MicroRNA-146b acts as a potential tumor suppressor in human prostate cancer.

Purpose: MicroRNAs (miRs) act as either tumor suppressors or oncogenes and are frequently deregulated in cancers. Although downregulation of miR-146b has been reported in various cancers, its role in prostate cancer is totally unknown.

Methods: The miR-146b expression in 18 human prostate cancer lines with case-matched adjacent normal tissues was measured by quantitative RT-PCR. Furthermore, the expression levels of miR-146b in normal prostate and prostate cancer cell lines were assessed. Cell proliferation, apoptosis, migration and invasion assays were performed in overexpressing or knockdown miR-146b cells.

Results: miR-146b expression was significantly reduced in all prostate tumor tissues. Furthermore, miR-146b was significantly decreased in prostate cancer cells as compared to normal prostate cells. Loss-of-function and gain-of-function showed that miR-146b induced apoptosis and suppressed cell proliferation, migration and invasion of the prostate cancer cell lines.

Conclusion: Our results demonstrated that miR-146b expression is downregulated in prostate tumor tissues and is a potential tumor suppressor miR, suggesting that miR-146b might be a potential clinical marker and therapeutic target for prevention and treatment of prostate cancer.