Adenovirus-mediated thymidine kinase gene therapy and coxsackie adenovirus receptor expression in ovarian cancer cells.

Coxsackie adenovirus receptor (CAR) expression is the main mechanism of adenovirus entry into target cells. It is unclear whether CAR expression itself is influenced by transduction with the adenovirus-Rous sarcoma virus-thymidine kinase (ADV-RSV-TK) gene therapy construct or by the subsequent intracellular accumulation of the TK gene product. Antibody generation and characterization, immunocytochemistry, Western blotting and 3-(4,5-dimethylthiazol)-2,5-diphenyl tetrazolium bromide (MTT) assay were performed to investigate the relationship of gene transfer and CAR expression as well as differences in therapeutic susceptibility of MDAH-2774 and OVCAR-3 cell lines to ADV-RSV-TK gene therapy. CAR expression was observed on the membranes but intracellular translocation of CAR also took place dependent on cellular growth patterns. TK gene expression was dependent on multiplicity of infection (MOI) and thus on vector dose in a linear fashion. Neither TK expression nor ADV transduction influenced CAR expression, or ADV-RSV-TK transduction. Differential susceptibility of different cell lines to TK-induced cell killing by acyclovir metabolites was observed. CAR expression appears not to be influenced by adenoviral transduction or by the accumulation of the TK gene product. Differences in therapeutic sensitivity are most likely mediated by intracellular mechanisms and not by modulation of CAR expression.