Tumor genetic heterogeneity analysis of chronic sun-damaged melanomas
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE139362 | GEO | 2020/05/19
REPOSITORIES: GEO
Similar Datasets
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:Among the myriad tumors analyzed to date, cutaneous malignant melanomas bear some of the highest mutational burdens. Thus, it is somewhat surprising that oncogene exclusion between is so pronounced in melanomas where there is only a single melanoma out of 366 sequenced specimens which harbors concurrent BRAF(V600E/M) and NRAS(G13R) mutations (TCGA-ES-A2NC Sample; WWW.bioportal.org), In this senario some NRAS and BRAF mutations co-expressing cells show slow growth phenotypes by under study mechanism. We used Affymetrix GeneChip Expression Arrays to detail the global programme of gene expression underlying oncogenic exclusion and identified distinct classes of up and down-regulated genes during this process.
2018-11-22 | GSE122835 | GEO
Project description:Recent studies revealed trajectories of mutational events in early melanomagenesis, but the accompanying changes in gene expression are far less understood. Therefore, we performed a comprehensive RNA-Seq analysis of laser-microdissected melanocytic nevi (n=23) and primary melanoma samples (n=57) and characterized the molecular mechanisms of early melanoma development. Using self-organizing maps, unsupervised clustering and analysis of pseudotime (PT) dynamics to identify evolutionary trajectories, we describe here two transcriptomic types of melanocytic nevi (N1 and N2) and primary melanomas (M1 and M2). N1/M1 lesions are characterized by pigmentation-type and MITF gene signatures, and a high prevalence of NRAS mutations in M1 melanomas. N2/M2 lesions are characterized by inflammatory-type and AXL gene signatures with an equal distribution of wild type and mutated BRAF and low prevalence of NRAS mutations in M2 melanomas. Interestingly, N1 nevi and M1 melanomas and N2 nevi and M2 melanomas, respectively, cluster together, but there is no clustering in a stage-dependent manner. Transcriptional signatures of M1 melanomas harbour signatures of BRAF/MEK inhibitor resistance and M2 melanomas harbour signatures of anti-PD-1 antibody treatment resistance. Transcriptomic signatures suggest that the epigenetic regulators SMARCA2 and SMARCA4 are differentially involved in the epigenetic programming of the two melanoma types. Pseudotime dynamics of nevus and melanoma samples reflect a switch-like immune-escape mechanism in melanoma development with downregulation of immune genes paralleled by an increasing expression of a cell cycle signature in late-stage melanomas. Taken together, the transcriptome analysis identifies gene signatures and mechanisms underlying development of melanoma in early and late stages with relevance for diagnostics and therapy.
2018-07-19 | GSE112509 | GEO
Project description:Melanoma is the deadliest form of skin cancer with rising incidence and mortality rates. Oncogenic mutation in BRAF gene is the single most frequent genetic alteration in human melanoma; however, this event per se is not sufficient to produce melanoma in vivo. We have investigated whether epigenetic changes, specifically aberrant DNA methylation and dysregulation of gene expression, alone or in combination with this genetic event, are involved in the genesis of human melanoma. We have constructed the whole M-bM-^@M-^XM-bM-^@M-^Xof primary human melanomas in relation to their BRAF mutational status. Our methylation profiling identified a large number of hyper- or hypomethylated genes in melanoma tumors, many of which being novel and having the potential to serve as biomarkers. Gene ontology analysis revealed that gene categories involved in neuronal cell morphology and development, and skin and neurological disorders were highly enriched. Frequently methylated targets included developmental regulatory transcription factors and homeobox genes, which are mostly subjected to bivalent histone marking and Polycomb occupancy in embryonic stem cells. Notably, several genes involved in the MEK-ERK and the PI3K pathways, two of the most frequently perturbed pathways in human melanoma, showed extensive methylation changes. Gene expression profiling identified a long list of dysregulated genes, many of which being involved in melanocytes development and differentiation, and showing