Expression of miR-145 in breast cancer and its role in invasion and migration of breast cancer cells / 中华检验医学杂志

ABSTRACT

Objective To investigate the expression level of microRNA-145 in breast cancer cell lines andtissues and its impact on breast cancer invasion and metastasis.Methods MiR-145 expression was detected by FQ-PCR in 5 breast cancer cell lines ( HBL-100, MCF-7, MDA-MB-231, MDA-MB-468 and SK-BR-3)and in breast cancer tissue and paraneoplastic tissues (n=39).The miR-145 expression plasmid ( Psif-miR-145 ) and negative control plasmid were transfected into SK-BR-3 using lipofectamine, respectively.The characteristics of invasion and migration of the transfected SK-BR-3 cells were examined by scratch test and transwell assay.The target genes of miR-145 were predicted by bioinformatics and the ANGPT2 gene were verified as miR-145 target by the dual-luciferase reporter assay.The expression levels of ANGPT2 protein was examined by western blot after pSIF-miR-145 transfection by lipofectamine in breast cancer cell line SK-BR-3.Results FQ-PCR result indicated that miR-145 expression level waslower in breast cancer tissue (45.93 ±22.02)than paraneoplastic tissue [ (182.04 ±56.92), U value was 7, P<0.01].MiR-145 expression level was lower in breast cancer cell lines than normal breast cells.miR-145expression in 4 breast cancer cell lines was 0.51 ±0.05, 0.07 ±0.01, 0.36 ±0.04 and 0.04 ±0.01, respectively.Compare with normal breast cell, miR-145 was lower expressed in all 4 breast cancer cell lines (t value separately was 15.93, 308.17, 25.02, 201.30;P<0.05).Lower expression of miR-145 was observed in the highly invasive breast cancer cells (MDA-MB-231, MDA-MB-468 and SK-BR-3), compared with weakly invasive breast cancer cell (MCF-7) (t value separately was14.18, 3.78, 15.20;P<0.05). Wound healing assay shows that overexpression of miR-145 in SK-BR-3 significantly reducedthe motility as compared with control group (P <0.01).The cell invasion assay indicated the numbers of miR-145 overexpressed SK-BR-3 cells, which invased to lower chamber, was 137 ±37, the numbers of invased cells was 617 ±80 when the negative control was applied. Over-expression of miR-145 could repress the expression levelsof ANGPT2 protein;miR-145 could repress the activity of luciferase reporter carrying a 3′-untranslated region of ANGPT2 mutated the predicted binding site, the activity of luciferase was reversed. Conclusions MiR-145 depressed in breast cancer cell lines and breast cancer tissues.MiR-145 maybe plays an important role in breast cancer invasion and migration by directly target ANGPT2.