5 research outputs found
A ruthenium polypyridyl intercalator stalls DNA replication forks, radiosensitizes human cancer cells and is enhanced by Chk1 inhibition
Ruthenium(II) polypyridyl complexes can intercalate DNA with high affinity and prevent cell
proliferation; however, the direct impact of ruthenium-based intercalation on cellular DNA replication
remains unknown. Here we show the multi-intercalator [Ru(dppz)2(PIP)]2+ (dppz =
dipyridophenazine, PIP = 2-(phenyl)imidazo[4,5-f][1,10]phenanthroline) immediately stalls
replication fork progression in HeLa human cervical cancer cells. In response to this replication
blockade, the DNA damage response (DDR) cell signalling network is activated, with checkpoint
kinase 1 (Chk1) activation indicating prolonged replication-associated DNA damage, and cell
proliferation is inhibited by G1-S cell-cycle arrest. Co-incubation with a Chk1 inhibitor achieves
synergistic apoptosis in cancer cells, with a significant increase in phospho(Ser139) histone H2AX (γ-
H2AX) levels and foci indicating increased conversion of stalled replication forks to double-strand
breaks (DSBs). Normal human epithelial cells remain unaffected by this concurrent treatment.
Furthermore, pre-treatment of HeLa cells with [Ru(dppz)2(PIP)]2+ before external beam ionising
radiation results in a supra-additive decrease in cell survival accompanied by increased γ-H2AX
expression, indicating the compound functions as a radiosensitizer. Together, these results indicate ruthenium-based intercalation can block replication fork progression and demonstrate how these
DNA-binding agents may be combined with DDR inhibitors or ionising radiation to achieve more
efficient cancer cell killing