Expression of miR-21 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 of microRNA-21(miR-21)in breast cancer cell lines and serum of patients with breast cancer and the impact on the invasion and migration of breast cancer cells.Methods From Jan 2013 to Feb 2014, miR-21 expression were determined by fluorescent quantity polymerase chain reaction (FQ-PCR) in 4 breast cell lines (HBL-100, MCF-7, MDA-MB-231 and MDA-MB-468) and in serum from breast cancer patients ( n =56 ) , breast benign disease patients ( n =39 ) andhealth controls ( n =45 ) . The characteristics of cell invasion and migration were examined by transwellinvasion and migration assay afterbreast cancer cell line MDA-MB-231 were transfectedwith miR-21 inhibitor or negative control by lipofectamin.The t test was used to analysis the normal distribution data. Results FQ-PCR results showed that the relative expression of miR-21 in the normal breast epithelial cell line HBL-100 was 1.01 ±0.04, in the breast cancer cell line MCF-7, MDA-MB-231 and MDA-MB-468 were 1.99 ±0.11,4.02 ±0.38 and 3.73 ±0.79 respectively.Compared with the normal controls, miR-21 were highly expressed in the three breast cancer cell lines, the difference was statistically significant (t=9.01, 9.20 and 4.55, respectively, P<0.01); and the miR-21 was highly expressed in invasive and metastatic breast cancer cell lines (MDA-MB-231 and MDA-MB-468),compared with weakly invasive breast cancer cell line MCF-7, the difference was statistically significant ( t values were 6.14 and 2.91, P<0. 05), suggesting that miR-21 is highly expressed in breast cancer cells, and is closely related to the invasion and metastasis.The relative expression of miR-21 in serum of breast cancer was 2.63 (1.57-4.59), in benign breast disease group was 1.34 (1.01-1.78), in healthy control group was 0.81 (0.52-1.59), the miR-21 expression in the serum of breast cancer patients was significantly higher than in patients with benign lesions and normal control group (U values were 208 and 279, P<0.01), whereas no significant difference in serum in patients with benign lesions and normal control group, the miR-21 expression in the serum of breast cancer patients with lymph node metastasis (U=95 , P=0.19) was 3.55 (2.44-5.26), significantly higher than those without lymph node metastasis [2.11(1.59-3.25), U=216,P=0.021]. The results of invasion and migration assay showed that cells treated with miR-21 inhibitor invasion was44 ±18, the number of cell migration was98 ±22, while the negative control treated cells after invasion was133 ±44, migration cell number255 ±35;miR-21 inhibitor treatment compared with the negative control, cell invasion and migration was also significantly decreased( t values were 5.46 and 9.08, P<0. 01) .The cell invasion and migration assay indicated the numbers of MDA-MB-231 cells, which invaded or migrated to lower chamber, were 44 ±18 and 98 ±22 respectively after miR-21 inhibitor was applied, The numbers of invaded or migrated cells were 133 ±44 and 255 ±35 when the negative control was applied.The ability of cell invasion and migration was decreased significantly in the inhibitor group compared with the negative group(tvalue separately was 5.46, 9.08, P<0.01).The capacity of breast cancer cell invasion and migrationwas significantly decreased after transfection ofmiR-21 inhibitor.Conclusions MiR-21 is highly expressed in breast cancer cell lines and breast cancer patients′serum.Altered expression of miR-21 maybeplays an important role in breast cancer invasion and migration.MiR-21 may serve as new biomarker to early detectionand prognosis estimation of breast cancer.