Roles of PLC-γ2 and PKCα in TPA-induced apoptosis of gastric cancer cells
Roles of PLC-γ2 and PKCα in TPA-induced apoptosis of gastric cancer cells
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DOI：
10.3748/wjg.v9.i11.2413
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发表时间：
2003-11
影响因子：
4.3
通讯作者：
Bing-huo Zhang;Qiao Wu;Xiao-feng Ye;Su Liu;Xiao-feng Lin;Mu Chen
中科院分区：
文献类型：
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作者：
Bing-huo Zhang;Qiao Wu;Xiao-feng Ye;Su Liu;Xiao-feng Lin;Mu Chen
目的：探讨PLCγ2和PKCα在TPA诱导胃癌细胞凋亡中的作用。方法：人胃癌细胞株MGC 80 -3。Western blot检测PLCγ2和PKCα蛋白表达水平。激光扫描共聚焦显微镜下免疫荧光分析显示PLCγ2和PKCα的蛋白定位。DAPI荧光染色观察细胞凋亡形态，并随机抽取1000个细胞计数凋亡指数。研究结果：TPA处理胃癌MGC 80 -3细胞后，不仅可上调PLC-γ2蛋白的表达，而且可诱导PLC-γ2从细胞质向细胞核移位。然而，这一过程并不直接与细胞凋亡诱导。进一步研究表明，PKCα由胞浆向胞核转位与细胞凋亡的启动有关。为探讨PLC-γ2与PKCα在凋亡诱导过程中的必然联系，采用PLC抑制剂{“type”：“entrez-nucleotide”，“attrs”：{“text”：“U 73122”，“term_id”：“4098075”，“term_text”：“U 73122”}} U 73122阻断PLC-γ2易位，但在MG C80 -3细胞中既不刺激PKCα易位，也不诱导凋亡。然而，当TPA暴露于U 73122处理的细胞时，不仅PLC-γ2重新分布，而且PKCα也重新分布。而单独用PKC抑制剂处理细胞时，PLC-γ2蛋白仍定位于胞浆。而在TPA存在时，无论是否存在PKC抑制剂，PLC-γ2蛋白均发生重新分布。结论：PLC-γ2转位是TPA信号传递至下游分子PKCα的关键。PKCα作为一种效应子直接促进MGC 80 -3细胞凋亡。因此，PLCγ2和PKCα的蛋白转位是诱导细胞凋亡过程中的关键事件。
AIM: To investigate the roles of PLCγ2 and PKCα in TPA-induced apoptosis of gastric cancer cells. METHODS: Human gastric cancer cell line MGC80-3 was used. Protein expression levels of PLCγ2 and PKCα were detected by Western blot. Protein localization of PLCγ2 and PKCα was shown by immunofluoscence analysis under laser-scanning confocal microscope. Apoptotic morphology was observed by DAPI fluorescence staining, and apoptotic index was counted among 1000 cells randomly. RESULTS: Treatment of gastric cancer cells MGC80-3 with TPA not only up-regulated expression of PLC-γ2 protein, but also induced PLC-γ2 translocation from the cytoplasm to the nucleus. However, this process was not directly associated with apoptosis induction. Further investigation showed that PKCα translocation from the cytoplasm to the nucleus was correlated with initiation of apoptosis. To explore the inevitable linkage between PLC-γ2 and PKCα during apoptosis induction, PLC inhibitor {"type":"entrez-nucleotide","attrs":{"text":"U73122","term_id":"4098075","term_text":"U73122"}}U73122 was used to block PLC-γ2 translocation, in which neither stimulating PKCα translocation nor inducing apoptosis occurred in MGC80-3 cells. However, when {"type":"entrez-nucleotide","attrs":{"text":"U73122","term_id":"4098075","term_text":"U73122"}}U73122-treated cells were exposed to TPA, not only PLC-γ2, but also PKCα was redistributed. On the other hand, when cells were treated with PKC inhibitor alone, PLC-γ2 protein was still located in the cytoplasm. However, redistribution of PLC-γ2 protein occurred in the presence of TPA, no matter whether PKC inhibitor existed or not. CONCLUSION: PLC-γ2 translocation is critical in transmitting TPA signal to its downstream molecule PKCα. As an effector, PKCα directly promotes apoptosis of MGC80-3 cells. Therefore, protein translocation of PLCγ2 and PKCα is critical event in the process of apoptosis induction.