title: [Improved sensitivity of gastric carcinoma cells to fluorouracil-related drugs by transfection of thymidine phosphorylase gene].
abstract: OBJECTIVE
  To investigate the relationship between the expression of thymidine phosphorylase (TP) and the sensitivity of gastric carcinoma to 5-fluorouracil (5-FU) and its prodrugs.
  
  
  METHODS
  Gastric carcinoma cell line AGS was transfected with recombinant plasmid pEGFP-N1-TP or control plasmid pEGFP-N1 by lipofectamin 2000. The expression of green fluorescence labeled protein was observed under fluorescence microscope. Positive clones AGS-p and AGS-pTP were selected by G418 treatment. Expression of TP protein and mRNA was detected by immunocytochemistry and RT-PCR, respectively. Drug sensitivity to 5-FU and its prodrugs was assessed by MTT assay.
  
  
  RESULTS
  Cell clones with the expression of green fluorescent protein (AGS-p) and a clone with TP and green fluorescent fusion protein (AGS-pTP) were established. Immunostaining of TP protein was strongly positive in AGS-pTP and negative in AGS-p and AGS. The expression of TP mRNA was significantly higher in AGS-pTP (0.8090 ± 0.0450) than that in AGS (0.0490 ± 0.0046) and AGS-p (0.0610 ± 0.0069; P < 0.01). The sensitivity to doxifluridine and capecitabine in AGS-pTP was significantly increased, as compared with that in AGS-p. IC50 values of AGS-pTP to doxifluridine and capecitabine were estimated 1.7 folds and 2.2 folds as much as that of AGS-p, respectively. The sensitivity to 5-FU was not different between AGS-pTP and AGS-p.
  
  
  CONCLUSIONS
  Enhancement of TP expression improves the sensitivity of gastric carcinoma cells to doxifluridine and capecitabine. But it does not affect the sensitivity to 5-FU.
authors.affiliation: Department of Pathology, Preclinical Medical College and Tumor Institute, Fujian Medical University, Fuzhou 350004, China.
authors.forename: Li-juan
authors.initials: LJ
authors.lastname: Zhuo
authors.forename: Mei-qin
authors.initials: MQ
authors.lastname: Gao
authors.forename: Ai-min
authors.initials: AM
authors.lastname: Huang
mesh_terms: D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology*; D000069287:Capecitabine; D045744:Cell Line, Tumor / Q000187:drug effects; D003841:Deoxycytidine / Q000031:analogs & derivatives / Q000494:pharmacology; D005467:Floxuridine / Q000494:pharmacology; D005472:Fluorouracil / Q000031:analogs & derivatives / Q000494:pharmacology*; D006801:Humans; D010957:Plasmids; D012333:RNA, Messenger / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012680:Sensitivity and Specificity; D013274:Stomach Neoplasms / Q000378:metabolism* / Q000473:pathology*; D013939:Thymidine Phosphorylase / Q000096:biosynthesis* / Q000235:genetics; D014162:Transfection
chemical_list: D000964:Antimetabolites, Antineoplastic; D012333:RNA, Messenger; D011994:Recombinant Proteins; D005467:Floxuridine; D003841:Deoxycytidine; D000069287:Capecitabine; D013939:Thymidine Phosphorylase; D005472:Fluorouracil; C025034:doxifluridine