幽门螺杆菌细胞毒素相关蛋白A对人胃腺癌上皮AGS细胞蛋白质组的影响

为明确幽门螺杆菌细胞毒素相关蛋白A(CagA)在致病过程中对宿主细胞蛋白质表达的影响及其与CagA磷酸化的相关性,分别用野生型cagA质粒和磷酸化位点突变型cagA质粒转染人胃腺癌上皮AGS细胞,应用表面加强激光解析电离-飞行时间质谱技术,分析细胞蛋白质组的改变。结果表明,在可捕获的400多个蛋白质中,野生型CagA可使AGS细胞质荷比为4229、4714、4728、5129、6546、6657、8162、9084、13803、14021的10个蛋白质表达上调,质荷比为2013、4286、8563、9952、11085、11645的6个蛋白质表达下调。突变型CagA只能使质荷比为4714、4728、6546和6657的蛋白质表达上调。这些结果提示,这16个差异表达蛋白质可能参与了CagA的致病过程,其中质荷比为4714、4728、6546和6657蛋白质表达的改变与CagA的磷酸化作用无关,而其余12个蛋白质表达的改变则都依赖于CagAEPIYA重复序列酪氨酸位点的磷酸化。这些发现为进一步探讨CagA的致病机制提供了实验依据。

Proteomic Analysis of Human Gastric Adenocarcinoma Epithelial AGS Cells Following Transfection of Helicobacter pylori Cytotoxin-associated Gene A

Helicobacter pylori (Hp) cytotoxin-associated protein A (CagA) is closely associated with gastritis, peptic ulcer and gastric carcinoma. Tyrosine-phosphorylation of C-terminal region repeat sequence(s) is considered playing an important role in the biological function of CagA. To identify the host cell proteins involved in CagA induced pathogenesis and investigate whether the changes of protein expression depend on the tyrosine- phosphorylation of CagA, protein expression profiles were analyzed in human gastric adenocarcinoma epithelial AGS cells transfected with wild type cagA and phosphorylation site mutant cagA using ProteinChips and surface enhanced laser desorption/Ionization time-of-flight mass spectrometry (SELDI-TOF-MS) proteomics technology. The profiles showed the expression level of 10 proteins at mass/charge ratios (m/z) of 4 229, 4 714, 4 728, 5 129, 6 546, 6 657, 8 162, 9 084, 13 803, 14 021 were up-regulated while 6 proteins at m/z of 2 013, 4 286, 8 563, 9 952, 11 085, 11 645 were down-regulated after wild type cagA transfection, indicating that these 16 proteins might have relationships with CagA induced pathogenesis. Besides, only 4 proteins at m/z of 4 714, 4 728, 6 546, 6 656 among the 16 proteins mentioned above were found up-regulated after mutant cagA transfection, suggesting these expres- sion changes were independent of the tyrosine-phosphorylation of CagA while the changes of other 12 proteins were dependent of the tyrosine-phosphorylation of CagA. These results may provide new targets for further understand- ing of the biological function and pathogenesis of CagA.