Aims and background: To investigate the expressions of TET2 mRNA in bone marrow CD3(+) and CD34(+) cells of the patients with myelodysplastic syndromes (MDS) and to study the effect of silencing TET2 by small interfering RNA (siRNA) on the biological characteristics of CD34(+) cells.
Methods: CD3(+) and CD34(+) cells were sorted by magnetic activated cell-sorting system from bone marrow of MDS patients and controls. The mRNA expressions of TET2 in bone marrow CD3(+) and CD34(+) cells of 28 MDS patients and 20 controls were detected by qPCR. The silencing effect of RNA interference (RNAi) on TET2 expression in CD34(+) bone marrow cells of normal control was identified by qPCR and Western blot analysis. The cell cycle kinetics and cell apoptosis were then detected by flow cytometry.
Results: The expression of TET2 mRNA in CD3(+) and CD34(+) cells was down-regulated in MDS compared with that in controls [(0.16 ± 0.11) vs. (1.05 ± 0.32) (P<0.001); (0.58 ± 0.26) vs. (1.25 ± 0.94) (P<0.005)]. The siRNA targeting TET2 suppressed the expression of TET2 in normal CD34(+) cells. Meanwhile, the proliferation activity was significantly enhanced [G0/G1: (87.82 ± 8.25)% vs. (92.65 ±7.06)% and (93.60 ± 5.54)%, P<0.05; S: (11.50 ± 8.31)% vs. (6.92 ± 7.04)% and (5.95 ± 5.53)%, P<0.05] and the apoptosis rate was declined [(21.28 ± 9.73)% vs. (26.17 ± 9.88)% and (26.20 ± 9.78)%] in the cells which transfected with TET2 siRNA as compared to those in the cells transfected with scrambled siRNA and control cells.
Conclusions: The TET2 expression of in CD3(+) and CD34(+) cells of MDS patients was decreased. Suppression of TET2 expression renders the CD34(+) cells harboring more aggressive phenotype. This preliminary finding suggests that CD34(+) cells lowering expression of TET2 may play an oncogenic role on myeloid tumor and CD3(+) T cells of MDS patients may be derived from the malignant clone.
Keywords: Biological effect; CD3+ T cells; CD34+ cells; Myelodysplastic syndromes; TET2; siRNA.