAMs, NNMs, M184V, and protease-associated mutations (PRAMs) were similar in the PT groups, the prevalence of M184V and major PI mutations were significantly lower in the PHI group (PHI/PT ratios of 0.14 and 0.39, respectively). There was a decreased prevalence in the PHI population of resistant viruses co-expressing NNMs or TAMs with M184V compared with viruses that harbored NNMs or TAMs in the absence of M184V (P < 0.0001). It was also observed that individuals in the PT subgroups who harbored RT mutations or PRAMs with M184V had lower levels of plasma viremia than individuals who lacked M184V (P < 0.05). These findings suggest that both decreased viremia and viral fitness in the case of M184V-containing HIV-1 variants may impact on viral transmissibility.

  19. Overexpression of VOZ2 confers biotic stress tolerance but decreases abiotic stress resistance in Arabidopsis

    OpenAIRE

    Nakai, Yusuke; Fujiwara, Sumire; Kubo, Yasuyuki; Sato, Masa H.

    2013-01-01

    VOZ (vascular plant one zinc-finger protein) is a plant specific one-zinc finger type transcriptional activator, which is highly conserved through land plant evolution. We have previously shown that loss-of-function mutations in VOZ1 and VOZ2 showed increased cold and drought stress tolerances whereas decreased biotic stress resistance in Arabidopsis. Here, we demonstrate that transgenic plants overexpressing VOZ2 impairs freezing and drought stress tolerances but increases resistance to a fu...

  20. mTOR target NDRG1 confers MGMT-dependent resistance to alkylating chemotherapy

    OpenAIRE

    Weiler, M.; Blaes, J; Pusch, S.; Sahm, F; Czabanka, M; Luger, S; Bunse, L; Solecki, G; Eichwald, V; Jugold, M; Hodecker, S; Osswald, M; Meisner, C; Hielscher, T; Rübmann, P

    2014-01-01

    A hypoxic microenvironment induces resistance to alkylating agents by activating targets in the mammalian target of rapamycin (mTOR) pathway. The molecular mechanisms involved in this mTOR-mediated hypoxia-induced chemoresistance, however, are unclear. Here we identify the mTOR target N-myc downstream regulated gene 1 (NDRG1) as a key determinant of resistance toward alkylating chemotherapy, driven by hypoxia but also by therapeutic measures such as irradiation, corticosteroids, and chronic e...

  1. Hairpin RNA Targeting Multiple Viral Genes Confers Strong Resistance to Rice Black-Streaked Dwarf Virus

    Directory of Open Access Journals (Sweden)

    Fangquan Wang

    2016-05-01

    Full Text Available Rice black-streaked dwarf virus (RBSDV belongs to the genus Fijivirus in the family of Reoviridae and causes severe yield loss in rice-producing areas in Asia. RNA silencing, as a natural defence mechanism against plant viruses, has been successfully exploited for engineering virus resistance in plants, including rice. In this study, we generated transgenic rice lines harbouring a hairpin RNA (hpRNA construct targeting four RBSDV genes, S1, S2, S6 and S10, encoding the RNA-dependent RNA polymerase, the putative core protein, the RNA silencing suppressor and the outer capsid protein, respectively. Both field nursery and artificial inoculation assays of three generations of the transgenic lines showed that they had strong resistance to RBSDV infection. The RBSDV resistance in the segregating transgenic populations correlated perfectly with the presence of the hpRNA transgene. Furthermore, the hpRNA transgene was expressed in the highly resistant transgenic lines, giving rise to abundant levels of 21–24 nt small interfering RNA (siRNA. By small RNA deep sequencing, the RBSDV-resistant transgenic lines detected siRNAs from all four viral gene sequences in the hpRNA transgene, indicating that the whole chimeric fusion sequence can be efficiently processed by Dicer into siRNAs. Taken together, our results suggest that long hpRNA targeting multiple viral genes can be used to generate stable and durable virus resistance in rice, as well as other plant species.

  2. The potyviral suppressor of RNA silencing confers enhanced resistance to multiple pathogens

    International Nuclear Information System (INIS)

    Helper component-protease (HC-Pro) is a plant viral suppressor of RNA silencing, and transgenic tobacco expressing HC-Pro has increased susceptibility to a broad range of viral pathogens. Here we report that these plants also exhibit enhanced resistance to unrelated heterologous pathogens. Tobacco mosaic virus (TMV) infection of HC-Pro-expressing plants carrying the N resistance gene results in fewer and smaller lesions compared to controls without HC-Pro. The resistance to TMV is compromised but not eliminated by expression of nahG, which prevents accumulation of salicylic acid (SA), an important defense signaling molecule. HC-Pro-expressing plants are also more resistant to tomato black ring nepovirus (TBRV) and to the oomycete Peronospora tabacina. Enhanced TBRV resistance is SA-independent, whereas the response to P. tabacina is associated with early induction of markers characteristic of SA-dependent defense. Thus, a plant viral suppressor of RNA silencing enhances resistance to multiple pathogens via both SA-dependent and SA-independent mechanisms

  3. Extraction and identification of exosomes from drug-resistant breast cancer cells and their potential role in cell-to-cell drug-resistance transfer

    Institute of Scientific and Technical Information of China (English)

    许金金

    2014-01-01

    Objective To explore whether docetaxel-resistant cells(MCF-7/Doc)and doxorubicin-resistant cells(MCF-7/ADM)can secrete Exosomes and their potential role in cell-cell drug-resistance transfer.Methods Exosomes were extracted from the cell culture supernatants of MCF-7/Doc and MCF-7/ADM cells by fractionation ultracentrifugation,and were identified by transmission

  4. Role of multidrug resistance protein 2 (MRP2) in chemoresistance and clinical outcome in oesophageal squamous cell carcinoma

    OpenAIRE

    Yamasaki, M; Makino, T; Masuzawa, T; Kurokawa, Y.; Miyata, H.; Takiguchi, S; K. Nakajima; Fujiwara, Y.; Matsuura, N; M. Mori; Doki, Y

    2011-01-01

    Background: Although multidrug resistance protein 2 (MRP2) confers chemoresistance in some cancer types, its implication on oesophageal squamous cell carcinoma (ESCC) remains unclear. Methods: We evaluated MRP2 expression by immunohistochemistry and RT–PCR using 81 resected specimens from ESCC patients who did or did not receive neo-adjuvant chemotherapy (NACT), including 5-fluorouracil, doxorubicin, and cisplatin (CDDP). Correlation between MRP2 expression and response to chemotherapy was al...

  5. Cell wall remodelling enzymes modulate fungal cell wall elasticity and osmotic stress resistance

    OpenAIRE

    Ene, Iuliana; Walker, Louise; Schiavone, Marion; Lee, Keunsook K.; Dague, Etienne; Gow, Neil A.R.; Munro, Carol A

    2015-01-01

    The fungal cell wall confers cell morphology and protection against environmental insults. For fungal pathogens, the cell wall is a key immunological modulator and an ideal therapeutic target. Yeast cell walls possess an inner matrix of interlinked β-glucan and chitin that is thought to provide tensile strength and rigidity. Yeast cells remodel their walls over time in response to environmental change, a process controlled by evolutionarily conserved stress (Hog1) and cell integrity (Mkc1, Ce...

  6. Placenta Mesenchymal Stem Cell Derived Exosomes Confer Plasticity on Fibroblasts.

    Science.gov (United States)

    Tooi, Masayuki; Komaki, Motohiro; Morioka, Chikako; Honda, Izumi; Iwasaki, Kengo; Yokoyama, Naoki; Ayame, Hirohito; Izumi, Yuichi; Morita, Ikuo

    2016-07-01

    Mesenchymal stem cell (MSC)-conditioned medium (MSC-CM) has been reported to enhance wound healing. Exosomes contain nucleic acids, proteins, and lipids, and function as an intercellular communication vehicle for mediating some paracrine effects. However, the function of MSC-derived exosomes (MSC-exo) remains elusive. In this study, we isolated human placenta MSC (PlaMSC)-derived exosomes (PlaMSC-exo) and examined their function in vitro. PlaMSCs were isolated from human term placenta using enzymatic digestion. PlaMSC-exo were prepared from the conditioned medium of PlaMSC (PlaMSC-CM) by ultracentrifugation. The expression of stemness-related genes, such as OCT4 and NANOG, in normal adult human dermal fibroblasts (NHDF) after incubation with PlaMSC-exo was measured by real-time reverse transcriptase PCR analysis (real-time PCR). The effect of PlaMSC-exo on OCT4 transcription activity was assessed using Oct4-EGFP reporter mice-derived dermal fibroblasts. The stimulating effects of PlaMSC-exo on osteoblastic and adipocyte-differentiation of NHDF were evaluated by alkaline phosphatase (ALP), and Alizarin red S- and oil red O-staining, respectively. The expression of osteoblast- and adipocyte-related genes was also assessed by real-time PCR. The treatment of NHDF with PlaMSC-exo significantly upregulated OCT4 and NANOG mRNA expression. PlaMSC-exo also enhanced OCT4 transcription. The NHDF treated with PlaMSC-exo exhibited osteoblastic and adipocyte-differentiation in osteogenic and adipogenic induction media. PlaMSC-exo increase the expression of OCT4 and NANOG mRNA in fibroblasts. As a result, PlaMSC-exo influence the differentiation competence of fibroblasts to both osteoblastic and adipocyte-differentiation. It shows a new feature of MSCs and the possibility of clinical application of MSC-exo. J. Cell. Biochem. 117: 1658-1670, 2016. © 2015 Wiley Periodicals, Inc. PMID:26640165

  7. Endocytic Ark/Prk kinases play a critical role in adriamycin resistance in both yeast and mammalian cells.

    Science.gov (United States)

    Takahashi, Tsutomu; Furuchi, Takemitsu; Naganuma, Akira

    2006-12-15

    To elucidate the mechanism of acquired resistance to Adriamycin, we searched for genes that, when overexpressed, render Saccharomyces cerevisiae resistant to Adriamycin. We identified AKL1, a gene of which the function is unknown but is considered, nonetheless, to be a member of the Ark/Prk kinase family, which is involved in the regulation of endocytosis, on the basis of its deduced amino acid sequence. Among tested members of the Ark/Prk kinase family (Ark1, Prk1, and Akl1), overexpressed Prk1 also conferred Adriamycin resistance on yeast cells. Prk1 is known to dissociate the Sla1/Pan1/End3 complex, which is involved in endocytosis, by phosphorylating Sla1 and Pan1 in the complex. We showed that Akl1 promotes phosphorylation of Pan1 in this complex and reduces the endocytic ability of the cell, as does Prk1. Sla1- and End3-defective yeast cells were also resistant to Adriamycin and overexpression of Akl1 in these defective cells did not increase the degree of Adriamycin resistance, suggesting that Akl1 might reduce Adriamycin toxicity by reducing the endocytic ability of cells via a mechanism that involves the Sla1/Pan1/End3 complex and the phosphorylation of Pan1. We also found that HEK293 cells that overexpressed AAK1, a member of the human Ark/Prk family, were Adriamycin resistant. Our findings suggest that endocytosis might be involved in the mechanism of Adriamycin toxicity in yeast and human cells.

  8. Modified cellulose synthase gene from 'Arabidopsis thaliana' confers herbicide resistance to plants

    Energy Technology Data Exchange (ETDEWEB)

    Somerville, Chris R.; Scieble, Wolf

    2000-10-11

    Cellulose synthase ('CS'), a key enzyme in the biosynthesis of cellulose in plants is inhibited by herbicides comprising thiazolidinones such as 5-tert-butyl-carbamoyloxy-3-(3-trifluromethyl) phenyl-4-thiazolidinone (TZ), isoxaben and 2,6-dichlorobenzonitrile (DCB). Two mutant genes encoding isoxaben and TZ-resistant cellulose synthase have been isolated from isoxaben and TZ-resistant Arabidopsis thaliana mutants. When compared with the gene coding for isoxaben or TZ-sensitive cellulose synthase, one of the resistant CS genes contains a point mutation, wherein glycine residue 998 is replaced by an aspartic acid. The other resistant mutation is due to a threonine to isoleucine change at amino acid residue 942. The mutant CS gene can be used to impart herbicide resistance to a plant; thereby permitting the utilization of the herbicide as a single application at a concentration which ensures the complete or substantially complete killing of weeds, while leaving the transgenic crop plant essentially undamaged.

  9. Transgenic Rice Plants Harboring Genomic DNA from Zizania latifolia Confer Bacterial Blight Resistance

    Institute of Scientific and Technical Information of China (English)

    SHEN Wei-wei; SONG Cheng-li; CHEN Jie; Fu Ya-ping; Wu Jian-li; JIANG Shao-mei

    2011-01-01

    Based on the sequence of a resistance gene analog FZ14 derived from Zizania latifolia (Griseb.),a pair of specific PCR primers FZ14P1/FZ14P2 was designed to isolate candidate disease resistance gene.The pooled-PCR approach was adopted using the primer pair to screen a genomic transformation-competent artificial chromosome (TAC) library derived from Z.latifolia.A positive TAC clone (ZR1) was obtained and confirmed by sequence analysis.The results indicated that ZR1 consisted of conserved motifs similar to P-loop (kinase 1a),kinase 2,kinase 3a and GLPL (Gly-Leu-Pro-Leu),suggesting that it could be a portion of NBS-LRR type of resistance gene.Using Agrobacterium-mediated transformation of Nipponbare mature embryo,a total of 48 independent transgenic T0 plants were obtained.Among them,36 plants were highly resistant to the virulent bacterial blight strain P×O71.The results indicate that ZR1 contains at least one functional bacterial blight resistance gene.

  10. Lumped series resistance of solar cells as a result of distributed sheet resistance

    Science.gov (United States)

    Sokolić, Saša; Križaj, Dejan; Amon, Slavko

    1993-04-01

    An analysis of solar cell distributed sheet resistance is performed by solving the nonlinear Poisson equation for the surface potential. Two different approaches to lumped series resistance are discussed: equivalent series resistance RSeq obtained from the cell's equivalent circuit that satisfies the actual current of the cell (all other parameters in the equivalent circuit except the series resistance are kept constant) and Joule series resistance RSJ obtained from the Joule losses in the emitter of the cell. It is observed that the I( U) characteristic obtained from the equivalent circuit that includes RSJ generally disagrees with the actual I( U) characteristic of the solar cell. An additional series resistance RSadd should be introduced in series with RSJ. Series resistances RSJ, Sadd and RSeq are analyzed numerically in one and two dimensions for different conditions of terminal voltage, illumination and weighted sheet resistance Rshb2, where b is related to the geometry of the analyzed cell. Following the derivations and the results of the numerical analysis it can be concluded that wherever RSJ varies as a function of terminal voltage, RSadd should be taken into consideration.

  11. Beta4 integrin-dependent formation of polarized three-dimensionalarchitecture confers resistance to apoptosis in normal and malignantmammary epithelium

    Energy Technology Data Exchange (ETDEWEB)

    Weaver, Valerie M.; Lelievre, Sophie; Lakins, Johnathon N.; Chrenek, Micah A.; Jones, Jonathan C.R.; Giancotti, Filippo; Werb, Zena; Bissell, Mina J.

    2002-08-27

    Tumor cells can evade chemotherapy by acquiring resistanceto apoptosis. We investigated the molecular mechanism whereby malignantand nonmalignant mammary epithelial cells become insensitive toapoptosis. We show that regardless of growth status formation ofpolarized, three-dimensional structures driven by basement membraneconfers protection to apoptosis in both nonmalignant and malignantmammary epithelial cells. By contrast, irrespective of their malignantstatus, nonpolarized structures are sensitive to induction of apoptosis.Resistance to apoptosis requires ligation of beta4 integrins, whichregulates tissue polarity, hemidesmosome formation and NFkB activation.Expression of beta4 integrin that lacks the hemidesmosome targetingdomain interferes with tissue polarity and NFkB activation and permitsapoptosis. These results indicate that integrin-induced polarity maydrive tumor cell resistance to apoptosis-inducing agents via effects onNFkB.

  12. 30S Subunit-Dependent Activation of the Sorangium cellulosum So ce56 Aminoglycoside Resistance-Conferring 16S rRNA Methyltransferase Kmr

    Science.gov (United States)

    Savic, Miloje; Sunita, S.; Zelinskaya, Natalia; Desai, Pooja M.; Macmaster, Rachel; Vinal, Kellie

    2015-01-01

    Methylation of bacterial 16S rRNA within the ribosomal decoding center confers exceptionally high resistance to aminoglycoside antibiotics. This resistance mechanism is exploited by aminoglycoside producers for self-protection while functionally equivalent methyltransferases have been acquired by human and animal pathogenic bacteria. Here, we report structural and functional analyses of the Sorangium cellulosum So ce56 aminoglycoside resistance-conferring methyltransferase Kmr. Our results demonstrate that Kmr is a 16S rRNA methyltransferase acting at residue A1408 to confer a canonical aminoglycoside resistance spectrum in Escherichia coli. Kmr possesses a class I methyltransferase core fold but with dramatic differences in the regions which augment this structure to confer substrate specificity in functionally related enzymes. Most strikingly, the region linking core β-strands 6 and 7, which forms part of the S-adenosyl-l-methionine (SAM) binding pocket and contributes to base flipping by the m1A1408 methyltransferase NpmA, is disordered in Kmr, correlating with an exceptionally weak affinity for SAM. Kmr is unexpectedly insensitive to substitutions of residues critical for activity of other 16S rRNA (A1408) methyltransferases and also to the effects of by-product inhibition by S-adenosylhomocysteine (SAH). Collectively, our results indicate that adoption of a catalytically competent Kmr conformation and binding of the obligatory cosubstrate SAM must be induced by interaction with the 30S subunit substrate. PMID:25733511

  13. Mycobacterium tuberculosis pncA Polymorphisms That Do Not Confer Pyrazinamide Resistance at a Breakpoint Concentration of 100 Micrograms per Milliliter in MGIT

    Science.gov (United States)

    Whitfield, Michael G.; Streicher, Elizabeth M.; Sampson, Samantha L.; Sirgel, Frik A.; van Helden, Paul D.; Mercante, Alexandra; Willby, Melisa; Hughes, Kelsey; Birkness, Kris; Morlock, Glenn; van Rie, Annelies; Posey, James E.

    2015-01-01

    Sequencing of the Mycobacterium tuberculosis pncA gene allows for pyrazinamide susceptibility testing. We summarize data on pncA polymorphisms that do not confer resistance at a susceptibility breakpoint of 100 μg/ml pyrazinamide in MGIT within a cohort of isolates from South Africa and the U.S. Centers for Disease Control and Prevention. PMID:26292310

  14. BNYVV-derived dsRNA confers resistance to rhizomania disease of sugar beet as evidenced by a novel transgenic hairy root approach

    NARCIS (Netherlands)

    Pavli, R.; Panopoulos, N.J.; Goldbach, R.W.; Skaracis, G.N.

    2010-01-01

    Agrobacterium rhizogenes-transformed sugar beet hairy roots, expressing dsRNA from the Beet necrotic yellow vein virus replicase gene, were used as a novel approach to assess the efficacy of three intron-hairpin constructs at conferring resistance to rhizomania disease. Genetically engineered roots

  15. Obesogenic memory can confer long-term increases in adipose tissue but not liver inflammation and insulin resistance after weight loss

    Directory of Open Access Journals (Sweden)

    J. Schmitz

    2016-05-01

    Conclusions: These results demonstrate that although sustained weight loss improves systemic glucose homeostasis, primarily through improved inflammation and insulin action in liver, a remarkable obesogenic memory can confer long-term increases in adipose tissue inflammation and insulin resistance in mice as well as in a significant subpopulation of obese patients.

  16. Distinction between the Cfr Methyltransferase Conferring Antibiotic Resistance and the Housekeeping RlmN Methyltransferase

    DEFF Research Database (Denmark)

    Atkinson, Gemma C; Hansen, Lykke H; Tenson, Tanel;

    2013-01-01

    The cfr gene encodes the Cfr methyltransferase that primarily methylates C-8 in A2503 of 23S rRNA in the peptidyl transferase region of bacterial ribosomes. The methylation provides resistance to six classes of antibiotics of clinical and veterinary importance. The rlmN gene encodes the Rlm......N methyltransferase that methylates C-2 in A2503 in 23S rRNA and A37 in tRNA, but RlmN does not significantly influence antibiotic resistance. The enzymes are homologous and use the same mechanism involving radical S-adenosyl methionine to methylate RNA via an intermediate involving a methylated cysteine....... The differentiation between the two classes is supported by previous and new experimental evidence from antibiotic resistance, primer extensions, and mass spectrometry. Finally, evolutionary aspects of the distribution of Cfr- and RlmN-like enzymes are discussed....

  17. Multilevel Cell Storage and Resistance Variability in Resistive Random Access Memory

    Science.gov (United States)

    Pantelis, D. I.; Karakizis, P. N.; Dragatogiannis, D. A.; Charitidis, C. A.

    2016-06-01

    Multilevel per cell (MLC) storage in resistive random access memory (ReRAM) is attractive in achieving high-density and low-cost memory and will be required in future. In this chapter, MLC storage and resistance variability and reliability of multilevel in ReRAM are discussed. Different MLC operation schemes with their physical mechanisms and a comprehensive analysis of resistance variability have been provided. Various factors that can induce variability and their effect on the resistance margin between the multiple resistance levels are assessed. The reliability characteristics and the impact on MLC storage have also been assessed.

  18. A novel, double mutation in DNA gyrase A of Escherichia coli conferring resistance to quinolone antibiotics.

    OpenAIRE

    Truong, Q C; Nguyen Van, J C; Shlaes, D; Gutmann, L; Moreau, N J

    1997-01-01

    A spontaneous Escherichia coli mutant, named Q3, resistant to nalidixic acid was obtained from a previously described clinical isolate of E. coli, Q2, resistant to fluoroquinolones but susceptible to nalidixic acid (E. Cambau, F. Bordon, E. Collatz, and L. Gutmann, Antimicrob. Agents Chemother. 37:1247-1252, 1993). Q3 harbored the mutation Asp82Gly in addition to the Gly81Asp mutation of Q2. The different mutations leading to Gly81Asp, Asp82Gly, and Gly81AspAsp82Gly were introduced into the g...

  19. Cytotoxicity of the Sesquiterpene Lactones Neoambrosin and Damsin from Ambrosia maritima Against Multidrug-Resistant Cancer Cells.

    Science.gov (United States)

    Saeed, Mohamed; Jacob, Stefan; Sandjo, Louis P; Sugimoto, Yoshikazu; Khalid, Hassan E; Opatz, Till; Thines, Eckhard; Efferth, Thomas

    2015-01-01

    Multidrug resistance is a prevailing phenomenon leading to chemotherapy treatment failure in cancer patients. In the current study two known cytotoxic pseudoguaianolide sesquiterpene lactones; neoambrosin (1) and damsin (2) that circumvent MDR were identified. The two cytotoxic compounds were isolated using column chromatography, characterized using 1D and 2D NMR, MS, and compared with literature values. The isolated compounds were investigated for their cytotoxic potential using resazurin assays and thereafter confirmed with immunoblotting and in silico studies. MDR cells overexpressing ABC transporters (P-glycoprotein, BCRP, ABCB5) did not confer cross-resistance toward (1) and (2), indicating that these compounds are not appropriate substrates for any of the three ABC transporters analyzed. Resistance mechanisms investigated also included; the loss of the functions of the TP53 and the mutated EGFR. The HCT116 p53(-/-) cells were sensitive to 1 but resistant to 2. It was interesting to note that resistant cells transfected with oncogenic ΔEGFR exhibited hypersensitivity CS toward (1) and (2) (degrees of resistances were 0.18 and 0.15 for (1) and (2), respectively). Immunoblotting and in silico analyses revealed that 1 and 2 silenced c-Src kinase activity. It was hypothesized that inhibition of c-Src kinase activity may explain CS in EGFR-transfected cells. In conclusion, the significant cytotoxicity of 1 and 2 against different drug-resistant tumor cell lines indicate that they may be promising candidates to treat refractory tumors. PMID:26617519

  20. 2nd International Conference on Historic Earthquake-Resistant Timber Frames in the Mediterranean Area

    CERN Document Server

    Machado, José; Costa, Alfredo; Candeias, Paulo; Ruggieri, Nicola; Catarino, José

    2016-01-01

    This book presents a selection of the best papers from the HEaRT 2015 conference, held in Lisbon, Portugal, which provided a valuable forum for engineers and architects, researchers and educators to exchange views and findings concerning the technological history, construction features and seismic behavior of historical timber-framed walls in the Mediterranean countries. The topics covered are wide ranging and include historical aspects and examples of the use of timber-framed construction systems in response to earthquakes, such as the gaiola system in Portugal and the Bourbon system in southern Italy; interpretation of the response of timber-framed walls to seismic actions based on calculations and experimental tests; assessment of the effectiveness of repair and strengthening techniques, e.g., using aramid fiber wires or sheets; and modelling analyses. In addition, on the basis of case studies, a methodology is presented that is applicable to diagnosis, strengthening and improvement of seismic performance ...

  1. Sleeping Beauty-Mediated Drug Resistance Gene Transfer in Human Hematopoietic Progenitor Cells.

    Science.gov (United States)

    Hyland, Kendra A; Olson, Erik R; McIvor, R Scott

    2015-10-01

    The Sleeping Beauty (SB) transposon system can insert sequences into mammalian chromosomes, supporting long-term expression of both reporter and therapeutic genes. Hematopoietic progenitor cells (HPCs) are an ideal therapeutic gene transfer target as they are used in therapy for a variety of hematologic and metabolic conditions. As successful SB-mediated gene transfer into human CD34(+) HPCs has been reported by several laboratories, we sought to extend these studies to the introduction of a therapeutic gene conferring resistance to methotrexate (MTX), potentially providing a chemoprotective effect after engraftment. SB-mediated transposition of hematopoietic progenitors, using a transposon encoding an L22Y variant dihydrofolate reductase fused to green fluorescent protein, conferred resistance to methotrexate and dipyridamole, a nucleoside transport inhibitor that tightens MTX selection conditions, as assessed by in vitro hematopoietic colony formation. Transposition of individual transgenes was confirmed by sequence analysis of transposon-chromosome junctions recovered by linear amplification-mediated PCR. These studies demonstrate the potential of SB-mediated transposition of HPCs for expression of drug resistance genes for selective and chemoprotective applications. PMID:26176276

  2. Collateral methotrexate resistance in cisplatin-selected murine leukemia cells

    Directory of Open Access Journals (Sweden)

    Bhushan A.

    1999-01-01

    Full Text Available Resistance to anticancer drugs is a major cause of failure of many therapeutic protocols. A variety of mechanisms have been proposed to explain this phenomenon. The exact mechanism depends upon the drug of interest as well as the tumor type treated. While studying a cell line selected for its resistance to cisplatin we noted that the cells expressed a >25,000-fold collateral resistance to methotrexate. Given the magnitude of this resistance we elected to investigate this intriguing collateral resistance. From a series of investigations we have identified an alteration in a membrane protein of the resistant cell as compared to the sensitive cells that could be the primary mechanism of resistance. Our studies reviewed here indicate decreased tyrosine phosphorylation of a protein (molecular mass = 66 in the resistant cells, which results in little or no transfer of methotrexate from the medium into the cell. Since this is a relatively novel function for tyrosine phosphorylation, this information may provide insight into possible pharmacological approaches to modify therapeutic regimens by analyzing the status of this protein in tumor samples for a better survival of the cancer patients.

  3. PKCη confers protection against apoptosis by inhibiting the pro-apoptotic JNK activity in MCF-7 cells

    International Nuclear Information System (INIS)

    Apoptosis is frequently regulated by different protein kinases including protein kinase C family enzymes. Both inhibitory and stimulatory effects were demonstrated for several of the different PKC isoforms. Here we show that the novel PKC isoform, PKCη, confers protection against apoptosis induced by the DNA damaging agents, UVC irradiation and the anti-cancer drug - Camptothecin, of the breast epithelial adenocarcinoma MCF-7 cells. The induced expression of PKCη in MCF-7 cells, under the control of the tetracycline-responsive promoter, resulted in increased cell survival and inhibition of cleavage of the apoptotic marker PARP-1. Activation of caspase-7 and 9 and the release of cytochrome c were also inhibited by the inducible expression of PKCη. Furthermore, JNK activity, required for apoptosis in MCF-7, as indicated by the inhibition of both caspase-7 cleavage and cytochrome c release from the mitochondria in the presence of the JNK inhibitor SP600125, was also suppressed by PKCη expression. Hence, in contrast to most PKC isoforms enhancing JNK activation, our studies show that PKCη is an anti-apoptotic protein, acting as a negative regulator of JNK activity. Thus, PKCη could represent a target for intervention aimed to reduce resistance to anti-cancer treatments.

  4. Multidrug resistance of tumor cells: some new trends in research

    OpenAIRE

    Stavrovskaya, A. A.; G. P. Guens

    2014-01-01

    Multidrug resistance (MDR) of tumor cells is the resistance to a broad spectrum of structurally unrelated cytotoxic drugs with different mechanisms of action. One of the main causes of MDR phenotype is the activity of ATP-binding cassette transporters (ABC transporters). ABC transporters efflux toxic compounds from the cells. All living cells contain ABC transporters. This review is dedicated to the studies of three-dimensional structure of ABC transporters, to the data concerning MDR evoluti...

  5. Potentially Deceptive Health Nutrition-Related Advertising Claims: The Role of Inoculation in Conferring Resistance

    Science.gov (United States)

    Mason, Alicia M.; Miller, Claude H.

    2016-01-01

    Objective: This study sought to examine the efficacy of inoculation message treatments to facilitate resistance to health nutrition-related (HNR) commercial food advertising claims. Design: Data were collected across three phases extending across a 5-week period conducted over two semesters at a Midwest US university. A 2 × 3 between-subjects…

  6. Novel plasmid conferring kanamycin and tetracycline resistance in turkey-derived Campylobacter jejuni strain 11601MD

    Science.gov (United States)

    In Campylobacter spp., resistance to the antibiotics kanamycin and tetracycline is frequently associated with plasmid-borne genes. However, relatively few plasmids of Campylobacter jejuni have been fully characterized to date. A novel plasmid (p11601MD; 44,095 bp.) harboring tet(O) was identified in...

  7. Transfer of Clostridium difficile Genetic Elements Conferring Resistance to Macrolide-Lincosamide-Streptogramin B (MLSB) Antibiotics.

    Science.gov (United States)

    Barbanti, Fabrizio; Wasels, François; Spigaglia, Patrizia

    2016-01-01

    Molecular analysis is an important tool to investigate Clostridium difficile resistance to macrolide-lincosamide-streptogramin B (MLSB). In particular, the protocols described in this chapter have been designed to investigate the genetic organization of erm(B)-containing elements and to evaluate the capability of these elements to transfer in C. difficile recipient strains using filter mating assay. PMID:27507342

  8. Transgenic expression of the Aedes aegypti CYP9J28 confers pyrethroid resistance in Drosophila melanogaster

    NARCIS (Netherlands)

    N. Pavlidi; M. Monastirioti; P. Daborn; T. Van Leeuwen; J. Vontas

    2012-01-01

    The emergence and spread of insecticide resistance in mosquitoes, such as the major vector of dengue and yellow fever Aedes aegypti, is a major public health problem. A number of studies have been conducted to-date aiming to identify specific molecular changes that are associated with the phenotype,

  9. Transgenic resistance confers effective field level control of bacterial spot disease in tomato.

    Directory of Open Access Journals (Sweden)

    Diana M Horvath

    Full Text Available We investigated whether lines of transgenic tomato (Solanum lycopersicum expressing the Bs2 resistance gene from pepper, a close relative of tomato, demonstrate improved resistance to bacterial spot disease caused by Xanthomonas species in replicated multi-year field trials under commercial type growing conditions. We report that the presence of the Bs2 gene in the highly susceptible VF 36 background reduced disease to extremely low levels, and VF 36-Bs2 plants displayed the lowest disease severity amongst all tomato varieties tested, including commercial and breeding lines with host resistance. Yields of marketable fruit from transgenic lines were typically 2.5 times that of the non-transformed parent line, but varied between 1.5 and 11.5 fold depending on weather conditions and disease pressure. Trials were conducted without application of any copper-based bactericides, presently in wide use despite negative impacts on the environment. This is the first demonstration of effective field resistance in a transgenic genotype based on a plant R gene and provides an opportunity for control of a devastating pathogen while eliminating ineffective copper pesticides.

  10. mTOR target NDRG1 confers MGMT-dependent resistance to alkylating chemotherapy

    Science.gov (United States)

    Weiler, Markus; Blaes, Jonas; Pusch, Stefan; Sahm, Felix; Czabanka, Marcus; Luger, Sebastian; Bunse, Lukas; Solecki, Gergely; Eichwald, Viktoria; Jugold, Manfred; Hodecker, Sibylle; Osswald, Matthias; Meisner, Christoph; Hielscher, Thomas; Rübmann, Petra; Pfenning, Philipp-Niklas; Ronellenfitsch, Michael; Kempf, Tore; Schnölzer, Martina; Abdollahi, Amir; Lang, Florian; Bendszus, Martin; von Deimling, Andreas; Winkler, Frank; Weller, Michael; Vajkoczy, Peter; Platten, Michael; Wick, Wolfgang

    2014-01-01

    A hypoxic microenvironment induces resistance to alkylating agents by activating targets in the mammalian target of rapamycin (mTOR) pathway. The molecular mechanisms involved in this mTOR-mediated hypoxia-induced chemoresistance, however, are unclear. Here we identify the mTOR target N-myc downstream regulated gene 1 (NDRG1) as a key determinant of resistance toward alkylating chemotherapy, driven by hypoxia but also by therapeutic measures such as irradiation, corticosteroids, and chronic exposure to alkylating agents via distinct molecular routes involving hypoxia-inducible factor (HIF)-1alpha, p53, and the mTOR complex 2 (mTORC2)/serum glucocorticoid-induced protein kinase 1 (SGK1) pathway. Resistance toward alkylating chemotherapy but not radiotherapy was dependent on NDRG1 expression and activity. In posttreatment tumor tissue of patients with malignant gliomas, NDRG1 was induced and predictive of poor response to alkylating chemotherapy. On a molecular level, NDRG1 bound and stabilized methyltransferases, chiefly O6-methylguanine-DNA methyltransferase (MGMT), a key enzyme for resistance to alkylating agents in glioblastoma patients. In patients with glioblastoma, MGMT promoter methylation in tumor tissue was not more predictive for response to alkylating chemotherapy in patients who received concomitant corticosteroids. PMID:24367102

  11. Fine mapping of the Ph-3 gene conferring resistance to late blight (Phytophthora infestans) in tomato

    NARCIS (Netherlands)

    Zhang, C.Z.; Liu, L.; Zheng, Z.; Sun, Y.Y.; Zhou, L.X.; Yang, Y.H.; Cheng, F.; Zhang, Z.H.; Wang, X.W.; Huang, S.W.; Xie, B.Y.; Du, Y.C.; Bai, Y.; Li, J.M.

    2013-01-01

    Late blight, caused by the oomycete pathogen Phytophthora infestans (Mont.) de Bary, is a devastating disease for tomato and potato crops. In the past decades, many late blight resistance (R) genes have been characterized in potato. In contrast, less work has been conducted on tomato. The Ph-3 gene

  12. Salicylic acid confers enhanced resistance to Glomerella leaf spot in apple.

    Science.gov (United States)

    Zhang, Ying; Shi, Xiangpeng; Li, Baohua; Zhang, Qingming; Liang, Wenxing; Wang, Caixia

    2016-09-01

    Glomerella leaf spot (GLS) caused by Glomerella cingulata is a newly emergent disease that results in severe defoliation and fruit spots in apple. Currently, there are no effective means to control this disease except for the traditional fungicide sprays. Induced resistance by elicitors against pathogens infection is a widely accepted eco-friendly strategy. In the present study, we investigated whether exogenous application of salicylic acid (SA) could improve resistance to GLS in a highly susceptible apple cultivar (Malus domestica Borkh. cv. 'Gala') and the underlying mechanisms. The results showed that pretreatment with SA, at 0.1-1.0 mM, induced strong resistance against GLS in 'Gala' apple leaves, with SA treated leaves showing significant reduction in lesion numbers and disease index. Concurrent with the enhanced disease resistance, SA treatment markedly increased the total antioxidant capacity (T-AOC) and defence-related enzyme activities, including catalase (CAT), superoxide dismutase (SOD), peroxidase (POD), phenylalanine ammonia-lyase (PAL) and polyphenol oxidase (PPO). As expected, SA treatment also induced the expression levels of five pathogenesis-related (PR) genes including PR1, PR5, PR8, Chitinase and β-1,3-glucanase. Furthermore, the most pronounced and/or rapid increase was observed in leaves treated with SA and subsequently inoculated with G. cingulata compared to the treatment with SA or inoculation with the pathogen. Together, these results suggest that exogenous SA triggered increase in reactive oxygen species levels and the antioxidant system might be responsible for enhanced resistance against G. cingulata in 'Gala' apple leaves. PMID:27139585

  13. 1997 Gordon Research Conference on Plant Cell Walls. Final progress report

    Energy Technology Data Exchange (ETDEWEB)

    Staehelin, A.

    1999-08-25

    The Gordon Research Conference (GRC) on Plant Cell Walls was held at Tilton School, Tilton, New Hampshire, July 18-22, 1997. The conference was well attended with 106 participants. The attendees represented the spectrum of endeavor in this field coming from academia, industry, and government laboratories, both US and foreign scientists, senior researchers, young investigators, and students. In designing the formal speakers program, emphasis was placed on current unpublished research and discussion of the future target areas in this field. There was a conscious effort to stimulate lively discussion about the key issues in the field today. Time for formal presentations was limited in the interest of group discussions. In order that more scientists could communicate their most recent results, poster presentation time was scheduled. In addition to these formal interactions, free time was scheduled to allow informal discussions. Such discussions are fostering new collaborations and joint efforts in the field.

  14. An improved method for transformation of lettuce by Agrobacterium tumefaciens with a gene that confers freezing resistance

    Directory of Open Access Journals (Sweden)

    Pileggi Marcos

    2001-01-01

    Full Text Available An efficient method for constructing transgenic lettuce cultivars by Agrobacterium tumefaciens was described by Torres et al., 1993. In the present work, an improvement of the above procedure is described and applied to transform the cultivar Grand Rapids with a mutated P5CS gene. The major modifications were concerned with turning more practical the transformation and regeneration protocols. Also we tried to improve transformation steps by increasing injured area in explants and prolonging co-cultivation with Agrobacteria (in larger concentration. A more significant selective pressure was used against non-transformed plants and bacteria. In these work we were concerned to obtain T1 and T2 seeds. The P5CS gene codes for a delta¹-pyrroline-5-carboxylate synthetase, a bifunctional enzyme that catalyzes two steps of proline biosynthesis in plants (Zhang et al., 1995; Peng et al., 1996, while the mutated gene is insensitive to feedback inhibition by proline. The potential benefit of this gene is to confer water stress resistance (drought, salt, cold due to increased intracellular levels of proline that works like an osmoprotectant. In this work could obtain and characterize transgenic lettuce lineages which are resistant to freezing temperature.

  15. Critical POU domain residues confer Oct4 uniqueness in somatic cell reprogramming.

    Science.gov (United States)

    Jin, Wensong; Wang, Lei; Zhu, Fei; Tan, Weiqi; Lin, Wei; Chen, Dahua; Sun, Qinmiao; Xia, Zongping

    2016-01-01

    The POU domain transcription factor Oct4 plays critical roles in self-renewal and pluripotency of embryonic stem cells (ESCs). Together with Sox2, Klf4 and c-Myc, Oct4 can reprogram any other cell types to pluripotency, in which Oct4 is the only factor that cannot be functionally replaced by other POU family members. To investigate the determinant elements of Oct4 uniqueness, we performed Ala scan on all Ser, Thr, Tyr, Lys and Arg of murine Oct4 by testing their capability in somatic cell reprogramming. We uncovered a series of residues that are important for Oct4 functionality, in which almost all of these key residues are within the POU domains making direct interaction with DNA. The Oct4 N- and C-terminal transactivation domains (TADs) are not unique and could be replaced by the Yes-associated protein (YAP) TAD domain to support reprogramming. More importantly, we uncovered two important residues that confer Oct4 uniqueness in somatic cell reprogramming. Our systematic structure-function analyses bring novel mechanistic insight into the molecular basis of how critical residues function together to confer Oct4 uniqueness among POU family for somatic cell reprogramming. PMID:26877091

  16. Troglitazone reverses the multiple drug resistance phenotype in cancer cells

    Directory of Open Access Journals (Sweden)

    Gerald F Davies

    2009-03-01

    Full Text Available Gerald F Davies1, Bernhard HJ Juurlink2, Troy AA Harkness11Department of Anatomy and Cell Biology, College of Medicine, University of Saskatchewan, Saskatoon, Canada; 2College of Medicine, Alfaisal University, Riyadh, Kingdom of Saudi ArabiaAbstract: A major problem in treating cancer is the development of drug resistance. We previously demonstrated doxorubicin (DOX resistance in K562 human leukemia cells that was associated with upregulation of glyoxalase 1 (GLO-1 and histone H3 expression. The thiazolidinedione troglitazone (TRG downregulated GLO-1 expression and further upregulated histone H3 expression and post-translational modifications in these cells, leading to a regained sensitivity to DOX. Given the pleiotropic effects of epigenetic changes in cancer development, we hypothesized that TRG may downregulate the multiple drug resistance (MDR phenotype in a variety of cancer cells. To test this, MCF7 human breast cancer cells and K562 cells were cultured in the presence of low-dose DOX to establish DOX-resistant cell lines (K562/DOX and MCF7/DOX. The MDR phenotype was confirmed by Western blot analysis of the 170 kDa P-glycoprotein (Pgp drug efflux pump multiple drug resistance protein 1 (MDR-1, and the breast cancer resistance protein (BCRP. TRG markedly decreased expression of both MDR-1 and BCRP in these cells, resulting in sensitivity to DOX. Silencing of MDR-1 expression also sensitized MCF7/DOX cells to DOX. Use of the specific and irreversible peroxisome proliferator-activated receptor gamma (PPARγ inhibitor GW9662 in the nanomolar range not only demonstrated that the action of TRG on MCF/DOX was PPARγ-independent, but indicated that PPARγ may play a role in the MDR phenotype, which is antagonized by TRG. We conclude that TRG is potentially a useful adjunct therapy in chemoresistant cancers. Keywords: chemotherapy, doxorubicin, breast cancer resistance protein-1, multiple drug resistance, multiple drug resistance protein 1

  17. Overcome Cancer Cell Drug Resistance Using Natural Products

    Directory of Open Access Journals (Sweden)

    Pu Wang

    2015-01-01

    Full Text Available Chemotherapy is one of the major treatment methods for cancer. However, failure in chemotherapy is not uncommon, mainly due to dose-limiting toxicity associated with drug resistance. Management of drug resistance is important towards successful chemotherapy. There are many reports in the Chinese literature that natural products can overcome cancer cell drug resistance, which deserve sharing with scientific and industrial communities. We summarized the reports into four categories: (1 in vitro studies using cell line models; (2 serum pharmacology; (3 in vivo studies using animal models; and (4 clinical studies. Fourteen single compounds were reported to have antidrug resistance activity for the first time. In vitro, compounds were able to overcome drug resistance at nontoxic or subtoxic concentrations, in a dose-dependent manner, by inhibiting drug transporters, cell detoxification capacity, or cell apoptosis sensitivity. Studies in vivo showed that single compounds, herbal extract, and formulas had potent antidrug resistance activities. Importantly, many single compounds, herbal extracts, and formulas have been used clinically to treat various diseases including cancer. The review provides comprehensive data on use of natural compounds to overcome cancer cell drug resistance in China, which may facilitate the therapeutic development of natural products for clinical management of cancer drug resistance.

