Relationship between miR-34a and VEGF expressions in breast cancer tissue and the clinical significance
Objective: To investigate the relationship between miR-34a and VEGF expressions in breast cancer and the clinical significance. Methods: The miR-34a and VEGF expression in 40 paired specimens of breast cancer and adjacent tissue were detected, and the relations of miR-34a expression with clinicopathologic factors and VEGF expression in breast cancer were analyzed. The influence of miR-34a on transcriptional activity of VEGF in breast cancer MCF-7 cells was determined by dual-luciferase reporter assay system. In MCF-7 cells after transfection with miR-34a mimics, the changes in cell proliferation and expression of VEGF and its down-stream Akt protein were determined. Results: In breast cancer tissue compared with adjacent tissue, the miR-34a expression was decreased while VEGF expression was increased significantly (both P<0.05), and the miR-34a expression was significantly related to TNM stage of breast cancer tissue (P<0.05) and was negatively correlated to VEGF expression in breast cancer tissue (r2=0.4469, P=0.0033). After miR-34a mimics transfection in MCF-7 cells, the transcriptional activity of VEGF was inhibited, proliferation rate was reduced, and the VEGF expression and phosphorylation level of Akt protein was down-regulated significantly (all P<0.05). Conclusion: MiR-34a expression in breast cancer tissue is decreased, which reduces the inhibition on VEGF and its down-stream Akt phosphorylation, and thereby facilitate the growth of breast cancer.