Introduction
Mucinous Ovarian Carcinoma (MOC) is a rare form of epithelial ovarian cancer that is histologically distinct from other subtypes. Prognosis is poor when diagnosed at late stage, primarily due to resistance to the platinum-based therapies used successfully to treat other ovarian cancers. Thus, novel therapeutic options are desperately needed that address the full spectrum of molecular heterogeneity seen in MOC tumours. Our group has previously performed extensive bioinformatic analysis on our large mucinous tumour mutation and expression dataset to produce a ranked list of novel putative candidate genes that could be clinically targetable. We are now undertaking in vitro validation of these candidates and potential matched compounds in MOC pre-clinical models.
Methods
Dharmafect SMARTpool siRNA knockdown screens were performed for 15 gene targets across three MOC cell lines (JHOM-1, RMUG-S and MCAS). Successful knockdown was confirmed by RT-qPCR and viability assessed by high content imaging. Commercially available small molecule inhibitors targeting the top hits identified in siRNA screening were then tested in a 10uM 10-point dilution dose-response screen in the same cell lines, as well as two normal fibroblast cell lines (BJ and HFF-1) for comparison.
Results
siRNA screens resulted in statistically significant reductions in cellular viability for 12/15 genes, including the top four hits KIF18A, CDK1, CCNA2 and CDC20. Small molecule inhibitor screens are currently on-going, with preliminary data for one candidate gene, CDK1, presented here. Specific small molecule inhibitor Ro-3306 targeting CDK1 was shown to significantly reduce cellular viability in MOC cell lines by 50% or more at a dose concentration that resulted in minimal loss of viability for ’healthy control’ fibroblast cells.
Conclusions
Our siRNA knockdown data validates the output of our bioinformatic analysis pipelines in generating a list of candidate genes that were important for MOC cell viability, and supports the role of these genes as potential therapeutic targets. Demonstrated dose responses to a specific small molecule inhibitor of CDK1, Ro-3306 reveal significant reductions in cellular viability of MOC cells. Additionally, a therapeutic window was evident between MOC and healthy cells, suggesting this inhibitor may be able to be administered as a therapeutic that can successfully kill cancer cells while producing minimal side effects. These results will be used to inform future clinical trials to expand treatment options and ultimately improve MOC patient outcomes.