The cell cycle regulator ecdysoneless cooperates with H-Ras to promote oncogenic transformation of human mammary epithelial cells.

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Bele, Aditya; Mirza, Sameer; Zhang, Ying; Ahmad Mir, Riyaz; Lin, Simon; Kim, Jun Hyun; Gurumurthy, Channabasavaiah Basavaraju; West, William; Qiu, Fang; Band, Hamid; Band, Vimla

2015-01-01

The mammalian ortholog of Drosophila ecdysoneless (Ecd) gene product regulates Rb-E2F interaction and is required for cell cycle progression. Ecd is overexpressed in breast cancer and its overexpression predicts shorter survival in patients with ErbB2-positive tumors. Here, we demonstrate Ecd knock down (KD) in human mammary epithelial cells (hMECs) induces growth arrest, similar to the impact of Ecd Knock out (KO) in mouse embryonic fibroblasts. Furthermore, whole-genome mRNA expression analysis of control vs. Ecd KD in hMECs demonstrated that several of the top 40 genes that were down-regulated were E2F target genes. To address the role of Ecd in mammary oncogenesis, we overexpressed Ecd and/or mutant H-Ras in hTERT-immortalized hMECs. Cell cycle analyses revealed hMECs overexpressing Ecd+Ras showed incomplete arrest in G1 phase upon growth factor deprivation, and more rapid cell cycle progression in growth factor-containing medium. Analyses of cell migration, invasion, acinar structures in 3-D Matrigel and anchorage-independent growth demonstrated that Ecd+Ras-overexpressing cells exhibit substantially more dramatic transformed phenotype as compared to cells expressing vector, Ras or Ecd. Under conditions of nutrient deprivation, Ecd+Ras-overexpressing hMECs exhibited better survival, with substantial upregulation of the autophagy marker LC3 both at the mRNA and protein levels. Significantly, while hMECs expressing Ecd or mutant Ras alone did not form tumors in NOD/SCID mice, Ecd+Ras-overexpressing hMECs formed tumors, clearly demonstrating oncogenic cooperation between Ecd and mutant Ras. Collectively, we demonstrate an important co-oncogenic role of Ecd in the progression of mammary oncogenesis through promoting cell survival.

Novel determinants of H-Ras plasma membrane localization and transformation

DEFF Research Database (Denmark)

Willumsen, B M; Cox, A D; Solski, P A

1996-01-01

cysteine did not abolish palmitoylation. However, despite continued lipid modification the mutant proteins failed to bind to plasma membranes and instead accumulated on internal membranes and, importantly, were not transforming. Addition of an N-terminal myristoylation signal to these defective mutants......, or to proteins entirely lacking the C-terminal 25 residues restored both plasma membrane association and transforming activity. Thus, H-Ras does not absolutely require prenylation or palmitoylation nor indeed its hypervariable domain in order to interact with effectors that ultimately cause transformation....... However, in this native state, the C-terminus appears to provide a combination of lipids and a previously unrecognized signal for specific plasma membrane targeting that are essential for the correct localization and biological function of H-Ras....

A gene expression signature of RAS pathway dependence predicts response to PI3K and RAS pathway inhibitors and expands the population of RAS pathway activated tumors.

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Loboda, Andrey; Nebozhyn, Michael; Klinghoffer, Rich; Frazier, Jason; Chastain, Michael; Arthur, William; Roberts, Brian; Zhang, Theresa; Chenard, Melissa; Haines, Brian; Andersen, Jannik; Nagashima, Kumiko; Paweletz, Cloud; Lynch, Bethany; Feldman, Igor; Dai, Hongyue; Huang, Pearl; Watters, James

2010-06-30

Hyperactivation of the Ras signaling pathway is a driver of many cancers, and RAS pathway activation can predict response to targeted therapies. Therefore, optimal methods for measuring Ras pathway activation are critical. The main focus of our work was to develop a gene expression signature that is predictive of RAS pathway dependence. We used the coherent expression of RAS pathway-related genes across multiple datasets to derive a RAS pathway gene expression signature and generate RAS pathway activation scores in pre-clinical cancer models and human tumors. We then related this signature to KRAS mutation status and drug response data in pre-clinical and clinical datasets. The RAS signature score is predictive of KRAS mutation status in lung tumors and cell lines with high (> 90%) sensitivity but relatively low (50%) specificity due to samples that have apparent RAS pathway activation in the absence of a KRAS mutation. In lung and breast cancer cell line panels, the RAS pathway signature score correlates with pMEK and pERK expression, and predicts resistance to AKT inhibition and sensitivity to MEK inhibition within both KRAS mutant and KRAS wild-type groups. The RAS pathway signature is upregulated in breast cancer cell lines that have acquired resistance to AKT inhibition, and is downregulated by inhibition of MEK. In lung cancer cell lines knockdown of KRAS using siRNA demonstrates that the RAS pathway signature is a better measure of dependence on RAS compared to KRAS mutation status. In human tumors, the RAS pathway signature is elevated in ER negative breast tumors and lung adenocarcinomas, and predicts resistance to cetuximab in metastatic colorectal cancer. These data demonstrate that the RAS pathway signature is superior to KRAS mutation status for the prediction of dependence on RAS signaling, can predict response to PI3K and RAS pathway inhibitors, and is likely to have the most clinical utility in lung and breast tumors.

A gene expression signature of RAS pathway dependence predicts response to PI3K and RAS pathway inhibitors and expands the population of RAS pathway activated tumors

Directory of Open Access Journals (Sweden)

Paweletz Cloud

2010-06-01

Full Text Available Abstract Background Hyperactivation of the Ras signaling pathway is a driver of many cancers, and RAS pathway activation can predict response to targeted therapies. Therefore, optimal methods for measuring Ras pathway activation are critical. The main focus of our work was to develop a gene expression signature that is predictive of RAS pathway dependence. Methods We used the coherent expression of RAS pathway-related genes across multiple datasets to derive a RAS pathway gene expression signature and generate RAS pathway activation scores in pre-clinical cancer models and human tumors. We then related this signature to KRAS mutation status and drug response data in pre-clinical and clinical datasets. Results The RAS signature score is predictive of KRAS mutation status in lung tumors and cell lines with high (> 90% sensitivity but relatively low (50% specificity due to samples that have apparent RAS pathway activation in the absence of a KRAS mutation. In lung and breast cancer cell line panels, the RAS pathway signature score correlates with pMEK and pERK expression, and predicts resistance to AKT inhibition and sensitivity to MEK inhibition within both KRAS mutant and KRAS wild-type groups. The RAS pathway signature is upregulated in breast cancer cell lines that have acquired resistance to AKT inhibition, and is downregulated by inhibition of MEK. In lung cancer cell lines knockdown of KRAS using siRNA demonstrates that the RAS pathway signature is a better measure of dependence on RAS compared to KRAS mutation status. In human tumors, the RAS pathway signature is elevated in ER negative breast tumors and lung adenocarcinomas, and predicts resistance to cetuximab in metastatic colorectal cancer. Conclusions These data demonstrate that the RAS pathway signature is superior to KRAS mutation status for the prediction of dependence on RAS signaling, can predict response to PI3K and RAS pathway inhibitors, and is likely to have the most clinical

Caveolin-1 down-regulation is required for Wnt5a-Frizzled 2 signalling in Ha-RasV12 -induced cell transformation.

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Lin, Hsiu-Kuan; Lin, Hsi-Hui; Chiou, Yu-Wei; Wu, Ching-Lung; Chiu, Wen-Tai; Tang, Ming-Jer

2018-05-01

Caveolin-1 (Cav1) is down-regulated during MK4 (MDCK cells harbouring inducible Ha-Ras V12 gene) transformation by Ha-Ras V12 . Cav1 overexpression abrogates the Ha-Ras V12 -driven transformation of MK4 cells; however, the targeted down-regulation of Cav1 is not sufficient to mimic this transformation. Cav1-silenced cells, including MK4/shCav1 cells and MDCK/shCav1 cells, showed an increased cell area and discontinuous junction-related proteins staining. Cellular and mechanical transformations were completed when MDCK/shCav1 cells were treated with medium conditioned by MK4 cells treated with IPTG (MK4+I-CM) but not with medium conditioned by MK4 cells. Nanoparticle tracking analysis showed that Ha-Ras V12 -inducing MK4 cells increased exosome-like microvesicles release compared with their normal counterparts. The cellular and mechanical transformation activities of MK4+I-CM were abolished after heat treatment and exosome depletion and were copied by exosomes derived from MK4+I-CM (MK4+I-EXs). Wnt5a, a downstream product of Ha-Ras V12 , was markedly secreted by MK4+I-CM and MK4+I-EXs. Suppression of Wnt5a expression and secretion using the porcupine inhibitor C59 or Wnt5a siRNA inhibited the Ha-Ras V12 - and MK4+I-CM-induced transformation of MK4 cells and MDCK/shCav1 cells, respectively. Cav1 down-regulation, either by Ha-Ras V12 or targeted shRNA, increased frizzled-2 (Fzd2) protein levels without affecting its mRNA levels, suggesting a novel role of Cav1 in negatively regulating Fzd2 expression. Additionally, silencing Cav1 facilitated the internalization of MK4+I-EXs in MDCK cells. These data suggest that Cav1-dependent repression of Fzd2 and exosome uptake is potentially relevant to its antitransformation activity, which hinders the activation of Ha-Ras V12 -Wnt5a-Stat3 pathway. Altogether, these results suggest that both decreasing Cav1 and increasing exosomal Wnt5a must be implemented during Ha-Ras V12 -driven cell transformation. © 2018 The Authors

Induction of non-apoptotic programmed cell death by oncogenic RAS in human epithelial cells and its suppression by MYC overexpression.

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Dendo, Kasumi; Yugawa, Takashi; Nakahara, Tomomi; Ohno, Shin-Ichi; Goshima, Naoki; Arakawa, Hirofumi; Kiyono, Tohru

2018-02-09

Oncogenic mutations of RAS genes, found in about 30% of human cancers, are considered to play important roles in cancer development. However, oncogenic RAS can also induce senescence in mouse and human normal fibroblasts. In some cell lines, oncogenic RAS has been reported to induce non-apoptotic programed cell death (PCD). Here, we investigated effects of oncogenic RAS expression in several types of normal human epithelial cells. Oncogenic RAS but not wild-type RAS stimulated macropinocytosis with accumulation of large-phase lucent vacuoles in the cytoplasm, subsequently leading to cell death which was indistinguishable from a recently proposed new type of PCD, methuosis. A RAC1 inhibitor suppressed accumulation of macropinosomes and overexpression of MYC attenuated oncogenic RAS-induced such accumulation, cell cycle arrest and cell death. MYC suppression or rapamycin treatment in some cancer cell lines harbouring oncogenic mutations in RAS genes induced cell death with accumulation of macropinosomes. These results suggest that this type of non-apoptotic PCD is a tumour-suppressing mechanism acting against oncogenic RAS mutations in normal human epithelial cells, which can be overcome by MYC overexpression, raising the possibility that its induction might be a novel approach to treatment of RAS-mutated human cancers. © The Author(s) 2017. Published by Oxford University Press.

Human hypervariable sequences in risk assessment: rare Ha-ras alleles in cancer patients

International Nuclear Information System (INIS)

Krontiris, T.G.; DiMartino, N.A.; Mitcheson, H.D.; Lonergan, J.A.; Begg, C.; Parkinson, D.R.

1987-01-01

A variable tandem repeat (VTR) is responsible for the hyperallelism one kilobase 3' to the human c-Ha-ras-1 (Ha-ras) gene. Thirty-two distinct restriction fragments, comprising 3 allelic classes by frequency of occurrence, have thus far been detected in a sample size of approximately 800 caucasians. Rare Ha-ras alleles, 21 in all, are almost exclusively confined to the genomes of cancer patients. From their data the authors have computed the relative cancer risk associated with possession of a rare Ha-ras allele to be 27. To understand the molecular basis for this phenomenon, they have begun to clone Ha-ras fragments from nontumor DNA of cancer patients. They report here the weak activation, as detected by transfection and transformation of NIH 3T3 mouse cells, of two Ha-ras genes which were obtained from lymphocyte DNA of a melanoma patient. They have mapped the regions that confer this transforming activity to the fragment containing the VTR in one Ha-ras clone and the fragment containing gene coding sequences in the other

Constitutively active RAS signaling reduces 1,25 dihydroxyvitamin D-mediated gene transcription in intestinal epithelial cells by reducing vitamin D receptor expression.

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DeSmet, Marsha L; Fleet, James C

2017-10-01

High vitamin D status is associated with reduced colon cancer risk but these studies ignore the diversity in the molecular etiology of colon cancer. RAS activating mutations are common in colon cancer and they activate pro-proliferative signaling pathways. We examined the impact of RAS activating mutations on 1,25 dihydroxyvitamin D (1,25(OH) 2 D)-mediated gene expression in cultured colon and intestinal cell lines. Transient transfection of Caco-2 cells with a constitutively active mutant K-RAS (G12 V) significantly reduced 1,25(OH) 2 D-induced activity of both a human 25-hydroxyvitamin D, 24 hydroxyase (CYP24A1) promoter-luciferase and an artificial 3X vitamin D response element (VDRE) promoter-luciferase reporter gene. Young Adult Mouse Colon (YAMC) and Rat Intestinal Epithelial (RIE) cell lines with stable expression of mutant H-RAS had suppressed 1,25(OH) 2 D-mediated induction of CYP24A1 mRNA. The RAS effects were associated with lower Vitamin D receptor (VDR) mRNA and protein levels in YAMC and RIE cells and they could be partially reversed by VDR overexpression. RAS-mediated suppression of VDR levels was not due to either reduced VDR mRNA stability or increased VDR gene methylation. However, chromatin accessibility to the VDR gene at the proximal promoter (-300bp), an enhancer region at -6kb, and an enhancer region located in exon 3 was significantly reduced in RAS transformed YAMC cells (YAMC-RAS). These data show that constitutively active RAS signaling suppresses 1,25(OH) 2 D-mediated gene transcription in colon epithelial cells by reducing VDR gene transcription but the mechanism for this suppression is not yet known. These data suggest that cancers with RAS-activating mutations may be less responsive to vitamin D mediated treatment or chemoprevention. Copyright © 2017 Elsevier Ltd. All rights reserved.

Characterization of a novel oncogenic K-ras mutation in colon cancer

International Nuclear Information System (INIS)

Akagi, Kiwamu; Uchibori, Ryosuke; Yamaguchi, Kensei; Kurosawa, Keiko; Tanaka, Yoichiro; Kozu, Tomoko

2007-01-01

Activating mutations of RAS are frequently observed in subsets of human cancers, indicating that RAS activation is involved in tumorigenesis. Here, we identified and characterized a novel G to T transversion mutation of the K-ras gene at the third position of codon 19 (TTG) which substituted phenylalanine for leucine in 3 primary colon carcinomas. Biological and biochemical activity was examined using transformed NIH3T3 cells expressing mutant or wild-type K-ras. Transformants harboring the K-ras mutation at codon 19 showed proliferative capacity under serum-starved conditions, less contact inhibition, anchorage-independent growth, tumorigenicity in nude mice and elevation of active Ras-GTP levels. These results indicated that this novel mutation possesses high oncogenic activity

Ras GTPases Modulate Morphogenesis, Sporulation and Cellulase Gene Expression in the Cellulolytic Fungus Trichoderma reesei

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Zhang, Jiwei; Zhang, Yanmei; Zhong, Yaohua; Qu, Yinbo; Wang, Tianhong

2012-01-01

Background The model cellulolytic fungus Trichoderma reesei (teleomorph Hypocrea jecorina) is capable of responding to environmental cues to compete for nutrients in its natural saprophytic habitat despite its genome encodes fewer degradative enzymes. Efficient signalling pathways in perception and interpretation of environmental signals are indispensable in this process. Ras GTPases represent a kind of critical signal proteins involved in signal transduction and regulation of gene expression. In T. reesei the genome contains two Ras subfamily small GTPases TrRas1 and TrRas2 homologous to Ras1 and Ras2 from S. cerevisiae, but their functions remain unknown. Methodology/Principal Findings Here, we have investigated the roles of GTPases TrRas1 and TrRas2 during fungal morphogenesis and cellulase gene expression. We show that both TrRas1 and TrRas2 play important roles in some cellular processes such as polarized apical growth, hyphal branch formation, sporulation and cAMP level adjustment, while TrRas1 is more dominant in these processes. Strikingly, we find that TrRas2 is involved in modulation of cellulase gene expression. Deletion of TrRas2 results in considerably decreased transcription of cellulolytic genes upon growth on cellulose. Although the strain carrying a constitutively activated TrRas2G16V allele exhibits increased cellulase gene transcription, the cbh1 and cbh2 expression in this mutant still strictly depends on cellulose, indicating TrRas2 does not directly mediate the transmission of the cellulose signal. In addition, our data suggest that the effect of TrRas2 on cellulase gene is exerted through regulation of transcript abundance of cellulase transcription factors such as Xyr1, but the influence is independent of cAMP signalling pathway. Conclusions/Significance Together, these findings elucidate the functions for Ras signalling of T. reesei in cellular morphogenesis, especially in cellulase gene expression, which contribute to deciphering the

Comparative transforming potential of different human papillomaviruses associated with non-melanoma skin cancer

International Nuclear Information System (INIS)

Massimi, Paola; Thomas, Miranda; Bouvard, Veronique; Ruberto, Irene; Campo, M. Saveria; Tommasino, Massimo; Banks, Lawrence

2008-01-01

It is well established that high-risk human papillomaviruses (HPVs) that infect mucosal epithelia are the causative agents of cervical cancer. In contrast, the association of cutaneo-tropic HPV types with the development of non-melanoma skin cancer (NMSC) is less well defined. In this study, we have analysed the in vitro transforming potential of various cutaneous HPV types. Using oncogene cooperation assays with activated ras, we have shown that diverse cutaneous types, including 12, 14, 15, 24, 36 and 49, have significant transforming potential. Interestingly, most of this activity appears to be encoded by the E6 gene product. In contrast, the common HPV-10 exhibits no significant transforming potential in these assays. This difference may be a reflection of different patterns of cellular localization, with transforming E6s being nuclear and non-transforming being cytoplasmic. These results provide molecular support for a role of these viruses in the development of certain human malignancies

Genetic analysis of Ras genes in epidermal development and tumorigenesis

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Drosten, Matthias; Lechuga, Carmen G; Barbacid, Mariano

2013-01-01

Proliferation and differentiation of epidermal keratinocytes are tightly controlled to ensure proper development and homeostasis of the epidermis. The Ras family of small GTPases has emerged as a central node in the coordination of cell proliferation in the epidermis. Recent genetic evidence from mouse models has revealed that the intensity of Ras signaling modulates the proliferative capacity of epidermal keratinocytes. Interfering with Ras signaling either by combined elimination of the 3 Ras genes from the basal layer of the epidermis or by overexpression of dominant-negative Ras isoforms caused epidermal thinning due to hypoproliferation of keratinocytes. In contrast, overexpression of oncogenic Ras mutants in different epidermal cell layers led to hyperproliferative phenotypes including the development of papillomas and squamous cell carcinomas. Here, we discuss the value of loss- and gain-of-function studies in mouse models to assess the role of Ras signaling in the control of epidermal proliferation. PMID:24150175

Andrographolide Sensitizes Ras-Transformed Cells to Radiation in vitro and in vivo

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Hung, Shih-Kai; Hung, Ling-Chien; Kuo, Cheng-Deng

2010-01-01

Purpose: Increasing the sensitivity of tumor cells to radiation is a major goal of radiotherapy. The present study investigated the radiosensitizing effects of andrographolide and examined the molecular mechanisms of andrographolide-mediated radiosensitization. Methods and Materials: An H-ras-transformed rat kidney epithelial (RK3E) cell line was used to measure the radiosensitizing effects of andrographolide in clonogenic assays, 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H tetrazolium bromide assays, and a xenograft tumor growth model. The mechanism of andrographolide-sensitized cell death was analyzed using annexin V staining, caspase 3 activity assays, and terminal transferase uridyl nick end labeling assays. The roles of nuclear factor kappa B (NF-κB) and Akt in andrographolide-mediated sensitization were examined using reporter assays, electrophoretic mobility shift assays, and Western blotting. Results: Concurrent andrographolide treatment (10 μM, 3 h) sensitized Ras-transformed cells to radiation in vitro (sensitizer enhancement ratio, 1.73). Andrographolide plus radiation (one dose of 300 mg/kg peritumor andrographolide and one dose of 6 Gy radiation) resulted in significant tumor growth delay (27 ± 2.5 days) compared with radiation alone (22 ± 1.5 days; p <.05). Radiation induced apoptotic markers (e.g., caspase-3, membrane reversion, DNA fragmentation), and andrographolide treatment did not promote radiation-induced apoptosis. However, the protein level of activated Akt was significantly reduced by andrographolide. NF-κB activity was elevated in irradiated Ras-transformed cells, and andrographolide treatment significantly reduced radiation-induced NF-κB activity. Conclusion: Andrographolide sensitized Ras-transformed cells to radiation both in vitro and in vivo. Andrographolide-mediated radiosensitization was associated with downregulation of Akt and NF-κB activity. These observations indicate that andrographolide is a novel radiosensitizing agent

Rat embryo cells immortalized with transfected oncogenes are transformed by gamma irradiation.

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Endlich, B; Salavati, R; Sullivan, T; Ling, C C

1992-12-01

Cesium-137 gamma rays were used to transform rat embryo cells (REC) which were first transfected with activated c-myc or c-Ha-ras oncogenes to produce immortal cell lines (REC:myc and REC:ras). When exposed to 6 Gy of 137Cs gamma rays, some cells became morphologically transformed with focus formation frequencies of approximately 3 x 10(-4) for REC:myc and approximately 1 x 10(-4) for REC:ras, respectively. Cells isolated from foci of gamma-ray-transformed REC:myc (REC:myc:gamma) formed anchorage-independent colonies and were tumorigenic in nude mice, but foci from gamma-ray-transformed REC:ras (REC:ras:gamma) did not exhibit either of these criteria of transformation. Similar to the results with gamma irradiation, we observed a sequence-dependent phenomenon when myc and ras were transfected into REC, one at a time. REC immortalized by ras transfection were not converted to a tumorigenic phenotype by secondary transfection with myc, but REC transfected with myc were very susceptible to transformation by subsequent ras transfection. This suggests that myc-immortalized cells are more permissive to transformation via secondary treatments. In sequentially transfected REC, myc expression was high whether it was transfected first or second, whereas ras expression was highest when the ras gene was transfected secondarily into myc-containing REC. Molecular analysis of REC:ras:gamma transformants showed no alterations in structure of the transfected ras or of the endogenous ras, myc, p53, or fos genes. The expression of ras and p53 was increased in some isolates of REC:ras:gamma, but myc and fos expression were not affected. Similarly, REC:myc:gamma transformants did not demonstrate rearrangement or amplification of the transfected or the endogenous myc genes, or of the potentially cooperating Ha-, Ki-, or N-ras genes. Northern hybridization analysis revealed increased expression of N-ras in two isolates, REC:myc:gamma 33 and gamma 41, but no alterations in the expression

The role of autophagy in cytotoxicity induced by new oncogenic B-Raf inhibitor UI-152 in v-Ha-ras transformed fibroblasts

International Nuclear Information System (INIS)

Ahn, Jun-Ho; Ahn, Soon Kil; Lee, Michael

2012-01-01

Highlights: ► We recently discovered a potent and selective B-Raf inhibitor, UI-152. ► UI-152 displayed a selective cytotoxicity toward v-Ha-ras transformed cells. ► UI-152-induced growth inhibition was largely meditated by autophagy. ► UI-152 induced paradoxical activation of Raf-1. -- Abstract: In human cancers, B-Raf is the most frequently mutated protein kinase in the MAPK signaling cascade, making it an important therapeutic target. We recently discovered a potent and selective B-Raf inhibitor, UI-152, by using a structure-based drug design strategy. In this study, we examined whether B-Raf inhibition by UI-152 may be an effective therapeutic strategy for eliminating cancer cells transformed with v-Ha-ras (Ras-NIH 3T3). UI-152 displayed selective cytotoxicity toward Ras-NIH 3T3 cells while having little to no effect on non-transformed NIH 3T3 cells. We found that treatment with UI-152 markedly increased autophagy and, to a lesser extent, apoptosis. However, inhibition of autophagy by addition of 3-MA failed to reverse the cytotoxic effects of UI-152 on Ras-NIH 3T3 cells, demonstrating that apoptosis and autophagy can act as cooperative partners to induce growth inhibition in Ras-NIH 3T3 cells treated with UI-152. Most interestingly, cell responses to UI-152 appear to be paradoxical. Here, we showed that although UI-152 inhibited ERK, it induced B-Raf binding to Raf-1 as well as Raf-1 activation. This paradoxical activation of Raf-1 by UI-152 is likely to be coupled with the inhibition of the mTOR pathway, an intracellular signaling pathway involved in autophagy. We also showed for the first time that, in multi-drug resistant cells, the combination of UI-152 with verapamil significantly decreased cell proliferation and increased autophagy. Thus, our findings suggest that the inhibition of autophagy, in combination with UI-152, offers a more effective therapeutic strategy for v-Ha-ras-transformed cells harboring wild-type B-Raf.

Active Erk Regulates Microtubule Stability in H-ras-Transformed Cells

Directory of Open Access Journals (Sweden)

Rene E. Harrison

2001-01-01

Full Text Available Increasing evidence suggests that activated erk regulates cell functions, at least in part, by mechanisms that do not require gene transcription. Here we show that the map kinase, erk, decorates microtubules (MTs and mitotic spindles in both parental and mutant active rastransfected 10T1 /2 fibroblasts and MCF10A breast epithelial cells. Approximately 20% of total cellular erk decorated MTs in both cell lines. A greater proportion of activated erk was associated with MTs in the presence of mutant active H-ras than in parental cells. Activation of erk by the ras pathway coincided with a decrease in the stability of MT, as detected by a stability marker. The MKK1 inhibitor, PD98059 and transfection of a dominant negative MKK1 blocked ras-induced instability of MTs but did not modify the association of erk with MTs or affect MT stability of the parental cells. These results indicate that the subset of active erk kinase that associates with MTs contributes to their instability in the presence of a mutant active ras. The MT-associated subset of active erk likely contributes to the enhanced invasive and proliferative abilities of cells containing mutant active H-ras.

Change of mitotic cycle and DNA repair in embryonic cells of rat, immortalized by E1 A oncogene and transformated by E1 A and c-Ha-Ras oncogenes under ionizing radiation action

International Nuclear Information System (INIS)

Kirillova, T.V.

1997-01-01

Comparison investigation into the repair of mitotic cycle and the reunion of DN single- and double-strand breaks in gamma-ray irradiated initial E1 A oncogene immortalized and E1 A and c-Ha-Ras oncogene transformed (mutant form) lines of rat embryonic fibroblasts was carried out. Possible involvement of Ras gene product in DNA repair speed governing and absence of tumor suppression function of p 53 protein in the embryonic and E1 A oncogene immortalized cells of rat fibroblast, as well as, presence of the mentioned function of p 53 protein in E1 A and c-Ha-Ras oncogene transformed cells were studied [ru

The absence of an association between Interleukin 1β gene polymorphisms and recurrent aphthous stomatitis (RAS).

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Ślebioda, Zuzanna; Kowalska, Anna; Rozmiarek, Marta; Krawiecka, Ewa; Szponar, Elżbieta; Dorocka-Bobkowska, Barbara

2017-12-01

Recurrent aphthous stomatitis (RAS) is a chronic, ulcerative disease with a probable polygenic mode of inheritance and complex etiology with a strong immunological background. The aim of the present study was to determine the possible association between two single nucleotide polymorphisms (SNPs) of the IL-1β gene: IL-1β-511 T>C (rs16944) and IL-1β+3954C>T (rs1143634) and RAS susceptibility in a moderately large group of patients. One hundred and four patients with minor, major and herpetiform RAS and 75 healthy volunteers were genotyped at IL-1β-511 T>C (rs16944) and IL-1β+3954C>T (rs1143634) using the PCR-RFLP approach. The results were statistically analysed with chi-square test and test of difference between two rates of structure, with p<0.05 assumed to be a statistically significance level (Statistica 10, StatSoft ® , Kraków, Poland). There were no statistically significant differences in the genotype distribution for the IL-1β C[+3954]T polymorphism between the RAS and control groups. The frequency of IL-1β*T[-511]/*T[-511] homozygotes among the patients was significantly higher when compared to our study control (p<0.0347). The results after stratification into carriers and non-carriers of C and T alleles did not clearly indicate which SNP may be considered a risk factor for RAS. The genetic association between the studied SNPs of the IL-1β gene and RAS remains controversial and requires further investigation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Novel approach to abuse the hyperactive K-Ras pathway for adenoviral gene therapy of colorectal cancer

International Nuclear Information System (INIS)

Naumov, Inna; Kazanov, Dina; Lisiansky, Victoria; Starr, Alex; Aroch, Ilan; Shapira, Shiran; Kraus, Sarah; Arber, Nadir

2012-01-01

Background: Functional activation of oncogenic K-Ras signaling pathway plays an important role in the early events of colorectal carcinogenesis (CRC). K-Ras proto-oncogene is involved in 35–40% of CRC cases. Mutations in the Ras gene trigger the transduction of proliferative and anti-apoptotic signals, even in the absence of extra cellular stimuli. The objective of the current study was to use a gene-targeting approach to kill human CRC cells selectively harboring mutated K-Ras. Results: A recombinant adenovirus that carries a lethal gene, PUMA, under the control of a Ras responsive promoter (Ad-Py4-SV40-PUMA) was used selectively to target CRC cells (HCT116, SW480, DLD1 and RIE-Ras) that possess a hyperactive Ras pathway while using HT29 and RIE cells as a control that harbors wild type Ras and exhibit very low Ras activity. Control vector, without the Ras responsive promoter elements was used to assess the specificity of our “gene therapy” approach. Both adenoviral vectors were assed in vitro and in xenograft model in vivo. Ad-Py4-SV40-PUMA showed high potency to induce ∼ 50% apoptosis in vitro, to abolish completely tumor formation by infecting cells with the Ad-Py4-SV40-PUMA prior xenografting them in nude mice and high ability to suppress by ∼ 35% tumor progression in vivo in already established tumors. Conclusions: Selective targeting of CRC cells with the activated Ras pathway may be a novel and effective therapy in CRC. The high potency of this adenoviral vector may help to overcome an undetectable micro metastasis that is the major hurdle in challenging with CRC.

Novel approach to abuse the hyperactive K-Ras pathway for adenoviral gene therapy of colorectal cancer

Energy Technology Data Exchange (ETDEWEB)

Naumov, Inna [Integrated Cancer Prevention Center, Tel Aviv (Israel); Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv (Israel); Kazanov, Dina [Integrated Cancer Prevention Center, Tel Aviv (Israel); Lisiansky, Victoria [Integrated Cancer Prevention Center, Tel Aviv (Israel); Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv (Israel); Starr, Alex [Lung and Allergy Institute, Tel Aviv Sourasky Medical Center, Tel Aviv (Israel); Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv (Israel); Aroch, Ilan; Shapira, Shiran; Kraus, Sarah [Integrated Cancer Prevention Center, Tel Aviv (Israel); Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv (Israel); Arber, Nadir, E-mail: narber@post.tau.ac.il [Integrated Cancer Prevention Center, Tel Aviv (Israel); Department of Gastroenterology, Tel Aviv Sourasky Medical Center, Tel Aviv (Israel); Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv (Israel)

2012-01-15

Background: Functional activation of oncogenic K-Ras signaling pathway plays an important role in the early events of colorectal carcinogenesis (CRC). K-Ras proto-oncogene is involved in 35-40% of CRC cases. Mutations in the Ras gene trigger the transduction of proliferative and anti-apoptotic signals, even in the absence of extra cellular stimuli. The objective of the current study was to use a gene-targeting approach to kill human CRC cells selectively harboring mutated K-Ras. Results: A recombinant adenovirus that carries a lethal gene, PUMA, under the control of a Ras responsive promoter (Ad-Py4-SV40-PUMA) was used selectively to target CRC cells (HCT116, SW480, DLD1 and RIE-Ras) that possess a hyperactive Ras pathway while using HT29 and RIE cells as a control that harbors wild type Ras and exhibit very low Ras activity. Control vector, without the Ras responsive promoter elements was used to assess the specificity of our 'gene therapy' approach. Both adenoviral vectors were assed in vitro and in xenograft model in vivo. Ad-Py4-SV40-PUMA showed high potency to induce {approx} 50% apoptosis in vitro, to abolish completely tumor formation by infecting cells with the Ad-Py4-SV40-PUMA prior xenografting them in nude mice and high ability to suppress by {approx} 35% tumor progression in vivo in already established tumors. Conclusions: Selective targeting of CRC cells with the activated Ras pathway may be a novel and effective therapy in CRC. The high potency of this adenoviral vector may help to overcome an undetectable micro metastasis that is the major hurdle in challenging with CRC.

The RAS Initiative

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NCI established the RAS Initiative to explore innovative approaches for attacking the proteins encoded by mutant forms of RAS genes and to ultimately create effective, new therapies for RAS-related cancers.

Development of a High-Throughput Gene Expression Screen for Modulators of RAS-MAPK Signaling in a Mutant RAS Cellular Context.

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Severyn, Bryan; Nguyen, Thi; Altman, Michael D; Li, Lixia; Nagashima, Kumiko; Naumov, George N; Sathyanarayanan, Sriram; Cook, Erica; Morris, Erick; Ferrer, Marc; Arthur, Bill; Benita, Yair; Watters, Jim; Loboda, Andrey; Hermes, Jeff; Gilliland, D Gary; Cleary, Michelle A; Carroll, Pamela M; Strack, Peter; Tudor, Matt; Andersen, Jannik N

2016-10-01

The RAS-MAPK pathway controls many cellular programs, including cell proliferation, differentiation, and apoptosis. In colorectal cancers, recurrent mutations in this pathway often lead to increased cell signaling that may contribute to the development of neoplasms, thereby making this pathway attractive for therapeutic intervention. To this end, we developed a 26-member gene signature of RAS-MAPK pathway activity utilizing the Affymetrix QuantiGene Plex 2.0 reagent system and performed both primary and confirmatory gene expression-based high-throughput screens (GE-HTSs) using KRAS mutant colon cancer cells (SW837) and leveraging a highly annotated chemical library. The screen achieved a hit rate of 1.4% and was able to enrich for hit compounds that target RAS-MAPK pathway members such as MEK and EGFR. Sensitivity and selectivity performance measurements were 0.84 and 1.00, respectively, indicating high true-positive and true-negative rates. Active compounds from the primary screen were confirmed in a dose-response GE-HTS assay, a GE-HTS assay using 14 additional cancer cell lines, and an in vitro colony formation assay. Altogether, our data suggest that this GE-HTS assay will be useful for larger unbiased chemical screens to identify novel compounds and mechanisms that may modulate the RAS-MAPK pathway. © 2016 Society for Laboratory Automation and Screening.

DA-Raf, a dominant-negative antagonist of the Ras-ERK pathway, is a putative tumor suppressor.

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Kanno, Emiri; Kawasaki, Osamu; Takahashi, Kazuya; Takano, Kazunori; Endo, Takeshi

2018-01-01

Activating mutations of RAS genes, particularly KRAS, are detected with high frequency in human tumors. Mutated Ras proteins constitutively activate the ERK pathway (Raf-MEK-ERK phosphorylation cascade), leading to cellular transformation and tumorigenesis. DA-Raf1 (DA-Raf) is a splicing variant of A-Raf and contains the Ras-binding domain (RBD) but lacks the kinase domain. Accordingly, DA-Raf antagonizes the Ras-ERK pathway in a dominant-negative fashion and suppresses constitutively activated K-Ras-induced cellular transformation. Thus, we have addressed whether DA-Raf serves as a tumor suppressor of Ras-induced tumorigenesis. DA-Raf(R52Q), which is generated from a single nucleotide polymorphism (SNP) in the RBD, and DA-Raf(R52W), a mutant detected in a lung cancer, neither bound to active K-Ras nor interfered with the activation of the ERK pathway. They were incapable of suppressing activated K-Ras-induced cellular transformation and tumorigenesis in mice, in which K-Ras-transformed cells were transplanted. Furthermore, although DA-Raf was highly expressed in lung alveolar epithelial type 2 (AE2) cells, its expression was silenced in AE2-derived lung adenocarcinoma cell lines with oncogenic KRAS mutations. These results suggest that DA-Raf represents a tumor suppressor protein against Ras-induced tumorigenesis. Copyright © 2017 Elsevier Inc. All rights reserved.

Alterations in the K-ras and p53 genes in rat lung tumors

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Belinsky, S.A.; Swafford, D.S.; Finch, G.L.; Mitchell, C.E. [Inhalation Toxicology Research Institute, Albuquerque, NM (United States)] [and others

1997-06-01

Activation of the K-ras protooncogene and inactivation of the p53 tumor suppressor gene are events common to many types of human cancers. Molecular epidemiology studies have associated mutational profiles in these genes with specific exposures. The purpose of this paper is to review investigations that have examined the role of the K-ras and p53 genes in lung tumors induced in the F344 rat by mutagenic and nonmutagenic exposures. Mutation profiles within the K-ras and p53 genes, if present in rat lung tumors, would help to define some of the molecular mechanisms underlying cancer induction by various environmental agents. Pulmonary adenocarcinomas or squamous cell carcinomas were induced by tetranitromethane (TNM), 4-methylnitrosamino-1-(3-pyridyl)-1-butanone (NNK), beryllium metal, plutonium-239, X-ray, diesel exhaust, or carbon black. These agents were chosen because the tumors they produced could arise via different types of DNA damage. Mutation of the K-ras gene was determined by approaches that included DNA transfection, direct sequencing, mismatch hybridization, and restriction fragment length polymorphism analysis. The frequency for mutation of the K-ras gene was exposure dependent. The transition mutations formed could have been derived from deamination of cytosine. Alteration in the p53 gene was assessed by immunohistochemical analysis for p53 protein and single-strand conformation polymorphism (SSCP) analysis of exons 4 to 9. None of the 93 adenocarinomas examined was immunoreactive toward the anti-p53 antibody CM1. In contrast, 14 of 71 squamous cell carcinomas exhibited nuclear p53 immunoreactivity with no correlation to type of exposure. However, SSCP analysis only detected mutations in 2 of 14 squamous cell tumors that were immunoreactive, suggesting that protein stabilization did not stem from mutations within the p53 gene. Thus, the p53 gene does not appear to be involved in the genesis of most rat lung tumors. 2 figs., 2 tabs., 48 refs.

Oncogenic ras-driven cancer cell vesiculation leads to emission of double-stranded DNA capable of interacting with target cells

International Nuclear Information System (INIS)

Lee, Tae Hoon; Chennakrishnaiah, Shilpa; Audemard, Eric; Montermini, Laura; Meehan, Brian; Rak, Janusz

2014-01-01

Highlights: • Oncogenic H-ras stimulates emission of extracellular vesicles containing double-stranded DNA. • Vesicle-associated extracellular DNA contains mutant N-ras sequences. • Vesicles mediate intercellular transfer of mutant H-ras DNA to normal fibroblasts where it remains for several weeks. • Fibroblasts exposed to vesicles containing H-ras DNA exhibit increased proliferation. - Abstract: Cell free DNA is often regarded as a source of genetic cancer biomarkers, but the related mechanisms of DNA release, composition and biological activity remain unclear. Here we show that rat epithelial cell transformation by the human H-ras oncogene leads to an increase in production of small, exosomal-like extracellular vesicles by viable cancer cells. These EVs contain chromatin-associated double-stranded DNA fragments covering the entire host genome, including full-length H-ras. Oncogenic N-ras and SV40LT sequences were also found in EVs emitted from spontaneous mouse brain tumor cells. Disruption of acidic sphingomyelinase and the p53/Rb pathway did not block emission of EV-related oncogenic DNA. Exposure of non-transformed RAT-1 cells to EVs containing mutant H-ras DNA led to the uptake and retention of this material for an extended (30 days) but transient period of time, and stimulated cell proliferation. Thus, our study suggests that H-ras-mediated transformation stimulates vesicular emission of this histone-bound oncogene, which may interact with non-transformed cells

Oncogenic ras-driven cancer cell vesiculation leads to emission of double-stranded DNA capable of interacting with target cells

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Lee, Tae Hoon; Chennakrishnaiah, Shilpa [Montreal Children’s Hospital, Research Institute of McGill University Health Centre, McGill University, Montreal, Quebec (Canada); Audemard, Eric [McGill University and Genome Quebec Innovation Centre, Montreal, Quebec (Canada); Montermini, Laura; Meehan, Brian [Montreal Children’s Hospital, Research Institute of McGill University Health Centre, McGill University, Montreal, Quebec (Canada); Rak, Janusz, E-mail: janusz.rak@mcgill.ca [Montreal Children’s Hospital, Research Institute of McGill University Health Centre, McGill University, Montreal, Quebec (Canada)

2014-08-22

Highlights: • Oncogenic H-ras stimulates emission of extracellular vesicles containing double-stranded DNA. • Vesicle-associated extracellular DNA contains mutant N-ras sequences. • Vesicles mediate intercellular transfer of mutant H-ras DNA to normal fibroblasts where it remains for several weeks. • Fibroblasts exposed to vesicles containing H-ras DNA exhibit increased proliferation. - Abstract: Cell free DNA is often regarded as a source of genetic cancer biomarkers, but the related mechanisms of DNA release, composition and biological activity remain unclear. Here we show that rat epithelial cell transformation by the human H-ras oncogene leads to an increase in production of small, exosomal-like extracellular vesicles by viable cancer cells. These EVs contain chromatin-associated double-stranded DNA fragments covering the entire host genome, including full-length H-ras. Oncogenic N-ras and SV40LT sequences were also found in EVs emitted from spontaneous mouse brain tumor cells. Disruption of acidic sphingomyelinase and the p53/Rb pathway did not block emission of EV-related oncogenic DNA. Exposure of non-transformed RAT-1 cells to EVs containing mutant H-ras DNA led to the uptake and retention of this material for an extended (30 days) but transient period of time, and stimulated cell proliferation. Thus, our study suggests that H-ras-mediated transformation stimulates vesicular emission of this histone-bound oncogene, which may interact with non-transformed cells.

Upstream CREs participate in the basal activity of minute virus of mice promoter P4 and in its stimulation in ras-transformed cells.

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Perros, M; Deleu, L; Vanacker, J M; Kherrouche, Z; Spruyt, N; Faisst, S; Rommelaere, J

1995-01-01

The activity of the P4 promoter of the parvovirus minute virus of mice (prototype strain MVMp) is stimulated in ras-transformed FREJ4 cells compared with the parental FR3T3 line. This activation may participate in the oncolytic effect of parvoviruses, given that P4 drives a transcriptional unit encoding cytotoxic nonstructural proteins. Our results suggest that the higher transcriptional activity of promoter P4 in FREJ4 cells is mediated at least in part by upstream CRE elements. Accordingly, mutations in the CRE motifs impair P4 function more strongly in the FREJ4 derivative than in its FR3T3 parent. Further evidence that these elements contribute to hyperactivity of the P4 promoter in the ras transformant is the fact that they form distinct complexes with proteins from FREJ4 and FR3T3 cell extracts. This difference can be abolished by treating the FREJ4 cell extracts with cyclic AMP-dependent protein kinase (PKA) or treating original cultures with a PKA activator. These findings can be linked with two previously reported features of ras-transformed cells: the activation of a PKA-inhibited protein kinase cascade and the reduction of PKA-induced protein phosphorylation. In keeping with these facts, P4-directed gene expression can be up- or downmodulated in vivo by exposing cells to known inhibitors or activators of PKA, respectively. PMID:7636996

Radiosensitivity and ras oncogene expression in preneoplastic rat tracheal epithelial cells

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Thomassen, D.G.; Wuensch, S.A.; Kelly, G.

1988-01-01

The sensitivity of preneoplastic rat tracheal epithelial (RTE) cells to the cytotoxic effects of high- and low-LET radiation, and the modulating effect of the viral ras oncogene on this sensitivity were determined. Two lines of preneoplastic RTE cells have the same responsiveness to high-LET radiation, but differ in their responsiveness to a transfected ras oncogene and in their sensitivities to low-LET radiation. Cells that respond to ras by becoming neoplastic are more resistant to the cytotoxic effects of low-LET radiation than cells that are not transformable by ras. The radiosensitivity of ras-responsive cells was not altered by transfection with ras. However, transfection of ras-non responsive cells with ras decreased their sensitivity to low-LET radiation. These data suggest that the ability of cells to repair radiation damage changes as they progress to neoplasia. (author)

Bioinformatics of non small cell lung cancer and the ras proto-oncogene

CERN Document Server

Kashyap, Amita; Babu M, Naresh

2015-01-01

Cancer is initiated by activation of oncogenes or inactivation of tumor suppressor genes. Mutations in the K-ras proto-oncogene are responsible for 10–30% of adenocarcinomas. Clinical Findings point to a wide variety of other cancers contributing to lung cancer incidence. Such a scenario makes identification of lung cancer difficult and thus identifying its mechanisms can contribute to the society. Identifying unique conserved patterns common to contributing proto-oncogenes may further be a boon to Pharmacogenomics and pharmacoinformatics. This calls for ab initio/de novo drug discovery that in turn will require a comprehensive in silico approach of Sequence, Domain, Phylogenetic and Structural analysis of the receptors, ligand screening and optimization and detailed Docking studies. This brief involves extensive role of the RAS subfamily that includes a set of proteins, which cause an over expression of cancer-causing genes like M-ras and initiate tumour formation in lungs. SNP Studies and Structure based ...

Multistep carcinogenesis of normal human fibroblasts. Human fibroblasts immortalized by repeated treatment with Co-60 gamma rays were transformed into tumorigenic cells with Ha-ras oncogenes.

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Namba, M; Nishitani, K; Fukushima, F; Kimoto, T

1988-01-01

Two normal mortal human fibroblast cell strains were transformed into immortal cell lines, SUSM-1 and KMST-6, by treatment with 4-nitroquinoline 1-oxide (4NQO) and Co-60 gamma rays, respectively. These immortalized cell lines showed morphological changes of cells and remarkable chromosome aberrations, but neither of them grew in soft agar or formed tumors in nude mice. The immortal cell line, KMST-6, was then converted into neoplastic cells by treatment with Harvey murine sarcoma virus (Ha-MSV) or the c-Ha-ras oncogene derived from a human lung carcinoma. These neoplastically transformed cells acquired anchorage-independent growth potential and developed tumors when transplanted into nude mice. All the tumors grew progressively without regression until the animals died of tumors. In addition, the tumors were transplantable into other nude mice. Normal human fibroblasts, on the other hand, were not transformed into either immortal or tumorigenic cells by treatment with Ha-MSV or c-Ha-ras alone. Our present data indicate that (1) the chemical carcinogen, 4NQO, or gamma rays worked as an initiator of carcinogenesis in normal human cells, giving rise to immortality, and (2) the ras gene played a role in the progression of the immortally transformed cells to more malignant cells showing anchorage-independent growth and tumorigenicity. In other words, the immortalization process of human cells seems to be a pivotal or rate-limiting step in the carcinogenesis of human cells.

Ha-ras oncogene expression directed by a milk protein gene promoter: tissue specificity, hormonal regulation, and tumor induction in transgenic mice

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Andres, A.C.; Schoenenberger, C.A.; Groner, B.; Henninghausen, L.; LeMeur, M.; Gelinger, P.

1987-01-01

The activated human Ha-ras oncogene was subjected to the control of the promoter region of the murine whey acidic protein (Wap) gene, which is expressed in mammary epithelial cells in response to lactogenic hormones. The Wap-ras gene was stably introduced into the mouse germ line of five transgenic mice (one male and four females). Wap-ras expression was observed in the mammary glands of lactating females in two lines derived from female founders. The tissue-directed and hormone-dependent Wap expression was conferred on the Ha-ras oncogene. The signals governing Wap expression are located within 2.5 kilobases of 5' flanking sequence. The other two lines derived from female founders did not express the chimeric gene. In the line derived from the male founder the Wap-ras gene is integrated into the Y chromosome. Expression was found in the salivary gland of male animals only. After a long latency, Wap-ras-expressing mice developed tumors. The tumors arose in tissues expressing Wap-ras - i.e., mammary or salivary glands. Compared to the corresponding nonmalignant tissues, Wap-ras expression was enhanced in the tumors

[miR-143 inhibits cell proliferation through targeted regulating the expression of K-ras gene in HeLa cells].

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Qin, H X; Cui, H K; Pan, Y; Hu, R L; Zhu, L H; Wang, S J

2016-12-23

Objective: To explore the effect of microRNA miR-143 on the proliferation of cervical cancer HeLa cells through targeted regulating the expression of K-ras gene. Methods: The luciferase report carrier containing wild type 3'-UTR of K-ras gene (K-ras-wt) or mutated 3'-UTR of the K-ras (K-ras-mut) were co-transfected with iR-143 mimic into the HeLa cells respectively, and the targeting effect of miR-143 in the transfectants was verified by the dual luciferase report system. HeLa cells were also transfected with miR-143 mimic (miR-143 mimic group), mimic control (negative control group), and miR-143 mimic plus K-ras gene (miR-143 mimic+ K-ras group), respectively. The expression of miR-143 in the transfected HeLa cells was detected by real-time PCR (RT-PCR), and the expression of K-ras protein was detected by Western blot. The cell proliferation activity of each group was examined by MTT assay. In addition, human cervical cancer tissue samples ( n =5) and cervical intraepithelial neoplasia tissue samples ( n =5) were also examined for the expression of miR-143 and K-ras protein by RT-PCR and Western blot, respectively. Results: The luciferase report assay showed that co-transfection with miR-143 mimic decreased the luciferase activity of the K-ras-wt significantly, but did not inhibit the luciferase activity of the K-ras-mut. The expression of miR-143 in the HeLa cells transfected with miR-143 mimic was significantly higher than that in the HeLa cells transfected with the mimic control (3.31±0.45 vs 0.97±0.22, P cell proliferative activity of the miR-143 mimic group was significantly lower than that of the negative control group ( P cell proliferative activity of the miR-143 mimic+ K-ras group was also significantly lower than the control group ( P HeLa cells through targeted regulating the expression of K-ras gene. In human cervical cancer tissues of a small sample set, the expression of miR-143 is downregulated, and the expression of K-ras is upregulated.

Molecular interaction between K-Ras and H-REV107 in the Ras signaling pathway.

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Han, Chang Woo; Jeong, Mi Suk; Jang, Se Bok

2017-09-16

Ras proteins are small GTPases that serve as master moderators of a large number of signaling pathways involved in various cellular processes. Activating mutations in Ras are found in about one-third of cancers. H-REV107, a K-Ras binding protein, plays an important role in determining K-Ras function. H-REV107 is a member of the HREV107 family of class II tumor suppressor genes and a growth inhibitory Ras target gene that suppresses cellular growth, differentiation, and apoptosis. Expression of H-REV107 was strongly reduced in about 50% of human carcinoma cell lines. However, the specific molecular mechanism by which H-REV107 inhibits Ras is still unknown. In the present study, we suggest that H-REV107 forms a strong complex with activating oncogenic mutation Q61H K-Ras from various biochemical binding assays and modeled structures. In addition, the interaction sites between K-Ras and H-REV107 were predicted based on homology modeling. Here, we found that some structure-based mutants of the K-Ras disrupted the complex formation with H-REV107. Finally, a novel molecular mechanism describing K-Ras and H-REV107 binding is suggested and insights into new K-Ras effector target drugs are provided. Copyright © 2017 Elsevier Inc. All rights reserved.

Involvement of H- and N-Ras isoforms in transforming growth factor-β1-induced proliferation and in collagen and fibronectin synthesis

International Nuclear Information System (INIS)

Martinez-Salgado, Carlos; Fuentes-Calvo, Isabel; Garcia-Cenador, Begona; Santos, Eugenio; Lopez-Novoa, Jose M.

2006-01-01

Transforming growth factor β1 (TGF-β1) has a relevant role in the origin and maintenance of glomerulosclerosis and tubule-interstitial fibrosis. TGF-β and Ras signaling pathways are closely related: TGF-β1 overcomes Ras mitogenic effects and Ras counteracts TGF-β signaling. Tubule-interstitial fibrosis is associated to increases in Ras, Erk, and Akt activation in a renal fibrosis model. We study the role of N- and H-Ras isoforms, and the involvement of the Ras effectors Erk and Akt, in TGF-β1-mediated extracellular matrix (ECM) synthesis and proliferation, using embrionary fibroblasts from double knockout (KO) mice for H- and N-Ras (H-ras -/- /N-ras -/- ) isoforms and from heterozygote mice (H-ras +/- /N-ras +/- ). ECM synthesis is increased in basal conditions in H-ras -/- /N-ras -/- fibroblasts, this increase being higher after stimulation with TGF-β1. TGF-β1-induced fibroblast proliferation is smaller in H-ras -/- /N-ras -/- than in H-ras +/- /N-ras +/- fibroblasts. Erk activation is decreased in H-ras -/- /N-ras -/- fibroblasts; inhibition of Erk activation reduces fibroblast proliferation. Akt activation is higher in double KO fibroblasts than in heterozygotes; inhibition of Akt activation also inhibits ECM synthesis. We suggest that H- and N-Ras isoforms downregulate ECM synthesis, and mediate proliferation, in part through MEK/Erk activation. PI3K-Akt pathway activation may be involved in the increase in ECM synthesis observed in the absence of H- and N-Ras

About the RAS Initiative

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The RAS Initiative, a "hub and spoke" model, connects researchers to better understand and target the more than 30% of cancers driven by mutations in RAS genes. Includes oversight and contact information.

Identification of a c-Jun N-terminal kinase-2-dependent signal amplification cascade that regulates c-Myc levels in ras transformation

DEFF Research Database (Denmark)

Mathiasen, D.P.; Egebjerg, C.; Andersen, S.H.

2012-01-01

are essential for ras transformation. Previous studies show that ERK-mediated serine 62 phosphorylation protects c-Myc from proteasomal degradation. ERK is, however, not alone sufficient to stabilize c-Myc but requires the cooperation of cancerous inhibitor of protein phosphatase 2A (CIP2A), an oncogene...... that counteracts protein phosphatase 2A-mediated dephosphorylation of c-Myc. Here we show that JNK2 regulates Cip2a transcription via ATF2. ATF2 and c-Myc cooperate to activate the transcription of ATF3. Remarkably, not only ectopic JNK2, but also ectopic ATF2, CIP2A, c-Myc and ATF3 are sufficient to rescue...... the defective ras transformation of JNK2-deficient cells. Thus, these data identify the key signal converging point of JNK2 and ERK pathways and underline the central role of CIP2A in ras transformation.Oncogene advance online publication, 27 June 2011; doi:10.1038/onc.2011.230....

RAS Initiative - Community Outreach

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Through community and technical collaborations, workshops and symposia, and the distribution of reference reagents, the RAS Initiative seeks to increase the sharing of knowledge and resources essential to defeating cancers caused by mutant RAS genes.

Biological aspects and tumorigenic activity of the Ras proto-oncogenic family Aspectos biológicos e atividade tumorigênica da família proto-oncogênica Ras

Directory of Open Access Journals (Sweden)

Juliano André Boquett

2010-12-01

Full Text Available Proto-oncogenes play an important role in the regulation of the cellular cycle, being critical to the tumorigenesis. In this category we can find the RAS family. Due to the high transformation potential of these genes, this family is the best described and most studied one. It is formed by the H-, K- and the N-RAS genes, that codify highly related proteins expressed in several types of cells, denominated p21.These proteins act in the sign transduction from the membrane to the nucleus, as well as in the control of proliferation, differentiation and cellular death, and they are regulated by the interaction with GDP (inactive and GTP (active. These proteins show variation in only 10 - 15% of the primary structure, in the C-terminal portion denominated hyper-variant region. When in the oncogenic form, the p21 proteins remain active, providing continuous stimuli to the cellular proliferation. Among the RAS genes, K-RAS ones have been the most studied for presenting more frequent mutations and for being present in more aggressive tumors, implying the patients’ shorter survival time. Due to these facts and relative bibliography lack in the Portuguese language on this family, we presented in this work a systematized and updated review on the RAS genes. Os proto-oncogenes desempenham importante papel na regulação do ciclo celular, e são críticos à tumorigênese. Nessa categoria se encontra a família RAS, que, devido ao elevado potencial transformante dos genes que a compõem, é uma das mais bem descritas e estudadas. É formada pelos genes H-, K- e N-RAS, que codificam proteínas altamente relacionadas expressas em vários tipos de células, denominadas p21. Estas atuam na transdução de sinal da membrana ao núcleo, estão envolvidas no controle da proliferação, diferenciação e morte celular e são reguladas pela interação com GDP (inativa e GTP (ativa. As proteínas p21 diferem em apenas 10-15% da sua estrutura primária, na porção C

Regulation of p21ras activity

DEFF Research Database (Denmark)

Lowy, D R; Zhang, K; DeClue, J E

1992-01-01

The ras genes encode GTP/GDP-binding proteins that participate in mediating mitogenic signals from membrane tyrosine kinases to downstream targets. The activity of p21ras is determined by the concentration of GTP-p21ras, which is tightly regulated by a complex array of positive and negative control...... mechanisms. GAP and NF1 can negatively regulate p21ras activity by stimulating hydrolysis of GTP bound to p21ras. Other cellular factors can positively regulate p21ras by stimulating GDP/GTP exchange....

Ras-dva is a novel Pit-1- and glucocorticoid-regulated gene in the embryonic anterior pituitary gland.

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Ellestad, Laura E; Porter, Tom E

2013-01-01

Glucocorticoids play a role in functional differentiation of pituitary somatotrophs and lactotrophs during embryogenesis. Ras-dva was identified as a gene regulated by anterior neural fold protein-1/homeobox expressed in embryonic stem cells-1, a transcription factor known to be critical in pituitary development, and has an expression profile in the chicken embryonic pituitary gland that is consistent with in vivo regulation by glucocorticoids. The objective of this study was to characterize expression and regulation of ras-dva mRNA in the developing chicken anterior pituitary. Pituitary ras-dva mRNA levels increased during embryogenesis to a maximum on embryonic day (e) 18 and then decreased and remained low or undetectable after hatch. Ras-dva expression was highly enriched in the pituitary gland on e18 relative to other tissues examined. Glucocorticoid treatment of pituitary cells from mid- and late-stage embryos rapidly increased ras-dva mRNA, suggesting it may be a direct transcriptional target of glucocorticoids. A reporter construct driven by 4 kb of the chicken ras-dva 5'-flanking region, containing six putative pituitary-specific transcription factor-1 (Pit-1) binding sites and two potential glucocorticoid receptor (GR) binding sites, was highly activated in embryonic pituitary cells and up-regulated by corticosterone. Mutagenesis of the most proximal Pit-1 site decreased promoter activity in chicken e11 pituitary cells, indicating regulation of ras-dva by Pit-1. However, mutating putative GR binding sites did not substantially reduce induction of ras-dva promoter activity by corticosterone, suggesting additional DNA elements within the 5'-flanking region are responsible for glucocorticoid regulation. We have identified ras-dva as a glucocorticoid-regulated gene that is likely expressed in cells of the Pit-1 lineage within the developing anterior pituitary gland.

Beta1 integrin promotes but is not essential for metastasis of ras-myc transformed fibroblasts

DEFF Research Database (Denmark)

Brakebusch, C; Wennerberg, K; Krell, H W

1999-01-01

To investigate the role of beta1 integrin during tumor metastasis, we established a ras-myc transformed fibroblastoid cell line with a disrupted beta1 integrin gene on both alleles (GERM 11). Stable transfection of this cell line with an expression vector encoding beta1A integrin resulted in beta1A......, tumors induced by the high expressing clones 1A10 and 2F2 were markedly smaller, suggesting an inverse correlation of tumor growth and beta1 integrin expression. The metastasis potential of all three beta1 integrin-expressing GERM 11 sublines tested was significantly higher than that of the beta1......-deficient GERM 11 cells. GERM 116 tumors led in all animals to severe metastasis in lung and liver, while GERM 11 tumors induced only a few metastatic foci in the lung. Stroma of both tumors contained nidogen and high amounts of tenascin C, but only a few very low levels of fibronectin, laminin-1...

New insights into RAS biology reinvigorate interest in mathematical modeling of RAS signaling.

Science.gov (United States)

Erickson, Keesha E; Rukhlenko, Oleksii S; Posner, Richard G; Hlavacek, William S; Kholodenko, Boris N

2018-03-05

RAS is the most frequently mutated gene across human cancers, but developing inhibitors of mutant RAS has proven to be challenging. Given the difficulties of targeting RAS directly, drugs that impact the other components of pathways where mutant RAS operates may potentially be effective. However, the system-level features, including different localizations of RAS isoforms, competition between downstream effectors, and interlocking feedback and feed-forward loops, must be understood to fully grasp the opportunities and limitations of inhibiting specific targets. Mathematical modeling can help us discern the system-level impacts of these features in normal and cancer cells. New technologies enable the acquisition of experimental data that will facilitate development of realistic models of oncogenic RAS behavior. In light of the wealth of empirical data accumulated over decades of study and the advancement of experimental methods for gathering new data, modelers now have the opportunity to advance progress toward realization of targeted treatment for mutant RAS-driven cancers. Copyright © 2018 Elsevier Ltd. All rights reserved.

