Exome_sequencing_of_NRAS_driven_zebrafish_melanomas

Activating mutations in BRAF and NRAS genes are among the most frequent genetic events in human melanoma. BRAF mutations are present in over 60% of melanoma cases, while NRAS mutations (predominantly NRASQ61K or NRASQ61R ) have been identified in 33% of the primary and 26% of the metastatic disease. Mutations present in BRAF and NRAS are often mutually exclusive and alone are not sufficient to cause tumorigenesis. Transgenic zebrafish expressing mutant forms of human BRAF and NRAS develop tumours only in the presence of an inactivated tumour suppressor such as p53, arguing for the requirement for additional genetic events in melanoma development. We are interested in determining the specific genetic events underlying melanoma progression. We are currently investigating the pattern of somatic mutations in the exomes of zebrafish melanomas in which BRAFV600E is the initiating event (SeqComm I0009). For a broader and more comprehensive representation of melanoma , we wish to extend this study to include instances of zebrafish melanoma developed from oncogenic NRAS. We have obtained tumour samples from an NRASQ61; p53-/- transgenic zebrafish at different stages of the disease, of particular interest: abnormal nevi in addition to melanoma from the same fish. Our proposal is to sequence the exomes of these additional samples with following aims: 1) Detailed comparison of somatic mutations between the NRAS and BRAF driven melanomas in engineered zebrafish models. 2) Detailed comparison of genetic events at different stages of the NRAS-driven disease. With the recent therapeutic advances in melanoma therapy through targeted inhibition of BRAFV600E (Flaherty et al. 2010), investigating the genetics of the NRAS-driven subset of melanomas will of equal clinical importance for furthering our understanding melanoma progression and improving treatment.