A systematic assessment of chemical, genetic, and epigenetic factors influencing the activity of anticancer drug KP1019 (FFC14A)

Metallodrugs: Synthesis, mechanism of action and nanoencapsulation for targeted chemotherapy

As a multifactorial and heterogeneous disease, cancer has a high mortality rate, and the search for more effective treatments is an enormous challenge. Metal coordination compounds open a range of possibilities that conventional organic and biological molecules can no longer fulfil due to increasing drug resistance. Metallodrugs still have tremendous potential to help overcome drug resistance and find new cures in medicine, considering that at least 25 metallic elements participate in healthy functioning of the human body. Transition metal ions, such as copper, zinc and iron, are incorporated into catalytic proteins, the so-called metalloenzymes, which participate in various chemical reactions necessary for life. The interaction of metal complexes in different pathways with the structural richness of deoxyribonucleic acid encouraged to seek to understand the mechanisms of action and overcome the obstacles encountered for a promising future of these drugs. The success of platinum-based metallodrugs is one of the great inspirations for the search of new metallodrugs, although the approval of these molecules has been slow in recent years due to the risk of systemic toxicity and insufficient understanding of their mechanisms. To overcome the clinical limitations encountered in some metallodrugs, nanoencapsulation has been proposed as a new approach to improve therapeutic index in chemotherapy. The remarkable selectivity of nanoencapsulated metallodrugs and their enhanced capacity to bypass various biological barriers allow site-specific targeting. In this review, we present the advances in the development and use of the most relevant metallodrugs, and new delivery approaches, in the fight against cancer.

The Lipid Metabolism as Target and Modulator of BOLD-100 Anticancer Activity: Crosstalk with Histone Acetylation

The leading first-in-class ruthenium-complex BOLD-100 currently undergoes clinical phase-II anticancer evaluation. Recently, BOLD-100 is identified as anti-Warburg compound. The present study shows that also deregulated lipid metabolism parameters characterize acquired BOLD-100-resistant colon and pancreatic carcinoma cells. Acute BOLD-100 treatment reduces lipid droplet contents of BOLD-100-sensitive but not -resistant cells. Despite enhanced glycolysis fueling lipid accumulation, BOLD-100-resistant cells reveal diminished lactate secretion based on monocarboxylate transporter 1 (MCT1) loss mediated by a frame-shift mutation in the MCT1 chaperone basigin. Glycolysis and lipid catabolism converge in the production of protein/histone acetylation substrate acetyl-coenzymeA (CoA). Mass spectrometric and nuclear magnetic resonance analyses uncover spontaneous cell-free BOLD-100-CoA adduct formation suggesting acetyl-CoA depletion as mechanism bridging BOLD-100-induced lipid metabolism alterations and histone acetylation-mediated gene expression deregulation. Indeed, BOLD-100 treatment decreases histone acetylation selectively in sensitive cells. Pharmacological targeting confirms histone de-acetylation as central mode-of-action of BOLD-100 and metabolic programs stabilizing histone acetylation as relevant Achilles' heel of acquired BOLD-100-resistant cell and xenograft models. Accordingly, histone gene expression changes also predict intrinsic BOLD-100 responsiveness. Summarizing, BOLD-100 is identified as epigenetically active substance acting via targeting several onco-metabolic pathways. Identification of the lipid metabolism as driver of acquired BOLD-100 resistance opens novel strategies to tackle therapy failure.

Metallo-Drugs in Cancer Therapy: Past, Present and Future

Cancer treatments which include conventional chemotherapy have not proven very successful in curing human malignancies. The failures of these treatment modalities include inherent resistance, systemic toxicity and severe side effects. Out of 50% patients administrated to chemotherapy, only 5% survive. For these reasons, the identification of new drug designs and therapeutic strategies that could target cancer cells while leaving normal cells unaffected still continues to be a challenge. Despite advances that have led to the development of new therapies, treatment options are still limited for many types of cancers. This review provides an overview of platinum, copper and ruthenium metal based anticancer drugs in clinical trials and in vitro/in vivo studies. Presumably, copper and ruthenium complexes have greater potential than Pt(II) complexes, showing reduced toxicity, a new mechanism of action, a different spectrum of activity and the possibility of non-cross-resistance. We focus the discussion towards past, present and future aspects.

