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Sample records for resistant cell development

  1. 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.

  2. Development of the sulfur mustard resistant keratinocyte cell line HaCaT/SM.

    Science.gov (United States)

    Schmidt, Annette; Steinritz, Dirk; Thiermann, Horst

    2016-02-26

    Pairs of corresponding cytotoxic drug sensitive and resistant cell lines are powerful tools to develop treatment strategies. Developing cytotoxic drug resistant cell lines is a well-established method in cancer research. In more than fifty years of sulfur mustard (SM) resistant research such a cell pair has never been produced. Hereinafter we describe the first successful approach to develop a SM resistant keratinocyte cell line. Starting with the SM sensitive keratinocyte cell line HaCaT we used a strategy of continuous exposure with gradually increased concentrations. Cells were cultured in total for more than 40 months starting with an initial concentration of 0.07μM SM twice a week up to a final concentration of 7.2μM SM. The achieved cell line HaCaT/SM had an LC50 resistance increase of 4.7-fold and an LC90 increase of 8.2-fold. Hereinafter we demonstrate the production of the first sulfur mustard (SM) resistant cell line. The new achieved cell line called HaCaT/SM is able to tolerate a continuous exposure of an SM concentration, which is associated with an inhibitory effect of 93% within the original HaCaT cells, which were used as starting point. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  3. Development of hyper osmotic resistant CHO host cells for enhanced antibody production.

    Science.gov (United States)

    Kamachi, Yasuharu; Omasa, Takeshi

    2018-04-01

    Cell culture platform processes are generally employed to shorten the duration of new product development. A fed-batch process with continuous feeding is a conventional platform process for monoclonal antibody production using Chinese hamster ovary (CHO) cells. To establish a simplified platform process, the feeding method can be changed from continuous feed to bolus feed. However, this change induces a rapid increase of osmolality by the bolus addition of nutrients. The increased osmolality suppresses cell culture growth, and the final product concentration is decreased. In this study, osmotic resistant CHO host cells were developed to attain a high product concentration. To establish hyper osmotic resistant CHO host cells, CHO-S host cells were passaged long-term in a hyper osmotic basal medium. There were marked differences in cell growth of the original and established host cells under iso- (328 mOsm/kg) or hyper-osmolality (over 450 mOsm/kg) conditions. Cell growth of the original CHO host cells was markedly decreased by the induction of osmotic stress, whereas cell growth of the hyper osmotic resistant CHO host cells was not affected. The maximum viable cell concentration of hyper osmotic resistant CHO host cells was 132% of CHO-S host cells after the induction of osmotic stress. Moreover, the hyper osmotic resistant characteristic of established CHO host cells was maintained even after seven passages in iso-osmolality basal medium. The use of hyper osmotic resistance CHO host cells to create a monoclonal antibody production cell line might be a new approach to increase final antibody concentrations with a fed-batch process. Copyright © 2017 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  4. Autophagy facilitates multidrug resistance development through inhibition of apoptosis in breast cancer cells.

    Science.gov (United States)

    Sun, W L; Lan, D; Gan, T Q; Cai, Z W

    2015-01-01

    Acquired multidrug resistance (MDR) is the main mechanism of chemotherapeutic drugs resistance. Nevertheless, the mechanisms of MDR are complex and still not very clear. Recently, including our previous study, several studies have revealed that macroautophagy (here referred to as autophagy) induced by anti-cancer drugs in breast cancer cells may facilitate the development of resistance to epirubicin (EPI), paclitaxel (PTX), tamoxifen or herceptin. Whereas there are a few studies on the relationship between autophagy and MDR, especially the studies designed directly employing induced resistant breast cancer cells. Based on previous study, we explored the relationship between autophagy and MDR. The results showed that induced EPI-resistant MCF-7er and SK-BR-3er cells were simultaneously resistant to PTX and vinorelbine (NVB), which demonstrated that the cells obtained MDR phenotype. Furthermore, PTX and NVB could also induce autophagy in MCF-7er and SK-BR-3er cells, and the induced autophagy protected the cells from apoptosis, which facilitated the development of resistance to PTX and NVB. Thus, autophagy promoted the development of MDR in breast cancer cells through inhibition of apoptosis. In addition, we found that P-glycoprotein (Pgp) was overexpressed in MCF-7er and SK-Br-3er cells. And we preliminarily investigated the relationship between autophagy and P-glycoprotein (Pgp). The results showed that the expression of the protein did not obviously change despite the inhibition of autophagy. Therefore, the role of Pgp in the development of MDR might be independent of autophahy. Also this finding implies that autophagy might be a target to overcome MDR in breast cancer cells, and clinical use autophagy inhibitors might be one of the important strategies for overcoming MDR in breast cancer therapy. Autophagy, apoptosis, multidrug resistance, breast cancer, chemotherapy.

  5. Enhanced stability of microtubules contributes in the development of colchicine resistance in MCF-7 cells.

    Science.gov (United States)

    Rai, Ankit; Kapoor, Sonia; Naaz, Afsana; Kumar Santra, Manas; Panda, Dulal

    2017-05-15

    Understanding the mechanism of resistance to tubulin-targeted anticancer drugs is important for improved chemotherapy. In this work, a colchicine-resistant MCF-7 cell line (MCF-7 Col30 ) was generated by the gradual increment of colchicine treatment and the MCF-7 Col30 showed ∼8-fold resistance towards colchicine. MCF-7 Col30 cells showed ∼2.5-fold resistance against microtubule depolymerizing agents, vinblastine, and nocodazole. In contrast, it displayed more sensitivity towards paclitaxel, a microtubule-polymerizing agent. MCF-7 and MCF-7 Col30 cells showed similar sensitivity towards cisplatin. Further, the level of P-glycoprotein did not increase in MCF-7 Col30 cells. MCF-7 Col30 cells resisted the microtubule depolymerizing effects of colchicine. The time-lapse imaging of individual microtubules in live cells showed that the dynamics of microtubules in MCF-7 Col30 cells was suppressed as compared to the parent MCF-7 cells. The levels of tubulin acetylation and glutamylation increased in MCF-7 Col30 cells than the parent MCF-7 cells suggesting that microtubules are stabilized in MCF-7 Col30 cells. Interestingly, the level of βIII tubulin was increased by 2.3 folds whereas that of βII and βIV tubulin was decreased by 55 and 150%, respectively in MCF-7 Col30 cells. The results suggested that the changes in the level of β-tubulin isoforms and the post-translational modifications of microtubules altered the stability and dynamics of microtubules and contributed to the development of colchicine-resistance in MCF-7 cells. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Thymidylate synthase expression determines pemetrexed targets and resistance development in tumour cells.

    Directory of Open Access Journals (Sweden)

    Aitziber Buqué

    Full Text Available Although treatment options for cancer patients are increasing every year, the drug resistance problem remains very present. It is very difficult to find a drug that acts equally on tumours of the same histology as the individual's genetic characteristics often determine the response to treatment. Furthermore, tumours that initially respond to anti-tumour therapy are able to adapt and develop resistance to the drug, while others do not. In addition, this usually implies resistance development to agents to which the cells have not been exposed, a phenomenon called cross-resistance or multidrug resistance. Given this situation, it has been suggested that the most appropriate treatment would be able to act in parallel on multiple pathways constitutively altered in tumour cells. Pemetrexed is a multitargeted antifolate that exerts its activity against folate-dependent enzymes involved in de novo pyrimidine and purine synthesis. It is currently in use in combination with cisplatin against malignant pleural mesothelioma and non-squamous non-small cell lung cancer with favourable results. By real-time RT-PCR gene expression assays and restoration viability assays we demonstrated that Pemetrexed targets folate-dependent enzymes involved in de novo biosynthesis of purines differently depending on the intrinsic genetic characteristics of the tumour. These differences did not, however, interfere either with the initial response to the drug or with the activation of apoptotic pathways. In addition, these genetic fingerprints can differentiate two groups of tumours: those capable of developing resistance to antifolate, and not capable. These results may be useful to employ targets gene expression as resistance markers, a valuable tool for identifying patients likely to receive combination therapy to prevent the development of resistance.

  7. MicroRNA expression profiles associated with development of drug resistance in Ehrlich ascites tumor cells

    DEFF Research Database (Denmark)

    Husted, Susanne; Søkilde, Rolf; Rask, Lene

    2011-01-01

    Multidrug resistance (MDR) poses a major obstacle to successful chemotherapeutic treatment of cancer, and often involves multiple genes, which may be regulated post-transcriptionally by microRNAs (miRNAs). The purpose of the present study was therefore to identify any resistance-associated changes...... in miRNA expression in a sensitive and five increasingly drug-resistant Ehrlich ascites tumor (EAT) cell lines, representing different steps in the development of resistance. We used an LNA-enhanced microarray platform to study the global miRNA expression profiles in the six murine EAT cell lines......, and identified growth-, hypoxia-, and resistance-specific miRNA patterns. Among the differentially expressed miRNAs, we found the two clusters miR-183∼miR-96∼miR-182 and miR-200b∼miR-200a∼miR-429 as well as miR-141 to be consistently upregulated in the MDR cell lines, while miR-125b-5p and the two clusters mi...

  8. Native cell-death genes as candidates for developing wilt resistance in transgenic banana plants.

    Science.gov (United States)

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

    2014-07-04

    In order to feed an ever-increasing world population, there is an urgent need to improve the production of staple food and fruit crops. The productivity of important food and fruit crops is constrained by numerous biotic and abiotic factors. The cultivation of banana, which is an important fruit crop, is severely threatened by Fusarium wilt disease caused by infestation by an ascomycetes fungus Fusarium oxysporum f. sp. cubense (Foc). Since there are no established edible cultivars of banana resistant to all the pathogenic races of Foc, genetic engineering is the only option for the generation of resistant cultivars. Since Foc is a hemibiotrophic fungus, investigations into the roles played by different cell-death-related genes in the progression of Foc infection on host banana plants are important. Towards this goal, three such genes namely MusaDAD1, MusaBAG1 and MusaBI1 were identified in banana. The study of their expression pattern in banana cells in response to Foc inoculation (using Foc cultures or fungal toxins like fusaric acid and beauvericin) indicated that they were indeed differentially regulated by fungal inoculation. Among the three genes studied, MusaBAG1 showed the highest up-regulation upon Foc inoculation. Further, in order to characterize these genes in the context of Foc infection in banana, we generated transgenic banana plants constitutively overexpressing the three genes that were later subjected to Foc bioassays in a contained greenhouse. Among the three groups of transgenics tested, transformed banana plants overexpressing MusaBAG1 demonstrated the best resistance towards Foc infection. Further, these plants also showed the highest relative overexpression of the transgene (MusaBAG1) among the three groups of transformed plants generated. Our study showed for the first time that native genes like MusaBAG1 can be used to develop transgenic banana plants with efficient resistance towards pathogens like Foc. Published by Oxford University Press

  9. C-fos upregulates P-glycoprotein, contributing to the development of multidrug resistance in HEp-2 laryngeal cancer cells with VCR-induced resistance.

    Science.gov (United States)

    Li, Guodong; Hu, Xiaoling; Sun, Lu; Li, Xin; Li, Jianfeng; Li, Tongli; Zhang, Xiaohui

    2018-01-01

    Laryngeal cancer tends to have a very poor prognosis due to the unsatisfactory efficacy of chemotherapy for this cancer. Multidrug resistance (MDR) is the main cause of chemotherapy failure. The proto-oncogene c-fos has been shown to be involved in the development of MDR in several tumor types, but few studies have evaluated the relationship between c-fos and MDR in laryngeal cancer. We investigated the role of c-fos in MDR development in laryngeal cancer cells (cell line: human epithelial type 2, HEp-2) using the chemotherapeutic vincristine (VCR). HEp-2/VCR drug resistance was established by selection against an increasing drug concentration gradient. The expressions of c-fos and multidrug resistance 1 (mdr1) were measured using qPCR and western blot. C-fos overexpression or knockdown was performed in various cells. The intracellular rhodamine-123 (Rh-123) accumulation assay was used to detect the transport capacity of P-glycoprotein (P-gp, which is encoded by the mdr1 gene). HEp-2 cells with VCR-induced resistance (HEp-2/VCR cells) were not only resistant to VCR but also evolved cross-resistance to other chemotherapeutic drugs. The expressions of the c-fos and mdr1genes were significantly higher in the HEp-2/VCR cells than in control cells. C-fos overexpression in HEp-2 cells (c-fos WT) resulted in increased P-gp expression and increased the IC 50 for 5-FU. C-fos knockdown in the HEp-2/VCR cells (c-fos shRNA) resulted in decreased P-gp expression and decreased IC 50 for 5-FU. An intracellular Rh-123 accumulation assay showed that the mean intracellular fluorescence intensity (MFI) was lower in the HEp-2/VCR cells than in HEp-2 cells. C-fos WT cells also showed lower MFI. By contrast, c-fos shRNA cells exhibited a higher MFI than the control group. C-fos increased the expression of P-gp and mdr1 in the HEp-2/VCR cells, and enhanced the efflux function of the cells, thereby contributing to the development of MDR.

  10. Developing Novel Therapeutics Targeting Undifferentiated and Castration-Resistant Prostate Cancer Stem Cells

    Science.gov (United States)

    2015-10-01

    in vivo cytotoxicities of the conjugated JRM2 peptide and finishing up screening and validating the kinase inhibitor library screening. 15. SUBJECT...cells were purified out and then lysed to infect bacteria K91, from which 960 and 704 tet/kan- resistant bacterial colonies were generated from GFP+ and...Figure 2A; data not shown). To determine whether JRM2 can preferentially bind to the PSA-/lo LNCaP cells, we made several versions of JRM2 conjugates

  11. Ion channels and transporters in the development of drug resistance in cancer cells

    DEFF Research Database (Denmark)

    Hoffmann, Else Kay; Lambert, Ian Henry

    2014-01-01

    Multi-drug resistance (MDR) to chemotherapy is the major challenge in the treatment of cancer. MDR can develop by numerous mechanisms including decreased drug uptake, increased drug efflux and the failure to undergo drug-induced apoptosis. Evasion of drug-induced apoptosis through modulation of ion...

  12. The Endothelial Cell: an “Early Responder” in the Development of Insulin Resistance

    OpenAIRE

    Barrett, Eugene J.; Liu, Zhenqi

    2013-01-01

    Vascular endothelium is an important insulin target and plays a pivotal role in the development of metabolic insulin resistance provoked by the Western lifestyle. It acts as a “first-responder” to environmental stimuli such as nutrients, cytokines, chemokines and physical activity and regulates insulin delivery to muscle and adipose tissue and thereby affecting insulin-mediated glucose disposal by these tissues. In addition, it also regulates the delivery of insulin and other appetite regulat...

  13. Development of a Standard Test to Assess the Resistance of Staphylococcus aureus Biofilm Cells to Disinfectants

    NARCIS (Netherlands)

    Luppens, S.B.I.; Reij, M.W.; Heijden, van der R.W.; Rombouts, F.M.; Abee, T.

    2002-01-01

    A standardized disinfectant test for Staphylococcus aureus cells in biofilms was developed. Two disinfectants, the membrane-active compound benzalkonium chloride (BAC) and the oxidizing agent sodium hypochlorite, were used to evaluate the biofilm test. S. aureus formed biofilms on glass, stainless

  14. Anti-cancer effects of newly developed chemotherapeutic agent, glycoconjugated palladium (II) complex, against cisplatin-resistant gastric cancer cells

    International Nuclear Information System (INIS)

    Tanaka, Mamoru; Kamiya, Takeshi; Joh, Takashi; Kataoka, Hiromi; Yano, Shigenobu; Ohi, Hiromi; Kawamoto, Keisuke; Shibahara, Takashi; Mizoshita, Tsutomu; Mori, Yoshinori; Tanida, Satoshi

    2013-01-01

    Cisplatin (CDDP) is the most frequently used chemotherapeutic agent for various types of advanced cancer, including gastric cancer. However, almost all cancer cells acquire resistance against CDDP, and this phenomenon adversely affects prognosis. Thus, new chemotherapeutic agents that can overcome the CDDP-resistant cancer cells will improve the survival of advanced cancer patients. We synthesized new glycoconjugated platinum (II) and palladium (II) complexes, [PtCl 2 (L)] and [PdCl 2 (L)]. CDDP-resistant gastric cancer cell lines were established by continuous exposure to CDDP, and gene expression in the CDDP-resistant gastric cancer cells was analyzed. The cytotoxicity and apoptosis induced by [PtCl 2 (L)] and [PdCl 2 (L)] in CDDP-sensitive and CDDP-resistant gastric cancer cells were evaluated. DNA double-strand breaks by drugs were assessed by evaluating phosphorylated histone H2AX. Xenograft tumor mouse models were established and antitumor effects were also examined in vivo. CDDP-resistant gastric cancer cells exhibit ABCB1 and CDKN2A gene up-regulation, as compared with CDDP-sensitive gastric cancer cells. In the analyses of CDDP-resistant gastric cancer cells, [PdCl 2 (L)] overcame cross-resistance to CDDP in vitro and in vivo. [PdCl 2 (L)] induced DNA double-strand breaks. These results indicate that [PdCl 2 (L)] is a potent chemotherapeutic agent for CDDP-resistant gastric cancer and may have clinical applications

  15. Develop Hydrophilic Conductive Coating Technology with High Oxidation Resistance for Non-Flow-Through PEM Fuel Cells and Electrolyzers, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — ElectroChem proposes to develop oxidation resistant, electrically conductive, hydrophilic coatings in PEM fuel cells and in PEM electrolyzers. The use of hydrophilic...

  16. Development of a peptidase-resistant substrate for single-cell measurement of protein kinase B activation.

    Science.gov (United States)

    Proctor, Angela; Wang, Qunzhao; Lawrence, David S; Allbritton, Nancy L

    2012-08-21

    An iterative design strategy using three criteria was utilized to develop a peptidase-resistant substrate peptide for protein kinase B. Libraries of peptides possessing non-native amino acids were screened for time to 50% phosphorylation, degradation half-life within a lysate, and appearance of a dominant fragment. The lead peptide possessed a half-life of 92 ± 7 and 16 ± 2 min in HeLa and LNCaP cytosolic lysates, respectively, representing a 4.6- and 2.7-fold lifetime improvement over that of the starting peptide. The redesigned peptide possessed a 4.5-fold improvement in phosphorylation efficiency compared to the starting peptide. The same peptide fragments were formed when the lead peptide was incubated in a lysate or loaded into single cells although the fragments formed in significantly different ratios suggesting that distinct peptidases metabolized the peptide in the two preparations. The rate of peptide degradation and phosphorylation was on average 0.1 ± 0.2 zmol pg(-1) s(-1) and 0.04 ± 0.08 zmol pg(-1) s(-1), respectively, for single LNCaP cells loaded with 4 ± 8 μM of peptide. Peptidase-resistant kinase substrates should find widespread utility in both lysate-based and single-cell assays of kinase activity.

  17. Development and characterization of a hydrogen peroxide-resistant cholangiocyte cell line: A novel model of oxidative stress-related cholangiocarcinoma genesis

    Energy Technology Data Exchange (ETDEWEB)

    Thanan, Raynoo [Department of Biochemistry, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002 (Thailand); Liver Fluke and Cholangiocarcinoma Research Center, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002 (Thailand); Techasen, Anchalee [Liver Fluke and Cholangiocarcinoma Research Center, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002 (Thailand); Faculty of Associated Medical Science, Khon Kaen University, Khon Kaen 40002 (Thailand); Hou, Bo [Department of Environmental and Molecular Medicine, Mie University Graduate School of Medicine, Tsu, Mie 514-8507 (Japan); Jamnongkan, Wassana; Armartmuntree, Napat [Department of Biochemistry, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002 (Thailand); Liver Fluke and Cholangiocarcinoma Research Center, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002 (Thailand); Yongvanit, Puangrat, E-mail: puangrat@kku.ac.th [Department of Biochemistry, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002 (Thailand); Liver Fluke and Cholangiocarcinoma Research Center, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002 (Thailand); Murata, Mariko, E-mail: mmurata@doc.medic.mie-u.ac.jp [Department of Environmental and Molecular Medicine, Mie University Graduate School of Medicine, Tsu, Mie 514-8507 (Japan)

    2015-08-14

    Oxidative stress is a cause of inflammation–related diseases, including cancers. Cholangiocarcinoma is a liver cancer with bile duct epithelial cell phenotypes. Our previous studies in animal and human models indicated that oxidative stress is a major cause of cholangiocarcinoma development. Hydrogen peroxide (H{sub 2}O{sub 2}) can generate hydroxyl radicals, which damage lipids, proteins, and nucleic acids, leading to cell death. However, some cells can survive by adapting to oxidative stress conditions, and selective clonal expansion of these resistant cells would be involved in oxidative stress-related carcinogenesis. The present study aimed to establish H{sub 2}O{sub 2}-resistant cell line from an immortal cholangiocyte cell line (MMNK1) by chronic treatment with low-concentration H{sub 2}O{sub 2} (25 μM). After 72 days of induction, H{sub 2}O{sub 2}-resistant cell lines (ox-MMNK1-L) were obtained. The ox-MMNK1-L cell line showed H{sub 2}O{sub 2}-resistant properties, increasing the expression of the anti-oxidant genes catalase (CAT), superoxide dismutase-1 (SOD1), superoxide dismutase-2 (SOD2), and superoxide dismutase-3 (SOD3) and the enzyme activities of CAT and intracellular SODs. Furthermore, the resistant cells showed increased expression levels of an epigenetics-related gene, DNA methyltransferase-1 (DNMT1), when compared to the parental cells. Interestingly, the ox-MMNK1-L cell line had a significantly higher cell proliferation rate than the MMNK1 normal cell line. Moreover, ox-MMNK1-L cells showed pseudopodia formation and the loss of cell-to-cell adhesion (multi-layers) under additional oxidative stress (100 μM H{sub 2}O{sub 2}). These findings suggest that H{sub 2}O{sub 2}-resistant cells can be used as a model of oxidative stress-related cholangiocarcinoma genesis through molecular changes such as alteration of gene expression and epigenetic changes. - Highlights: • An H{sub 2}O{sub 2}-resistant ox-MMNK1-L cells was established from

  18. Chemo Resistance of Breast Cancer Stem Cells

    National Research Council Canada - National Science Library

    Wicha, Max S

    2006-01-01

    .... Development of this new tool will greatly facilitate future studies. Preliminary results both in xenograft models as well as in neoadjuvant trial are providing strong support for our hypothesis for resistance of cancer cells to chemotherapy...

  19. 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...

  20. Developing Novel Therapeutics Targeting Undifferentiated and Castration-Resistant Prostate Cancer Stem Cells

    Science.gov (United States)

    2016-10-01

    display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE 2. REPORT TYPE Annual 3. DATES...cell numbers compared to the time-matched control LNCaP-GFP cells (Figure 1F). We further characterized LNCaP-GFP and LNCaP-MDV cells at crisis point...cadherin, SLUG , and vimentin), and CSCs (i.e., CD44, integrin α2β1, and ABCG2) [2-4, 20, 25-33] (Figure 3B; Supplementary Figure S3). Flow

  1. Relationship of Soluble RAGE with Insulin Resistance and Beta Cell Function during Development of Type 2 Diabetes Mellitus

    Directory of Open Access Journals (Sweden)

    Subrata Kumar Biswas

    2015-01-01

    Full Text Available This study examined whether circulating levels of soluble receptor for advanced glycation end products (sRAGE alter in prediabetes and correlate with insulin resistance (IR and beta cell function in prediabetes and newly diagnosed type 2 diabetes mellitus (T2DM. Subjects without previous history of diabetes were recruited and grouped as control, prediabetes, and newly diagnosed T2DM. The control subjects (n=40 and people with prediabetes (n=52 and diabetes (n=66 were similar in terms of age, sex, BMI, systolic and diastolic BP, and fasting insulin level. HOMA-IR was found significantly higher in people with diabetes than control subjects (p<0.001 and people with prediabetes (p=0.005; and HOMA-%B was found significantly deteriorated in people with diabetes (p<0.001 compared to control subjects and people with prediabetes. However, serum sRAGE levels did not show any significant alteration in people with prediabetes compared to control subjects. Moreover, univariate and multivariate analyses did not identify any significant correlation and statistical association of sRAGE with HOMA-IR and HOMA-%B in people with prediabetes and newly diagnosed T2DM. Our data suggest that serum sRAGE levels do not alter in people with prediabetes compared to control subjects and do not correlate or associate with IR and beta cell function during development of T2DM.

  2. Relationship of Soluble RAGE with Insulin Resistance and Beta Cell Function during Development of Type 2 Diabetes Mellitus.

    Science.gov (United States)

    Biswas, Subrata Kumar; Mohtarin, Sabreena; Mudi, Sonchita Rani; Anwar, Taznuva; Banu, Laila Anjuman; Alam, Sheikh Md Khorshed; Fariduddin, Md; Arslan, M Iqbal

    2015-01-01

    This study examined whether circulating levels of soluble receptor for advanced glycation end products (sRAGE) alter in prediabetes and correlate with insulin resistance (IR) and beta cell function in prediabetes and newly diagnosed type 2 diabetes mellitus (T2DM). Subjects without previous history of diabetes were recruited and grouped as control, prediabetes, and newly diagnosed T2DM. The control subjects (n = 40) and people with prediabetes (n = 52) and diabetes (n = 66) were similar in terms of age, sex, BMI, systolic and diastolic BP, and fasting insulin level. HOMA-IR was found significantly higher in people with diabetes than control subjects (p alteration in people with prediabetes compared to control subjects. Moreover, univariate and multivariate analyses did not identify any significant correlation and statistical association of sRAGE with HOMA-IR and HOMA-%B in people with prediabetes and newly diagnosed T2DM. Our data suggest that serum sRAGE levels do not alter in people with prediabetes compared to control subjects and do not correlate or associate with IR and beta cell function during development of T2DM.

  3. Dihydrodiol dehydrogenases regulate the generation of reactive oxygen species and the development of cisplatin resistance in human ovarian carcinoma cells

    OpenAIRE

    Chen, Jianli; Adikari, Mahesha; Pallai, Rajash; Parekh, Hemant K.; Simpkins, Henry

    2007-01-01

    We have previously demonstrated that overexpression of dihydrodiol dehydrogenase isoform 1 (DDH1) or DDH2 leads to the induction of drug resistance to platinum based drugs in human ovarian, lung, cervical and germ cell tumor cell lines. DDH belongs to a family of aldoketo reductases that are involved in the detoxification of several endogenous and exogenous substrates. DDH1 and DDH2 in particular have been shown to be involved in the detoxification (activation?) of polycyclic aromatic hydroca...

  4. Development and application of resistive pulse spectroscopy: studies on the size, form and deformability of red blood cells

    Energy Technology Data Exchange (ETDEWEB)

    Yee, J.P.

    1979-01-01

    The following studies were conducted using the resistive pulse spectroscopy (RPS) technique: cumulative spectra and individual pulse forms for rigid latex polymer spheres; acquisition and analysis of RPS spectral data by means of special computer program; interaction of red blood cells with glutaraldehyde; membrane properties of erythrocytes undergoing abrupt osmotic hemolysis; reversible effects of the binding of chlorpromazine HCl at the red cell membrane surface; effects of high cholesterol diet on erythrocytes of guinea pigs; and multi-population analysis for a mixture of fetal and maternal red cells. (HLW)

  5. 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.

  6. Development of a Resistance-like Phenotype to Sorafenib by Human Hepatocellular Carcinoma Cells Is Reversible and Can Be Delayed by Metronomic UFT Chemotherapy

    Directory of Open Access Journals (Sweden)

    Terence C. Tang

    2010-11-01

    Full Text Available Acquired resistance to antiangiogenic drugs, such as sorafenib, is a major clinical problem. We studied development of a resistance to sorafenib in new preclinical models of human hepatocellular carcinoma (HCC along with a strategy to delay such resistance—combination with metronomic chemotherapy. Three different xenograft models were studied using human Hep3B HCC cells, which are highly responsive to sorafenib, namely, orthotopic and subcutaneous transplant in severe combined immunodeficient mice, and an orthotopic transplant in nude mice. The complementary DNA for the β-subunit of human choriogonadotropin was transfected into HCC cells, and urine levels of the protein were monitored as a surrogate of tumor burden. Extended daily treatments, sometimes interrupted by a break period of 3 to 7 days to allow recovery from toxicity at sorafenib doses of 30 to 60 mg/kg, were maintained until and after evidence of tumor relapse. Initially responsive tumors seemed to develop a resistance-like phenotype after long-term daily treatment (e.g., >42 days at doses of 30 to 60 mg/kg. Transplantation of cell lines established from progressing tumors into new hosts showed that the resistant phenotype was not propagated. Furthermore, a regimen of daily metronomic uracil + tegafur (UFT, an oral 5-fluorouracil prodrug chemotherapy with a less toxic regimen of sorafenib (15 mg/kg per day significantly delayed the onset of resistance (>91 days. In conclusion, development of a resistance-like phenotype to sorafenib is reversible, and metronomic UFT plus sorafenib may be a promising and well-tolerated treatment for increasing efficacy by delaying emergence of such resistance.

  7. 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.

  8. In Situ Microscopy Analysis Reveals Local Innate Immune Response Developed around Brucella Infected Cells in Resistant and Susceptible Mice

    Science.gov (United States)

    Copin, Richard; Vitry, Marie-Alice; Hanot Mambres, Delphine; Machelart, Arnaud; De Trez, Carl; Vanderwinden, Jean-Marie; Magez, Stefan; Akira, Shizuo; Ryffel, Bernhard; Carlier, Yves; Letesson, Jean-Jacques; Muraille, Eric

    2012-01-01

    Brucella are facultative intracellular bacteria that chronically infect humans and animals causing brucellosis. Brucella are able to invade and replicate in a broad range of cell lines in vitro, however the cells supporting bacterial growth in vivo are largely unknown. In order to identify these, we used a Brucella melitensis strain stably expressing mCherry fluorescent protein to determine the phenotype of infected cells in spleen and liver, two major sites of B. melitensis growth in mice. In both tissues, the majority of primary infected cells expressed the F4/80 myeloid marker. The peak of infection correlated with granuloma development. These structures were mainly composed of CD11b+ F4/80+ MHC-II+ cells expressing iNOS/NOS2 enzyme. A fraction of these cells also expressed CD11c marker and appeared similar to inflammatory dendritic cells (DCs). Analysis of genetically deficient mice revealed that differentiation of iNOS+ inflammatory DC, granuloma formation and control of bacterial growth were deeply affected by the absence of MyD88, IL-12p35 and IFN-γ molecules. During chronic phase of infection in susceptible mice, we identified a particular subset of DC expressing both CD11c and CD205, serving as a reservoir for the bacteria. Taken together, our results describe the cellular nature of immune effectors involved during Brucella infection and reveal a previously unappreciated role for DC subsets, both as effectors and reservoir cells, in the pathogenesis of brucellosis. PMID:22479178

  9. Developing a Thermal- and Coking-Resistant Cobalt-Tungsten Bimetallic Anode Catalyst for Solid Oxide Fuel Cells

    NARCIS (Netherlands)

    Yan, N.; Pandey, J.; Zeng, Y.; Amirkhiz, B.S.; Hua, B.; Geels, N.J.; Luo, J.L.; Rothenberg, G.

    2016-01-01

    We report the development of a novel Co–W bimetallic anode catalyst for solid oxide fuel cells (SOFCs) via a facile infiltration-annealing process. Using various microscopic and spectroscopic measurements, we find that the formed intermetallic nanoparticles are highly thermally stable up to 900 °C

  10. Development is Resistance | Tandon | Africa Development

    African Journals Online (AJOL)

    The main the argument of this article is that, in our epoch, resistance against imperial domination is the first law of motion of development. How did I come to this conclusion? I came to it through a critical look at the existing theories of development, and through my active participation in over fifty years of Africa's struggle to ...

  11. 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.

  12. Impaired pentose phosphate pathway in the development of 3D MCF-7 cells mediated intracellular redox disturbance and multi-cellular resistance without drug induction.

    Science.gov (United States)

    Wang, Wenjie; Cai, Qingyun; Zhou, Fang; Liu, Jiali; Jin, Xiaoliang; Ni, Ping; Lu, Meng; Wang, Guangji; Zhang, Jingwei

    2018-05-01

    Although metabolic reprogramming and redox imbalance are widely reported to be involved in chemo-resistance in cancer treatment, much more attention was paid to anti-cancer drug induced effect. Our previous studies showed that cancer cells can develop P-gp overexpression-mediated intrinsic drug resistance in the formation of 3D MCF-7 multi-cellular layers (MCLs) without any drug induction. However, whether metabolic reprogramming and redox imbalance functioned during this progress remained unrevealed. In our present study, LC-Q/TOF-MS and GC-MS were used in combination for analysing intracellular metabolites. The contribution of pentose phosphate pathway (PPP) and its related redox status were checked by chemical interfering and silencing/over-expression of glucose-6-phosphate dehydrogenase (G6PD). The downstream products of G6PD were assayed by quantitative real-time PCR, western blot and flow cytometry. Results showed that not only G6PD expression but also G6PD activity was significantly lowered along with 3D MCF-7 cells culture time. Impaired PPP disturbed redox-cycling, generated reactive oxygen species (ROS), which triggered cell cycle arrest and caused the switch to Chk2/p53/NF-κB pathway-mediated P-gp induction. Our results provided a new attempt to associate intrinsic small molecule metabolites (impaired PPP) communicating with cell signalling pathways through disturbed intracellular redox status to elucidate multi-cellular resistance (MCR) in 3D MCF-7 cells, which improved the understanding of the mechanisms of P-gp up-regulation in MCR with metabolomic and related redox status support. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  13. Paclitaxel resistance development is associated with biphasic changes in reactive oxygen species, mitochondrial membrane potential and autophagy with elevated energy production capacity in lung cancer cells: A chronological study.

    Science.gov (United States)

    Datta, Satabdi; Choudhury, Diptiman; Das, Amlan; Das Mukherjee, Dipanwita; Das, Nabanita; Roy, Sib Sankar; Chakrabarti, Gopal

    2017-02-01

    Paclitaxel (Tx) is one of the first-line chemotherapeutic drugs used against lung cancer, but acquired resistance to this drug is a major challenge against successful chemotherapy. In this work, we have focused on the chronological changes of various cellular parameters and associated effect on Tx (10 nM) resistance development in A549 cell line. It was observed, at initial stage, the cell death percentage due to drug treatment had increased up to 20 days, and thereafter, it started declining and became completely resistant by 40 days. Expressions of βIII tubulin and drug efflux pumps also increased over the period of resistance development. Changes in cellular autophagy and reactive oxygen species generation showed a biphasic pattern and increased gradually over the course of upto 20 days, thereafter declined gradually; however, their levels remained higher than untreated cells when resistance was acquired. Increase in extracellular acidification rates and oxygen consumption rates was found to be directly correlated with acquisition of resistance. The depolarisation of mitochondrial membrane potential was also biphasic; first, it increased with increase of cell death up to 20 days, thereafter, it gradually decreased to normal level along with resistance development. Increase in activity of catalase, glutathione peroxidase and glutathione content over these periods may attribute in bringing down the reactive oxygen species levels and normalisation of mitochondrial membrane potential in spite of comparatively higher reactive oxygen species production by the Tx-resistant cells.

  14. Drug resistance in cancer cells

    National Research Council Canada - National Science Library

    Mehta, Kapil, Dr; Siddik, Zahid H

    2009-01-01

    ... from disappointment with the drug resistance reversal strategies that were carried out in the 1990s using pump inhibitors to block drug resistance mediated by P-glycoprotein, product of the MDR-1 gene. However, if one takes the larger definition - multidrug resistance as simultaneous resistance to multiple structurally unrelated anticancer therapies - its...

  15. 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

    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...... 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...

  16. Development of recommended resistance factors for drilled shafts in weak rocks based on o-cell tests : [technical summary].

    Science.gov (United States)

    2010-03-01

    Since October 1st 2007, federal-funded projects including new bridges have been mandated to be designed to meet American Association of State Highway and Transportation Officials (AASHTO) Load and Resistance Factor Design (LRFD) Bridge Design Specifi...

  17. Development of recommended resistance factors for drilled shafts in weak rocks based on o-cell tests.

    Science.gov (United States)

    2010-03-01

    From October 1, 2007, the new bridges on federal-aid funded projects are mandated to be designed to meet : American Association of State Highway and Transportation Officials (AASHTO) Load and Resistance Factor Design : (LRFD) Bridge Design Specificat...

  18. Development of Nano-Liposomal Formulations of Epidermal Growth Factor Receptor Inhibitors and their Pharmacological Interactions on Drug-Sensitive and Drug-Resistant Cancer Cell Lines

    Science.gov (United States)

    Trummer, Brian J.

    A rapidly expanding understanding of molecular derangements in cancer cell function has led to the development of selective, targeted chemotherapeutic agents. Growth factor signal transduction networks are frequently activated in an aberrant fashion, particularly through the activity of receptor tyrosine kinases (RTK). This has spurred an intensive effort to develop receptor tyrosine kinase inhibitors (RTKI) that are targeted to specific receptors, or receptor subfamilies. Chapter 1 reviews the pharmacology, preclinical, and clinical aspects of RTKIs that target the epidermal growth factor receptor (EGFR). EGFR inhibitors demonstrate significant success at inhibiting phosphorylation-based signaling pathways that promote cancer cell proliferation. Additionally RTKIs have physicochemical and structural characteristics that enable them to function as inhibitors of multi-drug resistance transport proteins. Thus EGFR inhibitors and other RTKIs have both on-target and off-target activities that could be beneficial in cancer therapy. However, these agents exert a number of side effects, some of which arise from their hydrophobic nature and large in vivo volume of distribution. Side effects of the EGFR inhibitor gefitinib include skin rash, severe myelotoxicity when combined with certain chemotherapeutic agents, and impairment of the blood brain barrier to xenobiotics. Weighing the preclinical and clinical observations with the EGFR inhibitors, we developed the primary overall hypothesis of this research: that drug-carrier formulations of RTKIs such as the EGFR inhibitors could be developed based on nanoparticulate liposomal carriers. Theoretically, this carrier strategy would ameliorate toxicity and improve the biodistribution and tumor selectivity of these agents. We hypothesized specifically that liposomal formulations could shift the biodistribution of EGFR inhibitors such as gefitinib away from skin, bone marrow, and the blood brain barrier, and toward solid tumors

  19. Breast cancer cells can switch between estrogen receptor alpha and ErbB signaling and combined treatment against both signaling pathways postpones development of resistance

    DEFF Research Database (Denmark)

    Sonne-Hansen, Katrine; Norrie, Ida C; Emdal, Kristina Bennet

    2010-01-01

    The majority of breast cancers are estrogen responsive, but upon progression of disease other growth promoting pathways are activated, e.g., the ErbB receptor system. The present study focuses on resistance to the pure estrogen antagonist fulvestrant and strategies to treat resistant cells or even...

  20. Cytostatic resistance profile of the sulfur mustard resistant keratinocyte cell line HaCaT/SM.

    Science.gov (United States)

    Schmidt, Annette; Wolf, Markus; Rothmiller, Simone; Worek, Franz; Steinritz, Dirk; Thiermann, Horst

    2018-03-15

    The cell line HaCaT/SM was developed as a sulfur mustard (SM) resistant cell line from the human keratinocyte cell line HaCaT. This cell line was established to learn more about the effect of SM and possible therapeutic approaches to counteract the cytotoxic effects of SM. The aim of this study was to clarify whether the SM-resistant cell line HaCaT/SM exhibit also resistance to other alkylating agents or cytotoxic drugs with different mechanism of action. The chemosensitivity of SM-resistant human keratinocyte cell line HaCaT/SM and the original cell line HaCaT were tested using the XTT assay. Nine cytotoxic drugs from five different substance groups were investigated. HaCaT/SM showed a significant increase in resistance against all tested drugs. From the substance class of the alkylating agents, HaCaT/SM showed the strongest resistance increase against chlorambucil (1.7 fold increase). Whereas over all substances strongest increase was observed against cisplatin (5.1 fold increase). The highest resistance was observed for cisplatin. The SM resistant cells revealed changes in the miRNA profile as described before. The resistance to cisplatin is also connected to a specific miRNA profile. Interestingly, changes of miRNA-203 and miRNA-21 levels were found in HaCaT/SM as well as in cisplatin resistant cells. It is therefore conceivable that the same resistance pathways are involved for both substances. Copyright © 2018 Elsevier B.V. All rights reserved.

  1. Development of thrombus-resistant and cell compatible crimped polyethylene terephthalate cardiovascular grafts using surface co-immobilized heparin and collagen

    Energy Technology Data Exchange (ETDEWEB)

    Al Meslmani, Bassam, E-mail: almeslmanib@yahoo.com [Department of Pharmaceutical Technology and Biopharmaceutics, Marburg University, Ketzerbach 63, 35037 Marburg (Germany); Mahmoud, Gihan, E-mail: mahmoudg@staff.uni-marburg.de [Department of Pharmaceutical Technology and Biopharmaceutics, Marburg University, Ketzerbach 63, 35037 Marburg (Germany); Department of Pharmaceutics and Industrial Pharmacy, Helwan University, Ain Helwan, 11795 Cairo (Egypt); Strehlow, Boris, E-mail: strehlo4@staff.uni-marburg.de [Department of Pharmaceutical Technology and Biopharmaceutics, Marburg University, Ketzerbach 63, 35037 Marburg (Germany); Mohr, Eva, E-mail: mohr@staff.uni-marburg.de [Department of Pharmaceutical Technology and Biopharmaceutics, Marburg University, Ketzerbach 63, 35037 Marburg (Germany); Leichtweiß, Thomas, E-mail: Thomas.leichtweiss@phys.chemie.uni-giessen.de [Institute of Physical Chemistry, Justus-Liebig-University, Heinrich-Buff-Ring 58, 35392 Giessen (Germany); Bakowsky, Udo, E-mail: ubakowsky@aol.com [Department of Pharmaceutical Technology and Biopharmaceutics, Marburg University, Ketzerbach 63, 35037 Marburg (Germany)

    2014-10-01

    Short-term patency of polyethylene terephthalate (PET) cardiovascular grafts is determined mainly by the inherent thrombogenicity and improper endothelialization following grafts implantation. The aim of the present study was to immobilize heparin to develop thrombus resistant grafts. Additionally, collagen was co-immobilized to enhance the host cell compatibility. The synthetic woven and knitted forms of crimped PET grafts were surface modified by Denier reduction to produce functional carboxyl groups. The produced groups were used as anchor sites for covalent immobilization of heparin or co-immobilization of heparin/collagen by the end-point method. The modified surface was characterized using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The biological activity of immobilized molecules was investigated in vitro using direct blood coagulation test, and “platelet deposition under flow condition. Furthermore, the biocompatibility of modified grafts with host cells was assessed using L929 cell as model. All modified grafts showed significant resistance against fibrin and clot formation. The number of deposited platelets on heparin-immobilized woven and knitted grafts obviously decreased by 3 fold and 2.8 fold per unit surface area respectively, while the heparin/collagen co-immobilized grafts showed only a decrease by 1.7 and 1.8 fold compared to unmodified PET. Heparin-immobilized grafts reported no significant effect on L929 cells adhesion and growth (P > 0.05), conversely, collagen co-immobilization considerably increased cell adhesion almost ∼ 1.3 fold and 2 fold per unit surface area for woven and knitted grafts respectively. Our results emphasize that immobilization of heparin minimized the inherent thrombogenicity of the PET grafts. The simultaneous co-immobilization of collagen supported host cell adhesion and growth required for the grafts biocompatibility. - Highlight: • Heparin and collagen were co-immobilized on

  2. Role of Autophagy in Cisplatin Resistance in Ovarian Cancer Cells*

    Science.gov (United States)

    Wang, Juan; Wu, Gen Sheng

    2014-01-01

    Cisplatin-based treatment is the first line chemotherapy for several cancers including ovarian cancer. The development of cisplatin resistance results in treatment failure, but the underlying mechanisms are not fully understood. Here we show that the induction of autophagy plays an important role in cisplatin resistance in ovarian cancer cells. Specifically, we show that cisplatin resistance is correlated with autophagy induction in a panel of ovarian cancer cells but not in immortalized human ovarian surface epithelial cells. Mechanistically, cisplatin treatment activates ERK and subsequently promotes autophagy. The inhibition of ERK activation with MEK inhibitors or knockdown of ERK expression with siRNA decreases cisplatin-induced autophagy and subsequently sensitizes ovarian cancer cells to cisplatin-induced apoptosis. In ovarian cancer cells that have developed acquired cisplatin resistance, both ERK activation and autophagy induction are increased. Importantly, knockdown of ERK or inhibition of autophagy promotes cisplatin-induced apoptosis in acquired cisplatin-resistant cells. Collectively, our data indicate that ERK-mediated autophagy can lead to cisplatin resistance and suggest that cisplatin resistance can be overcome by inhibition of autophagy in ovarian cancer cells. PMID:24794870

  3. Natural killer T cells in adipose tissue prevent insulin resistance

    NARCIS (Netherlands)

    Schipper, H.S.; Rakhshandehroo, M.; Graaf, van de S.F.J.; Venken, K.; Koppen, A.; Stienstra, R.; Prop, S.; Meerding, J.; Hamers, N.; Besra, G.S.; Boon, den L.; Nieuwenhuis, E.E.S.; Elewaut, D.; Prakken, B.; Kersten, A.H.; Boes, M.; Kalkhoven, E.

    2012-01-01

    Lipid overload and adipocyte dysfunction are key to the development of insulin resistance and can be induced by a high-fat diet. CD1d-restricted invariant natural killer T (iNKT) cells have been proposed as mediators between lipid overload and insulin resistance, but recent studies found decreased

  4. Role of the plant cell wall in gravity resistance.

    Science.gov (United States)

    Hoson, Takayuki; Wakabayashi, Kazuyuki

    2015-04-01

    Gravity resistance, mechanical resistance to the gravitational force, is a principal graviresponse in plants, comparable to gravitropism. The cell wall is responsible for the final step of gravity resistance. The gravity signal increases the rigidity of the cell wall via the accumulation of its constituents, polymerization of certain matrix polysaccharides due to the suppression of breakdown, stimulation of cross-link formation, and modifications to the wall environment, in a wide range of situations from microgravity in space to hypergravity. Plants thus develop a tough body to resist the gravitational force via an increase in cell wall rigidity and the modification of growth anisotropy. The development of gravity resistance mechanisms has played an important role in the acquisition of responses to various mechanical stresses and the evolution of land plants. Copyright © 2014 Elsevier Ltd. All rights reserved.

  5. 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

  6. Tcf3 and cell cycle factors contribute to butyrate resistance in colorectal cancer cells

    International Nuclear Information System (INIS)

    Chiaro, Christopher; Lazarova, Darina L.; Bordonaro, Michael

    2012-01-01

    Highlights: ► We investigate mechanisms responsible for butyrate resistance in colon cancer cells. ► Tcf3 modulates butyrate’s effects on Wnt activity and cell growth in resistant cells. ► Tcf3 modulation of butyrate’s effects differ by cell context. ► Cell cycle factors are overexpressed in the resistant cells. ► 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 1 to S transition. Knowledge of the molecular mechanisms determining the variable sensitivity of CRC cells to butyrate may assist in developing approaches that prevent or reverse butyrate resistance.

  7. 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

  8. How Economic Development Affects Antibiotic Resistance

    OpenAIRE

    John B. Horowitz; H. Brian Moehring

    2014-01-01

    Initially, economic development increases resistance because migration of people to urban areas in developing countries increases incomes, crowding and the use of antibiotics. Also, developing countries often don't require prescriptions or distribute high quality antibiotics. In developed countries, antibiotic resistance often falls or there is a decline in the rate of growth of resistance because infections decline with improvements in water quality, sanitation, housing and nutrition. Howeve...

  9. Metalloproteins during development of Walker-256 carcinosarcoma resistant phenotype

    Directory of Open Access Journals (Sweden)

    V. F. Chekhun

    2015-04-01

    Full Text Available The study was focused on the detection of changes in serum and tumor metal-containing proteins in animals during development of doxorubicin-resistant phenotype in malignant cells after 12 courses of chemotherapy. We found that on every stage of resistance development there was a significant increase in content of ferritin and transferrin proteins (which take part in iron traffick and storage in Walker-256 carcinosarcoma tissue. We observed decreased serum ferritin levels at the beginning stage of the resistance development and significant elevation of this protein levels in the cases with fully developed resistance phenotype. Transferrin content showed changes opposite to that of ferritin. During the development of resistance phenotype the tumor tissue also exhibited increased ‘free iron’ concentration that putatively correlate with elevation of ROS generation and levels of MMP-2 and MMP-9 active forms. The tumor non-protein thiol content increases gradually as well. The serum of animals with early stages of resistance phenotype development showed high ceruloplasmin activity and its significant reduction after loss of tumor sensitivity to doxorubicin. Therefore, the development of resistance phenotype in Walker-256 carcinosarcoma is accompanied by both the deregulation of metal-containing proteins in serum and tumor tissue and by the changes in activity of antioxidant defense system. Thus, the results of this study allow us to determine the spectrum of metal-containing proteins that are involved in the development of resistant tumor phenotype and that may be targeted for methods for doxorubicin sensitivity correction therapy.

  10. Development of TRAIL Resistance by Radiation-Induced Hypermethylation of DR4 CpG Island in Recurrent Laryngeal Squamous Cell Carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jong Cheol [Department of Otorhinolaryngology, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan (Korea, Republic of); Department of Biomedical Research Center, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan (Korea, Republic of); Lee, Won Hyeok [Department of Biomedical Research Center, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan (Korea, Republic of); Min, Young Joo [Department of Biomedical Research Center, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan (Korea, Republic of); Department of Internal Medicine, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan (Korea, Republic of); Cha, Hee Jeong [Department of Pathology, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan (Korea, Republic of); Han, Myung Woul [Department of Otorhinolaryngology, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan (Korea, Republic of); Chang, Hyo Won [Department of Otolaryngology, Asan Medical Center, University of Ulsan College of Medicine, Seoul (Korea, Republic of); Kim, Sun-A [Department of Pathology, Asan Medical Center, University of Ulsan College of Medicine, Seoul (Korea, Republic of); Choi, Seung-Ho [Department of Otolaryngology, Asan Medical Center, University of Ulsan College of Medicine, Seoul (Korea, Republic of); Kim, Seong Who, E-mail: swhokim@gmail.com [Department of Biochemistry and Molecular Biology, Asan Medical Center, University of Ulsan College of Medicine, Seoul (Korea, Republic of); Kim, Sang Yoon, E-mail: sykim3715@gmail.com [Department of Otolaryngology, Asan Medical Center, University of Ulsan College of Medicine, Seoul (Korea, Republic of); Biomedical Research Institute, Korea Institute of Science and Technology, Seoul (Korea, Republic of)

    2014-04-01

    Purpose: There are limited therapeutic options for patients with recurrent head and neck cancer after radiation therapy failure. To assess the use of tumor necrosis factor–related apoptosis-inducing ligand (TRAIL) as a salvage chemotherapeutic agent for recurrent cancer after radiation failure, we investigated the effect of clinically relevant cumulative irradiation on TRAIL-induced apoptosis. Methods and Materials: Using a previously established HN3 cell line from a laryngeal carcinoma patient, we generated a chronically irradiated HN3R isogenic cell line. Viability and apoptosis in HN3 and HN3R cells treated with TRAIL were analyzed with MTS and PI/annexin V-FITC assays. Western blotting and flow cytometry were used to determine the underlying mechanism of TRAIL resistance. DR4 expression was semiquantitatively scored in a tissue microarray with 107 laryngeal cancer specimens. Methylation-specific polymerase chain reaction and bisulfite sequencing for DR4 were performed for genomic DNA isolated from each cell line. Results: HN3R cells were more resistant than HN3 cells to TRAIL-induced apoptosis because of significantly reduced levels of the DR4 receptor. The DR4 staining score in 37 salvage surgical specimens after radiation failure was lower in 70 surgical specimens without radiation treatment (3.03 ± 2.75 vs 5.46 ± 3.30, respectively; P<.001). HN3R cells had a methylated DR4 CpG island that was partially demethylated by the DNA demethylating agent 5-aza-2′-deoxycytidine. Conclusion: Epigenetic silencing of the TRAIL receptor by hypermethylation of a DR4 CpG island might be an underlying mechanism for TRAIL resistance in recurrent laryngeal carcinoma treated with radiation.

  11. Molecular Mechanisms of Insulin Resistance Development

    Directory of Open Access Journals (Sweden)

    Vsevolod Arsen'evich Tkachuk

    2014-05-01

    Full Text Available Insulin resistance (IR is a phenomenon associated with an impaired ability of insulin to stimulate glucose uptake by target cells and to reduce the blood glucose level. A response increase in insulin secretion by the pancreas and hyperinsulinemia are compensatory reactions of the body. The development of IR leads to the inability of target cells to respond to insulin that results in developing type 2 diabetes mellitus (T2DM and metabolic syndrome. For this reason, the metabolic syndrome is defined in practice as a combination of IR with one or more pathologies such as T2DM, arterial hypertension, dyslipidemia, abdominal obesity, non-alcoholic fatty liver disease, and some others. However, a combination of high blood glucose and insulin levels always serves as its physiological criterion.IR should be considered as a systemic failure of the endocrine regulation in the body. Physiological causes of IR are diverse. The main ones are nutritional overload and accumulation of certain lipids and their metabolites in cells, low physical activity, chronic inflammation and stress of various nature, including oxidative and endoplasmic reticulum stress (impairment of damaged protein degradation in the cell. Recent studies have demonstrated that these physiological mechanisms likely act through a single intracellular scenario. This is the impairment of signal transduction from the insulin receptor to its targets via the negative feedback mechanism in intracellular insulin-dependent signaling cascades.This review describes the physiological and intracellular mechanisms of insulin action and focuses on their abnormalities upon IR development. Finally, feasible trends in early molecular diagnosis and therapy of IR are discussed.

  12. The behavior of electrochemical cell resistance

    International Nuclear Information System (INIS)

    Ritley, K.A.; Dull, P.M.; Weber, M.H.; Carroll, M.; Hurst, J.J.; Lynn, K.G.

    1990-01-01

    Knowledge of the basic electrochemical behavior found in typical cold fusion experiments is important to understanding and preventing experimental errors. For a Pd/LiOH(D)/Pt electrochemical cell, the applied cell voltage/current relationship (the effective cell resistance) does not obey Ohm's law directly, but instead exhibits a complicated response to the current, voltage, temperature, electrolyte conductance, and other factors. Failure to properly consider this response can possibly result in errors that could affect the heat balance in calorimetry and temperature measurement experiments. Measurements of this response under varying voltage, temperature, and electrolyte conductivity conditions are reported. A plausible scenario in which the temperature dependence of the effective cell resistance can either exaggerate or ameliorate novel exothermic processes is suggested

  13. Insulin resistance in vascular endothelial cells promotes intestinal tumour formation

    DEFF Research Database (Denmark)

    Wang, X; Häring, M-F; Rathjen, Thomas

    2017-01-01

    The risk of several cancers, including colorectal cancer, is increased in patients with obesity and type 2 diabetes, conditions characterised by hyperinsulinaemia and insulin resistance. Because hyperinsulinaemia itself is an independent risk factor for cancer development, we examined tissue...... did not change intestinal tumour number or size distribution on either a low or high-fat diet. We therefore asked whether cells in the tumour stroma might explain the association between tumour formation and insulin resistance. To this end, we generated Apc(Min/+) mice with loss of insulin receptors...... and increased the frequency of neutrophils in tumours. We conclude that although insulin is mitogenic for intestinal tumour cells in vitro, impaired insulin action in the tumour microenvironment may be more important in conditions where hyperinsulinaemia is secondary to insulin resistance. Insulin resistance...

  14. Development of ultra radiation-resistant cables

    International Nuclear Information System (INIS)

    Fujimura, Shun-ichi; Handa, Katsue; Kubo, Masaji; Tsutsumi, Yukihiro; Seguchi, Tadao.

    1990-01-01

    For the purpose of using in the environment where the exposure to the radiation of large dose occurs, the ultra radiation-resistant cables using acenaphthylene bromide condensation product Con-BACN were developed, and it was already reported. However, since the Con-BACN is the mixture of condensation products, the bromine content, the condensed composition and the effect of giving radiation resistance tended to change widely. In this paper, the review of the method of synthesizing Con-BACN, the composition of the obtained condensation product, the mechanism that the Con-BACN gives the effect of radiation resistance and the characteristics of the ultra radiation-resistant cables using the Con-BACN are reported. The new reaction for synthesizing Con-BACN was developed, which solved the difficulty in the old process. The optimum condensation composition was decided in view of the characteristics of radiation resistance. Also the yield of Con-BACN was improved to 70-90%. It was predicted that graft reaction exerted influence to the effect of giving radiation resistance. The radiation resistance, environment resistance and incombustibility of the ultra radiation-resistant cables are reported. (K.I.)

  15. Bcr-Abl Amplification Plays a Major Role in Resistance to Tyrosine Kinase Inhibitors in K-562 Cell Line

    OpenAIRE

    Czyżewski, Krzysztof; Skonieczka, Katarzyna; Różycki, Patryk; Kołodziej, Beata; Kuryło-Rafińska, Beata; Kubicka, Małgorzata; Matiakowska, Karolina; Mucha, Barbara; Haus, Olga; Wysocki, Mariusz; Styczyński, Jan

    2012-01-01

    An emerging problem in patients with chronic myeloid leukemia (CML) is increasing resistance to tyrosine kinase inhibitors (TKIs). To determine genetic and cellular mechanisms involved in the development of resistance to TKIs, nine imatinib-resistant cell lines were derived from K- 562 cell line followed by testing of drug sensitivity, multidrug resistance proteins and cytogenetic studies. In imatinib-resistant cell lines cross-resistance to daunorubicin, etoposide and cytarabine were observe...

  16. [Establishment of 5 resistant ovarian cancer cell strains and expression of resistance-related genes].

    Science.gov (United States)

    Luan, Ying-zi; Li, Li; Li, Dang-rong; Zhang, Wei; Tang, Bu-jian

    2004-06-01

    To investigate expression difference of several drug resistance related genes between sensitive and resistant ovarian carcinoma cells. Cell lines resistant to cisplatin, carboplatin and taxol were established from ovarian carcinoma cell lines of SKOV3 and A2780, and their biological features were detected. The expressions of several genes related to drug resistance were measured by RT-PCR method. (1) The values of resistance index (RI) of resistant cells to relevant drugs were elevated 3 times or more, with different degrees of cross-resistance to several other drugs (RI 2 approximately 20). They grew more slowly than primary cells (Td elongated 1.4 approximately 2.4 times, P 0.05). Intracellular concentrations of relevant drugs were reduced 2.0 approximately 8.5 times in resistant cells (P p53, lung resistance protein-1 (LRP-1), multiple drug resistance related protein-1 (MRP-1) genes were expressed at lower levels in resistant cells than in sensitive cells; while protein kinase C (PKC), topoisomerase (topo) I, and topo II beta were expressed higher, no obvious alterations were found concerning glutathione S transferase-pi (GST-pi), and topo II alpha. Expression of multiple drug resistance-1 (MDR-1) gene was either elevated or reduced in different cells. The expressions of resistance related genes were widely different in different kinds of resistant cells, suggesting more than one pathway leading to resistance transformation. This adds more difficulties for clinical management.

  17. 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

  18. Development of botanicals to combat antibiotic resistance

    Directory of Open Access Journals (Sweden)

    Pooja D. Gupta

    2017-10-01

    Full Text Available The discovery of antibiotics in the previous century lead to reduction in mortality and morbidity due to infectious diseases but their inappropriate and irrational use has resulted in emergence of resistant microbial populations. Alteration of target sites, active efflux of drugs and enzymatic degradations are the strategies employed by the pathogenic bacteria to develop intrinsic resistance to antibiotics. This has led to an increased interest in medicinal plants since 25–50% of current pharmaceuticals are plant derived. Crude extracts of medicinal plants could serve as an alternate source of resistance modifying agents owing to the wide variety of secondary metabolites. These metabolites (alkaloids, tannins, polyphenols etc. could act as potentials for antimicrobials and resistance modifiers. Plant extracts have the ability to bind to protein domains leading to modification or inhibition protein–protein interactions. This enables the herbals to also present themselves as effective modulators of host related cellular processes viz immune response, mitosis, apoptosis and signal transduction. Thus they may exert their activity not only by killing the microorganism but by affecting key events in the pathogenic process, thereby, the bacteria, fungi and viruses may have a reduced ability to develop resistance to botanicals. The article is meant to stimulate research wherein the cidal activity of the extract is not the only parameter considered but other mechanism of action by which plants can combat drug resistant microbes are investigated. The present article emphasizes on mechanisms involved in countering multi drug resistance.

  19. Cancer Stem Cell Plasticity Drives Therapeutic Resistance

    Directory of Open Access Journals (Sweden)

    Mary R. Doherty

    2016-01-01

    Full Text Available The connection between epithelial-mesenchymal (E-M plasticity and cancer stem cell (CSC properties has been paradigm-shifting, linking tumor cell invasion and metastasis with therapeutic recurrence. However, despite their importance, the molecular pathways involved in generating invasive, metastatic, and therapy-resistant CSCs remain poorly understood. The enrichment of cells with a mesenchymal/CSC phenotype following therapy has been interpreted in two different ways. The original interpretation posited that therapy kills non-CSCs while sparing pre-existing CSCs. However, evidence is emerging that suggests non-CSCs can be induced into a transient, drug-tolerant, CSC-like state by chemotherapy. The ability to transition between distinct cell states may be as critical for the survival of tumor cells following therapy as it is for metastatic progression. Therefore, inhibition of the pathways that promote E-M and CSC plasticity may suppress tumor recurrence following chemotherapy. Here, we review the emerging appreciation for how plasticity confers therapeutic resistance and tumor recurrence.

  20. 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

  1. Cancer stem cells and drug resistance: the potential of nanomedicine

    Science.gov (United States)

    Vinogradov, Serguei; Wei, Xin

    2012-01-01

    Properties of the small group of cancer cells called tumor-initiating or cancer stem cells (CSCs) involved in drug resistance, metastasis and relapse of cancers can significantly affect tumor therapy. Importantly, tumor drug resistance seems to be closely related to many intrinsic or acquired properties of CSCs, such as quiescence, specific morphology, DNA repair ability and overexpression of antiapoptotic proteins, drug efflux transporters and detoxifying enzymes. The specific microenvironment (niche) and hypoxic stability provide additional protection against anticancer therapy for CSCs. Thus, CSC-focused therapy is destined to form the core of any effective anticancer strategy. Nanomedicine has great potential in the development of CSC-targeting drugs, controlled drug delivery and release, and the design of novel gene-specific drugs and diagnostic modalities. This review is focused on tumor drug resistance-related properties of CSCs and describes current nanomedicine approaches, which could form the basis of novel combination therapies for eliminating metastatic and CSCs. PMID:22471722

  2. Biological characteristics of Taxol‑resistant ovarian cancer cells and reversal of Taxol resistance by adenovirus expressing p53.

    Science.gov (United States)

    Liu, Qun; Sui, Rui; Li, Ruirui; Miao, Jinwei; Liu, Jian

    2015-02-01

    The development of acquired drug resistance is the primary cause of chemotherapy failure in the treatment of ovarian cancer. To examine the mechanism underlying Taxol (TAX) resistance in ovarian cancer and attempt to reverse it, the present study induced a TAX‑resistant ovarian cancer cell line SKOV3/TAX using a gradient concentration increment method. The properties of the resistant cell line were initially investigated by proliferation, colony formation, adhesion and cell cycle analysis compared with control SKOV3 cells. To examine the mechanism, the expression of p53 upregulated modulator of apoptosis (PUMA) was compared between SKOV3/TAX and SKOV3 cells by western blot analysis. An adenovirus expressing p53 (Ad‑p53), alone or in combination with TAX, was used to treat the drug‑resistant ovarian cancer cells SKOV3/TAX. The effects of Ad‑p53 on pro‑apoptosis and the reversal of drug resistance were evaluated using flow cytometric analysis, cleaved‑poly ADP‑ribose polymerase detection, microscopic observation and MTT measurement. Compared with the control cells, the TAX‑resistant ovarian cancer cell line SKOV3/TAX was characterized by reduced sensitivity to TAX treatment, a significantly slower proliferation rate, higher colony‑forming efficiency and higher adhesion ability. However, no significant difference in cell cycle distribution was identified. PUMA, a potent pro‑apoptotic protein, was markedly suppressed in the SKOV3/TAX cells. Ad‑p53 infection stimulated the upregulation of PUMA and re‑sensitized the resistant ovarian cancer cells to TAX by an apoptotic mechanism. Therefore, Ad‑p53 infection is an effective gene therapy method to re‑sensitize the resistant ovarian cancer cells to TAX by restoring the expression of PUMA.

  3. 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

    Background: Erlotinib (Tarceva®, Roche) has significantly changed the treatment of non-small cell lung cancer (NSCLC) as approximately 70% of patients show significant tumor regression when treated (Santarpia et. al., 2013). However, all patients relapse due to development of acquired resistance...... 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...... the identification of novel resistance mechanisms. We identified 2875 cytoplasmic proteins present in all 4 cell lines. Of these 87, 56 and 23 are upregulated >1.5 fold; and 117, 72 and 32 are downregulated >1.5 fold, respectively, in the 3 resistant clones compared to the parental cell line. By network analysis, we...

  4. Quantitative proteomics identifies central players in erlotinib resistance of the non-small cell lung cancer cell line HCC827

    DEFF Research Database (Denmark)

    Jacobsen, Kirstine; Lund, Rikke Raaen; Beck, Hans Christian

    Background: Erlotinib (Tarceva®, Roche) has significantly changed the treatment of non-small cell lung cancer (NSCLC) as 70% of patients show significant tumor regression when treated. However, all patients relapse due to development of acquired resistance, which in 43-50% of cases are caused...... by a secondary mutation (T790M) in EGFR. Importantly, a majority of resistance cases are still unexplained. Our aim is to identify novel resistance mechanisms in erlotinib-resistant subclones of the NSCLC cell line HCC827. Materials & Methods: We established 3 erlotinib-resistant subclones (resistant to 10, 20...... or other EGFR or KRAS mutations, potentiating the identification of novel resistance mechanisms. We identified 2875 cytoplasmic proteins present in all 4 cell lines. Of these 87, 56 and 23 are upregulated >1.5 fold; and 117, 72 and 32 are downregulated >1.5 fold, respectively, in the 3 resistant clones...

