p38通路在二烯丙基二硫诱导人胃癌MGC803细胞G_2/M期阻滞中的作用

Diallyl Disulfide-Induced G_2/M Arrest of Human Gastric Cancer MGC803 Cells Involves Activation of p38 MAP Kinase Pathways

背景与目的:研究表明p38通路参与了细胞G2/M期阻滞过程的调控,但对其调控机制研究很少。本研究旨在探讨p38通路在二烯丙基二硫(diallyldisulfide,DADS)诱导人胃癌MGC803细胞G2/M期阻滞中的作用及其机制。方法:采用MTT法检测MGC803细胞的生长活性;流式细胞仪检测药物对细胞周期分布的影响;Westernblot法检测药物对P38蛋白、磷酸化P38蛋白、Cdc25C蛋白的表达。结果:MTT法检测结果显示,P38特异性抑制剂SB203580可拮抗DADS对MGC803细胞的抑制增殖作用。流式细胞仪分析表明,30mg/L的DADS处理MGC803细胞24h后,G2/M期的比率为39.4%,高于对照组的9.3%(P<0.05);但用SB203580抑制P38的活性后,DADS诱导的G2/M期比率从39.4%降到21.2%(P<0.05)。Westernblot结果表明,DADS处理MGC803细胞后,p38通路快速激活,磷酸化P38的表达与对照组相比,在20min内升高3.52倍,而P38总蛋白量没有发生明显改变;DADS作用24h后,Cdc25C磷酸酶表达降低了62%,而用SB203580抑制剂后,DADS对Cdc25C的抑制作用可以部分逆转(P<0.05)。结论:DADS可能通过激活p38通路使部分MGC803细胞停滞在G2/M期,p38通路调节Cdc25C磷酸酶的表达在DADS诱导MGC803细胞G2/M期阻滞中起着重要作用。

BACKGROUND &OBJECTIVE: p38 MAP kinase signal transduction pathway was thought to be involved in the G2/M arrest,however,the involved mechanisms were not clear. This study was designed to determine the role of p38 MAP kinase signal transduction pathways in diallyl disulfide (DADS) induced G2/M arrest in human gastric cancer MGC803 cells and its related molecular mechanisms. METHODS: MGC803 cells growth inhibition was measured by MTT assay. Phase distribution of cell cycle was analyzed by flow cytometry. Expression of Cdc25C, p38, phosphorylation of p38 (pp38) were determined by Western blot analysis. RESULTS: MTT assay showed that SB203580, a specific p38 MAPK inhibitor, blocked DADS induced growth inhibition. Flow cytometry analysis revealed that treatment of MGC803 cells with 30 mg/L DADS for 24 hours increased in the percentage of cells arrested in the G2/M phase from 9.3%to 39.4%(P< 0.05). Whereas in the presence of SB203580 the percentage decreased nearly one time, from 39.4%to 21.2%(P< 0.05). Western blot analysis showed that phosphorylation of p38 was increased 3.52 folds following treatment of MGC803 cells with 30 mg/L DADS for 20 minutes. At the same time, the total p38 abundance did not change. DADS treatment of MGC803 cells for 24 hours decreased the level of Cdc25C by 68%, and pretreatment of MGC803 cells with SB203580 partially reversed the downregulation of Cdc25C level by DADS (P< 0.05). CONCLUSION: DADS induced G2/M arrest of MGC803 cells involves the activation of p38 MAP kinase pathway. Decreased Cdc25C protein expression by p38 played a crucial role in G2/M arrest after the treatment with DADS.