Worldwide, over 225 million women have an unmet need for modern contraception. Unmet need accounts for 74 million unplanned pregnancies and 70,000 maternal deaths yearly. Adverse side-effects of hormonal contraceptives is the most frequent reason for discontinued or non-use. There is an acute need for new contraceptives that do not alter normal endocrine profile and offer wider contraceptive choices.
Selectively blocking ovulation without affecting ovarian hormones is an ideal approach to contraceptive development that minimises/ eliminates side effects.
We developed a high-throughput approach for screening drug libraries for potential ovulation blocking capacity using automated assessment of cumulus oocyte complex (COC) adhesion to extracellular matrix in vitro. Two small molecules CRS-006 and LCRF-0006, N-cadherin antagonists, were identified as “hits” that potently and dose dependently inhibited COC adhesion to fibronectin. During COC in vitro maturation, both N-cadherin antagonists severely inhibited COC expansion and oocyte meiotic resumption with concomitant loss of b-catenin and E-cadherin at the oocyte cell membrane. Profiling of the transcriptional response to N-cadherin inhibition identified targets of b-catenin and YAP1 pathways were dysregulated indicating that in COCs these pathways are dependent on N-cadherin action. In vivo, treatment with N-Cadherin antagonist CRS-066 significantly reduced ovulations (11 vs 26 oocytes/ovary; p-5.8*10^-6) compared to controls in mice. Ovarian histology and immunofluorescence revealed structural dysgenesis of follicles, with disorganised granulosa and cumulus cell layers. In particular, connections between cumulus corona radiata cells and the oocyte was disrupted. This was not due to LH-pathway downregulation as Lhcgr and downstream signaling remained intact. Again, the transcriptome analysis indicated that mechanistically, N-cadherin antagonism caused dysregulation of Hippo/YAP and b-catenin mechanosensitive pathways in vivo. Overall, this study establishes a robust proof-of-concept to develop a unique high-throughput model for screening drugs for contraceptive potential; and demonstrates a critical role of N-cadherin in oocyte-cumulus signaling during follicle development and ovulation.