The immunohistochemical expression pattern of beta-catenin has been correlated with beta-catenin gene mutations, clinicopathological features, and disease outcome in 69 stage I and II ovarian carcinomas. beta-Catenin expression was localized in the nuclei, in addition to the cytoplasm and membrane, in 11 tumors (16%): nine endometrioid carcinomas with widespread nuclear expression and two serous carcinomas with focal nuclear expression.
These results uncover β-catenin as a critical factor in promoting ovarian cancer aggressiveness and a new mechanism linking between β-catenin and miRNA downregulation underlying this process.
To summarize, the results of this study suggest that beta-catenin mutations and MI could represent two independent pathways in endometrioid ovarian carcinomas because they occur simultaneously very infrequently (in 5% of these cases). beta-catenin mutations are always associated with a nuclear beta-catenin expression pattern, whereas cases with a replication error -plus phenotype showed no abnormal beta-catenin subcellular localization.
Both nuclear and cytoplasmic beta-catenin expressions were demonstrated in 4 of the 27 ovarian carcinomas for which tissue samples were available for examination.
Our study identifies activated Wnt signalling to be a marker for precursor lesions of OC and successfully develops a mouse model that mimics the earliest events in pathogenesis of OC by constitutively activating βcatenin.