Cellular transport mechanisms of cytotoxic metallodrugs: an overview beyond cisplatin

Copper-Based Complexes with Adamantane Ring-Conjugated bis(3,5-Dimethyl-pyrazol-1-yl)acetate Ligand as Promising Agents for the Treatment of Glioblastoma

The new ligand L2Ad, obtained by conjugating the bifunctional species bis(3,5-dimethylpyrazol-1-yl)-acetate and the drug amantadine, was used as a chelator for the synthesis of new Cu complexes 1-5. Their structures were investigated by synchrotron radiation-induced X-ray photoelectron spectroscopy (SR-XPS), near-edge X-ray absorption fine structure (NEXAFS) spectroscopy, and by combining X-ray absorption fine structure (XAFS) spectroscopy techniques and DFT modeling. The structure of complex 3 was determined by single-crystal X-ray diffraction analysis. Tested on U87, T98, and U251 glioma cells, Cu(II) complex 3 and Cu(I) complex 5 decreased cell viability with IC50 values significantly lower than cisplatin, affecting cell growth, proliferation, and death. Their effects were prevented by treatment with the Cu chelator tetrathiomolybdate, suggesting the involvement of copper in their cytotoxic activity. Both complexes were able to increase ROS production, leading to DNA damage and death. Interestingly, nontoxic doses of 3 or 5 enhanced the chemosensitivity to Temozolomide.

Static magnetic field reduces cisplatin resistance via increasing apoptosis pathways and genotoxicity in cancer cell lines

Cisplatin is a chemotherapy drug widely used in cancer treatment. Alongside its clinical benefits, however, it may inflict intolerable toxicity and other adverse effects on healthy tissues. Due to the limitation of administering a high dose of cisplatin as well as cancer drug resistance, it is necessary to utilize new methods optimizing treatment modalities through both higher therapeutic efficacy and reduced administered doses of radiation and drugs. In this study, sensitive (A2780) and resistant (A2780CP) ovarian carcinoma cells underwent treatment with cisplatin + static magnetic field (SMF). First, the levels of genotoxicity after treatment were evaluated by Comet assay. Then, cell cycle analysis and apoptosis assay were conducted by a flow cytometer. Lastly, the expression levels of genes involved in apoptosis and cellular drug uptake were investigated by PCR. After treating different groups of cells for 24, 48, and 96 h, the co-treatment of SMF and cisplatin as a combination managed to increase the amount of DNA damage in both sensitive and resistant cell lines. A considerable increase in mortality of cells was also observed mostly in the form of apoptosis, which was caused by inhibition of the cell cycle. The combination also increased the expression levels of apoptotic genes, namely P53 and P21; however, it did not have much effect on the expression levels of BCL2. Besides, the levels of CTR1 gene expression increased significantly in the groups receiving the aforementioned combination. Our study suggests that the combination of cisplatin + SMF might have clinical potential which needs further investigations through future studies.

Vanadocene-functionalized mesoporous silica nanoparticles: platforms for the development of theranostic materials against breast cancer

Nanoscale materials have demonstrated a very high potential in anticancer therapy by properly adjusting their functionalization and physicochemical properties. Herein, we report the synthesis of some novel vanadocene-loaded silica-based nanomaterials incorporating four different S-containing amino acids (penicillamine, methionine, captopril, and cysteine) and different fluorophores (rhodamine B, coumarin 343 or Alexa Fluor™ 647), which have been characterized by diverse solid-state spectroscopic techniques viz; FTIR, diffuse reflectance spectroscopies,13C and51V solid-state NMR spectroscopy, thermogravimetry and TEM. The analysis of the biological activity of the novel vanadocene-based nanostructured silicas showed that the materials containing cysteine and captopril aminoacids demonstrated high cytotoxicity and selectivity against triple negative breast cancer cells, making them very promising antineoplastic drug candidates. According to the biological results it seems that vanadium activity is connected to its incorporation through the amino acid, resulting in synergy that increases the cytotoxic activity against cancer cells of the studied materials presumably by increasing cell internalization. The results presented herein hold significant potential for future developments in mesoporous silica-supported metallodrugs, which exhibit strong cytotoxicity while maintaining low metal loading. They also show potential for theranostic applications highlighted by the analysis of the optical properties of the studied systems after incorporating rhodamine B, coumarin 343 (possible)in vitroanticancer analysis, or Alexa Fluor™ 647 (in vivostudies of cancer models).

The equivalence of different types of electric pulses for electrochemotherapy with cisplatin - an in vitro study

BACKGROUND

Electrochemotherapy (ECT) is a treatment involving the administration of chemotherapeutics drugs followed by the application of 8 square monopolar pulses of 100 μs duration at a repetition frequency of 1 Hz or 5000 Hz. However, there is increasing interest in using alternative types of pulses for ECT. The use of high-frequency short bipolar pulses has been shown to mitigate pain and muscle contractions. Conversely, the use of millisecond pulses is interesting when combining ECT with gene electrotransfer for the uptake of DNA-encoding proteins that stimulate the immune response with the aim of converting ECT from a local to systemic treatment. Therefore, the aim of this study was to investigate how alternative types of pulses affect the efficiency of the ECT.

MATERIALS AND METHODS

We performed in vitro experiments, exposing Chinese hamster ovary (CHO) cells to conventional ECT pulses, high-frequency bipolar pulses, and millisecond pulses in the presence of different concentrations of cisplatin. We determined cisplatin uptake by inductively coupled plasma mass spectrometry and cisplatin cytotoxicity by the clonogenic assay.

RESULTS

We observed that the three tested types of pulses potentiate the uptake and cytotoxicity of cisplatin in an equivalent manner, provided that the electric field is properly adjusted for each pulse type. Furthermore, we quantified that the number of cisplatin molecules, resulting in the eradication of most cells, was 2-7 × 107 per cell.

CONCLUSIONS

High-frequency bipolar pulses and millisecond pulses can potentially be used in ECT to reduce pain and muscle contraction and increase the effect of the immune response in combination with gene electrotransfer, respectively.

On the mechanism of action of arsenoplatins: arsenoplatin-1 binding to a B-DNA dodecamer

The reaction of Pt-based anticancer agents with arsenic trioxide affords robust complexes known as arsenoplatins. The prototype of this family of anticancer compounds is arsenoplatin-1 (AP-1) that contains an As(OH)2 fragment linked to a Pt(II) moiety derived from cisplatin. Crystallographic and spectrometric studies of AP-1 binding to a B-DNA double helix dodecamer are presented here, in comparison with cisplatin and transplatin. Results reveal that AP-1, cisplatin and transplatin react differently with the DNA model system. Notably, in the AP-1/DNA systems, the Pt-As bond can break down with time and As-containing fragments can be released. These results have implications for the understanding of the mechanism of action of arsenoplatins.

Role of Epigenetics for the Efficacy of Cisplatin

The clinical utility of the chemotherapeutic agent cisplatin is restricted by cancer drug resistance, which is either intrinsic to the tumor or acquired during therapy. Epigenetics is increasingly recognized as a factor contributing to cisplatin resistance and hence influences drug efficacy and clinical outcomes. In particular, epigenetics regulates gene expression without changing the DNA sequence. Common types of epigenetic modifications linked to chemoresistance are DNA methylation, histone modification, and non-coding RNAs. This review provides an overview of the current findings of various epigenetic modifications related to cisplatin efficacy in cell lines in vitro and in clinical tumor samples. Furthermore, it discusses whether epigenetic alterations might be used as predictors of the platinum agent response in order to prevent avoidable side effects in patients with resistant malignancies. In addition, epigenetic targeting therapies are described as a possible strategy to render cancer cells more susceptible to platinum drugs.

