Activating c-KIT mutations confer oncogenic cooperativity and rescue RUNX1/ETO-induced DNA damage and apoptosis in human primary CD34+ hematopoietic progenitors.

Wichmann C, Quagliano-Lo Coco I, Yildiz Ö, Chen-Wichmann L, Weber H, Syzonenko T, Döring C, Brendel C, Ponnusamy K, Kinner A, Brandts C, Henschler R, Grez M
Source: Leukemia
Publication Date: (2015)
Issue: 29(2): 279-89
Research Area:
Gene Expression
Basic Research
Cells used in publication:
Species: human
Tissue Origin: blood
CD34+ cell, human
Species: human
Tissue Origin: blood
Species: human
Tissue Origin: kidney
Species: human
Tissue Origin: lung
The RUNX1/ETO (RE) fusion protein, which originates from the t(8;21) chromosomal rearrangement, is one of the most frequent translocation products found in de novo acute myeloid leukemia (AML). In RE leukemias, activated forms of the c-KIT tyrosine kinase receptor are frequently found, thereby suggesting oncogenic cooperativity between these oncoproteins in the development and maintenance of t(8;21) malignancies. In this report, we show that activated c-KIT cooperates with a C-terminal truncated variant of RE, REtr, to expand human CD34+ hematopoietic progenitors ex vivo. CD34+ cells expressing both oncogenes resemble the AML-M2 myeloblastic cell phenotype, in contrast to REtr-expressing cells which largely undergo granulocytic differentiation. Oncogenic c-KIT amplifies REtr-depended clonogenic growth and protects cells from exhaustion. Activated c-KIT reverts REtr-induced DNA damage and apoptosis. In the presence of activated c-KIT, REtr-downregulated DNA-repair genes are re-expressed leading to an enhancement of DNA-repair efficiency via homologous recombination. Together, our results provide new mechanistic insight into REtr and c-KIT oncogenic cooperativity and suggest that augmented DNA repair accounts for the increased chemoresistance observed in t(8;21)-positive AML patients with activated c-KIT mutations. This cell-protective mechanism might represent a new therapeutic target, as REtr cells with activated c-KIT are highly sensitive to pharmacological inhibitors of DNA repair.