Differential induction of CYP1A1 and CYP1B1 by benzo[a]pyrene in oral squamous cell carcinoma cell lines and by tobacco smoking in oral mucosa

Oral Oncol. 2009 Nov;45(11):980-5. doi: 10.1016/j.oraloncology.2009.05.562. Epub 2009 Jul 2.


Polyaromatic hydrocarbons, including benzo[a]pyrene (BP), are major tobacco carcinogens. Their carcinogenic effects require metabolic activation by cytochrome p450 (CYP) enzymes. Relative CYP isoform expression is related to tissue-specific tobacco-related squamous cell carcinoma (SCC) susceptibility. There have been conflicting reports regarding relative CYP1A1 and CYP1B1 oral expression, and information regarding CYP1B1 expression in oral tissues is limited. To quantify BP- and tobacco-induced CYP1A1 and CYP1B1 expression in oral SCC cells and oral mucosa.

Study design: Real-time qPCR was performed to measure (1) BP-induced CYP1A1 and CYP1B1 mRNA expression in seven oral/other head and neck SCC cell lines (2) CYP1A1 and CYP1B1 mRNA expression in gingiva from 22 smokers and 24 nonsmokers. SCC lines exhibited either similar induction of both isoforms or preferential CYP1A1 induction (CYP1A1-to-CYP1B1 ratios 0.8-4.3). In contrast, gingival tissues from smokers exhibited preferential CYP1B1 induction. Marked interindividual variation in CYP1A1 and CYP1B1 expression was observed among smokers. In vitro conditions may not account for factors that modulate expression in vivo. Interindividual variation in inducible CYP1A1 and CYP1B1 expression may account in part for variation in tobacco-related oral SCC risk.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Aryl Hydrocarbon Hydroxylases / metabolism*
  • Benzo(a)pyrene / pharmacology*
  • Benzo(a)pyrene / toxicity
  • Carcinoma, Squamous Cell / metabolism*
  • Cytochrome P-450 CYP1A1 / metabolism*
  • Cytochrome P-450 CYP1B1
  • Female
  • Head and Neck Neoplasms / metabolism*
  • Humans
  • Male
  • Middle Aged
  • Mouth Mucosa / metabolism
  • Mouth Neoplasms / metabolism
  • Polymerase Chain Reaction / methods
  • Smoking / adverse effects
  • Smoking / metabolism


  • Benzo(a)pyrene
  • Aryl Hydrocarbon Hydroxylases
  • CYP1B1 protein, human
  • Cytochrome P-450 CYP1A1
  • Cytochrome P-450 CYP1B1