Development of Integrated Bioorthogonal Self-Catalyzed NO Donor/Platinum(IV) Prodrugs for Synergistical Intervention against Triple-Negative Breast Cancer

The platinum(IV) prodrug strategy is attractive for the synergistic antitumor effect. High levels (>400 nM) of nitric oxide (NO) exert promising cancer inhibition effects via multiple mechanisms. Herein, we designed and synthesized a new group of integrated bioorthogonal self-catalyzed NO donor/Pt(IV) prodrugs bearing long alkyl chains to enhance the stability in circulation, while the cytoplasmic reductants trigger cascade activation to release Pt and NO in tumor cells. Specifically, compound 10c exhibited an improved stability, favorable pharmacokinetic properties (AUC(0-t) of 2210.10 h*ng/mL), potent anti-triple-negative breast cancer (TNBC) effects (71.08% tumor growth inhibition (TGI) against the MDA-MB-231 xenograft model), potent in vivo anti-TNBC lung metastasis activity, and acceptable low toxicity. Importantly, NO released from 10c leads to the S-nitrosation of metal transporters Atox1&ATP7a in TNBC cells, which increases the Pt retention and inhibits lysyl oxidase, generating synergistic tumoricidal and antimetastatic activity. These results may inspire further study on the synergistical therapy of Pt and NO for the treatment of TNBC.

In vitro and in vivo accumulation of the anticancer Ru complexes [RuII(cym)(HQ)Cl] and [RuII(cym)(PCA)Cl]Cl

The cellular accumulation and the underlying mechanisms for the two ruthenium-based anticancer complexes [RuII(cym)(HQ)Cl] 1 (cym = η6-p-cymene, HQ = 8-hydroxyquinoline) and [RuII(cym)(PCA)Cl]Cl 2 (PCA = N-fluorophenyl-2-pyridinecarbothioamide) were investigated in HCT116 human colorectal carcinoma cells. The results showed that the cellular accumulation of both complexes increased over time and with higher concentrations, and that 2 accumulates in greater quantities in cells than 1. Inhibition studies of selected cellular accumulation mechanisms indicated that both 1 and 2 may be transported into the cells by both passive diffusion and active transporters, similar to cisplatin. Efflux experiments indicated that 1 and 2 are subjected to efflux through a mechanism that does not involve p-glycoprotein, as addition of verapamil did not make any difference. Exploring the influence of the Cu transporter by addition of CuCl2 resulted in a higher accumulation of 1 and 2 whilst the amount of Pt detected was slightly reduced when cells were treated with cisplatin. Complexes 1 and 2 were further explored in zebrafish where accumulation and distribution were determined with ICP-MS and LA-ICP-MS. The results correlated with the in vitro observations and zebrafish treated with 2 showed higher Ru contents than those treated with 1. The distribution studies suggested that both complexes mainly accumulated in the intestines of the zebrafish.

Anticancer Potential of Dendritic Poly(aryl ether)-Substituted Polypyridyl Ligand-Based Ruthenium(II) Coordination Entities

This paper studies the anticancer potency of dendritic poly(aryl ether)-substituted polypyridyl ligand-based ruthenium(II) coordination entities. The dendritic coordination entities were successfully designed, synthesized, and characterized by different spectral methods such as Fourier transform infrared (FTIR), 1H and 13C- NMR, and mass spectrometry. Further, to understand the structure and solvation behavior of the coordination entities, we performed all-atom molecular dynamics (MD) simulations. The behavior, configuration, and size of the coordination entities in DMSO and water were studied by calculating the radius of gyration (Rg) and solvent-accessible surface area (SASA). The MTT assay was used to assess the in vitro cytotoxicity of all of the coordination entities against cancerous A549 (lung cancer cells), MDA MB 231 (breast cancer cells), and HepG2 (liver cancer cells) and was found to be good with comparable IC50 values with respect to the standard drug cisplatin. The coordination entities exhibited dose dependence, and the highest activity was shown against HepG2 cell lines in comparison to the other cancer cell lines. In addition, fluorescence staining studies, such as AO/EB, DAPI, and cell death analysis by PI staining, were performed on the coordination entities to understand the apoptosis mechanism. Furthermore, reactive oxygen species (ROS) and mitochondrial membrane potential (MMP) assays confirmed apoptosis in cancer cells via the mitochondrial pathway. The DNA fragmentation assay was done followed by molecular docking analysis with DNA executed to strengthen and support the experimental observations.

Emerging platinum(IV) prodrug nanotherapeutics: A new epoch for platinum-based cancer therapy

Owing to the unique DNA damaging cytotoxicity, platinum (Pt)-based chemotherapy has long been the first-line choice for clinical oncology. Unfortunately, Pt drugs are restricted by the severe dose-dependent toxicity and drug resistance. Correspondingly, Pt(IV) prodrugs are developed with the aim to improve the antitumor performance of Pt drugs. However, as "free" molecules, Pt(IV) prodrugs are still subject to unsatisfactory in vivo destiny and antitumor efficacy. Recently, Pt(IV) prodrug nanotherapeutics, inheriting both the merits of Pt(IV) prodrugs and nanotherapeutics, have emerged and demonstrated the promise to address the underexploited dilemma of Pt-based cancer therapy. Herein, we summarize the latest fronts of emerging Pt(IV) prodrug nanotherapeutics. First, the basic outlines of Pt(IV) prodrug nanotherapeutics are overviewed. Afterwards, how versatile Pt(IV) prodrug nanotherapeutics overcome the multiple biological barriers of antitumor drug delivery is introduced in detail. Moreover, advanced combination therapies based on multimodal Pt(IV) prodrug nanotherapeutics are discussed with special emphasis on the synergistic mechanisms. Finally, prospects and challenges of Pt(IV) prodrug nanotherapeutics for future clinical translation are spotlighted.

Exploring the Potent Anticancer Activity of Essential Oils and Their Bioactive Compounds: Mechanisms and Prospects for Future Cancer Therapy

Cancer is one of the leading causes of death worldwide, affecting millions of people each year. Fortunately, the last decades have been marked by considerable advances in the field of cancer therapy. Researchers have discovered many natural substances, some of which are isolated from plants that have promising anti-tumor activity. Among these, essential oils (EOs) and their constituents have been widely studied and shown potent anticancer activities, both in vitro and in vivo. However, despite the promising results, the precise mechanisms of action of EOs and their bioactive compounds are still poorly understood. Further research is needed to better understand these mechanisms, as well as their effectiveness and safety in use. Furthermore, the use of EOs as anticancer drugs is complex, as it requires absolute pharmacodynamic specificity and selectivity, as well as an appropriate formulation for effective administration. In this study, we present a synthesis of recent work on the mechanisms of anticancer action of EOs and their bioactive compounds, examining the results of various in vitro and in vivo studies. We also review future research prospects in this exciting field, as well as potential implications for the development of new cancer drugs.

