Helicobacter pylori induces cancer cell motility independent of the c-Met receptor.
Helicobacter pylori induces cancer cell motility independent of the c-Met receptor.
复制标题
幽门螺杆菌幽门螺杆菌诱导与C-MET受体无关的癌细胞运动。
DOI：
10.4103/1477-3163.50892
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发表时间：
2009
影响因子：
--
通讯作者：
Cardelli JA
中科院分区：
文献类型：
--
作者：
Snider JL;Cardelli JA
肝细胞生长因子(HGF)受体c-Met与晚期癌症进展和患者预后不良密切相关。幽门螺杆菌(H.Pylori)是最近提出的一种胃部病原体，它依赖于c-Met与细菌CagA蛋白的相互作用来刺激c-Met的磷酸化，而CagA蛋白是Hp诱导的癌细胞运动和侵袭所必需的。在本报告中，我们使用短发夹RNA(ShRNA)、识别离散c-Met残基磷酸化的抗体的Western印迹分析和免疫荧光显微镜来研究CagA-c-Met的相互作用。数据显示，shRNA介导的c-Met基因敲除并不降低幽门螺杆菌诱导的细胞运动，这表明c-Met不是运动所必需的。令人惊讶的是，c-Met基因敲除并没有降低被磷酸化-c-Met抗体识别的幽门螺杆菌诱导蛋白的水平。这个125kD的蛋白比c-Met小10kD，这表明H.Pylori不能磷酸化c-Met，而是与另一种蛋白发生交叉反应。当c-Met磷酸化抑制剂不降低细菌诱导的125kD蛋白水平，c-Met免疫沉淀(IP)不能从Hp处理的裂解物中检测到125kD蛋白时，这一假说得到证实。该蛋白被鉴定为抗体与磷酸化的CagA交叉反应的产物。我们还证实了CagA与c-Met相互作用，但这种相互作用可能导致了前人将磷酸化的CagA误解为c-Met的磷酸化。最后，蛋白酶体抑制剂lactacystin可延长HGF诱导的c-Met的磷酸化时间，并促进CagA阴性的幽门螺杆菌刺激AGS细胞的运动，提示持续的c-Met磷酸化可以补偿CagA依赖信号的丢失。这些数据表明，幽门螺杆菌刺激癌细胞的运动不依赖于c-Met受体。我们进一步推测，尽管幽门螺杆菌不以c-Met为靶点，但细菌仍可能利用c-Met效应信号来刺激CagA非依赖性癌细胞的运动，这可能为Hp依赖的胃癌进展提供了进一步的机制。
The hepatocyte growth factor (HGF) receptor, c-Met, is strongly implicated in late-stage cancer progression and poor patient prognosis. The stomach pathogen, Helicobacter pylori (H. pylori), was recently proposed to stimulate c-Met phosphorylation dependent upon interaction of c-Met with the bacterial CagA protein required for H. pylori-induced cancer cell motility and invasion. In this report, we employed short hairpin RNA (shRNA), western blot analysis using antibodies recognizing phosphorylation at discrete c-Met residues, and immunofluorescence microscopy to investigate the CagA-c-Met interaction. The data showed that shRNA-mediated c-Met knockdown did not reduce H. pylori-induced cell motility, suggesting that c-Met was not required for motility. Surprisingly, c-Met knockdown did not reduce the level of an H. pylori-induced protein recognized by a phospho-c-Met antibody. This 125 kD protein was 10 kD smaller than c-Met, suggesting that H. pylori did not phosphorylate c-Met but cross-reacted with another protein. This hypothesis was confirmed when c-Met phosphorylation inhibitors did not lower the levels of the bacteria-induced 125 kD protein, and c-Met immunoprecipitation (IP) did not detect this 125 kD protein from H. pylori-treated lysates. This protein was identified as a product of antibody cross reactivity with phosphorylated CagA. We also confirmed that CagA interacts with c-Met, but this interaction may have caused previous authors to misinterpret phosphorylated CagA as c-Met phosphorylation. Finally, pretreatment with the proteasomal inhibitor, lactacystin, caused prolonged HGF-induced c-Met phosphorylation and facilitated a CagA-negative H. pylori to stimulate AGS cell motility, suggesting that sustained c-Met phosphorylation compensates for the loss of CagA-dependent signaling. These data demonstrate that H. pylori stimulates cancer cell motility independent of the c-Met receptor. We further hypothesize that although H. pylori does not target c-Met, the bacteria may still utilize c-Met effector signaling to stimulate CagA-independent cancer cell motility, which may provide a further mechanism of H. pylori-dependent gastric cancer progression.