  18. Drought resistance of Pinus sylvestris seedlings conferred by plastic root architecture rather than ectomycorrhizal colonisation

    OpenAIRE

    Moser, Barbara; Kipfer, Tabea; Richter, Sarah; Egli, Simon; Wohlgemuth, Thomas

    2015-01-01

    Abstract ContextIncreased summer drought is considered as a threat to the regeneration of Pinus sylvestris in the Central Alps. To a certain degree, seedlings are able to mitigate negative effects of drought by altering root/shoot ratios. But, seedlings may also enhance access to water and nutrients by cooperation with ectomycorrhizal fungi. AimsWe tested the importance of both mechanisms for drought resistance of P. sylvestris seedlings during early establishment and assessed whether differe...

  19. Fast and Accurate Large-Scale Detection of β-Lactamase Genes Conferring Antibiotic Resistance

    OpenAIRE

    Lee, Jae Jin; Lee, Jung Hun; Kwon, Dae Beom; Jeon, Jeong Ho; Park, Kwang Seung; Lee, Chang-Ro; Lee, Sang Hee

    2015-01-01

    Fast detection of β-lactamase (bla) genes allows improved surveillance studies and infection control measures, which can minimize the spread of antibiotic resistance. Although several molecular diagnostic methods have been developed to detect limited bla gene types, these methods have significant limitations, such as their failure to detect almost all clinically available bla genes. We developed a fast and accurate molecular method to overcome these limitations using 62 primer pairs, which we...

  20. Depletion of γ-catenin by Histone Deacetylase Inhibition Confers Elimination of CML Stem Cells in Combination with Imatinib.

    Science.gov (United States)

    Jin, Yanli; Yao, Yiwu; Chen, Li; Zhu, Xiaohui; Jin, Bei; Shen, Yingying; Li, Juan; Du, Xin; Lu, Yuhong; Jiang, Sheng; Pan, Jingxuan

    2016-01-01

    Quiescent leukemia stem cells (LSCs) that are insensitive to BCR-ABL tyrosine kinase inhibitors confer resistance to imatinib in chronic myelogenous leukemia (CML). Identifying proteins to regulate survival and stemness of LSCs is urgently needed. Although histone deacetylase inhibitors (HDACis) can eliminate quiescent LSCs in CML, little is known about the underlying mechanism that HDACis kill LSCs. By fishing with a biotin-labeled probe, we identified that HDACi JSL-1 bound to the protein γ-catenin. γ-Catenin expression was higher in LSCs from CML patients than normal hematopoietic stem cells. Silencing γ-catenin in human CML CD34(+) bone-marrow (BM) cells sufficiently eliminated LSCs, which suggests that γ-catenin is required for survival of CML LSCs. Pharmacological inhibition of γ-catenin thwarted survival and self-renewal of human CML CD34(+) cells in vitro, and of murine LSCs in BCR-ABL-driven CML mice. γ-Catenin inhibition reduced long-term engraftment of human CML CD34(+) cells in NOD.Cg-Prkdc (scid) II2rg (tm1Sug)/JicCrl (NOG) mice. Silencing γ-catenin by shRNA in human primary CD34(+) cells did not alter β-catenin, implying a β-catenin-independent role of γ-catenin in survival and self-renewal of CML LSCs. Taken together, our findings validate that γ-catenin may be a novel therapeutic target of LSCs, and suppression of γ-catenin by HDACi may explain elimination of CML LSCs. PMID:27570562

  1. MIMIVIRE is a defence system in mimivirus that confers resistance to virophage.

    Science.gov (United States)

    Levasseur, Anthony; Bekliz, Meriem; Chabrière, Eric; Pontarotti, Pierre; La Scola, Bernard; Raoult, Didier

    2016-03-10

    Since their discovery, giant viruses have revealed several unique features that challenge the conventional definition of a virus, such as their large and complex genomes, their infection by virophages and their presence of transferable short element transpovirons. Here we investigate the sensitivity of mimivirus to virophage infection in a collection of 59 viral strains and demonstrate lineage specificity in the resistance of mimivirus to Zamilon, a unique virophage that can infect lineages B and C of mimivirus but not lineage A. We hypothesized that mimiviruses harbour a defence mechanism resembling the clustered regularly interspaced short palindromic repeat (CRISPR)-Cas system that is widely present in bacteria and archaea. We performed de novo sequencing of 45 new mimivirus strains and searched for sequences specific to Zamilon in a total of 60 mimivirus genomes. We found that lineage A strains are resistant to Zamilon and contain the insertion of a repeated Zamilon sequence within an operon, here named the 'mimivirus virophage resistance element' (MIMIVIRE). Further analyses of the surrounding sequences showed that this locus is reminiscent of a defence mechanism related to the CRISPR-Cas system. Silencing the repeated sequence and the MIMIVIRE genes restores mimivirus susceptibility to Zamilon. The MIMIVIRE proteins possess the typical functions (nuclease and helicase) involved in the degradation of foreign nucleic acids. The viral defence system, MIMIVIRE, represents a nucleic-acid-based immunity against virophage infection. PMID:26934229

  2. Modulation of auxin content in Arabidopsis confers improved drought stress resistance.

    Science.gov (United States)

    Shi, Haitao; Chen, Li; Ye, Tiantian; Liu, Xiaodong; Ding, Kejian; Chan, Zhulong

    2014-09-01

    Auxin is a well-known plant phytohormone that is involved in multiple plant growth processes and stress responses. In this study, auxin response was significantly modulated under drought stress condition. The iaaM-OX transgenic lines with higher endogenous indole-3-acetic acid (IAA) level and IAA pre-treated wild type (WT) plants exhibited enhanced drought stress resistance, while the yuc1yuc2yuc6 triple mutants with lower endogenous IAA level showed decreased stress resistance in comparison to non-treated WT plants. Additionally, endogenous and exogenous auxin positively modulated the expression levels of multiple abiotic stress-related genes (RAB18, RD22, RD29A, RD29B, DREB2A, and DREB2B), and positively affected reactive oxygen species (ROS) metabolism and underlying antioxidant enzyme activities. Moreover, auxin significantly modulated some carbon metabolites including amino acids, organic acids, sugars, sugar alcohols and aromatic amines. Notably, endogenous and exogenous auxin positively modulated root architecture especially the lateral root number. Taken together, this study demonstrated that auxin might participate in the positive regulation of drought stress resistance, through regulation of root architecture, ABA-responsive genes expression, ROS metabolism, and metabolic homeostasis, at least partially. PMID:24992887

  3. Screening for Escherichia coli K-12 genes conferring glyoxal resistance or sensitivity by transposon insertions.

    Science.gov (United States)

    Lee, Changhan; Kim, Jihong; Kwon, Minsuk; Lee, Kihyun; Min, Haeyoung; Kim, Seong Hun; Kim, Dongkyu; Lee, Nayoung; Kim, Jiyeun; Kim, Doyun; Ko, Changmin; Park, Chankyu

    2016-09-01

    Glyoxal (GO) belongs to the reactive electrophilic species generated in vivo in all organisms. In order to identify targets of GO and their response mechanisms, we attempted to screen for GO-sensitive mutants by random insertions of TnphoA-132. The genes responsible for GO susceptibility were functionally classified as the following: (i) tRNA modification; trmE, gidA and truA, (ii) DNA repair; recA and recC, (iii) toxin-antitoxin; mqsA and (iv) redox metabolism; yqhD and caiC In addition, an insertion in the crp gene, encoding the cAMP responsive transcription factor, exhibits a GO-resistant phenotype, which is consistent with the phenotype of adenylate cyclase (cya) mutant showing GO resistance. This suggests that global regulation involving cAMP is operated in a stress response to GO. To further characterize the CRP-regulated genes directly associated with GO resistance, we created double mutants deficient in both crp and one of the candidate genes including yqhD, gloA and sodB The results indicate that these genes are negatively regulated by CRP as confirmed by real-time RT-PCR. We propose that tRNA as well as DNA are the targets of GO and that toxin/antitoxin, antioxidant and cAMP are involved in cellular response to GO.

  4. Breast cancer cells with acquired antiestrogen resistance are sensitized to cisplatin-induced cell death

    DEFF Research Database (Denmark)

    Yde, Christina Westmose; Gyrd-Hansen, Mads; Lykkesfeldt, Anne E;

    2007-01-01

    with parental MCF-7 cells. Our data show that Bcl-2 can protect antiestrogen-resistant breast cancer cells from cisplatin-induced cell death, indicating that the reduced expression of Bcl-2 in the antiestrogen-resistant cells plays a role in sensitizing the cells to cisplatin treatment.......Antiestrogens are currently used for treating breast cancer patients who have estrogen receptor-positive tumors. However, patients with advanced disease will eventually develop resistance to the drugs. Therefore, compounds effective on antiestrogen-resistant tumors will be of great importance...... for future breast cancer treatment. In this study, we have investigated the effect of the chemotherapeutic compound cisplatin using a panel of antiestrogen-resistant breast cancer cell lines established from the human breast cancer cell line MCF-7. We show that the antiestrogen-resistant cells...

  5. Differential resistance to cell entry by porcine endogenous retrovirus subgroup A in rodent species

    Directory of Open Access Journals (Sweden)

    Takeuchi Yasuhiro

    2007-12-01

    Full Text Available Abstract Background The risk of zoonotic infection by porcine endogenous retroviruses (PERV has been highlighted in the context of pig-to-human xenotransplantation. The use of receptors for cell entry often determines the host range of retroviruses. A human-tropic PERV subgroup, PERV-A, can enter human cells through either of two homologous multitransmembrane proteins, huPAR-1 and huPAR-2. Here, we characterised human PARs and their homologues in the PERV-A resistant rodent species, mouse and rat (muPAR and ratPAR, respectively. Results Upon exogenous expression in PERV-A resistant cells, human and rat PARs, but not muPAR, conferred PERV-A sensitivity. Exogenously expressed ratPAR binds PERV-A Env and allows PERV-A infection with equivalent efficiency to that of huPAR-1. Endogenous ratPAR expression in rat cell lines appeared to be too low for PERV-A infection. In contrast, the presence of Pro at position 109 in muPAR was identified to be the determinant for PERV-A resistance. Pro109. was shown to be located in the second extracellular loop (ECL2 and affected PERV-A Env binding to PAR molecules. Conclusion The basis of resistance to PERV-A infection in two rodent species is different. Identification of a single a.a. mutation in muPAR, which is responsible for mouse cell resistance to PERV-A highlighted the importance of ECL-2 for the viral receptor function.

  6. 2012 PLANT CELL WALLS GORDON RESEARCH CONFERENCE AND GORDON RESEARCH SEMINAR, AUGUST 4-10, 2012

    Energy Technology Data Exchange (ETDEWEB)

    Rose, Jocelyn

    2012-08-10

    The sub-theme of this year’s meeting, ‘Cell Wall Research in a Post-Genome World’, will be a consideration of the dramatic technological changes that have occurred in the three years since the previous cell wall Gordon Conference in the area of DNA sequencing. New technologies are providing additional perspectives of plant cell wall biology across a rapidly growing number of species, highlighting a myriad of architectures, compositions, and functions in both "conventional" and specialized cell walls. This meeting will focus on addressing the knowledge gaps and technical challenges raised by such diversity, as well as our need to understand the underlying processes for critical applications such as crop improvement and bioenergy resource development.

  7. Characterisation and Manipulation of Docetaxel Resistant Prostate Cancer Cell Lines

    LENUS (Irish Health Repository)

    O'Neill, Amanda J

    2011-10-07

    Abstract Background There is no effective treatment strategy for advanced castration-resistant prostate cancer. Although Docetaxel (Taxotere®) represents the most active chemotherapeutic agent it only gives a modest survival advantage with most patients eventually progressing because of inherent or acquired drug resistance. The aims of this study were to further investigate the mechanisms of resistance to Docetaxel. Three Docetaxel resistant sub-lines were generated and confirmed to be resistant to the apoptotic and anti-proliferative effects of increasing concentrations of Docetaxel. Results The resistant DU-145 R and 22RV1 R had expression of P-glycoprotein and its inhibition with Elacridar partially and totally reversed the resistant phenotype in the two cell lines respectively, which was not seen in the PC-3 resistant sublines. Resistance was also not mediated in the PC-3 cells by cellular senescence or autophagy but multiple changes in pro- and anti-apoptotic genes and proteins were demonstrated. Even though there were lower basal levels of NF-κB activity in the PC-3 D12 cells compared to the Parental PC-3, docetaxel induced higher NF-κB activity and IκB phosphorylation at 3 and 6 hours with only minor changes in the DU-145 cells. Inhibition of NF-κB with the BAY 11-7082 inhibitor reversed the resistance to Docetaxel. Conclusion This study confirms that multiple mechanisms contribute to Docetaxel resistance and the central transcription factor NF-κB plays an immensely important role in determining docetaxel-resistance which may represent an appropriate therapeutic target.

  8. Identification of amino acids conferring high-level resistance to expanded-spectrum cephalosporins in the penA gene from Neisseria gonorrhoeae strain H041.

    Science.gov (United States)

    Tomberg, Joshua; Unemo, Magnus; Ohnishi, Makoto; Davies, Christopher; Nicholas, Robert A

    2013-07-01

    The recent identification of a high-level-ceftriaxone-resistant (MIC = 2 to 4 μg/ml) isolate of Neisseria gonorrhoeae from Japan (H041) portends the loss of ceftriaxone as an effective treatment for gonococcal infections. This is of grave concern because ceftriaxone is the last remaining option for first-line empirical antimicrobial monotherapy. The penA gene from H041 (penA41) is a mosaic penA allele similar to mosaic alleles conferring intermediate-level cephalosporin resistance (Ceph(i)) worldwide but has 13 additional mutations compared to the mosaic penA gene from the previously studied Ceph(i) strain 35/02 (penA35). When transformed into the wild-type strain FA19, the penA41 allele confers 300- and 570-fold increases in the MICs for ceftriaxone and cefixime, respectively. In order to understand the mechanisms involved in high-level ceftriaxone resistance and to improve surveillance and epidemiology during the potential emergence of ceftriaxone resistance, we sought to identify the minimum number of amino acid alterations above those in penA35 that confer high-level resistance to ceftriaxone. Using restriction fragment exchange and site-directed mutagenesis, we identified three mutations, A311V, T316P, and T483S, that, when incorporated into the mosaic penA35 allele, confer essentially all of the increased resistance of penA41. A311V and T316P are close to the active-site nucleophile Ser310 that forms the acyl-enzyme complex, while Thr483 is predicted to interact with the carboxylate of the β-lactam antibiotic. These three mutations have thus far been described only for penA41, but dissemination of these mutations in other mosaic alleles would spell the end of ceftriaxone as an effective treatment for gonococcal infections.

  9. Molecular cloning of cDNAs which are highly overexpressed in mitoxantrone-resistant cells

    DEFF Research Database (Denmark)

    Miyake, K; Mickley, L; Litman, Thomas;

    1999-01-01

    Reports of multiple distinct mitoxantrone-resistant sublines without overexpression of P-glycoprotein or the multidrug-resistance associated protein have raised the possibility of the existence of another major transporter conferring drug resistance. In the present study, a cDNA library from mito...

  10. DNA Methylation and Apoptosis Resistance in Cancer Cells

    OpenAIRE

    Pierre-François Cartron; François Marie Vallette; Eric Hervouet; Mathilde Cheray

    2013-01-01

    Apoptosis is a cell death programme primordial to cellular homeostasis efficiency. This normal cell suicide program is the result of the activation of a cascade of events in response to death stimuli. Apoptosis occurs in normal cells to maintain a balance between cell proliferation and cell death. A deregulation of this balance due to modifications in the apoptosic pathway leads to different human diseases including cancers. Apoptosis resistance is one of the most important hallmarks of cance...

  11. Hydrodynamic resistance of confined cells in rectangular microchannels

    Science.gov (United States)

    Khan, Zeina S.; Vanapalli, Siva A.

    2011-03-01

    Several microfluidic approaches have been developed to screen suspended cells mechanically in microchannels by exploiting characteristics that are linked to their individual mechanical properties. Typically changes in cell shape due to shear-induced deformation and transit times are reported; while these measurements are qualitative compared to more precise techniques such as atomic force microscopy and micropipette aspiration their advantage lies in throughput, with the ability to screen hundreds to thousands of cells in a minute. We study the potential of a microfluidic cell squeezer to characterize the hydrodynamic resistance of LNCaP prostate cancer cells by measuring dynamical pressure-drop variations along a micrometer-sized channel. The hydrodynamic resistance of the cell introduces an excess pressure drop in the narrow channel which depends on the mechanical stiffness of the cell. We additionally visualize the cell size and assess the influence of cell size on the hydrodynamic resistance of each cell, demonstrating the capability of the microfluidic cell squeezer to yield the hydrodynamic resistance as a mechanical fingerprint of cells.

  12. Hantavirus-infection confers resistance to cytotoxic lymphocyte-mediated apoptosis.

    Directory of Open Access Journals (Sweden)

    Shawon Gupta

    2013-03-01

    Full Text Available Hantaviruses cause hemorrhagic fever with renal syndrome (HFRS and hantavirus cardio-pulmonary syndrome (HCPS; also called hantavirus pulmonary syndrome (HPS, both human diseases with high case-fatality rates. Endothelial cells are the main targets for hantaviruses. An intriguing observation in patients with HFRS and HCPS is that on one hand the virus infection leads to strong activation of CD8 T cells and NK cells, on the other hand no obvious destruction of infected endothelial cells is observed. Here, we provide an explanation for this dichotomy by showing that hantavirus-infected endothelial cells are protected from cytotoxic lymphocyte-mediated induction of apoptosis. When dissecting potential mechanisms behind this phenomenon, we discovered that the hantavirus nucleocapsid protein inhibits the enzymatic activity of both granzyme B and caspase 3. This provides a tentative explanation for the hantavirus-mediated block of cytotoxic granule-mediated apoptosis-induction, and hence the protection of infected cells from cytotoxic lymphocytes. These findings may explain why infected endothelial cells in hantavirus-infected patients are not destroyed by the strong cytotoxic lymphocyte response.

  13. Generation of a human hepatoma cell line supporting efficient replication of a lamivudine resistant hepatitis B virus.

    Science.gov (United States)

    Zhang, Yijun; Zhang, Yongmei; Kang, Yaoyue; Wang, Jinyu; Liu, Hongyan; Zhu, Haoxiang; Qin, Yanli; Mao, Richeng; Lin, Xu; Lu, Mengji; Zhang, Jiming

    2014-06-01

    Emergence of lamivudine (LAM) resistance causes treatment failure in patients with chronic hepatitis B and compromise the efficacy of subsequent salvage therapies with other nucleot(s)ide analogs (NAs). Establishment of cell-based assays supporting LAM-resistant hepatitis B virus (HBV) replication will not only provide tools for investigating the replication property, but also screening for antiviral agents efficiently inhibiting the replication of LAM-resistant HBV variants. Accordingly, a human hepatoma (HepG2)-derived cell line was established by stable transfection of a plasmid containing a 1.2 unit length of HBV genome harboring rtL180M and rtM204V mutations that confer LAM resistance. In addition to support efficient viral genome replication, the cell line also produces high levels of HBV virions and subviral particles. As expected, HBV DNA replication in this cell line is completely resistant to lamivudine, but sensitive to adefovir (ADV), entecavir (ETV) and tenofovir (TDF). The cell line is suitable for screening for antiviral agents that inhibit LAM-resistant HBV replication and inhibitors of HBsAg biosynthesis and secretion, which may reduce HBsAg antigenemia and ultimately help to restore host antiviral immune response against HBV and cure chronic HBV infection. PMID:24583110

  14. Mutations in Novel Lipopolysaccharide Biogenesis Genes Confer Resistance to Amoebal Grazing in Synechococcus elongatus.

    Science.gov (United States)

    Simkovsky, Ryan; Effner, Emily E; Iglesias-Sánchez, Maria José; Golden, Susan S

    2016-05-01

    In natural and artificial aquatic environments, population structures and dynamics of photosynthetic microbes are heavily influenced by the grazing activity of protistan predators. Understanding the molecular factors that affect predation is critical for controlling toxic cyanobacterial blooms and maintaining cyanobacterial biomass production ponds for generating biofuels and other bioproducts. We previously demonstrated that impairment of the synthesis or transport of the O-antigen component of lipopolysaccharide (LPS) enables resistance to amoebal grazing in the model predator-prey system consisting of the heterolobosean amoeba HGG1 and the cyanobacteriumSynechococcus elongatusPCC 7942 (R. S. Simkovsky et al., Proc Natl Acad Sci U S A 109:16678-16683, 2012,http://dx.doi.org/10.1073/pnas.1214904109). In this study, we used this model system to identify additional gene products involved in the synthesis of O antigen, the ligation of O antigen to the lipid A-core conjugated molecule (including a novel ligase gene), the generation of GDP-fucose, and the incorporation of sugars into the lipid A core oligosaccharide ofS. elongatus Knockout of any of these genes enables resistance to HGG1, and of these, only disruption of the genes involved in synthesis or incorporation of GDP-fucose into the lipid A-core molecule impairs growth. Because these LPS synthesis genes are well conserved across the diverse range of cyanobacteria, they enable a broader understanding of the structure and synthesis of cyanobacterial LPS and represent mutational targets for generating resistance to amoebal grazers in novel biomass production strains. PMID:26921432

  15. Hepatitis C virus cell-cell transmission and resistance to direct-acting antiviral agents

    DEFF Research Database (Denmark)

    Xiao, Fei; Fofana, Isabel; Heydmann, Laura;

    2014-01-01

    -targeting entry inhibitors (HTEIs) was highly effective in inhibiting viral dissemination of resistant genotype 2 viruses. Combining HTEIs with DAAs prevented antiviral resistance and led to rapid elimination of the virus in cell culture model. In conclusion, our work provides evidence that cell-cell transmission......Hepatitis C virus (HCV) is transmitted between hepatocytes via classical cell entry but also uses direct cell-cell transfer to infect neighboring hepatocytes. Viral cell-cell transmission has been shown to play an important role in viral persistence allowing evasion from neutralizing antibodies. In...... contrast, the role of HCV cell-cell transmission for antiviral resistance is unknown. Aiming to address this question we investigated the phenotype of HCV strains exhibiting resistance to direct-acting antivirals (DAAs) in state-of-the-art model systems for cell-cell transmission and spread. Using HCV...

  16. Conferred resistance to Botrytis cinerea in Lilium by overexpression of the RCH10 chitinase gene

    OpenAIRE

    Núñez de Cáceres González, Francisco; Davey, Michael R.; Cancho Sánchez, Ester; Wilson, Zoe A

    2015-01-01

    The production of ornamentals is an important global industry, with Lilium being one of the six major bulb crops in the world. The international trade in ornamentals is in the order of £60-75 billion and is expected to increase worldwide by 2-4 % per annum. The continued success of the floriculture industry depends on the introduction of new species/cultivars with major alterations in key agronomic characteristics, such as resistance to pathogens. Fungal diseases are the cause of reduced yiel...

  17. Acute myeloid leukemia cells MOLM-13 and SKM-1 established for resistance by azacytidine are crossresistant to P-glycoprotein substrates.

    Science.gov (United States)

    Messingerova, Lucia; Imrichova, Denisa; Kavcova, Helena; Turakova, Katarina; Breier, Albert; Sulova, Zdena

    2015-10-01

    Establishment of the acute myeloid leukemia cells SKM-1 and MOLM-13 for resistance by azacytidine (AzaC) resulted in SKM-1/AzaC and MOLM-13/AzaC cell variants with reduced sensitivity to AzaC. Despite the fact that AzaC is not substrate of P-glycoprotein (P-gp), the adaptation procedure resulted in an induction in P-gp expression/efflux activity that confers crossresistance to P-gp substrates in both resistant cell variants. While the resistance to P-gp substrates in SKM-1/AzaC and MOLM-13/AzaC cells could be reversed by the P-gp inhibitors, resistance to AzaC was insensitive to these inhibitors in both resistant cell variants. In addition, NF-κB and the antiapoptotic protein Bcl-2 were downregulated and the proapoptotic proteins Bax and p53 were upregulated in both resistant cell variants when compared with their sensitive counterparts. Moreover, at least five times the elevation in overall glutathione S-transferase activity was measured with 1-chloro-2, 5-dinitrobenzene as a substrate in the resistant variant of both cell lines. Taken together, the findings of the present study indicate that the treatment of AML cells with AzaC might lead to a drug resistance phenotype that may be associated with cross resistance to P-gp substrates and substrates of glutathione S-transferases.

  18. Molecular characterization of a gene that confers 2-deoxyglucose resistance in yeast.

    Science.gov (United States)

    Sanz, P; Randez-Gil, F; Prieto, J A

    1994-09-01

    We have isolated a gene whose expression enables yeast cells to overcome the inhibition of growth produced by the presence of 2-deoxyglucose. The gene contains an open reading frame of 738 bp that may code for a protein of 27,100 Da. Cells carrying this gene contain high levels of a specific 2-deoxyglucose-6-phosphate phosphatase. The expression of this phosphatase is increased by the presence of 2-deoxyglucose and is constant along the growth curve. PMID:7754708

  19. The Cytochrome P450 gene CYP6P12 confers pyrethroid resistance in kdr-free Malaysian populations of the dengue vector Aedes albopictus.

    Science.gov (United States)

    Ishak, Intan H; Riveron, Jacob M; Ibrahim, Sulaiman S; Stott, Rob; Longbottom, Joshua; Irving, Helen; Wondji, Charles S

    2016-01-01

    Control of Aedes albopictus, major dengue and chikungunya vector, is threatened by growing cases of insecticide resistance. The mechanisms driving this resistance remain poorly characterised. This study investigated the molecular basis of insecticide resistance in Malaysian populations of Ae. albopictus. Microarray-based transcription profiling revealed that metabolic resistance (cytochrome P450 up-regulation) and possibly a reduced penetration mechanism (consistent over-expression of cuticular protein genes) were associated with pyrethroid resistance. CYP6P12 over-expression was strongly associated with pyrethroid resistance whereas CYP6N3 was rather consistently over-expressed across carbamate and DDT resistant populations. Other detoxification genes also up-regulated in permethrin resistant mosquitoes included a glucuronosyltransferase (AAEL014279-RA) and the glutathione-S transferases GSTS1 and GSTT3. Functional analyses further supported that CYP6P12 contributes to pyrethroid resistance in Ae. albopictus as transgenic expression of CYP6P12 in Drosophila was sufficient to confer pyrethroid resistance in these flies. Furthermore, molecular docking simulations predicted CYP6P12 possessing enzymatic activity towards pyrethroids. Patterns of polymorphism suggested early sign of selection acting on CYP6P12 but not on CYP6N3. The major role played by P450 in the absence of kdr mutations suggests that addition of the synergist PBO to pyrethroids could improve the efficacy of this insecticide class and overcome resistance in field populations of Ae. albopictus. PMID:27094778

  20. Enhanced resistance to nanoparticle toxicity is conferred by overproduction of extracellular polymeric substances

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, Nimisha, E-mail: joshi.nimisha@gmail.com [School of GeoSciences, Microbial Geochemistry Laboratory, University of Edinburgh, West Mains Road, Edinburgh EH9 3JW (United Kingdom); Ngwenya, Bryne T. [School of GeoSciences, Microbial Geochemistry Laboratory, University of Edinburgh, West Mains Road, Edinburgh EH9 3JW (United Kingdom); French, Christopher E. [School of Biological Sciences, Institute of Cell Biology, Darwin Building, University of Edinburgh, Mayfield Road, Edinburgh EH9 3JR (United Kingdom)

    2012-11-30

    Highlights: Black-Right-Pointing-Pointer Demonstration that bacteria engineered for EPS overproduction have better survival against Ag nanotoxicity. Black-Right-Pointing-Pointer EPS destabilises Ag nanoparticles and promotes their aggregation. Black-Right-Pointing-Pointer TEM demonstration that EPS traps the Ag nanoparticles outside the cell. Black-Right-Pointing-Pointer EPS from overexpressing strains offers protection to non-EPS strains of bacteria. Black-Right-Pointing-Pointer EPS polymer analogues such as xanthan also produce a similar response. - Abstract: The increasing production and use of engineered nanoparticles, coupled with their demonstrated toxicity to different organisms, demands the development of a systematic understanding of how nanoparticle toxicity depends on important environmental parameters as well as surface properties of both cells and nanomaterials. We demonstrate that production of the extracellular polymeric substance (EPS), colanic acid by engineered Escherichia coli protects the bacteria against silver nanoparticle toxicity. Moreover, exogenous addition of EPS to a control strain results in an increase in cell viability, as does the addition of commercial EPS polymer analogue xanthan. Furthermore, we have found that an EPS producing strain of Sinorhizobium meliloti shows higher survival upon exposure to silver nanoparticles than the parent strain. Transmission electron microscopy (TEM) observations showed that EPS traps the nanoparticles outside the cells and reduces the exposed surface area of cells to incoming nanoparticles by inducing cell aggregation. Nanoparticle size characterization in the presence of EPS and xanthan indicated a marked tendency towards aggregation. Both are likely effective mechanisms for reducing nanoparticle toxicity in the natural environment.

  1. Enhanced resistance to nanoparticle toxicity is conferred by overproduction of extracellular polymeric substances

    International Nuclear Information System (INIS)

    Highlights: ► Demonstration that bacteria engineered for EPS overproduction have better survival against Ag nanotoxicity. ► EPS destabilises Ag nanoparticles and promotes their aggregation. ► TEM demonstration that EPS traps the Ag nanoparticles outside the cell. ► EPS from overexpressing strains offers protection to non-EPS strains of bacteria. ► EPS polymer analogues such as xanthan also produce a similar response. - Abstract: The increasing production and use of engineered nanoparticles, coupled with their demonstrated toxicity to different organisms, demands the development of a systematic understanding of how nanoparticle toxicity depends on important environmental parameters as well as surface properties of both cells and nanomaterials. We demonstrate that production of the extracellular polymeric substance (EPS), colanic acid by engineered Escherichia coli protects the bacteria against silver nanoparticle toxicity. Moreover, exogenous addition of EPS to a control strain results in an increase in cell viability, as does the addition of commercial EPS polymer analogue xanthan. Furthermore, we have found that an EPS producing strain of Sinorhizobium meliloti shows higher survival upon exposure to silver nanoparticles than the parent strain. Transmission electron microscopy (TEM) observations showed that EPS traps the nanoparticles outside the cells and reduces the exposed surface area of cells to incoming nanoparticles by inducing cell aggregation. Nanoparticle size characterization in the presence of EPS and xanthan indicated a marked tendency towards aggregation. Both are likely effective mechanisms for reducing nanoparticle toxicity in the natural environment.

  2. Is Resistance Useless? Multidrug Resistance and Collateral Sensitivity

    OpenAIRE

    Hall, Matthew D.; Handley, Misty D.; Gottesman, Michael M.

    2009-01-01

    When cancer cells develop resistance to chemotherapeutics, it is frequently conferred by the ATP-dependent efflux pump P-glycoprotein (MDR1, P-gp, ABCB1). P-gp can efflux a wide range of cancer drugs; thus its expression confers cross-resistance, termed multidrug resistance (MDR), to a wide range of drugs. Strategies to overcome this resistance have been actively sought for over 30 years, yet no clinical solutions exist. A less understood aspect of MDR is the hypersensitivity of resistant can...

  3. A genetic marker allele conferring resistance to Ascaris suum in pigs

    DEFF Research Database (Denmark)

    Skallerup, Per; Thamsborg, Stig M.; Jørgensen, Claus B.;

    2013-01-01

    Mapping of quantitative trait loci (QTLs) has helped dissecting the genetics underlying the variation in resistance to helminth infections. In pigs, two single nucleotide polymorphisms (SNP TXNIP and SNP ARNT), both on chromosome 4, have been reported to be associated with Ascaris suum worm burden...... of the AB genotype. We used different indicators of resistance (worm burden, faecal egg counts, number of liver white spots and A. suum-specific serum IgG antibody levels) of which the first two traits were considered core traits and the last two traits were associated traits. Pigs of the AA genotype had...... lower mean macroscopic worm burden (2.4 vs. 19.3), lower mean total worm burden (26.5 vs. 70.1) and excreted fewer A. suum eggs at week 8 p.i. (mean number of eggs/g faeces: 238 vs. 1259) than pigs of the AB genotype. However, none of these differences were significant (P- values of 0.06, 0.06 and 0...

  4. Characterization of Mobile Staphylococcus equorum Plasmids Isolated from Fermented Seafood That Confer Lincomycin Resistance.

    Directory of Open Access Journals (Sweden)

    Jong-Hoon Lee

    Full Text Available The complete nucleotide sequences of lincomycin-resistance gene (lnuA-containing plasmids in Staphylococcus equorum strains isolated from the high-salt-fermented seafood jeotgal were determined. These plasmids, designated pSELNU1-3, are 2638-bp long, have two polymorphic sites, and encode typical elements found in plasmids that replicate via a rolling-circle mechanism including the replication protein gene (rep, a double-stranded origin of replication, a single-stranded origin of replication, and counter-transcribed RNA sequence, as well as lnuA. Plasmid sequences exhibit over 83% identity to other Staphylococcus plasmids that harbor rep and lnuA genes. Further, three pairs of identified direct repeats may be involved in inter-plasmid recombination. One plasmid, pSELNU1, was successfully transferred to other Staphylococcus species, Enterococcus faecalis, and Tetragenococcus halophilus in vitro. Antibiotic susceptibility of the transconjugants was host-dependent, and transconjugants maintained a lincomycin resistance phenotype in the absence of selective pressure over 60 generations.

  5. Characterization of Mobile Staphylococcus equorum Plasmids Isolated from Fermented Seafood That Confer Lincomycin Resistance.

    Science.gov (United States)

    Lee, Jong-Hoon; Jeong, Do-Won

    2015-01-01

    The complete nucleotide sequences of lincomycin-resistance gene (lnuA)-containing plasmids in Staphylococcus equorum strains isolated from the high-salt-fermented seafood jeotgal were determined. These plasmids, designated pSELNU1-3, are 2638-bp long, have two polymorphic sites, and encode typical elements found in plasmids that replicate via a rolling-circle mechanism including the replication protein gene (rep), a double-stranded origin of replication, a single-stranded origin of replication, and counter-transcribed RNA sequence, as well as lnuA. Plasmid sequences exhibit over 83% identity to other Staphylococcus plasmids that harbor rep and lnuA genes. Further, three pairs of identified direct repeats may be involved in inter-plasmid recombination. One plasmid, pSELNU1, was successfully transferred to other Staphylococcus species, Enterococcus faecalis, and Tetragenococcus halophilus in vitro. Antibiotic susceptibility of the transconjugants was host-dependent, and transconjugants maintained a lincomycin resistance phenotype in the absence of selective pressure over 60 generations. PMID:26448648

  6. Altered glycosylation of platelet-derived von Willebrand factor confers resistance to ADAMTS13 proteolysis.

    Science.gov (United States)

    McGrath, Rachel T; van den Biggelaar, Maartje; Byrne, Barry; O'Sullivan, Jamie M; Rawley, Orla; O'Kennedy, Richard; Voorberg, Jan; Preston, Roger J S; O'Donnell, James S

    2013-12-12

    Platelet-von Willebrand factor (VWF) is stored within α-granules and accounts for ∼20% of total VWF in platelet-rich plasma. This platelet-VWF pool is distinct from plasma-VWF and is enriched in high molecular weight multimers (HMWM). Previous studies have described significant functional discrepancies between platelet-VWF and plasma-VWF; however, the molecular basis of these differences is not well understood. We have characterized terminal glycan expression on platelet-VWF. Our findings demonstrate that platelet-VWF exists as a distinct natural glycoform. In particular, N-linked sialylation is markedly reduced (>50%) compared with plasma-VWF. Moreover, unlike plasma-VWF, platelet-VWF does not express AB blood group determinants, although precursor H antigen expression is similar to that on plasma-VWF. Because of this differential glycosylation, platelet-VWF exhibits specific resistance to ADAMTS13 proteolysis. Thus platelet activation at sites of vascular injury results in the release of high local concentrations of HMWM platelet-VWF that is more resistant to ADAMTS13, thereby facilitating platelet-plug formation. PMID:24106205

  7. Th17 cells confer long-term adaptive immunity to oral mucosal Candida albicans infections.

    Science.gov (United States)

    Hernández-Santos, N; Huppler, A R; Peterson, A C; Khader, S A; McKenna, K C; Gaffen, S L

    2013-09-01

    Oropharyngeal candidiasis (OPC) is an opportunistic infection caused by Candida albicans. Despite its prevalence, little is known about C. albicans-specific immunity in the oral mucosa. Vaccines against Candida generate both T helper type 1 (Th1) and Th17 responses, and considerable evidence implicates interleukin (IL)-17 in immunity to OPC. However, IL-17 is also produced by innate immune cells that are remarkably similar to Th17 cells, expressing the same markers and localizing to similar mucosal sites. To date, the relative contribution(s) of Th1, Th17, and innate IL-17-producing cells in OPC have not been clearly defined. Here, we sought to determine the nature and function of adaptive T-cell responses to OPC, using a new recall infection model. Mice subjected to infection and re-challenge with Candida mounted a robust and stable antigen-specific IL-17 response in CD4+ but not CD8+ T cells. There was little evidence for Th1 or Th1/Th17 responses. The Th17 response promoted accelerated fungal clearance, and Th17 cells could confer protection in Rag1-/- mice upon adoptive transfer. Surprisingly, CD4 deficiency did not cause OPC but was instead associated with compensatory IL-17 production by Tc17 and CD3+CD4-CD8- cells. Therefore, classic CD4+Th17 cells protect from OPC but can be compensated by other IL-17-producing cells in CD4-deficient hosts. PMID:23250275

  8. Mapping of a Leishmania major gene/locus that confers pentamidine resistance by deletion and insertion of transposable element

    Directory of Open Access Journals (Sweden)

    Coelho Adriano C.

    2004-01-01

    Full Text Available Pentamidine (PEN is an alternative compound to treat antimony-resistant leishmaniasis patients, which cellular target remains unclear. One approach to the identification of prospective targets is to identify genes able to mediate PEN resistance following overexpression. Starting from a genomic library of transfected parasites bearing a multicopy episomal cosmid vector containing wild-type Leishmania major DNA, we isolated one locus capable to render PEN resistance to wild type cells after DNA transfection. In order to map this Leishmania locus, cosmid insert was deleted by two successive sets of partial digestion with restriction enzymes, followed by transfection into wild type cells, overexpression, induction and functional tests in the presence of PEN. To determine the Leishmania gene related to PEN resistance, nucleotide sequencing experiments were done through insertion of the transposon Mariner element of Drosophila melanogaster (mosK into the deleted insert to work as primer island. Using general molecular techniques, we described here this method that permits a quickly identification of a functional gene facilitating nucleotide sequence experiments from large DNA fragments. Followed experiments revealed the presence of a P-Glycoprotein gene in this locus which role in Leishmania metabolism has now been analyzed.

  9. Collateral chemoresistance to anti-microtubule agents in a lung cancer cell line with acquired resistance to erlotinib.

    Science.gov (United States)

    Mizuuchi, Hiroshi; Suda, Kenichi; Sato, Katsuaki; Tomida, Shuta; Fujita, Yoshihiko; Kobayashi, Yoshihisa; Maehara, Yoshihiko; Sekido, Yoshitaka; Nishio, Kazuto; Mitsudomi, Tetsuya

    2015-01-01

    Various alterations underlying acquired resistance to epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) have been described. Although treatment strategies specific for these mechanisms are under development, cytotoxic agents are currently employed to treat many patients following failure of EGFR-TKIs. However, the effect of TKI resistance on sensitivity to these cytotoxic agents is mostly unclear. This study investigated the sensitivity of erlotinib-resistant tumor cells to five cytotoxic agents using an in vitro EGFR-TKI-resistant model. Four erlotinib-sensitive lung adenocarcinoma cell lines and their resistant derivatives were tested. Of the resistant cell lines, all but one showed a similar sensitivity to the tested drugs as their parental cells. HCC4006ER cells with epithelial mesenchymal transition features acquired resistance to the three microtubule-targeting agents, docetaxel, paclitaxel and vinorelbine, but not to cisplatin and gemcitabine. Gene expression array and immunoblotting demonstrated that ATP-binding cassette subfamily B, member 1 (ABCB1) was up-regulated in HCC4006ER cells. ABCB1 knockdown by siRNA partially restored sensitivity to the anti-microtubule agents but not to erlotinib. Moreover, the histone deacetylase inhibitor entinostat sensitized HCC4006ER cells to anti-microtubule agents through ABCB1 suppression. Our study indicates that sensitivity of tumor cells to cytotoxic agents in general does not change before and after failure of EGFR-TKIs. However, we describe that two different molecular alterations confer acquired resistance to EGFR-TKIs and cytotoxic agents, respectively. This phenomenon should be kept in mind in selection of subsequent therapy after failure of EGFR-TKIs. PMID:25875914

  10. Collateral chemoresistance to anti-microtubule agents in a lung cancer cell line with acquired resistance to erlotinib.

    Directory of Open Access Journals (Sweden)

    Hiroshi Mizuuchi

    Full Text Available Various alterations underlying acquired resistance to epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs have been described. Although treatment strategies specific for these mechanisms are under development, cytotoxic agents are currently employed to treat many patients following failure of EGFR-TKIs. However, the effect of TKI resistance on sensitivity to these cytotoxic agents is mostly unclear. This study investigated the sensitivity of erlotinib-resistant tumor cells to five cytotoxic agents using an in vitro EGFR-TKI-resistant model. Four erlotinib-sensitive lung adenocarcinoma cell lines and their resistant derivatives were tested. Of the resistant cell lines, all but one showed a similar sensitivity to the tested drugs as their parental cells. HCC4006ER cells with epithelial mesenchymal transition features acquired resistance to the three microtubule-targeting agents, docetaxel, paclitaxel and vinorelbine, but not to cisplatin and gemcitabine. Gene expression array and immunoblotting demonstrated that ATP-binding cassette subfamily B, member 1 (ABCB1 was up-regulated in HCC4006ER cells. ABCB1 knockdown by siRNA partially restored sensitivity to the anti-microtubule agents but not to erlotinib. Moreover, the histone deacetylase inhibitor entinostat sensitized HCC4006ER cells to anti-microtubule agents through ABCB1 suppression. Our study indicates that sensitivity of tumor cells to cytotoxic agents in general does not change before and after failure of EGFR-TKIs. However, we describe that two different molecular alterations confer acquired resistance to EGFR-TKIs and cytotoxic agents, respectively. This phenomenon should be kept in mind in selection of subsequent therapy after failure of EGFR-TKIs.

