Detection of N-RAS and K-RAS in their active GTP-bound form in acute myeloid leukemia without activating RAS mutations

RAS genes, predominantly N-RAS and K-RAS, have been implicated in the pathogenesis of acute myeloid leukemia (AML), due to activating RAS mutations detectable in similar to 20% of AML patients. In the present study, RAS proteins were detected in their activated, GTP-bound form, in AML patients (n - 10) not expressing mutated forms of H-RAS, K-RAS and N- RAS. Further analysis revealed the simultaneous presence of N- RAS and K-RAS proteins in the GTP-bound state in seven out of 10 AML samples. In four out of 10 samples the levels of RAS-GTP were comparable to an AML cell line (TF-1) with an activating N- RAS mutation (Q61P). The detection of RAS-GTP in AML patients without RAS mutations further supports a functional role of RAS proteins in the pathogenesis of AML and may explain the observed effects of RAS inhibitors in some AML patients in the absence of activating RAS mutations.