VCP relocalization limits mitochondrial activity, GSH depletion and ferroptosis during starvation in PC3 prostate cancer cells

Abstract

During periods of crisis, cells must compensate to survive. To this end, cells may need to alter the subcellular localization of crucial proteins. Here, we show that during starvation, VCP, the most abundant soluble ATPase, relocalizes and forms aggregate-like structures at perinuclear regions in PC3 prostate cancer cells. This movement is associated with a lowered metabolic state, in which mitochondrial activity and ROS production are reduced. VCP appears to explicitly sense glutamine levels, as removal of glutamine from complete medium triggered VCP relocalization and its addition to starvation media blunted VCP relocalization. Cells cultured in Gln(+) starvation media exhibited uniformly distributed VCP in the cytoplasm (free VCP) and underwent ferroptotic cell death, which was associated with a decrease in GSH levels. Moreover, the addition of a VCP inhibitor, CB-5083, in starvation media prevented VCP relocalization and triggered ferroptotic cell death. Likewise, expression of GFP-fused VCP proteins, irrespective of ATPase activities, displayed free VCP and triggered cell death during starvation. These results indicate that free VCP is essential for the maintenance of mitochondrial function and that PC3 cells employ a strategy of VCP self-aggregation to suppress mitochondrial activity in order to escape cell death during starvation, a novel VCP-mediated survival mechanism.