DNA methylation consistency implicates the primary tumor cell origin of recurrent hepatocellular carcinoma

Aims: To investigate if DNA methylation pattern assay could be a new approach to identifying the primary tumor cell origin of the recurrent hepatocellular carcinoma (HCC). Materials & Methods: Methylation of 24 genes and expression of 22 cancer stem cell (CSC) biomarkers were quantitatively measured in 10 paired primary and recurrent HCC specimens. The HBV viral–host junctions were determined in six pairs of them with HBV infection. Results: Similar DNA methylation patterns were observed among nine of ten pairs of primary and recurrent tumors. In five of six paired specimens with HBV infection, exactly same HBV DNA integrations were identified in each paired tumors. The expression of seven CSC biomarkers increased significantly in either primary or recurrent tumor tissues. Conclusion: Recurrent HCCs mostly originate from their primary tumors. Assay of DNA methylation patterns could provide a new approach to determining the origin of recurrent HCC.