Expression data from second oncogene expressing Melanoma Cells.
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE122835 | GEO | 2018/11/22
REPOSITORIES: GEO
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Project description:The oncogenic mutation BRAFV600E is a common event in nevi and melanomas, which are aggressive skin tumors characterized by MAPK signaling pathway activation. It has been observed that mutated benign melanocytic lesions can remain unchanged for decades, but also proliferate or undergo oncogene-induced senescence. The purpose of this study was to investigate the presence of a gene expression signature in BRAFV600E mutated nevi compared to wild-type ones, all derived from sun exposed sites. Microdissected tissues from excisional biopsies of acquired nevi were analyzed to detect the presence of BRAF and NRAS mutations and to profile whole genome expression by means of oligonucleotide microarrays. BRAFV600E mutation was evidenced in 64% of nevi, while no NRAS mutations were detected. Functional analysis of genes differentially expressed between wild-type and mutated lesions pointed out the role of oxidative stress in causing the oncogenic BRAF mutation and that the direct consequence of constitutive activation of BRAF-MEK-ERK pathway, in a benign contest, is the activation of apoptosis, autophagy and senescence. Our data also indicate that in mutated lesions, p53 plays a crucial role in the maintenance of the benign status. In our study, in order to understand the role of BRAF mutation in acquired nevi, we performed gene expression profiling analysis on fourteen lesions derived from intermittently exposed sites, using whole genome oligonucleotide microarrays. Expression data were coupled with sequencing results on BRAF and NRAS genes and class comparison algorithms were applied to detect sequences differentially expressed between BRAFV600E and BRAFwt-NRASwt lesions. Some of the obtained results were further validated by Real-Time RT-PCR on an independent cohort of samples. Mutation analysis evidenced BRAF mutations in 64% of the common acquired nevi. All the mutations consisted in the substitution V600E (T1799A). No alteration was found on exon 11 of the BRAF gene nor on exons 1 and 2 of the NRAS gene, as expected since no lesion came from chronically exposed sites. Transcriptome analysis was carried out using oligo-microarrays and differential expression was tested applying the Linear Models package LIMMA available at www.bioconductor.org that uses Bayesian statistics to compute the probability of a gene being differentially expressed. Only 25 transcripts had B value greater then 2. We then performed a one-way ANOVA, dividing samples into three classes according to their BRAF mutational status (wt, ++, +++) as assessed by pyrosequencing. We found 2882 known transcripts by selecting those with ANOVA p-value<0.01 and increasing or decreasing expression trends along the three classes. Functional analysis was performed using the MetaCoreTM software package to identify overrepresented functional processes. BRAF signature, acquired nevi, gene expression profiling "++ and +++" refer to the percentage of alleles carrying the mutation in the *BRAF*V600E lesions. This has been assessed by pyrosequencing analysis (Venesio et al, 2008. PMID= 18408659).
2016-06-30 | E-GEOD-23976 | biostudies-arrayexpress
Project description:In an effort to understand the mechanisms of acquired resistance to BRAF inhibitors, we isolated clones that acquired resistance to the BRAF inhibitor GSK2118436 derived from the A375 BRAF V600E mutant melanoma cell line. This resistance clones acquired mutations in NRAS and MEK1. One clones, 16R6-4, acquired two mutations in NRAS – Q61K and A146T. Proliferation and western blot analyses demonstrated that these clones were insensitive to single agent GSK2118436 or GSK1120212 (an allosteric MEK inhibitor) but were sensitive to the combination of GSK2118436 and GSK1120212. To further characterize this combination, global transcriptomic analysis was performed in A375 and 16R6-4 after 24 hour treatment with GSK2118436, GSK1120212 or the combination of GSK2118436 and GSK1120212. This data set was published in Molecular Cancer Therapeutics with the title “Combined inhibition of BRAF and MEK, BRAF and PI3K/mTOR, or MEK and PI3K/mTOR overcomes acquired resistance to the BRAF inhibitor GSK2118436, mediated by NRAS or MEK mutations” by Greger, J.G., et.al.
