Fig. 3

Metformin and OSMI-1 induce inhibition of Bcl2 activity through CHOP and JNK signaling pathways, respectively. A HCT116 cells were treated with metformin (1, 5, and 25 mM) for 48 h and the levels of PERK, P-eIF2α, ATF4, CHOP, Bcl2, and P-JNK were analyzed by western blot analysis. β-Actin was used as a loading control in all western blot analyses. B HCT116 cells were treated with OSMI-1 (5, 10, and 20 μM) for 48 h and the levels of P-JNK, CHOP, P-Bcl2, and Bcl2 were investigated by western blot analysis. C HCT116 cells were pretreated for 1 h in the presence or absence of SP600125 (50 µM) and then treated for 48 h with or without OSMI-1 (20 µM). The levels of P-JNK and P-Bcl2 were investigated by western blot analysis. D HCT116 cells were treated with metformin (25 mM), OSMI-1 (10 μM or 20 μM), or a combination thereof for 48 h, and CHOP, Bax, and Bcl2 levels were determined by western blot analysis. Significance was determined by control and combination treatment group Student’s t-test. ***p < 0.001. E HCT116 cells in 6-well plates were transfected with CHOP siRNA and treated with metformin (25 mM), OSMI-1 (20 μM), or a combination thereof for 48 h. The levels of ATF4, CHOP, and Bcl2 were determined by western blot analysis