title: HIV protease inhibitors block oral epithelial cell DNA synthesis.
abstract: OBJECTIVE
  Anti-retroviral therapy regimens that include HIV protease inhibitors (PIs) are associated with diverse adverse effects including increased prevalence of oral warts, oral sensorial deficits and gastrointestinal toxicities suggesting that PIs may perturb epithelial cell biology. To test the hypothesis that PIs could affect specific biological processes of oral epithelium, the effects of these agents were evaluated in several oral epithelial cell-lines.
  
  
  METHODS
  Primary and immortalized oral keratinocytes and squamous carcinoma cells of oropharyngeal origin were cultured in the presence of pharmacologically relevant concentrations of PIs. Their affects on cell viability, cytotoxicity and DNA synthesis were assessed by enzymatic assays and incorporation of 5-bromo-2'-deoxyuridine (BrdU) into DNA.
  
  
  RESULTS
  Viability of primary and immortalized oral keratinocytes as well as squamous carcinoma cells of oropharyngeal origin was significantly reduced by select PIs at concentrations found in plasma. Of the seven PIs evaluated, nelfinavir was the most potent with a mean 50% inhibitory concentration [IC(50)] of 4.1 microM. Lopinavir and saquinavir also reduced epithelial cell viability (IC(50) of 10-20 microM). Atazanavir and ritonovir caused minor reductions in viability, while amprenavir and indinavir were not significant inhibitors. The reduced cell viability, as shown by BrdU incorporation assays, was due to inhibition of DNA synthesis rather than cell death due to cytotoxicity.
  
  
  CONCLUSIONS
  Select PIs retard oral epithelial cell proliferation in a drug and dose-dependent manner by blocking DNA synthesis. This could account for some of their adverse effects on oral health.
authors.affiliation: Department of Oral Health Practice, University of Kentucky, Lexington, KY 40536-0297, USA.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Danaher
authors.forename: Chunmei
authors.initials: C
authors.lastname: Wang
authors.forename: Andrew T
authors.initials: AT
authors.lastname: Roland
authors.forename: Charlotte S
authors.initials: CS
authors.lastname: Kaetzel
authors.forename: Richard N
authors.initials: RN
authors.lastname: Greenberg
authors.forename: Craig S
authors.initials: CS
authors.lastname: Miller
mesh_terms: D000704:Analysis of Variance; D001973:Bromodeoxyuridine / Q000494:pharmacology; D002294:Carcinoma, Squamous Cell / Q000188:drug therapy*; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D004261:DNA Replication / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D057075:Enzyme Assays; D004847:Epithelial Cells / Q000187:drug effects*; D017320:HIV Protease Inhibitors / Q000009:adverse effects / Q000494:pharmacology*; D006801:Humans; D015603:Keratinocytes / Q000187:drug effects*; D009061:Mouth Mucosa / Q000166:cytology*; D014062:Tongue Neoplasms / Q000188:drug therapy*; D014407:Tumor Cells, Cultured
chemical_list: D017320:HIV Protease Inhibitors; D001973:Bromodeoxyuridine