title: PCR-SSCP-DNA sequencing method in detecting PTEN gene mutation and its significance in human gastric cancer.
abstract: OBJECTIVE
  To discuss the possible effect of PTEN gene mutations on occurrence and development of gastric cancer.
  
  
  METHODS
  Fifty-three gastric cancer specimens were selected to probe PTEN gene mutations in genome of gastric cancer and paracancerous tissues using PCR-SSCP-DNA sequencing method based on microdissection and to observe the protein expression by immunohistochemistry technique.
  
  
  RESULTS
  PCR-SSCP-DNA sequencing indicated that 4 kinds of mutation sites were found in 5 of 53 gastric cancer specimens. One kind of mutation was found in exons. AA-TCC mutation was located at 40 bp upstream of 3' lateral exon 7 (115946 AA-TCC). Such mutations led to terminator formation in the 297th codon of the PTEN gene. The other 3 kinds of mutation were found in introns, including a G-C point mutation at 91 bp upstream of 5' lateral exon 5(90896 G-C), a T-G point mutation at 24 bp upstream of 5' lateral exon 5 (90963 T-G), and a single base A mutation at 7 bp upstream of 5' lateral exon 5 (90980 A del). The PTEN protein expression in gastric cancer and paracancerous tissues detected using immunohistochemistry technique indicated that the total positive rate of PTEN protein expression was 66% in gastric cancer tissue, which was significantly lower than that (100%) in paracancerous tissues (P < 0.005).
  
  
  CONCLUSIONS
  PTEN gene mutation and expression may play an important role in the occurrence and development of gastric cancer.
authors.affiliation: Department of Gastroenterology, Tenth People's Hospital of Tongji University, Shanghai, China. guochuanyong@hotmail.com
authors.forename: Chuan-Yong
authors.initials: CY
authors.lastname: Guo
authors.forename: Xuan-Fu
authors.initials: XF
authors.lastname: Xu
authors.forename: Jian-Ye
authors.initials: JY
authors.lastname: Wu
authors.forename: Shu-Fang
authors.initials: SF
authors.lastname: Liu
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001483:Base Sequence; D005091:Exons / Q000235:genetics; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation / Q000235:genetics*; D051059:PTEN Phosphohydrolase / Q000235:genetics*; D016133:Polymerase Chain Reaction; D018807:Polymorphism, Single-Stranded Conformational; D017422:Sequence Analysis, DNA; D013274:Stomach Neoplasms / Q000235:genetics*
chemical_list: D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human