ABSTRACT
Transforming growth factor-β1 (TGF-β1) acts as a tumor promoter in advanced prostate cancer (PCa). We speculated that microRNAs (miRNAs) that are inhibited by TGF-β1 might exert anti-tumor effects. To assess this, we identified several miRNAs downregulated by TGF-β1 in PCa cell lines and selected miR-3691-3p for detailed analysis as a candidate anti-oncogene miRNA. miR-3691-3p was expressed at significantly lower levels in human PCa tissue compared with paired benign prostatic hyperplasia tissue, and its expression level correlated inversely with aggressive clinical pathological features. Overexpression of miR-3691-3p in PCa cell lines inhibited proliferation, migration, and invasion, and promoted apoptosis. The miR-3691-3p target genes E2F transcription factor 3 (E2F3) and PR domain containing 1, with ZNF domain (PRDM1) were upregulated in miR-3691-3p-overexpressing PCa cells, and silencing of E2F3 or PRDM1 suppressed PCa cell proliferation, migration, and invasion. Treatment of mice bearing PCa xenografts with a miR-3691-3p agomir inhibited tumor growth and promoted tumor cell apoptosis. Consistent with the negative regulation of E2F3 and PRDM1 by miR-3691-3p, both proteins were overexpressed in clinical PCa specimens compared with noncancerous prostate tissue. Our results indicate that TGF-β1-regulated miR-3691-3p acts as an anti-oncogene in PCa by downregulating E2F3 and PRDM1. These results provide novel insights into the mechanisms by which TGF-β1 contributes to the progression of PCa.
ABSTRACT
@#[Abstract] Objective: To investigate the expression of miR144-3p in bladder cancer tissues and cells and its effect on the proliferation and invasion of T24 cells. Methods: A total of 36 cases of bladder cancer tissue specimens and 10 cases of normal bladder epithelial tissue specimens were collected from Tangdu Hospital of Air Force Medical University during February 2018 and December 2018. In addition, bladder cancer T24 cell line and normal urothelial cell line SV-HUC-1 were also collected for this study. The levels of miR144-3p in bladder cancer tissues and cells were detected by qPCR methods. The miR-144-3p mimics and miR-NC were transfected into T24 cells by LipofectamineTM 2000, respectively. The proliferation, cell cycle distribution and invasion abilities were detected by MTT, Flow cytometry and Transwell chamber methods, respectively. TargetScan software was used to predict the binding site between miR-144-3p and E2F3 (E2F transcription factor 3); Dual luciferase reporter gene assay was used to verify the relationship between miR-144-3p and E2F3; and WB was used to detect the expression levels of miR-144-3p and E2F3 in cells. Results: The expression of miR-144-3p was downregulated in bladder cancer tissues and cells (all P<0.01). In addition, the expression level of miR-144-3p in muscular invasive bladder cancer tissues was significantly lower than that in non-muscular invasive bladder cancer tissues (P<0.05). Dual luciferase reporter gene assay confirmed that there was a targeted relationship between miR-144-3p and E2F3. Overexpression of miR-144-3p inhibited the proliferation and invasion of T24 cells (all P<0.01) and downregulated the expression of E2F3 (P<0.01); upregulation of E2F3 could reverse the inhibitory effect of miR-144-3p overexpression on proliferation and invasion of T24 cells. Conclusion: miR-144-3p has low expression level in bladder cancer tissues. It inhibits proliferation and invasion of bladder cancer cells by downregulating E2F3.