Micheliolide exerts effects in myeloproliferative neoplasms through inhibiting STAT3/5 phosphorylation via covalent binding to STAT3/5 proteins

Ruxolitinib is a cornerstone of management for some subsets of myeloproliferative neoplasms(MPNs);however,a considerable number of patients respond suboptimally.Here,we evaluated the efficacy of micheliolide(MCL),a natural guaianolide sesquiterpene lactone,alone or in combination with ruxolitinib in samples from patients with MPNs,JAK2V617F-mutated MPN cell lines,and a Jak2V617F knock-in mouse model.MCL effectively suppressed colony formation of hematopoietic progenitors in samples from patients with MPNs and inhibited cell growth and survival of MPN cell lines in vitro.Co-treatment with MCL and ruxolitinib resulted in greater inhibitory effects compared with treatment with ruxolitinib alone.Moreover,dimethylaminomicheliolide(DMAMCL),an orally available derivative of MCL,significantly increased the efficacy of ruxolitinib in reducing splenomegaly and cytokine production in Jak2V617F knock-in mice without evident effects on normal hematopoiesis.Importantly,MCL could target the Jak2V617F clone and reduce mutant allele burden in vivo.Mechanistically,MCL can form a stable covalent bond with cysteine residues of STAT3/5 to suppress their phosphorylation,thus inhibiting JAK/STAT signaling.Overall,these findings suggest that MCL is a promising drug in combination with ruxolitinib in the setting of suboptimal response to ruxolitinib.