Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.10.1 (ERK)
95,504 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To evaluate the role of the MEK/ERK pathway in NSCLC survival, we analyzed NSCLC cell lines that differed in tumor histology and status of p53, Rb, and K-ras. Constitutive ERK1/2 activity was demonstrated in 17 of 19 cell lines by maintenance of ERK1/2 phosphorylation with serum deprivation. Phosphorylation of ERK1/2 correlated with phosphorylation of MEK1/2 and p90RSK, but was inversely correlated with phosphorylation of c-Raf at S259. With serum deprivation, the MEK inhibitors, PD98059 and U0126, inhibited ERK1/2 activity but did not increase apoptosis. PD98059 and U0126 induced cell cycle arrest in G(0)/G(i) in cells with the highest levels of ERK1/2 activity, which correlated with induction of p27 but not p21. To confirm the cytostatic response to MEK inhibitors, we performed transient transfections with dominant negative forms of MEK or ERK. Surprisingly, dominant negative MEK and ERK mutants increased apoptosis without affecting cell cycle or p27 levels. When combined with paclitaxel, MEK inhibitors had no effect on apoptosis. In contrast, dominant negative ERK2 potentiated paclitaxel-induced apoptosis. Our studies show that constitutive ERK1/2 activity in NSCLC cells promotes cellular survival and chemotherapeutic resistance. Moreover, our data are the first to demonstrate divergent cellular responses to inhibition of the MEK/ERK pathway by small molecule inhibitors or dominant negative mutants.
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PMID:Variable apoptotic response of NSCLC cells to inhibition of the MEK/ERK pathway by small molecules or dominant negative mutants. 1218 40

Human pancreatic cancers harbor mutations in the K-ras gene, and these mutations convert the gene oncogenic and constitutively active forms. However, in pancreatic cancer cells little is known about the activation of the downstream pathways of Ras, MEK-ERK and MEKK1-JNK, and their roles in cell survival and proliferation. An analysis of nine pancreatic cancer tissues revealed JNK activation in all tumor samples and ERK activation in three tumor samples. Colony formation assays by transfection of dominant negative mutants of Ras, ERK or MEKK1 into pancreatic cancer cell lines (BxPC-3, PANC-1, MIAPaCa-2 and AsPC-1) and an amnion-derived cell line (FL) revealed that DN-MEKK strongly inhibits the survival of colonies in pancreatic cancer cells, but not in FL cells. In vitro kinase assays and luciferase assays using the Gal4c-Jun system revealed that in pancreatic cancer cells DN-MEKK fails to inhibit JNK activation. In PANC-1 cells, c-Jun was found to be a major component of protein component binding to AP-1 site and CRE, but not in FL cells. The inhibitory effect of DN-MEKK in PANC-1 cells was thought to be the result of the inhibition of c-Jun DNA-binding. The difference of suppression in pancreatic cancer cells and non-pancreatic cancer cells suggested that the MEKK1 pathway mainly contributes to cell survival in pancreatic cancer cells and may provide an advantage for the gene therapy of pancreatic cancers using DN-MEKK expression vectors.
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PMID:Dominant negative MEKK1 inhibits survival of pancreatic cancer cells. 1218 92

The evolutionarily conserved Ras/Raf/MEK/ERK pathway is thought to be essential for proliferation of eukaryotic cells. The human multiple myeloma (MM) cell line 8226 encodes an activated K-ras allele and proliferates without requirement for the main MM growth and survival factor IL-6. Surprisingly, the addition of the MEK1/2 inhibitors PD98059 or U0126 to 8226 cultures at doses that block virtually all ERK1/2 activity had minimal effects on the rapid proliferation of this cell line. In contrast, proliferation of the IL-6-dependent MM cell line, ANBL-6 was blocked by PD98059. Levels of activated forms of the other classical MAP kinases (JNK and p38) were very low during MM cell proliferation and, therefore, do not substitute for the mitogenic activities normally regulated by ERK kinases. These data demonstrate that proliferation of 8226 cells does not require ERK1/2 activity, and suggest that IL-6-independent growth of MM may correlate with independence from a requirement for ERK activity. Other signal transduction pathways that appear to regulate cell cycle progression in these cells were examined.
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PMID:Proliferation of IL-6-independent multiple myeloma does not require the activity of extracellular signal-regulated kinases (ERK1/2). 1220 79

