A study on the correlation between DNA methylation and protein expression levels of SDC2 in patients with colorectal cancer and its clinicopathological significance

Purpose To investigate the association between Syndecan-2 gene methylation and protein expression dynamics in colorectal cancer and evaluate its clinicopathological significance. Methods We analyzed 197 tissues (96 colorectal cancer, 64 adenoma, and 37 normal tissues). Syndecan-2 methylation was quantified using quantitative methylation-specific polymerase chain reaction, and protein expression was evaluated via immunohistochemistry. Results Syndecan-2 methylation frequency was significantly higher in colorectal cancer (81.25%) and adenoma (64.06%) than in normal (5.41%) tissues. It showed high diagnostic accuracy for colorectal cancer (area under the curve = 0.88). Although methylation status was unrelated to most clinical parameters, higher methylation levels were correlated with poor tumor differentiation ( p = 0.022). Syndecan-2 protein was aberrantly expressed in tumor stroma but lacked clinical correlations. A significant positive correlation between methylation and protein expression was observed across the sample ( p < 0.05); however, this association was not maintained within the colorectal cancer subgroup specifically, showing no intrasample concordance (Kappa statistic = −0.046). Conclusion Syndecan-2 methylation serves as a highly sensitive epigenetic biomarker for the early detection of colorectal cancer. The findings reveal a complex and heterogeneous relationship between Syndecan-2 methylation and its protein expression during colorectal cancer progression, suggesting stage-specific regulatory mechanisms. Further multiomics studies are warranted to elucidate the underlying functional dynamics.