A GLIAL-SPECIFIC, REPRESSIBLE, ADENOVIRUS VECTOR FOR BRAIN-TUMOR GENE-THERAPY

The principle hurdles for gene therapy are selectivity and efficacy, T oward that end, we constructed an adenovirus gene delivery system to e nable robust, glial-specific, and repressible ectopic expression, A re plication-incompetent (El-deleted) adenovirus 5 vector was modified by the addition of three tandem repeats of a 300-bp fragment enhancer re gion of the glial fibrillary acidic protein gene coupled to a minimal promoter sequence from human cytomegalovirus to drive a tetracycline-c ontrolled transactivator. Using beta-galactosidase as a reporter gene, we demonstrated high level expression in cells of glial origin (inclu ding cell lines derived from glioblastoma multiforme) but no detectabl e expression in nonglial cells (neuroblastoma or fibroblasts). Further more, expression was tightly regulated by anhydrous tetracycline. To o ur knowledge, this is the first gene therapy delivery system that is g lial specific and which also allows for repression of ectopic gene exp ression.