ADENOVIRAL-MEDIATED GENE-TRANSFER OF A CONSTITUTIVELY ACTIVE RETINOBLASTOMA GENE INHIBITS HUMAN PANCREATIC TUMOR-CELL PROLIFERATION

Background, The development of pancreatic cancer involves an accumulat ion of genetic changes, including oncogene activation and mutations in tumor suppressor genes important in cell cycle regulation, iis a step to developing gene therapies to restore cell cycle control, we hypoth esized that adenoviral-mediated gene transfer of a constitutively acti ve, nonphosphorylatable form of the retinoblastoma gene (AdRb) would i nhibit human pancreatic tumor cell proliferation. Methods. Transfectio n efficiency was assessed by beta-gal staining with an adenovirus expr essing the beta-galactosidase gene (AdLacZ). The effect of AdRb on DNA synthesis in pancreatic cancer cell lines was determined by tritiated thymidine incorporation. Western blotting with an antihemagglutinin a ntibody directed to the hemagglutinin-tagged AdRb construct was prefor med to confirm transfection of pancreatic cancer cells. Apoptosis was evaluated with a TUNEL assay. Results. Efficient transfection of human pancreatic cancer cell lines was achieved with AdLacZ. AdRb inhibited tritiated thymidine uptake in the cancer cell lines BxPC-3, MIA PaCa- 2 and PANC-1. Western blotting confirmed transfection of cancer cells with AdRb. AdRb, did not inhibit growth by apoptosis. Conclusions. Ade noviral-mediated gene delivery of constitutively active Rb produces si gnificant growth inhibition in human pancreatic cancer cell lines and is not a result of apoptosis. Further studies examining the role of Rb in pancreatic cancer are warranted.