Shi, Y., Liu, X., Calaoagan, J., Samuelsson, S., Chou, T.-F., Deshaies, R. J., & Sambucetti, L. C. (2013, 6-10 April). Development of functional assays for p97/VCP inhibition. Paper presented at the Annual Meeting of the American Association for Cancer Research (AACR’13), Washington, DC.
p97 (also called VCP in metazoans and CDC48 in yeast) is a highly conserved, ubiquitously expressed, and essential AAA ATPase. p97 plays a key role in endoplasmic reticulum-associated degradation of misfolded secretory and membrane proteins as well as ubiquitin-dependent turnover of a subset of cytoplasmic substrates of the ubiquitin-proteasome system. p97 also plays a critical role in specific cellular processes including Golgi membrane reassembly, membrane fusion, autophagy and DNA repair mechanisms. p97 expression is elevated in a number of cancer types including prostate cancer, non-small-cell lung carcinoma and leukemia. Given its cellular functions in protein homeostasis and the successful clinical development of proteasome inhibitors, p97 has emerged as an exciting new target for cancer therapy. We used p97 siRNA and a recently identified small molecule p97 inhibitor, N2,N4-dibenzylquinazoline- 2,4-diamine (DBeQ) as tools to develop functional assays suitable for further evaluating the activity of potential p97 inhibitors. A panel of unfolded protein response marker genes that are consistently modulated by p97 siRNA or DBeQ treatment has been identified. In addition, methods to monitor autophagic activity have been developed, including high content analysis of LC3B-GFP puncta formation. Cell viability assays were used to determine the susceptibility of various cancer cell lines to p97 inhibition. These assays will be used to evaluate the effects of potential p97 inhibitors on p97-dependent pathways and anti-proliferative activity.