Nuclear detection of Y-box protein-1 (YB-1) closely associates with progesterone receptor negativity and is a strong adverse survival factor in human breast cancer
Y-box binding protein-1 (YB-1) is the prototypic member of the cold shock protein family that fulfills numerous cellular functions. In the nucleus YB-1 protein orchestrates transcription of proliferation-related genes, whereas in the cytoplasm it associates with mRNA and directs translation.
In human tumor entities, such as breast, lung and prostate cancer, cellular YB-1 expression indicates poor clinical outcome, suggesting that YB-1 is an attractive marker to predict patients'prognosis and, potentially, is suitable to individualize treatment protocols. Given these predictive qualities of YB-1 detection we sought to establish a highly specific monoclonal antibody (Mab) for diagnostic testing and its characterization towards outcome prediction (relapse-free and overall survival).
Methods: Hybridoma cell generation was carried out with recombinant YB-1 protein as immunogen and Mab characterization was performed using immunoblotting and ELISA with recombinant and tagged YB-1 proteins, as well as immunohistochemistry of healthy and breast cancer specimens.
Breast tumor tissue array staining results were analyzed for correlations with receptor expression and outcome parameters.
Results: YB-1-specific Mab F-E2G5 associates with conformational binding epitopes mapping to two domains within the N-terminal half of the protein and detects nuclear YB-1 protein by immunohistochemistry in paraffin-embedded breast cancer tissues. Prognostic evaluation of Mab F-E2G5 was performed by immunohistochemistry of a human breast cancer tissue microarray comprising 179 invasive breast cancers, 8 ductal carcinoma in situ and 37 normal breast tissue samples.
Nuclear YB-1 detection in human breast cancer cells was associated with poor overall survival (p=0.0046). We observed a close correlation between nuclear YB-1 detection and absence of progesterone receptor expression (p=0.002), indicating that nuclear YB-1 detection marks a specific subgroup of breast cancer.
Likely due to limitation of sample size Cox regression models failed to demonstrate significance for nuclear YB-1 detection as independent prognostic marker.
Conclusions: Monoclonal YB-1 antibody F-E2G5 should be of great value for prospective studies to validate YB-1 as a novel biomarker suitable to optimize breast cancer treatment.
Author: Edgar DahlAbdelaziz En-NiaFrank WiesmannRenate KringsSonja DjudjajElisabeth BreuerThomas FuchsPeter WildArndt HartmannSandra DunnPeter Mertens
Credits/Source: BMC Cancer 2009, 9:410
Published on: 2009-11-24
Copyright by the authors listed above - made available via BioMedCentral (Open Access). Please
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