Abstract 2697: Alterations in the HSP70 interactome are induced by overexpression of MUC1 in pancreatic cancer

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Abstract Heat Shock Protein 70 (HSP70) is an evolutionarily well-conserved molecular chaperone involved in several cellular processes such as folding of proteins, modulating protein-protein interactions and transport of proteins across membranes. HSP70 works synergistically with a series of chaperones, co-chaperones, adaptors, and folding enzymes known as the HSP70 “interactome”. Previous work has demonstrated that HSP70 interactome changes can be promoted by overexpression of oncoproteins. An important “client” of HSP70 is the oncoprotein MUC1. MUC1 is overexpressed and promotes drug resistance in pancreatic cancer. We applied quantitative affinity-purification mass spectrometry (AP-MS) to characterize the HSP70 interactome differences between PC3/NEO and PC3/MUC1 cell lines. 439 HSP70-interacting proteins were identified and quantified via LC-MS/MS. Interestingly while 53% of HSP70 interactions remained constant upon MUC1 overexpression, 29% significantly increased and 18% decreased. Many of the altered proteins were key co-chaperones that regulate and maintain HSP70 activity. High levels of MUC1 promoted HSP70 association with 15 co-chaperones (HSPA5, DNAJB1, STIP1, TXNDC5, HSPB1, CCT2, TCP1, P4HB, CCT6A, CCT8, PDIA3 and HSP90B). Conversely, MUC1 overexpression triggered the loss of HSP70 interaction with only 2 co-chaperones (PPIB and DNAJA2). We are currently validating these altered interactions using an array of biochemical techniques. Our hope is that by understanding these HSP70 interactome changes, we may be able to uncover novel ways to inhibit MUC1 function in pancreatic cancer. Citation Format: . Nitika, Donald J. Wolfgeher, Pinku Mukherjee, Andrew W. Truman. Alterations in the HSP70 interactome are induced by overexpression of MUC1 in pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2697.