Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.24 (mitogen-activated protein kinase)
 95,810 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Approximately, 10% to 15% of serous ovarian tumors fall into the category designated as tumors of low malignant potential (LMP). Like their invasive counterparts, LMP tumors may be associated with extraovarian disease, for example, in the peritoneal cavity and regional lymph nodes. However, unlike typical invasive carcinomas, patients generally have a favorable prognosis. The mutational profile also differs markedly from that seen in most serous carcinomas. Typically, LMP tumors are associated with KRAS and BRAF mutations. Interrogation of expression profiles in serous LMP tumors suggested overall redundancy of RAS-MAPK pathway mutations and a distinct mechanism of oncogenesis compared with high-grade ovarian carcinomas. Our findings indicate that activating mutation of the RAS-MAPK pathway in serous LMP may be present in >70% of cases compared with approximately 12.5% in serous ovarian carcinomas. In addition to mutations of KRAS (18%) and BRAF (48%) mutations, ERBB2 mutations (6%), but not EGFR, are prevalent among serous LMP tumors. Based on the expression profile signature observed throughout our serous LMP cohort, we propose that RAS-MAPK pathway activation is a requirement of serous LMP tumor development and that other activators of this pathway are yet to be defined. Importantly, as few nonsurgical options exist for treatment of recurrent LMP tumors, therapeutic targeting of this pathway may prove beneficial, especially in younger patients where maintaining fertility is important.
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PMID:Mutation of ERBB2 provides a novel alternative mechanism for the ubiquitous activation of RAS-MAPK in ovarian serous low malignant potential tumors. 1901 Aug 16

Hyperactivated extracellular signal-regulated kinase (ERK) signaling is common in human cancer and is often the result of activating mutations in BRAF, RAS, and upstream receptor tyrosine kinases. To characterize the mitogen-activated protein kinase/ERK kinase (MEK)/ERK dependence of lung cancers harboring BRAF kinase domain mutations, we screened a large panel of human lung cancer cell lines (n = 87) and tumors (n = 916) for BRAF mutations. We found that non-small cell lung cancers (NSCLC) cells with both V600E and non-V600E BRAF mutations were selectively sensitive to MEK inhibition compared with those harboring mutations in epidermal growth factor receptor (EGFR), KRAS, or ALK and ROS kinase fusions. Supporting its classification as a "driver" mutation in the cells in which it is expressed, MEK inhibition in (V600E)BRAF NSCLC cells led to substantial induction of apoptosis, comparable with that seen with EGFR kinase inhibition in EGFR mutant NSCLC models. Despite high basal ERK phosphorylation, EGFR mutant cells were uniformly resistant to MEK inhibition. Conversely, BRAF mutant cell lines were resistant to EGFR inhibition. These data, together with the nonoverlapping pattern of EGFR and BRAF mutations in human lung cancer, suggest that these lesions define distinct clinical entities whose treatment should be guided by prospective real-time genotyping. To facilitate such an effort, we developed a mass spectrometry-based genotyping method for the detection of hotspot mutations in BRAF, KRAS, and EGFR. Using this assay, we confirmed that BRAF mutations can be identified in a minority of NSCLC tumors and that patients whose tumors harbor BRAF mutations have a distinct clinical profile compared with those whose tumors harbor kinase domain mutations in EGFR.
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PMID:Genetic predictors of MEK dependence in non-small cell lung cancer. 1901 Sep 12

This study examined the status of KRAS and BRAF mutations, in relation to extracellular signal-regulated protein kinase (ERK) activation in 58 ovarian carcinomas to clarify the clinicopathological and prognostic significance of KRAS/BRAF mutations. Somatic mutations of either KRAS or BRAF were identified in 12 (20.6%) out of 58 ovarian carcinomas. The frequency of KRAS/BRAF mutations in conventional serous high-grade carcinomas (4.0% : 1/25) was significantly lower than that in the other histological type (32.3% : 10/31). Phosphorylated ERK1/2 (p-ERK1/2) expression was identified in 18 (38.2%) out of 45 ovarian carcinomas. KRAS/BRAF mutation was significantly correlated with International Federation of Gynecology and Obstetrics (FIGO) stage I, II (P<0.001), and p-ERK1/2 (P<0.001). No significant correlations between KRAS/BRAF mutations or p-ERK1/2 expression and overall survival were found in patients with ovarian carcinoma treated with platinum and taxane chemotherapy (P=0.2460, P=0.9339, respectively). Next, to clarify the roles of ERK1/2 activation in ovarian cancers harbouring KRAS or BRAF mutations, we inactivated ERK1/2 in ovarian cancer cells using CI-1040. Cl-1040 is a compound that selectively inhibits MAP kinase kinase (MEK), an upstream regulator of ERK1/2, and thus prevents ERK1/2 activation. Profound growth inhibition and apoptosis were observed in CI-1040-treated cancer cells with mutations in either KRAS or BRAF in comparison with the ovarian cancer cells containing wild-type sequences. This was evident in both in vitro and in vivo studies. The findings in this study indicate that an activated ERK1/2 pathway is critical to tumour growth and survival of ovarian cancers with KRAS or BRAF mutations. Furthermore, they suggest that the CI-1040-induced phenotypes depend on the mutational status of KRAS and BRAF in ovarian cancers. Therefore, ovarian cancer patients with KRAS or BRAF mutations may benefit from CI-1040 treatment.
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PMID:KRAS or BRAF mutation status is a useful predictor of sensitivity to MEK inhibition in ovarian cancer. 1901 67