  11. Cell biological mechanisms of multidrug resistance in tumors.

    OpenAIRE

    Simon, S. M.; Schindler, M

    1994-01-01

    Multidrug resistance (MDR) is a generic term for the variety of strategies tumor cells use to evade the cytotoxic effects of anticancer drugs. MDR is characterized by a decreased sensitivity of tumor cells not only to the drug employed for chemotherapy but also to a broad spectrum of drugs with neither obvious structural homology nor common targets. This pleiotropic resistance is one of the major obstacles to the successful treatment of tumors. MDR may result from structural or functional cha...

  12. Is resistance futile? Changing external resistance does not improve microbial fuel cell performance.

    Science.gov (United States)

    Lyon, Delina Y; Buret, Francois; Vogel, Timothy M; Monier, Jean-Michel

    2010-04-01

    Microbial fuel cells (MFCs) show promise as an alternative to conventional batteries for point source electricity generation. A better understanding of the relationship between the microbiological and electrical aspects of fuels cells is needed prior to successful MFC application. Here, we observed the effects of external resistance on power production and the anodic biofilm community structure. Large differences in the external resistance affected both power production and microbial community structure. After the establishment of the anodic microbial community, change in external resistance (from low to high and vice versa) changed the anodic microbial community structure, but the resulting community did not resemble the communities established at that same external resistance. Different microbial community structures, established under different external resistances, resulted in similar power production, demonstrating the flexibility of the MFC system. PMID:19783225

  13. Mutations in an Atypical TIR-NB-LRR-LIM Resistance Protein Confer Autoimmunity

    Science.gov (United States)

    Bi, Dongling; Johnson, Kaeli C. M.; Zhu, Zhaohai; Huang, Yan; Chen, Fang; Zhang, Yuelin; Li, Xin

    2011-01-01

    In order to defend against microbial infection, plants employ a complex immune system that relies partly on resistance (R) proteins that initiate intricate signaling cascades upon pathogen detection. The resistance signaling network utilized by plants is only partially characterized. A genetic screen conducted to identify novel defense regulators involved in this network resulted in the isolation of the snc6-1D mutant. Positional cloning revealed that this mutant contained a molecular lesion in the chilling sensitive 3 (CHS3) gene, thus the allele was renamed chs3-2D. CHS3 encodes a TIR-NB-LRR R protein that contains a C-terminal zinc-binding LIM (Lin-11, Isl-1, Mec-3) domain. Although this protein has been previously implicated in cold stress and defense response, the role of the LIM domain in modulating protein activity is unclear. The chs3-2D allele contains a G to A point mutation causing a C1340 to Y1340 substitution close to the LIM domain. It encodes a dominant gain-of-function mutation. The chs3-2D mutant is severely stunted and displays curled leaf morphology. Additionally, it constitutively expresses PATHOGENESIS-RELATED (PR) genes, accumulates salicylic acid, and shows enhanced resistance to the virulent oomycete isolate Hyaloperonospora arabidopsidis (H.a.) Noco2. Subcellular localization assays using GFP fusion constructs indicate that both CHS3 and chs3-2D localize to the nucleus. A third chs3 mutant allele, chs3-3D, was identified in an unrelated genetic screen in our lab. This allele contains a C to T point mutation resulting in an M1017 to V1017 substitution in the LRR–LIM linker region. Additionally, a chs3-2D suppressor screen identified two revertant alleles containing secondary mutations that abolish the mutant morphology. Analysis of the locations of these molecular lesions provides support for the hypothesis that the LIM domain represses CHS3 R-like protein activity. This repression may occur through either autoinhibition or binding of a

  14. Mutations in an atypical TIR-NB-LRR-LIM resistance protein confers autoimmunity

    Directory of Open Access Journals (Sweden)

    Dongling eBi

    2011-10-01

    Full Text Available In order to defend against infection, plants employ a complex immune system that relies partly on resistance (R proteins which initiate intricate signalling cascades upon pathogen detection. The resistance signalling network in plants is only partially characterized. A genetic screen conducted to identify novel defense regulators involved in this network resulted in the isolation of the snc6-1D mutant. Positional cloning revealed that this mutant contained a molecular lesion in the CHILLING SENSITIVE 3 (CHS3 gene, thus the allele was renamed chs3-2D. CHS3 encodes a TIR-NB-LRR R protein that contains a C-terminal zinc-binding LIM (Lin-11, Isl-1, Mec-3 domain. Although this protein has been previously implicated in cold stress and defense response, the role of the LIM domain in modulating protein activity is unclear. The chs3-2D allele contains a G to A point mutation causing a C1340 to Y1340 substitution close to the LIM domain. It encodes a dominant, gain-of-function mutation. The chs3-2D mutant is stunted and displays curled leaf morphology. Additionally, it constitutively expresses PATHOGENESIS-RELATED (PR genes, accumulates salicylic acid, and shows enhanced resistance to the virulent oomycete isolate Hyaloperonospora arabidopsidis (H.a. Noco2. Subcellular localization assays using GFP fusion constructs indicate that both CHS3 and chs3-2D localize to the nucleus. A third mutant allele, chs3-3D, was identified in an unrelated genetic screen in our lab. This allele contains a C to T point mutation resulting in an M1017 to V1017 substitution in the LRR-LIM linker region. Additionally, a chs3-2D suppressor screen identified two revertant alleles containing secondary mutations that abolish the mutant morphology. Analysis of the locations of these molecular lesions provides support for the hypothesis that the LIM domain represses CHS3 R-like protein activity. This repression may occur through either autoinhibition or binding of a negative defense

  15. The flavoprotein Tah18-dependent NO synthesis confers high-temperature stress tolerance on yeast cells

    Energy Technology Data Exchange (ETDEWEB)

    Nishimura, Akira; Kawahara, Nobuhiro [Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192 (Japan); Takagi, Hiroshi, E-mail: hiro@bs.naist.jp [Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192 (Japan)

    2013-01-04

    Highlights: Black-Right-Pointing-Pointer NO is produced from L-arginine in response to elevated temperature in yeast. Black-Right-Pointing-Pointer Tah18 was first identified as the yeast protein involved in NO synthesis. Black-Right-Pointing-Pointer Tah18-dependent NO synthesis confers tolerance to high-temperature on yeast cells. -- Abstract: Nitric oxide (NO) is a ubiquitous signaling molecule involved in the regulation of a large number of cellular functions. In the unicellular eukaryote yeast, NO may be involved in stress response pathways, but its role is poorly understood due to the lack of mammalian NO synthase (NOS) orthologues. Previously, we have proposed the oxidative stress-induced L-arginine synthesis and its physiological role under stress conditions in yeast Saccharomyces cerevisiae. Here, our experimental results indicated that increased conversion of L-proline into L-arginine led to NO production in response to elevated temperature. We also showed that the flavoprotein Tah18, which was previously reported to transfer electrons to the Fe-S cluster protein Dre2, was involved in NO synthesis in yeast. Gene knockdown analysis demonstrated that Tah18-dependent NO synthesis confers high-temperature stress tolerance on yeast cells. As it appears that such a unique cell protection mechanism is specific to yeasts and fungi, it represents a promising target for antifungal activity.

  16. Kinase domain mutations confer resistance to novel inhibitors targeting JAK2V617F in myeloproliferative neoplasms

    OpenAIRE

    Deshpande, Anagha; Reddy, Mamatha M.; Schade, Georg O.M.; Ray, Arghya; Chowdary, Tirumala K.; Griffin, James D.; Sattler, Martin

    2011-01-01

    The transforming JAK2V617F kinase is frequently associated with myeloproliferative neoplasms (MPNs) and thought to be instrumental for the overproduction of myeloid lineage cells. Several small molecule drugs targeting JAK2 are currently in clinical development for treatment in these diseases. We performed a high-throughput in vitro screen to identify point mutations in JAK2V617F that would be predicted to have potential clinical relevance and associated with drug resistance to the JAK2 inhib...

  17. Expression of Dm-AMP1 in rice confers resistance to Magnaporthe oryzae and Rhizoctonia solani.

    Science.gov (United States)

    Jha, Sanjay; Tank, Harsukh G; Prasad, Bishun Deo; Chattoo, Bharat B

    2009-02-01

    Magnaporthe oryzae and Rhizoctonia solani, are among the most important pathogens of rice, severely limiting its productivity. Dm-AMP1, an antifungal plant defensin from Dahlia merckii, was expressed in rice (Oryza sativa L. sp. indica cv. Pusa basmati 1) using Agrobacterium tumefaciens-mediated transformation. Expression levels of Dm-AMP1 ranged from 0.43% to 0.57% of total soluble protein in transgenic plants. It was observed that constitutive expression of Dm-AMP1 suppresses the growth of M. oryzae and R. solani by 84% and 72%, respectively. Transgenic expression of Dm-AMP1 was not accompanied by an induction of pathogenesis-related (PR) gene expression, indicating that the expression of DmAMP1 directly inhibits the pathogen. The results of in vitro, in planta and microscopic analyses suggest that Dm-AMP1 expression has the potential to provide broad-spectrum disease resistance in rice. PMID:18618285

  18. Construction and expression of retroviruses encoding dual drug resistance genes in human umbilical cord blood CD34+ cells

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A series of retroviral vectors encoding human mdr1 gene alone as well as in combination with either human mgmt gene or human mutant Ser31-dhfr gene are engineered. The resultant retroviruses are used to transduce human umbilical cord blood CD34+ cells. It has been shown that expression of dual drug resistance genes in transduced cells confers a broad range of resistance to both kinds of corresponding drugs. These data suggest a rationale for the use of such double chemoresistance gene constructs in an in vivo model in which transduced hematopoietic cells will acquire multiple protection against the cytotoxic side effects of combination chemotherapy and may have future application in chemoprotection of normal tissues, thus killing tumor cells more effectively.

  19. Old yellow enzyme confers resistance of Hansenula polymorpha towards allyl alcohol

    NARCIS (Netherlands)

    Komduur, JA; Leao, AN; Monastyrska, [No Value; Veenhuis, M; Kiel, JAKW; Leão, Adriana N.; Monastyrska, Iryna

    2002-01-01

    In the methylotrophic yeast, Hansenula polymorpha, peroxisomes are formed during growth on methanol as sole carbon and energy source and contain the key enzymes for its metabolism, one of the major enzymes being alcohol oxidase (AO). Upon a shift of these cells to glucose-containing medium, peroxiso

  20. NFkB signaling is important for growth of antiestrogen resistant breast cancer cells

    DEFF Research Database (Denmark)

    Yde, Christina Westmose; Emdal, Kristina Bennet; Guerra, Barbara;

    2012-01-01

    resistant cell growth and a potential target for re-sensitizing resistant cells to endocrine therapy. We used an MCF-7-derived cell model for antiestrogen resistant breast cancer to investigate dependence on NF¿B signaling for antiestrogen resistant cell growth. We found that targeting NF¿B preferentially...... inhibited resistant cell growth. Antiestrogen resistant cells expressed increased p50 and RelB, and displayed increased phosphorylation of p65 at Ser529 and Ser536. Moreover, transcriptional activity of NF¿B after stimulation with tumor necrosis factor a was enhanced in antiestrogen resistant cell lines...... resistant cells increased sensitivity to tamoxifen treatment. Our data provide evidence that NF¿B signaling is enhanced in antiestrogen resistant breast cancer cells and plays an important role for antiestrogen resistant cell growth and for sensitivity to tamoxifen treatment in resistant cells. Our results...

  1. Ectopic expression of ubiquitin-conjugating enzyme gene from wild rice, OgUBC1, confers resistance against UV-B radiation and Botrytis infection in Arabidopsis thaliana

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, En Hee; Pak, Jung Hun; Kim, Mi Jin; Kim, Hye Jeong [Department of Genetic Engineering, Dong-A University, Busan 604-714 (Korea, Republic of); Shin, Sang Hyun [National Crop Experiment Station, Rural Development Administration, Suwon 441-100 (Korea, Republic of); Lee, Jai Heon; Kim, Doh Hoon; Oh, Ju Sung [Department of Genetic Engineering, Dong-A University, Busan 604-714 (Korea, Republic of); Oh, Boung-Jun [BioControl Center, Jeonnam 516-942 (Korea, Republic of); Jung, Ho Won, E-mail: hwjung@dau.ac.kr [Department of Genetic Engineering, Dong-A University, Busan 604-714 (Korea, Republic of); Chung, Young Soo, E-mail: chungys@dau.ac.kr [Department of Genetic Engineering, Dong-A University, Busan 604-714 (Korea, Republic of)

    2012-10-19

    Highlights: Black-Right-Pointing-Pointer We isolated a novel E2 ubiquitin-conjugating enzyme from leaves of wild rice plants. Black-Right-Pointing-Pointer The OgUBC1 was highly expressed in leaves treated with SA and UV-B radiation. Black-Right-Pointing-Pointer The recombinant OgUBC1 has an enzymatic activity of E2 in vitro. Black-Right-Pointing-Pointer The OgUBC1 could protect disruption of plant cells by UV-B radiation. Black-Right-Pointing-Pointer OgUBC1 confers disease resistance and UV-B tolerance in transgenic Arabidopsis plants. -- Abstract: A previously unidentified gene encoding ubiquitin-conjugating enzyme was isolated from leaves of wild rice plant treated with wounding and microbe-associated molecular patterns. The OgUBC1 gene was composed of 148 amino acids and contained a typical active site and 21 ubiquitin thioester intermediate interaction residues and 4 E3 interaction residues. Both exogenous application of salicylic acid and UV-B irradiation triggered expression of OgUBC1 in leaves of wild rice. Recombinant OgUBC1 proteins bound to ubiquitins in vitro, proposing that the protein might act as E2 enzyme in planta. Heterologous expression of the OgUBC1 in Arabidopsis thaliana protected plants from cellular damage caused by an excess of UV-B radiation. A stable expression of chalcone synthase gene was detected in leaves of OgUBC1-expressing Arabidopsis, resulting in producing higher amounts of anthocyanin than those in wild-type Col-0 plants. Additionally, both pathogenesis-related gene1 and 5 were transcribed in the transgenic Arabidopsis in the absence of pathogen infection. The OgUBC1-expressing plants were resistant to the infection of Botrytis cinerea. Taken together, we suggested that the OgUBC1 is involved in ubiquitination process important for cellular response against biotic and abiotic stresses in plants.

  2. Transgenic expression of the rice Xa21 pattern-recognition receptor in banana (Musa sp.) confers resistance to Xanthomonas campestris pv. musacearum.

    Science.gov (United States)

    Tripathi, Jaindra N; Lorenzen, Jim; Bahar, Ofir; Ronald, Pamela; Tripathi, Leena

    2014-08-01

    Banana Xanthomonas wilt (BXW), caused by the bacterium Xanthomonas campestris pv. musacearum (Xcm), is the most devastating disease of banana in east and central Africa. The spread of BXW threatens the livelihood of millions of African farmers who depend on banana for food security and income. There are no commercial chemicals, biocontrol agents or resistant cultivars available to control BXW. Here, we take advantage of the robust resistance conferred by the rice pattern-recognition receptor (PRR), XA21, to the rice pathogen Xanthomonas oryzae pv. oryzae (Xoo). We identified a set of genes required for activation of Xa21-mediated immunity (rax) that were conserved in both Xoo and Xcm. Based on the conservation, we hypothesized that intergeneric transfer of Xa21 would confer resistance to Xcm. We evaluated 25 transgenic lines of the banana cultivar 'Gonja manjaya' (AAB) using a rapid bioassay and 12 transgenic lines in the glasshouse for resistance against Xcm. About 50% of the transgenic lines showed complete resistance to Xcm in both assays. In contrast, all of the nontransgenic control plants showed severe symptoms that progressed to complete wilting. These results indicate that the constitutive expression of the rice Xa21 gene in banana results in enhanced resistance against Xcm. Furthermore, this work demonstrates the feasibility of PRR gene transfer between monocotyledonous species and provides a valuable new tool for controlling the BXW pandemic of banana, a staple food for 100 million people in east Africa.

  3. Identification of yeast genes that confer resistance to chitosan oligosaccharide (COS) using chemogenomics

    OpenAIRE

    Jaime Maria DLA; Lopez-Llorca Luis; Conesa Ana; Lee Anna Y; Proctor Michael; Heisler Lawrence E; Gebbia Marinella; Giaever Guri; Westwood J; Nislow Corey

    2012-01-01

    Background: Chitosan oligosaccharide (COS), a deacetylated derivative of chitin, is an abundant, and renewable natural polymer. COS has higher antimicrobial properties than chitosan and is presumed to act by disrupting/permeabilizing the cell membranes of bacteria, yeast and fungi. COS is relatively non-toxic to mammals. By identifying the molecular and genetic targets of COS, we hope to gain a better understanding of the antifungal mode of action of COS. Results: Three different chemogenomic...

  4. Systematic mutagenesis of genes encoding predicted autotransported proteins of Burkholderia pseudomallei identifies factors mediating virulence in mice, net intracellular replication and a novel protein conferring serum resistance.

    Science.gov (United States)

    Lazar Adler, Natalie R; Stevens, Mark P; Dean, Rachel E; Saint, Richard J; Pankhania, Depesh; Prior, Joann L; Atkins, Timothy P; Kessler, Bianca; Nithichanon, Arnone; Lertmemongkolchai, Ganjana; Galyov, Edouard E

    2015-01-01

    Burkholderia pseudomallei is the causative agent of the severe tropical disease melioidosis, which commonly presents as sepsis. The B. pseudomallei K96243 genome encodes eleven predicted autotransporters, a diverse family of secreted and outer membrane proteins often associated with virulence. In a systematic study of these autotransporters, we constructed insertion mutants in each gene predicted to encode an autotransporter and assessed them for three pathogenesis-associated phenotypes: virulence in the BALB/c intra-peritoneal mouse melioidosis model, net intracellular replication in J774.2 murine macrophage-like cells and survival in 45% (v/v) normal human serum. From the complete repertoire of eleven autotransporter mutants, we identified eight mutants which exhibited an increase in median lethal dose of 1 to 2-log10 compared to the isogenic parent strain (bcaA, boaA, boaB, bpaA, bpaC, bpaE, bpaF and bimA). Four mutants, all demonstrating attenuation for virulence, exhibited reduced net intracellular replication in J774.2 macrophage-like cells (bimA, boaB, bpaC and bpaE). A single mutant (bpaC) was identified that exhibited significantly reduced serum survival compared to wild-type. The bpaC mutant, which demonstrated attenuation for virulence and net intracellular replication, was sensitive to complement-mediated killing via the classical and/or lectin pathway. Serum resistance was rescued by in trans complementation. Subsequently, we expressed recombinant proteins of the passenger domain of four predicted autotransporters representing each of the phenotypic groups identified: those attenuated for virulence (BcaA), those attenuated for virulence and net intracellular replication (BpaE), the BpaC mutant with defects in virulence, net intracellular replication and serum resistance and those displaying wild-type phenotypes (BatA). Only BcaA and BpaE elicited a strong IFN-γ response in a restimulation assay using whole blood from seropositive donors and were

  5. A red and far-red light receptor mutation confers resistance to the herbicide glyphosate.

    Science.gov (United States)

    Sharkhuu, Altanbadralt; Narasimhan, Meena L; Merzaban, Jasmeen S; Bressan, Ray A; Weller, Steve; Gehring, Chris

    2014-06-01

    Glyphosate is a widely applied broad-spectrum systemic herbicide that inhibits competitively the penultimate enzyme 5-enolpyruvylshikimate 3-phosphate synthase (EPSPS) from the shikimate pathway, thereby causing deleterious effects. A glyphosate-resistant Arabidopsis mutant (gre1) was isolated and genetic analyses indicated that a dysfunctional red (R) and far-red (FR) light receptor, phytochrome B (phyB), caused this phenotype. This finding is consistent with increased glyphosate sensitivity and glyphosate-induced shikimate accumulation in low R:FR light, and the induction of genes encoding enzymes of the shikimate pathway in high R:FR light. Expression of the shikimate pathway genes exhibited diurnal oscillation and this oscillation was altered in the phyB mutant. Furthermore, transcript analysis suggested that this diurnal oscillation was not only dependent on phyB but was also due to circadian regulatory mechanisms. Our data offer an explanation of the well documented observation that glyphosate treatment at various times throughout the day, with their specific composition of light quality and intensity, results in different efficiencies of the herbicide.

  6. A red and far-red light receptor mutation confers resistance to the herbicide glyphosate

    KAUST Repository

    Sharkhuu, Altanbadralt

    2014-06-01

    Glyphosate is a widely applied broad-spectrum systemic herbicide that inhibits competitively the penultimate enzyme 5-enolpyruvylshikimate 3-phosphate synthase (EPSPS) from the shikimate pathway, thereby causing deleterious effects. A glyphosate-resistant Arabidopsis mutant (gre1) was isolated and genetic analyses indicated that a dysfunctional red (R) and far-red (FR) light receptor, phytochrome B (phyB), caused this phenotype. This finding is consistent with increased glyphosate sensitivity and glyphosate-induced shikimate accumulation in low R:FR light, and the induction of genes encoding enzymes of the shikimate pathway in high R:FR light. Expression of the shikimate pathway genes exhibited diurnal oscillation and this oscillation was altered in the phyB mutant. Furthermore, transcript analysis suggested that this diurnal oscillation was not only dependent on phyB but was also due to circadian regulatory mechanisms. Our data offer an explanation of the well documented observation that glyphosate treatment at various times throughout the day, with their specific composition of light quality and intensity, results in different efficiencies of the herbicide.

  7. Repurposing of tetracyclines to overcome resistance pathways associated with photochemotherapy in cancer (Conference Presentation)

    Science.gov (United States)

    Liu, Joyce; Huang, Huang-Chiao; Rizvi, Imran; Hasan, Tayyaba

    2016-03-01

    Given the consistently poor prognoses for some of the most difficult-to-treat cancers, rapidly translatable treatment regimens that offer improvements in outcomes are much needed. The repurposing of FDA approved non-cancer drugs presents an opportunity to design clinically feasible, novel combinations of therapies with a mechanistic rationale, to overcome resistance and survival pathways that render many current treatments ineffective. Tetracyclines are a class of antibiotics that demonstrate potential for such repurposing, as they have also been shown by others to affect a wide range of targets in cancer. Notably, the unique structure of tetracyclines allows them to act through both light activated and non-light mediated mechanisms. While light activation of tetracyclines can result in singlet oxygen production, their non-light mediated targets include inhibition of DNA repair enzymes and modulation of hypoxia-inducible markers, among others. With these mechanisms in mind, we seek to elucidate the benefit of including tetracyclines as part of an already promising, mechanistically cooperative photochemotherapy combination for ovarian cancer. In ovarian cancer, the dismal rates of recurrence and survival associated with the aggressive disease further emphasize the need to mechanistically reinforce treatments regimens. Thus, the results will highlight insights into the cooperative effect of repurposed tetracyclines on treatment response and molecular markers, both in vitro and in a challenging mouse model of disseminated ovarian cancer.

  8. Structural Basis for Carbapenem-Hydrolyzing Mechanisms of Carbapenemases Conferring Antibiotic Resistance

    Directory of Open Access Journals (Sweden)

    Jeong Ho Jeon

    2015-04-01

    Full Text Available Carbapenems (imipenem, meropenem, biapenem, ertapenem, and doripenem are β-lactam antimicrobial agents. Because carbapenems have the broadest spectra among all β-lactams and are primarily used to treat infections by multi-resistant Gram-negative bacteria, the emergence and spread of carbapenemases became a major public health concern. Carbapenemases are the most versatile family of β-lactamases that are able to hydrolyze carbapenems and many other β-lactams. According to the dependency of divalent cations for enzyme activation, carbapenemases can be divided into metallo-carbapenemases (zinc-dependent class B and non-metallo-carbapenemases (zinc-independent classes A, C, and D. Many studies have provided various carbapenemase structures. Here we present a comprehensive and systematic review of three-dimensional structures of carbapenemase-carbapenem complexes as well as those of carbapenemases. We update recent studies in understanding the enzymatic mechanism of each class of carbapenemase, and summarize structural insights about regions and residues that are important in acquiring the carbapenemase activity.

  9. Effect of curcumin on multidrug resistance in resistant human gastric carcinoma cell line SGC7901/VCR

    Institute of Scientific and Technical Information of China (English)

    Xiao-qing TANG; Hu BI; Jian-qiang FENG; Jian-guo CAO

    2005-01-01

    Aim: To investigate the reversal effects of curcumin on multidrug resistance (MDR)in a resistant human gastric carcinoma cell line. Methods: The cytotoxic effect of vincristine (VCR) was evaluated by MTT assay. The cell apoptosis induced by VCR was determined by propidium iodide (PI)-stained flow cytometry (FCM) and a morphological assay using acridine orange (AO)/ethidium bromide (EB) dual staining. P-glycoprotein (P-gp) function was demonstrated by the accumulation and efflux of rhodamine123 (Rh123) using FCM. The expression of P-gp and the activation of caspase-3 were measured by FCM using fluorescein isothiocyanate (FITC)-conjugated anti-P-gp and anti-cleaved caspase-3 antibodies, respectively.Results: Curcumin, at concentrations of 5 μmol/L, 10 μmol/L, or 20 μmol/L, had no cytotoxic effect on a parent human gastric carcinoma cell line (SGC7901) or its VCR-resistant variant cell line (SGC7901/VCR). The VCR-IC50 value of the SGC7901/VCR cells was 45 times more than that of the SGC7901cells and the SGC7901/VCR cells showed apoptotic resistance to VCR. SGC7901/VCR cells treated with 5μmol/L, 10 μmol/L, or 20 μmol/L curcumin decreased the IC50 value of VCR and promoted VCR-mediated apoptosis in a dose-dependent manner. Curcumin (10μmol/L) increased Rh 123 accumulation and inhibited the efflux of Rh 123 in S GC7901/VCR cells, but did not change the accumulation and efflux of Rh123 in SGC7901cells. P-gp was overexpressed in SGC7901/VCR cells, whereas it was downregulated after a 24-h treatment with curcumin (10 μmol/L). Resistant cells treated with 1μmol/L VCR alone showed 77% lower levels of caspase-3 activation relative to SGC7901 cells, but the activation of caspase-3 in the resistant cell line increased by 44% when cells were treated with VCR in combination with curcumin.Conclusion: Curcumin can reverse the MDR of the human gastric carcinoma SGC7901/VCR cell line. This might be associated with decreased P-gp function and expression, and the promotion of

  10. FG020326 Sensitized Multidrug Resistant Cancer Cells to Docetaxel-Mediated Apoptosis via Enhancement of Caspases Activation

    Directory of Open Access Journals (Sweden)

    Li-Wu Fu

    2012-05-01

    Full Text Available Apoptotic resistance is the main obstacle for treating cancer patients with chemotherapeutic drugs. Multidrug resistance (MDR is often characterized by the expression of P-glycoprotein (P-gp, a 170-KD ATP-dependent drug efflux protein. Functional P-gp can confer resistance to activate caspase-8 and -3 dependent apoptosis induced by a range of different stimuli, including tumor necrosis and chemotherapeutic drugs such as docetaxel and vincristine. We demonstrated here that comparison of sensitive KB cells, P-gp positive (P-gp+ve KBv200 cells were extremely resistant to apoptosis induced by docetaxel. FG020326, a pharmacological inhibitor of P-gp function, could enhance concentration-dependently the effect of docetaxel on cell apoptosis and sensitize caspase-8, -9 and -3 activation in P-gp overexpressing KBv200 cells, but not in KB cells. Therefore, the enhancement of caspase-8, -9 and -3 activation induced by docetaxel may be one of the key mechanisms of the reversal of P-gp mediated docetaxel resistance by FG020326.

  11. Lung-specific loss of the laminin α3 subunit confers resistance to mechanical injury

    OpenAIRE

    Urich, Daniela; Eisenberg, Jessica L.; Hamill, Kevin J.; Takawira, Desire; Chiarella, Sergio E.; Soberanes, Saul; Gonzalez, Angel; Koentgen, Frank; Manghi, Tomas; Hopkinson, Susan B.; Misharin, Alexander V.; Perlman, Harris; Mutlu, Gokhan M; Budinger, G. R. Scott; Jonathan C.R. Jones

    2011-01-01

    Laminins are heterotrimeric glycoproteins of the extracellular matrix that are secreted by epithelial cells and which are crucial for the normal structure and function of the basement membrane. We have generated a mouse harboring a conditional knockout of α3 laminin (Lama3fl/fl), one of the main laminin subunits in the lung basement membrane. At 60 days after intratracheal treatment of adult Lama3fl/fl mice with an adenovirus encoding Cre recombinase (Ad-Cre), the protein abundance of α3 lami...

  12. Cell fate determination in cisplatin resistance and chemosensitization

    Science.gov (United States)

    Luong, Khanh V.; Wang, Ling; Roberts, Brett J.; Wahl, James K.; Peng, Aimin

    2016-01-01

    Understanding the determination of cell fate choices after cancer treatment will shed new light on cancer resistance. In this study, we quantitatively analyzed the individual cell fate choice in resistant UM-SCC-38 head and neck cancer cells exposed to cisplatin. Our study revealed a highly heterogeneous pattern of cell fate choices in UM-SCC-38 cells, in comparison to that of the control, non-tumorigenic keratinocyte HaCaT cells. In both UM-SCC-38 and HaCaT cell lines, the majority of cell death occurred during the immediate interphase without mitotic entry, whereas significant portions of UM-SCC-38 cells survived the treatment via either checkpoint arrest or checkpoint slippage. Interestingly, checkpoint slippage occurred predominantly in cells treated in late S and G2 phases, and cells in M-phase were hypersensitive to cisplatin. Moreover, although the cisplatin-resistant progression of mitosis exhibited no delay in general, prolonged mitosis was correlated with the induction of cell death in mitosis. The finding thus suggested a combinatorial treatment using cisplatin and an agent that blocks mitotic exit. Consistently, we showed a strong synergy between cisplatin and the proteasome inhibitor Mg132. Finally, targeting the DNA damage checkpoint using inhibitors of ATR, but not ATM, effectively sensitized UM-SCC-38 to cisplatin treatment. Surprisingly, checkpoint targeting eliminated both checkpoint arrest and checkpoint slippage, and augmented the induction of cell death in interphase without mitotic entry. Taken together, our study, by profiling cell fate determination after cisplatin treatment, reveals new insights into chemoresistance and suggests combinatorial strategies that potentially overcome cancer resistance. PMID:26993599

  13. Two different point mutations in ABL gene ATP-binding domain conferring Primary Imatinib resistance in a Chronic Myeloid Leukemia (CML patient: A case report

    Directory of Open Access Journals (Sweden)

    Iqbal Zafar

    2004-01-01

    Full Text Available Imatinib (Gleevec is the effective therapy for BCR-ABL positive CML patients. Point mutations have been detected in ATP-binding domain of ABL gene which disturbs the binding of Gleevec to this target leading to resistance. Detection of mutations is helpful in clinical management of imatinib resistance. We established a very sensitive (ASO PCR to detect mutations in an imatinib-resistant CML patient. Mutations C944T and T1052C were detected which cause complete partial imatinib resistance, respectively. This is the first report of multiple point mutations conferring primary imatinib resistance in same patient at the same time. Understanding the biological reasons of primary imatinib resistance is one of the emerging issues of pharmacogenomics and will be helpful in understanding primary resistance of molecularly-targeted cancer therapies. It will also be of great utilization in clinical management of imatinib resistance. Moreover, this ASO-PCR assay is very effective in detecting mutations related to imatinib resistance.

  14. Conjugative plasmid in Corynebacterium flaccumfaciens subsp. oortii that confers resistance to arsenite, arsenate, and antimony(III)

    Energy Technology Data Exchange (ETDEWEB)

    Hendrick, C.A.; Haskins, W.P.; Vidaver, A.K.

    1984-07-01

    Gene transfer systems for phytopathogenic corynebacteria have not been reported previously. In this paper a conjugative 46-megadalton plasmid (pDG101) found in Corynebacterium flaccumfaciens subsp. oorii CO101 is described that mediates resistance to arsenite, arsenate, and antimony(III). Transfer of the plasmid from CO101 to four other strains from the C. flaccumfaciens group occurred between cells immobilized on nitrocellulose filters or on agar surfaces. Transconjugant strains expressed the same levels of metal resistance as the donor strain and were able to act as donor strains in subsequent matings. The physical presence of the plasmid was detected by agarose gel electrophoresis. Arsenite-sensitive derivatives of the donor and transconjugant strains were obtained after heat treatment; these were cured of pDG101.

  15. Mitomycin resistance in mammalian cells expressing the bacterial mitomycin C resistance protein MCRA

    OpenAIRE

    Belcourt, Michael F.; Penketh, Philip G.; Hodnick, William F.; Johnson, David A.; David H Sherman; Rockwell, Sara; Sartorelli, Alan C.

    1999-01-01

    The mitomycin C-resistance gene, mcrA, of Streptomyces lavendulae produces MCRA, a protein that protects this microorganism from its own antibiotic, the antitumor drug mitomycin C. Expression of the bacterial mcrA gene in mammalian Chinese hamster ovary cells causes profound resistance to mitomycin C and to its structurally related analog porfiromycin under aerobic conditions but produces little change in drug sensitivity under hypoxia. The mitomycins are prodrugs that are enzymatically reduc...

  16. Taxotere resistance in SUIT Taxotere resistance in pancreatic carcinoma cell line SUIT 2 and its sublines

    Institute of Scientific and Technical Information of China (English)

    Bin Liu; Edgar Staren; Takeshi Iwamura; Hubert Appert; John Howard

    2001-01-01

    AIM: To investigate the specific mechanisms of intrinsic and acquired resistance to taxotere (TXT) in pancreatic adenocarcinoma (PAC). METHODS: MTT assay was used to detect the sensitivity of PAC cell line SUIT-2 and its sublines (S-007, S-013, S-020,S-028 and TXT selected SUIT-2 cell line, S2/TXT) to TXT.Mdr1 (P-gp), multidrug resistance associated protein (MRP), lung resistance protein (LRP) and β-tubulin isotype gene expressions were detected by RT-PCR. The functionality of P-gp and MRP was tested using their specific blocker verapamil ( Ver ) and indomethacin ( IMC ),respectively. The transporter activity of P-gp was also confirmed by Rhodamine 123 accumulation assay. RESULTS: S-020 and S2/TXT were found to be significantly resistant to TXT(19 and 9.5-fold to their parental cell line SUIT-2, respectively ). RT-PCR demonstrated strong expression of Mdr1 in these two cell lines, but weaker expression or no expression in other cells lines. MRP and LRP expressions were found in most of these cell lines. The TXT-resistance in S2-020 and S2/TXT could be reversed almost completely by Ver, but not by IMC. Flow cytometry showed that Ver increased the accumulation of Rhodamine-123 in these two cell lines. Compared with S-020 and SUIT-2,the levels of β-tubulin isotype II, III expreesions in S-2/TXTwere increased remarkably. CONCLUSION: The both intrinsic and acquired TXT-related drugresistance in these PAC cell lines is mainly mediated by P-gp, but had no relationship to MRP and LRP expressions.The increases of β-tubulin isotype II, III might be collateral changes that occur when the SUIT-2 cells are treated with TXT.

  17. Tumourigenicity and radiation resistance of mesenchymal stem cells

    DEFF Research Database (Denmark)

    D'Andrea, Filippo Peder; Horsman, Michael Robert; Kassem, Moustapha;

    2012-01-01

    Background. Cancer stem cells are believed to be more radiation resistant than differentiated tumour cells of the same origin. It is not known, however, whether normal nontransformed adult stem cells share the same radioresistance as their cancerous counterpart. Material and methods. Nontumourige......Background. Cancer stem cells are believed to be more radiation resistant than differentiated tumour cells of the same origin. It is not known, however, whether normal nontransformed adult stem cells share the same radioresistance as their cancerous counterpart. Material and methods....... Nontumourigenic (TERT4) and tumourigenic (TRET20) cell lines, from an immortalised mesenchymal stem cell line, were grown in culture prior to irradiation and gene expression analysis. Radiation resistance was measured using a clonogenic assay. Differences in gene expression between the two cell lines, both under...... nontreated and irradiated conditions, were assessed with microarrays (Affymetrix Human Exon 1.0 ST array). The cellular functions affected by the altered gene expressions were assessed through gene pathway mapping (Ingenuity Pathway Analysis). Results. Based on the clonogenic assay the nontumourigenic cell...

  18. A novel P106L mutation in EPSPS and an unknown mechanism(s) act additively to confer resistance to glyphosate in a South African Lolium rigidum population.

    Science.gov (United States)

    Kaundun, Shiv S; Dale, Richard P; Zelaya, Ian A; Dinelli, Giovanni; Marotti, Ilaria; McIndoe, Eddie; Cairns, Andrew

    2011-04-13

    Glyphosate resistance evolution in weeds is a growing problem in world agriculture. Here, we have investigated the mechanism(s) of glyphosate resistance in a Lolium rigidum population (DAG1) from South Africa. Nucleotide sequencing revealed the existence of at least three EPSPS homologues in the L. rigidum genome and identified a novel proline 106 to leucine substitution (P106L) in 52% DAG1 individuals. This mutation conferred a 1.7-fold resistance increase to glyphosate at the whole plant level. Additionally, a 3.1-fold resistance increase, not linked to metabolism or translocation, was estimated between wild-type P106-DAG1 and P106-STDS sensitive plants. Point accepted mutation analysis suggested that other amino acid substitutions at EPSPS position 106 are likely to be found in nature besides the P106/S/A/T/L point mutations reported to date. This study highlights the importance of minor mechanisms acting additively to confer significant levels of resistance to commercial field rates of glyphosate in weed populations subjected to high selection pressure.

  19. P-glycoprotein Mediates Ceritinib Resistance in Anaplastic Lymphoma Kinase-rearranged Non-small Cell Lung Cancer

    Directory of Open Access Journals (Sweden)

    Ryohei Katayama

    2016-01-01

    Full Text Available The anaplastic lymphoma kinase (ALK fusion oncogene is observed in 3%–5% of non-small cell lung cancer (NSCLC. Crizotinib and ceritinib, a next-generation ALK tyrosine kinase inhibitor (TKI active against crizotinib-refractory patients, are clinically available for the treatment of ALK-rearranged NSCLC patients, and multiple next-generation ALK-TKIs are currently under clinical evaluation. These ALK-TKIs exhibit robust clinical activity in ALK-rearranged NSCLC patients; however, the emergence of ALK-TKI resistance restricts the therapeutic effect. To date, various secondary mutations or bypass pathway activation-mediated resistance have been identified, but large parts of the resistance mechanism are yet to be identified. Here, we report the discovery of p-glycoprotein (P-gp/ABCB1 overexpression as a ceritinib resistance mechanism in ALK-rearranged NSCLC patients. P-gp exported ceritinib and its overexpression conferred ceritinib and crizotinib resistance, but not to PF-06463922 or alectinib, which are next-generation ALK inhibitors. Knockdown of ABCB1 or P-gp inhibitors sensitizes the patient-derived cancer cells to ceritinib, in vitro and in vivo. P-gp overexpression was identified in three out of 11 cases with in ALK-rearranged crizotinib or ceritinib resistant NSCLC patients. Our study suggests that alectinib, PF-06463922, or P-gp inhibitor with ceritinib could overcome the ceritinib or crizotinib resistance mediated by P-gp overexpression.

  20. Tcf3 and cell cycle factors contribute to butyrate resistance in colorectal cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Chiaro, Christopher, E-mail: cchiaro@tcmedc.org [Department of Basic Sciences, The Commonwealth Medical College, 525 Pine Street, Scranton, PA 18509 (United States); Lazarova, Darina L., E-mail: dlazarova@tcmedc.org [Department of Basic Sciences, The Commonwealth Medical College, 525 Pine Street, Scranton, PA 18509 (United States); Bordonaro, Michael, E-mail: mbordonaro@tcmedc.org [Department of Basic Sciences, The Commonwealth Medical College, 525 Pine Street, Scranton, PA 18509 (United States)

    2012-11-09

    Highlights: Black-Right-Pointing-Pointer We investigate mechanisms responsible for butyrate resistance in colon cancer cells. Black-Right-Pointing-Pointer Tcf3 modulates butyrate's effects on Wnt activity and cell growth in resistant cells. Black-Right-Pointing-Pointer Tcf3 modulation of butyrate's effects differ by cell context. Black-Right-Pointing-Pointer Cell cycle factors are overexpressed in the resistant cells. Black-Right-Pointing-Pointer Reversal of altered gene expression can enhance the anti-cancer effects of butyrate. -- Abstract: Butyrate, a fermentation product of dietary fiber, inhibits clonal growth in colorectal cancer (CRC) cells dependent upon the fold induction of Wnt activity. We have developed a CRC cell line (HCT-R) that, unlike its parental cell line, HCT-116, does not respond to butyrate exposure with hyperactivation of Wnt signaling and suppressed clonal growth. PCR array analyses revealed Wnt pathway-related genes, the expression of which differs between butyrate-sensitive HCT-116 CRC cells and their butyrate-resistant HCT-R cell counterparts. We identified overexpression of Tcf3 as being partially responsible for the butyrate-resistant phenotype, as this DNA-binding protein suppresses the hyperinduction of Wnt activity by butyrate. Consequently, Tcf3 knockdown in HCT-R cells restores their sensitivity to the effects of butyrate on Wnt activity and clonal cell growth. Interestingly, the effects of overexpressed Tcf3 differ between HCT-116 and HCT-R cells; thus, in HCT-116 cells Tcf3 suppresses proliferation without rendering the cells resistant to butyrate. In HCT-R cells, however, the overexpression of Tcf3 inhibits Wnt activity, and the cells are still able to proliferate due to the higher expression levels of cell cycle factors, particularly those driving the G{sub 1} to S transition. Knowledge of the molecular mechanisms determining the variable sensitivity of CRC cells to butyrate may assist in developing approaches that

  1. Recent Advances in Electrical Resistance Preheating of Aluminum Reduction Cells

    Science.gov (United States)

    Ali, Mohamed Mahmoud; Kvande, Halvor

    2016-06-01

    ABSTRACT There are two mainpreheating methods that are used nowadays for aluminum reduction cells. One is based on electrical resistance preheating with a thin bed of small coke and/or graphite particles between the anodes and the cathode carbon blocks. The other is flame preheating, where two or more gas or oil burners are used. Electrical resistance preheating is the oldest method, but is still frequently used by different aluminum producers. Many improvements have been made to this method by different companies over the last decade. In this paper, important points pertaining to the preparation and preheating of these cells, as well as measurements made during the preheating process and evaluation of the performance of the preheating, are illustrated. The preheating times of these cells were found to be between 36 h and 96 h for cell currents between 176 kA and 406 kA, while the resistance bed thickness was between 13 mm and 60 mm. The average cathode surface temperature at the end of the preheating was usually between 800°C and 950°C. The effect of the preheating methods on cell life is unclear and no quantifiable conclusions can be drawn. Some works carried out in the mathematical modeling area are also discussed. It is concluded that there is a need for more studies with real situations for preheated cells on the basis of actual measurements. The expected development in electrical resistance preheating of aluminum reduction cells is also summarized.

