miR-451 inhibits invasion and proliferation of bladder cancer by regulating EMT

Abstract

MicroRNAs (miRNAs) have recently been reported play a crucial role in some tumors. In order to investigate the association of miR-451 with bladder cancer, we investigate the expression of miR-451 in bladder cancer tissues and its role in biological behavior of T24, 5637 and J28 bladder cancer cell lines. Quantitative RT-PCR results showed miR-451 was significantly down-regulated in bladder cancer tissues and paracancerous tissues compared with normal bladder tissues. miR-451 expression was significantly associated with histological differentiation degree and TNM stage. Over-expression of miR-451 was established by transfecting miR-451 mimics into T24, 5637 and J28 cells, and its effects on the biological behavior of bladder cancer were studied using transwell assay, migration assay, adhesion assay, MTT and flow cytometry. Results indicated over-expression of miR-451 significantly inhibited cell proliferation, migration, invasion and induced apoptosis of the bladder cancer cells. Furthermore, we investigated the expression level of EMT related proteins in transfected 5637 cells by western blot. Results shown E-cadherin was up-regulated more significantly than N-cadherin, vimentin and Snail. N-cadherin and vimentin were up-regulated significantly when miR-451 was inhibited in miR-451 inhibitor group, however, no significant changes in mimics group. In conclusion, miR451 should be a tumor-suppressing gene in bladder cancer. miR-451 could maintain the bladder tumor cells in epithelial phenotype, inhibit EMT process, thereby reducing the invasion and migration of tumor cells.

Keywords: EMT; bladder cancer; miR-451.

Figure 1

miR-451 expression in bladder cancer tissues and matched adjacent and normal tissues. A. Comparison of miR-451 expression in bladder cancer tissues, paracancerous tissues and normal bladder tissues. B. The expression level of miR-451 in distant migration tumor cells and no distant migration tumor cells. C. The expression level of miR-451 in Ta-T4 group. D. The expression level of miR-451 in bladder cancer tissues and corresponding paracancerous tissues of different differentiation. The term 2^-ΔΔCT was used to describe the expression level of miR-451. Small nuclear RNA U6 served as internal normalized references for miR-451. X ± SD is represented in the images. miR-451 expression in normal bladder tissues was normalized and calculated as 1. **P < 0.01.

Figure 2

A. miR-451 expression in T24, 5637 and J82 cell lines. B. miR-451 over-expression in T24, 5637 and J82 cell lines inhibit cell invasion compared with the control group and NC group. C. miR-451 over-expression in T24, 5637 and J82 cell lines weakened cell adhesion ability compared with the control group and NC group. D. miR-451 over-expression in T24, 5637 and J82 cell lines inhibits cell migration compared with the control group and NC group. **P < 0.01.

Figure 3

miR-451 reduced cell proliferation and induced apoptosis in bladder cancer cells. A. miR-451 over-expression significantly reduced cell proliferation in T24, 5637 and J82 cell lines. B. miR-451 over-expression significantly induced apoptosis in T24 and 5637 cell lines. **P < 0.01.

Figure 4

A. TGF-β induced EMT. B, C. Expression of four EMT related proteins in 5637 cells. miR-451 over-expression promotes the induction of E-cadherin, and down-regulated stimulate N-cadherin expression. The expression level of β-actin was used as an internal control. **P < 0.01. *P < 0.05.