title: Modification of the Rb-binding domain of replication-competent adenoviral vector enhances cytotoxicity against human esophageal cancers via NF-kappaB activity.
abstract: A replication-competent adenoviral vector deficient for expression of the early E1B55K protein has been applied in clinical studies. The vector, however, was not fully effective for the treatment of human cancer. In this study, the E1A gene (which encodes an Rb-binding domain protein) of the adenoviral vector AxE1AdB was further engineered with a point mutation designed to abolish binding to Rb protein (pRb) and arrest the cell cycle (AxdAdB-3). The difference in the cytotoxicity of these vectors in two cancer cell lines was observed in association with differences in replication, infection efficiency, and expression levels of adenovirus receptors. Relative to the parent vector (AxE1AdB), which worked in a manner similar to ONYX-015, AxdAdB-3 with the mutated pRb-binding motif demonstrated increased cytotoxicity against p53-mutant human esophageal cancer cell lines EC-GI-10 and T.Tn. AxdAdB-3 showed a greater oncolytic effect than AxE1AdB in vivo despite almost the same replication efficiency in vitro. Unexpectedly, cell cycle arrest in AxdAdB-3-infected cells was less efficient than that in cell lines infected with AxE1AdB. However, AxdAdB-3 strongly reduced NF-kappaB activity and thereby enhanced apoptosis more than AxE1AdB did. These data demonstrate that the Rb-binding domain of E1A can regulate NF-kappaB activity and that modifications to this domain may lead to advances in gene therapies for the treatment of human cancers.
authors.affiliation: Department of Internal and Geriatric Medicine, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan.
authors.forename: Katsumi
authors.initials: K
authors.lastname: Yamada
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Moriyama
authors.forename: Hisafumi
authors.initials: H
authors.lastname: Yasuda
authors.forename: Kenta
authors.initials: K
authors.lastname: Hara
authors.forename: Yoshimasa
authors.initials: Y
authors.lastname: Maniwa
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Hamada
authors.forename: Koichi
authors.initials: K
authors.lastname: Yokono
authors.forename: Masao
authors.initials: M
authors.lastname: Nagata
mesh_terms: D017500:Adenovirus E1A Proteins / Q000235:genetics; D017501:Adenovirus E1B Proteins / Q000235:genetics; D000260:Adenoviruses, Human / Q000235:genetics*; D000595:Amino Acid Sequence; D001665:Binding Sites / Q000235:genetics; D045744:Cell Line, Tumor; D003588:Cytopathogenic Effect, Viral / Q000235:genetics; D004938:Esophageal Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000628:therapy*; D015316:Genetic Therapy / Q000379:methods; D005822:Genetic Vectors; D006801:Humans; D016328:NF-kappa B / Q000378:metabolism*; D011485:Protein Binding; D011991:Receptors, Virus / Q000235:genetics; D016160:Retinoblastoma Protein / Q000378:metabolism*; D014161:Transduction, Genetic
chemical_list: D017500:Adenovirus E1A Proteins; D017501:Adenovirus E1B Proteins; D016328:NF-kappa B; D011991:Receptors, Virus; D016160:Retinoblastoma Protein