[Adeno-associated virus-mediated gene transfer of endostatin for inhibiting growth and metastasis of human nasopharyngeal carcinoma in nude mice].

OBJECTIVE: To investigate the inhibitory effect on growth and metastasis of human nasopharyngeal carcinoma in nude mice by adeno-associated virus-mediated gene transfer of human endostatin.

METHODS: The infectious efficiency of recombinant adeno-associated virus (rAAV) in vitro was detected. The endostatin expressed in human umbilical vein endothelial cell ECV304 was detected by immunofluorescence staining. MTT was used to assay inhibitory effect of the infecting supernatant of recombinant adeno-associated viral vectors carrying human endostatin gene (rAAV-hEndo)on ECV304 cell. Heterotopic implantation model of human nasopharyngeal carcinoma cell C666-1 in nude mice was established. rAAV-hEndo or rAAV-EGFP or PBS were injected into the tail vein of tumor bearing mice. Three weeks after implantation, the volumes of tumor, inhibition rate, the percentage of lung metastases, microvessel density (MVD) and apoptotic index (AI) were evaluated respectively.

RESULTS: The infectious efficiency of rAAV was 98% in vitro. Immunofluorescence staining showed the humam endostatin protein was expressed mainly in cytoplasm. ECV304 cell proliferation was obviously inhibited by the infecting supernatant of rAAV-hEndo. The inhibitory rate was 67.3% when the supernatant was used 72 h later. Compared with PBS group, the restrained percentage of tumor in hEndo group was 70.7%. The percentage of lung metastases in hEndo group, EGFP group and PBS group was 0.0%, 50.0% and 66.7% respectively. The average MVD of hEndo group (3.67 +/- 1.63) was significantly lower than that of EGFP group (19.67 +/- 2.16) and PBS group (22.50 +/- 3.02) (P < 0.01). The apoptotic index increased significantly in hEndo group(28.83 +/- 5.27)% versus EGFP group (6.17 +/- 2.79)% and PBS group (4.50 +/- 2.17)% (P < 0.01). The survival time of tumor bearing mice in hEndo group (36.50 +/- 8.46) d was significantly longer than EGFP group (24.00 +/- 5.66) d and PBS group (21.17 +/- 3.92) d (P < 0.01).

CONCLUSIONS: The gene transfer of human endostatin mediated by adeno-associate virus can inhibit the growth and metastasis of human nasopharyngeal carcinoma in nude mice effectively. The mechanism may be due to the effect of antiangiogensis and inducement of tumor cell apoptosis.