2012-02-01 | GSE35230 | GEO
Project description:In an effort to understand the mechanisms of acquired resistance to BRAF inhibitors, we isolated clones that acquired resistance to the BRAF inhibitor GSK2118436 derived from the A375 BRAF V600E mutant melanoma cell line. This resistance clones acquired mutations in NRAS and MEK1. One clones, 16R6-4, acquired two mutations in NRAS – Q61K and A146T. Proliferation and western blot analyses demonstrated that these clones were insensitive to single agent GSK2118436 or GSK1120212 (an allosteric MEK inhibitor) but were sensitive to the combination of GSK2118436 and GSK1120212. To further characterize this combination, global transcriptomic analysis was performed in A375 and 16R6-4 after 24 hour treatment with GSK2118436, GSK1120212 or the combination of GSK2118436 and GSK1120212. This data set was published in Molecular Cancer Therapeutics with the title “Combined inhibition of BRAF and MEK, BRAF and PI3K/mTOR, or MEK and PI3K/mTOR overcomes acquired resistance to the BRAF inhibitor GSK2118436, mediated by NRAS or MEK mutations” by Greger, J.G., et.al. A375 and 16R6-4 (an A375 derived GSK2118436 resistance clone) were treated for 24 hours with 0.1 micromolar GSK2118436, 1 micromolar GSK2118436, 0.01 micromolar GSK1120212, 0.1 micromolar GSK2118436 + 0.01 micromolar GSK1120212, or 1 micromolar GSK2118436 + 0.01 micromolar GSK1120212.
2012-02-01 | E-GEOD-35230 | biostudies-arrayexpress
Project description:We found that pigmented and amelanotic (MPNST-like) melanomas arise in the genetically engineered BRAF(V600E)-Cdk4(R24C) mouse melanoma model and even in the same animal. To explore the molecular differences between the two type of melanomas in this model we performed global gene expression profiling and pathway analysis to compare the underlying mechanisms. This information was used to identify human melanomas that resemble each type of the mouse melanomas found in the in the genetically engineered BRAF(V600E)-Cdk4(R24C) mouse melanoma model.
2015-12-01 | GSE71879 | GEO
Project description:Primary outcome(s): Describe frequency of BRAF mutations (V600E and non-V600E mutations) in KRAS/NRAS wild-type metastatic colorectal adenocarcinoma.
| 2636275 | ecrin-mdr-crc
Project description:<p>Desmoplastic melanoma is an infrequent variant of melanoma with sarcomatous histology, distinct clinical behavior, and unknown pathogenesis. We performed low-coverage genome and high-coverage exome sequencing of 20 desmoplastic melanomas, followed by targeted sequencing of 293 genes to validate candidate genes. A high mutation burden (median 62 mutations/Mb) ranked desmoplastic melanoma among the most highly mutated cancers. Mutation patterns strongly implicate UV-radiation as the dominant mutagen, indicating a superficially located cell of origin. Novel alterations included recurrent promoter mutations of NF-kappa B inhibitor epsilon, NFKBIE (IkBε) in 14.5% of samples. Commonly mutated oncogenes in melanomas, in particular BRAF(V600E) and NRAS(Q61K/R), were absent. Instead, other genetic alterations known to activate the MAPK and PI3K signaling cascades were identified in 73% of samples, affecting NF1, CBL, ERBB2, MAP2K1, MAP3K1, BRAF, EGFR, PTPN11, MET, RAC1, SOS2, NRAS, and PIK3CA, some of which being candidates for targeted therapies.</p> <p><i>Reprinted from:</i><br/> Shain, A. H. et al. Exome sequencing of desmoplastic melanoma identifies recurrent NFKBIE promoter mutations and diverse activating mutations in the MAPK pathway. <i>Nat. Genet. <br/> With permission from Nature Genetics</i> </p>
| phs000977 | dbGaP
Project description:Melanomas on mucosal membranes, acral skin (soles, palms, and nail bed), and skin with chronic sun-induced damage have infrequent mutations in BRAF and NRAS, genes within the mitogenactivated protein (MAP) kinase pathway commonly mutated in melanomas on intermittently sun-exposed skin. This raises the question of whether other aberrations are occurring in the MAP kinase cascade in the melanoma types with infrequent mutations of BRAF and NRAS. Oncogenic mutations in KIT were found in three of seven tumors with amplifications. Examination of all 102 primary melanomas found mutations and/or copy number increases of KIT in 39% ofmucosal, 36% of acral, and 28% of melanomas on chronically sun-damaged skin, but not in any (0%) melanomas on skin without chronic sun damage. Seventy-nine percent of tumors with mutations and 53% of tumors with multiple copies of KIT demonstrated increased KIT protein levels. KIT is an important oncogene in melanoma. Because the majority of the KIT mutations we found in melanoma also occur in imatinib-responsive cancers of other types, imatinib may offer an immediate therapeutic benefit for a significant proportion of the global melanoma burden. Keywords: melanoma, oncogene, comparative genomic hybridization, KIT
2006-09-09 | GSE4747 | GEO
Project description:We studied the effects of endogenous expression of the melanoma oncogene RAC1 P29S in BRAF V600E;PTEN hemizygous mouse melanomas.