Oncogenic N-Ras Stimulates SRF-Mediated Transactivation via H3 Acetylation at Lysine 9

Directory of Open Access Journals (Sweden)

Sun-Ju Yi

2018-01-01

Full Text Available Signal transduction pathways regulate the gene expression by altering chromatin dynamics in response to mitogens. Ras proteins are key regulators linking extracellular stimuli to a diverse range of biological responses associated with gene regulation. In mammals, the three ras genes encode four Ras protein isoforms: H-Ras, K-Ras4A, K-Ras4B, and N-Ras. Although emerging evidence suggests that Ras isoforms differentially regulate gene expressions and are functionally nonredundant, the mechanisms underlying Ras specificity and Ras signaling effects on gene expression remain unclear. Here, we show that oncogenic N-Ras acts as the most potent regulator of SRF-, NF-κB-, and AP-1-dependent transcription. N-Ras-RGL2 axis is a distinct signaling pathway for SRF target gene expression such as Egr1 and JunB, as RGL2 Ras binding domain (RBD significantly impaired oncogenic N-Ras-induced SRE activation. By monitoring the effect of Ras isoforms upon the change of global histone modifications in oncogenic Ras-overexpressed cells, we discovered that oncogenic N-Ras elevates H3K9ac/H3K23ac levels globally in the chromatin context. Importantly, chromatin immunoprecipitation (ChIP assays revealed that H3K9ac is significantly enriched at the promoter and coding regions of Egr1 and JunB. Collectively, our findings define an undocumented role of N-Ras in modulating of H3 acetylation and in gene regulation.

BMP suppresses PTEN expression via RAS/ERK signaling.

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Beck, Stayce E; Carethers, John M

2007-08-01

Bone morphogenetic protein (BMP), a member of the transforming growth factor beta family, classically utilizes the SMAD signaling pathway for its growth suppressive effects,and loss of this signaling cascade may accelerate cell growth. In the colon cancer predisposition syndrome Juvenile Polyposis, as well as in the late progression stages of nonsyndromic colorectal cancers, SMAD4 function is typically abrogated. Here, we utilized the SMAD4-null SW480 colon cancer cell line to examine BMPs effect on a potential target gene, PTEN, and how its expression might be regulated. Initial treatment of the SMAD4-null cells with BMP resulted in mild growth suppression, but with prolonged exposure to BMP, the cells become growth stimulatory, which coincided with observed decreases in transcription and translation of PTEN, and with corresponding increases in phospho-AKT protein levels. BMP-induced PTEN suppression was mediated via the RAS/ERK pathway, as pharmacologic inhibition of RAS/ERK, or interference with protein function in the cytosol by DN-RAS prevented BMP-induced growth promotion and changes in PTEN levels, as did treatment with noggin, a BMP ligand inhibitor. Thus, BMP downregulates PTEN via RAS/ERK in a SMAD4-null environment that contributes to cell growth, and constitutes a SMAD4-independent but BMP-responsive signaling pathway.

Mutational analysis of a ras catalytic domain

DEFF Research Database (Denmark)

Willumsen, B M; Papageorge, A G; Kung, H F

1986-01-01

localization. We speculate that this latter region interacts with the putative cellular target of ras. The results suggest that transforming ras proteins require membrane localization, guanosine nucleotide binding, and an additional undefined function that may represent interaction with their target....

Processing and fatty acid acylation of RAS1 and RAS2 proteins in Saccharomyces cerevisiae

International Nuclear Information System (INIS)

Fujiyama, A.; Tamanoi, F.

1986-01-01

The authors demonstrate the pathway for the biosynthesis of RAS1 and RAS2 gene products of Saccharomyces cerevisiae leading to their localization in membranes. The primary translation products of these genes are detected in a soluble fraction. Shortly after synthesis, these precursor molecules are converted to forms that migrate slightly faster than the precursor forms on a NaDodSO 4 /polyacrylamide gel. These processed proteins are further modified by fatty acid acylation, which is detected by [ 3 H]palmitic acid labeling. The acylated derivatives are found exclusively in cell membranes, indicating the translocation of the RAS proteins from cytosol to membranes during maturation process. The attached fatty acids can be released by mild alkaline hydrolysis, suggesting that the linkage between the fatty acid and the protein is an ester bond. The site of the modification by fatty acid is presumably localized to the COOH-terminal portion of the RAS proteins. Fraction of the membranes by sucrose gradient demonstrates that a majority of the fatty-acylated RAS proteins are localized in plasma membrane

Transformation and radiosensitivity of human diploid skin fibroblasts transfected with activated ras oncogene and SV40 T-antigen.

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Su, L N; Little, J B

1992-08-01

Three normal human diploid cell strains were transfected with an activated Ha-ras oncogene (EJ ras) or SV40 T-antigen. Multiple clones were examined for morphological alterations, growth requirements, ability to grow under anchorage independent conditions, immortality and tumorigenicity in nude mice. Clones expressing SV40 T-antigen alone or in combination with ras protein p21 were significantly radioresistant as compared with their parent cells or clones transfected with the neo gene only. This radioresistant phenotype persisted in post-crisis, immortalized cell lines. Cells transfected with EJ ras alone showed no morphological alterations nor significant changes in radiosensitivity. Cell clones expressing ras and/or SV40 T-antigen showed a reduced requirement for serum supplements, an increase in aneuploidy and chromosomal aberrations, and enhanced growth in soft agar as an early cellular response to SV40 T-antigen expression. The sequential order of transfection with SV40 T-antigen and ras influenced radio-sensitivity but not the induction of morphological changes. These data suggest that expression of the SV40 T-antigen but not activated Ha-ras plays an important role in the radiosensitivity of human diploid cells. The radioresistant phenotype in SV40 T transfected cells was not related to the enhanced level of genetic instability seen in pre-crisis and newly immortalized cells, nor to the process of immortalization itself.

Concurrent mutation in exons 1 and 2 of the K-ras oncogene in colorectal cancer

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Fiorella Guadagni

2012-01-01

Full Text Available The K-ras gene is frequently mutated in colorectal cancer and has been associated with tumor initiation and progression; approximately 90% of the activating mutations are found in codons 12 and 13 of exon 1 and just under 5% in codon 61 located in exon 2. These mutations determine single aminoacidic substitutions in the GTPase pocket leading to a block of the GTP hydrolytic activity of the K-ras p21 protein, and therefore to its constitutive activation. Point mutations in sites of the K-ras gene, other than codons 12, 13 and 61, and other types of genetic alterations, may occur in a minority of cases, such as in the less frequent cases of double mutations in the K-ras gene. However, all mutations in this gene, even those which occur in non-canonical sites or double mutations, are relevant oncogenic alterations in colorectal cancer and may underlie K-ras pathway hyperactivation. In the present study, we report the case of a patient with colorectal cancer presenting a concurrent point mutation in exons 1 and 2 of the K-ras gene, a GGT to TGT substitution (Glycine to Cysteine at codon 12, and a GAC to AAC substitution (Aspartic Acid to Asparagine at codon 57. In addition, we found in the same patient’s sample a silent polymorphism at codon 11 (Ala11Ala of exon 1. (Folia Histochemica et Cytobiologica 2011; Vol. 49, No. 4, pp. 729–733

Transformation and radiosensitivity of human diploid skin fibroblasts transfected with activated RAS oncogene and SV40 T-antigen

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Su, L.-N.; Little, J.B. (Harvard School of Public Health, Boston, MA (United States))

1992-08-01

Three normal human diploid cell strains were transfected with an activated Ha-ras oncogene (EJ ras) or SV40 T-antigen. Multiple clones were examined for morphological alterations, growth requirements, ability to grow under anchorage independent conditions, immortality and tumorigenicity in nude mice. Clones expressing SV40 T-antigen alone or in combination with ras protein p21 were significantly radioresistant as compared with their parent cells or clones transfected with the neo gene only. This radioresistant phenotype persisted in post-crisis, immortalized cell lines. These data suggest that expression of the SV40 T-antigen but not activated Ha-ras plays an important role in the radiosensitivity of human diploid cells. The radioresistant phenotype in SV40 T transfected cells was not related to the enhanced level of genetic instability seen in pre-crisis and newly immortalized cells, nor to the process of immortalization itself. (author).

Transformation and radiosensitivity of human diploid skin fibroblasts transfected with activated RAS oncogene and SV40 T-antigen

International Nuclear Information System (INIS)

Su, L.-N.; Little, J.B.

1992-01-01

Three normal human diploid cell strains were transfected with an activated Ha-ras oncogene (EJ ras) or SV40 T-antigen. Multiple clones were examined for morphological alterations, growth requirements, ability to grow under anchorage independent conditions, immortality and tumorigenicity in nude mice. Clones expressing SV40 T-antigen alone or in combination with ras protein p21 were significantly radioresistant as compared with their parent cells or clones transfected with the neo gene only. This radioresistant phenotype persisted in post-crisis, immortalized cell lines. These data suggest that expression of the SV40 T-antigen but not activated Ha-ras plays an important role in the radiosensitivity of human diploid cells. The radioresistant phenotype in SV40 T transfected cells was not related to the enhanced level of genetic instability seen in pre-crisis and newly immortalized cells, nor to the process of immortalization itself. (author)

H-Ras and K-Ras Oncoproteins Induce Different Tumor Spectra When Driven by the Same Regulatory Sequences.

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Drosten, Matthias; Simón-Carrasco, Lucía; Hernández-Porras, Isabel; Lechuga, Carmen G; Blasco, María T; Jacob, Harrys K C; Fabbiano, Salvatore; Potenza, Nicoletta; Bustelo, Xosé R; Guerra, Carmen; Barbacid, Mariano

2017-02-01

Genetic studies in mice have provided evidence that H-Ras and K-Ras proteins are bioequivalent. However, human tumors display marked differences in the association of RAS oncogenes with tumor type. Thus, to further assess the bioequivalence of oncogenic H-Ras and K-Ras, we replaced the coding region of the murine K-Ras locus with H-Ras G12V oncogene sequences. Germline expression of H-Ras G12V or K-Ras G12V from the K-Ras locus resulted in embryonic lethality. However, expression of these genes in adult mice led to different tumor phenotypes. Whereas H-Ras G12V elicited papillomas and hematopoietic tumors, K-Ras G12V induced lung tumors and gastric lesions. Pulmonary expression of H-Ras G12V created a senescence-like state caused by excessive MAPK signaling. Likewise, H-Ras G12V but not K-Ras G12V induced senescence in mouse embryonic fibroblasts. Label-free quantitative analysis revealed that minor differences in H-Ras G12V expression levels led to drastically different biological outputs, suggesting that subtle differences in MAPK signaling confer nonequivalent functions that influence tumor spectra induced by RAS oncoproteins. Cancer Res; 77(3); 707-18. ©2016 AACR. ©2016 American Association for Cancer Research.

Ras mutations are rare in solitary cold and toxic thyroid nodules.

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Krohn, K; Reske, A; Ackermann, F; Müller, A; Paschke, R

2001-08-01

Activation of ras proto-oncogenes as a result of point mutations is detectable in a significant percentage of most types of tumour. Similar to neoplasms of other organs, mutations of all three ras genes can be found in thyroid tumours. H-, K- and N-ras mutations have been detected in up to 20% of follicular adenomas and adenomatous nodules which were not functionally characterized. This raises the question as to whether ras mutations are specific for hypofunctional nodules and TSH receptor mutations for hyperfunctioning nodules. To investigate ras and TSH receptor mutations with respect to functional differentiation we studied 41 scintigraphically cold nodules and 47 toxic thyroid nodules. To address the likelihood of a somatic mutation we also studied the clonal origin of these tumours. Genomic DNA was extracted from nodular and surrounding tissue. Mutational hot spots in exons 1 and 2 of the H- and K-ras gene were PCR amplified and sequenced using big dye terminator chemistry. Denaturing gradient gel electrophoresis (DGGE) was used to verify sequencing results for the H-ras gene and to analyse the N-ras gene because its greater sensitivity in detecting somatic mutations. Clonality of nodular thyroid tissue was evaluated using X-Chromosome inactivation based on PCR amplification of the human androgen receptor locus. Monoclonal origin was detectable in 14 of 23 informative samples from cold thyroid nodules. In toxic thyroid nodules the frequency of clonal tissue was 20 in 30 informative cases. Only one point mutation could be found in the N-ras gene codon 61 (Gly to Arg) in a cold adenomatous nodule which was monoclonal. In toxic thyroid nodules no ras mutation was detectable. Our study suggests that ras mutations are rare in solitary cold and toxic thyroid nodules and that the frequent monoclonal origin of these tumours implies somatic mutations in genes other than H-, K- and N-ras.

Transcriptional Profile of Ki-Ras-Induced Transformation of Thyroid Cells

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Visconti, Roberta; Federico, Antonella; Coppola, Valeria

2007-01-01

Abstract In the last years, an increasing number of experiments has provided compelling evidence for a casual role of Ras protein mutations, resulting in their constitutive activation, in thyroid carcinogenesis. However, despite the clear involvement of Ras proteins in thyroid carcinogenesis, the...

H-ras oncogene-transformed human bronchial epithelial cells (TBE-1) secrete a single metalloprotease capable of degrading basement membrane collagen

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Collier, I.E.; Wilhelm, S.M.; Eisen, A.Z.

1988-01-01

H-ras transformed human bronchial epithelial cells (TBE-1) secrete a single major extracellular matrix metalloprotease which is not found in the normal parental cells. The enzyme is secreted in a latent form which can be activated to catalyze the cleavage of the basement membrane macromolecule type IV collagen. The substrates in their order of preference are: gelatin, type IV collagen, type V collagen, fibronectin, and type VII collagen; but the enzyme does not cleave the interstitial collagens or laminin. This protease is identical to gelatinase isolated from normal human skin explants, normal human skin fibroblasts, and SV40-transformed human lung fibroblasts. Based on this ability to initiate the degradation of type IV collagen in a pepsin-resistant portion of the molecule, it will be referred to as type IV collagenase. This enzyme is most likely the human analog of type IV collagenase detected in several rodent tumors. Type IV collagenase consists of three domains. Type IV collagenase represents the third member of a newly recognized gene family coding for secreted extracellular matrix metalloproteases, which includes interstitial fibroblast collagenase and stromelysin

Control of Saccharomyces cerevisiae catalase T gene (CTT1) expression by nutrient supply via the RAS-cyclic AMP pathway.

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Bissinger, P H; Wieser, R; Hamilton, B; Ruis, H

1989-03-01

In Saccharomyces cerevisiae, lack of nutrients triggers a pleiotropic response characterized by accumulation of storage carbohydrates, early G1 arrest, and sporulation of a/alpha diploids. This response is thought to be mediated by RAS proteins, adenylate cyclase, and cyclic AMP (cAMP)-dependent protein kinases. This study shows that expression of the S. cerevisiae gene coding for a cytoplasmic catalase T (CTT1) is controlled by this pathway: it is regulated by the availability of nutrients. Lack of a nitrogen, sulfur, or phosphorus source causes a high-level expression of the gene. Studies with strains with mutations in the RAS-cAMP pathway and supplementation of a rca1 mutant with cAMP show that CTT1 expression is under negative control by a cAMP-dependent protein kinase and that nutrient control of CTT1 gene expression is mediated by this pathway. Strains containing a CTT1-Escherichia coli lacZ fusion gene have been used to isolate mutants with mutations in the pathway. Mutants characterized in this investigation fall into five complementation groups. Both cdc25 and ras2 alleles were identified among these mutants.

Identification of Differentially Expressed K-Ras Transcript Variants in Patients With Leiomyoma.

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Zolfaghari, Nooshin; Shahbazi, Shirin; Torfeh, Mahnaz; Khorasani, Maryam; Hashemi, Mehrdad; Mahdian, Reza

2017-10-01

Molecular studies have demonstrated a wide range of gene expression variations in uterine leiomyoma. The rat sarcoma virus/rapidly accelerated fibrosarcoma/mitogen-activated protein kinase (RAS/RAF/MAPK) is the crucial cellular pathway in transmitting external signals into nucleus. Deregulation of this pathway contributes to excessive cell proliferation and tumorigenesis. The present study aims to investigate the expression profile of the K-Ras transcripts in tissue samples from patients with leiomyoma. The patients were leiomyoma cases who had no mutation in mediator complex subunit 12 ( MED12) gene. A quantitative approach has been applied to determine the difference in the expression of the 2 main K-Ras messenger RNA (mRNA) variants. The comparison between gene expression levels in leiomyoma and normal myometrium group was performed using relative expression software tool. The expression of K-Ras4B gene was upregulated in leiomyoma group ( P = .016), suggesting the involvement of K-Ras4B in the disease pathogenesis. Pairwise comparison of the K-Ras4B expression between each leiomyoma tissue and its matched adjacent normal myometrium revealed gene upregulation in 68% of the cases. The expression of K-Ras4A mRNA was relatively upregulated in leiomyoma group ( P = .030). In addition, the mean expression of K-Ras4A gene in leiomyoma tissues relative to normal samples was 4.475 (95% confidence interval: 0.10-20.42; standard error: 0.53-12.67). In total, 58% of the cases showed more than 2-fold increase in K-Ras4A gene expression. Our results demonstrated increased expression of both K-Ras mRNA splicing variants in leiomyoma tissue. However, the ultimate result of KRAS expression on leiomyoma development depends on the overall KRAS isoform balance and, consequently, on activated signaling pathways.

Opposite effects of Ha-Ras and Ki-Ras on radiation-induced apoptosis via differential activation of PI3K/Akt and Rac/p38 mitogen-activated protein kinase signaling

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Choi, J.-A.; Kang, C.-M.; Lee, Y.-S.; Lee, S.-J.; Bae, S.-W.; Cho, C.-K.

2003-01-01

It has been well known that Ras signaling is involved in various cellular processes, including proliferation, differentiation, and apoptosis. However, distinct cellular functions of Ras isozymes are not fully understood. Here we show the opposing roles of Ha-Ras and Ki-Ras genes in the modulation of cell sensitivity to ionizing radiation. Overexpression of active isoform of Ha-Ras (12V-Ha- Ras) in Rat2 cells increases resistance to the ionizing radiation. Constitutive activation of phosphoinositide-3-kinase (PI3K) and Akt is detected specifically in 12V-Ha-Ras-overexpressing cells. The specific PI3K inhibitor LY294002 inhibits PI3K/Akt signaling and potentiates the radiation-induced apoptosis, suggesting that activation of PI3K/Akt signaling pathway is involved in the increased radio-resistance in cells overexpressing 12V-Ha-Ras. Overexpression of activated Ki-Ras (12V-Ki-Ras), on the other hand, markedly increases radiation sensitivity. The p38 mitogen-activated protein (MAP) kinase activity is selectively enhanced by ionizing radiation in cells overexpressing 12V-Ki-Ras. The specific p38 MAP kinase inhibitor, PD169316, or dominant-negative p38 MAP kinase decreases radiation-induced cell death. We further show that the mechanism that underlies potentiation of cell death in cells overexpressing 12V-Ki-Ras involves Bax translocation to the mitochondrial membrane. Elevated Bax translocation following ionizing irradiation in 12V-Ki-Ras-overexpressing cells is completely inhibited by PD169316 or dominant-negative p38 MAP kinase. In addition, introduction of cells with RacN17, a dominant negative mutant of Rac, resulted in a marked inhibition of radiation-induced Bax translocation and apoptotic cell death as well as p38 MAP kinase activation. Taken together, these findings explain the opposite effects of Ha-Ras and Ki-Ras on modulation of radio-sensitivity, and suggest that differential activation of PI3K/Akt and Rac/p38 MAP kinase signaling by Ha-Ras and Ki-Ras may

Which downstream signal transduction pathway(s) of H-ras are necessary for the cellular response(s) to ionizing radiation? (Results of an astro research fellowship year)

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Rudoltz, Marc S.; Muschel, Ruth J.; McKenna, W. Gillies

1996-01-01

Purpose/Background: The H-ras oncogene encodes a protein which is an essential component of multiple downstream effector pathways required for induction of proliferation and differentiation. Ras plays a role in the control some of these signal transduction pathways, such as the MAP kinase pathway which controls gene expression and the Rac-Rho pathway which controls cell morphology. Previous work from our laboratory has associated H-ras expression with radiation resistance, a prolonged delay in G2 following exposure to ionizing radiation, and suppression of radiation-induced apoptosis. In addition, H-ras cooperates with myc in transformation. Recent work by White et al. (Cell 80:533-541, 1995) and Joneson et al. (Science 271: 810-812, 1996) describes three mutations in H-ras which were engineered to eliminate different downstream signal transduction pathways of H-ras. T35S contains a serine in place of threonine at amino acid 35 and is defective for ras-induced cytoskeletal changes and initiation of DNA synthesis. E37G contains a glutamic acid in place of glycine at amino acid 37 which eliminates interaction of H-ras with a GDP/GTP exchange factor. C40 contains a substitution of cysteine for tyrosine at amino acid 40 and is defective for H-ras induction of the MAP kinase pathway. We propose that by expressing these mutant H-ras proteins in immortalized cells the downstream pathways of H-ras which regulate the cellular response(s) to ionizing radiation may be determined. Materials and Methods: pHP-5 plasmids encoding these H-ras mutant genes (see White et al.) were transfected by calcium phosphate precipitation into MR4 cells, rat embryo fibroblasts immortalized by expression of v-myc. In this vector, the cDNA for H-ras is placed under the control of a CMV constitutive promoter, and selection is provided by hygromycin. The transfections performed were as follows: V12Ras (no mutation), T35S, E37G, C40, T35S + E37G, and T35S + C40. Twenty four hours after transfection

Depletion of Pokemon gene inhibits hepatocellular carcinoma cell growth through inhibition of H-ras.

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Zhang, Quan-Le; Tian, De-An; Xu, Xiang-Jiang

2011-01-01

Pokemon is a transcription repressor which plays a critical role in cell transformation and malignancy. However, little is known about its effect on the development and progression of hepatocellular carcinoma (HCC). The aim of this study was to investigate the expression of Pokemon in human HCC tissues and the biological behavior of Pokemon in HCC cells in which it is overexpressed. We also explored the expression of potential downstream cofactors of Pokemon. Reverse transcription polymerase chain reaction and Western blot analysis were used to investigate the expression of Pokemon in tissues of 30 HCC patients. We then examined cell proliferation or apoptosis and β-catenin or H-ras expression in Pokemon-depleted HepG(2) cells using DNA vector-based RNA interference technology. Pokemon was markedly expressed in 22/30 (73.3%) HCC tissues, with expression levels higher than in adjacent normal liver tissues (p Pokemon inhibited proliferation of HepG(2) or induced apoptosis. Also, H-ras expression decreased to a large extent. Pokemon exerts its oncogenic activity in the development of HCC by promoting cancer cell growth and reducing apoptosis, and the effect may be mediated by H-ras. Copyright © 2011 S. Karger AG, Basel.

Coexistence of K-ras mutations and HPV infection in colon cancer

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Tezol Ayda

2006-05-01

Full Text Available Abstract Background Activation of the ras genes or association with human papillomavirus infection have been extensively studied in colorectal cancer. However, the correlation between K-ras mutations and HPV in colorectal cancer has not been investigated yet. In this study we aimed to investigate the presence of K-ras mutations and their correlation with HPV infection in colon cancer. Methods K-ras mutations were analyzed by a mutagenic PCR assay and digestion with specific restriction enzymes to distinguish the wild-type and mutant codons. HPV infection was analyzed by PCR amplification and hybridization with specific probes by Southern blotting. Stattistical analyses were performed by the chi-square and Fisher's exact tests Results HPV gene fragments were detected in 43 tumors and 17 normal tissue samples. HPV 18 was the prevalent type in the tumor tissue. A mutation at codon 12 of the K-ras gene was present in 31 patients. 56% of the HPV-positive tumors also harbored a K-ras mutation. Codon 13 mutations were not observed. These data indicate that infection with high risk HPV types and mutational activation of the K-ras gene are frequent events in colorectal carcinogenesis. Conclusion Our findings suggest that mutational activation of the K-ras gene is a common event in colon carcinogenesis and that HPV infection may represent an important factor in the development of the premalignant lesions leading to the neoplastic phenotype.

Gene expression profiling and candidate gene resequencing identifies pathways and mutations important for malignant transformation caused by leukemogenic fusion genes.

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Novak, Rachel L; Harper, David P; Caudell, David; Slape, Christopher; Beachy, Sarah H; Aplan, Peter D

2012-12-01

NUP98-HOXD13 (NHD13) and CALM-AF10 (CA10) are oncogenic fusion proteins produced by recurrent chromosomal translocations in patients with acute myeloid leukemia (AML). Transgenic mice that express these fusions develop AML with a long latency and incomplete penetrance, suggesting that collaborating genetic events are required for leukemic transformation. We employed genetic techniques to identify both preleukemic abnormalities in healthy transgenic mice as well as collaborating events leading to leukemic transformation. Candidate gene resequencing revealed that 6 of 27 (22%) CA10 AMLs spontaneously acquired a Ras pathway mutation and 8 of 27 (30%) acquired an Flt3 mutation. Two CA10 AMLs acquired an Flt3 internal-tandem duplication, demonstrating that these mutations can be acquired in murine as well as human AML. Gene expression profiles revealed a marked upregulation of Hox genes, particularly Hoxa5, Hoxa9, and Hoxa10 in both NHD13 and CA10 mice. Furthermore, mir196b, which is embedded within the Hoxa locus, was overexpressed in both CA10 and NHD13 samples. In contrast, the Hox cofactors Meis1 and Pbx3 were differentially expressed; Meis1 was increased in CA10 AMLs but not NHD13 AMLs, whereas Pbx3 was consistently increased in NHD13 but not CA10 AMLs. Silencing of Pbx3 in NHD13 cells led to decreased proliferation, increased apoptosis, and decreased colony formation in vitro, suggesting a previously unexpected role for Pbx3 in leukemic transformation. Published by Elsevier Inc.

RAS signaling and anti-RAS therapy: lessons learned from genetically engineered mouse models, human cancer cells, and patient-related studies.

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Fang, Bingliang

2016-01-01

Activating mutations of oncogenic RAS genes are frequently detected in human cancers. The studies in genetically engineered mouse models (GEMMs) reveal that Kras-activating mutations predispose mice to early onset tumors in the lung, pancreas, and gastrointestinal tract. Nevertheless, most of these tumors do not have metastatic phenotypes. Metastasis occurs when tumors acquire additional genetic changes in other cancer driver genes. Studies on clinical specimens also demonstrated that KRAS mutations are present in premalignant tissues and that most of KRAS mutant human cancers have co-mutations in other cancer driver genes, including TP53, STK11, CDKN2A, and KMT2C in lung cancer; APC, TP53, and PIK3CA in colon cancer; and TP53, CDKN2A, SMAD4, and MED12 in pancreatic cancer. Extensive efforts have been devoted to develop therapeutic agents that target enzymes involved in RAS posttranslational modifications, that inhibit downstream effectors of RAS signaling pathways, and that kill RAS mutant cancer cells through synthetic lethality. Recent clinical studies have revealed that sorafenib, a pan-RAF and VEGFR inhibitor, has impressive benefits for KRAS mutant lung cancer patients. Combination therapy of MEK inhibitors with either docetaxel, AKT inhibitors, or PI3K inhibitors also led to improved clinical responses in some KRAS mutant cancer patients. This review discusses knowledge gained from GEMMs, human cancer cells, and patient-related studies on RAS-mediated tumorigenesis and anti-RAS therapy. Emerging evidence demonstrates that RAS mutant cancers are heterogeneous because of the presence of different mutant alleles and/or co-mutations in other cancer driver genes. Effective subclassifications of RAS mutant cancers may be necessary to improve patients' outcomes through personalized precision medicine. © The Author 2015. Published by ABBS Editorial Office in association with Oxford University Press on behalf of the Institute of Biochemistry and Cell Biology

Synthetic medical studies on atomic bomb survivors exposed in short distances, 15. Detection of transforming gene(s)

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Kamada, Nanao; Tanaka, Kimio; Kontani, Nobuko; Yokoro, Kenjiro; Takimoto, Yasuo; Kuramoto, Atsushi; Munaka, Masaki; Kurihara, Minoru; Hattori, Takao

1988-03-01

In an effort to search for biological significance of chromosome aberration observed in bone marrow cells and peripheral lymphocytes, the presence of transforming genes in the DNA of bone marrow cells was examined in four healthy A-bomb survivors (Group I), three with preleukemia (Group II), and nine with leukemia (Group III). In Group I exposed at 300 - 500 m from the hypocenter, estimated radiation doses ranged from 565 to 667 cGy; and randomly abnormal karyotypes ranged from 30.7 % to 48.3 %. In Group II exposed at 800 m, in which estimated radiation doses were 300 - 600 cGy, one survivor had a complicated karyotype abnormality; and in the two others, abnormal clones were partly observed. Group III, which was exposed at 800 - 2,000 m and had estimated doses of 20 - 200 cGy, consisted of acute lymphoid leukemia (one), acute myeloid leukemia (five), and chronic myeloid leukemia (three). The patient with acute lymphoid leukemia had a complicated karyotype abnormality. N-ras genes were observed not only in seven acute or chronic leukemic patients but also in three healthy survivors. This may have important implications for the mechanism of leukemic transformation. (Namekawa, K.).

Obesity Suppresses Cell-Competition-Mediated Apical Elimination of RasV12-Transformed Cells from Epithelial Tissues.

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Sasaki, Ayana; Nagatake, Takahiro; Egami, Riku; Gu, Guoqiang; Takigawa, Ichigaku; Ikeda, Wataru; Nakatani, Tomoya; Kunisawa, Jun; Fujita, Yasuyuki

2018-04-24

Recent studies have revealed that newly emerging transformed cells are often eliminated from epithelial tissues via cell competition with the surrounding normal epithelial cells. This cancer preventive phenomenon is termed epithelial defense against cancer (EDAC). However, it remains largely unknown whether and how EDAC is diminished during carcinogenesis. In this study, using a cell competition mouse model, we show that high-fat diet (HFD) feeding substantially attenuates the frequency of apical elimination of RasV12-transformed cells from intestinal and pancreatic epithelia. This process involves both lipid metabolism and chronic inflammation. Furthermore, aspirin treatment significantly facilitates eradication of transformed cells from the epithelial tissues in HFD-fed mice. Thus, our work demonstrates that obesity can profoundly influence competitive interaction between normal and transformed cells, providing insights into cell competition and cancer preventive medicine. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.

Stat1 phosphorylation determines Ras oncogenicity by regulating p27 kip1.

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Shuo Wang

Full Text Available Inactivation of p27 Kip1 is implicated in tumorigenesis and has both prognostic and treatment-predictive values for many types of human cancer. The transcription factor Stat1 is essential for innate immunity and tumor immunosurveillance through its ability to act downstream of interferons. Herein, we demonstrate that Stat1 functions as a suppressor of Ras transformation independently of an interferon response. Inhibition of Ras transformation and tumorigenesis requires the phosphorylation of Stat1 at tyrosine 701 but is independent of Stat1 phosphorylation at serine 727. Stat1 induces p27 Kip1 expression in Ras transformed cells at the transcriptional level through mechanisms that depend on Stat1 phosphorylation at tyrosine 701 and activation of Stat3. The tumor suppressor properties of Stat1 in Ras transformation are reversed by the inactivation of p27 Kip1. Our work reveals a novel functional link between Stat1 and p27 Kip1, which act in coordination to suppress the oncogenic properties of activated Ras. It also supports the notion that evaluation of Stat1 phosphorylation in human tumors may prove a reliable prognostic factor for patient outcome and a predictor of treatment response to anticancer therapies aimed at activating Stat1 and its downstream effectors.

Rasputin, the Drosophila homologue of the RasGAP SH3 binding protein, functions in ras- and Rho-mediated signaling.

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Pazman, C; Mayes, C A; Fanto, M; Haynes, S R; Mlodzik, M

2000-04-01

The small GTPase Ras plays an important role in many cellular signaling processes. Ras activity is negatively regulated by GTPase activating proteins (GAPs). It has been proposed that RasGAP may also function as an effector of Ras activity. We have identified and characterized the Drosophila homologue of the RasGAP-binding protein G3BP encoded by rasputin (rin). rin mutants are viable and display defects in photoreceptor recruitment and ommatidial polarity in the eye. Mutations in rin/G3BP genetically interact with components of the Ras signaling pathway that function at the level of Ras and above, but not with Raf/MAPK pathway components. These interactions suggest that Rin is required as an effector in Ras signaling during eye development, supporting an effector role for RasGAP. The ommatidial polarity phenotypes of rin are similar to those of RhoA and the polarity genes, e.g. fz and dsh. Although rin/G3BP interacts genetically with RhoA, affecting both photoreceptor differentiation and polarity, it does not interact with the gain-of-function genotypes of fz and dsh. These data suggest that Rin is not a general component of polarity generation, but serves a function specific to Ras and RhoA signaling pathways.

Activated H-Ras regulates hematopoietic cell survival by modulating Survivin

International Nuclear Information System (INIS)

Fukuda, Seiji; Pelus, Louis M.

2004-01-01

Survivin expression and Ras activation are regulated by hematopoietic growth factors. We investigated whether activated Ras could circumvent growth factor-regulated Survivin expression and if a Ras/Survivin axis mediates growth factor independent survival and proliferation in hematopoietic cells. Survivin expression is up-regulated by IL-3 in Ba/F3 and CD34 + cells and inhibited by the Ras inhibitor, farnesylthiosalicylic acid. Over-expression of constitutively activated H-Ras (CA-Ras) in Ba/F3 cells blocked down-modulation of Survivin expression, G 0 /G 1 arrest, and apoptosis induced by IL-3 withdrawal, while dominant-negative (DN) H-Ras down-regulated Survivin. Survivin disruption by DN T34A Survivin blocked CA-Ras-induced IL-3-independent cell survival and proliferation; however, it did not affect CA-Ras-mediated enhancement of S-phase, indicating that the anti-apoptotic activity of CA-Ras is Survivin dependent while its S-phase enhancing effect is not. These results indicate that CA-Ras modulates Survivin expression independent of hematopoietic growth factors and that a CA-Ras/Survivin axis regulates survival and proliferation of transformed hematopoietic cells

Aberrantly methylated genes in human papillary thyroid cancer and their association with BRAF/RAS mutation.

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Yasuko eKikuchi

2013-12-01

Full Text Available Cancer arises through accumulation of epigenetic and genetic alteration. Aberrant promoter methylation is a common epigenetic mechanism of gene silencing in cancer cells. We here performed genome-wide analysis of DNA methylation of promoter regions by Infinium HumanMethylation27 BeadChip, using 14 clinical papillary thyroid cancer samples and 10 normal thyroid samples. Among the 14 papillary cancer cases, 11 showed frequent aberrant methylation, but the other three cases showed no aberrant methylation at all. Distribution of the hypermethylation among cancer samples was non-random, which implied existence of a subset of preferentially methylated papillary thyroid cancer. Among 25 frequently methylated genes, methylation status of six genes (HIST1H3J, POU4F2, SHOX2, PHKG2, TLX3, HOXA7 was validated quantitatively by pyrosequencing. Epigenetic silencing of these genes in methylated papillary thyroid cancer cell lines was confirmed by gene re-expression following treatment with 5-aza-2'-deoxycytidine and trichostatin A, and detected by real-time RT-PCR. Methylation of these six genes was validated by analysis of additional 20 papillary thyroid cancer and 10 normal samples. Among the 34 cancer samples in total, 26 cancer samples with preferential methylation were significantly associated with mutation of BRAF/RAS oncogene (P=0.04, Fisher’s exact test. Thus we identified new genes with frequent epigenetic hypermethylation in papillary thyroid cancer, two subsets of either preferentially methylated or hardly methylated papillary thyroid cancer, with a concomitant occurrence of oncogene mutation and gene methylation. These hypermethylated genes may constitute potential biomarkers for papillary thyroid cancer.

Epidermal Growth Factor Receptor and K-RAS status in two cohorts of squamous cell carcinomas

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Van Laethem Jean-Luc

2010-05-01

Full Text Available Abstract Background With the availability of effective anti-EGFR therapies for various solid malignancies, such as non-cell small lung cancer, colorectal cancer and squamous cell carcinoma of the head and neck, the knowledge of EGFR and K-RAS status becomes clinically important. The aim of this study was to analyse EGFR expression, EGFR gene copy number and EGFR and K-RAS mutations in two cohorts of squamous cell carcinomas, specifically anal canal and tonsil carcinomas. Methods Formalin fixed, paraffin-embedded tissues from anal and tonsil carcinoma were used. EGFR protein expression and EGFR gene copy number were analysed by means of immunohistochemistry and fluorescence in situ hybridisation. The somatic status of the EGFR gene was investigated by PCR using primers specific for exons 18 through 21. For the K-RAS gene, PCR was performed using exon 2 specific primers. Results EGFR immunoreactivity was present in 36/43 (83.7% of anal canal and in 20/24 (83.3% of tonsil squamous cell carcinomas. EGFR amplification was absent in anal canal tumours (0/23, but could be identified in 4 of 24 tonsil tumours. From 38 anal canal specimens, 26 specimens were successfully analysed for exon 18, 30 for exon 19, 34 for exon 20 and 30 for exon 21. No EGFR mutations were found in the investigated samples. Thirty samples were sequenced for K-RAS exon 2 and no mutation was identified. From 24 tonsil specimens, 22 were successfully analysed for exon 18 and all 24 specimens for exon 19, 20 and 21. No EGFR mutations were found. Twenty-two samples were sequenced for K-RAS exon 2 and one mutation c.53C > A was identified. Conclusion EGFR mutations were absent from squamous cell carcinoma of the anus and tonsils, but EGFR protein expression was detected in the majority of the cases. EGFR amplification was seen in tonsil but not in anal canal carcinomas. In our investigated panel, only one mutation in the K-RAS gene of a tonsil squamous cell carcinoma was identified

Epidermal Growth Factor Receptor and K-RAS status in two cohorts of squamous cell carcinomas

International Nuclear Information System (INIS)

Van Damme, Nancy; Pauwels, Patrick; Peeters, Marc; Deron, Philippe; Van Roy, Nadine; Demetter, Pieter; Bols, Alain; Dorpe, Jo Van; Baert, Filip; Van Laethem, Jean-Luc; Speleman, Franki

2010-01-01

With the availability of effective anti-EGFR therapies for various solid malignancies, such as non-cell small lung cancer, colorectal cancer and squamous cell carcinoma of the head and neck, the knowledge of EGFR and K-RAS status becomes clinically important. The aim of this study was to analyse EGFR expression, EGFR gene copy number and EGFR and K-RAS mutations in two cohorts of squamous cell carcinomas, specifically anal canal and tonsil carcinomas. Formalin fixed, paraffin-embedded tissues from anal and tonsil carcinoma were used. EGFR protein expression and EGFR gene copy number were analysed by means of immunohistochemistry and fluorescence in situ hybridisation. The somatic status of the EGFR gene was investigated by PCR using primers specific for exons 18 through 21. For the K-RAS gene, PCR was performed using exon 2 specific primers. EGFR immunoreactivity was present in 36/43 (83.7%) of anal canal and in 20/24 (83.3%) of tonsil squamous cell carcinomas. EGFR amplification was absent in anal canal tumours (0/23), but could be identified in 4 of 24 tonsil tumours. From 38 anal canal specimens, 26 specimens were successfully analysed for exon 18, 30 for exon 19, 34 for exon 20 and 30 for exon 21. No EGFR mutations were found in the investigated samples. Thirty samples were sequenced for K-RAS exon 2 and no mutation was identified. From 24 tonsil specimens, 22 were successfully analysed for exon 18 and all 24 specimens for exon 19, 20 and 21. No EGFR mutations were found. Twenty-two samples were sequenced for K-RAS exon 2 and one mutation c.53C > A was identified. EGFR mutations were absent from squamous cell carcinoma of the anus and tonsils, but EGFR protein expression was detected in the majority of the cases. EGFR amplification was seen in tonsil but not in anal canal carcinomas. In our investigated panel, only one mutation in the K-RAS gene of a tonsil squamous cell carcinoma was identified. This indicates that EGFR and K-RAS mutation analysis is not

Effects of mutant human Ki-rasG12C gene dosage on murine lung tumorigenesis and signaling to its downstream effectors

International Nuclear Information System (INIS)

Dance-Barnes, Stephanie T.; Kock, Nancy D.; Floyd, Heather S.; Moore, Joseph E.; Mosley, Libyadda J.; D'Agostino, Ralph B.; Pettenati, Mark J.; Miller, Mark Steven

2008-01-01

Studies in cell culture have suggested that the level of RAS expression can influence the transformation of cells and the signaling pathways stimulated by mutant RAS expression. However, the levels of RAS expression in vivo appear to be subject to feedback regulation, limiting the total amount of RAS protein that can be expressed. We utilized a bitransgenic mouse lung tumor model that expressed the human Ki-ras G12C allele in a tetracycline-inducible, lung-specific manner. Treatment for 12 months with 500 μg/ml of doxycycline (DOX) allowed for maximal expression of the human Ki-ras G12C allele in the lung, and resulted in the development of focal hyperplasia and adenomas. We determined if different levels of mutant RAS expression would influence the phenotype of the lung lesions. Treatment with 25, 100 and 500 μg/ml of DOX resulted in dose-dependent increases in transgene expression and tumor multiplicity. Microscopic analysis of the lungs of mice treated with the 25 μg/ml dose of DOX revealed infrequent foci of hyperplasia, whereas mice treated with the 100 and 500 μg/ml doses exhibited numerous hyperplastic foci and also adenomas. Immunohistochemical and RNA analysis of the downstream effector pathways demonstrated that different levels of mutant RAS transgene expression resulted in differences in the expression and/or phosphorylation of specific signaling molecules. Our results suggest that the molecular alterations driving tumorigenesis may differ at different levels of mutant Ki-ras G12C expression, and this should be taken into consideration when inducible transgene systems are utilized to promote tumorigenesis in mouse models

k-RAS mutations in non-small cell lung cancer patients treated with TKIs among smokers and non-smokers: a meta-analysis

Directory of Open Access Journals (Sweden)

Ai-Gui Jiang

2016-06-01

Full Text Available Aim of the study : Recent studies have suggested that k-RAS mutations are related to the response to epidermal growth factor receptor (EGFR tyrosine-kinase inhibitions (TKIs in advanced non-small cell lung cancer (NSCLC treatment. The aim of this meta-analysis was to assess the relationship between smoking history and k-RAS mutations in NSCLC treated with TKIs. Material and methods : We searched MEDLINE and Web of Science up to 15 March 2014. The pooled relative risk (RR was estimated by using fixed effect model or random effect model, according to heterogeneity between studies. We also carried out power analyses. Results : We identified 12 studies with 1193 patients, including 196 patients (16.4% with k-RAS mutations. The pooled k-RAS mutations incidence was 22.8% (174/764 in patients with smoke expose vs. 5.4% (23/429 in those with no smoke exposure. The pooled RR was 2.991 (95% CI: 1.884–4.746; Z = 4.65, p = 0.000. No publication bias was found (Begg’s test: z = 1.09, p = 0.274 and Egger’s test: t = 1.38, p = 0.201. In subgroup analyses, the pooled RR was 3.336 (95% CI: 1.925–5.779; Z = 4.30, p = 0.000 in the Caucasian subgroup, while in the Asian subgroup the pooled RR was 2.093 (95% CI: 0.909–4.822; Z = 1.73, p = 0.083, but the sample size was underpowered (0.465. Conclusions : The current meta-analysis found that smoking was related to increased incidence of k-RAS mutations in non-small cell lung cancer treated with TKIs. This may be further evidence that smoking will lead to a worse prognosis in NSCLC patients treated with TKIs.

Inactivation of the DNA repair gene O6-methylguanine-DNA methyltransferase by promoter hypermethylation is associated with G to A mutations in K-ras in colorectal tumorigenesis.

Science.gov (United States)

Esteller, M; Toyota, M; Sanchez-Cespedes, M; Capella, G; Peinado, M A; Watkins, D N; Issa, J P; Sidransky, D; Baylin, S B; Herman, J G

2000-05-01

O6-methylguanine DNA methyltransferase (MGMT) is a DNA repair protein that removes mutagenic and cytotoxic adducts from the O6 position of guanine. O6-methylguanine mispairs with thymine during replication, and if the adduct is not removed, this results in conversion from a guanine-cytosine pair to an adenine-thymine pair. In vitro assays show that MGMT expression avoids G to A mutations and MGMT transgenic mice are protected against G to A transitions at ras genes. We have recently demonstrated that the MGMT gene is silenced by promoter methylation in many human tumors, including colorectal carcinomas. To study the relevance of defective MGMT function by aberrant methylation in relation to the presence of K-ras mutations, we studied 244 colorectal tumor samples for MGMT promoter hypermethylation and K-ras mutational status. Our results show a clear association between the inactivation of MGMT by promoter hypermethylation and the appearance of G to A mutations at K-ras: 71% (36 of 51) of the tumors displaying this particular type of mutation had abnormal MGMT methylation, whereas only 32% (12 of 37) of those with other K-ras mutations not involving G to A transitions and 35% (55 of 156) of the tumors without K-ras mutations demonstrated MGMT methylation (P = 0.002). In addition, MGMT loss associated with hypermethylation was observed in the small adenomas, including those that do not yet contain K-ras mutations. Hypermethylation of other genes such as p16INK4a and p14ARF was not associated with either MGMT hypermethylation or K-ras mutation. Our data suggest that epigenetic silencing of MGMT by promoter hypermethylation may lead to a particular genetic change in human cancer, specifically G to A transitions in the K-ras oncogene.

The ras1 function of Schizosaccharomyces pombe mediates pheromone-induced transcription

DEFF Research Database (Denmark)

Nielsen, O; Davey, William John; Egel, R

1992-01-01

Loss of ras1+ function renders fission yeast cells unable to undergo morphological changes in response to mating pheromones, whereas cells carrying activated mutations in ras1 are hyper-responsive. This has led to the suggestion that the ras1 gene product plays a role in mating pheromone signal...

Sequence analysis of the Ras-MAPK pathway genes SOS1, EGFR & GRB2 in silver foxes (Vulpes vulpes): candidate genes for hereditary hyperplastic gingivitis.

Science.gov (United States)

Clark, Jo-Anna B J; Tully, Sara J; Dawn Marshall, H

2014-12-01

Hereditary hyperplastic gingivitis (HHG) is an autosomal recessive disease that presents with progressive gingival proliferation in farmed silver foxes. Hereditary gingival fibromatosis (HGF) is an analogous condition in humans that is genetically heterogeneous with several known autosomal dominant loci. For one locus the causative mutation is in the Son of sevenless homologue 1 (SOS1) gene. For the remaining loci, the molecular mechanisms are unknown but Ras pathway involvement is suspected. Here we compare sequences for the SOS1 gene, and two adjacent genes in the Ras pathway, growth receptor bound protein 2 (GRB2) and epidermal growth factor receptor (EGFR), between HHG-affected and unaffected foxes. We conclude that the known HGF causative mutation does not cause HHG in foxes, nor do the coding regions or intron-exon boundaries of these three genes contain any candidate mutations for fox gum disease. Patterns of molecular evolution among foxes and other mammals reflect high conservation and strong functional constraints for SOS1 and GRB2 but reveal a lineage-specific pattern of variability in EGFR consistent with mutational rate differences, relaxed functional constraints, and possibly positive selection.

Ras oncogenes in oral cancer: the past 20 years.

Science.gov (United States)

Murugan, Avaniyapuram Kannan; Munirajan, Arasambattu Kannan; Tsuchida, Nobuo

2012-05-01

Oral squamous cell carcinoma (OSCC) of head and neck is associated with high morbidity and mortality in both Western and Asian countries. Several risk factors for the development of oral cancer are very well established, including tobacco chewing, betel quid, smoking, alcohol drinking and human papilloma virus (HPV) infection. Apart from these risk factors, many genetic factors such as oncogenes, tumor suppressor genes and regulatory genes are identified to involve in oral carcinogenesis with these risk factors dependent and independent manner. Ras is one of the most frequently genetically deregulated oncogene in oral cancer. In this review, we analyze the past 22years of literature on genetic alterations such as mutations and amplifications of the isoforms of the ras oncogene in oral cancer. Further, we addressed the isoform-specific role of the ras in oral carcinogenesis. We also discussed how targeting the Akt and MEK, downstream effectors of the PI3K/Akt and MAPK pathways, respectively, would probably pave the possible molecular therapeutic target for the ras driven tumorigenesis in oral cancer. Analysis of these ras isoforms may critically enlighten specific role of a particular ras isoform in oral carcinogenesis, enhance prognosis and pave the way for isoform-specific molecular targeted therapy in OSCC. Copyright © 2011 Elsevier Ltd. All rights reserved.

PI3K: A Crucial Piece in the RAS Signaling Puzzle.

Science.gov (United States)

Krygowska, Agata Adelajda; Castellano, Esther

2018-06-01

RAS proteins are key signaling switches essential for control of proliferation, differentiation, and survival of eukaryotic cells. RAS proteins are mutated in 30% of human cancers. In addition, mutations in upstream or downstream signaling components also contribute to oncogenic activation of the pathway. RAS proteins exert their functions through activation of several signaling pathways and dissecting the contributions of these effectors in normal cells and in cancer is an ongoing challenge. In this review, we summarize our current knowledge about how RAS regulates type I phosphatidylinositol 3-kinase (PI3K), one of the main RAS effectors. RAS signaling through PI3K is necessary for normal lymphatic vasculature development and for RAS-induced transformation in vitro and in vivo, especially in lung cancer, where it is essential for tumor initiation and necessary for tumor maintenance. Copyright © 2018 Cold Spring Harbor Laboratory Press; all rights reserved.

v-Ha-ras oncogene insertion: A model for tumor progression of human small cell lung cancer

International Nuclear Information System (INIS)

Mabry, M.; Nakagawa, Toshitaro; Nelkin, B.D.; McDowell, E.; Gesell, M.; Eggleston, J.C.; Casero, R.A. Jr.; Baylin, S.B.

1988-01-01

Small cell lung cancer (SCLC) manifests a range of phenotypes in culture that may be important in understanding its relationship to non-SCLCs and to tumor progression events in patients. Most SCLC-derived cell lines, termed classic SCLC lines, have properties similar to SCLC tumors in patients. To delineate further the relationships between these phenotypes and the molecular events involved, the authors inserted the v-Ha-ras gene in SCLC cell lines with (biochemical variant) and without (classic) an amplified c-myc gene. These two SCLC subtypes had markedly different phenotypic responses to similar levels of expression of v-Ha-ras RNA. No biochemical or morphologic changes were observed in classic SCLC cells. In contrast, in biochemical variant SCLC cells, v-Ha-ras expression induced features typical of large cell undifferentiated lung carcinoma. Expression of v-Ha-ras in biochemical variant SCLC cells directly demonstrates that important transitions can occur between phenotypes of human lung cancer cells and that these may play a critical role in tumor progression events in patients. The finding provide a model system to study molecular events involved in tumor progression steps within a series of related tumor types

Cytological and oncogene alterations in radiation-transformed Syrian hamster embryo cells

International Nuclear Information System (INIS)

Trutschler, K.; Hieber, L.; Kellerer, A.M.

1991-01-01

Syrian hamster embryo (SHE) cells were neoplastically transformed by different types of ionizing radiation (γ-rays, α-particles or carbon ions). Transformed and tumor cell lines (derived from nude mice tumors) were analysed for alterations of the oncogenes c-Ha-ras and c-myc, i.e. RFLPs, gene amplifications, activation by point mutation, gene expression, and for cytological changes. In addition, the chromosome number and the numbers of micronuclei per cell have been determined in a series of cell lines. (author)

Induction of Non-Apoptotic Cell Death by Activated Ras Requires Inverse Regulation of Rac1 and Arf6

OpenAIRE

Bhanot, Haymanti; Young, Ashley M.; Overmeyer, Jean H.; Maltese, William A.

2010-01-01

Methuosis is a unique form of non-apoptotic cell death triggered by alterations in the trafficking of clathrin-independent endosomes, ultimately leading to extreme vacuolization and rupture of the cell. Methuosis can be induced in glioblastoma cells by expression of constitutively active Ras. This study identifies the small GTPases, Rac1 and Arf6, and the Arf6 GTPase-activating-protein, GIT1, as key downstream components of the signaling pathway underlying Ras-induced methuosis. The extent to...

Human Mut T Homolog 1 (MTH1): a roadblock for the tumor-suppressive effects of oncogenic RAS-induced ROS.

Science.gov (United States)

Rai, Priyamvada

2012-01-01

Oncogenic RAS-induced reactive oxygen species (ROS) trigger barriers to cell transformation and cancer progression through tumor-suppressive responses such as cellular senescence or cell death. We have recently shown that oncogenic RAS-induced DNA damage and attendant premature senescence can be prevented by overexpressing human MutT Homolog 1 (MTH1), the major mammalian detoxifier of the oxidized DNA precursor, 8-oxo-dGTP. Paradoxically, RAS-induced ROS are also able to participate in tumor progression via transformative processes such as mitogenic signaling, the epithelial-mesenchymal transition (EMT), anoikis inhibition, and PI3K/Akt-mediated survival signaling. Here we provide a preliminary insight into the influence of MTH1 levels on the EMT phenotype and Akt activation in RAS-transformed HMLE breast epithelial cells. Within this context, we will discuss the implications of MTH1 upregulation in oncogenic RAS-sustaining cells as a beneficial adaptive change that inhibits ROS-mediated cell senescence and participates in the maintenance of ROS-associated tumor-promoting mechanisms. Accordingly, targeting MTH1 in RAS-transformed tumor cells will not only induce proliferative defects but also potentially enhance therapeutic cytotoxicity by shifting cellular response away from pro-survival mechanisms.

K-ras mutations in gastric stump carcinomas and in carcinomas from the non-operated stomach

NARCIS (Netherlands)

van Rees, B. P.; Musler, A.; Caspers, E.; Drillenburg, P.; Craanen, M. E.; Polkowski, W.; Chibowski, D.; Offerhaus, G. J.

1999-01-01

Partial gastrectomy is a well-established pre-malignant condition. It is postulated that in the gastric stump an accelerated neoplastic process takes place, similar to that of (intestinal type) adenocarcinoma from the non-operated stomach. K-ras codon 12 mutation is one of the most frequent

Molecular transformation, gene cloning, and gene expression systems for filamentous fungi

Science.gov (United States)

Gold, Scott E.; Duick, John W.; Redman, Regina S.; Rodriguez, Rusty J.

2001-01-01

This chapter discusses the molecular transformation, gene cloning, and gene expression systems for filamentous fungi. Molecular transformation involves the movement of discrete amounts of DNA into cells, the expression of genes on the transported DNA, and the sustainable replication of the transforming DNA. The ability to transform fungi is dependent on the stable replication and expression of genes located on the transforming DNA. Three phenomena observed in bacteria, that is, competence, plasmids, and restriction enzymes to facilitate cloning, were responsible for the development of molecular transformation in fungi. Initial transformation success with filamentous fungi, involving the complementation of auxotrophic mutants by exposure to sheared genomic DNA or RNA from wt isolates, occurred with low transformation efficiencies. In addition, it was difficult to retrieve complementing DNA fragments and isolate genes of interest. This prompted the development of transformation vectors and methods to increase efficiencies. The physiological studies performed with fungi indicated that the cell wall could be removed to generate protoplasts. It was evident that protoplasts could be transformed with significantly greater efficiencies than walled cells.

Dual knockdown of N-ras and epiregulin synergistically suppressed the growth of human hepatoma cells

Energy Technology Data Exchange (ETDEWEB)

Zhao, Meng; He, Hong-wei; Sun, Huan-xing; Ren, Kai-huan [Department of Oncology, Institute of Medicinal Biotechnology, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing 100050 (China); Shao, Rong-guang, E-mail: shaor@bbn.cn [Department of Oncology, Institute of Medicinal Biotechnology, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing 100050 (China)

2009-09-18

Hepatocellular carcinoma (HCC) is a major challenge because of its resistance to conventional cytotoxic chemotherapy and radiotherapy. Multi-targeted therapy might be a new option for HCC treatment. Our previous study showed that N-ras gene was activated in HCC and was inhibited by RNA interference. In the present study, we investigated the alternation of gene expression by microarray in N-Ras-siRNA-treated HepG2 cells. The results revealed that the EREG gene, encoding epiregulin, was dramatically up-regulated in response to silence of N-ras. We speculated that the up-regulation of epiregulin was involved in the compensatory mechanism of N-ras knockdown for cell growth. Therefore, we evaluated whether dual silence of N-ras and epiregulin display a greater suppression of cell growth. The results confirmed that dual knockdown of N-ras and epiregulin synergistically inhibited cell growth. Our results also showed that dual knockdown of N-ras and epiregulin significantly induced cell arrest at G0/G1 phase. Furthermore, Western blot assay showed that dual knockdown of N-ras and epiregulin markedly reduced the phosphorylations of ERK1/2, Akt and Rb, and inhibited the expression of cyclin D1. Our findings imply that multi-targeted silence of oncogenes might be an effective treatment for HCC.

Heterogeneity in radiosensitivity within esophageal cell line CaEs-17 and amplification of H-ras gene

International Nuclear Information System (INIS)

Wang Shunbao; Guo Lei; Niu Wenzhe

1997-01-01

Ten clones were picked from cultured colonies of CaEs-17 cell line and developed to a subcell line. The values of SF 2 were measured for each subcell line. Two radioresistant subcell lines, clone 7 and clone 10 were established. According to survival curve assay, for wild type, the value of D 0 was 1.57 Gy, D Q was 1.07 Gy, N was 1.96, SF 2 was 0.41. For clone 7, the value of D 0 was 1.64 Gy, D Q was 1.85 Gy, N was 3.07, SF 2 was 0.53. For clone 10, the value of D 0 was 1.58 Gy, D Q was 2.04 Gy, N was 3.63, SF 2 was 0.61. Clone 7 and clone 10 have much higher values of D Q and N than those of wild type. There was amplification of H-ras gene in clone 10 after 2 Gy irradiation. The amplification of H-ras gene in clone 10 after 2 Gy irradiation might be involved in hetero geneity of CaEs-17 cell line

Increased p21ras activity in human fibroblasts transduced with survivin enhances cell proliferation

International Nuclear Information System (INIS)

Temme, Achim; Diestelkoetter-Bachert, Petra; Schmitz, Marc; Morgenroth, Agnieszka; Weigle, Bernd; Rieger, Michael A.; Kiessling, Andrea; Rieber, E. Peter

2005-01-01

Survivin is critically involved in mitosis and when overexpressed enhances the activity of the Aurora B kinase, a serine-threonine kinase belonging to the family of oncogenic Aurora/IpI1p-related kinases. Both proteins interact with Ras GTPase-activating protein suggesting an impact on the Ras pathway. This study aimed at defining the role of survivin in proliferation and potential transformation of cells. When survivin was overexpressed in normal human lung fibroblasts, the characteristic track lanes of fibroblasts were disturbed and the rate of cell proliferation was increased. An enhanced level of p21 ras mRNA and protein expression and concomitant rise in levels of activated p21 ras were observed. Despite increased proliferation cell survival remained dependent on serum and cells were not able to form colonies in soft agar assays. These data suggest that overexpression of survivin increases cell growth but, despite the increase in active p21 ras , is not sufficient to transform primary cells. Yet, in addition to its anti-apoptotic function it might contribute to the accelerated growth of tumour cells by increasing p21 ras activity

Predictive value of K-ras and PIK3CA in non-small cell lung cancer patients treated with EGFR-TKIs: a systemic review and meta-analysis

International Nuclear Information System (INIS)

Chen, Jie-Ying; Cheng, Ya-Nan; Han, Lei; Wei, Feng; Yu, Wen-Wen; Zhang, Xin-Wei; Cao, Shui; Yu, Jin-Pu

2015-01-01

A meta-analysis was performed to augment the insufficient data on the impact of mutative EGFR downstream phosphatidylinositol-3-kinase (PI3K) and mitogen-activated protein kinase (MAPK) pathways on the clinical efficiency of epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) treatment of non-small cell lung cancer (NSCLC) patients. Network databases were explored in April, 2015. Papers that investigated the clinical outcomes of NSCLC patients treated with EGFR-TKIs according to the status of K-ras and/or PIK3CA gene mutation were included. A quantitative meta-analysis was conducted using standard statistical methods. Odds ratios (ORs) for objective response rate (ORR) and hazard ratios (HRs) for progression-free survival (PFS) and overall survival (OS) were calculated. Mutation in K-ras significantly predicted poor ORR [OR =0.22; 95% confidence interval (CI), 0.13-0.35], shorter PFS (HR =1.56; 95% CI, 1.27-1.92), and shorter OS (HR =1.59; 95% CI, 1.33-1.91) in NSCLC patients treated with EGFR-TKIs. Mutant PIK3CA significantly predicted shorter OS (HR =1.83; 95% CI, 1.05-3.20), showed poor ORR (OR =0.70; 95% CI, 0.22-2.18), and shorter PFS (HR =1.79; 95% CI, 0.91-3.53) in NSCLC patients treated with EGFR-TKIs. K-ras mutation adversely affected the clinical response and survival of NSCLC patients treated with EGFR-TKIs. PIK3CA mutation showed similar trends. In addition to EGFR, adding K-ras and PIK3CA as routine gene biomarkers in clinical genetic analysis is valuable to optimize the effectiveness of EGFR-TKI regimens and identify optimal patients who will benefit from EGFR-TKI treatment

Non-covalent interactions of the carcinogen (+)-anti-BPDE with exon 1 of the human K-ras proto-oncogene

Science.gov (United States)

Rodriguez, Jorge H.; Deligkaris, Christos

2013-03-01

Investigating the complementary, but different, effects of physical (non-covalent) and chemical (covalent) mutagen-DNA and carcinogen-DNA interactions is important for understanding possible mechanisms of development and prevention of mutagenesis and carcinogenesis. A highly mutagenic and carcinogenic metabolite of the polycyclic aromatic hydrocarbon benzo[ α]pyrene, namely (+)-anti-BPDE, is known to undergo both physical and chemical complexation with DNA. The major covalent adduct, a promutagenic, is known to be an external (+)-trans-anti-BPDE-N2-dGuanosine configuration whose origins are not fully understood. Thus, it is desirable to study the mechanisms of external non-covalent BPDE-DNA binding and their possible relationships to external covalent trans adduct formation. We present a detailed codon-by-codon computational study of the non-covalent interactions of (+)-anti-BPDE with DNA which explains and correctly predicts preferential (+)-anti-BPDE binding at minor groove guanosines. Due to its relevance to carcinogenesis, the interaction of (+)-anti-BPDE with exon 1 of the human K-ras gene has been studied in detail. Present address: Department of Physics, Drury University

Transformation and Stability of Cloned Polysaccharidase Genes in Gram-Positive Bacteria

OpenAIRE

EKİNCİ, Mehmet Sait

2014-01-01

Polysaccharidase genes from rumen bacteria were transferred to and expressed in ruminal and non-ruminal Gram-positive bacteria. The transformation efficiency and genetic stability of polysaccharidase genes in bacteria from different habitats were investigated. PCR amplification of cloned polysaccharidase genes from Escherichia coli, Lactococcus lactis, Enterococcus faecalis, Streptococcus sanguis and S. bovis strain 26 showed that rearrangement of plasmid and the gene fragment did not occur. ...

