PPFIA1-targeting miR-181a mimic and saRNA overcome imatinib resistance in BCR-ABL1-independent chronic myeloid leukemia by suppressing leukemia stem cell regeneration.

A large proportion of patients with chronic myeloid leukemia (CML; 20%-50%) develop resistance to imatinib in a BCR-ABL1-independent manner. Therefore, new therapeutic strategies for use in this subset of imatinib-resistant CML patients are urgently needed. In this study, we used a multi-omics approach to show that PPFIA1 was targeted by miR-181a. We demonstrate that both miR-181a and PPFIA1-siRNA reduced the cell viability and proliferative capacity of CML cells in vitro, as well as prolonged the survival of B-NDG mice harboring human BCR-ABL1-independent imatinib-resistant CML cells. Furthermore, treatment with miR-181a mimic and PPFIA1-siRNA inhibited the self-renewal of c-kit+ and CD34+ leukemic stem cells and promoted their apoptosis. Small activating (sa)RNAs targeting the promoter of miR-181a increased the expression of endogenous primitive miR-181a (pri-miR-181a). Transfection with saRNA 1-3 inhibited the proliferation of imatinib-sensitive and -resistant CML cells. However, only saRNA-3 showed a stronger and more sustained inhibitory effect than the miR-181a mimic. Collectively, these results show that miR-181a and PPFIA1-siRNA may overcome the imatinib resistance of BCR-ABL1-independent CML, partially by inhibiting the self-renewal of leukemia stem cells and promoting their apoptosis. Moreover, exogenous saRNAs represent promising therapeutic agents in the treatment of imatinib-resistant BCR-ABL1-independent CML.