Pancreatic cancer is a leading cause of cancer-related mortality. Treatment has limited efficacy, and 5-year survival rates remain less than 5%. Insights from epidemiology and discoveries in molecular genetics have laid the groundwork for a rational screening strategy for high-risk individuals. High-risk populations include those in their 6th to 8th decades of life, those with a family history of pancreatic cancer, and those with a personal history of tobacco smoking. Roughly 10% of cases are due to an inherited genetic susceptibility. Several familial syndromes with known genetic defects have been implicated, but the majority of familial cases result from as yet undefined genes. Acquired mutations have been identified in the oncogenes K-ras and HER2/neu, and in the tumor suppressor genes p16, p53, SMAD4, and BRCA2. No standard for screening or prevention exists, but strategies employing endoscopic, radiologic, and molecular methods to screen high-risk individuals are under investigation.
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PMID:Pancreatic cancer: epidemiology, genetics, and approaches to screening. 1252 Jun 39

A real-time PCR technique with automated computerized analysis (TaqMan ) was tested to detect K-ras mutations in 66 patients suffering from NSCLC. This technology is characterized by high reproducibility of data and a time-saving analysis procedure. In 11% (7/66) of the tumour specimens and 2% (1/58) of adjacent tumour-free lung specimens a K-ras codon 12 mutation was detected. In adenocarcinomas containing > or =40% tumour cells, however, K-ras mutations were seen in 25% of the cases. The point mutations detected in tumours were GGT right curved arrow TGT in five cases and GGT right curved arrow GTT in two cases. As compared with immunohistochemical parameters, the K-ras mutated group was characterized by a c-erbB-2 negativity (p=0.04) and a smaller number of c-erbB-3 (p=0.02) positive cases. EGFR, bcl-2, p53, Ki-67 and p120 expression did not differ significantly. Determination of the K-ras point mutations by automated TaqMan PCR in NSCLC tumour specimens is feasable and highly specific. Due to its high throughput capacity this method represents a valuable tool for routine screening.
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PMID:Automated real-time PCR to determine K-ras codon 12 mutations in non-small cell lung cancer: comparison with immunohistochemistry and clinico-pathological features. 1296 94

ZD1839 ('Iressa') is an epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) that inhibits EGFR signaling. Emerging evidence indicates that ZD1839 has clinical potential in lung cancer, but very little is known about the molecular characteristics of lung cancers that may determine sensitivity to ZD1839. We examined a panel of 19 lung cancer cell lines to investigate possible association between ZD1839 sensitivity and histological type, expression level and constitutive phosphorylation of EGFR and K-ras gene status. Our results indicate that neither expression level nor constitutive activation status of EGFR seems to predict sensitivity to ZD1839. In addition, ZD1839 sensitivity was not associated with expression of human epidermal growth factor receptor-2 (HER-2), another member of this tyrosine kinase receptor family nor with co-expression of EGFR and HER-2. Finally, no correlation was found between the presence of activating mutations of the K-ras gene, an important downstream mediator of the EGFR-transduced signals and the relative resistance to ZD1839. These findings warrant future study to clarify how ZD1839 inhibits lung cancer cell growth and to find a useful marker for prediction of sensitivity to this novel and promising agent for the treatment of lung cancers.
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PMID:The sensitivity of lung cancer cell lines to the EGFR-selective tyrosine kinase inhibitor ZD1839 ('Iressa') is not related to the expression of EGFR or HER-2 or to K-ras gene status. 1451 85

We performed a retrospective analysis of potential prognostic markers in 260 patients with surgically resected stage I and II non small-cell lung cancer (NSCLC) with a minimum 5-year follow-up. Cox proportional hazard models and Wilcoxon tests were employed to analyze the effect of patient characteristics on survival and disease-free survival (DFS). In the univariate analysis, the following were significant predictors of shorter overall survival: N-stage (N1 vs N0) (p<0.001); T-stage (T2 vs T1) (p<0.001); antigen A (loss vs presence) (p<0.01); cough (present vs absent) (p=0.01); bcl-2 expression (positive vs negative) (p=0.03); age (>63.5 vs <63.5) (p=0.03); mucin (positive vs negative) (p<0.03). The following were significant predictors of shorter DFS: N-stage (p<0.001); T-stage (p=0.001); loss of antigen A (p=0.01); mucin expression (p<0.01); cough (p=0.02); Ki-67 expression (p=0.02) and negative bcl-2 expression (p=0.03). Analysis of survival difference for histologic subtype, degree of differentiation, aneuploidy, %S-phase, codon 12 K-ras mutation, and immunohistochemistry staining for Lewisy, p53, Rb, microvessel count, HER2, E-cadherin and neuroendocrine markers did not reach statistical significance. In multivariate analysis, the following predicted for shorter overall survival: N-stage (p<0.01), antigen A (p=0.01), age (p<0.01), and bcl-2 (p=0.05); and for DFS, N-stage (p<0.01), antigen A (p<0.01), Ki-67 (p=0.03), mucin (p=0.04) and T-stage (p=0.05). Of all the clinical-pathological, proliferative, and biological markers studied, only a few carried independent prognostic significance.
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PMID:Prognostic markers in resected stage I and II non small-cell lung cancer: an analysis of 260 patients with 5 year follow-up. 1472 52

