title: Establishment of platform for screening insulin-like growth factor-1 receptor inhibitors and evaluation of novel inhibitors.
abstract: OBJECTIVE
  The insulin-like growth factor-1 receptor (IGF1R) is over-expressed in a wide variety of tumors and contributes to tumor cell proliferation, metastasis and drug resistance. The aim of this study was to establish a sensitive screening platform to identify novel IGF1R inhibitors.
  
  
  METHODS
  The catalytic domain of IGF1R was expressed using the Bac-to-Bac baculovirus expression system. The screening platform for IGF1R inhibitors was established based on ELISA. The binding profile of IGF1R with the inhibitors was predicted with molecular docking and then subjected to the surface plasmon resonance (SPR) approach. The growth inhibition of cancer cells by the inhibitors was assessed with MTT assay. Apoptosis was analyzed using flow cytometry and Western blotting.
  
  
  RESULTS
  A naturally occurring small molecule compound hematoxylin was identified as the most potent inhibitor (IC₅₀ value=1.8±0.1 μmol/L) within a library of more than 200 compounds tested. Molecular simulation predicted the possible binding mode of hematoxylin with IGF1R. An SPR assay further confirmed that hematoxylin bound directly to IGF1R with high binding affinity (Kd=4.2 × 10⁻⁶ mol/L). In HL-60 cancer cells, hematoxylin inactivated the phosphorylation of IGF1R and downstream signaling and therefore suppressed cell proliferation. Mechanistic studies revealed that hematoxylin induced apoptosis in HL-60 cells via both extrinsic and intrinsic pathways.
  
  
  CONCLUSIONS
  A simple, sensitive ELISA-based screening platform for identifying IGF1R inhibitors was established. Hematoxylin was identified as a promising IGF1R inhibitor with effective antitumor activity that deserves further investigation.
authors.affiliation: School of Pharmacy, Shanghai Jiao Tong University, Shanghai 200240, China.
authors.forename: Lin-jiang
authors.initials: LJ
authors.lastname: Tong
authors.forename: Hua
authors.initials: H
authors.lastname: Xie
authors.forename: Ting
authors.initials: T
authors.lastname: Peng
authors.forename: Xiao-feng
authors.initials: XF
authors.lastname: Liu
authors.forename: Xian-liang
authors.initials: XL
authors.lastname: Xin
authors.forename: Xun
authors.initials: X
authors.lastname: Huang
authors.forename: Si-meng
authors.initials: SM
authors.lastname: Chen
authors.forename: Hong-yan
authors.initials: HY
authors.lastname: Liu
authors.forename: Hong-lin
authors.initials: HL
authors.lastname: Li
authors.forename: Mei-yu
authors.initials: MY
authors.lastname: Geng
authors.forename: Ming
authors.initials: M
authors.lastname: Yin
authors.forename: Jian
authors.initials: J
authors.lastname: Ding
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D002413:Cations, Divalent / Q000378:metabolism; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D003001:Cloning, Molecular; D004354:Drug Screening Assays, Antitumor / Q000191:economics / Q000379:methods*; D004797:Enzyme-Linked Immunosorbent Assay / Q000191:economics / Q000379:methods*; D018922:HL-60 Cells; D006416:Hematoxylin / Q000494:pharmacology*; D006801:Humans; D008958:Models, Molecular; D009369:Neoplasms / Q000188:drug therapy; D010766:Phosphorylation / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D017434:Protein Structure, Tertiary; D017526:Receptor, IGF Type 1 / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012680:Sensitivity and Specificity
chemical_list: D000970:Antineoplastic Agents; D002413:Cations, Divalent; D047428:Protein Kinase Inhibitors; D017526:Receptor, IGF Type 1; D006416:Hematoxylin