Search

Whereas oncogenes can potentially be inhibited with small molecules, the loss of tumour suppressors is more common and is problematic because the tumour-suppressor proteins are no longer present to be targeted. Notable examples include SMARCB1-mutant cancers, which are highly lethal malignancies driven by the inactivation of a subunit of SWI/SNF (also known as BAF) chromatin-remodelling complexes. Here, to generate mechanistic insights into the consequences of SMARCB1 mutation and to identify vulnerabilities, we contributed 14 SMARCB1-mutant cell lines to a near genome-wide CRISPR screen as part of the Cancer Dependency Map Project1–3. We report that the little-studied gene DDB1–CUL4-associated factor 5 (DCAF5) is required for the survival of SMARCB1-mutant cancers. We show that DCAF5 has a quality-control function for SWI/SNF complexes and promotes the degradation of incompletely assembled SWI/SNF complexes in the absence of SMARCB1. After depletion of DCAF5, SMARCB1-deficient SWI/SNF complexes reaccumulate, bind to target loci and restore SWI/SNF-mediated gene expression to levels that are sufficient to reverse the cancer state, including in vivo. Consequently, cancer results not from the loss of SMARCB1 function per se, but rather from DCAF5-mediated degradation of SWI/SNF complexes. These data indicate that therapeutic targeting of ubiquitin-mediated quality-control factors may effectively reverse the malignant state of some cancers driven by disruption of tumour suppressor complexes.DCAF5 has a quality-control function for SWI/SNF complexes and promotes the degradation of incompletely assembled SWI/SNF complexes in the absence of SMARCB1. [ABSTRACT FROM AUTHOR]

Phosphatidylinositol 5‐phosphate 4‐kinase, type II, gamma (PIP4K2C) remains a poorly understood lipid kinase with minimal enzymatic activity but potential scaffolding roles in immune modulation and autophagy‐dependent catabolism. Achieving potent and selective agents for PIP4K2C while sparing other lipid and non‐lipid kinases has been challenging. Here, we report the discovery of the highly potent PIP4K2C binder TMX‐4102, which shows exclusive binding selectivity for PIP4K2C. Furthermore, we elaborated the PIP4K2C binder into TMX‐4153, a bivalent degrader capable of rapidly and selectively degrading endogenous PIP4K2C. Collectively, our work demonstrates that PIP4K2C is a tractable and degradable target, and that TMX‐4102 and TMX‐4153 are useful leads to further interrogate the biological roles and therapeutic potential of PIP4K2C. [ABSTRACT FROM AUTHOR]

Phosphatidylinositol 5‐phosphate 4‐kinase, type II, gamma (PIP4K2C) remains a poorly understood lipid kinase with minimal enzymatic activity but potential scaffolding roles in immune modulation and autophagy‐dependent catabolism. Achieving potent and selective agents for PIP4K2C while sparing other lipid and non‐lipid kinases has been challenging. Here, we report the discovery of the highly potent PIP4K2C binder TMX‐4102, which shows exclusive binding selectivity for PIP4K2C. Furthermore, we elaborated the PIP4K2C binder into TMX‐4153, a bivalent degrader capable of rapidly and selectively degrading endogenous PIP4K2C. Collectively, our work demonstrates that PIP4K2C is a tractable and degradable target, and that TMX‐4102 and TMX‐4153 are useful leads to further interrogate the biological roles and therapeutic potential of PIP4K2C. [ABSTRACT FROM AUTHOR]