PT  - JOURNAL ARTICLE
AU  - Piyush M. Vyas
AU  - Sanjoy Roychowdhury
AU  - Farah D. Khan
AU  - Thomas E. Prisinzano
AU  - Jatinder Lamba
AU  - Erin G. Schuetz
AU  - Joyce Blaisdell
AU  - Joyce A. Goldstein
AU  - Kimber L. Munson
AU  - Ronald N. Hines
AU  - Craig K. Svensson
TI  - Enzyme-Mediated Protein Haptenation of Dapsone and Sulfamethoxazole in Human Keratinocytes: I. Expression and Role of Cytochromes P450
AID  - 10.1124/jpet.106.105858
DP  - 2006 Oct 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 488--496
VI  - 319
IP  - 1
4099  - http://jpet.aspetjournals.org/content/319/1/488.short
4100  - http://jpet.aspetjournals.org/content/319/1/488.full
SO  - J Pharmacol Exp Ther2006 Oct 01; 319
AB  - Cutaneous drug reactions (CDRs) are among the most common adverse drug reactions and are responsible for numerous minor to life-threatening complications. Several arylamine drugs, such as sulfamethoxazole (SMX) and dapsone (DDS), undergo bioactivation, resulting in adduction to cellular proteins. These adducted proteins may initiate the immune response that ultimately results in a CDR. Recent studies have demonstrated that normal human epidermal keratinocytes (NHEKs) can bioactivate these drugs, resulting in protein haptenation. We sought to identify the enzyme(s) responsible for this bioactivation in NHEKs. Using immunofluorescence confocal microscopy and an adduct-specific enzyme-linked immunosorbent assay (ELISA), we found that N-acetylation of the primary amine of SMX and DDS markedly reduced the level of protein haptenation in NHEKs. Detection of mRNA and/or protein confirmed the presence of CYP3A4, CYP3A5, and CYP2E1 in NHEKs. In contrast, although a faint band suggestive of CYP2C9 protein was detected in one NHEK sample, a CYP2C9 message was not detectable. We also examined the ability of chemical inhibitors of cytochromes P450 (aminobenzotriazole and 1-dichloroethylene) and cyclooxygenase (indomethacin) to reduce protein haptenation when NHEKs were incubated with SMX or DDS by either confocal microscopy or ELISA. These inhibitors did not significantly attenuate protein adduction with either SMX or DDS, indicating that cytochromes P450 and cyclooxygenase do not play important roles in the bioactivation of these xenobiotics in NHEKs and thus suggesting the importance of other enzymes in these cells. The American Society for Pharmacology and Experimental Therapeutics