摘要
背景与目的:既往研究发现,肿瘤细胞的多药耐药(multidrugresistance,MDR)与蛋白激酶C(proteinkinaseC,PKC)信号转导系统关系密切,但其作用机制有待于进一步研究。本实验拟通过研究长春新碱(vincristine,VCR)及选择性PKCα、β抑制剂myr-ψPKC对人胃癌细胞MGC803的作用,探讨PKC信号转导系统与mdr1基因的关系。方法:用Westernblot检测MGC803细胞中mdr1基因编码的P-糖蛋白(P-glycoprotein,P-gp)的表达以及VCR作用对其表达的影响,用流式细胞术对VCR及作用后的细胞进行周期分析,同时用MTT法验证VCR诱导后及其作用下MGC803细胞的药物敏感性。结果:MGC803细胞在VCR短期作用下,P-gp表达增加,在myr-ψPKC的作用下其表达受到抑制。通过细胞周期分析发现VCR和myr-ψPKC共同作用的细胞其凋亡比例为31.23%,显著高于VCR单独作用时的细胞凋亡率(18.41%)(P<0.05)。VCR刺激后MGC803细胞对VCR的IC50为(284.0±13.2)ng/ml,是阴性对照组IC50犤(127.0±17.6)ng/ml犦的2.24倍,是myr-ψPKC组IC50犤(212.0±30.4)ng/ml犦的1.33倍。结论:MGC803细胞在VCR的短期作用下可诱导产生P-gp,而myr-ψPKC可通过选择性抑制PKCα、β而抑制P-gp的表达和逆转其耐药性,从而促进MGC803细胞的凋亡。PKC可能对胃癌mdr1表达有调节作用。
BACKGROUND & OBJECTIVE: It is showed that there is close rela ti onship between multidrug resistance (MDR) and protein kinase C signal transducti on system, but the mechanism remains unclarified. The aim of this study was to i nvestigate the correlation between protein kinase C (PKC) signal transduction sy stem and mdr1 gene in human gastric cancer cell line through studying the effect of vincristine (VCR) and a selective inhibitor of PKC, myr- ψ PKC on MGC803 c ells. METHODS: Western blot analysis was used to analyze the expression of P- g lycoprotein (P- gp), which was encoded by mdr1, in transient VCR induced MGC803 cells, which were treated with or without myr- ψ PKC. Cell cycle analysis was performed using flow cytometry and MTT assay was used to investigate the drug s usceptibility of MGC803 cells which were exposed to VCR with or without myr- ψ PKC. RESULTS: High level of P- gp expression was detected in the MGC803 cells after transient exposure to VCR, and its expression was down- regulated when th e same VCR induced MGC803 cell line was incubated with myr- ψ PKC. FCM results indicated that more MGC803 cells showed significantly higher level of apoptotic phenotype when treated with VCR and myr- ψ PKC (ratio 31.23% ), than those t reated with only VCR (ratio 18.42% ). The IC50 (284.0± 13 2 ng/ml) to VCR of MGC803 cells pretreated with VCR exhibited 2.24- fold of negative control grou p (127.0± 17 6 ng/ml) and 1.33- fold of the group (212.0± 30 4 ng/ml) tre ated with myr- ψ PKC. CONCLUSION: The expression of P- gp can be induced by t ransient exposure to VCR and this induction can be inhibited by myr- ψ PKC, wh ich blocks the activity of PKCα and β . PKC signal transduction system may pl ay certain roles in modulating mdr1 expression in gastric cancer.
出处
《癌症》
SCIE
CAS
CSCD
北大核心
2004年第4期396-400,共5页
Chinese Journal of Cancer