Dichloro Ru(II)-p-cymene-1,3,5-triaza-7-phosphaadamantane (RAPTA-C): A Case Study

The use of organometallic compounds to treat various phenotypes of cancer has attracted increased interest in recent decades. Organometallic compounds, which are transitional between conventional inorganic and organic materials, have outstanding and one-of-a-kind features that offer fresh insight into the development of inorganic medicinal chemistry. The therapeutic potential of ruthenium(II)-arene RAPTA-type compounds is being thoroughly investigated, specifically owing to the excellent antimetastatic property of the initial candidate RAPTA-C. This review gives a thorough analysis of this complex and its evolution as a potential anticancer drug candidate. The numerous mechanistic investigations of RAPTA-C are discussed, and they are connected to the macroscopic biological characteristics that have been found. The "multitargeted" complex described here target enzymes, peptides, and intracellular proteins in addition to DNA that allow it to specifically target cancer cells. Understanding these may allow researchers to find specific targets and tune a new-generation organometallic complex accordingly.

Series of Organotin(IV) Compounds with Different Dithiocarbamate Ligands Induced Cytotoxicity, Apoptosis and Cell Cycle Arrest on Jurkat E6.1, T Acute Lymphoblastic Leukemia Cells

The discovery of cisplatin has influenced scientists to study the anticancer properties of other metal complexes. Organotin(IV) dithiocarbamate compounds are gaining attention as anticancer agents due to their potent cytotoxic properties on cancer cells. In this study, a series of organotin compounds were assessed for their toxic effects on the Jurkat E6.1 cell line. WST-1 assay was used to determine the cytotoxic effect of the compounds and showed that six out of seven organotin(IV) dithiocarbamate compounds exhibited potent cytotoxic effects toward T-lymphoblastic leukemia cells, Jurkat E6.1 with the concentration of IC₅₀ ranging from 0.67-0.94 µM. The apoptosis assay by Annexin V-FITC/PI staining showed that all tested compounds induced cell death mainly via apoptosis. Cell cycle analysis assessed using RNase/PI staining showed that organotin(IV) dithiocarbamate compounds induced cell cycle arrest at different phases. In conclusion, the tested organotin(IV) dithiocarbamate compounds demonstrated potent cytotoxicity against Jurkat E6.1 cells via apoptosis and cell cycle arrest at low IC₅₀ value. However, further studies on the mechanisms of action are required to probe the possible potential of these compounds on leukemia cells before they can be developed into anti-leukemic agents.

Carbosilane ruthenium metallodendrimer as alternative anti-cancer drug carrier in triple negative breast cancer mouse model: A preliminary study

The carbosilane metallodendrimer G₁-[[NCPh(o-N)Ru(η6- p-cymene)Cl]Cl]₄ (CRD13), based on an arene Ru(II) complex coordinated to imino-pyridine surface groups, has been conjugated with anti-cancer drugs. Ruthenium in the positively-charged dendrimer structure allows this nanoparticle to be considered as an anticancer drug carrier, made more efficient because ruthenium has anticancer properties. The ability of CRD13 to form complexes with Doxorubicin (DOX), 5-Fluorouracil (5-Fu), and Methotrexate (MTX) has been evaluated using zeta potential measurement, transmission electron microscopy (TEM) and computer simulation. The results show that it forms stable nanocomplexes with all those drugs, enhancing their effectiveness against MDA-MB-231 cancer cells. In vivo tests indicate that the CRD13/DOX system caused a decrease of tumor weight in mice with triple negative breast cancer. However, the tumors were most visibly reduced when naked dendrimers were injected.

In Vitro Evaluation of the Cytotoxic Potential of Thiosemicarbazide Coordinating Compounds in Hepatocyte Cell Culture

Cancer is a global medical problem and, despite research efforts in the field of tumor treatment, there is currently a shortage of specific anticancer drugs. Most anticancer drugs show significant side effects. The liver is the organ that has central functions in drug metabolism, being a major target of the harmful action of anticancer compounds. In this context, it is essential to evaluate the cytotoxic effects of potential anticancer substances. Therefore, hepatotoxicity and hepatocyte viability were determined in vitro to evaluate the action of seven new local thiosemicarbazide coordination compounds (CCT) on normal liver cells. Doxorubicin was used as a reference substance. The control group consisted of hepatocytes not exposed to CCT action. The cell viability of hepatocytes treated with CCT decreased significantly by 5-12% compared to the control, but was statistically significantly higher by 5-14% compared to doxorubicin, except after CMD-8 and CMT-67 influence, when it does not change. Thus, new local CCT had a selective effect on hepatocytes in vitro and were less hepatotoxic compared to doxorubicin, which may be the basis for further study of its potential in anticancer drugs.

Cisplatin-induced ototoxicity: From signaling network to therapeutic targets

Administration of cisplatin, a common chemotherapeutic drug, has an inevitable side effect of sensorineural hearing loss. The main etiologies are stria vascularis injury, spiral ganglion degeneration, and hair cell death. Over several decades, the research scope of cisplatin-induced ototoxicity has expanded with the discovery of the molecular mechanism mediating inner ear cell death, highlighting the roles of reactive oxygen species and transport channels for cisplatin uptake into inner ear cells. Upon entering hair cells, cisplatin disrupts organelle metabolism, induces oxidative stress, and targets DNA to cause intracellular damage. Recent studies have also reported the role of inflammation in cisplatin-induced ototoxicity. In this article, we preform a narrative review of the latest reported molecular mechanisms of cisplatin-induced ototoxicity, from extracellular to intracellular. We build up a signaling network starting with cisplatin entering into the inner ear through the blood labyrinth barrier, disrupting cochlear endolymph homeostasis, and activating inflammatory responses of the outer hair cells. After entering the hair cells, cisplatin causes hair cell death via DNA damage, redox system imbalance, and mitochondrial and endoplasmic reticulum dysfunction, culminating in programmed cell death including apoptosis, necroptosis, autophagic death, pyroptosis, and ferroptosis. Based on the mentioned mechanisms, prominent therapeutic targets, such as channel-blocking drugs of cisplatin transporter, construction of cisplatin structural analogues, anti-inflammatory drugs, antioxidants, cell death inhibitors, and others, were collated. Considering the recent research efforts, we have analyzed the feasibility of the aforementioned therapeutic strategies and proposed our otoprotective approaches to overcome cisplatin-induced ototoxicity.

Highly Charged Ru(II) Polypyridyl Complexes as Photosensitizer Agents in Photodynamic Therapy of Epithelial Ovarian Cancer Cells

Ovarian cancer recurrence is frequent and associated with chemoresistance, leading to extremely poor prognosis. Herein, we explored the potential anti-cancer effect of a series of highly charged Ru(II)-polypyridyl complexes as photosensitizers in photodynamic therapy (PDT), which were able to efficiently sensitize the formation of singlet oxygen upon irradiation (Ru12+ and Ru22+) and to produce reactive oxygen species (ROS) in their corresponding dinuclear metal complexes with the Fenton active Cu(II) ion/s ([CuRu1]4+ and [Cu2Ru2]6+). Their cytotoxic and anti-tumor effects were evaluated on human ovarian cancer A2780 cells both in the absence or presence of photoirradiation, respectively. All the compounds tested were well tolerated under dark conditions, whereas they switched to exert anti-tumor activity following photoirradiation. The specific effect was mediated by the onset of programed cell death, but only in the case of Ru12+ and Ru22+ was preceded by the loss of mitochondrial membrane potential soon after photoactivation and ROS production, thus supporting the occurrence of apoptosis via type II photochemical reactions. Thus, Ru(II)-polypyridyl-based photosensitizers represent challenging tools to be further investigated in the identification of new therapeutic approaches to overcome the innate chemoresistance to platinum derivatives of some ovarian epithelial cancers and to find innovative drugs for recurrent ovarian cancer.

