[Effect of miRNA-135b on proliferation, invasion and migration of triple-negative breast cancer by targeting APC].

OBJECTIVE: To explore the expression of miRNA-135b in a variety of breast cancer cell lines and its function on the proliferation, invasion and migration in triple-negative breast cancer cell lines by targeting adenomatous polyposis coli (APC).

METHODS: Quantitative real-time (RT)--PCR was used to detect the expression of miRNA-135b in seven breast cancer cell lines and one normal breast cell line. The three-negative breast cancer cell lines MDA-MB-231 and MDA-MB-468 with miRNA-135b high-expression were divided into three groups: the normal growth group, the negative control group (transfected with negative counter-part) and the experimental group (transfected with miRNA-135b inhibitors). RT- PCR and Western blot were used to explore the expression of APC. The proliferation was detected by Cell Counting Kit-8 (CCK-8) method and the invasion and migration were detected by Transwell method.

RESULTS: The levels of miRNA-135b were higher in triple-negative breast cancer cell lines than other types, especially MDA-MB-231 (P=0.001) and MDA-MB-468 (P=0.036). Compared with normal growth group and negative control group, the mRNA and protein of APC were up-regulated in experimental group MDA-MB-231 (P=0.013, P=0.021), MDA-MB-468 (P=0.017, P=0.014). CCK-8 results showed that the proliferation rate of experimental group was decreased compared with negative control and normal growth group MDA-MB-231 (P=0.00 ), MDA-MB-468 (P=0.01). The invasion and migration ability of MDA-MB-231 (P=0.002, P=0.00) and MDA-MB-468 (P=0.01, P=0.00) were obviously decreased after transfected miRNA-135b inhibitors.

CONCLUSION: The expressions of miRNA-135b were higher in most triple-negative breast cancer cell lines than others. miRNA-135b could promote the proliferation, invasion and migration in triple-negative breast cancer cell lines MDA-MB-231 and MDA-MB-468, and APC was one of the target genes of miRNA- 135b by participating in the process of regulation.