Inhibition by arsenic trioxide of human hepatoma cell growth

Arsenic trioxide (As2O3) has been shown to be effective for treatment of patients with refractory or relapsed acute promyelocytic leukemia and a variety of other malignant hematopoetic disorders. We studied the effect of this agent on proliferation of human hepatoma-derived cell lines (SK-Hep-1, HepG2, and HuH7). In HuH7 cells, As2O3 reduced proliferation time- and dose-dependently at 1 and 2 μM, while in SK-Hep-1 and HepG2 cells, As2O3 inhibited proliferation at 2 and 4 μM respectively. Cell cycle analysis by flow cytometry showed that As2O3 induced apoptosis in these hepatoma-derived cells as confirmed by appearance of sub-G1 cells. Sensitivity of hepatoma-derived cells to As2O3 was inversely related to their intracellular glutathione (GSH) and intensity of GSH synthesis. Arsenic sensitivity was restored to relatively resistant cell lines when GSH was depleted by l-buthionine sulfoximine (BSO). These results indicate that As2O3 may have therapeutic potential for treatment of hepatocellular carcinoma.