Project description:Uveal melanoma (UM) is the most common primary ocular cancer in adults, which metastasizes mainly to the liver in around half of the cases. The limited potency of current treatment options for metastatic UM necessitates an urgent exploration of novel therapeutic approaches to improve patient prognosis. We conducted a large epigenetic compound library screen with the currently most well characterized, focused epigenetics library available, which consists of 932 potent, cell permeable, medically active, epigenetic-directed small molecule modulators. Our screening identified two new lead compounds, which so-far have been unappreciated for UM. Romidepsin, an HDAC inhibitor with specificity for class I HDACs, was the most efficient compound in-vitro, as well as the BET inhibitor Mivebresib, which showed minimal toxicity on normal cells. RNA sequencing and pathway analysis revealed an upregulation of PRC-associated gene targets induced by HDAC inhibition, while BET inhibition appears to act through retinoic acid related pathways. Mivebresib treatment in a metastatic uveal melanoma mouse model resulted in longer survival times and reduced metastasis to the spinal cord and brain. The results of our drug screen indicate a vulnerability for HDAC and BET inhibition for UM cells. The BET inhibitor Mivebresib may be a promising candidate for future synergistic and clinical trials.
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: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: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:Uveal melanoma is the most common intraocular malignant tumour in adults.Posterior uveal melanoma is highly likely to metastasise to the liver (89%), lungs (29%), bone (17%), skin and subcutaneous tissues (12%), and lymph nodes (11%) and has an extremely high mortality rate.Due to the unclear pathogenesis, there is still no effective treatment for uveal melanoma other than surgery.Thus, it is crucial to investigate the mechanisms of carcinogenesis and proliferation of uveal melanoma.Recent evidence suggests that biomolecular condensates,membrane-free cellular compartments formed by liquid-liquid phase separation (LLPS), plays crucial roles in physiological and tumorigenic processes.The aim of this study was to investigate the role of LLPS in the development of uveal melanoma in order to explore potential therapeutic targets for UM.
Project description:Little is known about genes that promote melanoma cell growth and proliferation. siRNAs may be used to address the role of individual genesin these processes. RNAi library screens were used in the past to gain a comprehensive overview of all genes involved in cell growth, proliferation, migration and other cellular processes. A large-scale loss-of-function screen for eight different melanoma cell lines was performed using a pooled lentiviral shRNA library (GeneNet Human 50K lentiviral shRNA Library,cat#SI206B-1, System Biosciences) to identify genes relevant for melanoma cell growth and proliferation. shRNAs that lead to cell death or reduced growth of transduced melanoma cells are negatively selected and thereby underrepresented in the final cellular shRNA pool and vice versa. The shRNAs of the shRNA library (3-5 per gene) have complementary sequences to probes on the custom Affymetrix microarray HG-U133Plus2 and were analysed using this array. Well-known melanoma cell lines SK-Mel-103, A375, SK-Mel-147, SK-Mel-19, SK-Mel-28, SK-Mel-29, SK-Mel-5, WM3523cln6 were transduced with the lentiviral shRNA library and grown for 10 days under puromycin selection (day 10), control cells of respective cell lines were transduced and frozen immediately after transduction and genomic integration of shRNAs (day 0). Totel DNA was extracted and genomically integrated shRNAs were hybridized to Affymetrix microarrays (HG-U133Plus2.0 array).
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.
Project description:G protein alpha q and 11 are mutated in 90% of uveal melanoma and they activate the MAPK pathway. Using expression microarray analysis, we identified a unique MEK dependent transcriptional signature with genes that are involved in proliferation and tumor cell invasion. Uveal melanoma cells were profiled on Illumina Human HT-12 arrays per manufacturer's instructions