Exploring the Antitumor Potential of Copper Complexes Based on Ester Derivatives of Bis(pyrazol-1-yl)acetate Ligands

Bis(pyrazol-1-yl)acetic acid (HC(pz)₂COOH) and bis(3,5-dimethyl-pyrazol-1-yl)acetic acid (HC(pz^Me2)₂COOH) were converted into the methyl ester derivatives 1 (L^OMe) and 2 (L^2OMe), respectively, and were used for the preparation of Cu(I) and Cu(II) complexes 3–10. The copper(II) complexes were prepared by the reaction of CuCl₂·2H₂O or CuBr₂ with ligands 1 and 2 in methanol solution. The copper(I) complexes were prepared by the reaction of Cu[(CH₃CN)₄]PF₆ and 1,3,5-triaza-7-phosphaadamantane (PTA) or triphenylphosphine with L^OMe and L^2OMe in acetonitrile solution. Synchrotron radiation-based complementary techniques (XPS, NEXAFS, and XAS) were used to investigate the electronic and molecular structures of the complexes and the local structure around copper ions in selected Cu(I) and Cu(II) coordination compounds. All Cu(I) and Cu(II) complexes showed a significant in vitro antitumor activity, proving to be more effective than the reference drug cisplatin in a panel of human cancer cell lines, and were able to overcome cisplatin resistance. Noticeably, Cu complexes appeared much more effective than cisplatin in 3D spheroid cultures. Mechanistic studies revealed that the antitumor potential did not correlate with cellular accumulation but was consistent with intracellular targeting of PDI, ER stress, and paraptotic cell death induction.

Renoprotective Effect of Pediococcus acidilactici GKA4 on Cisplatin-Induced Acute Kidney Injury by Mitigating Inflammation and Oxidative Stress and Regulating the MAPK, AMPK/SIRT1/NF-κB, and PI3K/AKT Pathways

Acute kidney injury (AKI) describes a sudden loss of kidney function and is associated with a high mortality. Pediococcus acidilactici is a potent producer of bacteriocin and inhibits the growth of pathogens during fermentation and food storage; it has been used in the food industry for many years. In this study, the potential of P. acidilactici GKA4 (GKA4) to ameliorate AKI was investigated using a cisplatin-induced animal model. First, mice were given oral GKA4 for ten days and intraperitoneally injected with cisplatin on the seventh day to create an AKI mode. GKA4 attenuated renal histopathological alterations, serum biomarkers, the levels of inflammatory mediators, and lipid oxidation in cisplatin-induced nephrotoxicity. Moreover, GKA4 significantly decreased the expression of inflammation-related proteins and mitogen-activated protein kinase (MAPK) in kidney tissues. Eventually, GKA4 also increased the levels of related antioxidant enzymes and pathways. Consistently, sirtuin 1 (SIRT1) upregulated the level of autophagy-related proteins (LC3B, p62, and Beclin1). Further studies are needed to check our results and advance our knowledge of the mechanism whereby PI3K inhibition (wortmannin) reverses the effect of GKA4 on cisplatin-treated AKI. Taken together, GKA4 provides a therapeutic target with promising clinical potential after cisplatin treatment by reducing oxidative stress and inflammation via the MAPK, AMP-activated protein kinase (AMPK)/SIRT1/nuclear factor kappa B (NF-κB), and phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) axes.

Multidrug Resistance in Cancer: Understanding Molecular Mechanisms, Immunoprevention and Therapeutic Approaches

Cancer is one of the leading causes of death worldwide. Several treatments are available for cancer treatment, but many treatment methods are ineffective against multidrug-resistant cancer. Multidrug resistance (MDR) represents a major obstacle to effective therapeutic interventions against cancer. This review describes the known MDR mechanisms in cancer cells and discusses ongoing laboratory approaches and novel therapeutic strategies that aim to inhibit, circumvent, or reverse MDR development in various cancer types. In this review, we discuss both intrinsic and acquired drug resistance, in addition to highlighting hypoxia- and autophagy-mediated drug resistance mechanisms. Several factors, including individual genetic differences, such as mutations, altered epigenetics, enhanced drug efflux, cell death inhibition, and various other molecular and cellular mechanisms, are responsible for the development of resistance against anticancer agents. Drug resistance can also depend on cellular autophagic and hypoxic status. The expression of drug-resistant genes and the regulatory mechanisms that determine drug resistance are also discussed. Methods to circumvent MDR, including immunoprevention, the use of microparticles and nanomedicine might result in better strategies for fighting cancer.

Current Developments of N-Heterocyclic Carbene Au(I)/Au(III) Complexes toward Cancer Treatment

Since their first discovery, N-heterocyclic carbenes have had a significant impact on organometallic chemistry. Due to their nature as strong σ-donor and π-acceptor ligands, they are exceptionally well suited to stabilize Au(I) and Au(III) complexes in biological environments. Over the last decade, the development of rationally designed NHCAu(I/III) complexes to specifically target DNA has led to a new “gold rush” in bioinorganic chemistry. This review aims to summarize the latest advances of NHCAu(I/III) complexes that are able to interact with DNA. Furthermore, the latest advancements on acyclic diamino carbene gold complexes with anticancer activity are presented as these typically overlooked NHC alternatives offer great additional design possibilities in the toolbox of carbene-stabilized gold complexes for targeted therapy.

A family of amphiphilic dioxidovanadium(V) hydrazone complexes as potent carbonic anhydrase inhibitors along with anti-diabetic and cytotoxic activities

A family of dioxidovanadium(V) complexes (1-4) of the type [Na(H₂O)_x]⁺[V^VO₂(HL^1-4)]^- (x = 4, 4.5 and 7) where HL^2- represents the dianionic form of 2-hydroxybenzoylhydrazone of 2-hydroxyacetophenone (H₂L¹, complex 1), 2-hydroxy-5-methylacetophenone (H₂L², complex 2), 2-hydroxy-5-methoxyacetophenone (H₂L³, complex 3) and 2-hydroxy-5-chloroacetophenone (H₂L⁴, complex 4), have been synthesized and characterized by analytical and spectral methods. These complexes exhibited the potential abilities to suppress the erythrocytes carbonic anhydrase enzymatic activity in type 1 and type 2 diabetic patients (in vitro), promising antidiabetic activity against T2 diabetic mice (in vivo). They also exhibited significant cytotoxic activity against cervical cancer (SiHa) cells (in vitro) as the IC₅₀ value of complexes 1, 2 and 4 is substantially lower than the value found for cisplatin while that of 3 is comparable and follow the order: 4 < 1 < 2 < 3 and can kill the cells by apoptosis via the generation of reactive oxygen species (ROS). The complexes are soluble both in water and octanol media and also non-toxic at working concentrations. The antidiabetic activity of these four complexes follows the order: 4 > 2 > 1 > 3 while both the carbonic anhydrase and cytotoxic activity follow the order: 4 > 1 > 2 > 3 suggesting that complex 4, containing electron withdrawing Cl atom is the most reactive while 3 with electron donating OCH₃ group is the least reactive species. The molecular docking study on hCA-I and hCA-II demonstrates that complexes interact via hydrogen bonding as well as different types of π-stacking.

