Xenoantigen, an alphaGal epitope-expression construct driven by the hTERT-promoter, specifically kills human...

BACKGROUND: We previously reported the usefulness of the alphaGal epitope as a target molecule for gene therapy against cancer. To induce cancer cell specific transcription of the alphaGal epitope, an expression vector which synthesizes the alphaGal epitope under the control of a promoter region of the human telomerase reverse transcriptase (hTERT), NK7, was constructed. METHODS: NK7 was transfected into a human pancreatic carcinoma cell line, MIA cells, and telomerase-negative SUSM-1 cells served controls. Expression of the alphaGal epitope was confirmed by flow cytometry using IB4 lectin. The susceptibility of transfected MIA cells to human natural antibodies, was examined using a complement-dependent cytotoxic cross-match test (CDC) and a flow cytometry using annexin V. RESULTS: The alphaGal epitope expression was detected only on the cell surfaces of NK7-transfected MIA cells, i.e., not on naive MIA cells or telomerase negative SUSM-1 cells. The CDC results indicated that MIA cells transfected with NK7 are susceptible to human natural antibody-mediated cell killing, and the differences, as compared to NK-7 transfected telomerase negative SUSM-1 cells or telomerase positive naïve MIA cells, were statistically significant. The flow cytometry using annexin V showed a higher number of the apoptotic cells in NK-7 transfected MIA cells than in naïve MIA cells. CONCLUSIONS: The results suggest that alphaGal epitope-expression, under the control of the hTERT-promoter, may be useful in cancer specific gene therapy.