  5. The stepwise evolution of the exome during acquisition of docetaxel resistance in breast cancer cells

    DEFF Research Database (Denmark)

    Hansen, Stine Ninel; Ehlers, Natasja Spring; Zhu, Shida

    2016-01-01

    Background: Resistance to taxane-based therapy in breast cancer patients is a major clinical problem that may be addressed through insight of the genomic alterations leading to taxane resistance in breast cancer cells. In the current study we used whole exome sequencing to discover somatic genomic...... alterations, evolving across evolutionary stages during the acquisition of docetaxel resistance in breast cancer cell lines. Results: Two human breast cancer in vitro models (MCF-7 and MDA-MB-231) of the step-wise acquisition of docetaxel resistance were developed by exposing cells to 18 gradually increasing...... resistance relevant genomic variation appeared to arise midway towards fully resistant cells corresponding to passage 31 (5 nM docetaxel) for MDA-MB-231 and passage 16 (1.2 nM docetaxel) for MCF-7, and where the cells also exhibited a period of reduced growth rate or arrest, respectively. MCF-7 cell acquired...

  6. SCREENING FOR DEVELOPMENT OF HOST PLANT RESISTANCE ...

    African Journals Online (AJOL)

    Tangaza

    losses of cowpea yields and if not controlled, they limit the yields to less than 300kg/ha (Singh et al., 1990). A considerable progress has been made during the past decade in cowpea breeding and a range of varieties have been developed with resistance to several diseases, insect pests and parasitic weeds. Much time ...

  7. Enhanced autophagy in cytarabine arabinoside-resistant U937 leukemia cells and its potential as a target for overcoming resistance.

    Science.gov (United States)

    Cheong, June-Won; Kim, Yundeok; Eom, Ju In; Jeung, Hoi-Kyung; Min, Yoo Hong

    2016-04-01

    Autophagy is a lysosomal degradation mechanism that is essential for cell survival, differentiation, development, and homeostasis. Autophagy protects cells from various stresses, including protecting normal cells from harmful metabolic conditions, and cancer cells from chemotherapeutics. In the current study, a cytarabine arabinoside (Ara‑C)‑sensitive U937 leukemia cell line and an Ara‑C‑resistant U937 (U937/AR) cell line were assessed for baseline autophagy activity by investigating the LC3‑I conversion to LC3‑II, performing EGFP‑LC3 puncta, an acidic autophagolysosome assay, and measuring the expression of various autophagy‑related genes. The results demonstrated significantly higher autophagic activity in the U937/AR cells compared with the U937 cells, when the cells were cultured with or without serum. Furthermore, an increase in the autophagic activity in starved U937/AR cells was demonstrated, compared with that in the starved U937 cells. Administration of an autophagy inhibitor demonstrated no change in cell death in the two cell lines when cultured with serum, however, it induced cell death regardless of the Ara‑C sensitivity when the cell lines were cultured without serum. In addition, the U937 cells demonstrated an Ara‑C resistance when cultured without serum. Co‑treatment with Ara‑C and the autophagy inhibitor significantly induced cell death in the U937/AR and Ara‑C‑sensitive U937 cells. In conclusion, autophagy serves an important role in protecting U937 cells from Ara‑C and in the development of Ara‑C resistance. Inhibition of autophagy combined with the Ara‑C treatment in the U937 cells augmented the anti‑leukemic effect of Ara‑C and overcame Ara‑C resistance, suggesting that autophagy may be an important therapeutic target to further improve the treatment outcome in patients with acute myeloid leukemia.

  8. Non-Small Cell Lung Cancer Cells Acquire Resistance to the ALK Inhibitor Alectinib by Activating Alternative Receptor Tyrosine Kinases.

    Science.gov (United States)

    Isozaki, Hideko; Ichihara, Eiki; Takigawa, Nagio; Ohashi, Kadoaki; Ochi, Nobuaki; Yasugi, Masayuki; Ninomiya, Takashi; Yamane, Hiromichi; Hotta, Katsuyuki; Sakai, Katsuya; Matsumoto, Kunio; Hosokawa, Shinobu; Bessho, Akihiro; Sendo, Toshiaki; Tanimoto, Mitsune; Kiura, Katsuyuki

    2016-03-15

    Crizotinib is the standard of care for advanced non-small cell lung cancer (NSCLC) patients harboring the anaplastic lymphoma kinase (ALK) fusion gene, but resistance invariably develops. Unlike crizotinib, alectinib is a selective ALK tyrosine kinase inhibitor (TKI) with more potent antitumor effects and a favorable toxicity profile, even in crizotinib-resistant cases. However, acquired resistance to alectinib, as for other TKIs, remains a limitation of its efficacy. Therefore, we investigated the mechanisms by which human NSCLC cells acquire resistance to alectinib. We established two alectinib-resistant cell lines that did not harbor the secondary ALK mutations frequently occurring in crizotinib-resistant cells. One cell line lost the EML4-ALK fusion gene, but exhibited increased activation of insulin-like growth factor-1 receptor (IGF1R) and human epidermal growth factor receptor 3 (HER3), and overexpressed the HER3 ligand neuregulin 1. Accordingly, pharmacologic inhibition of IGF1R and HER3 signaling overcame resistance to alectinib in this cell line. The second alectinib-resistant cell line displayed stimulated HGF autocrine signaling that promoted MET activation and remained sensitive to crizotinib treatment. Taken together, our findings reveal two novel mechanisms underlying alectinib resistance that are caused by the activation of alternative tyrosine kinase receptors rather than by secondary ALK mutations. These studies may guide the development of comprehensive treatment strategies that take into consideration the various approaches ALK-positive lung tumors use to withstand therapeutic insult. ©2015 American Association for Cancer Research.

  9. Radiation resistance of solar cells for space application, 1

    International Nuclear Information System (INIS)

    Mitsui, Hiroshi; Tanaka, Ryuichi; Sunaga, Hiromi

    1989-07-01

    A 50-μm thick ultrathin silicon solar cell and a 280-μm thick high performance AlGaAs/GaAs solar cell with high radiation resistance have been recently developed by National Space Development Agency of Japan (NASDA). In order to study the radiation resistance of these cells, a joint research was carried out between Japan Atomic Energy Research Institute (JAERI) and NASDA from 1984 through 1987. In this research, the irradiation method of electron beams, the effects of the irradiation conditions on the deterioration of solar cells by electron beams, and the annealing effects of the radiation damage in solar cells were investigated. This paper is the first one of a series of reports of the joint research. In this paper, the space radiation environment which artificial satellites will encounter, the solar cells used, and the experimental methods are described. In addition to these, the results of the study on the irradiation procedure of electron beams are reported. In the study of the irradiation method of electron beams, three methods, that is, the fixed irradiation method, the moving irradiation method, and the spot irradiation method were examined. In the fixed irradiation method and moving one, stationary solar cells and solar cells moving by conveyer were irradiated by scanning electron beams, respectively. On the other hand, in the spot irradiation method, stationary solar cells were irradiated by non-scanning steady electron beams. It was concluded that the fixed irradiation method was the most proper method. In addition to this, in this study, some pieces of information were obtained with respect to the changes in the electrical characteristics of solar cells caused by the irradiation of electron beams. (author) 52 refs

  10. The Enhanced metastatic potential of hepatocellular carcinoma (HCC cells with sorafenib resistance.

    Directory of Open Access Journals (Sweden)

    Ariel Ka-Man Chow

    Full Text Available Acquired resistance towards sorafenib treatment was found in HCC patients, which results in poor prognosis. To investigate the enhanced metastatic potential of sorafenib resistance cells, sorafenib-resistant (SorR cell lines were established by long-term exposure of the HCC cells to the maximum tolerated dose of sorafenib. Cell proliferation assay and qPCR of ABC transporter genes (ABCC1-3 were first performed to confirm the resistance of cells. Migration and invasion assays, and immunoblotting analysis on the expression of epithelial to mesenchymal transition (EMT regulatory proteins were performed to study the metastatic potential of SorR cells. The expression of CD44 and CD133 were studied by flow cytometry and the gene expressions of pluripotency factors were studied by qPCR to demonstrate the enrichment of cancer stem cells (CSCs in SorR cells. Control (CTL and SorR cells were also injected orthotopically to the livers of NOD-SCID mice to investigate the development of lung metastasis. Increased expressions of ABCC1-3 were found in SorR cells. Enhanced migratory and invasive abilities of SorR cells were observed. The changes in expression of EMT regulatory proteins demonstrated an activation of the EMT process in SorR cells. Enriched proportion of CD44(+ and CD44(+CD133(+ cells were also observed in SorR cells. All (8/8 mice injected with SorR cells demonstrated lung metastasis whereas only 1/8 mouse injected with CTL cells showed lung metastasis. HCC cells with sorafenib resistance demonstrated a higher metastatic potential, which may be due to the activated EMT process. Enriched CSCs were also demonstrated in the sorafenib resistant cells. This study suggests that advanced HCC patients with acquired sorafenib resistance may have enhanced tumor growth or distant metastasis, which raises the concern of long-term sorafenib treatment in advanced HCC patients who have developed resistance of sorafenib.

  11. Multidrug-resistant hepatocellular carcinoma cells are enriched for ...

    African Journals Online (AJOL)

    Chemotherapy is a main treatment for cancer, while multidrug-resistance is the main reason for chemotherapy failure, and tumor relapse and metastasis. Cancer stem cells or cancer stem-like cells (CSCs) are a small subset of cancer cells, which may be inherently resistant to the cytotoxic effect of chemotherapy.

  12. Barbigerone reverses multidrug resistance in breast MCF-7/ADR cells.

    Science.gov (United States)

    Li, Xiuxia; Wan, Li; Wang, Fang; Pei, Heying; Zheng, Li; Wu, Wenshuang; Ye, Haoyu; Wang, Yanping; Chen, Lijuan

    2018-01-24

    Development of agents to overcome multidrug resistance (MDR) is one of the important strategies in cancer chemotherapy, and P-glycoprotein (P-gp) correlates with the degree of resistance. As a naturally occurring isoflavone, whether barbigerone (BA) could reverse MDR, is unknown. In this paper, we evaluated effects of BA on reversing P-gp mediated MDR of adriamycin (ADR)-resistant human breast carcinoma (MCF-7/ADR) cells. BA (0.5 μM) treatment showed strong potency to increase ADR cytotoxicity toward MCF-7/ADR cells. It was also demonstrated that BA time- and dose-dependently increased accumulations of ADR and reduced the efflux in MCF-7/ADR cells, pretreatment of these cells with BA might relocalized ADR to the nuclei. Furthermore, the results also revealed that BA did not affect P-gp, but alter P-gp ATPase activity. Intravenous administration of BA significantly increased anticancer efficacy of ADR to MCF-7/ADR xenograft model in nude mice. These results revealed that BA might reverse P-gp mediated MDR through inhibition of ATPase activity, which indicated a novel use of BA as a potent candidate for cancer chemotherapy. Copyright © 2018 John Wiley & Sons, Ltd.

  13. Decreased cisplatin uptake by resistant L1210 leukemia cells

    International Nuclear Information System (INIS)

    Hromas, R.A.; North, J.A.; Burns, C.P.

    1987-01-01

    Cisplatin resistance remains poorly understood compared to other forms of anti-neoplastic drug resistance. In this report radiolabelled cisplatin and rapid separation techniques were used to compare drug uptake by L1210 leukemia cells that are sensitive (K25) or resistant (SCR9) to cisplatin. Uptake of cisplatin by both cell lines was linear without saturation kinetics up to 100 μM. The resistant ZCR9 cells had 36-60% reduced drug uptake as compared to its sensitive parent line, K25. In contrast, there was no difference in the rate of efflux. We conclude that a decreased rate of uptake is one possible mechanism of cellular cisplatin resistance. (Author)

  14. Collective cell motility promotes chemotactic prowess and resistance to chemorepulsion.

    Science.gov (United States)

    Malet-Engra, Gema; Yu, Weimiao; Oldani, Amanda; Rey-Barroso, Javier; Gov, Nir S; Scita, Giorgio; Dupré, Loïc

    2015-01-19

    Collective cell migration is a widespread biological phenomenon, whereby groups of highly coordinated, adherent cells move in a polarized fashion. This migration mode is a hallmark of tissue morphogenesis during development and repair and of solid tumor dissemination. In addition to circulating as solitary cells, lymphoid malignancies can assemble into tissues as multicellular aggregates. Whether malignant lymphocytes are capable of coordinating their motility in the context of chemokine gradients is, however, unknown. Here, we show that, upon exposure to CCL19 or CXCL12 gradients, malignant B and T lymphocytes assemble into clusters that migrate directionally and display a wider chemotactic sensitivity than individual cells. Physical modeling recapitulates cluster motility statistics and shows that intracluster cell cohesion results in noise reduction and enhanced directionality. Quantitative image analysis reveals that cluster migration runs are periodically interrupted by transitory rotation and random phases that favor leader cell turnover. Additionally, internalization of CCR7 in leader cells is accompanied by protrusion retraction, loss of polarity, and the ensuing replacement by new leader cells. These mechanisms ensure sustained forward migration and resistance to chemorepulsion, a behavior of individual cells exposed to steep CCL19 gradients that depends on CCR7 endocytosis. Thus, coordinated cluster dynamics confer distinct chemotactic properties, highlighting unexpected features of lymphoid cell migration. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. 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.

  16. Treatment Resistance Mechanisms of Malignant Glioma Tumor Stem Cells

    International Nuclear Information System (INIS)

    Schmalz, Philip G.R.; Shen, Michael J.; Park, John K.

    2011-01-01

    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

  17. 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

    . 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...

  18. 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.

  19. Characterisation of multidrug-resistant Ehrlich ascites tumour cells selected in vivo for resistance to etoposide

    DEFF Research Database (Denmark)

    Nielsen, D; Maare, C; Eriksen, J

    2000-01-01

    -extractable immunoreactive topoisomerase IIalpha and beta in EHR2/VP16 was reduced by 30-40% relative to that in EHR2. The multidrug resistance-associated protein (MRP) mRNA was increased 20-fold in EHR2/VP16 as compared with EHR2, whereas the expression of P-glycoprotein was unchanged. In EHR2/VP16, the steady......M. ATPase activity was slightly stimulated by daunorubicin, whereas vinblastine, verapamil, and cyclosporin A had no effect. In conclusion, development of resistance to VP16 in EHR2 is accompanied by a significant reduction in topoisomerase II (alpha and beta) and by increased expression of MRP mRNA (20......An Ehrlich ascites tumour cell line (EHR2) was selected for resistance to etoposide (VP16) by in vivo exposure to this agent. The resulting cell line (EHR2/VP16) was 114.3-, 5.7-, and 4.0-fold resistant to VP16, daunorubicin, and vincristine, respectively. The amount of salt...

  20. /TiN Resistive RAM (RRAM) Cells

    Science.gov (United States)

    Chen, Z. X.; Fang, Z.; Wang, Y.; Yang, Y.; Kamath, A.; Wang, X. P.; Singh, N.; Lo, G.-Q.; Kwong, D.-L.; Wu, Y. H.

    2014-11-01

    We present a study of Ni silicide as the bottom electrode in HfO2-based resistive random-access memory cells. Various silicidation conditions were used for each device, yielding different Ni concentrations within the electrode. A higher concentration of Ni in the bottom electrode was found to cause a parasitic SET operation during certain RESET operation cycles, being attributed to field-assisted Ni cation migration creating a Ni filament. As such, the RESET is affected unless an appropriate RESET voltage is used. Bottom electrodes with lower concentrations of Ni were able to switch at ultralow currents (RESET current <1 nA) by using a low compliance current (<500 nA). The low current is attributed to the tunneling barrier formed by the native SiO2 at the Ni silicide/HfO2 interface.

  1. Cisplatin and low dose rate irradiation in cisplatin resistant and sensitive human glioma cells

    International Nuclear Information System (INIS)

    Wilkins, David E.; Cheng, E. Ng; Raaphorst, G. Peter

    1996-01-01

    Purpose: Human glioma cell lines resistant (U373MG CP ) and sensitive (U373MG) to cisplatin were used to evaluate the effect of cisplatin as a sensitizer to low dose rate irradiation (LDRI). Methods and Materials: A cisplatin resistant glioma cell line U373MG CP was developed by chronic exposure of parental U373MG cells to cisplatin. Plateau phase cells were treated with cisplatin, high dose rate (HDR) irradiation (1.12 Gy/min), LDRI (0.0088 Gy/min), or cisplatin concurrent with LDRI. Cell survival was determined by the colony forming assay. Results: Both cell lines showed increased resistance to radiation at LDR compared with HDR, with Dose Modifying Factors (DMF at 10% survival level) of 1.7 for U373MG and 2.5 for U373MG CP . The increased LDR sparing effect in the cisplatin resistant U373MG CP cells indicates increased repair proficiency. The resistant cell line showed a fourfold increase in resistance to cisplatin cytotoxicity at the 10% survival level compared with the parental U373MG cells. Cisplatin enhanced the response of both cell lines to LDRI. The DMFs were 1.2, 1.2, and 1.7, respectively, for the sensitive U373MG cell line given 1 μg/ml, and the resistant cell line given 3 or 6 μg/ml cisplatin treatments concurrent with LDRI. Conclusions: These data show that cisplatin can be an effective sensitizer to LDRI in both cisplatin resistant and sensitive glioma cell lines. However, in the resistant cell line, higher concentrations of cisplatin were necessary to achieve the same level of sensitization as in the sensitive cell line

  2. Development of radiation resistant PEEK insulation cable

    International Nuclear Information System (INIS)

    Mio, Keigo; Ogiwara, Norio; Hikichi, Yusuke; Furukori, Hisayoshi; Arai, Hideyuki; Nishizawa, Daiji; Nishidono, Toshiro

    2009-04-01

    Material characterization and development has been carried out for cable insulation suitable for use in the J-PARC 3-GeV RCS radiation environment. In spite of its high cost, PEEK (polyether-ether-ketone) has emerged as the leading candidate satisfying requirements of being non-halogen based, highly incombustible and with radiation resistant at least 10 MGy, along with the usual mechanical characteristics such as good elongation at break, which are needed in a cable insulation. Gamma-ray irradiation tests have been done in order to study radiation resistance of PEEK cable. Further, mechanical, electrical and fire retardant characteristics of a complete cable such as would be used at the J-PARC RCS were investigated. As a result, PEEK cables were shown to be not degraded by radiation up to at least 10 MGy, and thus could be expected to operate stably under the 3-GeV RCS radiation environment. (author)

  3. p-Glycoprotein ABCB5 and YB-1 expression plays a role in increased heterogeneity of breast cancer cells: correlations with cell fusion and doxorubicin resistance

    International Nuclear Information System (INIS)

    Yang, Ji Yeon; Ha, Seon-Ah; Yang, Yun-Sik; Kim, Jin Woo

    2010-01-01

    Cancer cells recurrently develop into acquired resistance to the administered drugs. The iatrogenic mechanisms of induced chemotherapy-resistance remain elusive and the degree of drug resistance did not exclusively correlate with reductions of drug accumulation, suggesting that drug resistance may involve additional mechanisms. Our aim is to define the potential targets, that makes drug-sensitive MCF-7 breast cancer cells turn to drug-resistant, for the anti-cancer drug development against drug resistant breast cancer cells. Doxorubicin resistant human breast MCF-7 clones were generated. The doxorubicin-induced cell fusion events were examined. Heterokaryons were identified and sorted by FACS. In the development of doxorubicin resistance, cell-fusion associated genes, from the previous results of microarray, were verified using dot blot array and quantitative RT-PCR. The doxorubicin-induced expression patterns of pro-survival and pro-apoptotic genes were validated. YB-1 and ABCB5 were up regulated in the doxorubicin treated MCF-7 cells that resulted in certain degree of genomic instability that accompanied by the drug resistance phenotype. Cell fusion increased diversity within the cell population and doxorubicin resistant MCF-7 cells emerged probably through clonal selection. Most of the drug resistant hybrid cells were anchorage independent. But some of the anchorage dependent MCF-7 cells exhibited several unique morphological appearances suggesting minor population of the fused cells maybe de-differentiated and have progenitor cell like characteristics. Our work provides valuable insight into the drug induced cell fusion event and outcome, and suggests YB-1, GST, ABCB5 and ERK3 could be potential targets for the anti-cancer drug development against drug resistant breast cancer cells. Especially, the ERK-3 serine/threonine kinase is specifically up-regulated in the resistant cells and known to be susceptible to synthetic antagonists

  4. JNK at the crossroad of obesity, insulin resistance, and cell stress response

    OpenAIRE

    Solinas, Giovanni; Becattini, Barbara

    2016-01-01

    Background: The cJun-N-terminal-kinase (JNK) plays a central role in the cell stress response, with outcomes ranging from cell death to cell proliferation and survival, depending on the specific context. JNK is also one of the most investigated signal transducers in obesity and insulin resistance, and studies have identified new molecular mechanisms linking obesity and insulin resistance. Emerging evidence indicates that whereas JNK1 and JNK2 isoforms promote the development of obesity and in...

  5. Development of ghrelin resistance in a cancer cachexia rat model using human gastric cancer-derived 85As2 cells and the palliative effects of the Kampo medicine rikkunshito on the model

    Science.gov (United States)

    Sawada, Yumi; Hashimoto, Hirofumi; Yoshimura, Mitsuhiro; Ohbuchi, Katsuya; Sudo, Yuka; Suzuki, Masami; Miyano, Kanako; Shiraishi, Seiji; Higami, Yoshikazu; Yanagihara, Kazuyoshi; Hattori, Tomohisa; Kase, Yoshio; Ueta, Yoichi; Uezono, Yasuhito

    2017-01-01

    Cancer cachexia (CC) is a multifactorial disease characterized by decreased food intake and loss of body weight due to reduced musculature with or without loss of fat mass. Patients with gastric cancer have a high incidence of cachexia. We previously established a novel CC rat model induced by human gastric cancer-derived 85As2 cells in order to examine the pathophysiology of CC and identify potential therapeutics. In patients with CC, anorexia is often observed, despite elevation of ghrelin, suggesting that ghrelin resistance may develop in these patients. In this study, we aimed to clarify the occurrence of ghrelin resistance in CC rats accompanied by anorexia and we investigated whether rikkunshito (RKT), a traditional Japanese Kampo medicine that potentiates ghrelin signaling, ameliorated CC-related anorexia through alleviation of ghrelin resistance. 85As2-tumor-bearing rats developed severe CC symptoms, including anorexia and loss of body weight/musculature, with the latter symptoms being greater in cachectic rats than in non-tumor-bearing or pair-fed rats. CC rats showed poor responses to intraperitoneal injection of ghrelin. In CC rats, plasma ghrelin levels were elevated and hypothalamic anorexigenic peptide mRNA levels were decreased, whereas hypothalamic growth hormone secretagogue receptor (GHS-R) mRNA was not affected. In vitro, RKT directly enhanced ghrelin-induced GHS-R activation. RKT administrated orally for 7 days partly alleviated the poor response to ghrelin and ameliorated anorexia without affecting the elevation of plasma ghrelin levels in CC rats. The expression of hypothalamic orexigenic neuropeptide Y mRNA but not hypothalamic GHS-R mRNA was increased by RKT. Thus, the 85As2 cell-induced CC rat model developed ghrelin resistance, possibly contributing to anorexia and body weight loss. The mechanism through which RKT ameliorated anorexia in the CC rat model may involve alleviation of ghrelin resistance by enhancement of ghrelin signaling

  6. Tumor cell heterogeneity: impact on mechanisms of therapeutic drug resistance

    International Nuclear Information System (INIS)

    Richardson, Mary E.; Siemann, Dietmar W.

    1997-01-01

    Purpose: The aim of these studies was to determine whether chemotherapy-resistant tumor cell sublines derived from a single starting cell population with identical treatment protocols, have the same mechanism of resistance. Methods and Materials: Twelve cyclophosphamide-resistant sublines were derived from KHT-iv murine sarcoma cells by repeated exposures to 2, 4, or 8 μg/ml doses of 4-hydroperoxycyclophosphamide (4-OOHCP). To investigate possible mechanisms of resistance, glutathione (GSH) levels, glutathione S-transferase (GST) activity, and aldehyde dehydrogenase (ALDH) activity were determined. In addition, studies with the GSH depletor buthionine sulfoximine (BSO) and the ALDH inhibitor diethylamino-benzaldehyde (DEAB) were undertaken. Results: Resistant factors to 4-OOHCP, assessed at 10% clonogenic cell survival, ranged from 1.5-7.0 for the various cell lines. Crossresistance to melphalan and adriamycin also were commonly observed. Increased GSH levels, GST activity and ALDH activity were detected in the sublines but not all exhibited the same pattern of biochemical alterations. The response to GSH and ALDH inhibitors also varied among the sublines; the resistance being reversible in some cell lines but not others. Conclusion: The present results indicate that when resistant sublines are derived simultaneously from the same starting cell population, the observed mechanisms of resistance may not be the same in each of the variants. These findings support the hypothesis that preexisting cellular heterogeneity may affect mechanisms of acquired resistance

  7. 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...

  8. Space solar cell technology development - A perspective

    Science.gov (United States)

    Scott-Monck, J.

    1982-01-01

    The developmental history of photovoltaics is examined as a basis for predicting further advances to the year 2000. Transistor technology was the precursor of solar cell development. Terrestrial cells were modified for space through changes in geometry and size, as well as the use of Ag-Ti contacts and manufacture of a p-type base. The violet cell was produced for Comsat, and involved shallow junctions, new contacts, and an enhanced antireflection coating for better radiation tolerance. The driving force was the desire by private companies to reduce cost and weight for commercial satellite power supplies. Liquid phase epitaxial (LPE) GaAs cells are the latest advancement, having a 4 sq cm area and increased efficiency. GaAs cells are expected to be flight ready in the 1980s. Testing is still necessary to verify production techniques and the resistance to electron and photon damage. Research will continue in CVD cell technology, new panel technology, and ultrathin Si cells.

  9. Identification of resistance mechanisms in erlotinib-resistant subclones of the non-small cell lung cancer cell line HCC827 by exome sequencing

    DEFF Research Database (Denmark)

    Jacobsen, Kirstine; Alcaraz, Nicolas; Lund, Rikke Raaen

    the SeqCap EZ Human Exome Library v3.0 kit and whole-exome sequencing of these (100 bp paired-end) were performed on an Illumina HiSeq 2000 platform. Using a recently developed in-house analysis pipeline the sequencing data were analyzed. The analysis pipeline includes quality control using Trim......Background: Erlotinib (Tarceva®, Roche) has significantly changed the treatment of non-small cell lung cancer (NSCLC) as 70% of patients show significant tumor regression upon treatment (Santarpia et. al., 2013). However, all patients relapse due to development of acquired resistance, which...... mutations in erlotinib-resistant subclones of the NSCLC cell line, HCC827. Materials & Methods: We established 3 erlotinib-resistant subclones (resistant to 10, 20, 30 µM erlotinib, respectively). DNA libraries of each subclone and the parental HCC827 cell line were prepared in biological duplicates using...

  10. Reduced expression of p27 is a novel mechanism of docetaxel resistance in breast cancer cells

    International Nuclear Information System (INIS)

    Brown, Iain; Shalli, Kawan; McDonald, Sarah L; Moir, Susan E; Hutcheon, Andrew W; Heys, Steven D; Schofield, Andrew C

    2004-01-01

    Docetaxel is one of the most effective chemotherapeutic agents in the treatment of breast cancer. Breast cancers can have an inherent or acquired resistance to docetaxel but the causes of this resistance remain unclear. However, apoptosis and cell cycle regulation are key mechanisms by which most chemotherapeutic agents exert their cytotoxic effects. We created two docetaxel-resistant human breast cancer cell lines (MCF-7 and MDA-MB-231) and performed cDNA microarray analysis to identify candidate genes associated with docetaxel resistance. Gene expression changes were validated at the RNA and protein levels by reverse transcription PCR and western analysis, respectively. Gene expression cDNA microarray analysis demonstrated reduced p27 expression in docetaxel-resistant breast cancer cells. Although p27 mRNA expression was found to be reduced only in MCF-7 docetaxel-resistant sublines (2.47-fold), reduced expression of p27 protein was noted in both MCF-7 and MDA-MB-231 docetaxel-resistant breast cancer cells (2.83-fold and 3.80-fold, respectively). This study demonstrates that reduced expression of p27 is associated with acquired resistance to docetaxel in breast cancer cells. An understanding of the genes that are involved in resistance to chemotherapy may allow further development in modulating drug resistance, and may permit selection of those patients who are most likely to benefit from such therapies

  11. Effects of c-myc oncogene modulation on drug resistance in human small cell lung carcinoma cell lines

    NARCIS (Netherlands)

    vanWaardenburg, RCAM; Meijer, C; Uges, DRA; deVries, EGE; Mulder, NH

    1996-01-01

    Small cell lung carcinoma (SCLC) is characterized by rapid development of resistance to drugs, such as cis-diamminedichloroplatinum(II) (cDDP) and anthracyclines. The molecular basis for resistance to cDDP and adriamycin (Adr) is poorly understood. One of the genetic alterations observed in SCLC,

  12. Rolling Resistance Measurement and Model Development

    DEFF Research Database (Denmark)

    Andersen, Lasse Grinderslev; Larsen, Jesper; Fraser, Elsje Sophia

    2015-01-01

    There is an increased focus worldwide on understanding and modeling rolling resistance because reducing the rolling resistance by just a few percent will lead to substantial energy savings. This paper reviews the state of the art of rolling resistance research, focusing on measuring techniques......, surface and texture modeling, contact models, tire models, and macro-modeling of rolling resistance...

  13. [Role of oral cavity colonization resistance in dental caries development].

    Science.gov (United States)

    Petrushanko, T A; Chereda, V V; Loban', G A

    2013-01-01

    Colonization resistance is one of local immunity mechanisms determined by a combination of factors that inhibit the adhesion and growth of mucous membrane bacteria. We examined patients with different levels of caries intensity assessing oral mucosa colonization resistance by our own method. Caries development resulted in changes of colonization resistance with the increased rate of inhibition of the oral mucosa colonization resistance barrier.

  14. Inhibition of PARP1 activity enhances chemotherapeutic efficiency in cisplatin-resistant gastric cancer cells.

    Science.gov (United States)

    Wang, Qiang; Xiong, Jianping; Qiu, Danping; Zhao, Xue; Yan, Donglin; Xu, Wenxia; Wang, Zhangding; Chen, Qi; Panday, Sapna; Li, Aiping; Wang, Shouyu; Zhou, Jianwei

    2017-11-01

    Cisplatin (DDP) is the first line chemotherapeutic drug for several cancers, including gastric cancer (GC). Unfortunately, the rapid development of drug resistance remains a significant challenge for the clinical application of cisplatin. There is an urgent need to develop new strategies to overcome DDP resistance for cancer treatment. In this study, four types of human GC cells have been divided into naturally sensitive or naturally resistant categories according to their responses to cisplatin. PARP1 activity (poly (ADP-ribose), PAR) was found to be greatly increased in cisplatin-resistant GC cells. PARP1 inhibitors significantly enhanced cisplatin-induced DNA damage and apoptosis in the resistant GC cells via the inhibition of PAR. Mechanistically, PARP1 inhibitors suppress DNA-PKcs stability and reduce the capability of DNA double-strand break (DSB) repair via the NHEJ pathway. This was also verified in BGC823/DDP GC cells with acquired cisplatin resistance. In conclusion, we identified that PARP1 is a useful interceptive target in cisplatin-resistant GC cells. Our data provide a promising therapeutic strategy against cisplatin resistance in GC cells that has potential translational significance. Copyright © 2017. Published by Elsevier Ltd.

  15. Optical imaging of radiation-induced metabolic changes in radiation-sensitive and resistant cancer cells

    Science.gov (United States)

    Alhallak, Kinan; Jenkins, Samir V.; Lee, David E.; Greene, Nicholas P.; Quinn, Kyle P.; Griffin, Robert J.; Dings, Ruud P. M.; Rajaram, Narasimhan

    2017-06-01

    Radiation resistance remains a significant problem for cancer patients, especially due to the time required to definitively determine treatment outcome. For fractionated radiation therapy, nearly 7 to 8 weeks can elapse before a tumor is deemed to be radiation-resistant. We used the optical redox ratio of FAD/(FAD+NADH) to identify early metabolic changes in radiation-resistant lung cancer cells. These radiation-resistant human A549 lung cancer cells were developed by exposing the parental A549 cells to repeated doses of radiation (2 Gy). Although there were no significant differences in the optical redox ratio between the parental and resistant cell lines prior to radiation, there was a significant decrease in the optical redox ratio of the radiation-resistant cells 24 h after a single radiation exposure (p=0.01). This change in the redox ratio was indicative of increased catabolism of glucose in the resistant cells after radiation and was associated with significantly greater protein content of hypoxia-inducible factor 1 (HIF-1α), a key promoter of glycolytic metabolism. Our results demonstrate that the optical redox ratio could provide a rapid method of determining radiation resistance status based on early metabolic changes in cancer cells.

  16. Physical Intimacy of Breast Cancer Cells with Mesenchymal Stem Cells Elicits Trastuzumab Resistance through Src Activation

    Science.gov (United States)

    Daverey, Amita; Drain, Allison P.; Kidambi, Srivatsan

    2015-01-01

    The development of resistance to trastuzumab is a major obstacle for lasting effective treatment of patients with ErbB2-overexpressing tumors. Here, we demonstrate that the physical contact of breast cancer cells with mesenchymal stem cells (MSCs) is a potential modulator of trastuzumab response by activation of nonreceptor tyrosine kinase c-Src and down regulation of phosphatase and tensin homolog (PTEN). Using an in vitro patterned breast cancer/MSC co-culture model, we find that the presence of MSCs results in Src activation that is missing in cancer cells monoculture, transwell co-culture, and cells treated with MSCs conditioned media. Interestingly, the co-culture model also results in PTEN loss and activation of PI3K/AKT pathway that has been demonstrated as fundamental proliferative and survival pathways in clinical settings. To our knowledge, this is the first report that showed PTEN loss without the use of chemical inhibitors, matrix stiffness, or silencing RNAs. In addition, breast cancer cells in co-culture with MSCs conferred trastuzumab resistance in vitro as observed in the lack of inhibition of proliferative and migrative properties of the cancer cells. Our findings show that MSCs are potent mediators of resistance to trastuzumab and might reveal targets to enhance trastuzumab efficacy in patients. PMID:26345302

  17. Phytosphingosine can overcome resistance to ionizing radiation in ionizing radiation-resistant cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Park, Moon Taek; Choi, Jung A; Kim, Min Jeong; Bae, Sang Woo; Kang, Chang Mo; Cho, Chul Koo; Lee, Yun Sil; Lee, Su Jae [Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of); Kang, Seong Man [Graduate School of Biotechnology, Korea University, Seoul (Korea, Republic of); Chung, Hee Yong [College of Medicine, Hanyang University, Seoul (Korea, Republic of)

    2004-07-01

    Although the majority of cancer cells are killed by inonizing radiation, certain types show resistance to it. We previously reported that phytosphingosine also induces apoptotic cell death in caspase dependent pathway in human cancer cells. In the present study, we examined whether phytosphingosine could overcome radiation resistance in the variant Jurkat clones. We first selected radiation-resistant Jurkat clones and examined cross-responsiveness of the clones between radiation and phytosphingosine. Treatment with phytosphingosine significantly did not affect apoptosis in all the clones, indicating that there seemed to be cross-resistance between radiation and phytosphingosine. Nevertheless, combined treatment of phytosphingosine with radiation synergistically enhanced killing of radiation-resistant cells, compared to radiation or phytosphingosine alone. The pan-caspase inhibitor z-VAD-fmk did not completely inhibit the synergistic cell killing induced by combined treatment of ionizing radiation and phytosphingosine. These results demonstrated that apoptosis induced by combined treatment of radiation and phytosphingosine in radiation-resistant cells was associated with caspase independent pathway. We also found that apoptotic cell death induced by combined treatment of ionizing radiation and phytosphingosine correlated to the increases of ROS. The enhancement of ROS generation induced the loss of mitochondria transmembrane potential. In conclusion, ROS generation in combined treatment of phytosphingosine with radiation significantly induced the translocation of AIF to nucleus from mitochondria, suggesting a potential clinical application of combination treatment of radiation and phytosphingosine to radiation-resistant cancer cells.

  18. Phytosphingosine can overcome resistance to ionizing radiation in ionizing radiation-resistant cancer cells

    International Nuclear Information System (INIS)

    Park, Moon Taek; Choi, Jung A; Kim, Min Jeong; Bae, Sang Woo; Kang, Chang Mo; Cho, Chul Koo; Lee, Yun Sil; Lee, Su Jae; Park, Moon Taek; Choi, Jung A; Kim, Min Jeong; Kang, Seong Man; Chung, Hee Yong

    2004-01-01

    Although the majority of cancer cells are killed by inonizing radiation, certain types show resistance to it. We previously reported that phytosphingosine also induces apoptotic cell death in caspase dependent pathway in human cancer cells. In the present study, we examined whether phytosphingosine could overcome radiation resistance in the variant Jurkat clones. We first selected radiation-resistant Jurkat clones and examined cross-responsiveness of the clones between radiation and phytosphingosine. Treatment with phytosphingosine significantly did not affect apoptosis in all the clones, indicating that there seemed to be cross-resistance between radiation and phytosphingosine. Nevertheless, combined treatment of phytosphingosine with radiation synergistically enhanced killing of radiation-resistant cells, compared to radiation or phytosphingosine alone. The pan-caspase inhibitor z-VAD-fmk did not completely inhibit the synergistic cell killing induced by combined treatment of ionizing radiation and phytosphingosine. These results demonstrated that apoptosis induced by combined treatment of radiation and phytosphingosine in radiation-resistant cells was associated with caspase independent pathway. We also found that apoptotic cell death induced by combined treatment of ionizing radiation and phytosphingosine correlated to the increases of ROS. The enhancement of ROS generation induced the loss of mitochondria transmembrane potential. In conclusion, ROS generation in combined treatment of phytosphingosine with radiation significantly induced the translocation of AIF to nucleus from mitochondria, suggesting a potential clinical application of combination treatment of radiation and phytosphingosine to radiation-resistant cancer cells

  19. Candida Biofilms: Development, Architecture, and Resistance

    Science.gov (United States)

    CHANDRA, JYOTSNA; MUKHERJEE, PRANAB K.

    2015-01-01

    Intravascular device–related infections are often associated with biofilms (microbial communities encased within a polysaccharide-rich extracellular matrix) formed by pathogens on the surfaces of these devices. Candida species are the most common fungi isolated from catheter-, denture-, and voice prosthesis–associated infections and also are commonly isolated from contact lens–related infections (e.g., fungal keratitis). These biofilms exhibit decreased susceptibility to most antimicrobial agents, which contributes to the persistence of infection. Recent technological advances have facilitated the development of novel approaches to investigate the formation of biofilms and identify specific markers for biofilms. These studies have provided extensive knowledge of the effect of different variables, including growth time, nutrients, and physiological conditions, on biofilm formation, morphology, and architecture. In this article, we will focus on fungal biofilms (mainly Candida biofilms) and provide an update on the development, architecture, and resistance mechanisms of biofilms. PMID:26350306

  20. Magic bullets to fight resistance : Uncovering how peptide-antibiotics break down the bacterial cell envelope

    NARCIS (Netherlands)

    Medeiros-Silva, J.|info:eu-repo/dai/nl/288254600; Jekhmane, S.|info:eu-repo/dai/nl/412782715; Breukink, E.|info:eu-repo/dai/nl/120305100; Weingarth, M.|info:eu-repo/dai/nl/330985655

    The rapid rise of resistant bacteria urgently calls for novel antibiotics that are robust to resistance development. Ideal templates could be peptide-antibiotics that destroy the bacterial cell wall by binding to its membrane-anchored precursor lipid II at irreplaceable phosphate groups. Indeed,

  1. From 1 Sun to 10 Suns c-Si Cells by Optimizing Metal Grid, Metal Resistance, and Junction Depth

    International Nuclear Information System (INIS)

    Chaudhari, V.A.; Solanki, C.S.

    2009-01-01

    Use of a solar cell in concentrator PV technology requires reduction in its series resistance in order to minimize the resistive power losses. The present paper discusses a methodology of reducing the series resistance of a commercial c-Si solar cell for concentrator applications, in the range of 2 to 10 suns. Step by step optimization of commercial cell in terms of grid geometry, junction depth, and electroplating of the front metal contacts is proposed. A model of resistance network of solar cell is developed and used for the optimization. Efficiency of un optimized commercial cell at 10 suns drops by 30% of its 1 sun value corresponding to resistive power loss of about 42%. The optimized cell with grid optimization, junction optimization, electroplating, and junction optimized with electroplated contacts cell gives resistive power loss of 20%, 16%, 11%, and 8%, respectively. An efficiency gain of 3% at 10 suns for fully optimized cell is estimated

  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. Development of IFN-gamma resistance is associated with attenuation of SOCS genes induction and constitutive expression of SOCS 3 in melanoma cells

    Czech Academy of Sciences Publication Activity Database

    Fojtová, Miloslava; Boudný, V.; Kovařík, Aleš; Lauerová, L.; Adámková, L.; Součková, K.; Jarkovský, J.; Kovařík, J.

    2007-01-01

    Roč. 97, č. 2 (2007), s. 231-237 ISSN 0007-0920 Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : SOCS protein * malignant melanoma * interferon resistance Subject RIV: BO - Biophysics Impact factor: 4.635, year: 2007

  4. Raman spectroscopy differentiates between sensitive and resistant multiple myeloma cell lines

    Science.gov (United States)

    Franco, Domenico; Trusso, Sebastiano; Fazio, Enza; Allegra, Alessandro; Musolino, Caterina; Speciale, Antonio; Cimino, Francesco; Saija, Antonella; Neri, Fortunato; Nicolò, Marco S.; Guglielmino, Salvatore P. P.

    2017-12-01

    Current methods for identifying neoplastic cells and discerning them from their normal counterparts are often nonspecific and biologically perturbing. Here, we show that single-cell micro-Raman spectroscopy can be used to discriminate between resistant and sensitive multiple myeloma cell lines based on their highly reproducible biomolecular spectral signatures. In order to demonstrate robustness of the proposed approach, we used two different cell lines of multiple myeloma, namely MM.1S and U266B1, and their counterparts MM.1R and U266/BTZ-R subtypes, resistant to dexamethasone and bortezomib, respectively. Then, micro-Raman spectroscopy provides an easily accurate and noninvasive method for cancer detection for both research and clinical environments. Characteristic peaks, mostly due to different DNA/RNA ratio, nucleic acids, lipids and protein concentrations, allow for discerning the sensitive and resistant subtypes. We also explored principal component analysis (PCA) for resistant cell identification and classification. Sensitive and resistant cells form distinct clusters that can be defined using just two principal components. The identification of drug-resistant cells by confocal micro-Raman spectroscopy is thus proposed as a clinical tool to assess the development of resistance to glucocorticoids and proteasome inhibitors in myeloma cells.

  5. 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.

  6. [Role of SOX4 on DDP Resistance in Non-small Cell Lung Cancer Cell of A549].

    Science.gov (United States)

    Li, Wei; Liu, Xu; Zhang, Guoqian; Zhang, Linlin

    2017-05-20

    Lung cancer is one of the most serious disease and the incidence of non-small cell lung cancer (NSCLC) is the highest in lung cancer. The main reason for the failure of chemotherapy is the tolerance to cisplatin. Transcriptional regulator SOX4 plays an important role in the occurrence and development of many tumors, and regulates Wnt signaling pathway by regulating the expression of β-catenin. We aimed to investigate the role of SOX4 on cisplatin-resistance in NSCLC cell A549 cell. The cisplatin-resistance lung cancer cell line A549/DDP was constructed by induction method in vitro, and cisplatin-resistance detected by CCK8 assay. Growth curves of A549 and A549/DDP was calculated. The expression level of SOX4 in A549 and A549/DDP cells were detected by Western blot. A549/DDP were knockdown of SOX4 by siRNA transfection, and the cisplatin-resistance of detected by CCK-8 assay, the expression level of β-catenin and Survivin were detected by real-time PCR and Western blot. The cisplatin-resistance cell line A549/DDP was constructed successfully, and its cisplatin-resistance is 13.7 times higher than in A549. There was no significance difference between A549 and A549/DDP in cell proliferation. The expression level of SOX4 is higher in A549/DDP than in A549. The cisplatin-resistance significantly decreased in A549/DDP cells after knockdown of SOX4 by siRNA transfection. The expression level of β-catenin and Survivin significantly decreased in A549/DDP cells after knockdown of SOX4. SOX4 can strengthen cisplatin-resistance of non-small cell lung cancer cell A549.
.

  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. Role of free radicals in an adriamycin-resistant human small cell lung cancer cell line

    NARCIS (Netherlands)

    Meijer, C.; Mulder, N H; Timmer-Bosscha, H; Zijlstra, J G; de Vries, E G

    1987-01-01

    In two Adriamycin (Adr) resistant sublines (GLC4-Adr1 and GLC4-Adr2) of a human small cell lung carcinoma cell line, GLC4, cross-resistance for radiation was found. GLC4-Adr1 has an acquired Adr resistance factor of 44 after culturing without Adr for 20 days and GLC4-Adr2, the same subline cultured

  9. Volatile resistance states in electrochemical metallization cells enabling non-destructive readout of complementary resistive switches

    International Nuclear Information System (INIS)

    Van den Hurk, Jan; Linn, Eike; Waser, Rainer; Zhang, Hehe; Valov, Ilia

    2014-01-01

    Redox-based resistive memory cells exhibit changes of OFF or intermediate resistance values over time and even ON states can be completely lost in certain cases. The stability of these resistance states and the time until resistance loss strongly depends on the materials system. On the basis of electrical measurements and chemical analysis we found a viable explanation for these volatile resistance states (VRSs) in Ag-GeS x -based electrochemical metallization memory cells and identified a technological application in the field of crossbar memories. Complementary resistive switches usually suffer from the necessity of a destructive read-out procedure increasing wear and reducing read-out speed. From our analysis we deduced a solution to use the VRS as an inherent selector mechanism without the need for additional selector devices. (paper)

  10. Theory of the high base resistivity n(+)pp(+) silicon solar cell and its application to radiation damage effects

    Science.gov (United States)

    Goradia, C.; Weinberg, I.

    1985-01-01

    Particulate radiation in space is a principal source of silicon solar cell degradation, and an investigation of cell radiation damage at higher base resistivities appears to have implication toward increasing solar cell and, therefore, useful satellite lifetimes in the space environment. However, contrary to expectations, it has been found that for cells with resistivities of 84 and 1250 ohm cm, the radiation resistance decreases as cell base resistivity increases. An analytical solar-cell computer model was developed with the objective to determine the reasons for this unexpected behavior. The present paper has the aim to describe the analytical model and its use in interpreting the behavior, under irradiation, of high-resistivity solar cells. Attention is given to boundary conditions at the space-charge region edges, cell currents, cell voltages, the generation of the theoretical I-V characteristic, experimental results, and computer calculations.

  11. Tumourigenicity and radiation resistance of mesenchymal stem cells

    DEFF Research Database (Denmark)

    D'Andrea, Filippo P; Horsman, Michael Robert; Kassem, Moustapha

    2011-01-01

    . 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...

  12. High expression of leptin receptor leads to temozolomide resistance with exhibiting stem/progenitor cell features in gliobalastoma.

    Science.gov (United States)

    Han, Guosheng; Wang, Laixing; Zhao, Wenyuan; Yue, Zhijian; Zhao, Rui; Li, Yanan; Zhou, Xiaoping; Hu, Xiaowu; Liu, Jianmin

    2013-12-15

    Glioblastoma is a highly aggressive malignant disease with notable resistance to chemotherapy. In this study, we found that leptin receptor (ObR)-positive glioblastoma cells were resistant to temozolomide (TMZ), and TMZ-resistant cells exhibited high expression of ObR. ObR can serve as a marker to enrich glioblastoma cells with some stem/progenitor cell traits, which explained the reason for TMZ resistance of ObR+ cells. STAT3-mediated SOX2/OCT4 signaling axis maintained the stem/progenitor cell properties of ObR+ cells, which indirectly regulated glioblastoma TMZ resistance. These findings gain insight into the molecular link between obesity and glioblastoma, and better understanding of this drug-resistant population may lead to the development of more effective therapeutic interventions for glioblastoma.

  13. Haplopappus gracilis cell strains resistant to pyrimidine analogues.

    Science.gov (United States)

    Jones, G E; Hann, J

    1979-03-01

    Strains of Haplopappus gracilis (Nutt.) Gray cells resistant to 6-azauracil have been isolated from cultures of diploid cells. These strains are also resistant to 8-azaguanine, as is their parent. The variants are 100- to 125-fold more resistant to 6-azauracil than their parent, and they exhibit different spectra of cross resistance to other pyrimidine analogues. The phenotype of each variant is stable in the absence of selection. The majority of cells in cultures of the variants are diploid; all others examined were tetraploid. Initial rates of uptake of uracil are not reduced in the variants. Fluorouracil, to which two variants are resistant, is taken up by one of them as well as by the parent. Responses of the other two to fluorouracil are not correlated with decreased ability to accumulate this analogue.

  14. Comparison of western blot analysis and immunocytochemical detection of P-glycoprotein in multidrug resistant cells.

    OpenAIRE

    Friedlander, M L; Bell, D R; Leary, J; Davey, R A

    1989-01-01

    A sensitive immunocytochemical technique was developed to detect a 170,000 dalton cell membrane glycoprotein (P-gp) in cell lines resistant to vincristine and vinblastine with varying degrees of resistance. P-gp was shown very clearly using the C219 monoclonal antibody and immunocytochemical detection with either antialkaline phosphate or peroxidase-antiperoxidase with silver gold intensification. There was good correlation between the results obtained with immunocytochemical detection of P-g...

  15. 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.

  16. Development of Antibiotic Resistance during Simulated Treatment of Pseudomonas aeruginosa in Chemostats.

    Science.gov (United States)

    Feng, Yanfang; Hodiamont, Caspar J; van Hest, Reinier M; Brul, Stanley; Schultsz, Constance; Ter Kuile, Benno H

    2016-01-01

    During treatment of infections with antibiotics in critically ill patients in the intensive care resistance often develops. This study aims to establish whether under those conditions this resistance can develop de novo or that genetic exchange between bacteria is by necessity involved. Chemostat cultures of Pseudomonas aeruginosa were exposed to treatment regimes with ceftazidime and meropenem that simulated conditions expected in patient plasma. Development of antibiotic resistance was monitored and mutations in resistance genes were searched for by sequencing PCR products. Even at the highest concentrations that can be expected in patients, sufficient bacteria survived in clumps of filamentous cells to recover and grow out after 3 to 5 days. At the end of a 7 days simulated treatment, the minimal inhibitory concentration (MIC) had increased by a factor between 10 and 10,000 depending on the antibiotic and the treatment protocol. The fitness costs of resistance were minimal. In the resistant strains, only three mutations were observed in genes associated with beta-lactam resistance. The development of resistance often observed during patient treatment can be explained by de novo acquisition of resistance and genetic exchange of resistance genes is not by necessity involved. As far as conclusions based on an in vitro study using P. aeruginosa and only two antibiotics can be generalized, it seems that development of resistance can be minimized by treating with antibiotics in the highest concentration the patient can endure for the shortest time needed to eliminate the infection.

  17. Inhibition of autophagy by andrographolide resensitizes cisplatin-resistant non-small cell lung carcinoma cells via activation of the Akt/mTOR pathway

    International Nuclear Information System (INIS)

    Mi, Shanwei; Xiang, Gang; Yuwen, Daolu; Gao, Jian; Guo, Wenjie; Wu, Xuefeng; Wu, Xudong; Sun, Yang; Su, Yongqian; Shen, Yan; Xu, Qiang

    2016-01-01

    Resistance to cisplatin is a major obstacle for the success of non-small cell lung cancer therapy. The mechanisms underlying cisplatin resistance are not fully understood. In this study, we found that the increase of basal auotophagy accompanied the development of cisplatin resistance. Meanwhile the blockade of the Akt/mTOR pathway occurred in the process. Inhibition of this pathway was induced by cisplatin treatment in the resistant non-small cell lung carcinoma cells. Andrographolide, a natural diterpenoid, promoted the activation of the Akt/mTOR signaling by downregulating PTEN and suppressed autophagy, which subsequently resensitized the resistant cells to cisplatin-mediated apoptosis. Cisplatin treatment in combination with andrographolide significantly prevented the growth of the resistant cells in vivo. These results highlight the involvement of autophagy in cisplatin-resistance development and suggest that inhibition of autophagy via tuning the Akt/mTOR signaling could be a promising strategy in the therapy for cisplatin-resistant non-small cell lung cancer. - Highlights: • The increase of basal auotophagy accompanied the development of cisplatin resistance in NSCLC cells. • Cisplatin induced the blockade of the Akt/mTOR pathway. • Andrographolide promoted the activation of the Akt/mTOR signaling. • Andrographolide downregulated PTEN expression. • Cisplatin treatment in combination with andrographolide resensitized the resistant cells to cisplatin.

  18. Parallel selection of chemotherapy-resistant cell lines to illuminate mechanisms of drug resistance in human tumors

    DEFF Research Database (Denmark)

    Krzystanek, Marcin; Eklund, Aron Charles; Birkbak, Nicolai Juul

    2011-01-01

    of the experimental system. Doxorubicin is an anthracycline that exerts its anticancer effect through intercalation into DNA and inhibition of topoisomerase II, whereas paclitaxel stabilizes microtubules and disrupts the mitotic spindle. We use expression and copy number data from two cell lines, MDA-231 and MCF-7...... the identification of reliable predictive biomarkers for each drug. Currently, we are developing a framework for systematic biomarker discovery by using a combination of gene expression and CGH arrays to keep track of consistent changes that take place during resistance acquisition in cell lines towards two anti......-cancer drugs: doxorubicin and paclitaxel. By monitoring changes at two different levels (DNA and RNA) of the genome and developing multiple cell lines developing resistance against the same drug under identical conditions, we were able to separate relevant changes from spurious ones and thus reducing the noise...

  19. Chinese hamster pleiotropic multidrug-resistant cells are not radioresistant

    International Nuclear Information System (INIS)

    Mitchell, J.B.; Gamson, J.; Russo, A.; Friedman, N.; DeGraff, W.; Carmichael, J.; Glatstein, E.

    1988-01-01

    The inherent cellular radiosensitivity of a Chinese hamster ovary pleiotropic cell line that is multidrug resistant (CHRC5) was compared to that of its parental cell line (AuxB1). Radiation survival curve parameters n and D0 were 4.5 and 1.1 Gy, respectively, for the CHRC5 line and 5.0 and 1.2 Gy, respectively, for the parental line. Thus, the inherent radiosensitivity of the two lines was similar even though key intracellular free radical scavenging and detoxifying systems employing glutathione, glutathione transferase, and catalase produced enzyme levels that were 2.0-, 1.9-, and 1.9-fold higher, respectively, in the drug-resistant cell line. Glutathione depletion by buthionine sulfoximine resulted in the same extent of aerobic radiosensitization in both lines (approximately 10%). Incorporation of iododeoxyuridine into cellular DNA sensitized both cell lines to radiation. These studies indicate that pleiotropic drug resistance does not necessarily confer radiation resistance

  20. Discontinuing MEK inhibitors in tumor cells with an acquired resistance increases migration and invasion.

    Science.gov (United States)

    Nörz, Dominik; Grottke, Astrid; Bach, Johanna; Herzberger, Christiane; Hofmann, Bianca T; Nashan, Bjorn; Jücker, Manfred; Ewald, Florian

    2015-11-01

    Development of small molecular inhibitors against BRAF and MEK has been a breakthrough in the treatment of malignant melanoma. However, the long-term effect is foiled in virtually all patients by the emergence of resistant tumor cell populations. Therefore, mechanisms resulting in the acquired resistance against BRAF and MEK inhibitors have gained much attention and several strategies have been proposed to overcome tumor resistance, including interval treatment or withdrawal of these compounds after disease progression. Using a panel of cell lines with an acquired resistance against MEK inhibitors, we have evaluated the sensitivity of these cells against compounds targeting AKT/mTOR signaling, as well as novel ERK1/2 inhibitors. Furthermore, the effects of withdrawal of MEK inhibitor on migration in resistant cell lines were analyzed. We demonstrate that withdrawal of BRAF or MEK inhibitors in tumor cells with an acquired resistance results in reactivation of ERK1/2 signaling and upregulation of EMT-inducing transcription factors, leading to a highly migratory and invasive phenotype of cancer cells. Furthermore, we show that migration in these cells is independent from AKT/mTOR signaling. However, combined targeting of AKT/mTOR using MK-2206 and AZD8055 efficiently inhibits proliferation in all resistant tumor cell lines analyzed. We propose that combined targeting of MEK/AKT/mTOR or treatment with a novel ERK1/2 inhibitor downstream of BRAF/MEK suppresses proliferation as well as migration and invasion in resistant tumor cells. We provide a rationale against the discontinuation of BRAF or MEK inhibitors in patients with an acquired resistance, and provide a rationale for combined targeting of AKT/mTOR and MEK/ERK1/2, or direct targeting of ERK1/2 as an effective treatment strategy. Copyright © 2015 Elsevier Inc. All rights reserved.

  1. CD133 expression in chemo-resistant Ewing sarcoma cells

    Directory of Open Access Journals (Sweden)

    Kovar Heinrich

    2010-03-01

    Full Text Available Abstract Background Some human cancers demonstrate cellular hierarchies in which tumor-initiating cancer stem cells generate progeny cells with reduced tumorigenic potential. This cancer stem cell population is proposed to be a source of therapy-resistant and recurrent disease. Ewing sarcoma family tumors (ESFT are highly aggressive cancers in which drug-resistant, relapsed disease remains a significant clinical problem. Recently, the cell surface protein CD133 was identified as a putative marker of tumor-initiating cells in ESFT. We evaluated ESFT tumors and cell lines to determine if high levels of CD133 are associated with drug resistance. Methods Expression of the CD133-encoding PROM1 gene was determined by RT-PCR in ESFT tumors and cell lines. CD133 protein expression was assessed by western blot, FACS and/or immunostaining. Cell lines were FACS-sorted into CD133+ and CD133- fractions and proliferation, colony formation in soft agar, and in vivo tumorigenicity compared. Chemosensitivity was measured using MTS (3-(4,5-dimethylthiazol-2-yl-5-(3-carboxy-methoxyphenyl-2-(4-sulfophenyl-2H-tetrazolium assays. Results PROM1 expression was either absent or extremely low in most tumors. However, PROM1 was highly over-expressed in 4 of 48 cases. Two of the 4 patients with PROM1 over-expressing tumors rapidly succumbed to primary drug-resistant disease and two are long-term, event-free survivors. The expression of PROM1 in ESFT cell lines was similarly heterogeneous. The frequency of CD133+ cells ranged from 2-99% and, with one exception, no differences in the chemoresistance or tumorigenicity of CD133+ and CD133- cell fractions were detected. Importantly, however, the STA-ET-8.2 cell line was found to retain a cellular hierarchy in which relatively chemo-resistant, tumorigenic CD133+ cells gave rise to relatively chemo-sensitive, less tumorigenic, CD133- progeny. Conclusions Up to 10% of ESFT express high levels of PROM1. In some tumors and cell

  2. Induction of tumor necrosis factor expression and resistance in a human breast tumor cell line.

    OpenAIRE

    Spriggs, D; Imamura, K; Rodriguez, C; Horiguchi, J; Kufe, D W

    1987-01-01

    Tumor necrosis factor (TNF) is a polypeptide cytokine that is cytotoxic to some but not all tumor cells. The basis for resistance to the cytotoxic effects of this agent remains unclear. We have studied the development of TNF resistance in human ZR-75-1 breast carcinoma cells. ZR-75-1 cells have undetectable levels of TNF RNA and protein. However, TNF transcripts are transiently induced in these cells by exposure to recombinant human TNF. This induction of TNF RNA is associated with production...

  3. Research and development issues for molten carbonate fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Krumpelt, M.

    1996-04-01

    This paper describes issues pertaining to the development of molten carbonate fuel cells. In particular, the corrosion resistance and service life of nickel oxide cathodes is described. The resistivity of lithium oxide/iron oxides and improvement with doping is addressed.

  4. Pluripotent cells display enhanced resistance to mutagenesis

    Directory of Open Access Journals (Sweden)

    Daniel J. Cooper

    2017-03-01

    Full Text Available Pluripotent cells have been reported to exhibit lower frequencies of point mutations and higher levels of DNA repair than differentiated cells. This predicts that pluripotent cells are less susceptible to mutagenic exposures than differentiated cells. To test this prediction, we used a lacI mutation-reporter transgene system to assess the frequency of point mutations in multiple lines of mouse pluripotent embryonic stem cells and induced pluripotent cells, as well as in multiple lines of differentiated fibroblast cells, before and after exposure to a moderate dose of the mutagen, methyl methanesulfonate. We also measured levels of key enzymes in the base excision repair (BER pathway in each cell line before and after exposure to the mutagen. Our results confirm that pluripotent cells normally maintain lower frequencies of point mutations than differentiated cells, and show that differentiated cells exhibit a large increase in mutation frequency following a moderate mutagenic exposure, whereas pluripotent cells subjected to the same exposure show no increase in mutations. This result likely reflects the higher levels of BER proteins detectable in pluripotent cells prior to exposure and supports our thesis that maintenance of enhanced genetic integrity is a fundamental characteristic of pluripotent cells.

  5. 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

    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...... and PARP cleavage in the fulvestrant resistant cells. Barasertib also exerted preferential growth inhibition of tamoxifen resistant T47D cell lines. Finally, high percentage of Aurora kinase B positive tumor cells was significantly associated with reduced disease-free and overall survival in 261 ER...

  6. Breast Cancer Stem Cells in Antiestrogen Resistance

    Science.gov (United States)

    2014-10-01

    Schafer JIM ,O’Regan RM, Jordan VC. Antitumor action of physiological estradiol on tamox- ifen stimulated breast tumors grown in athymic mice. Clin. Cancer...JS, Crowe DL (2009) Tumor initiating cancer stem cells from human breast cancer cell lines. Int J Oncol 34:1449–1453. 10. Woodward WA, Chen MS... Crowe DL (2009) Tumor initiating cancer stem cells from human breast cancer cell lines. Int J Oncol 34: 1449–1453. 49. Woodward WA, Chen MS, Behbod F

  7. Development of large area resistive electrodes for ATLAS NSW Micromegas

    Science.gov (United States)

    Ochi, Atsuhiko

    2018-02-01

    Micromegas with resistive anodes will be used for the NSW upgrades of the ATLAS experiment at LHC. Resistive electrodes are used in MPGD devices to prevent sparks in high-rate operation. Large-area resistive electrodes for Micromegas have been developed using two different technologies: screen printing and carbon sputtering. The maximum resistive foil size is 45 × 220 cm with a printed pattern of 425-μm pitch strips. These technologies are also suitable for mass production. Prototypes of a production model series have been successfully produced. In this paper, we report the development, the production status, and the test results of resistive Micromegas.

  8. Harnessing the p53-PUMA Axis to Overcome DNA Damage Resistance in Renal Cell Carcinoma

    Directory of Open Access Journals (Sweden)

    Xiaoguang Zhou

    2014-12-01

    Full Text Available Resistance to DNA damage–induced apoptosis is a hallmark of cancer and a major cause of treatment failure and lethal disease outcome. A tumor entity that is largely resistant to DNA-damaging therapies including chemo- or radiotherapy is renal cell carcinoma (RCC. This study was designed to explore the underlying molecular mechanisms of DNA damage resistance in RCC to develop strategies to resensitize tumor cells to DNA damage–induced apoptosis. Here, we show that apoptosis-resistant RCC cells have a disconnect between activation of p53 and upregulation of the downstream proapoptotic protein p53 upregulated modulator of apoptosis (PUMA. We demonstrate that this disconnect is not caused by gene-specific repression through CCCTC-binding factor (CTCF but instead by aberrant chromatin compaction. Treatment with an HDAC inhibitor was found to effectively reactivate PUMA expression on the mRNA and protein level and to revert resistance to DNA damage–induced cell death. Ectopic expression of PUMA was found to resensitize a panel of RCC cell lines to four different DNA-damaging agents tested. Remarkably, all RCC cell lines analyzed were wild-type for p53, and a knockdown was likewise able to sensitize RCC cells to acute genotoxic stress. Taken together, our results indicate that DNA damage resistance in RCC is reversible, involves the p53-PUMA axis, and is potentially targetable to improve the oncological outcomes of RCC patients.

  9. Biophysics of Cell Membrane Lipids in Cancer Drug Resistance: Implications for Drug Transport and Drug Delivery with Nanoparticles

    Science.gov (United States)

    Peetla, Chiranjeevi; Vijayaraghavalu, Sivakumar; Labhasetwar, Vinod

    2013-01-01

    In this review, we focus on the biophysics of cell membrane lipids, particularly when cancers develop acquired drug resistance, and how biophysical changes in resistant cell membrane influence drug transport and nanoparticle-mediated drug delivery. Recent advances in membrane lipid research show the varied roles of lipids in regulating membrane P-glycoprotein function, membrane trafficking, apoptotic pathways, drug transport, and endocytic functions, particularly endocytosis, the primary mechanism of cellular uptake of nanoparticle-based drug delivery systems. Since acquired drug resistance alters lipid biosynthesis, understanding the role of lipids in cell membrane biophysics and its effect on drug transport is critical for developing effective therapeutic and drug delivery approaches to overcoming drug resistance. Here we discuss novel strategies for (a) modulating the biophysical properties of membrane lipids of resistant cells to facilitate drug transport and regain endocytic function and (b) developing effective nanoparticles based on their biophysical interactions with membrane lipids to enhance drug delivery and overcome drug resistance. PMID:24055719

  10. Mechanisms of hepatitis B virus resistance development.

    Science.gov (United States)

    Warner, Nadia; Locarnini, Stephen

    2014-01-01

    Hepatitis B virus (HBV) resistance to nucleos(t)ide analogue (NA) therapy is essentially structure specific, with each NA falling within three main structural groups. Resistance to each of these is characterized by specific mutations in the reverse transcriptase domains of the HBV polymerase, and may be associated with compensatory mutations which can increase replication. HBV polymerase is considered to have a traditional 'right-handed' structural conformation, and each of the resistance mutations is predicted to cause a specific structural change of the polymerase, thereby preventing incorporation of NA into replicating DNA. The selection of resistance occurs at different rates for each NA, and is affected by the high mutational rate of HBV and the ability of the drug to suppress viral replication. Some mutations or combinations of mutations may be associated with multidrug resistance, limiting treatment options. In contrast to most other viruses, resistance in HBV is confounded by the overlapping surface gene, the major NA-resistant mutations also altering the surface proteins in most cases, potentially altering virus secretion and neutralization, which may pose a public health threat in the future. © 2014 S. Karger AG, Basel.

  11. Parallel Evolution under Chemotherapy Pressure in 29 Breast Cancer Cell Lines Results in Dissimilar Mechanisms of Resistance

    DEFF Research Database (Denmark)

    Tegze, Balint; Szallasi, Zoltan Imre; Haltrich, Iren

    2012-01-01

    Background: Developing chemotherapy resistant cell lines can help to identify markers of resistance. Instead of using a panel of highly heterogeneous cell lines, we assumed that truly robust and convergent pattern of resistance can be identified in multiple parallel engineered derivatives of only...... a few parental cell lines. Methods: Parallel cell populations were initiated for two breast cancer cell lines (MDA-MB-231 and MCF-7) and these were treated independently for 18 months with doxorubicin or paclitaxel. IC50 values against 4 chemotherapy agents were determined to measure cross......-resistance. Chromosomal instability and karyotypic changes were determined by cytogenetics. TaqMan RT-PCR measurements were performed for resistance-candidate genes. Pgp activity was measured by FACS. Results: All together 16 doxorubicin-and 13 paclitaxel-treated cell lines were developed showing 2-46 fold and 3-28 fold...