Blocking anaplerotic entry of glutamine into the TCA cycle sensitizes K-Ras mutant cancer cells to cytotoxic drugs.

Science.gov (United States)

Saqcena, M; Mukhopadhyay, S; Hosny, C; Alhamed, A; Chatterjee, A; Foster, D A

2015-05-14

Cancer cells undergo a metabolic transformation that allows for increased anabolic demands, wherein glycolytic and tricarboxylic acid (TCA) cycle intermediates are shunted away for the synthesis of biological molecules required for cell growth and division. One of the key shunts is the exit of citrate from the mitochondria and the TCA cycle for the generation of cytosolic acetyl-coenzyme A that can be used for fatty acid and cholesterol biosynthesis. With the loss of mitochondrial citrate, cancer cells rely on the 'conditionally essential' amino acid glutamine (Q) as an anaplerotic carbon source for TCA cycle intermediates. Although Q deprivation causes G1 cell cycle arrest in non-transformed cells, its impact on the cancer cell cycle is not well characterized. We report here a correlation between bypass of the Q-dependent G1 checkpoint and cancer cells harboring K-Ras mutations. Instead of arresting in G1 in response to Q-deprivation, K-Ras-driven cancer cells arrest in either S- or G2/M-phase. Inhibition of K-Ras effector pathways was able to revert cells to G1 arrest upon Q deprivation. Blocking anaplerotic utilization of Q mimicked Q deprivation--causing S- and G2/M-phase arrest in K-Ras mutant cancer cells. Significantly, Q deprivation or suppression of anaplerotic Q utilization created synthetic lethality to the cell cycle phase-specific cytotoxic drugs, capecitabine and paclitaxel. These data suggest that disabling of the G1 Q checkpoint could represent a novel vulnerability of cancer cells harboring K-Ras and possibly other mutations that disable the Q-dependent checkpoint.

p53, erbB-2 and K-ras gene alterations are rare in spontaneous and plutonium-239-induced canine lung neoplasia

International Nuclear Information System (INIS)

Tierney, L.A.; Hahn, F.F.; Lechner, J.F.

1996-01-01

Inhalation of high-linear energy transfer radiation in the form of radon progeny is a suspected cause of human lung cancer. To gain insight into the types of genetic derangements caused by this type of radiation, lung tumors from beagle dogs exposed to 239 PuO 2 and those arising in animals with no known carcinogen exposure were examined for evidence of aberrations in genes known to be altered in lung tumors. Altered expression of the p53 tumor suppressor gene and proto-oncogene erbB-2 proteins (p185 erbB2 ) was evaluated by immunohistochemical analysis of 117 tumors representing different histological types in exposed (n = 80) and unexposed (n = 37) animals. Twenty-eight tumors were analyzed for K-ras proto-oncogene mutations by polymerase chain reaction amplification and direct sequencing. Fourteen percent (16/116) of all lung neoplasms showed elevated nuclear accumulation of p53 protein. Regardless of exposure history, adenosquamous and squamous cell cancers comprised 94% of all tumors with p53 abnormalities. Eighteen percent (21/117) of all tumors had evidence of erbB-2 protein overexpression. K-ras mutations were not detected in codons 12, 13 or 61 of tumors from unexposed (n = 9) or plutonium-exposed dogs (n = 19). These data indicate that p53 and K-ras gene abnormalities as a result of missense mutation are infrequent events in spontaneous and 239 PuO 2 -induced lung neoplasia in this colony of beagle dogs. Alternative mechanisms of gene alteration may be involved in canine pulmonary carcinogenesis. 45 refs., 3 figs., 2 tabs

RAS/ERK modulates TGFβ-regulated PTEN expression in human pancreatic adenocarcinoma cells

OpenAIRE

Chow, Jimmy Y.C.; Quach, Khai T.; Cabrera, Betty L.; Cabral, Jennifer A.; Beck, Stayce E.; Carethers, John M.

2007-01-01

Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is rarely mutated in pancreatic cancers, but its regulation by transforming growth factor (TGF)-β might mediate growth suppression and other oncogenic actions. Here, we examined the role of TGFβ and the effects of oncogenic K-RAS/ERK upon PTEN expression in the absence of SMAD4. We utilized two SMAD4-null pancreatic cell lines, CAPAN-1 (K-RAS mutant) and BxPc-3 (WT-K-RAS), both of which express TGFβ surface receptors. Cells were t...

Promoter methylation of RASSF1A and DAPK and mutations of K-ras, p53, and EGFR in lung tumors from smokers and never-smokers

International Nuclear Information System (INIS)

Liu, Yang; Gao, Weimin; Siegfried, Jill M; Weissfeld, Joel L; Luketich, James D; Keohavong, Phouthone

2007-01-01

Epidemiological studies indicate that some characteristics of lung cancer among never-smokers significantly differ from those of smokers. Aberrant promoter methylation and mutations in some oncogenes and tumor suppressor genes are frequent in lung tumors from smokers but rare in those from never-smokers. In this study, we analyzed promoter methylation in the ras-association domain isoform A (RASSF1A) and the death-associated protein kinase (DAPK) genes in lung tumors from patients with primarily non-small cell lung cancer (NSCLC) from the Western Pennsylvania region. We compare the results with the smoking status of the patients and the mutation status of the K-ras, p53, and EGFR genes determined previously on these same lung tumors. Promoter methylation of the RASSF1A and DAPK genes was analyzed by using a modified two-stage methylation-specific PCR. Data on mutations of K-ras, p53, and EGFR were obtained from our previous studies. The RASSF1A gene promoter methylation was found in tumors from 46.7% (57/122) of the patients and was not significantly different between smokers and never-smokers, but was associated significantly in multiple variable analysis with tumor histology (p = 0.031) and marginally with tumor stage (p = 0.063). The DAPK gene promoter methylation frequency in these tumors was 32.8% (40/122) and did not differ according to the patients' smoking status, tumor histology, or tumor stage. Multivariate analysis adjusted for age, gender, smoking status, tumor histology and stage showed that the frequency of promoter methylation of the RASSF1A or DAPK genes did not correlate with the frequency of mutations of the K-ras, p53, and EGFR gene. Our results showed that RASSF1A and DAPK genes' promoter methylation occurred frequently in lung tumors, although the prevalence of this alteration in these genes was not associated with the smoking status of the patients or the occurrence of mutations in the K-ras, p53 and EGFR genes, suggesting each of

Evolution of AF6-RAS association and its implications in mixed-lineage leukemia

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Smith, Matthew J.; Ottoni, Elizabeth; Ishiyama, Noboru; Goudreault, Marilyn; Haman, André; Meyer, Claus; Tucholska, Monika; Gasmi-Seabrook, Genevieve; Menezes, Serena; Laister, Rob C.; Minden, Mark D.; Marschalek, Rolf; Gingras, Anne-Claude; Hoang, Trang; Ikura, Mitsuhiko

2017-10-23

Elucidation of activation mechanisms governing protein fusions is essential for therapeutic development. MLL undergoes rearrangement with numerous partners, including a recurrent translocation fusing the epigenetic regulator to a cytoplasmic RAS effector, AF6/afadin. We show here that AF6 employs a non-canonical, evolutionarily conserved α-helix to bind RAS, unique to AF6 and the classical RASSF effectors. Further, all patients with MLL-AF6 translocations express fusion proteins missing only this helix from AF6, resulting in exposure of hydrophobic residues that induce dimerization. We provide evidence that oligomerization is the dominant mechanism driving oncogenesis from rare MLL translocation partners and employ our mechanistic understanding of MLL-AF6 to examine how dimers induce leukemia. Proteomic data resolve association of dimerized MLL with gene expression modulators, and inhibiting dimerization disrupts formation of these complexes while completely abrogating leukemogenesis in mice. Oncogenic gene translocations are thus selected under pressure from protein structure/function, underscoring the complex nature of chromosomal rearrangements.

Mutations in APC, CTNNB1 and K-ras genes and expression of hMLH1 in sporadic colorectal carcinomas from the Netherlands Cohort Study

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Lüchtenborg, Margreet; Weijenberg, Matty P; Wark, Petra A; Saritas, A Merdan; Roemen, Guido MJM; Muijen, Goos NP van; Bruïne, Adriaan P de; Brandt, Piet A van den; Goeij, Anton FPM de

2005-01-01

The early to intermediate stages of the majority of colorectal tumours are thought to be driven by aberrations in the Wnt (APC, CTNNB1) and Ras (K-ras) pathways. A smaller proportion of cancers shows mismatch repair deficiency. The aim of this study was to analyse the co-occurrence of these genetic alterations in relation to tumour and patient characteristics. In a group of 656 unselected sporadic colorectal cancer patients, aberrations in the APC, K-ras, CTNNB1 genes, and expression of hMLH1 were investigated. Additionally, tumours were divided in groups based on molecular features and compared with respect to patient's age at diagnosis, sex, family history of colorectal cancer, tumour sub-localisation, Dukes' stage and differentiation. Mutations at the phosphorylation sites (codons 31, 33, 37, and 45) in the CTNNB1 gene were observed in tumours from only 5/464 patients. Tumours with truncating APC mutations and activating K-ras mutations in codons 12 and 13 occurred at similar frequencies (37% (245/656) and 36% (235/656), respectively). Seventeen percent of tumours harboured both an APC and a K-ras mutation (109/656). Nine percent of all tumours (58/656) lacked hMLH1 expression. Patients harbouring a tumour with absent hMLH1 expression were older, more often women, more often had proximal colon tumours that showed poorer differentiation when compared to patients harbouring tumours with an APC and/or K-ras mutation. CTNNB1 mutations seem to be of minor importance in sporadic colorectal cancer. The main differences in tumour and patient characteristics are found between groups of patients based on mismatch repair deficiency

Mutations in APC, CTNNB1 and K-ras genes and expression of hMLH1 in sporadic colorectal carcinomas from the Netherlands Cohort Study

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de Bruïne Adriaan P

2005-12-01

Full Text Available Abstract Background The early to intermediate stages of the majority of colorectal tumours are thought to be driven by aberrations in the Wnt (APC, CTNNB1 and Ras (K-ras pathways. A smaller proportion of cancers shows mismatch repair deficiency. The aim of this study was to analyse the co-occurrence of these genetic alterations in relation to tumour and patient characteristics. Methods In a group of 656 unselected sporadic colorectal cancer patients, aberrations in the APC, K-ras, CTNNB1 genes, and expression of hMLH1 were investigated. Additionally, tumours were divided in groups based on molecular features and compared with respect to patient's age at diagnosis, sex, family history of colorectal cancer, tumour sub-localisation, Dukes' stage and differentiation. Results Mutations at the phosphorylation sites (codons 31, 33, 37, and 45 in the CTNNB1 gene were observed in tumours from only 5/464 patients. Tumours with truncating APC mutations and activating K-ras mutations in codons 12 and 13 occurred at similar frequencies (37% (245/656 and 36% (235/656, respectively. Seventeen percent of tumours harboured both an APC and a K-ras mutation (109/656. Nine percent of all tumours (58/656 lacked hMLH1 expression. Patients harbouring a tumour with absent hMLH1 expression were older, more often women, more often had proximal colon tumours that showed poorer differentiation when compared to patients harbouring tumours with an APC and/or K-ras mutation. Conclusion CTNNB1 mutations seem to be of minor importance in sporadic colorectal cancer. The main differences in tumour and patient characteristics are found between groups of patients based on mismatch repair deficiency.

Immunodetection of rasP21 and c-myc oncogenes in oral mucosal swab preparation from clove cigarette smokers

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Silvi Kintawati

2008-12-01

Full Text Available Background: Smoking is the biggest factor for oral cavity malignancy. Some carcinogens found in cigar will stimulate epithel cell in oral cavity and cause mechanism disturbance on tissue resistance and produce abnormal genes (oncogenes. Oncogenes ras and myc are found on malignant tumor in oral cavity which are associated with smoking. Purpose: This research is to find the expression of oncogenes rasP21 and c-myc in oral mucosa epithelial of smoker with immunocytochemistry reaction. Methods: An oral mucosal swab was performed to 30 smokers categorized as light, moderate, and chain, and 10 non smokers which was followed by immunocytochemistry reaction using antibody towards oncogene rasP21 and c-myc is reacted to identify the influence of smoking towards malignant tumor in oral cavity. The result is statistically analyzed using Kruskal-Wallis test. Result: Based on the observation result of oncogene rasP21reaction, it shows that there is significant difference between non smoker group and light smoker, compared to moderate and chain smoker group (p < 0.01. On the other side, the observation result of oncogene c-myc indicates that there is no significant difference between the group of non smokers and the group of light, moderate, and chain smokers (p > 0.05. Conclusion: The higher the possibility of oral cavity malignancy and that the antibody for rasP21 oncogene can be used as a marker for early detection of oral cavity malignancy caused by smoking.

Identification of auxotrophic mutants of the yeast Kluyveromyces marxianus by non-homologous end joining-mediated integrative transformation with genes from Saccharomyces cerevisiae.

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Yarimizu, Tohru; Nonklang, Sanom; Nakamura, Junpei; Tokuda, Shuya; Nakagawa, Takaaki; Lorreungsil, Sasithorn; Sutthikhumpha, Surasit; Pukahuta, Charida; Kitagawa, Takao; Nakamura, Mikiko; Cha-Aim, Kamonchai; Limtong, Savitree; Hoshida, Hisashi; Akada, Rinji

2013-12-01

The isolation and application of auxotrophic mutants for gene manipulations, such as genetic transformation, mating selection and tetrad analysis, form the basis of yeast genetics. For the development of these genetic methods in the thermotolerant fermentative yeast Kluyveromyces marxianus, we isolated a series of auxotrophic mutants with defects in amino acid or nucleic acid metabolism. To identify the mutated genes, linear DNA fragments of nutrient biosynthetic pathway genes were amplified from Saccharomyces cerevisiae chromosomal DNA and used to directly transform the K. marxianus auxotrophic mutants by random integration into chromosomes through non-homologous end joining (NHEJ). The appearance of transformant colonies indicated that the specific S. cerevisiae gene complemented the K. marxianus mutant. Using this interspecific complementation approach with linear PCR-amplified DNA, we identified auxotrophic mutations of ADE2, ADE5,7, ADE6, HIS2, HIS3, HIS4, HIS5, HIS6, HIS7, LYS1, LYS2, LYS4, LYS9, LEU1, LEU2, MET2, MET6, MET17, TRP3, TRP4 and TRP5 without the labour-intensive requirement of plasmid construction. Mating, sporulation and tetrad analysis techniques for K. marxianus were also established. With the identified auxotrophic mutant strains and S. cerevisiae genes as selective markers, NHEJ-mediated integrative transformation with PCR-amplified DNA is an attractive system for facilitating genetic analyses in the yeast K. marxianus. Copyright © 2013 John Wiley & Sons, Ltd.

Induction of Non-Apoptotic Cell Death by Activated Ras Requires Inverse Regulation of Rac1 and Arf6

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Bhanot, Haymanti; Young, Ashley M.; Overmeyer, Jean H.; Maltese, William A.

2010-01-01

Methuosis is a unique form of non-apoptotic cell death triggered by alterations in the trafficking of clathrin-independent endosomes, ultimately leading to extreme vacuolization and rupture of the cell. Methuosis can be induced in glioblastoma cells by expression of constitutively active Ras. This study identifies the small GTPases, Rac1 and Arf6, and the Arf6 GTPase-activating-protein, GIT1, as key downstream components of the signaling pathway underlying Ras-induced methuosis. The extent to which graded expression of active H-Ras(G12V) triggers cytoplasmic vacuolization correlates with the amount of endogenous Rac1 in the active GTP state. Blocking Rac1 activation with the specific Rac inhibitor, EHT 1864, or co-expression of dominant-negative Rac1(T17N), prevents the accumulation of vacuoles induced by H-Ras(G12V). Coincident with Rac1 activation, H-Ras(G12V) causes a decrease in the amount of active Arf6, a GTPase that functions in recycling of clathrin-independent endosomes. The effect of H-Ras(G12V) on Arf6 is blocked by EHT 1864, indicating that the decrease in Arf6-GTP is directly linked to activation of Rac1. Constitutively active Rac1(G12V) interacts with GIT1 in immunoprecipitation assays. Ablation of GIT1 by shRNA prevents the decrease in active Arf6, inhibits vacuolization, and prevents loss of cell viability in cells expressing Rac1(G12V). Together the results suggest that perturbations of endosome morphology associated with Ras-induced methuosis are due to downstream activation of Rac1, combined with reciprocal inactivation of Arf6. The latter appears to be mediated through Rac1 stimulation of GIT1. Further insights into this pathway could suggest opportunities for induction of methuosis in cancers that are resistant to apoptotic cell death. PMID:20713492

Trabecular meshwork ECM remodeling in glaucoma: could RAS be a target?

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Agarwal, Puneet; Agarwal, Renu

2018-06-14

Disturbances of extracellular matrix (ECM) homeostasis in trabecular meshwork (TM) cause increased aqueous outflow resistance leading to elevated intraocular pressure (IOP) in glaucomatous eyes. Therefore, restoration of ECM homeostasis is a rational approach to prevent disease progression. Since renin-angiotensin system (RAS) inhibition positively alters ECM homeostasis in cardiovascular pathologies involving pressure and volume overload, it is likely that RAS inhibitors reduce IOP primarily by restoring ECM homeostasis. Areas covered: Current evidence showing the presence of RAS components in ocular tissue and its role in regulating aqueous humor dynamics is briefly summarized. The role of RAS in ECM remodeling is discussed both in terms of its effects on ECM synthesis and its breakdown. The mechanisms of ECM remodeling involving interactions of RAS with transforming growth factor-β, Wnt/β-catenin signaling, bone morphogenic proteins, connective tissue growth factor, and matrix metalloproteinases in ocular tissue are discussed. Expert opinion: Current literature strongly indicates a significant role of RAS in ECM remodeling in TM of hypertensive eyes. Hence, IOP-lowering effect of RAS inhibitors may primarily be attributed to restoration of ECM homeostasis in aqueous outflow pathways rather than its vascular effects. However, the mechanistic targets for RAS inhibitors have much wider distribution and consequences, which remain relatively unexplored in TM.

Genotyping of K-ras codons 12 and 13 mutations in colorectal cancer by capillary electrophoresis.

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Chen, Yen-Ling; Chang, Ya-Sian; Chang, Jan-Gowth; Wu, Shou-Mei

2009-06-26

Point mutations of the K-ras gene located in codons 12 and 13 cause poor responses to the anti-epidermal growth factor receptor (anti-EGFR) therapy of colorectal cancer (CRC) patients. Besides, mutations of K-ras gene have also been proven to play an important role in human tumor progression. We established a simple and effective capillary electrophoresis (CE) method for simultaneous point mutation detection in codons 12 and 13 of K-ras gene. We combined one universal fluorescence-based nonhuman-sequence primer and two fragment-oriented primers in one tube, and performed this two-in-one polymerase chain reaction (PCR). PCR fragments included wild type and seven point mutations at codons 12 and 13 of K-ras gene. The amplicons were analyzed by single-strand conformation polymorphism (SSCP)-CE method. The CE analysis was performed by using a 1x Tris-borate-EDTA (TBE) buffer containing 1.5% (w/v) hydroxyethylcellulose (HEC) (MW 250,000) under reverse polarity with 15 degrees C and 30 degrees C. Ninety colorectal cancer patients were blindly genotyped using this developed method. The results showed good agreement with those of DNA sequencing method. The SSCP-CE was feasible for mutation screening of K-ras gene in populations.

[Experimental study on carcinogenesis by human papillomavirus type 8 E7 gene].

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Nishikawa, T

1994-05-01

Human papillomavirus (HPV) 5 and HPV8 are often detected in skin cancers developed in patients suffering from epidermodysplasia verruciformis, as well as in skin cancers developed in immunosuppressed patients. In the present study, in order to examine the transforming activity of the HPV8E7 gene, the HPV8E7 and HPV8E6/E7 genes were cloned into the expression vector (pcD2-Y), under the SV40 enhancer/promoter to construct pcD2-8E7 and pcD2-8E6/E7, respectively. The E7 and E6/E7 genes of genital high-risk HPV16 were also cloned into pcD2-Y to construct pcD2-16E7 and pcD2-16E6/E7, respectively. They were tested for their ability to collaboratively transform primary rat embryo fibroblasts (REFs) with activated H-ras gene. Transfection experiments of REFs having an activated H-ras gene revealed that pcD2-8E7, as well as pcD2-16E7 and pcD2-16E6/E7, induced transformation of cells in G418-resistant colonies at efficiencies of 11.9%, 43.0% and 53.0%, respectively. Transformed cell lines induced by activated H-ras gene and pcD2-8E7 or pcD2-16E7 were named 8RE and 16RE cell lines, respectively. Tumor induction in syngeneic newborn rats by injected the 8RE cells was higher than that of the 16RE cells. In cytological and histological examination, the 8RE cell lines and their induced tumors were different from the 16RE cell lines and their induced tumors. The 8RE cell lines showed the characteristic transformation with efficient growth ability on plastic and colony formation in 0.3% soft agar. These results support the hypothesis that the HPV8E7 gene plays an important role in the carcinogenesis of skin cancers.

Tumorigenesis of K-ras mutation in human endometrial carcinoma via upregulation of estrogen receptor.

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Tu, Zheng; Gui, Liming; Wang, Jianliu; Li, Xiaoping; Sun, Pengming; Wei, Lihui

2006-05-01

To investigate the tumorigenesis of mutant [12Asp]-K-ras in endometrial carcinoma and its relationship with ER. We constructed pcDI-[12Asp]K-ras4B by inserting full-length [12Asp]K-ras4B from human endometrial carcinoma Hec-1A cells, into pcDI vector. Cell proliferation of NIH3T3 after transfection with pcDI-[12Asp]K-ras4B was measured by MTT assay. The cell transformation was determined by colony formation and tumor nodule development. [12Asp]-K-ras4B-NIH3T3 cells were transfected with constitutively active pCMV-RafCAAX and dominant-negative pCMV-RafS621A. Cell growth was measured by MTT assay and [3H]thymidine incorporation. After transfected with pcDI-[12Asp]K-ras4B or pCMV-RafS621A, the cells were harvested for Western blot and reporter assay to determine the expression and transcriptional activity of ERalpha and ERbeta, respectively. [12Asp]-K-ras4B enhanced NIH3T3 cells proliferation after 48 h post-transfection (P ras4B-NIH3T3 cells (13.48%) than pcDI-NIH3T3 (4.26%) or untreated NIH3T3 (2.33%). The pcDI-[12Asp]-K-ras4B-NIH3T3 cells injected to the nude mice Balb/C developed tumor nodules with poor-differentiated cells after 12 days. An increase of ERalpha and ERbeta was observed in pcDI-[12Asp]-K-ras4B-NIH3T3 cells. RafS621A downregulated ERalpha and ERbeta expression. Estrogen induced the ER transcriptional activity by 5-fold in pcDI-NIH3T3 cells, 13-fold in pcDI-[12Asp]K-ras4B-NIH3T3 and 19-fold in HEC-1A. RafS621A suppressed the ER transcriptional activity. K-ras mutation induces tumorigenesis in endometrium, and this malignant transformation involves Raf signaling pathway and ER.

Increased OXPHOS activity precedes rise in glycolytic rate in H-RasV12/E1A transformed fibroblasts that develop a Warburg phenotype

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Pluk Helma

2009-07-01

Full Text Available Abstract Background The Warburg phenotype in cancer cells has been long recognized, but there is still limited insight in the consecutive metabolic alterations that characterize its establishment. We obtained better understanding of the coupling between metabolism and malignant transformation by studying mouse embryonic fibroblast-derived cells with loss-of-senescence or H-RasV12/E1A-transformed phenotypes at different stages of oncogenic progression. Results Spontaneous immortalization or induction of senescence-bypass had only marginal effects on metabolic profiles and viability. In contrast, H-RasV12/E1A transformation initially caused a steep increase in oxygen consumption and superoxide production, accompanied by massive cell death. During prolonged culture in vitro, cell growth rate increased gradually, along with tumor forming potential in in vitro anchorage-independent growth assays and in vivo tumor formation assays in immuno-deficient mice. Notably, glucose-to-lactic acid flux increased with passage number, while cellular oxygen consumption decreased. This conversion in metabolic properties was associated with a change in mitochondrial NAD+/NADH redox, indicative of decreased mitochondrial tricarboxic acid cycle and OXPHOS activity. Conclusion The high rate of oxidative metabolism in newly transformed cells is in marked contrast with the high glycolytic rate in cells in the later tumor stage. In our experimental system, with cells growing under ambient oxygen conditions in nutrient-rich media, the shift towards this Warburg phenotype occurred as a step-wise adaptation process associated with augmented tumorigenic capacity and improved survival characteristics of the transformed cells. We hypothesize that early-transformed cells, which potentially serve as founders for new tumor masses may escape therapies aimed at metabolic inhibition of tumors with a fully developed Warburg phenotype.

Homologous gene targeting of a carotenoids biosynthetic gene in Rhodosporidium toruloides by Agrobacterium-mediated transformation.

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Sun, Wenyi; Yang, Xiaobing; Wang, Xueying; Lin, Xinping; Wang, Yanan; Zhang, Sufang; Luan, Yushi; Zhao, Zongbao K

2017-07-01

To target a carotenoid biosynthetic gene in the oleaginous yeast Rhodosporidium toruloides by using the Agrobacterium-mediated transformation (AMT) method. The RHTO_04602 locus of R. toruloides NP11, previously assigned to code the carotenoid biosynthetic gene CRTI, was amplified from genomic DNA and cloned into the binary plasmid pZPK-mcs, resulting in pZPK-CRT. A HYG-expression cassette was inserted into the CRTI sequence of pZPK-CRT by utilizing the restriction-free clone strategy. The resulted plasmid was used to transform R. toruloides cells according to the AMT method, leading to a few white transformants. Sequencing analysis of those transformants confirmed homologous recombination and insertional inactivation of CRTI. When the white variants were transformed with a CRTI-expression cassette, cells became red and produced carotenoids as did the wild-type strain NP11. Successful homologous targeting of the CrtI locus confirmed the function of RHTO_04602 in carotenoids biosynthesis in R. toruloides. It provided valuable information for metabolic engineering of this non-model yeast species.

Exploring environmental causes of altered ras effects: fragmentation plus integration?

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Porta, Miquel; Ayude, Daniel; Alguacil, Juan; Jariod, Manuel

2003-02-01

Mutations in ras genes are the most common abnormality of oncogenes in human cancer and a major example of activation by point mutation. Experimental and epidemiological studies support the notion that Ki-ras activation and expression may be chemically related. We discuss the potential role of several environmental compounds in the induction or promotion of ras mutations in humans, with a focus on exocrine pancreatic cancer, the human tumor with the highest prevalence at diagnosis of Ki-ras mutations. Organochlorine compounds, organic solvents, and coffee compounds may play an indirect role in causing Ki-ras mutations, rather than as direct inducers of the mutations. Although for some organochlorine compounds the induction of point mutations in ras oncogenes cannot be excluded, it seems more likely that the effects of these compounds are mediated through nongenomic or indirectly genotoxic mechanisms of action. Organic solvents also may act via enzymatic induction of ras mutagens or by providing a proliferation advantage to ras-mutated cell clones. In exocrine pancreatic cancer, caffeine, other coffee compounds, or other factors with which coffee drinking is associated could modulate Ki-ras activation by interfering with DNA repair, cell-cycle checkpoints, and apoptosis. Asbestos, cigarette smoking, and some dietary factors also may be involved in the initiation or the promotion of Ki-ras mutations in lung and colon cancers. Further development of the mechanistic scenarios proposed here could contribute to a meaningful integration of biological, clinical, and environmental knowledge on the causes of altered ras effects. Copyright 2003 Wiley-Liss, Inc.

DNA mismatch repair deficiency accelerates lung neoplasm development in K-rasLA1/+ mice: a brief report

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Downey, Charlene M; Jirik, Frank R

2015-01-01

Inherited as well as acquired deficiencies in specific DNA mismatch repair (MMR) components are associated with the development of a wide range of benign and malignant neoplasms. Loss of key members such as MSH2 and MLH1 severely cripples the ability of the cell to recognize and correct such lesions as base:base mismatches and replicative DNA polymerase errors such as slippages at repetitive sequences. Genomic instability resulting from MMR deficiency not only predisposes cells to malignant transformation but may also promote tumor progression. To test the latter, we interbred Msh2 −/− mice with the K-ras LA1/+ transgenic line that spontaneously develops a range of premalignant and malignant lung lesions. Compared to K-ras LA1/+ mice, K-ras LA1/+ ; Msh2 −/− mice developed lung adenomas and adenocarcinomas at an increased frequency and also demonstrated evidence of accelerated adenocarcinoma growth. Since MMR defects have been identified in some human lung cancers, the mutant mice may not only be of preclinical utility but they will also be useful in identifying gene alterations able to act in concert with Kras mutants to promote tumor progression

High-throughput screening identifies small molecules that bind to the RAS:SOS:RAS complex and perturb RAS signaling.

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Burns, Michael C; Howes, Jennifer E; Sun, Qi; Little, Andrew J; Camper, DeMarco V; Abbott, Jason R; Phan, Jason; Lee, Taekyu; Waterson, Alex G; Rossanese, Olivia W; Fesik, Stephen W

2018-05-01

K-RAS is mutated in approximately 30% of human cancers, resulting in increased RAS signaling and tumor growth. Thus, RAS is a highly validated therapeutic target, especially in tumors of the pancreas, lung and colon. Although directly targeting RAS has proven to be challenging, it may be possible to target other proteins involved in RAS signaling, such as the guanine nucleotide exchange factor Son of Sevenless (SOS). We have previously reported on the discovery of small molecules that bind to SOS1, activate SOS-mediated nucleotide exchange on RAS, and paradoxically inhibit ERK phosphorylation (Burns et al., PNAS, 2014). Here, we describe the discovery of additional, structurally diverse small molecules that also bind to SOS1 in the same pocket and elicit similar biological effects. We tested >160,000 compounds in a fluorescence-based assay to assess their effects on SOS-mediated nucleotide exchange. X-Ray structures revealed that these small molecules bind to the CDC25 domain of SOS1. Compounds that elicited high levels of nucleotide exchange activity in vitro increased RAS-GTP levels in cells, and inhibited phospho ERK levels at higher treatment concentrations. The identification of structurally diverse SOS1 binding ligands may assist in the discovery of new molecules designed to target RAS-driven tumors. Copyright © 2018 Elsevier Inc. All rights reserved.

Influence of a ras oncogene on platelet-derived growth factor (PDGF)-stimulated phosphoinositide hydrolysis in murine fibroblasts

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Parries, G.; Racker, E.

1986-01-01

The authors have examined the effects of transfection of rat-1 fibroblasts with the ras oncogene on the metabolism of phosphatidylinositol (PI). Incubation of [ 3 H]inositol-labeled rat-1 cells with PDGF resulted in a 2- to 3-fold increase in [ 3 H]IP3 levels within 90 s. In the presence of 25 mM Li+, [ 3 H]IP1 levels were increased 8-fold after 30 min. In contrast, incubation of ras-transfected fibroblasts (EJ-2 line) with PDGF had little or no effect on the level of either [ 3 H]IP3 or [ 3 H]IP1. Similar stimulations by PDGF were observed in NIH 3T3 cells, but not in Kirsten virus-transformed or Harvey ras-transfected cell lines. On the other hand, NIH 3T3 cells transfected with v-src responded to PDGF by stimulation of PI turnover similar to the parent cell line. In NIH 3T3 cells transfected with an expression vector containing the v-Ha-ras gene under transcriptional control of the glucocorticoid-inducible mouse mammary tumor virus promoter, the PDGF stimulation of [ 3 H]inositol incorporation into PI was reduced from 10-fold in the absence of dexamethasone to 1.8-fold when the cells were pretreated for 26 h with 2 μM dexamethasone. In the parental 3T3 cells PDGF stimulation was reduced by about 40% in the presence of dexamethasone. In the absence of PDGF the rate of PI turnover (i.e., the kinetics of [ 3 H]IP1 accumulation in the presence of Li+) in EJ-2 cells was similar to that in rat-1 cells. Thus, in the presence of PDGF, the rate of PI turnover in rat-1 cells was several fold higher than in the transfected cells. These results suggest that the ras gene product (p21) may exert an inhibitory effect on PDGF-stimulated phosphoinositide metabolism

The prognostic impact of K-RAS mutations in adult acute myeloid leukemia patients treated with high-dose cytarabine

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Ahmad EI

2011-07-01

Full Text Available Ebtesam I Ahmad, Heba H Gawish, Nashwa MA Al Azizi, Ashraf M ElhefniClinical Pathology Department, Hematology and Oncology Unit of Internal Medicine Department, Faculty of Medicine, Zagazig University, Sharkia, EgyptBackground: Activating point mutation of the RAS gene has been generally accepted as an oncogenic event in a variety of malignancies. It represents one of the most common genetic alterations in acute myeloid leukemia (AML. However, little is known about its clinical relevance in the treatment outcome for this leukemia.Objective: This study aimed to clarify the biologic and prognostic impact of K-RAS mutations in relation to the dose of cytarabine (ara-C used in postinduction consolidation chemotherapy in adult AML patients.Patients and methods: The study comprised of 71 de novo AML patients with male/female ratio 1.4:1; their ages ranged from 21–59 years with a median of 37 years. They were subjected to full clinical evaluation, routine laboratory investigations, cytogenetic studies by G-banding (Giemsa staining, and K-RAS mutation detection using real-time polymerase chain reaction. The patients were randomized into two groups according to the ara-C dose used in consolidation treatment, the high the dose ara-C (HDAC group receiving 400 mg ara-C and-low-dose ara-C (LDAC group receiving 100 mg ara-C; they were followed over a period of five years.Results: Mutations in the K-RAS gene (mutRAS were detected in 23 patients (32% with the remaining 48 patients (68% having wild-type RAS (wtRAS. The percent of blast cells was significantly lower in mutRAS compared to wtRAS patients (P ≤ 0.001 while M4 subtype of AML and Inv(16 frequencies were significantly higher in mutRAS compared to wtRAS patients (P = 0.015 and (P = 0.003, respectively. The patients were followed up for a median of 43 months (range 11–57 months. There was no significant difference in overall survival (OS between mutRAS and wtRAS (P = 0.326. Within the mutRAS

Oxidative Stress Posttranslationally Regulates the Expression of Ha-Ras and Ki-Ras in Cultured Astrocytes

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Samantha Messina

2012-01-01

Full Text Available Addition of hydrogen peroxide to cultured astrocytes induced a rapid and transient increase in the expression of Ha-Ras and Ki-Ras. Pull-down experiments with the GTP-Ras-binding domain of Raf-1 showed that oxidative stress substantially increased the activation of Ha-Ras, whereas a putative farnesylated activated form of Ki-Ras was only slightly increased. The increase in both Ha-Ras and Ki-Ras was insensitive to the protein synthesis inhibitor, cycloheximide, and was occluded by the proteasomal inhibitor, MG-132. In addition, exposure to hydrogen peroxide reduced the levels of ubiquitinated Ras protein, indicating that oxidative stress leads to a reduced degradation of both isoforms through the ubiquitin/proteasome pathway. Indeed, the late reduction in Ha-Ras and Ki-Ras was due to a recovery of proteasomal degradation because it was sensitive to MG-132. The late reduction of Ha-Ras levels was abrogated by compound PD98059, which inhibits the MAP kinase pathway, whereas the late reduction of Ki-Ras was unaffected by PD98059. We conclude that oxidative stress differentially regulates the expression of Ha-Ras and Ki-Ras in cultured astrocytes, and that activation of the MAP kinase pathway by oxidative stress itself or by additional factors may act as a fail-safe mechanism limiting a sustained expression of the potentially detrimental Ha-Ras.

P120-GAP associated with syndecan-2 to function as an active switch signal for Src upon transformation with oncogenic ras

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Huang, J.-W.; Chen, C.-L.; Chuang, N.-N.

2005-01-01

BALB/3T3 cells transfected with plasmids pcDNA3.1-[S-ras(Q 61 K)] of shrimp Penaeus japonicus were applied to reveal a complex of p120-GAP/syndecan-2 being highly expressed upon transformation. Of interest, most of the p120-GAP/syndecan-2 complex was localized at caveolae, a membrane microdomain enriched with caveolin-1. To confirm the molecular interaction between syndecan-2 and p120-GAP, we further purified p120-GAP protein from mouse brains by using an affinity column of HiTrap-RACK1 and expressed mouse RACK1-encoded fusion protein and mouse syndecan-2-encoded fusion protein in bacteria. We report molecular affinities exist between p120-GAP and RACK1, syndecan-2 and RACK1 as well as p120-GAP and syndecan-2. The selective affinity between p120-GAP and syndecan-2 was found to be sufficient to detach RACK1. The p120-GAP/syndecan-2 complex was demonstrated to keep Src tyrosine kinase in an activated form. On the other hand, the syndecan-2/RACK1 complex was found to have Src in an inactivated form. These data indicate that the p120-GAP/syndecan-2 complex at caveolae could provide a docking site for Src to transmit tyrosine signaling, implying that syndecan-2/p120-GAP functions as a tumor promoter upon transformation with oncogenic ras of shrimp P. japonicus

MRAS: A Close but Understudied Member of the RAS Family.

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Young, Lucy C; Rodriguez-Viciana, Pablo

2018-01-08

MRAS is the closest relative to the classical RAS oncoproteins and shares most regulatory and effector interactions. However, it also has unique functions, including its ability to function as a phosphatase regulatory subunit when in complex with SHOC2 and protein phosphatase 1 (PP1). This phosphatase complex regulates a crucial step in the activation cycle of RAF kinases and provides a key coordinate input required for efficient ERK pathway activation and transformation by RAS. MRAS mutations rarely occur in cancer but deregulated expression may play a role in tumorigenesis in some settings. Activating mutations in MRAS (as well as SHOC2 and PP1) do occur in the RASopathy Noonan syndrome, underscoring a key role for MRAS within the RAS-ERK pathway. MRAS also has unique roles in cell migration and differentiation and has properties consistent with a key role in the regulation of cell polarity. Further investigations should shed light on what remains a relatively understudied RAS family member. Copyright © 2018 Cold Spring Harbor Laboratory Press; all rights reserved.

Zonation of heme synthesis enzymes in mouse liver and their regulation by β-catenin and Ha-ras.

Science.gov (United States)

Braeuning, Albert; Schwarz, Michael

2010-11-01

Cytochrome P450 (CYP) hemoproteins play an important role in hepatic biotransformation. Recently, β-catenin and Ha-ras signaling have been identified as players controlling transcription of various CYP genes in mouse liver. The aim of the present study was to analyze the role of β-catenin and Ha-ras in the regulation of heme synthesis. Heme synthesis-related gene expression was analyzed in normal liver, in transgenic mice expressing activated β-catenin or Ha-ras, and in hepatomas. Regulation of the aminolevulinate dehydratase promoter was studied in vitro. Elevated expression of mRNAs and proteins involved in heme biosynthesis was linked to β-catenin activation in perivenous hepatocytes, in transgenic hepatocytes, and in hepatocellular tumors. Stimulation of the aminolevulinate dehydratase promoter by β-catenin was independent of the β-catenin/T-cell-specific transcription factor dimer. By contrast, activation of Ha-ras repressed heme synthesis-related gene expression. The present data suggest that β-catenin enhances the expression of both CYPs and heme synthesis-related genes, thus coordinating the availability of CYP apoprotein and its prosthetic group heme. The reciprocal regulation of heme synthesis by β-catenin and Ha-ras-dependent signaling supports our previous hypothesis that antagonistic action of these pathways plays a major role in the control of zonal gene expression in healthy mouse liver and aberrant expression patterns in hepatocellular tumors.

The effect of aquaporin 5 overexpression on the Ras signaling pathway

International Nuclear Information System (INIS)

Woo, Janghee; Lee, Juna; Kim, Myoung Sook; Jang, Se Jin; Sidransky, David; Moon, Chulso

2008-01-01

Human aquaporin 5 (AQP5) has been shown to be overexpressed in multiple cancers, such as pancreatic cancer and colon cancer. Furthermore, it has been reported that ectopic expression of AQP5 leads to many phenotypic changes characteristic of transformation. However, the biochemical mechanism leading to transformation in AQP5-overexpressing cells has not been clearly elucidated. In this report, the overexpression of AQP5 in NIH3T3 cells demonstrated a significant effect on Ras activity and, thus, cell proliferation. Furthermore, this influence was shown to be mediated by phosphorylation of the PKA consensus site of AQP5. This is the first evidence demonstrating an association between AQP5 and a signaling pathway, namely the Ras signal transduction pathway, which may be the basis of the oncogenic properties seen in AQP-overexpressing cells

Distinct roles of the RasGAP family proteins in C. elegans associative learning and memory.

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Gyurkó, M Dávid; Csermely, Péter; Sőti, Csaba; Steták, Attila

2015-10-15

The Ras GTPase activating proteins (RasGAPs) are regulators of the conserved Ras/MAPK pathway. Various roles of some of the RasGAPs in learning and memory have been reported in different model systems, yet, there is no comprehensive study to characterize all gap genes in any organism. Here, using reverse genetics and neurobehavioural tests, we studied the role of all known genes of the rasgap family in C. elegans in associative learning and memory. We demonstrated that their proteins are implicated in different parts of the learning and memory processes. We show that gap-1 contribute redundantly with gap-3 to the chemosensation of volatile compounds, gap-1 plays a major role in associative learning, while gap-2 and gap-3 are predominantly required for short- and long-term associative memory. Our results also suggest that the C. elegans Ras orthologue let-60 is involved in multiple processes during learning and memory. Thus, we show that the different classes of RasGAP proteins are all involved in cognitive function and their complex interplay ensures the proper formation and storage of novel information in C. elegans.

Spectrum of K ras mutations in Pakistani colorectal cancer patients

International Nuclear Information System (INIS)

Murtaza, B.N.; Bibi, A.; Rashid, M.U.; Khan, Y.I.; Chaudri, M.S.; Shakoori, A.R.

2013-01-01

The incidence of colorectal cancer (CRC) is increasing daily worldwide. Although different aspects of CRC have been studied in other parts of the world, relatively little or almost no information is available in Pakistan about different aspects of this disease at the molecular level. The present study was aimed at determining the frequency and prevalence of K ras gene mutations in Pakistani CRC patients. Tissue and blood samples of 150 CRC patients (64% male and 36% female) were used for PCR amplification of K ras and detection of mutations by denaturing gradient gel electrophoresis, restriction fragment length polymorphism analysis, and nucleotide sequencing. The K ras mutation frequency was found to be 13%, and the most prevalent mutations were found at codons 12 and 13. A novel mutation was also found at codon 31. The dominant mutation observed was a G to A transition. Female patients were more susceptible to K ras mutations, and these mutations were predominant in patients with a nonmetastatic stage of CRC. No significant differences in the prevalence of K ras mutations were observed for patient age, gender, or tumor type. It can be inferred from this study that Pakistani CRC patients have a lower frequency of K ras mutations compared to those observed in other parts of the world, and that K ras mutations seemed to be significantly associated with female patients

Spectrum of K ras mutations in Pakistani colorectal cancer patients

Energy Technology Data Exchange (ETDEWEB)

Murtaza, B.N.; Bibi, A. [School of Biological Sciences, University of the Punjab, Quaid-i-Azam Campus, Lahore (Pakistan); Rashid, M.U.; Khan, Y.I. [Shaukat Khanum Memorial Cancer Hospital and Research Centre, Johar Town, Lahore (Pakistan); Chaudri, M.S. [Services Institute of Medical Sciences, Lahore (Pakistan); Shakoori, A.R. [School of Biological Sciences, University of the Punjab, Quaid-i-Azam Campus, Lahore (Pakistan)

2013-11-29

The incidence of colorectal cancer (CRC) is increasing daily worldwide. Although different aspects of CRC have been studied in other parts of the world, relatively little or almost no information is available in Pakistan about different aspects of this disease at the molecular level. The present study was aimed at determining the frequency and prevalence of K ras gene mutations in Pakistani CRC patients. Tissue and blood samples of 150 CRC patients (64% male and 36% female) were used for PCR amplification of K ras and detection of mutations by denaturing gradient gel electrophoresis, restriction fragment length polymorphism analysis, and nucleotide sequencing. The K ras mutation frequency was found to be 13%, and the most prevalent mutations were found at codons 12 and 13. A novel mutation was also found at codon 31. The dominant mutation observed was a G to A transition. Female patients were more susceptible to K ras mutations, and these mutations were predominant in patients with a nonmetastatic stage of CRC. No significant differences in the prevalence of K ras mutations were observed for patient age, gender, or tumor type. It can be inferred from this study that Pakistani CRC patients have a lower frequency of K ras mutations compared to those observed in other parts of the world, and that K ras mutations seemed to be significantly associated with female patients.

Specific regulation of point-mutated K-ras-immortalized cell proliferation by a photodynamic antisense strategy.

Science.gov (United States)

Higuchi, Maiko; Yamayoshi, Asako; Kato, Kiyoko; Kobori, Akio; Wake, Norio; Murakami, Akira

2010-02-01

It has been reported that point mutations in genes are responsible for various cancers, and the selective regulation of gene expression is an important factor in developing new types of anticancer drugs. To develop effective drugs for the regulation of point-mutated genes, we focused on photoreactive antisense oligonucleotides. Previously, we reported that photoreactive oligonucleotides containing 2'-O-psoralenylmethoxyethyl adenosine (2'-Ps-eom) showed drastic photoreactivity in a strictly sequence-specific manner. Here, we demonstrated the specific gene regulatory effects of 2'-Ps-eom on [(12)Val]K-ras mutant (GGT --> GTT). Photo-cross-linking between target mRNAs and 2'-Ps-eom was sequence-specific, and the effect was UVA irradiation-dependent. Furthermore, 2'-Ps-eom was able to inhibit K-ras-immortalized cell proliferation (K12V) but not Vco cells that have the wild-type K-ras gene. These results suggest that the 2'-Ps-eom will be a powerful nucleic acid drug to inhibit the expression of disease-causing point mutation genes, and has great therapeutic potential in the treatment of cancer.

RAS Insight

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David Heimbrook, now CEO of the Frederick National Laboratory for Cancer Research, played a major role in a large pharma as it tried to develop an anti-RAS drug. Lessons from that failure inform the RAS Initiative today.

Genetic and Molecular Analysis of Suppressors of Ras Mutations

National Research Council Canada - National Science Library

Sieburth, Derek

1998-01-01

.... elegans vulval development. We describe the identification and characterization of a novel gene, sur-8, that functions to regulate a receptor tyrosine kinase-Ras-MAP kinase-mediated signal transduction pathway during C...

Ras1 interacts with multiple new signaling and cytoskeletal loci in Drosophila eggshell patterning and morphogenesis.

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Schnorr, J D; Holdcraft, R; Chevalier, B; Berg, C A

2001-10-01

Little is known about the genes that interact with Ras signaling pathways to regulate morphogenesis. The synthesis of dorsal eggshell structures in Drosophila melanogaster requires multiple rounds of Ras signaling followed by dramatic epithelial sheet movements. We took advantage of this process to identify genes that link patterning and morphogenesis; we screened lethal mutations on the second chromosome for those that could enhance a weak Ras1 eggshell phenotype. Of 1618 lethal P-element mutations tested, 13 showed significant enhancement, resulting in forked and fused dorsal appendages. Our genetic and molecular analyses together with information from the Berkeley Drosophila Genome Project reveal that 11 of these lines carry mutations in previously characterized genes. Three mutations disrupt the known Ras1 cell signaling components Star, Egfr, and Blistered, while one mutation disrupts Sec61beta, implicated in ligand secretion. Seven lines represent cell signaling and cytoskeletal components that are new to the Ras1 pathway; these are Chickadee (Profilin), Tec29, Dreadlocks, POSH, Peanut, Smt3, and MESK2, a suppressor of dominant-negative Ksr. A twelfth insertion disrupts two genes, Nrk, a "neurospecific" receptor tyrosine kinase, and Tpp, which encodes a neuropeptidase. These results suggest that Ras1 signaling during oogenesis involves novel components that may be intimately associated with additional signaling processes and with the reorganization of the cytoskeleton. To determine whether these Ras1 Enhancers function upstream or downstream of the Egf receptor, four mutations were tested for their ability to suppress an activated Egfr construct (lambdatop) expressed in oogenesis exclusively in the follicle cells. Mutations in Star and l(2)43Bb had no significant effect upon the lambdatop eggshell defect whereas smt3 and dock alleles significantly suppressed the lambdatop phenotype.

Genetic and Molecular Analysis of Suppressors of Ras Mutations

National Research Council Canada - National Science Library

Sieburth, Derek

1999-01-01

.... elegans vulvaZ development. We describe the identification and characterization of a novel gene, sur-8, that functions to regulate a receptor tyrosine kinase-Ras-MAp kinase- mediated signal transduction pathway during C...

Mice lacking Ras-GRF1 show contextual fear conditioning but not spatial memory impairments: convergent evidence from two independently generated mouse mutant lines

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Raffaele ed'Isa

2011-12-01

Full Text Available Ras-GRF1 is a neuronal specific guanine exchange factor that, once activated by both ionotropic and metabotropic neurotransmitter receptors, can stimulate Ras proteins, leading to long-term phosphorylation of downstream signaling. The two available reports on the behavior of two independently generated Ras-GRF1 deficient mouse lines provide contrasting evidence on the role of Ras-GRF1 in spatial memory and contextual fear conditioning. These discrepancies may be due to the distinct alterations introduced in the mouse genome by gene targeting in the two lines that could differentially affect expression of nearby genes located in the imprinted region containing the Ras-grf1 locus. In order to determine the real contribution of Ras-GRF1 to spatial memory we compared in Morris Water Maze learning the Brambilla’s mice with a third mouse line (GENA53 in which a nonsense mutation was introduced in the Ras-GRF1 coding region without additional changes in the genome and we found that memory in this task is normal. Also, we measured both contextual and cued fear conditioning, which were previously reported to be affected in the Brambilla’s mice, and we confirmed that contextual learning but not cued conditioning is impaired in both mouse lines. In addition, we also tested both lines for the first time in conditioned place aversion in the Intellicage, an ecological and remotely controlled behavioral test, and we observed normal learning. Finally, based on previous reports of other mutant lines suggesting that Ras-GRF1 may control body weight, we also measured this non-cognitive phenotype and we confirmed that both Ras-GRF1 deficient mutants are smaller than their control littermates. In conclusion, we demonstrate that Ras-GRF1 has no unique role in spatial memory while its function in contextual fear conditioning is likely to be due not only to its involvement in amygdalar functions but possibly to some distinct hippocampal connections specific to

Regulation of Ras exchange factors and cellular localization of Ras activation by lipid messengers in T cells

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Jesse E. Jun

2013-09-01

Full Text Available The Ras-MAPK signaling pathway is highly conserved throughout evolution and is activated downstream of a wide range of receptor stimuli. Ras guanine nucleotide exchange factors (RasGEFs catalyze GTP loading of Ras and play a pivotal role in regulating receptor-ligand induced Ras activity. In T cells, three families of functionally important RasGEFs are expressed: RasGRF, RasGRP, and SOS-family GEFs.Early on it was recognized that Ras activation is critical for T cell development and that the RasGEFs play an important role herein. More recent work has revealed that nuances in Ras activation appear to significantly impact T cell development and selection. These nuances include distinct biochemical patterns of analog versus digital Ras activation, differences in cellular localization of Ras activation, and intricate interplays between the RasGEFs during distinct T cell developmental stages as revealed by various new mouse models. In many instances, the exact nature of these nuances in Ras activation or how these may result from fine-tuning of the RasGEFs is not understood.One large group of biomolecules critically involved in the control of Ras-GEFs´functions are lipid second messengers. Multiple, yet distinct lipid products are generated following T cell receptor (TCR stimulation and bind to different domains in the RasGRP and SOS RasGEFs to facilitate the activation of the membrane-anchored Ras GTPases. In this review we highlight how different lipid-based elements are generated by various enzymes downstream of the TCR and other receptors and how these dynamic and interrelated lipid products may fine-tune Ras activation by RasGEFs in developing T cells.

Codon 61 mutations in the c-Harvey-ras gene in mouse skin tumors induced by 7,12-dimethylbenz[a]anthracene plus okadaic acid class tumor promoters.

Science.gov (United States)

Fujiki, H; Suganuma, M; Yoshizawa, S; Kanazawa, H; Sugimura, T; Manam, S; Kahn, S M; Jiang, W; Hoshina, S; Weinstein, I B

1989-01-01

Three okadaic acid class tumor promoters, okadaic acid, dinophysistoxin-1, and calyculin A, have potent tumor-promoting activity in two-stage carcinogenesis experiments on mouse skin. DNA isolated from tumors induced by 7,12-dimethylbenz[a]anthracene (DMBA) and each of these tumor promoters revealed the same mutation at the second nucleotide of codon 61 (CAA----CTA) in the c-Ha-ras gene, determined by the polymerase chain reaction procedure and DNA sequencing. Three potent 12-O-tetradecanoylphorbol-13-acetate (TPA)-type tumor promoters, TPA, teleocidin, and aplysiatoxin, showed the same effects. These results provide strong evidence that this mutation in the c-Ha-ras gene is due to a direct effect of DMBA rather than a selective effect of specific tumor promoters.

Evolutionarily conserved regions of the human c-myc protein can be uncoupled from transforming activity

International Nuclear Information System (INIS)

Sarid, J.; Halazonetis, T.D.; Murphy, W.; Leder, P.

1987-01-01

The myc family of oncogenes contains coding sequences that have been preserved in different species for over 400 million years. This conservation (which implies functional selection) is broadly represented throughout the C-terminal portion of the human c-myc protein but is largely restricted to three cluster of amino acid sequences in the N-terminal region. The authors have examined the role that the latter three regions of the c-myc protein might play in the transforming function of the c-myc gene. Several mutations, deletions and frameshifts, were introduced into the c-myc gene, and these mutant genes were tested for their ability to collaborate with the EJ-ras oncogene to transform rat embryo fibroblasts. Complete elimination of the first two N-terminal conserved segments abolished transforming activity. In contrast, genes altered in a portion of the second or the entire third conserved segment retained their transforming activity. Thus, the latter two segments are not required for the transformation process, suggesting that they serve another function related only to the normal expression of the c-myc gene

Small GTPase R-Ras participates in neural tube formation in zebrafish embryonic spinal cord.

Science.gov (United States)

Ohata, Shinya; Uga, Hideko; Okamoto, Hitoshi; Katada, Toshiaki

2018-06-27

Ras related (R-Ras), a small GTPase, is involved in the maintenance of apico-basal polarity in neuroepithelial cells of the zebrafish hindbrain, axonal collapse in cultured murine hippocampal neurons, and maturation of blood vessels in adult mice. However, the role of R-Ras in neural tube formation remains unknown. Using antisense morpholino oligonucleotides (AMOs), we found that in the spinal cord of zebrafish embryos, the lumen was formed bilaterally in rras morphants, whereas it was formed at the midline in control embryos. As AMO can cause off-target effects, we generated rras mutant zebrafish lines using CRISPR/Cas9 technology. Although these rras mutant embryos did not have a bilateral lumen in the spinal cord, the following findings suggest that the phenotype is unlikely due to an off-target effect of rras AMO: 1) The rras morphant phenotype was rescued by an injection of AMO-resistant rras mRNA, and 2) a bilaterally segregated spinal cord was not observed in rras mutant embryos injected with rras AMO. The results suggest that the function of other ras family genes may be redundant in rras mutants. Previous research reported a bilaterally formed lumen in the spinal cord of zebrafish embryos with a mutation in a planar cell polarity (PCP) gene, van gogh-like 2 (vangl2). In the present study, in cultured cells, R-Ras was co-immunoprecipitated with Vangl2 but not with another PCP regulator, Pricke1. Interestingly, the interaction between R-Ras and Vangl2 was stronger in guanine-nucleotide free point mutants of R-Ras than in wild-type or constitutively active (GTP-bound) forms of R-Ras. R-Ras may regulate neural tube formation in cooperation with Vangl2 in the developing zebrafish spinal cord. Copyright © 2018 Elsevier Inc. All rights reserved.

The Frequency and Type of K-RAS Mutations in Mexican Patients With Colorectal Cancer: A National Study.

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Cárdenas-Ramos, Susana G; Alcázar-González, Gregorio; Reyes-Cortés, Luisa M; Torres-Grimaldo, Abdiel A; Calderón-Garcidueñas, Ana L; Morales-Casas, José; Flores-Sánchez, Patricia; De León-Escobedo, Raúl; Gómez-Díaz, Antonio; Moreno-Bringas, Carmen; Sánchez-Guillén, Jorge; Ramos-Salazar, Pedro; González-de León, César; Barrera-Saldaña, Hugo A

2017-06-01

Current metastatic colorectal cancer (mCRC) therapy uses monoclonal antibodies against the epidermal growth factor receptor. This treatment is only useful in the absence of K-RAS gene mutations; therefore the study of such mutations is part of a personalized treatment. The aim of this work is to determine the frequency and type of the most common K-RAS mutations in Mexican patients with metastatic disease by nucleotide sequencing. We studied 888 patients with mCRC from different regions of Mexico. The presence of mutations in exon 2, codons 12 and 13, of the K-RAS gene was determined by nucleotide sequencing. Patients exhibited K-RAS gene mutations in 35% (310/888) of cases. Mutation frequency of codons 12 and 13 was 71% (221/310) and 29% (89/310), respectively. The most common mutation (45.7%) in codon 12 was c.35G>A (p.G12D), whereas the one in codon 13 was c.38G>A (p.G13D) (78.7%). Given the frequency of K-RAS mutations in Mexicans, making a genetic study before deciding to treat mCRC patients with monoclonal antibodies is indispensable.

Expression of proto-oncogenes in non-Hodgkin's lymphomas by in situ hybridization with biotinylated DNA probes

International Nuclear Information System (INIS)

Hamatani, Kiyohiro; Yoshida, Kuniko; Abe, Masumi; Shimaoka, Katsutaro; Shiku, Hiroshi; Akiyama, Mitoshi; Kondo, Hisayoshi.

1989-11-01

Expression of six proto-oncogenes (fos, myc, myb, Ki-ras, Ha-ras, and N-ras) in 43 cases of non-Hodgkin's lymphoma was analyzed by means of in situ hybridization. Biotinylated DNA probes of the six oncogenes and those of the immunoglobulin H-chain (IgH) gene and the T cell receptor β-chain (TCRβ) gene were used. The results of in situ hybridization performed under blind conditions by IgH and TCRβ gene probes were compatible with those of typing by cell surface markers. The nuclear protein-related proto-oncogenes, fos myc, and myb, were expressed in about 70 % - 80 % of all cases regardless of phenotypes, histology or histologic grade. On the contrary, genes of the ras family were expressed in fewer cases except for the Ki-ras gene which was more frequently expressed by cases of the T cell immunophenotype with a high malignancy grade. The results of dot hybridization with RNA extracted from some cases were compatible with those of in situ hybridization, further demonstrating the specificity of in situ hybridization. (author)

The Prognostic Impact of K-RAS Mutations in Adult Acute Myeloid Leukemia Patients Treated with High Dose Cytarabine

International Nuclear Information System (INIS)

Ahmad, E.I.; Gawish, H.H.; Al-Azizi, N.M.A.; El-Hefni, A.M.

