AML-137: Expression of Enhancer of Zeste 2 Polycomb Repressive Complex 2 Subunit Gene (EZH2) In Acute Myeloid Leukemia

Abstract

<h3>Background:</h3> Enhancer of Zeste Homolog 2 (EZH2) is the catalytic subunit of the chromatin-modifying enzyme polycomb group (PRC)2. As a complex, these proteins selectively silence target genes through trimethylation of histone H3 at lysine 27. EZH2 is strongly oncogenic. It has been observed in various malignancies, which makes it an interesting therapeutic target. Whether it function as a tumor suppressor or oncogene is not settled in acute myeloid leukemia (AML). <h3>Objective:</h3> This study was done to determine the relative expression level of <i>EZH2</i> in a cohort of Egyptian patients with adult newly diagnosed AML. <h3>Materials and Methods:</h3> The present study included 45 <i>de novo</i> AML and 40 healthy persons of matched age and sex as a control group. The following was performed on all patients: complete blood count, bone marrow examination, cytochemical and immunophenotyping studies, conventional cytogenetics, and hepatic and renal function tests. Detection of <i>EZH2</i> gene expression level by real-time quantitative polymerase chain reaction was done for all patients and controls. <h3>Results:</h3> The median age of our patients was 33 years. Males constituted 66.7% (30 patients) of our patients, and females constituted 33.3% (15 patients). The majority of our patients (71.1%, 32 patients) were M5. Cytogenetic studies revealed the presence of normal cytogenetic results in 28 (62.1%) patients. <i>EZH2</i> expression was lower in AML patients compared with controls (p <0.001). There was no difference in <i>EZH2</i> levels when considering age, sex, bone marrow blasts, cytogenetic study, or type or site of infection. Low <i>EZH2</i> expression was associated with higher mortality in 31(68.9%) patients and resistance to chemotherapy in 39 (86.6%) patients. <h3>Conclusions:</h3> From this study, we concluded that low <i>EZH2</i> is common in Egyptian AML patients. It functions as tumor suppressor gene, rather than an oncogene. Its presence is associated with resistance to chemotherapy and high mortality rate.