Abstract: Objectives To observe the effects of arsenic trioxide (As₂O₃) on the cell cycle, differentiation and proliferation of cultured mouse melanoma Cloudman S91 cells. Methods The cell viability was measured by MTT reduction assay. The morphological changes of the cells were examined by Wright-Giemsa staining. Clone forming was carried out to test the proliferation ability. Apoptosis rate and cell cycle of S91 cells were measured by flow cytometry. Results As₂O₃ in the concentrations of 0.031~0.25 μmol/L promoted cell growth markedly and blocked the transformation of cells from G₀ to G₁. As₂O₃ in the concentrations of 0.5~8.0 μmol/L inhibited the cell growth and induced apoptosis markedly. Conclusions As₂O₃ has marked effects on mouse melanoma S91 cells, which include inducing apoptosis and promoting differentiation and proliferation. These effects are dose- and time-dependent.

Key words: Arsenicals, Melanoma, experimental, Apoptosis