Bioactivity and Development of Small Non-Platinum Metal-Based Chemotherapeutics

Countless expectations converge in the multidisciplinary endeavour for the search and development of effective and safe drugs in fighting cancer. Although they still embody a minority of the pharmacological agents currently in clinical use, metal-based complexes have great yet unexplored potential, which probably hides forthcoming anticancer drugs. Following the historical success of cisplatin and congeners, but also taking advantage of conventional chemotherapy limitations that emerged with applications in the clinic, the design and development of non-platinum metal-based chemotherapeutics, either as drugs or prodrugs, represents a rapidly evolving field wherein candidate compounds can be fine-tuned to access interactions with druggable biological targets. Moving in this direction, over the last few decades platinum family metals, e.g., ruthenium and palladium, have been largely proposed. Indeed, transition metals and molecular platforms where they originate are endowed with unique chemical and biological features based on, but not limited to, redox activity and coordination geometries, as well as ligand selection (including their inherent reactivity and bioactivity). Herein, current applications and progress in metal-based chemoth are reviewed. Converging on the recent literature, new attractive chemotherapeutics based on transition metals other than platinum—and their bioactivity and mechanisms of action—are examined and discussed. A special focus is committed to anticancer agents based on ruthenium, palladium, rhodium, and iridium, but also to gold derivatives, for which more experimental data are nowadays available. Next to platinum-based agents, ruthenium-based candidate drugs were the first to reach the stage of clinical evaluation in humans, opening new scenarios for the development of alternative chemotherapeutic options to treat cancer.

Metallodrugs, an approach against invasion and metastasis in cancer treatment

Cancer is a heterogeneous and multifactorial disease that causes high mortality throughout the world; therefore, finding the most effective therapies is a major research challenge. Currently, most anticancer drugs present a limited number of well‐established targets, such as cell proliferation or death; however, it is important to consider that the worse progression of cancer toward pathological stages implies invasion and metastasis processes. Medicinal Inorganic Chemistry (MIC) is a young area that deals with the design, synthesis, characterization, preclinical evaluation, and mechanism of action of new inorganic compounds, called metallodrugs. The properties of metallic ions allow enriching of strategies for the design of new drugs, enabling the adjustment of physicochemical and stereochemical properties. Metallodrugs can adopt geometries, such as tetrahedral, octahedral, square planar, and square planar pyramid, which adjusts their arrangement and facilitates binding with a wide variety of targets. The redox properties of some metal ions can be modulated by the presence of the bound ligands to adjust their interaction, thereby opening a range of mechanisms of action. In this regard, the mechanisms of action that trigger the biological activity of metallodrugs have been generally identified by: (a) coordination of the metal to biomolecules (for instance, cisplatin binds to the N7 in DNA guanine, as Pt‐N via coordination of the inhibition of enzymes); (b) redox‐active; and (c) ROS production. For this reason, a series of metallodrugs can interact with several specific targets in the anti‐invasive processes of cancer and can prevent metastasis. The structural base of several metal compounds shows great anticancer potential by inhibiting the signaling pathways related to cancer progression. In this minireview, we present the advances in the field of antimetastatic effects of metallodrugs.

DMSO reduces the cytotoxicity of anticancer ruthenium complex KP1019 in yeast

Low solubility in aqueous solutions is a significant limitation of the otherwise promising anticancer ruthenium complex KP1019. In laboratory studies, this challenge is often overcome by using DMSO to help drive the drug into solution. Since DMSO was previously shown to alter the bioactivity of platinum-based chemotherapeutics, here we examine DMSO's effects on KP1019. Using Saccharomyces cerevisiae as a model organism, we apply multiple measures of growth inhibition to demonstrate that DMSO reduces the drug's toxicity. This reduction in bioactivity correlates with spectrophotometric changes consistent with DMSO-dependent increases in the stability of the KP1019 pro-drug. The impact of DMSO on the biology and chemistry of KP1019 suggests this solvent should not be used in studies of this and similar anticancer ruthenium complexes.

The Anticancer Activity of Indazole Compounds: A Mini Review

The incidence and mortality of cancer continue to grow since the current medical treatments often fail to produce a complete and durable tumor response and ultimately give rise to therapy resistance and tumor relapse. Heterocycles with potential therapeutic values are of great pharmacological importance, and among them, indazole moiety is a privileged structure in medicinal chemistry. Indazole compounds possess potential anticancer activity, and indazole-based agents such as, axitinib, lonidamine and pazopanib have already been employed for cancer therapy, demonstrating indazole compounds as useful templates for the development of novel anticancer agents. The aim of this review is to present the main aspects of exploring anticancer properties, such as the structural modifications, the structure-activity relationship and mechanisms of action, making an effort to highlight the importance and therapeutic potential of the indazole compounds in the present anticancer agents.

