BACKGROUND: Bax is a strong pro-apoptotic gene that induces programmed cell death when expressed. Human telomerase reverse transcriptase (hTERT) is the catalytic subunit for telomerase, an enzyme found to be active in more than 85% of human cancers. Recently, a binary adenoviral system (Ad/GT-Bax + Ad/hTERT-GV16) was constructed using the hTERT promoter to induce Bax gene expression in tumor cells. METHODS: To test whether human pancreatic tumor cells would respond to this system of Bax-induced apoptosis, we compared the effects of Bax gene induction with that of LacZ gene induction using the same binary system. RESULTS: Lysates of the human pancreatic cell lines PANC-28, MIA PaCa-2, and BxPC-3 showed significantly elevated levels of human telomerase using the PCR-based TRAP assay. As early as 24 h after treatment with Bax-induction gene therapy, growth inhibition was observed. Overexpression of the Bax protein was confirmed by Western blotting. Extensive apoptosis on FACS analysis at 48 h was seen after Bax induction. In addition, cytosolic cytochrome c levels increased compared to mitochondrial levels after Bax induction. Levels of caspase-3, a key downstream enzyme involved in apoptosis, also increased significantly compared to controls after treatment. None of these effects were seen with LacZ. CONCLUSION: Our results suggest that the binary adenoviral vector system, Ad/GT-Bax + Ad/hTERT-GV16, induces high levels of Bax expression that induce apoptosis in human pancreatic cancer cells.
BACKGROUND:Bax is a strong pro-apoptotic gene that induces programmed cell death when expressed. Human telomerase reverse transcriptase (hTERT) is the catalytic subunit for telomerase, an enzyme found to be active in more than 85% of humancancers. Recently, a binary adenoviral system (Ad/GT-Bax + Ad/hTERT-GV16) was constructed using the hTERT promoter to induce Bax gene expression in tumor cells. METHODS: To test whether humanpancreatic tumor cells would respond to this system of Bax-induced apoptosis, we compared the effects of Bax gene induction with that of LacZ gene induction using the same binary system. RESULTS: Lysates of the humanpancreatic cell lines PANC-28, MIA PaCa-2, and BxPC-3 showed significantly elevated levels of human telomerase using the PCR-based TRAP assay. As early as 24 h after treatment with Bax-induction gene therapy, growth inhibition was observed. Overexpression of the Bax protein was confirmed by Western blotting. Extensive apoptosis on FACS analysis at 48 h was seen after Bax induction. In addition, cytosolic cytochrome c levels increased compared to mitochondrial levels after Bax induction. Levels of caspase-3, a key downstream enzyme involved in apoptosis, also increased significantly compared to controls after treatment. None of these effects were seen with LacZ. CONCLUSION: Our results suggest that the binary adenoviral vector system, Ad/GT-Bax + Ad/hTERT-GV16, induces high levels of Bax expression that induce apoptosis in humanpancreatic cancer cells.