Regulation of VCP/p97 demonstrates the critical balance between cell death and epithelial-mesenchymal transition (EMT) downstream of ER stress

Valosin-containing protein (VCP), also called p97, is a AAA+ ATPase that has been shown to be involved in endoplasmic reticulum-associated protein degradation (ERAD), mitochondria quality control and vesicle transport. We and others have previously found that disruption of VCP is sufficient to cause endoplasmic reticulum (ER) stress. We observed that induction of ER stress either following siRNA mediated loss of VCP or inhibition of VCP with eeyarestatin I potently activates an EMT-like state in cells. Interestingly, both ER stress and EMT are reversible events. Further, brief treatment of cells with eeyarestatin I increases EMT markers, and migratory and invasive properties of lung cancer cells. By examining primary lung adenocarcinoma patient samples we find that the VCP locus is heterozygously lost in nearly half of lung adenocarcinomas and VCP protein expression is decreased in nearly all primary lung tumors. Further, primary lung adenocarcinomas have increased ER stress and EMT markers. These observations have potential clinical relevance because increased ER stress and EMT markers are known to contribute to chemoresistance and poor survival of patients with lung adenocarcinoma.