title: The novel BH3 α-helix mimetic JY-1-106 induces apoptosis in a subset of cancer cells (lung cancer, colon cancer and mesothelioma) by disrupting Bcl-xL and Mcl-1 protein-protein interactions with Bak.
abstract: BACKGROUND
  It has been shown in many solid tumors that the overexpression of the pro-survival Bcl-2 family members Bcl-2/Bcl-xL and Mcl-1 confers resistance to a variety of chemotherapeutic agents. We designed the BH3 α-helix mimetic JY-1-106 to engage the hydrophobic BH3-binding grooves on the surfaces of both Bcl-xL and Mcl-1.
  
  
  METHODS
  JY-1-106-protein complexes were studied using molecular dynamics (MD) simulations and the SILCS methodology. We have evaluated the in vitro effects of JY-1-106 by using a fluorescence polarization (FP) assay, an XTT assay, apoptosis assays, and immunoprecipitation and western-blot assays. A preclinical human cancer xenograft model was used to test the efficacy of JY-1-106 in vivo.
  
  
  RESULTS
  MD and SILCS simulations of the JY-1-106-protein complexes indicated the importance of the aliphatic side chains of JY-1-106 to binding and successfully predicted the improved affinity of the ligand for Bcl-xL over Mcl-1. Ligand binding affinities were measured via an FP assay using a fluorescently labeled Bak-BH3 peptide in vitro. Apoptosis induction via JY-1-106 was evidenced by TUNEL assay and PARP cleavage as well as by Bax-Bax dimerization. Release of multi-domain Bak from its inhibitory binding to Bcl-2/Bcl-xL and Mcl-1 using JY-1-106 was detected via immunoprecipitation (IP) western blotting.At the cellular level, we compared the growth proliferation IC50s of JY-1-106 and ABT-737 in multiple cancer cell lines with various Bcl-xL and Mcl-1 expression levels. JY-1-106 effectively induced cell death regardless of the Mcl-1 expression level in ABT-737 resistant solid tumor cells, whilst toxicity toward normal human endothelial cells was limited. Furthermore, synergistic effects were observed in A549 cells using a combination of JY-1-106 and multiple chemotherapeutic agents. We also observed that JY-1-106 was a very effective agent in inducing apoptosis in metabolically stressed tumors. Finally, JY-1-106 was evaluated in a tumor-bearing nude mouse model, and was found to effectively repress tumor growth. Strong TUNEL signals in the tumor cells demonstrated the effectiveness of JY-1-106 in this animal model. No significant side effects were observed in mouse organs after multiple injections.
  
  
  CONCLUSIONS
  Taken together, these observations demonstrate that JY-1-106 is an effective pan-Bcl-2 inhibitor with very promising clinical potential.
authors.affiliation: Department of Surgery, Scott & White Memorial Hospital and Clinic, The Texas A&M University System, Health Science Center, College of Medicine, 702 SW HK Dodgen Loop, Temple, Texas 76504, USA.
authors.forename: Xiaobo
authors.initials: X
authors.lastname: Cao
authors.forename: Jeremy L
authors.initials: JL
authors.lastname: Yap
authors.forename: M Karen
authors.initials: MK
authors.lastname: Newell-Rogers
authors.forename: Chander
authors.initials: C
authors.lastname: Peddaboina
authors.forename: Weihua
authors.initials: W
authors.lastname: Jiang
authors.forename: Harry T
authors.initials: HT
authors.lastname: Papaconstantinou
authors.forename: Dan
authors.initials: D
authors.lastname: Jupitor
authors.forename: Arun
authors.initials: A
authors.lastname: Rai
authors.forename: Kwan-Young
authors.initials: KY
authors.lastname: Jung
authors.forename: Richard P
authors.initials: RP
authors.lastname: Tubin
authors.forename: Wenbo
authors.initials: W
authors.lastname: Yu
authors.forename: Kenno
authors.initials: K
authors.lastname: Vanommeslaeghe
authors.forename: Paul T
authors.initials: PT
authors.lastname: Wilder
authors.forename: Alexander D
authors.initials: AD
authors.lastname: MacKerell
authors.forename: Steven
authors.initials: S
authors.lastname: Fletcher
authors.forename: Roy W
authors.initials: RW
authors.lastname: Smythe
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis; D001549:Benzamides / Q000494:pharmacology*; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D008654:Mesothelioma / Q000378:metabolism / Q000473:pathology*; D051379:Mice; D056004:Molecular Dynamics Simulation; D018716:Molecular Mimicry; D064549:Myeloid Cell Leukemia Sequence 1 Protein / Q000378:metabolism*; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D023041:Xenograft Model Antitumor Assays; D050998:bcl-2 Homologous Antagonist-Killer Protein / Q000378:metabolism*; D051020:bcl-X Protein / Q000378:metabolism*; D062366:para-Aminobenzoates / Q000494:pharmacology*
chemical_list: D000970:Antineoplastic Agents; D001549:Benzamides; C587245:JY-1-106; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051020:bcl-X Protein; D062366:para-Aminobenzoates