Enhanced Effects of TRAIL-endostatin-based Double-gene-radiotherapy on Suppressing Growth, Promoting Apoptosis and Inducing Cell Cycle Arrest in Vascular Endothelial Cells

This study examined the effects of TRAIL-endostatin-based gene-radiotherapy on cellu-lar growth, apoptosis and cell cycle progression in human vascular endothelial cells ECV304 in vitro. The expression of TRAIL and endostatin protein in ECV304 cells was detected by ELISA after the transfection of recombinant plasmid pshuttle-Egr1-shTRAIL-shES and X-ray irradiation. Then MTT assay was used for determining the cellular proliferation, and flow cytometry (FCM) plus Annexin V and propidium iodide (PI) double-staining or PI single-staining were employed for the detection of apoptosis and cell cycle progression. The results showed that expression of TRAIL and endostatin protein exhibited a time- and dose-dependent change in ECV304 cells after pshut-tle-Egr1-shTRAIL-shES transfection in conjunction with irradiation. In the TRAIL-endostatin-based single- or double-gene-radiotherapy, the cell viability declined in a time- and dose-dependent manner, the percentage of cells at G2/M phase and apoptotic rate was increased, and the percentage of cells at G0/G1 phase was lowered as compared with those receiving radiotherapy alone. Moreover, TRAIL-endostatin-based double-gene-radiotherapy demonstrated better effects on growth inhibition, promotion of apoptosis and induction of cell cycle arrest in ECV304 cells than single-gene-radiotherapy.

Anti-tumor effect of pEgr-interferon-γ-endostatin gene-radiotherapy in mice bearing Lewis lung carcinoma and its mechanism

Background Gene-radiotherapy, the combination of gene therapy and radiation therapy, is a new paradigm for cancer treatment. To enhance anti-tumor effect of gene-radiotherapy, in this study we construct a radiation-inducible dual-gene co-expression vector pEgr-interferon(IFN)-γ- endostatin and studied the anti-tumor effect of pEgr-IFN-γ-endostatin gene-radiotherapy in mice bearing Lewis lung carcinoma and its mechanism.Methods Gene recombinant technique was used to construct dual-gene co-expression plasmid pEgr-IFN-γ-endostatin, and single-gene expression plasmid pEgr-IFN-γ and pEgr-endostatin. The plasmids packed by liposome were injected locally into the tumors of the mice, and the tumors were irradiated with 5 Gy X-ray 36 hours later. The tumor growth rate at different time and mean survival period of the mice were observed. Cytotoxic activity of splenic cytotoxic T-lymphocyte (CTL), natural killer (NK) cell and tumor necrosis factor (TNF)-α secretion activity of peritoneal macrophages of the mice in various groups were evaluated 15 days after irradiation. The intratumor micro-vessel density was evaluated by immunohistochemical staining 10 days after irradiation.Results The tumor growth rate of the mice in dual-gene-radiotherapy group was significantly lower than those in control group, 5 Gy group and single-gene-radiotherapy group at different time after gene-radiotherapy, and the mean survival period of which was longer. Cytotoxic activity of splenic CTL, NK and TNF-α secretion activity of peritoneal macrophages of the mice in dual-gene-radiotherapy group were significantly higher than those in control group, 5 Gy X-ray irradiation group and pEgr-endostatin gene-radiotherapy group 15 days after irradiation. The intratumor micro-vessel density of the mice in dual-gene-radiotherapy group was significantly lower than those in control group, 5 Gy X-ray irradiation group and pEgr-IFN-γgene-radiotherapy group. Conclusion The anti-tumor effect of dual-gene-radiotherapy was significantly better than that of single-gene-radiotherapy by combining the enhancement of anti-tumor immunologic function induced by IFN-γ with the anti-angiogenesis function of endostatin.