YAP/TEAD-activated TAG synthesis and peroxidation in lipid droplets confer ROS resistance in cancer stem cells

Cancer stem cells (CSCs) exhibit reduced levels of reactive oxygen species (ROS) despite increased oxidative phosphorylation, through mechanisms that remain poorly understood. Understanding these mechanisms could lead to new strategies for identifying and eradicating CSCs.

We combined lipidomic profiling, RNA-sequencing (RNA-seq), and TAGsig analysis to identify key lipids and genes involved in CSC-mediated resistance to ROS. These findings were further validated through a series of in vitro and in vivo experiments.

We show that triacylglycerol (TAG), the main lipid in lung CSCs, localizes to peri-mitochondrial lipid droplets (LDs) and acts as a ROS scavenger. TAG undergoes peroxidation in these droplets upon exposure to H₂O₂, tBH, hypoxia, and FeCl₂, whereas in non-CSCs, oxidation occurs in mitochondria. RNA-seq analysis revealed upregulation of TAG synthesis enzymes (ACSL1/4, LPIN2, DGAT1/2, PNPLA3) in CSCs compared to non-CSCs. Inhibition and knockdown of DGAT1/2, which block TAG synthesis, led to reduced LDs and diminished sphere formation, radioresistance, and tumor initiation in vivo. Additionally, a six-gene TAG synthesis signature effectively predicted prognosis and survival in lung cancer patients. CSCs upregulated the ^Y357YAP/TEAD pathway to activate transcription of TAG synthesis genes, enhancing resistance to ROS.

We demonstrate that TAG in peri-mitochondrial LDs functions as a ROS scavenger, enabling CSCs to survive in hyperoxidative environments. Targeting the signaling pathways involved in TAG synthesis presents a potential strategy for eradicating CSCs.