Pathway incompatibility between NF-kB and RAS signaling constrains oncogenicity in B-cell leukemia

Abstract

B-cell acute lymphoblastic leukemia (B-ALL) arises from lymphoid precursors that fail to complete normal B-cell maturation and frequently harbor activating mutations in the RAS-ERK pathway that promote leukemic survival. These cells remain dependent on precursor B-cell receptor (pre-BCR)-associated signaling programs, which oncogenic RAS can functionally mimic. While oncogenesis is often attributed to cooperating mutations, mutually exclusive genetic alterations suggest that certain oncogenic pathways may be functionally incompatible. In our previous work, we proposed the concept of pathway incompatibility, in which co-activation of specific oncogenic signaling programs antagonizes their oncogenic activity and suppresses tumorigenesis. Here, we examined the interaction between RAS signaling and canonical NF-kB activity in B-ALL within this framework. Genomic analysis revealed underrepresentation of cases harboring concurrent RAS and NF-kB pathway alterations. Functionally, activation of canonical NF-kB induced apoptotic depletion of RAS-pathway-mutated B-ALL cells, whereas activation of the non-canonical pathway conferred a growth advantage. Mechanistically, canonical NF-kB suppressed pre-BCR-associated signaling programs and increased expression of mature B-cell receptor (BCR) components, indicating a developmental signaling state incompatible with oncogenic RAS activity. Consistent with this framework, enforced oncogenic RAS signaling was poorly tolerated in BCR-positive lymphoma cells unless BCR expression was disrupted. Pharmacologic activation of NF-kB reduced ERK signaling and selectively impaired viability of RAS-pathway-mutated B-ALL cells, with enhanced effects in combination with ERK inhibition. Together, these findings identify canonical NF-kB signaling as a developmental context-dependent constraint on RAS-driven leukemogenesis and support pathway incompatibility as a determinant of the oncogenicity of signaling pathways.