Expression of epithelial to mesenchymal transition-related markers in lymph node metastases as a surrogate for primary tumor metastatic potential in breast cancer

• Main Authors: Markiewicz Aleksandra, Ahrends Tomasz, Wełnicka-Jaśkiewicz Marzena, Seroczyńska Barbara, Skokowski Jarosław, Jaśkiewicz Janusz, Szade Jolanta, Biernat Wojciech, Żaczek Anna J
• Format: Article
• Language: English
• Published: BMC 2012-11-01
• Series: Journal of Translational Medicine
• Subjects: Breast cancer; Primary tumor; Lymph node metastasis; Gene expression; Immunohistochemistry; Biomarkers; Epithelial-mesenchymal transition
• Online Access: http://www.translational-medicine.com/content/10/1/226

<p>Abstract</p> <p>Background</p> <p>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.</p> <p>Methods</p> <p>Formalin-fixed paraffin-embedded samples from PT and matched LNM from 42 stage II-III breast cancer patients were examined. Expression of <it>TWIST1</it>, <it>SNAIL</it> and <it>SLUG</it> 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.</p> <p>Results</p> <p>On average, mRNA expression of <it>TWIST1</it>, <it>SNAIL</it> and <it>SLUG</it> 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 <it>TWIST1</it> and <it>SNAIL</it> 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).</p> <p>Conclusions</p> <p>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.</p>