title: Comparative metabolism of benzo[a]pyrene by human keratinocytes infected with high-risk human papillomavirus types 16 and 18 as episomal or integrated genomes.
abstract: BACKGROUND
  Infection with human papillomavirus (HPV) is a critical factor in the development of cervical cancer. Smoking is an additional risk factor. Tobacco smoke carcinogens, such as benzo[a]pyrene (B[a]P), and their cytochrome P450-related metabolites are present in significantly higher levels in the cervical mucus of women smokers than in nonsmokers. We determined the metabolism and P450 expression of B[a]P-treated human keratinocytes infected with HPV-16 or -18.
  
  
  METHODS
  Monolayer cultures of uninfected primary human foreskin keratinocytes, human vaginal and cervical keratinocytes carrying episomal genomes of HPV-16 and -18, respectively, and invasive cervical carcinoma cell lines carrying either HPV-16 or -18 genomes integrated into the host DNA, were incubated with 0.1 μM [(3)H]B[a]P. The resulting oxidative metabolites were analyzed and quantified by radioflow high-performance liquid chromatography. Additionally, all cell lines were incubated with unlabeled 0.1 μM B[a]P for Western blot analysis of cytochrome P450 1A1 and 1B1.
  
  
  RESULTS
  Significant enhancement in levels of both detoxification and activation metabolites was found in incubations with all types of HPV-infected cells compared with control incubations (P < 0.05). The highest capacity to metabolize B[a]P was observed with cells containing integrated HPV-18 genomes. Induction of cytochrome 1B1 was observed in HPV-16 and -18 integrated, and in HPV-16 episomal cell types.
  
  
  CONCLUSIONS
  Both viral genotype and genomic status in the host cell affect B[a]P metabolism and cytochrome P450 1B1 expression. An increase of DNA-damaging metabolites might result from exposure of HPV-infected women to cigarette smoke carcinogens.
authors.affiliation: Department of Pharmacology, Penn State University, Hershey, PA 17033, USA.
authors.forename: Neil
authors.initials: N
authors.lastname: Trushin
authors.forename: Samina
authors.initials: S
authors.lastname: Alam
authors.forename: Karam
authors.initials: K
authors.lastname: El-Bayoumy
authors.forename: Jacek
authors.initials: J
authors.lastname: Krzeminski
authors.forename: Shantu G
authors.initials: SG
authors.lastname: Amin
authors.forename: Jenny
authors.initials: J
authors.lastname: Gullett
authors.forename: Craig
authors.initials: C
authors.lastname: Meyers
authors.forename: Bogdan
authors.initials: B
authors.lastname: Prokopczyk