Mutant NPM1 maintains RASGRP3 protein stability via interaction with MID1 to promote acute myeloid leukemia cell proliferation and autophagy.

ABSTRACT

Acute myeloid leukemia is a heterogeneous hematologic malignancy with high mortality in the world. NPM1 gene mutations are a frequent occurrence in acute myeloid leukemia, leading to abnormal autophagy, while the mechanism of NPM1 mutation-driven acute myeloid leukemia pathogenesis remains to be fully elucidated. GEO microarrays were used to screen for dysregulated autophagy-related genes in NPM1-mutant acute myeloid leukemia and analysis of RASGRP3 expression and prognosis. Next, we explored the potential molecular mechanisms relationship between RASGRP3 and NPM1 through utilizing immunoprecipitation, Western blot, and cycloheximide assay. Further, CCK8, EdU staining, immunofluorescence, and Western blot were performed to explore the effect of RASGRP3 on cell proliferation and apoptosis in NPM1-mutated acute myeloid leukemia. Finally, Western blot was used to study the mechanism of action of RASGRP3. RASGRP3 expression was upregulated in NPM1-mutated acute myeloid leukemia. Mislocalized NPM1-mA in the cytoplasm could bind to E3 ubiquitin-protein ligase MID1 to block degradation of the RASGRP3 protein. RASGRP3 could also activate the EGFR-STAT3 axis to promote proliferation and autophagy in acute myeloid leukemia. In conclusion, our results identified RASGRP3 as a proto-oncogene in NPM1-mutated acute myeloid leukemia. The RASGRP3-EGFR/STAT3 axis may be a promising therapeutic target for this unique leukemic subtype.