title: A comprehensive analysis of phosphatase and tensin homolog deleted on chromosome 10 (PTEN) loss in colorectal cancer.
abstract: BACKGROUND
  Alterations of PTEN, regulator of the PTEN/PI3K-AKT pathway, are common in several types of cancer. This study aimed to do comprehensive analysis of PTEN in colorectal cancer patients.
  
  
  METHODS
  Totally, 198 colorectal cancer patients who received surgery at Taipei Veterans General Hospital from 2006 to 2008 were enrolled. Mutations, loss of protein expression, promoter hypermethylation, and DNA copy number of PTEN were analyzed by sequencing, immunohistochemistry, methylation-specific polymerase chain reaction PCR, and quantitative (QPCR), respectively, and correlated with clinicopathological features and patients' outcome.
  
  
  RESULTS
  Genomic mutations, loss of protein expression, promoter hypermethylation, and decreased DNA copy number of PTEN were found in 4 (2.02 %), 68 (34.3 %), 54 (27.3 %), and 36 (18.2 %) tumors, respectively. Of these 68 tumors with loss expression of PTEN, 34 (50 %) tumors had promoter methylation and 18 (26.5 %) had decreased DNA copy number. All four tumors with PTEN mutations demonstrated loss of PTEN expression. In the stage I disease, frequency of loss of PTEN expression was 20 % and significantly increased to 56.9 % in stage IV disease. Either loss expression of PTEN, PTEN hypermethylation or decreased PTEN copy number was not associated with colorectal cancer (CRC) patients' outcome.
  
  
  CONCLUSIONS
  PTEN alterations were found in up to one-third of colorectal cancers but did not impact CRC patients' prognosis.
authors.affiliation: Department of Clinical Pathology, Yang-Ming Branch, Taipei City Hospital, Taipei, Taiwan. b7901127@tmu.edu.tw.
authors.forename: Pei-Ching
authors.initials: PC
authors.lastname: Lin
authors.affiliation: Division of Colon and Rectal Surgery, Department of Surgery, Taipei Veterans General Hospital, No.201, 2nd section, ShiPai Road, Taipei, Taiwan. jklin@vghtpe.gov.tw.|Faculty of Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan. jklin@vghtpe.gov.tw.
authors.forename: Jen-Kou
authors.initials: JK
authors.lastname: Lin
authors.affiliation: Division of Colon and Rectal Surgery, Department of Surgery, Taipei Veterans General Hospital, No.201, 2nd section, ShiPai Road, Taipei, Taiwan. hhlin7@vghtpe.gov.tw.|Faculty of Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan. hhlin7@vghtpe.gov.tw.
authors.forename: Hung-Hsin
authors.initials: HH
authors.lastname: Lin
authors.affiliation: Division of Colon and Rectal Surgery, Department of Surgery, Taipei Veterans General Hospital, No.201, 2nd section, ShiPai Road, Taipei, Taiwan. ytlan@vghtpe.gov.tw.|Faculty of Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan. ytlan@vghtpe.gov.tw.
authors.forename: Yuan-Tzu
authors.initials: YT
authors.lastname: Lan
authors.affiliation: Division of Colon and Rectal Surgery, Department of Surgery, Taipei Veterans General Hospital, No.201, 2nd section, ShiPai Road, Taipei, Taiwan. cclin15@vghtpe.gov.tw.|Faculty of Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan. cclin15@vghtpe.gov.tw.
authors.forename: Chun-Chi
authors.initials: CC
authors.lastname: Lin
authors.affiliation: Division of Colon and Rectal Surgery, Department of Surgery, Taipei Veterans General Hospital, No.201, 2nd section, ShiPai Road, Taipei, Taiwan. yangsh@vghtpe.gov.tw.|Faculty of Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan. yangsh@vghtpe.gov.tw.
authors.forename: Shung-Haur
authors.initials: SH
authors.lastname: Yang
authors.affiliation: Division of Colon and Rectal Surgery, Department of Surgery, Taipei Veterans General Hospital, No.201, 2nd section, ShiPai Road, Taipei, Taiwan. wschen@vghtpe.gov.tw.|Faculty of Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan. wschen@vghtpe.gov.tw.
authors.forename: Wei-Shone
authors.initials: WS
authors.lastname: Chen
authors.affiliation: Faculty of Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan. wyliang@vghtpe.gov.tw.|Department of Pathology, Taipei Veterans General Hospital, Taipei, Taiwan. wyliang@vghtpe.gov.tw.
authors.forename: Wen-Yi
authors.initials: WY
authors.lastname: Liang
authors.affiliation: Division of Colon and Rectal Surgery, Department of Surgery, Taipei Veterans General Hospital, No.201, 2nd section, ShiPai Road, Taipei, Taiwan. jkjiang@vghtpe.gov.tw.|Faculty of Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan. jkjiang@vghtpe.gov.tw.
authors.forename: Jeng-Kai
authors.initials: JK
authors.lastname: Jiang
authors.affiliation: Division of Colon and Rectal Surgery, Department of Surgery, Taipei Veterans General Hospital, No.201, 2nd section, ShiPai Road, Taipei, Taiwan. changsc@vghtpe.gov.tw.|Faculty of Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan. changsc@vghtpe.gov.tw.
authors.forename: Shih-Ching
authors.initials: SC
authors.lastname: Chang
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015179:Colorectal Neoplasms / Q000235:genetics*; D056915:DNA Copy Number Variations; D019175:DNA Methylation; D004252:DNA Mutational Analysis; D004273:DNA, Neoplasm / Q000235:genetics; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D051059:PTEN Phosphohydrolase / Q000235:genetics*; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA
chemical_list: D004273:DNA, Neoplasm; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human