LC- and CZE-ICP-MS approaches for the in vivo analysis of the anticancer drug candidate sodium trans-[tetrachloridobis(1H-indazole)ruthenate(III)] (KP1339) in mouse plasma

Investigating the Interaction of an Anticancer Nucleolipidic Ru(III) Complex with Human Serum Proteins: A Spectroscopic Study

Ruthenium(III) complexes are very promising candidates as metal-based anticancer drugs, and several studies have supported the likely role of human serum proteins in the transport and selective delivery of Ru(III)-based compounds to tumor cells. Herein, the anticancer nanosystem composed of an amphiphilic nucleolipid incorporating a Ru(III) complex, which we named DoHuRu, embedded into the biocompatible cationic lipid DOTAP, was investigated as to its interaction with two human serum proteins thought to be involved in the mechanism of action of Ru(III)-based anticancer drugs, i.e., human serum albumin (HSA) and human transferrin (hTf). This nanosystem was studied in comparison with the simple Ru(III) complex named AziRu, a low molecular weight metal complex previously designed as an analogue of NAMI-A, decorated with the same ruthenium ligands as DoHuRu but devoid of the nucleolipid scaffold and not inserted in liposomal formulations. For this study, different spectroscopic techniques, i.e., Fluorescence Spectroscopy and Circular Dichroism (CD), were exploited, showing that DoHuRu/DOTAP liposomes can interact with both serum proteins without affecting their secondary structures.

Thermodynamics-based rules of thumb to evaluate the interaction of chelators and kinetically-labile metal ions in blood serum and plasma

Metal ions play a very important role in nature and their homeostasis is crucial. A lot of metal-related chemical research activities are ongoing that concern metal-based drugs or tools, such as chelation therapy, metal- and metabolite sensors, metallo-drugs and prodrugs, PET and MRI imaging agents, etc. In most of these cases, the applied chelator/ligand (L) or metal-ligand complex (M-L) has at least to pass the blood plasma to reach the target. Hence it is exposed to several metal-binding proteins (mainly serum albumin and transferrin) and to all essential metal ions (zinc, copper, iron, etc.). This holds also for studies in cultured cells when fetal calf serum is used in the medium. There is a risk that the applied compound (L or M-L) in the serum is transformed into a different entity, due to trans-metallation and/or ligand exchange reactions. This depends on the thermodynamics and kinetics. For kinetically-labile complexes, the complex stability with all the ligands and all metal ions present in serum is decisive in evaluating the thermodynamic driving force towards a certain fate of the chelator or metal-ligand complex. To consider that, an integrative view is needed on the stability constants, by taking into account all the metal ions present and all the main proteins to which they are bound, as well as the non-occupied metal binding site in proteins. Only then, a realistic estimation of the complex stability, and hence its potential fate, can be done. This perspective aims to provide a simple approach to estimate the thermodynamic stability of labile metal-ligand complexes in a blood plasma/serum environment. It gives a guideline to obtain an estimation of the plasma and serum complex stability and metal selectivity starting from the chemical stability constants of metal-ligand complexes. Although of high importance, it does not focus on the more complex kinetic aspects of metal-transfer reactions. The perspective should help for a better design of such compounds, to perform test tube assays which are relevant to the conditions in the plasma/serum and to be aware of the importance of ternary complexes, kinetics and competition experiments.

Crystallographic analysis of interaction between cisplatin and human serum albumin: Effect of fatty acid

Metallodrugs are important for anticancer treatments. They bind mainly to human serum albumin (HSA) in blood circulation, greatly modulating their pharmacokinetics and anticancer efficacy. Fatty acid (FA) is one of the most important endogenous ligands of HSA with tight binding to HSA and affecting its conformation. However, the effect of fatty acids on metallodrugs interaction with HSA is unknown. Here we identify the binding sites of a widely used metallodrug, cisplatin, in HSA in the presence or absence of a representative fatty acid, myristate, by X-ray crystallography. Our crystal structures indicate that the sidechain of residue Met548 becomes more exposed to solvent in the presence of fatty acid, and is the main Pt binding site together with Met329 in HSA:Myr:cisplatin ternary structure. An undoubted new Pt binding site is detected at His338 in the presence of fatty acid, and additional two sites are also identified at His146 and His440 + K436. In addition, we revealed the mechanism of cisplatin-induced HSA aggregation, which is due to the crosslinking between Met298 and His510 of two HSA molecules.

