幽门螺杆菌作用后AGS细胞内钙离子的动态变化研究

Ca^(2+) sequential changes of AGS cell after infected by Helicobacter pylori

背景幽门螺杆菌(Helicobacter pylori,Hp)感染与胃癌发生密切相关,但致病机制尚未清晰。细胞毒素相关蛋白A(CagA)是Ⅰ型Hp的主要毒力因子,在Hp诱导的疾病特别是胃癌的发展中起重要作用。前期的研究发现,Hp作用后人胃腺癌上皮细胞(AGS)的钙离子相关蛋白钙网织蛋白CRT以及钙离子结合蛋白CALNUC磷酸化程度发生改变,提示Hp可能会影响AGS细胞的钙稳态,通过钙离子通路影响细胞的增殖或凋亡。目的研究Hp作用于人胃腺癌上皮细胞后,AGS细胞内钙离子的时序性变化,以及CagA对AGS细胞内钙离子的影响,进一步揭示Hp的致病机制。方法采用钙离子荧光标记示踪法,AGS细胞以Fluo-3/AM荧光指示剂负载,特异性地活体标记AGS内的钙离子,采用激光共聚焦显微镜观察分析Hp26695及其CagA缺失株(Hp26695△CagA)分别作用于AGS细胞1h、2h、3h、4h、5h、6h后,AGS细胞内钙离子的变化情况。结果幽门螺杆菌与AGS细胞相互作用1h,胞内Ca2+部分流失,5h胞内Ca2+大量流失。1～6h内,Hp26695与Hp26695△CagA作用的AGS细胞荧光强度没有显著差异。结论Hp作用会导致AGS细胞内Ca2+剥夺,且与CagA的存在无明显关联性。

Background Helicobacter pylori （H.pylori） infection is closely related with gastric cancer. The pathogenic mechanisms of H.pylori are not yet clear. Cytotoxin-associated protein A （CagA） is the main virulence factor for type I -H.pylori and plays an important role in the diseases induced, especially in the development of gastric cancer. Previous studies showed that the phosphorylation degree of calcium-related protein calreticulin （CRT） and nucleobindin-2 precursor （CALNUC） changed significantly in human gastric adenocarcinoma epithelial （AGS） which infected by H.pylori. This result suggested that H.pylori might affect the calcium homeostasis of AGS and could activate or inhibit its proliferation or apoptosis pathway. Aims To study the Ca^2＋ sequential changes and the effect of CagA on Ca^2＋ in AGS cells which were infected by H.pylori, further reveal the pathogenic mechanism of H.pylori. Methods The calcium fluorescent tracer method was used and calcium ions of AGS cells were labeled by fluorescent indicator Fluo-3/AM. After AGS cells were infected for 1 to 6 hours by H.pylori 26695 and H.pylori26695△CagA respectively, laser scanning confocal microscope was used to analyse the change status of AGS cells. Results Part of the intracellular Ca^2＋ lost when AGS cells were infected for 1 hour and large number of intracellular Ca^2＋ lost when AGS cells were infected for 5 hour by H.pylori 26695 or H.pylori 26695 △ CagA. There was no significant difference in fluorescence intensity of AGS which was infected respectively by H.pylori 26695 and H.pylori 26695 △CagA from 1 hour to 6 hour. Conclusion H.pylori will lead to Ca^2＋ deprivation in AGS cells. CagA can not induce deprivation of intracellular Ca^2＋. The loss of AGS intracellular calcium has no apparent correlation with CagA.