Pharmacological targeting of casein kinase 1δ suppresses oncogenic NRAS-driven melanoma

Activating mutations in NRAS account for 15-20% of melanoma, yet effective anti-NRAS therapies are still lacking. In this study, we unveil the casein kinase 1 delta (CK1 delta) as an uncharacterized regulator of oncogenic NRAS mutations, specifically Q61R and Q61K, which are the most prevalent NRAS mutations in melanoma. The genetic ablation or pharmacological inhibition of CK1 delta markedly destabilizes NRAS mutants and suppresses their oncogenic functions. Moreover, we identify USP46 as a bona fide deubiquitinase of NRAS mutants. Mechanistically, CK1 delta directly phosphorylates USP46 and activates its deubiquitinase activity towards NRAS mutants, thus promoting oncogenic NRAS-driven melanocyte malignant transformation and melanoma progression in vitro and in vivo. Our findings underscore the significance of the CK1 delta-USP46 axis in stabilizing oncogenic NRAS mutants and provide preclinical evidence that targeting this axis holds promise as a therapeutic strategy for human melanoma harboring NRAS mutations. Activating NRAS mutations are frequently oncogenic drivers of melanoma; however, attempts to therapeutically target mutant NRAS have remained largely unsuccessful. Here, the authors identify an axis of mutant NRAS regulation wherein casein kinase 1 delta (CK1 delta) promotes USP46-mediated stabilisation of oncogenic NRAS.