title: Expression of phosphorylated-mTOR during the development of prostate cancer.
abstract: BACKGROUND
  The PI3K pathway plays a significant role in the progression of prostate cancer (PCa) to an advanced stage. Mouse models suggest that the downstream effector molecule of the PI3K pathway, mTOR, is also important in the development of PCa, where it plays a pivotal role in forming precursor lesions such as high grade prostatic intraepithelial neoplasia (HGPIN). This study was conducted to determine the status of phosphorylated-mTOR (p-mTOR the activated state of mTOR) across the PCa progression model by looking at expression in normal prostate tissue, proliferative inflammatory atrophy (PIA), HGPIN, and PCa.
  
  
  METHODS
  Expression of p-mTOR was evaluated by immunohistochemistry on tissue microarrays constructed from 120 archival formalin-fixed paraffin embedded radical prostatectomy tissue specimens. Levels of expression were recorded as the percentage of positive epithelial cells multiplied by the intensity of staining scored as 0-3.
  
  
  RESULTS
  p-mTOR expression was found to increase across the progression model with mean staining in non-neoplastic samples of 40 compared to 98 in PIA, 107 in HGPIN, and 136 in cancer (P < 0.001), but without significant increase between HGPIN and PIA. Correlation of high p-mTOR expression with outcome in PCa showed a trend towards worse prognosis, but this was not statistically significant.
  
  
  CONCLUSIONS
  This study demonstrates that p-mTOR signaling has a potential role in both the initiation and progression of PCa. These data provide support for further research into the possible use of rapamycin analogues in the treatment of PCa, and raise the possibility that mTOR might be a potential target for chemoprevention.
authors.affiliation: Department of Medical Oncology, Chris O'Brien Lifehouse, Sydney, New South Wales, Australia; Department of Medical Oncology, Royal Prince Alfred Hospital, Camperdown, New South Wales, Australia; Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia.
authors.forename: Sarah I M
authors.initials: SI
authors.lastname: Sutherland
authors.forename: Ruth
authors.initials: R
authors.lastname: Pe Benito
authors.forename: Susan M
authors.initials: SM
authors.lastname: Henshall
authors.forename: Lisa G
authors.initials: LG
authors.lastname: Horvath
authors.forename: James G
authors.initials: JG
authors.lastname: Kench
mesh_terms: D015331:Cohort Studies; D018450:Disease Progression; D005500:Follow-Up Studies; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D061986:MCF-7 Cells; D008297:Male; D010766:Phosphorylation / Q000235:genetics; D011471:Prostatic Neoplasms / Q000209:etiology / Q000235:genetics* / Q000473:pathology*; D058570:TOR Serine-Threonine Kinases / Q000096:biosynthesis / Q000235:genetics*
chemical_list: C546842:MTOR protein, human; D058570:TOR Serine-Threonine Kinases
keywords: atrophy; carcinoma; mTOR; prostate; prostatic intraepithelial neoplasia