  12. Transfer of multidrug resistance among acute myeloid leukemia cells via extracellular vesicles and their microRNA cargo.

    Science.gov (United States)

    Bouvy, Céline; Wannez, Adeline; Laloy, Julie; Chatelain, Christian; Dogné, Jean-Michel

    2017-11-01

    The treatment of acute leukemia is still challenging due in part to the development of resistance and relapse. This chemotherapeutics resistance is established by clonal selection of resistant variants of the cancer cells. Recently, a horizontal transfer of chemo-resistance among cancer cells via extracellular vesicles (EVs) has been suggested. The aim of this research was to investigate the role of EVs in chemo-resistance in acute myeloid leukemia. For this purpose, the sensitive strain of the promyelocytic leukemia HL60 cell line was studied along with its multi-resistant strain, HL60/AR that overexpresses the multidrug resistance protein 1 (MRP-1). A chemo-resistance transfer between the two strains was established by treating HL60 cells with EVs generated by HL60/AR. This study reveals that EVs from HL60/AR can interact with HL60 cells and transfer at least partially, their chemo-resistance. EVs-treated cells begin to express MRP-1 probably due to a direct transfer of MRP-1 and nucleic acids transported by EVs. In this context, two microRNAs were highlighted for their high differential expression in EVs related to sensitive or chemo-resistant cells: miR-19b and miR-20a. Because circulating microRNAs are found in all biological fluids, these results bring out their potential clinical use as chemo-resistance biomarkers in acute myeloid leukemia. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Artesunate induces ROS-mediated apoptosis in doxorubicin-resistant T leukemia cells.

    Directory of Open Access Journals (Sweden)

    Thomas Efferth

    Full Text Available BACKGROUND: A major obstacle for successful cancer treatment often is the development of drug resistance in cancer cells during chemotherapy. Therefore, there is an urgent need for novel drugs with improved efficacy against tumor cells and with less toxicity on normal cells. Artesunate (ART, a powerful anti-malarial herbal compound, has been shown to inhibit growth of various tumor cell lines in vitro and of xenografted Kaposi's sarcoma in mice in vivo. However, the molecular mechanisms by which ART exerts its cytotoxicity have not been elucidated. The ART-class of anti-malarial compounds is attractive due to their activity against multidrug-resistant Plasmodium falciparum and Plasmodium vivax strains. Another salient feature of these compounds is the lack of severe side effects in malaria patients. METHODOLOGY AND PRINCIPAL FINDINGS: In this study, we used T-cell leukemias as a model system to study the molecular mechanisms of ART-induced apoptosis. The most typical anticancer drugs are DNA intercalators such as Doxorubicin. To investigate drug sensitivity and resistance, we chose a Doxorubicin-resistant leukemia cell line and investigated the killing effect of ART on these cells. We show that ART induces apoptosis in leukemic T cells mainly through the mitochondrial pathway via generation of reactive oxygen species (ROS, a mechanism different from Doxorubicin. This is confirmed by the fact that the antioxidant N-Acetyle-Cysteine (NAC could completely block ROS generation and, consequently, inhibited ART-induced apoptosis. Therefore, ART can overcome the Doxorubicin-resistance and induce the Doxorubicin-resistant leukemia cells to undergo apoptosis. We also show that ART can synergize with Doxorubicin to enhance apoptotic cell death in leukemic T cells. This synergistic effect can be largely explained by the fact that ART and Doxorubicin use different killing mechanisms. CONCLUSIONS: Our studies raise the possibility to develop ART in

  14. Resistance among domestic violence offenders: measurement development and initial validation.

    Science.gov (United States)

    Levesque, Deborah A; Velicer, Wayne F; Castle, Patricia H; Greene, R Neil

    2008-02-01

    Batterers' resistance to traditional intervention programs has been well documented. Within a Transtheoretical Model of Change (stage of change) framework, a measure of processes of resistance was developed and administered to 346 adult male domestic violence offenders in treatment. The study yielded a 38-item measure that assesses eight dimensions of resistance: (a) System Blaming, (b) Problems with Partner, (c) Problems with Alliance, (d) Social Justification, (e) Hopelessness, (f) Isolation, (g) Psychological Reactance, and (h) Passive Reactance. The relationship between resistance and stage of change, time in treatment, and partner aggression are reported. Results suggest that we look beyond the most common forms of resistance (e.g., denial and victim-blaming) to identify and address other forms of resistance that may be more internally based and difficult to detect. The processes of resistance measure provides a tool for measuring those types of resistance.

  15. CD133+CD24lo defines a 5-Fluorouracil-resistant colon cancer stem cell-like phenotype

    Science.gov (United States)

    Paschall, Amy V.; Yang, Dafeng; Lu, Chunwan; Redd, Priscilla S.; Choi, Jeong-Hyeon; Heaton, Christopher M.; Lee, Jeffrey R.; Nayak-Kapoor, Asha; Liu, Kebin

    2016-01-01

    The chemotherapeutic agent 5-Fluorouracil (5-FU) is the most commonly used drug for patients with advanced colon cancer. However, development of resistance to 5-FU is inevitable in almost all patients. The mechanism by which colon cancer develops 5-FU resistance is still unclear. One recently proposed theory is that cancer stem-like cells underlie colon cancer 5-FU resistance, but the phenotypes of 5-FU-resistant colon cancer stem cells are still controversial. We report here that 5-FU treatment selectively enriches a subset of CD133+ colon cancer cells in vitro. 5-FU chemotherapy also increases CD133+ tumor cells in human colon cancer patients. However, sorted CD133+ colon cancer cells exhibit no increased resistance to 5-FU, and CD133 levels exhibit no correlation with colon cancer patient survival or cancer recurrence. Genome-wide analysis of gene expression between sorted CD133+ colon cancer cells and 5-FU-selected colon cancer cells identifies 207 differentially expressed genes. CD24 is one of the genes whose expression level is lower in the CD133+ and 5-FU-resistant colon cancer cells as compared to CD133+ and 5-FU-sensitive colon cancer cells. Consequently, CD133+CD24lo cells exhibit decreased sensitivity to 5-FU. Therefore, we determine that CD133+CD24lo phenotype defines 5-FU-resistant human colon cancer stem cell-like cells. PMID:27659530

  16. The Pathway Analysis of Micrornas Regulated Drug-Resistant Responses in HeLa Cells.

    Science.gov (United States)

    Yang, Yubo; Dai, Cuihong; Cai, Zhipeng; Hou, Aiju; Cheng, Dayou; Wu, Guanying; Li, Jing; Cui, Jie; Xu, Dechang

    2016-03-01

    Chemotherapy is the main strategy in the treatment of cancer; however, the development of drug-resistance is the obstacle in long-term treatment of cervical cancer. Cisplatin is one of the most common drugs used in cancer therapy. Recently, accumulating evidence suggests that miRNAs are involved in various bioactivities in oncogenesis. It is not unexpected that miRNAs play a key role in acquiring of drug-resistance in the progression of tumor. In this study, we induced and maintained four levels of cisplatin-resistant HeLa cell lines (HeLa/CR1, HeLa/CR2, HeLa/CR3, and HeLa/CR4). According to the previous studies and existing evidence, we selected five miRNAs (miR-183, miR-182, miR-30a, miR-15b, and miR-16) and their potential target mRNAs as our research targets. The real-time RT-PCR was adopted to detect the relative expression of miRNAs and their mRNAs. The results show that miR-182 and miR-15b were up-regulated in resistant cell lines, while miR-30a was significantly down-regulated. At the same time, their targets are related to drug resistance. Compared to their parent HeLa cell line, the expression of selected miRNAs in resistant cell lines altered. The alteration suggests that HeLa cell drug resistance is associated with distinct miRNAs, which indicates that miRNAs may be one of the therapy targets in the treatment of cervical cancer by sensitizing cell to chemotherapy. We suggested a possible network diagram based on the existing theory and the preliminary results of candidate miRNAs and their targets in HeLa cells during development of drug resistance.

  17. DNA from radiation resistant human tumor cells transfers resistance to NIH/3T3 cells with varying degrees of penetrance

    International Nuclear Information System (INIS)

    Kasid, U.; Dritschilo, A.; Weichselbaum, R.

    1987-01-01

    Experimental evidence suggests that clinical radiation resistance may correlate with in vitro radiation survival parameters. Specifically, they isolated several cell lines from radioresistant head and neck carcinomas with D/sub 0/ values greater than 2 Gy. The authors co-transfected DNA from cell line SQ2OB (D/sub 0/ = 2.4 Gy) with the rhoSVNeO plasmid into NIH/3T3 cells (D/sub 0/ = 1.7 Gy). Antibiotic G418 resistant, transformed clones were isolated and confirmed by Southern blotting to contain human alu, as well as rhoSVNeO sequences. Screening for radiation resistance with 8Gy (Cs-137) revealed that 3 of 4 tested hybrid clones show a radiation survival intermediate between NIH/3T3 and SQ2OB. This suggests that radiation resistance is a dominant, transfectable phenotype of mammalian cells and can be expressed in more sensitive cells. Karyotyping of resistant hybrid clones shows the presence of double minute chromosomes. Secondary transfection results and experiments to clone the genetic factors responsible for radiation resistance are in progress and results will be reported

  18. Increased p38-MAPK is responsible for chemotherapy resistance in human gastric cancer cells

    International Nuclear Information System (INIS)

    Guo, Xianling; Zhang, Baihe; Wu, Mengchao; Wei, Lixin; Ma, Nannan; Wang, Jin; Song, Jianrui; Bu, Xinxin; Cheng, Yue; Sun, Kai; Xiong, Haiyan; Jiang, Guocheng

    2008-01-01

    Chemoresistance is one of the main obstacles to successful cancer therapy and is frequently associated with Multidrug resistance (MDR). Many different mechanisms have been suggested to explain the development of an MDR phenotype in cancer cells. One of the most studied mechanisms is the overexpression of P-glycoprotein (P-gp), which is a product of the MDR1 gene. Tumor cells often acquire the drug-resistance phenotype due to upregulation of the MDR1 gene. Overexpression of MDR1 gene has often been reported in primary gastric adenocarcinoma. This study investigated the role of p38-MAPK signal pathway in vincristine-resistant SGC7901/VCR cells. P-gp and MDR1 RNA were detected by Western blot analysis and RT-PCR amplification. Mitgen-activated protein kinases and function of P-gp were demonstrated by Western blot and FACS Aria cytometer analysis. Ap-1 activity and cell apoptosis were detected by Dual-Luciferase Reporter Assay and annexin V-PI dual staining. The vincristine-resistant SGC7901/VCR cells with increased expression of the multidrug-resistance 1 (MDR1) gene were resistant to P-gp-related drug and P-gp-unrelated drugs. Constitutive increases of phosphorylated p38-MAPK and AP-1 activities were also found in the drug-resistant cells. Inhibition of p38-MAPK by SB202190 reduced activator protein-1 (AP-1) activity and MDR1 expression levels and increased the sensitivity of SGC7901/VCR cells to chemotherapy. Activation of the p38-MAPK pathway might be responsible for the modulation of P-glycoprotein-mediated and P-glycoprotein-unmediated multidrug resistance in the SGC7901/VCR cell line

  19. Parathyroid hormone resistance and B cell lymphopenia in propionic acidemia.

    Science.gov (United States)

    Griffin, T A; Hostoffer, R W; Tserng, K Y; Lebovitz, D J; Hoppel, C L; Mosser, J L; Kaplan, D; Kerr, D S

    1996-07-01

    The mechanisms of hypocalcemia, recurrent infections and hypogammaglobulinemia associated with metabolic decompensation of propionic acidemia due to propionyl-CoA carboxylase deficiency have not been defined. A 7-week-old infant with this disorder presented with severe hypocalcemia and B cell lymphopenia during an episode of metabolic acidosis and hyperammonemia. Hypocalcemia (1.1 mmol l-1) was associated with elevated serum intact parathyroid hormone (122 ng l-1), hyperphosphatemia, hypophosphaturia and hypercalcuria, indicating parathyroid hormone resistance. B cell lymphopenia (20 cells microliters-1) was associated with transient neutropenia, anemia and subsequent hypogamma-globulinemia (IgG < 294 mg dl-1, IgM < 8 mg dl-1, IgA < 8 mg dl-1), while T cells were normal. Parathyroid hormone resistance and B cell lymphopenia resolved following treatment with hemodialysis, diet and carnitine. These complications may be due to interference with parathyroid hormone renal tubular action and B cell maturation/proliferation by accumulated organic acids.

  20. Development and partial metabolic characterization of a dietary cholesterol-resistant colony of rabbits

    International Nuclear Information System (INIS)

    Overturf, M.L.; Smith, S.A.; Hewett-Emmett, D.; Loose-Mitchell, D.S.; Soma, M.R.; Gotto, A.M. Jr.; Morrisett, J.D.

    1989-01-01

    A colony of New Zealand white rabbits has been developed which, when fed a cholesterol-supplemented diet, exhibit unusual resistance to hypercholesterolemia and atherosclerosis, disorders usually observed in normal cholesterol-fed rabbits. When resistant rabbits (RT) were fed a normal low cholesterol diet (ND), their plasma lipoprotein patterns were significantly different from those of normal rabbits (NR) fed the same diet. The low density lipoprotein cholesterol (LDL-c)/high density lipoprotein cholesterol (HDL-c) ratio and LDL-c/very low density lipoprotein cholesterol (VLDL-c) ratio were lower in the resistant rabbits. The hydrated density of HDL of the normal-responsive rabbits was greater than that of the resistant rabbits. LDL from resistant rabbits contained a lower proportion of esterified cholesterol and protein than LDL from normal rabbits. Peripheral mononuclear cells from resistant rabbits bound about 30% more 125 I-labeled rabbit LDL than mononuclear cells from normal rabbits. These results demonstrate that the plasma cholesterol levels of these animals is at least partly under genetic control and that compositional differences exist between the major plasma lipoprotein classes of normal and resistant rabbits even during the ingestion of low-cholesterol diet. The results indicate that at least a part of the difference in the cholesterolemic responses between the two rabbit groups is due to an enhanced LDL uptake by the mononuclear cells, and presumably by other somatic cells of the resistant group

  1. Elevated β-catenin activity contributes to carboplatin resistance in A2780cp ovarian cancer cells

    International Nuclear Information System (INIS)

    Barghout, Samir H.; Zepeda, Nubia; Xu, Zhihua; Steed, Helen; Lee, Cheng-Han; Fu, YangXin

    2015-01-01

    Ovarian cancer is the fifth leading cause of cancer-related mortalities in women. Epithelial ovarian cancer (EOC) represents approximately 90% of all ovarian malignancies. Most EOC patients are diagnosed at advanced stages and current chemotherapy regimens are ineffective against advanced EOC due to the development of chemoresistance. It is important to better understand the molecular mechanisms underlying acquired resistance to effectively manage this disease. In this study, we examined the expression of the Wnt/β-catenin signaling components in the paired cisplatin-sensitive (A2780s) and cisplatin-resistant (A2780cp) EOC cell lines. Our results showed that several negative regulators of Wnt signaling are downregulated, whereas a few Wnt ligands and known Wnt/β-catenin target genes are upregulated in A2780cp cells compared to A2780s cells, suggesting that Wnt/β-catenin signaling is more active in A2780cp cells. Further analysis revealed nuclear localization of β-catenin and higher β-catenin transcriptional activity in A2780cp cells compared to A2780s cells. Finally, we demonstrated that chemical inhibition of β-catenin transcriptional activity by its inhibitor CCT036477 sensitized A2780cp cells to carboplatin, supporting a role for β-catenin in carboplatin resistance in A2780cp cells. In conclusion, our data suggest that increased Wnt/β-catenin signaling activity contributes to carboplatin resistance in A2780cp cells. - Highlights: • Wnt ligands and target genes are upregulated in cisplatin resistant A2780cp cells. • Negative regulators of Wnt signaling are down-regulated in A2780cp cells. • β-catenin transcriptional activity is higher in A2780cp cells compared to A2780s cells. • Inhibition of β-catenin activity increases carboplatin cytotoxicity in A2780cp cells.

  2. Elevated β-catenin activity contributes to carboplatin resistance in A2780cp ovarian cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Barghout, Samir H. [Department of Obstetrics and Gynecology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB (Canada); Zepeda, Nubia; Xu, Zhihua [Department of Oncology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB (Canada); Steed, Helen [Department of Obstetrics and Gynecology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB (Canada); Lee, Cheng-Han [Department of Laboratory Medicine and Pathology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB (Canada); Fu, YangXin, E-mail: yangxin@ualberta.ca [Department of Oncology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB (Canada); Department of Obstetrics and Gynecology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB (Canada)

    2015-12-04

    Ovarian cancer is the fifth leading cause of cancer-related mortalities in women. Epithelial ovarian cancer (EOC) represents approximately 90% of all ovarian malignancies. Most EOC patients are diagnosed at advanced stages and current chemotherapy regimens are ineffective against advanced EOC due to the development of chemoresistance. It is important to better understand the molecular mechanisms underlying acquired resistance to effectively manage this disease. In this study, we examined the expression of the Wnt/β-catenin signaling components in the paired cisplatin-sensitive (A2780s) and cisplatin-resistant (A2780cp) EOC cell lines. Our results showed that several negative regulators of Wnt signaling are downregulated, whereas a few Wnt ligands and known Wnt/β-catenin target genes are upregulated in A2780cp cells compared to A2780s cells, suggesting that Wnt/β-catenin signaling is more active in A2780cp cells. Further analysis revealed nuclear localization of β-catenin and higher β-catenin transcriptional activity in A2780cp cells compared to A2780s cells. Finally, we demonstrated that chemical inhibition of β-catenin transcriptional activity by its inhibitor CCT036477 sensitized A2780cp cells to carboplatin, supporting a role for β-catenin in carboplatin resistance in A2780cp cells. In conclusion, our data suggest that increased Wnt/β-catenin signaling activity contributes to carboplatin resistance in A2780cp cells. - Highlights: • Wnt ligands and target genes are upregulated in cisplatin resistant A2780cp cells. • Negative regulators of Wnt signaling are down-regulated in A2780cp cells. • β-catenin transcriptional activity is higher in A2780cp cells compared to A2780s cells. • Inhibition of β-catenin activity increases carboplatin cytotoxicity in A2780cp cells.

  3. MicroRNA-181a promotes docetaxel resistance in prostate cancer cells.

    Science.gov (United States)

    Armstrong, Cameron M; Liu, Chengfei; Lou, Wei; Lombard, Alan P; Evans, Christopher P; Gao, Allen C

    2017-06-01

    Docetaxel is one of the primary drugs used for treating castration resistant prostate cancer (CRPC). Unfortunately, over time patients invariably develop resistance to docetaxel therapy and their disease will continue to progress. The mechanisms by which resistance develops are still incompletely understood. This study seeks to determine the involvement of miRNAs, specifically miR-181a, in docetaxel resistance in CRPC. Real-time PCR was used to measure miR-181a expression in parental and docetaxel resistant C4-2B and DU145 cells (TaxR and DU145-DTXR). miR-181a expression was modulated in parental or docetaxel resistant cells by transfecting them with miR-181a mimics or antisense, respectively. Following transfection, cell number was determined after 48 h with or without docetaxel. Cross resistance to cabazitaxel induced by miR-181a was also determined. Western blots were used to determine ABCB1 protein expression and rhodamine assays used to assess activity. Phospho-p53 expression was assessed by Western blot and apoptosis was measured by ELISA in C4-2B TaxR and PC3 cells with inhibited or overexpressed miR-181a expression with or without docetaxel. miR-181a is significantly overexpressed in TaxR and DU145-DTXR cells compared to parental cells. Overexpression of miR-181a in parental cells confers docetaxel and cabazitaxel resistance and knockdown of miR-181a in TaxR cells re-sensitizes them to treatment with both docetaxel and cabazitaxel. miR-181a was not observed to impact ABCB1 expression or activity, a protein which was previously demonstrated to be highly involved in docetaxel resistance. Knockdown of miR-181a in TaxR cells induced phospho-p53 expression. Furthermore, miR-181a knockdown alone induced apoptosis in TaxR cells which could be further enhanced by the addition of DTX. Overexpression of mir-181a in prostate cancer cells contributes to their resistance to docetaxel and cabazitaxel and inhibition of mir-181a expression can restore treatment response

  4. Cytokine-Induced Killer Cells Modulates Resistance to Cisplatin in the A549/DDP Cell Line.

    Science.gov (United States)

    Yang, Lili; Du, Chunjuan; Wu, Lei; Yu, Jinpu; An, Xiumei; Yu, Wenwen; Cao, Shui; Li, Hui; Ren, Xiubao

    2017-01-01

    Background Cytokine-induced killer (CIK) cells can potentially enhance the tumor-killing activity of chemotherapy. Objective This study aimed to evaluate the effects of CIK cells on cisplatin (DDP) resistance in the human lung adenocarcinoma cell line A549/DDP. Methods The detect resistance index, drug resistance related-genes and cytokine secretion of A549/DDP co-cultured with CIK cells were assayed in vitro . Results After A549/DDP co-culture with CIK cells, the DDP resistance of A549/DDP significantly decreased in a time-dependent manner. The DDP resistance of A549/DDP co-cultured with CIK cells for 20 h decreased 4.93-fold compared with that of A549/DDP cells cultured alone ( P A549/DDP significantly decreased after co-culture with CIK cells ( P A549/DDP with CIK cells. The expression of GST-π was restored by adding the neutralizing IFN-γ. Conclusion CIK cells can reverse the drug resistance of A549/DDP in a time-dependent manner by reducing GST-π expression to increase the accumulation of DDP. The effect of CIK cells on re-sensitizing lung cancer cells to the chemotherapy drug was partially dependent on the secretion of IFN-γ.

  5. Solar cell materials developing technologies

    CERN Document Server

    Conibeer, Gavin J

    2014-01-01

    This book presents a comparison of solar cell materials, including both new materials based on organics, nanostructures and novel inorganics and developments in more traditional photovoltaic materials. It surveys the materials and materials trends in the field including third generation solar cells (multiple energy level cells, thermal approaches and the modification of the solar spectrum) with an eye firmly on low costs, energy efficiency and the use of abundant non-toxic materials.

  6. STUDY OF THE RELATIONSHIP BETWEEN CIRCADIAN RHYTHMS AND DRUG RESISTANCE OF BREAST TUMOR CELL LINES

    Directory of Open Access Journals (Sweden)

    A. M. Оgloblina

    2015-01-01

    Full Text Available 10 % of genome mRNA expression is rhythmic and these 24-hrs rhythms are under control of the circadian clock. Epidemiologic studies have revealed a clear link between the disruption of circadian rhythms and cancer development in humans. Growing evidence shows that circadian disruption is associated with development of malignant tumors, including breast cancer. Aim of this study was to investigate: the expression of circadian clock genes in human mammary epithelial cell line MCF10A and breast cancer cell lines MCF-7, ZR-75-1, BT-474 and if the multidrug resistance phenotype of cancer cells is associated with changes in circadian clock genes expression. We have found that Per1 expression significantly reduced in cancer cells. No correlation was detected between the expression of circadian clock genes and cancer breast cell lines drug resistance. Interestingly, the expression of Bmal1, Per1 and Cry1 were increased in multi-drug resistant MCF-7_D cells compare with the parent cells MCF-7 cells, however, if these changes in the expression contribute to the drug-resistance or not is not clear. These results argue for further study.

  7. Resistant Starch Regulates Gut Microbiota: Structure, Biochemistry and Cell Signalling.

    Science.gov (United States)

    Yang, Xiaoping; Darko, Kwame Oteng; Huang, Yanjun; He, Caimei; Yang, Huansheng; He, Shanping; Li, Jianzhong; Li, Jian; Hocher, Berthold; Yin, Yulong

    2017-01-01

    Starch is one of the most popular nutritional sources for both human and animals. Due to the variation of its nutritional traits and biochemical specificities, starch has been classified into rapidly digestible, slowly digestible and resistant starch. Resistant starch has its own unique chemical structure, and various forms of resistant starch are commercially available. It has been found being a multiple-functional regulator for treating metabolic dysfunction. Different functions of resistant starch such as modulation of the gut microbiota, gut peptides, circulating growth factors, circulating inflammatory mediators have been characterized by animal studies and clinical trials. In this mini-review, recent remarkable progress in resistant starch on gut microbiota, particularly the effect of structure, biochemistry and cell signaling on nutrition has been summarized, with highlights on its regulatory effect on gut microbiota. © 2017 The Author(s). Published by S. Karger AG, Basel.

  8. Heterogeneity in induced thermal resistance of rat tumor cell clones

    International Nuclear Information System (INIS)

    Tomasovic, S.P.; Rosenblatt, P.L.; Heitzman, D.

    1983-01-01

    Four 13762NF rat mammary adenocarcinoma clones were examined for their survival response to heating under conditions that induced transient thermal resistance (thermotolerance). Clones MTC and MTF7 were isolated from the subcutaneous locally growing tumor, whereas clones MTLn2 and MTLn3 were derived from spontaneous lung metastases. There was heterogeneity among these clones in thermotolerance induced by either fractionated 45 0 C or continuous 42 0 C heating, but the order of sensitivity was not necessarily the same. The clones developed thermal resistance at different rates and to different degrees within the same time intervals. There was heterogeneity between clones isolated from within either the primary site or metastatic lesions. However, clones derived from metastatic foci did not intrinsically acquire more or less thermotolerance to fractionated 45 0 C or continuous 42 0 C heating than did clones from the primary tumor. Further, there was no apparent relationship between any phenotypic properties that conferred more or less thermotolerance in vitro and any phenotypic properties that conferred enhanced metastatic success of these same clones by spontaneous (subcutaneous) or experimental (intravenous) routes in vivo. These tumor clones also differ in their karyotype, metastatic potential, cell surface features, sensitivity to x-irradiation and drugs, and ability to repair sublethal radiation damage. These results provide further credence to the concept that inherent heterogeneity within tumors may be as important in therapeutic success as other known modifiers of outcome such as site and treatment heterogeneity

  9. Extracellular matrix induces doxorubicin-resistance in human osteosarcoma cells by suppression of p53 function.

    Science.gov (United States)

    Harisi, Revekka; Dudas, Jozsef; Nagy-Olah, Julia; Timar, Ferenc; Szendroi, Miklos; Jeney, Andras

    2007-08-01

    Osteosarcoma is the most common primary malignant bone tumor in childhood and adolescence. The several chemotherapy-resistant cases of osteosarcoma are at a higher risk of relapse and adverse outcome. The aim of the current study was to determine the role of extracellular matrix in the resistance developed against chemotherapeutic treatments of human osteosarcoma cells. A cell line, named OSCORT was established from the biopsy of a 17-year-old male patient with primary osteosarcoma. Cell proliferation, apoptosis and quantification of DNA damage after treatments with doxorubicin were investigated in classical and three-dimensional cell culture systems using an extracellular matrix gel. The experimental results were related to the clinical observations of the case. The cells cultured in extracellular matrix gel have shown resistance to doxorubicin similar to that seen in the clinical case, as demonstrated by their proliferation, apoptosis and doxorubicin-induced DNA damage characteristics. Among the extracellular matrix components, the heparan sulfate proteoglycan and-to a lesser extent-fibronectin were involved in the doxorubicin resistance. Laminin and nidogen did not decrease the cytoreductive effect of doxorubicin, while collagen IV even increased it. The extracellular matrix gel decreased the protein levels of p53 and abrogated its cell nuclear translocalization. The most frequent known mutations in the p53 gene were not found in OSCORT cells. The current study provides experimental evidence for an epigenetical, extracellular matrix-induced loss of p53 function, which lead to a potent chemotherapy resistance showing accordance with the clinical experience.

  10. Development of Thymic Epithelial Cells

    DEFF Research Database (Denmark)

    Ulyanchenko, Svetlana; Vaidya, Harsh J.; O'Neill, Kathy E.

    2016-01-01

    The thymus is the primary lymphoid organ in which the T cell repertoire is generated. The complex cellularity of this organ is uniquely designed to facilitate T cell development: defects in thymus development or function can cause immunodeficiencies ranging from the absence of T cell-mediated imm......The thymus is the primary lymphoid organ in which the T cell repertoire is generated. The complex cellularity of this organ is uniquely designed to facilitate T cell development: defects in thymus development or function can cause immunodeficiencies ranging from the absence of T cell......-mediated immunity to broad-spectrum autoimmune disease. Peak thymus size and output occurs early in life, after which the thymus undergoes a natural process of involution. This results in the progressive loss of functional thymus tissue and correspondingly in decreased production of new naïve T cells with age...... - contributing to the diminished capacity of the aged immune system to adequately respond to new antigenic challenge. Age-related thymic involutions, together with the thymic involutions associated with cytotoxic therapies (e.g., radio- or chemotherapy), have raised interest in development of clinically useful...

  11. Chemical communication of antibiotic resistance by a highly resistant subpopulation of bacterial cells.

    Directory of Open Access Journals (Sweden)

    Omar M El-Halfawy

    Full Text Available The overall antibiotic resistance of a bacterial population results from the combination of a wide range of susceptibilities displayed by subsets of bacterial cells. Bacterial heteroresistance to antibiotics has been documented for several opportunistic Gram-negative bacteria, but the mechanism of heteroresistance is unclear. We use Burkholderia cenocepacia as a model opportunistic bacterium to investigate the implications of heterogeneity in the response to the antimicrobial peptide polymyxin B (PmB and also other bactericidal antibiotics. Here, we report that B. cenocepacia is heteroresistant to PmB. Population analysis profiling also identified B. cenocepacia subpopulations arising from a seemingly homogenous culture that are resistant to higher levels of polymyxin B than the rest of the cells in the culture, and can protect the more sensitive cells from killing, as well as sensitive bacteria from other species, such as Pseudomonas aeruginosa and Escherichia coli. Communication of resistance depended on upregulation of putrescine synthesis and YceI, a widely conserved low-molecular weight secreted protein. Deletion of genes for the synthesis of putrescine and YceI abrogate protection, while pharmacologic inhibition of putrescine synthesis reduced resistance to polymyxin B. Polyamines and YceI were also required for heteroresistance of B. cenocepacia to various bactericidal antibiotics. We propose that putrescine and YceI resemble "danger" infochemicals whose increased production by a bacterial subpopulation, becoming more resistant to bactericidal antibiotics, communicates higher level of resistance to more sensitive members of the population of the same or different species.

  12. Mouse dendritic cells pulsed with capsular polysaccharide induce resistance to lethal pneumococcal challenge: roles of T cells and B cells.

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    Noam Cohen

    Full Text Available Mice are exceedingly sensitive to intra-peritoneal (IP challenge with some virulent pneumococci (LD50 = 1 bacterium. To investigate how peripheral contact with bacterial capsular polysaccharide (PS antigen can induce resistance, we pulsed bone marrow dendritic cells (BMDC of C57BL/6 mice with type 4 or type 3 PS, injected the BMDC intra-foot pad (IFP and challenged the mice IP with supra-lethal doses of pneumococci. We examined the responses of T cells and B cells in the draining popliteal lymph node and measured the effects on the bacteria in the peritoneum and blood. We now report that: 1 The PS co-localized with MHC molecules on the BMDC surface; 2 PS-specific T and B cell proliferation and IFNγ secretion was detected in the draining popliteal lymph nodes on day 4; 3 Type-specific resistance to lethal IP challenge was manifested only after day 5; 4 Type-specific IgM and IgG antibodies were detected in the sera of only some of the mice, but B cells were essential for resistance; 5 Control mice vaccinated with a single injection of soluble PS did not develop a response in the draining popliteal lymph node and were not protected; 6 Mice injected with unpulsed BMDC also did not resist challenge: In unprotected mice, pneumococci entered the blood shortly after IP inoculation and multiplied exponentially in both blood and peritoneum killing the mice within 20 hours. Mice vaccinated with PS-pulsed BMDC trapped the bacteria in the peritoneum. The trapped bacteria proliferated exponentially IP, but died suddenly at 18-20 hours. Thus, a single injection of PS antigen associated with intact BMDC is a more effective vaccine than the soluble PS alone. This model system provides a platform for studying novel aspects of PS-targeted vaccination.

  13. Overcoming Multidrug Resistance in Human Cancer Cells by Natural Compounds

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    Tomohiro Nabekura

    2010-05-01

    Full Text Available Multidrug resistance is a phenomenon whereby tumors become resistant to structurally unrelated anticancer drugs. P-glycoprotein belongs to the large ATP-binding cassette (ABC transporter superfamily of membrane transport proteins. P-glycoprotein mediates resistance to various classes of anticancer drugs including vinblastine, daunorubicin, and paclitaxel, by actively extruding the drugs from the cells. The quest for inhibitors of anticancer drug efflux transporters has uncovered natural compounds, including (--epigallocatechin gallate, curcumin, capsaicin, and guggulsterone, as promising candidates. In this review, studies on the effects of natural compounds on P-glycoprotein and anticancer drug efflux transporters are summarized.

  14. ABC transporters as multidrug resistance mechanisms and the development of chemosensitizers for their reversal

    Directory of Open Access Journals (Sweden)

    Choi Cheol-Hee

    2005-10-01

    Full Text Available Abstract One of the major problems related with anticancer chemotherapy is resistance against anticancer drugs. The ATP-binding cassette (ABC transporters are a family of transporter proteins that are responsible for drug resistance and a low bioavailability of drugs by pumping a variety of drugs out cells at the expense of ATP hydrolysis. One strategy for reversal of the resistance of tumor cells expressing ABC transporters is combined use of anticancer drugs with chemosensitizers. In this review, the physiological functions and structures of ABC transporters, and the development of chemosensitizers are described focusing on well-known proteins including P-glycoprotein, multidrug resistance associated protein, and breast cancer resistance protein.

  15. Targeting therapy-resistant cancer stem cells by hyperthermia

    DEFF Research Database (Denmark)

    Oei, A L; Vriend, L E M; Krawczyk, P M

    2017-01-01

    Eradication of all malignant cells is the ultimate but challenging goal of anti-cancer treatment; most traditional clinically-available approaches fail because there are cells in a tumour that either escape therapy or become therapy-resistant. A subpopulation of cancer cells, the cancer stem cells...... (CSCs), is considered to be of particular significance for tumour initiation, progression and metastasis. CSCs are considered in particular to be therapy-resistant and may drive disease recurrence, which positions CSCs in the focus of anti-cancer research, but successful CSC-targeting therapies...... are limited. Here, we argue that hyperthermia - a therapeutic approach based on local heating of a tumour - is potentially beneficial for targeting CSCs in solid tumours. First, hyperthermia has been described to target cells in hypoxic and nutrient-deprived tumour areas where CSCs reside and ionising...

  16. Isolation and characterization of erlotinib-resistant human non-small cell lung cancer A549 cells

    OpenAIRE

    IKEDA, RYUJI; VERMEULEN, LEE C.; LAU, ELIM; JIANG, ZHISHENG; KAVANAUGH, SHANNON M.; YAMADA, KATSUSHI; KOLESAR, JILL M.

    2010-01-01

    Erlotinib, an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor, is an effective therapy for non-small cell lung cancer (NSCLC). However, resistance to erlotinib reduces its efficacy. To investigate the basis of erlotinib resistance, we isolated erlotinib-resistant human NSCLC A549 cells, termed A549/ER cells. The A549/ER cells were found to be resistant to erlotinib, as well as paclitaxel and gemcitabine. We then performed a PCR array to investigate the resistance to erlotini...

  17. Characterisation of multidrug-resistant Ehrlich ascites tumour cells selected in vivo for resistance to etoposide

    DEFF Research Database (Denmark)

    Nielsen, D; Maare, C; Eriksen, J

    2000-01-01

    An Ehrlich ascites tumour cell line (EHR2) was selected for resistance to etoposide (VP16) by in vivo exposure to this agent. The resulting cell line (EHR2/VP16) was 114.3-, 5.7-, and 4.0-fold resistant to VP16, daunorubicin, and vincristine, respectively. The amount of salt-extractable immunorea......An Ehrlich ascites tumour cell line (EHR2) was selected for resistance to etoposide (VP16) by in vivo exposure to this agent. The resulting cell line (EHR2/VP16) was 114.3-, 5.7-, and 4.0-fold resistant to VP16, daunorubicin, and vincristine, respectively. The amount of salt......-extractable immunoreactive topoisomerase IIalpha and beta in EHR2/VP16 was reduced by 30-40% relative to that in EHR2. The multidrug resistance-associated protein (MRP) mRNA was increased 20-fold in EHR2/VP16 as compared with EHR2, whereas the expression of P-glycoprotein was unchanged. In EHR2/VP16, the steady...

  18. Doxorubicin fails to eradicate cancer stem cells derived from anaplastic thyroid carcinoma cells: characterization of resistant cells.

    Science.gov (United States)

    Zheng, Xuqin; Cui, Dai; Xu, Shuhang; Brabant, Georg; Derwahl, Michael

    2010-08-01

    Current chemotherapy with doxorubicin fails to eradicate anaplastic thyroid cancer or even to stop tumor progress which may be due to the failure of these drugs to effectively target putative cancer stem cells. To test this hypothesis, anaplastic thyroid cell lines were characterized by FACS for their content of cancer stem cells, their in vitro sphere-forming capacity and their expression of multidrug resistance transporters of the ABC gene family which may confer drug resistance to the cells. Cells were treated with doxorubicin in short-term and long-term culture up to 6 months to establish a resistant cell line. The survival of cancer and cancer stem cells and the differential expression of transporters were analyzed. Anaplastic thyroid cancer cell lines that consisted of 0.4-0.8% side population cells, expressed ABCG2 and multi-drug-resistant 1 (MDR1) transporters. Treatment with doxorubicin gradually killed the non-side population of cancer cells derived from anaplastic thyroid carcinoma cells. This conferred a growth advantage to cancer stem cells which in turn overgrew the culture. Resistant cell line consisted of a 70% side population fraction enriched with Oct4-positive cancer stem cells. Inhibition of ABCG2 and/or MDR1 revealed that resistance of cancer stem cells to doxorubicin may be mainly due to the expression of these ABC transporters that were highly up-regulated in the resistant subline. The poor outcome of chemotherapy with doxorubicin in anaplastic thyroid carcinoma may be partly explained by up-regulation of ABCG2 and MDR1 transporters that confers resistance to cancer stem cells. Thus an effective treatment of anaplastic thyroid cancer has not only to destroy cancer cells that represent the bulk of tumor cell population but also cancer stem cells that may drive tumor progression.

  19. MiR-1244 sensitizes the resistance of non-small cell lung cancer A549 cell to cisplatin.

    Science.gov (United States)

    Li, Weili; Wang, Wenzhe; Ding, Mingjian; Zheng, Xiaoliang; Ma, Shenglin; Wang, Xiaoju

    2016-01-01

    Cisplatin (DDP)-based chemotherapy is the mainstay of first-line therapy for lung cancer. However, their efficacy is often limited by the existence or development of chemoresistance. The aim of this study was to find and investigate the function of miRNAs in cisplatin (DDP)-resistant non-small cell lung cancer (NSCLC) A549 cell. Quantitative real-time PCR assay was employed to compare the differences of miRNA expression in both cisplatin-resistant A549 (A549/DDP) cell and the parental A549 cell. The dysregulated miRNAs were then corrected by transfecting oligonucleotides into A549/DDP cells. The cellular sensitivity to cisplatin, cell apoptosis and migration were conducted by MTT, flow cytometry and cell wound healing assay, respectively. Both miR-589 and miR-1244 were significantly down-regulated in A549/DDP cell compared to the parental A549, while the expression of miR-182 and miR-224 were increased in A549/DDP cell (P A549/DDP cell. The study indicates a crucial role of miR-1244 in the progress of cisplatin resistance of A549. Further understanding of miR-1244-mediated signaling pathways may promote the clinical use of miR-1244 in lung cancer therapy.

  20. Environmental factors influencing the development and spread of antibiotic resistance.

    Science.gov (United States)

    Bengtsson-Palme, Johan; Kristiansson, Erik; Larsson, D G Joakim

    2018-01-01

    Antibiotic resistance and its wider implications present us with a growing healthcare crisis. Recent research points to the environment as an important component for the transmission of resistant bacteria and in the emergence of resistant pathogens. However, a deeper understanding of the evolutionary and ecological processes that lead to clinical appearance of resistance genes is still lacking, as is knowledge of environmental dispersal barriers. This calls for better models of how resistance genes evolve, are mobilized, transferred and disseminated in the environment. Here, we attempt to define the ecological and evolutionary environmental factors that contribute to resistance development and transmission. Although mobilization of resistance genes likely occurs continuously, the great majority of such genetic events do not lead to the establishment of novel resistance factors in bacterial populations, unless there is a selection pressure for maintaining them or their fitness costs are negligible. To enable preventative measures it is therefore critical to investigate under what conditions and to what extent environmental selection for resistance takes place. In addition, understanding dispersal barriers is not only key to evaluate risks, but also to prevent resistant pathogens, as well as novel resistance genes, from reaching humans. © FEMS 2017.

  1. Environmental factors influencing the development and spread of antibiotic resistance

    Science.gov (United States)

    Kristiansson, Erik; Larsson, D G Joakim

    2017-01-01

    Abstract Antibiotic resistance and its wider implications present us with a growing healthcare crisis. Recent research points to the environment as an important component for the transmission of resistant bacteria and in the emergence of resistant pathogens. However, a deeper understanding of the evolutionary and ecological processes that lead to clinical appearance of resistance genes is still lacking, as is knowledge of environmental dispersal barriers. This calls for better models of how resistance genes evolve, are mobilized, transferred and disseminated in the environment. Here, we attempt to define the ecological and evolutionary environmental factors that contribute to resistance development and transmission. Although mobilization of resistance genes likely occurs continuously, the great majority of such genetic events do not lead to the establishment of novel resistance factors in bacterial populations, unless there is a selection pressure for maintaining them or their fitness costs are negligible. To enable preventative measures it is therefore critical to investigate under what conditions and to what extent environmental selection for resistance takes place. In addition, understanding dispersal barriers is not only key to evaluate risks, but also to prevent resistant pathogens, as well as novel resistance genes, from reaching humans. PMID:29069382

  2. Drug-resistant colon cancer cells produce high carcinoembryonic antigen and might not be cancer-initiating cells

    Directory of Open Access Journals (Sweden)

    Lee HC

    2013-06-01

    Full Text Available Hsin-chung Lee,1,2 Qing-Dong Ling,1,3 Wan-Chun Yu,4 Chunh-Ming Hung,4 Ta-Chun Kao,4 Yi-Wei Huang,4 Akon Higuchi3–51Graduate Institute of Systems Biology and Bioinformatics, National Central University, Jhongli, Taoyuan, 2Department of Surgery, Cathay General Hospital, Da'an District, Taipei, 3Cathay Medical Research Institute, Cathay General Hospital, Hsi-Chi City, Taipei, 4Department of Chemical and Materials Engineering, National Central University, Jhongli, Taoyuan, Taiwan; 5Department of Reproduction, National Research Institute for Child Health and Development, Okura, Tokyo, JapanPurpose: We evaluated the higher levels of carcinoembryonic antigen (CEA secreted by the LoVo human colon carcinoma cells in a medium containing anticancer drugs. Drug-resistant LoVo cells were analyzed by subcutaneously xenotransplanting them into mice. The aim of this study was to evaluate whether the drug-resistant cells isolated in this study were cancer-initiating cells, known also as cancer stem cells (CSCs.Methods: The production of CEA was investigated in LoVo cells that were cultured with 0–10 mM of anticancer drugs, and we evaluated the increase in CEA production by the LoVo cells that were stimulated by anticancer drug treatment. The expression of several CSC markers in LoVo cells treated with anticancer drugs was also evaluated. Following anticancer drug treatment, LoVo cells were injected subcutaneously into the flanks of severe combined immunodeficiency mice in order to evaluate the CSC fraction.Results: Production of CEA by LoVo cells was stimulated by the addition of anticancer drugs. Drug-resistant LoVo cells expressed lower levels of CSC markers, and LoVo cells treated with any of the anticancer drugs tested did not generate tumors within 8 weeks from when the cells were injected subcutaneously into severe combined immunodeficiency mice. These results suggest that the drug-resistant LoVo cells have a smaller population of CSCs than the

  3. Paeonol reverses paclitaxel resistance in human breast cancer cells by regulating the expression of transgelin 2.

    Science.gov (United States)

    Cai, Jiangxia; Chen, Siying; Zhang, Weipeng; Hu, Sasa; Lu, Jun; Xing, Jianfeng; Dong, Yalin

    2014-06-15

    Paclitaxel (PTX) is a first-line antineoplastic drug that is commonly used in clinical chemotherapy for breast cancer treatment. However, the occurrence of drug resistance in chemotherapeutic treatment has greatly restricted its use. There is thus an urgent need to find ways of reversing paclitaxel chemotherapy resistance in breast cancer. Plant-derived agents have great potential in preventing the onset of the carcinogenic process and enhancing the efficacy of mainstream antitumor drugs. Paeonol, a main compound derived from the root bark of Paeonia suffruticosa, has various biological activities, and is reported to have reversal drug resistance effects. This study established a paclitaxel-resistant human breast cancer cell line (MCF-7/PTX) and applied the dual-luciferase reporter gene assay, MTT assay, flow cytometry, transfection assay, Western blotting and the quantitative real-time polymerase chain reaction (qRT-PCR) to investigate the reversing effects of paeonol and its underlying mechanisms. It was found that transgelin 2 may mediate the resistance of MCF-7/PTX cells to paclitaxel by up-regulating the expressions of the adenosine-triphosphate binding cassette transporter proteins, including P-glycoprotein (P-gp), multidrug resistance associated protein 1 (MRP1), and breast cancer resistance protein (BCRP). Furthermore, the ability of paeonol to reverse paclitaxel resistance in breast cancer was confirmed, with a superior 8.2-fold reversal index. In addition, this study found that paeonol down-regulated the transgelin 2-mediated paclitaxel resistance by reducing the expressions of P-gp, MRP1, and BCRP in MCF-7/PTX cells. These results not only provide insight into the potential application of paeonol to the reversal of paclitaxel resistance, thus facilitating the sensitivity of breast cancer chemotherapy, but also highlight a potential role of transgelin 2 in the development of paclitaxel resistance in breast cancer. Copyright © 2014 Elsevier GmbH. All

  4. Daptomycin-resistant Enterococcus faecalis diverts the antibiotic molecule from the division septum and remodels cell membrane phospholipids.

    Science.gov (United States)

    Tran, Truc T; Panesso, Diana; Mishra, Nagendra N; Mileykovskaya, Eugenia; Guan, Ziqianq; Munita, Jose M; Reyes, Jinnethe; Diaz, Lorena; Weinstock, George M; Murray, Barbara E; Shamoo, Yousif; Dowhan, William; Bayer, Arnold S; Arias, Cesar A

    2013-07-23

    Treatment of multidrug-resistant enterococci has become a challenging clinical problem in hospitals around the world due to the lack of reliable therapeutic options. Daptomycin (DAP), a cell membrane-targeting cationic antimicrobial lipopeptide, is the only antibiotic with in vitro bactericidal activity against vancomycin-resistant enterococci (VRE). However, the clinical use of DAP against VRE is threatened by emergence of resistance during therapy, but the mechanisms leading to DAP resistance are not fully understood. The mechanism of action of DAP involves interactions with the cell membrane in a calcium-dependent manner, mainly at the level of the bacterial septum. Previously, we demonstrated that development of DAP resistance in vancomycin-resistant Enterococcus faecalis is associated with mutations in genes encoding proteins with two main functions, (i) control of the cell envelope stress response to antibiotics and antimicrobial peptides (LiaFSR system) and (ii) cell membrane phospholipid metabolism (glycerophosphoryl diester phosphodiesterase and cardiolipin synthase). In this work, we show that these VRE can resist DAP-elicited cell membrane damage by diverting the antibiotic away from its principal target (division septum) to other distinct cell membrane regions. DAP septal diversion by DAP-resistant E. faecalis is mediated by initial redistribution of cell membrane cardiolipin-rich microdomains associated with a single amino acid deletion within the transmembrane protein LiaF (a member of a three-component regulatory system [LiaFSR] involved in cell envelope homeostasis). Full expression of DAP resistance requires additional mutations in enzymes (glycerophosphoryl diester phosphodiesterase and cardiolipin synthase) that alter cell membrane phospholipid content. Our findings describe a novel mechanism of bacterial resistance to cationic antimicrobial peptides. The emergence of antibiotic resistance in bacterial pathogens is a threat to public health

  5. Loss and stabilization of resistance to aminopterin in mouse cell lines

    International Nuclear Information System (INIS)

    Safronov, V.V.; Kapitsa, O.S.; Sapegina, M.B.; Gorodetskii, S.I.

    1986-01-01

    Using step-wise selection, lines of mouse L-cells were obtained (clones B-82, TK-), resistance to aminopterin (AP) of which exceeds resistance of parental cells by 10 3 -5 x 10 4 times. Increased resistance is the result of amplification of the gene for dihydrofolate reductase (DHFR), which was established according to increase in enzyme activity by 15-120 times and by cytogenetic methods. Development and disappearance of resistance to AP was studied and karyological analysis of lines obtained was conducted. Two types of karylogical changes were revealed: the presence of double microchromosomes (DM) and of a marker chromosome having homogeneously staining regions (HSR). The localization of the DHFR and HSR genes was demonstrated using in situ hybridization. At early stages of the development of resistance and for a long time, an extrachromosomal localization of amplified genes in the structure of DM, which determine unstable resistance to toxin, is fundamental. The possibility was demonstrated of the long-term existence of cells in which DM and HSR are present simultaneously. Change in number of copies of the DHFR gene in lines of such cells occurs through change in the number of DM, while size and localization of HSR are constant in different conditions of cell culturing. The presence of HSR determines stable resistance to AP. Data were obtained in support of an intermediate relative stabilization of resistance, which is caused by temporary insertion of copies of the DHFR gene into other sections of chromosomes, in addition to HSR dispersed variously through the genome

  6. The identification of new genes related to cisplatin resistance in ovarian adenocarcinoma cell line A2780

    International Nuclear Information System (INIS)

    Solar, P.; Fedorocko, P.; Sytkowski, A.; Hodorova, I.

    2006-01-01

    Ovarian cancer cells are usually sensitive to platinum-based chemotherapy, such as cisplatin (CDDP), initially but typically become resistant to the drug over time. The phenomenon of clinical drug resistance represents a serious problem for successful disease treatment, and the molecular mechanism(s) are not fully understood. In search of novel mechanisms that may lead to the development of CDDP chemoresistance we have applied subtractive hybridization based on the PCR-select cDNA subtraction. In current study we have used subtractive hybridization to identify differentially-expressed genes in CDDP resistant CP70 and C200 cells versus CDDP-sensitive A2780 human ovarian adenocarcinoma cells. We have analyzed 256 randomly selected clones. Subtraction efficiency was determined by dot blot and DNA sequencing. Confirmation of differentially expressed cDNAs was done by virtual northern blot analysis, and 17 genes that were differentially expressed in both CDDP resistant cell lines versus CDDP sensitive A2780 cells were identified. The expression of 10 of these genes was undetectable or detected with low expression in sensitive A2780 cells in comparison to resistant ones. These genes included ARHGDIB, RANBP2, ASPH, PRTFDC1, SSX2IP, MBNL1, DNAJC15, MMP10, TCTE1L and one unidentified sequence. Additional 7 genes that were more highly expressed in resistant CP70 and C200 vs. A2780 cells included ANXA2, USP8, HSPCA, TRA1, CNAP1, ATP2B1 and COX2. Interestingly, multi-drug resistance associated p-glycoprotein (p170) was not detected by the western blot in CDDP resistant CP70 and C200 cells. Our identified genes are involved in diverse processes, such as stress response, chromatin condensation, protection from protein degradation, invasiveness of cells, alterations of Ca 2+ homeostasis and others which may contribute to CDDP resistance of ovarian adenocarcinoma cells. Further characterization of these genes and gene products should yield important insights into the biology of

  7. Fibrocyte-like cells mediate acquired resistance to anti-angiogenic therapy with bevacizumab

    Science.gov (United States)

    Mitsuhashi, Atsushi; Goto, Hisatsugu; Saijo, Atsuro; Trung, Van The; Aono, Yoshinori; Ogino, Hirokazu; Kuramoto, Takuya; Tabata, Sho; Uehara, Hisanori; Izumi, Keisuke; Yoshida, Mitsuteru; Kobayashi, Hiroaki; Takahashi, Hidefusa; Gotoh, Masashi; Kakiuchi, Soji; Hanibuchi, Masaki; Yano, Seiji; Yokomise, Hiroyasu; Sakiyama, Shoji; Nishioka, Yasuhiko

    2015-01-01

    Bevacizumab exerts anti-angiogenic effects in cancer patients by inhibiting vascular endothelial growth factor (VEGF). However, its use is still limited due to the development of resistance to the treatment. Such resistance can be regulated by various factors, although the underlying mechanisms remain incompletely understood. Here we show that bone marrow-derived fibrocyte-like cells, defined as alpha-1 type I collagen-positive and CXCR4-positive cells, contribute to the acquired resistance to bevacizumab. In mouse models of malignant pleural mesothelioma and lung cancer, fibrocyte-like cells mediate the resistance to bevacizumab as the main producer of fibroblast growth factor 2. In clinical specimens of lung cancer, the number of fibrocyte-like cells is significantly increased in bevacizumab-treated tumours, and correlates with the number of treatment cycles, as well as CD31-positive vessels. Our results identify fibrocyte-like cells as a promising cell biomarker and a potential therapeutic target to overcome resistance to anti-VEGF therapy. PMID:26635184

  8. Regulatory circuitry governing fungal development, drug resistance, and disease.

    Science.gov (United States)

    Shapiro, Rebecca S; Robbins, Nicole; Cowen, Leah E

    2011-06-01

    Pathogenic fungi have become a leading cause of human mortality due to the increasing frequency of fungal infections in immunocompromised populations and the limited armamentarium of clinically useful antifungal drugs. Candida albicans, Cryptococcus neoformans, and Aspergillus fumigatus are the leading causes of opportunistic fungal infections. In these diverse pathogenic fungi, complex signal transduction cascades are critical for sensing environmental changes and mediating appropriate cellular responses. For C. albicans, several environmental cues regulate a morphogenetic switch from yeast to filamentous growth, a reversible transition important for virulence. Many of the signaling cascades regulating morphogenesis are also required for cells to adapt and survive the cellular stresses imposed by antifungal drugs. Many of these signaling networks are conserved in C. neoformans and A. fumigatus, which undergo distinct morphogenetic programs during specific phases of their life cycles. Furthermore, the key mechanisms of fungal drug resistance, including alterations of the drug target, overexpression of drug efflux transporters, and alteration of cellular stress responses, are conserved between these species. This review focuses on the circuitry regulating fungal morphogenesis and drug resistance and the impact of these pathways on virulence. Although the three human-pathogenic fungi highlighted in this review are those most frequently encountered in the clinic, they represent a minute fraction of fungal diversity. Exploration of the conservation and divergence of core signal transduction pathways across C. albicans, C. neoformans, and A. fumigatus provides a foundation for the study of a broader diversity of pathogenic fungi and a platform for the development of new therapeutic strategies for fungal disease.

  9. Cytotoxicity of South-African medicinal plants towards sensitive and multidrug-resistant cancer cells.

    Science.gov (United States)

    Saeed, Mohamed E M; Meyer, Marion; Hussein, Ahmed; Efferth, Thomas

    2016-06-20

    Traditional medicine plays a major role for primary health care worldwide. Cancer belongs to the leading disease burden in industrialized and developing countries. Successful cancer therapy is hampered by the development of resistance towards established anticancer drugs. In the present study, we investigated the cytotoxicity of 29 extracts from 26 medicinal plants of South-Africa against leukemia cell lines, most of which are used traditionally to treat cancer and related symptoms. We have investigated the plant extracts for their cytotoxic activity towards drug-sensitive parental CCRF-CEM leukemia cells and their multidrug-resistant P-glycoprotein-overexpressing subline, CEM/ADR5000 by means of the resazurin assay. A panel of 60 NCI tumor cell lines have been investigated for correlations between selected phytochemicals from medicinal plants and the expression of resistance-conferring genes (ABC-transporters, oncogenes, tumor suppressor genes). Seven extracts inhibited both cell lines (Acokanthera oppositifolia, Hypoestes aristata, Laurus nobilis, Leonotis leonurus, Plectranthus barbatus, Plectranthus ciliates, Salvia apiana). CEM/ADR5000 cells exhibited a low degree of cross-resistance (3.35-fold) towards the L. leonurus extract, while no cross-resistance was observed to other plant extracts, although CEM/ADR5000 cells were highly resistant to clinically established drugs. The log10IC50 values for two out of 14 selected phytochemicals from these plants (acovenoside A and ouabain) of 60 tumor cell lines were correlated to the expression of ABC-transporters (ABCB1, ABCB5, ABCC1, ABCG2), oncogenes (EGFR, RAS) and tumor suppressors (TP53). Sensitivity or resistance of the cell lines were not statistically associated with the expression of these genes, indicating that multidrug-resistant, refractory tumors expressing these genes may still respond to acovenoside A and ouabain. The bioactivity of South African medicinal plants may represent a basis for the development

  10. Radiation resistant passivation of silicon solar cells

    International Nuclear Information System (INIS)

    Swanson, R.M.; Gan, J.Y.; Gruenbaum, P.E.

    1991-01-01

    This patent describes a silicon solar cell having improved stability when exposed to concentrated solar radiation. It comprises a body of silicon material having a major surface for receiving radiation, a plurality of p and n conductivity regions in the body for collecting electrons and holes created by impinging radiation, and a passivation layer on the major surface including a first layer of silicon oxide in contact with the body and a polycrystalline silicon layer on the first layer of silicon oxide

  11. Mechanism of multidrug resistance of human small cell lung cancer cell line H446/VP.

    Science.gov (United States)

    Wang, Yan-Ling; Yan, Yun-Li; Zhou, Na-Jing; Han, Shuo; Zhao, Jun-Xia; Cao, Cui-Li; Lü, Yu-Hong

    2010-11-01

    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. The cell viability was measured by MTT 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. 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. 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.

  12. AIRE deficiency leads to impaired iNKT cell development.

    Science.gov (United States)

    Lindh, Emma; Rosmaraki, Eleftheria; Berg, Louise; Brauner, Hanna; Karlsson, Mikael C I; Peltonen, Leena; Höglund, Petter; Winqvist, Ola

    2010-02-01

    Autoimmune Polyendocrine Syndrome type I (APS I) is caused by mutations in the Autoimmune Regulator gene (AIRE), and results in the immunological destruction of endocrine organs. Herein we have characterized the CD1d-restricted invariant NKT cells (iNKT) and NK cells in APS I patients and Aire(-/-) mice, two cell populations known to play a role in the regulation of autoimmune disease. We show that the frequency of circulating iNKT cells is reduced in APS I patients compared to healthy controls. In accordance with this, iNKT cells are significantly reduced in the thymus and peripheral organs of Aire(-/-) mice. Bone marrow transfer from wild type donors into lethally irradiated Aire(-/-) recipients led to a decreased iNKT cell population in the liver, suggesting an impaired development of iNKT cells in the absence of Aire expression in radio-resistant cells. In contrast to the iNKT cells, both conventional NK cells and thymus-derived NK cells were unaffected by Aire deficiency and differentiated normally in Aire(-/-) mice. Our results show that expression of Aire in radio-resistant cells is important for the development of iNKT cells, whereas NK cell development and function does not depend on Aire. Copyright 2009 Elsevier Ltd. All rights reserved.

  13. 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

  14. Identification of genes associated with cisplatin resistance in human oral squamous cell carcinoma cell line

    International Nuclear Information System (INIS)

    Zhang, Ping; Zhang, Zhiyuan; Zhou, Xiaojian; Qiu, Weiliu; Chen, Fangan; Chen, Wantao

    2006-01-01

    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

  15. 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.

  16. Glucocorticoids promote a glioma stem cell-like phenotype and resistance to chemotherapy in human glioblastoma primary cells

    DEFF Research Database (Denmark)

    Kostopoulou, Ourania N; Mohammad, Abdul-Aleem; Bartek, Jiri

    2018-01-01

    -driven changes in cell morphology, proliferation, migration, gene expression, secretory activity and growth as neurospheres. Dexamethasone treatment of GBM cells appeared to promote the development of a GSC-like phenotype and conferred resistance to physiological stress and chemotherapy. We also analyzed......Glioma stem cells (GSCs) are glioblastoma (GBM) cells that are resistant to therapy and can give rise to recurrent tumors. The identification of patient-related factors that support GSCs is thus necessary to design effective therapies for GBM patients. Glucocorticoids (GCs) are used to treat GBM......-associated edema. However, glucocorticoids participate in the physiological response to psychosocial stress, which has been linked to poor cancer prognosis. This raises concern that glucocorticoids affect the tumor and GSCs. Here, we treated primary human GBM cells with dexamethasone and evaluated GC...

  17. Identification of glycan structure alterations on cell membrane proteins in desoxyepothilone B resistant leukemia cells.

    Science.gov (United States)

    Nakano, Miyako; Saldanha, Rohit; Göbel, Anja; Kavallaris, Maria; Packer, Nicolle H

    2011-11-01

    Resistance to tubulin-binding agents used in cancer is often multifactorial and can include changes in drug accumulation and modified expression of tubulin isotypes. Glycans on cell membrane proteins play important roles in many cellular processes such as recognition and apoptosis, and this study investigated whether changes to the glycan structures on cell membrane proteins occur when cells become resistant to drugs. Specifically, we investigated the alteration of glycan structures on the cell membrane proteins of human T-cell acute lymphoblastic leukemia (CEM) cells that were selected for resistance to desoxyepothilone B (CEM/dEpoB). The glycan profile of the cell membrane glycoproteins was obtained by sequential release of N- and O-glycans from cell membrane fraction dotted onto polyvinylidene difluoride membrane with PNGase F and β-elimination respectively. The released glycan alditols were analyzed by liquid chromatography (graphitized carbon)-electrospray ionization tandem MS. The major N-glycan on CEM cell was the core fucosylated α2-6 monosialo-biantennary structure. Resistant CEM/dEpoB cells had a significant decrease of α2-6 linked sialic acid on N-glycans. The lower α2-6 sialylation was caused by a decrease in activity of β-galactoside α2-6 sialyltransferase (ST6Gal), and decreased expression of the mRNA. It is clear that the membrane glycosylation of leukemia cells changes during acquired resistance to dEpoB drugs and that this change occurs globally on all cell membrane glycoproteins. This is the first identification of a specific glycan modification on the surface of drug resistant cells and the mechanism of this downstream effect on microtubule targeting drugs may offer a route to new interventions to overcome drug resistance.

  18. Cellular glutathione level does not predict ovarian cancer cells' resistance after initial or repeated exposure to cisplatin.

    Science.gov (United States)

    Nikounezhad, Nastaran; Nakhjavani, Maryam; Shirazi, Farshad H

    2017-05-01

    Cisplatin resistance development is a major obstacle in ovarian cancer treatment. One of the most important mechanisms underlying cisplatin resistance is drug detoxification by glutathione. In the present study, the importance of initial or repeated exposure to cisplatin in glutathione dependent resistance was investigated. To this purpose, some cisplatin sensitive and resistant variants of human ovarian cancer cell lines providing an appropriate range of cisplatin sensitivity were selected. Clonogenic survival assay was performed to evaluate cisplatin resistance and intracellular contents of reduced (GSH) and oxidized (GSSG) glutathione were analyzed using an HPLC method. Our results indicated that the intracellular GSH and GSSG concentrations were nearly equal in A2780 and A2780CP cells, while the A2780CP cells showed 14 times more resistance than the A2780 cells after initial exposure to cisplatin. A2780-R1 and A2780-R3 cells which have been repeatedly exposed to cisplatin also showed no significant difference in glutathione content, even though A2780-R3 was about two times more resistant than A2780-R1. Moreover, intracellular GSH/GSSG ratio decreased in the resistant cells, reflecting a shift towards a more oxidizing intracellular environment indicative of oxidative stress. As a conclusion, it seems that although the intracellular glutathione concentration increases after repeated exposure to cisplatin, there is no clear correlation between the intracellular GSH content in ovarian cancer cells and their resistance to cisplatin neither after initial nor after repeated exposure to this drug.

  19. Phalaris minor control, resistance development and strategies for ...

    African Journals Online (AJOL)

    But this practice enhances the development of resistant biotypes of P. minor. Different management approaches like preference of mechanical weeding over chemical weed control, integration of competitive varietal selection, crop rotation and herbicide rotation can be long duration strategies of resistance management in P.

  20. Cancer cell metabolic plasticity allows resistance to NAMPT inhibition but invariably induces dependence on LDHA.

    Science.gov (United States)

    Thongon, Natthakan; Zucal, Chiara; D'Agostino, Vito Giuseppe; Tebaldi, Toma; Ravera, Silvia; Zamporlini, Federica; Piacente, Francesco; Moschoi, Ruxanda; Raffaelli, Nadia; Quattrone, Alessandro; Nencioni, Alessio; Peyron, Jean-Francois; Provenzani, Alessandro

    2018-01-01

    Inhibitors of nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme in NAD + biosynthesis from nicotinamide, exhibit anticancer effects in preclinical models. However, continuous exposure to NAMPT inhibitors, such as FK866, can induce acquired resistance. We developed FK866-resistant CCRF-CEM (T cell acute lymphoblastic leukemia) and MDA MB231 (breast cancer) models, and by exploiting an integrated approach based on genetic, biochemical, and genome wide analyses, we annotated the drug resistance mechanisms. Acquired resistance to FK866 was independent of NAMPT mutations but rather was based on a shift towards a glycolytic metabolism and on lactate dehydrogenase A (LDHA) activity. In addition, resistant CCRF-CEM cells, which exhibit high quinolinate phosphoribosyltransferase (QPRT) activity, also exploited amino acid catabolism as an alternative source for NAD + production, becoming addicted to tryptophan and glutamine and sensitive to treatment with the amino acid transport inhibitor JPH203 and with l-asparaginase, which affects glutamine exploitation. Vice versa, in line with their low QPRT expression, FK866-resistant MDA MB231 did not rely on amino acids for their resistance phenotype. Our study identifies novel mechanisms of resistance to NAMPT inhibition, which may be useful to design more rational strategies for targeting cancer metabolism.

