CHARACTERIZATION OF CELL DEATH INDUCED BY ANTICANCER ANTIBIOTIC LIDAMYCIN IN HUMAN HEPATOMA BEL-7402 CELLS / 药学学报

ABSTRACT

AIM　To study the features of cell death induced by the anticancer antibiotic lidamycin (LDM) in human hepatoma BEL-7402 cells. METHODS　Chromatin condensation was observed by co-staining with fluorescent dyes, hoechst 33342 and propidium iodide. “G1 sub-peak” was detected by flow cytometry and DNA ladder was observed using agarose gel electrophoresis. The caspase-3, 6 activities were measured with kits specific for them. RESULTS　Typical apoptotic chromatin condensations appeared when the BEL-7402 cells were treated with the conventional antitumor agent mitomycin C 30 μmol.L-1 for 12 h. However, an abnormal type of chromatin condensation occurred when the cells were treated with LDM 1 μmol.L-1 for 6 h, which was characterized with keeping the completeness of nuclear membrane and not forming apoptotic bodies. The DNA ladder patterns were observed using agarose gel electrophoresis. The “G1 sub-peak” occurred only in the cells treated with LDM for 24 h, though chromatin condensation was earlier detected in treatment with LDM for 6 h. The caspase-3, 6 activities were increased about 5 and 4 folds, after the cells were treated with LDM 1 μmol.L-1 for 6 h, as did mitomycin C. The time of initiating chromatin condensation was earlier than that of the high peak activities of caspase-6. CONCLUSION　The characterization of cell death induced by lidamycin in the human hepatoma BEL-7402 cells differs from typical apoptosis. The results make it helpful to explain the molecular mechanism of the highly potent cytotoxicities of lidamycin toward tumor cells.