title: Celastrol induces unfolded protein response-dependent cell death in head and neck cancer.
abstract: The survival rate for patients with oral squamous cell carcinoma (OSCC) has not seen marked improvement in recent decades despite enhanced efforts in prevention and the introduction of novel therapies. We have reported that pharmacological exacerbation of the unfolded protein response (UPR) is an effective approach to killing OSCC cells. The UPR is executed via distinct signaling cascades whereby an initial attempt to restore folding homeostasis in the endoplasmic reticulum during stress is complemented by an apoptotic response if the defect cannot be resolved. To identify novel small molecules able to overwhelm the adaptive capacity of the UPR in OSCC cells, we engineered a complementary cell-based assay to screen a broad spectrum of chemical matter. Stably transfected CHO-K1 cells that individually report (luciferase) on the PERK/eIF2α/ATF4/CHOP (apoptotic) or the IRE1/XBP1 (adaptive) UPR pathways, were engineered [1]. The triterpenoids dihydrocelastrol and celastrol were identified as potent inducers of UPR signaling and cell death in a primary screen and confirmed in a panel of OSCC cells and other cancer cell lines. Biochemical and genetic assays using OSCC cells and modified murine embryonic fibroblasts demonstrated that intact PERK-eIF2-ATF4-CHOP signaling is required for pro-apoptotic UPR and OSCC death following celastrol treatment.
authors.affiliation: Carmen and Ann Adams Department of Pediatrics, Children׳s Hospital of Michigan, Detroit, MI 48201, USA; Molecular Therapeutics Program, Barbara Ann Karmanos Cancer Institute, Detroit, MI 48201, USA; Wayne State University School of Medicine, Detroit, MI, USA. Electronic address: afribley@med.wayne.edu.
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Fribley
authors.affiliation: Carmen and Ann Adams Department of Pediatrics, Children׳s Hospital of Michigan, Detroit, MI 48201, USA; Wayne State University School of Medicine, Detroit, MI, USA.
authors.forename: Justin R
authors.initials: JR
authors.lastname: Miller
authors.affiliation: Carmen and Ann Adams Department of Pediatrics, Children׳s Hospital of Michigan, Detroit, MI 48201, USA; Wayne State University School of Medicine, Detroit, MI, USA.
authors.forename: Amy L
authors.initials: AL
authors.lastname: Brownell
authors.affiliation: Carmen and Ann Adams Department of Pediatrics, Children׳s Hospital of Michigan, Detroit, MI 48201, USA; Molecular Therapeutics Program, Barbara Ann Karmanos Cancer Institute, Detroit, MI 48201, USA.
authors.forename: Danielle M
authors.initials: DM
authors.lastname: Garshott
authors.affiliation: Carmen and Ann Adams Department of Pediatrics, Children׳s Hospital of Michigan, Detroit, MI 48201, USA; Molecular Therapeutics Program, Barbara Ann Karmanos Cancer Institute, Detroit, MI 48201, USA; Wayne State University School of Medicine, Detroit, MI, USA.
authors.forename: Qinghua
authors.initials: Q
authors.lastname: Zeng
authors.affiliation: The Undergraduate Research Opportunities Program, University of Michigan, Ann Arbor, MI 48109, USA.
authors.forename: Tyler E
authors.initials: TE
authors.lastname: Reist
authors.affiliation: Wayne State University School of Medicine, Detroit, MI, USA.
authors.forename: Neha
authors.initials: N
authors.lastname: Narula
authors.affiliation: Wayne State University School of Medicine, Detroit, MI, USA.
authors.forename: Peter
authors.initials: P
authors.lastname: Cai
authors.affiliation: Carmen and Ann Adams Department of Pediatrics, Children׳s Hospital of Michigan, Detroit, MI 48201, USA; Wayne State University School of Medicine, Detroit, MI, USA.
authors.forename: Yue
authors.initials: Y
authors.lastname: Xi
authors.affiliation: Carmen and Ann Adams Department of Pediatrics, Children׳s Hospital of Michigan, Detroit, MI 48201, USA; Wayne State University School of Medicine, Detroit, MI, USA.
authors.forename: Michael U
authors.initials: MU
authors.lastname: Callaghan
authors.affiliation: Degenerative Disease Research Center, Sanford|Burnham Medical Research Institute La Jolla, CA 92037, USA.
authors.forename: Vamsi
authors.initials: V
authors.lastname: Kodali
authors.affiliation: Degenerative Disease Research Center, Sanford|Burnham Medical Research Institute La Jolla, CA 92037, USA.
authors.forename: Randal J
authors.initials: RJ
authors.lastname: Kaufman
mesh_terms: D051701:Activating Transcription Factor 4 / Q000378:metabolism; D000818:Animals; D017209:Apoptosis / Q000187:drug effects* / Q000235:genetics; D016466:CHO Cells; D002294:Carcinoma, Squamous Cell / Q000188:drug therapy / Q000473:pathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D003412:Cricetulus; D004268:DNA-Binding Proteins / Q000235:genetics; D059865:Endoplasmic Reticulum Stress / Q000502:physiology*; D015852:Eukaryotic Initiation Factor-2 / Q000378:metabolism; D006801:Humans; D051379:Mice; D009062:Mouth Neoplasms / Q000188:drug therapy / Q000473:pathology*; D053978:Pentacyclic Triterpenes; D010936:Plant Extracts / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis; D000071701:Regulatory Factor X Transcription Factors; D015398:Signal Transduction; D051742:Transcription Factor CHOP / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics; D029757:Tripterygium / Q000378:metabolism; D014315:Triterpenes / Q000494:pharmacology*; D054875:Ubiquitination / Q000187:drug effects; D056811:Unfolded Protein Response / Q000187:drug effects* / Q000235:genetics; D000071717:X-Box Binding Protein 1; D019892:eIF-2 Kinase / Q000378:metabolism
chemical_list: C497109:ATF4 protein, human; C497249:DDIT3 protein, human; D004268:DNA-Binding Proteins; D015852:Eukaryotic Initiation Factor-2; D053978:Pentacyclic Triterpenes; D010936:Plant Extracts; D012333:RNA, Messenger; D000071701:Regulatory Factor X Transcription Factors; D014157:Transcription Factors; D014315:Triterpenes; D000071717:X-Box Binding Protein 1; C000605543:XBP1 protein, human; C000605544:Xbp1 protein, mouse; D051701:Activating Transcription Factor 4; D051742:Transcription Factor CHOP; C460640:EIF2AK3 protein, human; D019892:eIF-2 Kinase; C050414:celastrol
keywords: Apoptosis; Celastrol; Chaperone; Drug discovery; ER stress; Oral cancer; Protein folding; Unfolded protein response