Effect of Estradiol on miR-21& miR-155 Expression in promyelocytic leukemia-derived cell line NB4

Background: Due to the estrogen participation in modulating the proliferation and commitment of stem cells and the effects of miR-21 and miR-155 expression on reduced proliferation and colony formation of acute myeloid leukemia (AML), the aim of the present study was to evaluate the effect of estradiol on expression of miR-21 and miR-155 in the NB4 cell line, as an acute promyelocytic leukemia (APL). Materials and Methods: In the present experiment, NB4 cells were treated with different quantities of estradiol (5, 25, 50, 75, 100, 150, 200, 250 μg/ml) and vehicle control for 24 and 48 hours. Viability, apoptosis, and cellular proliferation were estimated by trypan blue exclusion, flow cytometry, and MTT assays, respectively. The level of miR-155 and miR-21 expression was studied using absolute quantitative real-time PCR. Results: Results showed that estradiol in the effective dose (200 μg/ml) led to decreased cellular viability (in a dose dependent manner, P = 0.004) and apoptosis of NB4 cells. In addition, the expressions of miR-155 and miR-21 were significantly and dose-dependently decreased (p<0.05). Conclusion: Estradiol at the effective dose caused apoptosis in NB4 cell line. This substance can be used as a drug for the treatment of APL. However, further assessments are needed to support the effectiveness of estradiol in the treatment of APL.