PTEN下调FAK磷酸化来抑制EGFR受体突变体引起的胶质瘤细胞侵袭

PTEN inhibited the invasion of glioma cells with a common mutant epidermal growth factor receptor expression by dephosphorylating FAK

背景与目的:抑癌基因PTEN在胶质瘤中突变率达20%～40%,且PTEN缺失和表皮生长因子受体突变体EGFRvⅢ同时存在EGFR表达的胶质瘤组织中。PTEN通过直接与FAK作用从而降低其酪氨酸磷酸化来抑制肿瘤细胞侵袭。EGFRvⅢ表达,PTEN缺失都是肿瘤细胞侵袭性增加的原因之一。PTEN功能的丧失可能是EGFRvⅢ表达的肿瘤进一步发展成恶性侵袭性肿瘤的原因之一。本文将探讨在EGFRvⅢ表达和PTEN缺失的肿瘤细胞中转入PTEN以观察其是否能抑制EGFRvⅢ所引起的肿瘤细胞的侵袭。方法:将野生型PTEN及其突变体分别导入人胶质瘤细胞U87ΔEGFR中,利用Transwell-细胞侵袭实验观察细胞侵袭运动变化;免疫印迹实验检查FAK磷酸化变化;FAK表达载体来转染FAK磷酸化程度低的U87ΔEGFR-wtPTEN细胞,观察细胞侵袭运动变化。结果:PTEN和PTEN(G129E)能够抑制U87ΔEGFR细胞侵袭,并且下调FAK397位点磷酸化水平。U87ΔEGFR-wtPTEN细胞中FAK397位点磷酸化水平增加伴随着细胞侵袭能力的提高。结论:PTEN可能通过下调FAK397位点磷酸化水平来抑制EGFRvⅢ引起的胶质瘤细胞侵袭。

Background and purpose： PTEN mutation has been found in 20% -40% of malignant gliomas. The common mutant epidermal growth factor receptor（ EGFR v Ⅲ） was reported to coexpress in PTEN-deficient EGFR-expressing tumor. PTEN has been shown to interact directly with FAK and reduce its tyrosine phosphorylation levels to inhibit cell invasion. The invasion of glioma cells with EGFRvⅢ expression and PTEN deficiency is increased. This study was to observe whether PTEN inhibits glioma cell invasion even in the presence of strong pro-invasive signals provided by constitutive EGFR activity. Methods： U87AEGFR cells were transfected with pcDNA3.1 constructs encoding PTEN and the cells invasion levels were detected by transwell invasion assay. The expression of FAK was detected by immunoblotting. FAK expression vector was transfected into U87AEGFR-wtPTEN cells and the change of cells invasion was documented. Results： PTEN and PTEN （Gl29E） could inhibit cell invasion induced by EGFRv IlI. PTEN and PTEN （G129E） could decrease the FAK phosphorylation at Tyr397. Over expression of FAK in U87AEGFR-PTEN abrogated PTEN-induced down-regulation of the phosphorylation status of FAK and rescued cell invasion. Conclusions： PTEN could inhibit cell invasion induced by EGFRv Ⅲ by dephosphorylating FAK.