Taylor, SJ, Thien, CB, Dagger, SA, Duyvestyn, JM, Grove, CS, Lee, BH, Gilliland, DG and Langdon, WY (2014) Loss of c-Cbl E3 ubiquitin ligase activity enhances the development of myeloid leukemia in FLT3-ITD mutant mice. Experimental Hematology.

Abstract

Mutations in the FLT3 receptor tyrosine kinase (RTK) occur frequently in acute myeloid leukemia (AML), with the most common involving internal tandem duplication (ITD) within the juxtamembrane domain. FLT3-ITD mutations result in a mislocalized and constitutively activated receptor, which aberrantly phosphorylates STAT5 and upregulates the expression of its target genes. c-Cbl is an E3 ubiquitin ligase that negatively regulates RTKs, including FLT3, but whether it can downregulate mislocalized FLT3-ITD remains to be resolved. To help clarify this we combined a FLT3-ITD mutation with a loss-of-function mutation in the RING finger domain of c-Cbl that abolishes its E3 ligase activity. Mice transplanted with hematopoietic stem cells expressing both mutations rapidly develop myeloid leukemia indicating strong cooperation between the two. Although the c-Cbl mutation was shown to cause hyper-activation of another RTK, c-Kit, it had no effect on enhancing FLT3-ITD protein levels or STAT5 activation. This indicates that c-Cbl does not downregulate FLT3-ITD, and that the leukemia is driven by independent pathways involving FLT3-ITD's activation of STAT5 and mutant c-Cbl's activation of other RTKs, such as c-Kit. This study highlights the importance of c-Cbl's negative regulation of wild-type RTKs in suppressing FLT3-ITD-driven myeloid leukemia

Item Type:	Article
Additional Information:	NIBR author: Lee, BH institute: NIBR contributor address:
Date Deposited:	13 Oct 2015 13:11
Last Modified:	13 Oct 2015 13:11
URI:	https://oak.novartis.com/id/eprint/24935