ROR1 and ROR2 play distinct and opposing roles in endometrial cancer.

Objective: In recent years, the Wnt signalling pathway and the ROR1 and ROR2 receptors have been implicated in a range of gynecological cancers. These receptors have been described as prospective therapeutic targets, and this study investigated such potential in an endometrial cancer context.

Method: Immunohistochemistry for ROR1 and ROR2 was performed in a patient cohort, and expression was correlated with clinicopathological parameters including type, stage, grade, myometrial invasion, lymphovascular involvement, patient age and survival. The functional role of these receptors in endometrial cancer was investigated via siRNA knockdown of ROR1 and ROR2 in three cell line models (KLE, RL95-2 and MFE-319). Effects on proliferation, adhesion, migration and invasion were measured.

Results: High ROR1 expression in patient samples correlated with worse overall survival (p = 0.0169) while high ROR2 expression correlated with better overall survival (p = 0.06). ROR1 knockdown in KLE cells significantly decreased proliferation (p = 0.047) and reduced migration and invasion. ROR2 knockdown in RL95-2 cells increased cell migration and invasion (p = 0.011). Double ROR1 and ROR2 knockdown in MFE-319 cells decreased adhesion and significantly increased cell migration (P = 0.008) and invasion (p < 0.001).

Conclusion: ROR1 and ROR2 play distinct roles in endometrial cancer. ROR1 may promote tumor progression, similar to its role in ovarian cancer, while ROR2 may act as a tumor suppressor in endometrioid endometrial cancer, similar to its role in colorectal cancer. With several ROR-targeting therapies currently in development and phase I clinical trials for other tumor types, this study supports the potential of these receptors as therapeutic targets for women with endometrial cancer.