THE PANCREATITIS-ASSOCIATED PROTEIN-I PROMOTER ALLOWS TARGETING TO THE PANCREAS OF A FOREIGN GENE, WHOSE EXPRESSION IS UP-REGULATED DURING PANCREATIC INFLAMMATION

The pancreatitis-associated protein I (PAP I) is a pancreatic secretor y protein expressed in pancreas during acute pancreatitis but not in t he healthy pancreas, The promoter of the PAP I gene thus represents a potential candidate to drive expression of therapeutic molecules to th e diseased pancreas, In this work, we have constructed recombinant ade noviruses harboring the chloramphenicol acetyltransferase (CAT) gene d riven by several fragments of the PAP I promoter and have characterize d their properties in vitro and in vivo. In vitro studies showed that the transduction of the pancreatic cell line AR-42J with these adenovi ruses led to low levels of CAT activity in basal conditions. After sti mulation with a combination of interleukin-6 and dexamethasone or afte r induction of oxidative stress, CAT activity was strongly induced, a characteristic of the endogenous PAP I gene, Stimulation was maximal w hen constructs comprised 1253 base pairs of the PAP I promoter, upstre am from initiation of transcription, and decreased with shorter fragme nts of 317, 180, 118 or 61 base pairs. The recombinant adenovirus cont aining the CAT gene under the control of the PAP I promoter fragment ( -1253/+10) was also tested in vivo. Following administration by intrav enous injection into mice, CAT activity was measured in several tissue s 96 h later, In healthy animals, low but significant CAT activity was detected in pancreas, compared with near background values observed i ll the other tissues. When experimental acute pancreatitis was induced , CAT expression was strongly enhanced only in pancreas. In control ex periments with adenoviruses in which the CAT gene was driven by the cy tomegalovirus promoter, higher levels of expression were observed in a ll tissues, Expression was not modified after induction of acute pancr eatitis. In conclusion, this study shows that (i) a recombinant adenov irus containing a fragment of the PAP I promoter allows specific targe ting of a reporter gene to the mouse pancreas and (ii) expression of t he reporter gene in pancreas is induced during acute pancreatitis. Ade novirus-mediated gene therapy of acute pancreatitis is therefore conce ivable.