Project description:Analysis of DNA from fixed tissues specimens of 58 primary uveal melanomas, with known clinical outcome, to determine gene copy number variations that were associated with survival. Abstract: Uveal melanomas can be stratified into subgroups with high or low risk of metastatic death, according to the presence of gross chromosomal abnormalities. Where a monosomy 3 uveal melanoma is detected, patient survival at three years is reduced to 50%. However, approximately 5% of patients with a disomy 3 tumour ultimately develop metastasis, and a further 5% of monosomy 3 uveal melanoma patients’ exhibit disease-free survival for more than five years. Despite extensive knowledge of the chromosomal abnormalities occurring in uveal melanoma, the genes driving metastasis are not well defined. Gene copy number variations occurring in a well-characterised cohort of 58 formalin-fixed, paraffin-embedded uveal melanoma samples were identified using the Affymetrix SNP 6.0 whole genome microarray. Four genetic sub-groups of primary uveal melanoma were represented in the patient cohort: 1) disomy 3 with long-term survival; 2) metastasizing disomy 3; 3) metastasizing monosomy 3; and 4) monosomy 3 with long-term survival. Cox regression and Kaplan-Meier survival analysis identified three genes that were associated with differences in patient survival. Patients with an amplification of CNKSR3 (6q) or RIPK1 (6p) demonstrated longer survival than those with gene deletions or no copy number change (log rank, p=0.022 and p<0.001, respectively). Conversely, those patients with an amplification of PENK (8q) showed reduced survival (log rank p<0.001). CNKSR3, RIPK1 and PENK are novel candidate metastasis regulatory genes in uveal melanoma. This is the first report of amplification of a specific gene on 6p that is associated with improved uveal melanoma patient survival and suggests that the development of uveal melanomas with a propensity to metastasise may be limited by genes on 6p. 58 samples in total. Ten disomy 3 with long-term survival. Fifteen disomy 3 with metastasising. Seventeen monosomy 3 with long-term survival. Sixteen monosomy 3 metastasising.
Project description:Analysis of DNA from fixed tissues specimens of 58 primary uveal melanomas, with known clinical outcome, to determine gene copy number variations that were associated with survival. Abstract: Uveal melanomas can be stratified into subgroups with high or low risk of metastatic death, according to the presence of gross chromosomal abnormalities. Where a monosomy 3 uveal melanoma is detected, patient survival at three years is reduced to 50%. However, approximately 5% of patients with a disomy 3 tumour ultimately develop metastasis, and a further 5% of monosomy 3 uveal melanoma patients’ exhibit disease-free survival for more than five years. Despite extensive knowledge of the chromosomal abnormalities occurring in uveal melanoma, the genes driving metastasis are not well defined. Gene copy number variations occurring in a well-characterised cohort of 58 formalin-fixed, paraffin-embedded uveal melanoma samples were identified using the Affymetrix SNP 6.0 whole genome microarray. Four genetic sub-groups of primary uveal melanoma were represented in the patient cohort: 1) disomy 3 with long-term survival; 2) metastasizing disomy 3; 3) metastasizing monosomy 3; and 4) monosomy 3 with long-term survival. Cox regression and Kaplan-Meier survival analysis identified three genes that were associated with differences in patient survival. Patients with an amplification of CNKSR3 (6q) or RIPK1 (6p) demonstrated longer survival than those with gene deletions or no copy number change (log rank, p=0.022 and p<0.001, respectively). Conversely, those patients with an amplification of PENK (8q) showed reduced survival (log rank p<0.001). CNKSR3, RIPK1 and PENK are novel candidate metastasis regulatory genes in uveal melanoma. This is the first report of amplification of a specific gene on 6p that is associated with improved uveal melanoma patient survival and suggests that the development of uveal melanomas with a propensity to metastasise may be limited by genes on 6p.
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:Primary uveal melanomas show multiple chromosomal aberrations. To identify genome variation in six human primary uveal melanomas, genome wide copy number variation (CNV) analyses were carried out in human primary uveal melanoma samples using array comparative genome hybridization.
Project description:<p>Uveal melanoma is a rare form of melanoma that occurs in the eye and has no effective treatment once metastatic. To further characterize the genomic events driving uveal melanoma, whole exome sequencing was performed on 61 primary tumors derived from enucleations, 3 liver metasases, and paired normal DNA. Recurrent somatic genetic alterations including point mutations, small insertions and deletions, as well as copy number variations were identified. In addition, RNA sequencing of uveal melanoma cell lines expressing shRNAs was performed from total RNA as well as polysome-associated mRNA in order to identify transcripts regulated by EIF1AX at the level of translation.</p>
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.