g., vimentin) and gain of a fibroblastoid morphology together with an increased invasive potential have been described in oral squamous cell carcinoma cell lines [17, 18]. Furthermore, down-regulation of E-cadherin expression has been recently associated with poor prognosis in oral squamous cell carcinoma patients [19]. Finally, transforming growth factor-β is considered as playing a key role in the epithelial-mesenchymal transition process as well [11–13]. In our previous study using a 4-nitroquinoline 1-oxide-induced rat tongue carcinoma model, we showed that the appearance

of SMF was closely associated with the development of carcinoma but not with pre-malignant lesions [20]. Furthermore, on an ultrastructural level, we showed that the carcinoma cells, but not their normal counterparts, acquired cytoplasmic microfilaments that were consistent with contractile microfilaments both in appearance

and organization [21]. These see more events reflect the morphological modifications occurring within the malignant cells, approaching smooth muscle differentiation, probably as part of the epithelial-mesenchymal transition process. The purpose of the present study was to examine the changes in the occurrence of SMF in tongue epithelial lesions with malignant potential (hyperplasia and dysplasia) and in squamous cell carcinoma, Microbiology inhibitor and to assess the expression of transforming growth factor-β in cases of carcinoma. In addition, we attempted to identify the presence of carcinoma cells that co-express epithelial

membrane antigen and α-smooth muscle actin as a reflection of the epithelial-mesenchymal transition process using a double immunostaining method, which was not previously reported in studies on oral cancer in this context. Materials and Methods Study Group Study Population Records of 22 cases of squamous cell carcinoma of the tongue and 39 cases of premalignant lesions of the tongue consisting of hyperplasia (N = 16), mild dysplasia (N = 12), and moderate-to-severe dysplasia (N = 11) were retrieved from the files of the Department of Oral Pathology, School of Dental Medicine, Tel-Aviv University and Idasanutlin ic50 Institute of Pathology, The Chaim Sheba Medical Center, Tel Hashomer. Diagnoses Thalidomide were reevaluated and classified by two oral pathologists (MV and DD) according to the World Health Organization classification of head and neck tumors [22]. This study was approved by the Helsinki committee of the Sheba Medical Center. Immunohistochemical Stains Three µ wide sections had been cut from the 61 blocks containing the biopsy specimens of the study cases. They were mounted on positive-charged microscope slides (OptiplusTM, Biogenex, San Ramon, CA, USA), dewaxed in xylene, dehydrated in ethanol, rinsed in distilled water, placed in 3% H2O2, and rinsed again in distilled water. The slides were placed in citrate buffer solution, pH=6, in a microwave oven at 92°C for 10 min for retrieval of antigens.