2009-01-01

Activating point mutation of the RAS gene has been generally accepted as an oncogenic event in a variety of malignancies. It represents one of the most common genetic alterations in acute myeloid leukemia (AML). However there is still controversy about its clinical relevance on the treatment outcome of this leukemia. Objective: This study aimed to clarify the biologic and prognostic impact of K-RAS mutations in relation to the dose of cytarabine (ara-C) used in post induction consolidation chemotherapy in adult AML patients. Patients and Methods: The study comprised 71de novo AML patients with a male: Female ratio of 1.4: 1; their ages ranged from 21-59 years with a median of 37 years. They were subjected to full clinical evaluation, routine laboratory investigations, cytogenetic studies by G banding and K-RAS mutation detection using realtime PCR. The patients were randomized into 2 groups (gps) according to the ara-C dose used in consolidation treatment, HDAC gp receiving 400 mg ara-C and LDAC gp receiving 100 mg ara-C. They were followed over a period of 5 years. Results: Mutations in the K-RAS gene (mutRAS) were detected in 23 patients (32%) with the remaining 48 patients (68%) having wild type RAS (wtRAS). Blast cell percentage was significantly lower in mutRAS compared to wtRAS patients (p=<0.001). The M4 subtype of AML and cases with Inv 16 showed significantly higher frequencies in mutRAS compared to wtRAS patients, (p=0.015, 0.003, respectively). The patients were followed up for a median of 43 months (range 11-57 months). There was no significant difference in overall survival (OS) between mutRAS and wtRAS patients (p=0.326). Within the mutRAS patients treated with HDAC, cumulative OS was significantly higher than those treated with LDAC (p=0.001). This was not the case in the wtRAS group (p=0.285). There was no significant difference in disease The Prognostic Impact of K-RAS Mutations in Adult Acute Myeloid Leukemia Patients Treated with High Dose

A Drosophila immune response against Ras-induced overgrowth

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Thomas Hauling

2014-03-01

Full Text Available Our goal is to characterize the innate immune response against the early stage of tumor development. For this, animal models where genetic changes in specific cells and tissues can be performed in a controlled way have become increasingly important, including the fruitfly Drosophila melanogaster. Many tumor mutants in Drosophila affect the germline and, as a consequence, also the immune system itself, making it difficult to ascribe their phenotype to a specific tissue. Only during the past decade, mutations have been induced systematically in somatic cells to study the control of tumorous growth by neighboring cells and by immune cells. Here we show that upon ectopic expression of a dominant-active form of the Ras oncogene (RasV12, both imaginal discs and salivary glands are affected. Particularly, the glands increase in size, express metalloproteinases and display apoptotic markers. This leads to a strong cellular response, which has many hallmarks of the granuloma-like encapsulation reaction, usually mounted by the insect against larger foreign objects. RNA sequencing of the fat body reveals a characteristic humoral immune response. In addition we also identify genes that are specifically induced upon expression of RasV12. As a proof-of-principle, we show that one of the induced genes (santa-maria, which encodes a scavenger receptor, modulates damage to the salivary glands. The list of genes we have identified provides a rich source for further functional characterization. Our hope is that this will lead to a better understanding of the earliest stage of innate immune responses against tumors with implications for mammalian immunity.

Evidence implicating the Ras pathway in multiple CD28 costimulatory functions in CD4+ T cells.

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Sujit V Janardhan

Full Text Available CD28 costimulation is a critical event in the full activation of CD4(+ T cells that augments cytokine gene transcription, promotes cytokine mRNA stability, prevents induction of anergy, increases cellular metabolism, and increases cell survival. However, despite extensive biochemical analysis of the signaling events downstream of CD28, molecular pathways sufficient to functionally replace the diverse aspects of CD28-mediated costimulation in normal T cells have not been identified. Ras/MAPK signaling is a critical pathway downstream of T cell receptor stimulation, but its role in CD28-mediated costimulation has been controversial. We observed that physiologic CD28 costimulation caused a relocalization of the RasGEF RasGRP to the T cell-APC interface by confocal microscopy. In whole cell biochemical analysis, CD28 cross-linking with either anti-CD28 antibody or B7.1-Ig augmented TCR-induced Ras activation. To determine whether Ras signaling was sufficient to functionally mimic CD28 costimulation, we utilized an adenoviral vector encoding constitutively active H-Ras (61L to transduce normal, Coxsackie-Adenovirus Receptor (CAR transgenic CD4(+ T cells. Like costimulation via CD28, active Ras induced AKT, JNK and ERK phosphorylation. In addition, constitutive Ras signaling mimicked the ability of CD28 to costimulate IL-2 protein secretion, prevent anergy induction, increase glucose uptake, and promote cell survival. Importantly, we also found that active Ras mimicked the mechanism by which CD28 costimulates IL-2 production: by increasing IL-2 gene transcription, and promoting IL-2 mRNA stability. Finally, active Ras was able to induce IL-2 production when combined with ionomycin stimulation in a MEK-1-dependent fashion. Our results are consistent with a central role for Ras signaling in CD28-mediated costimulation.

RAS - Target Identification - Informatics

Science.gov (United States)

The RAS Informatics lab group develops tools to track and analyze “big data” from the RAS Initiative, as well as analyzes data from external projects. By integrating internal and external data, this group helps improve understanding of RAS-driven cancers.

The radiosensitivity of human keratinocytes: influence of activated c-H-ras oncogene expression and tumorigenicity

International Nuclear Information System (INIS)

Mendonca, M.S.; Redpath, J.L.; Stanbridge, E.J.

1991-01-01

The authors investigated γ-ray sensitivity of several activated c-H-ras (EJ) containing clones established after transfection of the spontaneously immortalized non-tumorigenic human keratinocyte cell line HaCaT. The clones were grouped according to tumorigenic potential after subcutaneous injection into nude mice, and fell into three classes: Class I clones A-4 and I-6 are non-tumorigenic and express very low levels of c-H-ras mRNA and no mutated ras protein (p 21 ); Class II clones I-5 and I-7 grow to large (benign) epidermal cysts, express intermediate to high c-H-ras mRNA and variable levels of mutated ras p 21 protein with clone I-5 expressing little and clone I-7 expressing high levels of p 21 ; Class III clones II-3 and II-4 grow to solid squamous cell carcinomas, express high c-H-ras mRNA and high level of mutated p 21 ras protein similar to clone I-7. Comparison of single-hit multitarget or linear-quadratic survival curve parameters, and survival at 2Gy (S 2 ) indicate no general correlation with either activated c-H-ras expression level or tumorigenic potential, and increased radioresistance. (author)

Inhibitors of Ras-SOS Interactions.

Science.gov (United States)

Lu, Shaoyong; Jang, Hyunbum; Zhang, Jian; Nussinov, Ruth

2016-04-19

Activating Ras mutations are found in about 30 % of human cancers. Ras activation is regulated by guanine nucleotide exchange factors, such as the son of sevenless (SOS), which form protein-protein interactions (PPIs) with Ras and catalyze the exchange of GDP by GTP. This is the rate-limiting step in Ras activation. However, Ras surfaces lack any evident suitable pockets where a molecule might bind tightly, rendering Ras proteins still 'undruggable' for over 30 years. Among the alternative approaches is the design of inhibitors that target the Ras-SOS PPI interface, a strategy that is gaining increasing recognition for treating Ras mutant cancers. Herein we focus on data that has accumulated over the past few years pertaining to the design of small-molecule modulators or peptide mimetics aimed at the interface of the Ras-SOS PPI. We emphasize, however, that even if such Ras-SOS therapeutics are potent, drug resistance may emerge. To counteract this development, we propose "pathway drug cocktails", that is, drug combinations aimed at parallel (or compensatory) pathways. A repertoire of classified cancer, cell/tissue, and pathway/protein combinations would be beneficial toward this goal. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Differential gene expression and clonal selection during cellular transformation induced by adhesion deprivation

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Kumar Mahesh J

2010-12-01

Full Text Available Abstract Background Anchorage independent growth is an important hallmark of oncogenic transformation. Previous studies have shown that when adhesion dependent fibroblasts were prevented from adhering to a substrate they underwent anoikis. In the present study we have demonstrated how anoikis resistant cells gain the transformation related properties with sequential selection of genes. We have proposed this process as a model system for selection of transformed cells from normal cells. Results This report demonstrates that some fibroblasts can survive during late stages of anoikis, at which time they exhibit transformation-associated properties such as in vitro colony formation in soft agar and in vivo subcutaneous tumour formation in nude mice. Cytogenetic characterisation of these cells revealed that they contained a t (2; 2 derivative chromosome and they have a selective survival advantage in non adherent conditions. Gene expression profile indicated that these cells over expressed genes related to hypoxia, glycolysis and tumor suppression/metastasis which could be helpful in their retaining a transformed phenotype. Conclusion Our results reveal some new links between anoikis and cell transformation and they provide a reproducible model system which can potentially be useful to study multistage cancer and to identify new targets for drug development.

RAS Initiative - Events

Science.gov (United States)

The NCI RAS Initiative has organized multiple events with outside experts to discuss how the latest scientific and technological breakthroughs can be applied to discover vulnerabilities in RAS-driven cancers.

Safe use of NSAIDs and RAS-inhibitors at Agogo Presbyterian Hospital, Ghana

NARCIS (Netherlands)

Meulendijks, L.G.; Adomako, E.A.; Appiah, E.B.; Kramers, C.

2016-01-01

BACKGROUND: Preventable adverse events of medication are an important cause of hospital admissions in the developed world, in which non-steroidal anti-inflammatory drugs (NSAIDs) and renin-angiotensin system (RAS-) inhibitors are frequently involved. NSAIDs and RAS-inhibitors are also often used in

Cyclic AMP signalling in Dictyostelium : G-proteins activate separate Ras pathways using specific RasGEFs

NARCIS (Netherlands)

Kae, Helmut; Kortholt, Arjan; Rehmann, Holger; Insall, RobertH.; Van Haastert, Peter J. M.; Spiegelman, George B.; Weeks, Gerald

In general, mammalian Ras guanine nucleotide exchange factors (RasGEFs) show little substrate specificity, although they are often thought to regulate specific pathways. Here, we provide in vitro and in vivo evidence that two RasGEFs can each act on specific Ras proteins. During Dictyostelium

Identification of H-Ras-Specific Motif for the Activation of Invasive Signaling Program in Human Breast Epithelial Cells

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Hae-Young Yong

2011-02-01

Full Text Available Increased expression and/or activation of H-Ras are often associated with tumor aggressiveness in breast cancer. Previously, we showed that H-Ras, but not N-Ras, induces MCF10A human breast epithelial cell invasion and migration, whereas both H-Ras and N-Ras induce cell proliferation and phenotypic transformation. In an attempt to determine the sequence requirement directing the divergent phenotype induced by H-Ras and N-Ras with a focus on the induction of human breast cell invasion, we investigated the structural and functional relationships between H-Ras and N-Ras using domain-swap and site-directed mutagenesis approaches. Here, we report that the hypervariable region (HVR, consisting of amino acids 166 to 189 in H-Ras, determines the invasive/migratory signaling program as shown by the exchange of invasive phenotype by swapping HVR sequences between H-Ras and N-Ras. We also demonstrate that the H-Ras-specific additional palmitoylation site at Cys184 is not responsible for the signaling events that distinguish between H-Ras and N-Ras. Importantly, this work identifies the C-terminal HVR, especially the flexible linker domain with two consecutive proline residues Pro173 and Pro174, as a critical domain that contributes to activation of H-Ras and its invasive potential in human breast epithelial cells. The present study sheds light on the structural basis for the Ras isoform-specific invasive program of breast epithelial cells, providing information for the development of agents that specifically target invasion-related H-Ras pathways in human cancer.

RAS/ERK modulates TGFbeta-regulated PTEN expression in human pancreatic adenocarcinoma cells.

Science.gov (United States)

Chow, Jimmy Y C; Quach, Khai T; Cabrera, Betty L; Cabral, Jennifer A; Beck, Stayce E; Carethers, John M

2007-11-01

Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is rarely mutated in pancreatic cancers, but its regulation by transforming growth factor (TGF)-beta might mediate growth suppression and other oncogenic actions. Here, we examined the role of TGFbeta and the effects of oncogenic K-RAS/ERK upon PTEN expression in the absence of SMAD4. We utilized two SMAD4-null pancreatic cell lines, CAPAN-1 (K-RAS mutant) and BxPc-3 (WT-K-RAS), both of which express TGFbeta surface receptors. Cells were treated with TGFbeta1 and separated into cytosolic/nuclear fractions for western blotting with phospho-SMAD2, SMAD 2, 4 phospho-ATP-dependent tyrosine kinases (Akt), Akt and PTEN antibodies. PTEN mRNA levels were assessed by reverse transcriptase-polymerase chain reaction. The MEK1 inhibitor, PD98059, was used to block the downstream action of oncogenic K-RAS/ERK, as was a dominant-negative (DN) K-RAS construct. TGFbeta increased phospho-SMAD2 in both cytosolic and nuclear fractions. PD98059 treatment further increased phospho-SMAD2 in the nucleus of both pancreatic cell lines, and DN-K-RAS further improved SMAD translocation in K-RAS mutant CAPAN cells. TGFbeta treatment significantly suppressed PTEN protein levels concomitant with activation of Akt by 48 h through transcriptional reduction of PTEN mRNA that was evident by 6 h. TGFbeta-induced PTEN suppression was reversed by PD98059 and DN-K-RAS compared with treatments without TGFbeta. TGFbeta-induced PTEN expression was inversely related to cellular proliferation. Thus, oncogenic K-RAS/ERK in pancreatic adenocarcinoma facilitates TGFbeta-induced transcriptional down-regulation of the tumor suppressor PTEN in a SMAD4-independent manner and could constitute a signaling switch mechanism from growth suppression to growth promotion in pancreatic cancers.

Analysis of the K-ras and p53 pathways in x-ray-induced lung tumors in the rat

Energy Technology Data Exchange (ETDEWEB)

Belinsky, S.A.; Middleton, S.K.; Hahn, F.F.; Nikula, K.J. [Inhalation Toxicology Research Inst., Albuquerque, NM (United States); Picksley, S.M. [Medical Sciences Inst., Dundee (United Kingdom)

1996-04-01

The risk from exposure to low-dose radiation in conjunction with cigarette smoking has not been estimated due in part to lmited knowledge surrounding the molecular mechanisms underlying radiation-induced cancers. The purpose of this investigation was to determine the frequency for alterations in genes within the K-ras and p53 signal and cell cycle regulatory pathways, respectively, in X-ray-induced lung tumors in the F344/N rat. These tumors were examined for genetic alterations in the K-ras, c-raf-1, p53, mdm2 and cip1 genes. No K-ras mutations were detected by sequencing in 18 squamous cell carcinomas (SCCs) or 17 adenocarcinomas. However, using a K-ras codon 12 mutation selection assay, a codon 12 GGT {r_arrow} GAT mutation was detected in one SCC, suggesting that activation of the K-ras proto-oncogene is both a rare and late event. Single-strand conformation polymorphism (SSCP) analysis of the kinase-binding domain of the c-raf-1 gene did not detect any polymorphisms. Three of 18 SCCs but none of the adenocarcinomas showed p53 nuclear immunoreactivity. Single-strand conformation polymorphism analysis of exons 4-9 of the p53 gene detected only an exon 9 mutation in one SCC. Mutations were not detected in the three SCCs with immunoreactive p53 protein. No amplification of the mdm2 gene was detected; however, nuclear mdm2 immunoreactivity was present in one of the three SCCs that stained positive for the p53 protein. The complete cDNA of the rat cip1 gene comprising 810 bases was cloned and sequenced. The frequency of somatic mutations in exon 2 of the cip1 gene was determined by SSCP analysis. No alterations in electrophoretic mobility were detected. The results of this investigation indicate that alterations in the K-ras and p53 pathways do not play a major role in the genesis of X-ray-induced lung tumors in the rat. 49 refs., 5 figs.

p21-ras effector domain mutants constructed by "cassette" mutagenesis

DEFF Research Database (Denmark)

Stone, J C; Vass, W C; Willumsen, B M

1988-01-01

A series of mutations encoding single-amino-acid substitutions within the v-rasH effector domain were constructed, and the ability of the mutants to induce focal transformation of NIH 3T3 cells was studied. The mutations, which spanned codons 32 to 40, were made by a "cassette" mutagenesis...

c-Ha-ras BamHI RFLP in human urothelial tumors and point mutations in hot codons

International Nuclear Information System (INIS)

Weismanova, E; Skovraga, M.; Kaluz, S.

1993-01-01

High-molecular weights DNAs from 30 bladder and renal cell carcinomas (RCC) were isolated and the c-Ha-ras the c-Ha-ras gene BamHI RFLP was examined. Amplification of c-Ha-ras with normal localization with regard to the size of alleles was found only in the case. One of the normally localized c-Ha-ras allele termed RCC c-H-ras of a length of about 6.6 kbp was cloned and an oncogene-activating point mutation was identified using two restriction enzymes. After comparison of CfrI and Cfr10I cleavage maps of RCC c-Ha-ras to complete nucleotide sequences of EJ/T24 c-Ha-ras oncogene and its normal counterpart, a point mutation was identified within codon 11 or 12. The use of CfrI and Cfr10I is of value for clinical practice in identification of point mutations in c-Ha-ras PCR product in neoplasia accompanied by somatic mutation of c-Ha-ras. The correlation among c-Ha-ras allele, amplification/loss, presence of point mutation and progression of neoplasia is discussed. (author)

Biological Effects of Potato Plants Transformation with Glucose Oxidase Gene and their Resistance to Hyperthermia

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O.I. Grabelnych

2017-02-01

Full Text Available It is known that regulation of plant tolerance to adverse environmental factors is connected with short term increase of the concentration of endogenous reactive oxygen species (ROS, which are signalling molecules for the induction of protective mechanisms. Introduction and expression of heterologous gox gene, which encodes glucose oxidase enzyme in plant genome, induce constantly higher content of hydrogen peroxide in plant tissues. It is not known how the introduction of native or modified gox gene affects the plant resistance to high-temperature stress, one of the most commonly used model for the study of stress response and thermal tolerance. In this study, we investigated biological effects of transformation and evaluated the resistance to temperature stress of potato plants with altered levels of glucose oxidase expression. Transformation of potato plants by gox gene led to the more early coming out from tuber dormancy of transformed plants and slower growth rate. Transformants containing the glucose oxidase gene were more sensitive to lethal thermal shock (50 °C, 90 min than the transformant with the empty vector (pBI or untransformed plants (CK. Pre-heating of plants at 37 °C significantly weakened the damaging effect of lethal thermal shock. This attenuation was more significant in the non-transformed plants.

Fetisisme Ras Kaukasoid dan Ras Mongoloid Sebagai Strategi Pemasaran dalam Sinetron Indonesia

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Dimas Yudhistira

2014-12-01

ABSTRAK   Budaya populer yang tumbuh seiring dengan industrialisasi memengaruhi produksi per- filman di Indonesia. Salah satu genre perfilman di Indonesia adalah sinetron. Sinetron yang di- kategorikan sebagai produk seni kitsch memiliki dua kriteria yaitu sebagai komoditi seni yang populer dan sebagai komoditi dagang yang menghasilkan keuntungan ekonomis. Sebagai se- buah produk seni kitsch yang merupakan dasar pembuatan karyanya adalah selera masyarakat kebanyakan maka sinetron harus jeli dalam melihat keadaan dan latar belakang masyarakat. Penelitian ini menggunakan metode kualitatif. Hasil penelitian ini menggambarkan masyara- kat Indonesia yang merupakan ras Melayu telah dijajah oleh ras Kaukasoid dan Mongoloid sebelum tahun 1945 dan setelahnya. Efek dari penjajahan ini adalah ras Melayu telah ditanami fantasi yang menjadi stereotip mengenai ras Kaukasoid dan Mongoloid yang berakhir dengan fetisisme. Fetisisme ini dijadikan sebagai strategi pemasaran oleh produser dan sutradara un- tuk menarik antusiasme calon penonton sinetron. Caranya dengan menampilkan aktor dan aktris Melayu keturunan Kaukasoid dan Mongoloid sebagai pemeran utama.   Kata kunci: sinetron, seni kitsch, ras, fetisisme

Machine Learning Detects Pan-cancer Ras Pathway Activation in The Cancer Genome Atlas

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Gregory P. Way

2018-04-01

Full Text Available Summary: Precision oncology uses genomic evidence to match patients with treatment but often fails to identify all patients who may respond. The transcriptome of these “hidden responders” may reveal responsive molecular states. We describe and evaluate a machine-learning approach to classify aberrant pathway activity in tumors, which may aid in hidden responder identification. The algorithm integrates RNA-seq, copy number, and mutations from 33 different cancer types across The Cancer Genome Atlas (TCGA PanCanAtlas project to predict aberrant molecular states in tumors. Applied to the Ras pathway, the method detects Ras activation across cancer types and identifies phenocopying variants. The model, trained on human tumors, can predict response to MEK inhibitors in wild-type Ras cell lines. We also present data that suggest that multiple hits in the Ras pathway confer increased Ras activity. The transcriptome is underused in precision oncology and, combined with machine learning, can aid in the identification of hidden responders. : Way et al. develop a machine-learning approach using PanCanAtlas data to detect Ras activation in cancer. Integrating mutation, copy number, and expression data, the authors show that their method detects Ras-activating variants in tumors and sensitivity to MEK inhibitors in cell lines. Keywords: Gene expression, machine learning, Ras, NF1, KRAS, NRAS, HRAS, pan-cancer, TCGA, drug sensitivity

ATF1 and RAS in exosomes are potential clinical diagnostic markers for cervical cancer.

Science.gov (United States)

Shi, Yanhua; Wang, Wei; Yang, Baozhi; Tian, Hongge

2017-10-01

Cervical cancer is one of the most common cancers among women worldwide. It is highly lethal yet can be treated when found in early stage. Thus, early detection is of significant important for early diagnosis of cervical cancer. Exosomes have been used as biomarkers in clinical diagnosis. It is unknown that whether blood exosomes associated with cervical cancer can be detected and if these exosomes can accurately represent the developmental stage of cervical cancer. Mouse models were made out of a relapsed cervical cancer patient's tumour sample for original and recurrent cervical cancer, and gene analysis in both tumours and exosomes in these mouse models were performed. We found that activating transcription factor 1 (ATF1) and RAS genes were significantly up-regulated in tumours of both primary and recurrent cervical cancer mouse model, and they can also be detected in the blood exosomes of the mouse model. Our results indicated that ATF1 and RAS could be potential candidate biomarkers for cervical cancer in early diagnosis. ATF1 and RAS genes were found significantly elevated in tumours of primary and recurrent cervical cancer mouse model, and they were also detected in the blood exosomes. Therefore, ATF1 and RAS could be used as a diagnostic marker for cervical cancer in the future. Copyright © 2017 John Wiley & Sons, Ltd.

Impact of The Protective Renin-Angiotensin System (RAS) on The Vasoreparative Function of CD34+ CACs in Diabetic Retinopathy

Science.gov (United States)

Duan, Yaqian; Moldovan, Leni; Miller, Rehae C.; Beli, Eleni; Salazar, Tatiana; Hazra, Sugata; Al-Sabah, Jude; Chalam, KV; Raghunandan, Sneha; Vyas, Ruchi;

Ameliorating effect of wheat bran, Beta-carotene and Curcumin on K-ras gene mutations and expression of ntioxidant enzymes in rat colon cancer

International Nuclear Information System (INIS)

Tarek Elmaghraby, T.; Korraa, S.S.; Maher, M.M.; Hassan, N.H.A.

2010-01-01

In Egypt, colon cancer has unique characterises differ than other countries, more than third cases happen in people under 40 years, with advanced stage, high grade tumors that carry more mutations . This may be return to increase pollution in food and water. The aim of the present study, is the investigation of the role of some natural products approaches for colorectal carcinoma including curcumin, wheat bran and β-Carotene. Accordingly, animals were injected with 1,2-dimethylhydrazine hydrochloride (DMH) and/or dually exposed to ionizing radiation to induce colorectal cancer. The frequency of mutation of K-ras gene, the level activity of SOD, GpX antioxidant enzymes and expression of SOD1, SOD2 and GpX1 in tissue of 120 colon rats from 10 different treated groups were studied. Curcumin, wheat bran and D-carotene have inhibition effect on formation of colon cancer and decrease the mutations in K-ras gene. Moreover, they have ameliorating effect on antioxidants enzymes activities and expressions. The present study revealed that wheat bran and D-carotene have better effect than curcumin.

RASOnD - A comprehensive resource and search tool for RAS superfamily oncogenes from various species

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Singh Tej P

2011-07-01

Full Text Available Abstract Background The Ras superfamily plays an important role in the control of cell signalling and division. Mutations in the Ras genes convert them into active oncogenes. The Ras oncogenes form a major thrust of global cancer research as they are involved in the development and progression of tumors. This has resulted in the exponential growth of data on Ras superfamily across different public databases and in literature. However, no dedicated public resource is currently available for data mining and analysis on this family. The present database was developed to facilitate straightforward accession, retrieval and analysis of information available on Ras oncogenes from one particular site. Description We have developed the RAS Oncogene Database (RASOnD as a comprehensive knowledgebase that provides integrated and curated information on a single platform for oncogenes of Ras superfamily. RASOnD encompasses exhaustive genomics and proteomics data existing across diverse publicly accessible databases. This resource presently includes overall 199,046 entries from 101 different species. It provides a search tool to generate information about their nucleotide and amino acid sequences, single nucleotide polymorphisms, chromosome positions, orthologies, motifs, structures, related pathways and associated diseases. We have implemented a number of user-friendly search interfaces and sequence analysis tools. At present the user can (i browse the data (ii search any field through a simple or advance search interface and (iii perform a BLAST search and subsequently CLUSTALW multiple sequence alignment by selecting sequences of Ras oncogenes. The Generic gene browser, GBrowse, JMOL for structural visualization and TREEVIEW for phylograms have been integrated for clear perception of retrieved data. External links to related databases have been included in RASOnD. Conclusions This database is a resource and search tool dedicated to Ras oncogenes. It has

Agrobacterium rhizogenes-Mediated Transformation – a Non-GMO Platform For Developing Compact Ornamentals

DEFF Research Database (Denmark)

Lütken, Henrik Vlk; Hegelund, Josefine Nymark; Lauridsen, Uffe Bjerre

of these compounds are potentially harmful to both the environment and human health. A new non-GMO molecular breeding strategy, as opposed to both the application of chemical growth retardants and conventional molecular breeding is Agrobacterium rhizogenes-mediated transformation. In this method, the soil borne...... for transformations, plants produced via this approach are not considered as GMOs in the European Union and Japan. We have developed an optimised Agrobacterium rhizogenes-mediated transformation platform useful for a wide range of ornamentals. Kalanchoë was the starting point and the effect of the rol-genes has now...

Impact of Emergent Circulating Tumor DNA RAS Mutation in Panitumumab-Treated Chemoresistant Metastatic Colorectal Cancer.

Science.gov (United States)

Kim, Tae Won; Peeters, Marc; Thomas, Anne L; Gibbs, Peter; Hool, Kristina; Zhang, Jianqi; Ang, Agnes; Bach, Bruce Allen; Price, Timothy

2018-06-13

The accumulation of emergent RAS mutations during anti-epidermal growth factor receptor (EGFR) therapy is of interest as a mechanism for acquired resistance to anti-EGFR treatment. Plasma analysis of circulating tumor (ct) DNA is a minimally invasive and highly sensitive method to determine RAS mutational status. This biomarker analysis of the global phase III ASPECCT study used next-generation sequencing to detect expanded RAS ctDNA mutations in panitumumab-treated patients. Plasma samples collected at baseline and posttreatment were analyzed categorically for the presence of RAS mutations by the Plasma Select -R™ 64-gene panel at 0.1% sensitivity. Among panitumumab-treated patients with evaluable plasma samples at baseline (n = 238), 188 (79%) were wild-type (WT) RAS, and 50 (21%) were mutant RAS Of the 188 patients with baseline ctDNA WT RAS status, 164 had evaluable posttreatment results with a 32% rate of emergent RAS mutations. The median overall survival (OS) for WT and RAS mutant status by ctDNA at baseline was 13.7 (95% confidence interval: 11.5-15.4) and 7.9 months (6.4-9.6), respectively ( P < 0.0001). Clinical outcomes were not significantly different between patients with and without emergent ctDNA RAS mutations. Although patients with baseline ctDNA RAS mutations had worse outcomes than patients who were WT RAS before initiating treatment, emergent ctDNA RAS mutations were not associated with less favorable patient outcomes in panitumumab-treated patients. Further research is needed to determine a clinically relevant threshold for baseline and emergent ctDNA RAS mutations. Copyright ©2018, American Association for Cancer Research.

A Histidine pH sensor regulates activation of the Ras-specific guanine nucleotide exchange factor RasGRP1.

Science.gov (United States)

Vercoulen, Yvonne; Kondo, Yasushi; Iwig, Jeffrey S; Janssen, Axel B; White, Katharine A; Amini, Mojtaba; Barber, Diane L; Kuriyan, John; Roose, Jeroen P

2017-09-27

RasGRPs are guanine nucleotide exchange factors that are specific for Ras or Rap, and are important regulators of cellular signaling. Aberrant expression or mutation of RasGRPs results in disease. An analysis of RasGRP1 SNP variants led to the conclusion that the charge of His 212 in RasGRP1 alters signaling activity and plasma membrane recruitment, indicating that His 212 is a pH sensor that alters the balance between the inactive and active forms of RasGRP1. To understand the structural basis for this effect we compared the structure of autoinhibited RasGRP1, determined previously, to those of active RasGRP4:H-Ras and RasGRP2:Rap1b complexes. The transition from the autoinhibited to the active form of RasGRP1 involves the rearrangement of an inter-domain linker that displaces inhibitory inter-domain interactions. His 212 is located at the fulcrum of these conformational changes, and structural features in its vicinity are consistent with its function as a pH-dependent switch.

Transformation assay in Bhas 42 cells: a model using initiated cells to study mechanisms of carcinogenesis and predict carcinogenic potential of chemicals.

Science.gov (United States)

Sasaki, Kiyoshi; Umeda, Makoto; Sakai, Ayako; Yamazaki, Shojiro; Tanaka, Noriho

2015-01-01

Transformation assays using cultured cells have been applied to the study of carcinogenesis. Although various cell systems exist, few cell types such as BALB/c 3T3 subclones and Syrian hamster embryo cells have been used to study chemically induced two-stage carcinogenesis. Bhas 42 cells were established as a clone by the transfection with the v-Ha-ras gene into mouse BALB/c 3T3 A31-1-1 cells and their subsequent selection based on their sensitivity to 12-O-tetradecanoylphorbol-13-acetate. Using Bhas 42 cells, transformed foci were induced by the treatment with nongenotoxic carcinogens, most of which act as tumor promoters. Therefore, Bhas 42 cells were considered to be a model of initiated cells. Subsequently, not only nongenotoxic carcinogens but also genotoxic carcinogens, most of which act as tumor initiators, were found to induce transformed foci by the modification of the protocol. Furthermore, transformation of Bhas 42 cells was induced by the transfection with genes of oncogenic potential. We interpret this high sensitivity of Bhas 42 cells to various types of carcinogenic stimuli to be related to the multistage model of carcinogenesis, as the transfection of v-Ha-ras gene further advances the parental BALB/c 3T3 A31-1-1 cells toward higher transforming potential. Thus, we propose that Bhas 42 cells are a novel and sensitive cell line for the analysis of carcinogenesis and can be used for the detection of not only carcinogenic substances but also gene alterations related to oncogenesis. This review will address characteristics of Bhas 42 cells, the transformation assay protocol, validation studies, and the various chemicals tested in this assay.

Nucleotide sequence of a human cDNA encoding a ras-related protein (rap1B)

Energy Technology Data Exchange (ETDEWEB)

Pizon, V; Lerosey, I; Chardin, P; Tavitian, A [INSERM, Paris (France)

1988-08-11

The authors have previously characterized two human ras-related genes rap1 and rap2. Using the rap1 clone as probe they isolated and sequenced a new rap cDNA encoding the 184aa rap1B protein. The rap1B protein is 95% identical to rap1 and shares several properties with the ras protein suggesting that it could bind GTP/GDP and have a membrane location. As for rap1, the structural characteristics of rap1B suggest that the rap and ras proteins might interact on the same effector.

Distinct gene number-genome size relationships for eukaryotes and non-eukaryotes: gene content estimation for dinoflagellate genomes.

Directory of Open Access Journals (Sweden)

Yubo Hou

Full Text Available The ability to predict gene content is highly desirable for characterization of not-yet sequenced genomes like those of dinoflagellates. Using data from completely sequenced and annotated genomes from phylogenetically diverse lineages, we investigated the relationship between gene content and genome size using regression analyses. Distinct relationships between log(10-transformed protein-coding gene number (Y' versus log(10-transformed genome size (X', genome size in kbp were found for eukaryotes and non-eukaryotes. Eukaryotes best fit a logarithmic model, Y' = ln(-46.200+22.678X', whereas non-eukaryotes a linear model, Y' = 0.045+0.977X', both with high significance (p0.91. Total gene number shows similar trends in both groups to their respective protein coding regressions. The distinct correlations reflect lower and decreasing gene-coding percentages as genome size increases in eukaryotes (82%-1% compared to higher and relatively stable percentages in prokaryotes and viruses (97%-47%. The eukaryotic regression models project that the smallest dinoflagellate genome (3x10(6 kbp contains 38,188 protein-coding (40,086 total genes and the largest (245x10(6 kbp 87,688 protein-coding (92,013 total genes, corresponding to 1.8% and 0.05% gene-coding percentages. These estimates do not likely represent extraordinarily high functional diversity of the encoded proteome but rather highly redundant genomes as evidenced by high gene copy numbers documented for various dinoflagellate species.

Interaction between Wnt/β-catenin and RAS-ERK pathways and an anti-cancer strategy via degradations of β-catenin and RAS by targeting the Wnt/β-catenin pathway.

Science.gov (United States)

Jeong, Woo-Jeong; Ro, Eun Ji; Choi, Kang-Yell

2018-01-01

Aberrant activation of the Wnt/β-catenin and RAS-extracellular signal-regulated kinase (ERK) pathways play important roles in the tumorigenesis of many different types of cancer, most notably colorectal cancer (CRC). Genes for these two pathways, such as adenomatous polyposis coli ( APC ) and KRAS are frequently mutated in human CRC, and involved in the initiation and progression of the tumorigenesis, respectively. Moreover, recent studies revealed interaction of APC and KRAS mutations in the various stages of colorectal tumorigenesis and even in metastasis accompanying activation of the cancer stem cells (CSCs). A key event in the synergistic cooperation between Wnt/β-catenin and RAS-ERK pathways is a stabilization of both β-catenin and RAS especially mutant KRAS by APC loss, and pathological significance of this was indicated by correlation of increased β-catenin and RAS levels in human CRC where APC mutations occur as high as 90% of CRC patients. Together with the notion of the protein activity reduction by lowering its level, inhibition of both β-catenin and RAS especially by degradation could be a new ideal strategy for development of anti-cancer drugs for CRC. In this review, we will discuss interaction between the Wnt/β-catenin and RAS-ERK pathways in the colorectal tumorigenesis by providing the mechanism of RAS stabilization by aberrant activation of Wnt/β-catenin. We will also discuss our small molecular anti-cancer approach controlling CRC by induction of specific degradations of both β-catenin and RAS via targeting Wnt/β-catenin pathway especially for the KYA1797K, a small molecule specifically binding at the regulator of G-protein signaling (RGS)-domain of Axin.

Adaptation of a RAS pathway activation signature from FF to FFPE tissues in colorectal cancer

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Bernard Omolo

2016-10-01

Full Text Available Abstract Background The KRAS gene is mutated in about 40 % of colorectal cancer (CRC cases, which has been clinically validated as a predictive mutational marker of intrinsic resistance to anti-EGFR inhibitor (EGFRi therapy. Since nearly 60 % of patients with a wild type KRAS fail to respond to EGFRi combination therapies, there is a need to develop more reliable molecular signatures to better predict response. Here we address the challenge of adapting a gene expression signature predictive of RAS pathway activation, created using fresh frozen (FF tissues, for use with more widely available formalin fixed paraffin-embedded (FFPE tissues. Methods In this study, we evaluated the translation of an 18-gene RAS pathway signature score from FF to FFPE in 54 CRC cases, using a head-to-head comparison of five technology platforms. FFPE-based technologies included the Affymetrix GeneChip (Affy, NanoString nCounter™ (NanoS, Illumina whole genome RNASeq (RNA-Acc, Illumina targeted RNASeq (t-RNA, and Illumina stranded Total RNA-rRNA-depletion (rRNA. Results Using Affy_FF as the “gold” standard, initial analysis of the 18-gene RAS scores on all 54 samples shows varying pairwise Spearman correlations, with (1 Affy_FFPE (r = 0.233, p = 0.090; (2 NanoS_FFPE (r = 0.608, p < 0.0001; (3 RNA-Acc_FFPE (r = 0.175, p = 0.21; (4 t-RNA_FFPE (r = −0.237, p = 0.085; (5 and t-RNA (r = −0.012, p = 0.93. These results suggest that only NanoString has successful FF to FFPE translation. The subsequent removal of identified “problematic” samples (n = 15 and genes (n = 2 further improves the correlations of Affy_FF with three of the five technologies: Affy_FFPE (r = 0.672, p < 0.0001; NanoS_FFPE (r = 0.738, p < 0.0001; and RNA-Acc_FFPE (r = 0.483, p = 0.002. Conclusions Of the five technology platforms tested, NanoString technology provides a more faithful translation of the RAS pathway gene

Stable transformation of sunflower (Helianthus annuus L.) using a non-meristematic regeneration protocol and green fluorescent protein as a vital marker.

Science.gov (United States)

Müller, A; Iser, M; Hess, D

2001-10-01

Stable transformation of sunflower was achieved using a non-meristematic hypocotyl explant regeneration protocol of public inbred HA300B. Uniformly transformed shoots were obtained after co-cultivation with Agrobacterium tumefaciens carrying a gfp (green fluorescent protein) gene containing an intron that blocks expression of gfp in Agrobacterium. Easily detectable, bright green fluorescence of transformed tissues was used to establish an optimal regeneration and transformation procedure. By Southern blot analysis, integration of the gfp and nptll genes was confirmed. Stable transformation efficiency was 0.1%. From 68 T1 plants analyzed, 17 showed transmission of transgene DNA and 15 of them contained the intact gfp gene. Expression of gfp was detected in 10 T1 plants carrying the intact gfp gene using a fluorimetric assay or western blot analysis. Expression of the nptll gene was confirmed in 13 T1 plants. The transformation system enables the rapid transfer of agronomically important genes.

Inhibition of the Ras-Net (Elk-3) pathway by a novel pyrazole that affects microtubules.

Science.gov (United States)

Wasylyk, Christine; Zheng, Hong; Castell, Christelle; Debussche, Laurent; Multon, Marie-Christine; Wasylyk, Bohdan

2008-03-01

Net (Elk-3/SAP-2/Erp) is a transcription factor that is phosphorylated and activated by the Ras-extracellular signal-regulated kinase (Erk) signaling pathway and is involved in wound healing, angiogenesis, and tumor growth. In a cell-based screen for small molecule inhibitors of Ras activation of Net transcriptional activity, we identified a novel pyrazole, XRP44X. XRP44X inhibits fibroblast growth factor 2 (FGF-2)-induced Net phosphorylation by the Ras-Erk signaling upstream from Ras. It also binds to the colchicine-binding site of tubulin, depolymerizes microtubules, stimulates cell membrane blebbing, and affects the morphology of the actin skeleton. Interestingly, Combretastin-A4, which produces similar effects on the cytoskeleton, also inhibits FGF-2 Ras-Net signaling. This differs from other classes of agents that target microtubules, which have either little effect (vincristine) or no effect (docetaxel and nocodazole) on the Ras-Net pathway. XRP44X inhibits various cellular properties, including cell growth, cell cycle progression, and aortal sprouting, similar to other molecules that bind to the tubulin colchicine site. XRP44X has the potentially interesting property of connecting two important pathways involved in cell transformation and may thereby represent an interesting class of molecules that could be developed for cancer treatment.

What makes Ras an efficient molecular switch: a computational, biophysical, and structural study of Ras-GDP interactions with mutants of Raf.

Science.gov (United States)

Filchtinski, Daniel; Sharabi, Oz; Rüppel, Alma; Vetter, Ingrid R; Herrmann, Christian; Shifman, Julia M

2010-06-11

Ras is a small GTP-binding protein that is an essential molecular switch for a wide variety of signaling pathways including the control of cell proliferation, cell cycle progression and apoptosis. In the GTP-bound state, Ras can interact with its effectors, triggering various signaling cascades in the cell. In the GDP-bound state, Ras looses its ability to bind to known effectors. The interaction of the GTP-bound Ras (Ras(GTP)) with its effectors has been studied intensively. However, very little is known about the much weaker interaction between the GDP-bound Ras (Ras(GDP)) and Ras effectors. We investigated the factors underlying the nucleotide-dependent differences in Ras interactions with one of its effectors, Raf kinase. Using computational protein design, we generated mutants of the Ras-binding domain of Raf kinase (Raf) that stabilize the complex with Ras(GDP). Most of our designed mutations narrow the gap between the affinity of Raf for Ras(GTP) and Ras(GDP), producing the desired shift in binding specificity towards Ras(GDP). A combination of our best designed mutation, N71R, with another mutation, A85K, yielded a Raf mutant with a 100-fold improvement in affinity towards Ras(GDP). The Raf A85K and Raf N71R/A85K mutants were used to obtain the first high-resolution structures of Ras(GDP) bound to its effector. Surprisingly, these structures reveal that the loop on Ras previously termed the switch I region in the Ras(GDP).Raf mutant complex is found in a conformation similar to that of Ras(GTP) and not Ras(GDP). Moreover, the structures indicate an increased mobility of the switch I region. This greater flexibility compared to the same loop in Ras(GTP) is likely to explain the natural low affinity of Raf and other Ras effectors to Ras(GDP). Our findings demonstrate that an accurate balance between a rigid, high-affinity conformation and conformational flexibility is required to create an efficient and stringent molecular switch. Copyright 2010 Elsevier Ltd

High Intra- and Inter-Tumoral Heterogeneity of RAS Mutations in Colorectal Cancer

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Marion Jeantet

2016-12-01

Full Text Available Approximately 30% of patients with wild type RAS metastatic colorectal cancer are non-responders to anti-epidermal growth factor receptor monoclonal antibodies (anti-EGFR mAbs, possibly due to undetected tumoral subclones harboring RAS mutations. The aim of this study was to analyze the distribution of RAS mutations in different areas of the primary tumor, metastatic lymph nodes and distant metastasis. A retrospective cohort of 18 patients with a colorectal cancer (CRC was included in the study. Multiregion analysis was performed in 60 spatially separated tumor areas according to the pathological tumor node metastasis (pTNM staging and KRAS, NRAS and BRAF mutations were tested using pyrosequencing. In primary tumors, intra-tumoral heterogeneity for RAS mutation was found in 33% of cases. Inter-tumoral heterogeneity for RAS mutation between primary tumors and metastatic lymph nodes or distant metastasis was found in 36% of cases. Moreover, 28% of tumors had multiple RAS mutated subclones in the same tumor. A high proportion of CRCs presented intra- and/or inter-tumoral heterogeneity, which has relevant clinical implications for anti-EGFR mAbs prescription. These results suggest the need for multiple RAS testing in different parts of the same tumor and/or more sensitive techniques.

Detecção imunoistoquímica das oncoproteínas p21ras, c-myc E p53 no carcinoma hepatocelular e no tecido hepático não-neoplásico Immunohistochemical detection of p21ras, c-myc and p53 oncoproteins in hepatocellular carcinoma and in non-neoplastic liver tissue

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Vera Lucia Nunes Pannain

2004-12-01

oncoproteins in hepatocellular carcinoma and non neoplastic tissue. Association of the immunoreactivity of these markers with histological grades and patterns, hepatitis B and C were additionally studied. METHODS: Detection of oncoproteins p21ras, c-myc and p53 was performed immunohistochemically in hepatocellular carcinoma (47 cases and surrounding non neoplastic liver tissue (40 cases. RESULTS: Oncoproteins p21ras, c-myc and p53 were detected in 44,7%, 53,2% and 36,2% of the hepatocellular carcinoma cases, respectively. The p21ras and c-myc immunoreactivity has shown a significant association. However there was no association of p21ras, c-myc and p53 detection with hepatitis B and C virus infections, histological grades and patterns. The same significant association between p21ras and c-myc was observed in non-neoplastic tissue with cirrhosis when compared with tissue without it. The p53 immunoreactivity was negative in all non-neoplastic liver tissue samples. CONCLUSIONS: The immunoreactivity detection of p21ras, c-myc and p53 corroborates previous evidence of their detection in hepatocellular carcinoma that suggest the participation of these proteins in human hepatocarcinogenesis. The significant association between p21ras and c-myc oncoproteins in hepatocellular carcinoma and in cirrhosis can point to an interaction between them mainly, in hepatocarcinogenesis that occurs through cirrhosis.

Agrobacterium-mediated transformation of tomato with the ICE1 transcription factor gene.

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Juan, J X; Yu, X H; Jiang, X M; Gao, Z; Zhang, Y; Li, W; Duan, Y D; Yang, G

2015-01-30

ICE1 genes play a very important role in plants in cold conditions. To improve the cold resistance of tomato, the ICE1 gene of Arabidopsis thaliana was used to construct the plant expression vector p3301-ICE1, and was overexpressed in tomato through Agrobacterium-mediated transformation. Five strains of resistant plants were obtained. PCR and half-quantitative results showed that the ICE1 gene was transferred to tomato; three strains tested positive. After low-temperature stress treatment, praline content and peroxide and catalase activities in the transgenic tomato plants were higher compared with non-transgenic controls, while malondialdehyde content was clearly lower.

Activation of the JNK pathway is essential for transformation by the Met oncogene.

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Rodrigues, G A; Park, M; Schlessinger, J

1997-05-15

The Met/Hepatocyte Growth Factor (HGF) receptor tyrosine kinase is oncogenically activated through a rearrangement that creates a hybrid gene Tpr-Met. The resultant chimeric p65(Tpr-Met) protein is constitutively phosphorylated on tyrosine residues in vivo and associates with a number of SH2-containing signaling molecules including the p85 subunit of PI-3 kinase and the Grb2 adaptor protein, which couples receptor tyrosine kinases to the Ras signaling pathway. Mutation of the binding site for Grb2 impairs the ability of Tpr-Met oncoprotein to transform fibroblasts, suggesting that the activation of the Ras/MAP kinase signaling pathway through Grb2 may be essential for cellular transformation. To test this hypothesis dominant-negative mutants of Grb2 with deletions of the SH3 domains were introduced into Tpr-Met transformed fibroblasts. Cells overexpressing the mutants were found to be morphologically reverted and exhibited reduced growth in soft agar. Surprisingly, the Grb2 mutants blocked activation of the JNK/SAPK but not MAP kinase activity induced by the Tpr-Met oncoprotein. Additionally, cells expressing dominant-negative Grb2 mutants had reduced PI-3-kinase activity and dominant-negative mutants of Rac1 blocked both Tpr-Met-induced transformation and activation of JNK. These experiments reveal a novel link between Met and the JNK pathway, which is essential for transformation by this oncogene.

Programmed Cell-to-Cell Variability in Ras Activity Triggers Emergent Behaviors during Mammary Epithelial Morphogenesis

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Jennifer S. Liu

2012-11-01

Full Text Available Variability in signaling pathway activation between neighboring epithelial cells can arise from local differences in the microenvironment, noisy gene expression, or acquired genetic changes. To investigate the consequences of this cell-to-cell variability in signaling pathway activation on coordinated multicellular processes such as morphogenesis, we use DNA-programmed assembly to construct three-dimensional MCF10A microtissues that are mosaic for low-level expression of activated H-Ras. We find two emergent behaviors in mosaic microtissues: cells with activated H-Ras are basally extruded or lead motile multicellular protrusions that direct the collective motility of their wild-type neighbors. Remarkably, these behaviors are not observed in homogeneous microtissues in which all cells express the activated Ras protein, indicating that heterogeneity in Ras activity, rather than the total amount of Ras activity, is critical for these processes. Our results directly demonstrate that cell-to-cell variability in pathway activation within local populations of epithelial cells can drive emergent behaviors during epithelial morphogenesis.

The C-terminus of H-Ras as a target for the covalent binding of reactive compounds modulating Ras-dependent pathways.

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Clara L Oeste

2011-01-01

Full Text Available Ras proteins are crucial players in differentiation and oncogenesis and constitute important drug targets. The localization and activity of Ras proteins are highly dependent on posttranslational modifications at their C-termini. In addition to an isoprenylated cysteine, H-Ras, but not other Ras proteins, possesses two cysteine residues (C181 and C184 in the C-terminal hypervariable domain that act as palmitoylation sites in cells. Cyclopentenone prostaglandins (cyPG are reactive lipidic mediators that covalently bind to H-Ras and activate H-Ras dependent pathways. Dienone cyPG, such as 15-deoxy-Δ(12,14-PGJ(2 (15d-PGJ(2 and Δ(12-PGJ(2 selectively bind to the H-Ras hypervariable domain. Here we show that these cyPG bind simultaneously C181 and C184 of H-Ras, thus potentially altering the conformational tendencies of the hypervariable domain. Based on these results, we have explored the capacity of several bifunctional cysteine reactive small molecules to bind to the hypervariable domain of H-Ras proteins. Interestingly, phenylarsine oxide (PAO, a widely used tyrosine phosphatase inhibitor, and dibromobimane, a cross-linking agent used for cysteine mapping, effectively bind H-Ras hypervariable domain. The interaction of PAO with H-Ras takes place in vitro and in cells and blocks modification of H-Ras by 15d-PGJ(2. Moreover, PAO treatment selectively alters H-Ras membrane partition and the pattern of H-Ras activation in cells, from the plasma membrane to endomembranes. These results identify H-Ras as a novel target for PAO. More importantly, these observations reveal that small molecules or reactive intermediates interacting with spatially vicinal cysteines induce intramolecular cross-linking of H-Ras C-terminus potentially contributing to the modulation of Ras-dependent pathways.

Suppression of survivin expression in glioblastoma cells by the Ras inhibitor farnesylthiosalicylic acid promotes caspase-dependent apoptosis.

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Blum, Roy; Jacob-Hirsch, Jasmine; Rechavi, Gideon; Kloog, Yoel

2006-09-01

The Ras inhibitor farnesylthiosalicylic acid (FTS) has been shown to induce apoptosis in glioblastoma multiforme, but its mechanism of action was unknown. We show that FTS or dominant-negative Ras, by deregulating extracellular signal-regulated kinase and Akt signaling, decreases survivin gene transcripts in U87 glioblastoma multiforme, leading to disappearance of survivin protein and cell death. FTS affected both Ras-controlled regulators of survivin transcription and Ras-regulated survival signals. Thus, Ras inhibition by FTS resulted in release of the survivin "brake" on apoptosis and in activation of the mitochondrial apoptotic pathway: dephosphorylation of Bad, activation of Bax, release of cytochrome c, and caspase activation. FTS-induced apoptosis of U87 cells was strongly attenuated by forced expression of survivin or by caspase inhibitors. These results show that resistance to apoptosis in glioblastoma multiforme can be abolished by a single Ras inhibitor, which targets both survivin, a critical inhibitor of apoptosis, and the intrinsic mitochondrial apoptotic machinery.

A Fast, Sensitive and Accurate High Resolution Melting (HRM Technology-Based Assay to Screen for Common K-ras Mutations

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D. Kramer

2009-01-01

Full Text Available Background: Increasing evidence points to a negative correlation between K-ras mutations and patient’s response to, or survival benefit after, treatment with EGFR-inhibitors. Therefore, rapid and reliable assays for mutational analysis of the K-ras gene are strongly needed.

Activation of RAS/ERK alone is insufficient to inhibit RXRα function and deplete retinoic acid in hepatocytes

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Wang, Ai-Guo, E-mail: wangaiguotl@hotmail.com; Song, Ya-Nan; Chen, Jun; Li, Hui-Ling; Dong, Jian-Yi; Cui, Hai-Peng; Yao, Liang; Li, Xue-Feng; Gao, Wen-Ting; Qiu, Ze-Wen; Wang, Fu-Jin; Wang, Jing-Yu, E-mail: wangjingyus@163.com

2014-09-26

Highlights: • The activation of RAS/ERK is insufficient to inhibit RXRα function and deplete RA. • The retinoid metabolism-related genes are down-regulated by ras oncogene. • The atRA has no effect on preventing hepatic tumorigenesis or curing the developed hepatic nodules. - Abstract: Activation of RAS/ERK signaling pathway, depletion of retinoid, and phosphorylation of retinoid X receptor alpha (RXRα) are frequent events found in liver tumors and thought to play important roles in hepatic tumorigenesis. However, the relationships among them still remained to be elucidated. By exploring the transgenic mouse model of hepatic tumorigenesis induced by liver-specific expression of H-ras12V oncogene, the activation of RAS/ERK, the mRNA expression levels of retinoid metabolism-related genes, the contents of retinoid metabolites, and phosphorylation of RXRα were determined. RAS/ERK signaling pathway was gradually and significantly activated in hepatic tumor adjacent normal liver tissues (P) and hepatic tumor tissues (T) of H-ras12V transgenic mice compared with normal liver tissues (Wt) of wild type mice. On the contrary, the mRNA expression levels of retinoid metabolism-related genes were significantly reduced in P and T compared with Wt. Interestingly, the retinoid metabolites 9-cis-retinoic acid (9cRA) and all-trans-retinoic acid (atRA), the well known ligands for nuclear transcription factor RXR and retinoic acid receptor (RAR), were significantly decreased only in T compared with Wt and P, although the oxidized polar metabolite of atRA, 4-keto-all-trans-retinoic-acid (4-keto-RA) was significantly decreased in both P and T compared with Wt. To our surprise, the functions of RXRα were significantly blocked only in T compared with Wt and P. Namely, the total protein levels of RXRα were significantly reduced and the phosphorylation levels of RXRα were significantly increased only in T compared with Wt and P. Treatment of H-ras12V transgenic mice at 5-week

Harvey murine sarcoma virus p21 ras protein: biological and biochemical significance of the cysteine nearest the carboxy terminus

DEFF Research Database (Denmark)

Willumsen, B M; Norris, K; Papageorge, A G

1984-01-01

localization. We have now further characterized the post-translational processing of these mutants and have also studied two C-terminal v-rasH point mutants: one encodes serine in place of cysteine-186, the other threonine for valine-187. The Thr-187 mutant was transformation-competent, and its p21 protein...... not undergo the posttranslational processing common to biologically active ras proteins: their electrophoretic migration rate did not change, they remained in the cytosol, and they failed to bind lipid. Since the cell-encoded ras proteins also contain this cysteine, we conclude that this amino acid residue...

High-Affinity Interaction of the K-Ras4B Hypervariable Region with the Ras Active Site

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Chavan, Tanmay S.; Jang, Hyunbum; Khavrutskii, Lyuba; Abraham, Sherwin J.; Banerjee, Avik; Freed, Benjamin C.; Johannessen, Liv; Tarasov, Sergey G.; Gaponenko, Vadim; Nussinov, Ruth; Tarasova, Nadya I.

2015-01-01

Ras proteins are small GTPases that act as signal transducers between cell surface receptors and several intracellular signaling cascades. They contain highly homologous catalytic domains and flexible C-terminal hypervariable regions (HVRs) that differ across Ras isoforms. KRAS is among the most frequently mutated oncogenes in human tumors. Surprisingly, we found that the C-terminal HVR of K-Ras4B, thought to minimally impact the catalytic domain, directly interacts with the active site of the protein. The interaction is almost 100-fold tighter with the GDP-bound than the GTP-bound protein. HVR binding interferes with Ras-Raf interaction, modulates binding to phospholipids, and slightly slows down nucleotide exchange. The data indicate that contrary to previously suggested models of K-Ras4B signaling, HVR plays essential roles in regulation of signaling. High affinity binding of short peptide analogs of HVR to K-Ras active site suggests that targeting this surface with inhibitory synthetic molecules for the therapy of KRAS-dependent tumors is feasible. PMID:26682817

Ras proteins have multiple functions in vegetative cells of Dictyostelium.

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Bolourani, Parvin; Spiegelman, George; Weeks, Gerald

2010-11-01

During the aggregation of Dictyostelium cells, signaling through RasG is more important in regulating cyclic AMP (cAMP) chemotaxis, whereas signaling through RasC is more important in regulating the cAMP relay. However, RasC is capable of substituting for RasG for chemotaxis, since rasG⁻ cells are only partially deficient in chemotaxis, whereas rasC⁻/rasG⁻ cells are totally incapable of chemotaxis. In this study we have examined the possible functional overlap between RasG and RasC in vegetative cells by comparing the vegetative cell properties of rasG⁻, rasC⁻, and rasC⁻/rasG⁻ cells. In addition, since RasD, a protein not normally found in vegetative cells, is expressed in vegetative rasG⁻ and rasC⁻/rasG⁻ cells and appears to partially compensate for the absence of RasG, we have also examined the possible functional overlap between RasG and RasD by comparing the properties of rasG⁻ and rasC⁻/rasG⁻ cells with those of the mutant cells expressing higher levels of RasD. The results of these two lines of investigation show that RasD is capable of totally substituting for RasG for cytokinesis and growth in suspension, whereas RasC is without effect. In contrast, for chemotaxis to folate, RasC is capable of partially substituting for RasG, but RasD is totally without effect. Finally, neither RasC nor RasD is able to substitute for the role that RasG plays in regulating actin distribution and random motility. These specificity studies therefore delineate three distinct and none-overlapping functions for RasG in vegetative cells.

Disorders of dysregulated signal traffic through the RAS-MAPK pathway: phenotypic spectrum and molecular mechanisms.

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Tartaglia, Marco; Gelb, Bruce D

2010-12-01

RAS GTPases control a major signaling network implicated in several cellular functions, including cell fate determination, proliferation, survival, differentiation, migration, and senescence. Within this network, signal flow through the RAF-MEK-ERK pathway-the first identified mitogen-associated protein kinase (MAPK) cascade-mediates early and late developmental processes controlling morphology determination, organogenesis, synaptic plasticity, and growth. Signaling through the RAS-MAPK cascade is tightly controlled; and its enhanced activation represents a well-known event in oncogenesis. Unexpectedly, in the past few years, inherited dysregulation of this pathway has been recognized as the cause underlying a group of clinically related disorders sharing facial dysmorphism, cardiac defects, reduced postnatal growth, ectodermal anomalies, variable cognitive deficits, and susceptibility to certain malignancies as major features. These disorders are caused by heterozygosity for mutations in genes encoding RAS proteins, regulators of RAS function, modulators of RAS interaction with effectors, or downstream signal transducers. Here, we provide an overview of the phenotypic spectrum associated with germline mutations perturbing RAS-MAPK signaling, the unpredicted molecular mechanisms converging toward the dysregulation of this signaling cascade, and major genotype-phenotype correlations. © 2010 New York Academy of Sciences.

Epac activation sensitizes rat sensory neurons via activation of Ras

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Shariati, Behzad; Thompson, Eric L.; Nicol, Grant D.; Vasko, Michael R.

2015-01-01

Guanine nucleotide exchange factors directly activated by cAMP (Epacs) have emerged as important signaling molecules mediating persistent hypersensitivity in animal models of inflammation, by augmenting the excitability of sensory neurons. Although Epacs activate numerous downstream signaling cascades, the intracellular signaling which mediates Epac-induced sensitization of capsaicin-sensitive sensory neurons remains unknown. Here, we demonstrate that selective activation of Epacs with 8-CPT-2′-O-Me-cAMP-AM (8CPT-AM) increases the number of action potentials (APs) generated by a ramp of depolarizing current and augments the evoked release of calcitonin gene-related peptide (CGRP) from isolated rat sensory neurons. Internal perfusion of capsaicin-sensitive sensory neurons with GDP-βS, substituted for GTP, blocks the ability of 8CPT-AM to increase AP firing, demonstrating that Epac-induced sensitization is G-protein dependent. Treatment with 8CPT-AM activates the small G-proteins Rap1 and Ras in cultures of sensory neurons. Inhibition of Rap1, by internal perfusion of a Rap1-neutralizing antibody or through a reduction in the expression of the protein using shRNA does not alter the Epac-induced enhancement of AP generation or CGRP release, despite the fact that in most other cell types, Epacs act as Rap-GEFs. In contrast, inhibition of Ras through expression of a dominant negative Ras (DN-Ras) or through internal perfusion of a Ras-neutralizing antibody blocks the increase in AP firing and attenuates the increase in the evoked release of CGRP induced by Epac activation. Thus, in this subpopulation of nociceptive sensory neurons, it is the novel interplay between Epacs and Ras, rather than the canonical Epacs and Rap1 pathway, that is critical for mediating Epac-induced sensitization. PMID:26596174

Epac activation sensitizes rat sensory neurons through activation of Ras.

