Introduction: Germline mutations in BRCA1 predispose individuals to high-grade serous tubal-ovarian cancer (HGSTOC), which originates from fallopian tube epithelial (FTE) cells. Repetitive exposure of these cells to follicular fluid during ovulation is thought to contribute to the development of this cancer. We have shown that BRCA1 deficiency in non-malignant FTE cells increases proinflammatory NFκB signaling, and that exposure to periovulatory follicular fluid further increases key proinflammatory interferon-stimulated genes such as ISG15. In the present study, we compared cytokine levels in follicular fluid derived from BRCA1 mutation carriers to that of non-mutation carriers and determined the effect of key differentially-expressed proteins on FTE cells.

Methods: Levels of 92 inflammatory proteins were measured using an antibody array in periovulatory follicular fluid collected from 59 patients (13 patients with BRCA1 mutations, 31 non-mutation carriers, and 15 with mutations other susceptibility genes). The impact of key identified proteins on proinflammatory signaling in an immortalized FTE cell line was determined by real-time qPCR and western blotting.

Results: Principal component analysis indicated that samples from BRCA1 mutation carriers clustered separately from other samples. RANKL and CSF-1 were among 8 proteins found to be increased in BRCA1 mutation carriers, and independently increased cell proliferation and NFκB activation. RANKL increased levels of downstream targets of NFκB and type I interferons. The increase in interferon downstream targets was blocked by NFκB inhibition.

Conclusion: RANKL and CSF-1 are increased in follicular fluid from BRCA1 mutation carriers and act upon FTE cells to increase proinflammatory signaling, which has been implicated in tumor initiation. This study implicates RANKL and CSF-1 as potential candidate targets for preventative strategies to mitigate HGSTOC risk in BRCA1 mutation carriers.