AUTHOR=Zhang Lianglu , Dong Lanlan , Lu Changming , Huang Wenxian , Yang Cuiping , Wang Qian , Wang Qian , Lei Ruixue , Sun Rui , Wan Kangkang , Li Tingting , Sun Fan , Gan Tian , Lin Jun , Yin Lei 

TITLE=Methylation of SDC2/TFPI2 and Its Diagnostic Value in Colorectal Tumorous Lesions

JOURNAL=Frontiers in Molecular Biosciences

VOLUME=8

YEAR=2021

URL=https://www.frontiersin.org/journals/molecular-biosciences/articles/10.3389/fmolb.2021.706754

DOI=10.3389/fmolb.2021.706754

ISSN=2296-889X

ABSTRACT=<p><bold>Background:</bold><italic>SDC2</italic> methylation is a feasible biomarker for colorectal cancer detection. Its specificity for colorectal cancer is higher than 90%, but the sensitivity is normally lower than 90%. This study aims to improve the sensitivity of <italic>SDC2</italic> detection through finding a high positive target from the false-negative samples of <italic>SDC2</italic> detection based on analysis of the bowel subsite difference in methylation.</p><p><bold>Methods:</bold> Hypermethylated <italic>TFPI2</italic> was identified in <italic>SDC2</italic> hypomethylated colorectal cancer samples retrieved from TCGA database with the methylation level lower than 0.2. The methylation-specific PCR assay was developed and then evaluated using tissue samples (184 cancer and 54 healthy control samples) and stool samples (289 cancer, 190 adenoma, and 217 healthy control samples).</p><p><bold>Results:</bold><italic>TFPI2</italic> was hypermethylated in most <italic>SDC2</italic> hypomethylated colorectal cancer samples. When the <italic>SDC2</italic>/<italic>TFPI2</italic>-combined PCR assay was performed in stool specimens, the AUC value of cancer vs. control was 0.98, with the specificity of 96.40% and sensitivity of 96.60%, and the AUC value of adenoma vs. control was 0.87, with the specificity of 95.70% and the sensitivity of 80.00%. The improvement in sensitivity was the most momentous in the left colon. As the detection index, the Ct value was better in improving the sensitivity of detection than the methylation level based on the 2<sup>−ΔΔCt</sup> value.</p><p><bold>Conclusion:</bold><italic>TFPI2</italic> can improve the sensitivity of <italic>SDC2</italic> methylation–specific detection of colorectal tumorous lesions while maintaining high specificity, in particular reducing the missed detection of left colon cancer and adenoma.</p>