Cu(I) and Cu(II) Complexes Based on Lonidamine-Conjugated Ligands Designed to Promote Synergistic Antitumor Effects

Bis(pyrazol-1-yl)- and bis(3,5-dimethylpyrazol-1-yl)-acetates were conjugated with the 2-hydroxyethylester and 2-aminoethylamide derivatives of the antineoplastic drug lonidamine to prepare Cu(I) and Cu(II) complexes that might act through synergistic mechanisms of action due to the presence of lonidamine and copper in the same chemical entity. Synchrotron radiation-based complementary techniques [X-ray photorlectron spectroscopy and near-edge X-ray absorption fine structure (NEXAFS)] were used to characterize the electronic and molecular structures of the complexes and the local structure around the copper ion (XAFS) in selected complexes. All complexes showed significant antitumor activity, proving to be more effective than the reference drug cisplatin in a panel of human tumor cell lines, and were able to overcome oxaliplatin and multidrug resistance. Noticeably, these Cu complexes appeared much more effective than cisplatin against 3D spheroids of pancreatic PSN-1 cancer cells; among these, PPh₃-containing Cu(I) complex 15 appeared to be the most promising derivative. Mechanistic studies revealed that 15 induced cancer cell death by means of an apoptosis-alternative cell death.

Mo(VI) Potential Metallodrugs: Explaining the Transport and Cytotoxicity by Chemical Transformations

The transport and cytotoxicity of molybdenum-based drugs have been explained with the concept of chemical transformation, a very important idea in inorganic medicinal chemistry that is often overlooked in the interpretation of the biological activity of metal-containing systems. Two monomeric, [MoO₂(L¹)(MeOH)] (1) and [MoO₂(L²)(EtOH)] (2), and two mixed-ligand dimeric Mo^VIO₂ species, [{MoO₂(L^1-2)}₂(μ-4,4'-bipy)] (3-4), were synthesized and characterized. The structures of the solid complexes were solved through SC-XRD, while their transformation in water was clarified by UV-vis, ESI-MS, and DFT. In aqueous solution, 1-4 lead to the penta-coordinated [MoO₂(L^1-2)] active species after the release of the solvent molecule (1 and 2) or removal of the 4,4'-bipy bridge (3 and 4). [MoO₂(L^1-2)] are stable in solution and react with neither serum bioligand nor cellular reductants. The binding affinity of 1-4 toward HSA and DNA were evaluated through analytical and computational methods and in both cases a non-covalent interaction is expected. Furthermore, the in vitro cytotoxicity of the complexes was also determined and flow cytometry analysis showed the apoptotic death of the cancer cells. Interestingly, μ-4,4'-bipy bridged complexes 3 and 4 were found to be more active than monomeric 1 and 2, due to the mixture of species generated, that is [MoO₂(L^1-2)] and the cytotoxic 4,4'-bipy released after their dissociation. Since in the cytosol neither the reduction of Mo^VI to Mo^V/IV takes place nor the production of reactive oxygen species (ROS) through Fenton-like reactions of 1-4 with H₂O₂ occurs, the mechanism of cytotoxicity should be attributable to the direct interaction with DNA that happens with a minor-groove binding which results in cell death through an apoptotic mechanism.

Relevance of Fluorinated Ligands to the Design of Metallodrugs for Their Potential Use in Cancer Treatment

Fluorination of pharmaceutical agents has afforded crucial modifications to their pharmacological profiles, leading to important advances in medicinal chemistry. On the other hand, metallodrugs are considered to be valuable candidates in the treatment of several diseases, albeit with the caveat that they may exhibit pharmacological disadvantages, such as poor water solubility, low bioavailability and short circulating time. To surmount these limitations, two approaches have been developed: one based on the design of novel metallodrug-delivering carriers and the other based on optimizing the structure of the ligands bound to the metal center. In this context, fluorination of the ligands may bring beneficial changes (physicochemical and biological) that can help to elude the aforementioned drawbacks. Thus, in this review, we discuss the use of fluorinated ligands in the design of metallodrugs that may exhibit potential anticancer activity.

The role of hydrolysis in biological effects of molybdenum cluster with DMSO ligands

Biological applications of octahedral molybdenum cluster complexes are complicated by their hydrolytic instability, since hydrolysis leads to irreversible changes in the structure and properties of these compounds. On the other hand, if such changes are thoroughly investigated and understood, the hydrolysis process can become an important tool for regulating specific biological effects of the clusters. In this work, we demonstrate how the luminescence and biological properties (cellular uptake, cytotoxicity in the dark and photodynamic effect) of highly unstable cluster complex [{Mo₆I₈}(DMSO)₆](NO₃)₄ change along with the degree of hydrolysis. Particularly, cluster solution preliminarily aged in water demonstrated lower dark and higher photoinduced cytotoxicity and higher cellular uptake in comparison with fresh solution.

[(C C)Au(N N)]+ Complexes as a New Family of Anticancer Candidates: Synthesis, Characterization and Exploration of the Antiproliferative Properties

A library of eleven cationic gold(III) complexes of the general formula [(C C)Au(N N)]⁺ when C C is either biphenyl or 4,4'-ditertbutyldiphenyl and N N is a bipyridine, phenanthroline or dipyridylamine derivative have been synthesized and characterized. Contrasting effects on the viability of the triple negative breast cancer cells MDA-MB-231 was observed from a preliminary screening. The antiproliferative activity of the seven most active complexes were further assayed on a larger panel of human cancer cells as well as on non-cancerous cells for comparison. Two complexes stood out for being either highly active or highly selective. Eventually, reactivity studies with biologically meaningful amino acids, glutathione, higher order DNA structures and thioredoxin reductase (TrxR) revealed a markedly different behavior from that of the well-known coordinatively isomeric [(C N C)Au(NHC)]⁺ structure. This makes the [(C C)Au(N N)]⁺ complexes a new class of organogold compounds with an original mode of action.

Ternary Copper Complex of L-Glutamine and Phenanthroline as Counterions of Cyclo-Tetravanadate Anion: Experimental–Theoretical Characterization and Potential Antineoplastic Activity

Over the last decade, therapeutic metallodrugs have become substantially effective in the treatment of cancer. Thus, developing new effective anticancer drugs is a significant research area against the continuing increase in cancers worldwide. In the search for heterobimetallic prodrugs containing V/Cu, a new cyclo-tetravanadate was synthesized and characterized by UV-visible and FTIR spectroscopies and single-crystal X-ray diffraction. L-Glutamine and 1,10-phenanthroline allow the crystallization of [Cu(L-Gln)(phen)(H2O)]4[V4O12]∙8(H2O) (1), in which the cyclo-tetravanadate acts as a free anion. Density functional theory (DFT) calculations were carried out to characterize the frontier molecular orbitals and molecular electrostatic potential. Global reactivity indexes were calculated and analyzed to give insight into the cyclo-tetravanadate anion and complex counterions interactions. Also, using Bader’s theory of atoms in molecules (AIM), non-covalent interactions were analyzed. Docking analysis with the Casiopeina-like complex resulting from the hydrolysis of compound 1 provided insights into these complex potential anticancer activities by interacting with DNA/tRNA via H-bonds and hydrophobic interactions. The release of both components could act together or separately, acting as prodrugs with potential dual antineoplastic activities.