  2. Prokaryotic arsenate reductase enhances arsenate resistance in Mammalian cells.

    Science.gov (United States)

    Wu, Dan; Tao, Xuanyu; Wu, Gaofeng; Li, Xiangkai; Liu, Pu

    2014-01-01

    Arsenic is a well-known heavy metal toxicant in the environment. Bioremediation of heavy metals has been proposed as a low-cost and eco-friendly method. This article described some of recent patents on transgenic plants with enhanced heavy metal resistance. Further, to test whether genetic modification of mammalian cells could render higher arsenic resistance, a prokaryotic arsenic reductase gene arsC was transfected into human liver cancer cell HepG2. In the stably transfected cells, the expression level of arsC gene was determined by quantitative real-time PCR. Results showed that arsC was expressed in HepG2 cells and the expression was upregulated by 3 folds upon arsenate induction. To further test whether arsC has function in HepG2 cells, the viability of HepG2-pCI-ArsC cells exposed to arsenite or arsenate was compared to that of HepG2-pCI cells without arsC gene. The results indicated that arsC increased the viability of HepG2 cells by 25% in arsenate, but not in arsenite. And the test of reducing ability of stably transfected cells revealed that the concentration of accumulated trivalent arsenic increased by 25% in HepG2-pCI-ArsC cells. To determine the intracellular localization of ArsC, a fusion vector with fluorescent marker pEGFP-N1-ArsC was constructed and transfected into.HepG2. Laser confocal microscopy showed that EGFP-ArsC fusion protein was distributed throughout the cells. Taken together, these results demonstrated that prokaryotic arsenic resistant gene arsC integrated successfully into HepG2 genome and enhanced arsenate resistance of HepG2, which brought new insights of arsenic detoxification in mammalian cells.

  3. Breast cancer resistance protein is localized at the plasma membrane in mitoxantrone- and topotecan-resistant cell lines

    NARCIS (Netherlands)

    Scheffer, GL; Maliepaard, M; Pijnenborg, ACLM; van Gastelen, MA; Schroeijers, AB; Allen, JD; Ross, DD; van der Valk, P; Dalton, WS; Schellens, JHM; Scheper, RJ; de Jong, MC

    2000-01-01

    Tumor cells may display a multidrug resistant phenotype by overexpression of ATP-binding cassette transporters such as multidrug resistance (,MDR1) P-glycoprotein, multidrug resistance protein 1 (MRP1), and breast cancer resistance protein (BCRP). The presence of BCRP has thus far been reported sole

  4. Drug Resistance and Cancer Stem Cells

    OpenAIRE

    Fonseca, João Pedro Couto

    2012-01-01

    O cancro do pulmão é a principal causa de morte por cancro a nível mundial. Apesar do crescente conhecimento sobre os mecanismos subjacentes ao processo tumorigénico não se tem observado alteração significativa na sobrevivência dos pacientes. É, por isso, urgente encontrar novas estratégias terapêuticas que visem superar a resistência, tanto intrínseca como extrínseca, observada com a quimioterapia corrente. Os tumores são caracterizados pela sua heterogeneidade celular, devido à coexistên...

  5. Synergistic and compensatory effects of two point mutations conferring target-site resistance to fipronil in the insect GABA receptor RDL.

    Science.gov (United States)

    Zhang, Yixi; Meng, Xiangkun; Yang, Yuanxue; Li, Hong; Wang, Xin; Yang, Baojun; Zhang, Jianhua; Li, Chunrui; Millar, Neil S; Liu, Zewen

    2016-01-01

    Insecticide resistance can arise from a variety of mechanisms, including changes to the target site, but is often associated with substantial fitness costs to insects. Here we describe two resistance-associated target-site mutations that have synergistic and compensatory effects that combine to produce high and persistent levels of resistance to fipronil, an insecticide targeting on γ-aminobytyric acid (GABA) receptors. In Nilaparvata lugens, a major pest of rice crops in many parts of Asia, we have identified a single point mutation (A302S) in the GABA receptor RDL that has been identified previously in other species and which confers low levels of resistance to fipronil (23-fold) in N. lugans. In addition, we have identified a second resistance-associated RDL mutation (R300Q) that, in combination with A302S, is associated with much higher levels of resistance (237-fold). The R300Q mutation has not been detected in the absence of A302S in either laboratory-selected or field populations, presumably due to the high fitness cost associated with this mutation. Significantly, it appears that the A302S mutation is able to compensate for deleterious effects of R300Q mutation on fitness cost. These findings identify a novel resistance mechanism and may have important implications for the spread of insecticide resistance. PMID:27557781

  6. MCF7/LCC9: an antiestrogen-resistant MCF-7 variant in which acquired resistance to the steroidal antiestrogen ICI 182,780 confers an early cross-resistance to the nonsteroidal antiestrogen tamoxifen

    DEFF Research Database (Denmark)

    Brünner, N; Boysen, B; Jirus, S;

    1997-01-01

    growth of MCF7/LCC9 tumors is not affected by treatment with ICI 182,780. Although there is some evidence of tamoxifen stimulation of tumor growth, this did not reach statistical significance. If this pattern of cross-resistance occurs in some breast cancer patients, administering triphenylethylene......Acquired resistance to antiestrogens is a major problem in the clinical management of initially endocrine responsive metastatic breast cancer. We have shown previously that estrogen-independent and -responsive MCF7/LCC1 human breast cancer cells selected for resistance to the triphenylethylene...

  7. NALP3 inflammasome up-regulation and CASP1 cleavage of the glucocorticoid receptor causes glucocorticoid resistance in leukemia cells

    Science.gov (United States)

    Paugh, Steven W.; Bonten, Erik J.; Savic, Daniel; Ramsey, Laura B.; Thierfelder, William E.; Gurung, Prajwal; Malireddi, R. K. Subbarao; Actis, Marcelo; Mayasundari, Anand; Min, Jaeki; Coss, David R.; Laudermilk, Lucas T.; Panetta, John C.; McCorkle, J. Robert; Fan, Yiping; Crews, Kristine R.; Stocco, Gabriele; Wilkinson, Mark R.; Ferreira, Antonio M.; Cheng, Cheng; Yang, Wenjian; Karol, Seth E.; Fernandez, Christian A.; Diouf, Barthelemy; Smith, Colton; Hicks, J. Kevin; Zanut, Alessandra; Giordanengo, Audrey; Crona, Daniel; Bianchi, Joy J.; Holmfeldt, Linda; Mullighan, Charles G.; den Boer, Monique L.; Pieters, Rob; Jeha, Sima; Dunwell, Thomas L.; Latif, Farida; Bhojwani, Deepa; Carroll, William L.; Pui, Ching-Hon; Myers, Richard M.; Guy, R. Kiplin; Kanneganti, Thirumala-Devi; Relling, Mary V.; Evans, William E.

    2015-01-01

    Glucocorticoids are universally used in the treatment of acute lymphoblastic leukemia (ALL), and leukemia cell resistant to glucocorticoids confers a poor prognosis. To elucidate mechanisms of glucocorticoid resistance, we determined the sensitivity to prednisolone of primary leukemia cells from 444 newly diagnosed ALL patients, revealing significantly higher expression of caspase 1 (CASP1) and its activator NLRP3 in glucocorticoid resistant leukemia cells, due to significantly lower somatic methylation of CASP1 and NLRP3 promoters. Over-expression of CASP1 resulted in cleavage of the glucocorticoid receptor, diminished glucocorticoid-induced transcriptional response and increased glucocorticoid resistance. Knockdown or inhibition of CASP1 significantly increased glucocorticoid receptor levels and mitigated glucocorticoid resistance in CASP1 overexpressing ALL. Our findings establish a new mechanism by which the NLRP3/CASP1 inflammasome modulates cellular levels of the glucocorticoid receptor and diminishes cell sensitivity to glucocorticoids. The broad impact on glucocorticoid transcriptional response suggests this mechanism could also modify glucocorticoid effects in other diseases. PMID:25938942

  8. Properties of resistant cells generated from lung cancer cell lines treated with EGFR inhibitors

    International Nuclear Information System (INIS)

    Epidermal growth factor receptor (EGFR) signaling plays an important role in non-small cell lung cancer (NSCLC) and therapeutics targeted against EGFR have been effective in treating a subset of patients bearing somatic EFGR mutations. However, the cancer eventually progresses during treatment with EGFR inhibitors, even in the patients who respond to these drugs initially. Recent studies have identified that the acquisition of resistance in approximately 50% of cases is due to generation of a secondary mutation (T790M) in the EGFR kinase domain. In about 20% of the cases, resistance is associated with the amplification of MET kinase. In the remaining 30-40% of the cases, the mechanism underpinning the therapeutic resistance is unknown. An erlotinib resistant subline (H1650-ER1) was generated upon continuous exposure of NSCLC cell line NCI-H1650 to erlotinib. Cancer stem cell like traits including expression of stem cell markers, enhanced ability to self-renew and differentiate, and increased tumorigenicity in vitro were assessed in erlotinib resistant H1650-ER1 cells. The erlotinib resistant subline contained a population of cells with properties similar to cancer stem cells. These cells were found to be less sensitive towards erlotinib treatment as measured by cell proliferation and generation of tumor spheres in the presence of erlotinib. Our findings suggest that in cases of NSCLC accompanied by mutant EGFR, treatment targeting inhibition of EGFR kinase activity in differentiated cancer cells may generate a population of cancer cells with stem cell properties

  9. Population distribution of Beta-lactamase conferring resistance to third-generation cephalosporins in human clinical Enterobacteriaceae in the Netherlands.

    Directory of Open Access Journals (Sweden)

    Guido M Voets

    Full Text Available There is a global increase in infections caused by Enterobacteriaceae with plasmid-borne β-lactamases that confer resistance to third-generation cephalosporins. The epidemiology of these bacteria is not well understood, and was, therefore, investigated in a selection of 636 clinical Enterobacteriaceae with a minimal inhibitory concentration >1 mg/L for ceftazidime/ceftriaxone from a national survey (75% E. coli, 11% E. cloacae, 11% K. pneumoniae, 2% K. oxytoca, 2% P. mirabilis. Isolates were investigated for extended-spectrum β-lactamases (ESBLs and ampC genes using microarray, PCR, gene sequencing and molecular straintyping (Diversilab and multi-locus sequence typing (MLST. ESBL genes were demonstrated in 512 isolates (81%; of which 446 (87% belonged to the CTX-M family. Among 314 randomly selected and sequenced isolates, bla(CTX-M-15 was most prevalent (n = 124, 39%, followed by bla(CTX-M-1 (n = 47, 15%, bla(CTX-M-14 (n = 15, 5%, bla(SHV-12 (n = 24, 8% and bla(TEM-52 (n = 13, 4%. Among 181 isolates with MIC ≥16 mg/L for cefoxitin plasmid encoded AmpCs were detected in 32 and 27 were of the CMY-2 group. Among 102 E. coli isolates with MIC ≥16 mg/L for cefoxitin ampC promoter mutations were identified in 29 (28%. Based on Diversilab genotyping of 608 isolates (similarity cut-off >98% discriminatory indices of bacteria with ESBL and/or ampC genes were 0.994, 0.985 and 0.994 for E. coli, K. pneumoniae and E. cloacae, respectively. Based on similarity cut-off >95% two large clusters of E. coli were apparent (of 43 and 30 isolates and 21 of 21 that were typed by belonged to ST131 of which 13 contained bla(CTX-M-15. Our findings demonstrate that bla(CTX-M-15 is the most prevalent ESBL and we report a larger than previously reported prevalence of ampC genes among Enterobacteriaceae responsible for resistance to third-generation cephalosporins.

  10. Nanodrug Delivery in Reversing Multidrug Resistance in Cancer Cells

    Directory of Open Access Journals (Sweden)

    Sonali eKapse-Mistry

    2014-07-01

    Full Text Available Different mechanisms in cancer cells become resistant to one or more chemotherapeutics is known as multidrug resistance(MDR which hinders chemotherapy efficacy. Potential factors for MDR includes enhanced drug detoxification, decreased drug uptake, increased intracellular nucleophiles levels, enhanced repair of drug induced DNA damage, overexpression of drug transporter such as P-glycoprotein(P-gp, multidrug resistance-associated proteins(MRP1, MRP2 and breast cancer resistance protein(BCRP. Currently nanoassemblies such as polymeric/solid lipid/inorganic/metal nanoparticles, quantum dots, dendrimers, liposomes, micelles has emerged as an innovative, effective and promising platforms for treatment of drug resistant cancer cells. Nanocarriers have potential to improve drug therapeutic index, ability for multifunctionality, divert ABC-transporter mediated drug efflux mechanism and selective targeting to tumor cells, cancer stem cells, tumor initiating cells or cancer microenvironment. Selective nanocarrier targeting to tumor overcomes dose-limiting side effects, lack of selectivity, tissue toxicity, limited drug access to tumor tissues, high drug doses and emergence of multiple drug resistance with conventional or combination chemotherapy. Current review highlights various nanodrug delivery systems to overcome mechanism of MDR by neutralizing, evading or exploiting the drug efflux pumps and those independent of drug efflux pump mechanism by silencing Bcl-2 and HIF1 gene expressions by siRNA and miRNA, modulating ceramide levels and targeting NF-B. Theragnostics combining a cytotoxic agent, targeting moiety, chemosensitizing agent and diagnostic imaging aid are highlighted as effective and innovative systems for tumor localization and overcoming MDR. Physical approaches such as combination of drug with thermal/ultrasound/photodynamic therapies to overcome MDR are focused. The review focuses on newer drug delivery systems developed to overcome

  11. Bmi-1 confers adaptive radioresistance to KYSE-150R esophageal carcinoma cells

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Guanyu [Department of General Surgery, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou (China); Liu, Luying [Department of Radiotherapy, Zhejiang Cancer Hospital, Hangzhou (China); Sharma, Sherven [David Geffen School of Medicine at UCLA, and the Department of Veterans Affairs, Los Angeles, CA (United States); Liu, Hai; Yang, Weifang; Sun, Xiaonan [Department of Radiotherapy, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou (China); Dong, Qinghua, E-mail: dongqinghua@zju.edu.cn [Biomedical Research Center, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou (China)

    2012-08-24

    Highlights: Black-Right-Pointing-Pointer Adaptive radioresistant KYSE-150R cells expressed high level of Bmi-1. Black-Right-Pointing-Pointer Bmi-1 depletion sensitized KYSE-150R cells to RT. Black-Right-Pointing-Pointer Bmi-1 depletion increased the generation of ROS in KYSE-150R cells exposed to radiation. Black-Right-Pointing-Pointer Bmi-1 depletion impaired DNA repair capacities in KYSE-150R cells exposed to radiation. -- Abstract: Radiotherapy (RT) is a major modality of cancer treatment. However, tumors often acquire radioresistance, which causes RT to fail. The exact mechanisms by which tumor cells subjected to fractionated irradiation (FIR) develop an adaptive radioresistance are largely unknown. Using the radioresistant KYSE-150R esophageal squamous cell carcinoma (ESCC) model, which was derived from KYSE-150 parental cells using FIR, the role of Bmi-1 in mediating the radioadaptive response of ESCC cells to RT was investigated. The results showed that the level of Bmi-1 expression was significantly higher in KYSE-150R cells than in the KYSE-150 parental cells. Bmi-1 depletion sensitized the KYSE-150R cells to RT mainly through the induction of apoptosis, partly through the induction of senescence. A clonogenic cell survival assay showed that Bmi-1 depletion significantly decreased the radiation survival fraction in KYSE-150R cells. Furthermore, Bmi-1 depletion increased the generation of reactive oxygen species (ROS) and the expression of oxidase genes (Lpo, Noxo1 and Alox15) in KYSE-150R cells exposed to irradiation. DNA repair capacities assessed by {gamma}-H2AX foci formation were also impaired in the Bmi-1 down-regulated KYSE-150R cells. These results suggest that Bmi-1 plays an important role in tumor radioadaptive resistance under FIR and may be a potent molecular target for enhancing the efficacy of fractionated RT.

  12. Y-box-binding protein-1 (YB-1) promotes cell proliferation, adhesion and drug resistance in diffuse large B-cell lymphoma.

    Science.gov (United States)

    Miao, Xiaobing; Wu, Yaxun; Wang, Yuchan; Zhu, Xinghua; Yin, Haibing; He, Yunhua; Li, Chunsun; Liu, Yushan; Lu, Xiaoyun; Chen, Yali; Shen, Rong; Xu, Xiaohong; He, Song

    2016-08-15

    YB-1 is a multifunctional protein, which has been shown to correlate with resistance to treatment of various tumor types. This study investigated the expression and biologic function of YB-1 in diffuse large B-cell lymphoma (DLBCL). Immunohistochemical analysis showed that the expression statuses of YB-1 and pYB-1(S102) were reversely correlated with the clinical outcomes of DLBCL patients. In addition, we found that YB-1 could promote the proliferation of DLBCL cells by accelerating the G1/S transition. Ectopic expression of YB-1 could markedly increase the expression of cell cycle regulators cyclin D1 and cyclin E. Furthermore, we found that adhesion of DLBCL cells to fibronectin (FN) could increase YB-1 phosphorylation at Ser102 and pYB-1(S102) nuclear translocation. In addition, overexpression of YB-1 could increase the adhesion of DLBCL cells to FN. Intriguingly, we found that YB-1 overexpression could confer drug resistance through cell-adhesion dependent and independent mechanisms in DLBCL. Silencing of YB-1 could sensitize DLBCL cells to mitoxantrone and overcome cell adhesion-mediated drug resistance (CAM-DR) phenotype in an AKT-dependent manner. PMID:27397581

  13. The hippo pathway effector YAP regulates motility, invasion, and castration-resistant growth of prostate cancer cells.

    Science.gov (United States)

    Zhang, Lin; Yang, Shuping; Chen, Xingcheng; Stauffer, Seth; Yu, Fang; Lele, Subodh M; Fu, Kai; Datta, Kaustubh; Palermo, Nicholas; Chen, Yuanhong; Dong, Jixin

    2015-04-01

    Yes-associated protein (YAP) is an effector of the Hippo tumor suppressor pathway. The functional significance of YAP in prostate cancer has remained elusive. In this study, we first show that enhanced expression of YAP is able to transform immortalized prostate epithelial cells and promote migration and invasion in both immortalized and cancerous prostate cells. We found that YAP mRNA was upregulated in androgen-insensitive prostate cancer cells (LNCaP-C81 and LNCaP-C4-2 cells) compared to the level in androgen-sensitive LNCaP cells. Importantly, ectopic expression of YAP activated androgen receptor signaling and was sufficient to promote LNCaP cells from an androgen-sensitive state to an androgen-insensitive state in vitro, and YAP conferred castration resistance in vivo. Accordingly, YAP knockdown greatly reduced the rates of migration and invasion of LNCaP-C4-2 cells and under androgen deprivation conditions largely blocked cell division in LNCaP-C4-2 cells. Mechanistically, we found that extracellular signal-regulated kinase-ribosomal s6 kinase signaling was downstream of YAP for cell survival, migration, and invasion in androgen-insensitive cells. Finally, immunohistochemistry showed significant upregulation and hyperactivation of YAP in castration-resistant prostate tumors compared to their levels in hormone-responsive prostate tumors. Together, our results identify YAP to be a novel regulator in prostate cancer cell motility, invasion, and castration-resistant growth and as a potential therapeutic target for metastatic castration-resistant prostate cancer (CRPC). PMID:25645929

  14. Leukemia stem cells in drug resistance and metastasis

    Institute of Scientific and Technical Information of China (English)

    DENG Chao-hua; ZHANG Qiu-ping

    2010-01-01

    Objective To review the central role of leukemia stem cells (LSCs) in drug resistance and metastasis, aiming to provide key insights into leukemogenic pathology and developing novel therapeutic strategies against the relapse of leukemia.Data sources The data used in this review were obtained mainly from the studies reported in PubMed using the key terms "tumor-initiating cells", "leukemia stem cells", "drug resistance" and "metastasis".Study selection Relevant articles on studies of leukemia stem cells were selected.Results Increasing numbers of studies have suggested the importance of cancer stem cells (CSCs) in the initiation and maintenance of cancer, especially in leukemia. This review has summarized the origin, characteristics, isolation and identification of LSCs. It highlights the crucial role of LSCs in drug resistance and metastasis of leukemia by illustrating possible mechanisms and aims to provide novel therapeutic strategies for LSCs-targeted treatment.Conclusion LSCs play a crucial role in drug resistance and metastasis of leukemia and new promising LSCs-targeted therapies warrant investigation in both experimental models and clinical practice.

  15. Listeria monocytogenes is resistant to lysozyme through the regulation, not the acquisition, of cell wall-modifying enzymes.

    Science.gov (United States)

    Burke, Thomas P; Loukitcheva, Anastasia; Zemansky, Jason; Wheeler, Richard; Boneca, Ivo G; Portnoy, Daniel A

    2014-11-01

    Listeria monocytogenes is a Gram-positive facultative intracellular pathogen that is highly resistant to lysozyme, a ubiquitous enzyme of the innate immune system that degrades cell wall peptidoglycan. Two peptidoglycan-modifying enzymes, PgdA and OatA, confer lysozyme resistance on L. monocytogenes; however, these enzymes are also conserved among lysozyme-sensitive nonpathogens. We sought to identify additional factors responsible for lysozyme resistance in L. monocytogenes. A forward genetic screen for lysozyme-sensitive mutants led to the identification of 174 transposon insertion mutations that mapped to 13 individual genes. Four mutants were killed exclusively by lysozyme and not other cell wall-targeting molecules, including the peptidoglycan deacetylase encoded by pgdA, the putative carboxypeptidase encoded by pbpX, the orphan response regulator encoded by degU, and the highly abundant noncoding RNA encoded by rli31. Both degU and rli31 mutants had reduced expression of pbpX and pgdA, yet DegU and Rli31 did not regulate each other. Since pbpX and pgdA are also present in lysozyme-sensitive bacteria, this suggested that the acquisition of novel enzymes was not responsible for lysozyme resistance, but rather, the regulation of conserved enzymes by DegU and Rli31 conferred high lysozyme resistance. Each lysozyme-sensitive mutant exhibited attenuated virulence in mice, and a time course of infection revealed that the most lysozyme-sensitive strain was killed within 30 min of intravenous infection, a phenotype that was recapitulated in purified blood. Collectively, these data indicate that the genes required for lysozyme resistance are highly upregulated determinants of L. monocytogenes pathogenesis that are required for avoiding the enzymatic activity of lysozyme in the blood.

  16. Hesperidin as a preventive resistance agent in MCF-7 breast cancer cells line resistance to doxorubicin

    Institute of Scientific and Technical Information of China (English)

    Rifki Febriansah; Dyaningtyas Dewi PP; Sarmoko; Nunuk Aries Nurulita; Edy Meiyanto; Agung Endro Nugroho

    2014-01-01

    Objective:To evaluate of hesperidin to overcome resistance of doxorubicin in MCF-7 resistant doxorubicin cells (MCF-7/Dox) in cytotoxicity apoptosis and P-glycoprotein (Pgp) expression in combination with doxorubicin. Methods:The cytotoxic properties, 50%inhibition concentration (IC50) and its combination with doxorubicin in MCF-7 cell lines resistant to doxorubicin (MCF-7/Dox) cells were determined using MTT assay. Apoptosis induction was examined by double staining assay using ethidium bromide-acridine orange. Immunocytochemistry assay was performed to determine the level and localization of Pgp. Results: Single treatment of hesperidin showed cytotoxic activity on MCF-7/Dox cells with IC50 value of 11 µmol/L. Thus, combination treatment from hesperidin and doxorubicin showed addictive and antagonist effect (CI>1.0). Hesperidin did not increase the apoptotic induction, but decreased the Pgp expressions level when combined with doxorubicin in low concentration. Conclusions: Hesperidin has cytotoxic effect on MCF-7/Dox cells with IC50 of 11 µmol/L. Hesperidin did not increased the apoptotic induction combined with doxorubicin. Co-chemotherapy application of doxorubicin and hesperidin on MCF-7/Dox cells showed synergism effect through inhibition of Pgp expression.

  17. Glioblastoma stem cells resistant to temozolomide-induced autophagy

    Institute of Scientific and Technical Information of China (English)

    FU Jun; LIU Zhi-gang; LIU Xiao-mei; CHEN Fu-rong; SHI Hong-liu; PANG Jesse Chung-sean; NG Ho-keung; CHEN Zhong-ping

    2009-01-01

    Background Recent studies have demonstrated the existence of a small fraction of cells with features of primitive neural progenitor cells and tumor-initiating function in brain tumors. These cells might represent primary therapeutic target for complete eradication of the tumors. This study aimed to determine the resistant phenotype of glioblastoma stem cells (GSCs) to temozolomide (TMZ) and to explore the possible molecular mechanisms underlying TMZ resistance.Methods Freshly resected glioblastoma specimen was collected and magnetic isolation of GSCs was carded out using the Miltenyi Biotec CD133 Celt isolation kit. The cytotoxic effect of TMZ on CD133+ and CD133- glioblastoma cells was determined by using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Autophagy-related proteins (Beclin-1, LC3 and Atg5) and cleaved caspase-3 (p17) were analyzed by Westem blotting. Immunofluorescent staining was used to detect Atg5, glial fibrillary acidic protein (GFAP) and CD133 expression in glioblastoma cells. Statistical analysis was carried out using SPSS 10.0 software. For all tests, the level of statistical significance was set at P <0.05.Results CD133+ glioblastoma cells exhibited neurosphere-like growth in vitro and high expression of CD133 stem cell marker. The growth-inhibiting rate in CD133- glioblastoma cells treated with 5 or 50 pmol/L TMZ was significantly higher than that in CD133+ glioblastoma cells ((14.36±3.75)% vs (2.54±1.36)% or (25.95±5.25)% vs (2.72±1.84)%, respectively, P <0.05). Atg5, LC3-ll and Beclin-1 levels were significantly lower in CD133+ glioblastoma cells than those in autologous CD133- cells after TMZ treatment (P <0.05). Caspase-3 was mildly activated only in CD133- glioblastoma cells after exposure to TMZ (P <0.05). Immunofluorescent staining revealed elevated expression of Atg5 in GFAP* cells following TMZ treatment.Conclusions The GSCs display strong capability of tumor's resistance to TMZ. This resistance is

  18. Cytotoxicity of the sesquiterpene lactones neoambrosin and damsin from Ambrosia maritima against multidrug-resistant cancer cells

    Directory of Open Access Journals (Sweden)

    Mohamed eSaeed

    2015-11-01

    Full Text Available Multidrug resistance (MDR is a prevailing phenomenon leading to chemotherapy treatment failure in cancer patients. In the current study two known cytotoxic pseudoguaianolide sesquiterpene lactones; neombrosin (1 and damsin (2 that circumvent MDR were identified. The two cytotoxic compounds were isolated using column chromatography, characterized using 1D and 2D NMR, MS and compared with literature values. The isolated compounds were investigated for their cytotoxic potential using resazurin assays and thereafter confirmed with immunoblotting and in silico studies. MDR cells overexpressing ABC transporters (P-glycoprotein, BCRP, ABCB5 did not confer cross-resistance towards neoambrosin (1 and damsin (2, indicating that these compounds are not appropriate substrates for any of the three ABC transporters analyzed. Resistance mechanisms investigated also included; the loss of the functions of the tumor suppressor TP53 and the mutated epidermal growth factor receptor (EGFR. The HCT116 p53−/− cells were sensitive to 1 but resistant to 2. It was interesting to note that resistant cells transfected with oncogenic ΔEGFR exhibited hypersensitivity (collateral sensitivity towards neoambrosin (1 and damsin (2 (degrees of resistances were 0.18 and 0.15 for (1 and (2, respectively. Immunoblotting and in silico analyses revealed that 1 and 2 silenced c-Src kinase activity. It was hypothesized that inhibition of c-Src kinase activity may explain collateral sensitivity in EGFR-transfected cells. In conclusion, the significant cytotoxicity of 1 and 2 against different drug-resistant tumor cell lines indicate that they may be promising candidates to treat refractory tumors.

  19. Crystalline silicon solar cells with high resistivity emitter

    Science.gov (United States)

    Panek, P.; Drabczyk, K.; Zięba, P.

    2009-06-01

    The paper presents a part of research targeted at the modification of crystalline silicon solar cell production using screen-printing technology. The proposed process is based on diffusion from POCl3 resulting in emitter with a sheet resistance on the level of 70 Ω/□ and then, shaped by high temperature passivation treatment. The study was focused on a shallow emitter of high resistivity and on its influence on output electrical parameters of a solar cell. Secondary ion mass spectrometry (SIMS) has been employed for appropriate distinguishing the total donor doped profile. The solar cell parameters were characterized by current-voltage characteristics and spectral response (SR) methods. Some aspects playing a role in suitable manufacturing process were discussed. The situation in a photovoltaic industry with emphasis on silicon supply and current prices of solar cells, modules and photovoltaic (PV) systems are described. The economic and quantitative estimation of the PV world market is shortly discussed.

  20. Development of simplified process for environmentally resistant cells. Final report

    Energy Technology Data Exchange (ETDEWEB)

    King, W.J.

    1980-12-01

    A program to develop a simple, foolproof, all-vacuum solar cell manufacturing process which can be completely automated and which results in medium efficiency cells which are inherently environmentally resistant is described. All components of the completed cells are integrated into a monolithic structure with no material interfaces. The exposed materials (Si, Al/sub 2/O/sub 3/, Al, Ni) are all resistant to atmospheric attack and the junction, per se, is passivated to prevent long term degradation. Such cells are intended to be incorporated into a simple module consisting basically of a press-formed metallic superstructure with a separated glass cover for missile, etc., protection. A 5 cm x 5 cm test cell configuration was designed in which the various efficiency loss factors were adjusted to yield a 10% AMI cell. Each of the cell elements was individually optimized for combination with the others. The basic cell consists of alloyed front (Al) and back (Ag plus Ni) contacts, a multi-purpose (AR, hermetic seal, implantation oxide) front surface coating of Al/sub 2/O/sub 3/, and an implanted front junction. Implantation damage annealing and contact alloying are carried out in a simple one step thermal treatment at 870/sup 0/C using a resistance heated furnace in vacuum. The use of non-analyzed and semi-analyzed beams for fabricating these cells was developed by KCI. A final lot of 50 cells made using the semi-analyzed beam method had an average efficiency of 10.4% at AMI (28 +- 1/sup 0/C). An economic analysis predicts a manufacturing cost of $.45/peak-watt for these cells using a one machine automatic method.

  1. Binding and uptake of diphtheria toxin by toxin-resistant Chinese hamster ovary and mouse cells.

    OpenAIRE

    Didsbury, J R; Moehring, J M; Moehring, T. J.

    1983-01-01

    We investigated two phenotypically distinct types of diphtheria toxin-resistant mutants of Chinese hamster cells and compared their resistance with that of naturally resistant mouse cells. All are resistant due to a defect in the process of internalization and delivery of toxin to its target in the cytosol, elongation factor 2. By cell hybridization studies, analysis of cross-resistance, and determination of specific binding sites for 125I-labeled diphtheria toxin, we showed that these cell s...

  2. Anthracycline resistance mediated by reductive metabolism in cancer cells: The role of aldo-keto reductase 1C3

    Energy Technology Data Exchange (ETDEWEB)

    Hofman, Jakub; Malcekova, Beata; Skarka, Adam; Novotna, Eva; Wsol, Vladimir, E-mail: wsol@faf.cuni.cz

    2014-08-01

    after anthracycline exposure was investigated in cancer cells. • AKR1C3 confers resistance of cancer cells to daunorubicin and idarubicin. • AKR1C3 can be induced by the exposure to anthracyclines in some cell lines.

  3. Vaccination with Leishmania histone H1-pulsed dendritic cells confers protection in murine visceral leishmaniasis.

    Science.gov (United States)

    Agallou, Maria; Smirlis, Despina; Soteriadou, Ketty P; Karagouni, Evdokia

    2012-07-20

    Visceral leishmaniasis is the most severe form of leishmaniases affecting millions of people worldwide often resulting in death despite optimal therapy. Thus, there is an urgent need for the development of effective anti-infective vaccine(s). In the present study, we evaluated the prophylactic value of bone marrow-derived dendritic cells (BM-DCs) pulsed with the Leishmania (L.) infantum histone H1. We developed fully mature BM-DCs characterized by enhanced capacity of IL-12 production after ex vivo pulsing with GST-LeishH1. Intravenous administration of these BM-DCs in naive BALB/c mice resulted in antigen-specific spleenocyte proliferation and IgG1 isotype antibody production and conferred protection against experimental challenge with L. infantum independently of CpG oligonucleotides (ODNs) co-administration. Protection was associated with a pronounced enhancement of parasite-specific IFNγ-producing cells and reduction of cells producing IL-10, whereas IL-4 production was comparable in protected and non-protected mice. The polarization of immune responses to Th1 type was further confirmed by the elevation of parasite-specific IgG2a/IgG1 ratio in protected mice. The above data indicate the immunostimulatory capacity of Leishmania histone H1 and further support its exploitation as a candidate protein for vaccine development against leishmaniasis.

  4. Public T cell receptors confer high-avidity CD4 responses to HIV controllers.

    Science.gov (United States)

    Benati, Daniela; Galperin, Moran; Lambotte, Olivier; Gras, Stéphanie; Lim, Annick; Mukhopadhyay, Madhura; Nouël, Alexandre; Campbell, Kristy-Anne; Lemercier, Brigitte; Claireaux, Mathieu; Hendou, Samia; Lechat, Pierre; de Truchis, Pierre; Boufassa, Faroudy; Rossjohn, Jamie; Delfraissy, Jean-François; Arenzana-Seisdedos, Fernando; Chakrabarti, Lisa A

    2016-06-01

    The rare patients who are able to spontaneously control HIV replication in the absence of therapy show signs of a particularly efficient cellular immune response. To identify the molecular determinants that underlie this response, we characterized the T cell receptor (TCR) repertoire directed at Gag293, the most immunoprevalent CD4 epitope in the HIV-1 capsid. HIV controllers from the ANRS CODEX cohort showed a highly skewed TCR repertoire that was characterized by a predominance of TRAV24 and TRBV2 variable genes, shared CDR3 motifs, and a high frequency of public clonotypes. The most prevalent public clonotypes generated TCRs with affinities at the higher end of values reported for naturally occurring TCRs. The high-affinity Gag293-specific TCRs were cross-restricted by up to 5 distinct HLA-DR alleles, accounting for the expression of these TCRs in HIV controllers of diverse genetic backgrounds. Transfer of these TCRs to healthy donor CD4+ T cells conferred high antigen sensitivity and polyfunctionality, thus recapitulating key features of the controller CD4 response. Transfer of a high-affinity Gag293-specific TCR also redirected CD8+ T cells to target HIV-1 capsid via nonconventional MHC II restriction. Together, these findings indicate that TCR clonotypes with superior functions are associated with HIV control. Amplification or transfer of such clonotypes may contribute to immunotherapeutic approaches aiming at a functional HIV cure. PMID:27111229

  5. Slow-Cycling Therapy-Resistant Cancer Cells

    OpenAIRE

    Moore, Nathan; Houghton, JeanMarie; Lyle, Stephen

    2011-01-01

    Tumor recurrence after chemotherapy is a major cause of patient morbidity and mortality. Recurrences are thought to be secondary to small subsets of cancer cells that are better able to survive traditional forms of chemotherapy and thus drive tumor regrowth. The ability to isolate and better characterize these therapy-resistant cells is critical for the future development of targeted therapies aimed at achieving more robust and long-lasting responses. Using a novel application for the prolife...

  6. Interferons Increase Cell Resistance to Staphylococcal Alpha-Toxin▿

    OpenAIRE

    Yarovinsky, Timur O.; Monick, Martha M.; Husmann, Matthias; Hunninghake, Gary W.

    2007-01-01

    Many bacterial pathogens, including Staphylococcus aureus, use a variety of pore-forming toxins as important virulence factors. Staphylococcal alpha-toxin, a prototype β-barrel pore-forming toxin, triggers the release of proinflammatory mediators and induces primarily necrotic death in susceptible cells. However, whether host factors released in response to staphylococcal infections may increase cell resistance to alpha-toxin is not known. Here we show that prior exposure to interferons (IFNs...

  7. Advances in the theory and application of BSF cells. [including electrical resistivity and photovoltaic cells

    Science.gov (United States)

    Mandelkorn, J.; Lamneck, J. H.

    1975-01-01

    The characteristics and behavior of p(+), p solar cells were investigated. The p(+), p cells were made by the removal of the n(+) surface layers from n(+), p p(+), BSF cells followed by application of a suitable contact to the resultant p(+), p structures. The open circuit voltage of p(+), p cells was found to increase with increasing 'p' bulk resistivity. The measured open circuit velocity-temperature coefficients were positive and increased with increasing resistivity. An outline of prior limitations in solar cell design is presented, and the removal of these limitations through use of BSF effects is pointed out. The study of BSF effects made feasible production of very thin high efficiency silicon cells as well as high resistivity-high efficiency cells, two desirable types of silicon cells which were previously impossible to make.

  8. Experimental evolution, genetic analysis and genome re-sequencing reveal the mutation conferring artemisinin resistance in an isogenic lineage of malaria parasites

    KAUST Repository

    Hunt, Paul

    2010-09-16

    Background: Classical and quantitative linkage analyses of genetic crosses have traditionally been used to map genes of interest, such as those conferring chloroquine or quinine resistance in malaria parasites. Next-generation sequencing technologies now present the possibility of determining genome-wide genetic variation at single base-pair resolution. Here, we combine in vivo experimental evolution, a rapid genetic strategy and whole genome re-sequencing to identify the precise genetic basis of artemisinin resistance in a lineage of the rodent malaria parasite, Plasmodium chabaudi. Such genetic markers will further the investigation of resistance and its control in natural infections of the human malaria, P. falciparum.Results: A lineage of isogenic in vivo drug-selected mutant P. chabaudi parasites was investigated. By measuring the artemisinin responses of these clones, the appearance of an in vivo artemisinin resistance phenotype within the lineage was defined. The underlying genetic locus was mapped to a region of chromosome 2 by Linkage Group Selection in two different genetic crosses. Whole-genome deep coverage short-read re-sequencing (IlluminaSolexa) defined the point mutations, insertions, deletions and copy-number variations arising in the lineage. Eight point mutations arise within the mutant lineage, only one of which appears on chromosome 2. This missense mutation arises contemporaneously with artemisinin resistance and maps to a gene encoding a de-ubiquitinating enzyme.Conclusions: This integrated approach facilitates the rapid identification of mutations conferring selectable phenotypes, without prior knowledge of biological and molecular mechanisms. For malaria, this model can identify candidate genes before resistant parasites are commonly observed in natural human malaria populations. 2010 Hunt et al; licensee BioMed Central Ltd.

  9. Cytosolic activation of cell death and stem rust resistance by cereal MLA-family CC-NLR proteins.

    Science.gov (United States)

    Cesari, Stella; Moore, John; Chen, Chunhong; Webb, Daryl; Periyannan, Sambasivam; Mago, Rohit; Bernoux, Maud; Lagudah, Evans S; Dodds, Peter N

    2016-09-01

    Plants possess intracellular immune receptors designated "nucleotide-binding domain and leucine-rich repeat" (NLR) proteins that translate pathogen-specific recognition into disease-resistance signaling. The wheat immune receptors Sr33 and Sr50 belong to the class of coiled-coil (CC) NLRs. They confer resistance against a broad spectrum of field isolates of Puccinia graminis f. sp. tritici, including the Ug99 lineage, and are homologs of the barley powdery mildew-resistance protein MLA10. Here, we show that, similarly to MLA10, the Sr33 and Sr50 CC domains are sufficient to induce cell death in Nicotiana benthamiana Autoactive CC domains and full-length Sr33 and Sr50 proteins self-associate in planta In contrast, truncated CC domains equivalent in size to an MLA10 fragment for which a crystal structure was previously determined fail to induce cell death and do not self-associate. Mutations in the truncated region also abolish self-association and cell-death signaling. Analysis of Sr33 and Sr50 CC domains fused to YFP and either nuclear localization or nuclear export signals in N benthamiana showed that cell-death induction occurs in the cytosol. In stable transgenic wheat plants, full-length Sr33 proteins targeted to the cytosol provided rust resistance, whereas nuclear-targeted Sr33 was not functional. These data are consistent with CC-mediated induction of both cell-death signaling and stem rust resistance in the cytosolic compartment, whereas previous research had suggested that MLA10-mediated cell-death and disease resistance signaling occur independently, in the cytosol and nucleus, respectively. PMID:27555587

  10. Cytosolic activation of cell death and stem rust resistance by cereal MLA-family CC-NLR proteins.

    Science.gov (United States)

    Cesari, Stella; Moore, John; Chen, Chunhong; Webb, Daryl; Periyannan, Sambasivam; Mago, Rohit; Bernoux, Maud; Lagudah, Evans S; Dodds, Peter N

    2016-09-01

    Plants possess intracellular immune receptors designated "nucleotide-binding domain and leucine-rich repeat" (NLR) proteins that translate pathogen-specific recognition into disease-resistance signaling. The wheat immune receptors Sr33 and Sr50 belong to the class of coiled-coil (CC) NLRs. They confer resistance against a broad spectrum of field isolates of Puccinia graminis f. sp. tritici, including the Ug99 lineage, and are homologs of the barley powdery mildew-resistance protein MLA10. Here, we show that, similarly to MLA10, the Sr33 and Sr50 CC domains are sufficient to induce cell death in Nicotiana benthamiana Autoactive CC domains and full-length Sr33 and Sr50 proteins self-associate in planta In contrast, truncated CC domains equivalent in size to an MLA10 fragment for which a crystal structure was previously determined fail to induce cell death and do not self-associate. Mutations in the truncated region also abolish self-association and cell-death signaling. Analysis of Sr33 and Sr50 CC domains fused to YFP and either nuclear localization or nuclear export signals in N benthamiana showed that cell-death induction occurs in the cytosol. In stable transgenic wheat plants, full-length Sr33 proteins targeted to the cytosol provided rust resistance, whereas nuclear-targeted Sr33 was not functional. These data are consistent with CC-mediated induction of both cell-death signaling and stem rust resistance in the cytosolic compartment, whereas previous research had suggested that MLA10-mediated cell-death and disease resistance signaling occur independently, in the cytosol and nucleus, respectively.

