Dual Fluorescence Isogenic Synthetic Lethal Kinase Screen and High-Content Secondary Screening for MUC16/CA125-Selective Agents

Significant strides have been made in the development of precision therapeutics for cancer. Aberrantly expressed glycoproteins represent a potential avenue for therapeutic development. The MUC16/CA125 glycoprotein serves as a biomarker of disease and a driver of malignant transformation in epithelial ovarian cancer. Previously, we demonstrated a proof-of-principle approach to selectively targeting MUC16(+) cells. In this report, we performed a synthetic lethal kinase screen using a human kinome RNAi library and identified key pathways preferentially targetable in MUC16 + cells using isogenic dual-fluorescence ovarian cancer cell lines. Using a separate approach, we performed high-content small-molecule screening of six different libraries of 356,982 compounds for MUC16/CA125-selective agents and identified lead candidates that showed preferential cytotoxicity in MUC16(+) cells. Compounds with differential activity were selected and tested in various other ovarian cell lines or isogenic pairs to identify lead compounds for structure-activity relationship (SAR) selection. Lead siRNA and small-molecule inhibitor candidates preferentially inhibited invasion of MUC16(+) cells in vitro and in vivo, and we show that this is due to decreased activation of MAPK, and non-receptor tyrosine kinases. Taken together, we present a comprehensive screening approach to the development of a novel class of MUC16-selective targeted therapeutics and identify candidates suitable for further clinical development.