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AIM:To determine whether SP-TAT-apoptin induces apoptosis and also maintains its tumor cell specificity. METHODS:In this study,we designed a secretory protein by adding a secretory signal peptide(SP) to the N terminus of Transactivating Transcription(TAT)-apoptin(SP-TAT-apoptin),to test the hypothesis that it gains an additive bystander effect as an anti-cancer therapy. We used an artificial human secretory SP whose amino acid sequence and corresponding cDNA sequence were generated by the SP hidden Markov model. RESULTS:In human liver carcinoma HepG2 cells,SP-TAT-apoptin expression showed a diffuse pattern in the early phase after transfection. After 48 h,however,it translocated into the nuclear compartment and caused massive apoptotic cell death,as determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT) assay and annexin-V binding assay. SP-TAT-apoptin did not,however,cause any cell death in non-malignant human umbilical vein endothelial cells(HUVECs). Most importantly,the conditioned medium from Chinese hamster ovary(CHO) cells transfected with SP-TAT-apoptin also induced significant cell deathin HepG2 cells,but not in HUVECs. CONCLUSION:The data demonstrated that SP-TAT-apoptin induces apoptosis only in malignant cells,and its secretory property might greatly increase its potency once it is delivered in vivo for cancer therapy.
AIM: To determine whether SP-TAT-apoptin induces apoptosis and also maintains its tumor cell specificity. METHODS: In this study, we designed a secretory protein by adding a secretory signal peptide (SP) to the N terminus of Transactivating Transcription (TAT) -apoptin (SP-TAT-apoptin), to test the hypothesis that it gains an additive bystander effect as an anti-cancer therapy. We used an artificial human secretory SP whose amino acid sequence and corresponding cDNA sequence were generated by the SP hidden Markov model. RESULTS: In human liver carcinoma HepG2 cells, SP-TAT-apoptin expression showed a diffuse pattern in the early phase after transfection. After 48 h, however, it translocated into the nuclear compartment and caused massivewalotic cell death, as determined by SP-TAT-apoptin did not, however, cause any cell death in non-malignant human umbilical vein endothelial cells (HUVECs). Most imp ortantly, the conditioned medium from Chinese hamster ovary (CHO) cells transfected with SP-TAT-apoptin also induced significant cell death in HepG2 cells, but not in HUVECs. CONCLUSION: The data demonstrated that SP-TAT-apoptin induces apoptosis in in malignant cells , and its secretory property might greatly increase its potency once it is delivered in vivo for cancer therapy.