The Role of CBFß in Ovarian Cancer

Ovarian cancer is the second most common and the deadliest gynecologic malignancy. Approximately 60% of women with ovarian cancer present with metastatic disease and the 5-year survival for these women is 30%. Standard treatments for ovarian cancer have not been modified in the last few decades, therefore novel treatment strategies and molecular targets are urgently needed for this disease. The RUNX family of transcription factors includes RUNX1, RUNX2 and RUNX3, which bind to DNA, and their shared binding partner CBFβ. These proteins are overexpressed in epithelial ovarian cancers. Prior studies have shown that genetic inhibition of RUNX1, RUNX2, RUNX3 and CBFβ in ovarian cancer cell lines reduces proliferation and decreases anchorage-independent growth in soft agar; however, the mechanisms underlying these effects remain elusive, and genetic inhibition is not an applicable strategy for patient care. Recently, inhibitors of the CBFβ/RUNX protein-protein interaction have been developed. These compounds bind to CBFβ and block its ability to bind RUNX proteins. In this dissertation, we used these novel tool compounds and genetic reduction of CBFβ to study both the effects of CBFβ inhibition in ovarian cancer and the downstream mechanisms underlying these effects. CBFβ inhibitor treatment reduces the proliferation of ovarian cancer cell lines and causes an S-phase delay. CBFβ inhibitor treatment also impairs wound healing and anchorage-independent growth. These phenotypes are driven by a small set of gene expression changes, including decreases in INBHA and MMP1. Reduction of INHBA or MMP1 recapitulates the effects of CBFβ inhibitor treatment. Knockdown of CBFβ results in a large number of gene expression changes. Additionally, CRISPR, but not siRNA- mediated, reduction of CBFβ reduces ovarian cancer cell proliferation and migration, andnalters the expression of some genes reduced by inhibitor treatment. Lastly, cells lacking CBFβ retain their sensitivity to CBFβ inhibitors. In sum, this dissertation establishes that CBFβ functions as an oncogene in ovarian cancer by altering a gene expression network and that CBFβ/RUNX inhibition represents a viable treatment strategy worthy of additional study.