Related Experiment Video
Updated: May 24, 2026

Through the Looking Glass: Time-lapse Microscopy and Longitudinal Tracking of Single Cells to Study Anti-cancer Therapeutics
Published on: May 14, 2016
Identification of small molecule proliferating cell nuclear antigen (PCNA) inhibitor that disrupts interactions with
Chandanamali Punchihewa1, Akira Inoue, Asami Hishiki
1Department of Chemical Biology and Therapeutics, St Jude Children’s Research Hospital, Memphis, Tennessee 38105, USA.
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.
Related Concept Videos
Negative Regulator Molecules
Restarting Stalled Replication Forks
Inhibition of Cdk Activity
Inhibition of CDK Activity
DNA Damage Can Stall the Cell Cycle
DNA Damage can Stall the Cell Cycle