concomitant aberrant DNA methylation. Sub-typing of the melanoma tumors based on BRAF mutational status revealed that tumors with a mutated BRAF had distinctive and more pronounced changes in both DNA methylation and gene expression profiles than tumors carrying the wildtype BRAF. The differentially compromised methylome and transcriptome of melanomas (dependent on BRAF mutation) deserves special attention because many epigenetic alterations, including DNA methylation-mediated regulation of gene expression, are potentially reversible. The dichotomous integrity of epigenome in human melanoma holds great promise for the field of personalized medicine. Methylome: Eleven primary human melanoma speciemens versus five normal human melanocyte samples. Transcriptome: Ten primary human melanoma speciemens versus four normal human melanocyte samples
2012-12-31 | E-GEOD-31879 | biostudies-arrayexpress
Project description:One third of BRAF-mutant metastatic melanoma patients treated with combined BRAF and MEK inhibition progress within six months. Treatment options for these patients remain limited. Here we analyse twenty BRAFV600 mutant melanoma metastases derived from 10 patients treated with the combination of debrafenib and trametinib for resistance mechanisms and genetic correlates of response. Resistance mechanisms are identified in 9/11 progressing tumors and MAPK reactivation occurred in 9/10 tumors, commonly via BRAF amplification and mutations activating NRAS and MEK2. Our data confirming that MEK2C125S, but not the synonymous MEK1C121S protein confers resistance to combination therapy, highlight the functional differences between these kinases and the preponderance of MEK2 mutations in combination therapy-resistant melanomas. Exome sequencing did not identify additional progression-specific resistance candidates. Nevertheless, most melanomas carried additional oncogenic mutations at baseline (e.g. RCA1 and AKT3) that activate the MAPK and P13K pathways and are thus predicted to diminish response to MAPK inhibitors. Total RNA obtained from fresh frozen melanoma tumors treated with a combination of dabrafenib and trametinib
2014-12-03 | E-GEOD-61992 | 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 57 lymphnode and subcutaneous melanoma metastases
2010-06-16 | E-GEOD-22153 | biostudies-arrayexpress
Project description:Fifty percent of cutaneous melanomas are driven by activated BRAFV600E, but tumors treated with RAF inhibitors, even when they respond dramatically, rapidly adapt and develop resistance. Thus, there is a pressing need to identify the major mechanisms of intrinsic and adaptive resistance and develop drug combinations that target these resistance mechanisms. In a combinatorial drug screen on a panel of 12 treatment-naïve BRAFV600E mutant melanoma cell lines of varying levels of resistance to MAPK pathway inhibition we identified the combination PLX4720, a targeted inhibitor of mutated BRaf, and lapatinib, an inhibitor of the ERBB family of receptor tyrosine kinases, as synergistically cytotoxic in the subset of cell lines that displayed the most resistance to PLX4720. To identify potential mechanisms of resistance to PLX4720 treatment and synergy with lapatinib treatment we performed a multi-platform functional genomics analysis to profile the genome as well as the transcriptional and proteomic responses of these cell lines to treatment with PLX4720. We found modest levels of resistance correlated with the zygosity of the BRAF V600E allele and RTK mutational status. Layered over base-line resistance was substantial upregulation of many ERBB pathway genes in response to BRaf inhibition, thus generating the vulnerability to combination with lapatinib. The transcriptional responses of ERBB pathway genes are associated with a number of transcription factors, including ETS2 and its associated cofactors that represent a convergent regulatory mechanism conferring synergistic drug susceptibility in the context of diverse mutational landscapes. 12 BRAF mutant melanomas and 4 melanomas with WT BRAF were exposed plx4720 treatment to evaluate their responses after 8 hours of treatment. 5 of the 12 BRAF mutant melanomas responses were also evaluated in response to the treatment of lapatinib alone, masitinib alone, the combination of lapatinib with plx4720, or the combination of masitinib with plx4720. All samples were run in at least triplicate.