Simultaneous Quantification and Speciation of Trace Metals in Paired Serum and CSF Samples by Size Exclusion Chromatography-Inductively Coupled Plasma-Dynamic Reaction Cell-Mass Spectrometry (SEC-DRC-ICP-MS)

BACKGROUND

Transition metals play a crucial role in brain metabolism: since they exist in different oxidation states they are involved in ROS generation, but they are also co-factors of enzymes in cellular energy metabolism or oxidative defense.

METHODS

Paired serum and cerebrospinal fluid (CSF) samples were analyzed for iron, zinc, copper and manganese as well as for speciation using SEC-ICP-DRC-MS. Brain extracts from Mn-exposed rats were additionally analyzed with SEC-ICP-DRC-MS.

RESULTS

The concentration patterns of transition metal size fractions were correlated between serum and CSF: Total element concentrations were significantly lower in CSF. Fe-ferritin was decreased in CSF whereas a LMW Fe fraction was relatively increased. The 400-600 kDa Zn fraction and the Cu-ceruloplasmin fraction were decreased in CSF, by contrast the 40-80 kDa fraction, containing Cu- and Zn-albumin, relatively increased. For manganese, the α-2-macroglobulin fraction showed significantly lower concentration in CSF, whereas the citrate Mn fraction was enriched. Results from the rat brain extracts supported the findings from human paired serum and CSF samples.

CONCLUSIONS

Transition metals are strictly controlled at neural barriers (NB) of neurologic healthy patients. High molecular weight species are down-concentrated along NB, however, the Mn-citrate fraction seems to be less controlled, which may be problematic under environmental load.

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.

Die Wechselwirkung mit ribosomalen Proteinen begleitet die Stressinduktion des Wirkstoffkandidaten BOLD-100/KP1339 im endoplasmatischen Retikulum

Der metallhaltige Wirkstoff BOLD‐100/KP1339 zeigte bereits vielversprechende Resultate in verschiedenen In vitro‐ und In vivo‐Tumormodellen sowie in klinischen Studien. Der detaillierte Wirkmechanismus wurde jedoch noch nicht komplett aufgeklärt. Als entscheidende Wirkstoffeffekte kristallisierten sich kürzlich die Stressinduktion im endoplasmatischen Retikulum (ER) und die damit einhergehende Modulierung von HSPA5 (GRP78) heraus. Das spontane und stabile Addukt zwischen BOLD‐100 und menschlichem Serumalbumin wurde als Immobilisierungsstrategie ausgewählt, um einen chemoproteomischen Ansatz auszuführen, der die ribosomalen Proteine RPL10, RPL24 und den Transkriptionsfaktor GTF2I als potentielle Interaktoren dieser Ru(III)‐Verbindung identifizierten. Dieses Ergebnis wurde mit proteomischen und transkriptomischen Profiling‐Experimenten kombiniert, was die Interpretation einer ribosomalen Beeinträchtigung sowie der Induktion von ER‐Stress unterstützte. Die Bildung von Polyribosomen und begleitende ER‐Schwellungen in behandelten Krebszellen wurden zudem durch TEM‐Messungen bestätigt. Somit scheint eine direkte Wechselwirkung von BOLD‐100 mit ribosomalen Proteinen die ER‐Stressinduktion und die Modulierung von GRP78 in Krebszellen zu begleiten.

Interaction with Ribosomal Proteins Accompanies Stress Induction of the Anticancer Metallodrug BOLD-100/KP1339 in the Endoplasmic Reticulum

The ruthenium-based anticancer agent BOLD-100/KP1339 has shown promising results in several in vitro and in vivo tumour models as well as in early clinical trials. However, its mode of action remains to be fully elucidated. Recent evidence identified stress induction in the endoplasmic reticulum (ER) and concomitant down-modulation of HSPA5 (GRP78) as key drug effects. By exploiting the naturally formed adduct between BOLD-100 and human serum albumin as an immobilization strategy, we were able to perform target-profiling experiments that revealed the ribosomal proteins RPL10, RPL24, and the transcription factor GTF2I as potential interactors of this ruthenium(III) anticancer agent. Integrating these findings with proteomic profiling and transcriptomic experiments supported ribosomal disturbance and concomitant induction of ER stress. The formation of polyribosomes and ER swelling of treated cancer cells revealed by TEM validated this finding. Thus, the direct interaction of BOLD-100 with ribosomal proteins seems to accompany ER stress-induction and modulation of GRP78 in cancer cells.

