ABSTRACT
<p><b>OBJECTIVE</b>To investigate the aberrant promoter methylation of hMLH1 gene promoter and its clinical significance in papillary thyroid cancer (PTC).</p><p><b>METHODS</b>methylation of hMLH1 gene promoter in the cancer tissue and matched tumor-adjacent normal tissue of 152 PTC patients were detected by real-time methylation specific PCR (qMSP). The relationship between the methylation of hMLH1 gene promoter and clinicopathological features was analyzed.</p><p><b>RESULTS</b>The methylation rate of hMLH1 gene promoter in cancer tissues was 37.5% (57/152), of which 33 cases were totally methylated and 24 cases were partially methylated. The methylation rate of adjacent normal tissues was 5.3% (8/152)(all were partially methylated). The methylation rate of PTC tissues was significantly higher than that in the tumor-adjacent normal tissue (P < 0.01). The promoter methylation of hMLH1 gene in PTC was significantly correlated with age, size and number of the primary lesion, local invasion, T stage and lymph node metastasis (P < 0.05) , but not correlated with gender and clinical stage (P > 0.05).</p><p><b>CONCLUSION</b>Promoter methylation of hMLH1 gene is a common molecular event in PTC tissue, and it is significantly correlated with the progression of PTC.</p>