title: Alanine aminotransferase regulation by androgens in non-hepatic tissues.
abstract: OBJECTIVE
  Alanine amino-transferases (ALTs) play a crucial role in drug development as a surrogate marker of liver injury where elevations in serum ALT activity are used to diagnose drug-induced liver damage. Two ALT isoforms have been characterized with disparate but overlapping tissue expression. ALT1 is primarily expressed in live; ALT2 is found in muscle and prostate tissues. We investigate ALT gene expression in diverse rodent tissues following administration of the steroidal androgen receptor (AR) agonist dihydrotestosterone and a novel tissue selective nonsteroidal agonist S-23.
  
  
  METHODS
  Putative AR regulation of ALT expression was determined in silico by an orthologous promoter androgen response element (ARE) search. Regulation was evaluated by transient transfection of ALT promoter region constructs and qRT-PCR experiments in cultured cells and in tissues following androgen administration.
  
  
  RESULTS
  Several putative AREs were found in the proximal promoter regions of ALT1 and ALT2. AREs in ALT2 but not ALT1 were capable of AR-mediated transcription. ALT2 expression was affected by castration and androgen administration in muscle and prostate but not liver tissues.
  
  
  CONCLUSIONS
  Androgen action in non-hepatic tissues, as opposed to xenobiotic toxicity alone, may contribute to increases in serum ALT activity following androgen administration.
authors.affiliation: Preclinical Research and Development, GTx, Inc., 3 North Dunlap Street, Memphis, Tennessee 38163, USA.
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Coss
authors.forename: Matt
authors.initials: M
authors.lastname: Bauler
authors.forename: Ramesh
authors.initials: R
authors.lastname: Narayanan
authors.forename: Duane D
authors.initials: DD
authors.lastname: Miller
authors.forename: James T
authors.initials: JT
authors.lastname: Dalton
mesh_terms: D000410:Alanine Transaminase / Q000097:blood / Q000235:genetics / Q000378:metabolism*; D000728:Androgens / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D015415:Biomarkers / Q000097:blood / Q000378:metabolism; D013196:Dihydrotestosterone / Q000494:pharmacology; D057809:HEK293 Cells; D006801:Humans; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008297:Male; D009132:Muscles / Q000187:drug effects / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011467:Prostate / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D044005:Tetrahydroisoquinolines / Q000494:pharmacology
chemical_list: D000728:Androgens; D015415:Biomarkers; D044005:Tetrahydroisoquinolines; D013196:Dihydrotestosterone; C031333:1-phenyl-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline; D000410:Alanine Transaminase