2015-09-16 | E-GEOD-68453 | biostudies-arrayexpress
Project description:Melanoma is the deadliest form of skin cancer with rising incidence and mortality rates. Oncogenic mutation in BRAF gene is the single most frequent genetic alteration in human melanoma; however, this event per se is not sufficient to produce melanoma in vivo. We have investigated whether epigenetic changes, specifically aberrant DNA methylation and dysregulation of gene expression, alone or in combination with this genetic event, are involved in the genesis of human melanoma. We have constructed the whole ‘‘of primary human melanomas in relation to their BRAF mutational status. Our methylation profiling identified a large number of hyper- or hypomethylated genes in melanoma tumors, many of which being novel and having the potential to serve as biomarkers. Gene ontology analysis revealed that gene categories involved in neuronal cell morphology and development, and skin and neurological disorders were highly enriched. Frequently methylated targets included developmental regulatory transcription factors and homeobox genes, which are mostly subjected to bivalent histone marking and Polycomb occupancy in embryonic stem cells. Notably, several genes involved in the MEK-ERK and the PI3K pathways, two of the most frequently perturbed pathways in human melanoma, showed extensive methylation changes. Gene expression profiling identified a long list of dysregulated genes, many of which being involved in melanocytes development and differentiation, and showing concomitant aberrant DNA methylation. Sub-typing of the melanoma tumors based on BRAF mutational status revealed that tumors with a mutated BRAF had distinctive and more pronounced changes in both DNA methylation and gene expression profiles than tumors carrying the wildtype BRAF. The differentially compromised methylome and transcriptome of melanomas (dependent on BRAF mutation) deserves special attention because many epigenetic alterations, including DNA methylation-mediated regulation of gene expression, are potentially reversible. The dichotomous integrity of epigenome in human melanoma holds great promise for the field of personalized medicine.
2012-12-31 | GSE31879 | GEO
Project description:BRAF, one of three RAF serine/threonine kinases (ARAF, BRAF and CRAF), plays a major role in the RAS-RAF-MEK-ERK mitogen-activated protein kinase (MAPK) signaling pathway, which mediates cellular responses to growth signals. Recently a high frequency (~60%-70%) of activating BRAF mutations (predominantly V600E) has been reported in malignant melanoma. In order to identify the downstream effects of BRAF signaling on melanoma cell growth and gene expression, cDNA microarray analysis was carried out following BRAF siRNA or MEK1/2 inhibitor (U0126) treatment. Keywords: time series, siRNA time series, siRNA, drug treatment
2013-07-07 | E-GEOD-5481 | biostudies-arrayexpress
Project description:Nearly 50% of cutaneous melanomas carry activating mutations on the BRAF oncogene, and the combination of BRAF- and MEK-inhibitors (BRAF/MEKi) is frequently used for their clinical management. One major drawback of BRAF/MEKi targeted therapy is the rapid development of therapeutic resistance, which can occur via multiple mechanisms, including the metabolic rewiring of cancer cells that often involves the upregulation of mitochondrial bionergetics and NAD+ biosynthetic pathways. mTORC2 is a signaling complex that requires the presence of its essential RICTOR subunit to play its regulatory functions in cell growth and metabolism. mTORC2 is believed to play mostly pro-oncogenic roles in several tumor types, including melanoma. However, bioinformatics analysis of TCGA melanoma patients’ database revealed that low RICTOR levels in tumors correlate with an overall worse clinical outcome. GSEA analysis of low-RICTOR tumors evidenced also a gene expression signature suggestive of activation of mitochondrial energy producing pathways. On these bases, we have hypothesized that inhibition of mTORC2 activity may render BRAFV600E melanoma cells resistant to BRAFi/MEKi. We show here that RICTOR/mTORC2-deficient cells are intrinsically tolerant to BRAFi/MEKi, and anticipate the onset of resistance to BRAFi after sustained drug exposure both in vitro and in vivo, indicating that mTORC2 activity normally opposes the acquisition of targeted therapy resistance in BRAFV600E melanomas. Mechanistically, RICTOR-deficient cells show an enhanced mitochondrial respiratory potential and increased expression of nicotinamide phosphoribosyltransferase (NAMPT) protein, the rate-limiting enzyme of NAD+ salvage pathway, and pharmacological inhibition of these processes in RICTOR-deficient cells is sufficient to restore sensitivity to BRAFi. Thus, our work identifies a novel role for mTORC2 in favoring the responses of BRAF-mutated melanoma cells to targeted therapy, and suggest that the evaluation of the intratumor level of RICTOR may help to predict the responses of melanoma patients to these treatments.
2024-05-23 | PXD045346 | Pride