Antibody-based profiling of the phosphoinositide 3-kinase pathway in clinical prostate cancer

Clin Cancer Res. 2004 Dec 15;10(24):8351-6. doi: 10.1158/1078-0432.CCR-04-0130.


Purpose: As kinase inhibitors transition from the laboratory to patients, it is imperative to develop biomarkers that can be used in the clinic. The primary objectives are to identify patients most likely to benefit from molecularly targeted therapies and to document modulation of the drug target. Constitutive activation of the phosphoinositide 3-kinase (PI3K) pathway and its downstream effectors, as a result of PTEN loss or by other mechanisms, occurs in a high proportion of prostate cancers, making it an ideal template for the design of clinical trials involving PI3K pathway inhibitors. Prostate cancers also present unique organ-specific challenges, in that tumors are heterogeneous and diagnostic tissue is extremely limited.

Experimental design: Working within these limitations, we have developed a set of immunohistochemical assays that define activation of the PI3K pathway in clinical samples.

Results and conclusions: Using both univariate and multivariate analyses, we show that loss of PTEN is highly correlated with the activation of AKT, and this, in turn, is associated with the phosphorylation of S6, one of its main effectors. These three antibodies are potentially able to define a molecular signature of PTEN loss and/or AKT pathway activation in prostate cancer.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Antibodies, Monoclonal*
  • Down-Regulation
  • Enzyme Activation
  • Gene Expression Regulation, Enzymologic
  • Gene Expression Regulation, Neoplastic*
  • Humans
  • Male
  • PTEN Phosphohydrolase
  • Phosphatidylinositol 3-Kinases / metabolism*
  • Phosphoric Monoester Hydrolases / antagonists & inhibitors
  • Phosphoric Monoester Hydrolases / metabolism
  • Phosphorylation
  • Prostate / enzymology
  • Prostate / immunology
  • Prostate / pathology
  • Prostatic Neoplasms / enzymology*
  • Prostatic Neoplasms / immunology
  • Prostatic Neoplasms / pathology
  • Protein-Serine-Threonine Kinases / metabolism
  • Proto-Oncogene Proteins / metabolism
  • Proto-Oncogene Proteins c-akt
  • Ribosomal Protein S6 Kinases / metabolism
  • Signal Transduction*
  • Tumor Suppressor Proteins / antagonists & inhibitors
  • Tumor Suppressor Proteins / metabolism


  • Antibodies, Monoclonal
  • Proto-Oncogene Proteins
  • Tumor Suppressor Proteins
  • Phosphatidylinositol 3-Kinases
  • AKT1 protein, human
  • Protein-Serine-Threonine Kinases
  • Proto-Oncogene Proteins c-akt
  • Ribosomal Protein S6 Kinases
  • Phosphoric Monoester Hydrolases
  • PTEN Phosphohydrolase
  • PTEN protein, human