EZH-2 expression and its prognostic significance in patients with low - grade non-hodgkin lymphoma

EZH-2 Expression and Its Prognostic Significance in Patients with Low - grade Non-Hodgkin Lymphoma Background and Aim: Non-Hodgkin lymphoma (NHL) comprises a heterogeneous group of diseases with many subtypes and is characterized by uncontrolled proliferation of lymphocytes undergoing a malignant mutation. A significant increase in the incidence of lymphoma in the second half of the 20th century receives attention. The molecular pathogenesis of NHL is highly complex. Mutations in proto-oncogenes, epigenetic modifiers, and karyotypic abnormalities are common in NHL. One of these epigenetic factors, EZH2, is a functional enzymatic component of the polycomb repressive complex 2 (PRC2); which is involved in DNA methylation and transcriptional suppression. EZH2 overexpression or its mutation has been associated with various cancers. The phenylalanine mutation of tyrosine 641 in the active SET domain of EZH2 results in H3K27 trimethylation, which has been associated with lymphoma. In this study, we aimed to investigate EZH2 expression and its impact on prognosis in low-grade NHL patients. Material and Method: Our study included 141 patients with a pathologically confirmed diagnosis of indolent lymphoma, followed up in Çukurova University Faculty of Medicine in the period from 2009 to 2019. EZH2 expession is evaluated by immunohistochemistry. A subgroup analysis was performed based on the EZH2 expression level. Results: Of the study patients; 94 (66.7%) were males and 47 (33.3%) were females. The median age of the patients was 56±12,18 (28-87) years. The immunohistochemical demonstration of EZH2 revealed negative staining in 94 (66.7%) patients and positive staining in 47 (33.3%) patients. According to the EZH2 staining intensity; negative staining was observed in 102 (72.3%) patients and positive staining was observed in 39 (27.7%) patients. İn this study, we found that high EZH2 expression in patients with indolent NHL was associated with descreased overall survival. High EZH2 expression increased mortality risk by a factor of 2,2 for overall survival and 1,7 for PFS. It was found that strong EZH-2 expression was associated with shorter total and disease-free survival. Conclusion: The pathogenesis of epigenetic factors such as EZH2 is still under investigation. EZH2 has prognostic significance in low-grade NHL patients and has a significant impact on survival. Further large-scale studies are required to shed light on therapies targeting EZH2.