Abstract:

Objective To investigate the in vitro anti-proliferation effect of a histone deacetylase inhibitor, chidamide, on a cutaneous malignant melanoma cell line, A375. Methods Cultured A375 cells were treated with different concentrations of chidamide （5, 10, 50, 100, 500 μmol/L） and trichostatin A （TSA） （0.1, 0.25, 0.5, 1.0 μmol/L）, respectively, for various durations （24, 48, 72, 96, 120 hours）. Subsequently, cell proliferation, apoptosis and cell cycle were detected by MTT assay, annexin V- fluorescein isothiocyanate and propidium iodide double staining, and DNA ploid analysis, respectively. Results The proliferation of A375 cells was inhibited in a dose-dependent manner by chidamide of 5 - 500 μmol/L and TSA of 0.1 - 1 μmol/L, and in a time-dependent manner from 0 to 120 hours after the beginning of treatment with chidamide of 5 - 500 μmol/L and TSA of 0.25 - 1 μmol/L. The 48-hour 50% growth inhibition concentration （IC50） of chidamide and TSA on A375 cells was about 250 μmol/L and 0.7 μmol/L, respectively. After 48-hour treatment, the apoptosis rate was 80.27% ± 3.06%, 79.53% ± 5.70%, 83.13% ± 6.90% in A375 cells treated with chidamide of 62.5, 125, 250 μmol/L, respectively, 16.27% ± 2.46%, 28.83% ± 2.55%, 83.40% ± 8.65% in those treated with TSA of 0.175, 0.35, 0.7 μmol/L, respec- tively, 10.43% ± 0.96% in untreated cells; a statistical increase was noticed in chidamide-treated cells and TSA-treated cells vs. untreated cells （all P < 0.001）. A positive correlation was observed between the apoptosis rate and concentrations of TSA （r = 0.955, P = 0.000）. Cell cycle analysis indicated that treatment with chidamide induced cell cycle arrest in G0/G1 phase, with the cell proportion in G0/G1 phase being 76.30% ± 6.06%, 82.79% ± 0.74%, 88.91% ± 5.29% in A375 cells treated with chidamide of 62.5, 125, 250 μmol/L, respectively, versus 38.73% ± 3.36% in untreated cells. While after 48-hour treatment with TSA of 0.35 and 0.7 μmol/L, the proportion of cells in G2 /M phases was 25.15% ± 2.71% and 58.71% ± 3.45%, respectively, compared to 15.73% ± 0.23% in untreated cells （P < 0.01）. Conclusion Chidamide and TSA could induce cell cycle arrest and apoptosis, as well as inhibit the growth of A375 cells in vitro.