title: Identification of small molecule proliferating cell nuclear antigen (PCNA) inhibitor that disrupts interactions with PIP-box proteins and inhibits DNA replication.
abstract: We have discovered that 3,3',5-triiodothyronine (T3) inhibits binding of a PIP-box sequence peptide to proliferating cell nuclear antigen (PCNA) protein by competing for the same binding site, as evidenced by the co-crystal structure of the PCNA-T3 complex at 2.1 Å resolution. Based on this observation, we have designed a novel, non-peptide small molecule PCNA inhibitor, T2 amino alcohol (T2AA), a T3 derivative that lacks thyroid hormone activity. T2AA inhibited interaction of PCNA/PIP-box peptide with an IC(50) of ~1 μm and also PCNA and full-length p21 protein, the tightest PCNA ligand protein known to date. T2AA abolished interaction of PCNA and DNA polymerase δ in cellular chromatin. De novo DNA synthesis was inhibited by T2AA, and the cells were arrested in S-phase. T2AA inhibited growth of cancer cells with induction of early apoptosis. Concurrently, Chk1 and RPA32 in the chromatin are phosphorylated, suggesting that T2AA causes DNA replication stress by stalling DNA replication forks. T2AA significantly inhibited translesion DNA synthesis on a cisplatin-cross-linked template in cells. When cells were treated with a combination of cisplatin and T2AA, a significant increase in phospho(Ser(139))histone H2AX induction and cell growth inhibition was observed.
authors.affiliation: Department of Chemical Biology and Therapeutics, St Jude Children’s Research Hospital, Memphis, Tennessee 38105, USA.
authors.forename: Chandanamali
authors.initials: C
authors.lastname: Punchihewa
authors.forename: Akira
authors.initials: A
authors.lastname: Inoue
authors.forename: Asami
authors.initials: A
authors.lastname: Hishiki
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Fujikawa
authors.forename: Michele
authors.initials: M
authors.lastname: Connelly
authors.forename: Benjamin
authors.initials: B
authors.lastname: Evison
authors.forename: Youming
authors.initials: Y
authors.lastname: Shao
authors.forename: Richard
authors.initials: R
authors.lastname: Heath
authors.forename: Isao
authors.initials: I
authors.lastname: Kuraoka
authors.forename: Patrick
authors.initials: P
authors.lastname: Rodrigues
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Hashimoto
authors.forename: Masanobu
authors.initials: M
authors.lastname: Kawanishi
authors.forename: Mamoru
authors.initials: M
authors.lastname: Sato
authors.forename: Takashi
authors.initials: T
authors.lastname: Yagi
authors.forename: Naoaki
authors.initials: N
authors.lastname: Fujii
mesh_terms: D002626:Chemistry, Pharmaceutical / Q000379:methods; D002843:Chromatin / Q000378:metabolism; D018360:Crystallography, X-Ray / Q000379:methods; D004261:DNA Replication / Q000502:physiology*; D015195:Drug Design; D005434:Flow Cytometry / Q000379:methods; D017930:Genes, Reporter; D006367:HeLa Cells; D006801:Humans; D020128:Inhibitory Concentration 50; D008024:Ligands; D008856:Microscopy, Fluorescence / Q000379:methods; D008968:Molecular Conformation; D010455:Peptides / Q000737:chemistry; D010766:Phosphorylation; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism*; D025941:Protein Interaction Mapping / Q000379:methods; D011994:Recombinant Proteins / Q000737:chemistry
chemical_list: D002843:Chromatin; D008024:Ligands; D010455:Peptides; D018809:Proliferating Cell Nuclear Antigen; D011994:Recombinant Proteins