Effect of tunicamycin treatment on cell apoptosis induced by doxorubicin in HepG2 cells.

<p>(A) HepG2 cells were pretreated with 3 µmol/L tunicamycin (TM) for 8 hr and then exposed to doxorubicin (2.5 mg/L) for 24 hr. Sub-G1 analysis in HepG2 cells were determined by FACS, and the data are expressed as the mean ± SD of three independent experiments. a: Untreated HepG2 cells; b: HepG2 cells treated with tunicamycin alone; c: HepG2 cells treated with doxorubicin alone; d: HepG2 cells were pretreated with tunicamycin for 8 hr, and then exposed to doxorubicin for 24 hr. (B) and (C) Cell morphology and percentage of apoptotic cells was examined by TUNEL staining. In this representative image, the cells with brown nuclei are apoptotic cells. a: Untreated HepG2 cells; b: HepG2 cells treated with tunicamycin alone; c: HepG2 cells treated with doxorubicin alone; d: HepG2 cells were pretreated with tunicamycin for 8 hr, and then exposed to doxorubicin for 24 hr. Data are presented as mean ± SD of three independent experiments (bars represent S.D.). (**P<0.01, compared with untreated HepG2 cells; ^##P<0.01, compared with doxorubicin alone) (D) Cleaved caspase-3 as an apoptotic marker were measured by western blot using specific anti- caspase-3 antibody. β-actin in the same HepG2 cells extract was used as an internal reference.