Gene Expression Profiling-Based Identification of Molecular Subtypes in Stage IV Melanoma with Different Clinical Outcome
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ABSTRACT:
ORGANISM(S): Homo sapiens
SUBMITTER: Åke Borg
PROVIDER: E-GEOD-22155 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
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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
Project description:Comparison of gene expression profiles between a primary melanoma and an early metastatic specimen from the same patient will provide essential biological insight into early metastatic processes. The DASL (cDNA mediated annealing, selection, extension and ligation) assay has been used to generate gene expression data for 502 cancer-related genes from very small formalin-fixed sentinel node biopsy (SNB) melanoma samples, this data has been further compared with gene expression of the matched formalin-fixed primary melanoma. Tissue was sampled from twenty-five SNB deposits using laser capture microdissection. The mean number of genes detected using DASL with SNB samples was lower than when using a core of primary melanoma tumor (242 versus 434 genes). A large proportion of SNB samples failed (<240 genes detected) the assay (57.7%). Area of tissue microdissected, RNA concentration and qRT-PCR quality control did not predict performance of samples on the array but age of sampled tissue negatively correlated with number of genes detected (p=0.01). For samples that performed successfully, matched primary samples were available for 10 samples. Gene expression profiles correlated between all matched tumor pairs (Spearman’s rho 0.15-0.80, p<0.01), although a number of genes were differentially expressed between nodal and primary tumors in all tumor pairs. This study demonstrates that the DASL assay can be used to generate gene expression data from small formalin-fixed samples, but not consistently. Differentially expressed genes were identified across 10 matched primary and nodal tumor pairs suggesting that the DASL assay could be used to derive essential biological information about early metastasis. Formalin-fixed paraffin-embedded SNB samples and primary tumors were identified from two study sets. In Study 1, population ascertained melanoma patients were recruited to a cohort in the period from 2000 till the present day. Eight positive SNB samples were identified, from patients whose primary tumors had already been sampled for DASL studies. In Study 2, seventeen positive SNB samples were identified in a study designed to identify predictors of sentinel node positivity and relapse (SNB study). One nodal RNA sample, microdissected from a diagnostic H&E slide, was not sent for DASL analysis because of low RNA concentration (0.37 ng/μl), therefore a total of 26 nodal samples (including 2 replicate samples) were supplied to the Illumina DASL service provider. Of the 11 samples successfully yielding gene expression data, 10 had matched primary samples (e.g., Node_1 and Primary_1) for which gene expression data were available and is presented in this data set.
2011-08-01 | E-GEOD-31139 | biostudies-arrayexpress
Project description:Although mutations in p53 are infrequent in human melanoma, its function is abnormal. In this study, whole genome bead arrays were used to examine the expression of p53 target genes in extracts from 6 melanoma cell lines, compared to extracts derived from diploid human melanocytes and fibroblasts, to provide a global assessment of aberrant p53 function. The expression of these genes was also examined in extracts derived from melanocytes and melanoma cell lines in which p53 expression had been inhibited using shRNA and compared to cells that had been transduced with a control shRNA. Total RNA extracted from 18 samples was analysed representing duplicates of 6 melanoma cell lines, 1 melanocyte cell line and 2 fibroblast cell lines. Melanoma cell lines were compared to normal cell lines. In addition, IgR3, Mel-RM and melanocyte cell lines were transduced with either control shRNA or p53 shRNA to evaluate the effect of p53 on its target genes. Cell lines transduced with control shRNA were compared to cell lines transduced with p53shRNA. Duplicates were analysed.
2011-12-01 | E-GEOD-29361 | biostudies-arrayexpress
Project description:This SuperSeries is composed of the following subset Series: GSE29359: Analysis of p53 target genes in melanoma part 1 GSE29361: Analysis of p53 target genes in melanoma part 2 Refer to individual Series
2011-12-01 | E-GEOD-29377 | 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:Inhibitors of the MAPKs, BRAF and MEK, induce tumor regression in the majority of patients with BRAF-mutant metastatic melanoma. The clinical benefit of MAPK inhibitors is restricted by the development of acquired resistance with half of those who benefit having progressed by 6-7 months and long-term responders uncommon. There remains no agreed treatment strategy on disease progression in these patients. Without published evidence, fears of accelerated disease progression on inhibitor withdrawal have led to the continuation of drugs beyond formal disease progression. We now demonstrate that treatment with MAPK inhibitors beyond disease progression can provide significant clinical benefit, and the withdrawal of these inhibitors led to a marked increase in the rate of disease progression in two patients. We also show that MAPK inhibitors retain partial activity in acquired resistant melanoma by examining drug-resistant clones generated to dabrafenib, trametinib or the combination of these drugs. All resistant sublines displayed a markedly slower rate of proliferation when exposed to MAPK inhibitors, and this coincided with a reduction in MAPK signalling, decrease in BrdU incorporation and S-phase inhibition. This cytostatic effect was also associated diminished levels of cyclin D1 and p-pRb.. Two short-term melanoma cultures generated from resistant tumour biopsies also responded to MAPK inhibition with comparable inhibitory changes in proliferation and MAPK signalling. These data provide a rationale for the continuation of BRAF and MEK inhibitors after disease progression and support the development of clinical trials to examine this strategy. Total RNA obtained from melanooma cell lines treated for 24h with dabrafenib, trametinib or combination of dabrafenib and trametinib
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2014-02-19 | E-GEOD-50509 | biostudies-arrayexpress