title: A modified HSP70 inhibitor shows broad activity as an anticancer agent.
abstract: The stress-induced HSP70 is an ATP-dependent molecular chaperone that plays a key role in refolding misfolded proteins and promoting cell survival following stress. HSP70 is marginally expressed in nontransformed cells, but is greatly overexpressed in tumor cells. Silencing HSP70 is uniformly cytotoxic to tumor but not normal cells; therefore, there has been great interest in the development of HSP70 inhibitors for cancer therapy. Here, we report that the HSP70 inhibitor 2-phenylethynesulfonamide (PES) binds to the substrate-binding domain of HSP70 and requires the C-terminal helical "lid" of this protein (amino acids 573-616) to bind. Using molecular modeling and in silico docking, we have identified a candidate binding site for PES in this region of HSP70, and we identify point mutants that fail to interact with PES. A preliminary structure-activity relationship analysis has revealed a derivative of PES, 2-(3-chlorophenyl) ethynesulfonamide (PES-Cl), which shows increased cytotoxicity and ability to inhibit autophagy, along with significantly improved ability to extend the life of mice with pre-B-cell lymphoma, compared with the parent compound (P = 0.015). Interestingly, we also show that these HSP70 inhibitors impair the activity of the anaphase promoting complex/cyclosome (APC/C) in cell-free extracts, and induce G2-M arrest and genomic instability in cancer cells. PES-Cl is thus a promising new anticancer compound with several notable mechanisms of action.
authors.affiliation: Program in Molecular and Cellular Oncogenesis, The Wistar Institute, Philadelphia, PA 19104, USA.
authors.forename: Gregor M
authors.initials: GM
authors.lastname: Balaburski
authors.forename: Julia I-Ju
authors.initials: JI
authors.lastname: Leu
authors.forename: Neil
authors.initials: N
authors.lastname: Beeharry
authors.forename: Seth
authors.initials: S
authors.lastname: Hayik
authors.forename: Mark D
authors.initials: MD
authors.lastname: Andrake
authors.forename: Gao
authors.initials: G
authors.lastname: Zhang
authors.forename: Meenhard
authors.initials: M
authors.lastname: Herlyn
authors.forename: Jessie
authors.initials: J
authors.lastname: Villanueva
authors.forename: Roland L
authors.initials: RL
authors.lastname: Dunbrack
authors.forename: Tim
authors.initials: T
authors.lastname: Yen
authors.forename: Donna L
authors.initials: DL
authors.lastname: George
authors.forename: Maureen E
authors.initials: ME
authors.lastname: Murphy
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage*; D003198:Computer Simulation; D015973:Gene Expression Regulation, Leukemic; D042822:Genomic Instability / Q000187:drug effects; D050884:HSP72 Heat-Shock Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D051379:Mice; D008958:Models, Molecular; D062105:Molecular Docking Simulation; D009374:Neoplasms, Experimental / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism; D015452:Precursor B-Cell Lymphoblastic Leukemia-Lymphoma / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects; D017434:Protein Structure, Tertiary / Q000187:drug effects; D013329:Structure-Activity Relationship; D013379:Substrate Specificity; D013449:Sulfonamides / Q000008:administration & dosage*
chemical_list: C545662:2-phenylethylenesulfonamide; D000970:Antineoplastic Agents; D050884:HSP72 Heat-Shock Proteins; D013449:Sulfonamides