Anti-tumor effects of pEgr-1-endostatin-TNF-α recombinant plasmid expression induced by ionizing radiation.

Purpose: The aim of the present study was to investigate the anti-tumor effect of a pEgr-1-endostatin-TNF-α recombinant plasmid induced by ionizing radiation. Method: Three hundred and twenty mice bearing Lewis lung carcinomas were divided into four experimental groups: blank control, irradiation treatment, plasmid treatment and plasmid combined irradiation treatment. Twenty-four hours after the recombinant plasmid was injected locally into the tumors of the mice, they were irradiated with 10 Gy γ-rays. The concentration of TNF-α and endostatin in the serum of mice was measured by ELISA and tumor growth in each group was compared. The tumor microvessel density was examined by H&E staining and immunohistochemistry analysis of CD31 positive cells. Results: Radiation could induce the expression of pEgr-1-endostatin-TNFα. The levels of endostatin and TNF-α could express steadily for about 4 weeks, with concentrations of 52.6±4.19 and 12.0±0.87 ng/ml respectively, in the second week in combined therapy group and maintained at relative higher level in the fourth week than other groups (F=29.7, P<0.05). Compared with the control group, the tumor micro vessel density was significantly depressed (P<0.05) and tumor growth was significantly inhibited (5907.2±78.6 mm3 vs. 763.5±12.3 mm3, P <0.05). Conclusions: The expression of pEgr-1-endostatin-TNF-α could be induced in mice in vivo and exhibited more significant anti-tumor and anti-angiogenesis effects than irradiation alone.