HUMAN APC GENE-EXPRESSION IN RODENT COLONIC EPITHELIUM IN-VIVO USING LIPOSOMAL GENE DELIVERY

Mutations or loss of the APC tumor-suppressor gene is important for th e development of colorectal polyps and cancers, but little is known ab out the function of this gene in normal tissue. To study the role of A PC and other genes in colonocytes in vivo, a system was developed wher eby transient expression of genes is established in normal rodent colo nic epithelium, using liposomal gene delivery by rectal catheter infus ion. Expression of a beta-galactosidase reporter gene and of the human APC gene under a constitutive promoter is demonstrated. A high effici ency of transfection is maintained, with close to 100% of epithelial c ells expressing the introduced gene. Expression is transient and does not persist beyond 4 days, consistent with the normal turnover time of gut epithelium, but it can be maintained by repeated treatments. Huma n APC was expressed for three weeks under these conditions at approxim ately one-tenth the level of the endogenous APC gene, and no toxicity was observed beyond that attributed to repeated rectal enemas. These r esults reveal that,in vivo expression of exogenous gene is feasible us ing a liposomal delivery system and suggest a method to further study the physiologic role of APC or other genes in the interrelated process of colonic epithelial proliferation and differentiation.