Cellular sensitivity to β-diketonato complexes of ruthenium(III) and chromium(III).

A100

The aim of this study was to investigate cellular response to ruthenium(III), and chromium(III) compounds carrying bidentate beta-diketonato ligands: [(acac)-acetylacetonate, (tfac)-trifluoroacetylacetonate]. Cell sensitivity studies were performed on several cell lines (A2780, cisplatin-sensitive and -resistant U2-OS and U2-OS/Pt, HeLa, B16, K562 and Jurkat) using growth-inhibition assay. Antiproliferative effect of Ru(acac)3 in combination with and cisplatin / oxaliplatin as a standards, was analyzed on HeLa cells, using Calcy Syn softver for median effect analysis. Flow cytometry was used to assess apoptosis by Annexin-V-FITC/PI staining, and to analyze induction of caspase-3 activity. Possible DNA binding/damaging affinity was investigated, by inductively coupled mass spectrometry, and by (13)C-thymidine / (3)H-uridine incorporation assay. Potential inhibitory effect of Ru(III) drugs on metalloproteinases MMP-2 and MMP-9, was investigated by gelatin-zymography. Cell sensitivity studies showed that the pattern of sensitivity to Ru(tfac)3 complex of the two cisplatin-sensitive/-resistant osteosarcoma cell lines, U2-OS and U2-OS/Pt, was similar to that of A2780 cells (72 h exposure), the IC50 being around 40 uM. The growth-inhibitory effect of Ru(acac)3 ranged over 100 uM, while Cr(acac)3 was completely devoid of antitumor action. Ru(acac)3 demonstrated synergistic effect in combination with cisplatin (IC < 1); however in combination with oxaliplatin values IC > 1 indicated antagonistic interaction. Ru(tfac)3 exhibited strong potential for apoptosis induction on A2780 cells (up to 40%) and caused cell cycle arrest in the S phase. Ru(acac)3-induced apoptosis was slightly higher than 10% whereas activation of caspase-3 in HeLa cells, was moderate. Ru(acac)3 exhibited inhibitory effect on pro-/active- MMP-2, as demonstrated by gelatin zymography. DNA binding study revealed that only Cr(acac)3 was capable of binding DNA, while Cr(III) and Ru(III) compounds, possess potential to inhibit DNA/RNA synthesis. In conclusion, capability of Ru(III) compounds to induce apoptosis and inhibit MMP-2 action, provides rational to investigate ruthenium based drugs as metastasis-preventive agents in combination therapy.