Science.gov (United States)

Shariati, Behzad; Thompson, Eric L; Nicol, Grant D; Vasko, Michael R

2016-01-01

Guanine nucleotide exchange factors directly activated by cAMP (Epacs) have emerged as important signaling molecules mediating persistent hypersensitivity in animal models of inflammation, by augmenting the excitability of sensory neurons. Although Epacs activate numerous downstream signaling cascades, the intracellular signaling which mediates Epac-induced sensitization of capsaicin-sensitive sensory neurons remains unknown. Here, we demonstrate that selective activation of Epacs with 8-CPT-2'-O-Me-cAMP-AM (8CPT-AM) increases the number of action potentials (APs) generated by a ramp of depolarizing current and augments the evoked release of calcitonin gene-related peptide (CGRP) from isolated rat sensory neurons. Internal perfusion of capsaicin-sensitive sensory neurons with GDP-βS, substituted for GTP, blocks the ability of 8CPT-AM to increase AP firing, demonstrating that Epac-induced sensitization is G-protein dependent. Treatment with 8CPT-AM activates the small G-proteins Rap1 and Ras in cultures of sensory neurons. Inhibition of Rap1, by internal perfusion of a Rap1-neutralizing antibody or through a reduction in the expression of the protein using shRNA does not alter the Epac-induced enhancement of AP generation or CGRP release, despite the fact that in most other cell types, Epacs act as Rap-GEFs. In contrast, inhibition of Ras through expression of a dominant negative Ras (DN-Ras) or through internal perfusion of a Ras-neutralizing antibody blocks the increase in AP firing and attenuates the increase in the evoked release of CGRP induced by Epac activation. Thus, in this subpopulation of nociceptive sensory neurons, it is the novel interplay between Epacs and Ras, rather than the canonical Epacs and Rap1 pathway, that is critical for mediating Epac-induced sensitization. Copyright © 2015 Elsevier Inc. All rights reserved.

Detection of up to 65% of Precancerous Lesions of the Human Colon and Rectum by Mutation Analysis of APC, K-Ras, B-Raf and CTNNB1

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Schneider, Mandy; Scholtka, Bettina; Gottschalk, Uwe; Faiss, Siegbert; Schatz, Daniela; Berghof-Jäger, Kornelia; Steinberg, Pablo

2010-01-01

In the present study a recently conceived 4-gene marker panel covering the Wnt and Ras-Raf-MEK-MAPK signaling pathways was used to analyze 20 colorectal serrated lesions and 41 colorectal adenoma samples and to determine the percentage of each of the above-mentioned potentially precancerous lesions carrying at least one of the four above-mentioned genes in a mutated form. CTNNB1 and B-Raf were screened by PCR-single-strand conformation polymorphism analysis, K-Ras by restriction fragment length polymorphism analysis and the APC gene mutation cluster region (codons 1243–1567) by direct DNA sequencing. APC mutations were only detected in 10% of the serrated lesions but in 34% of the adenomas. Twenty percent of the serrated lesions and 14% of the adenomas carried a mutated K-Ras. B-Raf was found to be mutated in 50% of the serrated lesions and in 22% of the adenomas. CTNNB1 was altered in 12% of the adenomas, but not in serrated lesions. By using the above gene marker panel it could be shown that 65% of the serrated lesions and 61% of the adenomas carried at least one of the four genes in a mutated form. Based on its excellent performance in detecting mutations in sporadic preneoplastic (in this study) and neoplastic lesions (in a previous study) of the human colon and rectum, this primer combination might also be suited to efficiently and non-invasively detect genetic alterations in stool DNA of patients with early colorectal cancer

Detection of up to 65% of Precancerous Lesions of the Human Colon and Rectum by Mutation Analysis of APC, K-Ras, B-Raf and CTNNB1

Energy Technology Data Exchange (ETDEWEB)

Schneider, Mandy; Scholtka, Bettina, E-mail: scholtka@uni-potsdam.de [Chair of Nutritional Toxicology, Institute of Nutritional Science, University of Potsdam, Arthur- Scheunert-Allee 114-116, 14558 Nuthetal (Germany); Gottschalk, Uwe [Maria Heimsuchung Caritas-Klinik Pankow, Breite Straße 46/47, 13187 Berlin (Germany); Faiss, Siegbert [III. Medizinische Abteilung - Gastroenterologie und Hepatologie, Asklepios Klinik Barmbek, Rubenkamp 220, 22291 Hamburg (Germany); Schatz, Daniela; Berghof-Jäger, Kornelia [BIOTECON Diagnostics GmbH, Hermannswerder Haus 17, 14473 Potsdam (Germany); Steinberg, Pablo, E-mail: scholtka@uni-potsdam.de [Chair of Nutritional Toxicology, Institute of Nutritional Science, University of Potsdam, Arthur- Scheunert-Allee 114-116, 14558 Nuthetal (Germany); Institute for Food Toxicology and Analytical Chemistry, University of Veterinary Medicine Hannover, Bischofsholer Damm 15, 30173 Hannover (Germany)

2010-12-29

In the present study a recently conceived 4-gene marker panel covering the Wnt and Ras-Raf-MEK-MAPK signaling pathways was used to analyze 20 colorectal serrated lesions and 41 colorectal adenoma samples and to determine the percentage of each of the above-mentioned potentially precancerous lesions carrying at least one of the four above-mentioned genes in a mutated form. CTNNB1 and B-Raf were screened by PCR-single-strand conformation polymorphism analysis, K-Ras by restriction fragment length polymorphism analysis and the APC gene mutation cluster region (codons 1243–1567) by direct DNA sequencing. APC mutations were only detected in 10% of the serrated lesions but in 34% of the adenomas. Twenty percent of the serrated lesions and 14% of the adenomas carried a mutated K-Ras. B-Raf was found to be mutated in 50% of the serrated lesions and in 22% of the adenomas. CTNNB1 was altered in 12% of the adenomas, but not in serrated lesions. By using the above gene marker panel it could be shown that 65% of the serrated lesions and 61% of the adenomas carried at least one of the four genes in a mutated form. Based on its excellent performance in detecting mutations in sporadic preneoplastic (in this study) and neoplastic lesions (in a previous study) of the human colon and rectum, this primer combination might also be suited to efficiently and non-invasively detect genetic alterations in stool DNA of patients with early colorectal cancer.

Ras signaling in aging and metabolic regulation.

Science.gov (United States)

Slack, Cathy

2017-12-07

Aberrant signal transduction downstream of the Ras GTPase has a well-established role in tumorigenesis. Mutations that result in hyperactivation of Ras are responsible for a third of all human cancers. Hence, small molecule inhibitors of the Ras signal transduction cascade have been under intense focus as potential cancer treatments. In both invertebrate and mammalian models, emerging evidence has also implicated components of the Ras signaling pathway in aging and metabolic regulation. Here, I review the current evidence for Ras signaling in these newly discovered roles highlighting the interactions between the Ras pathway and other longevity assurance mechanisms. Defining the role of Ras signaling in maintaining age-related health may have important implications for the development of interventions that could not only increase lifespan but also delay the onset and/or progression of age-related functional decline.

Decrease in specific micronutrient intake in colorectal cancer patients with tumors presenting Ki-ras mutation

OpenAIRE

JORDI SALAS; NURIA LASO; SERGI MAS; M. JOSE LAFUENTE; XAVIER CASTERAD; MANUEL TRIAS; ANTONIO BALLESTA; RAFAEL MOLINA; CARLOS ASCASO; SHICHUN ZHENG; JOHN K. WIENCKE; AMALIA LAFUENTE

2004-01-01

Decrease in specific micronutrient intake in colorectal cancer patients with tumors presenting Ki-ras mutation BACKGROUND: The diversity of the Mediterranean diet and the heterogeneity of acquired genetic alterations in colorectal cancer (CRC) led us to examine the possible association between dietary factors and mutations, such as Ki-ras mutations, in genes implicated in the pathogenesis of these neoplasms. PATIENTS AND METHODS: The study was based on 246 cases and 296 controls. For th...

Preoperative RAS Mutational Analysis Is of Great Value in Predicting Follicular Variant of Papillary Thyroid Carcinoma

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Tae Sook Hwang

2015-01-01

Full Text Available Follicular variant of papillary thyroid carcinoma (FVPTC, particularly the encapsulated subtype, often causes a diagnostic dilemma. We reconfirmed the molecular profiles in a large number of FVPTCs and investigated the efficacy of the preoperative mutational analysis in indeterminate thyroid nodules. BRAF V600E/K601E and RAS mutational analysis was performed on 187 FVPTCs. Of these, 132 (70.6% had a point mutation in one of the BRAF V600E (n=57, BRAF K601E (n=11, or RAS (n=64 genes. All mutations were mutually exclusive. The most common RAS mutations were at NRAS codon 61. FNA aspirates from 564 indeterminate nodules were prospectively tested for BRAF and RAS mutation and the surgical outcome was correlated with the mutational status. Fifty-seven and 47 cases were positive for BRAF and RAS mutation, respectively. Twenty-seven RAS-positive patients underwent surgery and all except one patient had FVPTC. The PPV and accuracy of RAS mutational analysis for predicting FVPTC were 96% and 84%, respectively. BRAF or RAS mutations were present in more than two-thirds of FVPTCs and these were mutually exclusive. BRAF mutational analysis followed by N, H, and KRAS codon 61 mutational analysis in indeterminate thyroid nodules would streamline the management of patients with malignancies, mostly FVPTC.

A comparative investigation of DNA strand breaks, sister chromatid exchanges and K-ras gene mutations induced by cadmium salts in cultured human cells

International Nuclear Information System (INIS)

Mouron, Silvana Andrea; Grillo, Claudia Alejandra; Dulout, Fernando Noel; Golijow, Carlos Daniel

2004-01-01

Cadmium (Cd) is a toxic heavy metal of continuing occupational and environmental concern with a wide variety of adverse effects. Several studies have shown that cadmium produces DNA strand breaks, DNA-protein cross-links, oxidative DNA damage, chromosomal aberrations, dysregulation of gene expression resulting in enhanced proliferation, depressed apoptosis and/or altered DNA repair. This study was undertaken to investigate the ability of cadmium chloride (CdCl 2 ) and cadmium sulphate (CdSO 4 ) to induce point mutations in codon 12 of the K-ras protooncogene assessed by polymerase chain reaction-single strand conformation polymorphisms (PCR-SSCP) and RFLP-enriched PCR methods. Also their genotoxic effects were analyzed by the comet assay and sister chromatid exchanges test. The human lung fibroblast cell line MRC-5 was used for the experiments. Sister chromatid exchanges assay (SCEs) frequencies were significantly increased in cells exposed to cadmium salts in relation to controls (p < 0.001). Despite the slow increment observed in the three comet parameters considered when cells were treated with cadmium chloride, significant differences between groups were only found in the variable comet moment (CM) (p < 0.005). On the other hand, when cells were exposed to cadmium sulphate, the Kruskal-Wallis test showed highly significant differences between groups for migration, tail moment and comet moment parameters (p < 0.001). Nevertheless, a null or weak point mutation induction in K-ras protooncogene was detected using polymerase chain reaction-low ionic strength-single strand conformation polymorphisms (PCR-LIS-SSCP) and RFLP-enriched PCR methods when cells were treated with cadmium salts. Thus, inorganic cadmium produces genotoxicity in human lung fibroblast MRC-5 cells, in the absence of significant point mutation of the K-ras gene

Transformation of follicular lymphoma to plasmablastic lymphoma with c-myc gene rearrangement.

Science.gov (United States)

Ouansafi, Ihsane; He, Bing; Fraser, Cory; Nie, Kui; Mathew, Susan; Bhanji, Rumina; Hoda, Rana; Arabadjief, Melissa; Knowles, Daniel; Cerutti, Andrea; Orazi, Attilio; Tam, Wayne

2010-12-01

Follicular lymphoma (FL) is an indolent lymphoma that transforms to high-grade lymphoma, mostly diffuse large B-cell lymphoma, in about a third of patients. We present the first report of a case of FL that transformed to plasmablastic lymphoma (PBL). Clonal transformation of the FL to PBL was evidenced by identical IGH/BCL2 gene rearrangements and VDJ gene usage in rearranged IGH genes. IGH/ BCL2 translocation was retained in the PBL, which also acquired c-myc gene rearrangement. Genealogic analysis based on somatic hypermutation of the rearranged IGH genes of both FL and PBL suggests that transformation of the FL to PBL occurred most likely by divergent evolution from a common progenitor cell rather than direct evolution from the FL clone. Our study of this unusual case expands the histologic spectrum of FL transformation and increases our understanding of the pathogenetic mechanisms of transformation of indolent lymphomas to aggressive lymphomas.

Gene-Transformation-Induced Changes in Chemical Functional Group Features and Molecular Structure Conformation in Alfalfa Plants Co-Expressing Lc-bHLH and C1-MYB Transcriptive Flavanoid Regulatory Genes: Effects of Single-Gene and Two-Gene Insertion.

Science.gov (United States)

Heendeniya, Ravindra G; Yu, Peiqiang

2017-03-20

Alfalfa ( Medicago sativa L.) genotypes transformed with Lc-bHLH and Lc transcription genes were developed with the intention of stimulating proanthocyanidin synthesis in the aerial parts of the plant. To our knowledge, there are no studies on the effect of single-gene and two-gene transformation on chemical functional groups and molecular structure changes in these plants. The objective of this study was to use advanced molecular spectroscopy with multivariate chemometrics to determine chemical functional group intensity and molecular structure changes in alfalfa plants when co-expressing Lc-bHLH and C1-MYB transcriptive flavanoid regulatory genes in comparison with non-transgenic (NT) and AC Grazeland (ACGL) genotypes. The results showed that compared to NT genotype, the presence of double genes ( Lc and C1 ) increased ratios of both the area and peak height of protein structural Amide I/II and the height ratio of α-helix to β-sheet. In carbohydrate-related spectral analysis, the double gene-transformed alfalfa genotypes exhibited lower peak heights at 1370, 1240, 1153, and 1020 cm -1 compared to the NT genotype. Furthermore, the effect of double gene transformation on carbohydrate molecular structure was clearly revealed in the principal component analysis of the spectra. In conclusion, single or double transformation of Lc and C1 genes resulted in changing functional groups and molecular structure related to proteins and carbohydrates compared to the NT alfalfa genotype. The current study provided molecular structural information on the transgenic alfalfa plants and provided an insight into the impact of transgenes on protein and carbohydrate properties and their molecular structure's changes.

The Fourth International Symposium on Genetic Disorders of the Ras/MAPK pathway

NARCIS (Netherlands)

D.A. Stevenson (David A.); L. Schill (Lisa); L. Schoyer (Lisa); B.S. Andresen (B.); A. Bakker (Annette); P. Bayrak-Toydemir (Pinar); E.M.M. Burkitt Wright (Emma M.); K. Chatfield (Kathryn); F. Elefteriou (Florent); Y. Elgersma (Ype); M.J. Fisher (Michael J.); D. Franz (David); B.D. Gelb (Bruce); A. Goriely (Anne); K.W. Gripp (Karen); A.Y. Hardan (Antonio Y.); K.M. Keppler-Noreuil (Kim M.); B. Kerr (Bronwyn); B. Korf (Bruce); C. Leoni (Chiara); F. Mccormick (Frank); S.R. Plotkin (Scott R.); K.A. Rauen (Katherine); K. Reilly (Karlyne); A.E. Roberts; A. Sandler (Abby); D. Siegel (Dawn); K.S. Walsh (Karin S.); B.C. Widemann (Brigitte C.)

2016-01-01

textabstractThe RASopathies are a group of disorders due to variations of genes associated with the Ras/MAPK pathway. Some of the RASopathies include neurofibromatosis type 1 (NF1), Noonan syndrome, Noonan syndrome with multiple lentigines, cardiofaciocutaneous (CFC) syndrome, Costello syndrome,

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

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Pileggi Marcos

2001-01-01

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

Autonomous and Non-autonomous Defects Underlie Hypertrophic Cardiomyopathy in BRAF-Mutant hiPSC-Derived Cardiomyocytes

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Rebecca Josowitz

2016-09-01

Full Text Available Germline mutations in BRAF cause cardio-facio-cutaneous syndrome (CFCS, whereby 40% of patients develop hypertrophic cardiomyopathy (HCM. As the role of the RAS/MAPK pathway in HCM pathogenesis is unclear, we generated a human induced pluripotent stem cell (hiPSC model for CFCS from three patients with activating BRAF mutations. By cell sorting for SIRPα and CD90, we generated a method to examine hiPSC-derived cell type-specific phenotypes and cellular interactions underpinning HCM. BRAF-mutant SIRPα+/CD90− cardiomyocytes displayed cellular hypertrophy, pro-hypertrophic gene expression, and intrinsic calcium-handling defects. BRAF-mutant SIRPα−/CD90+ cells, which were fibroblast-like, exhibited a pro-fibrotic phenotype and partially modulated cardiomyocyte hypertrophy through transforming growth factor β (TGFβ paracrine signaling. Inhibition of TGFβ or RAS/MAPK signaling rescued the hypertrophic phenotype. Thus, cell autonomous and non-autonomous defects underlie HCM due to BRAF mutations. TGFβ inhibition may be a useful therapeutic option for patients with HCM due to RASopathies or other etiologies.

Transient transformation meets gene function discovery: the strawberry fruit case

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Michela eGuidarelli

2015-06-01

Full Text Available Beside the well known nutritional and health benefits, strawberry (Fragaria X ananassa crop draws increasing attention as plant model system for the Rosaceae family, due to the short generation time, the rapid in vitro regeneration, and to the availability of the genome sequence of F. X ananassa and of the closely related F. vesca species. In the last years, the use of high-throughput sequence technologies provided large amounts of molecular information on the genes possibly related to several biological processes of this crop. Nevertheless, the function of most genes or gene products is still poorly understood and needs investigation. Transient transformation technology provides a powerful tool to study gene function in vivo, avoiding difficult drawbacks that typically affect the stable transformation protocols, such as transformation efficiency, transformants selection and regeneration. In this review we provide an overview of the use of transient expression in the investigation of the function of genes important for strawberry fruit development, defence and nutritional properties. The technical aspects related to an efficient use of this technique are described, and the possible impact and application in strawberry crop improvement are discussed.

Characterization of mutations and loss of heterozygosity of p53 and K-ras2 in pancreatic cancer cell lines by immobilized polymerase chain reaction

Directory of Open Access Journals (Sweden)

Edwards Jeremy

2003-07-01

Full Text Available Abstract Background The identification of known mutations in a cell population is important for clinical applications and basic cancer research. In this work an immobilized form of the polymerase chain reaction, referred to as polony technology, was used to detect mutations as well as gene deletions, resulting in loss of heterozygosity (LOH, in cancer cell lines. Specifically, the mutational hotspots in p53, namely codons 175, 245, 248, 249, 273, and 282, and K-ras2, codons 12, 13 and 61, were genotyped in the pancreatic cell line, Panc-1. In addition LOH analysis was also performed for these same two genes in Panc-1 by quantifying the relative gene copy number of p53 and K-ras2. Results Using polony technology, Panc-1 was determined to possess only one copy of p53, which possessed a mutation in codon 273, and two copies of K-ras2, one wildtype and one with a mutation in codon 12. To further demonstrate the general approach of this method, polonies were also used to detect K-ras2 mutations in the pancreatic cell lines, AsPc-1 and CAPAN-1. Conclusions In conclusion, we have developed an assay that can detect mutations in hotspots of p53 and K-ras2 as well as diagnose LOH in these same genes.

The gene transformer-2 of Sciara (Diptera, Nematocera) and its effect on Drosophila sexual development.

Science.gov (United States)

Martín, Iker; Ruiz, María F; Sánchez, Lucas

2011-03-15

The gene transformer-2, which is involved in sex determination, has been studied in Drosophila, Musca, Ceratitis, Anastrepha and Lucilia. All these members of Diptera belong to the suborder Brachycera. In this work, it is reported the isolation and characterisation of genes transformer-2 of the dipterans Sciara ocellaris and Bradysia coprophila (formerly Sciara coprophila), which belong to the much less extensively analysed Sciaridae Family of the Suborder Nematocera, which is paraphyletic with respect to Suborder Brachycera. The transformer-2 genes of the studied Sciara species were found to be transcribed in both sexes during development and adult life, in both the soma and germ lines. They produced a single primary transcript, which follows the same alternative splicing in both sexes, giving rise to different mRNAs isoforms. In S. ocellaris the most abundant mRNA isoform encoded a full-length protein of 251 amino acids, while that of B. coprophila encoded a protein of 246 amino acids. Both showed the features of the SR protein family. The less significant mRNA isoforms of both species encoded truncated, presumably non-functional Transformer-2 proteins. The comparison of the functional Sciara Transformer-2 proteins among themselves and those of other insects revealed the greatest degree of conservation in the RRM domain and linker region. In contrast, the RS1 and RS2 domains showed extensive variation with respect to their number of amino acids and their arginine-serine (RS) dipeptide content. The expression of S. ocellaris Transformer-2 protein in Drosophila XX pseudomales lacking the endogenous transformer-2 function caused their partial feminisation. The transformer-2 genes of both Sciaridae species encode a single protein in both sexes that shares the characteristics of the Transformer-2 proteins of other insects. These proteins showed conserved sex-determination function in Drosophila; i.e., they were able to form a complex with the endogenous Drosophila

ACE variants interact with the RAS pathway to confer risk and protection against type 2 diabetic nephropathy

DEFF Research Database (Denmark)

Ahluwalia, Tarun Veer Singh; Ahuja, Monica; Rai, Taranjit Singh

2009-01-01

Genetic predisposition has been proposed to be a major determinant in the development of renal complications of diabetes. Among candidate genes examined for susceptibility to diabetic nephropathy, angiotensin-converting enzyme (ACE) gene has been found to be associated with pathogenesis......, in the present study, we evaluated the association of ACE haplotypes and the interactions of ACE, angiotensinogen (AGT), and angiotensin II receptor type I (AGTR1) gene polymorphisms with DNP in Asian Indians. We genotyped seven variants of the RAS pathway genes (ACE, AGT, and AGTR1) in type 2 diabetic cohorts...... and progression of diabetic nephropathy. However, the role of other renin-angiotensin system (RAS) polymorphisms and their possible interactions with different ACE I/D genotypes are less clearly defined. Recent studies also show that ACE haplotypes may be better predictors to disease susceptibility. Thus...

An orthosteric inhibitor of the RAS-SOS interaction.

Science.gov (United States)

Nickerson, Seth; Joy, Stephen T; Arora, Paramjit S; Bar-Sagi, Dafna

2013-01-01

Rat sarcoma (RAS) proteins are signaling nodes that transduce extracellular cues into precise alterations in cellular physiology by engaging effector pathways. RAS signaling thus regulates diverse cell processes including proliferation, migration, differentiation, and survival. Owing to this central role in governing mitogenic signals, RAS pathway components are often dysregulated in human diseases. Targeted therapy of RAS pathways has generally not been successful, largely because of the robust biochemistry of the targets and their multifaceted network of molecular regulators. The rate-limiting step of RAS activation is Son of Sevenless (SOS)-mediated nucleotide exchange involving a single evolutionarily conserved catalytic helix from SOS. Structure function data of this mechanism provided a strong platform to design an SOS-derived, helically constrained peptide mimic as an inhibitor of the RAS-SOS interaction. In this chapter, we review RAS-SOS signaling dynamics and present evidence supporting the novel paradigm of inhibiting their interaction as a therapeutic strategy. We then describe a method of generating helically constrained peptide mimics of protein surfaces, which we have employed to inhibit the RAS-SOS active site interaction. The biochemical and functional properties of this SOS mimic support the premise that inhibition of RAS-nucleotide exchange can effectively block RAS activation and downstream signaling. © 2013 Elsevier Inc. All rights reserved.

RAS - Screens & Assays - Drug Discovery

Science.gov (United States)

The RAS Drug Discovery group aims to develop assays that will reveal aspects of RAS biology upon which cancer cells depend. Successful assay formats are made available for high-throughput screening programs to yield potentially effective drug compounds.

Efficient transformation and expression of gfp gene in Valsa mali var. mali.

Science.gov (United States)

Chen, Liang; Sun, Gengwu; Wu, Shujing; Liu, Huixiang; Wang, Hongkai

2015-01-01

Valsa mali var. mali, the causal agent of valsa canker of apple, causes great loss of apple production in apple producing regions. The pathogenic mechanism of the pathogen has not been studied extensively, thus a suitable gene marker for pathogenic invasion analysis and a random insertion of T-DNA for mutants are desirable. In this paper, we reported the construction of a binary vector pKO1-HPH containing a positive selective gene hygromycin phosphotransferase (hph), a reporter gene gfp conferring green fluorescent protein, and an efficient protocol for V. mali var. mali transformation mediated by Agrobacterium tumefaciens. A transformation efficiency up to about 75 transformants per 10(5) conidia was achieved when co-cultivation of V. mali var. mali and A. tumefaciens for 48 h in A. tumefaciens inductive medium agar plates. The insertions of hph gene and gfp gene into V. mali var. mali genome verified by polymerase chain reaction and southern blot analysis showed that 10 randomly-selected transformants exhibited a single, unique hybridization pattern. This is the first report of A. tumefaciens-mediated transformation of V. mali var mali carrying a 'reporter' gfp gene that stably and efficiently expressed in the transformed V. mali var. mali species.

Angiotensin peptides in the non-gravid uterus: Paracrine actions beyond circulation.

Science.gov (United States)

Casalechi, Maíra; Dela Cruz, Cynthia; Lima, Luiza C; Maciel, Luciana P; Pereira, Virgínia M; Reis, Fernando M

2018-03-01

The renin-angiotensin system (RAS) involves a complex network of precursors, peptides, enzymes and receptors comprising a systemic (endocrine) and a local (paracrine/autocrine) system. The local RAS plays important roles in tissue modulation and may operate independently of or in close interaction with the circulatory RAS, acting in a complementary fashion. Angiotensin (Ang) II, its receptor AT 1 and Ang-(1-7) expression in the endometrium vary with menstrual cycle, and stromal cell decidualization in vitro is accompanied by local synthesis of angiotensinogen and prorenin. Mas receptor is unlikely to undergo marked changes accompanying the cyclic ovarian steroid hormone fluctuations. Studies investigating the functional relevance of the RAS in the non-gravid uterus show a number of paracrine effects beyond circulation and suggest that RAS peptides may be involved in the pathophysiology of proliferative and fibrotic diseases. Endometrial cancer is associated with increased expression of Ang II, Ang-converting enzyme 1 and AT 1 in the tumoral tissue compared to neighboring non-neoplastic endometrium, and also with a gene polymorphism that enhances AT 1 signal. Ang II induces human endometrial cells to transdifferentiate into cells with myofibroblast phenotype and to synthetize extracellular matrix components that might contribute to endometrial fibrosis. Altogether, these findings point to a fully operating RAS within the uterus, but since many concepts rely on preliminary evidence further studies are needed to clarify the role of the local RAS in uterine physiology and pathophysiology. Copyright © 2018 Elsevier Inc. All rights reserved.

Gain-of-function mutations in RIT1 cause Noonan syndrome, a RAS/MAPK pathway syndrome.

Science.gov (United States)

Aoki, Yoko; Niihori, Tetsuya; Banjo, Toshihiro; Okamoto, Nobuhiko; Mizuno, Seiji; Kurosawa, Kenji; Ogata, Tsutomu; Takada, Fumio; Yano, Michihiro; Ando, Toru; Hoshika, Tadataka; Barnett, Christopher; Ohashi, Hirofumi; Kawame, Hiroshi; Hasegawa, Tomonobu; Okutani, Takahiro; Nagashima, Tatsuo; Hasegawa, Satoshi; Funayama, Ryo; Nagashima, Takeshi; Nakayama, Keiko; Inoue, Shin-Ichi; Watanabe, Yusuke; Ogura, Toshihiko; Matsubara, Yoichi

2013-07-11

RAS GTPases mediate a wide variety of cellular functions, including cell proliferation, survival, and differentiation. Recent studies have revealed that germline mutations and mosaicism for classical RAS mutations, including those in HRAS, KRAS, and NRAS, cause a wide spectrum of genetic disorders. These include Noonan syndrome and related disorders (RAS/mitogen-activated protein kinase [RAS/MAPK] pathway syndromes, or RASopathies), nevus sebaceous, and Schimmelpenning syndrome. In the present study, we identified a total of nine missense, nonsynonymous mutations in RIT1, encoding a member of the RAS subfamily, in 17 of 180 individuals (9%) with Noonan syndrome or a related condition but with no detectable mutations in known Noonan-related genes. Clinical manifestations in the RIT1-mutation-positive individuals are consistent with those of Noonan syndrome, which is characterized by distinctive facial features, short stature, and congenital heart defects. Seventy percent of mutation-positive individuals presented with hypertrophic cardiomyopathy; this frequency is high relative to the overall 20% incidence in individuals with Noonan syndrome. Luciferase assays in NIH 3T3 cells showed that five RIT1 alterations identified in children with Noonan syndrome enhanced ELK1 transactivation. The introduction of mRNAs of mutant RIT1 into 1-cell-stage zebrafish embryos was found to result in a significant increase of embryos with craniofacial abnormalities, incomplete looping, a hypoplastic chamber in the heart, and an elongated yolk sac. These results demonstrate that gain-of-function mutations in RIT1 cause Noonan syndrome and show a similar biological effect to mutations in other RASopathy-related genes. Copyright © 2013 The American Society of Human Genetics. Published by Elsevier Inc. All rights reserved.

Alphavirus production is inhibited in neurofibromin 1-deficient cells through activated RAS signalling

International Nuclear Information System (INIS)

Kolokoltsova, Olga A.; Domina, Aaron M.; Kolokoltsov, Andrey A.; Davey, Robert A.; Weaver, Scott C.; Watowich, Stanley J.

2008-01-01

Virus-host interactions essential for alphavirus pathogenesis are poorly understood. To address this shortcoming, we coupled retrovirus insertional mutagenesis and a cell survival selection strategy to generate clonal cell lines broadly resistant to Sindbis virus (SINV) and other alphaviruses. Resistant cells had significantly impaired SINV production relative to wild-type (WT) cells, although virus binding and fusion events were similar in both sets of cells. Analysis of the retroviral integration sites identified the neurofibromin 1 (NF1) gene as disrupted in alphavirus-resistant cell lines. Subsequent analysis indicated that expression of NF1 was significantly reduced in alphavirus-resistant cells. Importantly, independent down-regulation of NF1 expression in WT HEK 293 cells decreased virus production and increased cell viability during SINV infection, relative to infected WT cells. Additionally, we observed hyperactive RAS signalling in the resistant HEK 293 cells, which was anticipated because NF1 is a negative regulator of RAS. Expression of constitutively active RAS (HRAS-G12V) in a WT HEK 293 cell line resulted in a marked delay in virus production, compared with infected cells transfected with parental plasmid or dominant-negative RAS (HRAS-S17N). This work highlights novel host cell determinants required for alphavirus pathogenesis and suggests that RAS signalling may play an important role in neuronal susceptibility to SINV infection

CREBBP knockdown enhances RAS/RAF/MEK/ERK signaling in Ras pathway mutated acute lymphoblastic leukemia but does not modulate chemotherapeutic response.

Science.gov (United States)

Dixon, Zach A; Nicholson, Lindsay; Zeppetzauer, Martin; Matheson, Elizabeth; Sinclair, Paul; Harrison, Christine J; Irving, Julie A E

2017-04-01

Relapsed acute lymphoblastic leukemia is the most common cause of cancer-related mortality in young people and new therapeutic strategies are needed to improve outcome. Recent studies have shown that heterozygous inactivating mutations in the histone acetyl transferase, CREBBP , are particularly frequent in relapsed childhood acute lymphoblastic leukemia and associated with a hyperdiploid karyotype and KRAS mutations. To study the functional impact of CREBBP haploinsufficiency in acute lymphoblastic leukemia, RNA interference was used to knock down expression of CREBBP in acute lymphoblastic leukemia cell lines and various primagraft acute lymphoblastic leukemia cells. We demonstrate that attenuation of CREBBP results in reduced acetylation of histone 3 lysine 18, but has no significant impact on cAMP-dependent target gene expression. Impaired induction of glucocorticoid receptor targets was only seen in 1 of 4 CREBBP knockdown models, and there was no significant difference in glucocorticoid-induced apoptosis, sensitivity to other acute lymphoblastic leukemia chemotherapeutics or histone deacetylase inhibitors. Importantly, we show that CREBBP directly acetylates KRAS and that CREBBP knockdown enhances signaling of the RAS/RAF/MEK/ERK pathway in Ras pathway mutated acute lymphoblastic leukemia cells, which are still sensitive to MEK inhibitors. Thus, CREBBP mutations might assist in enhancing oncogenic RAS signaling in acute lymphoblastic leukemia but do not alter response to MEK inhibitors. Copyright© Ferrata Storti Foundation.

Generalized ward identities for non-local transformation

International Nuclear Information System (INIS)

Li Ziping; Li Ruijie

2002-01-01

Based on the phase-space generating functional of Green function for a system with a singular higher-order Lagrangian, the generalized canonical Ward identities under the local and non-local transformation in phase space for such a system have been derived. Starting from the configuration-space generating functional for a gauge-invariant system, the generalized Ward identities were deduced under the local, non-local and global transformation, respectively. The applications to the non-Abelian Chern-Simons theories with higher derivatives were given. Some relationships among the proper vertices have been deduced, in which one does not need to carry out the integration over canonical momenta in phase-space generating functional. The Ward-Takahashi identities for BRS transformation are also obtained

Analog reactor simulator RAS; Reaktorski analogni simulator RAS

Energy Technology Data Exchange (ETDEWEB)

Radanovic, Lj; Bingulac, S; Popovic, D [The Institute of Nuclear Sciences Boris Kidric, Vinca, Beograd (Yugoslavia)

1961-07-01

Analog computer RAS was designed as a nuclear reactor simulator, but it can be simultaneously used for solving a number of other problems. This paper contains a brief description of the simulator parts and their principal characteristics.

[Regulation of [12Asp]K-ras4B on transcriptional activity of estrogen receptor in endometrial carcinoma HEC-1A cell lines].

Science.gov (United States)

Gui, Li-ming; Wei, Li-hui; Xu, Ming-xu; Wang, Jian-liu; Zhong, Ying-cheng; Li, Xiao-ping; Tu, Zheng; Sun, Peng-ming; Ma, Da-long

2004-01-01

To investigate the effect of mutant-type [(12)Asp]K-ras4B gene on the expression of estrogen receptor (ER) alpha and beta and their transcriptional activity as a transcription factor in endometrial carcinoma HEC-1A cell line. (1) Effect of [(12)Asp]K-ras4B on the expression of ER alpha and beta were determined using Western blot assay. (2) Eukaryotic expression plasmid pGL3-luciferase-ERE containing luciferase report gene and estrogen receptor element (ERE) was constructed, and co-transfected into NIH3T3 and HEC-1A cell lines with pEGFP-N1 to examine the effect of [(12)Asp]K-ras4B on ER transcription that is regulated by estradiol. In addition, they were transfected into pSV5-HER0 (containing full length wide type ERalpha cDNA) and pCMV-rafS621A (inhibiting raf kinase) plasmids to test the effect of [(12)Asp]K-ras4B/raf signal pathway on transcriptional activity of ER proteins. (1) Protein level of ERs expressed in pcDI transfected control cells was low while it was increased for 3.6-fold (97 +/- 25, 349 +/- 67, P ras4B NIH3T3 cells after transfection. (2) In pcDI-[(12)Asp]K-ras4B NIH3T3 cells, the ratios for ERalpha and and ERbeta levels before transfection of rafS621A plasmids to that after the transfection, were 2.4:1 (724 +/- 45, 310 +/- 46, P HEC-1A cells, these ratios were 2.1:1 (566 +/- 22, 279 +/- 30, P ras4B NIH3T3 cells, 19-fold (141 +/- 39, 2644 +/- 331, P HEC-1A cells, respectively, when compared with those in the absence of E(2). (4) In pSV5-HER0 transfected pcDI-[(12)Asp] K-ras4B NIH3T3 cells and HEC-1A cells, compared to the untransfected cells, the ER transcriptional activity in the transfected cells increased markedly. The luciferase activity was increased for 8-fold (1048 +/- 91, 8099 +/- 452, P HEC-1A cells and pcDI-[(12)Asp]K-ras4B NIH3T3 cells. The ratio of luciferase activities in pcDI-[(12)Asp]K-ras4B NIH3T3 and HEC-1A cells, before and after transfection was 7.8:1 (1184 +/- 168, 152 +/- 27, P ras4B can enhance the expression of ERalpha and

Using the capital markets in Ras Gas

International Nuclear Information System (INIS)

Voge, B.; Penzer, M.

1997-01-01

In December 1996, Ras Laffan Liquefied Natural Gas Company Ltd (Ras Gas) closed a multi-source financing that included an offering of US$1.2bn of bonds. The sponsors of the Ras Gas project overcame a number of obstacles on the road to closing the capital markets offering. This article provides a general overview of capital markets offerings in international project financings and discusses how Ras Gas was able to successfully integrate a capital markets offering into a financing plan which included a commercial bank facility and several export-credit agency facilities. (Author)

The Ras suppressor-1 (RSU-1 in cancer

Directory of Open Access Journals (Sweden)

Lefteris C Zacharia

2017-04-01

Full Text Available Primary tumors are seldom the cause of death for cancer patients as most patients die from metastatic disease. Thus, deciphering metastatic mechanisms and key molecules involved is of utmost importance for the improved survival of cancer patients. Metastasis is a complex process in which cancer cells dissociate from the original tumor and spread to distant sites of the body. During the metastatic process, cancer cells lose contact both with the extracellular matrix (ECM and the neighboring cells within the primary tumor, thus invading though surrounding tissues. Therefore, ECM, and ECM-related adhesion proteins play a critical role in the metastatic process. Ras suppressor-1 (RSU-1 was first identified as a suppressor of Ras-dependent oncogenic transformation and is localized to cell-ECM adhesions where it is known to interact with the pro-survival adhesion protein PINCH-1. Although the connection to cancer is obvious, little is known regarding its expression in various cancer types. This opinion piece is focusing on recent literature regarding the expression of RSU-1 in various cancer types and the possible molecular mechanism of its action, pointing towards questions that need still to be addressed in this research field.

Study on transformation of cowpea trypsin inhibitor gene into ...

African Journals Online (AJOL)

Cowpea Trypsin Inhibitor (CpTI) gene was transferred into cauliflower by agrobacterium-mediated transformation method, and 14 transgenic cauliflower plants were obtained. Cotyledons and hypocotyls were used as explants. The putative transformants were assayed by PCR and Southern blotting analysis. The results ...

Inhibition of RAS in diabetic nephropathy

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Yacoub R

2015-04-01

Full Text Available Rabi Yacoub, Kirk N Campbell Department of Medicine, Division of Nephrology, Icahn School of Medicine at Mount Sinai, New York, NY, USA Abstract: Diabetic kidney disease (DKD is a progressive proteinuric renal disorder in patients with type 1 or type 2 diabetes mellitus. It is a common cause of end-stage kidney disease worldwide, particularly in developed countries. Therapeutic targeting of the renin–angiotensin system (RAS is the most validated clinical strategy for slowing disease progression. DKD is paradoxically a low systematic renin state with an increased intrarenal RAS activity implicated in its pathogenesis. Angiotensin II (AngII, the main peptide of RAS, is not only a vasoactive peptide but functions as a growth factor, activating interstitial fibroblasts and mesangial and tubular cells, while promoting the synthesis of extracellular matrix proteins. AngII also promotes podocyte injury through increased calcium influx and the generation of reactive oxygen species. Blockade of the RAS using either angiotensin converting enzyme inhibitors, or angiotensin receptor blockers can attenuate progressive glomerulosclerosis in animal models, and slows disease progression in humans with DKD. In this review, we summarize the role of intrarenal RAS activation in the pathogenesis and progression of DKD and the rationale for RAS inhibition in this population. Keywords: renin–angiotensin system, diabetic kidney disease, angiotensin II, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers

Coupling between p210bcr-abl and Shc and Grb2 adaptor proteins in hematopoietic cells permits growth factor receptor-independent link to ras activation pathway.

Science.gov (United States)

Tauchi, T; Boswell, H S; Leibowitz, D; Broxmeyer, H E

1994-01-01

Enforced expression of p210bcr-abl transforms interleukin 3 (IL-3)-dependent hematopoietic cell lines to growth factor-independent proliferation. It has been demonstrated that nonreceptor tyrosine kinase oncogenes may couple to the p21ras pathway to exert their transforming effect. In particular, p210bcr-abl was recently found to effect p21ras activation in hematopoietic cells. In this context, experiments were performed to evaluate a protein signaling pathway by which p210bcr-abl might regulate p21ras. It was asked whether Shc p46/p52, a protein containing a src-homology region 2 (SH2) domain, and known to function upstream from p21ras, might form specific complexes with p210bcr-abl and thus, possibly alter p21ras activity by coupling to the guanine nucleotide exchange factor (Sos/CDC25) through the Grb2 protein-Sos complex. This latter complex has been previously demonstrated to occur ubiquitously. We found that p210bcr-abl formed a specific complex with Shc and with Grb2 in three different murine cell lines transfected with a p210bcr-abl expression vector. There appeared to be a higher order complex containing Shc, Grb2, and bcr-abl proteins. In contrast to p210bcr-abl transformed cells, in which there was constitutive tight association between Grb2 and Shc, binding between Grb2 and Shc was Steel factor (SLF)-dependent in a SLF-responsive, nontransformed parental cell line. The SLF-dependent association between Grb2 and Shc in nontransformed cells involved formation of a complex of Grb2 with c-kit receptor after SLF treatment. Thus, p210bcr-abl appears to function in a hematopoietic p21ras activation pathway to allow growth factor-independent coupling between Grb2, which exists in a complex with the guanine nucleotide exchange factor (Sos), and p21ras. Shc may not be required for Grb2-c-kit interaction, because it fails to bind strongly to c-kit.

Parental exposure to medications and hydrocarbons and ras mutations in children with acute lymphoblastic leukemia: A report from the Children's Oncology Group

Energy Technology Data Exchange (ETDEWEB)

Shu, X.O.; Perentesis, J.P.; Wen, W.Q.; Buckley, J.D.; Boyle, E.; Ross, J.A.; Robison, L.L. [Childrens Oncology Group, Arcadia, CA (United States)

2004-07-01

Using data from a large case-control study of childhood acute lymphoblastic leukemia (ALL; age < 15 years), we used a case-case comparison approach to examine whether reported parental exposure to hydrocarbons at work or use of specific medications are related to ras gene mutations in the leukemia cells of children with ALL. We examined mutations in K-ras and N-ras genes atcodons 12, 13, and 61 by PCR and allele-specific oligonucleotide hybridization and confirmed them by DNA sequencing. Odds ratios (ORs) and 95% confidence intervals (CIs) were derived from logistic regression to examine the association of parental exposures with ras mutations. A total of 127 (15.2%) cases had ras mutations (K-ras 4.7% and N-ras 10.68%). Both maternal (OR 3.2,95% CI 1.7-6.1) and paternal (OR 2.0, 95% CI 1.1-3.7) reported use of mind-altering drugs were associated with N-ras mutations. Paternal use of amphetamines or diet pills was associated with N-ras mutations (OR 4.1, 95% CI 1.1-15.0). Maternal exposure to solvents (OR 3.1, 95% CI 1.0-9.7) and plastic materials (OR 6.9, 95% CI 1.2-39.7) during pregnancy and plastic materials after pregnancy (OR 8.3, 95% CI 1.4-48.8) were related to K-ras mutation. Maternal over exposure to oil and coal products before case diagnosis (OR 2.3, 95% CI 1.1-4.8) and during the postnatal period (OR 2.2, 95% CI 1.0-5.5) and paternal exposure to plastic materials before index pregnancy (OR 2.4, 95% CI 1.1-5.1) and other hydrocarbons during the postnatal period (OR 1.8, 95% CI 1.0-1.3) were associated with N-ras mutations. This study suggests that parental exposure to specific chemicals may be associated with distinct ras mutations in children who develop ALL.

Renal Artery Stenosis (RAS) Case study

International Nuclear Information System (INIS)

Zaater, M.K.

2012-01-01

Renal Artery Stenosis (RAS), is one of the causes of secondary hypertension; there are many causes of renal artery stenosis, as atherosclerosis of the renal artery which account for 90% of cases of RAS; fibromuscular dysplasia accounts for 10% of RAS. Various causes of thrombophilia either due congenital causes or acquired causes and can lead to RAS. Our patient was presented by acute attack of epistaxis and hypertension. Angiography of the Renal Arteries,are showed no sign of renal artery stenosis. However, the right kidney showed upper pole infarction, and the left kidney showed evidence of functional lower pole renal artery stenosis, although there is no anatomical stenosis detected in angiography. Work up for the cause of thrombophilia did not help in the diagnosis, which may be due to an undiscovered cause of thrombophilia

Demonstration of pb-PSHA with Ras-Elhekma earthquake, Egypt

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Elsayed Fergany

2017-06-01

Full Text Available The main goal of this work is to: (1 argue for the importance of a physically-based probabilistic seismic hazard analysis (pb-PSHA methodology and show examples to support the argument from recent events, (2 demonstrate the methodology with the ground motion simulations of May 28, 1998, Mw = 5.5 Ras-Elhekma earthquake, north Egypt. The boundaries for the possible rupture parameters that may have been identified prior to the 1998 Ras-Elhekma earthquake were estimated. A range of simulated ground-motions for the Ras-Elhekma earthquake was “predicted” for frequency 0.5–25 Hz at three sites, where the large earthquake was recorded, with average epicentral distances of 220 km. The best rupture model of the 1998 Ras-Elhekma earthquake was identified by calculated the goodness of fit between observed and synthesized records at sites FYM, HAG, and KOT. We used the best rupture scenario of the 1998 earthquake to synthesize the ground motions at interested sites where the main shock was not recorded. Based on the good fit of simulated and observed seismograms, we concluded that this methodology can provide realistic ground motion of an earthquake and highly recommended for engineering purposes in advance or foregoing large earthquakes at non record sites. We propose that there is a need for this methodology for good-representing the true hazard with reducing uncertainties.

Molecular analysis of p53 and K-ras in lung carcinomas of coal miners

Energy Technology Data Exchange (ETDEWEB)

Sarkar, F.H.; Li, Y.W.; Vallyathan, V. [Wayne State University, Detroit, MI (United States). School of Medicine, Dept. of Pathology

2001-10-01

Thirty-three cases of non-small cell lung cancers (NSCLC) from the archives of National Coal Workers' Autopsy Study were studied for mutational alterations in p53 and K-ras using PCR-SSCP, DNA sequencing and PCR-oligonucleotide probe hybridization techniques. Mutations of the p53 were observed in 4 smokers (19%) and one in a never smoker (8%). Two polymorphisms in smokers were detected at codon 213, a common site for sequence variation. Among the smokers the p53 mutations were in the heavy smokers. In never smokers there was only a single p53 mutation and two K-ras mutations. In never smokers the frequency of K-ras mutations was similar (17%) in smokers, but one never smoker had two K-ras mutations. Mutations of p53 were more frequent in adenocarcinomas (27%) and they were AT-GC transitions. There were two large cell undifferentiated carcinomas with p53 mutation and one with a K-ras mutation. Two of the 16 squamous cell carcinomas were positive for p53 mutation, while no K-ras mutations were found in this group. The results of these preliminary studies indicate a moderately different mutational spectrum of p53 and K-ras in coal miners independent of cigarette smoking. The mutational spectrum observed in this study of coal miners with heavy cigarette smoking history suggest a protective effect of coal mine dust in preventing abnormal mutations induced by chemical carcinogens in cigarette smoke or reactive oxygen species.

The inflammatory cytokine TNFα cooperates with Ras in elevating metastasis and turns WT-Ras to a tumor-promoting entity in MCF-7 cells

International Nuclear Information System (INIS)

Leibovich-Rivkin, Tal; Liubomirski, Yulia; Meshel, Tsipi; Abashidze, Anastasia; Brisker, Daphna; Solomon, Hilla; Rotter, Varda; Weil, Miguel; Ben-Baruch, Adit

2014-01-01

In the present study we determined the relative contribution of two processes to breast cancer progression: (1) Intrinsic events, such as activation of the Ras pathway and down-regulation of p53; (2) The inflammatory cytokines TNFα and IL-1β, shown in our published studies to be highly expressed in tumors of >80% of breast cancer patients with recurrent disease. Using MCF-7 human breast tumor cells originally expressing WT-Ras and WT-p53, we determined the impact of the above-mentioned elements and cooperativity between them on the expression of CXCL8 (ELISA, qRT-PCR), a member of a “cancer-related chemokine cluster” that we have previously identified. Then, we determined the mechanisms involved (Ras-binding-domain assays, Western blot, luciferase), and tested the impact of Ras + TNFα on angiogenicity (chorioallantoic membrane assays) and on tumor growth at the mammary fat pad of mice and on metastasis, in vivo. Using Ras G12V that recapitulates multiple stimulations induced by receptor tyrosine kinases, we found that Ras G12V alone induced CXCL8 expression at the mRNA and protein levels, whereas down-regulation of p53 did not. TNFα and IL-1β potently induced CXCL8 expression and synergized with Ras G12V , together leading to amplified CXCL8 expression. Testing the impact of WT-Ras, which is the common form in breast cancer patients, we found that WT-Ras was not active in promoting CXCL8; however, TNFα has induced the activation of WT-Ras: joining these two elements has led to cooperative induction of CXCL8 expression, via the activation of MEK, NF-κB and AP-1. Importantly, TNFα has led to increased expression of WT-Ras in an active GTP-bound form, with properties similar to those of Ras G12V . Jointly, TNFα + Ras activities have given rise to increased angiogenesis and to elevated tumor cell dissemination to lymph nodes. TNFα cooperates with Ras in promoting the metastatic phenotype of MCF-7 breast tumor cells, and turns WT-Ras into a tumor

Animal products and K-ras codon 12 and 13 mutations in colon carcinomas

NARCIS (Netherlands)

Kampman, E.; Voskuil, D.W.; Kraats, A.A. van; Balder, H.F.; Muijen, G.N.P. van; Goldbohm, R.A.; Veer, P. van 't

2000-01-01

K-ras gene mutations (codons 12 and 13) were determined by PCR-based mutant allele-specific amplification (MASA) in tumour tissue of 185 colon cancer patients: 36% harboured mutations, of which 82% were located in codon 12. High intakes of animal protein, calcium and poultry were differently

EMT-induced stemness and tumorigenicity are fueled by the EGFR/Ras pathway.

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Dominic Chih-Cheng Voon

Full Text Available Recent studies have revealed that differentiated epithelial cells would acquire stem cell-like and tumorigenic properties following an Epithelial-Mesenchymal Transition (EMT. However, the signaling pathways that participate in this novel mechanism of tumorigenesis have not been fully characterized. In Runx3 (-/- p53 (-/- murine gastric epithelial (GIF-14 cells, EMT-induced plasticity is reflected in the expression of the embryonal proto-oncogene Hmga2 and Lgr5, an exclusive gastrointestinal stem cell marker. Here, we report the concurrent activation of an EGFR/Ras gene expression signature during TGF-β1-induced EMT in GIF-14 cells. Amongst the altered genes was the induction of Egfr, which corresponded with a delayed sensitization to EGF treatment in GIF-14. Co-treatment with TGF-β1 and EGF or the expression of exogenous KRas led to increased Hmga2 or Lgr5 expression, sphere initiation and colony formation in soft agar assay. Interestingly, the gain in cellular plasticity/tumorigenicity was not accompanied by increased EMT. This uncoupling of EMT and the induction of plasticity reveals an involvement of distinct signaling cues, whereby the EGFR/Ras pathway specifically promotes stemness and tumorigenicity in EMT-altered GIF-14 cells. These data show that the EGFR/Ras pathway requisite for the sustenance of gastric stem cells in vivo and in vitro is involved in the genesis and promotion of EMT-induced tumor-initiating cells.

Exploiting the bad eating habits of Ras-driven cancers.

Science.gov (United States)

White, Eileen

2013-10-01

Oncogenic Ras promotes glucose fermentation and glutamine use to supply central carbon metabolism, but how and why have only emerged recently. Ras-mediated metabolic reprogramming generates building blocks for growth and promotes antioxidant defense. To fuel metabolic pathways, Ras scavenges extracellular proteins and lipids. To bolster metabolism and mitigate stress, Ras activates cellular self-cannibalization and recycling of proteins and organelles by autophagy. Targeting these distinct features of Ras-driven cancers provides novel approaches to cancer therapy.

Oncogenic Ras-Induced Morphologic Change Is through MEK/ERK Signaling Pathway to Downregulate Stat3 at a Posttranslational Level in NIH3T3 Cells

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Hsuan-Heng Yeh

2008-01-01

Full Text Available Ras is a key regulator of the MAP kinase-signaling cascade and may cause morphologic change of Ras-transformed cells. Signal transducer and activator of transcription 3 (Stat3 can be activated by cytokine stimulation. In this study, we unravel that Ha-rasV12 overexpression can downregulate the expression of Stat3 protein at a posttranslational level in NIH3T3 cells. Furthermore, we demonstrate that Stat3 expression downregulated by Ha-rasV12 overexpression is through proteosome degradation and not through a mTOR/p70S6K-related signaling pathway. The suppression of Stat3 accompanied by the morphologic change induced by Ha-rasV12 was through mitogen extracellular kinase (MEK/extracellular-regulated kinase (ERK signaling pathway. Microtubule disruption is involved in Ha-rasV12-induced morphologic change, which could be reversed by overexpression of Stat3. Taken together, we are the first to demonstrate that Stat3 protein plays a critical role in Ha-rasV12-induced morphologic change. Oncogenic Ras-triggered morphologic change is through the activation of MEK/ERK to posttranslationally downregulate Stat3 expression. Our finding may shed light on developing novel therapeutic strategies against Ras-related tumorigenesis.

H- ras deletion protects against angiotensin II-induced arterial hypertension and cardiac remodeling through protein kinase G-Iβ pathway activation.

Science.gov (United States)

Martín-Sánchez, Paloma; Luengo, Alicia; Griera, Mercedes; Orea, María Jesús; López-Olañeta, Marina; Chiloeches, Antonio; Lara-Pezzi, Enrique; de Frutos, Sergio; Rodríguez-Puyol, Manuel; Calleros, Laura; Rodríguez-Puyol, Diego

2018-02-01

Ras proteins regulate cell survival, growth, differentiation, blood pressure, and fibrosis in some organs. We have demonstrated that H- ras gene deletion produces mice hypotension via a soluble guanylate cyclase-protein kinase G (PKG)-dependent mechanism. In this study, we analyzed the consequences of H- ras deletion on cardiac remodeling induced by continuous angiotensin II (AngII) infusion and the molecular mechanisms implied. Left ventricular posterior wall thickness and mass and cardiomyocyte cross-sectional area were similar between AngII-treated H-Ras knockout (H -ras -/- ) and control wild-type (H -ras +/+ ) mice, as were extracellular matrix protein expression. Increased cardiac PKG-Iβ protein expression in H -ras -/- mice suggests the involvement of this protein in heart protection. Ex vivo experiments on cardiac explants could support this mechanism, as PKG blockade blunted protection against AngII-induced cardiac hypertrophy and fibrosis markers in H -ras -/- mice. Genetic modulation studies in cardiomyocytes and cardiac and embryonic fibroblasts revealed that the lack of H-Ras down-regulates the B-RAF/MEK/ERK pathway, which induces the glycogen synthase kinase-3β-dependent activation of the transcription factor, cAMP response element-binding protein, which is responsible for PKG-Iβ overexpression in H -ras -/- mouse embryonic fibroblasts. This study demonstrates that H- ras deletion protects against AngII-induced cardiac remodeling, possibly via a mechanism in which PKG-Iβ overexpression could play a partial role, and points to H-Ras and/or downstream proteins as potential therapeutic targets in cardiovascular disease.-Martín-Sánchez, P., Luengo, A., Griera, M., Orea, M. J., López-Olañeta, M., Chiloeches, A., Lara-Pezzi, E., de Frutos, S., Rodríguez-Puyol, M., Calleros, L., Rodríguez-Puyol, D. H- ras deletion protects against angiotensin II-induced arterial hypertension and cardiac remodeling through protein kinase G-Iβ pathway activation.

An evolutionary explanation model on the transformation of culture by cultural genes*

OpenAIRE

Lee, Han

2009-01-01

This article seeks to explain how cultural transformation takes place through the evolution of cultural genes. This explanation posits that just as the evolution of an organism takes place at the genetic level, so also does the transformation of culture. As such, this paper must answer the four following questions: 1) Are there cultural genes that correspond to biological genes? 2) How can we prove that the fundamental characteristic of such cultural genes is to replicate themselves? 3) Will ...

BRAF and RAS oncogenes regulate Rho GTPase pathways to mediate migration and invasion properties in human colon cancer cells: a comparative study

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Shirasawa Senji

2011-09-01

Full Text Available Abstract Background Colorectal cancer is a common disease that involves genetic alterations, such as inactivation of tumour suppressor genes and activation of oncogenes. Among them are RAS and BRAF mutations, which rarely coexist in the same tumour. Individual members of the Rho (Ras homology GTPases contribute with distinct roles in tumour cell morphology, invasion and metastasis. The aim of this study is to dissect cell migration and invasion pathways that are utilised by BRAFV600E as compared to KRASG12V and HRASG12V oncoproteins. In particular, the role of RhoA (Ras homolog gene family, member A, Rac1 (Ras-related C3 botulinum toxin substrate 1 and Cdc42 (cell division cycle 42 in cancer progression induced by each of the three oncogenes is described. Methods Colon adenocarcinoma cells with endogenous as well as ectopically expressed or silenced oncogenic mutations of BRAFV600E, KRASG12V and HRASG12V were employed. Signalling pathways and Rho GTPases were inhibited with specific kinase inhibitors and siRNAs. Cell motility and invasion properties were correlated with cytoskeletal properties and Rho GTPase activities. Results Evidence presented here indicate that BRAFV600E significantly induces cell migration and invasion properties in vitro in colon cancer cells, at least in part through activation of RhoA GTPase. The relationship established between BRAFV600E and RhoA activation is mediated by the MEK-ERK pathway. In parallel, KRASG12V enhances the ability of colon adenocarcinoma cells Caco-2 to migrate and invade through filopodia formation and PI3K-dependent Cdc42 activation. Ultimately increased cell migration and invasion, mediated by Rac1, along with the mesenchymal morphology obtained through the Epithelial-Mesenchymal Transition (EMT were the main characteristics rendered by HRASG12V in Caco-2 cells. Moreover, BRAF and KRAS oncogenes are shown to cooperate with the TGFβ-1 pathway to provide cells with additional transforming

RasGRP1, but not RasGRP3, is required for efficient thymic β-selection and ERK activation downstream of CXCR4.

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Dominic P Golec

Full Text Available T cell development is a highly dynamic process that is driven by interactions between developing thymocytes and the thymic microenvironment. Upon entering the thymus, the earliest thymic progenitors, called CD4(-CD8(- 'double negative' (DN thymocytes, pass through a checkpoint termed "β-selection" before maturing into CD4(+CD8(+ 'double positive' (DP thymocytes. β-selection is an important developmental checkpoint during thymopoiesis where developing DN thymocytes that successfully express the pre-T cell receptor (TCR undergo extensive proliferation and differentiation towards the DP stage. Signals transduced through the pre-TCR, chemokine receptor CXCR4 and Notch are thought to drive β-selection. Additionally, it has long been known that ERK is activated during β-selection; however the pathways regulating ERK activation remain unknown. Here, we performed a detailed analysis of the β-selection events in mice lacking RasGRP1, RasGRP3 and RasGRP1 and 3. We report that RasGRP1 KO and RasGRP1/3 DKO deficient thymi show a partial developmental block at the early DN3 stage of development. Furthermore, DN3 thymocytes from RasGRP1 and RasGRP1/3 double knock-out thymi show significantly reduced proliferation, despite expression of the TCRβ chain. As a result of impaired β-selection, the pool of TCRβ(+ DN4 is significantly diminished, resulting in inefficient DN to DP development. Also, we report that RasGRP1 is required for ERK activation downstream of CXCR4 signaling, which we hypothesize represents a potential mechanism of RasGRP1 regulation of β-selection. Our results demonstrate that RasGRP1 is an important regulator of proliferation and differentiation at the β-selection checkpoint and functions downstream of CXCR4 to activate the Ras/MAPK pathway.

