ABSTRACT
We report the design, synthesis and biological studies on a group of mixed ligand Fe(III) complexes as anti-cancer drug candidates, namely their interaction with DNA, cytotoxicity and mechanism(s) of action. The aim is to obtain stable, efficient and selective Fe-complexes to be used as anti-cancer agents with less damaging side effects than previously reported compounds. Five ternary Fe(III) complexes bearing a tripodal aminophenolate ligand L2-, H2L = N,N-bis(2-hydroxy-3,5-dimethylbenzyl)-N-(2-pyridylmethyl)amine, and different aromatic bases NNâ¯=â¯2,2'-bipyridine [Fe(L)(bipy)]PF6 (1), 1,10-phenanthroline [Fe(L)(phen)]PF6 (2), or a phenanthroline derivative co-ligand: [Fe(L)(amphen)]NO3 (3), [Fe(L)(amphen)]PF6 (3a), [Fe(L)(Clphen)]PF6 (4), [Fe(L)(epoxyphen)]PF6 (5) (where amphenâ¯=â¯1,10-phenanthroline-5-amine, epoxyphenâ¯=â¯5,6-epoxy-5,6-dihydro-1,10-phenanthroline, Clphenâ¯=â¯5-chloro-1,10-phenanthroline) and the [Fe(L)(EtOH)]NO3 (6) complex are synthesized. The compounds are characterized in the solid state and in solution by elemental analysis, ESI-MS, magnetic susceptibility measurements and FTIR, UV-Vis, 1H and 13C NMR and fluorescence spectroscopies. [Fe(phen)Cl3] and [Fe(amphen)Cl3] were also prepared for comparison purposes. Spectroscopic binding studies indicate groove binding as the main interaction for most complexes with DNA, and for those containing amphen a B- to Z-DNA conformational change is proposed to occur. As determined via MTT analysis all compounds 1-6 are cytotoxic against a panel of three different cell lines (HeLa, H1299, MDA-MB-231). For selected compounds with promising cytotoxic activity, apoptosis was evaluated using cell and DNA morphology, TUNEL, Annexin V/7AAD staining and caspase3/7 activity. The compounds induce oxidative DNA damage on plasmid DNA and in cell culture as assessed by 8-oxo-Guanine and γH2AX staining. Comet assay confirmed the presence of genomic damage. There is also increased reactive oxygen species formation following drug treatment, which may be the relevant mechanism of action, thus differing from that normally assumed for cisplatin. The Fe(III)-complexes were also tested against strains of M. Tuberculosis (MTb), complex 2 depicting higher anti-MTb activity than several known second line drugs. Hence, these initial studies show prospective anti-cancer and anti-MTb activity granting promise for further studies.
Subject(s)
Antineoplastic Agents/pharmacology , Coordination Complexes/pharmacology , Iron/chemistry , Phenanthrolines/pharmacology , Antineoplastic Agents/chemical synthesis , Antineoplastic Agents/chemistry , Antineoplastic Agents/toxicity , Antitubercular Agents/chemical synthesis , Antitubercular Agents/chemistry , Antitubercular Agents/pharmacology , Antitubercular Agents/toxicity , Apoptosis/drug effects , Cell Line, Tumor , Coordination Complexes/chemical synthesis , Coordination Complexes/chemistry , Coordination Complexes/toxicity , DNA/chemistry , DNA Breaks, Double-Stranded/drug effects , DNA Fragmentation/drug effects , Drug Design , Drug Stability , Humans , Ligands , Mycobacterium tuberculosis/drug effects , Phenanthrolines/chemical synthesis , Phenanthrolines/chemistry , Phenanthrolines/toxicity , Prospective Studies , Reactive Oxygen Species/metabolismABSTRACT
Overcoming drug resistance is a major challenge for cancer therapy. Tumor necrosis factor α-related apoptosis-inducing ligand (TRAIL) is a potent therapeutic as an activator of apoptosis, particularly in tumor but not in healthy cells. However, its efficacy is limited by the resistance of tumor cell populations to the therapeutic substance. Here, we have addressed this limitation through the development of a controlled release system, matrix-metalloproteinase (MMP)-sensitive and arg-gly-asp-ser (RGDS) peptide functionalized poly (ethylene-glycol) (PEG) particles which are synthesized via visible-light-induced water-in-water emulsion polymerization. Quinacrine (QC), a recently discovered TRAIL sensitizer drug, is loaded into the hydrogel carriers and the influence of this system on the apoptosis of a malignant type of brain cancer, glioblastoma multiforme (GBM), has been investigated in detail. The results suggest that MMP-sensitive particles are cytocompatible and superior to promote TRAIL-induced apoptosis in GBM cells when loaded with QC. Compared to QC and TRAIL alone, combination of QC-loaded PEG hydrogel and TRAIL demonstrates synergistic apoptotic inducing behavior. Furthermore, QC-loaded particles, but not QC or PEG-hydrogels alone, enhance apoptosis as is measured through expression of apoptosis-related genes. This system is promising to significantly improve the efficacy of chemotherapeutic drugs and suggests a combination treatment for GBM therapy.
