We compared the immunoexpression of 5 myoepithelial cell (MEC) markers (asmooth-muscle actin, calponin, h-caldesmon, vimentin, and S-100-protein) using 16 pleomorphic adenomas (PA), 15 adenoid cystic carcinomas (ACC), and 3 epithelialmyoepithelial carcinomas (EMC) of salivary glands. The cx-smooth-muscle actin was useful for identification of MECs, especially in cribriform and tubular ACC, followed by EMC. Calponin was similar to ct-smooth-muscle actin, except for polygonal and plasmacytoid cells of PA and for solid ACC, which showed a-smooth-muscle actin negative and calponin positive. H-caldesmon was negative. Vimentin immunostained all MEC types, and was negative in luminal cells. S-100 protein was expressed both in the nuclei and cytoplasm of MECs and luminal cells, especially in PA. The best way to identify MEC is using a-smooth-muscle actin or calponin, plus vimentin, since in tumors MECs are hardly ever fully differentiated.

Some oral cancers are known to develop from dysplastic oral epithelium. In the present study, the expression of c-Jun, c-Fos, and cyclin D1 proteins in oral epithelial lesions with different degrees of dysplasia, and in oral squamous cell carcinomas (OSCCs) was evaluated. Eighteen cases of mild dysplasia, 23 cases of moderate to severe dysplasia and 24 OSCCs were studied immunohistochemically. Additionally, 15 sections of oral mucosa without any evidence of dysplasia were included in the study. Results: c-Jun expression increased according to the degree of oral dysplasia, with the greatest expression found in OSCC. c-Fos expression was intense in normal mucosa, reduced in mild dysplasia and high in moderate to severe dysplasia and in OSCCs. Cyclin D1 was expressed in only a few cases of moderate to severe dysplasia and in most of the OSCCs. Statistical analysis showed a correlation between the three proteins and the degree of epithelial alteration. The present results indicate a possible role of c-Jun and c-Fos in malignant transformation of oral mucosa. (J. Oral Sci. 47, 71-76, 2005)