Rapid quantification of ruthenium(ii) polypyridyl anti-cancer drugs using a selective ligand dissociation LC-MS/MS method

Research on Ru anti-cancer drugs is on the rise with many complexes in clinical trials. Inductively coupled plasma-mass spectrometry (ICP-MS) has been the standard technique for bioanalytical studies on Ru and Pt complexes in biological media. Tedious ICP-MS methods rely on detecting and quantifying the element while lacking important structural information of the original complexes. Despite being equally sensitive, more accessible, and highly selective to the target species, liquid chromatography-tandem mass spectrometry (LC-MS/MS) has not been validated for the analysis of Ru drugs. Using USFDA guidelines, we report here the optimization and validation of a facile LC-MS/MS method for the detection and quantification of three Ru(ii) polypyridyl complexes in cells, plasma, and urine matrices. Importantly, a fast (10 min), single-step procedure was efficient for both extraction and sample purification, and analytes were rapidly eluted over a 3 min simple isocratic run. Specific parent ions were differentially fragmented by tandem MS, thus forming a unique and rational ligand dissociation chemistry that exhibits high selectivity to the target species with no measurable interferences or matrix effects. The developed LC-MS/MS method was advantageous vis-à-vis the prototypical ICP-MS based techniques both in vitro and in vivo, paving the way for its utilization in elaborate cellular uptake, pharmacokinetics, and pharmacodynamics studies.

Anticancer Ruthenium(III) Complexes and Ru(III)-Containing Nanoformulations: An Update on the Mechanism of Action and Biological Activity

The great advances in the studies on metal complexes for the treatment of different cancer forms, starting from the pioneering works on platinum derivatives, have fostered an increasingly growing interest in their properties and biomedical applications. Among the various metal-containing drugs investigated thus far, ruthenium(III) complexes have emerged for their selective cytotoxic activity in vitro and promising anticancer properties in vivo, also leading to a few candidates in advanced clinical trials. Aiming at addressing the solubility, stability and cellular uptake issues of low molecular weight Ru(III)-based compounds, some research groups have proposed the development of suitable drug delivery systems (e.g., taking advantage of nanoparticles, liposomes, etc.) able to enhance their activity compared to the naked drugs. This review highlights the unique role of Ru(III) complexes in the current panorama of anticancer agents, with particular emphasis on Ru-containing nanoformulations based on the incorporation of the Ru(III) complexes into suitable nanocarriers in order to enhance their bioavailability and pharmacokinetic properties. Preclinical evaluation of these nanoaggregates is discussed with a special focus on the investigation of their mechanism of action at a molecular level, highlighting their pharmacological potential in tumour disease models and value for biomedical applications.

Gel electrophoresis in combination with laser ablation-inductively coupled plasma mass spectrometry to quantify the interaction of cisplatin with human serum albumin

Cisplatin and its second and third generation analogues are widely used in the treatment of cancer. To study their reactions with proteins, we present a method based on SDS-PAGE separation and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) for platinum detection in the reaction between human serum albumin (HSA) and cisplatin. We developed matrix-matched standards of HSA/cisplatin mixtures and used them to quantify the amount of adducts formed at different HSA:cisplatin ratios. We noted that cisplatin incubation with HSA resulted in the formation of higher order HSA n-mers, depending on the amount of cisplatin added. This caused a depletion of the HSA dimer bands, while the majority of HSA was present as the monomer. Inducing the formation of such higher molecular weight species may have an impact on the mode of action of metallodrugs.