2018-08-10 | GSE118344 | GEO
Project description:Purpose: The incidence of malignant melanoma is increasing worldwide in fair-skinned populations. Melanomas respond poorly to systemic therapy, and metastatic melanomas inevitably become fatal. Although spontaneous regression, likely due to immune defense activation, rarely occurs, we lack a biological rationale and predictive markers in selecting patients for immune therapy. Experimental Design: We performed unsupervised hierarchical clustering of global gene expression data from stage IV melanomas in 57 patients. For further characterization, we used immunohistochemistry of selected markers, genome-wide DNA copy number analysis, genetic and epigenetic analysis of the Q3 CDKN2A locus, and NRAS/BRAF mutation screening. Results: The analysis revealed four distinct subtypes with gene signatures characterized by expression of immune response, pigmentation differentiation, proliferation, or stromal composition genes. Although all subtypes harbored NRAS and BRAF mutations, there was a significant difference between subtypes (P < 0.01), with no BRAF/NRAS wild-type samples in the proliferative subtype. Additionally, the proliferative subtype was characterized by a high frequency of CDKN2A homozygous deletions (P < 0.01). We observed a different prognosis between the subtypes (P = 0.01), with a particularly poor survival for patients harboring tumors of the proliferative subtype compared with the others (P = 0.003). Importantly, the clinical relevance of the subtypes was validated in an independent cohort of 44 stage III and IV melanomas. Moreover, low expression of an a priori defined gene set associated with immune response signaling was significantly associated with poor outcome (P = 0.001). Conclusions: Our data reveal a biologically based taxonomy of malignant melanomas with prognostic effect and support an influence of the antitumoral immune response on outcome. Expression profiles of 57 lymphnode and subcutaneous melanoma metastases
2010-06-16 | E-GEOD-22153 | biostudies-arrayexpress
Project description:Purpose: The incidence of malignant melanoma is increasing worldwide in fair-skinned populations. Melanomas respond poorly to systemic therapy, and metastatic melanomas inevitably become fatal. Although spontaneous regression, likely due to immune defense activation, rarely occurs, we lack a biological rationale and predictive markers in selecting patients for immune therapy. Experimental Design: We performed unsupervised hierarchical clustering of global gene expression data from stage IV melanomas in 57 patients. For further characterization, we used immunohistochemistry of selected markers, genome-wide DNA copy number analysis, genetic and epigenetic analysis of the Q3 CDKN2A locus, and NRAS/BRAF mutation screening. Results: The analysis revealed four distinct subtypes with gene signatures characterized by expression of immune response, pigmentation differentiation, proliferation, or stromal composition genes. Although all subtypes harbored NRAS and BRAF mutations, there was a significant difference between subtypes (P < 0.01), with no BRAF/NRAS wild-type samples in the proliferative subtype. Additionally, the proliferative subtype was characterized by a high frequency of CDKN2A homozygous deletions (P < 0.01). We observed a different prognosis between the subtypes (P = 0.01), with a particularly poor survival for patients harboring tumors of the proliferative subtype compared with the others (P = 0.003). Importantly, the clinical relevance of the subtypes was validated in an independent cohort of 44 stage III and IV melanomas. Moreover, low expression of an a priori defined gene set associated with immune response signaling was significantly associated with poor outcome (P = 0.001). Conclusions: Our data reveal a biologically based taxonomy of malignant melanomas with prognostic effect and support an influence of the antitumoral immune response on outcome. Expression profiles of 20 liver and lymphnode metastases. MM76 and MM23 were made in duplicate. Used as validationset in Jönsson et al. Clin Can Res 2010.
2010-06-16 | E-GEOD-22154 | biostudies-arrayexpress