Primary myelofibrosis (PMF) is characterized by immature megakaryocytic
hyperplasia,
splenomegaly, extramedullary hematopoiesis and
bone marrow fibrosis. Our preclinical study had demonstrated that
aurora kinase A (
AURKA) inhibitor
MLN8237 reduced the mutation burden of PMF by inducing differentiation of immature megakaryocytes. However, it only slightly alleviated
splenomegaly, reduced tissue
fibrosis, and normalized megakaryocytes in PMF patients of the preliminary clinical study. So enhancing therapeutic efficacy of PMF is needed. In this study, we found that
AURKA directly interacted with
heat shock protein 90 (HSP90) and HSP90 inhibitors promoted the
ubiquitin-dependent AURKA degradation. We demonstrated that HSP90 inhibitors
17-allylamino-17-demethoxygeldanamycin (17-AAG) and 17-dimethylaminoethylamino-17-demethoxygeldanamycin (17-DMAG), normalized peripheral blood counts, improved
splenomegaly, attenuated extramedullary hematopoiesis, decreased tissue
fibrosis and reduced mutant burden in a MPLW515L mouse model of PMF. Importantly, both
17-AAG and
17-DMAG treatment at effective doses in vivo did not influence on hematopoiesis in healthy mice. Collectively, the study demonstrates that HSP90 inhibitors induce cell differentiation via the
ubiquitin-dependent
AURKA and also are safe and effective for the treatment of a MPLW515L mouse model of PMF, which may provide a new strategy for PMF
therapy. Further, we demonstrate that combined
therapy shows superior activity in
acute megakaryocytic leukemia mouse model than single
therapy.