FAK对VEGF诱导小鼠肺血管内皮通透性升高作用研究

Role of FAK in the process of VEGF induced pulmonary vascular endothelial permeability in mice

目的黏附斑激酶(FAK)是由细胞因子激活的一种细胞质酪氨酸激酶,对细胞增殖、迁移及血管通透性起重要调控作用。本研究探讨FAK在肿瘤细胞分泌的血管内皮生长因子(VEGF)诱导肺血管内皮细胞通透性升高过程中的作用机制。方法将4T1细胞(小鼠乳腺癌细胞系)接种至Balb/c小鼠乳腺部位建立乳腺癌实验动物模型。选取鼠龄、质量大致相同的小鼠分为荷瘤组(4T1组,n=6)、空白对照组(PBS组,n=6)和贝伐珠单抗治疗组(BEVA组,n=6),测定小鼠肺组织的湿干质量比,评价肺水肿和肺组织血管通透性。ELISA法检测血清VEGF水平,免疫组织化学法检测肺组织中FAK的表达。结果对照组小鼠肺组织湿干质量比为3.13±0.24,4T1组为4.25±0.33,4T1组比对照组明显升高,差异有统计学意义,P<0.05。对照组小鼠血清VEGF水平为(10.65±3.97)pg/mL,4T1组为(119.11±60.52)pg/mL,4T1组比对照组明显升高,差异有统计学意义,P<0.05。免疫组化检测结果显示,在小鼠肺组织中,FAK主要定位于肺血管内皮细胞的细胞质,肺上皮细胞也有表达。FAK在4T1组小鼠肺组织中呈弥漫性表达,表达水平高于对照组。VEGF阻断剂贝伐珠单抗处理荷瘤小鼠,BEVA治疗组小鼠肺水肿减轻,肺组织湿干质量比为3.42±0.39,较4T1组(4.25±0.33)明显下降,差异有统计学意义,P<0.05。BEVA治疗组小鼠肺组织中FAK表达明显降低。结论原发肿瘤分泌的VEGF可诱导肺组织血管通透性升高,诱发肺水肿,其发生机制可能与血管内皮细胞FAK的活化表达相关。

Objective Focal adhesion kinase(FAK)is a cytoplasmic tyrosine kinase activated by cytokinehs and plays an important role in regulating cell proliferation,migration and vascular permeability.The purpose of this study is to investigate the molecular mechanism of FAK in pulmonary hyperpermeabilty induced by vascular endothelial growth factor(VEGF)secreted by primary tumor.Methods Murine breast cancer cells 4T1 were transplanted subcutaneously in mice to construct the xenograft tumor model.Mice with roughly the same age and quality were divided into tumor-bearing group(4T1 group,n=6),blank control group(PBS group,n=6)and bevacizumab treatment group(Beva group,n=6).Pulmonary edema and vascular permeability of lung tissue were assessed by measuring the wet-to-dry(W/D)ratio of lung tissue.Serum VEGF level was detected by ELISA,and the expression of FAK in lung tissue was examined by immunohistochemistry.Results Compared with lung W/D(3.13±0.24)and serum VEGF level(10.65±3.97)pg/ml of the control group,lung W/D(4.25±0.33)and serum VEGF level(119.11±60.52)pg/ml in 4T1 tumor-bearing mice were significantly greater(P<0.05).Immunohistochemistry showed that FAK was mainly localized in the cytoplasm of pulmonary vascular endothelial cells and was also expressed in lung epithelial cells.FAK was diffusely expression in lung tissue of 4T1 tumor bearing mice while sporadically expressed in that of control group.FAK expression was remarkably increased in 4T1 tumor-bearing mice.These increases induced by VEGF could be counteracted by BEVA,a VEGF antibody.The pulmonary edema of mice in the BEVA group was alleviated,lung W/D(3.42±0.39)was significantly lower than that in the 4T1 group(P<0.05),and the expression of FAK in lung tissue was significantly decreased.Conclusion These findings demonstrated that VEGF might induce lung highpermeability through the FAK pathway.