title: Structure based identification and characterization of flavonoids that disrupt human papillomavirus-16 E6 function.
abstract: Expression and function of the human papillomavirus (HPV) early protein 6 (E6) is necessary for viral replication and oncogenesis in cervical cancers. HPV E6 targets the tumor suppressor protein p53 for degradation. To achieve this, "high-risk" HPV E6 proteins bind to and modify the target specificity of the ubiquitin ligase E6AP (E6 associated protein). This E6-dependent loss of p53 enables the virus to bypass host cell defenses and facilitates virally induced activation of the cell cycle progression during viral replication. Disruption of the interaction between E6 and E6AP and stabilization of p53 should decrease viability and proliferation of HPV positive cells. A new in vitro high-throughput binding assay was developed to assay binding between HPV-16 E6 and E6AP and to identify compounds that inhibit this interaction. The compound luteolin emerged from the screen and a library of novel flavones based on its structure was synthesized and characterized using this in vitro binding assay. The compounds identified in this study disrupt the E6/E6AP interaction, increase the levels of p53 and p21(Cip1/Waf1), and decrease proliferation of HPV positive cell lines. The new class of flavonoid E6 inhibitors displays a high degree of specificity for HPV positive cells. Docking analyses suggest that these compounds bind in a hydrophobic pocket at the interface between E6 and E6AP and mimic the leucines in the conserved α-helical motif of E6AP. The activity and specificity of these compounds represent a promising new lead for development as an antiviral therapy in the treatment of HPV infection and cervical cancer.
authors.affiliation: Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America ; Department of Dermatology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America.
authors.forename: Jonathan J
authors.initials: JJ
authors.lastname: Cherry
authors.affiliation: Department of Dermatology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America.
authors.forename: Anne
authors.initials: A
authors.lastname: Rietz
authors.affiliation: Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America.
authors.forename: Anna
authors.initials: A
authors.lastname: Malinkevich
authors.affiliation: Department of Biochemistry, Tufts University School of Medicine, Boston, Massachusetts, United States of America.
authors.forename: Yuqi
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America ; Department of Dermatology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America.
authors.forename: Meng
authors.initials: M
authors.lastname: Xie
authors.affiliation: Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University College of Pharmacy, West Lafayette, Indiana, United States of America.
authors.forename: Matthew
authors.initials: M
authors.lastname: Bartolowits
authors.affiliation: Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University College of Pharmacy, West Lafayette, Indiana, United States of America.
authors.forename: V Jo
authors.initials: VJ
authors.lastname: Davisson
authors.affiliation: Department of Biochemistry, Tufts University School of Medicine, Boston, Massachusetts, United States of America.
authors.forename: James D
authors.initials: JD
authors.lastname: Baleja
authors.affiliation: Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America ; Department of Dermatology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America.
authors.forename: Elliot J
authors.initials: EJ
authors.lastname: Androphy
mesh_terms: D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D055808:Drug Discovery; D005260:Female; D005419:Flavonoids / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000494:pharmacology; D057166:High-Throughput Screening Assays / Q000379:methods; D052162:Human papillomavirus 16 / Q000187:drug effects*; D006801:Humans; D047311:Luteolin / Q000494:pharmacology; D008958:Models, Molecular; D015394:Molecular Structure; D009856:Oncogene Proteins, Viral / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding / Q000502:physiology; D012097:Repressor Proteins / Q000737:chemistry / Q000378:metabolism*; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*; D002583:Uterine Cervical Neoplasms / Q000188:drug therapy / Q000821:virology*
chemical_list: C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; C068651:E6 protein, Human papillomavirus type 16; D005419:Flavonoids; D009856:Oncogene Proteins, Viral; D012097:Repressor Proteins; D016159:Tumor Suppressor Protein p53; C471639:UBE3A protein, human; D044767:Ubiquitin-Protein Ligases; D047311:Luteolin