The eukaryotic vectors VR1012 expressing survivin or 33 tandem repeats of human mucin 1（MUC1）（VNTRs）,namely,VR1012-S and VR1012-VNTR（VNTR=variable number of tandem repeat）,were constructed by cloning survivin and VNTR genes into VR1012,respectively.The eukaryotic vector pEGFP expressing survivin and MUC1 VNTRs fusion gene pEGFP-MS was also constructed.Mouse melanoma cell line（B16） stably expressing survivin and MUC1 VNTRs（MS ＋ B16） was established by Lipofectamine-mediated transfection of pEGFP-MS into B16 cells.EGFP expression in MS ＋ B16 cells was observed using a fluorescent microscope and survivin and MUC1 VNTRs（MS） expression was confirmed by means of Western blot analysis.A syngenic graft tumor model was generated by subcutaneous injection of MS ＋ B16 cells into C57/BL6 mice and tumor size increased rapidly with time in a cell number dependent manner.After the third immunization,mice were challenged subcutaneously with 5×l0 5 MS ＋ B16 cells.Compared with that of the negative control immunized with phosphate-buffered saline（PBS）,a significant reduction of tumor growth was observed in groups immunized with survivin plasmid DNA and MUC1 VNTRs plasmid DNA.Thus,the suppression of subcutaneous tumor was antigen-specific.This model is useful for the development of tumor vaccines targeting survivin and MUCI VNTRs.
Human telomerase reverse transcriptase（hTERT） activity was detected in human nasopharyngeal carcinoma celI（CNE） but not in human normal lung fibroblas t（CCD-11Lu）. Recombinant adenoviruses Ad-CMV-TK-enh and Ad-hTERT-TK-enh were constructed and infected into normal fibroblasts and nasopharyngeal carcinoma cells. Ad-CMV-TK-enh with 100 μmol/L of ganciclovir（GCV） caused 87% of CCD-11Lu cells death and 91% of CNE cells death, Ad-hTERT-TK-enh with 100 μmol/L of GCV caused 24% of CCD-11Lu cells death and 79% of CNE cells death. These results indicate that the Ad-hTERT-TK-enh with GCV may be a useful method in suppressing tumor growth in targeted nasopharyngeal carcinoma gene therapy.
