The Mechanism Of Med19 Promoting The Proliferation Of Breast Cancer

Objective To explore the mechanism of Med19 targeted CBFA2T3-HEB pathway promoting the proliferation of breast cancer.Methods Lentivirus expression vector with si RNA-Med19 and overexpression of Med19(LV-Med19) and CBFA2T3(LV-CBFA2T3) were constructed according to the sequence of Med19 gene, then transfection of human breast cancer cell lines with lentirivus expression vector. The human breast cancer MCF-7, MDA-MB-231 cells which high expressed of Med19 were divided into three groups: transfection of lentivirus expression vector with si RNA-Med19(KD group), transfection of lentivirus expression vector with NC-Med19(NC group), and CON group. The BT549, Hs578 T cells which low expression of Med19 were handled according to the following rules: a, transfection of CON-Med19 only; b, transfection of LV-Med19 only; c, transfection of both LV-Med19 and CONCBFA2T3; d, transfection of both LV-Med19 and LV-CBFA2T3. MTT tests and colony formation assay were applied to test the proliferation of human breast cancer cells. Then RT-PCR and Western blot were used to determine the levels of Med19, CBFA2T3 and HEB genes m RNA and protein expression. Extraction of 25 cases of breast cancer tissue proteins, western blot was used to determine the levels of Med19 and CBFA2T3. SPSS18.0 was used to statistic the correlation between them.Results Si RNA- Med19 lentirivus expression vector was transfected into Med19-high expressed human breast cancer MCF-7, MDA-MB-231 cells successfully. Compared with NC group and CON group, cell proliferation and colony-formation capacity of KD group were significantly inhibited(P<0.05). RT-PCR and Western blot showed that the expression of Med19 m RNA and protein of KD group were dramatically inhibited, and the CBFA2T3 were significantly up-regulated, while the HEB was opposite(P<0.05). This suggests that down-regulation of Med19 may inhibit the breast cancer cell proliferation by up-regulating the expression of CBFA2T3 and further shutting down the expression of HEB that CBFA2T3-activated. While Med19 overexpression lentirivus vector(LV-Med19) transfected Med19-low express BT549, Hs578 T cells, the proliferation and colonyformation capacity were significantly increased(P<0.05). The expression of Med19 m RNA and protein were significantly increased, CBFA2T3 were decreased dramaticaly and the HEB was also upregulated when compared to CON-Med19 group(P<0.05). This showed that Med19 promotes proliferation of breast cancer cell by inhibiting the expression of CBFA2T3 and promoting the HEB that CBFA2T3-activated. While BT549, Hs578 T cells transfected by both LV-Med19 and LV-CBFA2T3,cell proliferation and colonyformation capacity were inhibited tending to CON-Med19 group. It sthowed that the proliferation promoting effects of Med19 can be eliminated by up-regulating CBFA2T3. And Western blot also showed that there was negative correlation between the expressions of Med19 and CBFA2T3 protein(r=-0.553, P<0.01), further proving that CBFA2T3 was regulated by Med19.Conclusion 1.Up-regulation of Med19 gene promotes breast cancer cell proliferation.2. Med19 promotes breast cancer cell proliferation by inhibiting the expression of CBFA2T3 and further increasing the expression of HEB that CBFA2T3-activated.3. Down-regulation of Med19 or up-regulation of CBFA2T3 could be new strategy for the targeted therapy of breast cancer.