  1. Post-influenzal triazole-resistant aspergillosis following allogeneic stem cell transplantation.

    Science.gov (United States)

    Talento, Alida Fe; Dunne, Katie; Murphy, Niamh; O'Connell, Brian; Chan, Grace; Joyce, Eimear Ann; Hagen, Ferry; Meis, Jacques F; Fahy, Ruauri; Bacon, Larry; Vandenberge, Elisabeth; Rogers, Thomas R

    2018-03-23

    Influenza virus infection is now recognised as a risk factor for invasive pulmonary aspergillosis (IPA). Delays in diagnosis contribute to delayed commencement of antifungal therapy. Additionally, the emergence of resistance to first-line triazole antifungal agents puts emphasis on early detection to prevent adverse outcomes. We present 2 allogeneic stem cell transplant patients who developed IPA due to triazole-resistant Aspergillus fumigatus following influenza infection. We underline the challenges faced in the management of these cases, the importance of early diagnosis and need for surveillance given the emergence of triazole-resistance. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  2. Concentrator-solar-cell development

    Science.gov (United States)

    Grenon, L.

    1982-07-01

    A program is described which is a continuation of earlier programs for the development of high-efficiency, low-cost, silicon concentrator solar cells. The base-line process steps and process sequences identified in these earlier contracts were evaluated and specific processes reviewed. In particular, emphasis on the use of Czochralski-grown silicon wafers rather than float-zone wafers were examined. Additionally, a study of the trade-offs between textured and nontextured cells was initiated, and the limits within which the low-cost plated nickel copper metallization can be used in concentrator solar cell applications was identified.

  3. Proteomic analysis of cell lines to identify the irinotecan resistance ...

    Indian Academy of Sciences (India)

    MADHU

    Department of Medical Oncology, Cancer Center, and The State Key Laboratory of Biotherapy, West China Hospital, West. China Medical School ... Chemotherapeutic drug resistance is a frequent cause of treatment failure in colon cancer patients. Several .... 3.1 Biological characteristics of LoVo/irinotecan cells. The IC50 ...

  4. The effect of vorinostat on the development of resistance to doxorubicin in neuroblastoma.

    Directory of Open Access Journals (Sweden)

    Timothy B Lautz

    Full Text Available Histone deacetylase (HDAC inhibitors, especially vorinostat, are currently under investigation as potential adjuncts in the treatment of neuroblastoma. The effect of vorinostat co-treatment on the development of resistance to other chemotherapeutic agents is unknown. In the present study, we treated two human neuroblastoma cell lines [SK-N-SH and SK-N-Be(2C] with progressively increasing doses of doxorubicin under two conditions: with and without vorinsotat co-therapy. The resultant doxorubicin-resistant (DoxR and vorinostat-treated doxorubicin resistant (DoxR-v cells were equally resistant to doxorubicin despite significantly lower P-glycoprotein expression in the DoxR-v cells. Whole genome analysis was performed using the Ilumina Human HT-12 v4 Expression Beadchip to identify genes with differential expression unique to the DoxR-v cells. We uncovered a number of genes whose differential expression in the DoxR-v cells might contribute to their resistant phenotype, including hypoxia inducible factor-2. Finally, we used Gene Ontology to categorize the biological functions of the differentially expressed genes unique to the DoxR-v cells and found that genes involved in cellular metabolism were especially affected.

  5. Community factors in the development of antibiotic resistance.

    Science.gov (United States)

    Larson, Elaine

    2007-01-01

    The global impact of antibiotic resistance is potentially devastating, threatening to set back progress against certain infectious diseases to the pre-antibiotic era. Although most antibiotic-resistant bacteria originally emerged in hospitals, drug-resistant strains are becoming more common in the community. Factors that facilitate the development of resistance within the community can be categorized as behavioral or environmental/policy. Behavioral factors include inappropriate use of antibiotics and ineffective infection control and hygiene practices. Environmental/policy factors include the continued use of antibiotics in agriculture and the lack of new drug development. A multifaceted approach that includes behavioral strategies in the community and the political will to make difficult regulatory decisions will help to minimize the problem of antimicrobial resistance globally.

  6. Development and preliminary tests of resistive microdot and microstrip detectors

    CERN Document Server

    Peskov, V; Nappi, E; Martinengo, P; Oliveira, R; Pietropaolo, F; Picchi, P

    2012-01-01

    In the last few years our group have focused on developing various designs of spark-protected micropattern gaseous detectors featuring resistive electrodes instead of the traditional metallic ones: resistive microstrip counters, resistive GEM, resistive MICROMEGAS. These detectors combine in one design the best features of RPCs (spark-protection) and micropattern detectors (a high position resolution). In this paper we report the progress so far made in developing other types of resistive micropattern detectors: a microdot-microhole detector and a microgap-microstrip detector. The former detector is an optimal electron amplifier for some special designs of dual phase noble liquid TPCs, for example with a CsI photocathode immersed inside the noble liquid. Preliminary tests of such a detector, for the first time built and investigated, are reported in this paper. The latter detector is mainly orientated towards medical imaging applications such as X-ray scanners. However, we believe that after a proper gas opti...

  7. Use of deferasirox, an iron chelator, to overcome imatinib resistance of chronic myeloid leukemia cells.

    Science.gov (United States)

    Kim, Dae Sik; Na, Yoo Jin; Kang, Myoung Hee; Yoon, Soo-Young; Choi, Chul Won

    2016-03-01

    The treatment of chronic myeloid leukemia (CML) has achieved impressive success since the development of the Bcr-Abl tyrosine kinase inhibitor, imatinib mesylate. Nevertheless, resistance to imatinib has been observed, and a substantial number of patients need alternative treatment strategies. We have evaluated the effects of deferasirox, an orally active iron chelator, and imatinib on K562 and KU812 human CML cell lines. Imatinib-resistant CML cell lines were created by exposing cells to gradually increasing concentrations of imatinib. Co-treatment of cells with deferasirox and imatinib induced a synergistic dose-dependent inhibition of proliferation of both CML cell lines. Cell cycle analysis showed an accumulation of cells in the subG1 phase. Western blot analysis of apoptotic proteins showed that co-treatment with deferasirox and imatinib induced an increased expression of apoptotic proteins. These tendencies were clearly identified in imatinib-resistant CML cell lines. The results also showed that co-treatment with deferasirox and imatinib reduced the expression of BcrAbl, phosphorylated Bcr-Abl, nuclear factor-κB (NF-κB) and β-catenin. We observed synergistic effects of deferasirox and imatinib on both imatinib-resistant and imatinib-sensitive cell lines. These effects were due to induction of apoptosis and cell cycle arrest by down-regulated expression of NF-κB and β-catenin levels. Based on these results, we suggest that a combination treatment of deferasirox and imatinib could be considered as an alternative treatment option for imatinib-resistant CML.

  8. Use of deferasirox, an iron chelator, to overcome imatinib resistance of chronic myeloid leukemia cells

    Science.gov (United States)

    Kim, Dae Sik; Na, Yoo Jin; Kang, Myoung Hee; Yoon, Soo-Young; Choi, Chul Won

    2016-01-01

    Background/Aims: The treatment of chronic myeloid leukemia (CML) has achieved impressive success since the development of the Bcr-Abl tyrosine kinase inhibitor, imatinib mesylate. Nevertheless, resistance to imatinib has been observed, and a substantial number of patients need alternative treatment strategies. Methods: We have evaluated the effects of deferasirox, an orally active iron chelator, and imatinib on K562 and KU812 human CML cell lines. Imatinib-resistant CML cell lines were created by exposing cells to gradually increasing concentrations of imatinib. Results: Co-treatment of cells with deferasirox and imatinib induced a synergistic dose-dependent inhibition of proliferation of both CML cell lines. Cell cycle analysis showed an accumulation of cells in the subG1 phase. Western blot analysis of apoptotic proteins showed that co-treatment with deferasirox and imatinib induced an increased expression of apoptotic proteins. These tendencies were clearly identified in imatinib-resistant CML cell lines. The results also showed that co-treatment with deferasirox and imatinib reduced the expression of BcrAbl, phosphorylated Bcr-Abl, nuclear factor-κB (NF-κB) and β-catenin. Conclusions: We observed synergistic effects of deferasirox and imatinib on both imatinib-resistant and imatinib-sensitive cell lines. These effects were due to induction of apoptosis and cell cycle arrest by down-regulated expression of NF-κB and β-catenin levels. Based on these results, we suggest that a combination treatment of deferasirox and imatinib could be considered as an alternative treatment option for imatinib-resistant CML. PMID:26874514

  9. Supporting R&D of industrial fuel cell developers.

    Energy Technology Data Exchange (ETDEWEB)

    Krumpelt, M.

    1998-09-11

    Argonne National Laboratory is supporting the industrial developers of molten carbonate fuel cells (MCFCs) and tubular solid oxide fuel cells (SOFCs). The results suggest that a lithium concentration level of 65-75 mol% in the LiNa electrolyte will improve cell performance. They have made inroads in understanding the interfacial resistance of bipolar plate materials, and they have reduced the air electrode overpotential in OSFCs by adding dopants.

  10. Sensitivity and resistance towards isoliquiritigenin, doxorubicin and methotrexate in T cell acute lymphoblastic leukaemia cell lines by pharmacogenomics.

    Science.gov (United States)

    Youns, Mahmoud; Fu, Yu-Jie; Zu, Yuan-Gang; Kramer, Anne; Konkimalla, V Badireenath; Radlwimmer, Bernhard; Sültmann, Holger; Efferth, Thomas

    2010-09-01

    The development of drug resistance in cancer cells necessitates the identification of novel agents with improved activity towards cancer cells. In the present investigation, we compared the cytotoxicity of the chalcone flavonoide, isoliquiritigenin (ISL), with that of doxorubicin (DOX) and methotrexate (MTX) in five T cell acute lymphoblastic leukaemia (T-ALL) cell lines (Jurkat, J-Jhan, J16, HUT78 and Karpas 45). To gain insight into the molecular mechanisms which determine the response of T-ALL cells towards ISL, DOX and MTX, we applied array-based matrix comparative genomic hybridisation and microarray-based mRNA expression profiling and compared the genomic and transcriptomic profiles of the cell lines with their 50% inhibition (IC(50)) values for these three drugs. The IC(50) values for ISL did not correlate with those for DOX or MTX, indicating that ISL was still active in DOX- or MTX-unresponsive cell lines. Likewise, the genomic imbalances of chromosomal clones and mRNA expression profile significantly correlating with IC(50) values for ISL were different from thoses correlating with IC(50) values for DOX and MTX. In conclusion, ISL represents a cytotoxic natural product with activity towards T-ALL cell lines. There was no cross-resistance between ISL and DOX or MTX, and the genomic and transcriptomic profiles pointed to different molecular modes of action of ISL as compared to DOX and MTX, indicating that ISL may be a valuable adjunct for cancer therapy to treat otherwise drug-resistant tumours.

  11. Development of a CB Resistant Durable, Flexible Hydration System

    National Research Council Canada - National Science Library

    Hall, Peyton W; Zeller, Frank T; Bulluck, John W; Dingus, Michael L

    2002-01-01

    A durable, flexible hydration system resistant to contamination by contact with VX, GD, and HD chemical agents, as well as damage by the decontaminants sodium hypochlorite and DS-2 is being developed for aviator use...

  12. Aire and T cell development.

    Science.gov (United States)

    Anderson, Mark S; Su, Maureen A

    2011-04-01

    In the thymus, developing T cells that react against self-antigens with high affinity are deleted in the process of negative selection. An essential component of this process is the display of self-antigens, including those whose expression are usually restricted to specific tissues, to developing T cells within the thymus. The Autoimmune Regulator (Aire) gene plays a crucial role in the expression of tissue specific self-antigens within the thymus, and disruption of Aire function results in spontaneous autoimmunity in both humans and mice. Recent advances have been made in our understanding of how Aire influences the expression of thousands of tissue-specific antigens in the thymus. Additional roles of Aire, including roles in chemokine and cytokine expression, have also been revealed. Factors important in the differentiation of Aire-expressing medullary thymic epithelial cells have been defined. Finally, the identity of antigen presenting cells in negative selection, including the role of medullary thymic epithelial cells in displaying tissue specific antigens to T cells, has also been clarified. Copyright © 2010 Elsevier Ltd. All rights reserved.

  13. Molecular characterization of irinotecan (SN-38) resistant human breast cancer cell lines

    DEFF Research Database (Denmark)

    Jandu, Haatisha; Aluzaite, Kristina; Fogh, Louise

    2016-01-01

    or an initial high dose of SN-38 (the active metabolite of irinotecan), respectively. The resistant cell lines were analyzed for cross-resistance to other anti-cancer drugs, global gene expression, growth rates, TOP1 and TOP2A gene copy numbers and protein expression, and inhibition of the breast cancer......Background: Studies in taxane and/or anthracycline refractory metastatic breast cancer (mBC) patients have shown approximately 30 % response rates to irinotecan. Hence, a significant number of patients will experience irinotecan-induced side effects without obtaining any benefit. The aim...... of this study was to lay the groundwork for development of predictive biomarkers for irinotecan treatment in BC.Methods: We established BC cell lines with acquired or de novo resistance to SN-38, by exposing the human BC cell lines MCF 7 and MDA MB 231 to either stepwise increasing concentrations over 6 months...

  14. Lysophosphatidate induces chemo-resistance by releasing breast cancer cells from taxol-induced mitotic arrest.

    Directory of Open Access Journals (Sweden)

    Nasser Samadi

    Full Text Available Taxol is a microtubule stabilizing agent that arrests cells in mitosis leading to cell death. Taxol is widely used to treat breast cancer, but resistance occurs in 25-69% of patients and it is vital to understand how Taxol resistance develops to improve chemotherapy. The effects of chemotherapeutic agents are overcome by survival signals that cancer cells receive. We focused our studies on autotaxin, which is a secreted protein that increases tumor growth, aggressiveness, angiogenesis and metastasis. We discovered that autotaxin strongly antagonizes the Taxol-induced killing of breast cancer and melanoma cells by converting the abundant extra-cellular lipid, lysophosphatidylcholine, into lysophosphatidate. This lipid stimulates specific G-protein coupled receptors that activate survival signals.In this study we determined the basis of these antagonistic actions of lysophosphatidate towards Taxol-induced G2/M arrest and cell death using cultured breast cancer cells. Lysophosphatidate does not antagonize Taxol action in MCF-7 cells by increasing Taxol metabolism or its expulsion through multi-drug resistance transporters. Lysophosphatidate does not lower the percentage of cells accumulating in G2/M by decreasing exit from S-phase or selective stimulation of cell death in G2/M. Instead, LPA had an unexpected and remarkable action in enabling MCF-7 and MDA-MB-468 cells, which had been arrested in G2/M by Taxol, to normalize spindle structure and divide, thus avoiding cell death. This action involves displacement of Taxol from the tubulin polymer fraction, which based on inhibitor studies, depends on activation of LPA receptors and phosphatidylinositol 3-kinase.This work demonstrates a previously unknown consequence of lysophosphatidate action that explains why autotaxin and lysophosphatidate protect against Taxol-induced cell death and promote resistance to the action of this important therapeutic agent.

  15. Effect of iron on pancreatic beta cell function and insulin resistance ...

    African Journals Online (AJOL)

    Background: Increase in total body iron store has been reported in the aetiology and development of diabetes mellitus. The effect of iron supplementation in female with respect to the incidence of diabetes mellitus was investigated on the pancreatic beta cell function and insulin resistance in normal female rats. Methods: ...

  16. Radiation resistance of amorphous silicon alloy solar cells

    International Nuclear Information System (INIS)

    Hanak, J.J.; Chen, E.; Myatt, A.; Woodyard, J.R.

    1987-01-01

    The radiation resistance of a-Si alloy solar cells when bombarded by high energy particles is reviewed. The results of investigations of high energy proton radiation resistance of a-Si alloy thin film photovoltaic cells are reported. Irradiations were carried out with 200 keV and 1.00 MeV protons with fluences ranging betweeen 1E11 and 1E15 cm-2. Defect generation and passivation mechanisms were studied using the AM1 conversion efficiency and isochronal anneals. It is concluded that the primary defect generation mechanism results from the knock-on of Si and Ge in the intrinsic layer of the cells. The defect passivation proceeds by the complex annealing of Si and Ge defects and not by the simple migration of hydrogen

  17. Novel Imidazopyridine Derivatives Possess Anti-Tumor Effect on Human Castration-Resistant Prostate Cancer Cells.

    Directory of Open Access Journals (Sweden)

    Matthew A Ingersoll

    Full Text Available Prostate cancer (PCa is the second leading cause of cancer-related death afflicting United States males. Most treatments to-date for metastatic PCa include androgen-deprivation therapy and second-generation anti-androgens such as abiraterone acetate and enzalutamide. However, a majority of patients eventually develop resistance to these therapies and relapse into the lethal, castration-resistant form of PCa to which no adequate treatment option remains. Hence, there is an immediate need to develop effective therapeutic agents toward this patient population. Imidazopyridines have recently been shown to possess Akt kinase inhibitory activity; thus in this study, we investigated the inhibitory effect of novel imidazopyridine derivatives HIMP, M-MeI, OMP, and EtOP on different human castration-resistant PCa cells. Among these compounds, HIMP and M-MeI were found to possess selective dose- and time-dependent growth inhibition: they reduced castration-resistant PCa cell proliferation and spared benign prostate epithelial cells. Using LNCaP C-81 cells as the model system, these compounds also reduced colony formation as well as cell adhesion and migration, and M-MeI was the most potent in all studies. Further investigation revealed that while HIMP primarily inhibits PCa cell growth via suppression of PI3K/Akt signaling pathway, M-MeI can inhibit both PI3K/Akt and androgen receptor pathways and arrest cell growth in the G2 phase. Thus, our results indicate the novel compound M-MeI to be a promising candidate for castration-resistant PCa therapy, and future studies investigating the mechanism of imidazopyridine inhibition may aid to the development of effective anti-PCa agents.

  18. Novel Imidazopyridine Derivatives Possess Anti-Tumor Effect on Human Castration-Resistant Prostate Cancer Cells.

    Science.gov (United States)

    Ingersoll, Matthew A; Lyons, Anastesia S; Muniyan, Sakthivel; D'Cunha, Napoleon; Robinson, Tashika; Hoelting, Kyle; Dwyer, Jennifer G; Bu, Xiu R; Batra, Surinder K; Lin, Ming-Fong

    2015-01-01

    Prostate cancer (PCa) is the second leading cause of cancer-related death afflicting United States males. Most treatments to-date for metastatic PCa include androgen-deprivation therapy and second-generation anti-androgens such as abiraterone acetate and enzalutamide. However, a majority of patients eventually develop resistance to these therapies and relapse into the lethal, castration-resistant form of PCa to which no adequate treatment option remains. Hence, there is an immediate need to develop effective therapeutic agents toward this patient population. Imidazopyridines have recently been shown to possess Akt kinase inhibitory activity; thus in this study, we investigated the inhibitory effect of novel imidazopyridine derivatives HIMP, M-MeI, OMP, and EtOP on different human castration-resistant PCa cells. Among these compounds, HIMP and M-MeI were found to possess selective dose- and time-dependent growth inhibition: they reduced castration-resistant PCa cell proliferation and spared benign prostate epithelial cells. Using LNCaP C-81 cells as the model system, these compounds also reduced colony formation as well as cell adhesion and migration, and M-MeI was the most potent in all studies. Further investigation revealed that while HIMP primarily inhibits PCa cell growth via suppression of PI3K/Akt signaling pathway, M-MeI can inhibit both PI3K/Akt and androgen receptor pathways and arrest cell growth in the G2 phase. Thus, our results indicate the novel compound M-MeI to be a promising candidate for castration-resistant PCa therapy, and future studies investigating the mechanism of imidazopyridine inhibition may aid to the development of effective anti-PCa agents.

  19. 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.

  20. 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.      

  1. Inhibition of autophagy by andrographolide resensitizes cisplatin-resistant non-small cell lung carcinoma cells via activation of the Akt/mTOR pathway.

    Science.gov (United States)

    Mi, Shanwei; Xiang, Gang; Yuwen, Daolu; Gao, Jian; Guo, Wenjie; Wu, Xuefeng; Wu, Xudong; Sun, Yang; Su, Yongqian; Shen, Yan; Xu, Qiang

    2016-11-01

    Resistance to cisplatin is a major obstacle for the success of non-small cell lung cancer therapy. The mechanisms underlying cisplatin resistance are not fully understood. In this study, we found that the increase of basal auotophagy accompanied the development of cisplatin resistance. Meanwhile the blockade of the Akt/mTOR pathway occurred in the process. Inhibition of this pathway was induced by cisplatin treatment in the resistant non-small cell lung carcinoma cells. Andrographolide, a natural diterpenoid, promoted the activation of the Akt/mTOR signaling by downregulating PTEN and suppressed autophagy, which subsequently resensitized the resistant cells to cisplatin-mediated apoptosis. Cisplatin treatment in combination with andrographolide significantly prevented the growth of the resistant cells in vivo. These results highlight the involvement of autophagy in cisplatin-resistance development and suggest that inhibition of autophagy via tuning the Akt/mTOR signaling could be a promising strategy in the therapy for cisplatin-resistant non-small cell lung cancer. Copyright © 2016 Elsevier Inc. All rights reserved.

  2. Naturally death-resistant precursor cells revealed as the origin of retinoblastoma

    DEFF Research Database (Denmark)

    Trinh, Emmanuelle; Lazzerini Denchi, Eros; Helin, Kristian

    2004-01-01

    The molecular mechanisms and the cell-of-origin leading to retinoblastoma are not well defined. In this issue of Cancer Cell, Bremner and colleagues describe the first inheritable model of retinoblastoma, revealing that loss of the pocket proteins pRb and p107 deregulates cell cycle exit in retinal...... precursors. The authors show that a subset of these precursors contain an inherent resistance to apoptosis, and that while most terminally differentiate, some are likely to acquire additional mutations, leading to tumor formation. Thus, this work defines the cell-of-origin of retinoblastoma and suggests...... that mutations giving increased proliferative capacity are required for retinoblastoma development....

  3. Transgenic approaches for development of disease resistance in banana

    International Nuclear Information System (INIS)

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

    2014-01-01

    Banana (Musa spp.) is an important food and cash crop worldwide. Diseases and pests pose the most serious constraint to banana cultivation. Among the diseases, Fusarium wilt and Banana Bunchy Top Virus (BBTV) are the most important economically. We have explored different transgenic approaches for development of efficient resistance in banana against these two diseases. For countering Fusarium wilt, we have over expressed Petunia floral defensins using a strong constitutive promoter in transgenic banana plants. We have also tested a host induced gene silencing strategy targeting two vital fungal genes to obtain Fusarium resistant banana plants. For development of BBTV resistant banana plants also, we have used a host-induced gene silencing approach utilizing the full and partial coding sequence of the viral replication initiation protein. Successful bioassays performed in controlled greenhouse conditions have shown the efficacy of using these strategies to develop disease resistant banana plants. (author)

  4. Non-p-glycoprotein-mediated multidrug resistance in detransformed rat cells selected for resistance to methylglyoxal bis(guanylhydrazone).

    Science.gov (United States)

    Weber, J M; Sircar, S; Horvath, J; Dion, P

    1989-11-01

    Three independent variants (G2, G4, G5), resistant to methylglyoxal bis(guanylhydrazone), an anticancer drug, have been isolated by single step selection from an adenovirus-transformed rat brain cell line (1). These variants display selective cross-resistance to several natural product drugs of dissimilar structure and action. Multidrug resistance has recently been shown to be caused by overexpression of the membrane-associated p-glycoprotein, most often caused by amplification of the mdr gene. Several types of experiments were conducted to determine whether the observed drug resistance in our cell lines could be due to changes at the mdr locus. The following results were obtained: (a) the mdr locus was not amplified; (b) transcription of the mdr gene and p-glycoprotein synthesis were not increased; (c) multidrug resistance cell lines, which carry an amplified mdr locus, were not cross-resistant to methylglyoxal bis(guanylhydrazone); (d) verapamil did not reverse the resistance of G cells or mdr cells to methylglyoxal bis(guanylhydrazone), nor that of G cells to vincristine; and (e) methylglyoxal bis(guanylhydrazone) resistance was recessive and depended on a block to drug uptake, as opposed to mdr cells which are dominant and express increased drug efflux. The results obtained suggest that the drug resistance in the G2, G4, and G5 cells was atypical and may be due to a mechanism distinct from that mediated by the mdr locus.

  5. Random Transposon Mutagenesis for Cell-Envelope Resistant to Phage Infection.

    Science.gov (United States)

    Reyes-Cortés, Ruth; Arguijo-Hernández, Emma S; Carballo-Ontiveros, Marco A; Martínez-Peñafiel, Eva; Kameyama, Luis

    2016-01-01

    In order to identify host components involved in the infective process of bacteriophages, we developed a wide-range strategy to obtain cell envelope mutants, using Escherichia coli W3110 and its specific phage mEp213. The strategy consisted in four steps: (1) random mutagenesis using transposon miniTn10Km(r); (2) selection of phage-resistant mutants by replica-plating; (3) electroporation of the phage-resistant mutants with mEp213 genome, followed by selection of those allowing phage development; and (4) sequencing of the transposon-disrupted genes. This strategy allowed us to distinguish the host factors related to phage development or multiplication within the cell, from those involved in phage infection at the level of the cell envelope.

  6. Effects of DTX3L on the cell proliferation, adhesion, and drug resistance of multiple myeloma cells.

    Science.gov (United States)

    Shen, Yaodong; Sun, Yuxiang; Zhang, Linlin; Liu, Hong

    2017-06-01

    Cell adhesion-mediated drug resistance is an important factor that influences the effects of chemotherapy in multiple myeloma. DTX3L, a ubiquitin ligase, plays a key role in cell-cycle-related process. Here, we found that the expression of DTX3L gradually increased during the proliferation of myeloma cells, which resulted in arrest of the cell cycle in the G1 phase and promoted the adherence of myeloma cells to fibronectin or bone marrow stromal cells. In addition, silencing of DTX3L improved sensitivity to chemotherapy drugs in multiple myeloma cell lines adherent to bone marrow stromal cells and increased the expression of caspase-3 and poly-adenosine diphosphate-ribose polymerase, two markers of apoptosis. Finally, we also found that DTX3L expression was regulated by focal adhesion kinase. Taken together, the results of this study show that DTX3L plays an important role in the proliferation and cell adhesion-mediated drug resistance of multiple myeloma cells and as such may play a key role in the development of multiple myeloma.

  7. Genome wide single cell analysis of chemotherapy resistant metastatic cells in a case of gastroesophageal adenocarcinoma

    International Nuclear Information System (INIS)

    Hjortland, Geir Olav; Fodstad, Oystein; Smeland, Sigbjorn; Hovig, Eivind; Meza-Zepeda, Leonardo A; Beiske, Klaus; Ree, Anne H; Tveito, Siri; Hoifodt, Hanne; Bohler, Per J; Hole, Knut H; Myklebost, Ola

    2011-01-01

    Metastatic progression due to development or enrichment of therapy-resistant tumor cells is eventually lethal. Molecular characterization of such chemotherapy resistant tumor cell clones may identify markers responsible for malignant progression and potential targets for new treatment. Here, in a case of stage IV adenocarcinoma of the gastroesophageal junction, we report the successful genome wide analysis using array comparative genomic hybridization (CGH) of DNA from only fourteen tumor cells using a bead-based single cell selection method from a bone metastasis progressing during chemotherapy. In a case of metastatic adenocarcinoma of the gastroesophageal junction, the progression of bone metastasis was observed during a chemotherapy regimen of epirubicin, oxaliplatin and capecitabine, whereas lung-, liver and lymph node metastases as well as the primary tumor were regressing. A bone marrow aspirate sampled at the site of progressing metastasis in the right iliac bone was performed, and single cell molecular analysis using array-CGH of Epithelial Specific Antigen (ESA)-positive metastatic cells, and revealed two distinct regions of amplification, 12p12.1 and 17q12-q21.2 amplicons, containing the KRAS (12p) and ERBB2 (HER2/NEU) (17q) oncogenes. Further intrapatient tumor heterogeneity of these highlighted gene copy number changes was analyzed by fluorescence in situ hybridization (FISH) in all available primary and metastatic tumor biopsies, and ErbB2 protein expression was investigated by immunohistochemistry. ERBB2 was heterogeneously amplified by FISH analysis in the primary tumor, as well as liver and bone metastasis, but homogenously amplified in biopsy specimens from a progressing bone metastasis after three initial cycles of chemotherapy, indicating a possible enrichment of erbB2 positive tumor cells in the progressing bone marrow metastasis during chemotherapy. A similar amplification profile was detected for wild-type KRAS, although more heterogeneously

  8. Rhodacyanine derivative selectively targets cancer cells and overcomes tamoxifen resistance.

    Directory of Open Access Journals (Sweden)

    John Koren

    Full Text Available MKT-077, a rhodacyanine dye, was shown to produce cancer specific cell death. However, complications prevented the use of this compound beyond clinical trials. Here we describe YM-1, a derivative of MKT-077. We found that YM-1 was more cytotoxic and localized differently than MKT-077. YM-1 demonstrated this cytotoxicity across multiple cancer cell lines. This toxicity was limited to cancer cell lines; immortalized cell models were unaffected. Brief applications of YM-1 were found to be non-toxic. Brief treatment with YM-1 restored tamoxifen sensitivity to a refractory tamoxifen-resistant MCF7 cell model. This effect is potentially due to altered estrogen receptor alpha phosphorylation, an outcome precipitated by selective reductions in Akt levels (Akt/PKB. Thus, modifications to the rhodocyanine scaffold could potentially be made to improve efficacy and pharmacokinetic properties. Moreover, the impact on tamoxifen sensitivity could be a new utility for this compound family.

  9. Inhibition of multidrug resistance-associated protein (MRP) activity by rifampicin in human multidrug-resistant lung tumor cells

    NARCIS (Netherlands)

    Courtois, A; Payen, L; Vernhet, L; de Vries, EGE; Guillouzo, A; Fardel, O

    1999-01-01

    The multidrug resistance-associated protein (MRP) is a drug efflux membrane pump conferring multidrug resistance on tumor cells. In order to look for compounds that can lead to reversal of such a resistance, the antituberculosis compound rifampicin, belonging to the chemical class of rifamycins, was

  10. Thioridazine affects transcription of genes involved in cell wall biosynthesis in methicillin-resistant Staphylococcus aureus

    DEFF Research Database (Denmark)

    Bonde, Mette; Højland, Dorte Heidi; Kolmos, Hans Jørn

    2011-01-01

    have previously shown that the expression of some resistance genes is abolished after treatment with thioridazine and oxacillin. To further understand the mechanism underlying the reversal of resistance, we tested the expression of genes involved in antibiotic resistance and cell wall biosynthesis...... reversal of resistance by thioridazine relies on decreased expression of specific genes involved in cell wall biosynthesis....

  11. BMI-1 Promotes Self-Renewal of Radio- and Temozolomide (TMZ)-Resistant Breast Cancer Cells.

    Science.gov (United States)

    Yan, Yanfang; Wang, Ying; Zhao, Pengxin; Ma, Weiyuan; Hu, Zhigang; Zhang, Kaili

    2017-12-01

    Breast cancer is a hormone-dependent malignancy and is the most prevalent cause of cancer-related mortality among females. Radiation therapy and chemotherapy are common treatments of breast cancer. However, tumor relapse and metastasis following therapy are major clinical challenges. The importance of B-lymphoma Moloney murine leukemia virus insertion region-1 (BMI-1) was implicated in cell proliferation, stem cell maintenance, and tumor initiation. We established radio- and temozolomide (TMZ)-resistant (IRC-R) MCF-7 and MDA-MB-231 cell lines to investigate the mechanism involved in therapeutic resistance. Cell proliferation and sphere number were dramatically elevated, and BMI-1 was remarkably upregulated, in IRC-R cells compared to parental cells. Silencing BMI-1 by RNA interference only affected the cell proliferation of IRC-R but not parental cells, suggesting the critical role of BMI-1 in radio- and TMZ resistance. We used a xenograft mice model to elucidate that BMI-1 was necessary in tumor development by assessing tumor volume and Ki67 expression. We found that Hedgehog (Hhg) signaling exerted synergized functions together with BMI-1, implicating the importance of BMI-1 in Hhg signaling. Downregulation of BMI-1 could be an effective strategy to suppress tumor growth, which supports the potential clinical use of targeting BMI-1 in breast cancer treatment.

  12. Survivin plays as a resistant factor against tamoxifen-induced apoptosis in human breast cancer cells.

    Science.gov (United States)

    Moriai, Ryosuke; Tsuji, Naoki; Moriai, Mikako; Kobayashi, Daisuke; Watanabe, Naoki

    2009-09-01

    Tamoxifen has been the mainstay of endocrine therapy for estrogen receptor-positive breast cancer. However, approximately 40% of breast cancer patients do not respond to tamoxifen treatment. Further, most tumors eventually acquire tamoxifen resistance. Therefore, it is necessary to develop effective modalities to enhance the efficacy of tamoxifen in breast cancer treatment. In this study, we investigated the mechanism by which breast cancer cells develop resistance against tamoxifen from the viewpoint of tamoxifen-induced apoptosis. Overexpression of the anti-apoptotic molecule survivin rendered the human breast cancer cells MCF-7 resistant to tamoxifen-induced apoptosis. To examine whether the down-regulation of survivin can enhance tamoxifen-induced apoptosis, we introduced siRNA targeting the survivin gene (survivin-siRNA) into MCF-7 cells. Survivin-siRNA transfection not only induced apoptosis without tamoxifen treatment but also augmented the tamoxifen-induced apoptosis. We have previously demonstrated that 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (HRIs), which are widely used to reduce the serum cholesterol levels in hypercholesterolemia patients, decreases survivin expression in colon cancer cells. To develop a pharmacological approach for improving the efficacy of tamoxifen treatment, we determined whether HRIs can enhance tamoxifen-induced apoptosis. Lovastatin, an HRI, down-regulated the expression of survivin protein in MCF-7 cells in a dose-dependent manner. In addition, the proportion of apoptotic cells induced by the tamoxifen and lovastatin combination was greater than the theoretical additive effect. These results suggest that survivin may function as a factor inducing resistance against tamoxifen-induced apoptosis, and the combined use of tamoxifen and HRI may be a novel approach to overcome tamoxifen resistance in breast cancer.

  13. Development of Magnetorheological Resistive Exercise Device for Rowing Machine

    Directory of Open Access Journals (Sweden)

    Vytautas Grigas

    2016-01-01

    Full Text Available Training equipment used by professional sportsmen has a great impact on their sport performance. Most universal exercisers may help only to improve the general physical condition due to the specific kinematics and peculiar resistance generated by their loading units. Training of effective techniques and learning of psychomotor skills are possible only when exercisers conform to the movements and resistance typical for particular sports kinematically and dynamically. Methodology of developing a magnetorheological resistive exercise device for generating the desired law of passive resistance force and its application in a lever-type rowing machine are described in the paper. The structural parameters of a controllable hydraulic cylinder type device were found by means of the computational fluid dynamics simulation performed by ANSYS CFX software. Parameters describing the magnetorheological fluid as non-Newtonian were determined by combining numerical and experimental research of the resistance force generated by the original magnetorheological damper. A structural scheme of the device control system was developed and the variation of the strength of magnetic field that affects the magnetorheological fluid circulating in the device was determined, ensuring a variation of the resistance force on the oar handle adequate for the resistance that occurs during a real boat rowing stroke.

  14. Development of alkaline fuel cells.

    Energy Technology Data Exchange (ETDEWEB)

    Hibbs, Michael R.; Jenkins, Janelle E.; Alam, Todd Michael; Janarthanan, Rajeswari; Horan, James L.; Caire, Benjamin R.; Ziegler, Zachary C.; Herring, Andrew M.; Yang, Yuan; Zuo, Xiaobing; Robson, Michael H.; Artyushkova, Kateryna; Patterson, Wendy; Atanassov, Plamen Borissov

    2013-09-01

    This project focuses on the development and demonstration of anion exchange membrane (AEM) fuel cells for portable power applications. Novel polymeric anion exchange membranes and ionomers with high chemical stabilities were prepared characterized by researchers at Sandia National Laboratories. Durable, non-precious metal catalysts were prepared by Dr. Plamen Atanassovs research group at the University of New Mexico by utilizing an aerosol-based process to prepare templated nano-structures. Dr. Andy Herrings group at the Colorado School of Mines combined all of these materials to fabricate and test membrane electrode assemblies for single cell testing in a methanol-fueled alkaline system. The highest power density achieved in this study was 54 mW/cm2 which was 90% of the project target and the highest reported power density for a direct methanol alkaline fuel cell.

  15. Using and development of multi adversity resistance system in cotton

    Directory of Open Access Journals (Sweden)

    Metin Durmuş ÇETİN

    2014-12-01

    Full Text Available The basic approach in plant breeding, make it possible to show the full genetic potential of plant. This methods also protect the health of plant growth over the period, by increasing resistance to diseases and pests is expected to provide. For this purpose, by Bird in 1963, with the name of multi adversity resistance has been initiated in cotton breeding and for many years as a result of the work carried out important varieties and germplasm have been developed. Nowadays, those using for varieties resistant to stress factors such as heat and drought are evaluated. And successful results are obtained.

  16. Antimicrobial resistance-a threat to the world's sustainable development.

    Science.gov (United States)

    Jasovský, Dušan; Littmann, Jasper; Zorzet, Anna; Cars, Otto

    2016-08-01

    This commentary examines how specific sustainable development goals (SDGs) are affected by antimicrobial resistance and suggests how the issue can be better integrated into international policy processes. Moving beyond the importance of effective antibiotics for the treatment of acute infections and health care generally, we discuss how antimicrobial resistance also impacts on environmental, social, and economic targets in the SDG framework. The paper stresses the need for greater international collaboration and accountability distribution, and suggests steps towards a broader engagement of countries and United Nations agencies to foster global intersectoral action on antimicrobial resistance.

  17. A New Product Development Partnership Model for Antibiotic Resistance.

    Science.gov (United States)

    Billington, John K

    2016-05-01

    Antibiotics have prevented countless deaths from common infections and have made possible many modern medical procedures. Over the past few decades, antibiotic-resistant bacteria have become a global threat, spreading between healthcare facilities and throughout communities worldwide at an alarming pace. Antibiotic overuse and misuse in humans, animals, and the environment accelerate resistance by selecting for bacteria with antibiotic-resistant traits, which then become predominant and infect others. Meanwhile, few antibiotics remain active against the most resistant bacteria. There is an urgent need for new antibiotics and other antibacterial products to replace second-line and last resort therapies when they no longer work. This Article proposes a new U.S.-based, non-governmental, not-for-profit product development partnership (PDP) model specifically designed for antibacterial development. This new model should both supplement and complement existing government-led efforts and should be built with mechanisms in place to balance the values of innovation, access, and conservation.

  18. Cell Wall Remodeling Enzymes Modulate Fungal Cell Wall Elasticity and Osmotic Stress Resistance.

    Science.gov (United States)

    Ene, Iuliana V; Walker, Louise A; Schiavone, Marion; Lee, Keunsook K; Martin-Yken, Hélène; Dague, Etienne; Gow, Neil A R; Munro, Carol A; Brown, Alistair J P

    2015-07-28

    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, Cek1) signaling pathways. These mitogen-activated protein kinase (MAPK) pathways modulate cell wall gene expression, leading to the construction of a new, modified cell wall. We show that the cell wall is not rigid but elastic, displaying rapid structural realignments that impact survival following osmotic shock. Lactate-grown Candida albicans cells are more resistant to hyperosmotic shock than glucose-grown cells. We show that this elevated resistance is not dependent on Hog1 or Mkc1 signaling and that most cell death occurs within 10 min of osmotic shock. Sudden decreases in cell volume drive rapid increases in cell wall thickness. The elevated stress resistance of lactate-grown cells correlates with reduced cell wall elasticity, reflected in slower changes in cell volume following hyperosmotic shock. The cell wall elasticity of lactate-grown cells is increased by a triple mutation that inactivates the Crh family of cell wall cross-linking enzymes, leading to increased sensitivity to hyperosmotic shock. Overexpressing Crh family members in glucose-grown cells reduces cell wall elasticity, providing partial protection against hyperosmotic shock. These changes correlate with structural realignment of the cell wall and with the ability of cells to withstand osmotic shock. The C. albicans cell wall is the first line of defense against external insults, the site of immune recognition by the host, and an attractive target for antifungal therapy. Its tensile strength is conferred by

  19. Myeloid Dendritic Cells (DCs) of Mice Susceptible to Paracoccidioidomycosis Suppress T Cell Responses whereas Myeloid and Plasmacytoid DCs from Resistant Mice Induce Effector and Regulatory T Cells

    Science.gov (United States)

    Pina, Adriana; Frank de Araujo, Eliseu; Felonato, Maíra; Loures, Flávio V.; Feriotti, Claudia; Bernardino, Simone; Barbuto, José Alexandre M.

    2013-01-01

    The protective adaptive immune response in paracoccidioidomycosis, a mycosis endemic among humans, is mediated by T cell immunity, whereas impaired T cell responses are associated with severe, progressive disease. The early host response to Paracoccidioides brasiliensis infection is not known since the disease is diagnosed at later phases of infection. Our laboratory established a murine model of infection where susceptible mice reproduce the severe disease, while resistant mice develop a mild infection. This work aimed to characterize the influence of dendritic cells in the innate and adaptive immunity of susceptible and resistant mice. We verified that P. brasiliensis infection induced in bone marrow-derived dendritic cells (DCs) of susceptible mice a prevalent proinflammatory myeloid phenotype that secreted high levels of interleukin-12 (IL-12), tumor necrosis factor alpha, and IL-β, whereas in resistant mice, a mixed population of myeloid and plasmacytoid DCs secreting proinflammatory cytokines and expressing elevated levels of secreted and membrane-bound transforming growth factor β was observed. In proliferation assays, the proinflammatory DCs from B10.A mice induced anergy of naïve T cells, whereas the mixed DC subsets from resistant mice induced the concomitant proliferation of effector and regulatory T cells (Tregs). Equivalent results were observed during pulmonary infection. The susceptible mice displayed preferential expansion of proinflammatory myeloid DCs, resulting in impaired proliferation of effector T cells. Conversely, the resistant mice developed myeloid and plasmacytoid DCs that efficiently expanded gamma interferon-, IL-4-, and IL-17-positive effector T cells associated with increased development of Tregs. Our work highlights the deleterious effect of excessive innate proinflammatory reactions and provides new evidence for the importance of immunomodulation during pulmonary paracoccidioidomycosis. PMID:23340311

  20. Development of portable fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Nakatou, K.; Sumi, S.; Nishizawa, N. [Sanyo Electric Co., Ltd., Osaka (Japan)

    1996-12-31

    Sanyo Electric has been concentrating on developing a marketable portable fuel cell using phosphoric acid fuel cells (PAFC). Due to the fact that this power source uses PAFC that operate at low temperature around 100{degrees} C, they are easier to handle compared to conventional fuel cells that operate at around 200{degrees} C , they can also be expected to provide extended reliable operation because corrosion of the electrode material and deterioration of the electrode catalyst are almost completely nonexistent. This power source is meant to be used independently and stored at room temperature. When it is started up, it generates electricity itself using its internal load to raise the temperature. As a result, the phosphoric acid (the electolyte) absorbs the reaction water when the temperature starts to be raised (around room temperature). At the same time the concentration and volume of the phosphoric acid changes, which may adversely affect the life time of the cell. We have studied means for starting, operating PAFC stack using methods that can simply evaluate changes in the concentration of the electrolyte in the stack with the aim of improving and extending cell life and report on them in this paper.

  1. Proteomics of cancer cell lines resistant to microtubule-stabilizing agents

    DEFF Research Database (Denmark)

    Albrethsen, Jakob; Angeletti, Ruth H; Horwitz, Susan Band

    2014-01-01

    was compared with two drug-resistant daughter cell lines, an EpoB-resistant cell line (EpoB8) and an ixabepilone-resistant cell line (Ixab80). All 2D DIGE results were validated by Western blot analyses. A variety of cytoskeletal and cytoskeleton-associated proteins were differentially expressed in drug......Despite the clinical success of microtubule-interacting agents (MIA), a significant challenge for oncologists is the inability to predict the response of individual patients with cancer to these drugs. In the present study, six cell lines were compared by 2D DIGE proteomics to investigate cellular...... resistance to the class of MIAs known as microtubule-stabilizing agents (MSA). The human lung cancer cell line A549 was compared with two drug-resistant daughter cell lines, a taxol-resistant cell line (AT12) and an epothilone B (EpoB)-resistant cell line (EpoB40). The ovarian cancer cell line Hey...

  2. Determination of internal resistance and electrocatalyst utilization of fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, J.A. [Thermodynamics and Kinetics Lab., Dept. of Mechanical Engineering, Toronto Univ., ON (Canada); Ward, C.A. [Thermodynamics and Kinetics Lab., Dept. of Mechanical Engineering, Toronto Univ., ON (Canada); Venter, R.D. [Thermodynamics and Kinetics Lab., Dept. of Mechanical Engineering, Toronto Univ., ON (Canada); Ho, S. [Thermodynamics and Kinetics Lab., Dept. of Mechanical Engineering, Toronto Univ., ON (Canada)

    1997-05-01

    Analytical methods have been proposed recently for determining both the internal resistance of fuel cell electrodes and the fraction of the electrocatalyst that is completely utilized. To apply these methods requires that the Tafel slope and the equilibrium exchange current for the electrolyte-electrocatalyst combination to be known when this combination is exposed to O{sub 2} and when it is exposed to H{sub 2}. The Tafel parameters have been previously reported for O{sub 2} and their measurement for H{sub 2} is reported herein. Also, to apply one of these analytical methods - maximum power method - requires that the current and potential to be measured when a fuel cell is operating at steady state and at maximum power. To apply the second method - approximate maximum power method - requires that the cell potential and slope of the potential versus current curve be measured at a current that is less than that corresponding to maximum power. To evaluate these methods, a series of porous carbon electrodes were constructed, and to give them different resistances nickel was electro-deposited on the one side of each. These electrodes were then assembled into fuel cells and tested. Their internal resistance was determined by the current-interrupt technique, and by using the analytical methods. These results agree to within the experimental error, 12%. Electro-depositing nickel on the gas side of the electrodes was found to decrease their internal resistance by an order of magnitude and increase the electrocatalyst utilization by a factor of three. (orig.)

  3. Unusual resistance of ALR/Lt mouse β cells to autoimmune destruction: Role for β cell-expressed resistance determinants

    Science.gov (United States)

    Mathews, Clayton E.; Graser, Robert T.; Savinov, Alexei; Serreze, David V.; Leiter, Edward H.

    2001-01-01

    Genetic analysis of autoimmune insulin-dependent diabetes mellitus (IDDM) has focused on genes controlling immune functions, with little investigation of innate susceptibility determinants expressed at the level of target β cells. The Alloxan (AL) Resistant (R) Leiter (Lt) mouse strain, closely related to the IDDM-prone nonobese diabetic (NOD)/Lt strain, demonstrates the importance of such determinants. ALR mice are unusual in their high constitutive expression of molecules associated with dissipation of free-radical stress systemically and at the β-cell level. ALR islets were found to be remarkably resistant to two different combinations of β-cytotoxic cytokines (IL-1β, tumor necrosis factor α, and IFN-γ) that destroyed islets from the related NOD and alloxan-susceptible strains. The close MHC relatedness between the NOD and ALR strains (H2-Kd and H2-Ag7 identical) allowed us to examine whether ALR islet cells could survive autoimmune destruction by NOD-derived Kd-restricted diabetogenic cytotoxic T lymphocyte clones (AI4 and the insulin-reactive G9C8 clones). Both clones killed islet cells from all Kd-expressing strains except ALR. ALR resistance to diabetogenic immune systems was determined in vivo by means of adoptive transfer of the G9C8 clone or by chimerizing lethally irradiated ALR or reciprocal (ALR × NOD)F1 recipients with NOD bone marrow. In all in vivo systems, ALR and F1 female recipients of NOD marrow remained IDDM free; in contrast, all of the NOD recipients became diabetic. In conclusion, the ALR mouse presents a unique opportunity to identify dominant IDDM resistance determinants expressed at the β cell level. PMID:11136257

  4. Use of tissue culture cell lines to evaluate HIV antiviral resistance.

    Science.gov (United States)

    Krowicka, Halina; Robinson, James E; Clark, Rebecca; Hager, Shannon; Broyles, Stephanie; Pincus, Seth H

    2008-07-01

    Most current assays of HIV antiviral resistance are based on either sequencing of viral genes (genotypic assays) or amplification and insertion of these genes into standardized virus backbones and culture. These latter are called phenotypic assays. But the only generally accepted phenotypic assay is based upon culture of intact patient virus, performed in phytohemagglutinin-activated peripheral blood mononuclear cells (PHA blasts) in the presence of differing drug concentrations. However, PHA blast culture is difficult and not always reproducible. Therefore we have sought cell lines that may produce more predictable results, yet faithfully mirror results in PHA blasts. We have compared 10 different cell lines for receptor and coreceptor expression, growth of laboratory-adapted strains of HIV, growth by direct inoculation of PBMC from infected patients, and in assays of antiviral drug effects. One of these cell lines, C8166-R5, is statistically not inferior to CD8-depleted PHA blasts for culturing HIV from the peripheral blood cells of patients. The effective concentrations of antiviral drugs of all classes were similar when assayed in C8166-R5 or PHA blasts. Known drug-resistant isolates grown in C8166-R5 demonstrated the predicted effects. We followed a patient longitudinally and demonstrated that resistance testing in C8166-R5 was predictive of clinical outcome. These experiments represent the first steps in developing a clinically useful phenotypic drug resistance assay based upon culturing the patient's own virus.

  5. Sildenafil Reduces Insulin-Resistance in Human Endothelial Cells

    Science.gov (United States)

    Mammi, Caterina; Pastore, Donatella; Lombardo, Marco F.; Ferrelli, Francesca; Caprio, Massimiliano; Consoli, Claudia; Tesauro, Manfredi; Gatta, Lucia; Fini, Massimo; Federici, Massimo; Sbraccia, Paolo; Donadel, Giulia; Bellia, Alfonso; Rosano, Giuseppe M.; Fabbri, Andrea; Lauro, Davide

    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 cells (HUVECs) were treated with insulin in presence of glucose 30 mM (HG) and glucosamine 10 mM (Gluc-N) with or without sildenafil. Insulin increased the expression of PDE5 and eNOS mRNA assayed by Real time-PCR. Cytofluorimetric analysis showed that sildenafil significantly increased NO production in basal condition. This effect was partially inhibited by the PI3K inhibitor LY 294002 and completely inhibited by the NOS inhibitor L-NAME. Akt-1 and eNOS activation was reduced in conditions mimicking insulin resistance and completely restored by sildenafil treatment. Conversely sildenafil treatment can counteract this noxious effect by increasing NO production through eNOS activation and reducing oxidative stress induced by hyperglycaemia and glucosamine. Conclusions/Significance These data indicate that sildenafil might improve NOS activity of endothelial cells in insulin resistance conditions and suggest the potential therapeutic use of sildenafil for improving vascular function in diabetic patients. PMID:21297971

  6. Sildenafil reduces insulin-resistance in human endothelial cells.

    Directory of Open Access Journals (Sweden)

    Caterina Mammi

    Full Text Available 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 cells (HUVECs were treated with insulin in presence of glucose 30 mM (HG and glucosamine 10 mM (Gluc-N with or without sildenafil. Insulin increased the expression of PDE5 and eNOS mRNA assayed by Real time-PCR. Cytofluorimetric analysis showed that sildenafil significantly increased NO production in basal condition. This effect was partially inhibited by the PI3K inhibitor LY 294002 and completely inhibited by the NOS inhibitor L-NAME. Akt-1 and eNOS activation was reduced in conditions mimicking insulin resistance and completely restored by sildenafil treatment. Conversely sildenafil treatment can counteract this noxious effect by increasing NO production through eNOS activation and reducing oxidative stress induced by hyperglycaemia and glucosamine. CONCLUSIONS/SIGNIFICANCE: These data indicate that sildenafil might improve NOS activity of endothelial cells in insulin resistance conditions and suggest the potential therapeutic use of sildenafil for improving vascular function in diabetic patients.

  7. Lipids that determine detergent resistance of MDCK cell membrane fractions.

    Science.gov (United States)

    Manni, Marco M; Cano, Ainara; Alonso, Cristina; Goñi, Félix M

    2015-10-01

    A comparative lipidomic study has been performed of whole Madin-Darby canine kidney epithelial cells and of the detergent-resistant membrane fraction (DRM) obtained after treating the cells with the non-ionic detergent Triton X-100. The DRM were isolated following a standard procedure that is extensively used in cell biology studies. Significant differences were found in the lipid composition of the whole cells and of DRM. The latter were enriched in all the analyzed sphingolipid classes: sphingomyelins, ceramides and hexosylceramides. Diacylglycerols were also preferentially found in DRM. The detergent-resistant fraction was also enriched in saturated over unsaturated fatty acyl chains, and in sn-1 acyl chains containing 16 carbon atoms, over the longer and shorter ones. The glycerophospholipid species phosphatidylethanolamines and phosphatidylinositols, that were mainly unsaturated, did not show a preference for DRM. Phosphatidylcholines were an intermediate case: the saturated, but not the unsaturated species were found preferentially in DRM. The question remains on whether these DRM, recovered from detergent-membrane mixtures by floatation over a sucrose gradient, really correspond to membrane domains existing in the cell membrane prior to detergent treatment. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  8. Resistance to DNA denaturation in irradiated Chinese hamster V79 fibroblasts is linked to cell shape

    International Nuclear Information System (INIS)

    Olive, P.L.; Vanderbyl, S.; MacPhail, S.H.

    1991-01-01

    Exponentially growing Chinese hamster V79-171b lung fibroblasts seeded at high density on plastic (approximately 7 x 10(3) cells/cm2) flatten, elongate, and produce significant amounts of extracellular fibronectin. When lysed in weak alkali/high salt, the rate of DNA denaturation following exposure to ionizing radiation is exponential. Conversely, cells plated at low density (approximately 7 x 10(2) cells/cm2) on plastic are more rounded 24 h later, produce little extracellular fibronectin, and display unusual DNA denaturation kinetics after X-irradiation. DNA in these cells resists denaturation, as though constraints to DNA unwinding have developed. Cell doubling time and distribution of cells in the growth cycle are identical for both high and low density cultures as is cell survival in response to radiation damage. The connection between DNA conformation and cell shape was examined further in low density cultures grown in conditioned medium. Under these conditions, cells at low density were able to elongate, and DNA denaturation of low density cultures was identical to that of high density cultures. Conversely, cytochalasin D, which interferes with actin polymerization causing cells to round up and release fibronectin, allowed development of constraints in high density cultures. These results suggest that DNA conformation is sensitive to changes in cell shape which result when cells are grown in different environments. However, these changes in DNA conformation detected by the DNA unwinding assay do not appear to play a direct role in radiation-induced cell killing

  9. Development of fire resistant, nontoxic aircraft interior materials

    Science.gov (United States)

    Haley, G.; Silverman, B.; Tajima, Y.

    1976-01-01

    All available newly developed nonmetallic polymers were examined for possible usage in developing fire resistant, nontoxic nonmetallic parts or assemblies for aircraft interiors. Specifically, feasibility for the development of clear films for new decorative laminates, compression moldings, injection molded parts, thermoformed plastic parts, and flexible foams were given primary considerations. Preliminary data on the flame resistant characteristics of the materials were obtained. Preliminary toxicity data were generated from samples of materials submitted from the contractor. Preliminary data on the physical characteristics of various thermoplastic materials to be considered for either compression molded, injection molded, or thermoformed parts were obtained.

  10. Characterisation of non-P-glycoprotein multidrug-resistant Ehrlich ascites tumour cells selected for resistance to mitoxantrone

    DEFF Research Database (Denmark)

    Nielsen, D; Eriksen, J; Maare, C

    2000-01-01

    . The efflux of daunorubicin from preloaded EHR2/MITOX cells was significantly increased. EHR2/MITOX microsomes had a significant basal unstimulated ATPase activity. The apparent K(i) value for vanadate inhibition of the ATPase activity in EHR2/MITOX microsomes was not significantly different from the K......An Ehrlich ascites tumour cell line (EHR2) was selected in vivo for resistance to mitoxantrone (MITOX). The resistant cell line (EHR2/MITOX) was 6123-, 33-, and 30-fold-resistant to mitoxantrone, daunorubicin, and etoposide, respectively, but retained sensitivity to vincristine. The resistant cells...... was reduced to one-third in EHR2/MITOX relative to EHR2 cells, whereas topoisomerase IIbeta was present in EHR2 but could not be detected in EHR2/MITOX. In the resistant subline, net accumulation of MITOX (120 min) and daunorubicin (60 min) was reduced by 43% and 27%, respectively, as compared with EHR2...

  11. Treg cell resistance to apoptosis in DNA vaccination for experimental autoimmune encephalomyelitis treatment.

    Directory of Open Access Journals (Sweden)

    Youmin Kang

    Full Text Available BACKGROUND: Regulatory T (Treg cells can be induced with DNA vaccinations and protect mice from the development of experimental autoimmune encephalomyelitis (EAE, a mouse model of multiple sclerosis (MS. Tacrolimus (FK506 has been shown to have functions on inducing immunosuppression and augmenting apoptosis of pathologic T cells in autoimmune disease. Here we examined the therapeutic effect of DNA vaccine in conjunction with FK506 on EAE. METHODOLOGY/PRINCIPAL FINDINGS: After EAE induction, C57BL/6 mice were treated with DNA vaccine in conjunction with FK506. Functional Treg cells were induced in treated EAE mice and suppressed Th1 and Th17 cell responses. Infiltrated CD4 T cells were reduced while Treg cells were induced in spinal cords of treated EAE mice. Remarkably, the activated CD4 T cells augmented apoptosis, but the induced Treg cells resisted apoptosis in treated EAE mice, resulting in alleviation of clinical EAE severity. CONCLUSIONS/SIGNIFICANCE: DNA vaccine in conjunction with FK506 treatment ameliorates EAE by enhancing apoptosis of CD4 T cells and resisting apoptosis of induced Treg cells. Our findings implicate the potential of tolerogenic DNA vaccines for treating MS.

  12. Transfection of rat embryo cells with mutant p53 increases the intrinsic radiation resistance

    International Nuclear Information System (INIS)

    Pardo, F.S.; Su, M.; Gerweck, L.; Schmidt, E.V.; Borek, C.; Preffer, F.; Dombkowski, D.

    1994-01-01

    Dominant oncogenic sequences have been shown to modulate the intrinsic radiation sensitivity of cells of both human and murine tumor cell lines. Whether transfection with candidate tumor-suppressor genes can modulate intrinsic radiation sensitivity is unknown. The data presented here demonstrate that transfection of rat embryo cells with a mutant p53 allele can increase the intrinsic radiation resistance of cells in vitro. First, transfection with mutant p53 resulted in transformed cellular morphology. Second, the transfected clone and the corresponding pooled population of transfected clones were more resistant to ionizing radiation in vitro. Last, analyses of the parameters of cell kinetics suggested that the radiobiological effects were unlikely to be due to altered parameters of cell kinetics at the time of irradiation, suggesting that mutant p53 altered the intrinsic radiation resistance of transfected cells by a more direct mechanism. Further experimentation will be necessary to develop a mechanistic approach for the study of these alterations. 29 refs., 3 figs., 2 tabs

  13. New Insights on Schwann Cell Development

    Science.gov (United States)

    Monk, Kelly R.; Feltri, M. Laura; Taveggia, Carla

    2015-01-01

    In the peripheral nervous system, Schwann cells are glial cells that are in intimate contact with axons throughout development. Schwann cells generate the insulating myelin sheath and provide vital trophic support to the neurons that they ensheathe. Schwann cell precursors arise from neural crest progenitor cells, and a highly ordered developmental sequence controls the progression of these cells to become mature myelinating or non-myelinating Schwann cells. Here, we discuss both seminal discoveries and recent advances in our understanding of the molecular mechanisms that drive Schwann cell development and myelination with a focus on cell-cell and cell-matrix signaling events. PMID:25921593

  14. Overlapping phenotypes of multidrug resistance among panels of human cancer-cell lines.

    Science.gov (United States)

    Izquierdo, M A; Shoemaker, R H; Flens, M J; Scheffer, G L; Wu, L; Prather, T R; Scheper, R J

    1996-01-17

    In addition to P-glycoprotein (Pgp), 2 proteins related to multidrug resistance (MDR) have recently been described. The Multidrug-Resistance-associated protein (MRP) is one of the ATP-binding-cassette (ABC) transporters. The Lung-Resistance Protein (LRP) is the major component of human vaults, which are newly described cellular organelles and thought to mediate intracellular transport processes. Using immunocytochemical methods, we have examined the expression of MRP and LRP among panels of human cancer-cell lines not selected for drug resistance which have been previously characterized for expression of Pgp, and in vitro response to a variety of anti-cancer drugs. Expression of MRP and LRP was observed in 47/55 (87%) and 46/59 (78%) cell lines, respectively. Statistically significant correlations were observed between expression of each of these 3 proteins and in vitro sensitivity to at least one drug classically associated with MDR. LRP showed the greatest individual predictive value, which also applied to several non-classical MDR drugs. Co-expression of 2-3 MDR-related proteins was observed in 64% of the lines and was, in general, associated with high relative levels of drug resistance. Previously identified "classic" MDR lines as well as "pan-resistant" lines concurrently expressed all 3 MDR-related proteins. Some highly drug-resistant cell lines without detectable MDRI/Pgp were found to express relatively high levels of MRP and LRP. The high prevalence of MRP and LRP expression observed in this large set of cell lines, which have not been subjected to laboratory drug selection, suggests that MDR mechanisms associated with these proteins may be widespread in human malignancies. Moreover, the overlapping of these more recently recognized MDR phenotypes with Pgp-type MDR results in a complex phenotype, the understanding of which may be of importance in the development of new drugs and design of clinical treatment protocols, particularly those seeking to employ

  15. Tumor Heterogeneity, Single-Cell Sequencing, and Drug Resistance

    Directory of Open Access Journals (Sweden)

    Felix Schmidt

    2016-06-01

    Full Text Available Tumor heterogeneity has been compared with Darwinian evolution and survival of the fittest. The evolutionary ecosystem of tumors consisting of heterogeneous tumor cell populations represents a considerable challenge to tumor therapy, since all genetically and phenotypically different subpopulations have to be efficiently killed by therapy. Otherwise, even small surviving subpopulations may cause repopulation and refractory tumors. Single-cell sequencing allows for a better understanding of the genomic principles of tumor heterogeneity and represents the basis for more successful tumor treatments. The isolation and sequencing of single tumor cells still represents a considerable technical challenge and consists of three major steps: (1 single cell isolation (e.g., by laser-capture microdissection, fluorescence-activated cell sorting, micromanipulation, whole genome amplification (e.g., with the help of Phi29 DNA polymerase, and transcriptome-wide next generation sequencing technologies (e.g., 454 pyrosequencing, Illumina sequencing, and other systems. Data demonstrating the feasibility of single-cell sequencing for monitoring the emergence of drug-resistant cell clones in patient samples are discussed herein. It is envisioned that single-cell sequencing will be a valuable asset to assist the design of regimens for personalized tumor therapies based on tumor subpopulation-specific genetic alterations in individual patients.

  16. Development of proliferation resistant isotope separation technology

    International Nuclear Information System (INIS)

    Jeong, Doyoung; Ko, Kwanghoon; Kim, Taeksoo; Park, Hyunmin; Lim, Gwon; Cha, Yongho; Han, Jaemin; Baik, Sunghoon; Cha, Hyungki

    2012-02-01

    This project was accomplished with an aim of establishing the industrial facilities for isotope separation in Korea. The experiment for the measurement of neutrino mass that has been an issue in physics, needs very much of enriched calcium-48 isotope. However, calcium-48 isotope can be produced only by the electro-magnetic method and, thus, its price is very expensive. Therefore, we expect that ALSIS can replace the electro-magnetic method for calcium-48 isotope production. In this research stage, the research was advanced systematically with core technologies, such as atomic vapor production, the measurement of vapor characteristics and stable and powerful laser development. These researches will be the basis of the next research stages. In addition, the international research trends and cooperation results are reported in this report

  17. The critical role of ERK in death resistance and invasiveness of hypoxia-selected glioblastoma cells

    International Nuclear Information System (INIS)

    Kim, Jee-Youn; Kim, Yong-Jun; Lee, Sun; Park, Jae-Hoon

    2009-01-01

    The rapid growth of tumor parenchyma leads to chronic hypoxia that can result in the selection of cancer cells with a more aggressive behavior and death-resistant potential to survive and proliferate. Thus, identifying the key molecules and molecular mechanisms responsible for the phenotypic changes associated with chronic hypoxia has valuable implications for the development of a therapeutic modality. The aim of this study was to identify the molecular basis of the phenotypic changes triggered by chronic repeated hypoxia. Hypoxia-resistant T98G (HRT98G) cells were selected by repeated exposure to hypoxia and reoxygenation. Cell death rate was determined by the trypan blue exclusion method and protein expression levels were examined by western blot analysis. The invasive phenotype of the tumor cells was determined by the Matrigel invasion assay. Immunohistochemistry was performed to analyze the expression of proteins in the brain tumor samples. The Student T-test and Pearson Chi-Square test was used for statistical analyses. We demonstrate that chronic repeated hypoxic exposures cause T98G cells to survive low oxygen tension. As compared with parent cells, hypoxia-selected T98G cells not only express higher levels of anti-apoptotic proteins such as Bcl-2, Bcl-X L , and phosphorylated ERK, but they also have a more invasive potential in Matrigel invasion chambers. Activation or suppression of ERK pathways with a specific activator or inhibitor, respectively, indicates that ERK is a key molecule responsible for death resistance under hypoxic conditions and a more invasive phenotype. Finally, we show that the activation of ERK is more prominent in malignant glioblastomas exposed to hypoxia than in low grade astrocytic glial tumors. Our study suggests that activation of ERK plays a pivotal role in death resistance under chronic hypoxia and phenotypic changes related to the invasive phenotype of HRT98G cells compared to parent cells

  18. Aurora kinase B is important for antiestrogen resistant cell growth and a potential biomarker for tamoxifen resistant breast cancer.

    Science.gov (United States)

    Larsen, Sarah L; Yde, Christina W; Laenkholm, Anne-Vibeke; Rasmussen, Birgitte B; Duun-Henriksen, Anne Katrine; Bak, Martin; Lykkesfeldt, Anne E; Kirkegaard, Tove

    2015-04-08

    Resistance to antiestrogen therapy is a major clinical challenge in the treatment of estrogen receptor α (ER)-positive breast cancer. The aim of the study was to explore the growth promoting pathways of antiestrogen resistant breast cancer cells to identify biomarkers and novel treatment targets. Antiestrogen sensitive and resistant T47D breast cancer cell lines were used as model systems. Parental and fulvestrant resistant cell lines were subjected to a kinase inhibitor library. Kinase inhibitors preferentially targeting growth of fulvestrant resistant cells were 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. 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 and PARP cleavage in the fulvestrant resistant cells. Barasertib also exerted preferential growth inhibition of tamoxifen resistant T47D cell lines. Finally, high percentage of Aurora kinase B positive tumor cells was significantly associated with reduced disease-free and overall survival in 261 ER-positive breast cancer patients, who have received tamoxifen as first-line adjuvant endocrine treatment. Our results indicate that Aurora kinase B is a driving factor for growth of antiestrogen resistant T47D breast

  19. Uncoupling salicylic acid-dependent cell death and defense-related responses from disease resistance in the Arabidopsis mutant acd5.

