CircPAN3 mediates drug resistance in acute myeloid leukemia through the miR-153-5p/miR-183-5p–XIAP axis

The contribution and role of circular RNAs (circRNAs) in mediating chemoresistance in acute myeloid leukemia (AML) are still poorly understood and need further investigation. In this study, we established a doxorubicin (ADM)-resistant THP-1 AML cell line (THP-1/ADM). A high-throughput microarray was used to identify circRNA expression profiles of THP-1/ADM cells and naive THP-1 cells. The identified potential functional circRNA molecule was further validated in THP-1/ADM cells and bone marrow (BM) specimens from 42 AML patients. The interactions with target microRNAs (miRNAs) and downstream messenger RNAs (mRNAs) were also explored. As a result, 49 circRNAs that are significantly differentially expressed between THP-1/ADM and THP-1 cells were identified. Of these circRNAs, downregulation of circPAN3 by small interfering RNA significantly restored ADM sensitivity of THP-1/ADM cells. Furthermore, BM samples from patients with refractory and recurrent AML showed increased expression of circPAN3. A detailed circRNA/miRNA/mRNA interaction network was predicated for this circRNA. Subsequent mechanistic experiments showed that downregulation of circPAN3 could decrease the expression of X-linked inhibitor of apoptosis protein (XIAP), but this effect was counteracted by miR-153-3p or miR-183-5p specific inhibitors. Luciferase experiments further demonstrated that these molecules are involved in the circPAN3 regulatory network. Our results revealed that circPAN3 may be a key mediator for chemoresistance of AML cells, which may depend on the circPAN3–miR-153-5p/miR-183-5p–XIAP axis. Our findings provide evidence that circPAN3 can be a valuable indicator for predicting clinical efficacy of chemotherapy in AML patients and also can serve as a potential target for reversing drug resistance in AML.