辐射诱导启动子介导的腺病毒自杀基因联合照射的抗肿瘤效应

Anti-tumor effect of adenovirus-mediated suicide gene therapy under control of tumor-specific and radio-inducible chimeric promoter in combination with γ-ray irradiation in vivo

目的检测利用肿瘤特异性辐射诱导嵌合启动子介导的腺病毒自杀基因系统联合放射线对肝癌细胞裸鼠皮下移植瘤生长的抑制作用。方法构建含有6个串联放射反应元件的人端粒酶反转录酶基因嵌合启动子调控辣根过氧化物酶表达的复制缺陷型腺病毒，同时建立人肝癌细胞MHCC97裸鼠皮下移植瘤模型，瘤内注射重组腺病毒，腹腔注射吲哚乙酸，同时给予叮射线照射，观察肿瘤生长、裸鼠生存状态，以及肿瘤组织和正常器官的组织病理学改变。结果分组处理后第31天，阴性对照病毒组、单纯病毒组、单纯照射组及联合组裸鼠皮下移植瘤相对体积分别为49．23±4．55、27．71±7．74、28．53±10．48和．11．58±3．23，组间差异具有统计学意义（F=16．288，P〈0．01），其中联合组的肿瘤抑制作用最强，生长抑制率为76．5％；与对照组相比，非对照组均能延长裸鼠中位生存期（r=18．307，P〈0．01），其中联合组差异最显著（13d与43d）；光镜下各治疗组肿瘤组织均出现坏死，其中联合组肿瘤坏死较多，而正常器官组织病理学检查未发现治疗相关损伤改变。对照组裸鼠肝脏显示出密集的肝癌转移灶，单纯治疗组仅有少数转移灶，而联合组肝脏未见明显异常。结论复制缺陷型腺病毒介导的靶向自杀基因治疗联合放疗能有效抑制肝癌皮下移植瘤生长，延长裸鼠生存期，为肝癌的治疗提供了新的途径，具有良好的应用前景。

Objective To detect the selective inhibitory effeets of irradiation plus adcnovirus- mediated horseradish peroxidase （HRP）/indole-3-acetic acid （IAA） suicide gone system using tumor- speeifie and radio-inducible chimeric promoter on human hepatoeellular carcinoma subcutaneously xenografted in nude mouse. Methods Recombinant replicated-deficient adenovirus vector containing HRP gene and chimeric human telomerase reverse transeriptase （hTERT） promoter carrying 6 radio- inducible CArG elements was constructed. A human subcutaneous transplanting hepatocellular carcinoma （MHCC97 cell line） model was treated with ＂/-ray irradiation plus intra-tumor injections of adenoviral vector and intra-peritoneal injections of prodrug IAA. The change of tumor volume and tumor growth inhibiting rate, the survival time of nude mice, as well as histopathology of xenograft tumor and normal tissues were evaluated. Results Thirty one days after the treatment, the relative tumor volumes in the negative, adenovirus therapy, irradiation, and combination groups were 49.23±4.55, 27.71 ±7.74, 28.53±10.48 and 11.58 ± 3.23,respectively. There was a significantly statistical difference among them （F=16. 288,P〈0.01）. The inhibition effect in the combination group was strongest as compared with that in other groups, and its inhibition ratio was 76.5%. The survival period extended to 43 d in the combination group, which showed a significantly difference with that in the control group（x2 = 18. 307 ,P 〈 0.01 ）. The area of tumors necrosis in the combination group was larger than that in the other groups, and the normal tissues showed no treatment-related toxic effect in all groups. However, multiple hepatocellular carcinoma metastases were observed in the liver in the control group, there were a few metastases in the monotherapy groups and no metastasis in the combination group. Conclusions Adenovirus-mediated suicide gene therapy plus radiotherapy dramatically could inhibit tumor growth and prolong median survival time. It might provide a promising therapeutic modality for hepatocellular carcinoma therapy.