Title:CDK1 Hyperphosphorylation Maintenance Drives the Time-course of G2-M Cell Cycle Arrest after Short Treatment with NAMI-A in Kb Cells
Volume: 12
Issue: 8
Author(s): Alberta Bergamo, Riccarda Delfino, Claudia Casarsa and Gianni Sava
Affiliation:
Keywords:
Cancer, Cell cycle, In vitro, Metastasis, Ruthenium, Treatment, signal transduction modulator, oral carcinoma, Ataxia telangiectasia-mutated protein kinase, phosphatases
Abstract: We investigated the molecular events of the ruthenium complex NAMI-A (0.1 mM for 1 h) on cell cycle G2-M arrest in KB
carcinoma cells. Flow cytometry analysis showed a progressive accumulation of cells in S phase at 16 h, and in G2-M phase at 20 h after
the end of treatment. NAMI-A pre-mitotic stop to cell proliferation was due to the maintenance of the phosphorylated, inactive, form of
Cdk1, caused by the activation of the ATM/ATR checkpoint, as confirmed by the up-regulation and phosphorylation of Chk1. All these
events are related to intracellular ruthenium accumulation, as confirmed by the lack of similar effects in cell lines unable to take the
ruthenium compound up. Considering the dependence of NAMI-A cell cycle arrest on the dose and on the length of cell challenge, and
considering the prolonged NAMI-A t1/2 in vivo in the lungs, we proved an even greater perturbation of the cell cycle regulating pathways
in lung metastases of NAMI-A treated mice. The ex-vivo data confirm the interaction of the ruthenium compound NAMI-A with the
ATM/ATR pathway, leading to the modulation of cell cycle regulating proteins, that can break the metastases cell cycle progression off.
