Vascular endothelial growth factor receptor 3 (VEGFR3) is expressed in cancer cell lines and exerts a critical role in cancer progression. However, the signaling pathways of VEGFR3 in ovarian cancer cell proliferation remain unclear. This study aimed to demonstrate the signaling pathways of VEGFR3 through the upregulated expression of miR-1236 in ovarian cancer cells. We found that the messenger RNA and protein of VEGFR3 were expressed in the ovarian cancer cell lines, but downregulated after microRNA-1236 (miR-1236) transfection. The inhibition of VEGFR3, using miR-1236, significantly reduced cell proliferation, clonogenic survival, migration, and invasion ability in SKOV3 and OVCAR3 cells (p < 0.01). The flow cytometry results indicated that the rate of apoptotic cells in SKOV3 (38.65%) and OVCAR3 (41.95%) cells increased following VEGFR3 inhibition. Moreover, VEGFR3 stimulation (using a specific ligand, VEGF-CS) significantly increased extracellular signal-regulated kinase 1/2 (ERK1/2) and protein kinase B (AKT) phosphorylation (p < 0.01), whereas VEGFR3 suppression reduced p-ERK1/2 (67.94% in SKOV3 and 93.52% in OVCAR3) and p-AKT (59.56% in SKOV3 and 78.73% in OVCAR3) compared to the VEGF-CS treated group. This finding demonstrated that miR-1236 may act as an endogenous regulator of ERK1/2 and AKT signaling by blocking the upstream regulator of VEGFR3. Overall, we demonstrated the important role of the miR-1236/VEGFR3 axis in ovarian cancer cell proliferation by regulating the ERK1/2 and AKT signaling that might be an effective strategy against ovarian cancer.

Background Tumor lymphangiogenesis is a critical component in the progression of cancers and specific microRNAs have been reported to be implicated in this process. Recent studies revealed the involvement of miR‐1236 in lymphangiogenic signaling by targeting vascular endothelial growth factor receptor 3 (VEGFR3). However, the prognostic importance of miR‐1236 and its clinical relevance for lymphangiogenesis in ovarian cancer (OC) remains unclear. Methods The study included 52 ovarian tumors and 28 normal ovarian tissues. Quantitative real‐time PCR was utilized to analyze the VEGFR3, VEGF‐C, LYVE‐1 and PROX1 mRNA expression as well as miR‐1236. VEGFR3 protein expression was measured by immunohistochemistry staining. Immunohistochemistry for the podoplanin marker (D2‐40) was performed to measure lymphatic vessel density (LVD). In addition, diagnostic evaluation based on the receiver‐operating characteristic (ROC) curve was performed. The influence of miR‐1236 on overall survival was evaluated by Kaplan–Meier method. Results Here, we show that miR‐1236 expression was significantly decreased in ovarian tumors compared with control tissues (p < 0.001) and correlated with advanced clinical stage, lymph node metastasis, distant metastasis and patient survival (All P < 0.05). Moreover, in ovarian tumors, LVD as well as the gene expression of VEGFR3, VEGF‐C and LYVE‐1, but not PROX1, were found to be remarkably higher compared with control tissues. We also detected a more robust positive staining for VEGFR3 in OC tissues than in control tissues. Furthermore, our results demonstrated an inverse association of miR‐1236 expression with LVD, VEGFR3, LYVE‐1 and PROX1 expression in OC tissues. The ROC curve analysis indicated that miR‐1236 expression has the potential to be used as a diagnostic and prognostic biomarker in OC. Survival analysis further verified a lowered overall survival rate in patients with low miR‐1236 expression than in those with high expression. Conclusions Our results provide evidence for the translational involvement of miR‐1236 in the lymphangiogenesis of OC by regulating lymphangiogenesis‐related factors and support the clinical importance of miR‐1236 as a new diagnostic and prognostic biomarker for OC.