Bax-induction gene therapy of pancreatic cancer.
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.


CONCLUSIONS
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.
Pirocanac
Elissa C
EC
Department of Surgery, University of California at San Diego, 92161, USA.
Nassirpour
Rounak
R
Yang
Meng
M
Wang
Jinwei
J
Nardin
Stephanie R
SR
Gu
Jian
J
Fang
Bingliang
B
Moossa
A R
AR
Hoffman
Robert M
RM
Bouvet
Michael
M
D017209:Apoptosis / Q000235:genetics / Q000502:physiology; D015870:Gene Expression; D015316:Genetic Therapy; D006801:Humans; D007763:Lac Operon; D010190:Pancreatic Neoplasms / Q000201:enzymology / Q000503:physiopathology / Q000628:therapy*; D011518:Proto-Oncogene Proteins / Q000235:genetics* / Q000502:physiology; D019253:Proto-Oncogene Proteins c-bcl-2; D019098:Telomerase / Q000378:metabolism; D014407:Tumor Cells, Cultured; D051028:bcl-2-Associated X Protein
C494826:BAX protein, human; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D019098:Telomerase