Multifaceted studies into the bioinorganic chemistry of ruthenium(II) arene anticancer complexes

Abstract

Ru(II) arene complexes are attractive anticancer drugs but their mechanisms of action and biological targets are not fully known, and new aspects of their modes of action are a focus of this thesis. A Ru(II) arene complex library covering a variety of ligands and diverse antitumour activities was investigated using spectroscopic techniques, biochemical assays and live cell analyses, to elucidate their mechanisms of action and biological targets. These studies were conducted on two breast cancer cell lines, the aggressive TNBC cell line, MDA-MB-231, and less aggressive epithelial cell line, MCF-7. A large complex-dependent range of antiproliferative activities and cell line sensitivities were observed.

In the first study of EV biochemistry changes, the FTIR spectra of the mainly microvesicle and mainly exosome fractions released by these cells following Ru arene complex treatment showed biochemical content varied greatly by proposed drug modes of action. The first research on the Ru anticancer drug interactions with proteoglycans comprised studies on the interactions of the library, and well-studied Ru(III) drugs NAMI-A and KP1019, with the heparan sulfate mimetic fondaparinux, using NSI-MS, UV-Vis reporter assays and heparinase II inhibition assays. The interactions depended on the initial complex charges, as fondaparinux has a large negative charge, and ligand exchange rates. Ligand exchange reactions were studied by XAS on the RAPTA and RAED complexes, which provided strong evidence for ligand-exchange of non-arene ligands with sulfur-donor ligands in both cells and cell medium and with the serum albumin protein. XFM and FTIR microscopy mapping experiments were performed on the two cell lines treated with RAPTA-C and RAED-C. This provided complementary information about intracellular distribution of these drugs and their biochemical impact on cells. RAPTA-C had strongest interactions with the cell surface region, while RAED-C targeted intracellular interactions.