重组腺相关病毒介导caveolin-1基因表达抑制肝癌新生血管形成的实验研究

Recombined adeno-associated viral vector-mediated systemic delivery of caveolin-1 inhibits angiogenesis of implanted hepatocellular tumor in vivo

目的 探讨caveolin-1参与肝细胞癌血管生成及影响血管通透性的作用机制.方法 构建肝癌细胞系HepG2裸鼠皮下移植瘤模型,局部注射编码重组可溶性caveolin-1蛋白的重组腺相关病毒载体rAAV-PEG-caveolin-1,观察其对肝癌细胞生长的抑制作用;通过肿瘤微血管密度（microvessel density,MVD）检测肿瘤新生血管的生成;Western blot检测脉管标志蛋白PECAM-1表达改变;FITC标记右旋糖苷测定肿瘤微血管通透性;放射强度测定法检测肝癌组织中eNOS活性,TUNEL法检测caveolin-1对肿瘤细胞的诱导凋亡效应.结果 rAAV-PEG-caveolin-1转染组治疗第14天后,移植瘤的瘤重较对照组和空载体转染组有不同程度的减小（P＜O.05）;免疫组化分析及Western blot结果显示rAAV-PEG-caveolin-1转染组较对照组及空载体组MVD及PECAM-1表达显著减少（P＜0.05）;FITC-右旋糖苷测定表明rAAV-PEG-caveolin-1可有效降低肿瘤微血管通透性;rAAV-PEG-caveolin-1转染组较对照组及空载体组eNOS活性明显下降（P＜0.05）;TUNEL分析显示rAAV-PEG-caveolin-1可诱导肿瘤细胞凋亡.结论 Caveolin-1是血管生成调节的关键分子,能显著抑制肿瘤新生血管的形成,并能有效降低肿瘤微血管的通透性.

Objective To investigate the antitumor effect of the recombined adeno-associated virus encoding caveolin-1 regulated by progression-elevated gene （PEG） promotor on the angiogenesis of implanted human hepatocellular carcinoma（HCC） cell lines in a nude mouse model. Methods HepG2 cells were inoculated subcutaneously into NOD/SCID mice, and animals were treated with rAAV-PEG-caveolin-1 after tumor cell innoculation. The fluorescence ratio of Evans blue to FITC-dextran was used to assess the changes of microvasculature permeability of the tumor. Western blot and immunohistochemical analyses were employed to detect PECAM-1 expression in tumor microvascular endothelium and microvessel density（MVD）, respectively; NOS activity was assessed by citrulline generation. Tumor growth was observed and tumor cell apoptosis in tumor tissues were measured by TUNEL. Results Tumor growth was significantly inhibited in mice injected with rAAV-PEG-caveolin-1. The administration of rAAV-PEG-caveolin-1 significantly blocked vascular leakage in the tumor microcirculation. The levels of PECAM-1 protein detected by Western blot were markedly reduced in rAAV-PEG-caveolin-1-treated mice, and there were fewer MVD in tumors from caveolin-1-treated mice, while NOS catalytic activity was much lower in rAAV-PEG-caveolin-1-treated mice compared to the control and empty vector-treated animals. TUNEL demonstrated significant induction of tumor cell specific apoptosis. Conclusions rAAV-PEG-caveolin-1 can reduce tumor progression through blocking microvascular formation by inhibiting eNOS.