Serum-binding properties of isosteric ruthenium and osmium anticancer agents elucidated by SEC-ICP-MS

ABSTRACT

Size-exclusion chromatography-inductively coupled plasma-mass spectrometry (SEC-ICP-MS) was used to study the serum-binding preferences of two metallodrugs with anticancer activities in vivo, namely the organoruthenium compound plecstatin-1 and its isosteric osmium analog. The complexes were administered intraperitoneally into mice bearing a CT-26 tumor. Comparing the total metal content of mouse whole blood and serum underlined that the metallodrugs are mainly located in serum and not in the cellular fraction of the blood samples. In mouse serum, both compounds were not only found to bind extensively to the serum albumin/transferrin fraction but also to immunoglobulins. Free drug was not observed in any of the samples indicating rapid protein binding of the metallodrugs. These findings were validated by spiking human serum with the respective compounds ex vivo. An NCI-60 screen is reported for the osmium analog, which revealed a relative selectivity for cancer cell lines of the ovary and the central nervous system with respect to plecstatin-1. Finally, a COMPARE 170 analysis revealed disruption of DNA synthesis as a possible treatment effect of the osmium-based drug candidate.

GRAPHICAL ABSTRACT

Hyphenation of capillary electrophoresis to inductively coupled plasma mass spectrometry with a modified coaxial sheath-flow interface

Capillary electrophoretic analyses benefit significantly from hyphenation to mass spectrometric techniques. While the coupling to ESI-MS is routinely performed, for example by using a coaxial sheath-flow interface, hyphenating it to inductively coupled plasma mass spectrometry is more technically challenging. We use a commercially available coaxial sheath-flow interface (CSFI) and a simple PTFE-based end-cap for easy, inexpensive CE-ICP-MS hyphenation with improved sensitivity and analytical performance compared to commercially available interfaces. We have optimized key nebulizer parameters such as capillary position, sheath liquid flow rate, and carrier gas flow rate, and compared the CSFI with a commercially available interface. In a set of proof-of-principle experiments employing the anticancer agent cisplatin it was demonstrated that the signal to noise response and sensitivity were considerably improved leading to detection limits for ¹⁹⁵Pt of 0.08 μM.

The impact of whole human blood on the kinetic inertness of platinum(iv) prodrugs - an HPLC-ICP-MS study

The potential advantage of platinum(iv) complexes as alternatives to classical platinum(ii)-based drugs relies on their kinetic stability in the body before reaching the tumor site and on their activation by reduction inside cancer cells. In this study, an analytical workflow has been developed to investigate the reductive biotransformation and kinetic inertness of platinum(iv) prodrugs comprising different ligand coordination spheres (respectively, lipophilicity and redox behavior) in whole human blood. The distribution of platinum(iv) complexes in blood pellets and plasma was determined by inductively coupled plasma-mass spectrometry (ICP-MS) after microwave digestion. An analytical approach based on reversed-phase (RP)-ICP-MS was used to monitor the parent compound and the formation of metabolites using two different extraction procedures. The ligand coordination sphere of the platinum(iv) complexes had a significant impact on their accumulation in red blood cells and on their degree of kinetic inertness in whole human blood. The most lipophilic platinum(iv) compound featuring equatorial chlorido ligands showed a pronounced penetration into blood cells and a rapid reductive biotransformation. In contrast, the more hydrophilic platinum(iv) complexes with a carboplatin- and oxaliplatin-core exerted kinetic inertness on a pharmacologically relevant time scale with notable amounts of the compound accumulated in the plasma fraction.

Structure-activity relationships for ruthenium and osmium anticancer agents - towards clinical development

Anticancer metallodrugs based on ruthenium and osmium are among the most investigated and advanced non-platinum metallodrugs. Inorganic drug discovery with these agents has undergone considerable advances over the past two decades and has currently two representatives in active clinical trials. As many ruthenium and osmium metallodrugs are prodrugs, a key question to be addressed is how the molecular reactivity of such metal-based therapeutics dictates the selectivity and the type of interaction with molecular targets. Within this frame, this review introduces the field by the examples of the most advanced ruthenium lead structures. Then, global structure-activity relationships are discussed for ruthenium and osmium metallodrugs with respect to in vitro antiproliferative/cytotoxic activity and in vivo tumor-inhibiting properties, as well as pharmacokinetics. Determining and validating global mechanisms of action and molecular targets are still major current challenges. Moreover, significant efforts must be invested in screening in vivo tumor models that mimic human pathophysiology to increase the predictability for successful preclinical and clinical development of ruthenium and osmium metallodrugs.

