Effect of pEgr-TNFalpha gene radiotherapy on mice melanoma

In the present study, we constructed a pEgr-tumour necrosis factor-alpha (TNFalpha) plasmid and investigated its expression properties in B16 cells on exposure to ionizing irradiation and, furthermore, the effect of gene radiotherapy on a melanoma model. Firstly, the recombinant pEgr-TNFalpha plasmid was constructed and transfected into B16 cells with liposomes to investigate its expression properties on exposure to X-irradiation. The melanoma-bearing model was then established and the tumour tissue was injected locally with the pEgr-TNFalpha plasmid and exposed to 20 Gy of X-irradiation. The tumour growth curve at different time points was described. At day 3, TNFalpha transcription in the tumour tissue was detected by reverse transcriptase-polymerase chain reaction (RT-PCR). The results showed that: (1) the eukaryotic expression vector pEgr-TNFalpha was successfully constructed and transfected into B16 cells; (2) TNFalpha expression was significantly increased in the transfected cells after X-irradiation, in contrast with that of the pCMV-TNFalpha group or the pEgr-TNFalpha group that received 0 Gy of irradiation; (3) after pEgr-TNFalpha gene radiotherapy, tumour growth was significantly slower than in those groups receiving irradiation or gene transfer alone. The TNFalpha concentration in the peripheral blood of tumour-bearing mice that received an injection of pEgr-TNFalpha and 20 Gy of irradiation was higher than that of the control group. Only in pEgr-TNFalpha and pEgr-TNFalpha + 20 Gy groups was TNFalpha messenger RNA (mRNA) detected in the tumour tissue. We conclude that pEgr-TNFalpha gene radiotherapy may significantly inhibit tumour growth, and that the anti-melanoma effect is superior to that of either gene therapy or radiotherapy alone. Our work provides the theoretical basis for further study on the gene radiotherapy of this tumour.