Aberrant DNA methylation of the p57KIP2 gene is a sensitive biomarker for detecting minimal residual disease in diffuse large B cell lymphoma

The detection of minimal residual disease (MRD) in bone marrow is very important in the clinical management of malignant lymphoma. So far, the assessment of MRD in cases of diffuse large B cell lymphoma (DLBCL) has had some technical limitations, such as requiring patient-specific primers and complicated experimental steps. To resolve these problems, we applied a tumor-specific epigenetic alteration of the p57KIP2 gene as a biomarker for detecting MRD in DLBCL. The methylation of the p57KIP2 gene was analyzed in 63 cases of DLBCL by methylation-specific real-time quantitative PCR. Methylation of the p57KIP2 gene was detected in 53 (84.1%) of these 63 cases of DLBCL. We could detect one p57KIP2 gene-methylated cell among 10,000 unmethylated cells by the serial dilution experiment. This sensitivity is proved to be equivalent to that of detection of bcl2/IgH rearrangement by real-time quantitative PCR. This sensitivity could be converted to the detection of two methylated genomes per reaction. Using clinical material, the same results were confirmed. In this study, we established a convenient and universal method for detecting MRD in DLBCL. This technique is applicable for over 80% of patients with DLBCL. This could promote systemic MRD studies in the area of DLBCL.