    OpenAIRE

    Greenberg, J T; Silverman, F P; Liang, H

    2000-01-01

    Salicylic acid (SA) is required for resistance to many diseases in higher plants. SA-dependent cell death and defense-related responses have been correlated with disease resistance. The accelerated cell death 5 mutant of Arabidopsis provides additional genetic evidence that SA regulates cell death and defense-related responses. However, in acd5, these events are uncoupled from disease resistance. acd5 plants are more susceptible to Pseudomonas syringae early in development and show spontaneou...

  20. Visual detection of multidrug resistance gene in living cell using the molecular beacon imaging

    Science.gov (United States)

    Zhou, Qiumei; Ma, Yi; Gu, Yueqing

    2014-09-01

    A major problem in cancer treatment is the development of resistance to chemotherapeutic agents in tumor cells. Detection of effective prognostic biomarkers and targets are of crucial importance to the management of individualized therapies. However, quantitative analysis of the drug resistance gene had been difficult because of technical limitations. In this study, we designed and used a special hairpin deoxyribonucleic acid (DNA), which served as a beacon for detecting human drug resistance indicater. Upon hybridizing with the target mRNA, the hairpin DNA modified gold nanoparticle beacons (hDAuNP beacons) release the fluorophores attached at 5'end of the oligonucleotide sequence. The fluorescence properties of the beacon before and after the hybridization with the complementary DNA were confirmed in vitro. The hDAuNP beacons could be taken up by living cells with low inherent cytotoxicity and higher stability. hDAuNP beacon imaged by confocal laser scanning microscopy to detect the resistance gene expression. The detected fluorescence in MCF7and MCF7/ADR cells correlates with the specific drug resistance gene expression, which is consistent with the result from Q-PCR. Thus, this approach overcame many of the challenges of previous techniques by creating highly sensitive and effective intracellular probes for monitoring gene expression.

  1. Daptomycin resistance in enterococci is associated with distinct alterations of cell membrane phospholipid content.

    Directory of Open Access Journals (Sweden)

    Nagendra N Mishra

    Full Text Available The lipopeptide antibiotic, daptomycin (DAP interacts with the bacterial cell membrane (CM. Development of DAP resistance during therapy in a clinical strain of Enterococcus faecalis was associated with mutations in genes encoding enzymes involved in cell envelope homeostasis and phospholipid metabolism. Here we characterized changes in CM phospholipid profiles associated with development of DAP resistance in clinical enterococcal strains.Using two clinical strain-pairs of DAP-susceptible and DAP-resistant E. faecalis (S613 vs. R712 and E. faecium (S447 vs. R446 recovered before and after DAP therapy, we compared four distinct CM profiles: phospholipid content, fatty acid composition, membrane fluidity and capacity to be permeabilized and/or depolarized by DAP. Additionally, we characterized the cell envelope of the E. faecium strain-pair by transmission electron microscopy and determined the relative cell surface charge of both strain-pairs.Both E. faecalis and E. faecium mainly contained four major CM PLs: phosphatidylglycerol (PG, cardiolipin, lysyl-phosphatidylglycerol (L-PG and glycerolphospho-diglycodiacylglycerol (GP-DGDAG. In addition, E. faecalis CMs (but not E. faecium also contained: i phosphatidic acid; and ii two other unknown species of amino-containing PLs. Development of DAP resistance in both enterococcal species was associated with a significant decrease in CM fluidity and PG content, with a concomitant increase in GP-DGDAG. The strain-pairs did not differ in their outer CM translocation (flipping of amino-containing PLs. Fatty acid content did not change in the E. faecalis strain-pair, whereas a significant decrease in unsaturated fatty acids was observed in the DAP-resistant E. faecium isolate R446 (vs S447. Resistance to DAP in E. faecium was associated with distinct structural alterations of the cell envelope and cell wall thickening, as well as a decreased ability of DAP to depolarize and permeabilize the CM

  2. Inhibiting autophagy overcomes docetaxel resistance in castration-resistant prostate cancer cells.

    Science.gov (United States)

    Wang, Quan; He, Wei-Yang; Zeng, Yi-Zhou; Hossain, Arman; Gou, Xin

    2018-02-19

    This study investigates the docetaxel-resistant mechanism and explores the effect of tea polyphenols (TP) on autophagy and its related mechanism in human castration-resistant prostate cancer (CRPC) cell lines PC3 and DU145. Immunofluorescence assay and annexin V-FITC/PI double staining flow cytometry were used to analyze the apoptosis and autophagy of PC3 and DU145 cells. The expression of autophagy-related proteins was detected by western bolt. Docetaxel could induce autophagy and apoptosis, together with the expression increase in p-JNK, p-Bcl-2 and Beclin1. The level of autophagy was remarkably decreased, but apoptosis was increased after combining with TP. In addition, the expression of p-mTOR was increased after combining with TP. Docetaxel induces protective autophagy in CRPC cells by JNK pathway activation and then Bcl-2 phosphorylation and Beclin1 dissociation. TP activates mTOR pathway, which ultimately inhibits docetaxel-induced autophagy and improves therapeutic efficacy of docetaxel in CRPC cells.

  3. Mechanisms of therapeutic resistance in cancer (stem cells with emphasis on thyroid cancer cells.

    Directory of Open Access Journals (Sweden)

    Sabine eHombach-Klonisch

    2014-03-01

    Full Text Available Tissue invasion, metastasis and therapeutic resistance to anti-cancer treatments are common and main causes of death in cancer patients. Tumor cells mount complex and still poorly understood molecular defense mechanisms to counteract and evade oxygen deprivation, nutritional restrictions as well as radio- and chemotherapeutic treatment regimens aimed at destabilizing their genomes and important cellular processes. In thyroid cancer, as in other tumors, such defense strategies include the reactivation in cancer cells of early developmental programs normally active exclusively in stem cells, the stimulation of cancer stem-like cells resident within the tumor tissue and the recruitment of bone marrow-derived progenitors into the tumor (Thomas et al., 2008;Klonisch et al., 2009;Derwahl, 2011. Metastasis and therapeutic resistance in cancer (stem cells involves the epithelial-to-mesenchymal transition- (EMT- mediated enhancement in cellular plasticity, which includes coordinated dynamic biochemical and nuclear changes (Ahmed et al., 2010. The purpose of the present review is to provide an overview of the role of DNA repair mechanisms contributing to therapeutic resistance in thyroid cancer and highlight the emerging roles of autophagy and damage associated molecular pattern (DAMP responses in EMT and chemoresistance in tumor cells. Finally, we use the stem cell factor and nucleoprotein High Mobility Group A2 (HMGA2 as an example to demonstrate how factors intended to protect stem cells are wielded by cancer (stem cells to gain increased transformative cell plasticity which enhances metastasis, therapeutic resistance and cell survival. Wherever possible, we have included information on these cellular processes and associated factors as they relate to thyroid cancer cells.

  4. Resistivity and thickness effects in dendritic web silicon solar cells

    Science.gov (United States)

    Meier, D. L.; Hwang, J. M.; Greggi, J.; Campbell, R. B.

    1987-01-01

    The decrease of minority carrier lifetime as resistivity decreases in dendritic-web silicon solar cells is addressed. This variation is shown to be consistent with the presence of defect levels in the bandgap which arise from extended defects in the web material. The extended defects are oxide precipitates (SiOx) and the dislocation cores they decorate. Sensitivity to this background distribution of defect levels increases with doping because the Fermi level moves closer to the majority carrier band edge. For high-resistivity dendritic-web silicon, which has a low concentration of these extended defects, cell efficiencies as high as 16.6 percent (4 sq cm, 40 ohm-cm boron-doped base, AM1.5 global, 100 mW/sq cm, 25 C JPL LAPSS1 measurement) and a corresponding electron lifetime of 38 microsec have been obtained. Thickness effects occur in bifacial cell designs and in designs which use light trapping. In some cases, the dislocation/precipitate defect can be passivated through the full thickness of web cells by hydrogen ion implantation.

  5. Differential microRNA expression signatures and cell type-specific association with Taxol resistance in ovarian cancer cells.

    Science.gov (United States)

    Kim, Yong-Wan; Kim, Eun Young; Jeon, Doin; Liu, Juinn-Lin; Kim, Helena Suhyun; Choi, Jin Woo; Ahn, Woong Shick

    2014-01-01

    Paclitaxel (Taxol) resistance remains a major obstacle for the successful treatment of ovarian cancer. MicroRNAs (miRNAs) have oncogenic and tumor suppressor activity and are associated with poor prognosis phenotypes. miRNA screenings for this drug resistance are needed to estimate the prognosis of the disease and find better drug targets. miRNAs that were differentially expressed in Taxol-resistant ovarian cancer cells, compared with Taxol-sensitive cells, were screened by Illumina Human MicroRNA Expression BeadChips. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was used to identify target genes of selected miRNAs. Kaplan-Meier survival analysis was applied to identify dysregulated miRNAs in ovarian cancer patients using data from The Cancer Genome Atlas. A total of 82 miRNAs were identified in ovarian carcinoma cells compared to normal ovarian cells. miR-141, miR-106a, miR-200c, miR-96, and miR-378 were overexpressed, and miR-411, miR-432, miR-494, miR-409-3p, and miR-655 were underexpressed in ovarian cancer cells. Seventeen miRNAs were overexpressed in Taxol-resistant cells, including miR-663, miR-622, and HS_188. Underexpressed miRNAs in Taxol-sensitive cells included miR-497, miR-187, miR-195, and miR-107. We further showed miR-663 and miR-622 as significant prognosis markers of the chemo-resistant patient group. In particular, the downregulation of the two miRNAs was associated with better survival, perhaps increasing the sensitivity of cancer cells to Taxol. In the chemo-sensitive patient group, only miR-647 could be a prognosis marker. These miRNAs inhibit several interacting genes of p53 networks, especially in TUOS-3 and TUOS-4, and showed cell line-specific inhibition effects. Taken together, the data indicate that the three miRNAs are closely associated with Taxol resistance and potentially better prognosis factors. Our results suggest that these miRNAs were successfully and reliably identified and would be used in the

  6. Role of Insulin-Like Growth Factor-1 Signaling Pathway in Cisplatin-Resistant Lung Cancer Cells

    International Nuclear Information System (INIS)

    Sun Yunguang; Zheng Siyuan; Torossian, Artour; Speirs, Christina K.; Schleicher, Stephen; Giacalone, Nicholas J.; Carbone, David P.; Zhao Zhongming; Lu Bo

    2012-01-01

    Purpose: The development of drug-resistant phenotypes has been a major obstacle to cisplatin use in non–small-cell lung cancer. We aimed to identify some of the molecular mechanisms that underlie cisplatin resistance using microarray expression analysis. Methods and Materials: H460 cells were treated with cisplatin. The differences between cisplatin-resistant lung cancer cells and parental H460 cells were studied using Western blot, MTS, and clonogenic assays, in vivo tumor implantation, and microarray analysis. The cisplatin-R cells were treated with human recombinant insulin-like growth factor (IGF) binding protein-3 and siRNA targeting IGF-1 receptor. Results: Cisplatin-R cells illustrated greater expression of the markers CD133 and aldehyde dehydrogenase, more rapid in vivo tumor growth, more resistance to cisplatin- and etoposide-induced apoptosis, and greater survival after treatment with cisplatin or radiation than the parental H460 cells. Also, cisplatin-R demonstrated decreased expression of insulin-like growth factor binding protein-3 and increased activation of IGF-1 receptor signaling compared with parental H460 cells in the presence of IGF-1. Human recombinant IGF binding protein-3 reversed cisplatin resistance in cisplatin-R cells and targeting of IGF-1 receptor using siRNA resulted in sensitization of cisplatin-R-cells to cisplatin and radiation. Conclusions: The IGF-1 signaling pathway contributes to cisplatin-R to cisplatin and radiation. Thus, this pathway represents a potential target for improved lung cancer response to treatment.

  7. Role of Insulin-Like Growth Factor-1 Signaling Pathway in Cisplatin-Resistant Lung Cancer Cells

    Energy Technology Data Exchange (ETDEWEB)

    Sun Yunguang [Department of Radiation Oncology, Vanderbilt University Medical Center, Nashville, TN (United States); Zheng Siyuan [Department of Biomedical Informatics, Vanderbilt University Medical Center, Nashville, TN (United States); Torossian, Artour; Speirs, Christina K.; Schleicher, Stephen; Giacalone, Nicholas J. [Department of Radiation Oncology, Vanderbilt University Medical Center, Nashville, TN (United States); Carbone, David P. [Department of Hematology and Oncology, Vanderbilt University Medical Center, Nashville, TN (United States); Zhao Zhongming, E-mail: zhongming.zhao@vanderbilt.edu [Department of Biomedical Informatics, Vanderbilt University Medical Center, Nashville, TN (United States); Lu Bo, E-mail: bo.lu@vanderbilt.edu [Department of Radiation Oncology, Vanderbilt University Medical Center, Nashville, TN (United States)

    2012-03-01

    Purpose: The development of drug-resistant phenotypes has been a major obstacle to cisplatin use in non-small-cell lung cancer. We aimed to identify some of the molecular mechanisms that underlie cisplatin resistance using microarray expression analysis. Methods and Materials: H460 cells were treated with cisplatin. The differences between cisplatin-resistant lung cancer cells and parental H460 cells were studied using Western blot, MTS, and clonogenic assays, in vivo tumor implantation, and microarray analysis. The cisplatin-R cells were treated with human recombinant insulin-like growth factor (IGF) binding protein-3 and siRNA targeting IGF-1 receptor. Results: Cisplatin-R cells illustrated greater expression of the markers CD133 and aldehyde dehydrogenase, more rapid in vivo tumor growth, more resistance to cisplatin- and etoposide-induced apoptosis, and greater survival after treatment with cisplatin or radiation than the parental H460 cells. Also, cisplatin-R demonstrated decreased expression of insulin-like growth factor binding protein-3 and increased activation of IGF-1 receptor signaling compared with parental H460 cells in the presence of IGF-1. Human recombinant IGF binding protein-3 reversed cisplatin resistance in cisplatin-R cells and targeting of IGF-1 receptor using siRNA resulted in sensitization of cisplatin-R-cells to cisplatin and radiation. Conclusions: The IGF-1 signaling pathway contributes to cisplatin-R to cisplatin and radiation. Thus, this pathway represents a potential target for improved lung cancer response to treatment.

  8. Development of ceftazidime resistance in an acute Burkholderia pseudomallei infection

    Directory of Open Access Journals (Sweden)

    Sarovich DS

    2012-08-01

    Full Text Available Derek S Sarovich,1,2,* Erin P Price,1,2,* Direk Limmathurotsakul,3 James M Cook,1 Alex T Von Schulze,1 Spenser R Wolken,1 Paul Keim,1 Sharon J Peacock,3,4 Talima Pearson1 1Center for Microbial Genetics and Genomics, Northern Arizona University, Flagstaff, AZ, USA; 2Tropical and Emerging Infectious Diseases Division, Menzies School of Health Research, Darwin, Australia; 3Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand; 4Department of Medicine, University of Cambridge, Cambridge, United Kingdom*These authors contributed equally to this workAbstract: Burkholderia pseudomallei, a bacterium that causes the disease melioidosis, is intrinsically resistant to many antibiotics. First-line antibiotic therapy for treating melioidosis is usually the synthetic β-lactam, ceftazidime (CAZ, as almost all B. pseudomallei strains are susceptible to this drug. However, acquired CAZ resistance can develop in vivo during treatment with CAZ, which can lead to mortality if therapy is not switched to a different drug in a timely manner. Serial B. pseudomallei isolates obtained from an acute Thai melioidosis patient infected by a CAZ susceptible strain, who ultimately succumbed to infection despite being on CAZ therapy for the duration of their infection, were analyzed. Isolates that developed CAZ resistance due to a proline to serine change at position 167 in the β-lactamase PenA were identified. Importantly, these CAZ resistant isolates remained sensitive to the alternative melioidosis treatments; namely, amoxicillin-clavulanate, imipenem, and meropenem. Lastly, real-time polymerase chain reaction-based assays capable of rapidly identifying CAZ resistance in B. pseudomallei isolates at the position 167 mutation site were developed. The ability to rapidly identify the emergence of CAZ resistant B. pseudomallei populations in melioidosis patients will allow timely alterations in treatment strategies

  9. Development of radiation-resisting high molecular-weight materials

    International Nuclear Information System (INIS)

    Nakagawa, Tsutomu

    1976-01-01

    The excellent radiation-resisting polyvinyl chloride developed at the opportunity of the research on the relationships between the protection of living body and the polymer-technological protection from radiation is reviewed. The report is divided into four main parts, namely 1) the change in the molecular arrangement of market-available, high molecular-weight materials by gamma-ray irradiation, 2) the protection of high molecular-weight materials from radiation, 3) the relationships between the biological radiation-protective substances and the change to radiation-resisting property of synthesized high molecular-weight substances, and 4) the development of the radiation-resisting high molecular-weight materials as metal-collecting agents. Attention is paid to the polyvinyl chloride having N-methyl-dithio-carbamate radical (PMD), synthesized by the author et. al., that has excellent radiation-resisting property. PMD has some possibility to form thiol- and amino-radicals necessary to protect living things from radiation. It is believed that the protection effects of N-methyl-dithio-carbamate radical are caused by the relatively stable S radical produced by the energy transfer. PMD film is suitable for the irradiation of foods, because it hardly changes the permeability of oxygen and carbon dioxide. PMD produces mercaptide or chelate. A new metal-collecting agent (PSDC) having reactivity with the metallic ions with radiation-resisting property was developed, which is derived from polyvinyl chloride and sodium N-methyl-N-carboxy-methyl-dithio-carbamate. (Iwakiri, K.)

  10. Development of Creep-Resistant and Oxidation-Resistant Austenitic Stainless Steels for High Temperature Applications

    Science.gov (United States)

    Maziasz, Philip J.

    2018-01-01

    Austenitic stainless steels are cost-effective materials for high-temperature applications if they have the oxidation and creep resistance to withstand prolonged exposure at such conditions. Since 1990, Oak Ridge National Laboratory (ORNL) has developed advanced austenitic stainless steels with creep resistance comparable to Ni-based superalloy 617 at 800-900°C based on specially designed "engineered microstructures" utilizing a microstructure/composition database derived from about 20 years of radiation effect data on steels. The wrought high temperature-ultrafine precipitate strengthened (HT-UPS) steels with outstanding creep resistance at 700-800°C were developed for supercritical boiler and superheater tubing for fossil power plants in the early 1990s, the cast CF8C-Plus steels were developed in 1999-2001 for land-based gas turbine casing and diesel engine exhaust manifold and turbocharger applications at 700-900°C, and, in 2015-2017, new Al-modified cast stainless steels with oxidation and creep resistance capabilities up to 950-1000°C were developed for automotive exhaust manifold and turbocharger applications. This article reviews and summarizes their development and their properties and applications.

  11. Involvement of MKP-1 and Bcl-2 in acquired cisplatin resistance in ovarian cancer cells

    OpenAIRE

    Wang, Juan; Zhou, Jun-Ying; Zhang, Lianfeng; Wu, Gen Sheng

    2009-01-01

    Although cisplatin is a very effective anticancer agent against several types of cancer including ovarian cancer, the mechanisms of acquired resistance are not fully understood. By chronically exposing cisplatin to ovarian cancer cell lines, we established two cisplatin-resistant cell lines OV433 and tOV112D. Our results indicate that the mechanisms underlying their cisplatin resistance are distinct. In OV433 cells, cisplatin resistance is associated with increased expression of mitogen-activ...

  12. Characterisation of non-P-glycoprotein multidrug-resistant Ehrlich ascites tumour cells selected for resistance to mitoxantrone

    DEFF Research Database (Denmark)

    Nielsen, D; Eriksen, J; Maare, C

    2000-01-01

    An Ehrlich ascites tumour cell line (EHR2) was selected in vivo for resistance to mitoxantrone (MITOX). The resistant cell line (EHR2/MITOX) was 6123-, 33-, and 30-fold-resistant to mitoxantrone, daunorubicin, and etoposide, respectively, but retained sensitivity to vincristine. The resistant cel...... to be associated with: 1) a quantitative reduction in topoisomerase IIalpha and beta protein; 2) reduced drug accumulation, probably as a result of increased expression of a novel transport protein with ATPase activity; and 3) increased expression of MRP mRNA....

  13. Development of quinoxaline 1, 4-dioxides resistance in Escherichia coli and molecular change under resistance selection.

    Directory of Open Access Journals (Sweden)

    Wentao Guo

    Full Text Available Quinoxaline 1, 4-dioxides (QdNOs has been used in animals as antimicrobial agents and growth promoters for decades. However, the resistance to QdNOs in pathogenic bacteria raises worldwide concern but it is barely known. To explore the molecular mechanism involved in development of QdNOs resistance in Escherichia coli, 6 strains selected by QdNOs in vitro and 21 strains isolated from QdNOs-used swine farm were subjected to MIC determination and PCR amplification of oqxA gene. A conjugative transfer was carried out to evaluate the transfer risk of QdNOs resistant determinant. Furthermore, the transcriptional profile of a QdNOs-resistant E. coli (79O4-2 selected in vitro with its parent strain 79-161 was assayed with a prokaryotic suppression subtractive hybridization (SSH PCR cDNA subtraction. The result showed that more than 95% (20/21 clinical isolates were oqxA positive, while all the 6 induced QdNOs-resistant strains carried no oqxA gene and exhibited low frequency of conjugation. 44 fragments were identified by SSH PCR subtraction in the QdNOs-resistant strain 79O4-2. 18 cDNAs were involved in biosynthesis of Fe-S cluster (narH, protein (rpoA, trmD, truA, glyS, ileS, rplFCX, rpsH, fusA, lipoate (lipA, lipid A (lpxC, trehalose (otsA, CTP(pyrG and others molecular. The 11 cDNAs were related to metabolism or degradation of glycolysis (gpmA and pgi and proteins (clpX, clpA, pepN and fkpB. The atpADG and ubiB genes were associated with ATP biosynthesis and electron transport chain. The pathway of the functional genes revealed that E. coli may adapt the stress generated by QdNOs or develop specific QdNOs-resistance by activation of antioxidative agents biosynthesis (lipoate and trehalose, protein biosynthesis, glycolysis and oxidative phosphorylation. This study initially reveals the possible molecular mechanism involved in the development of QdNOs-resistance in E. coli, providing with novel insights in prediction and assessment of the emergency

  14. Involvement of Cox-2 in the metastatic potential of chemotherapy-resistant breast cancer cells

    International Nuclear Information System (INIS)

    Kang, Ju-Hee; Song, Ki-Hoon; Jeong, Kyung-Chae; Kim, Sunshin; Choi, Changsun; Lee, Chang Hoon; Oh, Seung Hyun

    2011-01-01

    A major problem with the use of current chemotherapy regimens for several cancers, including breast cancer, is development of intrinsic or acquired drug resistance, which results in disease recurrence and metastasis. However, the mechanisms underlying this drug resistance are unknown. To study the molecular mechanisms underlying the invasive and metastatic activities of drug-resistant cancer cells, we generated a doxorubicin-resistant MCF-7 breast cancer cell line (MCF-7/DOX). We used MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assays, flow cytometry assays, DNA fragmentation assays, Western blot analysis, cell invasion assays, small interfering RNA (siRNA) transfection, reverse transcription-polymerase chain reaction, experimental lung metastasis models, and gelatin and fibrinogen/plasminogen zymography to study the molecular mechanism of metastatic activities in MCF-7/DOX cells. We found that MCF-7/DOX acquired invasive activities. In addition, Western blot analysis showed increased expression of epidermal growth factor receptor (EGFR) and Cox-2 in MCF-7/DOX cells. Inhibition of Cox-2, phosphoinositide 3-kinase (PI3K)/Akt, or mitogen-activated protein kinase (MAPK) pathways effectively inhibited the invasive activities of MCF-7/DOX cells. Gelatin and fibrinogen/plasminogen zymography analysis showed that the enzymatic activities of matrix metalloproteinase-2 (MMP-2), MMP-9, and urokinase-type plasminogen activator were markedly higher in MCF-7/DOX cells than in the MCF-7 cells. In vitro invasion assays and mouse models of lung metastasis demonstrated that MCF-7/DOX cells acquired invasive abilities. Using siRNAs and agonists specific for prostaglandin E (EP) receptors, we found that EP1 and EP3 played important roles in the invasiveness of MCF-7/DOX cells. We found that the invasive activity of MCF-7/DOX cells is mediated by Cox-2, which is induced by the EGFR-activated PI3K/Akt and MAPK pathways. In addition, EP1 and EP3 are important in

  15. Fuel cell development for transportation: Catalyst development

    Energy Technology Data Exchange (ETDEWEB)

    Doddapaneni, N. [Sandia National Lab., Albuquerque, NM (United States)

    1996-04-01

    Fuel cells are being considered as alternate power sources for transportation and stationary applications. With proton exchange membrane (PEM) fuel cells the fuel crossover to cathodes causes severe thermal management and cell voltage drop due to oxidation of fuel at the platinized cathodes. The main goal of this project was to design, synthesize, and evaluate stable and inexpensive transition metal macrocyclic catalysts for the reduction of oxygen and be electrochemically inert towards anode fuels such as hydrogen and methanol.

  16. 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.

  17. Novel drug-resistance mechanisms of pemetrexed-treated non-small cell lung cancer.

    Science.gov (United States)

    Tanino, Ryosuke; Tsubata, Yukari; Harashima, Nanae; Harada, Mamoru; Isobe, Takeshi

    2018-03-30

    Pemetrexed (PEM) improves the overall survival of patients with advanced non-small cell lung cancer (NSCLC) when administered as maintenance therapy. However, PEM resistance often appears during the therapy. Although thymidylate synthase is known to be responsible for PEM resistance, no other mechanisms have been investigated in detail. In this study, we explored new drug resistance mechanisms of PEM-treated NSCLC using two combinations of parental and PEM-resistant NSCLC cell lines from PC-9 and A549. PEM increased the apoptosis cells in parental PC-9 and the senescent cells in parental A549. However, such changes were not observed in the respective PEM-resistant cell lines. Quantitative RT-PCR analysis revealed that, besides an increased gene expression of thymidylate synthase in PEM-resistant PC-9 cells, the solute carrier family 19 member1 ( SLC19A1) gene expression was markedly decreased in PEM-resistant A549 cells. The siRNA-mediated knockdown of SLC19A1 endowed the parental cell lines with PEM resistance. Conversely, PEM-resistant PC-9 cells carrying an epidermal growth factor receptor (EGFR) mutation acquired resistance to a tyrosine kinase inhibitor erlotinib. Although erlotinib can inhibit the phosphorylation of EGFR and Erk, it is unable to suppress the phosphorylation of Akt in PEM-resistant PC-9 cells. Additionally, PEM-resistant PC-9 cells were less sensitive to the PI3K inhibitor LY294002 than parental PC-9 cells. These results indicate that SLC19A1 negatively regulates PEM resistance in NSCLC, and that EGFR-tyrosine-kinase-inhibitor resistance was acquired with PEM resistance through Akt activation in NSCLC harboring EGFR mutations.

  18. Methodology of Establishing and Identifying NCI-H2228/Crizotinib-resistant Cell Lines In Vitro

    Directory of Open Access Journals (Sweden)

    Di WU

    2015-06-01

    Full Text Available Background and objective The mechanisms of small molecule targeting drug resistance and ways to overcome resistance are now both urgent need to improve the clinical efficacy. This study aimed to investigate the feasibility of using different methods to establish the crizotinib-resistant non-small cell lung cancer NCI-H2228/Crizotinib cell lines and to clarify the mechanisms of resistance to small molecule targeting drug, thus providing experimental and theoretical bases for further studies to overcome the mechanisms of Crizotinib resistance. Methods The study utilized stepwise increase of drug concentrations and chemical mutagen to induce Crizotinib-resistant NCI-H2228 cells. The drug 50% inhibitory concentration (IC50 values of parental and resistant cells and the population doubling time were determined by MTT assay. The echinoderm microtubule-associated protein-like 4-anaplastic lymphoma kinase (EML4-ALK expression was evaluated by RT-PCR and Western blot. Full-length sequencing method was used to compare the EML4-ALK genes in the parent and drug-resistant cells and analyze the mechanisms of drug resistance. Results The method of gradually increasing drug concentration to induce Crizotinib-resistant NCI-H2228 cells was time-consuming because the cell growth recovery was extremely slow. Thus, this method was considered invalid. However, chemical mutagen ENU can effectively induce NCI-H2228 cells resistant to crizotinib in a short time [IC50]= (3.810±1.100 μmol/L, P=0.002,9 vs parental cells]. Furthermore, the gene mutation frequency of EML4-ALK in the resistant cells was significantly higher than that in the parent cells. Conclusion Chemical mutagen-induced cell resistance was easily operated and had effectively shortened the experimental process. Preliminary technical methods and experimental evidence for in-depth study of drug resistance mechanisms and approaches to overcome the targeted drug resistance were also provided.

  19. Developing Inset Resistant Maize Varieties for Food Security in Kenya

    International Nuclear Information System (INIS)

    Mugo, S.

    2002-01-01

    The Insect Resistant Maize for Africa (IRMA) project aims at increasing maize production and food security through development and deployment of stem borer resistant maize germplasm developed using conventional and through biotechnology methods such as Bt maize. Bt maize offers farmers an effective and practical option for controlling stem borers. It was recognized that the development and routine use of Bt maize will require addressing relevant bio-safety, environmental, and community concerns and research and information gathering activities are in place to address these concerns and research and information gathering activities are in place to address these concerns. Suitable Bt gene have been acquired or synthesized and back-crossed into elite maize germplasm at CIMMYT-Mexico, and the effective Cry-proteins against the major maize stem borers in Kenya were identified to better target pests. Stem borer resistant maize germplasm is being developed through conventional breeding, using locally adapted and exotic germplasm. for safe and effective deployment of Bt maize,studies on its impacts on target and non-target arthropods as well as studies on the effects of Bt maize on key non-target arthropods as well as studies on gene flow are underway. Insect resistance management strategies are being developed through quantifying the effectiveness, ???. Socioeconomic impact studies are revealing factors in the society that may influence the adoption of Bt maize in Kenya. Also, baseline data, essential for the monitoring and evaluation of the Bt maize technology in Kenya, has been established. Technology transfer and capacity building, creating awareness and communications have received attention in the project. This paper describes the major research activities as they relate to development of the stem bore resistant maize germplasm

  20. Development of debris-resistant bottom end piece

    International Nuclear Information System (INIS)

    Sohn, Dong Seong; Lee, Jae Kyung; Hwang, Dae Hyun; Yim, Jung Sik; Song, Kee Nam; Oh, Dong Seok; Im, Hyun Tae

    1993-01-01

    Debris-related fuel failures has been identified to be one of the major causes of fuel failures recently occured in nuclear power plants. In order to reduce the possibility of debris-related fuel failures, it is necessary to prevent the debris from reaching to fuel rods. In this regard, it is important to develop Debris-Resistant Bottom End Piece. (Author)

  1. Importance and implications of antibiotic resistance development in ...

    African Journals Online (AJOL)

    Antibiotic resistance (ABR) is regarded as one of today's major global health challenges. The development of ABR in nature is a complex phenomenon with many influencing factors, of which the farming industry is labelled a significant contributor. The transfer of ABR to humans, which usually occurs via the food chain, is of ...

  2. Development of a resistance management strategy for ixodid ticks ...

    African Journals Online (AJOL)

    The strategy developed for managing resistance in ticks with the acaricidal products on the market was based on mode of action of the active ingredients. The strategy requires the rotaional use of the acaricidal products in ways that reduces the selection pressure of active ingredients of same chemistry on the target-site in ...

  3. Phalaris minor control, resistance development and strategies for ...

    African Journals Online (AJOL)

    Administrator

    2011-09-26

    Sep 26, 2011 ... High production of wheat is associated with its continuous use. But this practice enhances the development of resistant biotypes of P. minor. Different management approaches like preference of mechanical weeding over chemical weed control, integration of competitive varietal selection, crop rotation and ...

  4. Progress in developing ultrathin solar cell blanket technology

    Science.gov (United States)

    Patterson, R. E.; Mesch, H. G.; Scott-Monck, J.

    1984-01-01

    A program was conducted to develop technologies for welding interconnects to three types of 50-micron-thick, 2 by 2-cm solar cells. Parallel-gap resistance welding was used for interconnect attachment. Weld schedules were independently developed for each of the three cell types and were coincidentally identical. Six 48-cell modules were assembled with 50-micron (nominal) thick cells, frosted fused-silica covers, silver-plated Invar interconnectors, and four different substrate designs. Three modules (one for each cell type) have single-layer Kapton (50-micron-thick) substrates. The other three modules each have a different substrate (Kapton-Kevlar-Kapton, Kapton-graphite-Kapton, and Kapton-graphite-aluminum honeycomb-graphite). All six modules were subjected to 4112 thermal cycles from -175 to 65 C (corresponding to over 40 years of simulated geosynchronous orbit thermal cycling) and experienced only negligible electrical degradation (1.1 percent average of six 48-cell modules).

  5. MicroRNA profiling of cisplatin-resistant oral squamous cell carcinoma cell lines enriched with cancer-stem-cell-like and epithelial-mesenchymal transition-type features

    Science.gov (United States)

    Ghosh, Ruma Dey; Ghuwalewala, Sangeeta; Das, Pijush; Mandloi, Sapan; Alam, Sk Kayum; Chakraborty, Jayanta; Sarkar, Sajal; Chakrabarti, Saikat; Panda, Chinmoy Kumar; Roychoudhury, Susanta

    2016-01-01

    Oral cancer is of major public health problem in India. Current investigation was aimed to identify the specific deregulated miRNAs which are responsible for development of resistance phenotype through regulating their resistance related target gene expression in oral squamous cell carcinoma (OSCC). Cisplatin-resistant OSCC cell lines were developed from their parental human OSCC cell lines and subsequently characterised. The resistant cells exhibited enhanced proliferative, clonogenic capacity with significant up-regulation of P-glycoprotein (ABCB1), c-Myc, survivin, β-catenin and a putative cancer-stem-like signature with increased expression of CD44, whereas the loss of E-cadherin signifies induced EMT phenotype. A comparative analysis of miRNA expression profiling in parental and cisplatin-resistant OSCC cell lines for a selected sets (deregulated miRNAs in head and neck cancer) revealed resistance specific signature. Moreover, we observed similar expression pattern for these resistance specific signature miRNAs in neoadjuvant chemotherapy treated and recurrent tumours compared to those with newly diagnosed primary tumours in patients with OSCC. All these results revealed that these miRNAs play an important role in the development of cisplatin-resistance mainly through modulating cancer stem-cell-like and EMT-type properties in OSCC. PMID:27045798

  6. Fitness Impaired Drug Resistant HIV-1 Is Not Compromised in Cell-to-Cell Transmission or Establishment of and Reactivation from Latency

    Directory of Open Access Journals (Sweden)

    Sophie M. Bastarache

    2014-09-01

    Full Text Available Both the presence of latently infected cells and cell-to-cell viral transmission are means whereby HIV can partially evade the inhibitory activities of antiretroviral drugs. The clinical use of a novel integrase inhibitor, dolutegravir (DTG, has established hope that this compound may limit HIV persistence, since no treatment-naïve patient treated with DTG has yet developed resistance against this drug, even though a R263K substitution in integrase confers low-level resistance to this drug in tissue culture. Here, we have studied the impact of R263K on HIV replication capacity and the ability of HIV to establish or be reactivated from latency and/or spread through cell-to-cell transmission. We affirm that DTG-resistant viruses have diminished capacity to replicate and establish infection. However, DTG-resistant viruses were efficiently transmitted via cell-to-cell contacts, and were as likely to establish and be reactivated from latent infection as wildtype viruses. Both cell-to-cell transmission of HIV and the establishment of and reemergence from latency are important for the establishment and maintenance of viral reservoirs. Since the DTG and other drug-resistant viruses studied here do not seem to have been impaired in regard to these activities, studies should be undertaken to characterize HIV reservoirs in patients who have been treated with DTG.

  7. The involvement of Bcl-2 family proteins in AKT-regulated cell survival in cisplatin resistant epithelial ovarian cancer.

    Science.gov (United States)

    Dai, Yan; Jin, Shiguang; Li, Xueping; Wang, Daxin

    2017-01-03

    Many studies involving patients with cisplatin-resistant ovarian cancer have shown that AKT activation leads to inhibition of apoptosis. The aim of this study was to examine the potential involvement of the Bcl-2 family proteins in AKT-regulated cell survival in response to cisplatin treatment. Cisplatin-sensitive (PEO1) and cisplatin-resistant (PEO4) cells were taken from ascites of patients with ovarian cancer before cisplatin treatment and after development of chemoresistance. It was found that cisplatin treatment activated the AKT signaling pathway and promoted cell proliferation in cisplatin-resistant EOC cells. When AKT was transfected into nucleus of cisplatin-resistant ovarian cancer cells, DNA-PK was phosphorylated at S473. The activated AKT (pAKT-S473) in these cells inhibited the death signal induced by cisplatin thereby inhibiting cisplatin-mediated apoptosis. Results from this study showed that the combination of cisplatin, DNA-PK inhibitor NU7441, and AKT inhibitor TCN can overcome drug resistance, increase apoptosis, and re-sensitize PEO4 cells to cisplatin treatment. A decrease in apoptotic activity was seen in PEO4 cells when Bad was downregulated by siRNA, which indicated that Bad promotes apoptosis in PEO4 cells. Use of the Bcl-2 inhibitor ABT-737 showed that ABT-737 binds to Bcl-2 but not Mcl-1 and releases Bax/Bak which leads to cell apoptosis. The combination of ABT-737 and cisplatin leads to a significant increase in the death of PEO1 and PEO4 cells. All together, these results indicate that Bcl-2 family proteins are regulators of drug resistance. The combination of cisplatin and Bcl-2 family protein inhibitor could be a strategy for the treatment of cisplatin-resistant ovarian cancer.

  8. Sensitivity to ionizing radiation and chemotherapeutic agents in gemcitabine-resistant human tumor cell lines

    NARCIS (Netherlands)

    van Bree, Chris; Castro Kreder, Natasja; Loves, Willem J. P.; Franken, Nicolaas A. P.; Peters, Godefridus J.; Haveman, Jaap

    2002-01-01

    Purpose: To determine cross-resistance to anti-tumor treatments in 2',2'difluorodeoxycytidine (dFdC, gemcitabine)-resistant human tumor cells. Methods and Materials: Human lung carcinoma cells SW-1573 (SWp) were made resistant to dFdC (SWg). Sensitivity to cisplatin (cDDP), paclitaxel,

  9. Generation and characterisation of cisplatin-resistant non-small cell lung cancer cell lines displaying a stem-like signature.

    Directory of Open Access Journals (Sweden)

    Martin P Barr

    Full Text Available Inherent and acquired cisplatin resistance reduces the effectiveness of this agent in the management of non-small cell lung cancer (NSCLC. Understanding the molecular mechanisms underlying this process may result in the development of novel agents to enhance the sensitivity of cisplatin.An isogenic model of cisplatin resistance was generated in a panel of NSCLC cell lines (A549, SKMES-1, MOR, H460. Over a period of twelve months, cisplatin resistant (CisR cell lines were derived from original, age-matched parent cells (PT and subsequently characterized. Proliferation (MTT and clonogenic survival assays (crystal violet were carried out between PT and CisR cells. Cellular response to cisplatin-induced apoptosis and cell cycle distribution were examined by FACS analysis. A panel of cancer stem cell and pluripotent markers was examined in addition to the EMT proteins, c-Met and β-catenin. Cisplatin-DNA adduct formation, DNA damage (γH2AX and cellular platinum uptake (ICP-MS was also assessed.Characterisation studies demonstrated a decreased proliferative capacity of lung tumour cells in response to cisplatin, increased resistance to cisplatin-induced cell death, accumulation of resistant cells in the G0/G1 phase of the cell cycle and enhanced clonogenic survival ability. Moreover, resistant cells displayed a putative stem-like signature with increased expression of CD133+/CD44+cells and increased ALDH activity relative to their corresponding parental cells. The stem cell markers, Nanog, Oct-4 and SOX-2, were significantly upregulated as were the EMT markers, c-Met and β-catenin. While resistant sublines demonstrated decreased uptake of cisplatin in response to treatment, reduced cisplatin-GpG DNA adduct formation and significantly decreased γH2AX foci were observed compared to parental cell lines.Our results identified cisplatin resistant subpopulations of NSCLC cells with a putative stem-like signature, providing a further understanding of the

  10. Generation and Characterisation of Cisplatin-Resistant Non-Small Cell Lung Cancer Cell Lines Displaying a Stem-Like Signature

    Science.gov (United States)

    Barr, Martin P.; Gray, Steven G.; Hoffmann, Andreas C.; Hilger, Ralf A.; Thomale, Juergen; O’Flaherty, John D.; Fennell, Dean A.; Richard, Derek; O’Leary, John J.; O’Byrne, Kenneth J.

    2013-01-01

    Introduction Inherent and acquired cisplatin resistance reduces the effectiveness of this agent in the management of non-small cell lung cancer (NSCLC). Understanding the molecular mechanisms underlying this process may result in the development of novel agents to enhance the sensitivity of cisplatin. Methods An isogenic model of cisplatin resistance was generated in a panel of NSCLC cell lines (A549, SKMES-1, MOR, H460). Over a period of twelve months, cisplatin resistant (CisR) cell lines were derived from original, age-matched parent cells (PT) and subsequently characterized. Proliferation (MTT) and clonogenic survival assays (crystal violet) were carried out between PT and CisR cells. Cellular response to cisplatin-induced apoptosis and cell cycle distribution were examined by FACS analysis. A panel of cancer stem cell and pluripotent markers was examined in addition to the EMT proteins, c-Met and β-catenin. Cisplatin-DNA adduct formation, DNA damage (γH2AX) and cellular platinum uptake (ICP-MS) was also assessed. Results Characterisation studies demonstrated a decreased proliferative capacity of lung tumour cells in response to cisplatin, increased resistance to cisplatin-induced cell death, accumulation of resistant cells in the G0/G1 phase of the cell cycle and enhanced clonogenic survival ability. Moreover, resistant cells displayed a putative stem-like signature with increased expression of CD133+/CD44+cells and increased ALDH activity relative to their corresponding parental cells. The stem cell markers, Nanog, Oct-4 and SOX-2, were significantly upregulated as were the EMT markers, c-Met and β-catenin. While resistant sublines demonstrated decreased uptake of cisplatin in response to treatment, reduced cisplatin-GpG DNA adduct formation and significantly decreased γH2AX foci were observed compared to parental cell lines. Conclusion Our results identified cisplatin resistant subpopulations of NSCLC cells with a putative stem-like signature, providing

  11. WNT4 mediates estrogen receptor signaling and endocrine resistance in invasive lobular carcinoma cell lines.

    Science.gov (United States)

    Sikora, Matthew J; Jacobsen, Britta M; Levine, Kevin; Chen, Jian; Davidson, Nancy E; Lee, Adrian V; Alexander, Caroline M; Oesterreich, Steffi

    2016-09-20

    Invasive lobular carcinoma (ILC) of the breast typically presents with clinical biomarkers consistent with a favorable response to endocrine therapies, and over 90 % of ILC cases express the estrogen receptor (ER). However, a subset of ILC cases may be resistant to endocrine therapies, suggesting that ER biology is unique in ILC. Using ILC cell lines, we previously demonstrated that ER regulates a distinct gene expression program in ILC cells, and we hypothesized that these ER-driven pathways modulate the endocrine response in ILC. One potential novel pathway is via the Wnt ligand WNT4, a critical signaling molecule in mammary gland development regulated by the progesterone receptor. The ILC cell lines MDA-MB-134-VI, SUM44PE, and BCK4 were used to assess WNT4 gene expression and regulation, as well as the role of WNT4 in estrogen-regulated proliferation. To assess these mechanisms in the context of endocrine resistance, we developed novel ILC endocrine-resistant long-term estrogen-deprived (ILC-LTED) models. ILC and ILC-LTED cell lines were used to identify upstream regulators and downstream signaling effectors of WNT4 signaling. ILC cells co-opted WNT4 signaling by placing it under direct ER control. We observed that ER regulation of WNT4 correlated with use of an ER binding site at the WNT4 locus, specifically in ILC cells. Further, WNT4 was required for endocrine response in ILC cells, as WNT4 knockdown blocked estrogen-induced proliferation. ILC-LTED cells remained dependent on WNT4 for proliferation, by either maintaining ER function and WNT4 regulation or uncoupling WNT4 from ER and upregulating WNT4 expression. In the latter case, WNT4 expression was driven by activated nuclear factor kappa-B signaling in ILC-LTED cells. In ILC and ILC-LTED cells, WNT4 led to suppression of CDKN1A/p21, which is critical for ILC cell proliferation. CDKN1A knockdown partially reversed the effects of WNT4 knockdown. WNT4 drives a novel signaling pathway in ILC cells, with a

  12. Cell-penetrating, guanidinium-rich molecular transporters for overcoming efflux-mediated multidrug resistance.

    Science.gov (United States)

    Vargas, Jessica R; Stanzl, Erika Geihe; Teng, Nelson N H; Wender, Paul A

    2014-08-04

    Multidrug resistance (MDR) is a major cause of chemotherapy failure in the clinic. Drugs that were once effective against naïve disease subsequently prove ineffective against recurrent disease, which often exhibits an MDR phenotype. MDR can be attributed to many factors; often dominating among these is the ability of a cell to suppress or block drug entry through upregulation of membrane-bound drug efflux pumps. Efflux pumps exhibit polyspecificity, recognizing and exporting many different types of drugs, especially those whose lipophilic nature contributes to residence in the membrane. We have developed a general strategy to overcome efflux-based resistance. This strategy involves conjugating a known drug that succumbs to efflux-mediated resistance to a cell-penetrating molecular transporter, specifically, the cell-penetrating peptide (CPP), d-octaarginine. The resultant conjugates are discrete single entities (not particle mixtures) and highly water-soluble. They rapidly enter cells, are not substrates for efflux pumps, and release the free drug only after cellular entry at a rate controlled by linker design and favored by target cell chemistry. This general strategy can be applied to many classes of drugs and allows for an exceptionally rapid advance to clinical testing, especially of drugs that succumb to resistance. The efficacy of this strategy has been successfully demonstrated with Taxol in cellular and animal models of resistant cancer and with ex vivo samples from patients with ovarian cancer. Next generation efforts in this area will involve the extension of this strategy to other chemotherapeutics and other MDR-susceptible diseases.

  13. Development and activation of cyanide-resistant respiration in the yeast Yarrowia lipolytica.

    Science.gov (United States)

    Medentsev, A G; Akimenko, V K

    1999-08-01

    Changes in respiratory activity and in the contents of adenine nucleotides (ATP, ADP, AMP) were studied in cells of the yeast Yarrowia lipolytica during the development of cyanide-resistant respiration. The transition of the yeast from the logarithmic to the stationary growth phase due to exhaustion of glucose was associated with decreased endogenous respiration and with the activation of a cyanide-resistant oxidase. Cyanide activated cell respiration during the stationary growth phase. The cyanide-resistant respiration was inhibited by benzohydroxamic acid (BHA), an inhibitor of the alternative oxidase. In the absence of cyanide, BHA had no effect on the cells which had the cyanide-resistant oxidase. This indicates that the cells do not use the alternative pathway in vivo. The decreased endogenous respiration of the cells was accompanied by decreased contents of adenine nucleotides. Addition of cyanide resulted in a sharp decrease in the content of ATP, in a twofold increase in the content of ADP, and in a fivefold increase in the content of AMP. In the absence of cyanide, BHA had virtually no effect on the contents of adenine nucleotides. The decreased rate of oxygen consumption during the transition of the cells to the stationary growth phase was caused by the decreased activity of the main cytochrome-containing respiratory chain (2,4-dinitrophenol (DNP) stimulated respiration). The alternative oxidase was synthesized in the cell but was inactive. Cyanide stimulated respiration due to activation of the alternative oxidase via the AMP produced. The decrease in the cell content of ATP is suggested to be a factor inducing the synthesis of the alternative oxidase.

  14. EGFR over-expression and activation in high HER2, ER negative breast cancer cell line induces trastuzumab resistance.

    Science.gov (United States)

    Dua, Rajiv; Zhang, Jianhuan; Nhonthachit, Phets; Penuel, Elicia; Petropoulos, Chris; Parry, Gordon

    2010-08-01

    HER2 is gene amplified or over-expressed in 20-25% of breast cancers resulting in elevated HER2 activation. Trastuzumab (Herceptin), a humanized monoclonal antibody, targets activated HER2 and is clinically effective in HER2-over-expressing breast cancers. However, despite prolonged survival, treated breast cancer patients develop resistance. Resistance to trastuzumab occurs upon inactivation of HER2 regulatory proteins or upon up-regulation of alternative receptors. In particular, elevated levels of EGFR, present in estrogen receptor (ER) positive, trastuzumab-resistant BT-474 xenografts caused, a trastuzumab-resistant phenotype (Ritter et al. Clin Cancer Res 13:4909-4919, 2007). However, the role of EGFR in acquired trastuzumab resistance in ER negative cell models is not well defined. In this study, SKBR3 cell line clones expressing EGFR were generated to examine the role of EGFR over-expression on trastuzumab sensitivity in an, ER-negative breast carcinoma cell line. A stable clone, SKBR3/EGFR (clone 4) expressing moderate levels of EGFR remained sensitive to trastuzumab, whereas a stable clone, SKBR3/EGFR (clone 5) expressing high levels of EGFR, became resistant to trastuzumab. Depletion of EGFR by EGFR small-interfering RNAs in the SKBR3/EGFR (clone 5) reversed trastuzumab resistance. However, the SKBR3/EGFR (clone 5) cell line remained sensitive to lapatinib, an EGFR/HER2 inhibitor. Biochemical analysis using co-immunoprecipitation and proximity-based quantitative VeraTag assays demonstrated that high levels of EGFR phosphorylation, EGFR/EGFR homo-dimerization, and EGFR/HER2 hetero-dimerization were present in the trastuzumab-resistant cells. We conclude that EGFR over-expression can mediate trastuzumab resistance in both ER positive and ER negative cells and hypothesize that a threshold level of EGFR, in the absence of autocrine ligand production, is required to induce the resistant phenotype.

  15. Children’s development through emergent patterns of resistance

    DEFF Research Database (Denmark)

    Hviid, Pernille; Villadsen, Jakob Waag

    From an existential perspective development is not something occurring bypassing the developing child. Children engage with the world and through this ongoing engagement priorities emerge. Hence, the child’s engagement in and with the world points back to the child, to what the child is and what...... resist the engagements of children? How does the introduction of global learning efforts and goals affect the child, not just as a young learner but as a developing person? Our empirical work focuses on interaction between Danish preschool children and their pedagogues. We will investigate...... these challenges and potentials to children’s development with a specific focus on resistance in the personal spheres of experiences....

  16. Capsaicin and Piperine Can Overcome Multidrug Resistance in Cancer Cells to Doxorubicin

    Directory of Open Access Journals (Sweden)

    Hanmei Li

    2018-03-01

    Full Text Available Background: Multidrug resistance (MDR can develop in cancer cells after treatment with anticancer drugs, mainly due to the overexpression of the ATP-binding cassette (ABC transporters. We analyzed the ability of two pungent-tasting alkaloids—capsaicin and piperine from Capsicum frutescens and Piper nigrum, respectively—to reverse multidrug resistance in the cancer cell lines Caco-2 and CEM/ADR 5000, which overexpress P-glycoprotein (P-gp and other ABC transporters. Methods: The MTT assay was first used to determine the cytotoxicity of doxorubicin, the alkaloids, and digitonin alone, and then their combinations. Furthermore, rhodamine (Rho 123 and calcein-AM were used to detect the effects of alkaloids on the activity of P-gp. Results: Capsaicin and piperine synergistically enhanced the cytotoxicity of doxorubicin in Caco-2 and CEM/ADR 5000 cells. Furthermore, capsaicin and piperine increased the intracellular accumulation of the fluorescent P-glycoprotein (P-gp substrates rhodamine and calcein and inhibited their efflux from the MDR cell lines. Conclusion: Our study has demonstrated that capsaicin and piperine are P-gp substrates and have potential chemosensitizing activity, which might be interesting for the development of novel modulators of multidrug resistance.

  17. Acyclovir-resistant herpes simplex virus 1 infection early after allogeneic hematopoietic stem cell transplantation with T-cell depletion.

    Science.gov (United States)

    Akahoshi, Yu; Kanda, Junya; Ohno, Ayumu; Komiya, Yusuke; Gomyo, Ayumi; Hayakawa, Jin; Harada, Naonori; Kameda, Kazuaki; Ugai, Tomotaka; Wada, Hidenori; Ishihara, Yuko; Kawamura, Koji; Sakamoto, Kana; Sato, Miki; Terasako-Saito, Kiriko; Kimura, Shun-Ichi; Kikuchi, Misato; Nakasone, Hideki; Kako, Shinichi; Shiraki, Kimiyasu; Kanda, Yoshinobu

    2017-07-01

    We previously reported that oral low-dose acyclovir (200 mg/day) for the prevention of herpes simplex virus (HSV) infections after allogenic hematopoietic stem cell transplantation (HSCT) is effective without the emergence of acyclovir-resistant HSV infections. However, HSV infections are of significant concern because the number of allogeneic HSCT with T-cell depletion, which is a risk factor of the emergence of drug-resistant HSV infections, has been increasing. We experienced a 25-year-old female who received allogenic HSCT from an unrelated donor with 1-antigen mismatch using anti-thymocyte globulin. Despite acyclovir prophylaxis (200 mg/day), she developed the right palatal ulcer that was positive for HSV-1 specific antigen by fluorescent antibody on day 20 and developed new hypoglossal and tongue ulcers on day 33. Replacement of acyclovir with foscarnet improved her ulcers. We isolated 2 acyclovir-resistant and foscarnet-sensitive strains from the right palatal and hypoglossal ulcers, which had the same frame shift mutation in the thymidine kinase genes. The rate of proliferation of the isolate from the hypoglossal ulcer was faster than that from the right palatal ulcer in the plaque reduction assay. HSV strains that acquired acyclovir-resistant mutations at the right palatal ulcer with larger plaque might spread to the hypoglossal ulcer as the secondary site of infection because of better growth property. Second-line antiviral agents should be considered when we suspect treatment failure of HSV infection, especially in HSCT with T-cell depletion. Further studies are required whether low-dose acyclovir prophylaxis leads to the emergence of virological resistance. Copyright © 2017 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

  18. Cutaneous squamous cell carcinoma in lupus vulgaris caused by drug resistant Mycobacterium tuberculosis

    Directory of Open Access Journals (Sweden)

    Muthu S Kumaran

    2017-01-01

    Full Text Available Tuberculosis (TB is still a major public health problem in the world, with many factors contributing to this burden, including poor living conditions, overcrowding, poverty, malnutrition, illiteracy, and rapid spread of human immunodeficiency virus infection. Cutaneous tuberculosis is a less common form of extrapulmonary tuberculosis, and in this paucibacillary form the diagnosis depends on histopathology, tuberculin positivity, and response to treatment. The diagnosis is even more difficult in cases with drug resistant Mycobacterium tuberculosis due to lack of awareness and lack of facilities to diagnose drug resistant tuberculosis. In this article, we describe an unusual case of multidrug resistant lupus vulgaris (LV, in a 34-year-old male who responded to anti-tubercular treatment (ATT initially, but developed recurrent disease which failed to respond to standard four-drug ATT; subsequently, tissue culture showed growth of multidrug resistant M. tuberculosis. Subsequently, he also developed cutaneous squamous cell carcinoma. This article aims to exemplify a grave complication that can occur in long-standing case of LV, the limitations faced by clinicians in developing countries where tuberculosis is endemic, and classical methods of proving drug resistance are generally unavailable or fail.

  19. Cutaneous Squamous Cell Carcinoma in Lupus Vulgaris Caused by Drug Resistant Mycobacterium Tuberculosis.

    Science.gov (United States)

    Kumaran, Muthu S; Narang, Tarun; Jitendriya, Madhukara; Tirumale, Rajalakshmi; Manjunath, Suraj; Savio, Jayanthi

    2017-01-01

    Tuberculosis (TB) is still a major public health problem in the world, with many factors contributing to this burden, including poor living conditions, overcrowding, poverty, malnutrition, illiteracy, and rapid spread of human immunodeficiency virus infection. Cutaneous tuberculosis is a less common form of extrapulmonary tuberculosis, and in this paucibacillary form the diagnosis depends on histopathology, tuberculin positivity, and response to treatment. The diagnosis is even more difficult in cases with drug resistant Mycobacterium tuberculosis due to lack of awareness and lack of facilities to diagnose drug resistant tuberculosis. In this article, we describe an unusual case of multidrug resistant lupus vulgaris (LV), in a 34-year-old male who responded to anti-tubercular treatment (ATT) initially, but developed recurrent disease which failed to respond to standard four-drug ATT; subsequently, tissue culture showed growth of multidrug resistant M. tuberculosis . Subsequently, he also developed cutaneous squamous cell carcinoma. This article aims to exemplify a grave complication that can occur in long-standing case of LV, the limitations faced by clinicians in developing countries where tuberculosis is endemic, and classical methods of proving drug resistance are generally unavailable or fail.

  20. Fludarabine-mediated circumvention of cytarabine resistance is associated with fludarabine triphosphate accumulation in cytarabine-resistant leukemic cells.

    Science.gov (United States)

    Yamamoto, Shuji; Yamauchi, Takahiro; Kawai, Yasukazu; Takemura, Haruyuki; Kishi, Shinji; Yoshida, Akira; Urasaki, Yoshimasa; Iwasaki, Hiromichi; Ueda, Takanori

    2007-02-01

    The combination of cytarabine (ara-C) with fludarabine is a common approach to treating resistant acute myeloid leukemia. Success depends on a fludarabine triphosphate (F-ara-ATP)-mediated increase in the active intracellular metabolite of ara-C, ara-C 5'-triphosphate (ara-CTP). Therapy-resistant leukemia may exhibit ara-C resistance, the mechanisms of which might induce cross-resistance to fludarabine with reduced F-ara-ATP formation. The present study evaluated the effect of combining ara-C and fludarabine on ara-C-resistant leukemic cells in vitro. Two variant cell lines (R1 and R2) were 8-fold and 10-fold more ara-C resistant, respectively, than the parental HL-60 cells. Reduced deoxycytidine kinase activity was demonstrated in R1 and R2 cells, and R2 cells also showed an increase in cytosolic 5'-nucleotidase II activity. Compared with HL-60 cells, R1 and R2 cells produced smaller amounts of ara-CTP. Both variants accumulated less F-ara-ATP than HL-60 cells and showed cross-resistance to fludarabine nucleoside (F-ara-A). R2 cells, however, accumulated much smaller amounts of F-ara-ATP and were more F-ara-A resistant than R1 cells. In HL-60 and R1 cells, F-ara-A pretreatment followed by ara-C incubation produced F-ara-ATP concentrations sufficient for augmenting ara-CTP production, thereby enhancing ara-C cytotoxicity. No potentiation was observed in R2 cells. Nucleotidase might preferentially degrade F-ara-A monophosphate over ara-C monophosphate, leading to reduced F-ara-ATP production and thereby compromising the F-ara-A-mediated potentiation of ara-C cytotoxicity in R2 cells. Thus, F-ara-A-mediated enhancement of ara-C cytotoxicity depended on F-ara-ATP accumulation in ara-C-resistant leukemic cells but ultimately was associated with the mechanism of ara-C resistance.

  1. Development of chloride-resisting concrete using fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Dhir, R.K.; Jones, M.R. [University of Dundee, Dundee (United Kingdom). Dept. of Civil Engineering, Concrete Technology Unit

    1999-01-01

    This paper describes how low-lime fly ash can be used to develop chloride-resistant concrete by improving both its physical resistance to the ingress of chloride and binding capacity of these ions in the cover zone. This includes optimizing the fly ash content, reducing the water/binder ratio of the concrete, processing fly ash to improve its particulate characteristics and, finally, using ternary blends with silica fume or metakaolin. This last method is shown to provide the highest degree of chloride resistance. A tentative classification of chloride-bearing environments together with recommendations for the specification of concrete for structures exposed to these environments, is proposed. 15 refs., 5 figs., 4 tabs.

  2. Abuse resistant high rate lithium/thionyl chloride cells

    Energy Technology Data Exchange (ETDEWEB)

    Surprenant, J.; Snuggerud, D.

    1982-08-01

    A compact, disc shaped lithium/thionyl chloride cell has been developed by Altus Corporation. The cell has a 6 Amphr capacity and is capable of high rate discharge at high voltage. Discharge data is presented over the range of 0.07 to 1.1 Amperes. The cell is operable over the temperature range of -40/sup 0/C to +70/sup 0/C, and has a 10 year shelf life at 20/sup 0/C. Safety features allow the cells to withstand fire, puncture, shock, spin, forced discharge or forced charge without dangerous reactions.

  3. Abuse resistant high rate lithium/thionyl chloride cells

    Science.gov (United States)

    Surprenant, J.; Snuggerud, D.

    A compact, disk shaped lithium/thionyl chloride cell has been developed. The cell has a 6 Amphr capacity and is capable of high rate discharge at high voltage. Discharge data are presented over the range of 0.07 to 1.1 amperes. The cell is operable over the temperature range of -40 C to +70 C, and has a 10 year shelf life at 20 C. Safety features allow the cells to withstand fire, puncture, shock, spin, forced discharge or forced charge without dangerous reactions.

  4. Alteration of miRNA expression in a sulfur mustard resistant cell line.

    Science.gov (United States)

    Rothmiller, Simone; Wolf, Markus; Worek, Franz; Steinritz, Dirk; Thiermann, Horst; Schmidt, Annette

    2017-08-18

    MicroRNAs (miRNAs) are responsible for post-transcriptional control of protein expression. Numerous miRNAs have been identified to be responsible for the resistance of tumor cells to cytostatic drugs. Possibly, the same miRNAs also play a role in the sulfur mustard (SM)-resistance of the keratinocyte cell line HaCaT/SM as alkylating cytostatics exhibit similar cytotoxic effects as SM. Basal expression levels of 1920 miRNAs in total were analyzed in HaCaT/SM compared to the origin human keratinocyte cell line HaCaT. The effect for selected miRNAs on cell survival was analyzed using antagomirs for ectopic miRNA level decrease or miRNA mimics for increase. Cell survival was calculated as SM dose-dependent-curves. Out of 1920 miRNAs analyzed, 49 were significantly up- and 29 were significantly downregulated in HaCaT/SM when compared to HaCaT controls. Out of these, 36 could be grouped in miRNA families. Most of the 15 miRNA family members showed either a common increase or decrease. Only the members of miR-10, miR-154, miR-430 and miR-548 family showed an inconsistent picture. The ectopic increase of miR-181 in HaCaT/SM had a positive effect on cell survival in the presence of SM. In summary, the extensive differences in miRNA expression pattern between these cell lines indicate that specific miRNAs may play a role in the resistance mechanism against sulfur mustard. The miR-125b-2 and miR-181b alone are not responsible for the resistance development against SM, but an ectopic increase of miR-181 even enhances the SM resistance of HaCaT/SM. Improving the resistance in normal keratinocytes by treatment with either both miRNAs together or a different combination might be used as an initial step in development of an innovative new drug or prophylactic agent against SM. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Can Insects Develop Resistance to Insect Pathogenic Fungi?

    Science.gov (United States)

    Yaroslavtseva, Olga N.; Greig, Carolyn; Kryukov, Vadim Y.; Grizanova, Ekaterina V.; Mukherjee, Krishnendu; Vilcinskas, Andreas; Glupov, Viktor V.; Butt, Tariq M.

    2013-01-01

    Microevolutionary adaptations and mechanisms of fungal pathogen resistance were explored in a melanic population of the Greater wax moth, Galleria mellonella. Under constant selective pressure from the insect pathogenic fungus Beauveria bassiana, 25th generation larvae exhibited significantly enhanced resistance, which was specific to this pathogen and not to another insect pathogenic fungus, Metarhizium anisopliae. Defense and stress management strategies of selected (resistant) and non-selected (susceptible) insect lines were compared to uncover mechanisms underpinning resistance, and the possible cost of those survival strategies. We hypothesize that the insects developed a transgenerationally primed resistance to the fungus B. bassiana, a costly trait that was achieved not by compromising life-history traits but rather by prioritizing and re-allocating pathogen-species-specific augmentations to integumental front-line defenses that are most likely to be encountered by invading fungi. Specifically during B. bassiana infection, systemic immune defenses are suppressed in favour of a more limited but targeted repertoire of enhanced responses in the cuticle and epidermis of the integument (e.g. expression of the fungal enzyme inhibitor IMPI, and cuticular phenoloxidase activity). A range of putative stress-management factors (e.g. antioxidants) is also activated during the specific response of selected insects to B. bassiana but not M. anisopliae. This too occurs primarily in the integument, and probably contributes to antifungal defense and/or helps ameliorate the damage inflicted by the fungus or the host’s own immune responses. PMID:23560083

  6. Effects of PEMF on a murine osteosarcoma cell line: drug-resistant (P-glycoprotein-positive) and non-resistant cells.

    Science.gov (United States)

    Miyagi, N; Sato, K; Rong, Y; Yamamura, S; Katagiri, H; Kobayashi, K; Iwata, H

    2000-02-01

    After pulsed exposure of Dunn osteosarcoma cells (nonresistant cells) to Adriamycin (ADR) at increasing concentrations and single-cell cloning of surviving cells, ADR-resistant cells were obtained. These resistant cells expressed P-glycoprotein and had resistance more than 10 times that of their nonresistant parent cells. Compared to the nonresistant cells not exposed to pulsing electromagnetic fields (PEMF) in ADR-free medium, their growth rates at ADR concentrations of 0.01 and 0.02 micrograms/ml, which were below IC50, were 83.0% and 61.8%, respectively. On the other hand, in the nonresistant cells exposed to PEMF (repetition frequency, 10 Hz; rise time, 25 microsec, peak magnetic field intensity, 0.4-0.8 mT), the growth rate was 111.9% in ADR-free medium, 95.5% at an ADR concentration of 0.01 micrograms/ml, and 92.2% at an ADR concentration of 0.02 micrograms/ml. This promotion of growth by PEMF is considered to be a result of mobilization of cells in the non-proliferative period of the cell cycle due to exposure to PEMF. However, at ADR concentrations above the IC50, the growth rate tended to decrease in the cells not exposed to PEMF. This may be caused by an increase in cells sensitive to ADR resulting from mobilization of cells in the non-proliferative period to the cell cycle. The growth rate in the resistant cells exposed to PEMF was significantly lower than that in the non-exposed resistant cells at all ADR concentrations, including ADR-free culture (PPEMF promotes the growth of undifferentiated cells but progressively suppresses the growth of more differentiated cells, i.e., PEMF controls cell growth depending on the degree of cell differentiation. This study also shows the potentiality of PEMF as an adjunctive treatment method for malignant tumors. Copyright 2000 Wiley-Liss, Inc.

