Combined MEK and JAK Inhibition abrogates murine myeloproliferative neoplasm

Jing Zhang, Guangyao Kong, Mark Wunderlich, David Yang, Erik A. Ranheim, Ken H. Young, Jinyong Wang, Yuan I. Chang, Juan Du, Yangang Liu, Sin Ruow Tey, Xinmin Zhang, Mark Juckett, Ryan Mattison, Alisa Damnernsawad, Jingfang Zhang, James C. Mulloy

Research output: Contribution to journalArticlepeer-review

43 Scopus citations


Overactive RAS signaling is prevalent in juvenile myelomonocytic leukemia (JMML) and the myeloproliferative variant of chronic myelomonocytic leukemia (MP-CMML) in humans, and both are refractory to conventional chemotherapy. Conditional activation of a constitutively active oncogenic Nras (Nras G12D/G12D) in murine hematopoietic cells promotes an acute myeloproliferative neoplasm (MPN) that recapitulates many features of JMML and MP-CMML. We found that NrasG12D/G12D-expressing HSCs, which serve as JMML/MP-CMML-initiating cells, show strong hyperactivation of ERK1/2, promoting hyperproliferation and depletion of HSCs and expansion of downstream progenitors. Inhibition of the MEK pathway alone prolonged the presence of NrasG12D/G12D-expressing HSCs but failed to restore their proper function. Consequently, approximately 60% of NrasG12D/G12D mice treated with MEK inhibitor alone died within 20 weeks, and the remaining animals continued to display JMML/MP-CMML-like phenotypes. In contrast, combined inhibition of MEK and JAK/STAT signaling, which is commonly hyperactivated in human and mouse CMML, potently inhibited human and mouse CMML cell growth in vitro, rescued mutant NrasG12D/G12D-expressing HSC function in vivo, and promoted long-term survival without evident disease manifestation in NrasG12D/G12D animals. These results provide a strong rationale for further exploration of combined targeting of MEK/ERK and JAK/STAT in treating patients with JMML and MP-CMML.

Original languageEnglish (US)
Pages (from-to)2762-2773
Number of pages12
JournalJournal of Clinical Investigation
Issue number6
StatePublished - Jun 2 2014
Externally publishedYes


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