Synergistic effect of cell differential agent-II and arsenic trioxide on induction of cell cycle arrest and apoptosis in hepatoma cells

Abstract

AIM: To illustrate the possible role of cell differential agent-II (CDA-II) in the apoptosis of hepatoma cells induced by arsenic trioxide (As₂O₃).

METHODS: Hepatoma cell lines BEL-7402 and HepG2 were treated with As₂O₃ together with CDA-II. Cell surviving fraction was determined by MTT assay; morphological changes were observed by immunofluorescence staining of Hoechst 33258; and cell cycle and the apoptosis index were determined by flow cytometry (FCM).

RESULTS: Cytotoxity of CDA-II was low. Nevertheless, CDA-II could strongly potentiate arsenic trioxide-induced apoptosis. At 1.0 g/L CDA-II, IC₅₀ of As₂O₃ in hepatoma cell lines was reduced from 5.0 µmol/L to 1.0 µmol/L (P < 0.01). The potentiation of apoptosis was dependent on the dosage of CDA-II. FCM indicated that in hepatoma, cell growth was inhibited by CDA-II at lower concentrations (< 2.0 g/L) primarily by arresting at S and G₂ phase, and at higher concentrations (> 2.0 g/L) apoptotic cell and cell cycle arresting at G₁ phase increased proportionally. The combination of two drugs led to much higher apoptotic rates, as compared with the either drug used alone.

CONCLUSION: CDA-II can strongly potentiate As₂O₃-induced apoptosis in hepatoma cells, and two drugs can produce a significant synergic effect.

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