ADP-overexpressing adenovirus elicits enhanced cytopathic effect by induction of apoptosis.
Replication-competent adenoviruses (Ad's) are emerging as a promising new modality for treatment of cancer. Selective replication of viral agents in tumor may lead to improved efficacy over nonreplicating Ad's due to their inherent ability to multiply, lyse, and spread to surrounding cells. We have previously shown that an E1B 55 kDa-deleted adenovirus (YKL-1) exhibits tumor-specific replication and cell lysis, but its cytolytic effects were reduced in comparison to the wild-type adenovirus. To increase the oncolytic potency of YKL-1, we have reintroduced the Ad death protein (ADP) gene under the control of either a CMV or an MLP promoter at the E3 region of YKL-1, generating YKL-cADP and YKL-mADP Ad's, respectively. ADP is an 11.6 kDa protein encoded by the E3 transcription unit, and is required to kill adenovirus-infected cells efficiently. However, to date, the mechanism by which ADP mediates cell death has not been clearly defined. In this study, we report that ADP-overexpressing Ad markedly enhanced cytolytic effect (up to 100-fold) against all tumor cell lines tested, but did not increase cytopathic effect in normal skin fibroblast, BJ. Moreover, plaque size formed by YKL-cADP was substantially larger than that of YKL-1, indicating an enhancement in cell lysis. TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling) assay and Annexin-V/PI double staining indicate that ADP-mediated cytotoxicity was largely driven by apoptosis. Finally, YKL-cADP adenovirus also showed superior antitumor effect than YKL-1 and YKL-mADP in C33A cervical and Hep3B hepatoma xenograft tumor models. Taken together, these lines of evidence demonstrate that the newly generated adenovirus expressing ADP under the CMV promoter induces efficient but tumor-selective cell lysis, which is critical for adding therapeutic value to replicating adenovirus for its use in cancer gene therapy.
Yun
Chae-Ok
CO
Brain Korea 21 Project for Medical Sciences, Institute for Cancer Research, Yonsei Cancer Center, Seoul, Korea. chaeok@yumc.yonsei.ac.kr
Kim
Eunhee
E
Koo
Taeyoung
T
Kim
Hoguen
H
Lee
Young-sook
YS
Kim
Joo-Hang
JH
D000256:Adenoviridae / Q000235:genetics* / Q000472:pathogenicity; D017503:Adenovirus E3 Proteins / Q000096:biosynthesis* / Q000235:genetics* / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000235:genetics*; D006528:Carcinoma, Hepatocellular / Q000235:genetics / Q000473:pathology / Q000628:therapy*; D004354:Drug Screening Assays, Antitumor; D005260:Female; D005347:Fibroblasts; D015316:Genetic Therapy / Q000379:methods*; D006801:Humans; D008113:Liver Neoplasms / Q000235:genetics / Q000473:pathology / Q000628:therapy; D008297:Male; D008562:Membrane Glycoproteins; D051379:Mice; D008819:Mice, Nude; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis; D014183:Transplantation, Heterologous; D014407:Tumor Cells, Cultured; D002583:Uterine Cervical Neoplasms / Q000235:genetics / Q000473:pathology / Q000628:therapy*; D014779:Virus Replication
D017503:Adenovirus E3 Proteins; D008562:Membrane Glycoproteins; D012333:RNA, Messenger; C099609:adenovirus death protein, Adenovirus