蛋白酶体抑制剂MG132诱导HL-60细胞凋亡前G2/M期阻滞及机制

背景和目的:蛋白酶体(proteasome)抑制剂能够诱导多种肿瘤细胞凋亡,是一种潜在的有应用前景的抗肿瘤剂.本研究旨在探讨蛋白酶体抑制剂MGl32(Z-Leu-Leu-Leu-CHO)诱导白血病细胞HL-60凋亡和C2/M期阻滞的机制.方法:采用荧光显微镜观察、流式细胞术和免疫印迹研究测定MG132诱导HL-60细胞凋亡和周期阻滞及机制.结果:2μmol/L的MG132能够有效地诱导HL-60细胞凋亡,用药后24 h就显现有细胞凋亡;在MG132诱导HL-60细胞凋亡出现之前有一个明显的G2/M期阻滞,加MG132后12 h时G2/M期时相百分比为63.42±2.02;24 h时加MG132组细胞凋亡为16.67±1.48,与对照组G2/M期时相百分比为7.29±3.01及细胞凋亡为0相比,两者之间有显著性差别(P＜0.01);咖啡因CAF能够减少MG132诱导HL-60细胞出现的G2/M期阻滞,同时也减少凋亡细胞的比例;细胞周期检查点的负调控因子p21waf/cip1蛋白在加MG132处理后3 h有明显的表达,但并未能检测到p53和p27蛋白.结论:MG132诱导HL-60细胞凋亡之前有一个明显的G2/M期阻滞,p21蛋白表达明显上调提示:是p21waf/cip1而不是p53或其同源蛋白参与了其中的调控.

Mechanism of G2/M cell cycle arrest before apoptosis in leukemia cell line HL-60 induced by proteasome inhibitor MG132

BACKGROUND & OBJECTIVE: Proteasome inhibitor is a kind of potential anti-tumor drug,it can induce apoptosis in various tumor cells. This study was designed to investigate the molecular mechanism of apoptosis and G(2)/M arrest in leukemia cell line HL-60 induced by proteasome inhibitor MG132 (Z-Leu-Leu-Leu-CHO). METHODS: Apoptosis in HL-60 cells was observed under fluorescent microscope, flow cytometry and immunoblot were used to analyze cell apoptosis, cell cycle arrest, and the mechanisms. RESULTS: MG132 (2 micromol/L)induced apoptosis in HL-60 cells after 24-h treatment. Meanwhile, HL-60 cells were arrested at G(2)/M phase before apoptosis after induced by MG132. The percentage of G(2)/M phase in MG132-treated HL-60 cells at 12 h was 63.42+/-2.02,while that in untreated cells was 7.29+/-3.01 (P< 0.01). The percentage of apoptosis in MG132-treated HL-60 cells at 24 h was 16.67+/-1.48, while untreated cells had no death (P< 0.01). Compared to the treatment with MG132 only, caffeine (2 mmol/L) exposure can reduce G(2)/M arrest and apoptosis in MG132-treated HL-60 cells. Expression of cyclin-dependent kinase inhibitor p21waf/cip1 up-regulated after treated with MG132 for 3 h, but no p53 or p27 detected. CONCLUSIONS: Proteasome inhibitor MG132 can induce G2/M arrest before the apoptosis appeared in HL-60 cells. The obvious up-regulation of p21 indicated that it is p21(waf/cip1), but not p53 or p53-related proteins,that involved in the regulation of G(2)/M arrest and subsequent apoptosis induced by MG132 in HL-60 cells.