MicroRNA: A Signature for the Clinical Progression of Chronic Lymphocytic Leukemia

Abstract

Chronic lymphocytic leukemia (CLL) is the most common human leukemia. The disease is caused by abnormal proliferation and development of lymphocytes and their precursors in the blood and bone marrow (BM). Recent studies have shown that the CLL’s clinical course and outcome depend not only on genetic but also epigenetic factors. MicroRNAs (miRNAs) are involved in the development of hematological tumors, including CLL. The aim of this study is to identify the miRNA expression profile in CLL and determine the role of miRNAs in biological pathways associated with leukemogenesis in CLL. The following samples were used in this study: (1) samples obtained by sternal puncture and aspiration biopsy of BM (n = 115). They included samples from 21 CLL patients with anemia and indications for therapy and 45 CLL patients without anemia and with indications for therapy. The control group for the CLL BM samples consisted of patients with non-cancerous blood diseases (n = 35). (2) Lymph node (LN) samples (n = 20) were collected from CLL patients. The control group for the CLL LN samples consisted of patients with lymphadenopathy (n = 37). All cases were patients before treatment. We demonstrated a significant upregulation of miRNA-34a and miRNA-150 in CLL BM samples (p < 0.05) and downregulation of miRNA-451a in CLL LN samples (p < 0.05). We noted a dynamic increase in the levels of miRNA-150 and miRNA-34a in BM at various stages of tumor progression of CLL. We concluded that a dynamic picture of clinical manifestations of CLL closely correlates with changes in epigenetic characteristics of the tumor. Progression of the lymphoproliferative process and indications for cytoreductive therapy are associated with changes in the miRNA profile generated by cancer cells in different sites of clonal expansion.