After 2006, germline mutations in the KRAS, SOS1, and RAF1 genes were reported to cause Noonan syndrome (NS), in addition to the PTPN11 gene, and now we can find the etiology of disease in approximately 60-70% of NS cases. The aim of this study was to assess the correlation between phenotype and genotype by molecular analysis of the PTPN11, SOS1, KRAS, and RAF1 genes in 59 Korean patients with NS. We found disease-causing mutations in 30 (50.8%) patients, which were located in the PTPN11 (27.1%), SOS1 (16.9%), KRAS (1.7%), and RAF1 (5.1%) genes. Three novel mutations (T59A in PTPN11, K170E in SOS1, S259T in RAF1) were identified. The patients with PTPN11 mutations showed higher prevalences of patent ductus arteriosus and thrombocytopenia. The patients with SOS1 mutations had a lower prevalence of delayed psychomotor development. All patients with RAF1 mutations had hypertrophic cardiomyopathy. Typical facial features and auxological parameters were, on statistical analysis, not significantly different between the groups. The molecular defects of NS are genetically heterogeneous and involve several genes other than PTPN11 related to the RAS-MAPK pathway.
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PMID:PTPN11, SOS1, KRAS, and RAF1 gene analysis, and genotype-phenotype correlation in Korean patients with Noonan syndrome. 1902 Jul 99

Ovarian serous carcinoma (OSC) is the most common and lethal histologic type of ovarian epithelial malignancy. Mutations of TP53 and dysfunction of the Brca1 and/or Brca2 tumor-suppressor proteins have been implicated in the molecular pathogenesis of a large fraction of OSCs, but frequent somatic mutations in other well-established tumor-suppressor genes have not been identified. Using a genome-wide screen of DNA copy number alterations in 36 primary OSCs, we identified two tumors with apparent homozygous deletions of the NF1 gene. Subsequently, 18 ovarian carcinoma-derived cell lines and 41 primary OSCs were evaluated for NF1 alterations. Markedly reduced or absent expression of Nf1 protein was observed in 6 of the 18 cell lines, and using the protein truncation test and sequencing of cDNA and genomic DNA, NF1 mutations resulting in deletion of exons and/or aberrant splicing of NF1 transcripts were detected in 5 of the 6 cell lines with loss of NF1 expression. Similarly, NF1 alterations including homozygous deletions and splicing mutations were identified in 9 (22%) of 41 primary OSCs. As expected, tumors and cell lines with NF1 defects lacked mutations in KRAS or BRAF but showed Ras pathway activation based on immunohistochemical detection of phosphorylated MAPK (primary tumors) or increased levels of GTP-bound Ras (cell lines). The TP53 tumor-suppressor gene was mutated in all OSCs with documented NF1 mutation, suggesting that the pathways regulated by these two tumor-suppressor proteins often cooperate in the development of ovarian carcinomas with serous differentiation.
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PMID:Neurofibromin 1 (NF1) defects are common in human ovarian serous carcinomas and co-occur with TP53 mutations. 1904 15

Mutations in genes coding for transducers participating in the RAS/MAPK pathway have been identified as the molecular cause underlying a group of clinically related developmental disorders with cognitive deficits of variable severity. To determine the spectrum of cognitive defects associated with dysregulation of this signal cascade, we studied the profile of cognitive abilities in patients with mutations affecting the PTPN11, SOS1, HRAS, KRAS, BRAF, RAF1, and MEK1 genes and phenotype-genotype correlations. Our findings support the observation that heterogeneity in cognitive abilities can be at least partially ascribed to the individual affected genes and type of mutation involved. While mutations affecting transducers upstream of RAS were less frequently associated with mental retardation, mutations in downstream components of the pathway were generally associated with a more severe cognitive impairment. Among patients with a heterozygous PTPN11 mutation, the T468M substitution was associated with a mean IQ significantly higher compared to that of individuals carrying the N308D change. Our study provides insights on the range of cognitive abilities in patients with gene mutations causing dysregulation of RAS signaling suggesting that the presence and severity of cognitive involvement can be predicted in part by the gene involved.
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PMID:Cognitive profile of disorders associated with dysregulation of the RAS/MAPK signaling cascade. 1913 93

