[Tumor-associated fibroblasts promotes proliferation and migration of prostate cancer cells by suppressing FBXL3 via upregulating hsa-miR-18b-5p].

Objective: To explore the mechanism of tumor-associated fibroblasts (CAFs) for regulating proliferation and migration of prostate cancer (PCa) cells.

Methods: We conducted a bioinformatics analysis to identify miRNAs with high expression in PCa. The proliferation, migration and hsa-miR-18b-5p expression levels were observed in PCa cells co-cultured with CAFs. We further examined hsa-miR-18b-5p expression level in 20 pairs of PCa and adjacent tissue samples and in different PCa cell lines and normal epithelial cells using RT-qPCR. In PCa cell lines C4-2 and LNCAPNC, the effects of transfection with a hsa-miR-18b-5p inhibitor on cell proliferation, migration, invasion, drug resistance, apoptosis and cell cycle were evaluated, and the effects of has-miR-18b-5p knockdown on C4-2 cell xenograft growth and mouse survival were observed in nude mice. Dual luciferase reporter gene assay was used to validate the targeting relationship between hsa-miR-18b-5p and its target genes, whose expressions were detected in PCa cells using RT-qPCR and Western blotting.

Results: The expression of hsa-miR-18b-5p was significantly increased in the co-culture of CAFs and PCa cell lines, which exhibited significantly enhanced proliferation and migration abilities. Transfection with has-miR-18b-5p inhibitor strongly attenuated the effect of CAFs for promoting proliferation and migration of PCa cells, and in C4-2 and LNCAP cells cultured alone, inhibition of hsa-miR-18b-5p obviously suppressed cell proliferation, migration, invasion, and drug resistance. In the tumor-bearing mice, hsa-miR-18b-5p knockdown in the transplanted cells significantly inhibited xenograft growth and increased the survival time of the mice. Target gene prediction suggested that FBXL3 was a potential target of hsa-miR-18b-5p, and dual luciferase reporter gene confirmed a binding site between them. In C4-2 and LNCAP cells, hsa-miR-18b-5p knockdown resulted in significantly increased expression levels of FBXL3.

Conclusion: CAFs promotes proliferation and migration of PCa cells by up-regulating hsa-miR-18b-5p to suppress FBXL3 expression.