title: Overexpression of human papillomavirus type 16 oncoproteins enhances hypoxia-inducible factor 1 alpha protein accumulation and vascular endothelial growth factor expression in human cervical carcinoma cells.
abstract: OBJECTIVE
  Human papillomavirus (HPV)-16 oncoproteins, E6 and E7, are associated with enhanced tumor angiogenesis in human cervical cancers. The purpose of this study was (a) to investigate whether expression of HPV-16 E6 and E7 oncoproteins induces hypoxia-inducible factor 1 alpha (HIF-1 alpha) and vascular endothelial growth factor expression in cervical cancer cells; and (b) to assess the effect of resveratrol on 16 E6- and E7-induced HIF-1 alpha and VEGF gene expression.
  
  
  METHODS
  Human cervical cancer cell lines C-33A and HeLa were transiently cotransfected with pSG5-HPV-16 E6 or 16 E7 constructs along with HIF-1 alpha small interfering RNA (siRNA) or nonspecific siRNA. The expression of HIF-1 alpha/VEGF was measured using real-time PCR, Western blot analysis, or ELISA. The in vitro angiogenic activity induced by 16 E6- and E7-transfected cells was examined. The effect of resveratrol on oncoprotein-induced HIF-1 alpha/VEGF expression and in vitro angiogenesis was investigated.
  
  
  RESULTS
  HPV-16 E6- and E7-transfected cervical cancer cells express increased HIF-1 alpha protein and VEGF expression. These stimulatory effects were abrogated by cotransfection with either HIF-1 alpha siRNA or treatment with resveratrol. Blocking extracellular signal-regulated kinase 1/2 (ERK 1/2) and phosphoinositide-3-kinase by PD98059 and LY294002, respectively, abolished 16 E6- and E7-induced HIF-1 alpha and VEGF expression. Functionally, we showed that HPV-16 E6- and E7-transfected cervical cancer cells stimulated in vitro capillary or tubule formation, and these angiogenic effects could be abolished either by cotransfection with HIF-1 alpha siRNA or by treatment with resveratrol.
  
  
  CONCLUSIONS
  HPV-16 oncoproteins contribute to enhanced angiogenesis in cervical cancer cells via HIF-1 alpha-dependent VEGF expression. Resveratrol suppresses 16 E6- and E7-induced HIF-1 alpha-mediated angiogenic activity and, thus, is a promising chemotherapeutic agent for human cervical cancer.
authors.affiliation: Center for Craniofacial Molecular Biology, University of Southern California, School of Dentistry, Los Angeles, California 90033, USA.
authors.forename: Xudong
authors.initials: X
authors.lastname: Tang
authors.forename: Qunzhou
authors.initials: Q
authors.lastname: Zhang
authors.forename: Junko
authors.initials: J
authors.lastname: Nishitani
authors.forename: Jimmy
authors.initials: J
authors.lastname: Brown
authors.forename: Shihong
authors.initials: S
authors.lastname: Shi
authors.forename: Anh D
authors.initials: AD
authors.lastname: Le
mesh_terms: D016588:Anticarcinogenic Agents / Q000494:pharmacology; D002277:Carcinoma / Q000235:genetics / Q000378:metabolism*; D002867:Chromones / Q000494:pharmacology; D005260:Female; D005419:Flavonoids / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000032:analysis / Q000037:antagonists & inhibitors / Q000378:metabolism*; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors; D009025:Morpholines / Q000494:pharmacology; D009389:Neovascularization, Pathologic / Q000235:genetics / Q000378:metabolism*; D009856:Oncogene Proteins, Viral / Q000235:genetics*; D050725:Papillomavirus E7 Proteins; D000081082:Phosphoinositide-3 Kinase Inhibitors; D034741:RNA, Small Interfering / Q000235:genetics / Q000494:pharmacology; D012097:Repressor Proteins / Q000235:genetics*; D000077185:Resveratrol; D013267:Stilbenes / Q000494:pharmacology; D015533:Transcriptional Activation; D014162:Transfection; D002583:Uterine Cervical Neoplasms / Q000235:genetics / Q000378:metabolism*; D042461:Vascular Endothelial Growth Factor A
chemical_list: D016588:Anticarcinogenic Agents; D002867:Chromones; C068651:E6 protein, Human papillomavirus type 16; D005419:Flavonoids; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D009025:Morpholines; D009856:Oncogene Proteins, Viral; D050725:Papillomavirus E7 Proteins; D000081082:Phosphoinositide-3 Kinase Inhibitors; D034741:RNA, Small Interfering; D012097:Repressor Proteins; D013267:Stilbenes; D042461:Vascular Endothelial Growth Factor A; C059731:oncogene protein E7, Human papillomavirus type 16; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D000077185:Resveratrol; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one