Silencing ROR1 and ROR2 inhibits invasion and adhesion in an organotypic model of ovarian cancer metastasis

OBJECTIVE Elevated expression of the ROR1 and ROR2 Wnt receptors has been noted in both the tumour and stromal compartments of ovarian cancer patient tissue samples. In vitro studies have suggested these receptors play a role in ovarian cancer metastasis. However, these previous studies have utilised simple 2D in vitro models to investigate cancer cell growth and migration, which does not allow investigation of stromal involvement in Wnt driven metastasis. AIM To investigate targeting ROR1 and ROR2 using a primary co-culture 3D model of epithelial ovarian cancer dissemination to the omentum. METHODS Primary fibroblasts (NOF) and mesothelial (HPMC) cells were isolated from fresh samples of omentum collected from women with benign or non-metastatic conditions and cultured with collagen to produce a organotypic 3D model. Stable shRNA knockdown of ROR1, ROR2 and double ROR1/ROR2 in OVCAR4 cells were plated onto the 3D model to measure adhesion, or using a transwell to measure invasion. Gene expression changes in primary cells upon OVCAR4 interaction was evaluated using indirect transwell co-culture. RESULTS Double knockdown of ROR1 and ROR2 strongly inhibited cell adhesion (p<0.05) and invasion (P<0.05) to the omentum model. ROR2 was up regulated in primary fibroblasts when cultured with OVCAR4 (P=0.05) and ectopic overexpression of ROR2 in NOFs inhibited cell proliferation (P<0.01) but increased cell migration. CONCLUSION The combination of ROR1 and ROR2 signalling influences ovarian cancer dissemination to the omentum, however ROR2 may also play a role in stromal activation during metastasis. Therefore, targeting both ROR1 and ROR2 may be a powerful approach to treating ovarian cancer.