Degree of apoptosis induced by adenovirus-mediated transduction of p53 or p73alpha depends on the p53 status of glioma cells

It has been reported that U-87MG glioma cells with wild-type p53 are resistant to p53 replacement gene therapy. As some gliomas harbor wild-type p53, it would be important to override the resistance mechanism due to wild-type p53 in glioma gene therapy. In this study, we transduced U-87MG cells or U251 glioma cells harboring mutated p53 with the p53 or p73alpha gene (a homologue of p53, that differently induces some p53-responsive genes) via adenovirus vectors (Advs) at same multiplicities of infection (MOIs) into respective cells (U-87MG: MOI 1000, U251: MOI 100), and evaluated the degree of apoptosis. The results demonstrate that the degree of apoptosis induced by Adv-mediated transduction of p53 in U-87MG cells was lower than that in U251 cells, whereas that induced by Adv-mediated transduction of p73alpha in U-87MG cells was higher than that in U251 cells. Bax expression in U-87MG and U251 cells induced by Adv-mediated transduction of p53 was almost the same as that of p73alpha. On the other hand, Adv-mediated transduction of p73alpha induced caspase-9 at higher levels than that of p53 in both cells. The results indicate that Adv-mediated transduction of p73alpha might be beneficial to overcome the resistance mechanism of glioma cells harboring wild-type p53.