In Vitro Nephrotoxicity Studies of Established and Experimental Platinum-Based Compounds

Cisplatin is one of the most commonly used drugs for the treatment of various solid cancers. However, its efficacy is restricted by severe side effects, especially dose-limiting nephrotoxicity. New platinum-based compounds are designed to overcome this limitation. Previous investigations showed that the platinum(IV)–nitroxyl complex PN149 is highly cytotoxic in various tumor cell lines. In the present study, investigations with PN149 were extended to normal human kidney tubule epithelia. Coincident with higher intracellular platinum accumulation, the cytotoxicity of PN149 in the proximal tubule epithelial cell line ciPTEC was more pronounced compared to the established platinum chemotherapeutics cisplatin, carboplatin and oxaliplatin. Quantitative gene expression profiling revealed the induction of ROS-inducible and anti-oxidative genes, suggesting an oxidative stress response by PN149. However, in contrast to cisplatin, no pro-inflammatory response was observed. Genes coding for distinct DNA damage response factors and genes related to apoptosis were up-regulated, indicating the activation of the DNA damage response system and induction of the apoptotic cascade by PN149. Altogether, a comparable transcriptional response was observed for PN149 and the platinum chemotherapeutics. However, the lack of inflammatory activity, which is a possible cause contributing to toxicity in human renal proximal tubule epithelia, might indicate the reduced nephrotoxic potential of PN149.

Metal- and metalloid-based compounds to target and reverse cancer multidrug resistance

Drug resistance remains the major cause of cancer treatment failure especially at the late stage of the disease. However, based on their versatile chemistry, metal and metalloid compounds offer the possibility to design fine-tuned drugs to circumvent and even specifically target drug-resistant cancer cells. Based on the paramount importance of platinum drugs in the clinics, two main areas of drug resistance reversal strategies exist: overcoming resistance to platinum drugs as well as multidrug resistance based on ABC efflux pumps. The current review provides an overview of both aspects of drug design and discusses the open questions in the field. The areas of drug resistance covered in this article involve: 1) Altered expression of proteins involved in metal uptake, efflux or intracellular distribution, 2) Enhanced drug efflux via ABC transporters, 3) Altered metabolism in drug-resistant cancer cells, 4) Altered thiol or redox homeostasis, 5) Altered DNA damage recognition and enhanced DNA damage repair, 6) Impaired induction of apoptosis and 7) Altered interaction with the immune system. This review represents the first collection of metal (including platinum, ruthenium, iridium, gold, and copper) and metalloid drugs (e.g. arsenic and selenium) which demonstrated drug resistance reversal activity. A special focus is on compounds characterized by collateral sensitivity of ABC transporter-overexpressing cancer cells. Through this approach, we wish to draw the attention to open research questions in the field. Future investigations are warranted to obtain more insights into the mechanisms of action of the most potent compounds which target specific modalities of drug resistance.

Reduction of muscle contraction and pain in electroporation-based treatments: An overview

BACKGROUND

In the first studies of electrochemotherapy (ECT), small cutaneous metastases were treated and only mild or moderate pain was observed; therefore, pain was not considered a significant issue. As the procedure began to be applied to larger cutaneous metastases, pain was reported more frequently. For that reason, reduction of both muscle contractions and pain have been investigated over the years.

AIM

To present an overview of different protocols described in literature that aim to reduce muscle contractions and pain caused by the electroporation (EP) effect in both ECT and irreversible EP treatments.

METHODS

Thirty-three studies published between January 1999 and November 2020 were included. Different protocol designs and electrode geometries that reduce patient pain and the number of muscle contractions and their intensity were analysed.

RESULTS

The analysis showed that both high frequency and bipolar/biphasic pulses can be used to reduce pain and muscle contractions in patients who undergo EP treatments. Moreover, adequate electrode design can decrease EP-related morbidity. Particularly, needle length, diameter and configuration of the distance between the needles can be optimised so that the muscle volume crossed by the current is reduced as much as possible. Bipolar/biphasic pulses with an inadequate pulse length seem to have a less evident effect on the membrane permeability compared with the standard pulse protocol. For that reason, the number of pulses and the voltage amplitude, as well as the pulse duration and frequency, must be chosen so that the dose of delivered energy guarantees EP efficacy.

CONCLUSION

Pain reduction in EP-based treatments can be achieved by appropriately defining the protocol parameters and electrode design. Most results can be achieved with high frequency and/or bipolar/biphasic pulses. However, the efficacy of these alternative protocols remains a crucial point to be assessed further.

Platinum Complexes in Colorectal Cancer and Other Solid Tumors

Simple Summary

Cisplatin is successfully used for the treatment of various solid cancers. Unfortunately, it shows no activity in colorectal cancer. The resistance phenotype of colorectal cancer cells is mainly caused by alterations in p53-controlled DNA damage signaling and/or defects in the cellular mismatch repair pathway. Improvement of platinum-based chemotherapy in cisplatin-unresponsive cancers, such as colorectal cancer, might be achieved by newly designed cisplatin analogues, which retain activity in unresponsive tumor cells. Moreover, a combination of cisplatin with biochemical modulators of DNA damage signaling might sensitize cisplatin-resistant tumor cells to the drug, thus providing another strategy to improve cancer therapy.

Abstract

Cisplatin is one of the most commonly used drugs for the treatment of various solid neoplasms, including testicular, lung, ovarian, head and neck, and bladder cancers. Unfortunately, the therapeutic efficacy of cisplatin against colorectal cancer is poor. Various mechanisms appear to contribute to cisplatin resistance in cancer cells, including reduced drug accumulation, enhanced drug detoxification, modulation of DNA repair mechanisms, and finally alterations in cisplatin DNA damage signaling preventing apoptosis in cancer cells. Regarding colorectal cancer, defects in mismatch repair and altered p53-mediated DNA damage signaling are the main factors controlling the resistance phenotype. In particular, p53 inactivation appears to be associated with chemoresistance and poor prognosis. To overcome resistance in cancers, several strategies can be envisaged. Improved cisplatin analogues, which retain activity in resistant cancer, might be applied. Targeting p53-mediated DNA damage signaling provides another therapeutic strategy to circumvent cisplatin resistance. This review provides an overview on the DNA repair pathways involved in the processing of cisplatin damage and will describe signal transduction from cisplatin DNA lesions, with special attention given to colorectal cancer cells. Furthermore, examples for improved platinum compounds and biochemical modulators of cisplatin DNA damage signaling will be presented in the context of colon cancer therapy.

Coupled mathematical modeling of cisplatin electroporation

The use of electrochemotherapy (ECT) is a well-established technique to increase the cellular uptake of cytotoxic agents within certain cancer treatment strategies. The study of the mechanisms that take part in this complex process is of high interest to gain a deeper knowledge of it, enabling the improvement of these strategies. In this work, we present a coupled multi-physics electroporation model based on a related previous one, to describe the effect of a set of electric pulses on cisplatin transport across the plasma membrane. The model applies a system of partial differential equations that includes Poisson's equation for the electric field, Nernst-Planck's equation for species transport, Maxwell's tensor and mechanical equilibrium equation for membrane deformation and Smoluchowski's equation for pore creation dynamics. Our numerical results were compared with previous numerical and experimental published data with good qualitative and quantitative agreement. These results indicate that pore aperture is favored at the cell poles by the electric field and mechanical stress forces, giving support to the dominant hypothesis of hydrophilic pore creation as the main mechanism of drug entry during an ECT treatment.

