title: Novel expression patterns of PI3K/Akt/mTOR signaling pathway components in colorectal cancer.
abstract: BACKGROUND
  The phosphatidylinositol 3-kinase/Akt/mammalian target of rapamycin (PI3K/Akt/mTOR) pathway plays a critical role in the growth and progression of colorectal cancer (CRC). The purpose of our study was 2-fold: (1) to determine the expression levels of several key components of this pathway, including p85alpha, Akt1, Akt2, p-mTOR(Ser2448), and p-p70S6K(Thr389) in CRCs; and (2) to correlate the expression of these proteins with cancer stage and location (left versus right side).
  
  
  METHODS
  Immunohistochemistry for p85alpha, Akt1, Akt2, p-mTOR(Ser2448), and p-p70S6K(Thr389) was performed on normal colon and CRCs from 154 patients.
  
  
  RESULTS
  All proteins investigated were significantly overexpressed in CRCs compared with matched normal colonic tissue from the same patient (p < 0.0001). PI3K pathway component proteins were moderately correlated across normal and malignant colon tissues; correlations tended to be stronger in normal tissues as compared with the same correlations in cancers. Expression levels of p85alpha were significantly higher in stage IV cancers than in stage I to III cancers (p = 0.0005). p85alpha expression was also significantly increased in the adjacent normal colonic mucosa of patients with stage IV CRC compared with earlier stages (p = 0.003). Finally, expression of Akt1, Akt2, and p-p70S6K(Thr389) was higher in left-sided CRCs compared with CRCs in the right colon (p = 0.007, p = 0.0008, and p = 0.04, respectively).
  
  
  CONCLUSIONS
  The PI3K/Akt/mTOR pathway components, p85alpha, Akt1, Akt2, p-mTOR(Ser2448), and p-p70S6K(Thr389) are highly overexpressed in CRCs, providing the rationale for targeting this pathway therapeutically in CRC patients. The increased expression of p85alpha in the adjacent normal mucosa of stage IV patients suggests an important field defect, which may contribute to the growth and progression of these cancers.
authors.affiliation: Department of Surgery, The University of Texas Medical Branch, Galveston, TX, USA.
authors.forename: Sara M
authors.initials: SM
authors.lastname: Johnson
authors.forename: Pat
authors.initials: P
authors.lastname: Gulhati
authors.forename: Bill A
authors.initials: BA
authors.lastname: Rampy
authors.forename: Yimei
authors.initials: Y
authors.lastname: Han
authors.forename: Piotr G
authors.initials: PG
authors.lastname: Rychahou
authors.forename: Hung Q
authors.initials: HQ
authors.lastname: Doan
authors.forename: Heidi L
authors.initials: HL
authors.lastname: Weiss
authors.forename: B Mark
authors.initials: BM
authors.lastname: Evers
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000378:metabolism; D016022:Case-Control Studies; D015331:Cohort Studies; D003110:Colonic Neoplasms / Q000201:enzymology* / Q000473:pathology / Q000601:surgery; D005260:Female; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D012004:Rectal Neoplasms / Q000201:enzymology* / Q000473:pathology / Q000601:surgery; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000378:metabolism*; D015398:Signal Transduction; D058570:TOR Serine-Threonine Kinases
chemical_list: D015415:Biomarkers; D047908:Intracellular Signaling Peptides and Proteins; D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D038762:Ribosomal Protein S6 Kinases, 70-kDa; D058570:TOR Serine-Threonine Kinases; C546842:MTOR protein, human; C448901:ribosomal protein S6 kinase, 70kD, polypeptide 1