title: Loss of PTEN expression is associated with colorectal cancer liver metastasis and poor patient survival.
abstract: BACKGROUND
  The tumour suppressor phosphatase and tensin homolog (PTEN) is an important negative regulator of cell-survival signaling. To evaluate the correlation between PTEN expression and clinicopathological characteristics of colorectal cancer patients with and without liver metastases, we investigated PTEN expression in primary colorectal cancer and colorectal cancer liver metastases.
  
  
  METHODS
  Sixty-nine pairs of primary colorectal cancer and corresponding liver metastasis specimens were analyzed immunohistochemically, and the correlation between immunohistochemical findings and clinicopathological factors was investigated. Seventy primary colorectal cancer specimens from patients without liver metastases were used as controls.
  
  
  RESULTS
  PTEN was strongly expressed in 44 (62.9%) colorectal cancer specimens from patients without liver metastases. In contrast, PTEN was weakly expressed in 52 (75.4%) primary colorectal cancer specimens from patients with liver metastases, and was absent in liver metastases. Weak PTEN expression in colorectal cancer tissues was significantly associated with advanced TNM stage (p < 0.01) and lymph node metastasis (p < 0.05). PTEN expression was significantly stronger in primary colorectal cancer specimens from patients without liver metastases. Furthermore, among colorectal cancer patients with liver metastases, the 5-year survival rate was significantly higher in patients with positive PTEN expression compared to those with negative PTEN expression (p = 0.012).
  
  
  CONCLUSIONS
  Our results suggest that loss of PTEN expression is involved with colorectal cancer aggressive capacity and that diagnostic evaluation of PTEN expression may provide valuable prognostic information to aid treatment strategies for colorectal cancer patients.
authors.affiliation: Department of Gastroenterological Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya 4678601, Japan. sawai@med.nagoya-cu.ac.jp
authors.forename: Hirozumi
authors.initials: H
authors.lastname: Sawai
authors.forename: Akira
authors.initials: A
authors.lastname: Yasuda
authors.forename: Nobuo
authors.initials: N
authors.lastname: Ochi
authors.forename: Jiachi
authors.initials: J
authors.lastname: Ma
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Matsuo
authors.forename: Takehiro
authors.initials: T
authors.lastname: Wakasugi
authors.forename: Hiroki
authors.initials: H
authors.lastname: Takahashi
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Funahashi
authors.forename: Mikinori
authors.initials: M
authors.lastname: Sato
authors.forename: Hiromitsu
authors.initials: H
authors.lastname: Takeyama
mesh_terms: D000368:Aged; D016022:Case-Control Studies; D015179:Colorectal Neoplasms / Q000175:diagnosis / Q000378:metabolism* / Q000473:pathology*; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008113:Liver Neoplasms / Q000175:diagnosis / Q000378:metabolism* / Q000556:secondary*; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D051059:PTEN Phosphohydrolase / Q000378:metabolism*; D011379:Prognosis; D015996:Survival Rate
chemical_list: D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human