title: The roles of E6-AP and MDM2 in p53 regulation in human papillomavirus-positive cervical cancer cells.
abstract: The p53 tumor suppressor is regulated by the MDM2 oncoprotein through a negative feedback mechanism. MDM2 promotes the ubiquitination and proteasome-dependent degradation of p53, possibly by acting as a ubiquitin ligase. In cervical cancer cells containing high-risk human papillomaviruses (HPV), p53 is also targeted for degradation by the HPV E6 oncoprotein in combination with the cellular E6-AP ubiquitin ligase. In this report, we describe the identification of efficient antisense oligonucleotides against human E6-AP. The roles of MDM2 and E6-AP in p53 regulation were investigated using a novel E6-AP antisense oligonucleotide and a previously characterized MDM2 antisense oligonucleotide. In HPV16-positive and HPV-18 positive cervical cancer cells, inhibition of E6-AP, but not MDM2, expression results in significant induction of p53. In HPV-negative tumor cells, p53 is activated by inhibition of MDM2 but not E6-AP. Furthermore, treatment with both E6-AP and MDM2 antisense oligonucleotides in HPV-positive cells does not lead to further induction of p53 over inhibition of E6-AP alone. Therefore, E6-AP-mediated degradation is dominant over MDM2 in cervical cancer cells but does not have a significant role in HPV-negative cells.
authors.affiliation: Department of Microbiology, Louisiana State University Medical Center, New Orleans 70112, USA.
authors.forename: M
authors.initials: M
authors.lastname: Traidej
authors.forename: L
authors.initials: L
authors.lastname: Chen
authors.forename: D
authors.initials: D
authors.lastname: Yu
authors.forename: S
authors.initials: S
authors.lastname: Agrawal
authors.forename: J
authors.initials: J
authors.lastname: Chen
mesh_terms: D002470:Cell Survival / Q000187:drug effects; D004317:Doxorubicin / Q000494:pharmacology; D005260:Female; D005455:Fluorescent Antibody Technique; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D008025:Ligases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D027383:Papillomaviridae / Q000235:genetics*; D010714:Phosphatidylethanolamines / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D051736:Proto-Oncogene Proteins c-mdm2; D012333:RNA, Messenger / Q000378:metabolism; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases; D002583:Uterine Cervical Neoplasms / Q000821:virology
chemical_list: D009687:Nuclear Proteins; D016376:Oligonucleotides, Antisense; D010714:Phosphatidylethanolamines; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D016159:Tumor Suppressor Protein p53; C020888:1,2-dielaidoylphosphatidylethanolamine; D004317:Doxorubicin; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2; D044767:Ubiquitin-Protein Ligases; D008025:Ligases