Metallomic study on the metabolism of RAPTA-C and cisplatin in cell culture medium and its impact on cell accumulation

The different extracellular speciation of cisplatin and the organoruthenium developmental anticancer agent RAPTA-C impacts the accumulation in cancer cells.

Capillary Electrophoresis-Inductively Coupled Plasma Mass Spectrometry

During the recent years, capillary electrophoresis (CE) has been fully established as a powerful tool in separation sciences as well as in element speciation. This road of success is based on the rapid analysis time, low sample requirements, high separation efficiency, and low operating costs of CE. Inductively coupled plasma mass spectrometry (ICP-MS) is known for superior detection and multielement capability. Consequently, the combination of both instruments is approved for analysis of complex sample types at low element concentrations which require high detection power. Also the diversity of potential applications brings CE-ICP-MS coupling into central focus of element speciation. The key to successful combination of ICP-MS as an (multi-)element selective detector for CE is the availability of a suitable and effective interface.Therefore, this chapter summarizes the most important and basic principles about coupling of capillary electrophoresis to ICP-MS. Specifically, the major requirements for interfacing are described and technical solutions are given. Such solutions include the closing of the electrical circuit from CE at the nebulization, the adoption of flow rates for efficient nebulization, the reduction of a suction flow through the capillary, caused by the nebulizer, and maintaining the high separation resolution from CE across the interface for ICP-MS detection. Additionally, detailed information is presented to determine and quantify the siphoning suction through the CE capillary by the nebulizer. Finally, two applications, namely, the manganese and selenium speciation in cerebrospinal fluid are shown as examples, providing the relevant operational parameter.

Novel Transgenic Mouse Model for Studying Human Serum Albumin as a Biomarker of Carcinogenic Exposure

Albumin is a commonly used serum protein for studying human exposure to xenobiotic compounds, including therapeutics and environmental pollutants. Often, the reactivity of albumin with xenobiotic compounds is studied ex vivo with human albumin or plasma/serum samples. Some studies have characterized the reactivity of albumin with chemicals in rodent models; however, differences between the orthologous peptide sequences of human and rodent albumins can result in the formation of different types of chemical-protein adducts with different interaction sites or peptide sequences. Our goal is to generate a human albumin transgenic mouse model that can be used to establish human protein biomarkers of exposure to hazardous xenobiotics for human risk assessment via animal studies. We have developed a human albumin transgenic mouse model and characterized the genotype and phenotype of the transgenic mice. The presence of the human albumin gene in the genome of the model mouse was confirmed by genomic PCR analysis, whereas liver-specific expression of the transgenic human albumin mRNA was validated by RT-PCR analysis. Further immunoblot and mass spectrometry analyses indicated that the transgenic human albumin protein is a full-length, mature protein, which is less abundant than the endogenous mouse albumin that coexists in the serum of the transgenic mouse. The transgenic protein was able to form ex vivo adducts with a genotoxic metabolite of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine, a procarcinogenic heterocyclic aromatic amine formed in cooked meat. This novel human albumin transgenic mouse model will facilitate the development and validation of albumin-carcinogen adducts as biomarkers of xenobiotic exposure and/or toxicity in humans.

Biodistribution of the novel anticancer drug sodium trans-[tetrachloridobis(1H-indazole)ruthenate(III)] KP-1339/IT139 in nude BALB/c mice and implications on its mode of action

The ruthenium complex sodium trans-[tetrachloridobis(1H-indazole)ruthenate(III)] (KP-1339/IT139) has entered clinical trials as the more soluble alternative to the indazolium compound KP1019. In order to get insight into its distribution and accumulation throughout a living organism, KP-1339/IT139 was administered intravenously in non-tumor bearing nude BALB/c mice and the Ru content in blood cells and plasma, bone, brain, colon, kidneys, liver, lung, muscle, spleen, stomach and thymus was determined at several time points. The Ru concentration in blood cells and plasma was found to increase slightly within the first hours of analysis, with the Ru concentration being 3-times higher in plasma compared to blood cells. The plasma samples were subjected to analysis by capillary zone electrophoresis (CZE) and size exclusion/anion exchange chromatography (SEC-IC) both coupled to inductively coupled plasma-mass spectrometry (ICP-MS) and a large majority of the total Ru content was found attached to mouse serum albumin (MSA), confirming similar behavior to KP1019 in an in vivo setting. Within 1h, the peak ratio of approximately 1.2-1.5 Ru per albumin molecule was reached which declined to about 1 Ru per albumin molecule within 24h. Beside the MSA adduct a higher molecular weight species was observed probably stemming from MSA conjugates. In addition, the tissue samples were mineralized by microwave digestion and analyzed for their Ru content. The highest Ru levels were found in colon, lung, liver, kidney and notably in the thymus. The peak Ru concentrations in these tissues were reached 1-6h after administration and declined slowly over time.

