Fabian R. Villagomez

WNT4 Regulates Cellular Metabolism via Intracellular Activity at the Mitochondria in Breast and Gynecologic Cancers

Abstract Wnt ligand WNT4 is critical in female reproductive tissue development, with WNT4 dysregulation linked to related pathologies including breast cancer (invasive lobular carcinoma, ILC) and gynecologic cancers. WNT4 signaling in these contexts is distinct from canonical Wnt signaling yet inadequately understood. We previously identified atypical intracellular activity of WNT4 (independent of Wnt secretion) regulating mitochondrial function, and herein examine intracellular functions of WNT4. We further examine how convergent mechanisms of WNT4 dysregulation impact cancer metabolism. In ILC, WNT4 is co-opted by estrogen receptor α (ER) via genomic binding in WNT4 intron 1, while in gynecologic cancers, a common genetic polymorphism (rs3820282) at this ER binding site alters WNT4 regulation. Using proximity biotinylation (BioID), we show canonical Wnt ligand WNT3A is trafficked for secretion, but WNT4 is localized to the cytosol and mitochondria. We identified DHRS2, mTOR, and STAT1 as putative WNT4 cytosolic/mitochondrial signaling partners. Whole metabolite profiling, and integrated transcriptomic data, support that WNT4 mediates metabolic reprogramming via fatty acid and amino acid metabolism. Furthermore, ovarian cancer cell lines with rs3820282 variant genotype are WNT4 dependent and have active WNT4 metabolic signaling. In protein array analyses of a cohort of 103 human gynecologic tumors enriched for patient diversity, germline rs3820282 genotype is associated with metabolic remodeling. Variant genotype tumors show increased AMPK activation and downstream signaling, with the highest AMPK signaling activity in variant genotype tumors from non-White patients. Taken together, atypical intracellular WNT4 signaling, in part via genetic dysregulation, regulates the distinct metabolic phenotypes of ILC and gynecologic cancers. Significance: WNT4 regulates breast and gynecologic cancer metabolism via a previously unappreciated intracellular signaling mechanism at the mitochondria, with WNT4 mediating metabolic remodeling. Understanding WNT4 dysregulation by estrogen and genetic polymorphism offers new opportunities for defining tumor biology, precision therapeutics, and personalized cancer risk assessment.

Claudin-4 Stabilizes the Genome via Nuclear and Cell-Cycle Remodeling to Support Ovarian Cancer Cell Survival

Abstract Alterations in the interplay between the nucleus and the cell cycle during cancer development lead to a state of genomic instability, often accompanied by observable morphologic aberrations. Tumor cells can regulate these aberrations to evade cell death, either by preventing or eliminating genomic instability. In epithelial ovarian cancer, overexpression of claudin-4 significantly contributes to therapy resistance through mechanisms associated with genomic instability regulation. However, the molecular mechanisms underlying claudin-4 overexpression in epithelial ovarian cancer remain poorly understood. In this study, we modified claudin-4 expression and employed a unique claudin mimic peptide to investigate claudin-4’s function. Our findings show that claudin-4 supports ovarian cancer cell survival by stabilizing the genome through nuclear and cell-cycle remodeling. Specifically, claudin-4 induced nuclear constriction by excluding lamin B1 and promoting perinuclear F-actin accumulation, thereby altering nuclear structure and dynamics. Similarly, cell-cycle modifications due to claudin-4 overexpression resulted in fewer cells entering the S-phase and reduced genomic instability in tumors. Importantly, disrupting claudin-4’s biological effects using claudin mimic peptide and forskolin increased the efficacy of PARP inhibitor treatment, correlating with alterations in the oxidative stress response. Our data indicate that claudin-4 protects tumor genome integrity by modulating the crosstalk between the nucleus and the cell cycle, leading to resistance to genomic instability formation and the effects of genomic instability–inducing agents. Significance: High-grade serous ovarian carcinoma is marked by chromosomal instability, which can serve to promote disease progression and allow cancer to evade therapeutic insults. The report highlights the role of claudin-4 in regulating genomic instability and proposes a novel therapeutic approach to exploit claudin-4–mediated regulation.