Cantharidin downregulates PSD1 expression and inhibits autophagic flux in yeast cells

Cantharidin is a terpenoid compound of insect origin, naturally produced by male blister beetles as an anti-predatory mechanism. Cantharidin has anticancer properties, which are attributed to its ability to induce cell cycle arrest, DNA damage, MAPK signalling pathway and apoptosis. Cantharidin has been reported to induce apoptosis in triple-negative breast cancer cells by suppressing autophagy via downregulation of Beclin 1 expression and autophagosome formation. However, it remains unclear which stage of the autophagic pathway is targeted by cantharidin. Herein, we report that yeast cells are sensitive to cantharidin, and external supplementation of ethanolamine (ETA) ameliorates the cytotoxicity. In addition, cantharidin downregulates phosphatidylserine decarboxylase1 (PSD1) expression. We also report that cantharidin inhibits autophagic flux, and external administration of ETA could rescue this inhibition. Additionally, co-treatment with chloroquine sensitized the autophagy inhibitory effects of cantharidin. We conclude that yeast cells are sensitive to cantharidin due to inhibition of autophagic flux.

ABC transporter Pdr5 is required for cantharidin resistance in Saccharomyces cerevisiae

Cantharidin is a potent anti-cancer drug and is known to exert its cytotoxic effects in several cancer cell lines. Although we have ample knowledge about its mode of action, we still know a little about cantharidin associated drug resistance mechanisms which dictates the efficacy and cytotoxic potential of this drug. In this direction, in the present study we employed Sacharomyces cerevisiae as a model organism and screened mutants of pleiotropic drug resistance network of genes for their susceptibility to cantharidin. We show that growth of pdr1Δ and pdr1Δpdr3Δ was severely reduced in presence of cantharidin whereas that of pdr3Δ remain unaffected when compared to wildtype. Loss of one of the PDR1 target genes PDR5, encoding an ABC membrane efflux pump, rendered the cells hypersensitive whereas overexpression of it conferred resistance. Additionally, cantharidin induced the upregulation of both PDR1 and PDR5 genes. Interestingly, pdr1Δpdr5Δ double deletion mutants were hypersensitive to cantharidin showing a synergistic effect in its cellular detoxification. Furthermore, transcriptional activation of PDR5 post cantharidin treatment was majorly dependent on the presence of Pdr1 and less significantly of Pdr3 transcription factors. Altogether our findings suggest that Pdr1 acts to increase cantharidin resistance by elevating the level of Pdr5 which serves as a major detoxification safeguard under CAN stress.

Proteomic analysis of the S. cerevisiae response to the anticancer ruthenium complex KP1019

Like platinum-based chemotherapeutics, the anticancer ruthenium complex indazolium trans-[tetrachlorobis(1H-indazole)ruthenate(iii)], or KP1019, damages DNA, induces apoptosis, and causes tumor regression in animal models. Unlike platinum-based drugs, KP1019 showed no dose-limiting toxicity in a phase I clinical trial. Despite these advances, the mechanism(s) and target(s) of KP1019 remain unclear. For example, the drug may damage DNA directly or by causing oxidative stress. Likewise, KP1019 binds cytosolic proteins, suggesting DNA is not the sole target. Here we use the budding yeast Saccharomyces cerevisiae as a model in a proteomic study of the cellular response to KP1019. Mapping protein level changes onto metabolic pathways revealed patterns consistent with elevated synthesis and/or cycling of the antioxidant glutathione, suggesting KP1019 induces oxidative stress. This result was supported by increased fluorescence of the redox-sensitive dye DCFH-DA and increased KP1019 sensitivity of yeast lacking Yap1, a master regulator of the oxidative stress response. In addition to oxidative and DNA stress, bioinformatic analysis revealed drug-dependent increases in proteins involved ribosome biogenesis, translation, and protein (re)folding. Consistent with proteotoxic effects, KP1019 increased expression of a heat-shock element (HSE) lacZ reporter. KP1019 pre-treatment also sensitized yeast to oxaliplatin, paralleling prior research showing that cancer cell lines with elevated levels of translation machinery are hypersensitive to oxaliplatin. Combined, these data suggest that one of KP1019's many targets may be protein metabolism, which opens up intriguing possibilities for combination therapy.