Extreme non-linear elasticity and transformation optics

DEFF Research Database (Denmark)

Gersborg, Allan Roulund; Sigmund, Ole

2010-01-01

realizations correspond to minimizers of elastic energy potentials for extreme values of the mechanical Poisson's ratio ν . For TE (Hz) polarized light an incompressible transformation ν = 1/2 is ideal and for TM (E z) polarized light one should use a compressible transformation with negative Poissons's ratio......Transformation optics is a powerful concept for designing novel optical components such as high transmission waveguides and cloaking devices. The selection of specific transformations is a non-unique problem. Here we reveal that transformations which allow for all dielectric and broadband optical...... ν = -1. For the TM polarization the mechanical analogy corresponds to a modified Liao functional known from the transformation optics literature. Finally, the analogy between ideal transformations and solid mechanical material models automates and broadens the concept of transformation optics...

Ras and Rheb Signaling in Survival and Cell Death

International Nuclear Information System (INIS)

Ehrkamp, Anja; Herrmann, Christian; Stoll, Raphael; Heumann, Rolf

2013-01-01

One of the most obvious hallmarks of cancer is uncontrolled proliferation of cells partly due to independence of growth factor supply. A major component of mitogenic signaling is Ras, a small GTPase. It was the first identified human protooncogene and is known since more than three decades to promote cellular proliferation and growth. Ras was shown to support growth factor-independent survival during development and to protect from chemical or mechanical lesion-induced neuronal degeneration in postmitotic neurons. In contrast, for specific patho-physiological cases and cellular systems it has been shown that Ras may also promote cell death. Proteins from the Ras association family (Rassf, especially Rassf1 and Rassf5) are tumor suppressors that are activated by Ras-GTP, triggering apoptosis via e.g., activation of mammalian sterile 20-like (MST1) kinase. In contrast to Ras, their expression is suppressed in many types of tumours, which makes Rassf proteins an exciting model for understanding the divergent effects of Ras activity. It seems likely that the outcome of Ras signaling depends on the balance between the activation of its various downstream effectors, thus determining cellular fate towards either proliferation or apoptosis. Ras homologue enriched in brain (Rheb) is a protein from the Ras superfamily that is also known to promote proliferation, growth, and regeneration through the mammalian target of rapamycin (mTor) pathway. However, recent evidences indicate that the Rheb-mTor pathway may switch its function from a pro-growth into a cell death pathway, depending on the cellular situation. In contrast to Ras signaling, for Rheb, the cellular context is likely to modulate the whole Rheb-mTor pathway towards cellular death or survival, respectively

Ras and Rheb Signaling in Survival and Cell Death

Energy Technology Data Exchange (ETDEWEB)

Ehrkamp, Anja [Molecular Neurobiochemistry, Ruhr University of Bochum, 44780 Bochum (Germany); Herrmann, Christian [Department of Physical Chemistry1, Protein Interaction, Ruhr University of Bochum, 44780 Bochum (Germany); Stoll, Raphael [Biomolecular NMR, Ruhr University of Bochum, 44780 Bochum (Germany); Heumann, Rolf, E-mail: rolf.heumann@rub.de [Molecular Neurobiochemistry, Ruhr University of Bochum, 44780 Bochum (Germany)

2013-05-28

One of the most obvious hallmarks of cancer is uncontrolled proliferation of cells partly due to independence of growth factor supply. A major component of mitogenic signaling is Ras, a small GTPase. It was the first identified human protooncogene and is known since more than three decades to promote cellular proliferation and growth. Ras was shown to support growth factor-independent survival during development and to protect from chemical or mechanical lesion-induced neuronal degeneration in postmitotic neurons. In contrast, for specific patho-physiological cases and cellular systems it has been shown that Ras may also promote cell death. Proteins from the Ras association family (Rassf, especially Rassf1 and Rassf5) are tumor suppressors that are activated by Ras-GTP, triggering apoptosis via e.g., activation of mammalian sterile 20-like (MST1) kinase. In contrast to Ras, their expression is suppressed in many types of tumours, which makes Rassf proteins an exciting model for understanding the divergent effects of Ras activity. It seems likely that the outcome of Ras signaling depends on the balance between the activation of its various downstream effectors, thus determining cellular fate towards either proliferation or apoptosis. Ras homologue enriched in brain (Rheb) is a protein from the Ras superfamily that is also known to promote proliferation, growth, and regeneration through the mammalian target of rapamycin (mTor) pathway. However, recent evidences indicate that the Rheb-mTor pathway may switch its function from a pro-growth into a cell death pathway, depending on the cellular situation. In contrast to Ras signaling, for Rheb, the cellular context is likely to modulate the whole Rheb-mTor pathway towards cellular death or survival, respectively.

EBP1 is a novel E2F target gene regulated by transforming growth factor-β.

Directory of Open Access Journals (Sweden)

David Judah

2010-11-01

Full Text Available Regulation of gene expression requires transcription factor binding to specific DNA elements, and a large body of work has focused on the identification of such sequences. However, it is becoming increasingly clear that eukaryotic transcription factors can exhibit widespread, nonfunctional binding to genomic DNA sites. Conversely, some of these proteins, such as E2F, can also modulate gene expression by binding to non-consensus elements. E2F comprises a family of transcription factors that play key roles in a wide variety of cellular functions, including survival, differentiation, activation during tissue regeneration, metabolism, and proliferation. E2F factors bind to the Erb3-binding protein 1 (EBP1 promoter in live cells. We now show that E2F binding to the EBP1 promoter occurs through two tandem DNA elements that do not conform to typical consensus E2F motifs. Exogenously expressed E2F1 activates EBP1 reporters lacking one, but not both sites, suggesting a degree of redundancy under certain conditions. E2F1 increases the levels of endogenous EBP1 mRNA in breast carcinoma and other transformed cell lines. In contrast, in non-transformed primary epidermal keratinocytes, E2F, together with the retinoblastoma family of proteins, appears to be involved in decreasing EBP1 mRNA abundance in response to growth inhibition by transforming growth factor-β1. Thus, E2F is likely a central coordinator of multiple responses that culminate in regulation of EBP1 gene expression, and which may vary depending on cell type and context.

EBP1 is a novel E2F target gene regulated by transforming growth factor-β.

Science.gov (United States)

Judah, David; Chang, Wing Y; Dagnino, Lina

2010-11-10

Regulation of gene expression requires transcription factor binding to specific DNA elements, and a large body of work has focused on the identification of such sequences. However, it is becoming increasingly clear that eukaryotic transcription factors can exhibit widespread, nonfunctional binding to genomic DNA sites. Conversely, some of these proteins, such as E2F, can also modulate gene expression by binding to non-consensus elements. E2F comprises a family of transcription factors that play key roles in a wide variety of cellular functions, including survival, differentiation, activation during tissue regeneration, metabolism, and proliferation. E2F factors bind to the Erb3-binding protein 1 (EBP1) promoter in live cells. We now show that E2F binding to the EBP1 promoter occurs through two tandem DNA elements that do not conform to typical consensus E2F motifs. Exogenously expressed E2F1 activates EBP1 reporters lacking one, but not both sites, suggesting a degree of redundancy under certain conditions. E2F1 increases the levels of endogenous EBP1 mRNA in breast carcinoma and other transformed cell lines. In contrast, in non-transformed primary epidermal keratinocytes, E2F, together with the retinoblastoma family of proteins, appears to be involved in decreasing EBP1 mRNA abundance in response to growth inhibition by transforming growth factor-β1. Thus, E2F is likely a central coordinator of multiple responses that culminate in regulation of EBP1 gene expression, and which may vary depending on cell type and context.

Characterization of transformation related genes in oral cancer cells.

Science.gov (United States)

Chang, D D; Park, N H; Denny, C T; Nelson, S F; Pe, M

1998-04-16

A cDNA representational difference analysis (cDNA-RDA) and an arrayed filter technique were used to characterize transformation-related genes in oral cancer. From an initial comparison of normal oral epithelial cells and a human papilloma virus (HPV)-immortalized oral epithelial cell line, we obtained 384 differentially expressed gene fragments and arrayed them on a filter. Two hundred and twelve redundant clones were identified by three rounds of back hybridization. Sequence analysis of the remaining clones revealed 99 unique clones corresponding to 69 genes. The expression of these transformation related gene fragments in three nontumorigenic HPV-immortalized oral epithelial cell lines and three oral cancer cell lines were simultaneously monitored using a cDNA array hybridization. Although there was a considerable cell line-to-cell line variability in the expression of these clones, a reliable prediction of their expression could be made from the cDNA array hybridization. Our study demonstrates the utility of combining cDNA-RDA and arrayed filters in high-throughput gene expression difference analysis. The differentially expressed genes identified in this study should be informative in studying oral epithelial cell carcinogenesis.

Electrostatic Interactions Positively Regulate K-Ras Nanocluster Formation and Function▿

Science.gov (United States)

Plowman, Sarah J.; Ariotti, Nicholas; Goodall, Andrew; Parton, Robert G.; Hancock, John F.

2008-01-01

The organization of Ras proteins into plasma membrane nanoclusters is essential for high-fidelity signal transmission, but whether the nanoscale enviroments of different Ras nanoclusters regulate effector interactions is unknown. We show using high-resolution spatial mapping that Raf-1 is recruited to and retained in K-Ras-GTP nanoclusters. In contrast, Raf-1 recruited to the plasma membrane by H-Ras is not retained in H-Ras-GTP nanoclusters. Similarly, upon epidermal growth factor receptor activation, Raf-1 is preferentially recruited to K-Ras-GTP and not H-Ras-GTP nanoclusters. The formation of K-Ras-GTP nanoclusters is inhibited by phosphorylation of S181 in the C-terminal polybasic domain or enhanced by blocking S181 phosphorylation, with a concomitant reduction or increase in Raf-1 plasma membrane recruitment, respectively. Phosphorylation of S181 does not, however, regulate in vivo interactions with the nanocluster scaffold galectin-3 (Gal3), indicating separate roles for the polybasic domain and Gal3 in driving K-Ras nanocluster formation. Together, these data illustrate that Ras nanocluster composition regulates effector recruitment and highlight the importance of lipid/protein nanoscale environments to the activation of signaling cascades. PMID:18458061

CNS germinomas are characterized by global demethylation, chromosomal instability and mutational activation of the Kit-, Ras/Raf/Erk- and Akt-pathways

Science.gov (United States)

Schulte, Simone Laura; Waha, Andreas; Steiger, Barbara; Denkhaus, Dorota; Dörner, Evelyn; Calaminus, Gabriele; Leuschner, Ivo; Pietsch, Torsten

2016-01-01

CNS germinomas represent a unique germ cell tumor entity characterized by undifferentiated tumor cells and a high response rate to current treatment protocols. Limited information is available on their underlying genomic, epigenetic and biological alterations. We performed a genome-wide analysis of genomic copy number alterations in 49 CNS germinomas by molecular inversion profiling. In addition, CpG dinucleotide methylation was studied by immunohistochemistry for methylated cytosine residues. Mutational analysis was performed by resequencing of candidate genes including KIT and RAS family members. Ras/Erk and Akt pathway activation was analyzed by immunostaining with antibodies against phospho-Erk, phosho-Akt, phospho-mTOR and phospho-S6. All germinomas coexpressed Oct4 and Kit but showed an extensive global DNA demethylation compared to other tumors and normal tissues. Molecular inversion profiling showed predominant genomic instability in all tumors with a high frequency of regional gains and losses including high level gene amplifications. Activating mutations of KIT exons 11, 13, and 17 as well as a case with genomic KIT amplification and activating mutations or amplifications of RAS gene family members including KRAS, NRAS and RRAS2 indicated mutational activation of crucial signaling pathways. Co-activation of Ras/Erk and Akt pathways was present in 83% of germinomas. These data suggest that CNS germinoma cells display a demethylated nuclear DNA similar to primordial germ cells in early development. This finding has a striking coincidence with extensive genomic instability. In addition, mutational activation of Kit-, Ras/Raf/Erk- and Akt- pathways indicate the biological importance of these pathways and their components as potential targets for therapy. PMID:27391150

Differential display technique of RNA from tumorigenic and non-tumorigenic variants of hamster cells transformed with avian sarcoma virus

International Nuclear Information System (INIS)

Leksa, V.; Altaner, C.

1997-01-01

Differential display technique was applied to study expression of RNA in tumorigenic and non-tumorigenic cell variants of avian sarcoma virus transformed hamster cells. Methodical conditions were worked out, which allowed identifying a cDNA fragment of an unknown gene expressed in non-tumorigenic cell variant only. Its role in tumor suppression remains to be determined. (author)

Altered expression of the IQGAP1 gene in human lung cancer cell lines

Energy Technology Data Exchange (ETDEWEB)

Mitchell, C.E.; Palmisano, W.A.; Lechner, J.F. [and others

1995-12-01

IQGAP1 is a GTPase activation protein that accelerates GTP hydrolysis by normal p21 ras proteins. Therefore, IQGAP1 could act as an upstream affector of p21 ras activity by convert in excess amounts of active GTP-21 ras to inactive GDP-21 ras. IQGAP1 displays extensive sequence similarity to the catalytic domain of all previously reported ras GAPs, including the tumor suppressor gene protein neurofibromatosis type 1 (NF1). It has been shown that abnormal NF1 protein cannot negatively regulate the activity of ras proteins in neuroblast cells. This observation supports the hypothesis that NF1 is a tumor suppressor gene whose product acts upstream of ras. IQGAP1 is primarily expressed in lung, where it may play a role similar to NF1 in regulating the activity of H-ras or K-ras proteins. IQGAP1 functions as other GAPs by controlling the activity of ras.

Primary murine CD4+ T cells fail to acquire the ability to produce effector cytokines when active Ras is present during Th1/Th2 differentiation.

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Sujit V Janardhan

Full Text Available Constitutive Ras signaling has been shown to augment IL-2 production, reverse anergy, and functionally replace many aspects of CD28 co-stimulation in CD4+ T cells. These data raise the possibility that introduction of active Ras into primary T cells might result in improved functionality in pathologic situations of T cell dysfunction, such as cancer or chronic viral infection. To test the biologic effects of active Ras in primary T cells, CD4+ T cells from Coxsackie-Adenovirus Receptor Transgenic mice were transduced with an adenovirus encoding active Ras. As expected, active Ras augmented IL-2 production in naive CD4+ T cells. However, when cells were cultured for 4 days under conditions to promote effector cell differentiation, active Ras inhibited the ability of CD4+ T cells to acquire a Th1 or Th2 effector cytokine profile. This differentiation defect was not due to deficient STAT4 or STAT6 activation by IL-12 or IL-4, respectively, nor was it associated with deficient induction of T-bet and GATA-3 expression. Impaired effector cytokine production in active Ras-transduced cells was associated with deficient demethylation of the IL-4 gene locus. Our results indicate that, despite augmenting acute activation of naïve T cells, constitutive Ras signaling inhibits the ability of CD4+ T cells to properly differentiate into Th1/Th2 effector cytokine-producing cells, in part by interfering with epigenetic modification of effector gene loci. Alternative strategies to potentiate Ras pathway signaling in T cells in a more regulated fashion should be considered as a therapeutic approach to improve immune responses in vivo.

Targeted deep sequencing of mucinous ovarian tumors reveals multiple overlapping RAS-pathway activating mutations in borderline and cancerous neoplasms

International Nuclear Information System (INIS)

Mackenzie, Robertson; Kommoss, Stefan; Winterhoff, Boris J.; Kipp, Benjamin R.; Garcia, Joaquin J.; Voss, Jesse; Halling, Kevin; Karnezis, Anthony; Senz, Janine; Yang, Winnie; Prigge, Elena-Sophie; Reuschenbach, Miriam; Doeberitz, Magnus Von Knebel; Gilks, Blake C.; Huntsman, David G.; Bakkum-Gamez, Jamie; McAlpine, Jessica N.; Anglesio, Michael S.

2015-01-01

Mucinous ovarian tumors represent a distinct histotype of epithelial ovarian cancer. The rarest (2-4 % of ovarian carcinomas) of the five major histotypes, their genomic landscape remains poorly described. We undertook hotspot sequencing of 50 genes commonly mutated in human cancer across 69 mucinous ovarian tumors. Our goals were to establish the overall frequency of cancer-hotspot mutations across a large cohort, especially those tumors previously thought to be “RAS-pathway alteration negative”, using highly-sensitive next-generation sequencing as well as further explore a small number of cases with apparent heterogeneity in RAS-pathway activating alterations. Using the Ion Torrent PGM platform, we performed next generation sequencing analysis using the v2 Cancer Hotspot Panel. Regions of disparate ERBB2-amplification status were sequenced independently for two mucinous carcinoma (MC) cases, previously established as showing ERBB2 amplification/overexpression heterogeneity, to assess the hypothesis of subclonal populations containing either KRAS mutation or ERBB2 amplification independently or simultaneously. We detected mutations in KRAS, TP53, CDKN2A, PIK3CA, PTEN, BRAF, FGFR2, STK11, CTNNB1, SRC, SMAD4, GNA11 and ERBB2. KRAS mutations remain the most frequently observed alteration among MC (64.9 %) and mucinous borderline tumors (MBOT) (92.3 %). TP53 mutation occurred more frequently in carcinomas than borderline tumors (56.8 % and 11.5 %, respectively), and combined IHC and mutation data suggest alterations occur in approximately 68 % of MC and as many as 20 % of MBOT. Proven and potential RAS-pathway activating changes were observed in all but one MC. Concurrent ERBB2 amplification and KRAS mutation were observed in a substantial number of cases (7/63 total), as was co-occurrence of KRAS and BRAF mutations (one case). Microdissection of ERBB2-amplified regions of tumors harboring KRAS mutation suggests these alterations are occurring in the same cell

RAS1, a quantitative trait locus for salt tolerance and ABA sensitivity in Arabidopsis

KAUST Repository

Ren, Zhonghai

2010-03-08

Soil salinity limits agricultural production and is a major obstacle for feeding the growing world population. We used natural genetic variation in salt tolerance among different Arabidopsis accessions to map a major quantitative trait locus (QTL) for salt tolerance and abscisic acid (ABA) sensitivity during seed germination and early seedling growth. A recombinant inbred population derived from Landsberg erecta (Ler; salt and ABA sensitive) x Shakdara (Sha; salt and ABA resistant) was used for QTL mapping. High-resolution mapping and cloning of this QTL, Response to ABA and Salt 1 (RAS1), revealed that it is an ABA- and salt stress-inducible gene and encodes a previously undescribed plant-specific protein. A premature stop codon results in a truncated RAS1 protein in Sha. Reducing the expression of RAS1 by transfer-DNA insertion in Col or RNA interference in Ler leads to decreased salt and ABA sensitivity, whereas overexpression of the Ler allele but not the Sha allele causes increased salt and ABA sensitivity. Our results suggest that RAS1 functions as a negative regulator of salt tolerance during seed germination and early seedling growth by enhancing ABA sensitivity and that its loss of function contributes to the increased salt tolerance of Sha.

Application of non-bijective transformations to various potentials

International Nuclear Information System (INIS)

Kibler, M.

1987-11-01

Some results about non-bijective quadratic transformations generalizing the Kustaanheimo-Stiefel and Levi-Civita transformations are reviewed in Chapter 1. The three remaining sections are devoted to new results: Chapter 2 deals with the Lie algebras under constraints associated to some Hurwitz transformations; Chapter 3 and Chapter 4 are concerned with several applications of some Hurwitz transformations to wave equations for various potentials in R 3 and R 5

Methylation associated inactivation of RASSF1A and its synergistic effect with activated K-Ras in nasopharyngeal carcinoma

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Yu Jing

2009-12-01

Full Text Available Abstract Background Epigenetic silencing of tumor suppressor genes associated with promoter methylation is considered to be a hallmark of oncogenesis. RASSF1A is a candidate tumor suppressor gene which was found to be inactivated in many human cancers. Although we have had a prelimilary cognition about the function of RASSF1A, the exact mechanisms about how RASSF1A functions in human cancers were largely unknown. Moreover, the effect of mutated K-Ras gene on the function of RASSF1A is lacking. The aim of this study was to investigate the expression profile and methylation status of RASSF1A gene, and to explore its concrete mechanisms as a tumor suppressor gene in Nasopharyngeal Carcinoma. Methods We examined the expression profile and methylation status of RASSF1A in two NPC cell lines, 38 primary nasopharyngeal carcinoma and 14 normal nasopharyngeal epithelia using RT-PCR and methylated specific PCR(MSP respectively. 5-aza-dC was then added to confirm the correlation between hypermethylation status and inactivation of RASSF1A. The NPC cell line CNE-2 was transfected with exogenous pcDNA3.1(+/RASSF1A plasmid in the presence or absence of mutated K-Ras by liposome-mediated gene transfer method. Flow cytometry was used to examine the effect of RASSF1A on cell cycle modulation and apoptosis. Meanwhile, trypan blue dye exclusion assays was used to detect the effect of RASSF1A transfection alone and the co-transfection of RASSF1A and K-Ras on cell proliferation. Results Promoter methylation of RASSF1A could be detected in 71.05% (27/38 of NPC samples, but not in normal nasopharyngeal epithelia. RASSF1A expression in NPC primary tumors was lower than that in normal nasopharyngeal epithelial (p p p p Conclusion Expression of RASSF1A is down-regulated in NPC due to the hypermethylation of promoter. Exogenous expression of RASSF1A is able to induce growth inhibition effect and apoptosis in tumor cell lines, and this effect could be enhanced by activated

MYC is a metastasis gene for non-small-cell lung cancer.

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Ulf R Rapp

Full Text Available BACKGROUND: Metastasis is a process by which cancer cells learn to form satellite tumors in distant organs and represents the principle cause of death of patients with solid tumors. NSCLC is the most lethal human cancer due to its high rate of metastasis. METHODOLOGY/PRINCIPAL FINDINGS: Lack of a suitable animal model has so far hampered analysis of metastatic progression. We have examined c-MYC for its ability to induce metastasis in a C-RAF-driven mouse model for non-small-cell lung cancer. c-MYC alone induced frank tumor growth only after long latency at which time secondary mutations in K-Ras or LKB1 were detected reminiscent of human NSCLC. Combination with C-RAF led to immediate acceleration of tumor growth, conversion to papillary epithelial cells and angiogenic switch induction. Moreover, addition of c-MYC was sufficient to induce macrometastasis in liver and lymph nodes with short latency associated with lineage switch events. Thus we have generated the first conditional model for metastasis of NSCLC and identified a gene, c-MYC that is able to orchestrate all steps of this process. CONCLUSIONS/SIGNIFICANCE: Potential markers for detection of metastasis were identified and validated for diagnosis of human biopsies. These markers may represent targets for future therapeutic intervention as they include genes such as Gata4 that are exclusively expressed during lung development.

Bcr-Abl oncoproteins bind directly to activators of the Ras signalling pathway.

OpenAIRE

Puil, L; Liu, J; Gish, G; Mbamalu, G; Bowtell, D; Pelicci, P G; Arlinghaus, R; Pawson, T

1994-01-01

The cytosolic 185 and 210 kDa Bcr-Abl protein tyrosine kinases play important roles in the development of Philadelphia chromosome positive (Ph+) chronic myelogenous leukemia (CML) and acute lymphoblastic leukemia (Ph+ ALL). p185 and p210 Bcr-Abl contain identical abl-encoded sequences juxtaposed to a variable number of bcr-derived amino acids. As the mitogenic and transforming activities of tyrosine kinases involve stimulation of the Ras pathway, we analyzed Bcr-Abl oncoproteins for interacti...

K-Ras(V14I) -induced Noonan syndrome predisposes to tumour development in mice.

Science.gov (United States)

Hernández-Porras, Isabel; Schuhmacher, Alberto J; Garcia-Medina, Raquel; Jiménez, Beatriz; Cañamero, Marta; de Martino, Alba; Guerra, Carmen

2016-06-01

The Noonan syndrome (NS) is an autosomal dominant genetic disorder characterized by short stature, craniofacial dysmorphism, and congenital heart defects. A significant proportion of NS patients may also develop myeloproliferative disorders (MPDs), including juvenile myelomonocytic leukaemia (JMML). Surprisingly, scarce information is available in relation to other tumour types in these patients. We have previously developed and characterized a knock-in mouse model that carries one of the most frequent KRAS-NS-related mutations, the K-Ras(V14I) substitution, which recapitulates most of the alterations described in NS patients, including MPDs. The K-Ras(V14I) mutation is a mild activating K-Ras protein; thus, we have used this model to study tumour susceptibility in comparison with mice expressing the classical K-Ras(G12V) oncogene. Interestingly, our studies have shown that these mice display a generalized tumour predisposition and not just MPDs. In fact, we have observed that the K-Ras(V14I) mutation is capable of cooperating with the p16Ink4a/p19Arf and Trp53 tumour suppressors, as well as with other risk factors such as pancreatitis, thereby leading to a higher cancer incidence. In conclusion, our results illustrate that the K-Ras(V14I) activating protein is able to induce cancer, although at a much lower level than the classical K-Ras(G12V) oncogene, and that it can be significantly modulated by both genetic and non-genetic events. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

[Arnold-Chiari malformation in Noonan syndrome and other syndromes of the RAS/MAPK pathway].

Science.gov (United States)

Ejarque, Ismael; Millán-Salvador, José M; Oltra, Silvestre; Pesudo-Martínez, José V; Beneyto, Magdalena; Pérez-Aytés, Antonio

2015-05-01

Noonan syndrome (NS) and other syndromes with a similar phenotype, such as LEOPARD, cardiofaciocutaneous, Costello and Legius, are associated to mutations in genes included in the RAS/MAPK pathway (RASopathies), which is an important signalling pathway related to cell proliferation. Tonsillar descent into the upper cervical spinal canal, known as Arnold-Chiari malformation (ACM), has been reported in patients with NS and this has led some researchers to suggest that ACM could be part of the phenotypic spectrum of NS. We report two cases of NS and ACM. Case 1: 29-year-old female with Noonan phenotype who underwent surgery at the age of nine years due to pulmonary valve stenosis. At the age of 27, she presented symptomatic ACM that required surgical decompression. She presented the c.922A>G (N308D) mutation in the gene PTPN that belongs to the RAS/MAPK pathway. Case 2: a 10-year-old female with Noonan phenotype and asymptomatic ACM detected in magnetic resonance imaging of the brain. She was a carrier of the c.923A>G (N308S) mutation in gene PTPN11. Six patients with this association have been found in the literature, four with the Noonan phenotype and two with LEOPARD. Our two patients provide supplementary evidence that backs up the hypothesis by which ACM would be part of the phenotypic spectrum of NS. The small number of reported cases of patients with this association does not allow us to draw up recommendations about when and how often neuroimaging studies should be performed; a careful neurological examination, however, should be included in the anticipatory health guidelines in syndromes involving the RAS/MAPK pathway.

cDNA sequence of human transforming gene hst and identification of the coding sequence required for transforming activity

International Nuclear Information System (INIS)

Taira, M.; Yoshida, T.; Miyagawa, K.; Sakamoto, H.; Terada, M.; Sugimura, T.

1987-01-01

The hst gene was originally identified as a transforming gene in DNAs from human stomach cancers and from a noncancerous portion of stomach mucosa by DNA-mediated transfection assay using NIH3T3 cells. cDNA clones of hst were isolated from the cDNA library constructed from poly(A) + RNA of a secondary transformant induced by the DNA from a stomach cancer. The sequence analysis of the hst cDNA revealed the presence of two open reading frames. When this cDNA was inserted into an expression vector containing the simian virus 40 promoter, it efficiently induced the transformation of NIH3T3 cells upon transfection. It was found that one of the reading frames, which coded for 206 amino acids, was responsible for the transforming activity

Involvement of up-regulated Necl-5/Tage4/PVR/CD155 in the loss of contact inhibition in transformed NIH3T3 cells

International Nuclear Information System (INIS)

Minami, Yukiko; Ikeda, Wataru; Kajita, Mihoko; Fujito, Tsutomu; Monden, Morito; Takai, Yoshimi

2007-01-01

Normal cells show contact inhibition of cell movement and proliferation, but this is lost following transformation. We found that Necl-5, originally identified as a poliovirus receptor and up-regulated in many cancer cells, enhances growth factor-induced cell movement and proliferation. We showed that when cells contact other cells, Necl-5 interacts in trans with nectin-3 and is removed by endocytosis from the cell surface, resulting in a reduction of cell movement and proliferation. We show here that up-regulation of the gene encoding Necl-5 by the oncogene V12-Ki-Ras causes enhanced cell movement and proliferation. Upon cell-cell contact, de novo synthesis of Necl-5 exceeds the rate of Necl-5 endocytosis, eventually resulting in a net increase in the amount of Necl-5 at the cell surface. In addition, expression of the gene encoding nectin-3 is markedly reduced in transformed cells. Thus, up-regulation of Necl-5 following transformation contributes to the loss of contact inhibition in transformed cells

Genetically transformed tobacco plants expressing synthetic EPSPS gene confer tolerance against glyphosate herbicide.

Science.gov (United States)

Imran, Muhammad; Asad, Shaheen; Barboza, Andre Luiz; Galeano, Esteban; Carrer, Helaine; Mukhtar, Zahid

2017-04-01

Glyphosate quashes the synthesis of 5-enolpyruvylshikimate-3- phosphate synthase (EPSPS) enzyme which intercedes the functioning of shikimate pathway for the production of aromatic amino acids. Herbicide resistant crops are developed using glyphosate insensitive EPSPS gene isolated from Agrobacterium sp. strain CP4, which give farmers a sustainable weed control option. Intentions behind this study were to design and characterize the synthetic herbicide resistant CP4 - EPSPS gene in a model plant system and check the effectiveness of transformed tobacco against application of glyphosate. Putative transgenic plants were obtained from independent transformation events, and stable plant transformation, transgene expression and integration were demonstrated respectively by PCR, qRT-PCR and Southern hybridization. Gene transcript level and gene copy number (1-4) varied among the tested transgenic tobacco lines. Herbicide assays showed that transgenic plants were resistant to glyphosate after 12 days of spraying with glyphosate, and EPSPS activity remained at sufficient level to withstand the spray at 1000 ppm of the chemical. T 1 plants analyzed through immunoblot strips and PCR showed that the gene was being translated into protein and transmitted to the next generation successfully. This codon optimized synthetic CP4 - EPSPS gene is functionally equivalent to the gene for glyphosate resistance available in the commercial crops and hence we recommend this gene for transformation into commercial crops.

A simple and non-invasive method for nuclear transformation of intact-walled Chlamydomonas reinhardtii.

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Sora Kim

Full Text Available Genetic engineering in microalgae is gaining attraction but nuclear transformation methods available so far are either inefficient or require special equipment. In this study, we employ positively charged nanoparticles, 3-aminopropyl-functionalized magnesium phyllosilicate (aminoclay, approximate unit cell composition of [H2N(CH23]8Si8Mg6O12(OH4, for nuclear transformation into eukaryotic microalgae. TEM and EDX analysis of the process of transformation reveals that aminoclay coats negatively-charged DNA biomolecules and forms a self-assembled hybrid nanostructure. Subsequently, when this nanostructure is mixed with microalgal cells and plated onto selective agar plates with high friction force, cell wall is disrupted facilitating delivery of plasmid DNA into the cell and ultimately to the nucleus. This method is not only simple, inexpensive, and non-toxic to cells but also provides efficient transformation (5.03×10(2 transformants/µg DNA, second only to electroporation which needs advanced instrumentation. We present optimized parameters for efficient transformation including pre-treatment, friction force, concentration of foreign DNA/aminoclay, and plasticity of agar plates. It is also confirmed the successful integration and stable expression of foreign gene in Chlamydomonas reinhardtii through molecular methods.

Discordance of Mutation Statuses of Epidermal Growth Factor Receptor and K-ras between Primary Adenocarcinoma of Lung and Brain Metastasis

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Kun-Ming Rau

2016-04-01

Full Text Available Mutations on epidermal growth factor receptor (EGFR of adenocarcinomas of lung have been found to be associated with increased sensitivity to EGFR tyrosine kinase inhibitors and K-ras mutations may correlate with primary resistance. We aimed to explore the discordant mutation statuses of EGFR and K-ras between primary tumors and matched brain metastases in adenocarcinomas of lung. We used a sensitive Scorpion ARMS method to analyze EGFR mutation, and Sanger sequencing followed by allele-specific real-time polymerase chain reaction to analyze K-ras mutation. Forty-nine paired tissues with both primary adenocarcinoma of lung and matched brain metastasis were collected. Thirteen patients (26.5% were discordant for the status of EGFR between primary and metastatic sites. K-ras gene could be checked in paired specimens from 33 patients, thirteen patients (39.6% were discordant for the status of K-ras. In primary lung adenocarcinoma, there were 14 patients of mutant EGFR had mutant K-ras synchronously. This study revealed that the status of EGFR mutation in lung adenocarcinomas is relatively consistent between primary and metastatic sites compared to K-ras mutation. However, there are still a few cases of adenocarcinoma of lung showing discordance for the status of EGFR mutation. Repeated analysis of EGFR mutation is highly recommended if tissue from metastatic or recurrent site is available for the evaluation of target therapy.

Defined spatiotemporal features of RAS-ERK signals dictate cell fate in MCF-7 mammary epithelial cells.

Science.gov (United States)

Herrero, Ana; Casar, Berta; Colón-Bolea, Paula; Agudo-Ibáñez, Lorena; Crespo, Piero

2016-06-15

Signals conveyed through the RAS-ERK pathway are essential for the determination of cell fate. It is well established that signal variability is achieved in the different microenvironments in which signals unfold. It is also known that signal duration is critical for decisions concerning cell commitment. However, it is unclear how RAS-ERK signals integrate time and space in order to elicit a given biological response. To investigate this, we used MCF-7 cells, in which EGF-induced transient ERK activation triggers proliferation, whereas sustained ERK activation in response to heregulin leads to adipocytic differentiation. We found that both proliferative and differentiating signals emanate exclusively from plasma membrane-disordered microdomains. Of interest, the EGF signal can be transformed into a differentiating stimulus by HRAS overexpression, which prolongs ERK activation, but only if HRAS localizes at disordered membrane. On the other hand, HRAS signals emanating from the Golgi complex induce apoptosis and can prevent heregulin-induced differentiation. Our results indicate that within the same cellular context, RAS can exert different, even antagonistic, effects, depending on its sublocalization. Thus cell destiny is defined by the ability of a stimulus to activate RAS at the appropriate sublocalization for an adequate period while avoiding switching on opposing RAS signals. © 2016 Herrero et al. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

DA-Raf-Mediated Suppression of the Ras--ERK Pathway Is Essential for TGF-β1-Induced Epithelial-Mesenchymal Transition in Alveolar Epithelial Type 2 Cells.

Science.gov (United States)

Watanabe-Takano, Haruko; Takano, Kazunori; Hatano, Masahiko; Tokuhisa, Takeshi; Endo, Takeshi

2015-01-01

Myofibroblasts play critical roles in the development of idiopathic pulmonary fibrosis by depositing components of extracellular matrix. One source of lung myofibroblasts is thought to be alveolar epithelial type 2 cells that undergo epithelial-mesenchymal transition (EMT). Rat RLE-6TN alveolar epithelial type 2 cells treated with transforming growth factor-β1 (TGF-β1) are converted into myofibroblasts through EMT. TGF-β induces both canonical Smad signaling and non-canonical signaling, including the Ras-induced ERK pathway (Raf-MEK-ERK). However, the signaling mechanisms regulating TGF-β1-induced EMT are not fully understood. Here, we show that the Ras-ERK pathway negatively regulates TGF-β1-induced EMT in RLE-6TN cells and that DA-Raf1 (DA-Raf), a splicing isoform of A-Raf and a dominant-negative antagonist of the Ras-ERK pathway, plays an essential role in EMT. Stimulation of the cells with fibroblast growth factor 2 (FGF2), which activated the ERK pathway, prominently suppressed TGF-β1-induced EMT. An inhibitor of MEK, but not an inhibitor of phosphatidylinositol 3-kinase, rescued the TGF-β1-treated cells from the suppression of EMT by FGF2. Overexpression of a constitutively active mutant of a component of the Ras-ERK pathway, i.e., H-Ras, B-Raf, or MEK1, interfered with EMT. Knockdown of DA-Raf expression with siRNAs facilitated the activity of MEK and ERK, which were only weakly and transiently activated by TGF-β1. Although DA-Raf knockdown abrogated TGF-β1-induced EMT, the abrogation of EMT was reversed by the addition of the MEK inhibitor. Furthermore, DA-Raf knockdown impaired the TGF-β1-induced nuclear translocation of Smad2, which mediates the transcription required for EMT. These results imply that intrinsic DA-Raf exerts essential functions for EMT by antagonizing the TGF-β1-induced Ras-ERK pathway in RLE-6TN cells.

Ras and relatives--job sharing and networking keep an old family together.

Science.gov (United States)

Ehrhardt, Annette; Ehrhardt, Götz R A; Guo, Xuecui; Schrader, John W

2002-10-01

Many members of the Ras superfamily of GTPases have been implicated in the regulation of hematopoietic cells, with roles in growth, survival, differentiation, cytokine production, chemotaxis, vesicle-trafficking, and phagocytosis. The well-known p21 Ras proteins H-Ras, N-Ras, K-Ras 4A, and K-Ras 4B are also frequently mutated in human cancer and leukemia. Besides the four p21 Ras proteins, the Ras subfamily of the Ras superfamily includes R-Ras, TC21 (R-Ras2), M-Ras (R-Ras3), Rap1A, Rap1B, Rap2A, Rap2B, RalA, and RalB. They exhibit remarkable overall amino acid identities, especially in the regions interacting with the guanine nucleotide exchange factors that catalyze their activation. In addition, there is considerable sharing of various downstream effectors through which they transmit signals and of GTPase activating proteins that downregulate their activity, resulting in overlap in their regulation and effector function. Relatively little is known about the physiological functions of individual Ras family members, although the presence of well-conserved orthologs in Caenorhabditis elegans suggests that their individual roles are both specific and vital. The structural and functional similarities have meant that commonly used research tools fail to discriminate between the different family members, and functions previously attributed to one family member may be shared with other members of the Ras family. Here we discuss similarities and differences in activation, effector usage, and functions of different members of the Ras subfamily. We also review the possibility that the differential localization of Ras proteins in different parts of the cell membrane may govern their responses to activation of cell surface receptors.

Agrobacterium-mediated transformation of modified antifreeze protein gene in strawberry

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Srisulak Dheeranupattana

2005-07-01

Full Text Available The optimum condition for shoot regeneration from leaf explants of strawberry cultivar Tiogar was investigated. It was found that the best regeneration condition was MS medium containing N6-Benzyladenine (BA and 2,4-Dichlorophenoxy acetic acid (2,4-D at concentrations of 1 mg.l-1 and 0.2 mg.l-1, respectively. Antibiotics sensitivity test found that shoot regeneration from leaf explant was inhibited more than 90% at the concentration of kanamycin (Km as low as 5 mg.l-1. The modified gene encoding antifreeze protein isoform HPLC 6 was successfully constructed using codons which were optimally expressed in the strawberry plant. The antifreeze protein genes, naturally in plasmid pSW1 and modified in plasmid BB, were transformed to strawberry leaf explants by Agrobacterium tumefaciens LBA 4404. The strawberry plants, transformed with both AFP genes, were able to root in MS media containing 50 mg.l-1 Km, while no roots grew from nontransformed plant in this condition. Polymerase chain reaction indicated that the transgenes were integrated in the genome of transformants.

Protoplast isolation, transient transformation of leaf mesophyll protoplasts and improved Agrobacterium-mediated leaf disc infiltration of Phaseolus vulgaris: tools for rapid gene expression analysis.

Science.gov (United States)

Nanjareddy, Kalpana; Arthikala, Manoj-Kumar; Blanco, Lourdes; Arellano, Elizabeth S; Lara, Miguel

2016-06-24

Phaseolus vulgaris is one of the most extensively studied model legumes in the world. The P. vulgaris genome sequence is available; therefore, the need for an efficient and rapid transformation system is more imperative than ever. The functional characterization of P. vulgaris genes is impeded chiefly due to the non-amenable nature of Phaseolus sp. to stable genetic transformation. Transient transformation systems are convenient and versatile alternatives for rapid gene functional characterization studies. Hence, the present work focuses on standardizing methodologies for protoplast isolation from multiple tissues and transient transformation protocols for rapid gene expression analysis in the recalcitrant grain legume P. vulgaris. Herein, we provide methodologies for the high-throughput isolation of leaf mesophyll-, flower petal-, hypocotyl-, root- and nodule-derived protoplasts from P. vulgaris. The highly efficient polyethylene glycol-mannitol magnesium (PEG-MMG)-mediated transformation of leaf mesophyll protoplasts was optimized using a GUS reporter gene. We used the P. vulgaris SNF1-related protein kinase 1 (PvSnRK1) gene as proof of concept to demonstrate rapid gene functional analysis. An RT-qPCR analysis of protoplasts that had been transformed with PvSnRK1-RNAi and PvSnRK1-OE vectors showed the significant downregulation and ectopic constitutive expression (overexpression), respectively, of the PvSnRK1 transcript. We also demonstrated an improved transient transformation approach, sonication-assisted Agrobacterium-mediated transformation (SAAT), for the leaf disc infiltration of P. vulgaris. Interestingly, this method resulted in a 90 % transformation efficiency and transformed 60-85 % of the cells in a given area of the leaf surface. The constitutive expression of YFP further confirmed the amenability of the system to gene functional characterization studies. We present simple and efficient methodologies for protoplast isolation from multiple P

Modulation of Ras signaling alters the toxicity of hydroquinone, a benzene metabolite and component of cigarette smoke

International Nuclear Information System (INIS)

North, Matthew; Shuga, Joe; Fromowitz, Michele; Loguinov, Alexandre; Shannon, Kevin; Zhang, Luoping; Smith, Martyn T; Vulpe, Chris D

2014-01-01

Benzene is an established human leukemogen, with a ubiquitous environmental presence leading to significant population exposure. In a genome-wide functional screen in the yeast Saccharomyces cerevisiae, inactivation of IRA2, a yeast ortholog of the human tumor suppressor gene NF1 (Neurofibromin), enhanced sensitivity to hydroquinone, an important benzene metabolite. Increased Ras signaling is implicated as a causal factor in the increased pre-disposition to leukemia of individuals with mutations in NF1. Growth inhibition of yeast by hydroquinone was assessed in mutant strains exhibiting varying levels of Ras activity. Subsequently, effects of hydroquinone on both genotoxicity (measured by micronucleus formation) and proliferation of WT and Nf1 null murine hematopoietic precursors were assessed. Here we show that the Ras status of both yeast and mammalian cells modulates hydroquinone toxicity, indicating potential synergy between Ras signaling and benzene toxicity. Specifically, enhanced Ras signaling increases both hydroquinone-mediated growth inhibition in yeast and genotoxicity in mammalian hematopoetic precursors as measured by an in vitro erythroid micronucleus assay. Hydroquinone also increases proliferation of CFU-GM progenitor cells in mice with Nf1 null bone marrow relative to WT, the same cell type associated with benzene-associated leukemia. Together our findings show that hydroquinone toxicity is modulated by Ras signaling. Individuals with abnormal Ras signaling could be more vulnerable to developing myeloid diseases after exposure to benzene. We note that hydroquinone is used cosmetically as a skin-bleaching agent, including by individuals with cafe-au-lait spots (which may be present in individuals with neurofibromatosis who have a mutation in NF1), which could be unadvisable given our findings

Genes that cooperate with tumor promoters in transformation

International Nuclear Information System (INIS)

Colburn, N.H.; Smith, B.M.

1988-01-01

Tumor-promoting phorbol esters, like growth factors, elicit pleiotropic responses involving biochemical pathways that lead to different biological responses. Genetic variant cell lines that are resistant to mitogenic, differentiation, or transformation responses to tumor promoters have been valuable tools for understanding the molecular bases of these responses. Studies using the mouse epidermal JB6 cell lines that are sensitive or resistant to tumor promoter-induced transformation have yielded new understanding of genetic and signal transduction events involved in neoplastic transformation. The isolation and characterization of cloned mouse promotion sensitivity genes pro-1 and pro-2 is reviewed. A new activity of pro-1 has been identified: when transfected into human cancer prone basal cell nevus syndrome fibroblasts but not normal fibroblasts mouse pro-1 confers lifespan extension of these cells. Recently, we have found tat a pro-1 homolog from a library of nasopharyngeal carcinoma, but not the homolog from a normal human library, is activated for transferring promotion sensitivity. The many genetic variants for responses to tumor promoters have also proved valuable for signal transduction studies. JPB P- cells fail to show the 12-O-tetradecanoyl-phorbol-13-acetate (TPA)-induced syntheses of two proteins of 15 and 16 kD seen in P+ cells. P-, P+, and TPA transformed cells show a progressive decrease in both basal and TPA-inducible levels of a protein kinase C substrate of 80 kD. P- cells are relatively resistant both to anchorage-independent transformation and to a protein band shift induced by the calcium analog lanthanum. It appears that one or more calcium-binding proteins and one or more pro genes may be critical determinants of tumor promoter-induced neoplastic transformation

The gene transformer-2 of Anastrepha fruit flies (Diptera, Tephritidae) and its evolution in insects.

Science.gov (United States)

Sarno, Francesca; Ruiz, María F; Eirín-López, José M; Perondini, André L P; Selivon, Denise; Sánchez, Lucas

2010-05-13

In the tephritids Ceratitis, Bactrocera and Anastrepha, the gene transformer provides the memory device for sex determination via its auto-regulation; only in females is functional Tra protein produced. To date, the isolation and characterisation of the gene transformer-2 in the tephritids has only been undertaken in Ceratitis, and it has been shown that its function is required for the female-specific splicing of doublesex and transformer pre-mRNA. It therefore participates in transformer auto-regulatory function. In this work, the characterisation of this gene in eleven tephritid species belonging to the less extensively analysed genus Anastrepha was undertaken in order to throw light on the evolution of transformer-2. The gene transformer-2 produces a protein of 249 amino acids in both sexes, which shows the features of the SR protein family. No significant partially spliced mRNA isoform specific to the male germ line was detected, unlike in Drosophila. It is transcribed in both sexes during development and in adult life, in both the soma and germ line. The injection of Anastrepha transformer-2 dsRNA into Anastrepha embryos caused a change in the splicing pattern of the endogenous transformer and doublesex pre-mRNA of XX females from the female to the male mode. Consequently, these XX females were transformed into pseudomales. The comparison of the eleven Anastrepha Transformer-2 proteins among themselves, and with the Transformer-2 proteins of other insects, suggests the existence of negative selection acting at the protein level to maintain Transformer-2 structural features. These results indicate that transformer-2 is required for sex determination in Anastrepha through its participation in the female-specific splicing of transformer and doublesex pre-mRNAs. It is therefore needed for the auto-regulation of the gene transformer. Thus, the transformer/transfomer-2 > doublesex elements at the bottom of the cascade, and their relationships, probably represent

Parallel logic gates in synthetic gene networks induced by non-Gaussian noise.

Science.gov (United States)

Xu, Yong; Jin, Xiaoqin; Zhang, Huiqing

2013-11-01

The recent idea of logical stochastic resonance is verified in synthetic gene networks induced by non-Gaussian noise. We realize the switching between two kinds of logic gates under optimal moderate noise intensity by varying two different tunable parameters in a single gene network. Furthermore, in order to obtain more logic operations, thus providing additional information processing capacity, we obtain in a two-dimensional toggle switch model two complementary logic gates and realize the transformation between two logic gates via the methods of changing different parameters. These simulated results contribute to improve the computational power and functionality of the networks.

Transforming RNA-Seq data to improve the performance of prognostic gene signatures.

Science.gov (United States)

Zwiener, Isabella; Frisch, Barbara; Binder, Harald

2014-01-01

Gene expression measurements have successfully been used for building prognostic signatures, i.e for identifying a short list of important genes that can predict patient outcome. Mostly microarray measurements have been considered, and there is little advice available for building multivariable risk prediction models from RNA-Seq data. We specifically consider penalized regression techniques, such as the lasso and componentwise boosting, which can simultaneously consider all measurements and provide both, multivariable regression models for prediction and automated variable selection. However, they might be affected by the typical skewness, mean-variance-dependency or extreme values of RNA-Seq covariates and therefore could benefit from transformations of the latter. In an analytical part, we highlight preferential selection of covariates with large variances, which is problematic due to the mean-variance dependency of RNA-Seq data. In a simulation study, we compare different transformations of RNA-Seq data for potentially improving detection of important genes. Specifically, we consider standardization, the log transformation, a variance-stabilizing transformation, the Box-Cox transformation, and rank-based transformations. In addition, the prediction performance for real data from patients with kidney cancer and acute myeloid leukemia is considered. We show that signature size, identification performance, and prediction performance critically depend on the choice of a suitable transformation. Rank-based transformations perform well in all scenarios and can even outperform complex variance-stabilizing approaches. Generally, the results illustrate that the distribution and potential transformations of RNA-Seq data need to be considered as a critical step when building risk prediction models by penalized regression techniques.

Transforming RNA-Seq data to improve the performance of prognostic gene signatures.

Directory of Open Access Journals (Sweden)

Isabella Zwiener

Full Text Available Gene expression measurements have successfully been used for building prognostic signatures, i.e for identifying a short list of important genes that can predict patient outcome. Mostly microarray measurements have been considered, and there is little advice available for building multivariable risk prediction models from RNA-Seq data. We specifically consider penalized regression techniques, such as the lasso and componentwise boosting, which can simultaneously consider all measurements and provide both, multivariable regression models for prediction and automated variable selection. However, they might be affected by the typical skewness, mean-variance-dependency or extreme values of RNA-Seq covariates and therefore could benefit from transformations of the latter. In an analytical part, we highlight preferential selection of covariates with large variances, which is problematic due to the mean-variance dependency of RNA-Seq data. In a simulation study, we compare different transformations of RNA-Seq data for potentially improving detection of important genes. Specifically, we consider standardization, the log transformation, a variance-stabilizing transformation, the Box-Cox transformation, and rank-based transformations. In addition, the prediction performance for real data from patients with kidney cancer and acute myeloid leukemia is considered. We show that signature size, identification performance, and prediction performance critically depend on the choice of a suitable transformation. Rank-based transformations perform well in all scenarios and can even outperform complex variance-stabilizing approaches. Generally, the results illustrate that the distribution and potential transformations of RNA-Seq data need to be considered as a critical step when building risk prediction models by penalized regression techniques.

Transformation of Aspergillus parasiticus with a homologous gene (pyrG) involved in pyrimidine biosynthesis

International Nuclear Information System (INIS)

Skory, C.D.; Horng, J.S.; Pestka, J.J.; Linz, J.E.

1990-01-01

The lack of efficient transformation methods for aflatoxigenic Aspergillus parasiticus has been a major constraint for the study of aflatoxin biosynthesis at the genetic level. A transformation system with efficiencies of 30 to 50 stable transformants per μg of DNA was developed for A. parasiticus by using homologous pyrG gene. The pyrG gene from A. parasiticus was isolated by in situ plaque hybridization of a lambda genomic DNA library. Uridine auxotrophs of A. parasiticus ATCC 36537, a mutant blocked in aflatoxin biosynthesis, were isolated by selection on 5-fluoroorotic acid following nitrosoguanidine mutagenesis. Isolates with mutations in the pyrG gene resulting in elimination of orotidine monophosphate (OMP) decarboxylase activity were detected by assaying cell extracts for their ability to convert [ 14 C]OMP to [ 14 C]UMP. Transformation of A. parasiticus pyrG protoplasts with the homologous pyrG gene restored the fungal cells to prototrophy. Enzymatic analysis of cell extracts of transformant clones demonstrated that these extracts had the ability to convert [ 14 C]OMP to [ 14 C]UMP. Southern analysis of DNA purified from transformant clones indicated that both pUC19 vector sequences and pyrG sequences were integrated into the genome. The development of this pyrG transformation system should allow cloning of the aflatoxin-biosynthetic genes, which will be useful in studying the regulation of aflatoxin biosynthesis and may ultimately provide a means for controlling aflatoxin production in the field

Molecular screening of pituitary adenomas for gene mutations and rearrangements

Energy Technology Data Exchange (ETDEWEB)

Herman, V.; Drazin, N.Z.; Gonskey, R.; Melmed, S. (Cedars-Sinai Medical Center, Los Angeles, CA (United States))

1993-07-01

Although pituitary tumors arise as benign monoclonal neoplasms, genetic alterations have not readily been identified in these adenomas. The authors studied restriction fragment abnormalities involving the GH gene locus, and mutations in the p53 and H-, K-, and N-ras genes in 22 human GH cell adenomas. Twenty two nonsecretory adenomas were also examined for p53 and ras gene mutations. Seven prolactinoma DNA samples were tested for deletions in the multiple endocrine neoplasia-1 (MEN-1) locus, as well as for rearrangements in the hst gene, a member of the fibroblast growth factor family. In DNA from GH-cell adenomas, identical GH restriction patterns were detected in both pituitary and lymphocyte DNA in all patients and in one patient with a mixed GH-TSH cell adenoma. Using polymerase chain reaction (PCR)-single stranded conformation polymorphism analysis, no mutations were detected in exons 5, 6, 7 and 8 of the p53 gene in GH cell adenomas nor in 22 nonsecretory adenomas. Codons 12/13 and 61 of H-ras, K-ras, and N-ras genes were also intact on GH cell adenomas and in nonsecretory adenomas. Site-specific probes for chromosome 11q13 including, PYGM, D11S146, and INT2 were used in 7 sporadic PRL-secreting adenomas to detect deletions of the MEN-1 locus on chromosome 11. One patient was identified with a loss of 11p, and the remaining 6 patients did not demonstrate loss of heterozygosity in the pituitary 11q13 locus, compared to lymphocyte DNA. None of these patients demonstrated hst gene rearrangements which also maps to this locus. These results show that p53 and ras gene mutations are not common events in the pathogenesis of acromegaly and nonsecretory tumors. Although hst gene rearrangements and deletions of 11q13 are not associated with sporadic PRl-cell adenoma formation, a single patient was detected with a partial loss of chromosome 11, including the putative MEN-1 site. 31 refs., 5 figs., 2 tabs.

Dusp6 attenuates Ras/MAPK signaling to limit zebrafish heart regeneration.

Science.gov (United States)

Missinato, Maria A; Saydmohammed, Manush; Zuppo, Daniel A; Rao, Krithika S; Opie, Graham W; Kühn, Bernhard; Tsang, Michael

2018-03-06

Zebrafish regenerate cardiac tissue through proliferation of pre-existing cardiomyocytes and neovascularization. Secreted growth factors such as FGFs, IGF, PDGFs and Neuregulin play essential roles in stimulating cardiomyocyte proliferation. These factors activate the Ras/MAPK pathway, which is tightly controlled by the feedback attenuator Dual specificity phosphatase 6 (Dusp6), an ERK phosphatase. Here, we show that suppressing Dusp6 function enhances cardiac regeneration. Inactivation of Dusp6 by small molecules or by gene inactivation increased cardiomyocyte proliferation, coronary angiogenesis, and reduced fibrosis after ventricular resection. Inhibition of Erbb or PDGF receptor signaling suppressed cardiac regeneration in wild-type zebrafish, but had a milder effect on regeneration in dusp6 mutants. Moreover, in rat primary cardiomyocytes, NRG1-stimulated proliferation can be enhanced upon chemical inhibition of Dusp6 with BCI. Our results suggest that Dusp6 attenuates Ras/MAPK signaling during regeneration and that suppressing Dusp6 can enhance cardiac repair. © 2018. Published by The Company of Biologists Ltd.

SCD1 Expression is dispensable for hepatocarcinogenesis induced by AKT and Ras oncogenes in mice.

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Lei Li

Full Text Available Increased de novo lipogenesis is one of the major metabolic events in cancer. In human hepatocellular carcinoma (HCC, de novo lipogenesis has been found to be increased and associated with the activation of AKT/mTOR signaling. In mice, overexpression of an activated form of AKT results in increased lipogenesis and hepatic steatosis, ultimately leading to liver tumor development. Hepatocarcinogenesis is dramatically accelerated when AKT is co-expressed with an oncogenic form of N-Ras. SCD1, the major isoform of stearoyl-CoA desaturases, catalyzing the conversion of saturated fatty acids (SFA into monounsaturated fatty acids (MUFA, is a key enzyme involved in de novo lipogenesis. While many studies demonstrated the requirement of SCD1 for tumor cell growth in vitro, whether SCD1 is necessary for tumor development in vivo has not been previously investigated. Here, we show that genetic ablation of SCD1 neither inhibits lipogenesis and hepatic steatosis in AKT-overexpressing mice nor affects liver tumor development in mice co-expressing AKT and Ras oncogenes. Molecular analysis showed that SCD2 was strongly upregulated in liver tumors from AKT/Ras injected SCD1(-/- mice. Noticeably, concomitant silencing of SCD1 and SCD2 genes was highly detrimental for the growth of AKT/Ras cells in vitro. Altogether, our study provides the evidence, for the first time, that SCD1 expression is dispensable for AKT/mTOR-dependent hepatic steatosis and AKT/Ras-induced hepatocarcinogenesis in mice. Complete inhibition of stearoyl-CoA desaturase activity may be required to efficiently suppress liver tumor development.

Acquired resistance to cetuximab is associated with the overexpression of Ras family members and the loss of radiosensitization in head and neck cancer cells

International Nuclear Information System (INIS)

Saki, Mohammad; Toulany, Mahmoud; Rodemann, H. Peter

2013-01-01

Purpose: Cetuximab in combination with radiation therapy is used to treat patients with head and neck squamous cell carcinoma (HNSCC). In the present study, the mechanism of acquired resistance to cetuximab in HNSCC cells was investigated in vitro. Material and methods: The HNSCC cell lines UT5 and SAS and UT5 cells with acquired resistance to cetuximab (UT5R9) were used. The radiotoxicity potentials of cetuximab and inhibitors of PI3K, MAPK and farnesylation were tested using a clonogenic survival assay. Western blotting was used to evaluate protein expression. The levels of EGFR ligands were detected by ELISA. Results: Cetuximab inhibited proliferation and induced radiosensitization in UT5 cells but not in SAS cells. In comparison with UT5 cells, cetuximab-resistant SAS cells markedly overexpressed the K-Ras, H-Ras and N-Ras proteins, as detected by Western blotting. Resistance in UT5R9 cells was associated with the overexpression of the K-Ras, H-Ras and N-Ras proteins as well as an increase in the autocrine production of the EGFR ligands amphiregulin and transforming growth factor α (TGFα). UT5R9 cells were significantly more radioresistant than UT5 cells. Radioresistant UT5R9 cells were not radiosensitized by cetuximab, but knocking down H-RAS and N-RAS with siRNA and targeting Ras farnesylation using the farnesyltransferase inhibitor lonafarnib induced radiosensitization in these cells. Targeting PI3K and MEK revealed that the activation of the PI3K/Akt pathway but not the MAPK/ERK pathway is associated with radioresistance in UT5R9 cells. Conclusion: Targeting Ras and PI3K activity improves the outcome of irradiation in cetuximab-resistant HNSCC cell lines in vitro

Normal p21Ras/MAP kinase pathway expression and function in PBMC from patients with polycystic ovary disease.

Science.gov (United States)

Buchs, A; Chagag, P; Weiss, M; Kish, E; Levinson, R; Aharoni, D; Rapoport, M J

2004-04-01

Polycystic ovary disease (PCOD) is associated with insulin resistance and increased prevalence of type II diabetes mellitus (T2DM). The p21Ras/MAP kinase is a major intracellular signaling pathway mediating insulin signaling in insulin responsive tissues. The expression, regulation and function of the p21Ras/MAP kinase pathway in PCOD patients were examined. Peripheral blood mononuclear cells (PBMC) were isolated from ten patients with PCOD and ten controls. The expression of p21Ras and its regulatory proteins; hSOS1 and p120GAP were studied. The basal and phytohemaglutinin (PHA) or insulin stimulated phosphorylation of MAP kinase was determined. Expression of p21Ras, and its regulatory proteins hSOS1 and p120GAP were similar in PCOD patients and controls. Basal, PHA and insulin stimulated phosphorylation of MAP kinase, were also comparable in the two groups as well as their PBMC proliferative response. These data indicate that the expression and overall function of the p21Ras/MAP kinase pathway remain intact in non-diabetic patients with PCOD.

Overexpression of K-p21Ras play a prominent role in lung cancer

Science.gov (United States)

Zhang, Peng-bo; Zhou, Xin-liang; Yang, Ju-lun

2018-06-01

The proto-oncogene ras product, p21Ras, has been found overexpression in many human tumors. However, the subtypes of overexpressed p21Ras still remain unclear. The purpose of this study was to investigate overexpressed isoforms of p21Ras and their roles in the progress of lung cancer. Method: The expression of total p21Ras in normal lung tissues and lung cancers was determined by immunohistochemically staining with monoclonal antibody (Mab) KGHR-1 which could recognize and broad spectrum reaction with the (K/H/N) ras protein. Then, the isoforms of p21Ras was examined by specific Mab for each p21Ras subtypes. Results: Low expression of total p21Ras was found in 26.67% (8/30) of normal lung tissues, and 81.31% (87/107) of adenocarcinoma harbored overexpressed total p21Ras. Besides, 70.00% (35/50) of squamous cell carcinoma were detected overexpressed total p21Ras. In addition, 122 lung cancer tissues from overexpression of total p21Ras protein were selected to detect the expression of each subtype. And all the 122 lung cancer tissues were K-p21Ras overexpression. Moreover, there was a statistical significance difference between the expression level of total p21Ras and differentiation, and the same results were observed between the expression level of total p21Ras and lymph node metastasis (P0.05). Conclusions: Overexpression of K-p21Ras plays a prominent role in the progress of lung cancer and it is suggested that the p21Ras could serve as a promising treatment target in lung cancer.

