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 was:44 ±18, the number of cell migration was:98 ±22, while the negative control treated cells after invasion was:133 ±44, migration cell number:255 ±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.
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.