  11. Identification of genes associated with cisplatin resistance in human oral squamous cell carcinoma cell line

    International Nuclear Information System (INIS)

    Cisplatin is widely used for chemotherapy of head and neck squamous cell carcinoma. However, details of the molecular mechanism responsible for cisplatin resistance are still unclear. The aim of this study was to identify the expression of genes related to cisplatin resistance in oral squamous cell carcinoma cells. A cisplatin-resistant cell line, Tca/cisplatin, was established from a cisplatin-sensitive cell line, Tca8113, which was derived from moderately-differentiated tongue squamous cell carcinoma. Global gene expression in this resistant cell line and its sensitive parent cell line was analyzed using Affymetrix HG-U95Av2 microarrays. Candidate genes involved in DNA repair, the MAP pathway and cell cycle regulation were chosen to validate the microarray analysis results. Cell cycle distribution and apoptosis following cisplatin exposure were also investigated. Cisplatin resistance in Tca/cisplatin cells was stable for two years in cisplatin-free culture medium. The IC50 for cisplatin in Tca/cisplatin was 6.5-fold higher than that in Tca8113. Microarray analysis identified 38 genes that were up-regulated and 25 that were down-regulated in this cell line. Some were novel candidates, while others are involved in well-characterized mechanisms that could be relevant to cisplatin resistance, such as RECQL for DNA repair and MAP2K6 in the MAP pathway; all the genes were further validated by Real-time PCR. The cell cycle-regulated genes CCND1 and CCND3 were involved in cisplatin resistance; 24-hour exposure to 10 μM cisplatin induced a marked S phase block in Tca/cisplatin cells but not in Tca8113 cells. The Tca8113 cell line and its stable drug-resistant variant Tca/cisplatin provided a useful model for identifying candidate genes responsible for the mechanism of cisplatin resistance in oral squamous cell carcinoma. Our data provide a useful basis for screening candidate targets for early diagnosis and further intervention in cisplatin resistance

  12. Identification of genes associated with cisplatin resistance in human oral squamous cell carcinoma cell line

    Directory of Open Access Journals (Sweden)

    Zhang Ping

    2006-09-01

    Full Text Available Abstract Background Cisplatin is widely used for chemotherapy of head and neck squamous cell carcinoma. However, details of the molecular mechanism responsible for cisplatin resistance are still unclear. The aim of this study was to identify the expression of genes related to cisplatin resistance in oral squamous cell carcinoma cells. Methods A cisplatin-resistant cell line, Tca/cisplatin, was established from a cisplatin-sensitive cell line, Tca8113, which was derived from moderately-differentiated tongue squamous cell carcinoma. Global gene expression in this resistant cell line and its sensitive parent cell line was analyzed using Affymetrix HG-U95Av2 microarrays. Candidate genes involved in DNA repair, the MAP pathway and cell cycle regulation were chosen to validate the microarray analysis results. Cell cycle distribution and apoptosis following cisplatin exposure were also investigated. Results Cisplatin resistance in Tca/cisplatin cells was stable for two years in cisplatin-free culture medium. The IC50 for cisplatin in Tca/cisplatin was 6.5-fold higher than that in Tca8113. Microarray analysis identified 38 genes that were up-regulated and 25 that were down-regulated in this cell line. Some were novel candidates, while others are involved in well-characterized mechanisms that could be relevant to cisplatin resistance, such as RECQL for DNA repair and MAP2K6 in the MAP pathway; all the genes were further validated by Real-time PCR. The cell cycle-regulated genes CCND1 and CCND3 were involved in cisplatin resistance; 24-hour exposure to 10 μM cisplatin induced a marked S phase block in Tca/cisplatin cells but not in Tca8113 cells. Conclusion The Tca8113 cell line and its stable drug-resistant variant Tca/cisplatin provided a useful model for identifying candidate genes responsible for the mechanism of cisplatin resistance in oral squamous cell carcinoma. Our data provide a useful basis for screening candidate targets for early diagnosis

  13. Mechanism of multidrug resistance of human small cell lung cancer cell line H446/VP

    Institute of Scientific and Technical Information of China (English)

    WANG Yan-ling; YAN Yun-li; ZHOU Na-jing; HAN Shuo; ZHAO Jun-xia; CAO Cui-li; Lü Yu-hong

    2010-01-01

    Background Small cell lung cancer (SCLC) is the most aggressive form of lung cancer. This study aimed to investigate the mechanism of human small cell lung cancer cell line resistance to etoposide (VP-16), H446/VP.Methods The cell viability was measured by M∏ assay. Immunocytochemistry, reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting methods were used to detect the multidrug resistance gene (MDR1), bcl-2, bax and the topoisomerase Ⅱ (Topo Ⅱ) expressions in H446 and H446/VP cells after treated with or without VP-16.Results The 50% inhibition concentration (IC50) of VP-16 on H446 cells was 49 mg/L, and 836 mg/L was for H446/VP cells. The expressions of MDR1 and bcl-2 were up-regulated, while the amounts of bax and Topo Ⅱ were reduced in H446/VP cells. After treated with 49 mg/L of VP-16, it showed that the drug could significantly inhibit bcl-2 and Topo Ⅱ expressions, and increase bax expression in H446 cells compared with that of H446/VP cells.Conclusions The H446/VP cell was stably resistant to VP-16. The decreased expression of Topo Ⅱ was correlated with the H446/VP multidrug resistance. The elevated expressions of MDR1, and the altered apoptotic pathways also played an important role in VP-16 induced multidrug resistance of SCLC.

  14. Smoothened (SMO) receptor mutations dictate resistance to vismodegib in basal cell carcinoma.

    Science.gov (United States)

    Pricl, Sabrina; Cortelazzi, Barbara; Dal Col, Valentina; Marson, Domenico; Laurini, Erik; Fermeglia, Maurizio; Licitra, Lisa; Pilotti, Silvana; Bossi, Paolo; Perrone, Federica

    2015-02-01

    Basal cell carcinomas (BCCs) and a subset of medulloblastomas are characterized by loss-of-function mutations in the tumor suppressor gene, PTCH1. PTCH1 normally functions by repressing the activity of the Smoothened (SMO) receptor. Inactivating PTCH1 mutations result in constitutive Hedgehog pathway activity through uncontrolled SMO signaling. Targeting this pathway with vismodegib, a novel SMO inhibitor, results in impressive tumor regression in patients harboring genetic defects in this pathway. However, a secondary mutation in SMO has been reported in medulloblastoma patients following relapse on vismodegib to date. This mutation preserves pathway activity, but appears to confer resistance by interfering with drug binding. Here we report for the first time on the molecular mechanisms of resistance to vismodegib in two BCC cases. The first case, showing progression after 2 months of continuous vismodegib (primary resistance), exhibited the new SMO G497W mutation. The second case, showing a complete clinical response after 5 months of treatment and a subsequent progression after 11 months on vismodegib (secondary resistance), exhibited a PTCH1 nonsense mutation in both the pre- and the post-treatment specimens, and the SMO D473Y mutation in the post-treatment specimens only. In silico analysis demonstrated that SMO(G497W) undergoes a conformational rearrangement resulting in a partial obstruction of the protein drug entry site, whereas the SMO D473Y mutation induces a direct effect on the binding site geometry leading to a total disruption of a stabilizing hydrogen bond network. Thus, the G497W and D473Y SMO mutations may represent two different mechanisms leading to primary and secondary resistance to vismodegib, respectively. PMID:25306392

  15. Outer Membrane Protein Changes and Efflux Pump Expression Together May Confer Resistance to Ertapenem in Enterobacter cloacae

    OpenAIRE

    Szabó, Dóra; Silveira, Fernanda; Hujer, Andrea M.; Robert A Bonomo; Hujer, Kristine M.; Jane W Marsh; Bethel, Christopher R.; Doi, Yohei; Deeley, Kathleen; Paterson, David L.

    2006-01-01

    We investigated ertapenem-susceptible and -resistant extended-spectrum β-lactamase-producing Enterobacter cloacae isolates obtained from the same patient. Gene transcription of OmpD and OmpF was diminished in the ertapenem-resistant isolate. An efflux pump inhibitor decreased the MICs of ertapenem in the resistant strain, suggesting a potential role of efflux pumps in ertapenem resistance.

  16. Resistance to Bacillus thuringiensis Toxin Cry2Ab in Trichoplusia ni Is Conferred by a Novel Genetic Mechanism

    OpenAIRE

    Song, Xiaozhao; Kain, Wendy; Cassidy, Douglas; Wang, Ping

    2015-01-01

    The resistance to the Bacillus thuringiensis (Bt) toxin Cry2Ab in a greenhouse-originated Trichoplusia ni strain resistant to both Bt toxins Cry1Ac and Cry2Ab was characterized. Biological assays determined that the Cry2Ab resistance in the T. ni strain was a monogenic recessive trait independent of Cry1Ac resistance, and there existed no significant cross-resistance between Cry1Ac and Cry2Ab in T. ni. From the dual-toxin-resistant T. ni strain, a strain resistant to Cry2Ab only was isolated,...

  17. The inverse correlation between series resistance and parallel resistance of small molecule organic solar cells

    Institute of Scientific and Technical Information of China (English)

    Kewei Wang; Yufeng Zheng; Gu Xu; Xiuping Xu

    2015-01-01

    Understanding the inversely correlated series resistance (Rs) and parallel resistance (Rp) remains a challenge. Here we report that the variation of Rs and Rp is inversely related through the morphology of the donor and acceptor interface in CuPc organic solar cells, when comparing the bilayer structure and bulk heterojunction structure. It was also found that the charge carrier concentration near the donor–acceptor interface plays an important role in the relationships of Rs and Rp under fixed interfacial morphology, which was verified by the change of Voc. The inversely correlated Rs and Rp contributes to the improvement of the fill factor, and in turn the power conversion efficiency.

  18. Specific dysregulation of IFNγ production by natural killer cells confers susceptibility to viral infection.

    Directory of Open Access Journals (Sweden)

    Nassima Fodil

    2014-12-01

    Full Text Available Natural Killer (NK cells contribute to the control of viral infection by directly killing target cells and mediating cytokine release. In C57BL/6 mice, the Ly49H activating NK cell receptor plays a key role in early resistance to mouse cytomegalovirus (MCMV infection through specific recognition of the MCMV-encoded MHC class I-like molecule m157 expressed on infected cells. Here we show that transgenic expression of Ly49H failed to provide protection against MCMV infection in the naturally susceptible A/J mouse strain. Characterization of Ly49H(+ NK cells from Ly49h-A transgenic animals showed that they were able to mount a robust cytotoxic response and proliferate to high numbers during the course of infection. However, compared to NK cells from C57BL/6 mice, we observed an intrinsic defect in their ability to produce IFNγ when challenged by either m157-expressing target cells, exogenous cytokines or chemical stimulants. This effect was limited to NK cells as T cells from C57BL/6 and Ly49h-A mice produced comparable cytokine levels. Using a panel of recombinant congenic strains derived from A/J and C57BL/6 progenitors, we mapped the genetic basis of defective IFNγ production to a single 6.6 Mb genetic interval overlapping the Ifng gene on chromosome 10. Inspection of the genetic interval failed to reveal molecular differences between A/J and several mouse strains showing normal IFNγ production. The chromosome 10 locus is independent of MAPK signalling or decreased mRNA stability and linked to MCMV susceptibility. This study highlights the existence of a previously uncovered NK cell-specific cis-regulatory mechanism of Ifnγ transcript expression potentially relevant to NK cell function in health and disease.

  19. Tamoxifen-resistant breast cancer cells possess cancer stem-like cell properties

    Institute of Scientific and Technical Information of China (English)

    LIU Hui; ZHANG Heng-wei; SUN Xian-fu; GUO Xu-hui; HE Ya-ning; CUI Shu-de; FAN Qing-xia

    2013-01-01

    Background Cancer stem cells (CSCs) are the cause of cancer recurrence because they are resistant to conventional therapy and contribute to cancer growth and metastasis.Endocrinotherapy is the most common breast cancer therapy and acquired tamoxifen (TAM) resistance is the main reason for endocrinotherapy failure during such therapy.Although acquired resistance to endocrine treatment has been extensively studied,the underlying mechanisms are unclear.We hypothesized that breast CSCs played an important role in TAM-induced resistance during breast cancer therapy.Therefore,we investigated the biological characteristics of TAM-resistant (TAM-R) breast cancer cells.Methods Mammosphere formation and tumorigenicity of wild-type (WT) and TAM-R MCF7 cells were tested by a mammosphere assay and mouse tumor xenografts respectively.Stem-cell markers (SOX-2,OCT-4,and CD133) and epithelial-mesenchymal transition (EMT) markers were tested by quantitative real-time (qRT)-PCR.Morphological observation was performed to characterize EMT.Results After induction of TAM resistance,TAM-R MCF7 cells exhibited increased proliferation in the presence of TAM compared to that of WT MCF7 cells (P <0.05),indicating enhanced TAM resistance of TAM-R MCF7 cells compared to that of WT MCF7 cells.TAM-R MCF7 cells showed enhanced mammosphere formation and tumorigenicity in nude mice compared to that of WT MCF7 cells (P <0.01),demonstrating the elevated CSC properties of TAM-R MCF7 cells.Consistently,qRT-PCR revealed that TAM-R MCF7 cells expressed increased mRNA levels of stem cell markers including SOX-2,OCT-4,and CD133,compared to those of WT MCF7 cells (P <0.05).Morphologically,TAM-R MCF7 cells showed a fibroblastic phenotype,but WT MCF7 cells were epithelial-like.After induction of TAM resistance,qRT-PCR indicated that MCF7 cells expressed increased mRNA levels of Snail,vimentin,and N-cadherin and decreased levels of E-cadherin,which are considered as EMT characteristics (P <0

  20. Cell Biological Mechanisms of Multidrug Resistance in Tumors

    Science.gov (United States)

    Simon, Sanford M.; Schindler, Melvin

    1994-04-01

    Multidrug resistance (MDR) is a generic term for the variety of strategies tumor cells use to evade the cytotoxic effects of anticancer drugs. MDR is characterized by a decreased sensitivity of tumor cells not only to the drug employed for chemotherapy but also to a broad spectrum of drugs with neither obvious structural homology nor common targets. This pleotropic resistance is one of the major obstacles to the successful treatment of tumors. MDR may result from structural or functional changes at the plasma membrane or within the cytoplasm, cellular compartments, or nucleus. Molecular mechanisms of MDR are discussed in terms of modifications in detoxification and DNA repair pathways, changes in cellular sites of drug sequestration, decreases in drug-target affinity, synthesis of specific drug inhibitors within cells, altered or inappropriate targeting of proteins, and accelerated removal or secretion of drugs.

  1. Endoplasmic Reticulum Ca(2+) Handling and Apoptotic Resistance in Tumor-Derived Endothelial Colony Forming Cells.

    Science.gov (United States)

    Poletto, Valentina; Dragoni, Silvia; Lim, Dmitry; Biggiogera, Marco; Aronica, Adele; Cinelli, Mariapia; De Luca, Antonio; Rosti, Vittorio; Porta, Camillo; Guerra, Germano; Moccia, Francesco

    2016-10-01

    Truly endothelial progenitor cells (EPCs) can be mobilized from bone marrow to support the vascular network of growing tumors, thereby sustaining the metastatic switch. Endothelial colony forming cells (ECFCs) are the only EPC subtype belonging to the endothelial phenotype and capable of incorporating within neovessels. The intracellular Ca(2+) machinery plays a key role in ECFC activation and is remodeled in renal cellular carcinoma-derived ECFCs (RCC-ECFCs). Particularly, RCC-ECFCs seems to undergo a drop in endoplasmic reticulum (ER) Ca(2+) concentration ([Ca(2+) ]ER ). This feature is remarkable when considering that inositol-1,4,5-trisphosphate (InsP3 )-dependent ER-to-mitochondria Ca(2+) transfer regulates the intrinsic apoptosis pathway. Herein, we sought to assess whether: (1) the [Ca(2+) ]ER and the InsP3 -induced ER-mitochondria Ca(2+) shuttle are reduced in RCC-ECFCs; and (2) the dysregulation of ER Ca(2+) handling leads to apoptosis resistance in tumor-derived cells. RCC-ECFCs displayed a reduction both in [Ca(2+) ]ER and in the InsP3 -dependent mitochondrial Ca(2+) uptake, while they expressed normal levels of Bcl-2 and Bak. The decrease in [Ca(2+) ]ER was associated to a remarkable ER expansion in RCC-ECFCs, which is a hallmark of ER stress, and did not depend on the remodeling of the Ca(2+) -transporting and the ER Ca(2+) -storing systems. As expected, RCC-ECFCs were less sensitive to rapamycin- and thapsigargin-induced apoptosis; however, buffering intracellular Ca(2+) levels with BAPTA dampened apoptosis in both cell types. Finally, store-operated Ca(2+) entry was seemingly uncoupled from the apoptotic machinery in RCC-ECFCs. Thus, the chronic underfilling of the ER Ca(2+) pool could confer a survival advantage to RCC-ECFCs and underpin RCC resistance to pharmacological treatment. J. Cell. Biochem. 117: 2260-2271, 2016. © 2016 Wiley Periodicals, Inc.

  2. Endoplasmic Reticulum Ca(2+) Handling and Apoptotic Resistance in Tumor-Derived Endothelial Colony Forming Cells.

    Science.gov (United States)

    Poletto, Valentina; Dragoni, Silvia; Lim, Dmitry; Biggiogera, Marco; Aronica, Adele; Cinelli, Mariapia; De Luca, Antonio; Rosti, Vittorio; Porta, Camillo; Guerra, Germano; Moccia, Francesco

    2016-10-01

    Truly endothelial progenitor cells (EPCs) can be mobilized from bone marrow to support the vascular network of growing tumors, thereby sustaining the metastatic switch. Endothelial colony forming cells (ECFCs) are the only EPC subtype belonging to the endothelial phenotype and capable of incorporating within neovessels. The intracellular Ca(2+) machinery plays a key role in ECFC activation and is remodeled in renal cellular carcinoma-derived ECFCs (RCC-ECFCs). Particularly, RCC-ECFCs seems to undergo a drop in endoplasmic reticulum (ER) Ca(2+) concentration ([Ca(2+) ]ER ). This feature is remarkable when considering that inositol-1,4,5-trisphosphate (InsP3 )-dependent ER-to-mitochondria Ca(2+) transfer regulates the intrinsic apoptosis pathway. Herein, we sought to assess whether: (1) the [Ca(2+) ]ER and the InsP3 -induced ER-mitochondria Ca(2+) shuttle are reduced in RCC-ECFCs; and (2) the dysregulation of ER Ca(2+) handling leads to apoptosis resistance in tumor-derived cells. RCC-ECFCs displayed a reduction both in [Ca(2+) ]ER and in the InsP3 -dependent mitochondrial Ca(2+) uptake, while they expressed normal levels of Bcl-2 and Bak. The decrease in [Ca(2+) ]ER was associated to a remarkable ER expansion in RCC-ECFCs, which is a hallmark of ER stress, and did not depend on the remodeling of the Ca(2+) -transporting and the ER Ca(2+) -storing systems. As expected, RCC-ECFCs were less sensitive to rapamycin- and thapsigargin-induced apoptosis; however, buffering intracellular Ca(2+) levels with BAPTA dampened apoptosis in both cell types. Finally, store-operated Ca(2+) entry was seemingly uncoupled from the apoptotic machinery in RCC-ECFCs. Thus, the chronic underfilling of the ER Ca(2+) pool could confer a survival advantage to RCC-ECFCs and underpin RCC resistance to pharmacological treatment. J. Cell. Biochem. 117: 2260-2271, 2016. © 2016 Wiley Periodicals, Inc. PMID:26917354

  3. Mathematical Modeling of Contact Resistance in Silicon Photovoltaic Cells

    KAUST Repository

    Black, J. P.

    2013-10-22

    In screen-printed silicon-crystalline solar cells, the contact resistance of a thin interfacial glass layer between the silicon and the silver electrode plays a limiting role for electron transport. We analyze a simple model for electron transport across this layer, based on the driftdiffusion equations. We utilize the size of the current/Debye length to conduct asymptotic techniques to simplify the model; we solve the model numerically to find that the effective contact resistance may be a monotonic increasing, monotonic decreasing, or nonmonotonic function of the electron flux, depending on the values of the physical parameters. © 2013 Society for Industrial and Applied Mathematics.

  4. Determination of the Antibiotic Resistance Profile of Student Cell Phones

    Directory of Open Access Journals (Sweden)

    Lisa Ann Blankinship

    2012-08-01

    Full Text Available Sampling of common use items (e.g., student cell phones for bacterial presence, identification, and antibiotic resistance profiling helps students to recognize the need for routine cleaning of personal items and encourages thoughtful use of currently available medications. This multilab period project can be used to teach or reinforce several methods from general microbiology including aseptic technique, isolation streak, serial dilution, spread plating, Kirby Bauer testing, unknown identification, and media production. The data generated can be saved and added to each semester, thus providing a data set that reflects a local trend of antibiotic resistance.      

  5. Insights into the structure, function and evolution of the radical-SAM 23S rRNA methyltransferase Cfr that confers antibiotic resistance in bacteria

    DEFF Research Database (Denmark)

    Karminska, K. H.; Purta, E.; Hansen, L .H.;

    2010-01-01

    The Cfr methyltransferase confers combined resistance to five classes of antibiotics that bind to the peptidyl tranferase center of bacterial ribosomes by catalyzing methylation of the C-8 position of 23S rRNA nucleotide A2503. The same nucleotide is targeted by the housekeeping methyltransferase...... of a 4Fe-4S cluster, a SAM molecule coordinated to the iron-sulfur cluster (SAM1) and a SAM molecule that is the putative methyl group donor (SAM2). All mutations at predicted functional sites affect Cfr activity significantly as assayed by antibiotic susceptibility testing and primer extension analysis...

  6. Invasive oral cancer stem cells display resistance to ionising radiation.

    Science.gov (United States)

    Gemenetzidis, Emilios; Gammon, Luke; Biddle, Adrian; Emich, Helena; Mackenzie, Ian C

    2015-12-22

    There is a significant amount of evidence to suggest that human tumors are driven and maintained by a sub-population of cells, known as cancer stem cells (CSC). In the case of head and neck cancer, such cells have been characterised by high expression levels of CD44 cell surface glycoprotein, while we have previously shown the presence of two diverse oral CSC populations in vitro, with different capacities for cell migration and proliferation. Here, we examined the response of oral CSC populations to ionising radiation (IR), a front-line measure for the treatment of head and neck tumors. We show that oral CSC initially display resistance to IR-induced growth arrest as well as relative apoptotic resistance. We propose that this is a result of preferential activation of the DNA damagerepair pathway in oral CSC with increased activation of ATM and BRCA1, elevated levels of DNA repair proteins RAD52, XLF, and a significantly faster rate of DNA double-strand-breaks clearance 24 hours following IR. By visually identifying CSC sub-populations undergoing EMT, we show that EMT-CSC represent the majority of invasive cells, and are more radio-resistant than any other population in re-constructed 3D tissues. We provide evidence that IR is not sufficient to eliminate CSC in vitro, and that sensitization of CD44hi/ESAlow cells to IR, followed by secondary EMT blockade, could be critical in order to reduce primary tumor recurrence, but more importantly to be able to eradicate cells capable of invasion and distant metastasis.

  7. Method for contact resistivity measurements on photovoltaic cells and cell adapted for such measurement

    Science.gov (United States)

    Burger, Dale R. (Inventor)

    1986-01-01

    A method is disclosed for scribing at least three grid contacts of a photovoltaic cell to electrically isolate them from the grid contact pattern used to collect solar current generated by the cell, and using the scribed segments for determining parameters of the cell by a combination of contact end resistance (CER) measurements using a minimum of three equally or unequally spaced lines, and transmission line modal (TLM) measurements using a minimum of four unequally spaced lines. TLM measurements may be used to determine sheet resistance under the contact, R.sub.sk, while CER measurements are used to determine contact resistivity, .rho..sub.c, from a nomograph of contact resistivity as a function of contact end resistance and sheet resistivity under the contact. In some cases, such as the case of silicon photovoltaic cells, sheet resistivity under the contact may be assumed to be equal to the known sheet resistance, R.sub.s, of the semiconductor material, thereby obviating the need for TLM measurements to determine R.sub.sk.

  8. The expression of a bean PGIP in transgenic wheat confers increased resistance to the fungal pathogen Bipolaris sorokiniana.

    Science.gov (United States)

    Janni, Michela; Sella, Luca; Favaron, Francesco; Blechl, Ann E; De Lorenzo, Giulia; D'Ovidio, Renato

    2008-02-01

    A possible strategy to control plant pathogens is the improvement of natural plant defense mechanisms against the tools that pathogens commonly use to penetrate and colonize the host tissue. One of these mechanisms is represented by the host plant's ability to inhibit the pathogen's capacity to degrade plant cell wall polysaccharides. Polygalacturonase-inhibiting proteins (PGIP) are plant defense cell wall glycoproteins that inhibit the activity of fungal endopolygalacturonases (endo-PGs). To assess the effectiveness of these proteins in protecting wheat from fungal pathogens, we produced a number of transgenic wheat lines expressing a bean PGIP (PvPGIP2) having a wide spectrum of specificities against fungal PGs. Three independent transgenic lines were characterized in detail, including determination of the levels of PvPGIP2 accumulation and its subcellular localization and inhibitory activity. Results show that the transgene-encoded protein is correctly secreted into the apoplast, maintains its characteristic recognition specificities, and endows the transgenic wheat with new PG recognition capabilities. As a consequence, transgenic wheat tissue showed increased resistance to digestion by the PG of Fusarium moniliforme. These new properties also were confirmed at the plant level during interactions with the fungal pathogen Bipolaris sorokiniana. All three lines showed significant reductions in symptom progression (46 to 50%) through the leaves following infection with this pathogen. Our results illustrate the feasibility of improving wheat's defenses against pathogens by expression of proteins with new capabilities to counteract those produced by the pathogens.

  9. "Resistance" to PSC-RANTES revisited: two mutations in human immunodeficiency virus type 1 HIV-1 SF162 or simian-human immunodeficiency virus SHIV SF162-p3 do not confer resistance.

    Science.gov (United States)

    Nedellec, Rebecca; Coetzer, Mia; Lederman, Michael M; Offord, Robin E; Hartley, Oliver; Mosier, Donald E

    2010-06-01

    Resistance of human immunodeficiency virus type 1 (HIV-1) to small-molecule CCR5 inhibitors is well demonstrated, but resistance to macromolecular CCR5 inhibitors (e.g., PSC-RANTES) that act by both CCR5 internalization and receptor blockade had not been reported until recently (3). The report of a single simian-human immunodeficiency virus SHIV(SF162-p3) variant with one V3 and one gp41 sequence change in gp160 that conferred both altered replicative fitness and resistance to PSC-RANTES was therefore surprising. We introduced the same two mutations into both the parental HIV-1(SF162) and the macaque-adapted SHIV(SF162-p3) and found minor differences in entry fitness but no changes in sensitivity to inhibition by either PSC-RANTES or the small-molecule allosteric inhibitor TAK-779. We attribute the earlier finding to confounding fitness effects with inhibitor sensitivity.

  10. Multiple mechanisms underlying acquired resistance to taxanes in selected docetaxel-resistant MCF-7 breast cancer cells

    International Nuclear Information System (INIS)

    Chemoresistance is a major factor involved in a poor response and reduced overall survival in patients with advanced breast cancer. Although extensive studies have been carried out to understand the mechanisms of chemoresistance, many questions remain unanswered. In this research, we used two isogenic MCF-7 breast cancer cell lines selected for resistance to doxorubicin (MCF-7DOX) or docetaxel (MCF-7TXT) and the wild type parental cell line (MCF-7CC) to study mechanisms underlying acquired resistance to taxanes in MCF-7TXT cells. Cytotoxicity assay, immunoblotting, indirect immunofluorescence and live imaging were used to study the drug resistance, the expression levels of drug transporters and various tubulin isoforms, apoptosis, microtubule formation, and microtubule dynamics. MCF-7TXT cells were cross resistant to paclitaxel, but not to doxorubicin. MCF-7DOX cells were not cross-resistant to taxanes. We also showed that multiple mechanisms are involved in the resistance to taxanes in MCF-7TXT cells. Firstly, MCF-7TXT cells express higher level of ABCB1. Secondly, the microtubule dynamics of MCF-7TXT cells are weak and insensitive to the docetaxel treatment, which may partially explain why docetaxel is less effective in inducing M-phase arrest and apoptosis in MCF-7TXT cells in comparison with MCF-7CC cells. Moreover, MCF-7TXT cells express relatively higher levels of β2- and β4-tubulin and relatively lower levels of β3-tubulin than both MCF-7CC and MCF-7DOX cells. The subcellular localization of various β-tubulin isoforms in MCF-7TXT cells is also different from that in MCF-7CC and MCF-7DOX cells. Multiple mechanisms are involved in the resistance to taxanes in MCF-7TXT cells. The high expression level of ABCB1, the specific composition and localization of β-tubulin isoforms, the weak microtubule dynamics and its insensitivity to docetaxel may all contribute to the acquired resistance of MCF-7TXT cells to taxanes

  11. 1st ESMO Consensus Conference in lung cancer; Lugano 2010: small-cell lung cancer

    DEFF Research Database (Denmark)

    Stahel, R; Thatcher, N; Früh, M;

    2011-01-01

    The 1st ESMO Consensus Conference on lung cancer was held in Lugano, Switzerland on 21st and 22nd May 2010 with the participation of a multidisciplinary panel of leading professionals in pathology and molecular diagnostics and medical, surgical and radiation oncology. Before the conference, the e...

  12. Expression of a full-length cDNA for the human "MDR1" gene confers resistance to colchicine, doxorubicin, and vinblastine.

    OpenAIRE

    Ueda, K; Cardarelli, C; Gottesman, M M; Pastan, I

    1987-01-01

    Intrinsic and acquired multidrug resistance (MDR) is an important problem in cancer therapy. MDR in human KB carcinoma cells selected for resistance to colchicine, vinblastine, or doxorubicin (former generic name adriamycin) is associated with overexpression of the "MDR1" gene, which encodes P-glycoprotein. We previously have isolated an overlapping set of cDNA clones for the human MDR1 gene from multidrug-resistant KB cells. Here we report the construction of a full-length cDNA for the human...

  13. High precision measurement of electrical resistance across endothelial cell monolayers.

    Science.gov (United States)

    Tschugguel, W; Zhegu, Z; Gajdzik, L; Maier, M; Binder, B R; Graf, J

    1995-05-01

    Effects of vasoactive agonists on endothelial permeability was assessed by measurement of transendothelial electrical resistance (TEER) of human umbilical vein endothelial cells (HUVECs) grown on porous polycarbonate supports. Because of the low values of TEER obtained in this preparation (< 5 omega cm2) a design of an Ussing type recording chamber was chosen that provided for a homogeneous electric field across the monolayer and for proper correction of series resistances. Precision current pulses and appropriate rates of sampling and averaging of the voltage signal allowed for measurement of < 0.1 omega resistance changes of the endothelium on top of a 21 omega series resistance of the support and bathing fluid layers. Histamine (10 microM) and thrombin (10 U/ml) induced an abrupt and substantial decrease of TEER, bradykinin (1 microM) was less effective, PAF (380 nM) and LTC4 (1 microM) had no effect. TEER was also reduced by the calcium ionophore A-23187 (10 microM). The technique allows for measurements of TEER in low resistance monolayer cultures with high precision and time resolution. The results obtained extend previous observations in providing quantitative data on the increase of permeability of HUVECs in response to vasoactive agonists.

  14. Pluripotent Stem Cell Protein Sox2 Confers Sensitivity to LSD1 Inhibition in Cancer Cells

    Directory of Open Access Journals (Sweden)

    Xiaoming Zhang

    2013-10-01

    Full Text Available Gene amplification of Sox2 at 3q26.33 is a common event in squamous cell carcinomas (SCCs of the lung and esophagus, as well as several other cancers. Here, we show that the expression of LSD1/KDM1 histone demethylase is significantly elevated in Sox2-expressing lung SCCs. LSD1-specific inhibitors selectively impair the growth of Sox2-expressing lung SCCs, but not that of Sox2-negative cells. Sox2 expression is associated with sensitivity to LSD1 inhibition in lung, breast, ovarian, and other carcinoma cells. Inactivation of LSD1 reduces Sox2 expression, promotes G1 cell-cycle arrest, and induces genes for differentiation by selectively modulating the methylation states of histone H3 at lysines 4 (H3K4 and 9 (H3K9. Reduction of Sox2 further suppresses Sox2-dependent lineage-survival oncogenic potential, elevates trimethylation of histone H3 at lysine 27 (H3K27 and enhances growth arrest and cellular differentiation. Our studies suggest that LSD1 serves as a selective epigenetic target for therapy in Sox2-expressing cancers.

  15. Microbeam PIXE analysis of platinum resistant and sensitive ovarian cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Jeynes, J.C.G., E-mail: J.C.Jeynes@surrey.ac.u [Ion Beam Centre, University of Surrey, Guildford GU2 7XH (United Kingdom); Bailey, M.J. [Ion Beam Centre, University of Surrey, Guildford GU2 7XH (United Kingdom); Coley, H. [Faculty of Health and Medical Sciences, University of Surrey, Guildford GU2 7XH (United Kingdom); Kirkby, K.J.; Jeynes, C. [Ion Beam Centre, University of Surrey, Guildford GU2 7XH (United Kingdom)

    2010-06-15

    Microbeam PIXE was used to analyse platinum in single ovarian cancer cells. Carboplatin sensitive and resistant cells were grown as a monolayer on polypropylene and treated with either carboplatin or cisplatin. Pt from the carboplatin could not be detected. The Pt from cisplatin in the cells could be detected, and significantly more Zn was found in the resistant cells compared to the sensitive cells. The sensitive cells probably accumulated more cisplatin than the resistant ones.

  16. Sildenafil Reduces Insulin-Resistance in Human Endothelial Cells

    OpenAIRE

    Caterina Mammi; Donatella Pastore; Lombardo, Marco F; Francesca Ferrelli; Massimiliano Caprio; Claudia Consoli; Manfredi Tesauro; Lucia Gatta; Massimo Fini; Massimo Federici; Paolo Sbraccia; Giulia Donadel; Alfonso Bellia; Giuseppe M Rosano; Andrea Fabbri

    2011-01-01

    BACKGROUND: The efficacy of Phosphodiesterase 5 (PDE5) inhibitors to re-establish endothelial function is reduced in diabetic patients. Recent evidences suggest that therapy with PDE5 inhibitors, i.e. sildenafil, may increase the expression of nitric oxide synthase (NOS) proteins in the heart and cardiomyocytes. In this study we analyzed the effect of sildenafil on endothelial cells in insulin resistance conditions in vitro. METHODOLOGY/PRINCIPAL FINDINGS: Human umbilical vein endothelial cel...

  17. Intrinsic resistance to aminoglycosides in Enterococcus faecium is conferred by the 16S rRNA m5C1404-specific methyltransferase EfmM

    DEFF Research Database (Denmark)

    Galimand, Marc; Schmitt, Emmanuelle; Panvert, Michel;

    2011-01-01

    confers resistance to these drugs. The EfmM protein shows significant sequence similarity to E. coli RsmF (previously called YebU), which is a 5-methylcytidine (m(5)C) methyltransferase modifying 16S rRNA nucleotide C1407. The target for EfmM is shown by mass spectrometry to be a neighboring 16S r......RNA nucleotide at C1404. EfmM uses the methyl group donor S-adenosyl-L-methionine to catalyze formation of m(5)C1404 on the 30S ribosomal subunit, whereas naked 16S rRNA and the 70S ribosome are not substrates. Addition of the 5-methyl to C1404 sterically hinders aminoglycoside binding. Crystallographic......Aminoglycosides are ribosome-targeting antibiotics and a major drug group of choice in the treatment of serious enterococcal infections. Here we show that aminoglycoside resistance in Enterococcus faecium strain CIP 54-32 is conferred by the chromosomal gene efmM, encoding the E. faecium...

  18. Natural Polymorphisms Conferring Resistance to HCV Protease and Polymerase Inhibitors in Treatment-Naive HIV/HCV Co-Infected Patients in China.

    Directory of Open Access Journals (Sweden)

    Kali Zhou

    Full Text Available The advent of direct-acting agents (DAAs has improved treatment of HCV in HIV co-infection, but may be limited by primary drug resistance. This study reports the prevalence of natural polymorphisms conferring resistance to NS3/4A protease inhibitors and NS5B polymerase inhibitors in treatment-naïve HIV/HCV co-infected individuals in China.Population based NS3/4A sequencing was completed for 778 treatment-naïve HIV/HCV co-infected patients from twelve provinces. NS3 sequences were amplified by nested PCR using in-house primers for genotypes 1-6. NS5B sequencing was completed for genotyping in 350 sequences. Resistance-associated variants (RAVs were identified in positions associated with HCV resistance.Overall, 72.8% (566/778 of all HCV sequences had at least one RAV associated with HCV NS3/4A protease inhibitor resistance. Variants were found in 3.6% (7/193 of genotype 1, 100% (23/23 of genotype 2, 100% (237/237 of genotype 3 and 92% (299/325 of genotype 6 sequences. The Q80K variant was present in 98.4% of genotype 6a sequences. High-level RAVs were rare, occurring in only 0.8% of patients. 93% (64/69 patients with genotype 1b also carried the C316N variant associated with NS5B low-level resistance.The low frequency of high-level RAVs associated with primary HCV DAA resistance among all genotypes in HIV/HCV co-infected patients is encouraging. Further phenotypic studies and clinical research are needed.

  19. Natural Polymorphisms Conferring Resistance to HCV Protease and Polymerase Inhibitors in Treatment-Naïve HIV/HCV Co-Infected Patients in China

    Science.gov (United States)

    Wang, Charles; Hu, Fengyu; Ning, Chuanyi; Lan, Yun; Tang, Xiaoping; Tucker, Joseph D.; Cai, Weiping

    2016-01-01

    Background The advent of direct-acting agents (DAAs) has improved treatment of HCV in HIV co-infection, but may be limited by primary drug resistance. This study reports the prevalence of natural polymorphisms conferring resistance to NS3/4A protease inhibitors and NS5B polymerase inhibitors in treatment-naïve HIV/HCV co-infected individuals in China. Methods Population based NS3/4A sequencing was completed for 778 treatment-naïve HIV/HCV co-infected patients from twelve provinces. NS3 sequences were amplified by nested PCR using in-house primers for genotypes 1–6. NS5B sequencing was completed for genotyping in 350 sequences. Resistance-associated variants (RAVs) were identified in positions associated with HCV resistance. Results Overall, 72.8% (566/778) of all HCV sequences had at least one RAV associated with HCV NS3/4A protease inhibitor resistance. Variants were found in 3.6% (7/193) of genotype 1, 100% (23/23) of genotype 2, 100% (237/237) of genotype 3 and 92% (299/325) of genotype 6 sequences. The Q80K variant was present in 98.4% of genotype 6a sequences. High-level RAVs were rare, occurring in only 0.8% of patients. 93% (64/69) patients with genotype 1b also carried the C316N variant associated with NS5B low-level resistance. Conclusions The low frequency of high-level RAVs associated with primary HCV DAA resistance among all genotypes in HIV/HCV co-infected patients is encouraging. Further phenotypic studies and clinical research are needed. PMID:27341031

  20. 2009 Plant Cell Walls Gordon Research Conference-August 2-7,2009

    Energy Technology Data Exchange (ETDEWEB)

    Debra Mohnen

    2009-08-07

    Plant cell walls are a complex cellular compartment essential for plant growth, development and response to biotic and abiotic stress and a major biological resource for meeting our future bioenergy and natural product needs. The goal of the 2009 Plant Cell Walls Gordon Research Conference is to summarize and critically evaluate the current level of understanding of the structure, synthesis and function of the whole plant extracellular matrix, including the polysaccharides, proteins, lignin and waxes that comprise the wall, and the enzymes and regulatory proteins that drive wall synthesis and modification. Innovative techniques to study how both primary and secondary wall polymers are formed and modified throughout plant growth will be emphasized, including rapid advances taking place in the use of anti-wall antibodies and carbohydrate binding proteins, comparative and evolutionary wall genomics, and the use of mutants and natural variants to understand and identify wall structure-function relationships. Discussions of essential research advances needed to push the field forward toward a systems biology approach will be highlighted. The meeting will include a commemorative lecture in honor of the career and accomplishments of the late Emeritus Professor Bruce A. Stone, a pioneer in wall research who contributed over 40 years of outstanding studies on plant cell wall structure, function, synthesis and remodeling including emphasis on plant cell wall beta-glucans and arabinogalactans. The dwindling supply of fossil fuels will not suffice to meet our future energy and industrial product needs. Plant biomass is the renewable resource that will fill a large part of the void left by vanishing fossil fuels. It is therefore critical that basic research scientists interact closely with industrial researchers to critically evaluate the current state of knowledge regarding how plant biomass, which is largely plant cell walls, is synthesized and utilized by the plant. A final

  1. A Distinct Lung-Interstitium-Resident Memory CD8+ T Cell Subset Confers Enhanced Protection to Lower Respiratory Tract Infection

    Directory of Open Access Journals (Sweden)

    Pavlo Gilchuk

    2016-08-01

    Full Text Available The nature and anatomic location of the protective memory CD8+ T cell subset induced by intranasal vaccination remain poorly understood. We developed a vaccination model to assess the anatomic location of protective memory CD8+ T cells and their role in lower airway infections. Memory CD8+ T cells elicited by local intranasal, but not systemic, vaccination with an engineered non-replicative CD8+ T cell-targeted antigen confer enhanced protection to a lethal respiratory viral challenge. This protection depends on a distinct CXCR3LO resident memory CD8+ T (Trm cell population that preferentially localizes to the pulmonary interstitium. Because they are positioned close to the mucosa, where infection occurs, interstitial Trm cells act before inflammation can recruit circulating memory CD8+ T cells into the lung tissue. This results in a local protective immune response as early as 1 day post-infection. Hence, vaccine strategies that induce lung interstitial Trm cells may confer better protection against respiratory pathogens.

  2. Characterization of a mantle cell lymphoma cell line resistant to the Chk1 inhibitor PF-00477736.

    Science.gov (United States)

    Restelli, Valentina; Chilà, Rosaria; Lupi, Monica; Rinaldi, Andrea; Kwee, Ivo; Bertoni, Francesco; Damia, Giovanna; Carrassa, Laura

    2015-11-10

    Mantle cell lymphoma (MCL) is an aggressive B-cell lymphoma characterized by the chromosomal translocation t(11;14) that leads to constitutive expression of cyclin D1, a master regulator of the G1-S phase. Chk1 inhibitors have been recently shown to be strongly effective as single agents in MCL. To investigate molecular mechanisms at the basis of Chk1 inhibitor activity, a MCL cell line resistant to the Chk1 inhibitor PF-00477736 (JEKO-1 R) was obtained and characterized. The JEKO-1 R cell line was cross resistant to another Chk1 inhibitor (AZD-7762) and to the Wee1 inhibitor MK-1775. It displayed a shorter doubling time than parental cell line, likely due to a faster S phase. Cyclin D1 expression levels were decreased in resistant cell line and its re-overexpression partially re-established PF-00477736 sensitivity. Gene expression profiling showed an enrichment in gene sets involved in pro-survival pathways in JEKO-1 R. Dasatinib treatment partly restored PF-00477736 sensitivity in resistant cells suggesting that the pharmacological interference of pro-survival pathways can overcome the resistance to Chk1 inhibitors. These data further corroborate the involvement of the t(11;14) in cellular sensitivity to Chk1 inhibitors, fostering the clinical testing of Chk1 inhibitors as single agents in MCL. PMID:26439697

  3. Telomere loss, not average telomere length, confers radiosensitivity to TK6-irradiated cells

    Energy Technology Data Exchange (ETDEWEB)

    Berardinelli, F.; Nieri, D.; Sgura, A.; Tanzarella, C. [Dip. Di Biologia, Università “Roma Tre”, Rome (Italy); INFN – “Roma Tre”, Rome (Italy); Antoccia, A., E-mail: antoccia@uniroma3.it [Dip. Di Biologia, Università “Roma Tre”, Rome (Italy); INFN – “Roma Tre”, Rome (Italy)

    2012-12-15

    Highlights: ► Ionizing radiation induced telomere lengthening in TK6 clones from a single cell. ► Telomerase is not involved in the telomere lengthening observed. ► TK6 cells display very heterogeneous values in telomere length and telomere loss. ► A selective process account for telomere lengthening in irradiated cells. ► Telomere loss, not mean telomere length, is predictive of radiosensitivity. - Abstract: Many and varied are the proposed mechanisms that lead to resistance to ionizing radiation treatment. Among them, an inverse relationship between telomere length and radioresistance has been recently advanced. Investigating such a relationship in TK6 lymphoblasts, we found that clones originating from cells survived to 4 Gy of X-rays showed a significantly higher telomere length when compared with clones grown from untreated cells. The lengthening observed was not attributable to a radiation-induced increase in telomerase activity, as demonstrated by TRAP assay performed in the dose range of 1–10 Gy. Given the evidence that TK6 whole population was characterized by heterogeneity in cellular mean telomere length and telomere loss, we tested the hypothesis that a process of selection may favour cells with longer telomeres (more radioresistant cells) following exposure to irradiation. In order to do this 15 independent TK6 clones were selected and characterized for telomere length and loss on the basis of q-FISH and flow-FISH analysis. Among the screened clones four characterized by long telomeres and four characterized by short telomeres were tested for their radiosensitivity by means of clonogenic assay. The results obtained showed that, in our experimental conditions (cellular model, radiation doses) no significant correlation was observed between radiosensitivity and mean telomere lengths, whereas a positive correlation was observed with respect to telomere loss. Overall, these results indicate that telomere loss and not mean telomere length plays

  4. Resistance of oxidative stress in biofilm and planktonic cells

    Directory of Open Access Journals (Sweden)

    Witold Jakubowski

    2015-04-01

    Full Text Available This work studied the susceptibility of biofilm produced by E. coli to oxidative stress, and compared the components of free radicals defences: level of glutathione, catalase and dismutase activities in planktonic and biofilm located cells. Results showed the diversity of responses to oxidative stress in bacterial cells in log or stationary phases in both planktonic and biofilm forms. The bacteria were exposed to free-radical donors (H2O2, tBOOH, menadione, SIN-1 or peroxynitrite in a wide range of final concentrations, from 0.5 to 10mM. Different level of toxicity of individual donors, independence of cell type (planktonic forms or biofilm and phases of growth were observed. The highest oxidative stress resistance was observed for the cells in logarithmic phase of growth treated with H2O2, both in planktonic and biofilm forms, whereas for the cells in stationary phase, the highest resistance was observed for menadione. These results showed higher efficiency of agents based on superoxide anion donors in combating bacteria colonizing abiotic surfaces stainless steel (AISI 316L.

