title: Additive effect of adenovirus-mediated E2F-1 gene transfer and topoisomerase II inhibitors on apoptosis in human osteosarcoma cells.
abstract: Recently, it has been demonstrated that Etoposide, a topoisomerase II inhibitor, can induce apoptosis in MDM2-overexpressing tumor cells by inhibition of MDM2 synthesis. We have previously shown that E2F-1 overexpression induces apoptosis of MDM2-overexpressing sarcoma cells, which is related to the inhibition of MDM2 expression. Therefore, the present study was designed to investigate the in vitro and in vivo effect of combined treatment of adenovirus-mediated E2F-1 and topoisomerase II inhibitors on the growth inhibition and apoptosis in human sarcoma cells. Two human sarcoma cell lines, OsACL and U2OS, were treated with topoisomerase II inhibitors (Etoposide and Adriamycin), alone or in combination with adenoviral vectors expressing beta-galactosidase (Ad-LacZ) or E2F-1 (Ad-E2F-1). E2F-1 expression was confirmed by Western blot analysis. Ad-E2F-1 gene transfer at a low dose (multiplicity of infection, 2) markedly increased the sensitivity of human sarcoma cells to topoisomerase II inhibitor treatment. This cooperative effect of E2F-1 and topoisomerase II inhibitors was less marked in SAOS-2 cells (p53 and pRb null). Topoisomerase II inhibitors also cooperated with E2F-1 overexpression to enhance tumor cell killing in an in vivo model using xenografts in nude mice. When combined with Adriamycin or Etoposide, E2F-1 adenovirus therapy resulted in approximately 95% and 85% decrease in tumor size, respectively, compared to controls (P<.05). These results suggest a new chemosensitization strategy that is effective in MDM2-overexpressing tumors and may have clinical utility.
authors.affiliation: Department of Surgery, University of Louisville, James Graham Brown Cancer Center, Kentucky 40202, USA.
authors.forename: H L
authors.initials: HL
authors.lastname: Yang
authors.forename: Y B
authors.initials: YB
authors.lastname: Dong
authors.forename: M J
authors.initials: MJ
authors.lastname: Elliott
authors.forename: S L
authors.initials: SL
authors.lastname: Wong
authors.forename: K M
authors.initials: KM
authors.lastname: McMasters
mesh_terms: D000256:Adenoviridae / Q000235:genetics*; D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D001859:Bone Neoplasms / Q000201:enzymology / Q000473:pathology / Q000628:therapy*; D002453:Cell Cycle / Q000187:drug effects; D018797:Cell Cycle Proteins; D002470:Cell Survival / Q000187:drug effects; D004268:DNA-Binding Proteins; D004317:Doxorubicin / Q000494:pharmacology; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005047:Etoposide / Q000494:pharmacology; D015870:Gene Expression; D018014:Gene Transfer Techniques; D006801:Humans; D020287:In Situ Nick-End Labeling; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009687:Nuclear Proteins; D012516:Osteosarcoma / Q000201:enzymology / Q000473:pathology / Q000628:therapy*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051736:Proto-Oncogene Proteins c-mdm2; D059005:Topoisomerase II Inhibitors; D014157:Transcription Factors / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
chemical_list: D000903:Antibiotics, Antineoplastic; D000972:Antineoplastic Agents, Phytogenic; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; C493753:E2F1 protein, human; C493754:E2f1 protein, mouse; D004791:Enzyme Inhibitors; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D059005:Topoisomerase II Inhibitors; D014157:Transcription Factors; D016159:Tumor Suppressor Protein p53; D005047:Etoposide; D004317:Doxorubicin; C497206:MDM2 protein, human; C497207:Mdm2 protein, mouse; D051736:Proto-Oncogene Proteins c-mdm2