Metal-based drugs that break the rules

Cisplatin and other platinum compounds have had a huge impact in the treatment of cancers and are applied in the majority of anticancer chemotherapeutic regimens. The success of these compounds has biased the approaches used to discover new metal-based anticancer drugs. In this perspective we highlight compounds that are apparently incompatible with the more classical (platinum-derived) concepts employed in the development of metal-based anticancer drugs, with respect to both compound design and the approaches used to validate their utility. Possible design approaches for the future are also suggested.

Quantum Chemical Studies on Detail Mechanism of Nitrosylation of NAMI-A-HSA Adduct

Hydrolysis of NAMI-A in NAMI-A-HSA (HSA = human serum albumin) and nitrosylation of hydrolyzed NAMI-A-HSA adduct have been studied in detail using density functional theory method. It has been observed that the chloride exchange reaction with water in the NAMI-A-HSA adduct follows an interchange dissociative mechanism passing through an unstable heptacoordinated activated complex. The computed free energy of activation (ΔG) and rate constant (k) for the hydrolysis process in aqueous medium are observed to be 24.85 kcal mol(-1) and 3.81 × 10(-6) s(-1), respectively. Nitrosylation of hydrolyzed NAMI-A-HSA adduct with nitric oxide is found to be thermodynamically more favorable with the incorporation of solvent effect and provides a detailed understanding related to the antimetastatic activity of the NAMI-A drug. This investigation shows that nitric oxide coordinates linearly to NAMI-A-HSA adduct leading to the reduction of ruthenium(III) to more active ruthenium(II), with the reduction potential of -2.32 V. Negative relative solvation and relative binding free energies suggest that the hydrolysis and nitrosylation reactions are found to be thermodynamically favorable and faster. Our computed results provide a detailed thermodynamics and kinetics which may be highly beneficial for understanding antimetastatic activity as well as the nitric oxide scavenging ability of NAMI-A.

Three-dimensional and co-culture models for preclinical evaluation of metal-based anticancer drugs

BACKGROUND

Hypoxic and necrotic regions that accrue within solid tumors in vivo are known to be associated with metastasis formation, radio- and chemotherapy resistance, and drug metabolism. Therefore, integration of these tumor characteristics into in vitro drug screening models is advantageous for any reliable investigation of the anticancer activity of novel drug candidates. In general, usage of cell culture models with in vivo like characteristics has become essential in preclinical drug studies and allows evaluation of complex problems such as tumor selectivity and anti-invasive properties of the drug candidates.

MATERIALS AND METHODS

In this study, we investigated the anticancer activity of clinically approved, investigational and experimental drugs based on platinum (cisplatin, oxaliplatin and KP1537), gallium (KP46), ruthenium (KP1339) and lanthanum (KP772) in different cell culture models such as monolayers, multicellular spheroids, as well as invasion and metastasis models. Results Application of the Alamar Blue assay to multicellular spheroids and a spheroid-based invasion assay resulted in an altered rating of compounds with regard to their cytotoxicity and ability to inhibit invasion when compared with monolayer-based cytotoxicity and transwell assays. For example, the gallium-based drug candidate KP46 showed in spheroid cultures significantly enhanced properties to inhibit protrusion formation and fibroblast mediated invasiveness, and improved cancer cell selectivity.

CONCLUSION

Taken together, our results demonstrate the advantages of spheroid-based assays and underline the necessity of using different experimental models for reliable preclinical investigations assessing and better predicting the anticancer potential of new compounds.

