title: Unambiguous Identification of β-Tubulin as the Direct Cellular Target Responsible for the Cytotoxicity of Chalcone by Photoaffinity Labeling.
abstract: Chalcone is a simple and potentially privileged structure in medicinal chemistry with a diverse repertoire of biological activities, among which cytotoxicity is of particular interest. The sharp structure-activity relationship (SAR) for chalcone's cytotoxicity suggests structure-specific target interactions. Despite the numerous putative targets proposed, evidence for direct target interactions in cells is unavailable. In this study, guided by the sharp cytotoxic SAR, we developed a cytotoxic chalcone-based photoaffinity labeling (PAL) probe, (E)-3-(3-azidophenyl)-1-[3,5-dimethoxy-4-(prop-2-yn-1-yloxy)phenyl]-2-methylprop-2-en-1-one (C95; IC50 : 0.38±0.01 μm), along with two structurally similar non-cytotoxic probes. These probes were used to search for the direct cellular target responsible for chalcone's cytotoxicity through intact cell-based PAL experiments, in which β-tubulin was identified to specifically interact with the cytotoxic probe (i.e., C95) but not the non-cytotoxic probes. A set of phenotypical and biochemical assays further reinforced β-tubulin as the cytotoxic target of chalcones. Peptide mass quantitation by mass spectrometric analysis revealed one peptide potentially labeled by C95, providing information on chalcone's binding site on β-tubulin.
authors.affiliation: Department of Medicinal Chemistry, College of Pharmacy, University of Minnesota, 2231 6th Street SE, Minneapolis, MN, 55455, USA.
authors.forename: Bo
authors.initials: B
authors.lastname: Zhou
authors.affiliation: Department of Medicinal Chemistry, College of Pharmacy, University of Minnesota, 2231 6th Street SE, Minneapolis, MN, 55455, USA.|Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology, Shanghai, 200237, China.
authors.forename: Xingxin
authors.initials: X
authors.lastname: Yu
authors.affiliation: Department of Medicinal Chemistry, College of Pharmacy, University of Minnesota, 2231 6th Street SE, Minneapolis, MN, 55455, USA. xingx009@umn.edu.|Research Center for Marine Drugs, School of Pharmacy, Second Military Medical University, 325 Guohe Road, Shanghai, 200433, China. xingx009@umn.edu.
authors.forename: Chunlin
authors.initials: C
authors.lastname: Zhuang
authors.affiliation: Masonic Cancer Center, University of Minnesota, 2231 6th Street SE, Minneapolis, MN, 55455, USA.
authors.forename: Peter
authors.initials: P
authors.lastname: Villalta
authors.affiliation: Molecular Biology and Lung Cancer Program, Lovelace Respiratory Research Institute, Albuquerque, NM, 87108, USA.
authors.forename: Yong
authors.initials: Y
authors.lastname: Lin
authors.affiliation: Department of Pharmacology and Cancer Institute, Penn State University College of Medicine, Hershey, PA, 17033, USA.
authors.forename: Junxuan
authors.initials: J
authors.lastname: Lu
authors.affiliation: Department of Medicinal Chemistry, College of Pharmacy, University of Minnesota, 2231 6th Street SE, Minneapolis, MN, 55455, USA. zhuan092@gmail.com.
authors.forename: Chengguo
authors.identifier: 0000-0002-9232-1586
authors.initials: C
authors.lastname: Xing
mesh_terms: D000072283:A549 Cells; D000970:Antineoplastic Agents / Q000737:chemistry / Q000494:pharmacology*; D001386:Azides / Q000737:chemistry / Q000494:pharmacology*; D001665:Binding Sites; D001710:Biotin / Q000031:analogs & derivatives / Q000737:chemistry; D002599:Chalcone / Q000737:chemistry / Q000494:pharmacology*; D047188:Chalcones / Q000737:chemistry / Q000494:pharmacology*; D057930:Click Chemistry; D059565:G2 Phase Cell Cycle Checkpoints / Q000187:drug effects; D006801:Humans; D019920:Photoaffinity Labels / Q000737:chemistry / Q000494:pharmacology*; D013329:Structure-Activity Relationship; D014404:Tubulin / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D050257:Tubulin Modulators / Q000737:chemistry / Q000494:pharmacology*
chemical_list: C000622557:3-(3-azidophenyl)-1-(3,5-dimethoxy-4-(prop-2-yn-1-yloxy)phenyl)-2-methylprop-2-en-1-one; D000970:Antineoplastic Agents; D001386:Azides; D047188:Chalcones; D019920:Photoaffinity Labels; D014404:Tubulin; D050257:Tubulin Modulators; D002599:Chalcone; D001710:Biotin
keywords: chalcones; chemical probes; cytotoxicity; photoaffinity labeling; tubulin