Characterization of UGTs active against SAHA and association between SAHA glucuronidation activity phenotype with UGT genotype

Renee M. Balliet, Gang Chen, Caria J. Gallagher, Ryan W. Dellinger, Dongxiao Sun, Philip Lazarusw

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Abstract

Suberoylanilide hydroxamic acid (SAHA) is a histone deace-tylase inhibitor used in the treatment of cutaneous T-cell lymphoma and in clinical trials for treatment of multiple other cancers. A major mode of SAHA metabolism is by glucuronidation via the UDP-glucuronosyltransferase (UGT) family of enzymes. To characterize the UGTs active against SAHA, homogenates from HEK293 cell lines overexpressing UGT wild-type or variant UGT were used. The hepatic UGTs 2B17 and 1A9 and the extrahepatic UGTs IAS and IAlO exhibited the highest overall activity against SAHA as determined by Fmax/KM (16 ± 6.5, 7.1 ± 2.2, 33 ± 6.3, and 24 ± 2.4 nLmin-,-|i,g UGT protein-1, respectively), with UGT2B17 exhibiting the lowest KM (300 jxmoI/L) against SAHA of any UGT in vitro. Whereas the UGTlA8p.Alal73Gly variant exhibited a 3-fold (P < 0.005) decrease in glucuronidation activity against SAHA compared with wild-type UGT1A8, the UGTlA8p.Cys277Tyr variant exhibited no detectable glucur-onidation activity; a similar lack of detectable glucuronidation activity was observed for the UGTlA10p.Glyl39Lys variant. To analyze the effects of the UGT2B17 gene deletion variant (UGT2B17*2) on SAHA glucuronidation phenotype, human liver microsomes (HLM) were analyzed for glucuronidation activity against SAHA and compared with UGT2B17 genotype. HLM from subjects homozygous for UGT2B17*2 exhibited a 45% (P < 0.01) decrease in glucuronidation activity and 75% (P < 0.002) increase in KM compared with HLMs from subjects homozygous for the wild-type VGT2B17H allele. Overall, these results suggest that several UGTs play an important role in the metabolism of SAHA and that UGT2B17-null individuals could potentially exhibit altered SAHA clearance rates with differences in overall response.

Original languageEnglish (US)
Pages (from-to)2981-2989
Number of pages9
JournalCancer Research
Volume69
Issue number7
DOIs
StatePublished - Apr 1 2009

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All Science Journal Classification (ASJC) codes

  • Oncology
  • Cancer Research

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