Dysregulated expression of microRNAs (miRNAs) is associated with a variety of diseases, including colorectal cancer. By comparing more than 200 miRNAs in 13 pairs of matched colorectal cancer and normal adjacent tissue samples through qRT-PCR and microarray analysis, we found a widespread disruption of miRNA expression during colorectal tumorigenesis. In particular, among a panel of presumed targets generated by in silico analysis that may interact with these aberrantly expressed miRNAs, KRAS oncogene has been further experimentally validated as the target of miR-143. First, an inverse correlation between KRAS protein and miR-143 in vivo was found. Second, KRAS expression in Lovo cells was significantly abolished by treatment with miR-143 mimic, whereas miR-143 inhibitor increased KRAS protein level. Third, luciferase reporter assay confirmed that miR-143 directly recognize the 3'-untranslated region of KRAS transcripts. Four, Lovo cells treated with miR-143 inhibitor showed a stimulated cell proliferation, whereas miR-143 overexpression had an opposite effect. Finally, inhibition of KRAS expression by miR-143 inhibits constitutive phosphorylation of ERK1/2. Taken together, the present study provides the first evidences that miR-143 is significant in suppressing colorectal cancer cell growth through inhibition of KRAS translation.
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PMID:Role of miR-143 targeting KRAS in colorectal tumorigenesis. 1913 7

The hedgehog and mitogen-activated protein kinase (MAPK) signaling pathways regulate growth in many tumors, suggesting cooperation between these two pathways in the regulation of cell proliferation. However, interactions between these pathways have not been extensively studied. We assessed cross-talk between hedgehog and MAPK signaling in the regulation of cell proliferation in gastric cancer. We showed that PTCH expression was significantly correlated with extracellular signal-regulated kinase (ERK) 1/2 phosphorylation (P = 0.016) as well as SHH expression (P = 0.034) in the 35 gastric cancers assessed by immunohistochemistry. Indeed, MAPK signaling increased the GLI transcriptional activity and induced the expression of hedgehog target genes in gastric cancer cells. The inductive effect of activated KRAS and mitogen-activated protein/extracellular signal-regulated kinase kinase (MEK) 1 was blocked by the suppressor of fused (SUFU), indicating that MAPK signaling regulates GLI activity via a SUFU-independent process. Moreover, the deletion of the NH2-terminal domain of GLI1 gene resulted in reduced response to MEK1 stimulation. Our results suggest that the KRAS-MEK-ERK cascade has a positive regulatory role in GLI transcriptional activity in gastric cancer.
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PMID:Regulation of the hedgehog signaling by the mitogen-activated protein kinase cascade in gastric cancer. 1914 99

LKB1/STK11 is a multitasking tumour suppressor kinase. Germline inactivating mutations of the gene are responsible for the Peutz-Jeghers hereditary cancer syndrome. It is also somatically inactivated in approximately 30% of non-small-cell lung cancer (NSCLC). Here, we report that LKB1/KRAS mutant NSCLC cell lines are sensitive to the MEK inhibitor CI-1040 shown by a dose-dependent reduction in proliferation rate, whereas LKB1 and KRAS mutations alone do not confer similar sensitivity. We show that this subset of NSCLC is also sensitised to the mTOR inhibitor rapamycin. Importantly, the data suggest that LKB1/KRAS mutant NSCLCs are a genetically and functionally distinct subset and further suggest that this subset of lung cancers might afford an opportunity for exploitation of anti-MAPK/mTOR-targeted therapies.
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PMID:LKB1/KRAS mutant lung cancers constitute a genetic subset of NSCLC with increased sensitivity to MAPK and mTOR signalling inhibition. 1916 1

Noonan, LEOPARD, and cardiofaciocutaneous syndromes (NS, LS, and CFCS) are developmental disorders with overlapping features including distinctive facial dysmorphia, reduced growth, cardiac defects, skeletal and ectodermal anomalies, and variable cognitive deficits. Dysregulated RAS-mitogen-activated protein kinase (MAPK) signal traffic has been established to represent the molecular pathogenic cause underlying these conditions. To investigate the phenotypic spectrum and molecular diversity of germline mutations affecting BRAF, which encodes a serine/threonine kinase functioning as a RAS effector frequently mutated in CFCS, subjects with a diagnosis of NS (N=270), LS (N=6), and CFCS (N=33), and no mutation in PTPN11, SOS1, KRAS, RAF1, MEK1, or MEK2, were screened for the entire coding sequence of the gene. Besides the expected high prevalence of mutations observed among CFCS patients (52%), a de novo heterozygous missense change was identified in one subject with LS (17%) and five individuals with NS (1.9%). Mutations mapped to multiple protein domains and largely did not overlap with cancer-associated defects. NS-causing mutations had not been documented in CFCS, suggesting that the phenotypes arising from germline BRAF defects might be allele specific. Selected mutant BRAF proteins promoted variable gain of function of the kinase, but appeared less activating compared to the recurrent cancer-associated p.Val600Glu mutant. Our findings provide evidence for a wide phenotypic diversity associated with mutations affecting BRAF, and occurrence of a clinical continuum associated with these molecular lesions.
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PMID:Germline BRAF mutations in Noonan, LEOPARD, and cardiofaciocutaneous syndromes: molecular diversity and associated phenotypic spectrum. 1920 69


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