Expression properties of recombinant pEgr-P16 plasmid in esophageal squamous cell carcinoma induced by ionizing irradiation

AIM: To construct the recombinant pEgr-P16 plasmid for the investigation of its expression properties in esophageal squamous cell carcinoma induced by ionizing irradiation and the feasibility of gene-radiotherapy for esophageal carcinoma.METHODS: The recombinant pEgr-P16 plasmid was constructed and transfected into EC9706 cells with lipofectamine. Western blot, quantitative RT-PCR and flow cytometry were performed to study the expression of pEgr-P16 in EC9706 cells and the biological characteristics of EC9706 cell line after transfection induced by ionizing irradiation.RESULTS: The eukaryotic expression vector pEgr-P16 was successfully constructed and transfected into EC9706 cells.The expression of P16 was significantly increased in the transfected cells after irradiation while the transfected cells were not induced by ionizing irradiation. The induction of apoptosis in transfection plus irradiation group was higher than that in plasmid alone or irradiation alone.CONCLUSION: The combination of pEgr-P16 and irradiation could significantly enhance the P16 expression property and markedly induce apoptosis in EC9706 cells. These results may lay an important experimental basis for gene radiotherapy for esophageal carcinoma.

Anti-tumor effect of pEgr-IFNγgene-radiotherapy in B16 melanoma-bearing mice

AIM: To construct a pEgr-IFNγ Plasmid and to investigate its expression properties of interferon-γ (INF-γ) induced by irradiation and the effect of gene-radiotherapy on the growth of melanoma. METHODS: A recombined plasmid, pEgr-IFNγ, was constructed and transfected into B16 cell line with lipofectamine. The expression properties of pEgr-IFNγ were investigated by ELISA. Then, a B16 melanoma-bearing model was established in mice, and the plasmid wasinjected into the tumor tissue. The tumor received 20 Gy X-ray irradiation 36 h after injection, and IFN-γ expression was detected from the tumor tissue. A tumor growth curve at different time points was determined. RESULTS: The eukaryotic expression vector, pEgr-IFNγ, was successfully constructed and transfected into B16 cells. IFN-γ expression was significantly increased in transfected cells after X-ray irradiation in comparison with 0 Gy group (77.73-94.60 pg/mL, P<0.05-0.001), and was significantly higher at 4 h and 6 h than that of control group after 2 Gy X-ray irradiation (78.90-90.00 pg/mL, P<0.01-0.001).When the transfected cells were given 2 Gy irradiation 5 times at an interval of 24 h, IFN-y expression decreased in a time-dependent manner. From d 3 to d 15 after IFNγ generadiotherapy, the tumor growth was significantly slower than that after irradiation or gene therapy alone. CONCLUSION: The anti-tumor effect of pEgr-IFNγ generadiotherapy is better than that of genebherapy or radiotherapy alone for melanoma. These results may establish an important experimental basis for gene-radiotherapy of cancer.

Construction of pETNF-P16 plasmid and its expression properties in EC9706 cell line induced by X-ray irradiation

AIM: Recombined plasmid pETNF-P16 was constructed to investigate its expression properties in esophageal squamous carcinoma cell line EC9706 induced by X-ray irradiation and the feasibility of gene-radiotherapy for esophageal carcinoma. METHODS: Recombined plasmid pETNF-P16 was constructed and transfected into EC9706 cells with lipofectamine. ELISA,Western blot, and immunocytochemistry were performedto determine the expression properties of pETNF-P16 in EC9706 after transfection induced by X-ray irradiation. RESULTS: Eukaryotic expression vector pETNF-P16 was successfully constructed and transfected into EC9706 cells. TNFα expressions were significantly increased in the transfected cells after different doses of X-ray irradiation than in those after 0Gy irradiation (1 192.330-2 026.518 pg/mL,P<0.05-0.01), and the TNFα expressions and P16 were significantly higher 6-48 h after 2 Gy X-ray irradiation (358.963-585.571 pg/mL, P<0.05-0.001). No P16 expression was detected in normal EC9706 cells. However, there was strong expression in the transfected and irradiation groups. CONCLUSION: X-ray irradiation induction could significantly enhance TNFα and P16 expression in EC9706 cells transfected with pETNF-P16 plasmid. These results may provide important experimental data and therapeutic potential for gene-radiotherapy of esophageal carcinoma.