Poor prognosis in carcinoma is associated with a gene expression signature of aberrant PTEN tumor suppressor pathway activity.
Pathway-specific therapy is the future of cancer management. The oncogenic phosphatidylinositol 3-kinase (PI3K) pathway is frequently activated in solid tumors; however, currently, no reliable test for PI3K pathway activation exists for human tumors. Taking advantage of the observation that loss of PTEN, the negative regulator of PI3K, results in robust activation of this pathway, we developed and validated a microarray gene expression signature for immunohistochemistry (IHC)-detectable PTEN loss in breast cancer (BC). The most significant signature gene was PTEN itself, indicating that PTEN mRNA levels are the primary determinant of PTEN protein levels in BC. Some PTEN IHC-positive BCs exhibited the signature of PTEN loss, which was associated to moderately reduced PTEN mRNA levels cooperating with specific types of PIK3CA mutations and/or amplification of HER2. This demonstrates that the signature is more sensitive than PTEN IHC for identifying tumors with pathway activation. In independent data sets of breast, prostate, and bladder carcinoma, prediction of pathway activity by the signature correlated significantly to poor patient outcome. Stathmin, encoded by the signature gene STMN1, was an accurate IHC marker of the signature and had prognostic significance in BC. Stathmin was also pathway-pharmacodynamic in vitro and in vivo. Thus, the signature or its components such as stathmin may be clinically useful tests for stratification of patients for anti-PI3K pathway therapy and monitoring therapeutic efficacy. This study indicates that aberrant PI3K pathway signaling is strongly associated with metastasis and poor survival across carcinoma types, highlighting the enormous potential impact on patient survival that pathway inhibition could achieve.
Saal
Lao H
LH
Institute for Cancer Genetics, Columbia University, New York, NY 10032, USA.
Johansson
Peter
P
Holm
Karolina
K
Gruvberger-Saal
Sofia K
SK
She
Qing-Bai
QB
Maurer
Matthew
M
Koujak
Susan
S
Ferrando
Adolfo A
AA
Malmström
Per
P
Memeo
Lorenzo
L
Isola
Jorma
J
Bendahl
Pär-Ola
PO
Rosen
Neal
N
Hibshoosh
Hanina
H
Ringnér
Markus
M
Borg
Ake
A
Parsons
Ramon
R
D014408:Biomarkers, Tumor; D002277:Carcinoma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D051059:PTEN Phosphohydrolase / Q000235:genetics / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism; D011379:Prognosis; D015398:Signal Transduction; D015996:Survival Rate; D016896:Treatment Outcome
D014408:Biomarkers, Tumor; D019869:Phosphatidylinositol 3-Kinases; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human