Chidamide and cytarabine synergistically treat acute myeloid leukemia: inhibiting ribosome biogenesis via the MYC-RRP9 pathway

This study explores innovative therapeutic approaches for acute myeloid leukemia by examining the synergistic effects of the histone deacetylase inhibitor chidamide in combination with cytarabine. In both in vitro and in vivo models, the drug combination demonstrated significant synergism in combating acute myeloid leukemia. Transcriptomic analysis revealed that the combination treatment notably downregulates the MYC signaling pathway. Binding assays, including surface plasmon resonance, molecular docking, and molecular dynamics simulations, further demonstrated that chidamide directly interacts with the c-Myc protein, while cytarabine enhanced this interaction. Delving deeper into the mechanism, we identified RRP9-an essential gene for ribosome biogenesis and a key player in acute myeloid leukemia prognosis-as a critical component of the MYC pathway. It was confirmed that MYC regulates RRP9 expression. Functional assays showed that overexpression of RRP9 promoted acute myeloid leukemia cell proliferation and resistance to the chidamide-cytarabine combination, whereas RRP9 knockdown impaired rRNA synthesis, reduced nucleolar size, and diminished protein production. Ultimately, we found that chidamide combined with cytarabine effectively inhibit ribosome biogenesis in acute myeloid leukemia cells. These results underscore the therapeutic potential of targeting the MYC-RRP9 axis to disrupt ribosome biogenesis in acute myeloid leukemia, offering a promising avenue for acute myeloid leukemia treatment.