Beta-Adrenoceptor Blockade Markedly Attenuates Transgene Expression From Cytomegalovirus Promoters Within the Cardiovascular System

Abstract

Objectives— The major immediate–early cytomegalovirus enhancer/promoter (MIECMV), widely used in cardiovascular gene therapy, contains several positively regulatory cAMP response elements (CRE). Catecholamine signaling via β-adrenoceptors might increase transgene expression from MIECMV, and if so, β-blockers may have a detrimental effect on the efficacy of clinical cardiovascular gene therapy strategies. Methods and Results— Cultured smooth muscle cells were exposed to isoprenaline, atenolol, or propranolol, alone and in combination before infection with adenoviruses expressing β-galactosidase. β-galactosidase expression was assayed 72 hours later. Isoprenaline increased transgene expression from MIECMV up to 8-fold ( P <0.001), but had no effect on a promoter containing no CRE. The effect of isoprenaline was inhibited by β-blockade and by specific CRE-decoy oligonucleotides. β-blockers did not reduce transgene expression below basal levels. After adenovirus-mediated porcine intracoronary gene transfer, however, β-blockade reduced β-galactosidase expression by up to 250-fold compared with non-β-blocked animals ( P <0.01). Conclusions— Enhancement of promoter activity by endogenous catecholamines is essential for high-level transgene expression from MIECMV within the vasculature. β-blocker-mediated suppression of transgene expression from MIECMV in vascular tissues has a significant bearing on clinical studies of cardiovascular gene transfer. This is the first described interaction to our knowledge between widely prescribed pharmaceuticals and a commonly used promoter of clinical transgene expression.