  7. Higher expression of SIRT1 induced resistance of esophageal squamous cell carcinoma cells to cisplatin.

    Science.gov (United States)

    Cao, Bin; Shi, Qintong; Wang, Wengong

    2015-04-01

    High expression of Sirtuin type 1 (SIRT1) exists in some cancer cells. However, it is still unclear whether SIRT1 affects the sensitivity of esophageal cancer cells to cisplatin. This study was designed to explore the relationship between SIRT1 expression and resistance of esophageal squamous cell carcinoma (ESCC) cells to cisplatin and reveal the underlying mechanism. The tissue samples of 68 ESCC patients were collected from Nanjing Drum Tower Hospital, China. All the patients had undergone cisplatin based combination chemotherapy. The expression of SIRT1and Noxa in tissue samples were analyzed by quantitative real-time reverse PCR (qRT-PCR) and Western blot. Human ESCC cell line (ECa9706 cells) was cultured and a cisplatin-resistant subline (ECa9706-CisR cells) was established by continuous exposure to cisplatin at different concentrations. The expression of SIRT1 and Noxa in both cell lines was analyzed by qRT-PCR and Western blot. siRNA technology was utilized to down-regulate the SIRT1 expression in ECa9706-CisR cells. The influence of SIRT1 silence on sensitivity of ECa9706-CisR cells to cisplatin was confirmed using CCK-8 assay and flow cytometry. Furthermore, the level change of Noxa after SIRT1 silence in ECa9706-CisR cells was determined by qRT-PCR and Western blot. SIRT1 and Noxa expression in chemo-resistant patients was significantly increased and decreased respectively, compared with chemo-sensitive patients. SIRT1 expression in ECa9706-CisR cells was significantly increased with a lower Noxa level, compared with normal ECa9706 cells. Cisplatin 5 µM could cause proliferation inhibition, G2/M phase arrest and apoptosis in ECa9706-CisR cells and these effects could be enhanced dramatically by SIRT1 silencing. Moreover, Noxa expression was increased after treated with SIRT1 siRNA. Over-expression of SIRT1 may cause resistance of ESCC cells to cisplatin through the mechanism involved with Noxa expression.

  8. The study of resistant mechanisms and reversal in an imatinib resistant Ph+ acute lymphoblastic leukemia cell line.

    Science.gov (United States)

    Xing, Hongyun; Yang, Xi; Liu, Ting; Lin, Juan; Chen, Xiaoyi; Gong, Yuping

    2012-04-01

    In this study, we established an imatinib resistant Ph+ acute lymphoblastic leukemia (ALL) cell line SUP-B15/RI in vitro and studied the mechanism of imatinib resistance. Our results showed that the BCR-ABL1 fusion gene and the mdr1 gene were 6.1 times and 1.7 times, respectively, as high as that of parental SUP-B15 cell line. We found no mutation in the Abl kinase domain of SUP-B15/RI. Furthermore, the detection of cell signaling pathway of PI3K/AKT/mTOR, RAS/RAF, NF-κB, JNK and STAT showed the up-regulation of phosphorylation of AKT, mTOR, P70S6K, and RAF, ERK, and MEK, down-regulation of PTEN and 4EBP-1, and no change in other cell signaling pathways in SUP-B15/RI. However, dasatinib and nilotinib showed partial resistance. Interestingly, bortezomib had no resistance. Imatinib combination with rapamycin had synergistic effect on overcoming the resistance. Altogether, over-expression of BCR-ABL1 and mdr1 gene were involved in the resistance mechanisms, and up-regulation of the cell signaling pathways of PI3K/AKT/mTOR, RAS/RAF in SUP-B15/RI cell line may be correlated with them. The SUP-B15/RI cell line was also resistant to the second generation tyrosine kinase, dasatinib, and nilotinib, not bortezomib. The combination of imatinib with rapamycin can partially overcome the resistance and blockade of the ubiquitin-proteasome can be also a promising pathway to overcome imatinib resistance. Copyright © 2011 Elsevier Ltd. All rights reserved.

  9. 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...

  10. Colorectal cancer cell lines made resistant to SN38-and Oxaliplatin: Roles of altered ion transporter function in resistance?

    DEFF Research Database (Denmark)

    Sandra, Christensen; Jensen, Niels Frank; Stoeckel, Johanne Danmark

    2013-01-01

    Colorectal cancer (CRC) is the 3rd most common cancer globally, with 5year survival rates of ~50%. Response rates to standard treatments (irinotecan (SN38) or Oxaliplatin (Oxp)) are 31–56% and drug resistance is a major problem. Thus, we established in vitro CRC models to investigate SN38 and Oxp...... resistance in HCT-116, HT-29 and LoVo cells. Microarray analysis and qPCR validation showed that mRNA expression of glutamate transporters SLC1A1 and SLC1A3 were markedly altered in resistant cells. Remarkably, mRNA levels of SLC1A3 were increased by ~40-and ~2500-fold in SN38-and Oxp-resistant HT29 cells......, respectively. Studies are ongoing to assess glutamate uptake in parental and resistant CRC cells and the effect of inhibition/knockdown of SLC1A1 and -3 on SN38- and Oxp resistance. In conclusion, SN38-and Oxp-resistance in CRC cells is associated with SLC1A1 and -3 dysregulation. As these transporters have...

  11. WILDFIRE IGNITION RESISTANCE ESTIMATOR WIZARD SOFTWARE DEVELOPMENT REPORT

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, M.; Robinson, C.; Gupta, N.; Werth, D.

    2012-10-10

    This report describes the development of a software tool, entitled “WildFire Ignition Resistance Estimator Wizard” (WildFIRE Wizard, Version 2.10). This software was developed within the Wildfire Ignition Resistant Home Design (WIRHD) program, sponsored by the U. S. Department of Homeland Security, Science and Technology Directorate, Infrastructure Protection & Disaster Management Division. WildFIRE Wizard is a tool that enables homeowners to take preventive actions that will reduce their home’s vulnerability to wildfire ignition sources (i.e., embers, radiant heat, and direct flame impingement) well in advance of a wildfire event. This report describes the development of the software, its operation, its technical basis and calculations, and steps taken to verify its performance.

  12. Asymmetric cell division during T cell development controls downstream fate

    Science.gov (United States)

    Pham, Kim; Shimoni, Raz; Charnley, Mirren; Ludford-Menting, Mandy J.; Hawkins, Edwin D.; Ramsbottom, Kelly; Oliaro, Jane; Izon, David; Ting, Stephen B.; Reynolds, Joseph; Lythe, Grant; Molina-Paris, Carmen; Melichar, Heather; Robey, Ellen; Humbert, Patrick O.; Gu, Min

    2015-01-01

    During mammalian T cell development, the requirement for expansion of many individual T cell clones, rather than merely expansion of the entire T cell population, suggests a possible role for asymmetric cell division (ACD). We show that ACD of developing T cells controls cell fate through differential inheritance of cell fate determinants Numb and α-Adaptin. ACD occurs specifically during the β-selection stage of T cell development, and subsequent divisions are predominantly symmetric. ACD is controlled by interaction with stromal cells and chemokine receptor signaling and uses a conserved network of polarity regulators. The disruption of polarity by deletion of the polarity regulator, Scribble, or the altered inheritance of fate determinants impacts subsequent fate decisions to influence the numbers of DN4 cells arising after the β-selection checkpoint. These findings indicate that ACD enables the thymic microenvironment to orchestrate fate decisions related to differentiation and self-renewal. PMID:26370500

  13. Demethylation restores SN38 sensitivity in cells with acquired resistance to SN38 derived from human cervical squamous cancer cells

    Science.gov (United States)

    TANAKA, TETSUJI; BAI, TAO; TOUJIMA, SAORI; UTSUNOMIYA, TOMOKO; MATSUOKA, TOSHIHIDE; KOBAYASHI, AYA; YAMAMOTO, MADOKA; SASAKI, NORIYUKI; TANIZAKI, YUKO; UTSUNOMIYA, HIROTOSHI; TANAKA, JUNKO; YUKAWA, KAZUNORI

    2012-01-01

    Using seven monoclonal SN38-resistant subclones established from ME180 human cervical squamous cell carcinoma cells, we examined the demethylation effects of 5-aza-2′-deoxycytidine (5-aza-CdR) on the SN38-sensitivity of the cells as well as the expression of death-associated protein kinase (DAPK) in the SN38-resistant cells. The DAPK expression levels were evaluated among parent ME180 cells, SN38-resistant ME180 cells and cisplatin-resistant ME180 cells by methylation-specific DAPK-PCR, quantitative RT-PCR and western blot analysis. The SN38-resistant cells co-treated with SN38 and 5-aza-CdR strongly exhibited enhanced SN38-sensitivities resembling those found in the parent cells. In the SN38-resistant subclones, no relationships were found between the restored SN38 sensitivity and hypermethylation of the DAPK promoter, DAPK mRNA expression, DAPK protein expression and induction of DAPK protein after 5-aza-CdR treatment, unlike the strong suppression of 5-aza-CdR-induced DAPK protein expression in the cisplatin-resistant subclones. These findings indicate that reversibly methylated molecules, but not DAPK, may regulate SN38 resistance, and that demethylating agents can be strong sensitizing anticancer chemotherapeutic drugs for SN38-resistant cancers. PMID:22246465

  14. Hyperleptinemia is required for the development of leptin resistance.

    Directory of Open Access Journals (Sweden)

    Zachary A Knight

    2010-06-01

    Full Text Available Leptin regulates body weight by signaling to the brain the availability of energy stored as fat. This negative feedback loop becomes disrupted in most obese individuals, resulting in a state known as leptin resistance. The physiological causes of leptin resistance remain poorly understood. Here we test the hypothesis that hyperleptinemia is required for the development of leptin resistance in diet-induced obese mice. We show that mice whose plasma leptin has been clamped to lean levels develop obesity in response to a high-fat diet, and the magnitude of this obesity is indistinguishable from wild-type controls. Yet these obese animals with constant low levels of plasma leptin remain highly sensitive to exogenous leptin even after long-term exposure to a high fat diet. This shows that dietary fats alone are insufficient to block the response to leptin. The data also suggest that hyperleptinemia itself can contribute to leptin resistance by downregulating cellular response to leptin as has been shown for other hormones.

  15. Antibiotic Discovery: Combatting Bacterial Resistance in Cells and in Biofilm Communities

    Directory of Open Access Journals (Sweden)

    Anahit Penesyan

    2015-03-01

    Full Text Available Bacterial resistance is a rapidly escalating threat to public health as our arsenal of effective antibiotics dwindles. Therefore, there is an urgent need for new antibiotics. Drug discovery has historically focused on bacteria growing in planktonic cultures. Many antibiotics were originally developed to target individual bacterial cells, being assessed in vitro against microorganisms in a planktonic mode of life. However, towards the end of the 20th century it became clear that many bacteria live as complex communities called biofilms in their natural habitat, and this includes habitats within a human host. The biofilm mode of life provides advantages to microorganisms, such as enhanced resistance towards environmental stresses, including antibiotic challenge. The community level resistance provided by biofilms is distinct from resistance mechanisms that operate at a cellular level, and cannot be overlooked in the development of novel strategies to combat infectious diseases. The review compares mechanisms of antibiotic resistance at cellular and community levels in the light of past and present antibiotic discovery efforts. Future perspectives on novel strategies for treatment of biofilm-related infectious diseases are explored.

  16. Nuclear respiratory factor-1 and bioenergetics in tamoxifen-resistant breast cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Radde, Brandie N.; Ivanova, Margarita M.; Mai, Huy Xuan; Alizadeh-Rad, Negin; Piell, Kellianne; Van Hoose, Patrick; Cole, Marsha P.; Muluhngwi, Penn; Kalbfleisch, Ted S. [Department of Biochemistry & Molecular Genetics, Center for Genetics and Molecular Medicine, University of Louisville School of Medicine, Louisville, KY 40292 (United States); Rouchka, Eric C. [Bioinformatics and Biomedical Computing Laboratory, Department of Computer Engineering and Computer Science, University of Louisville, Louisville, KY 40292 (United States); Hill, Bradford G. [Department of Medicine, University of Louisville School of Medicine, Louisville, KY 40292 (United States); Klinge, Carolyn M., E-mail: carolyn.klinge@louisville.edu [Department of Biochemistry & Molecular Genetics, Center for Genetics and Molecular Medicine, University of Louisville School of Medicine, Louisville, KY 40292 (United States)

    2016-09-10

    Acquired tamoxifen (TAM) resistance is a significant clinical problem in treating patients with estrogen receptor α (ERα)+ breast cancer. We reported that ERα increases nuclear respiratory factor-1 (NRF-1), which regulates nuclear-encoded mitochondrial gene transcription, in MCF-7 breast cancer cells and NRF-1 knockdown stimulates apoptosis. Whether NRF-1 and target gene expression is altered in endocrine resistant breast cancer cells is unknown. We measured NRF-1and metabolic features in a cell model of progressive TAM-resistance. NRF-1 and its target mitochondrial transcription factor A (TFAM) were higher in TAM-resistant LCC2 and LCC9 cells than TAM-sensitive MCF-7 cells. Using extracellular flux assays we observed that LCC1, LCC2, and LCC9 cells showed similar oxygen consumption rate (OCR), but lower mitochondrial reserve capacity which was correlated with lower Succinate Dehydrogenase Complex, Subunit B in LCC1 and LCC2 cells. Complex III activity was lower in LCC9 than MCF-7 cells. LCC1, LCC2, and LCC9 cells had higher basal extracellular acidification (ECAR), indicating higher aerobic glycolysis, relative to MCF-7 cells. Mitochondrial bioenergetic responses to estradiol and 4-hydroxytamoxifen were reduced in the endocrine-resistant cells compared to MCF-7 cells. These results suggest the acquisition of altered metabolic phenotypes in response to long term antiestrogen treatment may increase vulnerability to metabolic stress. - Highlights: • NRF-1 and TFAM expression are higher in endocrine-resistant breast cancer cells. • Oxygen consumption rate is similar in endocrine-sensitive and resistant cells. • Mitochondrial reserve capacity is lower in endocrine-resistant cells. • Endocrine-resistant breast cancer cells have increased glycolysis. • Bioenergetic responses to E2 and tamoxifen are lower in endocrine-resistant cells.

  17. LIQUID HYDROCARBON FUEL CELL DEVELOPMENT.

    Science.gov (United States)

    A compound anode consists of a reforming catalyst bed in direct contact with a palladium-silver fuel cell anode. The objective of this study was to...prove the feasibility of operating a compound anode fuel cell on a liquid hydrocarbon and to define the important parameters that influence cell...performance. Both reformer and fuel cell tests were conducted with various liquid hydrocarbon fuels. Included in this report is a description of the

  18. 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.

  19. Mechanisms of multidrug resistance in HL60 cells. Analysis of resistance associated membrane proteins and levels of mdr gene expression.

    Science.gov (United States)

    McGrath, T; Latoud, C; Arnold, S T; Safa, A R; Felsted, R L; Center, M S

    1989-10-15

    HL60 cells isolated for resistance to Adriamycin do not contain P-glycoprotein, as determined with immunological probes. These cells, however, are multidrug resistant and defective in the cellular accumulation of drug. In view of these findings, we have examined in greater detail certain properties of the HL60/Adr cells and have compared these properties to an HL60 drug-resistant isolate (HL60/Vinc) which contains high levels of P-glycoprotein. The results of these studies demonstrated that verapamil induces a major increase in cellular drug accumulation in both HL60/Adr and HL60/Vinc isolates. An 125I-labeled photoaffinity analog of verapamil labeled P-glycoprotein contained in membranes of HL60/Vinc cells. In contrast, this agent did not label any protein selectively associated with drug resistance in membranes of the HL60/Adr isolate. The photoactive dihydropyridine calcium channel blocker [3H]azidopine and [125I]NASV, a photoaffinity analog of vinblastine, labelled P-glycoprotein in membranes from HL60/Vinc cells, whereas in experiments with the HL60/Adr isolate there was no detectable labeling of a drug resistance associated membrane protein. Additional studies have been carried out to analyze membrane proteins of HL60/Adr cells labeled with the photoaffinity agent 8-azido-alpha-[32P]ATP (AzATP32). The results demonstrate that this agent labeled a resistance associated membrane protein of 190 kilodaltons (P190). P190 is essentially absent in membranes of drug-sensitive cells. Labeling of P190 with AzATP32 in membranes of resistant cells was blocked completely when incubations were carried out in the presence of excess unlabeled ATP. Additional studies were carried out to analyze mdr gene amplification and expression in sensitive and resistant cells. Experiments carried out with human 5',mdr1 (1.1 kb) and mdr3 (1.0 kb) cDNAs demonstrate that both of these sequences were highly amplified in the HL60/Vinc isolate. Only the mrd1 gene sequence however, was

  20. 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...

  1. Phenotypic and genomic comparisons of highly vancomycin-resistant Staphylococcus aureus strains developed from multiple clinical MRSA strains by in vitro mutagenesis.

    Science.gov (United States)

    Ishii, Kenichi; Tabuchi, Fumiaki; Matsuo, Miki; Tatsuno, Keita; Sato, Tomoaki; Okazaki, Mitsuhiro; Hamamoto, Hiroshi; Matsumoto, Yasuhiko; Kaito, Chikara; Aoyagi, Tetsuji; Hiramatsu, Keiichi; Kaku, Mitsuo; Moriya, Kyoji; Sekimizu, Kazuhisa

    2015-11-25

    The development of vancomycin (VCM) resistance in Staphylococcus aureus threatens global health. Studies of the VCM-resistance mechanism and alternative therapeutic strategies are urgently needed. We mutagenized S. aureus laboratory strains and methicillin-resistant S. aureus (MRSA) with ethyl methanesulfonate, and isolated mutants that exhibited high resistance to VCM (minimum inhibitory concentration = 32 μg/ml). These VCM-resistant strains were sensitive to linezolid and rifampicin, and partly to arbekacin and daptomycin. Beta-lactams had synergistic effects with VCM against these mutants. VCM-resistant strains exhibited a 2-fold increase in the cell wall thickness. Several genes were commonly mutated among the highly VCM-resistant mutants. These findings suggest that MRSA has a potential to develop high VCM resistance with cell wall thickening by the accumulation of mutations.

  2. A high temperature cell for simultaneous electrical resistance and neutron diffraction measurements.

    Science.gov (United States)

    Engin, T E; Powell, A V; Haynes, R; Chowdhury, M A H; Goodway, C M; Done, R; Kirichek, O; Hull, S

    2008-09-01

    An in situ cell that allows the electrical resistance of a sample pellet to be measured while performing neutron diffraction experiments has been developed at the ISIS pulsed neutron source. The sample is held between two spring loaded platinum electrodes embedded in a boron nitride clamp assembly with the resistance measured using the four-probe method. An outer quartz glass jacket allows the atmosphere within the sample enclosure to be controlled, and the entire device can be accommodated within a standard ISIS neutron furnace for measurements at temperatures up to 1270 K. The operation of this cell is illustrated using data for the structural, magnetic, and electrical properties of chalcopyrite CuFeS(2) collected over the temperature range of 398-873 K on the Polaris powder diffractometer at ISIS.

  3. ISG15 Inhibits IFN-α-Resistant Liver Cancer Cell Growth

    Directory of Open Access Journals (Sweden)

    Xin-xing Wan

    2013-01-01

    Full Text Available Hepatocellular carcinoma (HCC is one of the most prevalent tumors worldwide. Interferon-α (IFN-α has been widely used in the treatment of HCC, but patients eventually develop resistance. ISG15 ubiquitin-like modifier (ISG15 is a ubiquitin-like protein transcriptionally regulated by IFN-α which shows antivirus and antitumor activities. However, the exact role of ISG15 is unknown. In the present study, we showed that IFN-α significantly induced ISG15 expression but failed to induce HepG2 cell apoptosis, whereas transient overexpression of ISG15 dramatically increased HepG2 cell apoptosis. ISG15 overexpression increased overall protein ubiquitination, which was not observed in cells with IFN-α-induced ISG15 expression, suggesting that IFN-α treatment not only induced the expression of ISG15 but also inhibited ISG15-mediated ubiquitination. The tumor suppressor p53 and p21 proteins are the key regulators of cell survival and death in response to stress signals such as DNA damage. We showed that p53 or p21 is only up regulated in HepG2 cells ectopically expressing ISG15, but not in the presence of IFN-α-induced ISG15. Our results suggest that ISG15 overexpression could be developed into a powerful gene-therapeutic tool for treating IFN-α-resistant HCC.

  4. Development of Tetrapolar Conductivity Cell for Liquid Measurement Application

    Directory of Open Access Journals (Sweden)

    M. N. Anas

    2014-03-01

    Full Text Available This paper deals with the development of a liquid measuring instrumentation using the popular tetrapolar electrode configuration. The system consists of four-electrode ring shape using Cromium metal plate and a small measurement. The developed instrument is calibrated with the help of prepared saline solution prepared in lab. A liquid of known parameter is placed inside the measurement cell and current is injected through excitation electrode with certain frequency and voltage drop is measured across electrode potential terminals. From this voltages and cell constant value, the conductivity, resistivity and impedance of the measured liquid could be determined with acceptable accuracy with more than 96 % compared to the standard measurement.

  5. Long noncoding RNA ROR regulates chemoresistance in docetaxel-resistant lung adenocarcinoma cells via epithelial mesenchymal transition pathway.

    Science.gov (United States)

    Pan, Yan; Chen, Jing; Tao, Leilei; Zhang, Kai; Wang, Rui; Chu, Xiaoyuan; Chen, Longbang

    2017-05-16

    Emerging evidence indicates that the dysregulation of long non-coding RNAs (lncRNAs) contributes to the development and progression of lung adenocarcinoma (LAD), however the underlying mechanism of action of lncRNAs remains unclear. It is well known that the effective treatment of cancers has been hindered by drug resistance in the clinical setting. Epithelial-mesenchymal transition (EMT) has been recognized to be involved in acquiring drug resistance, cell migration and invasion properties in several types of cancer. Docetaxel-resistant LAD cells established previously in our lab present chemoresistant and mesenchymal features. Long intergenic non-protein coding RNA, regulator of reprogramming (linc-ROR), was first discovered in induced pluripotent stem cells (iPSCs) and was upregulated in docetaxel-resistant LAD cells. In this study, we tried to make clarification of lincRNA-related mechanisms underlying EMT followed by acquired resistance to chemotherapy in LAD. In order to hit the mark, we made use of multiple methods including microarray analysis, qRT-PCR, western blotting analysis, loss/gain-of-function analysis, luciferase assays, drug sensitivity assays, wound-healing assay and invasion assay. We found that decreased expression of linc-ROR effectively reversed EMT in docetaxel-resistant LAD cells and sensitized them to chemotherapy. The function of linc-ROR exerted in LAD cells depended on the sponging of miR-145, therefore, releasing the miR-145 target FSCN1, and thus contributing to the acquisition of chemoresistance and EMT phenotypes of docetaxel-resistant LAD cells. Our findings revealed that linc-ROR might act as potential therapeutic target to overcome chemotherapy resistance in LAD.

  6. 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. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  7. The PSA−/lo prostate cancer cell population harbors self-renewing long-term tumor-propagating cells that resist castration

    Science.gov (United States)

    Qin, Jichao; Liu, Xin; Laffin, Brian; Chen, Xin; Choy, Grace; Jeter, Collene; Calhoun-Davis, Tammy; Li, Hangwen; Palapattu, Ganesh S.; Pang, Shen; Lin, Kevin; Huang, Jiaoti; Ivanov, Ivan; Li, Wei; Suraneni, Mahipal V.; Tang, Dean G.

    2012-01-01

    SUMMARY Prostate cancer (PCa) is heterogeneous and contains both differentiated and undifferentiated tumor cells, but the relative functional contribution of these two cell populations remains unclear. Here we report distinct molecular, cellular, and tumor-propagating properties of PCa cells that express high (PSA+) and low (PSA−/lo) levels of the differentiation marker PSA. PSA−/lo PCa cells are quiescent and refractory to stresses including androgen deprivation, exhibit high clonogenic potential, and possess long-term tumor-propagating capacity. They preferentially express stem cell genes and can undergo asymmetric cell division generating PSA+ cells. Importantly, PSA−/lo PCa cells can initiate robust tumor development and resist androgen ablation in castrated hosts, and harbor highly tumorigenic castration-resistant PCa cells that can be prospectively enriched using ALDH+CD44+α2β1+ phenotype. In contrast, PSA+ PCa cells possess more limited tumor-propagating capacity, undergo symmetric division and are sensitive to castration. Together, our study suggests PSA−/lo cells may represent a critical source of castration-resistant PCa cells. PMID:22560078

  8. Effect of Bacteriophages on the Growth of Flavobacterium psychrophilum and Development of Phage-Resistant Strains.

    Science.gov (United States)

    Christiansen, Rói Hammershaimb; Madsen, Lone; Dalsgaard, Inger; Castillo, Daniel; Kalatzis, Panos G; Middelboe, Mathias

    2016-05-01

    The controlling effect of single and multiple phages on the density of Flavobacterium psychrophilum at different initial multiplicity of infection (MOI) was assessed in batch cultures to explore the potential for phage-based treatment of this important fish pathogen. A high initial phage concentration (MOI = 0.3-4) was crucial for efficient viral lysis, resulting in a 10(4)-10(5)-fold reduction of phage-sensitive cells (both single phages and phage cocktails), which was maintained throughout the incubation (>10 days). Following cell lysis, regrowth of phage-resistant strains was examined and resistant strains were isolated for further characterization. The application of a mathematical model allowed simulation of phage-host interactions and resistance development, confirming indications from strain isolations that phage-sensitive strains dominated the regrowing population (>99.8%) at low MOI and phage-resistant strains (>87.8%) dominated at high MOI. A cross-infectivity test covering 68 isolated strains and 22 phages resulted in 23 different host susceptibility patterns, with 20 of the isolates being resistant to all the applied phages. Eleven isolated strains with different susceptibility patterns had lower growth rates (0.093 to 0.31 h(-1)) than the host strain (0.33 h(-1)), while 10 of 14 examined strains had lost the ability to take up specific substrates as shown by BIOLOG profiles. Despite increased selection for phage resistance at high MOI, the results emphasize that high initial MOI is essential for fast and effective control of F. psychrophilum infection and suggest that the small populations of resistant clones had reduced competitive abilities relative to the sensitive ancestral strain.

  9. NSC23925, identified in a high-throughput cell-based screen, reverses multidrug resistance.

    Directory of Open Access Journals (Sweden)

    Zhenfeng Duan

    2009-10-01

    Full Text Available Multidrug resistance (MDR is a major factor which contributes to the failure of cancer chemotherapy, and numerous efforts have been attempted to overcome MDR. To date, none of these attempts have yielded a tolerable and effective therapy to reverse MDR; thus, identification of new agents would be useful both clinically and scientifically.To identify small molecule compounds that can reverse chemoresistance, we developed a 96-well plate high-throughput cell-based screening assay in a paclitaxel resistant ovarian cancer cell line. Coincubating cells with a sublethal concentration of paclitaxel in combination with each of 2,000 small molecule compounds from the National Cancer Institute Diversity Set Library, we identified a previously uncharacterized molecule, NSC23925, that inhibits Pgp1 and reverses MDR1 (Pgp1 but does not inhibit MRP or BCRP-mediated MDR. The cytotoxic activity of NSC23925 was further evaluated using a panel of cancer cell lines expressing Pgp1, MRP, and BCRP. We found that at a concentration of >10 microM NSC23925 moderately inhibits the proliferation of both sensitive and resistant cell lines with almost equal activity, but its inhibitory effect was not altered by co-incubation with the Pgp1 inhibitor, verapamil, suggesting that NSC23925 itself is not a substrate of Pgp1. Additionally, NSC23925 increases the intracellular accumulation of Pgp1 substrates: calcein AM, Rhodamine-123, paclitaxel, mitoxantrone, and doxorubicin. Interestingly, we further observed that, although NSC23925 directly inhibits the function of Pgp1 in a dose-dependent manner without altering the total expression level of Pgp1, NSC23925 actually stimulates ATPase activity of Pgp, a phenomenon seen in other Pgp inhibitors.The ability of NSC23925 to restore sensitivity to the cytotoxic effects of chemotherapy or to prevent resistance could significantly benefit cancer patients.

  10. Development of PEM fuel cell technology at international fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Wheeler, D.J.

    1996-04-01

    The PEM technology has not developed to the level of phosphoric acid fuel cells. Several factors have held the technology development back such as high membrane cost, sensitivity of PEM fuel cells to low level of carbon monoxide impurities, the requirement to maintain full humidification of the cell, and the need to pressurize the fuel cell in order to achieve the performance targets. International Fuel Cells has identified a hydrogen fueled PEM fuel cell concept that leverages recent research advances to overcome major economic and technical obstacles.

  11. Resistance mechanisms to erlotinib in the non-small cell lung cancer cell line, HCC827 examined by RNA-seq

    DEFF Research Database (Denmark)

    Jacobsen, Kirstine; Alcaraz, Nicolas; Ditzel, Henrik

    Background: Erlotinib, an EGFR selective reversible inhibitor, has dramatically changed the treatment of non-small cell lung cancer (NSCLC) as approximately 70% of patients show significant tumor regression upon treatment. However, all patients eventually relapse due to development of acquired...... - in erlotinib-resistant subclones of the NSCLC cell line HCC827. Materials & Methods: We established 3 erlotinib-resistant subclones (resistant to 10, 20, 30 µM erlotinib, respectively), and prepared cDNA libraries of purified RNA from biological duplicates using TruSeq® Stranded Total RNA Ribo-Zero™ Gold...... (Illumina) prior to sequencing on an Illumina HiSeq platform (100bp paired end). The resistant subclones were examined both in presence and absence of erlotinib. The data was analyzed by an in-house developed pipeline including quality control by Trim Galore v0.3.3, mapping of reads to HG19 by TopHat2 v.2...

  12. Resistance mechanisms to erlotinib in the non-small cell lung cancer cell line, HCC827 examined by RNA-seq

    DEFF Research Database (Denmark)

    Jacobsen, Kirstine; Alcaraz, Nicolas; Ditzel, Henrik

    (Illumina) prior to sequencing on an Illumina HiSeq platform (100bp paired end). The resistant subclones were examined both in presence and absence of erlotinib. The data was analyzed by an in-house developed pipeline including quality control by Trim Galore v0.3.3, mapping of reads to HG19 by TopHat2 v.2......Background: Erlotinib, an EGFR selective reversible inhibitor, has dramatically changed the treatment of non-small cell lung cancer (NSCLC) as approximately 70% of patients show significant tumor regression upon treatment. However, all patients eventually relapse due to development of acquired...... - in erlotinib-resistant subclones of the NSCLC cell line HCC827. Materials & Methods: We established 3 erlotinib-resistant subclones (resistant to 10, 20, 30 µM erlotinib, respectively), and prepared cDNA libraries of purified RNA from biological duplicates using TruSeq® Stranded Total RNA Ribo-Zero™ Gold...

  13. Saikosaponin A, an active glycoside from Radix bupleuri, reverses P-glycoprotein-mediated multidrug resistance in MCF-7/ADR cells and HepG2/ADM cells.

    Science.gov (United States)

    Ye, Rui-Ping; Chen, Zhen-Dong

    2017-02-01

    1. The expression and function of P-glycoprotein (P-gp) is associated with the phenotype of multidrug resistance (MDR). Saikosaponin A (SSA) is a triterpenoid saponin isolated from Radix Bupleuri. This study was mainly designed to understand effects of SSA on MDR in MCF-7/ADR and HepG2/ADM cells. 2. MDR reversal was examined as the alteration of cytotoxic drugs IC50 in resistant cells in the presence of SSA by MTT assay, and was compared with the non-resistant cells. Apoptosis and uptake of P-gp substrates in the tumor cells were detected by flow cytometry. Western blot was performed to assay the expression of P-gp. 3. Our results demonstrate SSA could increase the chemosensitivity of P-gp overexpressing HepG2/ADM and MCF-7/ADR cells to doxorubicin (DOX), vincristine (VCR) and paclitaxel. SSA promoted apoptosis of MCF-7/ADR cells in the presence of DOX. Moreover, it could also increase the retention of P-gp substrates DOX and rhodamine 123 in MCF-7/ADR cells, and decrease digoxin efflux ratio in Caco-2 cell monolayer. Finally, a mechanistic study showed that SSA reduced P-gp expression without affecting hydrolytic activity of P-gp. 4. In conclusion, our findings suggest that SSA could be further developed for sensitizing resistant cancer cells and used as an adjuvant therapy together with anticancer drugs to improve their therapeutic efficacies.

  14. Proteomic analysis of docetaxel resistance in human nasopharyngeal carcinoma cells using the two-dimensional gel electrophoresis method.

    Science.gov (United States)

    Peng, Xingchen; Gong, Fengming M; Ren, Min; Ai, Ping; Wu, ShaoYong; Tang, Jie; Hu, XiaoLin

    2016-09-01

    Docetaxel-based chemotherapy has been recommended for advanced nasopharyngeal carcinoma (NPC). However, treatment failure often occurs because of acquired drug resistance. In this study, a docetaxel-resistant NPC cell line CNE-2R was established with increasing doses of docetaxel for more than 6 months. Two-dimensional gel electrophoresis and ESI-Q-TOF-MS were used to compare the differential expression of docetaxel-resistance-associated proteins between human NPC CNE-2 cells and docetaxel-resistant CNE-2R cells. As a result, 24 differentially expressed proteins were identified, including 11 proteins with increased expression and 13 proteins with decreased expression. These proteins function in diverse biological processes such as metabolism, signal transduction, calcium ion binding, immune response, proteolysis, and so on. Among these, α-enolase (ENO1), significantly upregulated in CNE-2R, was selected for detailed analysis. Inhibition of ENO1 by shRNA restored CNE-2R cells' sensitivity to docetaxel. Moreover, overexpression of ENO1 could facilitate the development of acquired resistance of docetaxel in CNE-2 cells. Western blot and reverse-transcription PCR data of clinical samples confirmed that α-enolase was upregulated in docetaxel-resistant human NPC tissues. Finding such proteins might improve interpretation of the molecular mechanisms leading to the acquisition of docetaxel chemoresistance.

  15. Factors determining sensitivity or resistance of tumor cell lines towards artesunate.

    Science.gov (United States)

    Sertel, Serkan; Eichhorn, Tolga; Sieber, Sebastian; Sauer, Alexandra; Weiss, Johanna; Plinkert, Peter K; Efferth, Thomas

    2010-04-15

    Clinical oncology is still challenged by the development of drug resistance of tumors that result in poor prognosis for patients. There is an urgent necessity to understand the molecular mechanisms of resistance and to develop novel therapy strategies. Artesunate (ART) is an anti-malarial drug, which also exerts profound cytotoxic activity towards cancer cells. We first applied a gene-hunting approach using cluster and COMPARE analyses of microarray-based transcriptome-wide mRNA expression profiles. Among the genes identified by this approach were genes from diverse functional groups such as structural constituents of ribosomes (RPL6, RPL7, RPS12, RPS15A), kinases (CABC1, CCT2, RPL41), transcriptional and translational regulators (SFRS2, TUFM, ZBTB4), signal transducers (FLNA), control of cell growth and proliferation (RPS6), angiogenesis promoting factors (ITGB1), and others (SLC25A19, NCKAP1, BST1, DBH, FZD7, NACA, MTHFD2). Furthermore, we applied a candidate gene approach and tested the role of resistance mechanisms towards established anti-cancer drugs for ART resistance. By using transfected or knockout cell models we found that the tumor suppressor p16(INK4A) and the anti-oxidant protein, catalase, conferred resistance towards ART, while the oncogene HPV-E6 conferred sensitivity towards ART. The tumor suppressor p53 and its downstream protein, p21, as well as the anti-oxidant manganese-dependent superoxide dismutase did not affect cellular response to ART. In conclusion, our pharmacogenomic approach revealed that response of tumor cells towards ART is multi-factorial and is determined by gene expression associated with either ART sensitivity or resistance. At least some of the functional groups of genes (e.g. angiogenesis promoting factors, cell growth and proliferation-associated genes signal transducers and kinases) are also implicated in clinical responsiveness of tumors towards chemotherapy. It merits further investigation, whether ART is responsive in

  16. High-content screening identifies kinase inhibitors that overcome venetoclax resistance in activated CLL cells

    Science.gov (United States)

    Oppermann, Sina; Ylanko, Jarkko; Shi, Yonghong; Hariharan, Santosh; Oakes, Christopher C.; Brauer, Patrick M.; Zúñiga-Pflücker, Juan C.; Leber, Brian; Spaner, David E.

    2016-01-01

    Novel agents such as the Bcl-2 inhibitor venetoclax (ABT-199) are changing treatment paradigms for chronic lymphocytic leukemia (CLL) but important problems remain. Although some patients exhibit deep and durable responses to venetoclax as a single agent, other patients harbor subpopulations of resistant leukemia cells that mediate disease recurrence. One hypothesis for the origin of resistance to venetoclax is by kinase-mediated survival signals encountered in proliferation centers that may be unique for individual patients. An in vitro microenvironment model was developed with primary CLL cells that could be incorporated into an automated high-content microscopy-based screen of kinase inhibitors (KIs) to identify agents that may improve venetoclax therapy in a personalized manner. Marked interpatient variability was noted for which KIs were effective; nevertheless, sunitinib was identified as the most common clinically available KI effective in overcoming venetoclax resistance. Examination of the underlying mechanisms indicated that venetoclax resistance may be induced by microenvironmental signals that upregulate antiapoptotic Bcl-xl, Mcl-1, and A1, which can be counteracted more efficiently by sunitinib than by ibrutinib or idelalisib. Although patient-specific drug responses are common, for many patients, combination therapy with sunitinib may significantly improve the therapeutic efficacy of venetoclax. PMID:27297795

  17. Alternative Pathway to a Glycopeptide-Resistant Cell Wall in the Balhimycin Producer Amycolatopsis balhimycina.

    Science.gov (United States)

    Frasch, Hans-Joerg; Kalan, Lindsay; Kilian, Regina; Martin, Tobias; Wright, Gerard D; Stegmann, Evi

    2015-06-12

    Balhimycin, a vancomycin-type glycopeptide, is a lipid II targeting antibiotic produced by Amycolatopsis balhimycina. A. balhimycina has developed a self-resistance mechanism based on the synergistic action of different enzymes resulting in modified peptidoglycan. The canonical resistance mechanism against glycopeptides is the synthesis of peptidoglycan precursors ending with acyl-d-alanyl-d-lactate (d-Ala-d-Lac) rather than acyl-d-alanyl-d-alanine (d-Ala-d-Ala). This reprogramming is the result of the enzymes VanH, VanA, and VanX. VanH and VanA are required to produce d-Ala-d-Lac; VanX cleaves cytosolic pools of d-Ala-d-Ala, thereby ensuring that peptidoglycan is enriched in d-Ala-d-Lac. In A. balhimycina, the ΔvanHAXAb mutant showed a reduced glycopeptide resistance in comparison to the wild type. Nevertheless, ΔvanHAXAb was paradoxically still able to produce d-Ala-d-Lac containing resistant cell wall precursors suggesting the presence of a novel alternative glycopeptide resistance mechanism. In silico analysis, inactivation studies, and biochemical assays led to the characterization of an enzyme, Ddl1Ab, as a paraloguous chromosomal d-Ala-d-Lac ligase able to complement the function of VanAAb in the ΔvanHAXAb mutant. Furthermore, A. balhimycina harbors a vanYAb gene encoding a d,d-carboxypeptidase. Transcriptional analysis revealed an upregulated expression of vanYAb in the ΔvanHAXAb mutant. VanYAb cleaves the endstanding d-Ala from the pentapeptide precursors, reducing the quantity of sensitive cell wall precursors in the absence of VanXAb. These findings represent an unprecedented coordinated layer of resistance mechanisms in a glycopeptide antibiotic producing bacterium.

  18. A cell-free enzymatic activity assay for the evaluation of HIV-1 drug resistance to protease inhibitors

    Directory of Open Access Journals (Sweden)

    Satoko eMatsunaga

    2015-10-01

    Full Text Available Due to their high frequency of genomic mutations, human retroviruses often develop resistance to antiretroviral drugs. The emergence of drug-resistant human immunodeficiency virus type 1 (HIV-1 is a significant obstacle to the effective long-term treatment of HIV infection. The development of a rapid and versatile drug-susceptibility assay would enable acquisition of phenotypic information and facilitate determination of the appropriate choice of antiretroviral agents. In this study, we developed a novel in vitro method, termed the Cell-Free Drug Susceptibility Assay (CFDSA, for monitoring phenotypic information regarding the drug resistance of HIV-1 protease (PR. The CFDSA utilizes a wheat germ cell-free protein production system to synthesize enzymatically active HIV-1 PRs directly from PCR products amplified from HIV-1 molecular clones or clinical isolates in a rapid one-step procedure. Enzymatic activity of PRs can be readily measured by AlphaScreen (Amplified Luminescent Proximity Homogeneous Assay Screen in the presence or absence of clinically used protease inhibitors (PIs. CFDSA measurement of drug resistance was based on the fold resistance to the half-maximal inhibitory concentration (IC50 of various protease inhibitors (PIs. The CFDSA could serve as a non-infectious, rapid, accessible, and reliable alternative to infectious cell-based phenotypic assays for evaluation of PI-resistant HIV-1.

  19. Development of application technology of radiation-resistant microorganism

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dong Ho; Lim, Sang Yong; Joe, Min Ho; Jung, Jin Woo; Jung, Sun Wook; Song, Du Sup; Choi, Young Ji [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2009-02-15

    The scope of the project is divided into of three parts; (i) to define the survival strategy of radiation-resistant microbes, especially Deinococcus (ii) acquisition of gene resources encoding the novel protein and related with the production of functional materials (iii) development of control technology against radiation-resistant microbes. To this aim, first, the whole transcriptional response of the D. radiodurans strain haboring pprI mutation, which plays an important role in radiation resistance, was analyzed by cDNA microarray. The anti-oxidant activity of the major carotenoid of D. radiodurans, deinoxanthin, was analyzed and the strain was constructed, in which the gene necessary for bio- synthesis of deinoxanthin is deleted. The response to cadmium of D. radiodurans was also investigated through cDNA microarray analysis. Radiogenic therapy, one of the cancer treatments, is designed to use radiation-inducible gene for the treatment. To develop the gene-transfer vehicle for radiogenic therapy, we have investigated the virulence mechanism of Salmonella, which is tumor-targeting bacteria and studied the synergistic effect of some anti-cancer agents on radiation treatment for cancer. Finally, we confirmed that irradiation could decompose a fungus toxin, patulin, into various harmless by-products.

  20. Chemosensitivity of irradiated resistant cells of multicellular spheroids in A549 lung adenocarcinoma

    International Nuclear Information System (INIS)

    Shi Degang; Shi Genming; Huang Gang

    2006-01-01

    Objective: To investigate the chemosensitivity of irradiated resistant cells of multicellular spheroids in A549 lung adenocarcinoma. Methods: The A549 irradiated resistant cells were the 10th regrowth generations after irradiated with 2.5 Gy of 6 MV X-ray, the control groups were A549 parent cells and MCFY/VCR resistant cells. The 6 kinds of chemotherapeutic drugs were DDP, VDS, 5-FU, HCP, MMC and ADM respectively, with verapamil (VPL) as reverse agent. The treatment effect was compared with MTT assay, and the multidrug resistant gene expressions of mdrl and MRP were measured with RT-PCR method. Results: A549 cells and irradiated resistant cells were resistant to DDP, but sensitivity to VDS,5-FU, HCP, MMC and ADM. The inhibitory rates of VPL to the above two cells were 98% and 25% respectively(P 2 -MG and MRP/β 2 -MG of all A549 cells were about 0 and 0.7 respectively, and those of MCFT/VCR cells were 35 and 4.36. Conclusion: The chemosensitivity of A549 irradiated resistant cells had not changed markedly, the decreased sensitivity to VPL could not be explained by the gene expression of mdrl and MRP. It is conferred that some kinds of changes in the cell membrane and decreased regrowth ability to result in resistance. Unlike multidrug resistance induced by chemotherapy, VPL may be not an ideal reverser to irradiated resistant cells. The new kinds of biological preparation should be sought to combine chemotherapy to treat recurring tumor with irradiated resistance. (authors)

  1. T cell resistance to activation by dendritic cells requires long-term culture in simulated microgravity

    Science.gov (United States)

    Bradley, Jillian H.; Stein, Rachel; Randolph, Brad; Molina, Emily; Arnold, Jennifer P.; Gregg, Randal K.

    2017-11-01

    activation of SMG-T cells occurred in SMG, the T cells produced less IL-2 than control T cell cultures upon incubation with PMA and ionomycin. Short-term (24 h) SMG culture and activation of T cells by DC resulted in enhanced IL-2 production compared to Static-T cells, however, when culture was extended to 120 h, SMG-T cells secreted significantly less IL-2 than Static-T cells. SMG-T cell IL-2 doubled upon stimulation of the DC prior to addition to the T cell culture but remained less than control. SMG-T cell resistance to activation appeared comparable to the phenomenon of T cell exhaustion observed in patients with chronic diseases or persistent tumors. That is, long-term culture of T cells in SMG resulted in increased expression of the inhibitory receptor, CTLA-4. Blockade of CTLA-4 interaction with DC ligands resulted in improved T cell IL-2 production. Overall, this is the first study to determine the efficacy of DC in activating peptide-specific T cells. Furthermore, the findings suggests that countermeasures to restore T cell responsiveness in astronauts during long-term spaceflight or those living in microgravity environments should target possible inhibitory pathways that arise on activated T cells following stimulation.

  2. T cell resistance to activation by dendritic cells requires long-term culture in simulated microgravity.

    Science.gov (United States)

    Bradley, Jillian H; Stein, Rachel; Randolph, Brad; Molina, Emily; Arnold, Jennifer P; Gregg, Randal K

    2017-11-01

    . When activation of SMG-T cells occurred in SMG, the T cells produced less IL-2 than control T cell cultures upon incubation with PMA and ionomycin. Short-term (24 h) SMG culture and activation of T cells by DC resulted in enhanced IL-2 production compared to Static-T cells, however, when culture was extended to 120 h, SMG-T cells secreted significantly less IL-2 than Static-T cells. SMG-T cell IL-2 doubled upon stimulation of the DC prior to addition to the T cell culture but remained less than control. SMG-T cell resistance to activation appeared comparable to the phenomenon of T cell exhaustion observed in patients with chronic diseases or persistent tumors. That is, long-term culture of T cells in SMG resulted in increased expression of the inhibitory receptor, CTLA-4. Blockade of CTLA-4 interaction with DC ligands resulted in improved T cell IL-2 production. Overall, this is the first study to determine the efficacy of DC in activating peptide-specific T cells. Furthermore, the findings suggests that countermeasures to restore T cell responsiveness in astronauts during long-term spaceflight or those living in microgravity environments should target possible inhibitory pathways that arise on activated T cells following stimulation. Copyright © 2017 The Committee on Space Research (COSPAR). Published by Elsevier Ltd. All rights reserved.

  3. Remodeling of the malaria parasite and host human red cell by vesicle amplification that induces artemisinin resistance.

    Science.gov (United States)

    Bhattacharjee, Souvik; Coppens, Isabelle; Mbengue, Alassane; Suresh, Niraja; Ghorbal, Mehdi; Slouka, Zdenek; Safeukui, Innocent; Tang, Hsin-Yao; Speicher, David W; Stahelin, Robert V; Mohandas, Narla; Haldar, Kasturi

    2018-03-15

    Artemisinin resistance threatens worldwide malaria control and elimination. Elevation of phosphatidylinositol-3-phosphate (PI3P) can induce resistance in blood stages of Plasmodium falciparum The parasite unfolded protein response (UPR) has also been implicated as a proteostatic mechanism that may diminish artemisinin-induced toxic proteopathy. How PI3P acts and its connection to the UPR remain unknown, although both are conferred by mutation in P falciparum Kelch13 (K13), the marker of artemisinin resistance. Here we used cryoimmunoelectron microscopy to show that K13 concentrates at PI3P tubules/vesicles of the parasite's endoplasmic reticulum (ER) in infected red cells. K13 colocalizes and copurifies with the major virulence adhesin PfEMP1. The PfEMP1-K13 proteome is comprehensively enriched in multiple proteostasis systems of protein export, quality control, and folding in the ER and cytoplasm and UPR. Synthetic elevation of PI3P that induces resistance in absence of K13 mutation also yields signatures of proteostasis and clinical resistance. These findings imply a key role for PI3P-vesicle amplification as a mechanism of resistance of infected red cells. As validation, the major resistance mutation K13C580Y quantitatively increased PI3P tubules/vesicles, exporting them throughout the parasite and the red cell. Chemical inhibitors and fluorescence microscopy showed that alterations in PfEMP1 export to the red cell and cytoadherence of infected cells to a host endothelial receptor are features of multiple K13 mutants. Together these data suggest that amplified PI3P vesicles disseminate widespread proteostatic capacity that may neutralize artemisinins toxic proteopathy and implicate a role for the host red cell in artemisinin resistance. The mechanistic insights generated will have an impact on malaria drug development. © 2018 by The American Society of Hematology.

  4. Development of a high strength, hydrogen-resistant austenitic alloy

    International Nuclear Information System (INIS)

    Chang, K.M.; Klahn, D.H.; Morris, J.W. Jr.

    1980-08-01

    Research toward high-strength, high toughness nonmagnetic steels for use in the retaining rings of large electrical generators led to the development of a Ta-modified iron-based superalloy (Fe-36 Ni-3 Ti-3 Ta-0.5 Al-1.3 Mo-0.3 V-0.01 B) which combines high strength with good toughness after suitable aging. The alloy did, however, show some degradation in fatigue resistance in gaseous hydrogen. This sensitivity was associated with a deformation-induced martensitic transformation near the fracture surface. The addition of a small amount of chromium to the alloy suppressed the martensite transformation and led to a marked improvement in hydrogen resistance

  5. miR-193b Modulates Resistance to Doxorubicin in Human Breast Cancer Cells by Downregulating MCL-1

    Directory of Open Access Journals (Sweden)

    Jingpei Long

    2015-01-01

    Full Text Available MicroRNAs (miRNAs family, which is involved in cancer development, proliferation, apoptosis, and drug resistance, is a group of noncoding RNAs that modulate the expression of oncogenes and antioncogenes. Doxorubicin is an active cytotoxic agent for breast cancer treatment, but the acquisition of doxorubicin resistance is a common and critical limitation to cancer therapy. The aim of this study was to investigate whether miR-193b mediated the resistance of breast cancer cells to doxorubicin by targeting myeloid cell leukemia-1 (MCL-1. In this study, we found that miR-193b levels were significantly lower in doxorubicin-resistant MCF-7 (MCF-7/DOXR cells than in the parental MCF-7 cells. We observed that exogenous miR-193b significantly suppressed the ability of MCF-7/DOXR cells to resist doxorubicin. It demonstrated that miR-193b directly targeted MCL-1 3′-UTR (3′-Untranslated Regions. Further studies indicated that miR-193b sensitized MCF-7/DOXR cells to doxorubicin through a mechanism involving the downregulation of MCL-1. Together, our findings provide evidence that the modulation of miR-193b may represent a novel therapeutic target for the treatment of breast cancer.

  6. Differential microRNA expression signatures and cell type-specific association with Taxol resistance in ovarian cancer cells

    Directory of Open Access Journals (Sweden)

    Kim YW

    2014-02-01

    downregulation of the two miRNAs was associated with better survival, perhaps increasing the sensitivity of cancer cells to Taxol. In the chemo-sensitive patient group, only miR-647 could be a prognosis marker. These miRNAs inhibit several interacting genes of p53 networks, especially in TUOS-3 and TUOS-4, and showed cell line-specific inhibition effects. Taken together, the data indicate that the three miRNAs are closely associated with Taxol resistance and potentially better prognosis factors. Our results suggest that these miRNAs were successfully and reliably identified and would be used in the development of miRNA therapies in treating ovarian cancer. Keywords: microRNA, ovarian cancer, Taxol resistance, Kaplan–Meier survival analysis

  7. Development of programmable multi-channel earth resistivity system

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Hyun Ki; Choi, Jong Ho; Park, In Wha [Korea Institute of Geology Mining and Materials, Taejon (Korea, Republic of)

    1996-12-01

    Maximum 256 channel digital-stacking automatic electrical earth resistivity meter is upgrade-developed and field-tested with two commercially available systems (OYO McOHM and ABEM Terrameter) for Schlumberger vertical sounding and dipole-dipole arrays. The results of three systems are very well coincident for several dummy resistors and Schlumberger array in field site. The developed system K-Ohm shows even more reasonable quality data in sensitive dipole-dipole array measurements in comparison with the electrical survey instruments of digital stacking type manufactured by other countries. New Important features of upgraded programmable K-Ohm system are as follows ; 1) Auto-electrode-switching control by Notebook printer port, 2) receiving signal measurement by Notebook serial port, 3) interactive automatic dipole-dipole measurement software with two apparent resistivity sections compared in one Notebook display to minimize noisy data in field, 4) auto-saved field memo at any time appending to acquired data, 5) max 500 V{sub p-p} 500 mA transmitter (measuring cycle S/W programmable), 6) low-drift sigma - delta 24 bit A/D 0.0015 % linearity error with zero-offset and full - scale gain autocalibration, 7) DC 12 v operated and TX-RX 7,000 V optical-isolated, 8) electrodes grounding auto-tested, user-oriented any array sequential programmable control software. Further study will be focused on higher power TX and stand alone TX-RX system, and micro-resistivity system for in-borehole resistivity imaging. (author). 8 refs., 9 figs.

  8. Analysis of radiation resistance of InGaP/GaAs dual-junction thin-film space solar cell

    International Nuclear Information System (INIS)

    Imaizumi, Mitsuru; Ohshima, Takeshi; Takamoto, Tatsuya

    2010-01-01

    Thin-film III-V multi-junction solar cells can realize the advantages of being high-efficiency and light-weight, as such these cells meets the requirement for higher specific power and lower stowage volume solar panels. Here we report the development results of an InGaP/GaAs thin-film dual-junction (TF2J) solar cell. In this paper, we study the radiation resistance of the TF2J cells with efficiency of 20-23% under AM0.1 sun at 25degC. The cells were subjected to proton irradiation with an energy range of 100keV-10MeV. The results were compared with the radiation resistance of a conventional InGaP/GaAs/Ge triple-junction (3J) cell. In the proton energy range of 200-400keV, radiation resistance of the TF2J cell is superior to that of the 3J cell. Particularly, the 1sc of the TF2J cell is significantly higher than that of the 3J cell after exposure to 380keV protons, which results in higher remaining factor of Pmax for the TF2J cell. In additions, Voc of the cells after the irradiations are almost equivalent, even though the TF2J cell is a dual-junction structure. The higher 1sc of the TF2J cell after irradiation is due to higher radiation resistance of the GaAs subcell according to the comparison of the spectral response. (author)

  9. Single cell transcriptome profiling of developing chick retinal cells.

    Science.gov (United States)

    Laboissonniere, Lauren A; Martin, Gregory M; Goetz, Jillian J; Bi, Ran; Pope, Brock; Weinand, Kallie; Ellson, Laura; Fru, Diane; Lee, Miranda; Wester, Andrea K; Liu, Peng; Trimarchi, Jeffrey M

    2017-08-15

    The vertebrate retina is a specialized photosensitive tissue comprised of six neuronal and one glial cell types, each of which develops in prescribed proportions at overlapping timepoints from a common progenitor pool. While each of these cells has a specific function contributing to proper vision in the mature animal, their differential representation in the retina as well as the presence of distinctive cellular subtypes makes identifying the transcriptomic signatures that lead to each retinal cell's fate determination and development challenging. We have analyzed transcriptomes from individual cells isolated from the chick retina throughout retinogenesis. While we focused our efforts on the retinal ganglion cells, our transcriptomes of developing chick cells also contained representation from multiple retinal cell types, including photoreceptors and interneurons at different stages of development. Most interesting was the identification of transcriptomes from individual mixed lineage progenitor cells in the chick as these cells offer a window into the cell fate decision-making process. Taken together, these data sets will enable us to uncover the most critical genes acting in the steps of cell fate determination and early differentiation of various retinal cell types. © 2017 Wiley Periodicals, Inc.

  10. Quantitative immunoproteomics analysis reveals novel MHC class I presented peptides in cisplatin-resistant ovarian cancer cells.

    Science.gov (United States)

    Shetty, Vivekananda; Nickens, Zacharie; Testa, James; Hafner, Julie; Sinnathamby, Gomathinayagam; Philip, Ramila

    2012-06-18

    Platinum-based chemotherapy is widely used to treat various cancers including ovarian cancer. However, the mortality rate for patients with ovarian cancer is extremely high, largely due to chemo-resistant progression in patients who respond initially to platinum based chemotherapy. Immunotherapy strategies, including antigen specific vaccines, are being tested to treat drug resistant ovarian cancer with variable results. The identification of drug resistant specific tumor antigens would potentially provide significant improvement in effectiveness when combined with current and emerging therapies. In this study, using an immunoproteomics method based on iTRAQ technology and an LC-MS platform, we identified 952 MHC class I presented peptides. Quantitative analysis of the iTRAQ labeled MHC peptides revealed that cisplatin-resistant ovarian cancer cells display increased levels of MHC peptides derived from proteins that are implicated in many important cancer pathways. In addition, selected differentially presented epitope specific CTL recognize cisplatin-resistant ovarian cancer cells significantly better than the sensitive cells. These over-presented, drug resistance specific MHC class I associated peptide antigens could be potential targets for the development of immunotherapeutic strategies for the treatment of ovarian cancer including the drug resistant phenotype. Copyright © 2012 Elsevier B.V. All rights reserved.

  11. Identification and validation of COX-2 as a co-target for overcoming cetuximab resistance in colorectal cancer cells.

    Science.gov (United States)

    Lu, Yang; Shi, Chunmei; Qiu, Songbo; Fan, Zhen

    2016-10-04

    Cetuximab, an epidermal growth factor receptor (EGFR)-blocking antibody, was approved for treatment of metastatic colorectal cancer over a decade ago; however, patients' responses to cetuximab vary substantially due to intrinsic and acquired resistance to cetuximab. Here, we report our findings using Affymetrix HG-U133A array to examine changes in global gene expression between DiFi, a human colorectal cancer cell line that is highly sensitive to cetuximab, and two other cell lines: DiFi5, a DiFi subline with acquired resistance to cetuximab, and DiFi-AG, a DiFi subline with acquired resistance to the EGFR tyrosine kinase inhibitor AG1478 but sensitivity to cetuximab. We identified prostaglandin-endoperoxide synthase 2 (PTGS2), which encodes cyclooxygenase-2 (COX-2), as the gene with the greatest difference between the cetuximab-resistant DiFi5 cells and the cetuximab-sensitive DiFi cells and DiFi-AG cells. Reverse transcription polymerase chain reaction and Western blotting validated upregulation of COX-2 in DiFi5 but not in DiFi or DiFi-AG cells. We developed COX-2 knockdown stable clones from DiFi5 cells and demonstrated that genetic knockdown of COX-2 partially re-sensitized DiFi5 cells to cetuximab. We further confirmed that cetuximab in combination with a COX-2 inhibitor led to cell death via apoptosis or autophagy not only in DiFi5 cells but also in another colorectal cancer cell line naturally resistant to cetuximab. Our findings support further evaluation of the strategy of combining cetuximab and a COX-2 inhibitor for treatment of metastatic colorectal cancer.

  12. Effects of bone marrow stromal cells and umbilical cord blood-derived stromal cells on daunorubicin-resistant residual Jurkat cells.

    Science.gov (United States)

    Liang, X; Hao, L; Chen, X; Zhang, X; Kong, P; Peng, X; Gao, L; Zhang, C; Wang, Q

    2010-11-01

    To observe the effects of the hematopoietic inductive microenvironment (HIM) simulated by stromal cells of different origins on daunorubicin-resistant residual Jurkat cells (Jurkat/DNR cells). Jurkat/DNR cells were cultured and identified. Human umbilical cord blood-derived stromal cells (UCBDSCs) and normal human bone marrow stromal cells (BMSCs) were isolated and cocultured with Jurkat/DNR cells. Jurkat/DNR cells were collected after 14 days of coculture and analyzed with regard to cell proliferation and differentiation abilities, apoptosis, drug sensitivity, and MRD1 multidrug resistance gene mRNA expression. UCBDSC-simulated HIM suppressed proliferation and promoted apoptosis, differentiation, and drug sensitivity of Jurkat/DNR cells more significantly than BMSC-simulated HIM. Both BMSCs and UCBDSCs reconstruct the leukemic HIM and reverse drug resistance in Jurkat/DNR cells. UCBDSCs reconstruct the leukemic HIM and reverse drug resistance more significantly than BMSCs. Copyright © 2010 Elsevier Inc. All rights reserved.

  13. Downregulation of taurine uptake in multidrug resistant Ehrlich ascites tumor cells

    DEFF Research Database (Denmark)

    Poulsen, K A; Litman, Thomas; Eriksen, J

    2002-01-01

    In daunorubicin resistant Ehrlich ascites tumor cells (DNR), the initial taurine uptake was reduced by 56% as compared to the parental, drug sensitive Ehrlich cells. Kinetic experiments indicated that taurine uptake in Ehrlich cells occurs via both high- and low-affinity transporters. The maximal...... rate constant for the initial taurine uptake was reduced by 45% (high-affinity system) and 49% (low affinity system) in the resistant subline whereas the affinity of the transporters to taurine was unchanged. By immunoblotting we identified 3 TauT protein bands in the 50-70 kDa region. A visible...... reduction in the intensity of the band with the lowest molecular weight was observed in resistant cells. Quantitative RT-PCR indicated a significant reduction in the amount of taurine transporter mRNA in the resistant cells. Drug resistance in DNR Ehrlich cells is associated with overexpression of the mdr1...

  14. Translational research in ovarian carcinoma : cell biological aspects of drug resistance and tumor aggressiveness

    NARCIS (Netherlands)

    Zee, Ate Gerard Jan van der

    1994-01-01

    In this thesis diverse cell biological features that in cultured (ovarian) tumor cells have been linked to drug resistance and/or tumor aggressiveness are studied in tumor specimens of epithelial ovarian carcinomas.

  15. Silencing ofECHDC1inhibits growth of gemcitabine-resistant bladder cancer cells.

    Science.gov (United States)

    Asai, Seiji; Miura, Noriyoshi; Sawada, Yuichiro; Noda, Terutaka; Kikugawa, Tadahiko; Tanji, Nozomu; Saika, Takashi

    2018-01-01

    Combined gemcitabine and cisplatin (GC) treatment is a first line chemotherapy for bladder cancer. However, acquired resistance to GC has been a major problem. To address the mechanism of gemcitabine resistance, and to identify potential biomarkers or target proteins for its therapy, we aimed to identify candidate proteins associated with gemcitabine resistance using proteomic analysis. We established gemcitabine-resistant human bladder cancer cell lines (UMUC3GR and HT1376GR) from gemcitabine-sensitive human bladder cancer cell lines (UMUC3 and HT1376). We compared the protein expression of parental and gemcitabine-resistant cell lines using isobaric tags for relative and absolute quantification (iTRAQ) and liquid chromatography tandem mass spectrometry. Among the identified proteins, ethylmalonyl-CoA decarboxylase (ECHDC1) expression was significantly increased in both of the gemcitabine-resistant cell lines compared to the respective parental cell lines. Silencing of ECHDC1 reduced ECHDC1 expression and significantly inhibited the proliferation of UMUC3GR cells. Furthermore, silencing of ECHDC1 induced upregulation of p27, which is critical for cell cycle arrest in the G1 phase, and induced G1 arrest. In conclusion, ECHDC1 expression is increased in gemcitabine-resistant bladder cancer cells, and is involved in their cell growth. ECHDC1, which is a metabolite proofreading enzyme, may be a novel potential target for gemcitabine-resistant bladder cancer therapy.

  16. Induction of ferroptotic cell death for overcoming cisplatin resistance of head and neck cancer.

    Science.gov (United States)

    Roh, Jong-Lyel; Kim, Eun Hye; Jang, Hye Jin; Park, Jin Young; Shin, Daiha

    2016-10-10

    Inhibition of key molecules related to ferroptosis, cystine/glutamate antiporter and glutathione peroxidase, may induce eradication of chemotherapy/radiotherapy-resistant cancer cells. The present study investigated whether ferroptosis could overcome head and neck cancer (HNC) resistance to cisplatin treatment. Three cisplatin-resistant HNC cell lines (AMC-HN3R, -HN4R, and -HN9R) and their parental lines were used. The effects of cystine and glutamate alteration and pharmacological and genetic inhibition of cystine/glutamate antiporter were assessed by measuring viability, death, reactive oxygen species production, protein expression, and preclinical mouse tumor xenograft models. Conditioned media with no cystine or glutamine excess induced ferroptosis of both cisplatin-sensitive and -resistant HNC cells without any apparent changes to necrosis and apoptosis markers. The cystine/glutamate antiporter inhibitors erastin and sulfasalazine inhibited HNC cell growth and accumulated lipid reactive oxygen species, thereby inducing ferroptosis. Genetic silencing of cystine/glutamate antiporter with siRNA or shRNA treatment also induced effective ferroptotic cell death of resistant HNC cells and enhanced the cisplatin cytotoxicity of resistant HNC cells. Pharmacological and genetic inhibition of cystine/glutamate antiporter significantly sensitized resistant HNC cells to cisplatin in vitro and in vivo. Pharmacological and genetic inhibition of cystine/glutamate antiporter overcomes the cisplatin resistance of HNC cells by inducing ferroptosis. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  17. Human hepatocellular carcinoma cell lines exhibit multidrug resistance unrelated to MRD1 gene expression.

    Science.gov (United States)

    Shen, D W; Lu, Y G; Chin, K V; Pastan, I; Gottesman, M M

    1991-03-01

    Multidrug resistance of human cancer cells may result from expression of P-glycoprotein, the product of the MRD1 gene, acting as an energy-dependent drug efflux pump. However, direct evidence that expression of the MDR1 gene contributes to the multidrug resistance of human liver carcinomas has not been established. In this study, we tested five cell lines derived from human hepatocellular carcinomas for sensitivity to a variety of drugs used widely as anticancer agents; these included vinblastine, doxorubicin, actinomycin D, mitomycin C, 5-fluorouracil, 6-mercaptopurine, melphalan, methotrexate, cis-platinum and etoposide (VP-16). All five hepatoma cell lines were resistant at different levels to these chemicals compared to human KB cells. Although it has been demonstrated that resistance to vinblastine, colchicine, doxorubicin and actinomycin D in human multidrug-resistant cells is associated with overexpression of P-glycoprotein, very little expression of P-glycoprotein was found in these human hepatoma cells. Neither verapamil nor quinidine, inhibitors of the drug efflux pump, were able to overcome multidrug resistance in hepatoma cells. These results indicate that the multidrug resistance phenotype in human hepatocellular carcinoma cells cannot be attributed to expression of the MDR1 gene, but that novel mechanisms may account for the resistance of these cancer cells.