Surface-enhanced Raman spectroscopy of the anti-cancer drug irinotecan in presence of human serum albumin

The development of nanotechnological devices and their clinical application in medicine has become increasingly important, especially in the context of targeted and personalized therapy. This is particularly important in cancer therapy, where antitumor drugs are highly cytotoxic and often exert their therapeutic effect at concentrations close to systemic toxicity. In the last years a growing number of studies has started to report the use of plasmonic nanoprobes in the field of theranostics, broadening the application of vibrational spectroscopies like Raman scattering and surface enhanced Raman scattering (SERS) in biomedicine. The present work aims to identify and characterize the vibrational profiles of a widely used anticancer drug, irinotecan (CPT-11). With a rational approach, SERS experiments have been performed on this analyte employing both Au and Ag colloids, starting from simple aqueous solutions up to albumin mixtures. A major step forward for drug detection in albumin solutions has been taken with the adoption of a simple deproteinization strategy, and a two-in-one-step separation and identification by coupling thin layer chromatography, TLC, with SERS (TLC-SERS). The latter has revealed to be a valid system for protein separation and simultaneous analyte detection, showing a potential to become an innovative, sensitive and low cost method for antineoplastic drug profiling in patients' body fluids.

Application of mass spectrometric techniques to delineate the modes-of-action of anticancer metallodrugs

Mass spectrometry (MS) has emerged as an important tool for studying anticancer metallodrugs in complex biological samples and for characterising their interactions with biomolecules and potential targets on a molecular level. The exact modes-of-action of these coordination compounds and especially of next generation drug candidates have not been fully elucidated. Due to the fact that DNA is considered a crucial target for platinum chemotherapeutics, metallodrug-DNA binding studies dominated the field for a long time. However, more recently, alternative targets were considered, including enzymes and proteins that may play a role in the overall pharmacological and toxicological profile of metallodrugs. This review focuses on MS-based techniques for studying anticancer metallodrugs in vivo, in vitro and in situ to delineate their modes-of-action.

Interaction of the NAMI-A complex with nitric oxide under physiological conditions

The NAMI-A ([ImH][RuCl₄(Im)(DMSO)], Im – imidazole, DMSO – dimethyl sulfoxide) interact with nitric oxide (NO) under physiological-like conditions, however it is rather kinetically sluggish NO scavenger.

Inductively coupled plasma-MS in drug development: bioanalytical aspects and applications

The vast majority of today's modern bioanalytical methods for pharmacokinetic, pharmacodynamic and immunogenicity purposes are based on LC-MS/MS and immunoanalytical approaches. Indeed, these methodologies are suitable for a wide range of molecules from small to large. For a smaller but not insignificant group of compounds, LC-MS/MS is not suitable - or in some cases much less suitable - as a reliable bioanalytical methodology, and inductively coupled plasma (ICP)-MS is a more appropriate methodology. ICP-MS is one of these less widely used techniques in drug development. This methodology is predominantly used for elemental bioanalysis for pharmacokinetics, for imaging purposes, for mass-balance, food-effect and biomarker studies. In addition, in the last couple of years an increasing number of applications has been published, where ICP-MS and its various hyphenations (LC-ICP-MS, CE-ICP-MS) have been used for speciation/metabolism and proteomics studies. Here, the analytical potential, the quantitative bioanalytical aspects, the various modes of operation and the challenges of the application of ICP-MS in life sciences applications are given. This includes an overview of recent applications in this area in scientific literature, the various hyphenation possibilities and their application areas and the analysis of the various sample matrices applicable to these fields. It also provides a brief outlook of where the potential of this technique lies in the future of regulated bioanalysis and drug development.

Anticancer metallodrug research analytically painting the "omics" picture--current developments and future trends

Anticancer metallodrug development has for a long time been characterised by the similarity of new drug candidates to cisplatin and DNA as the primary target. Recent advances in bioanalytical techniques with high sensitivity and selectivity have revealed that metal-based drugs can undergo a wide range of biomolecular interactions beyond DNA and have generated interest in proteins as possible targets for metallodrugs. In fact, implementation of metallomics approaches that are able to reveal the fate of the compounds in biological systems can help to move drug development towards more targeted and rational design of novel metallodrugs. Additionally, proteomic screening and gene expression analysis can provide insight into physiological response to drug treatment and identify the reasons for drug resistance. Herein, we review selected applications which led to a better understanding of the mode of action of clinically established metal-based anticancer agents and novel metallodrug candidates.