Pearl millet transformation system using the positive selectable marker gene phosphomannose isomerase

CSIR Research Space (South Africa)

O'Kennedy, MM

2004-04-01

Full Text Available of the transgene. Similar to results obtained from previous studies with maize and wheat, the manA gene was shown to be a superior selectable marker gene for improving transformation efficiencies when compared to antibiotic or herbicide selectable marker genes....

Mutations in APC, CTNNBI en K-ras genes and expression of hMLHI in sporadic colorectal carcinomas from the Netherlands Cohort Study

NARCIS (Netherlands)

Luchtenborg, M.; Weijenberg, M.P.; Wark, P.A.; Merdan Saritas, M.

2005-01-01

Background - The early to intermediate stages of the majority of colorectal tumours are thought to be driven by aberrations in the Wnt (APC, CTNNB1) and Ras (K-ras) pathways. A smaller proportion of cancers shows mismatch repair deficiency. The aim of this study was to analyse the co-occurrence of

Relevance and diversity of Nitrospira populations in biofilters of brackish RAS.

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Myriam Kruse

Full Text Available Lithoautotrophic nitrite-oxidizing bacterial populations from moving-bed biofilters of brackish recirculation aquaculture systems (RAS; shrimp and barramundi were tested for their metabolic activity and phylogenetic diversity. Samples from the biofilters were labeled with (13C-bicarbonate and supplemented with nitrite at concentrations of 0.3, 3 and 10 mM, and incubated at 17 and 28°C, respectively. The biofilm material was analyzed by fatty acid methyl ester - stable isotope probing (FAME-SIP. High portions of up to 45% of Nitrospira-related labeled lipid markers were found confirming that Nitrospira is the major autotrophic nitrite oxidizer in these brackish systems with high nitrogen loads. Other nitrite-oxidizing bacteria such as Nitrobacter or Nitrotoga were functionally not relevant in the investigated biofilters. Nitrospira-related 16S rRNA gene sequences were obtained from the samples with 10 mM nitrite and analyzed by a cloning approach. Sequence studies revealed four different phylogenetic clusters within the marine sublineage IV of Nitrospira, though most sequences clustered with the type strain of Nitrospira marina and with a strain isolated from a marine RAS. Three lipids dominated the whole fatty acid profiles of nitrite-oxidizing marine and brackish enrichments of Nitrospira sublineage IV organisms. The membranes included two marker lipids (16∶1 cis7 and 16∶1 cis11 combined with the non-specific acid 16∶0 as major compounds and confirmed these marker lipids as characteristic for sublineage IV species. The predominant labeling of these characteristic fatty acids and the phylogenetic sequence analyses of the marine Nitrospira sublineage IV identified organisms of this sublineage as main autotrophic nitrite-oxidizers in the investigated brackish biofilter systems.

RasGRP3 regulates the migration of glioma cells via interaction with Arp3

Science.gov (United States)

Lee, Hae Kyung; Finniss, Susan; Cazacu, Simona; Xiang, Cunli; Poisson, Laila M.; Blumberg, Peter M.; Brodie, Chaya

2015-01-01

Glioblastoma (GBM), the most aggressive primary brain tumors, are highly infiltrative. Although GBM express high Ras activity and Ras proteins have been implicated in gliomagenesis, Ras-activating mutations are not frequent in these tumors. RasGRP3, an important signaling protein responsive to diacylglycerol (DAG), increases Ras activation. Here, we examined the expression and functions of RasGRP3 in GBM and glioma cells. RasGRP3 expression was upregulated in GBM specimens and glioma stem cells compared with normal brains and neural stem cells, respectively. RasGRP3 activated Ras and Rap1 in glioma cells and increased cell migration and invasion partially via Ras activation. Using pull-down assay and mass spectroscopy we identified the actin-related protein, Arp3, as a novel interacting protein of RasGRP3. The interaction of RasGRP3 and Arp3 was validated by immunofluorescence staining and co-immunoprecipitation, and PMA, which activates RasGRP3 and induces its translocation to the peri-nuclear region, increased the association of Arp3 and RasGRP3. Arp3 was upregulated in GBM, regulated cell spreading and migration and its silencing partially decreased these effects of RasGRP3 in glioma cells. In summary, RasGRP3 acts as an important integrating signaling protein of the DAG and Ras signaling pathways and actin polymerization and represents an important therapeutic target in GBM. PMID:25682201

Genes involved in degradation of para-nitrophenol are differentially arranged in form of non-contiguous gene clusters in Burkholderia sp. strain SJ98.

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Surendra Vikram

Full Text Available Biodegradation of para-Nitrophenol (PNP proceeds via two distinct pathways, having 1,2,3-benzenetriol (BT and hydroquinone (HQ as their respective terminal aromatic intermediates. Genes involved in these pathways have already been studied in different PNP degrading bacteria. Burkholderia sp. strain SJ98 degrades PNP via both the pathways. Earlier, we have sequenced and analyzed a ~41 kb fragment from the genomic library of strain SJ98. This DNA fragment was found to harbor all the lower pathway genes; however, genes responsible for the initial transformation of PNP could not be identified within this fragment. Now, we have sequenced and annotated the whole genome of strain SJ98 and found two ORFs (viz., pnpA and pnpB showing maximum identity at amino acid level with p-nitrophenol 4-monooxygenase (PnpM and p-benzoquinone reductase (BqR. Unlike the other PNP gene clusters reported earlier in different bacteria, these two ORFs in SJ98 genome are physically separated from the other genes of PNP degradation pathway. In order to ascertain the identity of ORFs pnpA and pnpB, we have performed in-vitro assays using recombinant proteins heterologously expressed and purified to homogeneity. Purified PnpA was found to be a functional PnpM and transformed PNP into benzoquinone (BQ, while PnpB was found to be a functional BqR which catalyzed the transformation of BQ into hydroquinone (HQ. Noticeably, PnpM from strain SJ98 could also transform a number of PNP analogues. Based on the above observations, we propose that the genes for PNP degradation in strain SJ98 are arranged differentially in form of non-contiguous gene clusters. This is the first report for such arrangement for gene clusters involved in PNP degradation. Therefore, we propose that PNP degradation in strain SJ98 could be an important model system for further studies on differential evolution of PNP degradation functions.

Efficient transformation and regeneration of transgenic cassava using the neomycin phosphotransferase gene as aminoglycoside resistance marker gene.

Science.gov (United States)

Niklaus, Michael; Gruissem, Wilhelm; Vanderschuren, Hervé

2011-01-01

Cassava is one of the most important crops in the tropics. Its industrial use for starch and biofuel production is also increasing its importance for agricultural production in tropical countries. In the last decade cassava biotechnology has emerged as a valuable alternative to the breeding constraints of this highly heterozygous crop for improved trait development of cassava germplasm. Cassava transformation remains difficult and time-consuming because of limitations in selecting transgenic tissues and regeneration of transgenic plantlets. We have recently reported an efficient and robust cassava transformation protocol using the hygromycin phosphotransferase II (hptII) gene as selection marker and the aminoglycoside hygromycin at optimal concentrations to maximize the regeneration of transgenic plantlets. In the present work, we expanded the transformation protocol to the use of the neomycin phosphotransferase II (nptII) gene as selection marker. Several aminoglycosides compatible with the use of nptII were tested and optimal concentrations for cassava transformation were determined. Given its efficiency equivalent to hptII as selection marker with the described protocol, the use of nptII opens new possibilities to engineer transgenic cassava lines with multiple T-DNA insertions and to produce transgenic cassava with a resistance marker gene that is already deregulated in several commercial transgenic crops.

Cloning of the DNA Repair Gene, Uvsf, by Transformation of Aspergillus Nidulans

OpenAIRE

Oza, K.; Kafer, E.

1990-01-01

As a first step in the cloning of the DNA repair gene uvsF of Aspergillus nidulans, uvsF pyrG double mutant strains were transformed with a genomic library which carried the complementing Neurospora pyr-4 gene in the vector. Rare pyr(+) uvs(+) cotransformants were obtained on media lacking pyrimidines, overlayed with MMS (methyl-methane sulfonate) to which uvsF is hypersensitive. Among MMS-resistant transformants, Southerns revealed two types which showed single bands of different sizes when ...

Atorvastatin inhibits insulin synthesis by inhibiting the Ras/Raf/ERK/CREB pathway in INS-1 cells

Science.gov (United States)

Sun, Hongxi; Li, Yu; Sun, Bei; Hou, Ningning; Yang, Juhong; Zheng, Miaoyan; Xu, Jie; Wang, Jingyu; Zhang, Yi; Zeng, Xianwei; Shan, Chunyan; Chang, Bai; Chen, Liming; Chang, Baocheng

2016-01-01

Abstract Backround: Type 2 diabetes has become a global epidemic disease. Atorvastatin has become a cornerstone in the prevention and treatment of atherosclerosis. However, increasing evidence showed that statins can dose-dependently increase the risk of diabetes mellitus. The mechanism is not clear. Objective: The Ras complex pathway (Ras/Raf/extracellular signal-regulated kinase [ERK]/cAMP response element-binding protein [CREB]) is the major pathway that regulates the gene transcription. Except for the inhibition of cholesterol synthesis by inhibiting the 3-hydroxy-3-methyl glutaryl coenzyme A (HMG-COA) reductase, statins can also downregulate the phosphorylation of a series of downstream substrates including the key proteins of the Ras complex pathway, therefore may inhibit the insulin syntheses in pancreatic beta cells. In our study, we investigated the inhibitory effect and the underlying mechanism of atorvastatin on insulin synthesis in rat islets. Methods: Islets were isolated from Wistar rats and cultured in Roswell Park Memorial Institute (RPMI)-1640 medium. The insulin content in the medium was measured by radioimmunoassay before and after the treatment of 50 μM atorvastatin. Effect of atorvastatin on the expression of insulin message Ribonucleic acid (mRNA) in pancreatic islet beta cells was also detected using quantitative real-time polymerase chain reaction. Western blotting was used to explore the possible role of the Ras complex pathway (Ras/Raf/ERK/CREB) in atorvastatin-inhibited insulin synthesis. The effects of atorvastatin on the binding of nuclear transcription factor p-CREB with CRE in INS-1 cells were examined via chromatin immunoprecipitation assay. Results: Compared with the control group, the insulin level decreased by 27.1% at 24 hours after atorvastatin treatment. Atorvastatin inhibited insulin synthesis by decreasing insulin mRNA expression of pancreatic islet beta cells. The activities of Ras, Raf-1, and p-CREB in the Ras complex

Elastic neutron diffraction study of transforming and non-transforming single crystal ZrV2

International Nuclear Information System (INIS)

Bostock, J.; Wong, M.; MacVicar, M.L.A.; Levinson, M.

1980-01-01

The mosaic spread of single crystal ZrV 2 is unusually narrow, approx. 1' from room temperature to 130K. For non-transforming perfect single crystal the mosaic gradually increases to approx. 1.86' at 4.2K; for transforming, twinned single crystal the room temperature mosaic is maintained to 110K, then increases to 2.76' at 94K when the crystal transforms to a mixed cubic (30%) and rhombohedral state (70%). The onset of the electronic instability (approx. 100K) is accompanied by an increase in diffuse scattering background which, for the twinned crystal, peaks at the structural transformation. The electronic instability coupled to the localized lattice stress appears to be the driving mechanism for the transformation

Regulation of an H-ras-related transcript by parathyroid hormone in rat osteosarcoma cells

Science.gov (United States)

Scott, D. K.; Weaver, W. R.; Clohisy, J. C.; Brakenhoff, K. D.; Kahn, A. J.; Partridge, N. C.

1992-01-01

The rat osteosarcoma cell line UMR 106-01 is a commonly used model system for the study of osteoblast function. However, it also expresses a phenotype characteristic of transformed cells. To test whether the latter could be accounted for by aberrant oncogene expression, we probed Northern blots of UMR and other osteoblastic cells with a panel of oncogene probes. These blots, when probed with a cDNA specific for v-H-ras, revealed a 7.0-kilobase (kb) H-ras-related transcript (designated HRRT) in UMR 106-01 cells that was not expressed in other osteoblastic cells. Osteoblast-enriched calvarial cells expressed the typical 1.1-kb H-ras mRNA, which was absent in UMR cells. Additionally, Western blots of lysates of UMR cells documented the presence of three proteins immunologically related to H-rasp21. To determine whether HRRT represented a recombinant retrovirus product, Northern blots were probed with a cDNA specific for the highly conserved gag-pol region of Moloney murine leukemia virus. These blots showed parallel cross-reactivity with an apparently identical transcript of 7.0 kb. The 7.0-kb transcripts detected by both v-H-ras and gag-pol probes declined to the same extent after treatment with concentrations of PTH known to inhibit proliferation of these cells. PTH regulated the abundance of HRRT in a time- and dose-dependent manner, with greatest repression of the transcript after 8 h of treatment with 10(-8) M PTH. The decrease in HRRT could not be completely accounted for by changes in transcriptional activity, as determined by nuclear run-on assays.(ABSTRACT TRUNCATED AT 250 WORDS).

Cloning of the PYR3 gene of Ustilago maydis and its use in DNA transformation

Energy Technology Data Exchange (ETDEWEB)

Banks, G.R.; Taylor, S.Y. (National Institute for Medical Research, London (England))

1988-12-01

The Ustilago maydis PYR3 gene encoding dihydroorotase activity was cloned by direct complementation of Escherichia coli pyrC mutations. PYR3 transformants of E. coli pyrC mutants expressed homologous transcripts of a variety of sizes and regained dihydroorotase activity. PYR3 also complemented Saccharomyces cerevisiae ura4 mutations, and again multiple transcripts were expressed in transformants, and enzyme activity was regained. A 1.25-kilobase poly(rA)+ PYR3 transcript was detected in U. maydis itself. Linear DNA carrying the PYR3 gene transformed a U. maydis pyr3-1 pyrimidine auxotroph to prototrophy. Hybridization analysis revealed that three different types of transformants could be generated, depending on the structure of the transforming DNA used. The first type involved exchange of chromosomal mutant gene sequences with the cloned wild-type plasmid sequences. A second type had integrated linear transforming DNA at the chromosomal PYR3 locus, probably via a single crossover event. The third type had integrated transforming DNA sequences at multiple sites in the U. maydis genome. In the last two types, tandemly reiterated copies of the transforming DNA were found to have been integrated. All three types had lost the sensitivity of the parental pyr3-1 mutant to UV irradiation. They had also regained dihydroorotase activity, although its level did not correlate with the PYR3 gene copy number.

Extensive gene-specific translational reprogramming in a model of B cell differentiation and Abl-dependent transformation.

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Jamie G Bates

Full Text Available To what extent might the regulation of translation contribute to differentiation programs, or to the molecular pathogenesis of cancer? Pre-B cells transformed with the viral oncogene v-Abl are suspended in an immortalized, cycling state that mimics leukemias with a BCR-ABL1 translocation, such as Chronic Myelogenous Leukemia (CML and Acute Lymphoblastic Leukemia (ALL. Inhibition of the oncogenic Abl kinase with imatinib reverses transformation, allowing progression to the next stage of B cell development. We employed a genome-wide polysome profiling assay called Gradient Encoding to investigate the extent and potential contribution of translational regulation to transformation and differentiation in v-Abl-transformed pre-B cells. Over half of the significantly translationally regulated genes did not change significantly at the level of mRNA abundance, revealing biology that might have been missed by measuring changes in transcript abundance alone. We found extensive, gene-specific changes in translation affecting genes with known roles in B cell signaling and differentiation, cancerous transformation, and cytoskeletal reorganization potentially affecting adhesion. These results highlight a major role for gene-specific translational regulation in remodeling the gene expression program in differentiation and malignant transformation.

Functional comparison of three transformer gene introns regulating conditional female lethality

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The trasformer gene plays a critical role in the sex determination pathways of many insects. We cloned two transformer gene introns from Anastrepha suspensa, the Caribbean fruit fly. These introns have sequences that putatively have a role in sex-specific splicing patterns that affect sex determinat...

Effects of Germline Mutations in the Ras/MAPK Signaling Pathway on Adaptive Behavior: Cardiofaciocutaneous Syndrome and Noonan Syndrome

Science.gov (United States)

Pierpont, Elizabeth I.; Pierpont, Mary Ella; Mendelsohn, Nancy J.; Roberts, Amy E.; Tworog-Dube, Erica; Rauen, Katherine A.; Seidenberg, Mark S.

2011-01-01

Cardiofaciocutaneous syndrome (CFC) and Noonan syndrome (NS) are two phenotypically overlapping genetic disorders whose underlying molecular etiologies affect a common signaling pathway. Mutations in the BRAF, MEK1 and MEK2 genes cause most cases of CFC and mutations in PTPN11, SOS1, KRAS and RAF1 typically cause NS. Although both syndromes are associated with developmental delays of varying severity, the extent to which the behavioral profiles differ may shed light on the different roles these respective genes play in development of skills necessary for everyday functioning. In this study, profiles of adaptive behavior of individuals with CFC and NS who had confirmed pathogenic mutations in Ras/MAPK pathway genes were investigated. Patterns of strengths and weaknesses, age-related differences, and risk factors for difficulties in adaptive skills were assessed. Although genes acting more downstream in the Ras/MAPK pathway were associated with more difficulties in adaptive functioning than genes more upstream in the pathway, several inconsistencies highlight the wide spectrum of possible developmental courses in CFC and NS. Along with clinical and genetic factors, variables such as chronological age, gestational age at birth and parental education levels accounted for significant variance in adaptive skills. Results indicate that there is wide heterogeneity in adaptive ability in CFC and NS, but that these abilities are correlated to some extent with the specific disease-causing genes. PMID:20186801

Agrobacterium tumefaciens-mediated transformation for investigating pathogenicity genes of the phytopathogenic fungus Colletotrichum sansevieriae.

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Nakamura, Masayuki; Kuwahara, Hideto; Onoyama, Keisuke; Iwai, Hisashi

2012-08-01

Agrobacterium tumefaciens-mediated transformation (AtMT) has become a common technique for DNA transformation of yeast and filamentous fungi. In this study, we first established a protocol of AtMT for the phytopathogenic fungus Colletotrichum sansevieriae. Binary T-DNA vector containing the hygromycin B phosphotransferase gene controlled by the Aspergillus nidulans gpdA promoter and the trpC terminator was constructed with pCAMBIA0380 and used with three different strains LBA4404, GV3101, and GV2260 of A. tumefaciens. Transformants were most effectively obtained when GV2260 and C. sansevieriae Sa-1-2 were co-cultivated; there were about 320 transformants per 10(6) spores. When 1,048 transformants were inoculated on Sansevieria trifasciata, three transformants were found to have completely lost their pathogenicity and two transformants displayed reduced pathogenicity. All of the five transformants had a single copy of T-DNA in their genomes. The three pathogenicity-deficient transformants were subjected to thermal asymmetric interlaced polymerase chain reaction and the reaction allowed us to amplify the sequences flanking the left and/or right borders. The flanking sequences of the two transformants, M154 and M875, showed no homology to any sequences in databases, but the sequences of M678 contained motifs of alpha-1,3-glucan synthase, suggesting that the gene might contribute to the pathogenicity of C. sansevieriae. This study describes a useful method for investigating pathogenicity genes in C. sansevieriae.

Accelerating the Non-equispaced Fast Fourier Transform on Commodity Graphics Hardware

DEFF Research Database (Denmark)

Sørensen, Thomas Sangild; Schaeffter, Tobias; Noe, Karsten Østergaard

2008-01-01

We present a fast parallel algorithm to compute the Non-equispaced fast Fourier transform on commodity graphics hardware (the GPU). We focus particularly on a novel implementation of the convolution step in the transform, which was previously its most time consuming part. We describe the performa......We present a fast parallel algorithm to compute the Non-equispaced fast Fourier transform on commodity graphics hardware (the GPU). We focus particularly on a novel implementation of the convolution step in the transform, which was previously its most time consuming part. We describe...

A novel Ras-interacting protein required for chemotaxis and cyclic adenosine monophosphate signal relay in Dictyostelium.

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Lee, S; Parent, C A; Insall, R; Firtel, R A

1999-09-01

We have identified a novel Ras-interacting protein from Dictyostelium, RIP3, whose function is required for both chemotaxis and the synthesis and relay of the cyclic AMP (cAMP) chemoattractant signal. rip3 null cells are unable to aggregate and lack receptor activation of adenylyl cyclase but are able, in response to cAMP, to induce aggregation-stage, postaggregative, and cell-type-specific gene expression in suspension culture. In addition, rip3 null cells are unable to properly polarize in a cAMP gradient and chemotaxis is highly impaired. We demonstrate that cAMP stimulation of guanylyl cyclase, which is required for chemotaxis, is reduced approximately 60% in rip3 null cells. This reduced activation of guanylyl cyclase may account, in part, for the defect in chemotaxis. When cells are pulsed with cAMP for 5 h to mimic the endogenous cAMP oscillations that occur in wild-type strains, the cells will form aggregates, most of which, however, arrest at the mound stage. Unlike the response seen in wild-type strains, the rip3 null cell aggregates that form under these experimental conditions are very small, which is probably due to the rip3 null cell chemotaxis defect. Many of the phenotypes of the rip3 null cell, including the inability to activate adenylyl cyclase in response to cAMP and defects in chemotaxis, are very similar to those of strains carrying a disruption of the gene encoding the putative Ras exchange factor AleA. We demonstrate that aleA null cells also exhibit a defect in cAMP-mediated activation of guanylyl cyclase similar to that of rip3 null cells. A double-knockout mutant (rip3/aleA null cells) exhibits a further reduction in receptor activation of guanylyl cyclase, and these cells display almost no cell polarization or movement in cAMP gradients. As RIP3 preferentially interacts with an activated form of the Dictyostelium Ras protein RasG, which itself is important for cell movement, we propose that RIP3 and AleA are components of a Ras

Association between H-RAS T81C genetic polymorphism and gastrointestinal cancer risk: A population based case-control study in China

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Li Qilong

2008-09-01

Full Text Available Abstract Background Gastrointestinal cancer, such as gastric, colon and rectal cancer, is a major medical and economic burden worldwide. However, the exact mechanism of gastrointestinal cancer development still remains unclear. RAS genes have been elucidated as major participants in the development and progression of a series of human tumours and the single nucleotide polymorphism at H-RAS cDNA position 81 was demonstrated to contribute to the risks of bladder, oral and thyroid carcinoma. Therefore, we hypothesized that this polymorphisms in H-RAS could influence susceptibility to gastrointestinal cancer as well, and we conducted this study to test the hypothesis in Chinese population. Methods A population based case-control study, including 296 cases with gastrointestinal cancer and 448 healthy controls selected from a Chinese population was conducted. H-RAS T81C polymorphism was genotyped by Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP assay. Results In the healthy controls, the TT, TC and CC genotypes frequencies of H-RAS T81C polymorphism, were 79.24%, 19.87% and 0.89%, respectively, and the C allele frequency was 10.83%. Compared with TT genotype, the TC genotype was significantly associated with an increased risk of gastric cancer (adjusted OR = 3.67, 95%CI = 2.21–6.08, while the CC genotype showed an increased risk as well (adjusted OR = 3.29, 95%CI = 0.54–19.86, but it was not statistically significant. In contrast, the frequency of TC genotype was not significantly increased in colon cancer and rectal cancer patients. Further analysis was performed by combining TC and CC genotypes compared against TT genotype. As a result, a statistically significant risk with adjusted OR of 3.65 (95%CI, 2.22–6.00 was found in gastric cancer, while no significant association of H-RAS T81C polymorphism with colon cancer and rectal cancer was observed. Conclusion These findings indicate, for the first time, that there

Association between H-RAS T81C genetic polymorphism and gastrointestinal cancer risk: A population based case-control study in China

International Nuclear Information System (INIS)

Zhang, Yongjing; Jin, Mingjuan; Liu, Bing; Ma, Xinyuan; Yao, Kaiyan; Li, Qilong; Chen, Kun

2008-01-01

Gastrointestinal cancer, such as gastric, colon and rectal cancer, is a major medical and economic burden worldwide. However, the exact mechanism of gastrointestinal cancer development still remains unclear. RAS genes have been elucidated as major participants in the development and progression of a series of human tumours and the single nucleotide polymorphism at H-RAS cDNA position 81 was demonstrated to contribute to the risks of bladder, oral and thyroid carcinoma. Therefore, we hypothesized that this polymorphisms in H-RAS could influence susceptibility to gastrointestinal cancer as well, and we conducted this study to test the hypothesis in Chinese population. A population based case-control study, including 296 cases with gastrointestinal cancer and 448 healthy controls selected from a Chinese population was conducted. H-RAS T81C polymorphism was genotyped by Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) assay. In the healthy controls, the TT, TC and CC genotypes frequencies of H-RAS T81C polymorphism, were 79.24%, 19.87% and 0.89%, respectively, and the C allele frequency was 10.83%. Compared with TT genotype, the TC genotype was significantly associated with an increased risk of gastric cancer (adjusted OR = 3.67, 95%CI = 2.21–6.08), while the CC genotype showed an increased risk as well (adjusted OR = 3.29, 95%CI = 0.54–19.86), but it was not statistically significant. In contrast, the frequency of TC genotype was not significantly increased in colon cancer and rectal cancer patients. Further analysis was performed by combining TC and CC genotypes compared against TT genotype. As a result, a statistically significant risk with adjusted OR of 3.65 (95%CI, 2.22–6.00) was found in gastric cancer, while no significant association of H-RAS T81C polymorphism with colon cancer and rectal cancer was observed. These findings indicate, for the first time, that there is an H-RAS T81C polymorphism existing in Chinese population

Approach for targeting Ras with small molecules that activate SOS-mediated nucleotide exchange.

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Burns, Michael C; Sun, Qi; Daniels, R Nathan; Camper, DeMarco; Kennedy, J Phillip; Phan, Jason; Olejniczak, Edward T; Lee, Taekyu; Waterson, Alex G; Rossanese, Olivia W; Fesik, Stephen W

2014-03-04

Aberrant activation of the small GTPase Ras by oncogenic mutation or constitutively active upstream receptor tyrosine kinases results in the deregulation of cellular signals governing growth and survival in ∼30% of all human cancers. However, the discovery of potent inhibitors of Ras has been difficult to achieve. Here, we report the identification of small molecules that bind to a unique pocket on the Ras:Son of Sevenless (SOS):Ras complex, increase the rate of SOS-catalyzed nucleotide exchange in vitro, and modulate Ras signaling pathways in cells. X-ray crystallography of Ras:SOS:Ras in complex with these molecules reveals that the compounds bind in a hydrophobic pocket in the CDC25 domain of SOS adjacent to the Switch II region of Ras. The structure-activity relationships exhibited by these compounds can be rationalized on the basis of multiple X-ray cocrystal structures. Mutational analyses confirmed the functional relevance of this binding site and showed it to be essential for compound activity. These molecules increase Ras-GTP levels and disrupt MAPK and PI3K signaling in cells at low micromolar concentrations. These small molecules represent tools to study the acute activation of Ras and highlight a pocket on SOS that may be exploited to modulate Ras signaling.

Ras Activity Oscillates in the Mouse Suprachiasmatic Nucleus and Modulates Circadian Clock Dynamics.

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Serchov, Tsvetan; Jilg, Antje; Wolf, Christian T; Radtke, Ina; Stehle, Jörg H; Heumann, Rolf

2016-04-01

Circadian rhythms, generated in the mouse suprachiasmatic nucleus (SCN), are synchronized to the environmental day-night changes by photic input. The activation of the extracellular signal-regulated kinases 1 and 2 (ERK1,2) and cAMP response element-binding protein (CREB)-mediated transcription play a critical role in this photoentrainment. The small GTPase Ras is one of the major upstream regulators of the ERK1,2/CREB pathway. In contrast to the well-described role of Ras in structural and functional synaptic plasticity in the adult mouse brain, the physiological regulation of Ras by photic sensory input is yet unknown. Here, we describe for the first time a circadian rhythm of Ras activity in the mouse SCN. Using synRas transgenic mice, expressing constitutively activated V12-Ha-Ras selectively in neurons, we demonstrate that enhanced Ras activation causes shortening of the circadian period length. We found upregulated expression and decreased inhibitory phosphorylation of the circadian period length modulator, glycogen synthase kinase-3 beta (GSK3β), in the SCN of synRas mice. Conversely, downregulation of Ras activity by blocking its function with an antibody in oscillating cell cultures reduced protein levels and increased phosphorylation of GSK3β and lengthened the period of BMAL1 promoter-driven luciferase activity. Furthermore, enhanced Ras activity in synRas mice resulted in a potentiation of light-induced phase delays at early subjective night, and increased photic induction of pERK1,2/pCREB and c-Fos. In contrast, at late subjective night, photic activation of Ras/ERK1,2/CREB in synRas mice was not sufficient to stimulate c-Fos protein expression and phase advance the clock. Taken together, our results demonstrate that Ras activity fine tunes the period length and modulates photoentrainment of the circadian clock.

Point mutation in activated c-Ha-ras gene of a chemically induced transplantable human pancreas carcinoma

International Nuclear Information System (INIS)

Maheshwari, K.K.; Parsa, I.

1986-01-01

The authors have reported a model of human pancreas carcinogenesis where repeated treatment with MNU of explants results in the development of transplantable carcinoma. This report compares the endonuclease digests of DNAs from normal human pancreas (HP) and MNU-induced transplantable tumor (HP-T1) analyzed with 32 P-labelled Ha-ras probe prepared from clone BS-9. The hybridization patterns of BamHI, BglII, EcoRI and HindIII digests of HP were significantly different from those of HP-T1. In EcoRI digests a 3.0 kb fragments of HP-T1 DNA hybridized with Ha-ras probe instead of a 4.3 kb fragments seen in HP DNA. The pattern for HindIII digests was similar to those of EcoRI. The BgIII digests of HP DNA revealed two hybridizing fragments of 8.0 and 4.3 kb whereas those of HP-T1 DNA fragments measured 8.5 and 4.0 kb. BamHI treated HP DNA showed only hybridizing fragments of 6.6 kb while the HP-T1 DNA showed to hybridizing fragments of 6.8 and 7.2 kb. The digested DNAs by HhaI, HinfI, KpnI, pstI, PvuII, SaII, SstI, TaqI and XbaI showed similar hybridization profiles. The point mutation in c-Ha-ras was examined in the HpaII and MspI double digests of both DNAs by 0.6 Kb SmaI fragments of pEJ. The hybridized fragments measured 412 and 355 bp in DNA digests from tumor and normal pancreas respectively

Genetic and Molecular Analysis of Suppressors of Ras Mutations

National Research Council Canada - National Science Library

Eastburn, Dennis

2000-01-01

.... The study of Caenorhabditis elegans and other model systems has demonstrated that Ras is part of a conserved Ras/MAPK signaling pathway involved in many aspects of development and cell regulation. The C...

Binding of the Ras activator son of sevenless to insulin receptor substrate-1 signaling complexes.

Science.gov (United States)

Baltensperger, K; Kozma, L M; Cherniack, A D; Klarlund, J K; Chawla, A; Banerjee, U; Czech, M P

1993-06-25

Signal transmission by insulin involves tyrosine phosphorylation of a major insulin receptor substrate (IRS-1) and exchange of Ras-bound guanosine diphosphate for guanosine triphosphate. Proteins containing Src homology 2 and 3 (SH2 and SH3) domains, such as the p85 regulatory subunit of phosphatidylinositol-3 kinase and growth factor receptor-bound protein 2 (GRB2), bind tyrosine phosphate sites on IRS-1 through their SH2 regions. Such complexes in COS cells were found to contain the heterologously expressed putative guanine nucleotide exchange factor encoded by the Drosophila son of sevenless gene (dSos). Thus, GRB2, p85, or other proteins with SH2-SH3 adapter sequences may link Sos proteins to IRS-1 signaling complexes as part of the mechanism by which insulin activates Ras.

Quantitative Assays for RAS Pathway Proteins and Phosphorylation States

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The NCI CPTAC program is applying its expertise in quantitative proteomics to develop assays for RAS pathway proteins. Targets include key phosphopeptides that should increase our understanding of how the RAS pathway is regulated.

Gene amplification in Chinese hamster embryo cells by the decay of incorporated iodine-125

International Nuclear Information System (INIS)

Luecke-Huhle, Christine; Ehrfeld, Angelika; Rau, Waltraud

1988-01-01

Simian Virus 40-transformed Chinese hamster embryo cells (Co631) contain 5 viral copies integrated per cell genome. These SV40 sequences were used as an endogenous indicator gene to study response of mammalian cells to radiation at gene level. Cells were internally irradiated by Auger electrons emitted by Iodine-125 which was incorporated in cell DNA in form of 5-[ 125 I] iododeoxyuridine ( 125 IdU). An increase in gene copy number was measured using dispersed cell blotting and Southern analysis in combination with highly sensitive DNA hybridization. A 13-fold amplification of the SV40 sequences and a 2-fold amplification of two cellular oncogenes of the ras family were found. Other cellular genes, like the α-actin gene, are not amplified and no variation in gene copy number was observed after incubation of cells with cold IdU. Thus, specific gene amplification seems to be the consequence of radiation-induced DNA damage and the resulting cell cycle arrest. (author)

Transformation of Inhibitor of Meristem Activity (IMA Gene into Jatropha curcas L.

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Asri Pirade Paserang

2015-09-01

Full Text Available Jatropha is one of the many biodiesel plants developed in tropical countries. Efforts to increase its productivity can be done using various methods of breeding. One of the breeding methods is the introduction of genes into the Jatropha plant. The aim of this study is to assess the success of genetic transformation using the Inhibitor of Meristem Activity (IMA gene in Jatropha curcas. The research procedures included inoculation of explants with Agrobacterium tumefaciens, callus induction, screening test of selection media, regeneration, and gene expression analysis using Polymerase Chain Reaction (PCR. IMA is one of the genes that controls flowering genes and ovule development. It was first isolated from tomato plants and has been successfully overexpressed in these plants using the Cauliflower Mosaic Virus (CaMV 35S promoter. In this experiment, plant transformation was performed on J. curcas as the target. Explant callus formation in both the control and treated samples was good, but shoot formation decreased dramatically in the treated explants. PCR analysis indicated that IMA genes can be inserted into J. curcas with the size of the IMA gene is 500 bp.

Phenotypic Screening Identifies Protein Synthesis Inhibitors as H-Ras-Nanocluster-Increasing Tumor Growth Inducers.

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Najumudeen, Arafath K; Posada, Itziar M D; Lectez, Benoit; Zhou, Yong; Landor, Sebastian K-J; Fallarero, Adyary; Vuorela, Pia; Hancock, John; Abankwa, Daniel

2015-12-15

Ras isoforms H-, N-, and K-ras are each mutated in specific cancer types at varying frequencies and have different activities in cell fate control. On the plasma membrane, Ras proteins are laterally segregated into isoform-specific nanoscale signaling hubs, termed nanoclusters. As Ras nanoclusters are required for Ras signaling, chemical modulators of nanoclusters represent ideal candidates for the specific modulation of Ras activity in cancer drug development. We therefore conducted a chemical screen with commercial and in-house natural product libraries using a cell-based H-ras-nanoclustering FRET assay. Next to established Ras inhibitors, such as a statin and farnesyl-transferase inhibitor, we surprisingly identified five protein synthesis inhibitors as positive regulators. Using commonly employed cycloheximide as a representative compound, we show that protein synthesis inhibition increased nanoclustering and effector recruitment specifically of active H-ras but not of K-ras. Consistent with these data, cycloheximide treatment activated both Erk and Akt kinases and specifically promoted H-rasG12V-induced, but not K-rasG12V-induced, PC12 cell differentiation. Intriguingly, cycloheximide increased the number of mammospheres, which are enriched for cancer stem cells. Depletion of H-ras in combination with cycloheximide significantly reduced mammosphere formation, suggesting an exquisite synthetic lethality. The potential of cycloheximide to promote tumor cell growth was also reflected in its ability to increase breast cancer cell tumors grown in ovo. These results illustrate the possibility of identifying Ras-isoform-specific modulators using nanocluster-directed screening. They also suggest an unexpected feedback from protein synthesis inhibition to Ras signaling, which might present a vulnerability in certain tumor cell types.

Diet, Lifestyle and risk of K-ras mutation-positive and -negative colorectal adenomas

NARCIS (Netherlands)

Wark, P.A.; Kuil, van der W.; Ploemacher, J.; Muijen, van G.N.P.; Mulder, Ch.J.J.; Weijenberg, M.P.; Kok, F.J.; Kampman, E.

2006-01-01

K-ras mutation-positive (K-ras+) and -negative (K-ras-) colorectal adenomas may differ clinically and pathologically. As environmental compounds may cause mutations in the growth-related K-ras oncogene or affect clonal selection depending on mutational status, we evaluated whether the aetiology of

Antisense gene therapy using anti-k-ras and antitelomerase oligonucleotides in colorectal cancer Eficacia de la terapia génica antisentido utilizando oligonucleótidos anti K-ras y antitelomerasa en cáncer colorrectal

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S. Lledó

2005-07-01

Full Text Available Aim: to test the efficacy of anti-k-ras and antitelomerase oligonucleotides for disabling colorectal cancer cell growth. Material and methods: an established human colorectal cancer cell line (SW 480, ATTC® was used. Oligodeoxiribonucleotides (ODNs have a phosphorotioate modification to ensure intracellular intake. We used an antitelomerase ODN (Telp5 and two anti-k-ras ODNs (AS-KRAS and ISIS. AS-KRAS is designed to join the k-ras oncogene's exon 1. ISIS links to the terminal transcription unit 5' of k-ras. Telp5 joins the template region of the hTR telomerase subunit. ODNs have been tested in different concentrations (1, 5, 10, 20 micromolar. Cell viability has been tested at 48 and 72 hours. Statistical analysis and graphic design were made with the statistical package "Analyzing Data with GraphPad Prism-1999", GraphPad Sofware Inc., San Diego CA©. We used the Student's t test for statistical analysis. Results: the lowest dose (1 µM was not effective. Using the highest dose (20 mM for 48 hours of combined AS-KRAS and Telp5 cell viability decreased to 99.67%. The rest of results varied depending on ODN type, dose, and exposure time. Conclusions: tested antisense ODNs stop colorectal cancer cell growth, and a combination of anti-telomerase and anti-k-ras is the most useful treatment. Efficacy is best with a higher dose and longer treatment period.Objetivo: evaluar la eficacia de oligonucleótidos anti k-ras y antitelomerasa para detener el crecimiento tumoral en el cáncer colorrectal. Material y métodos: se ha empleado una línea celular establecida de cáncer colorrectal humano (SW 480, ATTC®. Los oligodesoxirribonucleótidos (ODN utilizados en el presente trabajo presentan modificación fosforotioato con el fin de mejorar su estabilidad en presencia de fluidos biológicos. Hemos utilizado un ODN antitelomerasa (Telp5, y dos ODN anti k-ras (AS-KRAS e ISIS. AS-KRAS actúa en el exón 1 e ISIS actúa a nivel de la unidad terminal de

Evolutionary analyses of entire genomes do not support the association of mtDNA mutations with Ras/MAPK pathway syndromes.

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Alberto Gómez-Carballa

Full Text Available BACKGROUND: There are several known autosomal genes responsible for Ras/MAPK pathway syndromes, including Noonan syndrome (NS and related disorders (such as LEOPARD, neurofibromatosis type 1, although mutations of these genes do not explain all cases. Due to the important role played by the mitochondrion in the energetic metabolism of cardiac muscle, it was recently proposed that variation in the mitochondrial DNA (mtDNA genome could be a risk factor in the Noonan phenotype and in hypertrophic cardiomyopathy (HCM, which is a common clinical feature in Ras/MAPK pathway syndromes. In order to test these hypotheses, we sequenced entire mtDNA genomes in the largest series of patients suffering from Ras/MAPK pathway syndromes analyzed to date (n = 45, most of them classified as NS patients (n = 42. METHODS/PRINCIPAL FINDINGS: The results indicate that the observed mtDNA lineages were mostly of European ancestry, reproducing in a nutshell the expected haplogroup (hg patterns of a typical Iberian dataset (including hgs H, T, J, and U. Three new branches of the mtDNA phylogeny (H1j1, U5b1e, and L2a5 are described for the first time, but none of these are likely to be related to NS or Ras/MAPK pathway syndromes when observed under an evolutionary perspective. Patterns of variation in tRNA and protein genes, as well as redundant, private and heteroplasmic variants, in the mtDNA genomes of patients were as expected when compared with the patterns inferred from a worldwide mtDNA phylogeny based on more than 8700 entire genomes. Moreover, most of the mtDNA variants found in patients had already been reported in healthy individuals and constitute common polymorphisms in human population groups. CONCLUSIONS/SIGNIFICANCE: As a whole, the observed mtDNA genome variation in the NS patients was difficult to reconcile with previous findings that indicated a pathogenic role of mtDNA variants in NS.

Evolutionary Analyses of Entire Genomes Do Not Support the Association of mtDNA Mutations with Ras/MAPK Pathway Syndromes

Science.gov (United States)

Cerezo, María; Balboa, Emilia; Heredia, Claudia; Castro-Feijóo, Lidia; Rica, Itxaso; Barreiro, Jesús; Eirís, Jesús; Cabanas, Paloma; Martínez-Soto, Isabel; Fernández-Toral, Joaquín; Castro-Gago, Manuel; Pombo, Manuel; Carracedo, Ángel; Barros, Francisco

2011-01-01

Background There are several known autosomal genes responsible for Ras/MAPK pathway syndromes, including Noonan syndrome (NS) and related disorders (such as LEOPARD, neurofibromatosis type 1), although mutations of these genes do not explain all cases. Due to the important role played by the mitochondrion in the energetic metabolism of cardiac muscle, it was recently proposed that variation in the mitochondrial DNA (mtDNA) genome could be a risk factor in the Noonan phenotype and in hypertrophic cardiomyopathy (HCM), which is a common clinical feature in Ras/MAPK pathway syndromes. In order to test these hypotheses, we sequenced entire mtDNA genomes in the largest series of patients suffering from Ras/MAPK pathway syndromes analyzed to date (n = 45), most of them classified as NS patients (n = 42). Methods/Principal Findings The results indicate that the observed mtDNA lineages were mostly of European ancestry, reproducing in a nutshell the expected haplogroup (hg) patterns of a typical Iberian dataset (including hgs H, T, J, and U). Three new branches of the mtDNA phylogeny (H1j1, U5b1e, and L2a5) are described for the first time, but none of these are likely to be related to NS or Ras/MAPK pathway syndromes when observed under an evolutionary perspective. Patterns of variation in tRNA and protein genes, as well as redundant, private and heteroplasmic variants, in the mtDNA genomes of patients were as expected when compared with the patterns inferred from a worldwide mtDNA phylogeny based on more than 8700 entire genomes. Moreover, most of the mtDNA variants found in patients had already been reported in healthy individuals and constitute common polymorphisms in human population groups. Conclusions/Significance As a whole, the observed mtDNA genome variation in the NS patients was difficult to reconcile with previous findings that indicated a pathogenic role of mtDNA variants in NS. PMID:21526175

RAS signalling in energy metabolism and rare human diseases.

Science.gov (United States)

Dard, L; Bellance, N; Lacombe, D; Rossignol, R

2018-05-08

The RAS pathway is a highly conserved cascade of protein-protein interactions and phosphorylation that is at the heart of signalling networks that govern proliferation, differentiation and cell survival. Recent findings indicate that the RAS pathway plays a role in the regulation of energy metabolism via the control of mitochondrial form and function but little is known on the participation of this effect in RAS-related rare human genetic diseases. Germline mutations that hyperactivate the RAS pathway have been discovered and linked to human developmental disorders that are known as RASopathies. Individuals with RASopathies, which are estimated to affect approximately 1/1000 human birth, share many overlapping characteristics, including cardiac malformations, short stature, neurocognitive impairment, craniofacial dysmorphy, cutaneous, musculoskeletal, and ocular abnormalities, hypotonia and a predisposition to developing cancer. Since the identification of the first RASopathy, type 1 neurofibromatosis (NF1), which is caused by the inactivation of neurofibromin 1, several other syndromes have been associated with mutations in the core components of the RAS-MAPK pathway. These syndromes include Noonan syndrome (NS), Noonan syndrome with multiple lentigines (NSML), which was formerly called LEOPARD syndrome, Costello syndrome (CS), cardio-facio-cutaneous syndrome (CFC), Legius syndrome (LS) and capillary malformation-arteriovenous malformation syndrome (CM-AVM). Here, we review current knowledge about the bioenergetics of the RASopathies and discuss the molecular control of energy homeostasis and mitochondrial physiology by the RAS pathway. Copyright © 2018 Elsevier B.V. All rights reserved.

Correlation between the -1562C/T polymorphism in the matrix metalloproteinase-9 gene and hemorrhagic transformation of ischemic stroke.

Science.gov (United States)

Zhang, Xiaoman; Cao, Xinhui; Xu, Xiaoyu; Li, Aifan; Xu, Yuming

2015-03-01

The aim of the present study was to investigate the correlation between the -1562C/T polymorphism in an intron of the matrix metalloproteinase-9 (MMP-9) gene and hemorrhagic transformation of ischemic stroke (IS). Using polymerase chain reaction-restriction fragment length polymorphism, the -1562C/T polymorphisms in 222 patients with IS were detected. The patients were divided into hemorrhagic transformation (HT; 84 cases) and non-hemorrhagic transformation (NHT) groups (138 cases) depending on the results from the susceptibility-weighted magnetic resonance imaging, which was performed between one and two weeks following stroke onset. The allele frequencies were subsequently compared. Baseline data of the two groups were comparable. The HT group exhibited a significantly lower frequency of the CT+TT genotype compared with the NHT group (17.86 vs. 30.43%, Pcorrelated with hemorrhagic transformation of IS in the population studied. Furthermore, the T allele may be a protective factor for hemorrhagic transformation of IS in this population.

In vitro cell transformation induced by synthetic amorphous silica nanoparticles.

Science.gov (United States)

Fontana, Caroline; Kirsch, Anaïs; Seidel, Carole; Marpeaux, Léa; Darne, Christian; Gaté, Laurent; Remy, Aurélie; Guichard, Yves

2017-11-01

Synthetic amorphous silica nanoparticles (SAS) are among the most widely produced and used nanomaterials, but little is known about their carcinogenic potential. This study aims to evaluate the ability of four different SAS, two precipitated, NM-200 and NM-201, and two pyrogenic, NM-202 and NM-203, to induce the transformation process. For this, we used the recently developed in vitro Bhas 42 cell transformation assay (CTA). The genome of the transgenic Bhas 42 cells contains several copies of the v-Ha-ras gene, making them particularly sensitive to tumor-promoter agents. The Bhas 42 CTA, which includes an initiation assay and a promotion assay, was validated in our laboratory using known soluble carcinogenic substances. Its suitability for particle-type substances was verified by using quartz Min-U-Sil 5 (Min-U-Sil) and diatomaceous earth (DE) microparticles. As expected given their known transforming properties, Min-U-Sil responded positively in the Bhas 42 CTA and DE responded negatively. Transformation assays were performed with SAS at concentrations ranging from 2μg/cm 2 to 80μg/cm 2 . Results showed that all SAS have the capacity to induce transformed foci, interestingly only in the promotion assay, suggesting a mode of action similar to tumor-promoter substances. NM-203 exhibited transforming activity at a lower concentration than the other SAS. In conclusion, this study showed for the first time the transforming potential of different SAS, which act as tumor-promoter substances in the Bhas 42 model of cell transformation. Copyright © 2017 Elsevier B.V. All rights reserved.

Comparison of agrobacterium mediated wheat and barley transformation with nucleoside diphosphate kinase 2 (NDPK2) gene

International Nuclear Information System (INIS)

Waheed, U.; Shah, M.M.; Smedley, M.; Harwood, W.

2016-01-01

An efficient and reliable transformation system is imperative for improvement of important crop species like barley and wheat. Wheat transformation is complex due to larger genome size and polyploidy while barley has a limitation of genotypic dependency. The objective of current study was to compare the relative transformation efficiency of wheat and barley using specific expression vector pBRACT 214-NDPK2 constructed through gateway cloning carrying Nucleoside Diphosphate Kinase 2 (NDPK2) gene. The vector was used to compare the transformation response in both crops using immature embryos through Agrobacterium mediated transformation. Both wheat and barley showed different responses towards callus induction and regeneration. Immature embryos of 1.5 to 2 mm in diameter was found optimum for wheat callus induction while 1 to 1.5 mm for barley. Both embryogenic and non-embryogenic calli were found in wheat with significantly greater tendency for embryogenecity in barley. The overall regeneration response was found different for all transformed wheat and barley cultivars. Wheat cultivars showed good response initially that drastically slowed down in later stages with the exception of Fielder that reached to the green shoots with good roots. The barley transformed lines showed good regeneration response as compared to wheat. PCR analysis of putative transformants using genomic DNA showed a maximum of 27% transformation efficiency in barely. No true transformation response was obtained in all cultivars of wheat used in this study. The protocol developed for wheat and barley transformation will greatly be helpful in crop improvement programme through genetic engineering especially in diploid relatives of cereals. (author)

Crack growth in non-homogeneous transformable ceramics. Part II : Crack deflection

NARCIS (Netherlands)

Stam, Geert; Giessen, Erik van der

1996-01-01

Crack growth in transformation toughened ceramics is studied using a micromechanics based continuum model which accounts for both dilatant and shear transformation strain components. In the computations, the transformable phase is taken to be distributed non-homogeneously in order to model Zirconia

RasC is required for optimal activation of adenylyl cyclase and Akt/PKB during aggregation.

Science.gov (United States)

Lim, C J; Spiegelman, G B; Weeks, G

2001-08-15

Disruption of Dictyostelium rasC, encoding a Ras subfamily protein, generated cells incapable of aggregation. While rasC expression is enriched in a cell type-specific manner during post-aggregative development, the defect in rasC(-) cells is restricted to aggregation and fully corrected by application of exogenous cAMP pulses. cAMP is not produced in rasC(-) cells stimulated by 2'-deoxy-cAMP, but is produced in response to GTPgammaS in cell lysates, indicating that G-protein-coupled cAMP receptor activation of adenylyl cyclase is regulated by RasC. However, cAMP-induced ERK2 phosphorylation is unaffected in rasC(-) cells, indicating that RasC is not an upstream activator of the mitogen-activated protein kinase required for cAMP relay. rasC(-) cells also exhibit reduced chemotaxis to cAMP during early development and delayed response to periodic cAMP stimuli produced by wild-type cells in chimeric mixtures. Furthermore, cAMP-induced Akt/PKB phosphorylation through a phosphatidylinositide 3-kinase (PI3K)-dependent pathway is dramatically reduced in rasC(-) cells, suggesting that G-protein-coupled serpentine receptor activation of PI3K is regulated by RasC. Cells lacking the RasGEF, AleA, exhibit similar defects as rasC(-) cells, suggesting that AleA may activate RasC.

Ras activation by SOS

DEFF Research Database (Denmark)

Iversen, Lars; Tu, Hsiung-Lin; Lin, Wan-Chen

2014-01-01

Activation of the small guanosine triphosphatase H-Ras by the exchange factor Son of Sevenless (SOS) is an important hub for signal transduction. Multiple layers of regulation, through protein and membrane interactions, govern activity of SOS. We characterized the specific activity of individual ...

RasGRP1 confers the phorbol ester-sensitive phenotype to EL4 lymphoma cells.

Science.gov (United States)

Han, Shujie; Knoepp, Stewart M; Hallman, Mark A; Meier, Kathryn E

2007-01-01

The murine EL4 lymphoma cell line exists in variants that are either sensitive or resistant to the tumor promoter phorbol 12-myristate 13-acetate (PMA). In sensitive EL4 cells, PMA causes robust Erk mitogen-activated protein kinase activation that results in growth arrest. In resistant cells, PMA induces minimal Erk activation, without growth arrest. PMA stimulates IL-2 production in sensitive, but not resistant, cells. The role of RasGRP1, a PMA-activated guanine nucleotide exchange factor for Ras, in EL4 phenotype was examined. Endogenous RasGRP1 protein is expressed at much higher levels in sensitive than in resistant cells. PMA-induced Ras activation is observed in sensitive cells but not in resistant cells lacking Ras-GRP1. PMA induces down-regulation of RasGRP1 protein in sensitive cells but increases RasGRP1 in resistant cells. Transfection of RasGRP1 into resistant cells enhances PMA-induced Erk activation. In the reverse experiment, introduction of small interfering RNA (siRNA) for RasGRP1 suppresses PMA-induced Ras and Erk activations in sensitive cells. Sensitive cells incubated with siRNA for RasGRP1 exhibit the PMA-resistant phenotype, in that they are able to proliferate in the presence of PMA and do not secrete IL-2 when stimulated with PMA. These studies indicate that the PMA-sensitive phenotype, as previously defined for the EL4 cell line, is conferred by endogenous expression of RasGRP1 protein.

Changes in microbial water quality in RAS following altered feed loading

DEFF Research Database (Denmark)

Rojas-Tirado, Paula Andrea; Pedersen, Per Bovbjerg; Vadstein, Olav

2018-01-01

and inorganic nutrients available for microbial growth in RAS. How these nutrient inputs affect and regulate bacteria in RAS water is, however, unclear. To investigate this relationship and the associated water quality dynamics, the effects of altered feed loading on microbial water quality in RAS was studied....... The study included six independent, identical pilot-scale RAS, each with a total volume of 1.7 m3 (make-up water: 80 L/day) stocked with juvenile rainbow trout (Oncorhynchus mykiss). All systems had been operating with constant and identical feed loading of 3.13 kg feed/m3 make-up water for a period......Intensive recirculating aquaculture systems (RAS) with its hyper-eutrophic water offer ideal conditions for bacterial growth, abundance and activity, potentially affecting fish and system performance. Feed composition and feed loading in particular will have significant impact on organic...

Lead acetate induces EGFR activation upstream of SFK and PKCα linkage to the Ras/Raf-1/ERK signaling

International Nuclear Information System (INIS)

Wang, C.-Y.; Wang, Y.-T.; Tzeng, D.-W.; Yang, J.-L.

2009-01-01

Lead acetate (Pb), a probable human carcinogen, can activate protein kinase C (PKC) upstream of extracellular signal-regulated kinase 1 and 2 (ERK1/2). Yet, it remains unclear whether Pb activation of PKC → ERK1/2 involves receptor/non-receptor tyrosine kinases and the Ras signaling transducer. Here we demonstrate a novel mechanism elicited by Pb for transmitting ERK1/2 signaling in CL3 human non-small-cell lung adenocarcinoma cells. Pb induction of higher steady-state levels of Ras-GTP was essential for increasing phospho-Raf-1 S338 and phospho-ERK1/2. Pre-treatment of the cells with a conventional PKC inhibitor Goe6976 or depleting PKCα using specific small interfering RNA blocked Pb induction of Ras-GTP. Pb also activated cellular tyrosine kinases. Specific pharmacological inhibitors, PD153035 for epidermal growth factor receptor (EGFR) and SU6656 for Src family tyrosine kinases (SFK), but not AG1296 for platelet-derived growth factor receptor, could suppress the Pb-induced tyrosine kinases, PKCα, Ras-GTP, phospho-Raf-1 S338 and phospho-ERK1/2. Furthermore, phosphorylation of tyrosines on the EGFR multiple autophosphorylation sites and the conserved SFK autophosphorylation site occurred during exposure of cells to Pb for 1-5 min and 5-30 min, respectively. Intriguingly, Pb activation of EGFR required the intrinsic kinase activity but not dimerization of the receptor. Inhibition of SFK or PKCα activities did not affect EGFR phosphorylation, while knockdown of EGFR blocked SFK phosphorylation and PKCα activation following Pb. Together, these results indicate that immediate activation of EGFR in response to Pb is obligatory for activation of SFK and PKCα and subsequent the Ras-Raf-1-MKK1/2-ERK1/2 signaling cascade

Mevalonates, Ras and Breast Cancer

National Research Council Canada - National Science Library

White, Michael

2001-01-01

.... This selective inhibition appears to be a consequence of expression of oncogenic Ras. Here we are evaluating the ability of Fmev to selectively interfere with proliferation of breast cancer cells...

The drug target genes show higher evolutionary conservation than non-target genes.

Science.gov (United States)

Lv, Wenhua; Xu, Yongdeng; Guo, Yiying; Yu, Ziqi; Feng, Guanglong; Liu, Panpan; Luan, Meiwei; Zhu, Hongjie; Liu, Guiyou; Zhang, Mingming; Lv, Hongchao; Duan, Lian; Shang, Zhenwei; Li, Jin; Jiang, Yongshuai; Zhang, Ruijie

2016-01-26

Although evidence indicates that drug target genes share some common evolutionary features, there have been few studies analyzing evolutionary features of drug targets from an overall level. Therefore, we conducted an analysis which aimed to investigate the evolutionary characteristics of drug target genes. We compared the evolutionary conservation between human drug target genes and non-target genes by combining both the evolutionary features and network topological properties in human protein-protein interaction network. The evolution rate, conservation score and the percentage of orthologous genes of 21 species were included in our study. Meanwhile, four topological features including the average shortest path length, betweenness centrality, clustering coefficient and degree were considered for comparison analysis. Then we got four results as following: compared with non-drug target genes, 1) drug target genes had lower evolutionary rates; 2) drug target genes had higher conservation scores; 3) drug target genes had higher percentages of orthologous genes and 4) drug target genes had a tighter network structure including higher degrees, betweenness centrality, clustering coefficients and lower average shortest path lengths. These results demonstrate that drug target genes are more evolutionarily conserved than non-drug target genes. We hope that our study will provide valuable information for other researchers who are interested in evolutionary conservation of drug targets.

Ras-Induced and Extracellular Signal-Regulated Kinase 1 and 2 Phosphorylation-Dependent Isomerization of Protein Tyrosine Phosphatase (PTP)-PEST by PIN1 Promotes FAK Dephosphorylation by PTP-PEST ▿

Science.gov (United States)

Zheng, Yanhua; Yang, Weiwei; Xia, Yan; Hawke, David; Liu, David X.; Lu, Zhimin

2011-01-01

Protein tyrosine phosphatase (PTP)-PEST is a critical regulator of cell adhesion and migration. However, the mechanism by which PTP-PEST is regulated in response to oncogenic signaling to dephosphorylate its substrates remains unclear. Here, we demonstrate that activated Ras induces extracellular signal-regulated kinase 1 and 2-dependent phosphorylation of PTP-PEST at S571, which recruits PIN1 to bind to PTP-PEST. Isomerization of the phosphorylated PTP-PEST by PIN1 increases the interaction between PTP-PEST and FAK, which leads to the dephosphorylation of FAK Y397 and the promotion of migration, invasion, and metastasis of v-H-Ras-transformed cells. These findings uncover an important mechanism for the regulation of PTP-PEST in activated Ras-induced tumor progression. PMID:21876001

Genetic Validation of Cell Proliferation via Ras-Independent Activation of the Raf/Mek/Erk Pathway.

Science.gov (United States)

Lechuga, Carmen G; Simón-Carrasco, Lucía; Jacob, Harrys K C; Drosten, Matthias

2017-01-01

Signaling transmitted by the Ras family of small GTPases (H-, N-, and K-Ras) is essential for proliferation of mouse embryonic fibroblasts (MEFs). However, constitutive activation of the downstream Raf/Mek/Erk pathway can bypass the requirement for Ras proteins and allow cells to proliferate in the absence of the three Ras isoforms. Here we describe a protocol for a colony formation assay that permits evaluating the role of candidate proteins that are positive or negative regulators of cell proliferation mediated via Ras-independent Raf/Mek/Erk pathway activation. K-Ras lox (H-Ras -/- , N-Ras -/- , K-Ras lox/lox , RERT ert/ert ) MEFs are infected with retro- or lentiviral vectors expressing wild-type or constitutively activated candidate cDNAs, shRNAs, or sgRNAs in combination with Cas9 to ascertain the possibility of candidate proteins to function either as an activator or inhibitor of Ras-independent Raf/Mek/Erk activation. These cells are then seeded in the absence or presence of 4-Hydroxytamoxifen (4-OHT), which activates the resident CreERT2 alleles resulting in elimination of the conditional K-Ras alleles and ultimately generating Rasless cells. Colony formation in the presence of 4-OHT indicates cell proliferation via Ras-independent Raf/Mek/Erk activation.

Differential DNA methylation profile of key genes in malignant prostate epithelial cells transformed by inorganic arsenic or cadmium

International Nuclear Information System (INIS)

Pelch, Katherine E.; Tokar, Erik J.; Merrick, B. Alex; Waalkes, Michael P.

