title: cDNA suppression subtraction library for screening down-regulated genes in gastric carcinoma.
abstract: OBJECTIVE
  To establish cDNA suppression subtraction library with a high subtraction efficiency by counterpart normal gastric mucosa mixture mRNA subtracting gastric cancer cells mixture mRNA for screening down-regulated genes in gastric carcinoma.
  
  
  METHODS
  RNA of gastric cancer tissues and counterpart normal gastric mucosa were respectively isolated in five patients with gastric cancer, and their mRNA was purified. cDNA suppression subtraction library was established by counterpart normal gastric mucosa mixture mRNA (tester) subtracting gastric cancer tissues mixture mRNA (driver) of five patients with gastric carcinoma. The library plasmids were transformed into competent bacteria DH5a after ligation of the library cDNA fragments with T vectors. Library plasmids were extracted after picking colonies and shaking bacteria overnight. Its subtraction efficiency was confirmed by PCR and reverse hybridization of a nylon filter onto which the colonies of bacteria were transferred with probes of reverse transcription products cDNA of gastric cancer tissues mRNA and counterpart normal gastric mucosa mRNA labeled with alpha- (32)P dCTP.
  
  
  RESULTS
  mRNA purified from total RNA of gastric cancer tissues and counterpart normal gastric mucosa in five patients with gastric carcinoma revealed a good quality. cDNA suppression subtraction library constructed for screening down-regulated genes in gastric carcinoma represented a high subtraction efficiency. 86 % of differential expression in down-regulated genes between counterpart normal gastric mucosa and gastric carcinoma was confirmed.
  
  
  CONCLUSIONS
  cDNA suppression subtraction library with a high subtraction efficiency for screening down-regulated genes in gastric carcinoma is successfully established.
authors.affiliation: Department of General Surgery, Xijing Hospital, The Fourth Military Medical University, Xian 710032, Shaanxi Province, China.
authors.forename: Jian-Jun
authors.initials: JJ
authors.lastname: Du
authors.forename: Ke-Feng
authors.initials: KF
authors.lastname: Dou
authors.forename: Shu-You
authors.initials: SY
authors.lastname: Peng
authors.forename: Hua-Sheng
authors.initials: HS
authors.lastname: Xiao
authors.forename: Wei-Zhong
authors.initials: WZ
authors.lastname: Wang
authors.forename: Wen-Xian
authors.initials: WX
authors.lastname: Guan
authors.forename: Zhong-Hua
authors.initials: ZH
authors.lastname: Wang
authors.forename: Zhi-Qing
authors.initials: ZQ
authors.lastname: Gao
authors.forename: Ying-Bin
authors.initials: YB
authors.lastname: Liu
mesh_terms: D003001:Cloning, Molecular; D015252:Deoxyribonucleases, Type II Site-Specific; D015536:Down-Regulation / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic; D015723:Gene Library; D005820:Genetic Testing / Q000379:methods*; D006801:Humans; D009693:Nucleic Acid Hybridization; D010957:Plasmids; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000235:genetics; D013274:Stomach Neoplasms / Q000235:genetics*
chemical_list: D012333:RNA, Messenger; D015252:Deoxyribonucleases, Type II Site-Specific; C040158:GTAC-specific type II deoxyribonucleases