Induction of apoptosis in human leukemic HL-60 cells by trichosanthin / 中国病理生理杂志

ABSTRACT

AIM: To study the effect of trichosanthin (TCS), a type I ribosome-inactivating protein, on the induction of apoptosis in human leukemic cell line HL-60 cells and the influence of cycloheximide (CHX) on TCS-induced apoptosis. METHODS: Flow cytometry together with fluorescent microscopy were adopted to investigate the apoptotic cell death in HL-60 cells treated with TCS. RESULTS: Flow cytometric analysis indicated that TCS was able to induce significant apoptosis in HL-60 cells. The rates of apoptotic cells in HL-60 cells treated with TCS (20 mg/L) for 48 h was 48.7%±2.3%(±s), which was significantly higher than that of control (6.3%±1.0%)(P＜0.05). Under the same condition, the rate of apoptosis caused by CHX (5 mg/L) was 65.3%±3.9%. TCS-induced apoptosis was further confirmed by fluorescent microscopy observation and DNA gel electrophoresis, in which typical nuclear morphological changes such as chromatin condensation, nuclear fragmentation, were observed in many of the cells treated with TCS， and DNA extracted from these cells displayed typical ladder pattern. Furthermore, the effect of TCS was significantly enhanced with the pretreatment of CHX (0.2 mg/L) which did not induce any significant apoptosis when used at 0.2 mg/L seperately. TCS-induced apoptosis was time- and dose-dependent. CONCLUSION: TCS was able to induce apoptosis in HL-60 cells, which was enhanced by CHX. It was suggested that TCS-induced apoptosis was independent of new protein synthesis.