  5. Full Genome Characterization of Human Influenza A/H3N2 Isolates from Asian Countries Reveals a Rare Amantadine Resistance-Conferring Mutation and Novel PB1-F2 Polymorphisms

    Science.gov (United States)

    Zaraket, Hassan; Kondo, Hiroki; Hibino, Akinobu; Yagami, Ren; Odagiri, Takashi; Takemae, Nobuhiro; Tsunekuni, Ryota; Saito, Takehiko; Myint, Yi Yi; Kyaw, Yadanar; Oo, Khin Yi; Tin, Htay Htay; Lin, Nay; Anh, Nguyen Phuong; Hang, Nguyen Le Khanh; Mai, Le Quynh; Hassan, Mohd R.; Shobugawa, Yugo; Tang, Julian; Dbaibo, Ghassan; Saito, Reiko

    2016-01-01

    Influenza A viruses evolve at a high rate requiring continuous monitoring to maintain the efficacy of vaccines and antiviral drugs. We performed next generation sequencing analysis of 100 influenza A/H3N2 isolates collected in four Asian countries (Japan, Lebanon, Myanmar, and Vietnam) during 2012–2015. Phylogenetic analysis revealed several reassortment events leading to the circulation of multiple clades within the same season. This was particularly evident during the 2013 and 2013/2014 seasons. Importantly, our data showed that certain lineages appeared to be fitter and were able to persist into the following season. The majority of A/H3N2 viruses continued to harbor the M2-S31N mutation conferring amantadine-resistance. In addition, an S31D mutation in the M2-protein, conferring a similar level of resistance as the S31N mutation, was detected in three isolates obtained in Japan during the 2014/2015 season. None of the isolates possessed the NA-H274Y mutation conferring oseltamivir-resistance, though a few isolates were found to contain mutations at the catalytic residue 151 (D151A/G/N or V) of the NA protein. These variations did not alter the susceptibility to neuraminidase inhibitors and were not detected in the original clinical specimens, suggesting that they had been acquired during their passage in MDCK cells. Novel polymorphisms were detected in the PB1-F2 open-reading frame resulting in truncations in the protein of 24–34 aminoacids in length. Thus, this study has demonstrated the utility of monitoring the full genome of influenza viruses to allow the detection of the potentially fittest lineages. This enhances our ability to predict the strain(s) most likely to persist into the following seasons and predict the potential degree of vaccine match or mismatch with the seasonal influenza season for that year. This will enable the public health and clinical teams to prepare for any related healthcare burden, depending on whether the vaccine match is

  6. Full Genome Characterization of Human Influenza A/H3N2 Isolates from Asian Countries Reveals a Rare Amantadine Resistance-Conferring Mutation and Novel PB1-F2 Polymorphisms.

    Science.gov (United States)

    Zaraket, Hassan; Kondo, Hiroki; Hibino, Akinobu; Yagami, Ren; Odagiri, Takashi; Takemae, Nobuhiro; Tsunekuni, Ryota; Saito, Takehiko; Myint, Yi Yi; Kyaw, Yadanar; Oo, Khin Yi; Tin, Htay Htay; Lin, Nay; Anh, Nguyen Phuong; Hang, Nguyen Le Khanh; Mai, Le Quynh; Hassan, Mohd R; Shobugawa, Yugo; Tang, Julian; Dbaibo, Ghassan; Saito, Reiko

    2016-01-01

    Influenza A viruses evolve at a high rate requiring continuous monitoring to maintain the efficacy of vaccines and antiviral drugs. We performed next generation sequencing analysis of 100 influenza A/H3N2 isolates collected in four Asian countries (Japan, Lebanon, Myanmar, and Vietnam) during 2012-2015. Phylogenetic analysis revealed several reassortment events leading to the circulation of multiple clades within the same season. This was particularly evident during the 2013 and 2013/2014 seasons. Importantly, our data showed that certain lineages appeared to be fitter and were able to persist into the following season. The majority of A/H3N2 viruses continued to harbor the M2-S31N mutation conferring amantadine-resistance. In addition, an S31D mutation in the M2-protein, conferring a similar level of resistance as the S31N mutation, was detected in three isolates obtained in Japan during the 2014/2015 season. None of the isolates possessed the NA-H274Y mutation conferring oseltamivir-resistance, though a few isolates were found to contain mutations at the catalytic residue 151 (D151A/G/N or V) of the NA protein. These variations did not alter the susceptibility to neuraminidase inhibitors and were not detected in the original clinical specimens, suggesting that they had been acquired during their passage in MDCK cells. Novel polymorphisms were detected in the PB1-F2 open-reading frame resulting in truncations in the protein of 24-34 aminoacids in length. Thus, this study has demonstrated the utility of monitoring the full genome of influenza viruses to allow the detection of the potentially fittest lineages. This enhances our ability to predict the strain(s) most likely to persist into the following seasons and predict the potential degree of vaccine match or mismatch with the seasonal influenza season for that year. This will enable the public health and clinical teams to prepare for any related healthcare burden, depending on whether the vaccine match is

  7. CD19-CAR engineered NK-92 cells are sufficient to overcome NK cell resistance in B-cell malignancies.

    Science.gov (United States)

    Romanski, Annette; Uherek, Christoph; Bug, Gesine; Seifried, Erhard; Klingemann, Hans; Wels, Winfried S; Ottmann, Oliver G; Tonn, Torsten

    2016-07-01

    Many B-cell acute and chronic leukaemias tend to be resistant to killing by natural killer (NK) cells. The introduction of chimeric antigen receptors (CAR) into T cells or NK cells could potentially overcome this resistance. Here, we extend our previous observations on the resistance of malignant lymphoblasts to NK-92 cells, a continuously growing NK cell line, showing that anti-CD19-CAR (αCD19-CAR) engineered NK-92 cells can regain significant cytotoxicity against CD19 positive leukaemic cell lines and primary leukaemia cells that are resistant to cytolytic activity of parental NK-92 cells. The 'first generation' CAR was generated from a scFv (CD19) antibody fragment, coupled to a flexible hinge region, the CD3ζ chain and a Myc-tag and cloned into a retrovirus backbone. No difference in cytotoxic activity of NK-92 and transduced αCD19-CAR NK-92 cells towards CD19 negative targets was found. However, αCD19-CAR NK-92 cells specifically and efficiently lysed CD19 expressing B-precursor leukaemia cell lines as well as lymphoblasts from leukaemia patients. Since NK-92 cells can be easily expanded to clinical grade numbers under current Good Manufactoring Practice (cGMP) conditions and its safety has been documented in several phase I clinical studies, treatment with CAR modified NK-92 should be considered a treatment option for patients with lymphoid malignancies.

  8. Two non-target recessive genes confer resistance to the anti-oomycete microtubule inhibitor zoxamide in Phytophthora capsici.

    Directory of Open Access Journals (Sweden)

    Yang Bi

    Full Text Available This study characterized isolates of P. capsici that had developed a novel mechanism of resistance to zoxamide, which altered the minimum inhibition concentration (MIC but not the EC50. Molecular analysis revealed that the β-tubulin gene of the resistant isolates contained no mutations and was expressed at the same level as in zoxamide-sensitive isolates. This suggested that P. capsici had developed a novel non-target-site-based resistance to zoxamide. Analysis of the segregation ratio of zoxamide-resistance in the sexual progeny of the sensitive isolates PCAS1 and PCAS2 indicated that the resistance to zoxamide was controlled by one or more recessive nuclear genes. Furthermore, the segregation of resistance in the F1, F2, and BC1 progeny was in accordance with the theoretical ratios of the χ(2 test (P>0.05, which suggested that the resistance to zoxamide was controlled by two recessive genes, and that resistance to zoxamide occurred when at least one pair of these alleles was homozygous. This implies that the risk of zoxamide-resistance in P. capsici is low to moderate. Nevertheless this potential for resistance should be monitored closely, especially if two compatible mating types co-exist in the same field.

  9. The arabidopsis TIR-NB-LRR gene RAC1 confers resistance to Albugo candida (white rust) and is dependent on EDS1 but not PAD4.

    Science.gov (United States)

    Borhan, Mohammad H; Holub, Eric B; Beynon, Jim L; Rozwadowski, Kevin; Rimmer, S Roger

    2004-07-01

    Resistance to Albugo candida isolate Acem1 is conferred by a dominant gene, RAC1, in accession Ksk-1 of Arabidopsis thaliana. This gene was isolated by positional cloning and is a member of the Drosophila toll and mammalian interleukin-1 receptor (TIR) nucleotide-binding site leucine-rich repeat (NB-LRR) class of plant resistance genes. Strong identity of the TIR and NB domains was observed between the predicted proteins encoded by the Ksk-1 allele and the allele from an Acem1-susceptible accession Columbia (Col) (99 and 98%, respectively). However, major differences between the two predicted proteins occur within the LRR domain and mainly are confined to the beta-strand/beta-turn structure of the LRR. Both proteins contain 14 imperfect repeats. RAC1-mediated resistance was analyzed further using mutations in defense regulation, including: pad4-1, eds1-1, and NahG, in the presence of the RAC1 allele from Ksk-1. White rust resistance was completely abolished by eds1-1 but was not affected by either pad4-1 or NahG.

  10. Mitomycin resistance in mammalian cells expressing the bacterial mitomycin C resistance protein MCRA.

    Science.gov (United States)

    Belcourt, M F; Penketh, P G; Hodnick, W F; Johnson, D A; Sherman, D H; Rockwell, S; Sartorelli, A C

    1999-08-31

    The mitomycin C-resistance gene, mcrA, of Streptomyces lavendulae produces MCRA, a protein that protects this microorganism from its own antibiotic, the antitumor drug mitomycin C. Expression of the bacterial mcrA gene in mammalian Chinese hamster ovary cells causes profound resistance to mitomycin C and to its structurally related analog porfiromycin under aerobic conditions but produces little change in drug sensitivity under hypoxia. The mitomycins are prodrugs that are enzymatically reduced and activated intracellularly, producing cytotoxic semiquinone anion radical and hydroquinone reduction intermediates. In vitro, MCRA protects DNA from cross-linking by the hydroquinone reduction intermediate of these mitomycins by oxidizing the hydroquinone back to the parent molecule; thus, MCRA acts as a hydroquinone oxidase. These findings suggest potential therapeutic applications for MCRA in the treatment of cancer with the mitomycins and imply that intrinsic or selected mitomycin C resistance in mammalian cells may not be due solely to decreased bioactivation, as has been hypothesized previously, but instead could involve an MCRA-like mechanism. PMID:10468636

  11. Detailed Functional and Proteomic Characterization of Fludarabine Resistance in Mantle Cell Lymphoma Cells.

    Directory of Open Access Journals (Sweden)

    Lucie Lorkova

    Full Text Available Mantle cell lymphoma (MCL is a chronically relapsing aggressive type of B-cell non-Hodgkin lymphoma considered incurable by currently used treatment approaches. Fludarabine is a purine analog clinically still widely used in the therapy of relapsed MCL. Molecular mechanisms of fludarabine resistance have not, however, been studied in the setting of MCL so far. We therefore derived fludarabine-resistant MCL cells (Mino/FR and performed their detailed functional and proteomic characterization compared to the original fludarabine sensitive cells (Mino. We demonstrated that Mino/FR were highly cross-resistant to other antinucleosides (cytarabine, cladribine, gemcitabine and to an inhibitor of Bruton tyrosine kinase (BTK ibrutinib. Sensitivity to other types of anti-lymphoma agents was altered only mildly (methotrexate, doxorubicin, bortezomib or remained unaffacted (cisplatin, bendamustine. The detailed proteomic analysis of Mino/FR compared to Mino cells unveiled over 300 differentially expressed proteins. Mino/FR were characterized by the marked downregulation of deoxycytidine kinase (dCK and BTK (thus explaining the observed crossresistance to antinucleosides and ibrutinib, but also by the upregulation of several enzymes of de novo nucleotide synthesis, as well as the up-regulation of the numerous proteins of DNA repair and replication. The significant upregulation of the key antiapoptotic protein Bcl-2 in Mino/FR cells was associated with the markedly increased sensitivity of the fludarabine-resistant MCL cells to Bcl-2-specific inhibitor ABT199 compared to fludarabine-sensitive cells. Our data thus demonstrate that a detailed molecular analysis of drug-resistant tumor cells can indeed open a way to personalized therapy of resistant malignancies.

  12. Registration of durum wheat germplasm lines with combined mutations in SBEIIa and SBEIIb genes conferring increased amylose and resistant starch

    OpenAIRE

    Hazard, B; Zhang, X.; Naemeh, M; Dubcovsky, J.

    2014-01-01

    Durum wheat [Triticum turgidum L. subsp. durum (Desf.) Husn.], used in pasta, couscous, and flatbread production, is an important source of starch food products worldwide. The amylose portion of the starch forms resistant starch complexes that resist digestion and contribute to dietary fiber. Increasing the amount of amylose and resistant starch in wheat by mutating the STARCH BRANCHING ENZYME II (SBEII) genes has potential to provide human health benefits. Ethyl methane sulfonate mutations i...

  13. Melatonin overcomes resistance to clofarabine in two leukemic cell lines by increased expression of deoxycytidine kinase.

    Science.gov (United States)

    Yamanishi, Miho; Narazaki, Hidehiko; Asano, Takeshi

    2015-03-01

    Drug resistance remains a serious problem in leukemia therapy. Among newly developed nucleoside antimetabolites, clofarabine has broad cytotoxic activity showing therapeutic promise and is currently approved for relapsed acute lymphoblastic leukemia. To investigate the mechanisms responsible for clofarabine resistance, we established two clofarabine-resistant lymphoblastic leukemia cell lines from parental lines. To elucidate the mechanisms against clofarabine resistance in two newly established clofarabine-resistant cell lines, we measured the expression of export pumps multidrug resistance protein 1, multidrug resistance-associated protein 1, and ATP-binding cassette subfamily G member 2. There were no differences in the expression between clofarabine-sensitive and -resistant cell lines. Next, we determined expression of deoxycytidine kinase (dCK), which phosphorylates clofarabine to exert cytotoxicity, in clofarabine-sensitive and -resistant cells. Clofarabine-resistant cells showed significantly decreased expression of dCK RNA when compared with sensitive cells. To elucidate the mechanisms of decreased dCK expression in clofarabine-resistant cells, we analyzed the methylation status of CpG islands of the dCK promoter and found no differences in methylation status between clofarabine-sensitive and -resistant cells. Next, we measured the acetylation status of histone and found that total histone acetylation, and histone H3 and H4 acetylation on chromatin immunoprecipitation assay were significantly decreased in resistant cells. Melatonin is an indolamine that functions in the regulation of chronobiological rhythms to exert cytotoxic effects. We examined the effects of melatonin in clofarabine-resistant cells and found that melatonin treatment led to significantly increased cytotoxicity with clofarabine in resistant cells via increased acetylation. Melatonin may be a useful candidate for overcoming clofarabine resistance in two newly established clofarabine

  14. Prevalent HLA Class II Alleles in Mexico City Appear to Confer Resistance to the Development of Amebic Liver Abscess.

    Directory of Open Access Journals (Sweden)

    Eric G Hernández

    Full Text Available Amebiasis is an endemic disease and a public health problem throughout Mexico, although the incidence rates of amebic liver abscess (ALA vary among the geographic regions of the country. Notably, incidence rates are high in the northwestern states (especially Sonora with a rate of 12.57/100,000 inhabitants compared with the central region (Mexico City with a rate of 0.69/100,000 inhabitants. These data may be related to host genetic factors that are partially responsible for resistance or susceptibility. Therefore, we studied the association of the HLA-DRB1 and HLA-DQB1 alleles with resistance or susceptibility to ALA in two Mexican populations, one each from Mexico City and Sonora. Ninety ALA patients were clinically diagnosed by serology and sonography. Genomic DNA was extracted from peripheral blood mononuclear cells. To establish the genetic identity of both populations, 15 short tandem repeats (STRs were analyzed with multiplexed PCR, and the allelic frequencies of HLA were studied by PCR-SSO using LUMINEX technology. The allele frequencies obtained were compared to an ethnically matched healthy control group (146 individuals. We observed that both affected populations differed genetically from the control group. We also found interesting trends in the population from Mexico City. HLA-DQB1*02 allele frequencies were higher in ALA patients compared to the control group (0.127 vs 0.047; p= 0.01; pc= NS; OR= 2.9, 95% CI= 1.09-8.3. The less frequent alleles in ALA patients were HLA-DRB1*08 (0.118 vs 0.238 in controls; p= 0.01; pc= NS; OR= 0.42, 95% CI= 0.19-0.87 and HLA-DQB1*04 (0.109 vs 0.214; p= 0.02; pc= NS; OR= 0.40, 95% CI= 0.20-0.94. The haplotype HLA-DRB1*08/-DQB1*04 also demonstrated a protective trend against the development of this disease (0.081 vs. 0.178; p=0.02; pc=NS; OR= 0.40, 95% CI= 0.16-0.93. These trends suggest that the prevalent alleles in the population of Mexico City may be associated with protection against the

  15. Prevalent HLA Class II Alleles in Mexico City Appear to Confer Resistance to the Development of Amebic Liver Abscess

    Science.gov (United States)

    Hernández, Eric G.; Granados, Julio; Partida-Rodríguez, Oswaldo; Valenzuela, Olivia; Rascón, Edgar; Magaña, Ulises; Escamilla-Tilch, Mónica; López-Reyes, Alberto; Nieves-Ramírez, Miriam; González, Enrique; Morán, Patricia; Rojas, Liliana; Valadez, Alicia; Luna, Alexandra; Estrada, Francisco J.; Maldonado, Carmen; Ximénez, Cecilia

    2015-01-01

    Amebiasis is an endemic disease and a public health problem throughout Mexico, although the incidence rates of amebic liver abscess (ALA) vary among the geographic regions of the country. Notably, incidence rates are high in the northwestern states (especially Sonora with a rate of 12.57/100,000 inhabitants) compared with the central region (Mexico City with a rate of 0.69/100,000 inhabitants). These data may be related to host genetic factors that are partially responsible for resistance or susceptibility. Therefore, we studied the association of the HLA-DRB1 and HLA-DQB1 alleles with resistance or susceptibility to ALA in two Mexican populations, one each from Mexico City and Sonora. Ninety ALA patients were clinically diagnosed by serology and sonography. Genomic DNA was extracted from peripheral blood mononuclear cells. To establish the genetic identity of both populations, 15 short tandem repeats (STRs) were analyzed with multiplexed PCR, and the allelic frequencies of HLA were studied by PCR-SSO using LUMINEX technology. The allele frequencies obtained were compared to an ethnically matched healthy control group (146 individuals). We observed that both affected populations differed genetically from the control group. We also found interesting trends in the population from Mexico City. HLA-DQB1*02 allele frequencies were higher in ALA patients compared to the control group (0.127 vs 0.047; p= 0.01; pc= NS; OR= 2.9, 95% CI= 1.09-8.3). The less frequent alleles in ALA patients were HLA-DRB1*08 (0.118 vs 0.238 in controls; p= 0.01; pc= NS; OR= 0.42, 95% CI= 0.19-0.87) and HLA-DQB1*04 (0.109 vs 0.214; p= 0.02; pc= NS; OR= 0.40, 95% CI= 0.20-0.94). The haplotype HLA-DRB1*08/-DQB1*04 also demonstrated a protective trend against the development of this disease (0.081 vs. 0.178; p=0.02; pc=NS; OR= 0.40, 95% CI= 0.16-0.93). These trends suggest that the prevalent alleles in the population of Mexico City may be associated with protection against the development of ALA

  16. Aurora kinase B is important for antiestrogen resistant cell growth and a potential biomarker for tamoxifen resistant breast cancer

    DEFF Research Database (Denmark)

    Larsen, Sarah L; Yde, Christina W; Laenkholm, Anne-Vibeke;

    2015-01-01

    identified and the growth inhibitory effect verified by dose-response cell growth experiments. Protein expression and phosphorylation were investigated by western blot analysis. Cell cycle phase distribution and cell death were analyzed by flow cytometry. To evaluate Aurora kinase B as a biomarker...... for endocrine resistance, immunohistochemistry was performed on archival primary tumor tissue from breast cancer patients who have received adjuvant endocrine treatment with tamoxifen. RESULTS: The selective Aurora kinase B inhibitor barasertib was identified to preferentially inhibit growth of fulvestrant...... resistant T47D breast cancer cell lines. Compared with parental cells, phosphorylation of Aurora kinase B was higher in the fulvestrant resistant T47D cells. Barasertib induced degradation of Aurora kinase B, caused mitotic errors, and induced apoptotic cell death as measured by accumulation of SubG1 cells...

  17. The inverse correlation between series resistance and parallel resistance of small molecule organic solar cells

    Directory of Open Access Journals (Sweden)

    Kewei Wang

    2015-08-01

    Full Text Available Understanding the inversely correlated series resistance (Rs and parallel resistance (Rp remains a challenge. Here we report that the variation of Rs and Rp is inversely related through the morphology of the donor and acceptor interface in CuPc organic solar cells, when comparing the bilayer structure and bulk heterojunction structure. It was also found that the charge carrier concentration near the donor–acceptor interface plays an important role in the relationships of Rs and Rp under fixed interfacial morphology, which was verified by the change of Voc. The inversely correlated Rs and Rp contributes to the improvement of the fill factor, and in turn the power conversion efficiency.

  18. Inducible Expression of both ermB and ermT Conferred High Macrolide Resistance in Streptococcus gallolyticus subsp. pasteurianus Isolates in China.

    Science.gov (United States)

    Li, Meixia; Cai, Chao; Chen, Juan; Cheng, Changwei; Cheng, Guofu; Hu, Xueying; Liu, Cuiping

    2016-01-01

    Streptococcus gallolyticus subsp. pasteurianus is an under-recognized pathogen and zoonotic agent causing opportunistic infections in humans. Despite increasing recognition of this subspecies as a cause for human infectious diseases, limited information is known about its antibiotic resistance mechanism. In this study, we aim to identify the molecular mechanism underlying the high macrolide resistance of six S. gallolyticus subsp. pasteurianus isolates from dead ducklings collected in several natural outbreaks in China during 2010-2013. All isolates exhibited multi-drug resistance including high macrolide resistance (MIC ≥ 1024 mg/L for erythromycin, and 512 mg/L for clarithromycin). Efflux-encoding mefA and mefE genes were not detectable in these isolates. The presence of 23S rRNA mutations in specific isolates did not significantly change macrolide MICs. No nucleotide substitutions were found in genes encoding ribosomal proteins L4 or L22. The ermB and ermT genes were found in the genomes of all isolates. These two genes were acquired independently in one highly virulent isolate AL101002, and clustered with Tn916 and IS1216, respectively. The expression of both ermB and ermT in all isolates was erythromycin inducible and yielded comparable macrolide MICs in all six isolates. Taken together, inducible expression of both ermB and ermT conferred high macrolide resistance in these S. gallolyticus subsp. pasterianus isolates. Our findings reveal new macrolide resistance features in S. gallolyticus subsp. pasteurianus by both ermB and ermT. PMID:27669217

  19. The mecA homolog mecC confers resistance against β-lactams in Staphylococcus aureus irrespective of the genetic strain background.

    Science.gov (United States)

    Ballhausen, Britta; Kriegeskorte, André; Schleimer, Nina; Peters, Georg; Becker, Karsten

    2014-07-01

    In staphylococci, methicillin resistance is mediated by mecA-encoded penicillin-binding protein 2a (PBP2a), which has a low affinity for beta-lactams. Recently, a novel PBP2a homolog was described as being encoded by mecC, which shares only 70% similarity to mecA. To prove that mecC is the genetic determinant that confers methicillin resistance in Staphylococcus aureus, a mecC knockout strain was generated. The S. aureus ΔmecC strain showed considerably reduced oxacillin and cefoxitin MICs (0.25 and 4 μg/ml, respectively) compared to those of the corresponding wild-type methicillin-resistant S. aureus (MRSA) strain (8 and 16 μg/ml, respectively). Complementing the mutant in trans with wild-type mecC restored the resistance to oxacillin and cefoxitin. By expressing mecC and mecA in different S. aureus clonal lineages, we found that mecC mediates resistance irrespective of the genetic strain background, yielding oxacillin and cefoxitin MIC values comparable to those with mecA. In addition, we showed that mecC expression is inducible by oxacillin, which supports the assumption that a functional beta-lactam-dependent regulatory system is active in MRSA strains possessing staphylococcal cassette chromosome mec (SCCmec) type XI. In summary, we showed that mecC is inducible by oxacillin and mediates beta-lactam resistance in SCCmec type XI-carrying strains as well as in different S. aureus genetic backgrounds. Furthermore, our results could explain the comparatively low MICs for clinical mecC-harboring S. aureus isolates. PMID:24752255

  20. Silencing of MGMT with small interference RNA reversed resistance in human BCUN-resistant glioma cell lines

    Institute of Scientific and Technical Information of China (English)

    XIE Si-ming; FANG Mao; GUO Hui; ZHONG Xue-yun

    2011-01-01

    Background Our previous study had cloned two glioma cell lines SWOZ1 and SWOZ2 isolated from parental glioma cell line SWO38.The 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) resistance of SWOZ1 was higher than that of SWOZ2.Since O6-methylguanine-DNA methyltransferase (MGMT) was thought to be closely related to BCNU resistance in glioma,this study aimed to explore the function of MGMT in glioma resistant to BCNU.Methods A BCNU resistant glioma cell line SWOZ2-BCNU was established.The expression of MGMT was detected in SWOZ1,SWOZ2 and SWOZ2-BCNU.Small interferencing RNA targeting MGMT was used to silence the expression of MGMT in resistant cell lines SWOZ1 and SWOZ2-BCNU.The cytotoxicity of BCNU to these cells was measured using the cell counting kit-8 assay.Statistical analysis was carried out by one-way analysis of variance in statistical package SPSS 13.0.Results The resistance of SWOZ1 and SWOZ2-BCNU against BCNU was 4.9-fold and 5.3-fold higher than that of SWOZ2.The results of quantitative RT-PCR and Western blotting confirmed that MGMT was both significantly increased in SWOZ1 and SWOZ2-BCNU compared to SOWZ2.After transfection with small interferencing RNA targeting MGMT,a decreased level of MGMT mRNA expression in SWOZ1 and SWOZ2-BCNU for more than 75% compared to negative control was found and confirmed by Western blotting.As a result,the resistance against BCNU was reversed for about 50% both in the BCNU-resistant cell lines SWOZ1 and SWOZ2-BCNU.Conclusions Silencing MGMT with specific small interferencing RNA can reverse the BCNU resistant phenotype in these glioma cell lines.MGMT may play an important role both in intrinsic and acquired BCNU-resistance in glioma.

  1. Chloroquine enhances gefitinib cytotoxicity in gefitinib-resistant nonsmall cell lung cancer cells.

    Directory of Open Access Journals (Sweden)

    Mei-Chuan Tang

    Full Text Available Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs, including gefitinib, are effective for non-small cell lung cancer (NSCLC patients with EGFR mutations. However, these patients eventually develop resistance to EGFR-TKI. The goal of the present study was to investigate the involvement of autophagy in gefitinib resistance. We developed gefitinib-resistant cells (PC-9/gef from PC-9 cells (containing exon 19 deletion EGFR after long-term exposure in gefitinib. PC-9/gef cells (B4 and E3 were 200-fold more resistant to gefitinib than PC-9/wt cells. Compared with PC-9/wt cells, both PC-9/gefB4 and PC-9/gefE3 cells demonstrated higher basal LC3-II levels which were inhibited by 3-methyladenine (3-MA, an autophagy inhibitor and potentiated by chloroquine (CQ, an inhibitor of autophagolysosomes formation, indicating elevated autophagy in PC-9/gef cells. 3-MA and CQ concentration-dependently inhibited cell survival of both PC-9wt and PC-9/gef cells, suggesting that autophagy may be pro-survival. Furthermore, gefitinib increased LC3-II levels and autolysosome formation in both PC-9/wt cells and PC-9/gef cells. In PC-9/wt cells, CQ potentiated the cytotoxicity by low gefitinib (3 nM. Moreover, CQ overcame the acquired gefitinib resistance in PC-9/gef cells by enhancing gefitinib-induced cytotoxicity, activation of caspase 3 and poly (ADP-ribose polymerase cleavage. Using an in vivo model xenografting with PC-9/wt and PC-9/gefB4 cells, oral administration of gefitinib (50 mg/kg completely inhibited the tumor growth of PC-9/wt but not PC-9/gefB4cells. Combination of CQ (75 mg/kg, i.p. and gefitinib was more effective than gefitinib alone in reducing the tumor growth of PC-9/gefB4. Our data suggest that inhibition of autophagy may be a therapeutic strategy to overcome acquired resistance of gefitinib in EGFR mutation NSCLC patients.

  2. Quantitative proteomics as a tool to identify resistance mechanisms in erlotinib-resistant subclones of the non-small cell lung cancer cell line HCC827

    DEFF Research Database (Denmark)

    Jacobsen, Kirstine

    line HCC827. Materials & Methods: We established 3 erlotinib-resistant subclones (resistant to 10, 20, 30 µM erlotinib, respectively), and performed comparative quantitative proteomic analysis of these and the parental HCC827 cell line. The resistant subclones were examined both in absence and presence...

  3. Characterization of a mutation in the parE gene that confers fluoroquinolone resistance in Streptococcus pneumoniae.

    OpenAIRE

    Perichon, B; Tankovic, J; Courvalin, P

    1997-01-01

    We report a mutation in the parE genes of two in vitro mutants of Streptococcus pneumoniae responsible for low-level resistance to fluoroquinolones. Sequential acquisition of mutations in parE and gyrA leads to higher levels of resistance. This confirms that topoisomerase IV is the primary target of fluoroquinolones in S. pneumoniae.

  4. Overexpression of BSR1 confers broad-spectrum resistance against two bacterial diseases and two major fungal diseases in rice.

    Science.gov (United States)

    Maeda, Satoru; Hayashi, Nagao; Sasaya, Takahide; Mori, Masaki

    2016-06-01

    Broad-spectrum disease resistance against two or more types of pathogen species is desirable for crop improvement. In rice, Xanthomonas oryzae pv. oryzae (Xoo), the causal bacteria of rice leaf blight, and Magnaporthe oryzae, the fungal pathogen causing rice blast, are two of the most devastating pathogens. We identified the rice BROAD-SPECTRUM RESISTANCE 1 (BSR1) gene for a BIK1-like receptor-like cytoplasmic kinase using the FOX hunting system, and demonstrated that BSR1-overexpressing (OX) rice showed strong resistance to the bacterial pathogen, Xoo and the fungal pathogen, M. oryzae. Here, we report that BSR1-OX rice showed extended resistance against two other different races of Xoo, and to at least one other race of M. oryzae. In addition, the rice showed resistance to another bacterial species, Burkholderia glumae, which causes bacterial seedling rot and bacterial grain rot, and to Cochliobolus miyabeanus, another fungal species causing brown spot. Furthermore, BSR1-OX rice showed slight resistance to rice stripe disease, a major viral disease caused by rice stripe virus. Thus, we demonstrated that BSR1-OX rice shows remarkable broad-spectrum resistance to at least two major bacterial species and two major fungal species, and slight resistance to one viral pathogen. PMID:27436950

  5. Overexpression of Erg11p by the Regulatable GAL1 Promoter Confers Fluconazole Resistance in Saccharomyces cerevisiae

    OpenAIRE

    Kontoyiannis, Dimitrios P.; Sagar, Namita; Hirschi, Kendal D.

    1999-01-01

    The contribution of the dosage of target enzyme P-450 14α-demethylase (14αDM) to fluconazole resistance in both Candida albicans and Saccharomyces cerevisiae remains unclear. Here, we show that overexpression of Saccharomyces P-450 14αDM in S. cerevisiae, under the control of the regulatable promoter GAL1, results in azole resistance.

  6. The Ph-3 gene from Solanum pimpinellifolium encodes CC-NBS-LRR protein conferring resistance to Phytophthora infestans

    NARCIS (Netherlands)

    Zhang, C.; Liu, L.; Wang, X.; Vossen, J.H.; Li, G.; Li, T.; Zheng, Z.; Gao, J.; Guo, Y.; Visser, R.G.F.; Junming Li, J.; Bai, Y.; Du, Yongchen

    2014-01-01

    Late blight, caused by Phytophthora infestans, is one of the most destructive diseases in tomato. The resistance (R) gene Ph-3, derived from Solanum pimpinellifolium L3708, provides resistance to multiple P. infestans isolates and has been widely used in tomato breeding programmes. In our previous s

  7. The physical basis of cell survival models. A report on the physical aspects of the 6th L.H. Gray Conference

    International Nuclear Information System (INIS)

    This report is a brief summary of papers presented at the 6th L.H. Gray Conference dealing with models for the explanation of survival curves of irradiated cells. No extended critical discussion of the different models from one's own point of view is intended. However, some slight misunderstandings arising during the course of this conference make it meaningful to add a few remarks on the purpose and value of theoretical models for the effectiveness of radiation upon cells in general

  8. Isolation of human mdr DNA sequences amplified in multidrug-resistant KB carcinoma cells.

    OpenAIRE

    Roninson, I B; Chin, J E; Choi, K. G.; Gros, P.; Housman, D.E.; Fojo, A; Shen, D. W.; Gottesman, M M; Pastan, I

    1986-01-01

    The ability of tumor cells to develop simultaneous resistance to structurally different cytotoxic drugs constitutes a major problem in cancer chemotherapy. It was previously demonstrated that multidrug-resistant Chinese hamster cell lines contain an amplified, transcriptionally active DNA sequence designated mdr. This report presents evidence that multidrug-resistant sublines of human KB carcinoma cells, selected for resistance to either colchicine, vinblastine, or Adriamycin (doxorubicin), d...

  9. Two major er1 alleles confer powdery mildew resistance in three pea cultivars bred in Yunnan Province, China

    Directory of Open Access Journals (Sweden)

    Suli Sun

    2016-10-01

    Full Text Available Powdery mildew, caused by Erysiphe pisi D.C., is an important disease of pea (Pisum sativum L.. The use of cultivars carrying powdery mildew resistance alleles at the er1 locus is the most effective and economical means of controlling this disease. The objectives of this study were to screen Chinese elite pea cultivars for resistance to E. pisi and to identify the responsible gene at the er1 locus. Among the 37 pea cultivars tested, three (Yunwan 8, Yunwan 21, and Yunwan 23 were immune to E. pisi infection in phenotypic evaluations. The full-length cDNA sequences of the er1 candidate gene, PsMLO1, from the three resistant cultivars and control plants were analyzed. Comparison of the cDNA sequences of 10 clones revealed differences among the powdery mildew-resistant cultivars, susceptible controls, and wild-type cultivar Sprinter. The observed resistance in Yunwan 8 plants resulted from a point mutation (C → G at position 680 of PsMLO1 that introduced a stop codon, leading to premature termination of protein synthesis. The responsible resistance allele was identified as er1–1. Powdery mildew resistance in Yunwan 21 and Yunwan 23 plants was caused by identical insertions or deletions in PsMLO1. Three distinct PsMLO1 transcripts were observed in Yunwan 21 and Yunwan 23 plants. These transcripts were characterized by a 129-bp deletion and 155- and 220-bp insertions, respectively. The responsible resistance allele was identified as er1–2. We have characterized two important er1 alleles in three E. pisi-resistant pea cultivars bred in Yunnan Province, China. These cultivars represent important genetic resources for the breeding of powdery mildew-resistant pea cultivars.

  10. Consensus conference: multimodality management of early- and intermediate-stage non-small cell lung cancer.

    Science.gov (United States)

    Bordoni, Rodolfo

    2008-09-01

    Surgery is the mainstay of treatment in early- and intermediate-stage non-small cell lung cancer (NSCLC), yet recurrences are frequent. Studies have documented the benefits of chemotherapy administered after resection, but a number of questions remain regarding how overall outcomes can be further improved. To provide the oncology community with direction on these issues, a consensus conference of leading experts in the NSCLC field was held at the Fifth Annual Atlanta Lung Cancer Symposium on October 25-27, 2007. The available scientific literature is presented and when such literature is lacking, clinical experience is provided to support the following conclusions. Preoperative staging should be done in accordance with the National Comprehensive Cancer Network guidelines, but endoscopic fine needle aspiration of enlarged mediastinal nodes can be used, and if histology is positive for malignancy, mediastinoscopy can be avoided. Neoadjuvant systemic therapy is not generally recommended but can be considered to downstage an unresectable patient. There is currently no role for preoperative radiation or chemoradiation. Adjuvant systemic therapy is not recommended for stage IA and IB patients; however, adverse prognostic factors are acceptable reasons to consider adjuvant systemic therapy in the latter. Adjuvant systemic therapy is recommended for stage IIA, IIB, and IIIA patients, consistent with recent American Society of Clinical Oncology guidelines. A cisplatin-based regimen should be started within 60 days after surgery, but if relatively contraindicated, carboplatin is an acceptable alternative. Adjuvant radiation therapy is not recommended for N0 and N1 patients, but is used in N2 patients to decrease local recurrence. PMID:18779538

  11. Discovery of a Novel er1 Allele Conferring Powdery Mildew Resistance in Chinese Pea (Pisum sativum L.) Landraces.

    Science.gov (United States)

    Sun, Suli; Fu, Haining; Wang, Zhongyi; Duan, Canxing; Zong, Xuxiao; Zhu, Zhendong

    2016-01-01

    Pea powdery mildew, caused by Erysiphe pisi D.C., is an important disease worldwide. Deployment of resistant varieties is the main way to control this disease. This study aimed to screen Chinese pea (Pisum sativum L.) landraces resistant to E. pisi, and to characterize the resistance gene(s) at the er1 locus in the resistant landraces, and to develop functional marker(s) specific to the novel er1 allele. The 322 landraces showed different resistance levels. Among them, 12 (3.73%), 4 (1.24%) and 17 (5.28%) landraces showed immunity, high resistance and resistance to E. pisi, respectively. The other landraces appeared susceptible or highly susceptible to E. pisi. Most of the immune and highly resistant landraces were collected from Yunnan province. To characterize the resistance gene at the er1 locus, cDNA sequences of PsMLO1 gene were determined in 12 immune and four highly resistant accessions. The cDNAs of PsMLO1 from the immune landrace G0005576 produced three distinct transcripts, characterized by a 129-bp deletion, and 155-bp and 220-bp insertions, which were consistent with those of er1-2 allele. The PsMLO1 cDNAs in the other 15 resistant landraces produced identical transcripts, which had a new point mutation (T→C) at position 1121 of PsMLO1, indicating a novel er1 allele, designated as er1-6. This mutation caused a leucine to proline change in the amino acid sequence. Subsequently, the resistance allele er1-6 in landrace G0001778 was confirmed by resistance inheritance analysis and genetic mapping on the region of the er1 locus using populations derived from G0001778 × Bawan 6. Finally, a functional marker specific to er1-6, SNP1121, was developed using the high-resolution melting technique, which could be used in pea breeding via marker-assisted selection. The results described here provide valuable genetic information for Chinese pea landraces and a powerful tool for pea breeders. PMID:26809053

  12. Discovery of a Novel er1 Allele Conferring Powdery Mildew Resistance in Chinese Pea (Pisum sativum L.) Landraces.

    Science.gov (United States)

    Sun, Suli; Fu, Haining; Wang, Zhongyi; Duan, Canxing; Zong, Xuxiao; Zhu, Zhendong

    2016-01-01

    Pea powdery mildew, caused by Erysiphe pisi D.C., is an important disease worldwide. Deployment of resistant varieties is the main way to control this disease. This study aimed to screen Chinese pea (Pisum sativum L.) landraces resistant to E. pisi, and to characterize the resistance gene(s) at the er1 locus in the resistant landraces, and to develop functional marker(s) specific to the novel er1 allele. The 322 landraces showed different resistance levels. Among them, 12 (3.73%), 4 (1.24%) and 17 (5.28%) landraces showed immunity, high resistance and resistance to E. pisi, respectively. The other landraces appeared susceptible or highly susceptible to E. pisi. Most of the immune and highly resistant landraces were collected from Yunnan province. To characterize the resistance gene at the er1 locus, cDNA sequences of PsMLO1 gene were determined in 12 immune and four highly resistant accessions. The cDNAs of PsMLO1 from the immune landrace G0005576 produced three distinct transcripts, characterized by a 129-bp deletion, and 155-bp and 220-bp insertions, which were consistent with those of er1-2 allele. The PsMLO1 cDNAs in the other 15 resistant landraces produced identical transcripts, which had a new point mutation (T→C) at position 1121 of PsMLO1, indicating a novel er1 allele, designated as er1-6. This mutation caused a leucine to proline change in the amino acid sequence. Subsequently, the resistance allele er1-6 in landrace G0001778 was confirmed by resistance inheritance analysis and genetic mapping on the region of the er1 locus using populations derived from G0001778 × Bawan 6. Finally, a functional marker specific to er1-6, SNP1121, was developed using the high-resolution melting technique, which could be used in pea breeding via marker-assisted selection. The results described here provide valuable genetic information for Chinese pea landraces and a powerful tool for pea breeders.

