title: [Correlation between enzymatic activity and gene expression of orotate phosphoribosyl transferase (OPRT) in colorectal cancer].
abstract: BACKGROUND
  Orotate phosphoribosyl transferase (OPRT) is the initial key enzyme in the 5-FU metabolic pathway. It is an enzyme that converts 5-fluorouracil into 5-fluorouridine monophosphate. We have previously shown that there is a strong positive correlation between OPRT activity and the antitumor effects of 5-FU. In this study, we investigated the correlation between OPRT activity and mRNA expression levels of OPRT in 10 colorectal tumors.
  
  
  METHODS
  Activity was measured by radioassay in tissues. mRNA expression levels (OPRT/beta-actin) were measured by TaqMan PCR assay in the same tissues.
  
  
  RESULTS
  There was no correlation between OPRT activity and mRNA expression levels (r = -0.4301, p = 0.8926).
  
  
  CONCLUSIONS
  The absolute amount of an enzyme is determined by speed of synthesis (kappa s) and degradation (kappa deg). OPRT is thought to be a constitutive enzyme, and the results of this study show that it is difficult to estimate the OPRT activity from mRNA expression levels.
  
  
  CONCLUSIONS
  Further studies are necessary to develop techniques to measure OPRT activity in biopsies, in order to establish tailor-made therapies based on estimating the antitumor effect of 5-FU from OPRT, an enzyme related to 5-FU metabolism.
authors.affiliation: Dept. of Surgery, Toubu Chiiki Hospital, Tokyo Metropolitan Health and Medical Treatment Corporation.
authors.forename: Ochiai
authors.initials: O
authors.lastname: Takumi
authors.forename: Sugitani
authors.initials: S
authors.lastname: Michiharu
authors.forename: Nishimura
authors.initials: N
authors.lastname: Kazuhiko
authors.forename: Noguchi
authors.initials: N
authors.lastname: Hajime
authors.forename: Okada
authors.initials: O
authors.lastname: Tsuyoshi
authors.forename: Suda
authors.initials: S
authors.lastname: Sumito
authors.forename: Kamiyama
authors.initials: K
authors.lastname: Hirohiko
authors.forename: Isao
authors.initials: I
authors.lastname: Nagaoka
mesh_terms: D000368:Aged; D015179:Colorectal Neoplasms / Q000201:enzymology*; D005260:Female; D015870:Gene Expression; D006801:Humans; D008297:Male; D008875:Middle Aged; D009962:Orotate Phosphoribosyltransferase / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism
chemical_list: D012333:RNA, Messenger; D009962:Orotate Phosphoribosyltransferase