Effects for Histone Deacetylase Inhibitors on Proliferation and MKK7 Expression in Glioma Cells

Objective To investigate the effects of histone deacetylase inhibitors (HDACIs) on the proliferation and MKK7 expression in glioma cells. Methods Glioma cell line U251 cultured in vitro was transfected with MKK7-siRNA1, MKK7-siRNA2 and control siRNA for 48h, respectively. Western blot was performed to test MKK7 expression and JNK/c-Jun activities. BrdU incorporation assays were performed to determine the cellular proliferation rate. Cells were treated with 0.5μM HDAC inhibitor Trichostatin A (TSA) for 8h, dimethyl sulfoxide (DMSO) as a control. Western blot was performed to test the expression or phosphorylation levels of MKK7, p-JNK, JNK, p-c-Jun and c-Jun. MTT assays were performed to determine cellular proliferation rate at 8, 12, 24h after TSA treatment. Other HDACIs, including suberoylanilide hydroxamic acid (SAHA), valproic acid (VPA) and M344, were used to test if they could inhibit MKK7 expression and cellular proliferation as well. Results Compared with the control group, the knockdown of MKK7 suppressed JNK/c-Jun activities and proliferation rate(P=0.008); HDACI (0.5 μM TSA) treatment for 8h remarkably reduced MKK7 expression and JNK/c-Jun activities, and all other HDACIs (SAHA, M344, VPA) could suppress MKK7 expression as well. TSA treatment for 8 h did not decrease the proliferation rate, while TSA treatment for 12h significantly inhibited proliferation rate (P=0.006), and treatment for 24h exhibited more inhibitive effects (P=0.002); SAHA (P=0.001), M344 (P=0.008) or VPA (P=0.002) inhibited cellular proliferation as well. Conclusion HDACIs could inhibit MKK7 expression and MKK7-mdiated proliferation in glioma cells.