  18. Gefitinib inhibits invasive phenotype and epithelial-mesenchymal transition in drug-resistant NSCLC cells with MET amplification.

    Directory of Open Access Journals (Sweden)

    Silvia La Monica

    Full Text Available Despite the initial response, all patients with epidermal growth factor receptor (EGFR-mutant non-small cell lung cancer (NSCLC eventually develop acquired resistance to EGFR tyrosine kinase inhibitors (TKIs. The EGFR-T790M secondary mutation is responsible for half of acquired resistance cases, while MET amplification has been associated with acquired resistance in about 5-15% of NSCLCs. Clinical findings indicate the retained addiction of resistant tumors on EGFR signaling. Therefore, we evaluated the molecular mechanisms supporting the therapeutic potential of gefitinib maintenance in the HCC827 GR5 NSCLC cell line harbouring MET amplification as acquired resistance mechanism. We demonstrated that resistant cells can proliferate and survive regardless of the presence of gefitinib, whereas the absence of the drug significantly enhanced cell migration and invasion. Moreover, the continuous exposure to gefitinib prevented the epithelial-mesenchymal transition (EMT with increased E-cadherin expression and down-regulation of vimentin and N-cadherin. Importantly, the inhibition of cellular migration was correlated with the suppression of EGFR-dependent Src, STAT5 and p38 signaling as assessed by a specific kinase array, western blot analysis and silencing functional studies. On the contrary, the lack of effect of gefitinib on EGFR phosphorylation in the H1975 cells (EGFR-T790M correlated with the absence of effects on cell migration and invasion. In conclusion, our findings suggest that certain EGFR-mutated patients may still benefit from a second-line therapy including gefitinib based on the specific mechanism underlying tumor cell resistance.

  19. Association between Twist and multidrug resistance gene-associated proteins in Taxol®-resistant MCF-7 cells and a 293 cell model of Twist overexpression.

    Science.gov (United States)

    Wang, Li; Tan, Rui-Zhi; Zhang, Zhi-Xia; Yin, Rui; Zhang, Yong-Liang; Cui, Wei-Jia; He, Tao

    2018-01-01

    Multidrug resistance (MDR) severely limits the effectiveness of chemotherapy. Previous studies have identified Twist as a key factor of acquired MDR in breast, gastric and prostate cancer. However, the underlying mechanisms of action of Twist in MDR remain unclear. In the present study, the expression levels of MDR-associated proteins, including lung resistance-related protein (LRP), topoisomerase IIα (TOPO IIα), MDR-associated protein (MRP) and P-glycoprotein (P-gp), and the expression of Twist in cancerous tissues and pericancerous tissues of human breast cancer, were examined. In order to simulate Taxol ® resistance in cells, a Taxol ® -resistant human mammary adenocarcinoma cell subline (MCF-7/Taxol ® ) was established by repeatedly exposing MCF-7 cells to high concentrations of Taxol ® (up to 15 µg/ml). Twist was also overexpressed in 293 cells by transfecting this cell line with pcDNA5/FRT/TO vector containing full-length hTwist cDNA to explore the dynamic association between Twist and MDR gene-associated proteins. It was identified that the expression levels of Twist, TOPO IIα, MRP and P-gp were upregulated and LRP was downregulated in human breast cancer tissues, which was consistent with the expression of these proteins in the Taxol ® -resistant MCF-7 cell model. Notably, the overexpression of Twist in 293 cells increased the resistance to Taxol ® , Trichostatin A and 5-fluorouracil, and also upregulated the expression of MRP and P-gp. Taken together, these data demonstrated that Twist may promote drug resistance in cells and cancer tissues through regulating the expression of MDR gene-associated proteins, which may assist in understanding the mechanisms of action of Twist in drug resistance.

  20. Xanthohumol, a Prenylated Chalcone from Hops, Inhibits the Viability and Stemness of Doxorubicin-Resistant MCF-7/ADR Cells

    Directory of Open Access Journals (Sweden)

    Ming Liu

    2016-12-01

    Full Text Available Xanthohumol is a unique prenylated flavonoid in hops (Humulus lupulus L. and beer. Xanthohumol has been shown to possess a variety of pharmacological activities. There is little research on its effect on doxorubicin-resistant breast cancer cells (MCF-7/ADR and the cancer stem-like cells exiting in this cell line. In the present study, we investigate the effect of xanthohumol on the viability and stemness of MCF-7/ADR cells. Xanthohumol inhibits viability, induces apoptosis, and arrests the cell cycle of MCF-7/ADR cells in a dose-dependent manner; in addition, xanthohumol sensitizes the inhibition effect of doxorubicin on MCF-7/ADR cells. Interestingly, we also find that xanthohumol can reduce the stemness of MCF-7/ADR cells evidenced by the xanthohumol-induced decrease in the colony formation, the migration, the percentage of side population cells, the sphere formation, and the down-regulation of stemness-related biomarkers. These results demonstrate that xanthohumol is a promising compound targeting the doxorubicin resistant breast cancer cells and regulating their stemness, which, therefore, will be applied as a potential candidate for the development of a doxorubicin-resistant breast cancer agent and combination therapy of breast cancer.

  1. Xanthohumol, a Prenylated Chalcone from Hops, Inhibits the Viability and Stemness of Doxorubicin-Resistant MCF-7/ADR Cells.

    Science.gov (United States)

    Liu, Ming; Yin, Hua; Qian, Xiaokun; Dong, Jianjun; Qian, Zhonghua; Miao, Jinlai

    2016-12-28

    Xanthohumol is a unique prenylated flavonoid in hops ( Humulus lupulus L.) and beer. Xanthohumol has been shown to possess a variety of pharmacological activities. There is little research on its effect on doxorubicin-resistant breast cancer cells (MCF-7/ADR) and the cancer stem-like cells exiting in this cell line. In the present study, we investigate the effect of xanthohumol on the viability and stemness of MCF-7/ADR cells. Xanthohumol inhibits viability, induces apoptosis, and arrests the cell cycle of MCF-7/ADR cells in a dose-dependent manner; in addition, xanthohumol sensitizes the inhibition effect of doxorubicin on MCF-7/ADR cells. Interestingly, we also find that xanthohumol can reduce the stemness of MCF-7/ADR cells evidenced by the xanthohumol-induced decrease in the colony formation, the migration, the percentage of side population cells, the sphere formation, and the down-regulation of stemness-related biomarkers. These results demonstrate that xanthohumol is a promising compound targeting the doxorubicin resistant breast cancer cells and regulating their stemness, which, therefore, will be applied as a potential candidate for the development of a doxorubicin-resistant breast cancer agent and combination therapy of breast cancer.

  2. Intrinsic mechanism of estradiol-induced apoptosis in breast cancer cells resistant to estrogen deprivation.

    Science.gov (United States)

    Lewis, Joan S; Meeke, Kathleen; Osipo, Clodia; Ross, Eric A; Kidawi, Noman; Li, Tianyu; Bell, Eric; Chandel, Navdeep S; Jordan, V Craig

    2005-12-07

    We previously developed an estrogen receptor (ER)-positive breast cancer cell line (MCF-7:5C) that is resistant to long-term estrogen deprivation and undergoes rapid and complete apoptosis in the presence of physiologic concentrations of 17beta-estradiol. Here, we investigated the role of the mitochondrial apoptotic pathway in this process. Apoptosis in MCF-7:5C cells treated with estradiol, fulvestrant, or vehicle (control) was investigated by annexin V-propidium iodide double staining and 4',6-diamidino-2-phenylindole (DAPI) staining. Apoptosis was also analyzed in MCF-7:5C cells transiently transfected with small interfering RNAs (siRNAs) to apoptotic pathway components. Expression of apoptotic pathway intermediates was measured by western blot analysis. Mitochondrial transmembrane potential (psim) was determined by rhodamine-123 retention assay. Mitochondrial pathway activity was determined by cytochrome c release and cleavage of poly(ADP-ribose) polymerase (PARP) protein. Tumorigenesis was studied in ovariectomized athymic mice that were injected with MCF-7:5C cells. Differences between the treatment groups and control group were determined by two-sample t test or one-factor analysis of variance. All statistical tests were two-sided. MCF-7:5C cells treated with estradiol underwent apoptosis and showed increased expression of proapoptotic proteins, decreased psim, enhanced cytochrome c release, and PARP cleavage compared with cells treated with fulvestrant or vehicle. Blockade of Bax, Bim, and p53 mRNA expression by siRNA reduced estradiol-induced apoptosis relative to control by 76% [95% confidence interval (CI) = 73% to 79%, P estradiol-induced apoptosis in long-term estrogen-deprived breast cancer cells. Physiologic concentrations of estradiol could potentially be used to induce apoptosis and tumor regression in tumors that have developed resistance to aromatase inhibitors.

  3. Role of SOX4 on DDP Resistance in Non-small Cell Lung Cancer Cell of A549

    OpenAIRE

    Wei LI; Xu LIU; Guoqian ZHANG; Linlin ZHANG

    2017-01-01

    Background and objective Lung cancer is one of the most serious disease and the incidence of non-small cell lung cancer (NSCLC) is the highest in lung cancer. The main reason for the failure of chemotherapy is the tolerance to cisplatin. Transcriptional regulator SOX4 plays an important role in the occurrence and development of many tumors, and regulates Wnt signaling pathway by regulating the expression of β-catenin. We aimed to investigate the role of SOX4 on cisplatin-resistance in NSCLC c...

  4. [Anthelmintic resistance in ruminants: development, diagnostics, and procedures].

    Science.gov (United States)

    Knubben-Schweizer, Gabriela; Pfister, Kurt

    2017-08-10

    Anthelmintic resistance of gastrointestinal nematodes in small ruminants, but also in cattle and horses, is now found worldwide. The reason for increasing anthelmintic resistance is, in particular, the extensive use of all the anthelmintic agents available on the market. A non-targeted use leads to the selection of naturally occurring resistance genes within parasite populations. The most practical method for evaluating the efficacy of an anthelmintic is the fecal egg-count reduction test. To reduce the rate of anthelmintic resistance development, the available active substances must be applied less and in a targeted manner. When applying targeted (selective) treatment, part of the herd is left untreated. Therefore, it is necessary to identify the animals that require treatment for health or economic reasons. To decide on anthelmintic treatment, findings can be collected from single animals or from a group of animals in a herd. To determine which groups of animals are to be treated within a herd (targeted treatment), pooled fecal samples (cattle and small ruminants), serum pepsinogen concentration (cattle), or Ostertagia ostertagi antibodies in the bulk milk (cattle) can be analyzed. For individual animal (targeted selective) treatment, criteria including fecal egg count (cattle and small ruminants), conjuctival color as an indicator for infection with Haemonchus contortus (FAMACHA ® , small ruminants), body condition in adult animals (small ruminants), weight gain in juvenile animals (cattle and small ruminants), and the consistency of the feces (small ruminants) are used. These decision criteria can also be combined to enhance the informative value. Furthermore, an efficacy test of the anthelmintics used should be performed regularly at the beginning of the pasture season. During the pasture season, a low infection pressure should be maintained by pasture management strategies. The goal of sustainable parasite management is the reduction of anthelmintic

  5. Cell to cell signalling during vertebrate limb bud development

    NARCIS (Netherlands)

    Panman, Lia

    2004-01-01

    Communication between cells is essential during embryonic development. The vertebrate limb bud provides us a model to study signalling interactions between cells during patterning of embryonic tissues and organogenesis. In chapter 1 I give an introduction about limb bud development that is focussed

  6. Resistance of a soybean cell line to oxyfluorfen by overproduction of mitochondrial protoporphyrinogen oxidase.

    Science.gov (United States)

    Warabi, E; Usui, K; Tanaka, Y; Matsumoto, H

    2001-08-01

    The diphenyl ether herbicide oxyfluorfen (2-chloro-4-trifluoromethylphenyl 3-ethoxy-4-nitrophenyl ether) inhibits protoporphyrinogen oxidase (Protox) which catalyzes the oxidation of protoporphyrinogen IX (Protogen) to protoporphyrin IX (Proto IX), the last step of the common pathway to chlorophyll and haeme biosynthesis. We have selected an oxyfluorfen-resistant soybean cell line by stepwise selection methods, and the resistance mechanism has been investigated. No growth inhibition was observed in resistant cells at a concentration of 10(-7) M oxyfluorfen, a concentration at which normal cells did not survive. While the degree of inhibition of total extractable Protox by oxyfluorfen was the same in both cell types, the enzyme activity in the mitochondrial fraction from non-treated resistant cells was about nine-fold higher than that from normal cells. Northern analysis of mitochondrial Protox revealed that the concentration of mitochondrial Protox mRNA was much higher in resistant cells than that in normal cells. There were no differences in the absorption and metabolic breakdown of oxyfluorfen. The growth of resistant cells was also insensitive to oxadiazon [5-tert-butyl-3-(2,4-dichloro-5-isopropoxyphenyl)-1,3,4-oxadiazol-2-(3H)- one], the other chemical class of Protox inhibitor. Therefore, the resistance of the selected soybean cell line to oxyfluorfen is probably mainly due to the overproduction of mitochondrial Protox.

  7. Binding of paraquat to cell walls of paraquat resistant and susceptible biotypes of Hordeum glaucum

    International Nuclear Information System (INIS)

    Alizadeh, H.M.; Preston, C.; Powles, S.B.

    1997-01-01

    Full text: Paraquat is a widely used, non-selective, light activated contact herbicide acting as a photosystem electron acceptor. Resistance to paraquat in weed species has occurred in Australia and world-wide following extensive use of this herbicide. The mechanism of resistance to paraquat in 'Hordeum glaucum' is correlated with reduced herbicide translocation and may be due to sequestration of herbicide away from its site of action by either binding to cell walls or other means. We measured paraquat binding to a cell wall fraction in resistant and susceptible biotypes of H. glaucum to determine whether differences in binding of paraquat to cell walls could explain herbicide resistance. The cell wall fraction was isolated from leaves of resistant and susceptible biotypes and incubated with 14 C-labelled paraquat. Of the total paraquat - absorbed by a cell wall preparation, about 80% remains strongly bind to the cell wall and doesn't readily exchange with solution in the absence of divalent cations. Divalent cations (Ca 2+ ,putrescine and paraquat) can competitively exchange for paraquat tightly bound to the cell wall. From kinetic experiments it seems that there are two types of binding sites in the cell wall with different affinities for paraquat. No significant differences between cell wall, characteristics of resistant and susceptible biotypes of H. glaucum have been found in any of our experiments. Therefore, increased binding of paraquat to the cell wall appears not to be a mechanism for exclusion of paraquat in resistant biotype

  8. [Development of a Fluorescence Probe for Live Cell Imaging].

    Science.gov (United States)

    Shibata, Aya

    2017-01-01

     Probes that detect specific biological materials are indispensable tools for deepening our understanding of various cellular phenomena. In live cell imaging, the probe must emit fluorescence only when a specific substance is detected. In this paper, we introduce a new probe we developed for live cell imaging. Glutathione S-transferase (GST) activity is higher in tumor cells than in normal cells and is involved in the development of resistance to various anticancer drugs. We previously reported the development of a general strategy for the synthesis of probes for detection of GST enzymes, including fluorogenic, bioluminogenic, and 19 F-NMR probes. Arylsulfonyl groups were used as caging groups during probe design. The fluorogenic probes were successfully used to quantitate very low levels of GST activity in cell extracts and were also successfully applied to the imaging of microsomal MGST1 activity in living cells. The bioluminogenic and 19 F-NMR probes were able to detect GST activity in Escherichia coli cells. Oligonucleotide-templated reactions are powerful tools for nucleic acid sensing. This strategy exploits the target strand as a template for two functionalized probes and provides a simple molecular mechanism for multiple turnover reactions. We developed a nucleophilic aromatic substitution reaction-triggered fluorescent probe. The probe completed its reaction within 30 s of initiation and amplified the fluorescence signal from 0.5 pM target oligonucleotide by 1500 fold under isothermal conditions. Additionally, we applied the oligonucleotide-templated reaction for molecular releasing and peptide detection.

  9. Development of Proliferation Resistance Assessment Methodology Based on International Standards

    International Nuclear Information System (INIS)

    Lee, Yong Deok; Lee, Jung Won; Lee, Kwang Seok

    2009-03-01

    Proliferation resistance is one of the requirement to be met in GEN IV and INPRO for next generation nuclear energy system. Internationally, the evaluation methodology on PR had been already initiated from 1980, but the systematic development was started at 2000s. In Korea, for the export of nuclear energy system and the increase of international credibility and transparence of domestic nuclear system and fuel cycle development, the independent development of PR evaluation methodology was started in 2007 as a nuclear long term R and D project and the development is being performed for the model of PR evaluation methodology. In 1st year, comparative study of GEN-IV/INPRO, PR indicator development, quantification of indicator and evaluation model development, analysis of technology system and international technology development trend had been performed. In 2nd year, feasibility study of indicator, allowable limit of indicator, review of technical requirement of indicator were done. The results of PR evaluation must be applied in the beginning of conceptual design of nuclear system. Through the technology development of PR evaluation methodology, the methodology will be applied in the regulatory requirement for authorization and permission to be developed

  10. 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.

  11. Reduced expression of bax in small cell lung cancer cells is not sufficient to induce cisplatin-resistance

    Directory of Open Access Journals (Sweden)

    Biagosch J

    2010-10-01

    Full Text Available Abstract Resistance to cisplatin in the course of chemotherapy contributes to the poor prognosis of small cell lung cancer (SCLC. B cell lymphoma-2 is the founding member of a large family of proteins that either promote or inhibit apoptosis. We aimed at investigating if the pro-apoptotic members Bad, Bax, Bim and Bid are involved in cisplatin-resistance. Cisplatin-resistance in the SCLC cell line H1339 was induced by repetitive exposure to cisplatin. Protein expression was quantified by Western Blot and immuno-fluorescence analysis. Protein expression was altered using siRNA interference. Four "cycles" of 0.5 μg/ml cisplatin led to partial cisplatin-resistance in H1339 cells. The expression of Bad, Bim and Bid was comparable in naïve and resistant cells while the expression of Bax was reduced in the resistant clone. But, reducing Bax expression in naïve cells did not lead to altered cisplatin sensitivity neither in H1339 nor in H187 SCLC cells. We conclude that the reduced Bax expression after exposure to cisplatin is not sufficient to induce cis-platin-resistance in SCLC cells.

  12. Corrosion-resistant, electrically-conductive plate for use in a fuel cell stack

    Science.gov (United States)

    Carter, J David [Bolingbrook, IL; Mawdsley, Jennifer R [Woodridge, IL; Niyogi, Suhas [Woodridge, IL; Wang, Xiaoping [Naperville, IL; Cruse, Terry [Lisle, IL; Santos, Lilia [Lombard, IL

    2010-04-20

    A corrosion resistant, electrically-conductive, durable plate at least partially coated with an anchor coating and a corrosion resistant coating. The corrosion resistant coating made of at least a polymer and a plurality of corrosion resistant particles each having a surface area between about 1-20 m.sup.2/g and a diameter less than about 10 microns. Preferably, the plate is used as a bipolar plate in a proton exchange membrane (PEMFC) fuel cell stack.

  13. Development of high energy radiation resistant elastomeric composites

    International Nuclear Information System (INIS)

    Shah, C.; Patni, M.J.; Pandya, M.V.; Desai, M.R.

    1992-01-01

    Stabilizer formulations are developed for the elastomeric composites which can withstand high energy radiations to the total dose of 200 MRads. The elastomeric materials used are general purpose formulations based on Ethylene propylene diene (EPDM) and Chlorosulfonated polyethylene (CSP). The stabilizers are synthesized from highly aromatic ring compounds in the oligomeric and polymeric form, in the laboratory. The polymeric stabilizers are found to have better radiation resistance compared to the former one when the performance was evaluated using standard methodology. Dielectric analysis, FTIR and wide angle x-ray diffraction are used to follow the physico-chemical changes taking place in the bulk when subjected to the performance test

  14. pH regulation in sensitive and multidrug resistant Ehrlich ascites tumor cells

    DEFF Research Database (Denmark)

    Litman, Thomas; Pedersen, S F; Kramhøft, B

    1998-01-01

    Maintenance and regulation of intracellular pH (pHi) was studied in wild-type Ehrlich ascites tumor cells (EHR2) and five progressively daunorubicin-resistant, P-glycoprotein (P-gp)-expressing strains, the maximally resistant of which is EHR2/1.3. Steady-state pHi was similar in cells expressing...

  15. Effect of iron on pancreatic beta cell function and insulin resistance

    African Journals Online (AJOL)

    Dr Olaleye

    the incidence of diabetes mellitus was investigated on the pancreatic beta cell function and insulin resistance in normal ... hyperglycaemia, insulin resistance, hyperinsulinaemia, inflammation and pancreatic beta cell dysfunction thus predisposing the ..... and antioxidant status in alpha-thalassemia major: iron overload and ...

  16. Role of multidrug resistance protein (MRP) in glutathione S-conjugate transport in mammalian cells

    NARCIS (Netherlands)

    Muller, M; deVries, EGE; Jansen, PLM

    1996-01-01

    The human multidrug resistance protein (MRP), a 190-kDa member of the ABC-protein superfamily, is an ATP-dependent glutathione S-conjugate carrier (GS-X pump) and is present in membranes of many, if not all, cells, Overexpression of MRP in tumor cells contributes to resistance to natural product

  17. Role of multidrug resistance protein (MRP) in glutathione S-conjugate transport in mammalian cells

    NARCIS (Netherlands)

    Müller, M.; de Vries, E. G.; Jansen, P. L.

    1996-01-01

    The human multidrug resistance protein (MRP), a 190-kDa member of the ABC-protein superfamily, is an ATP-dependent glutathione S-conjugate carrier (GS-X pump) and is present in membranes of many, if not all, cells. Overexpression of MRP in tumor cells contributes to resistance to natural product

  18. MRP proteins as potential mediators of heavy metal resistance in zebrafish cells.

    Science.gov (United States)

    Long, Yong; Li, Qing; Wang, Youhui; Cui, Zongbin

    2011-04-01

    Acquired resistance of mammalian cells to heavy metals is closely relevant to enhanced expression of several multidrug resistance-associated proteins (MRP), but it remains unclear whether MRP proteins confer resistance to heavy metals in zebrafish. In this study, we obtained zebrafish (Danio rerio) fibroblast-like ZF4 cells with resistance to toxic heavy metals after chronic cadmium exposure and selection for 6months. These cadmium-resistant cells (ZF4-Cd) were maintained in 5μM cadmium and displayed cross-resistance to cadmium, mercury, arsenite and arsenate. ZF4-Cd cells remained the resistance to heavy metals after protracted culture in cadmium-free medium. In comparison with ZF4-WT cells, ZF4-Cd cells exhibited accelerated rate of cadmium excretion, enhanced activity of MRP-like transport, elevated expression of abcc2, abcc4 and mt2 genes, and increased content of cellular GSH. Inhibition of MRP-like transport activity, GSH biosynthesis and GST activity significantly attenuated the resistance of ZF4-Cd cells to heavy metals. The results indicate that some of MRP transporters are involved in the efflux of heavy metals conjugated with cellular GSH and thus play crucial roles in heavy metal detoxification of zebrafish cells. Copyright © 2010 Elsevier Inc. All rights reserved.

  19. Stimulation of cytolytic T lymphocytes by azaguanine-resistant mouse tumor cells in selective hat medium

    International Nuclear Information System (INIS)

    Snick, J. van; Uyttenhove, C.; Pel, A. van; Boon, T.

    1981-01-01

    Primed syngeneic or umprimed allogeneic mouse spleen cells were stimulated with azaguanine-resistant P815 tumor cells that were killed by the addition of aminopterin to the stimulation medium. The recovery of lymphocytes and their cytolytic activity and specificity were similar to those obtained after stimulation with irradiated cells. This method conveniently replaces the inactivation of stimulatory cells by irradiation or mitomycin treatment. Moreover, it has the advantage of inactivating not only the stimulatory cells but also the tumor cells that often contaminate the spleens of tumor-bearing animals, provided these animals have been inoculated with azaguanine-resistant tumor cell mutants. (Auth.)

  20. Effect of operating current dependent series resistance on the fill factor of a solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Dadu, Meena; Kapoor, A.; Tripathi, K.N. [Department of Electronic Science, University of Delhi, South Campus, Benito Juarez road, -110 021 New Delhi (India)

    2002-02-01

    The fill factor of a solar cell depends upon the series resistance, reverse saturation current, diode quality factor, operating current and voltage. Since the series resistance itself depends upon the operating current (or voltage), it makes the evaluation of fill factor very complicated. In this paper, we have evaluated the fill factor of a solar cell, taking into account operating current dependence of the series resistance.

  1. K562 human erythroleukemia cell variants resistant to growth inhibition by butyrate have deficient histone acetylation.

    OpenAIRE

    Ohlsson-Wilhelm, B M; Farley, B A; Kosciolek, B; La Bella, S; Rowley, P T

    1984-01-01

    K562 is an established human erythroleukemia cell line, inducible for hemoglobin synthesis by a variety of compounds including n-butyrate. To elucidate the role of butyrate-induced histone acetylation in the regulation of gene expression in K562 cells, we isolated 20 variants resistant to the growth inhibitory effect of butyrate. Four variants having different degrees of resistance were selected for detailed study. All four were found to be resistant to the hemoglobin-inducing effect of butyr...

  2. Overcoming cisplatin resistance of ovarian cancer cells by targeting HIF-1-regulated cancer metabolism

    OpenAIRE

    Ai, Zhihong; Lu, Yang; Qiu, Songbo; Fan, Zhen

    2016-01-01

    Cisplatin is currently one of the most effective chemotherapeutic drugs used for treating ovarian cancer; however, resistance to cisplatin is common. In this study, we explored an experimental strategy for overcoming cisplatin resistance of human ovarian cancer from the new perspective of cancer cell metabolism. By using two pairs of genetically matched cisplatin-sensitive and cisplatin-resistant ovarian cancer cell lines, we tested the hypothesis that downregulating hypoxia-inducible factor-...

  3. Phenethyl Isothiocyanate Induces Apoptotic Cell Death Through the Mitochondria-dependent Pathway in Gefitinib-resistant NCI-H460 Human Lung Cancer Cells In Vitro.

    Science.gov (United States)

    Hsia, Te-Chun; Huang, Yi-Ping; Jiang, Yi-Wen; Chen, Hsin-Yu; Cheng, Zheng-Yu; Hsiao, Yung-Ting; Chen, Cheng-Yen; Peng, Shu-Fen; Chueh, Fu-Shin; Chou, Yu-Cheng; Chung, Jing-Gung

    2018-04-01

    Some lung cancer patients treated with gefitinib develop resistance to this drug resulting in unsatisfactory treatment outcomes. Phenethyl isothiocyanate (PEITC), present in our common cruciferous vegetables, exhibits anticancer activities in many human cancer cell lines. Currently, there is no available information on the possible modification of gefitinib resistance of lung cancer in vitro by PEITC. Thus, the effects of PEITC on gefitinib resistant lung cancer NCI-H460 cells were investigated in vitro. The total cell viability, apoptotic cell death, production of reactive oxygen species (ROS) and Ca 2+ , levels of mitochondria membrane potential (ΔΨ m ) and caspase-3, -8 and -9 activities were measured by flow cytometry assay. PEITC induced chromatin condensation was examined by DAPI staining. PEITC-induced cell morphological changes, decreased total viable cell number and induced apoptotic cell death in NCI-H460 and NCI-H460/G cells. PEITC decreased ROS production in NCI-H460 cells, but increased production in NCI-H460/G cells. PEITC increased Ca 2+ production, decreased the levels of ΔΨ m and increased caspase-3, -8 and -9 activities in both NCI-H460 and NCI-H460/G cells. Western blotting was used to examine the effect of apoptotic cell death associated protein expression in NCI-H460 NCI-H460/G cells after exposure to PEITC. Results showed that PEITC increased expression of cleaved caspase-3, PARP, GADD153, Endo G and pro-apoptotic protein Bax in NCI-H460/G cells. Based on these results, we suggest that PEITC induces apoptotic cell death via the caspase- and mitochondria-dependent pathway in NCI-H460/G cells. Copyright© 2018, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.

  4. Mobile fuel cell development at Siemens

    Science.gov (United States)

    Strasser, K.

    1992-01-01

    Recent mobile fuel cell developments are reported with particular attention given to fuel cell technology based on photon exchange membrane (PEM) as electrolyte. Advantages of PEM fuel cells over conventional systems include their overload capacity, low power degradation, long lifetime, and the possibility to operate the fuel cell at different temperatures. The PEM fuel cells can be operated with CO2-containing reactants and have a considerable potential for increasing power. These facts make it possible to construct energy storage systems with H2/air fuel cells for electric cars or long-term storage facilities for regenerative energy systems.

  5. Cell surface alteration in Epstein-Barr virus-transformed cells from patients with extreme insulin resistance

    International Nuclear Information System (INIS)

    Gorden, D.L.; Robert, A.; Moncada, V.Y.; Taylor, S.I.; Muehlhauser, J.C.; Carpentier, J.L.

    1990-01-01

    An abnormality was detected in the morphology of the cell surface of Epstein-Barr virus-transformed lymphocytes of patients with genetic forms of insulin resistance. In cells from two patients with leprechaunism and two patients with type A extreme insulin resistance, scanning electron microscopy demonstrated a decrease in the percentage of the cell surface occupied by microvilli in cells from the patients with leprechaunism and type A insulin resistance compared with control cells. When cells from a healthy control subject and one of the patients with leprechaunism (Lep/Ark-1) were incubated with 125 I-labeled insulin, there was a decrease in the percentage of 125 I-insulin associated with microvilli on the cell surface. Thus, the decreased localization of insulin receptors with the microvillous region of the cell surface was in proportion to the decrease in microvilli

  6. Development of high-performance low-reflection rugged resistive touch screens for military displays

    Science.gov (United States)

    Wang, Raymond; Wang, Minshine; Thomas, John; Wang, Lawrence; Chang, Victor

    2010-04-01

    Just as iPhones with sophisticated touch interfaces have revolutionised the human interface for the ubiquitous cell phone, the Military is rapidly adopting touch-screens as a primary interface to their computers and vehicle systems. This paper describes the development of a true military touch interface solution from an existing industrial design. We will report on successful development of 10.4" and 15.4" high performance rugged resistive touch panels using IAD sputter coating. Low reflectance (specular impact, dust, and chemical resistant surface finishes. These touch panels were qualified over a wide operational temperature range, -51°C to +80°C specifically for military and rugged industrial applications.

  7. Photodynamic responsiveness of human leukemia Jurkat/A4 cells with multidrug resistant phenotype.

    Science.gov (United States)

    Philchenkov, A A; Shishko, E D; Zavelevich, M P; Kuiava, L M; Miura, K; Blokhin, D Y; Shton, I O; Gamaleia, N F

    2014-12-01

    Photodynamic therapy (PDT) is considered as a possible alternative approach to overcoming multidrug resistance (MDR). Analysis of cross-resistance to PDT in cells with different MDR pathways and resistance levels seems to be advantageous for elucidating the general mechanisms of cancer cell resistance to various treatment modalities. The aim of the study was to clarify whether the Jurkat/A4 leukemia cells with MDR phenotype are cross-resistant to PDT. Human T-cell acute lymphoblastic leukemia line Jurkat and Jurkat/A4 subline with MDR phenotype were used. 5-Aminolevulinic acid (ALA) and Photolon (a complex of chlorine-e6 and polyvinylpyrrolidone; PL) or gold nanocomposite of PL were applied as photosensitizers. The cells were pretreated with photosensitizers and exposed to laser radiation at corresponding wavelengths. The phototoxicity was assessed in trypan blue exclusion test. The hypodiploid cell fraction was analyzed by flow cytometry of propidium iodide-stained cells. Expression of genes related to PDT resistance was analyzed by microarray technique with Affymetrix U133A chips. ALA-mediated PDT resulted in dose-dependent cell death in both lines, the relative photodynamic efficacy in Jurkat/A4 cells being inferior to that in the parental Jurkat cells. There was no correlation between phototoxicity and apoptosis induction both in Jurkat and Jurkat/A4 cells. PL-mediated general phototoxicity in Jurkat cells amounted up to 75% at the maximal photosensitizer dose with about 40% of apoptotic death fraction. PL-phototoxicity in Jurkat/A4 cells was considerably lower. In contrast to Jurkat cells, PL-gold composite did not increase the efficacy of photosensitization as compared to free PL in Jurkat/A4 cells. Multidrug-resistant Jurkat/A4 cells exhibit reduced sensitivity to phototoxic effect in comparison with parental Jurkat cells independently of nature of the photosensitizer being assayed.

  8. Inhibition of β-Catenin to Overcome Endocrine Resistance in Tamoxifen-Resistant Breast Cancer Cell Line.

    Science.gov (United States)

    Won, Hye Sung; Lee, Kyung Mee; Oh, Ju Eon; Nam, Eun Mi; Lee, Kyoung Eun

    2016-01-01

    The β-catenin signaling is important in cell growth and differentiation and is frequently dysregulated in various cancers. The most well-known mechanism of endocrine resistance is cross-talk between the estrogen receptor (ER) and other growth factor signaling, such as phosphatidylinositol-3-kinase (PI3K)/Akt and the mammalian target of rapamycin (mTOR) signaling pathway. In the present study, we investigated whether β-catenin could be a potential target to overcome endocrine resistance in breast cancer. We established tamoxifen-resistant (TamR) cell line via long-term exposure of MCF-7 breast cancer cells to gradually increasing concentrations of tamoxifen. The levels of protein expression and mRNA transcripts were determined using western blot analysis and real-time quantitative PCR. The transcriptional activity of β-catenin was measured using luciferase activity assay. TamR cells showed a mesenchymal phenotype, and exhibited a relatively decreased expression of ER and increased expression of human epidermal growth factor receptor 2 and the epidermal growth factor receptor. We confirmed that the expression and transcriptional activity of β-catenin were increased in TamR cells compared with control cells. The expression and transcriptional activity of β-catenin were inhibited by β-catenin small-molecule inhibitor, ICG-001 or β-catenin siRNA. The viability of TamR cells, which showed no change after treatment with tamoxifen, was reduced by ICG-001 or β-catenin siRNA. The combination of ICG-001 and mTOR inhibitor, rapamycin, yielded an additive effect on the inhibition of viability in TamR cells. These results suggest that β-catenin plays a role in tamoxifen-resistant breast cancer, and the inhibition of β-catenin may be a potential target in tamoxifen-resistant breast cancer.

  9. Inhibition of β-Catenin to Overcome Endocrine Resistance in Tamoxifen-Resistant Breast Cancer Cell Line.

    Directory of Open Access Journals (Sweden)

    Hye Sung Won

    Full Text Available The β-catenin signaling is important in cell growth and differentiation and is frequently dysregulated in various cancers. The most well-known mechanism of endocrine resistance is cross-talk between the estrogen receptor (ER and other growth factor signaling, such as phosphatidylinositol-3-kinase (PI3K/Akt and the mammalian target of rapamycin (mTOR signaling pathway. In the present study, we investigated whether β-catenin could be a potential target to overcome endocrine resistance in breast cancer.We established tamoxifen-resistant (TamR cell line via long-term exposure of MCF-7 breast cancer cells to gradually increasing concentrations of tamoxifen. The levels of protein expression and mRNA transcripts were determined using western blot analysis and real-time quantitative PCR. The transcriptional activity of β-catenin was measured using luciferase activity assay.TamR cells showed a mesenchymal phenotype, and exhibited a relatively decreased expression of ER and increased expression of human epidermal growth factor receptor 2 and the epidermal growth factor receptor. We confirmed that the expression and transcriptional activity of β-catenin were increased in TamR cells compared with control cells. The expression and transcriptional activity of β-catenin were inhibited by β-catenin small-molecule inhibitor, ICG-001 or β-catenin siRNA. The viability of TamR cells, which showed no change after treatment with tamoxifen, was reduced by ICG-001 or β-catenin siRNA. The combination of ICG-001 and mTOR inhibitor, rapamycin, yielded an additive effect on the inhibition of viability in TamR cells.These results suggest that β-catenin plays a role in tamoxifen-resistant breast cancer, and the inhibition of β-catenin may be a potential target in tamoxifen-resistant breast cancer.

  10. Ameliorative effects of polyunsaturated fatty acids against palmitic acid-induced insulin resistance in L6 skeletal muscle cells

    Directory of Open Access Journals (Sweden)

    Sawada Keisuke

    2012-03-01

    Full Text Available Abstract Background Fatty acid-induced insulin resistance and impaired glucose uptake activity in muscle cells are fundamental events in the development of type 2 diabetes and hyperglycemia. There is an increasing demand for compounds including drugs and functional foods that can prevent myocellular insulin resistance. Methods In this study, we established a high-throughput assay to screen for compounds that can improve myocellular insulin resistance, which was based on a previously reported non-radioisotope 2-deoxyglucose (2DG uptake assay. Insulin-resistant muscle cells were prepared by treating rat L6 skeletal muscle cells with 750 μM palmitic acid for 14 h. Using the established assay, the impacts of several fatty acids on myocellular insulin resistance were determined. Results In normal L6 cells, treatment with saturated palmitic or stearic acid alone decreased 2DG uptake, whereas unsaturated fatty acids did not. Moreover, co-treatment with oleic acid canceled the palmitic acid-induced decrease in 2DG uptake activity. Using the developed assay with palmitic acid-induced insulin-resistant L6 cells, we determined the effects of other unsaturated fatty acids. We found that arachidonic, eicosapentaenoic and docosahexaenoic acids improved palmitic acid-decreased 2DG uptake at lower concentrations than the other unsaturated fatty acids, including oleic acid, as 10 μM arachidonic acid showed similar effects to 750 μM oleic acid. Conclusions We have found that polyunsaturated fatty acids, in particular arachidonic and eicosapentaenoic acids prevent palmitic acid-induced myocellular insulin resistance.

  11. Reversal of resistance by GF120918 in cell lines expressing the ABC half-transporter, MXR

    DEFF Research Database (Denmark)

    de Bruin, M; Miyake, K; Litman, Thomas

    1999-01-01

    The emergence of several newly identified members of the ABC transporter family has necessitated the development of antagonists that are able to inhibit more than one transporter. We assessed the ability of the chemosensitizer GF120918 to function as a multispecific antagonist using cytotoxicity...... assays, rhodamine and calcein efflux assays, and confocal microscopy in cell lines expressing different multidrug resistance transporters. At a concentration of 1 microM in cytotoxicity assays, GF120918 was able to sensitize both S1-B1-20, a subline expressing P-glycoprotein (Pgp), and S1-M1......-80, a subline expressing a newly identified mitoxantrone transporter, MXR. GF120918 was ineffective in sensitizing MRP-overexpressing MCF-7 VP-16 cells to etoposide as determined by cytotoxicity studies. In flow cytometry experiments, rhodamine 123 efflux in S1-B1-20 cells was decreased at GF120918...

  12. Nuclear microanalysis of platinum and trace elements in cisplatin-resistant human ovarian adenocarcinoma cells

    Science.gov (United States)

    Moretto, P.; Ortega, R.; Llabador, Y.; Simonoff, M.; Bénard, J.; Moretto, Ph.

    1995-09-01

    Macro-and Micro-PIXE analysis were applied to study the mechanisms of cellular resistance to cisplatin, a chemotherapeutic agent, widely used nowadays for the treatment of ovarian cancer. Two cultured cell lines, a cisplatin-sensitive and a resistant one, were compared for their trace elements content and platinum accumulation following in vitro exposure to the drug. Bulk analysis revealed significant differences in copper and iron content between the two lines. Subsequent individual cell microanalysis permitted us to characterize the response of the different morphological cell types of the resistant line. This study showed that the metabolism of some trace metals in cisplatin-resistant cells could be affected but the exact relationship with the resistant phenotype remains to be determined. From a technical point of view, this experiment demonstrated that an accurate measurement of trace elements could be derived from nuclear microprobe analysis of individual cell.

  13. The establishment of insulin resistance model in FL83B and L6 cell

    Science.gov (United States)

    Liu, Lanlan; Han, Jizhong; Li, Haoran; Liu, Mengmeng; Zeng, Bin

    2017-10-01

    The insulin resistance models of mouse liver epithelial and rat myoblasts cells were induced by three kinds of inducers: dexamethasone, high insulin and high glucose. The purpose is to select the optimal insulin resistance model, to provide a simple and reliable TR cell model for the study of the pathogenesis of TR and the improvement of TR drugs and functional foods. The MTT method is used for toxicity screening of three compounds, selecting security and suitable concentration. We performed a Glucose oxidase peroxidase (GOD-POD) method involving FL83B and L6 cell with dexamethasone, high insulin and high glucose-induced insulin resistance. Results suggested that FL83B cells with dexamethasone-induced (0.25uM) were established insulin resistance and L6 cells with high-glucose (30mM) and dexamethasone-induced (0.25uM) were established insulin resistance.

  14. Analysis of Distinct Roles of CaMKK Isoforms Using STO-609-Resistant Mutants in Living Cells.

    Science.gov (United States)

    Fujiwara, Yuya; Hiraoka, Yuri; Fujimoto, Tomohito; Kanayama, Naoki; Magari, Masaki; Tokumitsu, Hiroshi

    2015-06-30

    To assess the isoform specificity of the Ca(2+)/calmodulin-dependent protein kinase kinase (CaMKK)-mediated signaling pathway using a CaMKK inhibitor (STO-609) in living cells, we have established A549 cell lines expressing STO-609-resistant mutants of CaMKK isoforms. Following serial mutagenesis studies, we have succeeded in obtaining an STO-609-resistant CaMKKα mutant (Ala292Thr/Leu233Phe) and a CaMKKβ mutant (Ala328Thr/Val269Phe), which showed sensitivity to STO-609 that was 2-3 orders of magnitude lower without an appreciable effect on kinase activity or CaM requirement. These results are consistent with the results obtained for CaMKK activities in the extracts of A549 cells stably expressing the mutants of CaMKK isoforms. Ionomycin-induced 5'-AMP-activated protein kinase (AMPK) phosphorylation at Thr172 in A549 cells expressing either the wild-type or the STO-609-resistant mutant of CaMKKα was completely suppressed by STO-609 treatment but resistant to the inhibitor in the presence of the CaMKKβ mutant (Ala328Thr/Val269Phe). This result strongly suggested that CaMKKβ is responsible for ionomycin-induced AMPK activation, which supported previous reports. In contrast, ionomycin-induced CaMKIV phosphorylation at Thr196 was resistant to STO-609 treatment in A549 cells expressing STO-609-resistant mutants of both CaMKK isoforms, indicating that both CaMKK isoforms are capable of phosphorylating and activating CaMKIV in living cells. Considering these results together, STO-609-resistant CaMKK mutants developed in this study may be useful for distinguishing CaMKK isoform-mediated signaling pathways in combination with the use of an inhibitor compound.

  15. Efficacy of ponatinib against ABL tyrosine kinase inhibitor-resistant leukemia cells

    International Nuclear Information System (INIS)

    Okabe, Seiichi; Tauchi, Tetsuzo; Tanaka, Yuko; Ohyashiki, Kazuma

    2013-01-01

    Highlights: •Efficacy of ponatinib against ABL tyrosine kinase inhibitor-resistant leukemia cells okabe et al. •Imatinib or nilotinib resistance was involved Src family kinase. •The BCR-ABL point mutation (E334V) was highly resistant to imatinib or nilotinib. •Ponatinib was a powerful strategy against imatinib or nilotinib resistant Ph-positive cells. -- Abstract: Because a substantial number of patients with chronic myeloid leukemia acquire resistance to ABL tyrosine kinase inhibitors (TKIs), their management remains a challenge. Ponatinib, also known as AP24534, is an oral multi-targeted TKI. Ponatinib is currently being investigated in a pivotal phase 2 clinical trial. In the present study, we analyzed the molecular and functional consequences of ponatinib against imatinib- or nilotinib-resistant (R) K562 and Ba/F3 cells. The proliferation of imatinib- or nilotinib-resistant K562 cells did not decrease after treatment with imatinib or nilotinib. Src family kinase Lyn was activated. Point mutation Ba/F3 cells (E334 V) were also highly resistant to imatinib and nilotinib. Treatment with ponatinib for 72 h inhibited the growth of imatinib- and nilotinib-resistant cells. The phosphorylation of BCR-ABL, Lyn, and Crk-L was reduced. This study demonstrates that ponatinib has an anti-leukemia effect by reducing ABL and Lyn kinase activity and this information may be of therapeutic relevance

  16. Efficacy of ponatinib against ABL tyrosine kinase inhibitor-resistant leukemia cells

    Energy Technology Data Exchange (ETDEWEB)

    Okabe, Seiichi, E-mail: okabe@tokyo-med.ac.jp; Tauchi, Tetsuzo; Tanaka, Yuko; Ohyashiki, Kazuma

    2013-06-07

    Highlights: •Efficacy of ponatinib against ABL tyrosine kinase inhibitor-resistant leukemia cells okabe et al. •Imatinib or nilotinib resistance was involved Src family kinase. •The BCR-ABL point mutation (E334V) was highly resistant to imatinib or nilotinib. •Ponatinib was a powerful strategy against imatinib or nilotinib resistant Ph-positive cells. -- Abstract: Because a substantial number of patients with chronic myeloid leukemia acquire resistance to ABL tyrosine kinase inhibitors (TKIs), their management remains a challenge. Ponatinib, also known as AP24534, is an oral multi-targeted TKI. Ponatinib is currently being investigated in a pivotal phase 2 clinical trial. In the present study, we analyzed the molecular and functional consequences of ponatinib against imatinib- or nilotinib-resistant (R) K562 and Ba/F3 cells. The proliferation of imatinib- or nilotinib-resistant K562 cells did not decrease after treatment with imatinib or nilotinib. Src family kinase Lyn was activated. Point mutation Ba/F3 cells (E334 V) were also highly resistant to imatinib and nilotinib. Treatment with ponatinib for 72 h inhibited the growth of imatinib- and nilotinib-resistant cells. The phosphorylation of BCR-ABL, Lyn, and Crk-L was reduced. This study demonstrates that ponatinib has an anti-leukemia effect by reducing ABL and Lyn kinase activity and this information may be of therapeutic relevance.

  17. Development and Characterization of Temperature-resistant Polymer Electrolytes

    DEFF Research Database (Denmark)

    Qingfeng, Li; Hjuler, Hans Aage; Bjerrum, Niels

    1999-01-01

    Acid-doped PBI polymer electrolyte membranes have been developed and characterized for fuel cell applications at temperatures up to 200°C. Electric conductivity as high as 0.13 S/cm is obtained at 160°C at high doping levels. The water osmotic drag coefficient of the polymer electrolyte is found...

  18. Cellular response to 5-fluorouracil (5-FU in 5-FU-resistant colon cancer cell lines during treatment and recovery

    Directory of Open Access Journals (Sweden)

    Kravik Katherine L

    2006-05-01

    Full Text Available Abstract Background Treatment of cells with the anti-cancer drug 5-fluorouracil (5-FU causes DNA damage, which in turn affects cell proliferation and survival. Two stable wild-type TP53 5-FU-resistant cell lines, ContinB and ContinD, generated from the HCT116 colon cancer cell line, demonstrate moderate and strong resistance to 5-FU, respectively, markedly-reduced levels of 5-FU-induced apoptosis, and alterations in expression levels of a number of key cell cycle- and apoptosis-regulatory genes as a result of resistance development. The aim of the present study was to determine potential differential responses to 8 and 24-hour 5-FU treatment in these resistant cell lines. We assessed levels of 5-FU uptake into DNA, cell cycle effects and apoptosis induction throughout treatment and recovery periods for each cell line, and alterations in expression levels of DNA damage response-, cell cycle- and apoptosis-regulatory genes in response to short-term drug exposure. Results 5-FU treatment for 24 hours resulted in S phase arrests, p53 accumulation, up-regulation of p53-target genes on DNA damage response (ATF3, GADD34, GADD45A, PCNA, cell cycle-regulatory (CDKN1A, and apoptosis-regulatory pathways (FAS, and apoptosis induction in the parental and resistant cell lines. Levels of 5-FU incorporation into DNA were similar for the cell lines. The pattern of cell cycle progression during recovery demonstrated consistently that the 5-FU-resistant cell lines had the smallest S phase fractions and the largest G2(/M fractions. The strongly 5-FU-resistant ContinD cell line had the smallest S phase arrests, the lowest CDKN1A levels, and the lowest levels of 5-FU-induced apoptosis throughout the treatment and recovery periods, and the fastest recovery of exponential growth (10 days compared to the other two cell lines. The moderately 5-FU-resistant ContinB cell line had comparatively lower apoptotic levels than the parental cells during treatment and recovery

  19. Cytoview: Development of a cell modelling framework

    Indian Academy of Sciences (India)

    2007-07-06

    Jul 6, 2007 ... Home; Journals; Journal of Biosciences; Volume 32; Issue 5. Cytoview: Development of a cell modelling framework ... The framework serves as a first step in integrating different levels of data available for a biological cell and has the potential to lead to development of computational models in our pursuit to ...

  20. Keeping the Rhythm : Cardiac Pacemaker Cell Development

    NARCIS (Netherlands)

    Burkhard, Silja

    2017-01-01

    The heart is the first organ to form and function in the developing vertebrate embryo. Its proper morphogenesis and function is crucial for survival. Here we focus on the development and characterization of a highly specialized subset of cardiac cells, the pacemaker cells. In the mammalian heart,

  1. Colorectal cancer stem cells : regulation of the phenotype and implications for therapy resistance

    OpenAIRE

    Emmink, B.L.

    2014-01-01

    In this thesis different aspects of cancer stem cells in colorectal cancer are discribed. We focus on the therapy resistance of cancer stem cells and the effect that reactive oxygen species and hypoxia have on the cancer stem cell phenotype. For this purpose a novel culture method to propagate cancer stem cells form resected tumor specimens was used.

  2. Effects of an inducible anti-sense c-myc gene transfer in a drug-resistant human small-cell-lung-carcinoma cell line

    NARCIS (Netherlands)

    Van Waardenburg, R C; Meijer, C; Burger, H; Nooter, K; De Vries, E G; Mulder, N H; de Jong, Steven

    1997-01-01

    Small-cell-lung-cancer (SCLC) is characterized by rapid development of resistance to cytotoxic agents, such as cisplatin (cDDP) and anthracyclines. c-myc over-expression is one of the reported genetic alterations in this tumor. Amplification of the c-myc gene in this and other cancers is often

  3. Development and Performance Verification of High Resistance Semiconducting Glaze Insulators

    Science.gov (United States)

    Shinoda, Akihide; Chiyajo, Kiyonobu; Okada, Hideyuki; Suzuki, Yoshihiro; Ito, Susumu; Naito, Katsuhiko

    In case of transmission lines along the sea coast, audible noise due to partial discharges may occur from insulators when contaminated with sea salt and wetted. From the consideration to residents, insulator washing has been performed periodically, but this results in increase in the maintenance cost. As a countermeasure to reduce the audible noise, semiconducting glaze insulator (DC resistance approx. 20MΩ) has been developed and used. However, in case of a very special environment with direct spraying of sea water in seaside districts, there seems to be some risk of thermal runaway because voltage concentration on very small number of insulator units in a string is possible and it may rise the temperature of those units up to the critical point. In this paper, the thermal runaway mechanism is clarified from view point of input and output energy of the semiconducting glaze insulator under contaminated and wetted condition. The surface temperature starting thermal runaway is estimated from various experiments. As a result, the high resistance semiconducting glaze insulator, which has higher thermal runaway withstand capacity and acceptable agreeable audible noise characteristics is developed and subjected to the field evaluation.

  4. Development of resistance type moisture measuring device for grains

    Directory of Open Access Journals (Sweden)

    Sadiq Sius LAWAL

    2017-06-01

    Full Text Available The paper presents a study aimed at developing an indigenous moisture measuring device from locally available materials for grains based on the principle of resistance change of the material with corresponding change in moisture during drying. The developed device has four copper electrode cups positions in which both gauging and dummy copper electrode cups were placed to form Wheatstone bridge circuits of full, half and quarter for four, two and one gauging copper electrode cups respectively, while the remaining positions were used as dummies. These circuits were used to measure the resistances and hence obtaining the moisture content of the grains used. Grains of paddy rice, guinea corn and millet were used to test the device and it was observed that for full bridge circuits of each of the grains, paddy rice have a negative coefficient of correlation of -0.95, -0.99 for guinea corn and -0.99 for millet. The results obtained from predictive empirical equations when compared with the direct oven method, showed that the device can be used to predict or measure moisture content once calibrated.

  5. Development of wear resistant ceramic coatings for diesel engine components

    Energy Technology Data Exchange (ETDEWEB)

    Haselkorn, M.H. (Caterpillar, Inc., Peoria, IL (United States))

    1992-04-01

    Improved fuel economy and a reduction of emissions can be achieved by insulation of the combustion chamber components to reduce heat rejection. However, insulating the combustion chamber components will also increase the operating temperature of the piston ring/cylinder liner interface from approximately 150{degree}C to over 300{degree}C. Existing ring/liner materials can not withstand these higher operating temperatures and for this reason, new materials need to be developed for this critical tribological interface. The overall goal of this program is the development of piston ring/cylinder liner material pairs which would be able to provide the required friction and wear properties at these more severe operating conditions. More specifically, this program first selected, and then evaluated, potential d/wear resistant coatings which could be applied to either piston rings an or cylinder liners and provide, at 350{degree}C under lubricated conditions, coefficients of friction below 0.1 and wear rates of less than 25 {times} lO{sup {minus}6} mm/hour. The processes selected for applying the candidate wear resistant coatings to piston rings and/or cylinder liners were plasma spraying, chemical vapor, physical vapor and low temperature arc vapor deposition techniques as well as enameling techniques.

  6. Generation of a predictive melphalan resistance index by drug screen of B-cell cancer cell lines.

    Directory of Open Access Journals (Sweden)

    Martin Boegsted

    Full Text Available BACKGROUND: Recent reports indicate that in vitro drug screens combined with gene expression profiles (GEP of cancer cell lines may generate informative signatures predicting the clinical outcome of chemotherapy. In multiple myeloma (MM a range of new drugs have been introduced and now challenge conventional therapy including high dose melphalan. Consequently, the generation of predictive signatures for response to melphalan may have a clinical impact. The hypothesis is that melphalan screens and GEPs of B-cell cancer cell lines combined with multivariate statistics may provide predictive clinical information. MATERIALS AND METHODS: Microarray based GEPs and a melphalan growth inhibition screen of 59 cancer cell lines were downloaded from the National Cancer Institute database. Equivalent data were generated for 18 B-cell cancer cell lines. Linear discriminant analyses (LDA, sparse partial least squares (SPLS and pairwise comparisons of cell line data were used to build resistance signatures from both cell line panels. A melphalan resistance index was defined and estimated for each MM patient in a publicly available clinical data set and evaluated retrospectively by Cox proportional hazards and Kaplan-Meier survival analysis. PRINCIPAL FINDINGS: Both cell line panels performed well with respect to internal validation of the SPLS approach but only the B-cell panel was able to predict a significantly higher risk of relapse and death with increasing resistance index in the clinical data sets. The most sensitive and resistant cell lines, MOLP-2 and RPMI-8226 LR5, respectively, had high leverage, which suggests their differentially expressed genes to possess important predictive value. CONCLUSION: The present study presents a melphalan resistance index generated by analysis of a B-cell panel of cancer cell lines. However, the resistance index needs to be functionally validated and correlated to known MM biomarkers in independent data sets in order to

  7. Manipulation of intracellular auxin in a single cell by light with esterase-resistant caged auxins.

    Science.gov (United States)

    Kusaka, Naoyuki; Maisch, Jan; Nick, Peter; Hayashi, Ken-ichiro; Nozaki, Hiroshi

    2009-09-04

    Auxin, a plant hormone, is polar transported from its site of production. This auxin polar transport system establishes an auxin gradient in plant tissue that is necessary for proper plant development. Therefore, the spatial effect of the auxin gradient on plant development is highly important for the understanding of plant auxin responses. Herein we report the design, syntheses and biological properties of esterase-resistant caged auxins. The conventional caging group, 2-nitrobenzyl ester, was found to be enzymatically hydrolyzed in plant cells and released original auxin without photolysis. The esterase-resistant caging group, (2,5-dimethoxyphenyl)(2-nitrobenzyl) ester, (DMPNB) was designed to improve the stability of caged auxins. Three auxins, indole 3-acetic acid, naphthalene 1-acetic acid and 2,4-dichlorophenoxy acetic acid were caged with the DMPNB caging group. DMPNB-caged auxins were inactive within a plant cell until photolysis, but they release auxins with photoirradiation to activate auxin-responsive gene expression. We demonstrated spatial and temporal control of intracellular auxin levels with photoirradiation by using this caged auxin system and were able to photocontrol the physiological auxin response in Arabidopsis plants. Additionally, the photoirradiation of DMPNB-caged auxin within a single cell can manipulate the intracellular auxin level and triggers auxin response.

  8. Acquired temozolomide resistance in human glioblastoma cell line U251 is caused by mismatch repair deficiency and can be overcome by lomustine.

    Science.gov (United States)

    Stritzelberger, J; Distel, L; Buslei, R; Fietkau, R; Putz, F

    2018-04-01

    Glioblastoma multiforme (GBM) is the most common malignant primary brain tumor in adults. While the alkylating agent temozolomide (TMZ) has prolonged overall survival, resistance evolution represents an important clinical problem. Therefore, we studied the effectiveness of radiotherapy and CCNU in an in vitro model of acquired TMZ resistance. We studied the MGMT-methylated GBM cell line U251 and its in vitro derived TMZ-resistant subline, U251/TMZ-R. Cytotoxicity of TMZ, CCNU, and radiation was tested. Both cell lines were analyzed for MGMT promotor status and expression of mismatch repair genes (MMR). The influence of MMR inhibition by cadmium chloride (CdCl 2 ) on the effects of both drugs was evaluated. During the resistance evolution process in vitro, U251/TMZ-R developed MMR deficiency, but MGMT status did not change. U251/TMZ-R cells were more resistant to TMZ than parental U251 cells (cell viability: 92.0% in U251/TMZ-R/69.2% in U251; p = 0.032) yet more sensitive to CCNU (56.4%/80.8%; p = 0.023). The effectiveness of radiotherapy was not reduced in the TMZ-resistant cell line. Combination of CCNU and TMZ showed promising results for both cell lines and overcame resistance. CdCl 2 -induced MMR deficiency increased cytotoxicity of CCNU. Our results confirm MMR deficiency as a crucial process for resistance evolution to TMZ. MMR-deficient TMZ-resistant GBM cells were particularly sensitive to CCNU and to combined CCNU/TMZ. Effectiveness of radiotherapy was preserved in TMZ-resistant cells. Consequently, CCNU might be preferentially considered as a treatment option for recurrent MGMT-methylated GBM and may even be suitable for prevention of resistance evolution in primary treatment.

  9. Circumvention of acquired resistance to doxorubicin in K562 human leukemia cells by oxatomide.

    Science.gov (United States)

    Ishikawa, M; Fujita, R; Furusawa, S; Takayanagi, M; Sasaki, K; Satoh, S

    2001-10-01

    We studied the effect of oxatomide, an antiallergic drug, on the resistance of K562 cells to doxorubicin. Oxatomide synergistically potentiated the cytotoxicity of doxorubicin in doxorubicin-resistant K562 cells (K562/DXR) at a concentration of 1-10 microM, but had hardly any synergistic effect on the parental cell line (K562) at the same concentration. Oxatomide inhibit P-glycoprotein pump-efflux activity and the binding of [3H]-azidopine to the cell-surface protein P-glycoprotein, in a dose-related manner. These results indicate that oxatomide reverses the multidrug-resistance phenotype through direct interaction with P-glycoprotein.

  10. Recent Development in ITO-free Flexible Polymer Solar Cells

    Directory of Open Access Journals (Sweden)

    Shudi Lu

    2017-12-01

    Full Text Available Polymer solar cells have shown good prospect for development due to their advantages of low-cost, light-weight, solution processable fabrication, and mechanical flexibility. Their compatibility with the industrial roll-to-roll manufacturing process makes it superior to other kind of solar cells. Normally, indium tin oxide (ITO is adopted as the transparent electrode in polymer solar cells, which combines good conductivity and transparency. However, some intrinsic weaknesses of ITO restrict its large scale applications in the future, including a high fabrication price using high temperature vacuum deposition method, scarcity of indium, brittleness and scaling up of resistance with the increase of area. Some substitutes to ITO have emerged in recent years, which can be used in flexible polymer solar cells. This article provides the review on recent progress using other transparent electrodes, including carbon nanotubes, graphene, metal nanowires and nanogrids, conductive polymer, and some other electrodes. Device stability is also discussed briefly.

  11. Identification of microRNAs and mRNAs associated with multidrug resistance of human laryngeal cancer Hep-2 cells

    International Nuclear Information System (INIS)

    Yin, Wanzhong; Wang, Ping; Wang, Xin; Song, Wenzhi; Cui, Xiangyan; Yu, Hong; Zhu, Wei

    2013-01-01

    Multidrug resistance (MDR) poses a serious impediment to the success of chemotherapy for laryngeal cancer. To identify microRNAs and mRNAs associated with MDR of human laryngeal cancer Hep-2 cells, we developed a multidrug-resistant human laryngeal cancer subline, designated Hep-2/v, by exposing Hep-2 cells to stepwise increasing concentrations of vincristine (0.02-0.96'µM). Microarray assays were performed to compare the microRNA and mRNA expression profiles of Hep-2 and Hep-2/v cells. Compared to Hep-2 cells, Hep-2/v cells were more resistant to chemotherapy drugs (∼45-fold more resistant to vincristine, 5.1-fold more resistant to cisplatin, and 5.6-fold more resistant to 5-fluorouracil) and had a longer doubling time (42.33±1.76 vs 28.75±1.12'h, P<0.05), higher percentage of cells in G0/G1 phase (80.98±0.52 vs 69.14±0.89, P<0.05), increased efflux of rhodamine 123 (95.97±0.56 vs 12.40±0.44%, P<0.01), and up-regulated MDR1 expression. A total of 7 microRNAs and 605 mRNAs were differentially expressed between the two cell types. Of the differentially expressed mRNAs identified, regulator of G-protein signaling 10, high-temperature requirement protein A1, and nuclear protein 1 were found to be the putative targets of the differentially expressed microRNAs identified. These findings may open a new avenue for clarifying the mechanisms responsible for MDR in laryngeal cancer

  12. Development of a New Manta Robot Considering the Propulsive Resistance

    Directory of Open Access Journals (Sweden)

    Kota Mikuriya

    2017-03-01

    Full Text Available In recent years, biological research of an aquatic lifeis carried out actively. The sea is a dangerous environment forhumans, so that we cannot investigate an aquatic life for a longperiod of time. In addition, conventional underwater robots havea common mechanism for propulsion with screw propellers.Noises generated by screw propellers have a possibility of givinga bad effect on the biological behavior. On the other hand,biomimetic robots can investigate aquatic lives without affectingthem significantly. Our laboratory has developed a Manta robotthat has propulsion mechanisms with pectoral fins, mimickingthe pectoral fin of the manta ray. Conventional Manta robotshave a problem that its swimming speed is insufficient forinvestigating aquatic lives. In this paper, we develop anautonomous Manta robot that is excellent in the propulsionperformance by taking account of propulsion resistance causedby the body shape. Several experiments are conducted to showthe effectiveness of the proposed method, in the point of theswimming speed and propulsive efficiency

  13. 17β-estradiol exerts anticancer effects in anoikis-resistant hepatocellular carcinoma cell lines by targeting IL-6/STAT3 signaling

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seulki, E-mail: sl10f@naver.com [Department of Internal Medicine and Liver Research Institute, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 110-799 (Korea, Republic of); Lee, Minjong, E-mail: minjonglee2@naver.com [Division of Gastroenterology, Department of Internal Medicine, Kangwon National University Hospital, 156 Baengnyeong-ro, Chuncheon-si, Gangwon-do (Korea, Republic of); Kim, Jong Bin, E-mail: kkimjp@hanmail.net [Hormel Institute, University of Minnesota, 801 16th Ave NE, Austin, MN, 55912 (United States); Jo, Ara, E-mail: loveara0315@naver.com [Department of Internal Medicine and Liver Research Institute, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 110-799 (Korea, Republic of); Cho, Eun Ju, E-mail: creatioex@gmail.com [Department of Internal Medicine and Liver Research Institute, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 110-799 (Korea, Republic of); Yu, Su Jong, E-mail: ydoctor2@hanmail.net [Department of Internal Medicine and Liver Research Institute, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 110-799 (Korea, Republic of); Lee, Jeong-Hoon, E-mail: pindra@empal.com [Department of Internal Medicine and Liver Research Institute, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 110-799 (Korea, Republic of); Yoon, Jung-Hwan, E-mail: yoonjh@snu.ac.kr [Department of Internal Medicine and Liver Research Institute, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 110-799 (Korea, Republic of); Kim, Yoon Jun, E-mail: yoonjun@snu.ac.kr [Department of Internal Medicine and Liver Research Institute, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 110-799 (Korea, Republic of)

    2016-05-13

    17β-Estradiol (E2) has been proven to exert protective effects against HCC; however, its mechanism on HCC proliferation and suppression of invasion remains to be further explored. Because HCC up-regulates serum Interleukin-6 (IL-6) levels and Signal Transducer and Activator of Transcription 3 (STAT3), molecular agents that attenuate IL-6/STAT3 signaling can potentially suppress HCC development. In this study, we examined involvement of E2 in anoikis resistance that induces invasion capacities and chemo-resistance. Huh-BAT and HepG2 cells grown under anchorage-independent condition were selected. The anoikis-resistant (AR) cells showed stronger chemo-resistance against sorafenib, doxorubicin, 5-fluorouracil and cisplatin compared to adherent HCC cells. AR HCC cells exhibited decreased expression of E-cadherin and increased expression of the N-cadherin and vimentin compared to adherent HCC cells. We then demonstrated that E2 suppressed cell proliferation in AR HCC cells. IL-6 treatment enhanced invasive characteristics, and E2 reversed it. Regarding mechanism of E2, it decreased in the phosphorylation of STAT3 that overexpressed on AR HCC cells. The inhibitory effect of E2 on cell growth was accompanied with cell cycle arrest at G2/M phase and caspase-3/9/PARP activation through c-Jun N-terminal Kinase (JNK) phosphorylation. Taken together, these findings suggested that E2 inhibited the proliferation of AR HCC cells through down-regulation of IL-6/STAT3 signaling. Thus, E2 can be a potential therapeutic drug for treatment of metastatic or chemo-resistant HCC. -- Highlights: •Anoikis-resistant HCC cells characterized chemo-resistant and metastatic potentials. •17β-Estradiol down-regulated IL-6/STAT3 signaling in anoikis-resistant HCC cells. •17β-Estradiol suppressed cell proliferation by inducing G2/M phase arrest and apoptosis though JNK phosphorylation.

