title: Correlation of 18F-FLT uptake with equilibrative nucleoside transporter-1 and thymidine kinase-1 expressions in gastrointestinal cancer.
abstract: OBJECTIVE
  We examined equilibrative nucleoside transporter-1 (ENT1) and thymidine kinase-1 (TK1) messenger ribonucleic acid (mRNA) expressions in cancer tissue samples to elucidate the mechanism of 3'-deoxy-3'-F-fluorothymidine (FLT) uptake by positron emission tomography (PET) scan in gastrointestinal cancer.
  
  
  METHODS
  A total of 21 patients with newly diagnosed gastrointestinal cancer were examined with FLT PET. Tumor lesions were identified as areas of focally increased uptake, exceeding that of surrounding normal tissue. For semiquantitative analysis, the maximal standardized uptake value (SUV) was calculated. The expressions of ENT1 and TK1 in cancer tissue samples were compared with that of FLT SUV.
  
  
  RESULTS
  Of all gastrointestinal cancer lesions only one gastric cancer showed focally increased uptake of FLT PET. The mean (±standard deviation) FLT SUV in gastrointestinal cancer was 5.48±1.87. There was no significant correlation between FLT SUV and ENT1 (P=0.90) mRNA expression. There was a significant correlation between FLT SUV and TK1 mRNA expression (P<0.05).
  
  
  CONCLUSIONS
  Results of this preliminary study indicate that TK1 activity is an important determinant of FLT uptake in gastrointestinal cancer. In this study, it was found that ENT1 activity and FLT uptake were not related.
authors.affiliation: Department of Radiology, Faculty of Medicine, Kagawa University, Kagawa, Japan. reikok@med.kagawa-u.ac.jp
authors.forename: Reiko
authors.initials: R
authors.lastname: Kameyama
authors.forename: Yuka
authors.initials: Y
authors.lastname: Yamamoto
authors.forename: Kunihiko
authors.initials: K
authors.lastname: Izuishi
authors.forename: Takanori
authors.initials: T
authors.lastname: Sano
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Nishiyama
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001692:Biological Transport; D015224:Dideoxynucleosides / Q000378:metabolism*; D033721:Equilibrative Nucleoside Transporter 1 / Q000235:genetics*; D005260:Female; D005770:Gastrointestinal Neoplasms / Q000000981:diagnostic imaging / Q000235:genetics* / Q000378:metabolism*; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D011446:Prospective Studies; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013937:Thymidine Kinase / Q000235:genetics*
chemical_list: D015224:Dideoxynucleosides; D033721:Equilibrative Nucleoside Transporter 1; D012333:RNA, Messenger; D013937:Thymidine Kinase; C092717:thymidine kinase 1; C002854:alovudine