RESUMO
<p><b>OBJECTIVE</b>To evaluate the expression of cytokeratin 19(CK19) and connexin 43(Cx43) in various stages of oral carcinogenesis and investigate the relationship of CK19 and Cx43 in the process of oral cancer.</p><p><b>METHODS</b>4-nitroquinoline-1-oxide(4NQO) was used to induce oral carcinogenesis in the mucosa of SD rats and immunohistoche-mical technique was used to study the expression of CK19 and Cx43 in various stages of oral carcinogenesis.</p><p><b>RESULTS</b>The CK19 positive staining were distributed in the basal cell layer in the normal rat lingual mucosa. While CK19 positive staining were distributed in cytoplasm of supra-basal layers in the mild dysplasia, moderate dysplasia and severe dysplasia. In oral squamous cell carcinoma(OSCC) tissue, CK19 were expressed in all the stratum of epithelium. The positive rate of CK19 in normal, mild, moderate, severe dysplasia and OSCC tissues were respectively 30.00%, 50.00%, 58.33%, 80.00%, and 91.67%. With the lesions getting worse, the positive rate and the intensity of CK19 raised significantly (P<0.05). In normal tongue mucosa, Cx43 proteins were mainly expressed in the membrane of the epithelial cells of the rat tongue. It was weakly positive in the basal cell layer, increased in the stratum spinosum and stratum granulosum, and negative in the stratum corneum. Compared with normal epithelia, the expression of Cx43 in dysplastic and OSCC epithelia decreased significantly. The positive rate of Cx43 in normal, mild, moderate, severe dysplasia and OSCC tissues were respectively 100.00%, 85.71%, 66.67%, 40.00%, and 33.33%. The expression of Cx43 was significantly decreased with severity increasing (P<0.05).</p><p><b>CONCLUSION</b>The expression of CK19 protein significantly increases with the development of rat tongue carcinoma, suggesting that CK19 is associated with carcinogenesis. The expression of Cx43 protein dramatically decrease with the development of rat tongue carcinoma, suggesting that the abnormal expression of Cx43 protein is associated with oral mucosa carcinoma origination. The expression of CK19 and Cx43 has negative correlation. Combined detection of CK19 and Cx43 has an important role in the early diagnosis of OSCC and can help to improve the sensitivity and specificity of the early diagnosis of OSCC.</p>