Project description:Chromosome 3p monosomy is associated with a poor clinical outcome of patients with uveal melanoma. Since a copy of the tumor suppressor miR-16 gene is lost for these patients, we postulated that a 3p loss may reduce the miR-16 amount and activity, promoting RNA derepression and tumor burden (loss of brake effect) as observed in chronic lymphocytic leukemia. Unexpectedly, we found that miR-16 expression level is not decreased despite the 3p monosomy. In contrast, our results suggested that miR-16 activity is impaired in uveal melanoma. Here, we investigated the molecular mechanism explaining the sequestration of miR-16 by RNAs. By defining the miR-16 interactome, two genes sets have been highlighted, suggesting two divergent miR-16 functions. In addition to the canonical miR-16 targets such as CCND3 and CDC25A, we identified another set of miR-16-interacting RNAs called thereafter miR-16 sponges. miR-16 binds to these RNAs sponge without inducing their decay. Mechanistically, the miR-16/RNA non-canonical base-pairing promoted stability of mRNAs involved in cancer cell proliferation. The biological relevance has been challenged in uveal melanoma. We showed that patients with poor overall survival expressed higher levels of miR-16 sponges and canonical miR-16 targets. These results strongly suggested that miR-16 is no longer able to repress its targets and, in contrast, promotes RNA stability and protein expression of oncogenes. miR-16 activity assessment using our Sponge-signature discriminates the patient’s overall survival as efficiently as the current method based on copy number variations and driver mutations detection. To conclude, miRNA loss of function due to miRNA sequestration seems to promote cancer burden by two combined events – 'loss of brake and an acceleration'. Our results highlight the oncogenic role of the non-canonical base-pairing between miRNAs/mRNAs in uveal melanoma.
Project description:Uveal melanoma is a highly aggressive cancer with a strong propensity for metastasis, yet little is known about the biological mechanisms underlying this metastatic potential. We recently showed that most metastasizing uveal melanomas, which exhibit a class 2 gene expression profile, contain inactivating mutations in the tumor suppressor BAP1. The aim of this study was to investigate the role of BAP1 in uveal melanoma progression. To that end, uveal melanoma cells were studied following stable shRNA-mediated depletion of BAP1. RNA was isolated from three independent uveal melanoma cell lines each stably depleted using shRNA for either BAP1 or the control gene GFP. Two biological replicates were performed for each cell line.
Project description:Karyotyping by SNP array of primary uveal melanoma samples, uveal melanoma cell lines and normal controls The Human660WQuad v1.0 DNA Analysis Bead Chip and kit were used for high resolution molecular karyotyping of DNA isolated from snap-frozen primary uveal melanoma tissue isolated from enucleated eyes.
Project description:Uveal melanoma (UM) is a rare form of melanoma with a genetics and immunology that is different from skin melanoma. Previous studies have identified genetic driver events of early stage disease when the tumor is confined to the eye. In this study, we have characterized genomic events in UM metastases using whole-genome and RNA sequencing from thirty-two and twenty-eight patients, respectively, and profiled individual tumor infiltrating lymphocytes in a number of the metastases. We find that 91% of the patients have metastases carrying inactivating events in the tumor suppressor BAP1 and this coincided with somatic alterations in GNAQ, GNA11, CYSLTR2, PLCB4, SF3B1 and/or CDKN2A. Mutational signature analysis revealed a rare subset of tumors with prominent signs of UV damage, associated with outlier mutational burden. We study copy number variations (CNV) and find overrepresented events, some of which were not altered in matched primary eye tumors. A focused siRNA screen identified functionally significant genes of some of the segments recurrently gained. We reintroduced a functional copy of BAP1 into a patient-derived BAP1 deficient tumor cell line and found broad transcriptomic changes of genes associated with subtype distinction and prognosis in primary UM. Lastly, our analysis of the immune microenvironments of metastases revealed a presence of tumor-reactive T cells. However, a large fraction expressed the immune checkpoint receptors such as TIM-3, TIGIT and LAG3. These results provide an updated view of genomic events represented in metastatic UM and immune interactions in advanced lesions.
Project description:Genome wide DNA methylation profiling of primary uveal melanoma cells, normal uveal melanocytes, neural crest stem cells, embryonic stem cells and uveal melanoma cell lines. The Illumina Infinium 27k Human DNA methylation Beadchip Rev B was used to obtain DNA methylation profiles across approximately 27,000 CpGs in the samples. Samples included 58 primary UM, 3 NUM and NCSC controls and 2 cell lines. Bisulphite converted DNA from the 63 samples were hybridised to the Illumina Infinium 27k Human Methylation Beadchip Rev B
Project description:Despite advances in surgery and radiotherapy of uveal melanoma (UM), many patients develop distant metastases that poorly respond to therapy. Improved therapies for the metastatic disease are therefore urgently needed. Expression of the epidermal growth factor receptor (EGFR), a target of kinase inhibitors and humanized antibodies in use for several cancers, had been reported. 48 human UMs were analyzed by expression profiling. Evidence for signaling in tumors was obtained through the application of a UM-specific EGF signature. The EGFR specific kinase inhibitor, Gefitinib, and the humanized monoclonal antibody, Cetuximab, were tested for their effect on EGFR signaling. Natural killer cell mediated antibody-dependent cellular cytotoxicity (ADCC) and TNF-alpha release was analyzed for Cetuximab. EGFR appears suited as a novel molecular drug target for therapy of uveal melanoma. Gene expression profiles of 19 unique samples from uveal melanoma patients were measured.
Project description:G protein alpha q and 11 are mutated in 80% of uveal melanoma. We observed that treatment with the BRD4 inhibitor JQ1 resulted in different phenotypic responses in G-protein mutant uveal melanoma cell lines and wild type uveal melanoma cell lines. We used microarrarys to profile the gene expression changes occuring in wild type and mutant cell lines in response to treament with JQ1 Uveal melanoma cells were profiled in triplicate on Affymetrix Human Genome U133A 2.0 Array arrays per manufacturer's instructions
Project description:Gene expression in primary uveal melanoma cells and normal cell controls The HumanHT-12 v3 gene expression microarray (Illumina) was used to analyze RNA isolated from snap-frozen primary uveal melanoma tissue isolated from enucleated eyes and from normal cell controls.