MicroRNA-381 suppresses proliferation and invasion of prostate cancer cells through downregulation of the androgen receptor.

Prostate cancer (PCa) is the most frequently diagnosed malignancy in men and its incidence has increased rapidly worldwide. Notably, the molecular mechanisms underlying prostate tumorigenesis have not been fully identified. The levels of microRNA (miR)-381 have been explored in numerous types of malignancy; however, the expression levels and biological function of miR-381 in PCa remain largely unknown. In the present study, reverse-transcription polymerase chain reaction was used to detect the expression levels of miR-381 in PCa cells and normal prostate epithelial cells. Subsequently, miR-381 antisense oligonucleotides and mimics were transfected into LNCaP PCa cells. Bioinformatics analysis was performed to identify the potential target genes of miR-381. Protein expression analysis, dual-luciferase reporter assay and a rescue assay were used to confirm the target of miR-381. The data suggested that the expression levels of miR-381 were significantly decreased in PCa cells compared with in normal prostatic epithelial cells. Furthermore, transfection of LNCaP cells with miR-381 mimics suppressed their proliferation, migration and invasion. In addition, bioinformatics analysis suggested that the androgen receptor (AR) was a target gene of miR-381. miR-381 suppressed the expression levels of AR by directly binding to its 3'-untranslated region. Furthermore, transfection with an AR plasmid partially attenuated miR-381-induced inhibition of cell proliferation, migration and invasion. The results of the present study suggested that miR-381 may act as a tumor suppressor in PCa by directly targeting the AR.

Anti-tumor and anti-angiogenic effects of Fucoidan on prostate cancer: possible JAK-STAT3 pathway.

BACKGROUND: Prostate cancer is the most common cancer in men in the United States. Fucoidan is a bioactive polysaccharide extracted mainly from algae. The aim of this study was to investigate anti-tumor and anti-angiogenic effects of fucoidan in both cell-based assays and mouse xenograft model, as well as to clarify possible role of JAK-STAT3 pathway in the protection. METHODS: DU-145 human prostate cancer cells were treated with 100-1000 µg/mL of fucoidan. Cell viability, proliferation, migration and tube formation were studied using MTT, EdU, Transwell and Matrigel assays, respectively. Athymic nude mice were subcutaneously injected with DU-145 cells to induce xenograft model, and treated by oral gavage with 20 mg/kg of fucoidan for 28 days. Tumor volume and weight were recorded. Vascular density in tumor tissue was determined by hemoglobin assay and endothelium biomarker analysis. Protein expression and phosphorylation of JAK and STAT3 were determined by Western blot. Activation of gene promoters was investigated by chromatin Immunoprecipitation. RESULTS: Fucoidan could dose-dependently inhibit cell viability and proliferation of DU-145 cells. Besides, fucoidan also inhibited cell migration in Transwell and tube formation in Matrigel. In animal study, 28-day treatment of fucoidan significantly hindered the tumor growth and inhibited angiogenesis, with decreased hemoglobin content and reduced mRNA expression of CD31 and CD105 in tumor tissue. Furthermore, phosphorylated JAK and STAT3 in tumor tissue were both reduced after fucoidan treatment, and promoter activation of STAT3-regulated genes, such as VEGF, Bcl-xL and Cyclin D1, was also significantly reduced after treatment. CONCLUSIONS: All these findings provided novel complementary and alternative strategies to treat prostate cancer.

Decreased expression of SLC 39A14 is associated with tumor aggressiveness and biochemical recurrence of human prostate cancer.

OBJECTIVE: Solute carrier family 39, member 14 (SLC39A14), has been identified as a potential biomarker for various cancers. However, its roles in prostate cancer (PCa) are still unclear. The aim of this study was to investigate the clinical significance of SLC39A14 in patients with PCa and its functions in malignant phenotypes of PCa cells. PATIENTS AND METHODS: Subcellular localization and expression pattern of SLC39A14 protein were examined by immunohistochemistry. Then, the associations of SLC39A14 expression with various clinicopathological features and clinical outcome of patients with PCa were statistically evaluated. Subsequently, the effects of SLC39A14 overexpression and knockdown on PCa cell proliferation and motility were, respectively, examined by Cell Counting Kit-8, transwell, and wound-healing assays. RESULTS: The immunoreactive scores of SLC39A14 protein in human PCa tissues were significantly lower than those in normal prostate tissues. Based on the Taylor dataset, SLC39A14 downregulation occurred more frequently in patients with PCa with a higher Gleason score (P<0.001), advanced clinical stage (P=0.008), presence of metastasis (P=0.009), and prostate-specific antigen failure (P=0.006). More interestingly, the survival analysis identified SLC39A14 as an independent factor for predicting the biochemical recurrence-free survival of patients with PCa (P=0.017). Functionally, the enforced expression of SLC39A14 could suppress cell proliferation, invasion, and migration of PCa cell lines in vitro, which could be reversed by the knockdown of SLC39A14. CONCLUSION: Decreased expression of SLC39A14 may lead to malignant phenotypes of PCa cells and aggressive tumor progression in patients with PCa. Importantly, SLC39A14 may function as a tumor suppressor and a biomarker for screening patients with biochemical recurrence following radical prostatectomy.