Apoptotic Volume Decrease is the Early Event in Arsenic Trioxide Induced Apoptosis in Breast Cancer Cells

OBJECTIVE To investigate whether the apoptotic volume decrease is the early event in arsenic trioxide induced apoptosis in breast cancer MCF-7 cells. METHODS The effect of As₂O₃ on cell viability was assayed by methylthiazoletetrazolium(MTT). Apoptosis was analyzed by flow cytometry. Lag-time microphotography was employed to detect cell volume. The apoptotic signaling activity of Caspase-3 was detected by caspase assay kit. RESULTS MTT result showed As₂O₃ reduced the viability of MCF-7 cells in a concentration-dependent manner. Flow cytometry assay confirmed apoptosis resulted in As₂O₃-treated MCF-7 cells. Apoptotic volume decrease was observed within 2 h in As₂O₃ treated MCF-7 cells, but the caspase-3 activity had no significant change. The caspase-3 activity increased significantly until As₂O₃ treated MCF-7 cells for 6 h. CONCLUSION Apoptotic volume decrease is the early event in arsenic trioxide induced apoptosis in breast cancer cells.