Phosphorylation of Akt (Ser473) is an excellent predictor of poor clinical outcome in prostate cancer

Jeffrey I. Kreisberg, Shazli N. Malik, Thomas J. Prihoda, Roble G. Bedolla, Dean A. Troyer, Suzanne Kreisberg, Paramita M Ghosh

Research output: Contribution to journalArticlepeer-review

286 Scopus citations


We previously showed, by immunohistochemistry with phospho-specific antibodies, increased phosphorylation (activation) of Akt (Ser473) [phosphorylated Akt (pAkt)] in high-Gleason grade prostate cancer (Malik SN, et al., Clin Cancer Res 2002;8:1168-71). Elevation of pAkt was accompanied by decreased phosphorylation of extracellular signal-regulated kinase (ERK) 1/2 (Thr202/Tyr204) [phosphorylated ERK (pERK)], indicative of inactivation. In this report, we determined whether increased pAkt and decreased pERK predicted clinical outcome. Prostate-specific antigen (PSA) failure (detectable and rising PSA) versus PSA non-failure (undetectable PSA 5 years after prostatectomy) was used as a surrogate for clinical outcome. Prostate tumors from cases of PSA failure versus non-failure were stained for pAkt and pERK. A significant increase in mean pAkt staining (P < 0.001) in the PSA failures versus non-failures was seen based on the Wilcoxon signed ranks test [222.18 ± 33.9 (n = 37) versus 108.79 ± 104.57 (n = 16)]. Using the best-fitting multiple logistic regression equation, a 100-point increase in pAkt staining resulted in a 160% increase in the odds of being a PSA failure. There was decreased staining for pERK in PSA failures versus non-failures: a 100-point decrease resulted in an 80% increase in the odds of being a PSA failure. Each of these effects assumed the other biomarker was held constant. The area under the receiver-operating characteristic curve for these two biomarkers predicting PSA failure was 0.84, indicating excellent discrimination between PSA failure and non-failure cases. These data indicate that increased pAkt, alone or together with decreased pERK, is an important predictor of probability of PSA failure. However, pERK alone was not a significant predictor of PSA failure.

Original languageEnglish (US)
Pages (from-to)5232-5236
Number of pages5
JournalCancer Research
Issue number15
StatePublished - Aug 1 2004
Externally publishedYes

ASJC Scopus subject areas

  • Cancer Research
  • Oncology


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