Identification of biomarkers is one of the most promising approaches for the detection of early malignant or even premalignant lesions with the chance of diagnosing early stages of non-small cell lung cancer that could be treated curatively. Alterations of chromosomes (3p, 5q, 9p), genes (Rb, C-myc, C-mos, hTERT), proteins (p16, p53, K-ras, hnRNP A2/B1, MCM2, EGFR, erbB-2, erbB-3, erbB-4) and others can be found in lung cancer. Some of these occur at early stages of the disease and few could serve as potential screening markers. The actual literature is reviewed and the relevance of the different biomarkers for early lung cancer detection is discussed.
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PMID:Biomarkers in non-small cell lung cancer prevention. 1545 56

Despite novel therapies in lung cancer treatment the 5-year survival rate still remains poor. Furthermore, screening concepts for early diagnosis, based on conventional sputum cytology and chest radiography, have so far not demonstrated an impact on decreasing lung-cancer mortality. More specific molecular markers allow new insights in the process of lung carcinogenesis. Furthermore they raise the hope that they provide new tools for early diagnosis and screening of high-risk individuals, determination of prognosis, and identification of innovative treatments. In this review, these perspectives of molecular targets in lung cancer will be discussed and summarised. Angiogenesis-stimulating factors (VEGF, FGF, MMP, etc.), parameters concerning tumour cell proliferation and apoptosis (EGFR, p53, K-ras, rb, bcl-2, etc.) are well known. Several of these genetic factors have already been investigated, but no single parameter has yet gained a sufficient selectivity regarding prognostic significance or therapeutic efficacy. New aspects in the complex tumour-stroma interaction and the interactive, cross-talking signal transduction pathways and recently developed functional genomic approaches, such as DNA microarrays and proteomics might lead to further progress in biological staging models and treatment concepts.
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PMID:Molecular oncology--perspectives in lung cancer. 1555 1

To understand the role of BRAF dysfunction in the carcinogenesis and progression/development of colorectal tumors, the authors investigated genetic alterations in the BRAF gene in human colorectal neoplasms as well as the effects of an RAS inhibitor in BRAF-mutant cells. Seven colon cancer cell lines and 116 colorectal tumors (34 adenomas and 82 adenocarcinomas) were analyzed. Genetic alterations in the BRAF and K-ras genes were examined using polymerase chain reaction-single strand conformation polymorphism and direct sequencing analyses. The growth-inhibitory and apoptosis-inducing effects of the FTI-277 RAS inhibitor in colon cancer cell lines were analyzed as well. An immunohistochemical study was also performed to investigate the correlations between the clinicopathologic parameters involved in the Ki-67 labeling index and the number of apoptotic bodies in tumor cells. FTI-277 did not suppress the proliferation of BRAF-mutant cells (WiDr and TCO), but remarkably inhibited the growth of K-ras mutant cells (LoVo). Interestingly, LoVo cells underwent apoptosis by FTI-277 in a dose-dependent manner, whereas WiDr cells were resistant to this agent. In tumor samples, BRAF mutations were found in 1 (3.0%) of 33 adenomas and 6 (7.2%) of 83 adenocarcinomas. No tumor exhibited mutations in both the BRAF and K-ras genes. Neither BRAF nor K-ras mutations correlated with the Ki-67 labeling index immunohistochemically. However, the number of apoptotic bodies was significantly decreased in the BRAF-mutant tumors. Mutation in the BRAF gene may contribute to colorectal carcinogenesis by upregulating the antiapoptotic role of the RAS/RAF/MEK/ERK pathway.
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PMID:BRAF mutation associated with dysregulation of apoptosis in human colorectal neoplasms. 1572 18


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