Expression of epithelial to mesenchymal transition-related markers in lymph node metastases as a surrogate for primary tumor metastatic potential in breast cancer
- Equal contributors
1 Laboratory of Cell Biology, Department of Medical Biotechnology, Intercollegiate Faculty of Biotechnology, University of Gdańsk and Medical University of Gdańsk, Dębinki 1, Gdańsk, 80-211, Poland
2 Postgraduate School of Molecular Medicine, Medical University of Warsaw, Warsaw, Poland
3 Department of Oncology and Radiotherapy, Medical University of Gdańsk, Dębinki 7, Gdańsk, 80-211, Poland
4 Bank of Frozen Tissues and Genetic Specimen, Medical University of Gdańsk, Dębinki 1, Gdańsk, 80-211, Poland
5 Department of Surgical Oncology, Medical University of Gdańsk, Smoluchowskiego 17, Gdańsk, 80-214, Poland
6 Department of Pathomorphology, Medical University of Gdańsk, Smoluchowskiego 17, Gdańsk, 80-214, Poland
Journal of Translational Medicine 2012, 10:226 doi:10.1186/1479-5876-10-226Published: 19 November 2012
Breast cancers are phenotypically and genotypically heterogeneous tumors containing multiple cancer cell populations with various metastatic potential. Aggressive tumor cell subpopulations might more easily be captured in lymph nodes metastases (LNM) than in primary tumors (PT). We evaluated mRNA and protein levels of master EMT regulators: TWIST1, SNAIL and SLUG, protein levels of EMT-related markers: E-cadherin, vimentin, and expression of classical breast cancer receptors: HER2, ER and PgR in PT and corresponding LNM. The results were correlated with clinicopathological data and patients outcomes.
Formalin-fixed paraffin-embedded samples from PT and matched LNM from 42 stage II-III breast cancer patients were examined. Expression of TWIST1, SNAIL and SLUG was measured by reverse-transcription quantitative PCR. Protein expression was examined by immunohistochemistry on tissue microarrays. Kaplan-Meier curves for disease-free survival (DFS) and overall survival (OS) were compared using F-Cox test. Hazard ratios (HRs) with 95% confidence intervals (95% CI) were computed using Cox regression analysis.
On average, mRNA expression of TWIST1, SNAIL and SLUG was significantly higher in LNM compared to PT (P < 0.00001 for all). Gene and protein levels of TWIST1, SNAIL and SLUG were highly discordant between PT and matched LNM. Increased mRNA expression of TWIST1 and SNAIL in LNM was associated with shorter OS (P = 0.04 and P = 0.02, respectively) and DFS (P = 0.02 and P = 0.01, respectively), whereas their expression in PT had no prognostic impact. Negative-to-positive switch of SNAIL protein correlated with decreased OS and DFS (HR = 4.6; 1.1-18.7; P = 0.03 and HR = 3.8; 1.0-48.7; P = 0.05, respectively).
LNM are enriched in cells with more aggressive phenotype, marked by elevated levels of EMT regulators. High expression of TWIST1 and SNAIL in LNM, as well as negative-to-positive conversion of SNAIL confer worse prognosis, confirming the correlation of EMT with aggressive disease behavior. Thus, molecular profiling of LNM may be used as surrogate marker for aggressiveness and metastatic potential of PT.