Ectopic repression of receptor tyrosine kinase-like orphan receptor 2 inhibits malignant transformation of ovarian cancer cells by reversing epithelial-mesenchymal transition.

ABSTRACT

Receptor tyrosine kinase-like orphan receptor 2 is an enzyme-linked receptor which specifically modulates WNT5A signaling and plays an important role in tumorigenesis, invasion, and metastasis; however, the precise role of receptor tyrosine kinase-like orphan receptor 2 in cancer is controversial. The purpose of this study was to investigate the expression and role of receptor tyrosine kinase-like orphan receptor 2 in ovarian carcinoma and clarify the biological functions and interactions of receptor tyrosine kinase-like orphan receptor 2 with non-canonical Wnt pathways in ovarian cancer. The result of the human ovary tissue microarray revealed that the receptor tyrosine kinase-like orphan receptor 2-positive rate increased in malignant epithelial ovarian cancers and was extremely higher in the metastatic tumor tissues, which was also higher than that in the malignant ovarian tumor tissues. In addition, high expression of receptor tyrosine kinase-like orphan receptor 2 was closely related with ovarian cancer grading. The expression of receptor tyrosine kinase-like orphan receptor 2 protein was higher in SKOV3 and A2780 cells than OVCAR3 and 3AO cells. Knockdown of receptor tyrosine kinase-like orphan receptor 2 inhibited ovarian cancer cell proliferation, migration, invasion, and induced morphologic as well as digestive state alterations in stably transfected SKOV3 cells. Detailed study further revealed that silencing of receptor tyrosine kinase-like orphan receptor 2 reversed the epithelial-mesenchymal transition and inhibited non-canonical Wnt signaling. Our findings suggest that receptor tyrosine kinase-like orphan receptor 2 may be an important regulator of epithelial-mesenchymal transition, primarily regulated the non-canonical Wnt signaling pathway in ovarian cancer cells, and may display a promising therapeutic target for ovarian cancer.