Factors limiting adenovirus-mediated gene transfer into human lung and pancreatic cancer cell lines

Adenoviral vectors are a widely used means of gene transfer. However, trans gene expression after adenoviral administration varies among different carc inoma cell lines. We hypothesized that this variation is attributable, in p art, to the presence of cell surface molecules involved in adenoviral infec tion. To test this, we first assessed adenovirus-mediated transgene express ion in four human lung carcinoma cell lines and four human pancreatic carci noma cell lines in terms of luciferase activities and found it to vary from 4.8 x 10(4) to 6.1 x 10(7) relative light units/mu g of protein. Then, to determine whether the molecules involved in the entry of adenovirus into ho st cells were responsible for this variation, we evaluated the expression o f alpha v beta 5, alpha v, beta 3, alpha 5, and beta 1 integrins and that o f coxsackievirus and adenovirus receptor (CAR) in these cell lines. Statist ical analysis revealed that the levels of beta 3 were associated with the l evels of transgene expression. Blocking analysis showed that adenovirus-med iated gene transfer could be blocked by antibodies against these six molecu les but not by the antibodies against alpha 2 or alpha 3 integrins, thus su ggesting that the integrins alpha v beta 5, alpha v, beta 3, alpha 5, and b eta 1 and CAR molecules could limit adenovirus-mediated gene transfer when their levels fell below a certain threshold. Furthermore, cells expressing low levels of beta 3 and resistant to conventional adenoviral vectors were susceptible to a vector containing the heparin-binding domain in its fiber, thus suggesting that redirecting vectors to receptors other than CAR may b ypass the integrin pathway. These findings may have implications for improv ing the efficiency of adenovirus-mediated gene transfer and developing nove l adenoviral vectors.