Therapeutic targeting of metabolic vulnerabilities in cancers with MLL3/4-COMPASS epigenetic regulator mutations

ABSTRACT: Epigenetic alterations due to abnormalities in the enzymatic machineries modifying chromatin, are frequently reported in developmental diseases and in a variety of human cancers. However, the cellular dependency and functional outcome of epigenetic alterations during these processes have not been fully elucidated. In this study, we depleted two of the most frequently mutated epigenetic factors, the MLL3 and MLL4 components of the COMPASS family, in mouse embryonic stem cells (mESCs) to investigate the cellular vulnerabilities when enhancer functions are compromised as the result of MLL3-4/COMPASS loss. CRISPR dropout screens revealed synthetic lethality of purine and pyrimidine nucleotide synthesis pathway suppression in cells with MLL3/4 loss. We observed a metabolic usage shift towards purine synthesis in Mll3/4 knockout mESCs. Subsequently, Mll3/4 KO cells exhibited enhanced sensitivity to purine synthesis inhibitor lometrexol, which induced unique gene expression signature changes in Mll3/4 KO cells. A tandem mass tag (TMT) proteomics profiling further identified upregulation of purine metabolism factors in Mll3/4KO cells. We also identified the top MLL3/4 target genes coinciding with suppression of the purine metabolism pathway. Finally, in vivo cancer studies show that tumors mutated for MLL3 and/or MLL4 are very sensitive to purine synthesis inhibitor lometrexol in culture and in animal models of cancer. Taken together, we depict a metabolic dependency map for cells deficient for epigenetic factors and provide insights into cancer treatments related to epigenetic alterations corresponding with MLL3/4 COMPASS malfunction.

ORGANISM(S): Mus musculus Homo sapiens

PROVIDER: GSE200120 | GEO | 2023/06/01

REPOSITORIES: GEO