Utility of 5-Methylcytosine Immunohistochemical Staining to Assess Global DNA Methylation and Its Prognostic Impact in MDS Patients

Abstract

<br /> <strong><span style="font-size: small;">Background: </span></strong><span style="font-family: Times New Roman,Times New Roman; font-size: small;"><span style="font-family: Times New Roman,Times New Roman; font-size: small;">DNA methylation plays a vital role in the pathogenesis of the myelodysplastic syndrome (MDS), a heterogeneous group of clonal hematopoietic stem cell (HSC) disorders. It is reported to be an independent prognostic factor affecting overall survival (OS). Our aim was to analyze the role of global DNA methylation using an anti-5-methylcytosine (5-MC) antibody by immunohistochemistry (IHC) of bone marrow biopsy (BM Bx) specimens in MDS patients, assessing correlations with various clinical and biological prognostic factors. </span></span><strong><span style="font-size: small;">Material and methods: </span></strong><span style="font-family: Times New Roman,Times New Roman; font-size: small;" lang="JA"><span style="font-family: Times New Roman,Times New Roman; font-size: small;" lang="JA">A total of 59 MDS cases, classified as per the World Health Organization (WHO) 2008 guidelines, were evaluated </span></span><span style="font-family: Times New Roman,Times New Roman; font-size: small;"><span style="font-family: Times New Roman,Times New Roman; font-size: small;">over a period of 4 years. Clinical data were retrieved from departmental case records and anti-5-MC expression was </span></span><span style="font-family: Times New Roman,Times New Roman; font-size: small;" lang="JA"><span style="font-family: Times New Roman,Times New Roman; font-size: small;" lang="JA">analyzed with formalin fixed paraffin embedded sections of BM Bx specimens of MDS patients and controls. </span></span><strong><span style="font-size: small;">Results: </span></strong><span style="font-family: Times New Roman,Times New Roman; font-size: small;"><span style="font-family: Times New Roman,Times New Roman; font-size: small;">The median age at diagnosis was 52 years (15-85years). Patients were categorized into low risk (59%) and high risk (41%) according to International Prognostic Scoring System (IPSS). The median follow-up time was 10 months (1 to </span></span><span style="font-family: Times New Roman,Times New Roman; font-size: small;" lang="JA"><span style="font-family: Times New Roman,Times New Roman; font-size: small;" lang="JA">37 months). We generated a methylation score (M-score) using anti-5-MC and with the derived cut-off of 30.5 from the receiver operator curve (ROC), there was a significant difference between the two groups in the percentage of BM blasts (p=0.01), WHO sub-type (p=0.01), IPSS (p=0.004), progression to AML (p=0.04) on univariate analysis. Interestingly, patients showing a high M-score (M-score ≥ 30.5) demonstrated a significantly shorter OS and progression to AML. </span></span><span style="font-family: Times New Roman,Times New Roman; font-size: small;"><span style="font-family: Times New Roman,Times New Roman; font-size: small;">However, on multivariate analysis, only BM blasts (p=0.01) and IPSS (p=0.02) remained independent variables for progression to AML and OS respectively. </span></span><strong><span style="font-size: small;">Conclusion: </span></strong><span style="font-family: Times New Roman,Times New Roman; font-size: small;"><span style="font-family: Times New Roman,Times New Roman; font-size: small;">Immunostaining with anti-5-MC antibody with BM Bx samples is a simple and cost effective technique to detect global methylation, a powerful tool to predict overall survival in patients with MDS. </span></span>