BRCA status dictates Wnt responsiveness in epithelial ovarian cancer.

The association of BRCA1 and BRCA2 mutations with increased risk for developing epithelial ovarian cancer is well established. However, the observed clinical differences, particularly the improved therapy response and patient survival in BRCA2 mutant (BRCA2mt) patients are unexplained. Our objective is to identify molecular pathways that are differentially regulated upon the loss of BRCA1 and BRCA2 function in ovarian cancer. Transcriptomic and pathway analysis comparing BRCA1 mutant (BRCA1mt), BRCA2mt and homologous recombination wild-type (HRwt) ovarian tumors showed differential regulation of the Wnt/ß-catenin pathway. Using Wnt3A-treated BRCA1/2 wild-type (BRCAwt), BRCA1null and BRCA2null mouse ovarian cancer cells, we observed preferential activation of the canonical Wnt/ß-catenin signaling in BRCAwt ovarian cancer cells while the non-canonical Wnt/ß-catenin signaling was preferentially activated in the BRCA1null cells. Interestingly, BRCA2null mouse ovarian cancer cells, demonstrated a unique response to Wnt3A with the preferential upregulation of the Wnt signaling inhibitor, Axin2. In addition, decreased phosphorylation and enhanced stability of ß-catenin were observed in BRCA2null mouse ovarian cancer cells, which correlated with increased inhibitory phosphorylation on GSK3ß. These findings open venues for the translation of these molecular observations into modalities that can impact patient survival.

A Novel Role of Connective Tissue Growth Factor in the Regulation of the Epithelial Phenotype.

BACKGROUND: Epithelial-mesenchymal transition (EMT) is a biological process where epithelial cells lose their adhesive properties and gain invasive, metastatic, and mesenchymal properties. Maintaining the balance between the epithelial and mesenchymal stage is essential for tissue homeostasis. Many of the genes promoting mesenchymal transformation have been identified; however, our understanding of the genes responsible for maintaining the epithelial phenotype is limited. Our objective was to identify the genes responsible for maintaining the epithelial phenotype and inhibiting EMT. METHODS: RNA seq was performed using an vitro model of EMT. CTGF expression was determined via qPCR and Western blot analysis. The knockout of CTGF was completed using the CTGF sgRNA CRISPR/CAS9. The tumorigenic potential was determined using NCG mice. RESULTS: The knockout of CTGF in epithelial ovarian cancer cells leads to the acquisition of functional characteristics associated with the mesenchymal phenotype such as anoikis resistance, cytoskeleton remodeling, increased cell stiffness, and the acquisition of invasion and tumorigenic capacity. CONCLUSIONS: We identified CTGF is an important regulator of the epithelial phenotype, and its loss is associated with the early cellular modifications required for EMT. We describe a novel role for CTGF, regulating cytoskeleton and the extracellular matrix interactions necessary for the conservation of epithelial structure and function. These findings provide a new window into understanding the early stages of mesenchymal transformation.