A metabolic-epigenetic mechanism directs cell fate and therapeutic sensitivity in breast cancer

Abstract Over the past decade, studies have increasingly shed light on a reciprocal relationship between cellular metabolism and cell fate, meaning that a cell’s lineage both drives and is governed by its specific metabolic features. A recent study by Zhang and colleagues, published in Cell Metabolism, describes a novel metabolic-epigenetic regulatory axis that governs lineage identity in triple negative breast cancer (TNBC). Among the key findings, the authors demonstrate that the metabolic enzyme pyruvate kinase M2 (PKM2) directly binds to the histone methyltransferase enhancer of zeste homologue 2 (EZH2) in the nucleus to silence expression of a set of genes that includes the mitochondrial carnitine transporter SLC16A9. Perturbation of this metabolic-epigenetic regulatory mechanism induces a metabolic shift away from glycolysis and towards fatty acid oxidation. The ensuing influx of carnitine facilitates the deposition of the activating epigenetic mark H3K27Ac onto the promoter of GATA3, driving a committed luminal lineage state. Importantly, this metabolic-epigenetic axis represents a potentially targetable vulnerability for the treatment of TNBC, a subtype that currently lacks effective therapeutic strategies. These findings lend further support for the paradigm shift underlying our understanding of cancer metabolism: that a cellular fuel source functions not only to provide energy but also to direct the epigenetic regulation of cell fate.