Aberrant methylation of APC and Bikunin CpG islands in sporadic breast carcinomas / 中华预防医学杂志

<p><b>OBJECTIVE</b>To investigate relationship between methylation status of the APC and Bikunin CpG islands and clinicopathological characteristics of breast carcinomas.</p><p><b>METHODS</b>The methylation status of APC and Bikunin CpG islands in 152 sporadic breast carcinoma samples were analyzed by methylation specific PCR.</p><p><b>RESULTS</b>40.8% of breast carcinomas examined showed methylated signals for the APC. The methylation frequency of APC was significantly correlated to the tumor size (chi(2) = 4.041; P = 0.044), but not to patients' age, pathologic type of tumor, clinical stage, histological grade, lymph node metastasis and the status of estrogen or progestogen receptor. In addition, 24.6% of carcinoma samples examined revealed strong methylated signals for Bikunin. No significant correlation was found between the aberrant methylation of Bikunin and the clinicopathological characteristics of sporadic breast carcinomas.</p><p><b>CONCLUSION</b>The aberrant methylations of APC and Bikunin are frequent events during breast carcinogenesis. APC methylation might play a role in the progression of breast cancer.</p>

Quantification of methylation of SNCG CpG islands in human tissue samples by the combined COBRA-DHPLC assay / 中华预防医学杂志

<p><b>OBJECTIVE</b>To setup a quantitative assay for detection of methylation of SNCG CpG island in human tissue samples.</p><p><b>METHODS</b>Methylation status of the 16 tested CpG sites within the CpG island was analyzed by bisulfite-clone-sequencing for 2 gastric carcinoma cell lines, 2 normal gastric mucosa samples, and 2 pairs of primary gastric carcinomas and their corresponding non-neoplastic tissues, respectively.</p><p><b>RESULTS</b>The methylation of -88 and other four CpG sites was well correlated with the methylation of the overall CpG island. Thus, a combined bisulfite-restriction assay (COBRA) was developed based on the enzyme AciI, which digested the only one GCGG sequence in the PCR products of the methylated CpG island, but not the GTGG in the demethylated one. The digested fragments (144 bp and 85 bp) and undigested fragment (229 bp) could be completely separated by denaturing high performance liquid chromatography (DHPLC). According to the peak areas of these fragments, the proportion of the methylated copies of the SNCG CpG island was calculated easily. The result of the COBRA-DHPLC assay was reproducible and consistent with that of clone-sequencing.</p><p><b>CONCLUSION</b>A COBRA-DHPLC assay is setup successfully for quantification of methylation of the SNCG CpG island.</p>