The Relationship Between The E1B-deleted Adenovirus Antitumoral Efficacy And Host Cell P53 Status And Adenovirus Receptor

Training viruses to attack cancers is the new focus on anticancer research. d!1520(ONYX-015) is such a virus. This is human group C adenovirus contains an 827-base pair deletion in the E1B region and a point mutation at codon 2022 that does not express the 55KDa product of the El B gene. McCormick group hypothesized that dl!520 should be unable to replicate in p53+ cells but would be able to replicate in cells lacking funtional p53. In view of more than 50% of all human cancers lack funtional p53, dl!520 has been carried out to kill cancers. In American,a phase Illclinical trial is already under way. However, recently, another studies shown that dl!520 also replicates in some tumor cells harboring wild-type p53. Their datd raised serious questions on the usefulness of dl 1520 to kill tumor cells.To determine the effect of p53 on dl!520 replication, we first examined the replication of dl!520 in various p53 status cell lines.To avoid the other mechanisms that inactivated p53, we were carry out transfer the exogenous wild-type p53 gene into Hep3B cells(p53 null), and determined the effect of exo-p53 on dl!520 replication and cytopathic effect. We also researched that the effect of dl 1520 on normal tissues cells. Furthermore, we investigated the relationship between the infectability and the effect of dl!520 with a recombinate adenovirus expressing the 3 -galactosidase report gene and anti hexon monoclonal antibody. To explore the mechanisms that lower infectability in the resistant cell lines, we examined the expression of CAR levels by RT-PCR. In addition, we tested wether this limitation could be overcome by enhancing viral entry with cationic liposomes.We show here that dl!520 lyse infection and replication in the HepG-2(p53+) and P53~ cell lines Hep3B,U251,A431. However, markely inhibited the lyse infection and replication in the Lovo (p53+) cells and p53~ cell lines PC-3,T-24,Jurkat,K562,HL-60. We find that dl!520 also lyse infection and replication in the normal hepatocytes. We introduced wild-type p53 gene into Hep3B cells, Western blotting showed that cells (Hep3B) express high levels p53 protein at 48h after infection, we find that dl!520 also lyse infection and replication in the Hep3B-p53 cells. This data comfirmed dl!520 replcation is indipendent of p53 status in host cells. In addition, we report here that all resistant cell lines are low infectability, and their CAR express are lower or loss (PC-3 except). Cationic liposomes siglificantly increase adenovirus entry into PC-3 and Jurkat cell lines. Application of formation dll520-liposome complexs markly increase CPE in Jurkat cells.Our studies comfirmed that the replication of dl 1520 is indipendent of p53 status in host cells, and there is no essential requirement for ElB55KDa-p53 complex formation during replication and cytopathic effect. We find that dl!520 also lyse infection and replication in normal human hepatooytes. The resistance effect of cell lines to dl!520 correlated with the lower infectability, and correlated with CAR expression. Formation of dl!520-liposome complexes increase dl!520 enty into some cell lines.