  13. Role of Different Pfcrt and Pfmdr-1 Mutations in Conferring Resistance to Antimalaria Drugs in Plasmodium falciparum.

    Science.gov (United States)

    Ibraheem, Zaid O; Abd Majid, R; Noor, S Mohd; Sedik, H Mohd; Basir, R

    2014-01-01

    Emergence of drugs resistant strains of Plasmodium falciparum has augmented the scourge of malaria in endemic areas. Antimalaria drugs act on different intracellular targets. The majority of them interfere with digestive vacuoles (DVs) while others affect other organelles, namely, apicoplast and mitochondria. Prevention of drug accumulation or access into the target site is one of the mechanisms that plasmodium adopts to develop resistance. Plasmodia are endowed with series of transporters that shuffle drugs away from the target site, namely, pfmdr (Plasmodium falciparum multidrug resistance transporter) and pfcrt (Plasmodium falciparum chloroquine resistance transporter) which exist in DV membrane and are considered as putative markers of CQ resistance. They are homologues to human P-glycoproteins (P-gh or multidrug resistance system) and members of drug metabolite transporter (DMT) family, respectively. The former mediates drifting of xenobiotics towards the DV while the latter chucks them outside. Resistance to drugs whose target site of action is intravacuolar develops when the transporters expel them outside the DVs and vice versa for those whose target is extravacuolar. In this review, we are going to summarize the possible pfcrt and pfmdr mutation and their role in changing plasmodium sensitivity to different anti-Plasmodium drugs. PMID:25506039

  14. Valine-Resistance, a Potential Marker in Plant Cell Genetics. I. Distinction between Two Types of Valine-Resistant Tobacco Mutants Isolated from Protoplast-Derived Cells

    OpenAIRE

    Bourgin, J. P.; Goujaud, J.; Missonier, C.; Pethe, C.

    1985-01-01

    In previous experiments, seven lines of valine-resistant plants were regenerated from protoplast-derived haploid tobacco mesophyll cells which had been UV mutagenized and submitted to selection by toxic concentrations of valine. In this study we described the transmission of valine-resistance to progeny and a preliminary phenotypical and biochemical characterization of the resistant plants.—Two types were thus distinguished among the seven mutant lines. Valine-resistance of the mutants of the...

  15. SENSITIZING FOR CIS-DIAMMINEDICHLOROPLATINUM(II) ACTION BY HYPERTHERMIA IN RESISTANT CELLS

    NARCIS (Netherlands)

    KONINGS, AWT; HETTINGA, JVE; LEMSTRA, W; HUMPHREY, GB; KAMPINGA, HH

    1993-01-01

    cDDP-resistant Ehrlich ascites tumour (EAT) cells (ER cells) were tested for cellular content of total glutathione, heat sensitivity, cDDP sensitivity and synergistic effects of a combined treatment of heat and chemotherapy. In comparison with the non-resistant EAT cells (EN) the ER cells had an ele

  16. The T788G Mutation in the cyp51C Gene Confers Voriconazole Resistance in Aspergillus flavus Causing Aspergillosis

    OpenAIRE

    Liu, Wei; Sun, Yi; Chen, Wei; Liu, Weixia; Wan, Zhe; Bu, Dingfang; Li, Ruoyu

    2012-01-01

    With voriconazole (VRC) being approved as the first choice in treating invasive aspergillosis (IA) and its increasing use in treatment, a VRC-resistant strain of Aspergillus flavus, the second leading cause of IA after Aspergillus fumigatus, has emerged. The VRC-resistant strain of A. flavus was isolated for the first time from the surgical lung specimen of an IA patient with no response to VRC therapy. In order to ascertain the mechanism of VRC resistance, the azole target enzyme genes in th...

  17. Cloning and occurrence of czrC, a gene conferring cadmium and zinc resistance in MRSA CC398 Isolates

    DEFF Research Database (Denmark)

    Cavaco, Lina; Hasman, Henrik; Stegger, Marc;

    2010-01-01

    determinant, czrC, by PCR. The cloning of czrC confirmed that the zinc chloride and cadmium acetate MICs for isogenic constructs carrying this gene were increased compared to those for S. aureus RN4220. No difference in susceptibility to sodium arsenate, copper sulfate, or silver nitrate was observed. Seventy......C is encoding zinc and cadmium resistance in CC398 MRSA isolates, and that it is widespread both in humans and animals. Thus, resistance to heavy metals such as zinc and cadmium may play a role in the coselection of methicillin resistance in S. aureus....

  18. Distinct genetic alterations occur in ovarian tumor cells selected for combined resistance to carboplatin and docetaxel

    Directory of Open Access Journals (Sweden)

    Armstrong Stephen R

    2012-11-01

    Full Text Available Abstract Background Current protocols for the treatment of ovarian cancer include combination chemotherapy with a platinating agent and a taxane. However, many patients experience relapse of their cancer and the development of drug resistance is not uncommon, making successful second line therapy difficult to achieve. The objective of this study was to develop and characterize a cell line resistant to both carboplatin and docetaxel (dual drug resistant ovarian cell line and to compare this cell line to cells resistant to either carboplatin or docetaxel. Methods The A2780 epithelial endometrioid ovarian cancer cell line was used to select for isogenic carboplatin, docetaxel and dual drug resistant cell lines. A selection method of gradually increasing drug doses was implemented to avoid clonal selection. Resistance was confirmed using a clonogenic assay. Changes in gene expression associated with the development of drug resistance were determined by microarray analysis. Changes in the expression of selected genes were validated by Quantitative Real-Time Polymerase Chain Reaction (QPCR and immunoblotting. Results Three isogenic cell lines were developed and resistance to each drug or the combination of drugs was confirmed. Development of resistance was accompanied by a reduced growth rate. The microarray and QPCR analyses showed that unique changes in gene expression occurred in the dual drug resistant cell line and that genes known to be involved in resistance could be identified in all cell lines. Conclusions Ovarian tumor cells can acquire resistance to both carboplatin and docetaxel when selected in the presence of both agents. Distinct changes in gene expression occur in the dual resistant cell line indicating that dual resistance is not a simple combination of the changes observed in cell lines exhibiting single agent resistance.

  19. WRR4, a broad-spectrum TIR-NB-LRR gene from Arabidopsis thaliana that confers white rust resistance in transgenic oilseed Brassica crops.

    Science.gov (United States)

    Borhan, Mohammad Hossein; Holub, Eric B; Kindrachuk, Colin; Omidi, Mansour; Bozorgmanesh-Frad, Ghazaleh; Rimmer, S Roger

    2010-03-01

    White blister rust caused by Albugo candida (Pers.) Kuntze is a common and often devastating disease of oilseed and vegetable brassica crops worldwide. Physiological races of the parasite have been described, including races 2, 7 and 9 from Brassica juncea, B. rapa and B. oleracea, respectively, and race 4 from Capsella bursa-pastoris (the type host). A gene named WRR4 has been characterized recently from polygenic resistance in the wild brassica relative Arabidopsis thaliana (accession Columbia) that confers broad-spectrum white rust resistance (WRR) to all four of the above Al. candida races. This gene encodes a TIR-NB-LRR (Toll-like/interleukin-1 receptor-nucleotide binding-leucine-rich repeat) protein which, as with other known functional members in this subclass of intracellular receptor-like proteins, requires the expression of the lipase-like defence regulator, enhanced disease susceptibility 1 (EDS1). Thus, we used RNA interference-mediated suppression of EDS1 in a white rust-resistant breeding line of B. napus (transformed with a construct designed from the A. thaliana EDS1 gene) to determine whether defence signalling via EDS1 is functionally intact in this oilseed brassica. The eds1-suppressed lines were fully susceptible following inoculation with either race 2 or 7 isolates of Al. candida. We then transformed white rust-susceptible cultivars of B. juncea (susceptible to race 2) and B. napus (susceptible to race 7) with the WRR4 gene from A. thaliana. The WRR4-transformed lines were resistant to the corresponding Al. candida race for each host species. The combined data indicate that WRR4 could potentially provide a novel source of white rust resistance in oilseed and vegetable brassica crops.

  20. Involvement of CUL4A in Regulation of Multidrug Resistance to P-gp Substrate Drugs in Breast Cancer Cells

    Directory of Open Access Journals (Sweden)

    Yunshan Wang

    2013-12-01

    Full Text Available CUL4A encodes a core component of a cullin-based E3 ubiquitin ligase complex that regulates many critical processes such as cell cycle progression, DNA replication, DNA repair and chromatin remodeling by targeting a variety of proteins for ubiquitination and degradation. In the research described in this report we aimed to clarify whether CUL4A participates in multiple drug resistance (MDR in breast cancer cells. We first transfected vectors carrying CUL4A and specific shCUL4A into breast cancer cells and corresponding Adr cells respectively. Using reverse transcription polymerase chain reactions and western blots, we found that overexpression of CUL4A in MCF7 and MDA-MB-468 cells up-regulated MDR1/P-gp expression on both the transcription and protein levels, which conferred multidrug resistance to P-gp substrate drugs, as determined by 3-(4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide (MTT assays. On the other hand, silencing CUL4A in MCF7/Adr and MDA-MB-468/Adr cells led to the opposite effect. Moreover, ERK1/2 in CUL4A-overexpressing cells was highly activated and after treatment with PD98059, an ERK1/2-specific inhibitor, CUL4A-induced expression of MDR1/P-gp was decreased significantly. Lastly, immunohistochemistry in breast cancer tissues showed that P-gp expression had a positive correlation with the expression of CUL4A and ERK1/2. Thus, these results implied that CUL4A and ERK1/2 participated in multi-drug resistance in breast cancer through regulation of MDR1/P-gp expression.

  1. Autophagy is involved in doxorubicin induced resistance of human myeloma cell line RP-MI8226

    Institute of Scientific and Technical Information of China (English)

    潘耀柱

    2013-01-01

    Objective To explore the role of autophagy in doxorubicin (DOX) -induced resistance of human myeloma cell line RPMI8226.Methods We established doxorubicin induced resistant subline of myeloma cell line RPMI8226/DOX by drug concentration step-elevation method.Resistant index of DOX was measured by MTT

  2. Cloning and Occurrence of czrC, a Gene Conferring Cadmium and Zinc Resistance in Methicillin-Resistant Staphylococcus aureus CC398 Isolates

    OpenAIRE

    Cavaco, L.M.; Hasman, H.; Stegger, M.; Andersen, P S; Skov, R.; Fluit, A. C.; Ito, T.; Aarestrup, F. M.

    2010-01-01

    We recently reported a phenotypic association between reduced susceptibility to zinc and methicillin resistance in Staphylococcus aureus CC398 isolates from Danish swine (F. M. Aarestrup, L. M. Cavaco, and H. Hasman, Vet. Microbiol. 142:455-457, 2009). The aim of this study was to identify the genetic determinant causing zinc resistance in CC398 and examine its prevalence in isolates of animal and human origin. Based on the sequence of the staphylococcal cassette chromosome mec (SCCmec) eleme...

  3. Magnesium homeostasis in colon carcinoma LoVo cells sensitive or resistant to doxorubicin.

    Science.gov (United States)

    Castiglioni, Sara; Cazzaniga, Alessandra; Trapani, Valentina; Cappadone, Concettina; Farruggia, Giovanna; Merolle, Lucia; Wolf, Federica I; Iotti, Stefano; Maier, Jeanette A M

    2015-11-13

    Neoplastic cells accumulate magnesium, an event which provides selective advantages and is frequently associated with TRPM7 overexpression. Little is known about magnesium homeostasis in drug-resistant cancer cells. Therefore, we used the colon cancer LoVo cell model and compared doxorubicin-resistant to sensitive cells. In resistant cells the concentration of total magnesium is higher while its influx capacity is lower than in sensitive cells. Accordingly, resistant cells express lower amounts of the TRPM6 and 7, both involved in magnesium transport. While decreased TRPM6 levels are due to transcriptional regulation, post-transcriptional events are involved in reducing the amounts of TRPM7. Indeed, the calpain inhibitor calpeptin markedly increases the levels of TRPM7 in resistant cells. In doxorubicin-sensitive cells, silencing TRPM7 shifts the phenotype to one more similar to resistant cells, since in these cells silencing TRPM7 significantly decreases the influx of magnesium, increases its intracellular concentration and increases resistance to doxorubicin. On the other hand, calpain inhibition upregulates TRPM7, decreases intracellular magnesium and enhances the sensitivity to doxorubicin of resistant LoVo cells. We conclude that in LoVo cells drug resistance is associated with alteration of magnesium homeostasis through modulation of TRPM7. Our data suggest that TRPM7 expression may be an additional undisclosed player in chemoresistance.

  4. Role of Different Pfcrt and Pfmdr-1 Mutations in Conferring Resistance to Antimalaria Drugs in Plasmodium falciparum

    OpenAIRE

    Zaid O. Ibraheem; Abd Majid, R.; S. Mohd Noor; H. Mohd. Sedik; Basir, R.

    2014-01-01

    Emergence of drugs resistant strains of Plasmodium falciparum has augmented the scourge of malaria in endemic areas. Antimalaria drugs act on different intracellular targets. The majority of them interfere with digestive vacuoles (DVs) while others affect other organelles, namely, apicoplast and mitochondria. Prevention of drug accumulation or access into the target site is one of the mechanisms that plasmodium adopts to develop resistance. Plasmodia are endowed with series of transporters th...

  5. An AFLP marker linked to the Pm-1 gene that confers resistance to Podosphaera xanthii race 1 in Cucumis melo

    OpenAIRE

    Ana Paula Matoso Teixeira; Fatima Aparecida da Silva Barreto; Luis Eduardo Aranha Camargo

    2008-01-01

    Brazil produced 330,000 metric tons of melons in 2005, principally in the Northeast region where one of the most important melon pathogens is the powdery mildew fungus Podosphaera xanthii. The disease is controlled mainly by incorporating single dominant resistance genes into commercial hybrids. We report on linkage analysis of the Pm-1 resistance gene, introgressed from the AF125Pm-1 Cantalupensis Charentais-type breeding line into the yellow-fleshed melon (Group Inodorus) breeding line AF42...

  6. BH3 Mimetics Reactivate Autophagic Cell Death in Anoxia-Resistant Malignant Glioma Cells

    Directory of Open Access Journals (Sweden)

    Holger Hetschko

    2008-08-01

    Full Text Available Here, we investigated the specific roles of Bcl-2 family members in anoxia tolerance of malignant glioma. Flow cytometry analysis of cell death in 17 glioma cell lines revealed drastic differences in their sensitivity to oxygen withdrawal (<0.1% O2. Cell death correlated with mitochondrial depolarization, cytochrome C release, and translocation of green fluorescent protein (GFP-tagged light chain 3 to autophagosomes but occurred in the absence of caspase activation or phosphatidylserine exposure. In both sensitive and tolerant glioma cell lines, anoxia caused a significant up-regulation of BH3-only genes previously implicated in mediating anoxic cell death in other cell types (BNIP3, NIX, PUMA, and Noxa. In contrast, we detected a strong correlation between anoxia resistance and high expression levels of antiapoptotic Bcl-2 family proteins Bcl-xL, Bcl-2, and Mcl-1 that function to neutralize the proapoptotic activity of BH3-only proteins. Importantly, inhibition of both Bcl-2 and Bcl-xL with the small-molecule BH3 mimetics HA14-1 and BH3I-2′ and by RNA interference reactivated anoxia-induced autophagic cell death in previously resistant glioma cells. Our data suggest that endogenous BH3-only protein induction may not be able to compensate for the high expression of antiapoptotic Bcl-2 family proteins in anoxia-resistant astrocytomas. They also support the conjecture that BH3 mimetics may represent an exciting new approach for the treatment of malignant glioma.

  7. Exploiting mitochondrial dysfunction for effective elimination of imatinib-resistant leukemic cells.

    Directory of Open Access Journals (Sweden)

    Jérome Kluza

    Full Text Available Challenges today concern chronic myeloid leukemia (CML patients resistant to imatinib. There is growing evidence that imatinib-resistant leukemic cells present abnormal glucose metabolism but the impact on mitochondria has been neglected. Our work aimed to better understand and exploit the metabolic alterations of imatinib-resistant leukemic cells. Imatinib-resistant cells presented high glycolysis as compared to sensitive cells. Consistently, expression of key glycolytic enzymes, at least partly mediated by HIF-1α, was modified in imatinib-resistant cells suggesting that imatinib-resistant cells uncouple glycolytic flux from pyruvate oxidation. Interestingly, mitochondria of imatinib-resistant cells exhibited accumulation of TCA cycle intermediates, increased NADH and low oxygen consumption. These mitochondrial alterations due to the partial failure of ETC were further confirmed in leukemic cells isolated from some imatinib-resistant CML patients. As a consequence, mitochondria generated more ROS than those of imatinib-sensitive cells. This, in turn, resulted in increased death of imatinib-resistant leukemic cells following in vitro or in vivo treatment with the pro-oxidants, PEITC and Trisenox, in a syngeneic mouse tumor model. Conversely, inhibition of glycolysis caused derepression of respiration leading to lower cellular ROS. In conclusion, these findings indicate that imatinib-resistant leukemic cells have an unexpected mitochondrial dysfunction that could be exploited for selective therapeutic intervention.

  8. γ-Synuclein confers both pro-invasive and doxorubicin-mediated pro-apoptotic properties to the colon adenocarcinoma LS 174T cell line.

    Science.gov (United States)

    Goh, Kai-Wey; Say, Yee-How

    2015-09-01

    γ-synuclein, a neuronal protein of the synuclein family, is involved in carcinogenesis. To investigate its role in colorectal cancer carcinogenesis, we overexpressed γ-synuclein in LS 174T colon adenocarcinoma cell line (termed LS 174T-γsyn). When compared with untransfected/mock transfectants, LS 174T-γsyn had higher mobility in scratch wound assay, tend to scatter more in cell-scattering assay, and had enhanced lamellipodia and filopodia formation in cell-spreading assay. Enhanced adhesion of LS 174T-γsyn to fibronectin and collagen and significantly higher proliferation rate showed that γ-synuclein was able to increase extracellular matrix interaction and promoted proliferation of LS 174T. Higher invasiveness of LS 174T-γsyn was evidenced by enhanced invasion to the bottom of the basement membrane in Boyden chamber assay. However, LS 174T-γsyn were significantly more vulnerable to doxorubicin, vincristine and hydrogen peroxide insults, via apoptotic cell death. LS 174T-γsyn also had reduced anchorage-independent growth as shown by reduced colony formation and reduced anoikis resistance. We found that overexpression of γ-synuclein confers both pro-invasive and doxorubicin-mediated pro-apoptotic properties to LS 174T, where the former was mediated through enhanced cyclic adenosine monophosphate response element binding protein (CREB) phosphorylation, while the latter involved hepatocyte growth factor (HGF) downregulation and subsequent downstream signalling pathways possibly involving extracellular signal-regulated kinases (ERK)1/2, p38α, c-Jun N-terminal kinase (JNK) pan and Signal Transducers and Activators of Transcription (STATs). This unexpected contrasting finding as compared to other similar studies on colon cancer cell lines might be correlated with the degree of tumour advancement from which the cell lines were derived from.

  9. G-749, a novel FLT3 kinase inhibitor, can overcome drug resistance for the treatment of acute myeloid leukemia

    OpenAIRE

    Lee, Hee Kyu; Kim, Hong Woo; Lee, In Yong; Lee, Jungmi; Lee, Jaekyoo; Jung, Dong Sik; Lee, Sang Yeop; Park, Sung Ho; Hwang, Haejun; Choi, Jang-Sik; Kim, Jung-Ho; Kim, Se Won; Kim, Jung Keun; Cools, Jan; Koh, Jong Sung

    2014-01-01

    A novel inhibitor G-749 is very potent against FLT3 kinase mutants including D835Y and ITD/F691L that confer resistance to PKC412 and AC220.G-749 shows several desirable characteristics to overcome other drug resistances conferred by patient plasma, FLT3 ligand, and stromal cells.

  10. Phosphorylation of eIF4E Confers Resistance to Cellular Stress and DNA-Damaging Agents through an Interaction with 4E-T: A Rationale for Novel Therapeutic Approaches.

    Directory of Open Access Journals (Sweden)

    Alba Martínez

    Full Text Available Phosphorylation of the eukaryotic translation initiation factor eIF4E is associated with malignant progression and poor cancer prognosis. Accordingly, here we have analyzed the association between eIF4E phosphorylation and cellular resistance to oxidative stress, starvation, and DNA-damaging agents in vitro. Using immortalized and cancer cell lines, retroviral expression of a phosphomimetic (S209D form of eIF4E, but not phospho-dead (S209A eIF4E or GFP control, significantly increased cellular resistance to stress induced by DNA-damaging agents (cisplatin, starvation (glucose+glutamine withdrawal, and oxidative stress (arsenite. De novo accumulation of eIF4E-containing cytoplasmic bodies colocalizing with the eIF4E-binding protein 4E-T was observed after expression of phosphomimetic S209D, but not S209A or wild-type eIF4E. Increased resistance to cellular stress induced by eIF4E-S209D was lost upon knockdown of endogenous 4E-T or use of an eIF4E-W73A-S209D mutant unable to bind 4E-T. Cancer cells treated with the Mnk1/2 inhibitor CGP57380 to prevent eIF4E phosphorylation and mouse embryonic fibroblasts derived from Mnk1/2 knockout mice were also more sensitive to arsenite and cisplatin treatment. Polysome analysis revealed an 80S peak 2 hours after arsenite treatment in cells overexpressing phosphomimetic eIF4E, indicating translational stalling. Nonetheless, a selective increase was observed in the synthesis of some proteins (cyclin D1, HuR, and Mcl-1. We conclude that phosphorylation of eIF4E confers resistance to various cell stressors and that a direct interaction or regulation of 4E-T by eIF4E is required. Further delineation of this process may identify novel therapeutic avenues for cancer treatment, and these results support the use of modern Mnk1/2 inhibitors in conjunction with standard therapy.

  11. Self-assembled micelles of amphiphilic PEGylated rapamycin for loading paclitaxel and resisting multidrug resistance cancer cells

    OpenAIRE

    W. Tian; Liu, J; Guo, Y; Shen, Y.; D. Zhou; Guo, S.

    2015-01-01

    Self-assembled micelles of amphiphilic PEG–rapamycin conjugates loaded with paclitaxel have been developed for co-delivery and simultaneous intracellular release of paclitaxel and rapamycin, bypassing the cancer cell drug resistant mechanism and maximising the synergy of dual-drug combinational therapy. This novel nanomedicine offers 20-fold improved potency over free paclitaxel against a model multidrug resistant human breast cancer cell.

  12. Characterization of DNA topoisomerase I in three SN-38 resistant human colon cancer cell lines reveals a new pair of resistance-associated mutations

    DEFF Research Database (Denmark)

    Jensen, Niels Frank; Agama, Keli; Roy, Amit;

    2016-01-01

    to irinotecan represents a major clinical problem. Since molecular alterations in Top1 may result in resistance to irinotecan, we characterized Top1 in three human colon cancer cell lines with acquired resistance to SN-38. Methods: Three SN-38 resistant (20–67 fold increased resistance) cell lines were...

  13. Shotgun label-free proteomic analysis of clubroot (Plasmodiophora brassicae resistance conferred by the gene Rcr1 in Brassica rapa

    Directory of Open Access Journals (Sweden)

    Tao Song

    2016-07-01

    Full Text Available Clubroot, caused by the plasmodiophorid pathogen Plasmodiophora brassicae, is one of the most serious diseases on Brassica crops worldwide and a major threat to canola production in western Canada. Host resistance is the key strategy for clubroot management on canola. Several clubroot resistance (CR genes have been identified, but the mechanisms associated with these CR genes are poorly understood. In the current study, a label-free shotgun proteomic approach was used to profile and compare the proteomes of B. rapa carrying and not carrying the CR gene Rcr1 upon P. brassicae infection. A total of 527 differentially accumulated proteins (DAPs were identified between the resistant and susceptible samples, and functional annotation of these DAPs indicates that the perception of P. brassicae and activation of defense responses is triggered via an unique signaling pathway distinct from common modes of recognition receptors reported with many other plant-pathogen interactions; this pathway appears to act in a calcium-independent manner through a not-well defined cascade of mitogen-activated protein kinases and may require the ubiquitin-26S proteasome related to abiotic stresses, especially the cold-stress tolerance. Both up-regulation of defense-related and down-regulation of pathogenicity-related metabolism were observed in plants carrying Rcr1, and these functions may all contribute to the clubroot resistance mediated by this CR gene. These results, combined with those of transcriptomic analysis reported earlier, improved our understanding of molecular mechanisms associated with Rcr1 and clubroot resistance at large, and identified candidate metabolites or pathways for further confirmation of specific resistance mechanisms. Deploying CR genes with different modes of action may help improve the durability of clubroot resistance.

  14. Identification and Mapping of Two New Genes Conferring Resistance to Powdery Mildew from Aegilops tauschii (Coss.) Schmal

    Institute of Scientific and Technical Information of China (English)

    Xiao-Li Sun; Di Liu; Hai-Quan Zhang; Na-Xin Huo; Rong-Hua Zhou; Ji-Zeng Jia

    2006-01-01

    Two powdery mildew resistance genes were Identified from Aegilops tauschii accessions Y201 and Y212and mapped using two different F2 populations derived from the crosses between susceptible accession Y2272 and Y201, and susceptible accession Y2263 and Y212. Genetic analysis of resistance to powdery mildew indicated that the resistance of Y201 was controlled by a single dominant gene, whereas the resistance of Y212 was controlled by a single recessive gene. We have temporarily designated these genes as PmY201 and PmY212, respectively. By bulk segregation analysis, six microsatellite markers including Xgwm174, cfd26, cfd57, cfd102, Xgwm583 and Xgwm639 were found to be linked to PmY201 with genetic distances of 5.2, 7.7, 9.6, 12.5, 20.2 and 22.1 cM, respectively. Five SSR markers, including cfd57, Xgwm182,cfd7, cfd102, and cfd12, were found to be linked to PmY212 with distances of 5.6, 7.2, 11.5, 14.7, and 18.5 cM,respectively. According to the locations of the linked markers, the two resistance genes were located in the 5DL region. Based on the chromosomal locations and the resistance patterns of the two genes, we propose that PmY201 and PmY212 are two novel powdery mildew resistance genes, and are suitable for marker-assisted selection.

  15. Multi-Electrode Resistivity Probe for Investigation of Local Temperature Inside Metal Shell Battery Cells via Resistivity: Experiments and Evaluation of Electrical Resistance Tomography

    Directory of Open Access Journals (Sweden)

    Xiaobin Hong

    2015-01-01

    Full Text Available Direct Current (DC electrical resistivity is a material property that is sensitive to temperature changes. In this paper, the relationship between resistivity and local temperature inside steel shell battery cells (two commercial 10 Ah and 4.5 Ah lithium-ion cells is innovatively studied by Electrical Resistance Tomography (ERT. The Schlumberger configuration in ERT is applied to divide the cell body into several blocks distributed in different levels, where the apparent resistivities are measured by multi-electrode surface probes. The investigated temperature ranges from −20 to 80 °C. Experimental results have shown that the resistivities mainly depend on temperature changes in each block of the two cells used and the function of the resistivity and temperature can be fitted to the ERT-measurement results in the logistical-plot. Subsequently, the dependence of resistivity on the state of charge (SOC is investigated, and the SOC range of 70%–100% has a remarkable impact on the resistivity at low temperatures. The proposed approach under a thermal cool down regime is demonstrated to monitor the local transient temperature.

  16. Yeast cell wall extract induces disease resistance against bacterial and fungal pathogens in Arabidopsis thaliana and Brassica crop.

    Directory of Open Access Journals (Sweden)

    Mari Narusaka

    Full Text Available Housaku Monogatari (HM is a plant activator prepared from a yeast cell wall extract. We examined the efficacy of HM application and observed that HM treatment increased the resistance of Arabidopsis thaliana and Brassica rapa leaves to bacterial and fungal infections. HM reduced the severity of bacterial leaf spot and anthracnose on A. thaliana and Brassica crop leaves with protective effects. In addition, gene expression analysis of A. thaliana plants after treatment with HM indicated increased expression of several plant defense-related genes. HM treatment appears to induce early activation of jasmonate/ethylene and late activation of salicylic acid (SA pathways. Analysis using signaling mutants revealed that HM required SA accumulation and SA signaling to facilitate resistance to the bacterial pathogen Pseudomonas syringae pv. maculicola and the fungal pathogen Colletotrichum higginsianum. In addition, HM-induced resistance conferred chitin-independent disease resistance to bacterial pathogens in A. thaliana. These results suggest that HM contains multiple microbe-associated molecular patterns that activate defense responses in plants. These findings suggest that the application of HM is a useful tool that may facilitate new disease control methods.

  17. Resistance assessment for oxathiapiprolin in Phytophthora capsici and the detection of a point mutation (G769W in PcORP1 that confers resistance

    Directory of Open Access Journals (Sweden)

    Jianqiang eMiao

    2016-04-01

    Full Text Available The potential for oxathiapiprolin resistance in Phytophthora capsici was evaluated. The baseline sensitivities of 175 isolates to oxathiapiprolin were initially determinated and found to conform to a unimodal curve with a mean EC50 value of 5.61×10-4 μg/ml. Twelve stable oxathiapiprolin-resistant mutants were generated by fungicide adaption in two sensitive isolates, LP3 and HNJZ10. The fitness of the LP3-mutants was found to be similar to or better than that of the parental isolate LP3, while the HNJZ10-mutants were found to have lost the capacity to produce zoospores. Taken together these results suggest that the risk of P. capsici developing resistance to oxathiapiprolin is moderate. Comparison of the PcORP1 genes in the LP3-mutants and wild-type parental isolate, which encode the target protein of oxathiapiprolin, revealed that a heterozygous mutation caused the amino acid substitution G769W. Transformation and expression of the mutated PcORP1-769W allele in the sensitive wild-type isolate BYA5 confirmed that the mutation in PcORP1 was responsible for the observed oxathiapiprolin resistance. Finally diagnostic tests including As-PCR and CAPs were developed to detect the oxathiapiprolin resistance resulting from the G769W point mutation in field populations of P. capsici.

  18. The role of RAD51 in etoposide (VP16) resistance in small cell lung cancer

    DEFF Research Database (Denmark)

    Hansen, Lasse Tengbjerg; Lundin, Cecilia; Spang-Thomsen, Mogens;

    2003-01-01

    Etoposide (VP16) is a potent inducer of DNA double-strand breaks (DSBs) and is efficiently used in small cell lung cancer (SCLC) therapy. However, acquired VP16 resistance remains an important barrier to effective treatment. To understand the underlying mechanisms for VP16 resistance in SCLC, we...... investigated DSB repair and cellular VP16 sensitivity of SCLC cells. VP16 sensitivity and RAD51, DNA-PK(cs), topoisomerase IIalpha and P-glycoprotein protein levels were determined in 17 SCLC cell lines. In order to unravel the role of RAD51 in VP16 resistance, we cloned the human RAD51 gene, transfected SCLC...... cells with RAD51 sense or antisense constructs and measured the VP16 resistance. Finally, we measured VP16-induced DSBs in the 17 SCLC cell lines. Two cell lines exhibited a multidrug-resistant phenotype. In the other SCLC cell lines, the cellular VP16 resistance was positively correlated with the RAD51...

  19. Genetic mapping, marker assisted selection and allelic relationships for the Pu 6 gene conferring rust resistance in sunflower.

    Science.gov (United States)

    Bulos, Mariano; Vergani, Pablo Nicolas; Altieri, Emiliano

    2014-09-01

    Rust resistance in the sunflower line P386 is controlled by Pu 6 , a gene which was reported to segregate independently from other rust resistant genes, such as R 4 . The objectives of this work were to map Pu 6 , to provide and validate molecular tools for its identification, and to determine the linkage relationship of Pu 6 and R 4 . Genetic mapping of Pu 6 with six markers covered 24.8 cM of genetic distance on the lower end of linkage Group 13 of the sunflower consensus map. The marker most closely linked to Pu 6 was ORS316 at 2.5 cM in the distal position. ORS316 presented five alleles when was assayed with a representative set of resistant and susceptible lines. Allelism test between Pu 6 and R 4 indicated that both genes are linked at a genetic distance of 6.25 cM. This is the first confirmation based on an allelism test that at least two members of the R adv /R 4 /R 11 / R 13a /R 13b /Pu 6 cluster of genes are at different loci. A fine elucidation of the architecture of this complex locus will allow designing and constructing completely new genomic regions combining genes from different resistant sources and the elimination of the linkage drag around each resistant gene.

  20. Island cotton Gbve1 gene encoding a receptor-like protein confers resistance to both defoliating and non-defoliating isolates of Verticillium dahliae.

    Directory of Open Access Journals (Sweden)

    Baolong Zhang

    Full Text Available Verticillium wilt caused by soilborne fungus Verticillium dahliae could significantly reduce cotton yield. Here, we cloned a tomato Ve homologous gene, Gbve1, from an island cotton cultivar that is resistant to Verticillium wilt. We found that the Gbve1 gene was induced by V. dahliae and by phytohormones salicylic acid, jasmonic acid, and ethylene, but not by abscisic acid. The induction of Gbve1 in resistant cotton was quicker and stronger than in Verticillium-susceptible upland cotton following V. dahliae inoculation. Gbve1 promoter-driving GUS activity was found exclusively in the vascular bundles of roots and stems of transgenic Arabidopsis. Virus-induced silencing of endogenous genes in resistant cotton via targeting a fragment of the Gbve1 gene compromised cotton resistance to V. dahliae. Furthermore, we transformed the Gbve1 gene into Arabidopsis and upland cotton through Agrobacterium-mediated transformation. Overexpression of the Gbve1 gene endowed transgenic Arabidopsis and upland cotton with resistance to high aggressive defoliating and non-defoliating isolates of V. dahliae. And HR-mimic cell death was observed in the transgenic Arabidopsis. Our results demonstrate that the Gbve1 gene is responsible for resistance to V. dahliae in island cotton and can be used for breeding cotton varieties that are resistant to Verticillium wilt.

  1. Increased UV resistance in xeroderma pigmentosum group A cells after transformation with a human genomic DNA clone

    International Nuclear Information System (INIS)

    Xeroderma pigmentosum (XP) is an autosomal recessive disease in which the major clinical manifestation is a 2,000-fold enhanced probability of developing sunlight-induced skin tumors, and the molecular basis for the disease is a defective DNA excision repair system. To clone the gene defective XP complementation group A (XP-A), cDNA clones were isolated by a competition hybridization strategy in which the corresponding mRNAs were more abundant in cells of the obligately heterozygous parents relative to cells to the homozygous proband affected with the disease. In this report, a human genomic DNA clone that contains this cDNA was transformed into two independent homozygous XP-A cell lines, and these transformants displayed partial restoration of resistance to the killing effects of UV irradiation. The abundance of mRNA corresponding to this cDNA appears to correlate well with the observed UV cell survival. The results of unscheduled DNA synthesis after UV exposure indicate that the transformed cells are repair proficient relative to that of the control XP-A cells. However, using this same genomic DNA, transformation of an XP-F cell line did not confer any enhancement of UV survival or promote unscheduled DNA synthesis after UV exposure

  2. The Cfr rRNA methyltransferase confers resistance to Phenicols, Lincosamides, Oxazolidinones, Pleuromutilins, and Streptogramin A antibiotics

    DEFF Research Database (Denmark)

    Long, K. S.; Poehlsgaard, Jacob; Kehrenberg, C.;

    2006-01-01

    A novel multidrug resistance phenotype mediated by the Cfr rRNA methyltransferase is observed in Staphylococcus aureus and Escherichia coli. The cfr gene has previously been identified as a phenicol and lincosamide resistance gene on plasmids isolated from Staphylococcus spp. of animal origin...... and recently shown to encode a methyltransferase that modifies 23S rRNA at A2503. Antimicrobial susceptibility testing shows that S. aureus and E. coli strains expressing the cfr gene exhibit elevated MICs to a number of chemically unrelated drugs. The phenotype is named PhLOPSA for resistance to the following...... drug classes: Phenicols, Lincosamides, Oxazolidinones, Pleuromutilins, and Streptogramin A antibiotics. Each of these five drug classes contains important antimicrobial agents that are currently used in human and/or veterinary medicine. We find that binding of the PhLOPSA drugs, which bind...

  3. Multidrug resistance P-glycoprotein dampens SR-BI cholesteryl ester uptake from high density lipoproteins in human leukemia cells.

    Science.gov (United States)

    Spolitu, Stefano; Uda, Sabrina; Deligia, Stefania; Frau, Alessandra; Collu, Maria; Angius, Fabrizio; Batetta, Barbara

    2016-01-01

    Tumor cells are characterised by a high content of cholesterol esters (CEs), while tumor-bearing patients show low levels of high-density lipoproteins (HDLs). The origin and significance of high CE levels in cancer cell biology has not been completely clarified. Recent evidence that lymphoblastic cells selectively acquire exogenous CE from HDL via the scavenger receptor SR-BI has drawn attention to the additional membrane proteins involved in this pathway. P-glycopotein-MDR1 (P-gp) is a product of the MDR1 gene and confers resistance to antitumor drugs. Its possible role in plasma membrane cholesterol trafficking and CE metabolism has been suggested. In the present study this aspect was investigated in a lymphoblastic cell line selected for MDR1 resistance. CEM were made resistant by stepwise exposure to low (LR) and high (HR) doses of vincristine (VCR). P-gp activity ((3)H-vinblastine), CE content, CE and triglycerides (TG) synthesis ((14)C-oleate), neutral lipids and Dil-HDL uptake (fluorescence), SR-BI, ABCA1 and P-gp protein expression (western blotting) were determined. To better evaluate the relationship between CE metabolism and P-gp activity, the ACAT inhibitor Sandoz-58035 and the P-gp inhibitors progesterone, cyclosporine and verapamil were used. CE content and synthesis were similar in the parental and resistant cells. However, in the latter population, SR-BI protein expression increased, whereas CE-HDL uptake decreased. These changes correlated with the degree of VCR-resistance. As well as reverting MDR1-resistance, the inhibitors of P-gp activity induced the CE-HDL/SR-BI pathway by reactivating membrane cholesterol trafficking. Indeed, CE-HDL uptake, SRBI expression and CE content increased, whereas there was a decrease in cholesterol esterification. These results demonstrated that P-gp overexpression impairs anticancer drug uptake as well as the SR-BI mediated selective CE-HDL uptake. This suggests that these membrane proteins act in an opposite

  4. Identifying clinically relevant drug resistance genes in drug-induced resistant cancer cell lines and post-chemotherapy tissues.

    Science.gov (United States)

    Tong, Mengsha; Zheng, Weicheng; Lu, Xingrong; Ao, Lu; Li, Xiangyu; Guan, Qingzhou; Cai, Hao; Li, Mengyao; Yan, Haidan; Guo, You; Chi, Pan; Guo, Zheng

    2015-12-01

    Until recently, few molecular signatures of drug resistance identified in drug-induced resistant cancer cell models can be translated into clinical practice. Here, we defined differentially expressed genes (DEGs) between pre-chemotherapy colorectal cancer (CRC) tissue samples of non-responders and responders for 5-fluorouracil and oxaliplatin-based therapy as clinically relevant drug resistance genes (CRG5-FU/L-OHP). Taking CRG5-FU/L-OHP as reference, we evaluated the clinical relevance of several types of genes derived from HCT116 CRC cells with resistance to 5-fluorouracil and oxaliplatin, respectively. The results revealed that DEGs between parental and resistant cells, when both were treated with the corresponding drug for a certain time, were significantly consistent with the CRG5-FU/L-OHP as well as the DEGs between the post-chemotherapy CRC specimens of responders and non-responders. This study suggests a novel strategy to extract clinically relevant drug resistance genes from both drug-induced resistant cell models and post-chemotherapy cancer tissue specimens.

  5. Silibinin reverses drug resistance in human small-cell lung carcinoma cells

    Science.gov (United States)

    Sadava, David; Kane, Susan E.

    2014-01-01

    Small-cell lung carcinoma (SCLC) has a dismal prognosis in part because of multidrug resistance (MDR). Silibinin is a flavonolignan extracted from milk thistle (Silybum marianum), extracts of which are used in traditional medicine. We tested the effects of silibinin on drug-sensitive (H69) and multi-drug resistant (VPA17) SCLC cells. VPA17 cells did not show resistance to silibinin (IC50 = 60µM for H69 and VPA17). Flow cytometry analysis after incubation in 30 µM silibinin showed no changes in cell cycle phases in VPA17 or H69 cells compared with untreated cells. Silibinin (30 µM) incubation was pro-apoptotic in VPA17 cells after >3 days, as measured by ELISA of BUdR labeled DNA fragments. Apoptosis was also indicated by an increase in caspase-3 specific activity and decrease in survivin in VPA17 MDR cells. VPA17 cells had increased Pgp -mediated efflux of calcein acetoxymethyl ester (calcein AM); however, this was inhibited in cells pre-incubated in silibinin for 5 days. Pre-incubation of VPA17 cells in 30 µM silibinin for 5 days also reversed resistance to etoposide (IC50 = 5.50 uM to 0.65 µM) and doxorubicin (IC50 = 0.620 µM to 0.035 µM). The possible synergistic relationship between silibinin and chemotherapy drugs was determined by exposure of VPA17 cells to 1:1 ratios of their respective IC50 values, with serial dilutions at 0.25–2.0 × IC50 and calculation of the combination index (CI). Silibinin and etoposide showed synergism (CI = 0.46 at ED50), as did silibinin and doxorubicin (CI = 0.24 at ED50). These data indicate that in SCLC, silibinin is pro-apoptotic, reverses MDR and acts synergistically with chemotherapy drugs. Silibinin, a non-toxic natural product may be useful in the treatment of drug-resistant SCLC. PMID:23879966

  6. FoxM1 mediated resistance to gefitinib in non-small-cell lung cancer cells

    Institute of Scientific and Technical Information of China (English)

    Nuo XU; Xin ZHANG; Xun WANG; Hai-yan GE; Xiao-ying WANG; David GARFIELD; Ping YANG; Yuan-lin SONG; Chun-xue BAI

    2012-01-01

    Gefitinib is effective in only approximately 20% of patients with non-small-cell lung cancer (NSCLC),and the underlying mechanism remains unclear.FoxM1 is upregulated in NSCLC and associated with a poor prognosis in NSCLC patients.In this study,we examined the possible role of FoxM1 in gefitinib resistance and the related mechanisms.Methods:Gefitinib resistant human lung adenocarcinoma cell line SPC-A-1 and gefitinib-sensitive human lung mucoepidermoid carcinoma cell line NCI-H292 were used.mRNA and protein expression of FoxM1 and other factors were tested with quantitative RT PCR and Western blot analysis.RNA interference was performed to suppress FoxM1 expression in SPC-A-1 cells,and lentiviral infection was used to overexpress FoxM1 in H292 cells.MTT assay and flow cytometry were used to examine the proliferation and apoptosis of the cells.Results:Treatment of SPC-A-1 cells with gefitinib (1 and 10 μmol/L) upregulated the expression of FoxM1 in time- and concentrationdependent manners,while gefrtinib (1 μmol/L) downregulated in H292 cells.In SPC-A-1 cells treated with gefitinib (1 μmol/L),the expression of several downstream targets of FoxM1,including survivin,cyclin B1,SKP2,PLK1,Aurora B kinase and CDC25B,were significantly upregulated.Overexpression of FoxM1 increased the resistance in H292 cells,while attenuated FoxM1 expression restored the sensitivity to gefitinib in SPC-A-1 cells by inhibiting proliferation and inducing apoptosis.Conclusion:The results suggest that FoxM1 plays an important role in the resistance of NSCLC cells to gefitinib in vitro.FoxM1 could be used as a therapeutic target to overcome the resistance to gefitinib.