Redox and apoptotic potential of novel ruthenium complexes in rat blood and heart

Ruthenium(II) complexes offer the potential for lower toxicity compared with platinum(II) complexes. Our study aimed to compare cardiotoxicity of [Ru(Cl-tpy)(en)Cl][Cl], [Ru(Cl-tpy)(dach)Cl][Cl], [Ru(Cl-tpy)(bpy)Cl][Cl], cisplatin, and saline through assessment of redox status and relative expression of apoptosis-related genes. A total of 40 Wistar albino rats were divided into five groups. Ruthenium groups received a single dose of complexes intraperitoneally (4 mg/kg/week) for a 4-week period; cisplatin group received cisplatin (4 mg/kg/week) and control group received saline (4 mL/kg/week) in the same manner as ruthenium groups. In collected blood and heart tissue samples, spectrophotometric determination of oxidative stress biomarkers was performed. The relative expression of apoptosis-related genes (Bcl-2, Bax, and caspase-3) in hearts was examined by real-time polymerase chain reaction. Our results showed that systemic and cardiac pro-oxidative markers (thiobarbituric acid reactive substances and nitrite) were significantly lower in ruthenium groups compared with cisplatin group, while concentrations of antioxidative parameters (catalase, superoxide dismutase, and oxidized glutathione) were significantly higher. Ruthenium administration led to significantly lower gene expression of Bax and caspase-3 compared with cisplatin-treated rats, while Bcl-2 remained unchanged. Applied ruthenium complexes have less pronounced potential for induction of oxidative stress-mediated cardiotoxicity compared with cisplatin. These findings may help for future studies that should clarify the mechanisms of cardiotoxicity of ruthenium-based metallodrugs.

Mustards-Derived Terpyridine-Platinum Complexes as Anticancer Agents: DNA Alkylation vs Coordination

The development of bifunctional platinum complexes with the ability to interact with DNA via different binding modes is of interest in anticancer metallodrug research. Therefore, we report platinum(II) terpyridine complexes to target DNA by coordination and/or through a tethered alkylating moiety. The platinum complexes were evaluated for their in vitro antiproliferative properties against the human cancer cell lines HCT116 (colorectal), SW480 (colon), NCI-H460 (non-small cell lung), and SiHa (cervix) and generally exhibited potent antiproliferative activity although lower than their respective terpyridine ligands. ¹H NMR spectroscopy and/or ESI-MS studies on the aqueous stability and reactivity with various small biomolecules, acting as protein and DNA model compounds, were used to establish potential modes of action for these complexes. These investigations indicated rapid binding of complex PtL3 to the biomolecules through coordination to the Pt center, while PtL4 in addition alkylated 9-ethylguanine. PtL3 was investigated for its reactivity to the model protein hen egg white lysozyme (HEWL) by protein crystallography which allowed identification of the N^δ1 atom of His15 as the binding site.

Biochemical pathways of copper complexes: progress over the past 5 years

Copper is an essential trace element with vital roles in many metalloenzymes; it is also prominent among nonplatinum anticancer metallodrugs. Copper-based complexes are endogenously biocompatible, tenfold more potent than cisplatin, exhibit fewer adverse effects, and have a wide therapeutic window. In cancer biology, copper acts as an antitumor agent by inhibiting cancer via multiple pathways. Herein, we present an overview of advances in copper complexes as 'lead' antitumor drug candidates, and in understanding their biochemical and pharmacological pathways over the past 5 years. This review will help to develop more efficacious therapeutics to improve clinical outcomes for cancer treatments.

Breaking the Intracellular Redox Balance with Diselenium Nanoparticles for Maximizing Chemotherapy Efficacy on Patient-Derived Xenograft Models

Excessive oxidative stress in cancer cells can induce cancer cell death. Anticancer activity and drug resistance of chemotherapy are closely related to the redox state of tumor cells. Herein, five lipophilic Pt(IV) prodrugs were synthesized on the basis of the most widely used anticancer drug cisplatin, whose anticancer efficacy and drug resistance are closely related to the intracellular redox state. Subsequently, a series of cisplatin-sensitive and drug-resistant cell lines as well as three patient-derived primary ovarian cancer cells have been selected to screen those prodrugs. To verify if the disruption of redox balance can be combined with these Pt(IV) prodrugs, we then synthesized a polymer with a diselenium bond in the main chain for encapsulating the most effective prodrug to form nanoparticles (NP(Se)s). NP(Se)s can efficiently break the redox balance via simultaneously depleting GSH and augmenting ROS, thereby achieving a synergistic effect with cisplatin. In addition, genome-wide analysis via RNA-seq was employed to provide a comprehensive understanding of the changes in transcriptome and the alterations in redox-related pathways in cells treated with NP(Se)s and cisplatin. Thereafter, patient-derived xenograft models of hepatic carcinoma (PDX^HCC) and multidrug-resistant lung cancer (PDX^MDR) were established to evaluate the therapeutic effect of NP(Se)s, and a significant antitumor effect was achieved on both models with NP(Se)s. Overall, this study provides a promising strategy to break the redox balance for maximizing the efficacy of platinum-based cancer therapy.

Pt(II) and Au(III) complexes containing Schiff-base ligands: A promising source for antitumor treatment

The effective application of cisplatin in the clinic as an antitumor treatment has stimulated widespread interest in inorganic metal drugs. In particular, complexes containing the transition metals platinum and gold have attracted considerable attention due to their antitumor effects. The Pt(II) and Au(III) Schiff-base complexes are potential antitumor agents because of their remarkable biological activities and good stability, lipophilicity, and electroluminescent properties. These complexes act via various antitumor mechanisms that are unlike those of the classic platinum drugs, providing a feasible solution for improving the serious side effects caused by metal chemotherapy. In this review, promising antitumor agents based on Pt(II) and Au(III) complexes containing Schiff-base ligands, and their biological targets, including G-quadruplex DNA and thioredoxin reductase, are comprehensively summarized.

A recombinant platform to characterize the role of transmembrane protein hTMEM205 in Pt(II)-drug resistance and extrusion

Platinum-coordination complexes are among the most effective chemotherapeutic drugs used in clinics for the treatment of cancer. Despite their efficacy, cancer cells can develop drug resistance leading to treatment failure and relapse. Cellular uptake and extrusion of Pt(ii)-complexes mediated by transmembrane proteins are critical in controlling the intracellular concentration of Pt(ii)-drugs and in developing pre-target resistance. TMEM205 is a human transmembrane protein (hTMEM205) overexpressed in cancer cells that are resistant to cisplatin, but its molecular function underlying - resistance remains elusive. We developed a low-cost and high-throughput recombinant expression platform coupled to in vivo functional resistance assays to study the molecular mechanism by which the orphan hTMEM205 protects against Pt(ii)-complex toxicity. Based on the original observation by the Rosenberg group, which led to the discovery of cisplatin, we performed quantitative analysis of the effects of Pt(ii)-coordination complexes on cellular growth and filamentation in E. coli cells expressing hTMEM205. By coupling our methods with Pt quantification and cellular profiling in control and hTMEM205-expressing cells, we demonstrate that hTMEM205 mediates Pt(ii)-drug export selectively towards cisplatin and oxaliplatin but not carboplatin. By mutation analysis, we reveal that hTMEM205 recognizes and allows Pt(ii)-extrusion by a putative sulfur-based translocation mechanism, thereby resulting in pre-target resistance. Thus, hTMEM205 represents a new potential target that can be exploited to reduce cellular resistance towards Pt(ii)-drugs.

Reductive Stress, Bioactive Compounds, Redox-Active Metals, and Dormant Tumor Cell Biology to Develop Redox-Based Tools for the Treatment of Cancer

Significance: Cancer is related to redox biology from many points of view, such as initiation and promotion, metabolism and growth, invasion and metastasis, vascularization, or through the interaction with the immune system. In addition, this extremely complex relationship depends on the redox homeostasis of each cellular compartment, which might be used to fight cancer. Recent Advances: New ways of modulating specific and little explored aspects of redox biology have been revealed, as well as new delivery methods or uses of previously known treatments against cancer. Here, we review the latest experimental evidence regarding redox biology in cancer treatment and analyze its potential impact in the development of improved and more effective antineoplastic therapies. Critical Issues: A critical issue that deserves particular attention is the understanding that both extremes of redox biology (i.e., oxidative stress [OS] and reductive stress) might be useful or harmful in relation to cancer prevention and treatment. Future Directions: Additional research is needed to understand how to selectively induce reductive or OS adequately to avoid cancer proliferation or to induce cancer cell death.