2015-01-01

Previous work shows altered methylation patterns in inorganic arsenic (iAs)- or cadmium (Cd)-transformed epithelial cells. Here, the methylation status near the transcriptional start site was assessed in the normal human prostate epithelial cell line (RWPE-1) that was malignantly transformed by 10 μM Cd for 11 weeks (CTPE) or 5 μM iAs for 29 weeks (CAsE-PE), at which time cells showed multiple markers of acquired cancer phenotype. Next generation sequencing of the transcriptome of CAsE-PE cells identified multiple dysregulated genes. Of the most highly dysregulated genes, five genes that can be relevant to the carcinogenic process (S100P, HYAL1, NTM, NES, ALDH1A1) were chosen for an in-depth analysis of the DNA methylation profile. DNA was isolated, bisulfite converted, and combined bisulfite restriction analysis was used to identify differentially methylated CpG sites, which was confirmed with bisulfite sequencing. Four of the five genes showed differential methylation in transformants relative to control cells that was inversely related to altered gene expression. Increased expression of HYAL1 (> 25-fold) and S100P (> 40-fold) in transformants was correlated with hypomethylation near the transcriptional start site. Decreased expression of NES (> 15-fold) and NTM (> 1000-fold) in transformants was correlated with hypermethylation near the transcriptional start site. ALDH1A1 expression was differentially expressed in transformed cells but was not differentially methylated relative to control. In conclusion, altered gene expression observed in Cd and iAs transformed cells may result from altered DNA methylation status. - Highlights: • Cd and iAs are known human carcinogens, yet neither appears directly mutagenic. • Prior data suggest epigenetic modification plays a role in Cd or iAs induced cancer. • Altered methylation of four misregulated genes was found in Cd or iAs transformants. • The resulting altered gene expression may be relevant to cellular

Differential DNA methylation profile of key genes in malignant prostate epithelial cells transformed by inorganic arsenic or cadmium

Energy Technology Data Exchange (ETDEWEB)

Pelch, Katherine E.; Tokar, Erik J. [National Toxicology Program Laboratory, Division of the National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709 (United States); Merrick, B. Alex [Molecular Toxicology and Informatics Group, Biomolecular Screening Branch, Division of the National Toxicology Program, National Institute of Environmental Health Sciences, Morrisville, NC 27560 (United States); Waalkes, Michael P., E-mail: waalkes@niehs.nih.gov [National Toxicology Program Laboratory, Division of the National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709 (United States)

2015-08-01

Previous work shows altered methylation patterns in inorganic arsenic (iAs)- or cadmium (Cd)-transformed epithelial cells. Here, the methylation status near the transcriptional start site was assessed in the normal human prostate epithelial cell line (RWPE-1) that was malignantly transformed by 10 μM Cd for 11 weeks (CTPE) or 5 μM iAs for 29 weeks (CAsE-PE), at which time cells showed multiple markers of acquired cancer phenotype. Next generation sequencing of the transcriptome of CAsE-PE cells identified multiple dysregulated genes. Of the most highly dysregulated genes, five genes that can be relevant to the carcinogenic process (S100P, HYAL1, NTM, NES, ALDH1A1) were chosen for an in-depth analysis of the DNA methylation profile. DNA was isolated, bisulfite converted, and combined bisulfite restriction analysis was used to identify differentially methylated CpG sites, which was confirmed with bisulfite sequencing. Four of the five genes showed differential methylation in transformants relative to control cells that was inversely related to altered gene expression. Increased expression of HYAL1 (> 25-fold) and S100P (> 40-fold) in transformants was correlated with hypomethylation near the transcriptional start site. Decreased expression of NES (> 15-fold) and NTM (> 1000-fold) in transformants was correlated with hypermethylation near the transcriptional start site. ALDH1A1 expression was differentially expressed in transformed cells but was not differentially methylated relative to control. In conclusion, altered gene expression observed in Cd and iAs transformed cells may result from altered DNA methylation status. - Highlights: • Cd and iAs are known human carcinogens, yet neither appears directly mutagenic. • Prior data suggest epigenetic modification plays a role in Cd or iAs induced cancer. • Altered methylation of four misregulated genes was found in Cd or iAs transformants. • The resulting altered gene expression may be relevant to cellular

Immunoscintigraphy of human tumors transplanted in nude mice with radiolabeled anti-ras p21 monoclonal antibodies

International Nuclear Information System (INIS)

Katoh, Y.; Nakata, K.; Kohno, K.; Shima, M.; Satoh, A.; Kusumoto, Y.; Ishii, N.; Kohji, T.; Shiku, H.; Nagataki, S.

1990-01-01

Anti-ras p21 monoclonal antibody (RASK-3) was used for immunoscintigraphy of human cancer cell lines in nude mice. Iodine-125-labeled RASK-3 was injected into nude mice with either human colon cancers (FCC-1 or BM-314) or lung cancer (KNS-62). Clear images were obtained in all three cancers 7 days after the injection of antibody. No localization of 125 I-labeled control monoclonal antibody was observed. The ratio of tissue/blood radioactivity and % ID/g in the tumor were significantly higher than other organs by Day 8. The specific localization index examined by 131 I-RASK-3 and 125 I-control monoclonal antibody was also higher in the tumor than in other tissues. In the in vitro study, binding of RASK-3 to tumor cells increased significantly by treatment of cells with either lysolecithin or periodate-lysine-paraformaldehyde, which confirmed the intracellular localization of ras p21. The mechanism by which anti-ras p21 antibodies accumulate in tumor sites could be the necrotic changes in tumor cells or changes in membrane permeability of non-necrotic cells. These results provide a strong rationale for the utilization of ras p21 as a target antigen in the imaging of a variety of human cancers

Clinical predictors of hemorrhagic transformation in non lacunar ischemic stroke

Directory of Open Access Journals (Sweden)

Natalia R. Balian

2017-04-01

Full Text Available Hemorrhagic transformation is a complex phenomenon where brain tissue bleeds, which could be associated or not to an increase in the neurological deficit after the acute ischemic stroke. The aim of our study was to evaluate clinical predictors of hemorrhagic transformation in patients with non-lacunar ischemic stroke. We performed a prospective analysis of the clinical records and images of patients with non-lacunar ischemic stroke. Demographics, vascular risk factors, previous medications and the information of the event in patients with and without hemorrhagic transformation were here compared. We included in this study 747 patients with non-lacunar stroke, the mean age was 77 ± 11 years and 61% were females. In the univariate analysis, the age, a history of hypertension, atrial fibrillation, chronic kidney disease and the previous use of oral anticoagulation resulted statistically significant. In the multivariate analysis of logistic regression adjusted by age and vascular risk factors: the age > 80 years (OR 3.6, CI 95% 1.8-7.6, the pulse pressure > 60 mmHg at admission (OR 5.3, CI 95% 3.2-9.1, the chronic kidney disease (OR 3, CI 95% 2.5-3.8 and the presence of previous atrial fibrillation (OR 3.5, CI 95% 2.1-6.1 were associated with and increased risk of hemorrhagic transformation. The predictors of hemorrhagic transformation in our cohort showed a relationship with severe vascular illness. The identification of these patients could influence therapeutic decisions that could increase the risk of hemorrhagic transformation

Level of PAX5 in differential diagnosis of non-Hodgkin′s lymphoma

Directory of Open Access Journals (Sweden)

Brij Bharti

2016-01-01

Full Text Available Background & objectives: The PAX5, a paired box transcription factor and B-cell activator protein (BSAP, activates B-cell commitment genes and represses non-B-cell lineage genes. About 14 transcript variants of PAX5 have been observed in human. Any alteration in its expression pattern leads to lymphogenesis or associated diseases and carcinogenesis in non-lymphoid tissues. Its mechanisms of function in pathophysiology of non-Hodgkin′s lymphoma (NHL are unclear. This study was intended to explore influence of PAX5 in cascade of NHL pathogenesis and diagnosis. Methods: Samples of 65 patients were evaluated by immunohistochemical staining for cellular localization of PAX5, CD19, CD3, cABL, p53, Ras and Raf and by TUNEL assay, RNA-isolation and reverse transcriptase (RT-PCR, w0 estern blot analysis, and lactate dehydrogenase (LDH specific staining. Results: B-cell type NHL patients were positive for PAX5, p53, Ras, CD19, Raf and CD3. All of them showed TUNEL-positive cells. The differential expression pattern of PAX5, CD19, p53, CD3, Zap700 , HIF 1α, Ras, Raf and MAPK (mitogen-activated protein kinase at the levels of transcripts and proteins was observed. The LDH assay showed modulation of LDH4 and LDH5 isoforms in the lymph nodes of NHL patients. Interpretation & conclusions: The histological observations suggested that the patients represent diverse cases of NHL like mature B-cell type, mature T-cell type and high grade diffuse B-cell type NHL. The findings indicate that patients with NHL may also be analyzed for status of PAX5, CD19 and ZAP70, and their transcriptional and post-translational variants for the differential diagnosis of NHL and therapy.

Regulation of the pituitary tumor transforming gene by insulin-like-growth factor-I and insulin differs between malignant and non-neoplastic astrocytes

International Nuclear Information System (INIS)

Chamaon, Kathrin; Kirches, Elmar; Kanakis, Dimitrios; Braeuninger, Stefan; Dietzmann, Knut; Mawrin, Christian

2005-01-01

The reasons for overexpression of the oncogene pituitary tumor transforming gene (PTTG) in tumors are still not fully understood. A possible influence of the insulin-like growth factor I (Igf-I) may be of interest, since enhanced Igf-I signalling was reported in various human tumors. We examined the influence of Igf-I and insulin on PTTG expression in human astrocytoma cells in comparison to proliferating non-neoplastic rat embryonal astrocytes. PTTG mRNA expression and protein levels were increased in malignant astrocytes treated with Igf-I or insulin, whereas in rat embryonic astrocytes PTTG expression and protein levels increased only when cells were exposed to Igf-I. Enhanced transcription did not occur after treatment with inhibitors of phosphoinositol-3-kinase (PI3K) and mitogen-activated protein kinase (MAPK), blocking the two basic signalling pathways of Igf-I and insulin. In addition to this transcriptional regulation, both kinases directly bind to PTTG, suggesting a second regulatory route by phosphorylation. However, the interaction of endogenous PTTG with MAPK and PI3K, as well as PTTG phosphorylation were independent from Igf-I or insulin. The latter results were also found in human testis, which contains high PTTG levels as well as in nonneoplastic astrocytes. This suggest, that PI3K and MAPK signalling is involved in PTTG regulation not only in malignant astrocytomas but also in non-tumorous cells

The inhibitory NKR-P1B:Clr-b recognition axis facilitates detection of oncogenic transformation and cancer immunosurveillance

DEFF Research Database (Denmark)

Tanaka, M; Fine, Jason; Kirkham, Christina

2018-01-01

Natural killer (NK) cells express receptors specific for MHC class I (MHC-I) molecules involved in "missing-self" recognition of cancer and virus-infected cells. Here we elucidate the role of MHC-I-independent NKR-P1B:Clr-b interactions in the detection of oncogenic transformation by NK cells. Ras......-b protein, in turn promoting missing-self recognition via the NKR-P1B inhibitory receptor. Both Ras- and c-Myc-mediated Clr-b loss selectively augmented cytotoxicity of oncogene-transformed leukemia cells by NKR-P1B+ NK cells in vitro and enhanced rejection by WT mice in vivo. Interestingly, genetic...

CT radiogenomic characterization of EGFR, K-RAS, and ALK mutations in non-small cell lung cancer

Energy Technology Data Exchange (ETDEWEB)

Rizzo, Stefania; Rampinelli, Cristiano [European Institute of Oncology, Department of Radiology, Milan (Italy); Petrella, Francesco; Spaggiari, Lorenzo [European Institute of Oncology, Department of Thoracic Surgery, Milan (Italy); Buscarino, Valentina; De Maria, Federica [University of Milan, Department of Health Sciences, Milan (Italy); Raimondi, Sara [European Institute of Oncology, Department of Epidemiology and Biostatistics, Milan (Italy); Barberis, Massimo; Fumagalli, Caterina [European Institute of Oncology, Department of Pathology, Milan (Italy); Spitaleri, Gianluca; De Marinis, Filippo [European Institute of Oncology, Department of Thoracic Oncology, Milan (Italy); Bellomi, Massimo [European Institute of Oncology, Department of Radiology, Milan (Italy); University of Milan, Department of Health Sciences, Milan (Italy)

2016-01-15

To assess the association between CT features and EGFR, ALK, KRAS mutations in non-small cell lung cancer. Patients undergoing chest CT and testing for the above gene mutations were included. Qualitative evaluation of CTs included: lobe; lesion diameter; shape; margins; ground-glass opacity; density; cavitation; air bronchogram; pleural thickening; intratumoral necrosis; nodules in tumour lobe; nodules in non-tumour lobes; pleural retraction; location; calcifications; emphysema; fibrosis; pleural contact; pleural effusion. Statistical analysis was performed to assess association of features with each gene mutation. ROC curves for gene mutations were drawn; the corresponding area under the curve was calculated. P-values <0.05 were considered significant. Of 285 patients, 60/280 (21.43 %) were positive for EGFR mutation; 31/270 (11.48 %) for ALK rearrangement; 64/240 (26.67 %) for KRAS mutation. EGFR mutation was associated with air bronchogram, pleural retraction, females, non-smokers, small lesion size, and absence of fibrosis. ALK rearrangements were associated with age and pleural effusion. KRAS mutation was associated with round shape, nodules in non-tumour lobes, and smoking. This study disclosed associations between CT features and alterations of EGFR (air bronchogram, pleural retraction, small lesion size, absence of fibrosis), ALK (pleural effusion) and KRAS (round lesion shape, nodules in non-tumour lobes). (orig.)

Loss-of-Function CNKSR2 Mutation Is a Likely Cause of Non-Syndromic X-Linked Intellectual Disability.

Science.gov (United States)

Houge, G; Rasmussen, I H; Hovland, R

2012-01-01

In a non-dysmorphic 5-year-old boy with developmental delay, well-controlled epilepsy, and microcephaly, a 234-kb deletion of Xp22.12 was detected by copy number analysis. The maternally inherited deletion removed the initial 15 of the 21 exons of the connector enhancer of KSR-2 gene called CNKSR2 or CNK2. Our finding suggests that loss of CNKSR2 is a novel cause of non-syndromic X-linked mental retardation, an assumption supported by high gene expression in the brain, localization to the post-synaptic density, and a role in RAS/MAPK-dependent signal transduction.

Gain-of-function mutant p53 but not p53 deletion promotes head and neck cancer progression in response to oncogenic K-ras

Science.gov (United States)

Acin, Sergio; Li, Zhongyou; Mejia, Olga; Roop, Dennis R; El-Naggar, Adel K; Caulin, Carlos

2015-01-01

Mutations in p53 occur in over 50% of the human head and neck squamous cell carcinomas (SCCHN). The majority of these mutations result in the expression of mutant forms of p53, rather than deletions in the p53 gene. Some p53 mutants are associated with poor prognosis in SCCHN patients. However, the molecular mechanisms that determine the poor outcome of cancers carrying p53 mutations are unknown. Here, we generated a mouse model for SCCHN and found that activation of the endogenous p53 gain-of-function mutation p53R172H, but not deletion of p53, cooperates with oncogenic K-ras during SCCHN initiation, accelerates oral tumour growth, and promotes progression to carcinoma. Mechanistically, expression profiling of the tumours that developed in these mice and studies using cell lines derived from these tumours determined that mutant p53 induces the expression of genes involved in mitosis, including cyclin B1 and cyclin A, and accelerates entry in mitosis. Additionally, we discovered that this oncogenic function of mutant p53 was dependent on K-ras because the expression of cyclin B1 and cyclin A decreased, and entry in mitosis was delayed, after suppressing K-ras expression in oral tumour cells that express p53R172H. The presence of double-strand breaks in the tumours suggests that oncogene-dependent DNA damage resulting from K-ras activation promotes the oncogenic function of mutant p53. Accordingly, DNA damage induced by doxorubicin also induced increased expression of cyclin B1 and cyclin A in cells that express p53R172H. These findings represent strong in vivo evidence for an oncogenic function of endogenous p53 gain-of-function mutations in SCCHN and provide a mechanistic explanation for the genetic interaction between oncogenic K-ras and mutant p53. PMID:21952947

Differential Expression of Ccn4 and Other Genes Between Metastatic and Non-metastatic EL4 Mouse Lymphoma Cells.

Science.gov (United States)

Chahal, Manpreet S; Ku, H Teresa; Zhang, Zhihong; Legaspi, Christian M; Luo, Angela; Hopkins, Mandi M; Meier, Kathryn E

Previous work characterized variants of the EL4 murine lymphoma cell line. Some are non-metastatic, and others metastatic, in syngenic mice. In addition, metastatic EL4 cells were stably transfected with phospholipase D2 (PLD2), which further enhanced metastasis. Microarray analyses of mRNA expression was performed for non-metastatic, metastatic, and PLD2-expressing metastatic EL4 cells. Many differences were observed between non-metastatic and metastatic cell lines. One of the most striking new findings was up-regulation of mRNA for the matricellular protein WNT1-inducible signaling pathway protein 1 (CCN4) in metastatic cells; increased protein expression was verified by immunoblotting and immunocytochemistry. Other differentially expressed genes included those for reproductive homeobox 5 (Rhox5; increased in metastatic) and cystatin 7 (Cst7; decreased in metastatic). Differences between PLD2-expressing and parental cell lines were limited but included the signaling proteins Ras guanyl releasing protein 1 (RGS18; increased with PLD2) and suppressor of cytokine signaling 2 (SOCS2; decreased with PLD2). The results provide insights into signaling pathways potentially involved in conferring metastatic ability on lymphoma cells. Copyright© 2016, International Institute of Anticancer Research (Dr. John G. Delinasios), All rights reserved.

Characterization of ERAS, a putative novel human oncogene, in skin and breast

Energy Technology Data Exchange (ETDEWEB)

Peña Avalos, B.L. de la

2014-07-01

Most human tumors have mutations in genes of the RAS small GTPase protein family. RAS works as a molecular switch for signaling pathways that modulate many aspects of cell behavior, including proliferation, differentiation, motility and death. Oncogenic mutations in RAS prevent GTP hydrolysis, locking RAS in a permanently active state, being the most common mutations in HRAS, KRAS and NRAS. The human RAS family consists of at least 36 different genes, many of which have been scarcely studied. One of these relatively unknown genes is ERAS (ES cell-expressed RAS), which is a constitutively active RAS protein, localized in chromosome X and expressed only in embryonic cells, being undetectable in adult tissues. New high throughput technologies have made it possible to screen complete cancer genomes for identification of mutations associated to cancer. Using the Sleeping Beauty (SB) transposon system, ERAS was identified as a putative novel oncogene in non-melanoma skin and breast cancers. The major aim of this project is to determine the general characteristics of ERAS as a putative novel human oncogene in skin and breast cells. Forced expression of ERAS results in drastic changes in cell shape, proliferation and motility. When ERAS is overexpressed in skin and breast human cells it is mainly localized in the cytoplasmic membrane. ERAS activates the phosphatidylinositol-3-OH kinase (PI3K) pathway but not the mitogen-activated protein kinase (MAPK) pathway. ERAS-expressing cells suffer spontaneous morphologic and phenotypic EMT-like changes, including cytoskeleton reorganization, vimentin and N-cadherin up-regulation and down-regulation of E-cadherin, which can be associated with increased malignancy, and invasive and metastatic potential. Our results suggest that inappropriate expression of ERAS lead to transformation of human cells. (Author)

CD99 triggering induces methuosis of Ewing sarcoma cells through IGF-1R/RAS/Rac1 signaling.

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Manara, Maria Cristina; Terracciano, Mario; Mancarella, Caterina; Sciandra, Marika; Guerzoni, Clara; Pasello, Michela; Grilli, Andrea; Zini, Nicoletta; Picci, Piero; Colombo, Mario P; Morrione, Andrea; Scotlandi, Katia

2016-11-29

CD99 is a cell surface molecule that has emerged as a novel target for Ewing sarcoma (EWS), an aggressive pediatric bone cancer. This report provides the first evidence of methuosis in EWS, a non-apoptotic form of cell death induced by an antibody directed against the CD99 molecule. Upon mAb triggering, CD99 induces an IGF-1R/RAS/Rac1 complex, which is internalized into RAB5-positive endocytic vacuoles. This complex is then dissociated, with the IGF-1R recycling to the cell membrane while CD99 and RAS/Rac1 are sorted into immature LAMP-1-positive vacuoles, whose excessive accumulation provokes methuosis. This process, which is not detected in CD99-expressing normal mesenchymal cells, is inhibited by disruption of the IGF-1R signaling, whereas enhanced by IGF-1 stimulation. Induction of IGF-1R/RAS/Rac1 was also observed in the EWS xenografts that respond to anti-CD99 mAb, further supporting the role of the IGF/RAS/Rac1 axis in the hyperstimulation of macropinocytosis and selective death of EWS cells. Thus, we describe a vulnerability of EWS cells, including those resistant to standard chemotherapy, to a treatment with anti-CD99 mAb, which requires IGF-1R/RAS signaling but bypasses the need for their direct targeting. Overall, we propose CD99 targeting as new opportunity to treat EWS patients resistant to canonical apoptosis-inducing agents.

Effect of the gene transformer of Anastrepha on the somatic sexual development of Drosophila.

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Ruiz, María-Fernanda; Sánchez, Lucas

2010-01-01

The gene transformer (tra) is the key regulatory memory device for sex determination in tephritid insects. The present manuscript addressed the question about the functional conservation of the tephritid Anastrepha Transformer protein to direct somatic sexual development in Drosophila (Drosophilidae). The transformer cDNA of Anastrepha encoding the putative full-length Tra protein was cloned in pUAST and introduced into Drosophila melanogaster. To express this protein, the GAL4-UAS system was used. The Anastrepha Tra protein induced the female-specific splicing of both dsx and fru pre-mRNAs in Drosophila XY male flies, so that these became transformed into females, though this transformation was incomplete (the sexually dimorphic foreleg basitarsus and the external terminalia were monitored). It was found that the degree of female transformation directly depended on the dose of Anastrepha tra and Drosophila transformer-2 (tra-2) genes, and that the Anastrepha Tra-Drosophila Tra2 complex is not as efficient as the Drosophila Tra-Tra2 complex at inducing the female-specific splicing of Drosophila dsx pre-mRNA. This can explain why the Anastrepha Tra protein cannot fully substitute for the endogenous Drosophila Tra protein.

Evolution and Diversity of the Ras Superfamily of Small GTPases in Prokaryotes

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Wuichet, Kristin; Søgaard-Andersen, Lotte

2015-01-01

The Ras superfamily of small GTPases are single domain nucleotide-dependent molecular switches that act as highly tuned regulators of complex signal transduction pathways. Originally identified in eukaryotes for their roles in fundamental cellular processes including proliferation, motility, polarity, nuclear transport, and vesicle transport, recent studies have revealed that single domain GTPases also control complex functions such as cell polarity, motility, predation, development and antibiotic resistance in bacteria. Here, we used a computational genomics approach to understand the abundance, diversity, and evolution of small GTPases in prokaryotes. We collected 520 small GTPase sequences present in 17% of 1,611 prokaryotic genomes analyzed that cover diverse lineages. We identified two discrete families of small GTPases in prokaryotes that show evidence of three distinct catalytic mechanisms. The MglA family includes MglA homologs, which are typically associated with the MglB GTPase activating protein, whereas members of the Rup (Ras superfamily GTPase of unknown function in prokaryotes) family are not predicted to interact with MglB homologs. System classification and genome context analyses support the involvement of small GTPases in diverse prokaryotic signal transduction pathways including two component systems, laying the foundation for future experimental characterization of these proteins. Phylogenetic analysis of prokaryotic and eukaryotic GTPases supports that the last universal common ancestor contained ancestral MglA and Rup family members. We propose that the MglA family was lost from the ancestral eukaryote and that the Ras superfamily members in extant eukaryotes are the result of vertical and horizontal gene transfer events of ancestral Rup GTPases. PMID:25480683

Expression of DNA mismatch repair proteins in transformed non-Hodgkin's lymphoma: relationship to smoking

DEFF Research Database (Denmark)

Nandi, S; Yu, J; Reinert, Line

2006-01-01

leukemia (CLL/SLL), that have transformed to diffuse-large B-cell lymphoma (DLBCL). We correlated the presence or absence of DNA-mismatch repair enzymes by immunostaining as well as the p53 status to smoking history. Of all patients (n = 30), 37% showed negative immunostaining of MLH1, 16% showed negative...... for either MLH1 or MSH2 was 2.2 times higher in smokers than non-smokers (relative risk = 2.2041, 95% confidence interval: 0.89714, 5.41491). No direct correlation was found between smoking and the mutations in the p53 gene. These results suggest that cigarette smoking may play a role in the development...

Selectable genes for transformation of the fungal plant pathogen Glomerella cingulata f. sp. phaseoli (Colletotrichum lindemuthianum).

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Rodriguez, R J; Yoder, O C

1987-01-01

Glomerella cingulata f. sp. phaseoli (Gcp) was transformed using either of two selectable markers: the amdS + gene of Aspergillus nidulans, which encodes acetamidase and permits growth on acetamide as the sole nitrogen source and the hygBR gene of Escherichia coli which encodes hygromycin B (Hy) phosphotransferase and permits growth in the presence of the antibiotic Hy. The amdS+ gene functioned in Gcp under control of A. nidulans regulatory signals and hygBR was expressed after fusion to a promoter from Cochliobolus heterostrophus, another filamentous ascomycete. Protoplasts to be transformed were generated with the digestive enzyme complex Novozym 234 and then were exposed to plasmid DNA in the presence of 10 mM CaCl2 and polyethylene glycol. Transformation occurred by integration of single or multiple copies of either the amdS+ or hygBR plasmid into the fungal genome. There was no evidence of autonomous plasmid replication. Transformants were mitotically stable on selective and nonselective media. However, transforming DNA in hygBR transformants was observed to occasionally rearrange during nonselective growth, resulting in fewer copies of the plasmid per genome. These transformants were capable of infecting bean (Phaseolus vulgaris), the Gcp host plant, and after recovery from infected tissue were found to have retained both the transforming DNA unrearranged in their genomes and the Hy resistance phenotype. All single-conidial cultures derived from both amdS+ and hygBR transformants had the transplanted phenotype, suggesting that transformants were homokaryons.

R-Ras regulates migration through an interaction with filamin A in melanoma cells.

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Joanna E Gawecka

2010-06-01

Full Text Available Changes in cell adhesion and migration in the tumor microenvironment are key in the initiation and progression of metastasis. R-Ras is one of several small GTPases that regulate cell adhesion and migration on the extracellular matrix, however the mechanism has not been completely elucidated. Using a yeast two-hybrid approach we sought to identify novel R-Ras binding proteins that might mediate its effects on integrins.We identified Filamin A (FLNa as a candidate interacting protein. FLNa is an actin-binding scaffold protein that also binds to integrin beta1, beta2 and beta7 tails and is associated with diverse cell processes including cell migration. Indeed, M2 melanoma cells require FLNa for motility. We further show that R-Ras and FLNa interact in co-immunoprecipitations and pull-down assays. Deletion of FLNa repeat 3 (FLNaDelta3 abrogated this interaction. In M2 melanoma cells active R-Ras co-localized with FLNa but did not co-localize with FLNa lacking repeat 3. Thus, activated R-Ras binds repeat 3 of FLNa. The functional consequence of this interaction was that active R-Ras and FLNa coordinately increased cell migration. In contrast, co-expression of R-Ras and FLNaDelta3 had a significantly reduced effect on migration. While there was enhancement of integrin activation and fibronectin matrix assembly, cell adhesion was not altered. Finally, siRNA knockdown of endogenous R-Ras impaired FLNa-dependent fibronectin matrix assembly.These data support a model in which R-Ras functionally associates with FLNa and thereby regulates integrin-dependent migration. Thus in melanoma cells R-Ras and FLNa may cooperatively promote metastasis by enhancing cell migration.

The nitric oxide-sensitive p21Ras-ERK pathway mediates S-nitrosoglutathione-induced apoptosis

International Nuclear Information System (INIS)

Tsujita, Maristela; Batista, Wagner L.; Ogata, Fernando T.; Stern, Arnold; Monteiro, Hugo P.; Arai, Roberto J.

2008-01-01

p21Ras protein plays a critical role in cellular signaling that induces either cell cycle progression or apoptosis. Nitric oxide (NO) has been consistently reported to activate p21Ras through the redox sensitive cysteine residue (118). In this study, we demonstrated that the p21Ras-ERK pathway regulates THP-1 monocyte/macrophage apoptosis induced by S-nitrosoglutathione (SNOG). This was apparent from studies in THP-1 cells expressing NO-insensitive p21Ras (p21Ras C118S ) where the pro-apoptotic action of SNOG was almost abrogated. Three major MAP kinase pathways (ERK, JNK, and p38) that are downstream to p21Ras were investigated. It was observed that only the activation of ERK1/2 MAP kinases by SNOG in THP-1 cells was attributable to p21Ras. The inhibition of the ERK pathway by PD98059 markedly attenuated apoptosis in SNOG-treated THP-1 cells, but had a marginal effect on SNOG-treated THP-1 cells expressing NO-insensitive p21Ras. The inhibition of the JNK and p38 pathways by selective inhibitors had no marked effects on the percentage of apoptosis. The induction of p21Waf1 expression by SNOG was observed in THP-1 cells harboring mutant and wild-type p21Ras, however in cells expressing mutant Ras, the expression of p21Waf1 was significantly attenuated. The treatment of THP-1 cells expressing wild-type p21Ras with PD98059 resulted in significant attenuation of p21Waf1 expression. These results indicate that the redox sensitive p21Ras-ERK pathway plays a critical role in sensing and delivering the pro-apoptotic signaling mediated by SNOG

Expression microarray meta-analysis identifies genes associated with Ras/MAPK and related pathways in progression of muscle-invasive bladder transition cell carcinoma.

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Jonathan A Ewald

Full Text Available The effective detection and management of muscle-invasive bladder Transition Cell Carcinoma (TCC continues to be an urgent clinical challenge. While some differences of gene expression and function in papillary (Ta, superficial (T1 and muscle-invasive (≥T2 bladder cancers have been investigated, the understanding of mechanisms involved in the progression of bladder tumors remains incomplete. Statistical methods of pathway-enrichment, cluster analysis and text-mining can extract and help interpret functional information about gene expression patterns in large sets of genomic data. The public availability of patient-derived expression microarray data allows open access and analysis of large amounts of clinical data. Using these resources, we investigated gene expression differences associated with tumor progression and muscle-invasive TCC. Gene expression was calculated relative to Ta tumors to assess progression-associated differences, revealing a network of genes related to Ras/MAPK and PI3K signaling pathways with increased expression. Further, we identified genes within this network that are similarly expressed in superficial Ta and T1 stages but altered in muscle-invasive T2 tumors, finding 7 genes (COL3A1, COL5A1, COL11A1, FN1, ErbB3, MAPK10 and CDC25C whose expression patterns in muscle-invasive tumors are consistent in 5 to 7 independent outside microarray studies. Further, we found increased expression of the fibrillar collagen proteins COL3A1 and COL5A1 in muscle-invasive tumor samples and metastatic T24 cells. Our results suggest that increased expression of genes involved in mitogenic signaling may support the progression of muscle-invasive bladder tumors that generally lack activating mutations in these pathways, while expression changes of fibrillar collagens, fibronectin and specific signaling proteins are associated with muscle-invasive disease. These results identify potential biomarkers and targets for TCC treatments, and

Literature review : performance of RAP/RAS mixes and new direction.

Science.gov (United States)

2014-04-01

In the last several years reclaimed asphalt pavement (RAP) and recycled asphalt shingles (RAS) have been : widely used in asphalt mixes in Texas. The use of RAP/RAS can significantly reduce the initial cost of : asphalt mixtures, conserve energy, and...

CRISPR/Cas9-mediated gene targeting in Arabidopsis using sequential transformation.

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Miki, Daisuke; Zhang, Wenxin; Zeng, Wenjie; Feng, Zhengyan; Zhu, Jian-Kang

2018-05-17

Homologous recombination-based gene targeting is a powerful tool for precise genome modification and has been widely used in organisms ranging from yeast to higher organisms such as Drosophila and mouse. However, gene targeting in higher plants, including the most widely used model plant Arabidopsis thaliana, remains challenging. Here we report a sequential transformation method for gene targeting in Arabidopsis. We find that parental lines expressing the bacterial endonuclease Cas9 from the egg cell- and early embryo-specific DD45 gene promoter can improve the frequency of single-guide RNA-targeted gene knock-ins and sequence replacements via homologous recombination at several endogenous sites in the Arabidopsis genome. These heritable gene targeting can be identified by regular PCR. Our approach enables routine and fine manipulation of the Arabidopsis genome.

Differential DNA methylation profile of key genes in malignant prostate epithelial cells transformed by inorganic arsenic or cadmium.

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Pelch, Katherine E; Tokar, Erik J; Merrick, B Alex; Waalkes, Michael P

2015-08-01

Previous work shows altered methylation patterns in inorganic arsenic (iAs)- or cadmium (Cd)-transformed epithelial cells. Here, the methylation status near the transcriptional start site was assessed in the normal human prostate epithelial cell line (RWPE-1) that was malignantly transformed by 10μM Cd for 11weeks (CTPE) or 5μM iAs for 29weeks (CAsE-PE), at which time cells showed multiple markers of acquired cancer phenotype. Next generation sequencing of the transcriptome of CAsE-PE cells identified multiple dysregulated genes. Of the most highly dysregulated genes, five genes that can be relevant to the carcinogenic process (S100P, HYAL1, NTM, NES, ALDH1A1) were chosen for an in-depth analysis of the DNA methylation profile. DNA was isolated, bisulfite converted, and combined bisulfite restriction analysis was used to identify differentially methylated CpG sites, which was confirmed with bisulfite sequencing. Four of the five genes showed differential methylation in transformants relative to control cells that was inversely related to altered gene expression. Increased expression of HYAL1 (>25-fold) and S100P (>40-fold) in transformants was correlated with hypomethylation near the transcriptional start site. Decreased expression of NES (>15-fold) and NTM (>1000-fold) in transformants was correlated with hypermethylation near the transcriptional start site. ALDH1A1 expression was differentially expressed in transformed cells but was not differentially methylated relative to control. In conclusion, altered gene expression observed in Cd and iAs transformed cells may result from altered DNA methylation status. Published by Elsevier Inc.

Stable genetic transformation of Jatropha curcas via Agrobacterium tumefaciens-mediated gene transfer using leaf explants

KAUST Repository

Kumar, Nitish

2010-07-01

Jatropha curcas is an oil bearing species with multiple uses and considerable economic potential as a biofuel crop. A simple and reproducible protocol was developed for Agrobacterium tumefaciens-mediated stable genetic transformation of J. curcas using leaf explains. Agrobacterium strain LBA 4404 harbouring the binary vector pCAMBIA 1304 having sense-dehydration responsive element binding (S-DREB2A), beta-glucuronidase (gus), and hygromycin-phosphotransferase (hpt) genes were used for gene transfer. A number of parameters such as preculture of explains, wounding of leaf explants, Agrobacterium growth phase (OD), infection duration, co-cultivation period, co-cultivation medium pH, and acetosyringone, were studied to optimized transformation efficiency. The highest transformation efficiency was achieved using 4-day precultured, non-wounded leaf explants infected with Agrobacterium culture corresponding to OD(600)=0.6 for 20 min, followed by co-cultivation for 4 days in a co-cultivation medium containing 100 mu M acetosyringone, pH 5.7. Co-cultivated leaf explants were initially cultured on Murashige and Skoog (MS) medium supplemented with 2.27 mu M thidiazuron (TDZ) for regeneration of shoot buds, followed by selection on same medium with 5 mu g ml(-1) hygromycin. Selected shoot buds were transferred to MS medium containing 10 mu M kinetin (Kn), 4.5 mu M 6-benzyl aminopurine (BA), and 5.5 mu M alpha-naphthaleneacetic acid (NAA) for proliferation. The proliferated shoots were elongated on MS medium supplemented with 2.25 mu M BA and 8.5 mu M indole-3-acetic acid (IAA). The elongated shoots were rooted on half strength MS medium supplemented with 15 mu M indole-3-butyric acid (IBA), 5.7 mu M IAA, 5.5 mu M NAA, and 0.25 mg l(-1) activated charcoal. GUS histochemical analysis of the transgenic tissues further confirmed the transformation event. PCR and DNA gel blot hybridization were performed to confirm the presence of transgene. A transformation efficiency of 29% was

Stable genetic transformation of Jatropha curcas via Agrobacterium tumefaciens-mediated gene transfer using leaf explants

KAUST Repository

Kumar, Nitish; Vijay Anand, K.G.; Pamidimarri, D.V.N. Sudheer; Sarkar, Tanmoy; Reddy, Muppala P.; Radhakrishnan, T.; Kaul, Tanushri; Reddy, M.K.; Sopori, Sudhir K.

2010-01-01

Jatropha curcas is an oil bearing species with multiple uses and considerable economic potential as a biofuel crop. A simple and reproducible protocol was developed for Agrobacterium tumefaciens-mediated stable genetic transformation of J. curcas using leaf explains. Agrobacterium strain LBA 4404 harbouring the binary vector pCAMBIA 1304 having sense-dehydration responsive element binding (S-DREB2A), beta-glucuronidase (gus), and hygromycin-phosphotransferase (hpt) genes were used for gene transfer. A number of parameters such as preculture of explains, wounding of leaf explants, Agrobacterium growth phase (OD), infection duration, co-cultivation period, co-cultivation medium pH, and acetosyringone, were studied to optimized transformation efficiency. The highest transformation efficiency was achieved using 4-day precultured, non-wounded leaf explants infected with Agrobacterium culture corresponding to OD(600)=0.6 for 20 min, followed by co-cultivation for 4 days in a co-cultivation medium containing 100 mu M acetosyringone, pH 5.7. Co-cultivated leaf explants were initially cultured on Murashige and Skoog (MS) medium supplemented with 2.27 mu M thidiazuron (TDZ) for regeneration of shoot buds, followed by selection on same medium with 5 mu g ml(-1) hygromycin. Selected shoot buds were transferred to MS medium containing 10 mu M kinetin (Kn), 4.5 mu M 6-benzyl aminopurine (BA), and 5.5 mu M alpha-naphthaleneacetic acid (NAA) for proliferation. The proliferated shoots were elongated on MS medium supplemented with 2.25 mu M BA and 8.5 mu M indole-3-acetic acid (IAA). The elongated shoots were rooted on half strength MS medium supplemented with 15 mu M indole-3-butyric acid (IBA), 5.7 mu M IAA, 5.5 mu M NAA, and 0.25 mg l(-1) activated charcoal. GUS histochemical analysis of the transgenic tissues further confirmed the transformation event. PCR and DNA gel blot hybridization were performed to confirm the presence of transgene. A transformation efficiency of 29% was

RAS in Pregnancy and Preeclampsia and Eclampsia

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M. Rodriguez

2012-01-01

Full Text Available Preeclampsia is a common disease of pregnancy characterized by the presence of hypertension and commitment of many organs, including the brain, secondary to generalized endothelial dysfunction. Its etiology is not known precisely, but it involved several factors, highlighting the renin angiotensin system (RAS, which would have an important role in the origin of multisystem involvement. This paper reviews the evidence supporting the involvement of RAS in triggering the disease, in addition to the components of this system that would be involved and how it eventually produces brain engagement.

NMR 1H,13C, 15N backbone and 13C side chain resonance assignment of the G12C mutant of human K-Ras bound to GDP.

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Sharma, Alok K; Lee, Seung-Joo; Rigby, Alan C; Townson, Sharon A

2018-05-02

K-Ras is a key driver of oncogenesis, accounting for approximately 80% of Ras-driven human cancers. The small GTPase cycles between an inactive, GDP-bound and an active, GTP-bound state, regulated by guanine nucleotide exchange factors and GTPase activating proteins, respectively. Activated K-Ras regulates cell proliferation, differentiation and survival by signaling through several effector pathways, including Raf-MAPK. Oncogenic mutations that impair the GTPase activity of K-Ras result in a hyperactivated state, leading to uncontrolled cellular proliferation and tumorogenesis. A cysteine mutation at glycine 12 is commonly found in K-Ras associated cancers, and has become a recent focus for therapeutic intervention. We report here 1 H N, 15 N, and 13 C resonance assignments for the 19.3 kDa (aa 1-169) human K-Ras protein harboring an oncogenic G12C mutation in the GDP-bound form (K-RAS G12C-GDP ), using heteronuclear, multidimensional NMR spectroscopy. Backbone 1 H- 15 N correlations have been assigned for all non-proline residues, except for the first methionine residue.

Enhanced accumulation of atropine in Atropa belladonna transformed by Rac GTPase gene isolated from Scoparia dulcis.

Science.gov (United States)

Asano, Kyouhei; Lee, Jung-Bum; Yamamura, Yoshimi; Kurosaki, Fumiya

2013-12-01

Leaf tissues of Atropa belladonna were transformed by Sdrac2, a Rac GTPase gene, that is isolated from Scoparia dulcis, and the change in atropine concentration of the transformants was examined. Re-differentiated A. belladonna overexpressing Sdrac2 accumulated considerable concentration of atropine in the leaf tissues, whereas the leaves of plants transformed by an empty vector accumulated only a very low concentration of the compound. A. belladonna transformed by CASdrac2, a modified Sdrac2 of which translate was expected to bind guanosine triphosphate (GTP) permanently, accumulated very high concentrations of atropine (approximately 2.4-fold excess to those found in the wild-type plant in its natural habitat). In sharp contrast, the atropine concentration in transformed A. belladonna prepared with negatively modified Sdrac2, DNSdrac2, expected to bind guanosine diphosphate instead of GTP, was very low. These results suggested that Rac GTPases play an important role in the regulation of secondary metabolism in plant cells and that overexpression of the gene(s) may be capable of enhancing the production of natural products accumulated in higher plant cells.

A new variance stabilizing transformation for gene expression data analysis.

Science.gov (United States)

Kelmansky, Diana M; Martínez, Elena J; Leiva, Víctor

2013-12-01

In this paper, we introduce a new family of power transformations, which has the generalized logarithm as one of its members, in the same manner as the usual logarithm belongs to the family of Box-Cox power transformations. Although the new family has been developed for analyzing gene expression data, it allows a wider scope of mean-variance related data to be reached. We study the analytical properties of the new family of transformations, as well as the mean-variance relationships that are stabilized by using its members. We propose a methodology based on this new family, which includes a simple strategy for selecting the family member adequate for a data set. We evaluate the finite sample behavior of different classical and robust estimators based on this strategy by Monte Carlo simulations. We analyze real genomic data by using the proposed transformation to empirically show how the new methodology allows the variance of these data to be stabilized.

Phylogenetic distribution and evolutionary dynamics of the sex determination genes doublesex and transformer in insects.

Science.gov (United States)

Geuverink, E; Beukeboom, L W

2014-01-01

Sex determination in insects is characterized by a gene cascade that is conserved at the bottom but contains diverse primary signals at the top. The bottom master switch gene doublesex is found in all insects. Its upstream regulator transformer is present in the orders Hymenoptera, Coleoptera and Diptera, but has thus far not been found in Lepidoptera and in the basal lineages of Diptera. transformer is presumed to be ancestral to the holometabolous insects based on its shared domains and conserved features of autoregulation and sex-specific splicing. We interpret that its absence in basal lineages of Diptera and its order-specific conserved domains indicate multiple independent losses or recruitments into the sex determination cascade. Duplications of transformer are found in derived families within the Hymenoptera, characterized by their complementary sex determination mechanism. As duplications are not found in any other insect order, they appear linked to the haplodiploid reproduction of the Hymenoptera. Further phylogenetic analyses combined with functional studies are needed to understand the evolutionary history of the transformer gene among insects. © 2013 S. Karger AG, Basel.

Methylation of Promoter Regions of Genes of the Human Intrauterine Renin Angiotensin System and Their Expression

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Shane D. Sykes

2015-01-01

Full Text Available The intrauterine renin angiotensin system (RAS is implicated in placentation and labour onset. Here we investigate whether promoter methylation of RAS genes changes with gestation or labour and if it affects gene expression. Early gestation amnion and placenta were studied, as were term amnion, decidua, and placenta collected before labour (at elective caesarean section or after spontaneous labour and delivery. The expression and degree of methylation of the prorenin receptor (ATP6AP2, angiotensin converting enzyme (ACE, angiotensin II type 1 receptor (AGTR1, and two proteases that can activate prorenin (kallikrein, KLK1, and cathepsin D, CTSD were measured by qPCR and a DNA methylation array. There was no effect of gestation or labour on the methylation of RAS genes and CTSD. Amnion and decidua displayed strong correlations between the percent hypermethylation of RAS genes and CTSD, suggestive of global methylation. There were no correlations between the degree of methylation and mRNA abundance of any genes studied. KLK1 was the most methylated gene and the proportion of hypermethylated KLK1 alleles was lower in placenta than decidua. The presence of intermediate methylated alleles of KLK1 in early gestation placenta and in amnion after labour suggests that KLK1 methylation is uniquely dynamic in these tissues.

Two-dimensional electrophoretic analysis of transformation-sensitive polypeptides during chemically, spontaneously, and oncogene-induced transformation of rat liver epithelial cells

DEFF Research Database (Denmark)

Wirth, P J; Luo, L D; Fujimoto, Y

1992-01-01

; AFB), spontaneously, and oncogene (v-Ha-ras, v-raf, and v-myc/v-raf)-induced transformation of RLE cells. Two-dimensional mapping of [35S]methionine-labeled whole cell lysate, cell-free in vitro translation products and [32P]orthophosphate-labeled polypeptides revealed subsets of polypeptides specific...... for each transformation modality. A search of the RLE protein database indicated the specific subcellular location for the majority of these transformation-sensitive proteins. Significant alterations in the expression of the extracellular matrix protein, fibronectin, as well as tropomyosin......- and intermediate filament-related polypeptides (vimentin, beta-tubulin, the cytokeratins, and actin) were observed among the various transformant cell lines. Immunoprecipitation and Western immunoblot analysis of tropomyosin expression in four individual AFB-, as well as four spontaneously induced, and each...

Mechanisms of Membrane Binding of Small GTPase K-Ras4B Farnesylated Hypervariable Region*

Science.gov (United States)

Jang, Hyunbum; Abraham, Sherwin J.; Chavan, Tanmay S.; Hitchinson, Ben; Khavrutskii, Lyuba; Tarasova, Nadya I.; Nussinov, Ruth; Gaponenko, Vadim

2015-01-01

K-Ras4B belongs to a family of small GTPases that regulates cell growth, differentiation and survival. K-ras is frequently mutated in cancer. K-Ras4B association with the plasma membrane through its farnesylated and positively charged C-terminal hypervariable region (HVR) is critical to its oncogenic function. However, the structural mechanisms of membrane association are not fully understood. Here, using confocal microscopy, surface plasmon resonance, and molecular dynamics simulations, we observed that K-Ras4B can be distributed in rigid and loosely packed membrane domains. Its membrane binding domain interaction with phospholipids is driven by membrane fluidity. The farnesyl group spontaneously inserts into the disordered lipid microdomains, whereas the rigid microdomains restrict the farnesyl group penetration. We speculate that the resulting farnesyl protrusion toward the cell interior allows oligomerization of the K-Ras4B membrane binding domain in rigid microdomains. Unlike other Ras isoforms, K-Ras4B HVR contains a single farnesyl modification and positively charged polylysine sequence. The high positive charge not only modulates specific HVR binding to anionic phospholipids but farnesyl membrane orientation. Phosphorylation of Ser-181 prohibits spontaneous farnesyl membrane insertion. The mechanism illuminates the roles of HVR modifications in K-Ras4B targeting microdomains of the plasma membrane and suggests an additional function for HVR in regulation of Ras signaling. PMID:25713064

Genetic alterations in B-cell non-Hodgkin's lymphoma

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Magić Zvonko

2005-01-01

Full Text Available Background. Although the patients with diagnosed B-NHL are classified into the same disease stage on the basis of clinical, histopathological, and immunological parameters, they respond significantly different to the applied treatment. This points out the possibility that within the same group of lymphoma there are different diseases at molecular level. For that reason many studies deal with the detection of gene alterations in lymphomas to provide a better framework for diagnosis and treatment of these hematological malignancies. Aim. To define genetic alterations in the B-NHL with highest possibilities for diagnostic purposes and molecular detection of MRD. Methods. Formalin fixed and paraffin embedded lymph node tissues from 45 patients were examined by different PCR techniques for the presence of IgH and TCR γ gene rearrangement; K-ras and H-ras mutations; c-myc amplification and bcl-2 translocation. There were 34 cases of B-cell non-Hodgkin’s lymphoma (B-NHL, 5 cases of T-cell non-Hodgkin’s lymphoma (T-NHL and 6 cases of chronic lymphadenitis (CL. The mononuclear cell fraction of the peripheral blood of 12 patients with B-NHL was analyzed for the presence of monoclonality at the time of diagnosis and in 3 to 6 months time intervals after an autologous bone marrow transplantation (BMT. Results. The monoclonality of B-lymphocytes, as evidenced by DNA fragment length homogeneity, was detected in 88 % (30/34 of B-NHL, but never in CL, T-NHL, or in normal PBL. Bcl-2 translocation was detected in 7/31 (22.6% B-NHL specimens, c-myc amplification 9/31 (29%, all were more than doubled, K-ras mutations in 1/31 (3.23% and H-ras mutations in 2/31 (6.45% of the examined B-NHL samples. In the case of LC and normal PBL, however, these gene alterations were not detected. All the patients (12 with B-NHL had dominant clone of B-lymphocyte in the peripheral blood at the time of diagnosis while only in 2 of 12 patients MRD was detected 3 or 6 months after

Development of a Candida glabrata dominant nutritional transformation marker utilizing the Aspergillus nidulans acetamidase gene (amdS).

Science.gov (United States)

Fu, Jianmin; Blaylock, Morganne; Wickes, Cameron F; Welte, William; Mehrtash, Adrian; Wiederhold, Nathan; Wickes, Brian L

2016-05-01

The gene encoding Aspergillus nidulans acetamidase (amdS) was placed under control of Candida albicans ACT1 promoter and terminator sequences and then cloned into a plasmid containing C. glabrata ARS10,CEN8 or ARS10+CEN8 sequences. All plasmids transformed C. glabrata wild-type cells to acetamide+, with the ARS-only containing plasmid transforming cells at the highest frequencies (>1.0 × 10(4) transformants μg(-1)). Plasmids were rapidly lost under non-selective conditions with the frequency dependent on chromosomal element, thus recycling the acetamide- phenotype. The amdS plasmid was used to transform a set of clinical isolates resistant to a variety of antifungal drugs. All strains were successfully transformed to the acetamide+ phenotype at high frequency, confirming that this plasmid construct could be used as a simple dominant marker on virtually any strain. Gap repair experiments demonstrated that just as in Saccharomyces cerevisiae, gap repair functions efficiently inC. glabrata, suggesting that C. glabrata has numerous similarities toS. cerevisiae with regard to ease of molecular manipulation. The amdS system is inexpensive and efficient, and combined with existing C. glabrata plasmid elements, confers a high transformation frequency for C. glabrata with a phenotype that can be easily recycled. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Exogenous Gene Integration for Microalgal Cell Transformation Using a Nanowire-Incorporated Microdevice.

Science.gov (United States)

Bae, Sunwoong; Park, Seunghye; Kim, Jung; Choi, Jong Seob; Kim, Kyung Hoon; Kwon, Donguk; Jin, EonSeon; Park, Inkyu; Kim, Do Hyun; Seo, Tae Seok

2015-12-16

Superior green algal cells showing high lipid production and rapid growth rate are considered as an alternative for the next generation green energy resources. To achieve the biomass based energy generation, transformed microalgae with superlative properties should be developed through genetic engineering. Contrary to the normal cells, microalgae have rigid cell walls, so that target gene delivery into cells is challengeable. In this study, we report a ZnO nanowire-incorporated microdevice for a high throughput microalgal transformation. The proposed microdevice was equipped with not only a ZnO nanowire in the microchannel for gene delivery into cells but also a pneumatic polydimethylsiloxane (PDMS) microvalve to modulate the cellular attachment and detachment from the nanowire. As a model, hygromycin B resistance gene cassette (Hyg3) was functionalized on the hydrothermally grown ZnO nanowires through a disulfide bond and released into green algal cells, Chlamydomonas reinhardtii, by reductive cleavage. During Hyg3 gene delivery, a monolithic PDMS membrane was bent down, so that algal cells were pushed down toward ZnO nanowires. The supply of vacuum in the pneumatic line made the PDMS membrane bend up, enabling the gene delivered algal cells to be recovered from the outlet of the microchannel. We successfully confirmed Hyg3 gene integrated in microalgae by amplifying the inserted gene through polymerase chain reaction (PCR) and DNA sequencing. The efficiency of the gene delivery to algal cells using the ZnO nanowire-incorporated microdevice was 6.52 × 10(4)- and 9.66 × 10(4)-fold higher than that of a traditional glass bead beating and electroporation.

Assessment of ptxD gene as an alternative selectable marker for Agrobacterium-mediated maize transformation.

Science.gov (United States)

Nahampun, Hartinio N; López-Arredondo, Damar; Xu, Xing; Herrera-Estrella, Luis; Wang, Kan

2016-05-01

Bacterial phosphite oxidoreductase gene and chemical phosphite can be used as a selection system for Agrobacterium -mediated maize transformation. Application of phosphite (Phi) on plants can interfere the plant metabolic system leading to stunted growth and lethality. On the other hand, ectopic expression of the ptxD gene in tobacco and Arabidopsis allowed plants to grow in media with Phi as the sole phosphorous source. The phosphite oxidoreductase (PTXD) enzyme catalyzes the conversion of Phi into phosphate (Pi) that can then be metabolized by plants and utilized as their essential phosphorous source. Here we assess an alternative selectable marker based on a bacterial ptxD gene for Agrobacterium-mediated maize transformation. We compared the transformation frequencies of maize using either the ptxD/Phi selection system or a standard herbicide bar/bialaphos selection system. Two maize genotypes, a transformation amenable hybrid Hi II and an inbred B104, were tested. Transgene presence, insertion copy numbers, and ptxD transcript levels were analyzed and compared. This work demonstrates that the ptxD/Phi selection system can be used for Agrobacterium-mediated maize transformation of both type I and type II callus culture and achieve a comparable frequency as that of the herbicide bar/bialaphos selection system.

Analisis Kelembagaan Rantai Pasok Telur Ayam Ras Peternakan Rakyat Di Jawa Barat

OpenAIRE

Sejati, Wahyuning K

2011-01-01

Dalam konteks pengembangan pasar komoditas dan peningkatan kesejahteraan peternak rakyat perlu dipahami secara baik karakteristik dan kelembagaan petani, pemasok, dan pasar. Tulisan ini bertujuan untuk menganalisis kelembagaan rantai pasok peternak-pemasok-pasar komoditas telur ayam ras yang meliputi: (1) identifikasi kelembagaan peternakan rakyat ayam ras petelur; (2) analisis kelembagaan rantai pasok komoditas telur; dan (3) antisipasi kelembagaan introduksi rantai pasok telur ayam ras pete...

Quantum Noether identities for non-local transformations in higher-order derivatives theories

International Nuclear Information System (INIS)

Li, Z.P.; Long, Z.W.

2003-01-01

Based on the phase-space generating functional of the Green function for a system with a regular/singular higher-order Lagrangian, the quantum canonical Noether identities (NIs) under a local and non-local transformation in phase space have been deduced, respectively. For a singular higher-order Lagrangian, one must use an effective canonical action I eff P in quantum canonical NIs instead of the classical I P in classical canonical NIs. The quantum NIs under a local and non-local transformation in configuration space for a gauge-invariant system with a higher-order Lagrangian have also been derived. The above results hold true whether or not the Jacobian of the transformation is equal to unity or not. It has been pointed out that in certain cases the quantum NIs may be converted to conservation laws at the quantum level. This algorithm to derive the quantum conservation laws is significantly different from the quantum first Noether theorem. The applications of our formulation to the Yang-Mills fields and non-Abelian Chern-Simons (CS) theories with higher-order derivatives are given, and the conserved quantities at the quantum level for local and non-local transformations are found, respectively. (orig.)

Mechanisms of membrane binding of small GTPase K-Ras4B farnesylated hypervariable region.

Science.gov (United States)

Jang, Hyunbum; Abraham, Sherwin J; Chavan, Tanmay S; Hitchinson, Ben; Khavrutskii, Lyuba; Tarasova, Nadya I; Nussinov, Ruth; Gaponenko, Vadim

2015-04-10

K-Ras4B belongs to a family of small GTPases that regulates cell growth, differentiation and survival. K-ras is frequently mutated in cancer. K-Ras4B association with the plasma membrane through its farnesylated and positively charged C-terminal hypervariable region (HVR) is critical to its oncogenic function. However, the structural mechanisms of membrane association are not fully understood. Here, using confocal microscopy, surface plasmon resonance, and molecular dynamics simulations, we observed that K-Ras4B can be distributed in rigid and loosely packed membrane domains. Its membrane binding domain interaction with phospholipids is driven by membrane fluidity. The farnesyl group spontaneously inserts into the disordered lipid microdomains, whereas the rigid microdomains restrict the farnesyl group penetration. We speculate that the resulting farnesyl protrusion toward the cell interior allows oligomerization of the K-Ras4B membrane binding domain in rigid microdomains. Unlike other Ras isoforms, K-Ras4B HVR contains a single farnesyl modification and positively charged polylysine sequence. The high positive charge not only modulates specific HVR binding to anionic phospholipids but farnesyl membrane orientation. Phosphorylation of Ser-181 prohibits spontaneous farnesyl membrane insertion. The mechanism illuminates the roles of HVR modifications in K-Ras4B targeting microdomains of the plasma membrane and suggests an additional function for HVR in regulation of Ras signaling. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

A Chinese Herbal Decoction, Danggui Buxue Tang, Stimulates Proliferation, Differentiation and Gene Expression of Cultured Osteosarcoma Cells: Genomic Approach to Reveal Specific Gene Activation

Directory of Open Access Journals (Sweden)

Roy C. Y. Choi

2011-01-01

Full Text Available Danggui Buxue Tang (DBT, a Chinese herbal decoction used to treat ailments in women, contains Radix Astragali (Huangqi; RA and Radix Angelicae Sinensis (Danggui; RAS. When DBT was applied onto cultured MG-63 cells, an increase of cell proliferation and differentiation of MG-63 cell were revealed: both of these effects were significantly higher in DBT than RA or RAS extract. To search for the biological markers that are specifically regulated by DBT, DNA microarray was used to reveal the gene expression profiling of DBT in MG-63 cells as compared to that of RA- or RAS-treated cells. Amongst 883 DBT-regulated genes, 403 of them are specifically regulated by DBT treatment, including CCL-2, CCL-7, CCL-8, and galectin-9. The signaling cascade of this DBT-regulated gene expression was also elucidated in cultured MG-63 cells. The current results reveal the potential usage of this herbal decoction in treating osteoporosis and suggest the uniqueness of Chinese herbal decoction that requires a well-defined formulation. The DBT-regulated genes in the culture could serve as biological responsive markers for quality assurance of the herbal preparation.

Subcellular Distribution of S-Nitrosylated H-Ras in Differentiated and Undifferentiated PC12 Cells during Hypoxia.

Science.gov (United States)

Barbakadze, Tamar; Goloshvili, Galina; Narmania, Nana; Zhuravliova, Elene; Mikeladze, David

2017-10-01

Hypoxia or exposure to excessive reactive oxygen or nitrogen species could induce S-nitrosylation of various target proteins, including GTPases of the Ras-superfamily. Under hypoxic conditions, the Ras-protein is translocated to the cytosol and interacts with the Golgi complex, endoplasmic reticulum, mitochondria. The mobility/translocation of Ras depend on the cells oxidative status. However, the importance of relocated Snitrosylated- H-Ras (NO-H-Ras) in proliferation/differentiation processes is not completely understood. We have determined the content of soluble- and membrane-bound-NO-HRas in differentiated (D) and undifferentiated (ND) rat pheochromocytoma (PC12) cells under hypoxic and normoxic conditions. In our experimental study, we analyzed NO-H-Ras levels under hypoxic/normoxic conditions in membrane and soluble fractions of ND and D PC12 cells with/without nitric oxide donor, sodium nitroprusside (SNP) treatment. Cells were analyzed by the S-nitrosylated kit, immunoprecipitation, and Western blot. We assessed the action of NO-H-Ras on oxidative metabolism of isolated mitochondria by determining mitochondrial hydrogen peroxide generation via the scopoletin oxidation method and ATPproduction as estimated by the luminometric method. Hypoxia did not influence nitrosylation of soluble H-Ras in ND PC12 cells. Under hypoxic conditions, the nitrosylation of soluble-H-Ras greatly decreased in D PC12 cells. SNP didn't change the levels of nitrosylation of soluble-H-Ras, in either hypoxic or normoxic conditions. On the other hand, hypoxia, per se, did not affect the nitrosylation of membrane-bound-H-Ras in D and ND PC12 cells. SNP-dependent nitrosylation of membrane-bound-H-Ras greatly increased in D PC12 cells. Both unmodified normal and mutated H-Ras enhanced the mitochondrial synthesis of ATP, whereas the stimulatory effects on ATP synthesis were eliminated after S-nitrosylation of H-Ras. According to the results, it may be proposed that hypoxia can decrease S