| Ovarian cancers are highly heterogeneous and while surgery and chemotherapy is the preferred treatment, many patients are intrinsically resistant. Furthermore, all tumors that recur will become resistant. Recent evidence suggests that epigenetic deregulation might be a key factor in the onset and maintenance of chemoresistance. In my study, the epigenomes of a total of 45 ovarian samples, including 36 primary ovarian tumors and 9 normal ovarian samples, were analyzed to identify epigenetically altered genes that segregate with platinum response. This was further filtered with expression data to identify genes that were suppressed.;A tissue culture carboplatin resistance screen was developed to functionally validate this set of candidate platinum resistance genes. The screen utilized pools of shRNAs of the candidate genes to identify which of those genes when repressed allowed survival following carboplatin treatment. Our screen correctly identified 19 genes that when suppressed altered the chemoresistance of the cells in culture. Of the genes identified in the screen I further characterized one gene, docking protein 2 (DOK2), an adapter protein downstream of tyrosine kinase, to determine if we could elucidate the mechanism by which it increased resistance.;I showed that suppression of DOK2 induced chemotherapy resistance by decreasing the level of apoptosis in response to treatment. Furthermore, in cells with reduced DOK2, the level of anoikis was decreased. Anoikis represents a mechanism of possible importance in ovarian cancer where a large number of cells are floating in ascites. Functional analysis of the DOK2 genes ability to affect resistance validates this approach to finding genes involved in carboplatin resistance. Identifying methylated candidate genes involved in resistance, and the mechanisms of resistance is significant because it allows for the design of more appropriate therapy options or the introduction of combination drug treatments that might be more effective than the current standard of care. |
