Increased level of phosphorylated akt measured by chemiluminescence-linked immunosorbent assay is a predictor of poor prognosis in primary breast cancer overexpressing ErbB-2.
BACKGROUND
Akt1, Akt2 and Akt3 kinases are downstream components of phosphoinositol 3-kinase derived signals from receptor tyrosine kinases, which influence cell growth, proliferation and survival. Akt2 overexpression and amplification have been described in breast, ovarian and pancreatic cancers. The present study was designed to investigate the prognostic significance of activated Akt in primary breast cancer and its association with other tumour biomarkers.


METHODS
Using a two-site chemiluminescence-linked immunosorbent assay, we measured the quantitative expression levels of total phosphorylated (P-S473) Akt (Akt1/Akt2/Akt3) on cytosol fractions obtained from fresh frozen tissue samples of 156 primary breast cancer patients.


RESULTS
Akt phosphorylation was not associated with nodal status or ErbB-2 protein expression levels. High levels of phosphorylated Akt correlated (P < 0.01) with poor prognosis, and the significance of this correlation increased (P < 0.001) in the subset of patients with ErbB-2 overexpressing tumours. In addition, phosphorylated Akt was found to be associated with mRNA expression levels of several proliferation markers (e.g. thymidylate synthase), measured using quantitative real-time RT-PCR.


CONCLUSIONS
Our findings demonstrate that, in breast cancer patients, Akt activation is associated with tumour proliferation and poor prognosis, particularly in the subset of patients with ErbB2-overexpressing tumours.
Cicenas
Jonas
J
Stiftung Tumorbank Basel, Basel, Switzerland. jonasc@scientist.ch
Urban
Patrick
P
Vuaroqueaux
Vincent
V
Labuhn
Martin
M
Küng
Willy
W
Wight
Edward
E
Mayhew
Mark
M
Eppenberger
Urs
U
Eppenberger-Castori
Serenella
S
D014408:Biomarkers, Tumor; D001943:Breast Neoplasms / Q000235:genetics* / Q000473:pathology*; D049109:Cell Proliferation; D003600:Cytosol / Q000201:enzymology; D005260:Female; D006801:Humans; D007118:Immunoassay; D008163:Luminescent Measurements; D010766:Phosphorylation; D011379:Prognosis; D051057:Proto-Oncogene Proteins c-akt / Q000096:biosynthesis* / Q000502:physiology; D012333:RNA, Messenger / Q000096:biosynthesis; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000096:biosynthesis*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016019:Survival Analysis; D015854:Up-Regulation
D014408:Biomarkers, Tumor; D051057:Proto-Oncogene Proteins c-akt; D012333:RNA, Messenger; D018719:Erb-b2 Receptor Tyrosine Kinases; C494918:AKT1 protein, human; C494921:AKT2 protein, human; C491754:AKT3 protein, human