Anti-cancer properties of ruthenium compounds: NAMI-A and KP1019

Cancer research is among the key challenges in current medicine and biology. Many decades of investigations have brought measurable benefits in both areas with regard to expanding the knowledge of the molecular mechanism of cancer and developing treatment strategies. Despite that cancers are still among diseases with the highest mortality rate, and cancer treatment is often unsuccessful and connected with severe side effects. The development of therapeutic strategies in both targeting the primary tumor origin and preventing metastasis is largely based on testing newly synthesized chemical agents, including a group of metal-containing complexes. It seems that ruthenium-containing complexes are of high potential in cancer therapy, and our work presents the current data about the application of ruthenium-based complexes − NAMI-A and KP1019 in cancer therapy.

NAMI-A and KP1019/1339, Two Iconic Ruthenium Anticancer Drug Candidates Face-to-Face: A Case Story in Medicinal Inorganic Chemistry

NAMI-A ((ImH)[trans-RuCl₄(dmso-S)(Im)], Im = imidazole) and KP1019/1339 (KP1019 = (IndH)[trans-RuCl₄(Ind)₂], Ind = indazole; KP1339 = Na[trans-RuCl₄(Ind)₂]) are two structurally related ruthenium(III) coordination compounds that have attracted a lot of attention in the medicinal inorganic chemistry scientific community as promising anticancer drug candidates. This has led to a considerable amount of studies on their respective chemico-biological features and to the eventual admission of both to clinical trials. The encouraging pharmacological performances qualified KP1019 mainly as a cytotoxic agent for the treatment of platinum-resistant colorectal cancers, whereas the non-cytotoxic NAMI-A has gained the reputation of being a very effective antimetastatic drug. A critical and strictly comparative analysis of the studies conducted so far on NAMI-A and KP1019 allows us to define the state of the art of these experimental ruthenium drugs in terms of the respective pharmacological profiles and potential clinical applications, and to gain some insight into the inherent molecular mechanisms. Despite their evident structural relatedness, deeply distinct biological and pharmacological profiles do emerge. Overall, these two iconic ruthenium complexes form an exemplary and unique case in the field of medicinal inorganic chemistry.

Exploring cellular uptake, accumulation and mechanism of action of a cationic Ru-based nanosystem in human preclinical models of breast cancer

According to WHO, breast cancer incidence is increasing so that the search for novel chemotherapeutic options is nowadays an essential requirement to fight neoplasm subtypes. By exploring new effective metal-based chemotherapeutic strategies, many ruthenium complexes have been recently proposed as antitumour drugs, showing ability to impact on diverse cellular targets. In the framework of different molecular pathways leading to cell death in human models of breast cancer, here we demonstrate autophagy involvement behind the antiproliferative action of a ruthenium(III)-complex incorporated into a cationic nanosystem (HoThyRu/DOTAP), proved to be hitherto one of the most effective within the suite of nucleolipidic formulations we have developed for the in vivo transport of anticancer ruthenium(III)-based drugs. Indeed, evidences are implicating autophagy in both cancer development and therapy, and anticancer interventions endowed with the ability to trigger this biological response are currently considered attractive oncotherapeutic approaches. Moreover, crosstalk between apoptosis and autophagy, regulated by finely tuned metallo-chemotherapeutics, may provide novel opportunities for future improvement of cancer treatment. Following this line, our in vitro and in vivo preclinical investigations suggest that an original strategy based on suitable formulations of ruthenium(III)-complexes, inducing sustained cell death, could open new opportunities for breast cancer treatment, including the highly aggressive triple-negative subtype.

Challenges and Chances in the Preclinical to Clinical Translation of Anticancer Metallodrugs

Despite being “sentenced to death” for quite some time, anticancer platinum compounds are still the most frequently prescribed cancer therapies in the oncological routine and recent exciting news from late-stage clinical studies on combinations of metallodrugs with immunotherapies suggest that this situation will not change soon. It is perhaps surprising that relatively simple molecules like cisplatin, discovered over 50 years ago, are still widely used clinically, while none of the highly sophisticated metal compounds developed over the last decade, including complexes with targeting ligands and multifunctional (nano)formulations, have managed to obtain clinical approval. In this book chapter, we summarize the current status of ongoing clinical trials for anticancer metal compounds and discuss the reasons for previous failures, as well as new opportunities for the clinical translation of metal complexes.