Abstract B099: A common WNT4 polymorphism drives gynecologic cancer phenotypes and health disparities

Abstract Introduction: Beyond BRCA1/2 mutations, there is a limited understanding of gynecologic cancer etiology and risk. An underexplored risk factor is Wnt ligand WNT4, central to ovarian and uterine organogenesis. A single nucleotide polymorphism (SNP) at a key WNT4 regulatory site (rs3820282) is associated with 10-25% increased risk for gynecologic pathologies, including ovarian cancer (OvCa), but the mechanism is unknown. Importantly, rs3820282 variant allele frequency (VAF) is ~0% in African populations, ~15% in Caucasians, 20-40% in Latinx populations, and 45-55% in Asian populations, paralleling increased incidence of aggressive OvCa subtypes in Asian populations. We hypothesize the rs3820282 variant drives OvCa health disparities by aberrant activation of WNT4, mediating distinct cancer etiology, therapy resistance, and poor patient outcomes. Methods: To address our hypothesis, we employed global untargeted metabolomics, SNP genotyping, WNT4 overexpression, WNT4 siRNA-mediated knockdown, cell viability assays, and Reverse Phase Protein Array (RPPA). We assessed both OvCa cell lines, murine syngeneic tumor models (ID8 Tp53-/- and ID8 Tp53-/-, Brca2-/-), formalin-fixed pre- and post-chemotherapy primary human tumors (18 pairs), and snap frozen primary gynecologic tumors (n=103). Statistical tests performed in Prism GraphPad and include multi-comparison ANOVA, paired t-test, and unpaired t-test. Results: WNT4-overexpression in the ID8 model drove cisplatin resistance in vitro, and resistance and metastatic outgrowth in vivo (n=5 mice/model; post-treatment metastatic nodule mass: control = 5±8mg; WNT4 = 42±18mg; p=0. 0078). In paired OvCa tumors pre-/post-treatment with chemotherapy (n=18 pairs), we found WNT4 in the top 10 most-strongly induced genes post-chemotherapy (4-fold, p =0. 0005). In OvCa cell lines, WNT4 siRNA only suppressed growth in WNT4 variant lines (60% reduced growth in n=4 variants, vs n=4 wild-type p=0. 010). WNT4 siRNA dysregulated mitochondrial function only in WNT4 variant lines, linking the rs3820282 variant to WNT4-driven metabolic remodeling. RPPA analysis of gynecologic tumors (52% het. +variant) ; note this is one of the largest proteomic studies enriched for patient diversity (47% from non-White). We identified differential metabolic signaling; AMPK activation was increased in variant tumors (AMPKα1-pT172 + AMPKα2-pS345; p=0. 031) along with AMPK signaling targets. Conversely, glucose metabolism proteins were increased in wild-type tumors, and inversely correlated with AMPK activation (Spearman ρ=-0. 34, p=0. 0005), suggesting that WNT4 genotype underpins AMPK activation and metabolic remodeling. Conclusions: The rs3820282 variant permits aberrant activation of WNT4, driving AMPK-mediated metabolic remodeling and therapy resistance. As the rs3820282 VAF differs widely across populations, WNT4 polymorphism may drive disparities in gynecologic cancer risk and outcomes. Understanding WNT4 signaling and regulation via the rs3820282 variant can lead to precision treatments exploiting cellular dependencies on WNT4 signaling. Citation Format: Benjamin G. Bitler, Madeleine T. Shackleford, Lindsey Trevino, Linda S. Cook, Matthew J. Sikora. A common WNT4 polymorphism drives gynecologic cancer phenotypes and health disparities abstract. In: Proceedings of the AACR Special Conference on Ovarian Cancer; 2023 Oct 5-7; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84 (5 Suppl₂): Abstract nr B099.