Abstract: Objective To investigate the inhibitory effect of trichostatin A (TSA) on the proliferation of HepG2 cells and explore
the underlying mechanism. Methods HepG2 cells exposed to different concentrations of TSA for 24, 48, or 72 h were examined
for cell growth inhibition using a cell counting kit, changes in cell cycle distribution with flow cytometry, cell apoptosis with
annexin V-FTIC/PI double staining, and cell morphology changes under inverted microscope. The expressions of beta-catenin,
HDAC1, HDAC3, H3K9, cyclinD1 and Bax proteins in the exposed cells were detected by Western blotting, and the
expressions of HDAC1 and HDAC3 mRNAs by quantitative fluorescent PCR. Results Exposure to TSA caused significant
dose- and time-dependent inhibition of HepG2 cell proliferation (P<0.05) and resulted in increased cell percentage in G0/G1 and
G2/M phases and decreased cell percentage in S phase. The apoptotic index in the control group was (6.22 ± 0.25)% , which
increased to (7.17±0.20)% and (18.14±0.42)% after exposure to 250 and 500 nmol/L TSA, respectively. Exposure to 250 and 500
nmol/L TSA also caused cell morphology changes with numerous floating cells. The expressions of beta-catenin, H3K9 and Bax
proteins were significantly increased and CyclinD1, HDAC1, and HDAC3 protein expressions decreased in TSA-treated cells,
but the expressions of HDAC1 and HDAC3 mRNAs showed no significant changes. Conclusion TSA can inhibit the
proliferation of HepG2 cells and induce cell cycle arrest and apoptosis by inhibiting HDAC activity, promoting histone
acetylation, and activating Wnt/beta-catenin signaling pathway.