Immunohistochemical evaluation of mesenchymal tumors in terms of epithelial - mesenchymal transition (EMT) and mesenchymal - epithelial transition (MET)

AIM: To investigate immunohistochemical expression of EMT/MET and associated markers among mesenchymal tumors together with their potential influence on biological characteristics of these tumors. MATERIALS AND METHODS: Mesenchymal tumor cases (n=527) and also carcinoma (n=28) and malignant melanoma (n=18) control groups were selected for our study. Sections from tissue microarrays of 3-4 mm diameter, were immunohistochemically stained with SLUG, TWIST1, E-cadherin, ZEB1, Beta-catenin, P-cadherin, TCF15 (PARAXIS) and ALDH1 by Leica Autostainer. Cases were grouped as METhigh, METlow and METneg according to their staining patterns with E-cadherin, SLUG and TWIST1. Differentiated and dedifferentiated foci of dedifferentiated liposarcomas (n=16), also primary and metastatic foci of sarcomas with nodal metasis (n=7) were compared. RESULTS: Mesenchymal tumors were classified as METhigh (%19), METlow (%71,1) and METneg (%9,8), tendency towards epithelial transition was dominantly present. P-cadherin expression was found in %8,9 of mesenchymal tumors and was present nearly only in sarcomas. %33,5 of cases were positive with ALDH1 with prominent expression among nerve sheath tumors (%73,7). Nuclear staining with beta-catenin was rare (%4,4) and membranous staining was %23,3. TCF15 expression was found in %13,4 of cases. No significant difference was noted between the differentiated and dedifferentiated foci of dedifferentiated liposarcomas or primary and metastatic foci of sarcomas with nodal metastasis in terms of any markers (p>0,05). ALDH1 is helpful in distinction between MPNST and monophasic synovial sarcoma (%59,1 vs. %9,5); also DSRCT and Ewing's sarcoma (%75 vs. %0). CONCLUSIONS: MET tendency is a frequent finding among mesenchymal tumors. Dedifferentiation or nodal metasis were unrelated to MET. Presence of P-cadherin only in sarcomas set us thinking on its potential role in tumor progression. Markers such as ALDH1 and E-cadherin could be useful in diffential diagnoses of mesenchymal neoplasms.