AKR1C3 decreased CML sensitivity to Imatinib in bone marrow microenvironment via dysregulation of miR-379-5p

Background: Drug resistance is an important cause of death for most patients with chronic myeloid leukemia (CML). The bone marrow microenvironment is believed to be mainly responsible for resistance to BCR-ABL tyrosine kinase inhibitors. The mechanism involved, however, is still unclear.

Methods: Bioinformatic analysis from GEO database of AKR1C3 was utilized to identify the AKR1C3 expression in CML cells under bone marrow microenvironment. Western blot and qPCR were performed to detect the AKR1C3 expression in two CML cell lines K562 and KU812 cultured +/- bone microenvironment derived stromal cells. CCK-8, soft agar colony assay, and Annexin V/PI assay were performed to detect the sensitivity of CML cells (K562 and KU812) to Imatinib under a gain of or loss of function of AKR1C3 treatment. The CML murine model intravenous inoculated with K562-OE-vector and K562-OE-AKR1C3 cells were established to estimate the effect of AKR1C3 inhibitor Indomethacin on Imatinib resistance. The bioinformatic analysis of miRNA databases was used to predict the potential miRNAs targeting AKR1C3. And the luciferase assay was utilized to validate the target relationship between miR-379-5p and AKR1C3. And, the soft agar colony assay and Annexin V/PI were used to validate the effect of miR-379-5p in AKR1C3 induced Imatinib resistance.

Results: In present study, we investigated AKR1C3 was highly expressed in CML under bone marrow microenvironment. AKR1C3 decreased Imatinib activity in K562 and KU812 cells, while inhibition of AKR1C3 could enhance Imatinib sensitivity in vitro study. Furthermore, murine model results showed combination use of AKR1C3 inhibitor Indomethacin effectively prolong mice survival, indicating that AKR1C3 is a promising target to enhance Imatinib treatment. Mechanically, AKR1C3 was found to be suppressed by miR-379-5p, which was down-expression in bone marrow microenvironment. Besides, we found miR-379-5p could bind AKR1C3 3'UTR but not degrade its mRNA level. Further, gain of miR-379-5p rescued the imatinib resistance induced by AKR1C3 overexpression in CML cells.

Conclusions: Altogether, our study identifies a novel signaling regulation of miR-379-5p/AKR1C3/EKR axis in regulating IM resistance in CML cell, and provides a scientific base for exploring AKR1C3 as a biomarker in impeding IM resistance in CML.