miR-145-5p mimic inhibits bone metastasis of prostate cancer via the regulation of epithelial mesenchymal transition

Background. The bone is the most common site of distant metastasis in prostate cancer. However, treatments for the bone metastasis of prostate cancer remain unsatisfactory. MicroRNAs (miRNAs) are small noncoding RNAs that play a variety of critical roles in tumor development and progression. Studies have confirmed that miRNA mimics could regulate the response to therapy in many cancers. Methods. In this study, a set of forty-four miRNAs were reduced in prostate cancer patients with bone metastases by high-throughput sequencing analysis. Wound healing and transwell assays and western blotting analysis were used to explore the role of miRNA mimic in prostate cancer bone metastasis. Results. These mimics of down-regulated miRNAs may be able to cure prostate cancer bone metastasis, including hsa-miR-221-3p, hsa-miR-222-3p, hsa-miR-133a-3p, hsa-miR-222-5p, hsa-miR-204-3p, hsa-miR-145-5p, hsa-miR-3681-5p, hsa-miR-184, hsa-miR-144-3p, hsa-miR-204-5p, and hsa-miR-221-5p. To further investigate the role of these miRNA mimics on prostate cancer bone metastasis, miR-145-5p was randomly selected for validation. Bioinformatics analysis showed that miR-145-5p target genes significantly affected TGF-beta signaling pathway. Wound healing and transwell assays and western blotting analysis revealed that miR-145-5p mimic inhibited proliferation, migration and invasion. Importantly, miR-145-5p mimic increased the expression of E-cadherin and reduced the expression of matrix metalloproteinase 2 and 9. These results revealed that miR-145-5p mimic mediated epithelial mesenchymal transition. Meanwhile, miR-145-5p mimic enhanced the level of caspase 9, which is an important promoter of apoptosis. These results indicate that miR-145-5p mimic could inhibit the progress of prostate cancer bone metastasis via regulation of epithelial mesenchymal transition. In addition, miR-145-5p mimic could induce the apoptosis of prostate cancer cells with bone metastases. In summary, the miR-145-5p mimic is expected to become a novel strategy for the treatment of tumor metastasis.