SU-11752 is a potent and selective DNA-PK inhibitor. Inhibition kinetics and a direct assay for ATP binding showed that SU11752 inhibited DNA-PK by competing with ATP. SU11752 inhibited DNAdouble-strandbreak repair in cells and gave rise to a five-fold sensitization to ionizing radiation. At concentrations of SU11752 that inhibited DNA repair, cell cycle progression was still normal and ATM kinase activity was not inhibited.
T2AA, a proliferating cell nuclear antigen (PCNA) inhibitor, disrupts protein-protein interactions between PCNA and both a PIP-box-containing peptide (IC50= 1 μM) and full-length p21, reducing cellular colocalization of PCNA with DNA polymerase δ. This compound effectively inhibits DNA replication and cell proliferation in U2OS and HeLa cells in a concentration-dependent manner, additionally inducing S phase cell cycle arrest at a 20 μM concentration. Furthermore, T2AA enhances DNAdoublestrandbreak formation alongside cisplatin in a neutral comet assay and augments cisplatin-induced reductions in clonogenic survival in HeLa and U2OS cells.