RESUMEN
<p><b>OBJECTIVE</b>To elucidate the possible mechanism of oral carcinogenesis and to explore the value of clinical application of the detection of cytokeratin (CK) 19 for oral squamous cell carcinoma (OSCC) patients.</p><p><b>METHODS</b>The cancerous tissues, para-cancerous tissues and excised lymph nodes were collected from 20 operated patients with OSCC. The patients didn't receive radiotherapy and chemotherapy before hospitalization. The relative expression of CK19 mRNA in those tissues was detected by fluorescent quantitative polymerase chain reaction (FQ-PCR).</p><p><b>RESULTS</b>The expression of CK19 mRNA in the cancerous tissues was 1.85 and 1.66 times higher than that in normal oral mucosa and in para-cancerous tissues, respectively. The expression of CK19 mRNA in lymph nodes from 9 patients with OSCC was positive and the positive rate was 45% (9/20). The positive rate of CK19 mRNA in all lymph nodes from 9 patients with OSCC was 81.8% (18/22), and the positive rate of CK19 mRNA in all lymph nodes from 20 patients with OSCC was 41.9%(18/43). CK19 mRNA level in the cancerous tissues relative to para-cancerous tissues and normal oral mucosa of the patients whose CK19 mRNA expression was positive was lower than that of the patients whose CK19 mRNA expression was negative in lymph nodes, respectively.</p><p><b>CONCLUSION</b>The possible reason that the expression of CK19 mRNA in the cancerous tissues was higher than that in para-cancerous tissues and normal oral mucosa was that the CK19 synthesis in cancerous tissues increased obviously. The detection of CK19 mRNA in lymph nodes was regarded probably as one of the markers for detecting OSCC micrometastasis in lymph nodes. The detection of CK19 mRNA in lymph nodes by FQ-PCR was more sensitive than hematoxylin-eosin staining in diagnosing OSCC micrometastasis.</p>