title: Reduced expression of PTEN and increased PTEN phosphorylation at residue Ser380 in gastric cancer tissues: a novel mechanism of PTEN inactivation.
abstract: OBJECTIVE
  PTEN is a tumor suppressor gene in different cancers. This study was to determine the protein expression of PTEN and phosphorylation of PTEN (p-PTEN) at residue Ser380 in different histology specimens of gastric tissues.
  
  
  METHODS
  A total of 179tissue specimens of normal gastric mucosa, chronic gastritis, intestinal metaplasia, dysplasia, and gastric cancer were recruited for immunohistochemical analysis of PTEN and p-PTEN expression. Four gastric cancer AGS, MKN-45, MKN-28, and SGC-7901 cell lines and a non-cancerous gastric GES-1 cell line were used to detect expression of PTEN and p-PTEN protein using Western blot.
  
  
  RESULTS
  Expression level of PTEN protein was significantly decreased in gastric cancer tissues compared to normal gastric mucosa, chronic gastritis, intestinal metaplasia and dysplasia (P<0.05). In contrast, p-PTEN protein level was significantly increased in intestinal metaplasia, dysplasia and gastric cancer compared to normal gastric mucosa and chronic gastritis (P<0.05). However, there was no any association of PTEN and p-PTEN expression with clinicopathological characteristics from gastric cancer patients. Moreover, the ratio of p-PTEN and PTEN was higher in gastric cancer cell lines than that of the non-malignant cells.
  
  
  CONCLUSIONS
  This study demonstrated that aberrant expression of PTEN and p-PTEN at residue Ser380 was early event that could contribute to gastric carcinogenesis, and that PTEN phosphorylation at residue Ser380 could be a mechanism for PTEN inactivation.
authors.affiliation: Department of Gastroenterology, The First Affiliated Hospital of Nanchang University, Nanchang, 330006 Jiangxi, PR China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Yang
authors.forename: Xiao-Gang
authors.initials: XG
authors.lastname: Yuan
authors.forename: Jiang
authors.initials: J
authors.lastname: Chen
authors.forename: Shi-Wen
authors.initials: SW
authors.lastname: Luo
authors.forename: Zhi-Jun
authors.initials: ZJ
authors.lastname: Luo
authors.forename: Nong-Hua
authors.initials: NH
authors.lastname: Lu
mesh_terms: D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D051059:PTEN Phosphohydrolase / Q000096:biosynthesis* / Q000378:metabolism*; D010766:Phosphorylation; D013274:Stomach Neoplasms / Q000235:genetics* / Q000378:metabolism*
chemical_list: D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human