  14. Stanniocalcin 2 promotes cell proliferation and cisplatin resistance in cervical cancer

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yuxia; Gao, Ying; Cheng, Hairong; Yang, Guichun [Department of Gynecology, Harbin Medical University Cancer Hospital, Harbin, Heilongjiang, 150081 (China); Tan, Wenhua, E-mail: tanwenhua1962@163.com [Department of Gynecology, The Second Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang, 150086 (China)

    2015-10-23

    Cervical cancer is one of the most common carcinomas in the female reproductive system. Treatment of cervical cancer involves surgical removal and chemotherapy. Resistance to platinum-based chemotherapy drugs including cisplatin has increasingly become an important problem in the treatment of cervical cancer patients. We found in this study that stanniocalcin 2 (STC2) expression was upregulated in both cervical cancer tissues and cell lines. The levels of STC2 expression in cervical cancer cell lines were positively correlated with the rate of cell proliferation. Furthermore, in cisplatin resistant cervical cancer cells, the levels of STC2 expression were significantly elevated. Modulation of STC2 expression by siRNA or overexpression in cisplatin resistant cells resulted in altered cell survival, apoptosis, and cisplatin resistance. Finally, we found that there was significant difference in the activity of the MAPK signaling pathway between cisplatin sensitive and resistant cervical cancer cells, and that STC2 could regulate the activity of the MAPK signaling pathway. - Highlights: • STC2 was upregulated in cervical cancer and promoted cervical cancer cell proliferation. • Cisplatin resistant cells had elevated STC2 levels and enhanced proliferation. • STC2 regulated cisplatin chemosensitivity in cervical cancer cells. • STC2 regulated the activity of the MAPK signaling pathway.

  15. Stanniocalcin 2 promotes cell proliferation and cisplatin resistance in cervical cancer

    International Nuclear Information System (INIS)

    Wang, Yuxia; Gao, Ying; Cheng, Hairong; Yang, Guichun; Tan, Wenhua

    2015-01-01

    Cervical cancer is one of the most common carcinomas in the female reproductive system. Treatment of cervical cancer involves surgical removal and chemotherapy. Resistance to platinum-based chemotherapy drugs including cisplatin has increasingly become an important problem in the treatment of cervical cancer patients. We found in this study that stanniocalcin 2 (STC2) expression was upregulated in both cervical cancer tissues and cell lines. The levels of STC2 expression in cervical cancer cell lines were positively correlated with the rate of cell proliferation. Furthermore, in cisplatin resistant cervical cancer cells, the levels of STC2 expression were significantly elevated. Modulation of STC2 expression by siRNA or overexpression in cisplatin resistant cells resulted in altered cell survival, apoptosis, and cisplatin resistance. Finally, we found that there was significant difference in the activity of the MAPK signaling pathway between cisplatin sensitive and resistant cervical cancer cells, and that STC2 could regulate the activity of the MAPK signaling pathway. - Highlights: • STC2 was upregulated in cervical cancer and promoted cervical cancer cell proliferation. • Cisplatin resistant cells had elevated STC2 levels and enhanced proliferation. • STC2 regulated cisplatin chemosensitivity in cervical cancer cells. • STC2 regulated the activity of the MAPK signaling pathway.

  16. Photodynamic action of LED-activated pyropheophorbide-α methyl ester in cisplatin-resistant human ovarian carcinoma cells

    Science.gov (United States)

    Tan, Y.; Xu, C. S.; Xia, X. S.; Yu, H. P.; Bai, D. Q.; He, Y.; Leung, A. W. N.

    2009-04-01

    Cisplatin-resistance is a major obstacle for the successful therapy to ovarian cancer, and exploring novel approach to deactivate cisplatin-resistant ovarian cells will improve the clinical outcomes. Our present study showed that there was no dark cytotoxicity of MPPa in the COC1/DDP cells at the dose of 0.25 - 4 μM, and LED-activated MPPa resulted in drug dose- and light-dependent cytotoxicity. Apoptotic rate 6 h after LED-activated MPPa (2 μM) increased to 16.71% under the light energy of 1 J/cm2. Confocal laser scanning microscopy showed that MPPa mainly localized in the intracellular membrane system, namely the endoplasmic reticulum, Golgi apparatus, lysosomes and mitochondria in the COC1/DDP cells. Mitochondrial membrane potential (ΔΨm) was collapsed when COC1/DDP cells were exposed to 2 μM MPPa for 20 h and then 1 J/cm2 irradiation of LED source. These data demonstrated that LED-activated MPPa significantly deactivated cisplatin-resistant ovarian cell line COC1/DDP cells and enhanced apoptosis and decreased ΔΨm, which suggests LED is an efficient light source for PDT and LED-activated MPPa can be developed as new modality for treating cisplatin-resistant ovarian.

  17. Vorinostat, a histone deacetylase (HDAC) inhibitor, promotes cell cycle arrest and re-sensitizes rituximab- and chemo-resistant lymphoma cells to chemotherapy agents.

    Science.gov (United States)

    Xue, Kai; Gu, Juan J; Zhang, Qunling; Mavis, Cory; Hernandez-Ilizaliturri, Francisco J; Czuczman, Myron S; Guo, Ye

    2016-02-01

    Preclinical models of chemotherapy resistance and clinical observations derived from the prospective multicenter phase III collaborative trial in relapsed aggressive lymphoma (CORAL) study demonstrated that primary refractory/relapsed B cell diffuse large B cell lymphoma has a poor clinical outcome with current available second-line treatments. Preclinically, we found that rituximab resistance is associated with a deregulation on the mitochondrial potential rendering lymphoma cells resistant to chemotherapy-induced apoptotic stimuli. There is a dire need to develop agents capable to execute alternative pathways of cell death in an attempt to overcome chemotherapy resistance. Posttranscriptional histone modification plays an important role in regulating gene transcription and is altered by histone acetyltransferases (HATs) and histone deacetylases (HDACs). HDACs regulate several key cellular functions, including cell proliferation, cell cycle, apoptosis, angiogenesis, migration, antigen presentation, and/or immune regulation. Given their influence in multiple regulatory pathways, HDAC inhibition is an attractive strategy to evaluate its anti-proliferation activity in cancer cells. To this end, we studied the anti-proliferation activity and mechanisms of action of suberoylanilide hydroxamic acid (SAHA, vorinostat) in rituximab-chemotherapy-resistant preclinical models. A panel of rituximab-chemotherapy-sensitive (RSCL) and rituximab-chemotherapy-resistant cell lines (RRCL) and primary tumor cells isolated from relapsed/refractory B cell lymphoma patients were exposed to escalating doses of vorinostat. Changes in mitochondrial potential, ATP synthesis, and cell cycle distribution were determined by Alamar blue reduction, Titer-Glo luminescent assays, and flow cytometric, respectively. Protein lysates were isolated from vorinostat-exposed cells, and changes in members of Bcl-2 family, cell cycle regulatory proteins, and the acetylation status of histone H3 were

  18. Overcoming cisplatin resistance of ovarian cancer cells by targeting HIF-1-regulated cancer metabolism.

    Science.gov (United States)

    Ai, Zhihong; Lu, Yang; Qiu, Songbo; Fan, Zhen

    2016-04-01

    Cisplatin is currently one of the most effective chemotherapeutic drugs used for treating ovarian cancer; however, resistance to cisplatin is common. In this study, we explored an experimental strategy for overcoming cisplatin resistance of human ovarian cancer from the new perspective of cancer cell metabolism. By using two pairs of genetically matched cisplatin-sensitive and cisplatin-resistant ovarian cancer cell lines, we tested the hypothesis that downregulating hypoxia-inducible factor-1 (HIF-1), which regulates metabolic enzymes involved in glycolysis, is a promising strategy for overcoming cisplatin resistance of human ovarian cancer cells. We found that cisplatin downregulated the level of the regulatable α subunit of HIF-1, HIF-1α, in cisplatin-sensitive ovarian cancer cells through enhancing HIF-1α degradation but did not downregulate HIF-1α in their cisplatin-resistant counterparts. Overexpression of a degradation-resistant HIF-1α (HIF-1α ΔODD) reduced cisplatin-induced apoptosis in cisplatin-sensitive cells, whereas genetic knockdown of HIF-1α or pharmacological promotion of HIF-1α degradation enhanced response to cisplatin in both cisplatin-sensitive and cisplatin-resistant ovarian cancer cells. We further demonstrated that knockdown of HIF-1α improved the response of cisplatin-resistant ovarian cancer cells to cisplatin by redirecting the aerobic glycolysis in the resistant cancer cells toward mitochondrial oxidative phosphorylation, leading to cell death through overproduction of reactive oxygen species. Our findings suggest that the HIF-1α-regulated cancer metabolism pathway could be a novel target for overcoming cisplatin resistance in ovarian cancer. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  19. American fuel cell market development

    Science.gov (United States)

    Gillis, E. A.

    1992-01-01

    Over the past three decades several attempts have been made to introduce fuel cells into commercial markets. The prospective users recognized the attractive features of fuel cells, however they were unwilling to pay a premium for the features other than the easily-calculated fuel cost savings. There was no accepted method for a user to calculate and the accrue the economic value of the other features. The situation is changing. The Clean Air Act signed into law by President Bush on November 15, 1990, mandates a nation wide reduction in SO 2, NO x and ozone emissions. This law affects specific utilities for SO 2 reduction, and specific regions of the country for NO x and ozone reductions — the latter affecting the utility-, industrial- and transportation-sectors in these regions. The Act does not direct how the reductions are to be achieved; but it specifically establishes a trading market for emission allowances whereby an organization that reduces emissions below its target can sell its unused allowance to another organization. In addition to the Clean Air Act, there are other environmental issues emerging such as controls on CO 2 emissions, possible expansion of the list of controlled emissions, mandated use of alternative fuels in specific transportation districts and restrictions on electrical transmission systems. All of these so-called 'environmental externalities' are now recognized as having a real cost that can be quantified, and factored in to calculations to determine the relative economic standing of various technologies. This in turn justifies a premium price for fuel cells hence the renewed interest in the technology by the utility and transportation market segments.

  20. Relevance of copper transporter 1 and organic cation transporters 1-3 for oxaliplatin uptake and drug resistance in colorectal cancer cells.

    Science.gov (United States)

    Buß, I; Hamacher, A; Sarin, N; Kassack, M U; Kalayda, G V

    2018-03-01

    Oxaliplatin is a routinely used drug in the treatment of colorectal cancer. However, development of resistance is a major hurdle of the chemotherapy success. Defects in cellular accumulation represent a frequently reported feature of cells with acquired resistance to platinum drugs. Nevertheless, the mechanisms of oxaliplatin uptake and their role in oxaliplatin resistance remain poorly elucidated. The aim of this study was to investigate the relevance of copper transporter 1 (CTR1) and organic cation transporters 1-3 (OCT1-3) for oxaliplatin uptake and resistance to the drug in sensitive and oxaliplatin-resistant ileocecal colorectal adenocarcinoma cells. Co-incubation with copper(ii) sulfate, a CTR1 substrate, significantly decreased oxaliplatin accumulation but not cytotoxicity in both cell lines. Pre- as well as co-incubation with the OCT1 inhibitor atropine led to a significant reduction in oxaliplatin accumulation in sensitive but not in resistant cells. However, oxaliplatin cytotoxicity was also decreased in the presence of atropine in both cell lines. Cimetidine, an inhibitor of OCT2, induced a significant reduction in the cellular accumulation and potency of oxaliplatin in sensitive and resistant cells. An inhibitor of OCT3, decynium-22, had no influence on oxaliplatin accumulation and cytotoxicity in either cell line. No differences in the transporter expressions were observed between the cell lines, drug-treated or not, either at the mRNA or protein levels. A fluorescent oxaliplatin derivative CFDA-oxPt co-localized with CTR1, OCT1 and OCT2 in sensitive cells, but only with CTR1 and OCT2 in the resistant cell line. Our results suggest that oxaliplatin is transported into the cell by CTR1 in both cell lines. However, contribution of CTR1-mediated uptake to resistance seems unlikely. Uptake of oxaliplatin via OCT1 appears to take place in the sensitive but not in the resistant cell line underscoring the transporter relevance for oxaliplatin resistance. OCT

  1. Endoderm Generates Endothelial Cells during Liver Development

    Directory of Open Access Journals (Sweden)

    Orit Goldman

    2014-10-01

    Full Text Available Organogenesis requires expansion of the embryonic vascular plexus that migrates into developing organs through a process called angiogenesis. Mesodermal progenitors are thought to derive endothelial cells (ECs that contribute to both embryonic vasculogenesis and the subsequent organ angiogenesis. Here, we demonstrate that during development of the liver, which is an endoderm derivative, a subset of ECs is generated from FOXA2+ endoderm-derived fetal hepatoblast progenitor cells expressing KDR (VEGFR2/FLK-1. Using human and mouse embryonic stem cell models, we demonstrate that KDR+FOXA2+ endoderm cells developing in hepatic differentiation cultures generate functional ECs. This introduces the concept that ECs originate not exclusively from mesoderm but also from endoderm, supported in Foxa2 lineage-tracing mouse embryos by the identification of FOXA2+ cell-derived CD31+ ECs that integrate the vascular network of developing fetal livers.

  2. TLR4 and NFκB signaling is critical for taxol resistance in ovarian carcinoma cells.

    Science.gov (United States)

    Sun, Nian-Kang; Huang, Shang-Lang; Chang, Ting-Chang; Chao, Chuck C-K

    2018-03-01

    We report here that toll-like receptor 4 (TLR4) and ABCB1 are upregulated in SKOV3 ovarian carcinoma cells that acquired resistance to the anticancer drug taxol. Silencing of TLR4 using short-hairpin RNA sensitized taxol-resistant SKOV3 cells to taxol (4.6 fold), whereas ectopic expression of TLR4 in parental, taxol-sensitive SKOV3 cells or TLR4-null HEK293 cells induced taxol resistance (∼2 fold). A sub-lethal dose of taxol induced ABCB1 protein expression in taxol-resistant SKOV3 cells. Inactivation of TLR4 using chemical inhibitors (CLI-095 and AO-I) downregulated ABCB1 protein expression and enhanced the cytotoxic activity of taxol in taxol-resistant SKOV3 cells. While the sensitization effect of TLR4 inactivation was also detected in TOV21G ovarian cancer cells, which express moderate level of TLR4, ectopic expression of ABCB1 prevented the sensitization effect in these cells. Notably, the NFκB pathway was significantly activated by taxol, and inhibition of this pathway suppressed TLR4-regulated ABCB1 expression. Furthermore, taxol-induced NFκB signaling was reduced following TLR4 silencing in taxol-resistant SKOV3 cells. Consistent with these results, ectopic expression of TLR4 in taxol-sensitive SKOV3 cells enhanced ABCB1 expression and conferred resistance to taxol. The protective effect of exogenous TLR4 expression against taxol was reduced by treatment with NFκB inhibitor in these cells. These results demonstrate that taxol activates the TLR4-NFκB pathway which in turn induces ABCB1 gene expression. This cellular pathway thus represents a novel target to limit resistance to taxol in ovarian cancer cells. © 2017 Wiley Periodicals, Inc.

  3. CD1d-restricted NKT cell function prevents insulin resistance in lean mice, and is regulated by adipocytes and is regulated by adipocytes

    NARCIS (Netherlands)

    Schipper, Henk S.; Rakhshandehroo, Maryam; Graaf, van de Stan F.; Venken, Koen; Koppen, Arjen; Stienstra, Rinke; Prop, Serge; Meerding, Jenny; Hamers, Nicole; Besra, Gurdyal; Boon, Louis; Nieuwenhuis, Edward E.; Elewaut, Dirk; Prakken, Berent; Kersten, Sander; Boes, Marianne; Kalkhoven, Eric

    2012-01-01

    Lipid overload and adipocyte dysfunction are key to the development of insulin resistance and can be induced by a high-fat diet. CD1d-restricted invariant natural killer T (iNKT) cells have been proposed as mediators between lipid overload and insulin resistance, but recent studies found decreased

  4. Cell wall alterations in the leaves of fusariosis-resistant and susceptible pineapple cultivars.

    Science.gov (United States)

    de Farias Viégas Aquije, Glória Maria; Zorzal, Poliana Belisário; Buss, David Shaun; Ventura, José Aires; Fernandes, Patricia Machado Bueno; Fernandes, Antonio Alberto Ribeiro

    2010-10-01

    Fusariosis, caused by the fungus Fusarium subglutinans f. sp. ananas (Syn. F. guttiforme), is one of the main phytosanitary threats to pineapple (Ananas comosus var. comosus). Identification of plant cell responses to pathogens is important in understanding the plant-pathogen relationship and establishing strategies to improve and select resistant cultivars. Studies of the structural properties and phenolic content of cell walls in resistant (Vitoria) and susceptible (Perola) pineapple cultivars, related to resistance to the fungus, were performed. The non-chlorophyll base of physiologically mature leaves was inoculated with a conidia suspension. Analyses were performed post-inoculation by light, atomic force, scanning and transmission electron microscopy, and measurement of cell wall-bound phenolic compounds. Non-inoculated leaves were used as controls to define the constitutive tissue characteristics. Analyses indicated that morphological differences, such as cell wall thickness, cicatrization process and lignification, were related to resistance to the pathogen. Atomic force microscopy indicated a considerable difference in the mechanical properties of the resistant and susceptible cultivars, with more structural integrity, associated with higher levels of cell wall-bound phenolics, found in the resistant cultivar. p-Coumaric and ferulic acids were shown to be the major phenolics bound to the cell walls and were found in higher amounts in the resistant cultivar. Leaves of the resistant cultivar had reduced fungal penetration and a faster and more effective cicatrization response compared to the susceptible cultivar.

  5. Internal resistance of rear totally diffused solar cells with line shaped contacts

    Science.gov (United States)

    Meier, Sebastian; Saint-Cast, Pierre; Wöhrle, Nico; Fell, Andreas; Greulich, Johannes; Wolf, Andreas; Glunz, Stefan W.

    2017-11-01

    We present an analytical model for the internal resistance of passivated emitter and rear totally diffused (PERT) solar cells. First, we apply the model of Saint-Cast for the spreading resistance of a passivated emitter and rear cell (PERC) structure with line-shaped contacts. To account for the additional vertical current flow through the silicon wafer and the lateral current flow through the back surface field of a PERT structure, we add a parallel current path using common analytical expressions. We compare the analytical models with two-dimensional numerical simulations based on Quokka 3 and find deviations of less than 6% for the internal resistance. In addition, we compare the analytical model of the internal resistance of PERC and PERT solar cells with experimental data of the series resistance of PERC and PERT solar cells.

  6. Size-based cell sorting with a resistive pulse sensor and an electromagnetic pump in a microfluidic chip.

    Science.gov (United States)

    Song, Yongxin; Li, Mengqi; Pan, Xinxiang; Wang, Qi; Li, Dongqing

    2015-02-01

    An electrokinetic microfluidic chip is developed to detect and sort target cells by size from human blood samples. Target-cell detection is achieved by a differential resistive pulse sensor (RPS) based on the size difference between the target cell and other cells. Once a target cell is detected, the detected RPS signal will automatically actuate an electromagnetic pump built in a microchannel to push the target cell into a collecting channel. This method was applied to automatically detect and sort A549 cells and T-lymphocytes from a peripheral fingertip blood sample. The viability of A549 cells sorted in the collecting well was verified by Hoechst33342 and propidium iodide staining. The results show that as many as 100 target cells per minute can be sorted out from the sample solution and thus is particularly suitable for sorting very rare target cells, such as circulating tumor cells. The actuation of the electromagnetic valve has no influence on RPS cell detection and the consequent cell-sorting process. The viability of the collected A549 cell is not impacted by the applied electric field when the cell passes the RPS detection area. The device described in this article is simple, automatic, and label-free and has wide applications in size-based rare target cell sorting for medical diagnostics. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Estimation of interface resistivity in bonded Si for the development of high performance radiation detectors

    International Nuclear Information System (INIS)

    Kanno, Ikuo; Yamashita, Makoto; Nomiya, Seiichiro; Onabe, Hideaki

    2007-01-01

    For the development of high performance radiation detectors, direct bonding of Si wafers would be an useful method. Previously, p-n bonded Si were fabricated and they showed diode characteristics. The interface resistivity was, however, not investigated in detail. For the study of interface resistivity, n-type Si wafers with different resistivities were bonded. The resistivity of bonded Si wafers were measured and the interface resistivity was estimated by comparing with the results of model calculations. (author)

  8. Programmed Cell Death During Caenorhabditis elegans Development.

    Science.gov (United States)

    Conradt, Barbara; Wu, Yi-Chun; Xue, Ding

    2016-08-01

    Programmed cell death is an integral component of Caenorhabditis elegans development. Genetic and reverse genetic studies in C. elegans have led to the identification of many genes and conserved cell death pathways that are important for the specification of which cells should live or die, the activation of the suicide program, and the dismantling and removal of dying cells. Molecular, cell biological, and biochemical studies have revealed the underlying mechanisms that control these three phases of programmed cell death. In particular, the interplay of transcriptional regulatory cascades and networks involving multiple transcriptional regulators is crucial in activating the expression of the key death-inducing gene egl-1 and, in some cases, the ced-3 gene in cells destined to die. A protein interaction cascade involving EGL-1, CED-9, CED-4, and CED-3 results in the activation of the key cell death protease CED-3, which is tightly controlled by multiple positive and negative regulators. The activation of the CED-3 caspase then initiates the cell disassembly process by cleaving and activating or inactivating crucial CED-3 substrates; leading to activation of multiple cell death execution events, including nuclear DNA fragmentation, mitochondrial elimination, phosphatidylserine externalization, inactivation of survival signals, and clearance of apoptotic cells. Further studies of programmed cell death in C. elegans will continue to advance our understanding of how programmed cell death is regulated, activated, and executed in general. Copyright © 2016 by the Genetics Society of America.

  9. Multiple mechanisms underlying acquired resistance to taxanes in selected docetaxel-resistant MCF-7 breast cancer cells

    OpenAIRE

    Wang, Harris; Vo, The; Hajar, Ali; Li, Sarah; Chen, Xinmei; Parissenti, Amadeo M; Brindley, David N; Wang, Zhixiang

    2014-01-01

    Background 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. Methods 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 und...

  10. Development of Ultra Low Temperature, Impact Resistant Lithium Battery for the Mars Microprobe

    Science.gov (United States)

    Frank, H.; Deligiannis, F.; Davies, E.; Ratnakumar, Bugga V.; Surampudi, S.; Russel, P. G.; Reddy, T. B.

    1998-01-01

    The requirements of the power source for the Mars Microprobe, to be backpacked on the Mars 98 Spacecraft, are fairly demanding, with survivability to a shock of the order of 80,000 g combined with an operational requirement at -80 C. Development of a suitable power system, based on primary lithium-thionyl chloride is underway for the last eighteen months, together with Yardney Technical Products Inc., Pawcatuck, CT. The battery consists of 4 cells of 2 Ah capacity at 25 C, of which at least 25 % would be available at -80 C, at a moderate rate of C/20. Each probe contains two batteries and two such probes will be deployed. The selected cell is designed around an approximate 1/2 "D" cells, with flat plate electrodes. Significant improvements to the conventional Li-SOCl2 cell include: (a) use of tetrachlorogallate salt instead of aluminate for improved low temperature performance and reduced voltage delay, (b) optimization of the salt concentration, and (c) modification of the cell design to develop shock resistance to 80,000 g. We report here results from our several electrical performance tests, mission simulation tests, microcalorimetry and AC impedance studies, and Air gun tests. The cells have successfully gone through mission-enabling survivability and performance tests for the Mars Microprobe penetrator.

  11. Mouse Rad9b is essential for embryonic development and promotes resistance to DNA damage

    Science.gov (United States)

    Leloup, Corinne; Hopkins, Kevin M.; Wang, Xiangyuan; Zhu, Aiping; Wolgemuth, Debra J.; Lieberman, Howard B.

    2010-01-01

    RAD9 participates in promoting resistance to DNA damage, cell cycle checkpoint control, DNA repair, apoptosis, embryogenesis, and regulation of transcription. A paralogue of RAD9 (named RAD9B) has been identified. To define the function of mouse Rad9b (Mrad9b), embryonic stem (ES) cells with a targeted gene deletion were constructed and used to generate Mrad9b mutant mice. Mrad9b−/− embryos are resorbed after E7.5 while some of the heterozygotes die between E12.5 and a few days after birth. Mrad9b is expressed in embryonic brain and Mrad9b+/− embryos exhibit abnormal neural tube closure. Mrad9b−/− mouse embryonic fibroblasts are not viable. Mrad9b−/− ES cells are more sensitive to gamma rays and mitomycin C than Mrad9b+/+ controls, but show normal gamma-ray-induced G2/M checkpoint control. There is no evidence of spontaneous genomic instability in Mrad9b−/− cells. Our findings thus indicate that Mrad9b is essential for embryonic development and mediates resistance to certain DNA damaging agents. PMID:20842695

  12. Comparative Genome Analysis of Ciprofloxacin-Resistant Pseudomonas aeruginosa Reveals Genes Within Newly Identified High Variability Regions Associated With Drug Resistance Development

    OpenAIRE

    Su, Hsun-Cheng; Khatun, Jainab; Kanavy, Dona M.; Giddings, Morgan C.

    2013-01-01

    The alarming rise of ciprofloxacin-resistant Pseudomonas aeruginosa has been reported in several clinical studies. Though the mutation of resistance genes and their role in drug resistance has been researched, the process by which the bacterium acquires high-level resistance is still not well understood. How does the genomic evolution of P. aeruginosa affect resistance development? Could the exposure of antibiotics to the bacteria enrich genomic variants that lead to the development of resist...

  13. Alternating current electrical stimulation enhanced chemotherapy: a novel strategy to bypass multidrug resistance in tumor cells

    International Nuclear Information System (INIS)

    Janigro, Damir; Perju, Catalin; Fazio, Vincent; Hallene, Kerri; Dini, Gabriele; Agarwal, Mukesh K; Cucullo, Luca

    2006-01-01

    Tumor burden can be pharmacologically controlled by inhibiting cell division and by direct, specific toxicity to the cancerous tissue. Unfortunately, tumors often develop intrinsic pharmacoresistance mediated by specialized drug extrusion mechanisms such as P-glycoprotein. As a consequence, malignant cells may become insensitive to various anti-cancer drugs. Recent studies have shown that low intensity very low frequency electrical stimulation by alternating current (AC) reduces the proliferation of different tumor cell lines by a mechanism affecting potassium channels while at intermediate frequencies interfere with cytoskeletal mechanisms of cell division. The aim of the present study is to test the hypothesis that permeability of several MDR1 over-expressing tumor cell lines to the chemotherapic agent doxorubicin is enhanced by low frequency, low intensity AC stimulation. We grew human and rodent cells (C6, HT-1080, H-1299, SKOV-3 and PC-3) which over-expressed MDR1 in 24-well Petri dishes equipped with an array of stainless steel electrodes connected to a computer via a programmable I/O board. We used a dedicated program to generate and monitor the electrical stimulation protocol. Parallel cultures were exposed for 3 hours to increasing concentrations (1, 2, 4, and 8 μM) of doxorubicin following stimulation to 50 Hz AC (7.5 μA) or MDR1 inhibitor XR9576. Cell viability was assessed by determination of adenylate kinase (AK) release. The relationship between MDR1 expression and the intracellular accumulation of doxorubicin as well as the cellular distribution of MDR1 was investigated by computerized image analysis immunohistochemistry and Western blot techniques. By the use of a variety of tumor cell lines, we show that low frequency, low intensity AC stimulation enhances chemotherapeutic efficacy. This effect was due to an altered expression of intrinsic cellular drug resistance mechanisms. Immunohistochemical, Western blot and fluorescence analysis revealed

  14. The relationship between p38MAPK and apoptosis during paclitaxel resistance of ovarian cancer cells.

    Science.gov (United States)

    Lu, Meisong; Xiao, Lan; Li, Zhimin

    2007-12-01

    To investigate the relationship between p38 mitogen-activated protein kinase (p38MAPK) and cell apoptosis during the paclitaxel resistance of ovarian carcinoma cell lines, flow cytometry (FCM) and PI staining were employed to determine the effect of p38MAPK inhibitor SB203580 on the apoptosis of A2780/Taxol cells, a drug-resistant human ovarian carcinoma cell line. p38MAPK protein expression in SB203580-treated cells was immunochemically measured. The 50% inhibition concentration (IC(50)) of paclitaxel on A2780/Taxol cells was determined by MTT assay. MDR-1 mRNA, and expression of p38MAPK and phospho-p53 protein were detected by RT-PCR and Western blotting, respectively. The apoptosis rate of A2780/Taxol cells was (19.7+/-1.04)% 24 h after SB203580 treatment. A significant difference in apoptosis rate was found among experiment group, control group and untreated group (Pp53 protein was significantly increased. It is concluded that p38MAPK pathway is related to paclitaxel resistance of ovarian carcinoma, and blockade of this pathway can promote the apoptosis of the drug-resistant cells and reverse the drug-resistance. Moreover, p38MAPK-mediated apoptosis in paclitaxel-resistant ovarian carcinoma cells depends on the activation of p53.

  15. Sequential Salinomycin Treatment Results in Resistance Formation through Clonal Selection of Epithelial-Like Tumor Cells

    Directory of Open Access Journals (Sweden)

    Florian Kopp

    2014-12-01

    Full Text Available Acquiring therapy resistance is one of the major obstacles in the treatment of patients with cancer. The discovery of the cancer stem cell (CSC–specific drug salinomycin raised hope for improved treatment options by targeting therapy-refractory CSCs and mesenchymal cancer cells. However, the occurrence of an acquired salinomycin resistance in tumor cells remains elusive. To study the formation of salinomycin resistance, mesenchymal breast cancer cells were sequentially treated with salinomycin in an in vitro cell culture assay, and the resulting differences in gene expression and salinomycin susceptibility were analyzed. We demonstrated that long-term salinomycin treatment of mesenchymal cancer cells resulted in salinomycin-resistant cells with elevated levels of epithelial markers, such as E-cadherin and miR-200c, a decreased migratory capability, and a higher susceptibility to the classic chemotherapeutic drug doxorubicin. The formation of salinomycin resistance through the acquisition of epithelial traits was further validated by inducing mesenchymal-epithelial transition through an overexpression of miR-200c. The transition from a mesenchymal to a more epithelial-like phenotype of salinomycin-treated tumor cells was moreover confirmed in vivo, using syngeneic and, for the first time, transgenic mouse tumor models. These results suggest that the acquisition of salinomycin resistance through the clonal selection of epithelial-like cancer cells could become exploited for improved cancer therapies by antagonizing the tumor-progressive effects of epithelial-mesenchymal transition.

  16. Ferulic acid reverses ABCB1-mediated paclitaxel resistance in MDR cell lines.

    Science.gov (United States)

    Muthusamy, Ganesan; Balupillai, Agilan; Ramasamy, Karthikeyan; Shanmugam, Mohana; Gunaseelan, Srithar; Mary, Beaulah; Prasad, N Rajendra

    2016-09-05

    Multidrug resistance (MDR) remains a major obstacle in cancer chemotherapy. The use of the dietary phytochemicals as chemosensitizing agents to enhance the efficacy of conventional cytostatic drugs has recently gained the attention as a plausible approach for overcoming the drug resistance. The aim of this study was to investigate whether a naturally occurring diet-based phenolic acid, ferulic acid, could sensitize paclitaxel efficacy in ABCB1 overexpressing (P-glycoprotein) colchicine selected KB Ch(R)8-5 cell line. In vitro drug efflux assays demonstrated that ferulic acid inhibits P-glycoprotein transport function in drug resistant KB Ch(R)8-5 cell lines. However, ferulic acid significantly downregulates ABCB1 expression in a concentration dependent manner. Cytotoxicity assay reveals that ferulic acid decreased paclitaxel resistance in KBCh(R)8-5 and HEK293/ABCB1 cells, which indicates its chemosensitizing potential. Clonogenic cell survival assay and apoptotic morphological staining further confirm the chemosensitizing potential of ferulic acid in drug resistant KB Ch(R)8-5 cell lines. Ferulic acid treatment enhances paclitaxel mediated cell cycle arrest and upregulates paclitaxel-induced apoptotic signaling in KB resistant cells. Hence, it has been concluded that downregulation of ABCB1 and subsequent induction of paclitaxel-mediated cell cycle arrest and apoptotic signaling may be the cause for the chemosensitizing potential of ferulic acid in P-gp overexpressing cell lines. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Isolation and characterization of mink lung epithelial cell mutants resistant to transforming growth factor β

    International Nuclear Information System (INIS)

    Chinkers, M.

    1987-01-01

    Mink lung epithelial cells resistant to growth inhibition by transforming growth factor β (TGF-β) have been isolated by chemical mutagenesis and growth in the presence of platelet extracts enriched in TGF-β. Several resistant clones were isolated, at least one of which stably retained its resistance to TGF-β when grown in the absence of the factor. The cells of this clone were similar to the parent cells in morphology and growth properties. However, unlike the parent cells, the resistant cells did not show any of the following responses to 125 I TGF-β: (1) inhibition of DNA synthesis and proliferation; (2) morphological changes involving increased cell spreading; or (3) stimulation of synthesis of a 48-kilodalton secreted 35 S-protein. The resistant cells do, however, retain a functional TGF-β receptor. The TGF-β resistant cell lines may be useful in genetic studies designed to identify the biochemical events required for inhibition of epithelial cell growth by this factor

  18. Cell potentials, cell resistance, and proton fluxes in corn root tissue. Effects of dithioerythritol

    Energy Technology Data Exchange (ETDEWEB)

    Lin, W.; Hanson, J.B.

    1976-09-01

    Studies were made of the effect of dithioerythritol on net proton flux, potassium influx and efflux, cell potential, and cell resistance in fresh and washed corn (Zea mays L. WF9XM14) root tissue. Dithioerythritol induces equal proton influx and potassium efflux rates, decreases membrane resistance, and hyperpolarizes the cell potential. Greater effects on H/sup +/ and K/sup +/ fluxes are secured at pH 7 than at pH 5. Other sulfhydryl-protecting reagents produced the same responses. No evidence could be found that dithioerythritol affected energy metabolism or membrane ATPase, and proton influx was induced in the presence of uncoupling agents. We deduce that dithioerythritol activates a passive H/sup +//K/sup +/ antiport, driven in these experiments by the outwardly directed electrochemical gradient of K/sup +/. The net effect on H/sup +/ and K/sup +/ fluxes is believed to reside with the combined activity of a polarized H/sup +//K/sup +/ exchanging ATPase and the passive H/sup +//K/sup +/ antiport. A model is presented to show how the combined system might produce stable potential differences and K/sup +/ content.

  19. [Peptide inhibitors of myosin light chain kinase. Development of peptidase resistant analogues].

    Science.gov (United States)

    Sekridova, A V; Sidorova, M V; Az'muko, A A; Molokoedov, A S; Bushuev, V N; Marchenko, A V; Shcherbakova, O V; Shirinskiĭ, V P; Bespalova, Zh D

    2010-01-01

    Myosin light chain kinase (MLCK) is the key regulator of various forms of cell motility including endothelial and epithelial permeability in particular. One of the potential MLCK inhibitors to be used in humans is a membrane permeable peptide H-RKKYKYRRK-NH2 (L-PIK). In present work we used solid phase peptide synthesis and Fmoc-technology to produce five modifications of L-PIK. Based on (1)H NMR analysis revealed that these peptides demonstrated improved resistance to degradation in blood plasma. One of de novo synthesized peptides, L-[MeArg(1)]PIK inhibited MLCK activity in vitro with the same efficiency as L-PIK whereas other modified peptides showed reduced inhibitory activity. D-amino acid analog of PIK was the least active inhibitor. Thus, we have demonstrated the possibility to produce an effective MLCK peptide inhibitor with increased resistance to biodegradation that is suitable for further pharmacological development.

  20. Ethidium bromide resistance of L929 cells is accompanied by regular changes in karotype structure

    International Nuclear Information System (INIS)

    Grinchuk, T.M.; Novikova, I.Yu.; Sorokina, E.A.; Sal'nikov, K.V.

    1988-01-01

    Using the method of differential staining of chromosomes for G-bands a comparative karyological analysis of line L 929 mouse cells has been conducted, after the L 929 cells had been sequentially selected for resistance to ethidium bromide at concentrations of 1, 10, 25, and 50 μg/ml and had retained these levels of resistance for a number of cell generations. It was found that the resistant variants exhibited certain karyotypic changes. Only thirteen of the thirty six marker chromosomes typical of the original ethidium bromide-sensitive cells were preserved. Sixteen of the markers were specific for the resistant variants. The changes detected arose at the initial selection stage and were preserved unaltered as the concentration of the toxin was raised. The detection of similar karyotypic changes in cells of clone L 929 of independent origin selected for resistance of 3 μg/ml of ethidium bromide and also in cells of the clone selected for resistance to 25 μg/ml of ethidium bromide and studied previously by the present authors suggests that these changes are universal for L 929 cells resistant to ethidium bromide

  1. Plant breeding by using radiation mutation - Selection of herbicide-resistant cell lines by using {gamma}-rays

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hyo Yeon [Sunchun University, Sunchun (Korea); Seo, Yong Weon [Korea University, Seoul (Korea)

    2000-04-01

    In order to develop the herbicide resistant cell lines, micro calli derived from rice anther culture and mature seed of wheat cultivars were irradiated with gamma rays. 1) The callus was dedifferentiated by 7 or 21 day pretreatment at 7 deg. C in two rice cultivars, Ilpumbyeo ad Dongjinbyeo. 2) To check the optimum concentration of herbicide, three herbicides were tested with micro calli. 3) The optimum dose of gamma ray to seeds of wheat seemed to be from 100 to 150 Gy. 4) AFLP and RAPD technique were established to develope herbicide resistant molecular marker in rice. 34 refs., 10 figs., 5 tabs. (Author)

  2. Reversal of cisplatin resistance in non-small cell lung cancer stem cells by Taxus chinensis var.

    Science.gov (United States)

    Jiang, Y Q; Xu, X P; Guo, Q M; Xu, X C; Liu, Q Y; An, S H; Xu, J L; Su, F; Tai, J B

    2016-09-02

    Drug resistance in cells is a major impedance to successful treatment of lung cancer. Taxus chinensis var. inhibits the growth of tumor cells and promotes the synthesis of interleukins 1 and 2 and tumor necrosis factor, enhancing immune function. In this study, T. chinensis var.-induced cell death was analyzed in lung cancer cells (H460) enriched for stem cell growth in a defined serum-free medium. Taxus-treated stem cells were also analyzed for Rhodamine 123 (Rh-123) expression by flow cytometry, and used as a standard functional indicator of MDR. The molecular basis of T. chinensis var.-mediated drug resistance was established by real-time PCR analysis of ABCC1, ABCB1, and lung resistance-related protein (LRP) mRNA, and western blot analysis of MRP1, MDR1, and LRP. Our results revealed that stem cells treated with higher doses of T. chinensis var. showed significantly lower growth inhibition rates than did H460 cells (P var. and cisplatin was also significantly inhibited (P var. (P var.-treated stem cells showed significant downregulation of the ABCC1, ABCB1, and LRP mRNA and MRP1, MDR1, and LRP (P var.-mediated downregulation of MRP1, MDR1, and LRP might contribute to the reversal of drug resistance in non-small cell lung cancer stem cells.

  3. Logical development of the cell ontology.

    Science.gov (United States)

    Meehan, Terrence F; Masci, Anna Maria; Abdulla, Amina; Cowell, Lindsay G; Blake, Judith A; Mungall, Christopher J; Diehl, Alexander D

    2011-01-05

    The Cell Ontology (CL) is an ontology for the representation of in vivo cell types. As biological ontologies such as the CL grow in complexity, they become increasingly difficult to use and maintain. By making the information in the ontology computable, we can use automated reasoners to detect errors and assist with classification. Here we report on the generation of computable definitions for the hematopoietic cell types in the CL. Computable definitions for over 340 CL classes have been created using a genus-differentia approach. These define cell types according to multiple axes of classification such as the protein complexes found on the surface of a cell type, the biological processes participated in by a cell type, or the phenotypic characteristics associated with a cell type. We employed automated reasoners to verify the ontology and to reveal mistakes in manual curation. The implementation of this process exposed areas in the ontology where new cell type classes were needed to accommodate species-specific expression of cellular markers. Our use of reasoners also inferred new relationships within the CL, and between the CL and the contributing ontologies. This restructured ontology can be used to identify immune cells by flow cytometry, supports sophisticated biological queries involving cells, and helps generate new hypotheses about cell function based on similarities to other cell types. Use of computable definitions enhances the development of the CL and supports the interoperability of OBO ontologies.

  4. Logical Development of the Cell Ontology

    Directory of Open Access Journals (Sweden)

    Blake Judith A

    2011-01-01

    Full Text Available Abstract Background The Cell Ontology (CL is an ontology for the representation of in vivo cell types. As biological ontologies such as the CL grow in complexity, they become increasingly difficult to use and maintain. By making the information in the ontology computable, we can use automated reasoners to detect errors and assist with classification. Here we report on the generation of computable definitions for the hematopoietic cell types in the CL. Results Computable definitions for over 340 CL classes have been created using a genus-differentia approach. These define cell types according to multiple axes of classification such as the protein complexes found on the surface of a cell type, the biological processes participated in by a cell type, or the phenotypic characteristics associated with a cell type. We employed automated reasoners to verify the ontology and to reveal mistakes in manual curation. The implementation of this process exposed areas in the ontology where new cell type classes were needed to accommodate species-specific expression of cellular markers. Our use of reasoners also inferred new relationships within the CL, and between the CL and the contributing ontologies. This restructured ontology can be used to identify immune cells by flow cytometry, supports sophisticated biological queries involving cells, and helps generate new hypotheses about cell function based on similarities to other cell types. Conclusion Use of computable definitions enhances the development of the CL and supports the interoperability of OBO ontologies.

  5. Development of plant-based resist materials in electron beam lithography

    Science.gov (United States)

    Takei, Satoshi; Oshima, Akihiro; Yanamori, Naomi; Sekiguchi, Atsushi; Kozawa, Takahiro; Tagawa, Seiichi

    2011-04-01

    Electron beam lithography has great potential for future production of nano-imprint templates, light-emitting diodes, solar cell devices, actuators, biosensors, and micro electro mechanical systems (MEMS) where continued success ultimately requires improvements in current processing technologies. Electron beam lithography is promising for advancing multiple electronic applications due to several advantages such as high resolution, deep depth of focus, flexibility in material design, and assumable cost. This study presents progress in the development of a new plant-based resist material (TPU-EBR1) to achieve high exposure sensitivity and lower film thickness shrinkage by electron beam irradiation. Highly efficient crosslinking properties and high quality patterning line images were provided by specific process conditions of 30 keV electron beam lithography. Lower film thickness shrinkage of the newly developed TPU-EBR than that of the referenced acrylate type resist material is one of key to achieve EB patterning. The validity of our approach using the developed TPU-EBR was confirmed experimentally. In addition, this new approach was demonstrated to apply glucose and dextrin derivatives as the eco-friendlier compounds to the resist materials in micro and nano-patterning processes for environmentally-compatible electronic device fabrications.

  6. Sensitivity to ionizing radiation and chemotherapeutic agents in gemcitabine-resistant human tumor cell lines

    International Nuclear Information System (INIS)

    Bree, Chris van; Kreder, Natasja Castro; Loves, Willem J.P.; Franken, Nicolaas A.P.; Peters, Godefridus J.; Haveman, Jaap

    2002-01-01

    Purpose: To determine cross-resistance to anti-tumor treatments in 2',2'difluorodeoxycytidine (dFdC, gemcitabine)-resistant human tumor cells. Methods and Materials: Human lung carcinoma cells SW-1573 (SWp) were made resistant to dFdC (SWg). Sensitivity to cisplatin (cDDP), paclitaxel, 5-fluorouracil (5-FU), methotrexate (MTX), cytarabine (ara-C), and dFdC was measured by a proliferation assay. Radiosensitivity and radioenhancement by dFdC of this cell panel and the human ovarian carcinoma cell line A2780 and its dFdC-resistant variant AG6000 were determined by clonogenic assay. Bivariate flowcytometry was performed to study cell cycle changes. Results: In the SWg, a complete deoxycytidine kinase (dCK) deficiency was found on mRNA and protein level. This was accompanied by a 10-fold decrease in dCK activity which resulted in the >1000-fold resistance to dFdC. Sensitivity to other anti-tumor drugs was not altered, except for ara-C (>100-fold resistance). Radiosensitivity was not altered in the dFdC-resistant cell lines SWg and AG6000. High concentrations (50-100 μM dFdC) induced radioenhancement in the dFdC-resistant cell lines similar to the radioenhancement obtained at lower concentrations (10 nM dFdC) in the parental lines. An early S-phase arrest was found in all cell lines after dFdC treatment where radioenhancement was achieved. Conclusions: In the dFdC-resistant lung tumor cell line SWg, the deficiency in dCK is related to the resistance to dFdC and ara-C. No cross-resistance was observed to other anti-tumor drugs used for the treatment in lung cancer. Sensitivity to ionizing radiation was not altered in two different dFdC-resistant cell lines. Resistance to dFdC does not eliminate the ability of dFdC to sensitize cells to radiation

  7. Resistance of renal cell carcinoma to sorafenib is mediated by potentially reversible gene expression.

    Directory of Open Access Journals (Sweden)

    Liang Zhang

    Full Text Available PURPOSE: Resistance to antiangiogenic therapy is an important clinical problem. We examined whether resistance occurs at least in part via reversible, physiologic changes in the tumor, or results solely from stable genetic changes in resistant tumor cells. EXPERIMENTAL DESIGN: Mice bearing two human RCC xenografts were treated with sorafenib until they acquired resistance. Resistant 786-O cells were harvested and reimplanted into naïve mice. Mice bearing resistant A498 cells were subjected to a 1 week treatment break. Sorafenib was then again administered to both sets of mice. Tumor growth patterns, gene expression, viability, blood vessel density, and perfusion were serially assessed in treated vs control mice. RESULTS: Despite prior resistance, reimplanted 786-O tumors maintained their ability to stabilize on sorafenib in sequential reimplantation steps. A transcriptome profile of the tumors revealed that the gene expression profile of tumors upon reimplantation reapproximated that of the untreated tumors and was distinct from tumors exhibiting resistance to sorafenib. In A498 tumors, revascularization was noted with resistance and cessation of sorafenib therapy and tumor perfusion was reduced and tumor cell necrosis enhanced with re-exposure to sorafenib. CONCLUSIONS: In two RCC cell lines, resistance to sorafenib appears to be reversible. These results support the hypothesis that resistance to VEGF pathway therapy is not solely the result of a permanent genetic change in the tumor or selection of resistant clones, but rather is due to a great extent to reversible changes that likely occur in the tumor and/or its microenvironment.

  8. Development of induction cells at CAEP

    International Nuclear Information System (INIS)

    Wang Huacen; Zhang Kaizhi; Cheng Nian'an; Zhang Wenwei; Lai Qinggui; Wen Long; Zhang Linwen; Deng Jianjun; Ding Bonan

    2002-01-01

    The effects to develop induction cells for induction linac and radiography at CAEP are introduced and reviewed in this paper. During the past two decades, several kinds of cells have been designed and tested, and some of them have been used for construction of induction linac, such as Dragon-1 and 12 MeV, and a Synthetic Test Stand (STS) for comprehensive linac technology study. The structure, test results and performance in the induction linac of these cells are given

  9. Hypertranscription in development, stem cells, and regeneration

    Science.gov (United States)

    Percharde, Michelle; Bulut-Karslioglu, Aydan; Ramalho-Santos, Miguel

    2016-01-01

    SUMMARY Cells can globally up-regulate their transcriptome during specific transitions, a phenomenon called hypertranscription. Evidence for hypertranscription dates back over 70 years, but it has gone largely ignored in the genomics era until recently. We discuss data supporting the notion that hypertranscription is a unifying theme in embryonic development, stem cell biology, regeneration and cell competition. We review the history, methods for analysis, underlying mechanisms and biological significance of hypertranscription. PMID:27989554

  10. Collagenase-resistant collagen promotes mouse aging and vascular cell senescence.

    Science.gov (United States)

    Vafaie, Faran; Yin, Hao; O'Neil, Caroline; Nong, Zengxuan; Watson, Alanna; Arpino, John-Michael; Chu, Michael W A; Wayne Holdsworth, David; Gros, Robert; Pickering, J Geoffrey

    2014-02-01

    Collagen fibrils become resistant to cleavage over time. We hypothesized that resistance to type I collagen proteolysis not only marks biological aging but also drives it. To test this, we followed mice with a targeted mutation (Col1a1(r/r) ) that yields collagenase-resistant type I collagen. Compared with wild-type littermates, Col1a1(r/r) mice had a shortened lifespan and developed features of premature aging including kyphosis, weight loss, decreased bone mineral density, and hypertension. We also found that vascular smooth muscle cells (SMCs) in the aortic wall of Col1a1(r/r) mice were susceptible to stress-induced senescence, displaying senescence-associated ß-galactosidase (SA-ßGal) activity and upregulated p16(INK4A) in response to angiotensin II infusion. To elucidate the basis of this pro-aging effect, vascular SMCs from twelve patients undergoing coronary artery bypass surgery were cultured on collagen derived from Col1a1(r/r) or wild-type mice. This revealed that mutant collagen directly reduced replicative lifespan and increased stress-induced SA-ßGal activity, p16(INK4A) expression, and p21(CIP1) expression. The pro-senescence effect of mutant collagen was blocked by vitronectin, a ligand for αvß3 integrin that is presented by denatured but not native collagen. Moreover, inhibition of αvß3 with echistatin or with αvß3-blocking antibody increased senescence of SMCs on wild-type collagen. These findings reveal a novel aging cascade whereby resistance to collagen cleavage accelerates cellular aging. This interplay between extracellular and cellular compartments could hasten mammalian aging and the progression of aging-related diseases. © 2013 The Authors. Aging Cell published by the Anatomical Society and John Wiley & Sons Ltd.

  11. Partial Resistance of Carrot to Alternaria dauci Correlates with In Vitro Cultured Carrot Cell Resistance to Fungal Exudates

    Science.gov (United States)

    Voisine, Linda; Gatto, Julia; Hélesbeux, Jean-Jacques; Séraphin, Denis; Peña-Rodriguez, Luis M.; Richomme, Pascal; Boedo, Cora; Yovanopoulos, Claire; Gyomlai, Melvina; Briard, Mathilde; Simoneau, Philippe; Poupard, Pascal; Berruyer, Romain

    2014-01-01

    Although different mechanisms have been proposed in the recent years, plant pathogen partial resistance is still poorly understood. Components of the chemical warfare, including the production of plant defense compounds and plant resistance to pathogen-produced toxins, are likely to play a role. Toxins are indeed recognized as important determinants of pathogenicity in necrotrophic fungi. Partial resistance based on quantitative resistance loci and linked to a pathogen-produced toxin has never been fully described. We tested this hypothesis using the Alternaria dauci – carrot pathosystem. Alternaria dauci, causing carrot leaf blight, is a necrotrophic fungus known to produce zinniol, a compound described as a non-host selective toxin. Embryogenic cellular cultures from carrot genotypes varying in resistance against A. dauci were confronted with zinniol at different concentrations or to fungal exudates (raw, organic or aqueous extracts). The plant response was analyzed through the measurement of cytoplasmic esterase activity, as a marker of cell viability, and the differentiation of somatic embryos in cellular cultures. A differential response to toxicity was demonstrated between susceptible and partially resistant genotypes, with a good correlation noted between the resistance to the fungus at the whole plant level and resistance at the cellular level to fungal exudates from raw and organic extracts. No toxic reaction of embryogenic cultures was observed after treatment with the aqueous extract or zinniol used at physiological concentration. Moreover, we did not detect zinniol in toxic fungal extracts by UHPLC analysis. These results suggest that strong phytotoxic compounds are present in the organic extract and remain to be characterized. Our results clearly show that carrot tolerance to A. dauci toxins is one component of its partial resistance. PMID:24983469

  12. Extracellular matrix, cell skeletons, and embryonic development.

    Science.gov (United States)

    Hay, E D

    1989-09-01

    During embryonic development, the extracellular matrix (ECM) promotes the production of differentiated products by epithelial cells and the migration of mesenchymal cells, and probably also plays a role in epithelial-mesenchymal transformation. Here we examine the role of the cell skeleton (actin, microtubules, intermediate filaments) in mediating matrix effects on mesenchymal cell morphology, migration, and formation. The interaction of both epithelial cells and mesenchymal cells with ECM seems to involve the actin cortex, which is best developed in the base of the epithelial cell, where it attaches to underlying matrix via membrane-intercalated receptors. To interact with the matrix, the fibroblast has appropriate ECM receptors and an actin cortex around the whole cell. The actin cortex is absolutely required for assumption of bipolar shape, elongation, and movement through the matrix. Since the cortex seems to be anchored to the matrix, it is unlikely that it moves during cell migration. A new hypothesis states that the microtubule- and intermediate filament-rich endoplasm, containing the nucleus, moves past the actin cortex-receptor-matrix complex into the newly synthesized front end of the mesenchymal cell to effect forward movement. When epithelial cells transform into mesenchyme in the embryo, or when they are induced to do this in vitro, they switch from the keratin intermediate filament profile to one rich in vimentin, and the effect of cell matrix interaction on cell shape is profoundly altered. Vimentin-actin interactions with ECM may be a major factor in the ability of a cell to become mesenchymal.(ABSTRACT TRUNCATED AT 250 WORDS)

  13. Transcriptome analysis of chlorantraniliprole resistance development in the diamondback moth Plutella xylostella.

    Directory of Open Access Journals (Sweden)

    Qingsheng Lin

    Full Text Available BACKGROUND: The diamondback moth Plutella xyllostella has developed a high level of resistance to the latest insecticide chlorantraniliprole. A better understanding of P. xylostella's resistance mechanism to chlorantraniliprole is needed to develop effective approaches for insecticide resistance management. PRINCIPAL FINDINGS: To provide a comprehensive insight into the resistance mechanisms of P. xylostella to chlorantraniliprole, transcriptome assembly and tag-based digital gene expression (DGE system were performed using Illumina HiSeq™ 2000. The transcriptome analysis of the susceptible strain (SS provided 45,231 unigenes (with the size ranging from 200 bp to 13,799 bp, which would be efficient for analyzing the differences in different chlorantraniliprole-resistant P. xylostella stains. DGE analysis indicated that a total of 1215 genes (189 up-regulated and 1026 down-regulated were gradient differentially expressed among the susceptible strain (SS and different chlorantraniliprole-resistant P. xylostella strains, including low-level resistance (GXA, moderate resistance (LZA and high resistance strains (HZA. A detailed analysis of gradient differentially expressed genes elucidated the existence of a phase-dependent divergence of biological investment at the molecular level. The genes related to insecticide resistance, such as P450, GST, the ryanodine receptor, and connectin, had different expression profiles in the different chlorantraniliprole-resistant DGE libraries, suggesting that the genes related to insecticide resistance are involved in P. xylostella resistance development against chlorantraniliprole. To confirm the results from the DGE, the expressional profiles of 4 genes related to insecticide resistance were further validated by qRT-PCR analysis. CONCLUSIONS: The obtained transcriptome information provides large gene resources available for further studying the resistance development of P. xylostella to pesticides. The DGE data

  14. Reprogramming mediated radio-resistance of 3D-grown cancer cells

    International Nuclear Information System (INIS)

    Xue Gang; Ren Zhenxin; Chen Yaxiong; Zhu Jiayun; Du Yarong; Pan Dong; Li Xiaoman; Hu Burong; Grabham, Peter W.

    2015-01-01

    In vitro 3D growth of tumors is a new cell culture model that more closely mimics the features of the in vivo environment and is being used increasingly in the field of biological and medical research. It has been demonstrated that cancer cells cultured in 3D matrices are more radio-resistant compared with cells in monolayers. However, the mechanisms causing this difference remain unclear. Here we show that cancer cells cultured in a 3D microenvironment demonstrated an increase in cells with stem cell properties. This was confirmed by the finding that cells in 3D cultures upregulated the gene and protein expression of the stem cell reprogramming factors such as OCT4, SOX2, NANOG, LIN28 and miR-302a, compared with cells in monolayers. Moreover, the expression of β-catenin, a regulating molecule of reprogramming factors, also increased in 3D-grown cancer cells. These findings suggest that cancer cells were reprogrammed to become stem cell-like cancer cells in a 3D growth culture microenvironment. Since cancer stem cell-like cells demonstrate an increased radio-resistance and chemo-resistance, our results offer a new perspective as to why. Our findings shed new light on understanding the features of the 3D growth cell model and its application in basic research into clinical radiotherapy and medicine. (author)

  15. Molecular, biological characterization and drug sensitivity of chidamide-resistant non-small cell lung cancer cells

    Science.gov (United States)

    Luo, Song'e; Ma, Kai; Zhu, Hongxia; Wang, Shuren; Liu, Mei; Zhang, Weina; Liang, Shufang; Xu, Ningzhi

    2017-01-01

    Chidamide, a histone deacetylase (HDAC) inhibitor, has been applied in clinical trials for various types of hematological and solid tumors. Although acquired resistance is common in chemotherapy, the mechanism of resistance to chidamide is poorly characterized. The goal of the present study was to explore, in detail, the mechanism for the induced resistance to chidamide, and investigate a potential cross-resistance to other chemotherapeutic drugs. A549 cells were exposed to gradually increasing chidamide concentrations to establish a chidamide-resistant non-small cell lung cancer cell line (A549-CHI-R). The IC50 for chidamide, the proliferation inhibition rate, the total HDAC activity and the HDAC protein level were determined by an MTT assay, colony formation, a fluorometric HDAC activity assay and western blotting, respectively. Overexpression of the HDAC1 gene and HDAC1 gene-knockdown were achieved via plasmid transfection. A549-CHI-R cells demonstrated increased resistance to chidamide (8.6-fold). HDAC1 protein degradation was inhibited and HDAC activity was significantly higher in the A549-CHI-R cells relative to the parental A549 cells. A549-CHI-R cells demonstrated cross-resistance to paclitaxel, vinorelbine and gemcitabine, but not to cisplatin (CDDP) or 5-fluorouracil (5-FU). These results indicated that HDAC1 may be associated with resistance to chidamide, and HDAC1 may therefore be a predictive marker for chidamide sensitivity in cancer. In addition, A549-CHI-R cells remained sensitive to 5-FU and CDDP, indicating a potential strategy for cancer therapy. PMID:29344124

  16. The fuel cell; development and possibilities

    Energy Technology Data Exchange (ETDEWEB)

    Van Rijnsoever, J.W.M.

    Activities on fuel cells and fuel cell development in the USA and Japan are surveyed. Possibilities for large scale application are mentioned. Attention is given to efficiency and environmental aspects. There are no problems about hazardous emissions. Besides electric power some heat is generated, which is not always a disadvantage. In many cases both are useful products. (A.V.)

  17. Label-free recognition of drug resistance via impedimetric screening of breast cancer cells.

    Directory of Open Access Journals (Sweden)

    Bilge Eker

    Full Text Available We present a novel study on label-free recognition and distinction of drug resistant breast cancer cells (MCF-7 DOX from their parental cells (MCF-7 WT via impedimetric measurements. Drug resistant cells exhibited significant differences in their dielectric properties compared to wild-type cells, exerting much higher extracellular resistance (Rextra . Immunostaining revealed that MCF-7 DOX cells gained a much denser F-actin network upon acquiring drug resistance indicating that remodeling of actin cytoskeleton is probably the reason behind higher Rextra , providing stronger cell architecture. Moreover, having exposed both cell types to doxorubicin, we were able to distinguish these two phenotypes based on their substantially different drug response. Interestingly, impedimetric measurements identified a concentration-dependent and reversible increase in cell stiffness in the presence of low non-lethal drug doses. Combined with a profound frequency analysis, these findings enabled distinguishing distinct cellular responses during drug exposure within four concentration ranges without using any labeling. Overall, this study highlights the possibility to differentiate drug resistant phenotypes from their parental cells and to assess their drug response by using microelectrodes, offering direct, real-time and noninvasive measurements of cell dependent parameters under drug exposure, hence providing a promising step for personalized medicine applications such as evaluation of the disease progress and optimization of the drug treatment of a patient during chemotherapy.

  18. ABCF2, an Nrf2 target gene, contributes to cisplatin resistance in ovarian cancer cells.

    Science.gov (United States)

    Bao, Lingjie; Wu, Jianfa; Dodson, Matthew; Rojo de la Vega, Elisa Montserrat; Ning, Yan; Zhang, Zhenbo; Yao, Ming; Zhang, Donna D; Xu, Congjian; Yi, Xiaofang

    2017-06-01

    Previously, we have demonstrated that NRF2 plays a key role in mediating cisplatin resistance in ovarian cancer. To further explore the mechanism underlying NRF2-dependent cisplatin resistance, we stably overexpressed or knocked down NRF2 in parental and cisplatin-resistant human ovarian cancer cells, respectively. These two pairs of stable cell lines were then subjected to microarray analysis, where we identified 18 putative NRF2 target genes. Among these genes, ABCF2, a cytosolic member of the ABC superfamily of transporters, has previously been reported to contribute to chemoresistance in clear cell ovarian cancer. A detailed analysis on ABCF2 revealed a functional antioxidant response element (ARE) in its promoter region, establishing ABCF2 as an NRF2 target gene. Next, we investigated the contribution of ABCF2 in NRF2-mediated cisplatin resistance using our stable ovarian cancer cell lines. The NRF2-overexpressing cell line, containing high levels of ABCF2, was more resistant to cisplatin-induced apoptosis compared to its control cell line; whereas the NRF2 knockdown cell line with low levels of ABCF2, was more sensitive to cisplatin treatment than its control cell line. Furthermore, transient overexpression of ABCF2 in the parental cells decreased apoptosis and increased cell viability following cisplatin treatment. Conversely, knockdown of ABCF2 using specific siRNA notably increased apoptosis and decreased cell viability in cisplatin-resistant cells treated with cisplatin. This data indicate that the novel NRF2 target gene, ABCF2, plays a critical role in cisplatin resistance in ovarian cancer, and that targeting ABCF2 may be a new strategy to improve chemotherapeutic efficiency. © 2017 Wiley Periodicals, Inc.

  19. An "off-the-shelf" fratricide-resistant CAR-T for the treatment of T cell hematologic malignancies.

    Science.gov (United States)

    Cooper, Matthew L; Choi, Jaebok; Staser, Karl; Ritchey, Julie K; Devenport, Jessica M; Eckardt, Kayla; Rettig, Michael P; Wang, Bing; Eissenberg, Linda G; Ghobadi, Armin; Gehrs, Leah N; Prior, Julie L; Achilefu, Samuel; Miller, Christopher A; Fronick, Catrina C; O'Neal, Julie; Gao, Feng; Weinstock, David M; Gutierrez, Alejandro; Fulton, Robert S; DiPersio, John F

    2018-02-20

    T cell malignancies represent a group of hematologic cancers with high rates of relapse and mortality in patients for whom no effective targeted therapies exist. The shared expression of target antigens between chimeric antigen receptor (CAR) T cells and malignant T cells has limited the development of CAR-T because of unintended CAR-T fratricide and an inability to harvest sufficient autologous T cells. Here, we describe a fratricide-resistant "off-the-shelf" CAR-T (or UCART7) that targets CD7+ T cell malignancies and, through CRISPR/Cas9 gene editing, lacks both CD7 and T cell receptor alpha chain (TRAC) expression. UCART7 demonstrates efficacy against human T cell acute lymphoblastic leukemia (T-ALL) cell lines and primary T-ALL in vitro and in vivo without the induction of xenogeneic GvHD. Fratricide-resistant, allo-tolerant "off-the-shelf" CAR-T represents a strategy for treatment of relapsed and refractory T-ALL and non-Hodgkin's T cell lymphoma without a requirement for autologous T cells.

  20. Development of Cell Analysis Software for Cultivated Corneal Endothelial Cells.

    Science.gov (United States)

    Okumura, Naoki; Ishida, Naoya; Kakutani, Kazuya; Hongo, Akane; Hiwa, Satoru; Hiroyasu, Tomoyuki; Koizumi, Noriko

    2017-11-01

    To develop analysis software for cultured human corneal endothelial cells (HCECs). Software was designed to recognize cell borders and to provide parameters such as cell density, coefficient of variation, and polygonality of cultured HCECs based on phase contrast images. Cultured HCECs with high or low cell density were incubated with Ca-free and Mg-free phosphate-buffered saline for 10 minutes to reveal the cell borders and were then analyzed with software (n = 50). Phase contrast images showed that cell borders were not distinctly outlined, but these borders became more distinctly outlined after phosphate-buffered saline treatment and were recognized by cell analysis software. The cell density value provided by software was similar to that obtained using manual cell counting by an experienced researcher. Morphometric parameters, such as the coefficient of variation and polygonality, were also produced by software, and these values were significantly correlated with cell density (Pearson correlation coefficients -0.62 and 0.63, respectively). The software described here provides morphometric information from phase contrast images, and it enables subjective and noninvasive quality assessment for tissue engineering therapy of the corneal endothelium.

  1. Bcl-2 overexpression is associated with resistance to paclitaxel, but not gemcitabine, in multiple myeloma cells.

    Science.gov (United States)

    Gazitt, Y; Rothenberg, M L; Hilsenbeck, S G; Fey, V; Thomas, C; Montegomrey, W

    1998-10-01

    Multiple myeloma (MM) is an incurable disease despite an initial response-rate of >60% with conventional or high-dose chemotherapy using glucocorticosteroids (i.e. dexamethasone), or alkylating agents (i.e. melphalan). Although these agents are capable of inducing complete remission (CR) in >50% of MM patients, resistance develops rapidly, in >90% of patients, within 2 years of treatment. Therefore, there is a need for new drugs for the treatment of relapsing and refractory MM patients. Gemcitabine (GEM) is a pyrimidine analog that blocks DNA synthesis, whereas, paclitaxel (TAX) is a mitotic spindle poison that promotes microtubular aggregation. Since it appears that these two drugs have different cellular targets, we examined the effect of each drug individually for several parameters and for possible synergy. We studied the cytotoxic effect of TAX and GEM on MM cells expressing varying levels of the antiapoptotic protein bcl-2, which is overexpressed in the majority of myeloma cell from MM patients. We found that both drugs are cytotoxic by inducing apoptosis, however, the extent of apoptosis with TAX, but not with GEM was dependent on the levels of bcl-2 expression. We further investigated t