MicroRNAs (miRNAs) are short and single strand non-coding RNAs that involved in post-transcriptional regulation of gene expression. Dysregulation of miRNA expression is important event in the many of malignant diseases. Up-regulation of Let-7a-5p expression in acute myeloid leukemia in human in previous studies was reported. In this study blockage of Let-7a-5p in human acute promyelocytic leukemia cell line (HL60) was done by using locked nucleic acid (LNA) method and subsequently expression of Let-7a-5p, cell proliferation, apoptosis, necrosis, and CASP3 expression was measured. At three time points 24, 48 and 72 h after LNA anti- Let-7a-5p transfection, assessment of Let-7a-5p expression by qRT real-time PCR was completed. The MTT assay and annexin/PI staining have been performed. Also, CASP3 expression at different time points after LNA anti-Let-7a-5p transfection in HL60 cell line was measured. The results at three-time points after LNA transfection were represented that Let-7a-5p expression was lower in the LNA-anti-Let-7a group compared to the control groups. The cell viability significantly was different between LNA-anti-Let-7a group and control groups. Increasing apoptotic ratio was associated with Let-7a-5p blockage in the LNA-anti-Let-7a group compared with control groups. Also, the necrotic ratio was higher in the LNA-anti-Let-7a group rather than the other groups. Western blotting revealed that CASP3 expression associated with Let-7a-5p inhibition. Our results displayed that blockage of Let-7a-5p can reduced cell viability mainly due to the induction of apoptosis and CASP3 up-regulation in HL60 cells. These results can be useful in translational medicine for research of antisense therapy in leukemia.
Keywords: Acute promyelocytic leukemia; CASP3; Let-7a-5p; Locked nucleic acid; miRNA.