Metal-Based Anticancer Complexes and p53: How Much Do We Know?

P53 plays a key role in protecting the human genome from DNA-related mutations; however, it is one of the most frequently mutated genes in cancer. The P53 family members p63 and p73 were also shown to play important roles in cancer development and progression. Currently, there are various organic molecules from different structural classes of compounds that could reactivate the function of wild-type p53, degrade or inhibit mutant p53, etc. It was shown that: (1) the function of the wild-type p53 protein was dependent on the presence of Zn atoms, and (2) Zn supplementation restored the altered conformation of the mutant p53 protein. This prompted us to question whether the dependence of p53 on Zn and other metals might be used as a cancer vulnerability. This review article focuses on the role of different metals in the structure and function of p53, as well as discusses the effects of metal complexes based on Zn, Cu, Fe, Ru, Au, Ag, Pd, Pt, Ir, V, Mo, Bi and Sn on the p53 protein and p53-associated signaling.

Coordination of Ru(II)-Arene Fragments to Dipyridophenazine Ligands Leads to the Modulation of Their In Vitro and In Vivo Anticancer Activity

Despite extensive research on the anticancer properties of Ru complexes with dipyrido[3,2-a:2',3'-c]phenazine (dppz) ligands, their in vivo efficacy is rarely investigated. Aiming to understand whether the coordination of certain half-sandwich Ru(II)-arene fragments might improve the therapeutic potential of dppz ligands, we prepared a series of Ru(II)-arene complexes with the general formula [(η⁶-arene)Ru(dppz-R)Cl]PF₆, where the arene fragment was benzene, toluene, or p-cymene and R was -NO₂, -Me, or -COOMe. All compounds were fully characterized by ¹H and ¹³C NMR spectroscopy and high-resolution ESI mass-spectrometry, and their purity was verified by elemental analysis. The electrochemical activity was investigated using cyclic voltammetry. The anticancer activity of dppz ligands and their respective Ru complexes was assessed against several cancer cell lines, and their selectivity toward cancer cells was assessed using healthy MRC5 lung fibroblasts. The substitution of benzene with a p-cymene fragment resulted in a more than 17-fold increase of anticancer activity and selectivity of Ru complexes and significantly enhanced DNA degradation in HCT116 cells. All Ru complexes were electrochemically active in the biologically accessible redox window and were shown to markedly induce the production of ROS in mitochondria. The lead Ru-dppz complex significantly reduced tumor burden in mice with colorectal cancers without inducing liver and kidney toxicity.

Toward "E-ring-free" lamellarin analogues: synthesis and preliminary biological evaluation

Since the discovery of anticancer properties of a naturally occurring hexacyclic marine alkaloid Lamellarin D, the attempts have been made to prepare its synthetic analogues and elucidate the effects of each structural component on their activity profile. While F-ring-free, A-ring-free and B-ring-open lamellarins are known, E-ring-free analogues have never been investigated. In this work, we developed a facile and straightforward synthetic method toward E-ring-free lamellarin analogues based on the [3+2]-cycloaddition. For the first time, we prepared several pentacyclic lamellarin analogues without E-ring in their structure and assessed their cytotoxicity in a panel of cancer cell lines in comparison with several hexacyclic lamellarins. E-ring-free lamellarins were devoid of cytotoxicity due to their poor solubility in cellular environment, indicating the importance of E-ring for the therapeutic efficacy of lamellarins.

Elucidation of Structure-Activity Relationships in Indolobenzazepine-Derived Ligands and Their Copper(II) Complexes: the Role of Key Structural Components and Insight into the Mechanism of Action

Indolo[3,2-d][1]benzazepines (paullones), indolo[3,2-d][2]benzazepines, and indolo[2,3-d][2]benzazepines (latonduines) are isomeric scaffolds of current medicinal interest. Herein, we prepared a small library of novel indolo[3,2-d][2]benzazepine-derived ligands HL¹-HL⁴ and copper(II) complexes 1-4. All compounds were characterized by spectroscopic methods (¹H and ¹³C NMR, UV-vis, IR) and electrospray ionization (ESI) mass spectrometry, while complexes 2 and 3, in addition, by X-ray crystallography. Their purity was confirmed by HPLC coupled with high-resolution ESI mass spectrometry and/or elemental analysis. The stability of compounds in aqueous solutions in the presence of DMSO was confirmed by ¹H NMR and UV-vis spectroscopy measurements. The compounds revealed high antiproliferative activity in vitro in the breast cancer cell line MDA-MB-231 and hepatocellular carcinoma cell line LM3 in the low micromolar to nanomolar concentration range. Important structure-activity relationships were deduced from the comparison of anticancer activities of HL¹-HL⁴ and 1-4 with those of structurally similar paullone-derived (HL⁵-HL⁷ and 5-7) and latonduine-derived scaffolds (HL⁸-HL¹¹ and 8-11). The high anticancer activity of the lead drug candidate 4 was linked to reactive oxygen species and endoplasmic reticulum stress induction, which were confirmed by fluorescent microscopy and Western blot analysis.