Adenovirus-mediated transfer of p33(ING1) with p53 drastically augments apoptosis in gliomas

The p53 tumor suppressor gene is an important target for the gene therapy o f cancers, and clinical trials targeting this gene have been conducted. Som e cancers, however, are refractory to p53 gene therapy. Therefore, it has b een combined with other therapies, including chemotherapy and radiotherapy, to enhance the cytopathic effect of p53 induction. The p33(ING1) gene coop erates with p53 to block cell proliferation. In this study, we investigated whether adenovirus (Adv)-mediated coinduction of p33(ING1) and p53 enhance s apoptosis in glioma cells (U251 and U-373 MG), which showed no genetic al terations but low expression levels of p33(ING1). Although the single infec tion of Adv for p33(ING1) (Adv-p33) at a multiplicity of infection (MOI) of 100, or Adv for p53 controlled by myelin basic protein (MBP) promoter (Adv -MBP-p53), a glioma-specific promoter, at a MOI of 50, did not induce apopt osis in U251 and U-373 MG glioma cells; coinfection of Adv-p33 and Adv-MBP- p53 at the same MOIs induced drastically enhanced apoptosis in both cell li nes. Apoptosis was not induced in NGF-treated PC-12 cells infected with a h igh MOI (300) of Adv-p33 nor in those coinfected with Adv-p33 (100) and Adv -MBP-p53 (50). Coinfection of Adv-p33 and Adv-MBP-p53 demonstrated morpholo gical mitochondrial damage during the initial stage of apoptosis, which lik ely led to apoptotic cell death. Our results indicate that this coinfection approach can be used as a modality for the gene therapy of gliomas, sparin g damage to normal tissues.