Fig. 2

Inhibition of Sp protein function increases Bak protein expression. MMA, as a potential Sp binding inhibitor, increases Bak expression starting from the concentration of 5 nM in PLC/5 cells in 48 h incubation, and induces cleaved PARP level, which is a main mediator of apoptosis (a). As shown in the points and connection line figure, increased Bak expression trend is accompanied with MMA concentration from 5 nM to 100 nM, with a peak value about 5-fold increase compared with baseline (b, repeated three times). The inhibition rate was tested in immortal non-tumour cell lines and cancer cell lines. In the tested six HCC cell lines, MMA upregulated Bak expression (c, column 3 to 8). In immortal cells, MIHA and LO2, are less sensitive to MMA treatment, showing slight increasing Bak expression (C, column 1 and 2, repeated three times). MMA significantly induces Bak expression at 30 nM. In RT-PCR experiment, data showed Bak mRNA level increased significantly in HepG2, PLC/PRG/5 and Hep3B cells (D, 4 repeated wells per assay, * p < 0.05 compared with the corresponding control)