The Clinical and Prognostic Significance of Ribonucleotide Reductase Subunits RRM1 and RRM2 mRNA Levels in Patients with Chronic Lymphocytic Leukemia

Ribonucleotide Reductase (RNR) converts ribonucleotides to deoxyribonucleotides required for DNA replication and repair. RNR consists of subunits M1 and M2. It has been studied as a prognostic factor in several solid tumors and in chronic hematological malignancies, but not in chronic lymphocytic leukemia (CLL). Peripheral blood samples were collected from 135 CLL patients. M1/M2 gene mRNA levels were measured and expressed as a RRM1-2/GAPDH ratio. M1 gene promoter methylation was studied in a patients’ subgroup. M1 mRNA expression was higher in patients without anemia (p = 0.026), without lymphadenopathy (p = 0.005) and 17p gene deletion (p = 0.031). Abnormal LDH (p = 0.022) and higher Rai stage (p = 0.019) were associated with lower M1 mRNA levels. Higher M2 mRNA levels were found in patients without lymphadenopathy (p = .048), Rai stage 0 (p = 0.025) and Trisomy 12 (p = 0.025). The correlation between RNR subunits and clinic-biological characteristics in CLL patients demonstrate RNR’s potential role as a prognostic factor.