  7. The insulin-like growth factor 1 receptor causes acquired resistance to erlotinib in lung cancer cells with the wild-type epidermal growth factor receptor.

    Science.gov (United States)

    Suda, Kenichi; Mizuuchi, Hiroshi; Sato, Katsuaki; Takemoto, Toshiki; Iwasaki, Takuya; Mitsudomi, Tetsuya

    2014-08-15

    Epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitor (TKI) therapy often provides a dramatic response in lung cancer patients with EGFR mutations. In addition, moderate clinical efficacy of the EGFR-TKI, erlotinib, has been shown in lung cancer patients with the wild-type EGFR. Numerous molecular mechanisms that cause acquired resistance to EGFR-TKIs have been identified in lung cancers with the EGFR mutations; however, few have been reported in lung cancers with the wild-type EGFR. We used H358 lung adenocarcinoma cells lacking EGFR mutations that showed modest sensitivity to erlotinib. The H358 cells acquired resistance to erlotinib via chronic exposure to the drug. The H358 erlotinib-resistant (ER) cells do not have a secondary EGFR mutation, neither MET gene amplification nor PTEN downregulation; these have been identified in lung cancers with the EGFR mutations. From comprehensive screening of receptor tyrosine kinase phosphorylation, we observed increased phosphorylation of insulin-like growth factor 1 receptor (IGF1R) in H358ER cells compared with parental H358 cells. H358ER cells responded to combined therapy with erlotinib and NVP-AEW541, an IGF1R-TKI. Our results indicate that IGF1R activation is a molecular mechanism that confers acquired resistance to erlotinib in lung cancers with the wild-type EGFR. PMID:24458568

  8. Altered cell cycle regulation helps stem-like carcinoma cells resist apoptosis

    OpenAIRE

    Dalton Stephen; Chappell James

    2010-01-01

    Abstract Reemergence of carcinomas following chemotherapy and/or radiotherapy is not well understood, but a recent study in BMC Cancer suggests that resistance to apoptosis resulting from altered cell cycle regulation is crucial. See research article: http://biomedcentral.com/1471-2407/10/166

  9. Reversible resistance induced by FLT3 inhibition: a novel resistance mechanism in mutant FLT3-expressing cells.

    Directory of Open Access Journals (Sweden)

    Ellen Weisberg

    Full Text Available Clinical responses achieved with FLT3 kinase inhibitors in acute myeloid leukemia (AML are typically transient and partial. Thus, there is a need for identification of molecular mechanisms of clinical resistance to these drugs. In response, we characterized MOLM13 AML cell lines made resistant to two structurally-independent FLT3 inhibitors.MOLM13 cells were made drug resistant via prolonged exposure to midostaurin and HG-7-85-01, respectively. Cell proliferation was determined by Trypan blue exclusion. Protein expression was assessed by immunoblotting, immunoprecipitation, and flow cytometry. Cycloheximide was used to determine protein half-life. RT-PCR was performed to determine FLT3 mRNA levels, and FISH analysis was performed to determine FLT3 gene expression.We found that MOLM13 cells readily developed cross-resistance when exposed to either midostaurin or HG-7-85-01. Resistance in both lines was associated with dramatically elevated levels of cell surface FLT3 and elevated levels of phosphor-MAPK, but not phospho-STAT5. The increase in FLT3-ITD expression was at least in part due to reduced turnover of the receptor, with prolonged half-life. Importantly, the drug-resistant phenotype could be rapidly reversed upon withdrawal of either inhibitor. Consistent with this phenotype, no significant evidence of FLT3 gene amplification, kinase domain mutations, or elevated levels of mRNA was observed, suggesting that protein turnover may be part of an auto-regulatory pathway initiated by FLT3 kinase activity. Interestingly, FLT3 inhibitor resistance also correlated with resistance to cytosine arabinoside. Over-expression of FLT3 protein in response to kinase inhibitors may be part of a novel mechanism that could contribute to clinical resistance.

  10. Cloning and Occurrence of czrC, a Gene Conferring Cadmium and Zinc Resistance in Methicillin-Resistant Staphylococcus aureus CC398 Isolates

    NARCIS (Netherlands)

    Cavaco, L. M.; Hasman, H.; Stegger, M.; Andersen, P. S.; Skov, R.; Fluit, A. C.; Ito, T.; Aarestrup, F. M.

    2010-01-01

    We recently reported a phenotypic association between reduced susceptibility to zinc and methicillin resistance in Staphylococcus aureus CC398 isolates from Danish swine (F. M. Aarestrup, L. M. Cavaco, and H. Hasman, Vet. Microbiol. 142: 455-457, 2009). The aim of this study was to identify the gene

  11. tcrB, a gene conferring transferable copper resistance in Enterococcus faecium: occurrence, transferability, and linkage to macrolide and glycopeptide resistance

    DEFF Research Database (Denmark)

    Hasman, Henrik; Aarestrup, Frank Møller

    2002-01-01

    B protein from Enterococcus hirae. The tcrB gene was found in E. faecium isolated from pigs (75%), broilers (34%), calves (16%), and humans (10%) but not in isolates from sheep. Resistant isolates, containing the tcrB gene, grew on brain heart infusion agar plates containing up to 28 mM CuSO4 compared...

  12. Mutations in the nonstructural protein 3A confer resistance to the novel enterovirus replication inhibitor TTP-8307.

    NARCIS (Netherlands)

    Palma, A.M. De; Thibaut, H.J.; Linden, L. van de; Lanke, K.H.W.; Heggermont, W.; Ireland, S.; Andrews, R.; Arimilli, M.; Al-Tel, T.H.; Clercq, E. De; Kuppeveld, F.J.M. van; Neyts, J.

    2009-01-01

    A novel compound, TTP-8307, was identified as a potent inhibitor of the replication of several rhino- and enteroviruses. TTP-8307 inhibits viral RNA synthesis in a dose-dependent manner, without affecting polyprotein synthesis and/or processing. Drug-resistant variants of coxsackievirus B3 were all

  13. AFLP markers for the R-gene in the flea beetle, Phyllotreta nemorum, conferring resistance to defenses in Barbarea vulgaris

    NARCIS (Netherlands)

    Breuker, C.J.; Victoir, K.; Jong, de P.W.; Meijden, van der E.; Brakefield, P.M.; Vrieling, K.

    2005-01-01

    A so-called R-gene renders the yellow-striped flea beetle Phyllotreta nemorum L. (Coleoptera: Chrysomelidae: Alticinae) resistant to the defenses of the yellow rocket Barbarea vulgaris R.Br. (Brassicacea) and enables it to use it as a host plant in Denmark. In this study, genetic markers for an auto

  14. Resistance to downy mildew in lettuce ‘La Brillante’ is conferred by dm50 gene and multiple QTL

    Science.gov (United States)

    Many cultivars of lettuce (Lactuca sativa L.) are susceptible to downy mildew, a nearly globally ubiquitous disease caused by Bremia lactucae. We previously determined that Batavia type cultivar La Brillante has a high level of field resistance to the disease in California. Testing of a mapping popu...

  15. Correlation between Twist expression and multidrug resistance of breast cancer cell lines

    Institute of Scientific and Technical Information of China (English)

    Yue-Xi Wang; Xiao-Mei Chen; Jun Yan; Zhi-Ping Li

    2016-01-01

    Objective:To study the correlation between Twist expression and multidrug resistance of breast cancer cell lines. Methods:Human breast cancer cell lines MCF-7, cisplatin-resistant human breast cancer cell lines MCF-7/DDP, doxorubicin-resistant human breast cancer cell lines MCF-7/Adr and taxol-resistant human breast cancer cell lines MCF/PTX were cultured, Twist in human breast cancer cell lines MCF-7 was overexpressed and treated with doxorubicin, and then cell viability and expression levels of EMT marker molecules and related signaling pathway molecules were detected. Results:mRNA contents and protein contents of Twist in drug-resistant breast cancer cell lines MCF-7/DDP, MCF-7/Adr and MCF/PTX were higher than those in MCF-7 cell lines;after doxorubicin treatment, inhibitory rates of cell viability in MCF-7 cell lines were higher than those in MCF-7/Adr and MCF-7/Twist cell lines;E-cadherin expression levels in MCF-7/Adr cell lines and MCF-7/Twist cell lines were lower than those in MCF-7 cell lines, and mRNA contents and protein contents of N-cadherin, Vimentin, TGF-β, Smad, Wnt,β-catenin, TNF-αand NF-kB were higher than those in MCF-7 cell lines. Conclusion:Increased expression of Twist is associated with the occurrence of drug resistance in breast cancer cells.

  16. Silencing of the host factor eIF(iso)4E gene confers plum pox virus resistance in plum.

    Science.gov (United States)

    Wang, Xinhua; Kohalmi, Susanne E; Svircev, Antonet; Wang, Aiming; Sanfaçon, Hélène; Tian, Lining

    2013-01-01

    Plum pox virus (PPV) causes the most economically-devastating viral disease in Prunus species. Unfortunately, few natural resistance genes are available for the control of PPV. Recessive resistance to some potyviruses is associated with mutations of eukaryotic translation initiation factor 4E (eIF4E) or its isoform eIF(iso)4E. In this study, we used an RNA silencing approach to manipulate the expression of eIF4E and eIF(iso)4E towards the development of PPV resistance in Prunus species. The eIF4E and eIF(iso)4E genes were cloned from plum (Prunus domestica L.). The sequence identity between plum eIF4E and eIF(iso)4E coding sequences is 60.4% at the nucleotide level and 52.1% at the amino acid level. Quantitative real-time RT-PCR analysis showed that these two genes have a similar expression pattern in different tissues. Transgenes allowing the production of hairpin RNAs of plum eIF4E or eIF(iso)4E were introduced into plum via Agrobacterium-mediated transformation. Gene expression analysis confirmed specific reduced expression of eIF4E or eIF(iso)4E in the transgenic lines and this was associated with the accumulation of siRNAs. Transgenic plants were challenged with PPV-D strain and resistance was evaluated by measuring the concentration of viral RNA. Eighty-two percent of the eIF(iso)4E silenced transgenic plants were resistant to PPV, while eIF4E silenced transgenic plants did not show PPV resistance. Physical interaction between PPV-VPg and plum eIF(iso)4E was confirmed. In contrast, no PPV-VPg/eIF4E interaction was observed. These results indicate that eIF(iso)4E is involved in PPV infection in plum, and that silencing of eIF(iso)4E expression can lead to PPV resistance in Prunus species.

  17. Silencing of the host factor eIF(iso4E gene confers plum pox virus resistance in plum.

    Directory of Open Access Journals (Sweden)

    Xinhua Wang

    Full Text Available Plum pox virus (PPV causes the most economically-devastating viral disease in Prunus species. Unfortunately, few natural resistance genes are available for the control of PPV. Recessive resistance to some potyviruses is associated with mutations of eukaryotic translation initiation factor 4E (eIF4E or its isoform eIF(iso4E. In this study, we used an RNA silencing approach to manipulate the expression of eIF4E and eIF(iso4E towards the development of PPV resistance in Prunus species. The eIF4E and eIF(iso4E genes were cloned from plum (Prunus domestica L.. The sequence identity between plum eIF4E and eIF(iso4E coding sequences is 60.4% at the nucleotide level and 52.1% at the amino acid level. Quantitative real-time RT-PCR analysis showed that these two genes have a similar expression pattern in different tissues. Transgenes allowing the production of hairpin RNAs of plum eIF4E or eIF(iso4E were introduced into plum via Agrobacterium-mediated transformation. Gene expression analysis confirmed specific reduced expression of eIF4E or eIF(iso4E in the transgenic lines and this was associated with the accumulation of siRNAs. Transgenic plants were challenged with PPV-D strain and resistance was evaluated by measuring the concentration of viral RNA. Eighty-two percent of the eIF(iso4E silenced transgenic plants were resistant to PPV, while eIF4E silenced transgenic plants did not show PPV resistance. Physical interaction between PPV-VPg and plum eIF(iso4E was confirmed. In contrast, no PPV-VPg/eIF4E interaction was observed. These results indicate that eIF(iso4E is involved in PPV infection in plum, and that silencing of eIF(iso4E expression can lead to PPV resistance in Prunus species.

  18. Mechanisms for high methoxymorpholino doxorubicin cytotoxicity in doxorubicin-resistant tumor cell lines

    NARCIS (Netherlands)

    Bakker, M; Renes, J; Groenhuijzen, A; Visser, P; TimmerBosscha, H; Muller, M; Groen, HJM; Smit, EF; deVries, EGE

    1997-01-01

    Methoxymorpholino doxorubicin (MMRDX) is an anthracycline analogue that is able to overcome tumor cell resistance to classical anthracyclines. Mechanisms for increased MMRDX cytotoxicity were analyzed in a small cell lung carcinoma cell line (GLC(4)), its 300-fold doxorubicin-resistant and multidrug

  19. BNYVV-derived dsRNA confers resistance to rhizomania disease of sugar beet as evidenced by a novel transgenic hairy root approach.

    Science.gov (United States)

    Pavli, Ourania I; Panopoulos, Nicholas J; Goldbach, Rob; Skaracis, George N

    2010-10-01

    Agrobacterium rhizogenes-transformed sugar beet hairy roots, expressing dsRNA from the Beet necrotic yellow vein virus replicase gene, were used as a novel approach to assess the efficacy of three intron-hairpin constructs at conferring resistance to rhizomania disease. Genetically engineered roots were similar in morphology to wild type roots but were characterized by a profound abundancy, rapid growth rate and, in some cases, plagiotropic development. Upon challenge inoculation, seedlings showed a considerable delay in symptom development compared to untransformed or vector-transformed seedlings, expressing dsRNA from an unrelated source. The transgenic root system of almost all seedlings contained no or very low virus titer while the non-transformed aerial parts of the same plants were found infected, leading to the conclusion that the hairy roots studied were effectively protected against the virus. This readily applicable novel method forms a plausible approach to preliminarily evaluate transgenic rhizomania resistance before proceeding in transformation and whole plant regeneration of sugar beet, a tedious and time consuming process for such a recalcitrant crop species.

  20. BNYVV-derived dsRNA confers resistance to rhizomania disease of sugar beet as evidenced by a novel transgenic hairy root approach.

    Science.gov (United States)

    Pavli, Ourania I; Panopoulos, Nicholas J; Goldbach, Rob; Skaracis, George N

    2010-10-01

    Agrobacterium rhizogenes-transformed sugar beet hairy roots, expressing dsRNA from the Beet necrotic yellow vein virus replicase gene, were used as a novel approach to assess the efficacy of three intron-hairpin constructs at conferring resistance to rhizomania disease. Genetically engineered roots were similar in morphology to wild type roots but were characterized by a profound abundancy, rapid growth rate and, in some cases, plagiotropic development. Upon challenge inoculation, seedlings showed a considerable delay in symptom development compared to untransformed or vector-transformed seedlings, expressing dsRNA from an unrelated source. The transgenic root system of almost all seedlings contained no or very low virus titer while the non-transformed aerial parts of the same plants were found infected, leading to the conclusion that the hairy roots studied were effectively protected against the virus. This readily applicable novel method forms a plausible approach to preliminarily evaluate transgenic rhizomania resistance before proceeding in transformation and whole plant regeneration of sugar beet, a tedious and time consuming process for such a recalcitrant crop species. PMID:20127510

  1. TCRP1 contributes to cisplatin resistance by preventing Pol β degradation in lung cancer cells.

    Science.gov (United States)

    Liu, Xiaorong; Wang, Chengkun; Gu, Yixue; Zhang, Zhijie; Zheng, Guopei; He, Zhimin

    2015-01-01

    Cisplatin (DDP) is the first-line chemotherapy drug widely used for the treatment of lung cancer patients, whereas the majority of cancer patients will eventually show resistance to DDP. The mechanisms responsible for DDP resistance are not fully understood. Tongue cancer resistance-associated protein 1 (TCRP1) gene was recently cloned and reported to specially mediate DDP resistance in human oral squamous cell carcinoma (OSCC) cells. However, the mechanisms of TCRP1-mediated DDP resistance are far from clear, and whether TCRP1 participates in DDP resistance in lung cancer cells remains unknown. Here, we show that TCRP1 contributes to DDP resistance in lung cancer cells. Knockdown of TCRP1 sensitizes the cells to DDP and increases the DDP-induced DNA damage. We have identified that Pol β is associated with DDP resistance, and Pol β knockdown delays the repair of DDP-induced DNA damage in A549/DDP cells. We find TCRP1 interacts with Pol β in lung cancer cells. Moreover, TCRP1 knockdown decreases the level of Pol β and increases the level of its ubiquitination. These results suggest that TCRP1 contributes to DDP resistance through the prevention of Pol β degradation in lung cancer cells. These findings provide new insights into chemoresistance and may contribute to prevention and reversal of DDP resistance in treatment of lung cancer in the future.

  2. Studies of resistance factors against chloroethylnitrosourea drugs in malignant tumor cells

    OpenAIRE

    Egyházi, Suzanne

    1996-01-01

    Drug resistance is a major clinical problem in the chemotherapy of tumor diseases and the identification of factors that make tumor cells resistant to drug treatment is therefore of crucial importance. We have investigated a possible involvement of O6-methylguanine-DNA methyltransferase (MGMT), glutathione transferase (GST) and glutathione (GSH) in the resistance to 1,3- bis(2-chloroethyl)- 1 -nitrosourea (BCNU) in two human lung cancer cell lines. The non-small cell lung ca...

  3. Engineering Human T Cells for Resistance to Methotrexate and Mycophenolate Mofetil as an In Vivo Cell Selection Strategy

    OpenAIRE

    Mahesh Jonnalagadda; Brown, Christine E; Wen-Chung Chang; Ostberg, Julie R.; Forman, Stephen J.; Jensen, Michael C.

    2013-01-01

    Gene transfer and drug selection systems that enforce ongoing transgene expression in vitro and in vivo which are compatible with human pharmaceutical drugs are currently underdeveloped. Here, we report on the utility of incorporating human enzyme muteins that confer resistance to the lymphotoxic/immunosuppressive drugs methotrexate (MTX) and mycophenolate mofetil (MMF) in a multicistronic lentiviral vector for in vivo T lymphocyte selection. We found that co-expression of human dihydrofolate...

  4. Role of Metallothionein1H in Cisplatin Resistance of Non-Small Cell Lung Cancer Cells

    Institute of Scientific and Technical Information of China (English)

    Xin-fang Hou; Qing-xia Fan; Liu-xing Wang; Shi-xin Lu

    2009-01-01

    Objective: Despite platinum-based adjuvant chemotherapy has improved greatly patients' outcomes, drug resistance poses a major impediment to the successful use of such an effective agent. Metallothioneins(MTs) are known to play putative roles in cancer cell proliferation, apoptosis, differentiation, drug resistance and prognosis. The present studiy was to investigte the role of metallethioein1H(MT1H) in cisplatin resistance of human non-small cell lung cancer(NSCLC) cell lines in vitro or its possible molecular mechanisms. Methods: MT1H mRNA expression in A549 and A549/DDP cells was detected by RT-PCR. A recombinant eukaryotic expression plasmid pcDNA3.1(-)-MT1H was constructed and transfected into A549 cells which express no MT1H. MT1H siRNA was transfected into A549/DDP cells which express MT1H highly. MT1H expression was detected by RT-PCR and Immunoblot. The chemosensitivity to cisplatin was assessed by MTT assay. Apoptosis rate was determined by Tunel and FCM. Bcl-2 and Bax were determined by immunohistochemistry. Results: MT1H mRNA was expressed in A549/DDP but not in A549. After transfection of MT1H, MT1H expression was enhanced and the chemosensitivity to cisplatin was decreased in A549 cells. Inversely, after transfection of MT1H siRNA, MT1H expression was decreased and the chemosensitivity to cisplatin was increased in A549/DDP. The apoptosis rate induced by cisplatin was increased and Bcl-2 was down-regulated but Bax showed little change in A549/DDP cells interferred with MT1H siRNA. Conclusion: MT1H overexpression can promote drug resistance in A549 cells . Down-regulation of MT1H interfered with siRNA can effectively reverses the drug resistance in A549/DDP cells by down-regulating the expression of Bcl-2 and increasing cisplatin induced apoptosis. SiRNA targeting MT1H combined with chemotherapy may be a very promising strategy for treatment of lung cancer.

  5. Severe insulin resistance alters metabolism in mesenchymal progenitor cells.

    Science.gov (United States)

    Balhara, Bharti; Burkart, Alison; Topcu, Vehap; Lee, Youn-Kyoung; Cowan, Chad; Kahn, C Ronald; Patti, Mary-Elizabeth

    2015-06-01

    Donohue syndrome (DS) is characterized by severe insulin resistance due to mutations in the insulin receptor (INSR) gene. To identify molecular defects contributing to metabolic dysregulation in DS in the undifferentiated state, we generated mesenchymal progenitor cells (MPCs) from induced pluripotent stem cells derived from a 4-week-old female with DS and a healthy newborn male (control). INSR mRNA and protein were significantly reduced in DS MPC (for β-subunit, 64% and 89% reduction, respectively, P consumption in both the basal state (87% higher, P =.09) and in response to the uncoupler carbonyl cyanide-p-triflouromethoxyphenylhydrazone (2-fold increase, P =.06). Although mitochondrial DNA or mass did not differ, oxidative phosphorylation protein complexes III and V were increased in DS (by 37% and 6%, respectively; P < .05). Extracellular acidification also tended to increase in DS (91% increase, P = .07), with parallel significant increases in lactate secretion (34% higher at 4 h, P < .05). In summary, DS MPC maintain signaling downstream of the INSR, suggesting that IGF-1R signaling may partly compensate for INSR mutations. However, alterations in receptor expression and pathway-specific defects in insulin signaling, even in undifferentiated cells, can alter cellular oxidative metabolism, potentially via transcriptional mechanisms. PMID:25811318

  6. Measuring turbulence in a flotation cell using electrical resistance tomography

    Science.gov (United States)

    Meng, Jun; Xie, Weiguo; Runge, Kym; Bradshaw, Dee

    2015-11-01

    Measuring turbulence in an industrial flotation environment has long been problematic due to the opaque, aggressive, and abrasive three-phase environment in a flotation cell. One of the promising measurement techniques is electrical resistance tomography (ERT). By measuring the conductivity distribution across a measurement area, ERT has been adopted by many researchers to monitor and investigate many processes involving multiphase flows. In the research outlined in this paper, a compact ERT probe was built and then used to measure the conductivity distribution within a 60 l flotation cell operated with water and air. Two approaches were then developed to process the ERT data and estimate turbulence-related parameters. One is a conductivity variance method and the other is based on the Green-Kubo relations. Both rely on and use the fluctuation in the ERT measurement caused by bubbles moving through the measurement area changing the density of the fluid. The results from both approaches were validated by comparing the results produced by the ERT probe in a 60l flotation cell operated at different air rates and impeller speeds to that measured using an alternative turbulence measurement device. The second approach is considered superior to the first as the first requires the development of auxiliary information which would not usually be known for a new system.

  7. Cytomegalovirus-Infected Cells Resist T Cell Mediated Killing in an HLA-Recognition Independent Manner.

    Science.gov (United States)

    Proff, Julia; Walterskirchen, Christian; Brey, Charlotte; Geyeregger, Rene; Full, Florian; Ensser, Armin; Lehner, Manfred; Holter, Wolfgang

    2016-01-01

    In order to explore the potential of HLA-independent T cell therapy for human cytomegalovirus (HCMV) infections, we developed a chimeric antigen receptor (CAR) directed against the HCMV encoded glycoprotein B (gB), which is expressed at high levels on the surface of infected cells. T cells engineered with this anti-gB CAR recognized HCMV-infected cells and released cytokines and cytotoxic granules. Unexpectedly, and in contrast to analogous approaches for HIV, Hepatitis B or Hepatitis C virus, we found that HCMV-infected cells were resistant to killing by the CAR-modified T cells. In order to elucidate whether this phenomenon was restricted to the use of CARs, we extended our experiments to T cell receptor (TCR)-mediated recognition of infected cells. To this end we infected fibroblasts with HCMV-strains deficient in viral inhibitors of antigenic peptide presentation and targeted these HLA-class I expressing peptide-loaded infected cells with peptide-specific cytotoxic T cells (CTLs). Despite strong degranulation and cytokine production by the T cells, we again found significant inhibition of lysis of HCMV-infected cells. Impairment of cell lysis became detectable 1 day after HCMV infection and gradually increased during the following 3 days. We thus postulate that viral anti-apoptotic factors, known to inhibit suicide of infected host cells, have evolved additional functions to directly abrogate T cell cytotoxicity. In line with this hypothesis, CAR-T cell cytotoxicity was strongly inhibited in non-infected fibroblasts by expression of the HCMV-protein UL37x1, and even more so by additional expression of UL36. Our data extend the current knowledge on Betaherpesviral evasion from T cell immunity and show for the first time that, beyond impaired antigen presentation, infected cells are efficiently protected by direct blockade of cytotoxic effector functions through viral proteins.

  8. Study of the resistance mechanisms to ultraviolet light in Escherichia Coli. III. Genetic mapping of a mutation that confers resistance to radiation

    International Nuclear Information System (INIS)

    Inside this third work with respect to the investigation of the process of adaptation of different subcultures of Escherichia coli, to the UV light, its are present the obtained results in the identification of the gene or genes implied in the resistance to UV of one of the 5 populations derived for repeated exposure to growing dose of UV light of E. coli PQ30. Those obtained data indicate that the causing mutation of the phenotype is located in a single gene, since the insert of the fragment of DNA miniTn5 in this gene, causes the lost one from the resistance and the return to the original phenotype. The gene in question is denominated radA, located in the minute 99.6 of the chromosome of E. coli and required for the efficient repair of double ruptures in the DNA. (Author)

  9. Multidrug resistance and retroviral transduction potential in human small cell lung cancer cell lines

    DEFF Research Database (Denmark)

    Theilade, M D; Gram, G J; Jensen, P B;

    1999-01-01

    blue colonies after X-Gal staining of the cells grown in soft agar. All examined SCLC cell lines were transducible with either vector. Transduction efficiencies varied from 5.7% to 33.5% independent of the presence of MDR. These results indicate that MDR does not severely impair transduction of SCLC......Multidrug resistance (MDR) remains a major problem in the successful treatment of small cell lung cancer (SCLC). New treatment strategies are needed, such as gene therapy specifically targeting the MDR cells in the tumor. Retroviral LacZ gene-containing vectors that were either pseudotyped for the...... gibbon ape leukemia virus (GALV-1) receptor or had specificity for the amphotropic murine leukemia virus (MLV-A) receptor were used for transduction of five SCLC cell lines differing by a range of MDR mechanisms. Transduction efficiencies in these cell lines were compared by calculating the percentage of...

  10. Multidrug resistance and retroviral transduction potential in human small cell lung cancer cell lines

    DEFF Research Database (Denmark)

    Theilade, M D; Gram, G J; Jensen, P B;

    1999-01-01

    Multidrug resistance (MDR) remains a major problem in the successful treatment of small cell lung cancer (SCLC). New treatment strategies are needed, such as gene therapy specifically targeting the MDR cells in the tumor. Retroviral LacZ gene-containing vectors that were either pseudotyped...... for the gibbon ape leukemia virus (GALV-1) receptor or had specificity for the amphotropic murine leukemia virus (MLV-A) receptor were used for transduction of five SCLC cell lines differing by a range of MDR mechanisms. Transduction efficiencies in these cell lines were compared by calculating the percentage...... of blue colonies after X-Gal staining of the cells grown in soft agar. All examined SCLC cell lines were transducible with either vector. Transduction efficiencies varied from 5.7% to 33.5% independent of the presence of MDR. These results indicate that MDR does not severely impair transduction of SCLC...

  11. Resistance to paclitaxel in a cisplatin-resistant ovarian cancer cell line is mediated by P-glycoprotein.

    Directory of Open Access Journals (Sweden)

    Britta Stordal

    Full Text Available The IGROVCDDP cisplatin-resistant ovarian cancer cell line is also resistant to paclitaxel and models the resistance phenotype of relapsed ovarian cancer patients after first-line platinum/taxane chemotherapy. A TaqMan low-density array (TLDA was used to characterise the expression of 380 genes associated with chemotherapy resistance in IGROVCDDP cells. Paclitaxel resistance in IGROVCDDP is mediated by gene and protein overexpression of P-glycoprotein and the protein is functionally active. Cisplatin resistance was not reversed by elacridar, confirming that cisplatin is not a P-glycoprotein substrate. Cisplatin resistance in IGROVCDDP is multifactorial and is mediated in part by the glutathione pathway and decreased accumulation of drug. Total cellular glutathione was not increased. However, the enzyme activity of GSR and GGT1 were up-regulated. The cellular localisation of copper transporter CTR1 changed from membrane associated in IGROV-1 to cytoplasmic in IGROVCDDP. This may mediate the previously reported accumulation defect. There was decreased expression of the sodium potassium pump (ATP1A, MRP1 and FBP which all have been previously associated with platinum accumulation defects in platinum-resistant cell lines. Cellular localisation of MRP1 was also altered in IGROVCDDP shifting basolaterally, compared to IGROV-1. BRCA1 was also up-regulated at the gene and protein level. The overexpression of P-glycoprotein in a resistant model developed with cisplatin is unusual. This demonstrates that P-glycoprotein can be up-regulated as a generalised stress response rather than as a specific response to a substrate. Mechanisms characterised in IGROVCDDP cells may be applicable to relapsed ovarian cancer patients treated with frontline platinum/taxane chemotherapy.

  12. Map-based Cloning and Characterization of the BPH18 Gene from Wild Rice Conferring Resistance to Brown Planthopper (BPH) Insect Pest

    Science.gov (United States)

    Ji, Hyeonso; Kim, Sung-Ryul; Kim, Yul-Ho; Suh, Jung-Pil; Park, Hyang-Mi; Sreenivasulu, Nese; Misra, Gopal; Kim, Suk-Man; Hechanova, Sherry Lou; Kim, Hakbum; Lee, Gang-Seob; Yoon, Ung-Han; Kim, Tae-Ho; Lim, Hyemin; Suh, Suk-Chul; Yang, Jungil; An, Gynheung; Jena, Kshirod K.

    2016-01-01

    Brown planthopper (BPH) is a phloem sap-sucking insect pest of rice which causes severe yield loss. We cloned the BPH18 gene from the BPH-resistant introgression line derived from the wild rice species Oryza australiensis. Map-based cloning and complementation test revealed that the BPH18 encodes CC-NBS-NBS-LRR protein. BPH18 has two NBS domains, unlike the typical NBS-LRR proteins. The BPH18 promoter::GUS transgenic plants exhibited strong GUS expression in the vascular bundles of the leaf sheath, especially in phloem cells where the BPH attacks. The BPH18 proteins were widely localized to the endo-membranes in a cell, including the endoplasmic reticulum, Golgi apparatus, trans-Golgi network, and prevacuolar compartments, suggesting that BPH18 may recognize the BPH invasion at endo-membranes in phloem cells. Whole genome sequencing of the near-isogenic lines (NILs), NIL-BPH18 and NIL-BPH26, revealed that BPH18 located at the same locus of BPH26. However, these two genes have remarkable sequence differences and the independent NILs showed differential BPH resistance with different expression patterns of plant defense-related genes, indicating that BPH18 and BPH26 are functionally different alleles. These findings would facilitate elucidation of the molecular mechanism of BPH resistance and the identified novel alleles to fast track breeding BPH resistant rice cultivars. PMID:27682162

  13. Drug resistance in rat colon cancer cell lines is associated with minor changes in susceptibility to cytotoxic cells

    NARCIS (Netherlands)

    W. van de Vrie (Wim); S.A.M. van der Heyden (Sylke); E.E.O. Gheuens (Eric); H.H. Bijma (Hilmar); E.A. de Bruijn (Ernst); R.L. Marquet (Richard); A.T. van Oosterom (Allan); A.M.M. Eggermont (Alexander)

    1993-01-01

    textabstractThe development of resistance to anticancer drugs urges the search for different treatment modalities. Several investigators have reported the concomitant development of drug resistance and resistance to natural killer (NK), lymphokine-activated killer (LAK) or monocyte/macrophage cell l

  14. Yeast cells with impaired drug resistance accumulate glycerol and glucose.

    Science.gov (United States)

    Dikicioglu, Duygu; Oc, Sebnem; Rash, Bharat M; Dunn, Warwick B; Pir, Pınar; Kell, Douglas B; Kirdar, Betul; Oliver, Stephen G

    2014-01-01

    Multiple drug resistance (MDR) in yeast is effected by two major superfamilies of membrane transporters: the major facilitator superfamily (MFS) and the ATP-binding cassette (ABC) superfamily. In the present work, we investigated the cellular responses to disruptions in both MFS (by deleting the transporter gene, QDR3) and ABC (by deleting the gene for the Pdr3 transcription factor) transporter systems by growing diploid homozygous deletion yeast strains in glucose- or ammonium-limited continuous cultures. The transcriptome and the metabolome profiles of these strains, as well as the flux distributions in the optimal solution space, reveal novel insights into the underlying mechanisms of action of QDR3 and PDR3. Our results show how cells rearrange their metabolism to cope with the problems that arise from the loss of these drug-resistance genes, which likely evolved to combat chemical attack from bacterial or fungal competitors. This is achieved through the accumulation of intracellular glucose, glycerol, and inorganic phosphate, as well as by repurposing genes that are known to function in other parts of metabolism in order to minimise the effects of toxic compounds. PMID:24157722

  15. A cfr-Like Gene from Clostridium difficile Confers Multiple Antibiotic Resistance by the Same Mechanism as the cfr Gene

    DEFF Research Database (Denmark)

    Hansen, Lykke H; Vester, Birte

    2015-01-01

    The Cfr RNA methyltransferase causes multiple resistances to peptidyl transferase inhibitors by methylation of A2503 23S rRNA. Many cfr-like gene sequences in the databases code for unknown functions. This study confirms that a Cfr-like protein from a Peptoclostridium difficile (formerly Clostrid......The Cfr RNA methyltransferase causes multiple resistances to peptidyl transferase inhibitors by methylation of A2503 23S rRNA. Many cfr-like gene sequences in the databases code for unknown functions. This study confirms that a Cfr-like protein from a Peptoclostridium difficile (formerly...... Clostridium difficile) strain does function as a Cfr protein. The enzyme is expressed in Escherichia coli and shows elevated MICs for five classes of antibiotics. A primer extension stop indicates a modification at A2503 in 23S rRNA....

  16. Shotgun Label-free Proteomic Analysis of Clubroot (Plasmodiophora brassicae) Resistance Conferred by the Gene Rcr1 in Brassica rapa

    Science.gov (United States)

    Song, Tao; Chu, Mingguang; Lahlali, Rachid; Yu, Fengqun; Peng, Gary

    2016-01-01

    Clubroot, caused by the plasmodiophorid pathogen Plasmodiophora brassicae, is one of the most serious diseases on Brassica crops worldwide and a major threat to canola production in western Canada. Host resistance is the key strategy for clubroot management on canola. Several clubroot resistance (CR) genes have been identified, but the mechanisms associated with these CR genes are poorly understood. In the current study, a label-free shotgun proteomic approach was used to profile and compare the proteomes of Brassica rapa carrying and not carrying the CR gene Rcr1 in response to P. brassicae infection. A total of 527 differentially accumulated proteins (DAPs) were identified between the resistant (with Rcr1) and susceptible (without Rcr1) samples, and functional annotation of these DAPs indicates that the perception of P. brassicae and activation of defense responses are triggered via an unique signaling pathway distinct from common modes of recognition receptors reported with many other plant–pathogen interactions; this pathway appears to act in a calcium-independent manner through a not-well-defined cascade of mitogen-activated protein kinases and may require the ubiquitin-26S proteasome found to be related to abiotic stresses, especially the cold-stress tolerance in other studies. Both up-regulation of defense-related and down-regulation of pathogenicity-related metabolism was observed in plants carrying Rcr1, and these functions may all contribute to the CR mediated by Rcr1. These results, combined with those of transcriptomic analysis reported earlier, improved our understanding of molecular mechanisms associated with Rcr1 and CR at large, and identified candidate metabolites or pathways related to specific resistance mechanisms. Deploying CR genes with different modes of action may help improve the durability of CR.

  17. A new allele conferring resistance to Lysinibacillus sphaericus is detected in low frequency in Culex quinquefasciatus field populations

    OpenAIRE

    Menezes, Heverly Suzany Gouveia; Chalegre, Karlos Diogo de Melo; Romão, Tatiany Patrícia; de Oliveira, Cláudia Maria Fontes; de-Melo-Neto, Osvaldo Pompílio; Silva-Filha, Maria Helena Neves Lobo

    2016-01-01

    Background The Cqm1 α-glucosidase of Culex quinquefasciatus larvae acts as the midgut receptor for the binary toxin of the biolarvicide Lysinibacillus sphaericus. Mutations within the cqm1 gene can code for aberrant polypeptides that can no longer be properly expressed or bind to the toxin, leading to insect resistance. The cqm1 REC and cqm1 REC-2 alleles were identified in a laboratory selected colony and both displayed mutations that lead to equivalent phenotypes of refractoriness to L. sph...

  18. Shotgun Label-free Proteomic Analysis of Clubroot (Plasmodiophora brassicae) Resistance Conferred by the Gene Rcr1 in Brassica rapa.

    Science.gov (United States)

    Song, Tao; Chu, Mingguang; Lahlali, Rachid; Yu, Fengqun; Peng, Gary

    2016-01-01

    Clubroot, caused by the plasmodiophorid pathogen Plasmodiophora brassicae, is one of the most serious diseases on Brassica crops worldwide and a major threat to canola production in western Canada. Host resistance is the key strategy for clubroot management on canola. Several clubroot resistance (CR) genes have been identified, but the mechanisms associated with these CR genes are poorly understood. In the current study, a label-free shotgun proteomic approach was used to profile and compare the proteomes of Brassica rapa carrying and not carrying the CR gene Rcr1 in response to P. brassicae infection. A total of 527 differentially accumulated proteins (DAPs) were identified between the resistant (with Rcr1) and susceptible (without Rcr1) samples, and functional annotation of these DAPs indicates that the perception of P. brassicae and activation of defense responses are triggered via an unique signaling pathway distinct from common modes of recognition receptors reported with many other plant-pathogen interactions; this pathway appears to act in a calcium-independent manner through a not-well-defined cascade of mitogen-activated protein kinases and may require the ubiquitin-26S proteasome found to be related to abiotic stresses, especially the cold-stress tolerance in other studies. Both up-regulation of defense-related and down-regulation of pathogenicity-related metabolism was observed in plants carrying Rcr1, and these functions may all contribute to the CR mediated by Rcr1. These results, combined with those of transcriptomic analysis reported earlier, improved our understanding of molecular mechanisms associated with Rcr1 and CR at large, and identified candidate metabolites or pathways related to specific resistance mechanisms. Deploying CR genes with different modes of action may help improve the durability of CR. PMID:27462338

  19. Role of Mitochondrial Translocation of Telomerase in Hepatocellular Carcinoma Cells with Multidrug Resistance

    Directory of Open Access Journals (Sweden)

    Xianlong Ling, Lei Wen, Yuan Zhou

    2012-01-01

    Full Text Available Multidrug resistance (MDR is a major obstacle of cancer chemotherapy. This study aimed to investigate the role of mitochondrial translocation of telomerase (hTERT in MDR of human hepatocellular carcinoma (HCC cells. In this study, three HCC cell lines (SK-Hep1/CDDP1 cells, SK-Hep1/CDDP2 cells and SK-Hep1/CDDP3 cells with differential resistance index (RI to cisplatin (CDDP were induced by pulse treatment of SK-Hep1 (human hepatocellular cell line with CDDP in vitro. The RI of SK-Hep1/CDDP1 cells, SK-Hep1/CDDP2 cells and SK-Hep1/CDDP3 cells was 5.14, 8.66, and 14.25, respectively, and all the cell lines showed cross-resistance to Doxorubicin (DOX and 5-Fuorouracil (5-FU. The apoptosis rates in drug-resistant cells were significantly reduced. Cell cycle analysis revealed the ratio of drug-resistant cells in G2/M and S phases increased, while that in G1 phase decreased. Immunofluorescence staining and Western blot assay demonstrated, with the gradual elevation in RI, increasing hTERT translocated from the nuclei to the mitochondria, while real-time PCR indicated the shortening of telomere length in drug-resistant cells under the chemotherapeutic stress and the reduction of damaged mtDNA with the increase in RI. Furthermore, JC-1 staining also indicated the reduction of mitochondrial membrane potential in drug-resistant cells. The mitochondrial translocation of hTERT increases in multidrug-resistant cells and exerts protective effect on mitochondrial function. Drug-resistant tumor cells escape from apoptosis through hTERT-mediated mitochondrial protection. Mitochondrial translocation of hTERT may serve as an underlying mechanism of MDR.

  20. Role of mitochondrial translocation of telomerase in hepatocellular carcinoma cells with multidrug resistance.

    Science.gov (United States)

    Ling, Xianlong; Wen, Lei; Zhou, Yuan

    2012-01-01

    Multidrug resistance (MDR) is a major obstacle of cancer chemotherapy. This study aimed to investigate the role of mitochondrial translocation of telomerase (hTERT) in MDR of human hepatocellular carcinoma (HCC) cells. In this study, three HCC cell lines (SK-Hep1/CDDP1 cells, SK-Hep1/CDDP2 cells and SK-Hep1/CDDP3 cells) with differential resistance index (RI) to cisplatin (CDDP) were induced by pulse treatment of SK-Hep1 (human hepatocellular cell line) with CDDP in vitro. The RI of SK-Hep1/CDDP1 cells, SK-Hep1/CDDP2 cells and SK-Hep1/CDDP3 cells was 5.14, 8.66, and 14.25, respectively, and all the cell lines showed cross-resistance to Doxorubicin (DOX) and 5-Fuorouracil (5-FU). The apoptosis rates in drug-resistant cells were significantly reduced. Cell cycle analysis revealed the ratio of drug-resistant cells in G2/M and S phases increased, while that in G1 phase decreased. Immunofluorescence staining and Western blot assay demonstrated, with the gradual elevation in RI, increasing hTERT translocated from the nuclei to the mitochondria, while real-time PCR indicated the shortening of telomere length in drug-resistant cells under the chemotherapeutic stress and the reduction of damaged mtDNA with the increase in RI. Furthermore, JC-1 staining also indicated the reduction of mitochondrial membrane potential in drug-resistant cells. The mitochondrial translocation of hTERT increases in multidrug-resistant cells and exerts protective effect on mitochondrial function. Drug-resistant tumor cells escape from apoptosis through hTERT-mediated mitochondrial protection. Mitochondrial translocation of hTERT may serve as an underlying mecha