Synthesis, Crystal Structure, and Computational Methods of Vanadium and Copper Compounds as Potential Drugs for Cancer Treatment

Transition metal-based compounds have shown promising uses as therapeutic agents. Among their unique characteristics, these compounds are suitable for interaction with specific biological targets, making them important potential drugs to treat various diseases. Copper compounds, of which Casiopeinas® are an excellent example, have shown promising results as alternatives to current cancer therapies, in part because of their intercalative properties with DNA. Vanadium compounds have been extensively studied for their pharmacological properties and application, mostly in diabetes, although recently, there is a growing interest in testing their activity as anti-cancer agents. In the present work, two compounds, [Cu(Metf)(bipy)Cl]Cl·2H2O and [Cu(Impy)(Gly)(H2O)]VO3, were obtained and characterized by visible and FTIR spectroscopies, single-crystal X-ray diffraction, and theoretical methods. The structural and electronic properties of the compounds were calculated through the density functional theory (DFT) using the Austin-Frisch-Petersson functional with dispersion APFD, and the 6-311 + G(2d,p) basis set. Non-covalent interactions were analyzed using Hirshfeld surface analysis (HSA) and atom in molecules analysis (AIM). Additionally, docking analysis to test DNA/RNA interactions with the Casiopeina-like complexes were carried out. The compounds provide metals that can interact with critical biological targets. In addition, they show interesting non-covalent interactions that are responsible for their supramolecular arrangements.

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.

Antiproliferative Activity of Functionalized Histidine-derived Au(I) bis-NHC Complexes for Bioconjugation

A series of histidine derived Au(I) bis-NHC complexes bearing different ester, amide and carboxylic acid functionalities as well as wingtip substituents is synthesized and characterized. The stability in aqueous media, in vitro cytotoxicity in a set of cancer cell lines (MCF7, PC3 and A2780/A2780cisR) along with the cellular uptake are evaluated. Stability tests suggest hydrolysis of the ester within 8 h, which might lead to deactivation. Furthermore, the bis-NHC system shows a sufficient stability against cysteine and the thiol containing peptide GSH. The benzyl ester and amide show the highest activity comparable to the benchmark compound cisplatin, with the ester only displaying a slightly lower cytotoxicity than the amide. A cellular uptake study revealed that the benzyl ester and the amide could have different intracellular distribution profiles but both complexes induce perturbations of the cellular physiological processes. The simple modifiability and high stability of the complexes provides a promising system for upcoming post modifications to enable targeted cancer therapy.

Exploring Ovarian Cancer Cell Resistance to Rhenium Anticancer Complexes

Rhenium tricarbonyl complexes have been recently investigated as novel anticancer agents. However, little is understood about their mechanisms of action, as well as the means by which cancer cells respond to chronic exposure to these compounds. To gain a deeper mechanistic insight into these rhenium anticancer agents, we developed and characterized an ovarian cancer cell line that is resistant to a previously studied compound [Re(CO)3 (dmphen)(ptolICN)]+ , where dmphen=2,9-dimethyl-1,10-phenanthroline and ptolICN=para-tolyl isonitrile, called TRIP. This TRIP-resistant ovarian cancer cell line, A2780TR, was found to be 9 times less sensitive to TRIP compared to the wild-type A2780 ovarian cancer cell line. Furthermore, the cytotoxicities of established drugs and other rhenium anticancer agents in the TRIP-resistant cell line were determined. Notably, the drug taxol was found to exhibit a 184-fold decrease in activity in the A2780TR cell line, suggesting that mechanisms of resistance towards TRIP and this drug are similar. Accordingly, expression levels of the ATP-binding cassette transporter P-glycoprotein, an efflux transporter known to detoxify taxol, were found to be elevated in the A2780TR cell line. Additionally, a gene expression analysis using the National Cancer Institute 60 cell line panel identified the MT1E gene to be overexpressed in cells that are less sensitive to TRIP. Because this gene encodes for metallothioneins, this result suggests that detoxification by this class of proteins is another mechanism for resistance to TRIP. The importance of this gene in the A2780TR cell line was assessed, confirming that its expression is elevated in this cell line as well. As the first study to investigate and identify the cancer cell resistance pathways in response to a rhenium complex, this report highlights important similarities and differences in the resistance responses of ovarian cancer cells to TRIP and conventional drugs.

Exploring ovarian cancer cell resistance to rhenium anticancer complexes

Rhenium tricarbonyl complexes have been recently investigated as novel anticancer agents. However, little is understood about their mechanisms of action, as well as the means by which cancer cells respond to chronic exposure to these compounds. To gain a deeper mechanistic insight into these rhenium anticancer agents, we developed and characterized an ovarian cancer cell line that is resistant to a previously studied compound [Re(CO)3(dmphen)(ptolICN)]+, where dmphen = 2,9-dimethyl-1,10-phenanthroline and ptolICN = para-tolyl isonitrile, called TRIP. This TRIP-resistant ovarian cancer cell line, A2780TR, was found to be 9 times less sensitive to TRIP compared to the wild-type A2780 ovarian cancer cell line. Furthermore, the cytotoxicities of established drugs and other rhenium anticancer agents in the TRIP-resistant cell line were determined. Notably, the drug taxol was found to exhibit a 184-fold decrease in activity in the A2780TR cell line, suggesting that mechanisms of resistance towards TRIP and this drug are similar. Accordingly, expression levels of the ATP-binding cassette transporter P-glycoprotein, an efflux transporter known to detoxify taxol, were found to be elevated in the A2780TR cell line. Additionally, a gene expression analysis using the National Cancer Institute 60 cell line panel identified the MT1E gene to be overexpressed in cells that are less sensitive to TRIP. Because this gene encodes for metallothioneins, this result suggests that detoxification by this class of proteins is another mechanism for resistance to TRIP. The importance of this gene in the A2780TR cell line was assessed, confirming that its expression is elevated in this cell line as well. As the first study to investigate and identify the cancer cell resistance pathways in response to a rhenium complex, this report high-lights important similarities and differences in the resistance responses of ovarian cancer cells to TRIP and conventional drugs.

Ruthenium Dendrimers against Human Lymphoblastic Leukemia 1301 Cells

Ruthenium atoms located in the surfaces of carbosilane dendrimers markedly increase their anti-tumor properties. Carbosilane dendrimers have been widely studied as carriers of drugs and genes owing to such characteristic features as monodispersity, stability, and multivalence. The presence of ruthenium in the dendrimer structure enhances their successful use in anti-cancer therapy. In this paper, the activity of dendrimers of generation 1 and 2 against 1301 cells was evaluated using Transmission Electron Microscopy, comet assay and Real Time PCR techniques. Additionally, the level of reactive oxygen species (ROS) and changes of mitochondrial potential values were assessed. The results of the present study show that ruthenium dendrimers significantly decrease the viability of leukemia cells (1301) but show low toxicity to non-cancer cells (peripheral blood mononuclear cells-PBMCs). The in vitro test results indicate that the dendrimers injure the 1301 leukemia cells via the apoptosis pathway.