Quantitative evaluation of cellular uptake, DNA incorporation and adduct formation in cisplatin sensitive and resistant cell lines: Comparison of different Pt-containing drugs

Nucleic Acid-based Electrochemical Sensors Facilitate the Study of DNA Binding by Platinum (II)-based Antineoplastics

DNA crosslinking agents such as cisplatin and related platinum(II) analogs are effective drugs to treat solid tumors. However, these therapeutics can cause high toxicity in the body, and tumors can develop resistance to them. To develop less toxic and more effective DNA crosslinkers, medicinal chemists have focused on tuning the ligands in square planar platinum(II) complexes to modulate their bioavailability, targeted cell penetration, and DNA binding rates. Unfortunately, linking in vitro DNA binding capacity of DNA crosslinkers with their in vivo efficacy has proven challenging. Here we report an electrochemical biosensor strategy that allows the study of platinum(II)-DNA binding in real time. Our biosensors contain a purine-rich deoxynucleotide sequence, T6 (AG)10 , modified with a 5' hexylthiol linker for easy self-assembly onto gold electrodes. The 3' terminus is functionalized with the redox reporter methylene blue. Electron transfer from methylene blue to the sensor is a function of platinum(II) compound concentration and reaction time. Using these biosensors, we resolve DNA binding mechanisms including monovalent and bivalent binding, as well as base stacking. Our approach can measure DNA binding kinetics in buffers and in 50 % serum, offering a single-step, real-time approach to screen therapeutic compounds during drug development.

PLA2G4A and ACHE modulate lipid profiles via glycerophospholipid metabolism in platinum-resistant gastric cancer

BACKGROUND

Bioactive lipids involved in the progression of various diseases. Nevertheless, there is still a lack of biomarkers and relative regulatory targets. The lipidomic analysis of the samples from platinum-resistant in gastric cancer patients is expected to help us further improve our understanding of it.

METHODS

We employed LC-MS based untargeted lipidomic analysis to search for potential candidate biomarkers for platinum resistance in GC patients. Partial least squares discriminant analysis (PLS-DA) and variable importance in projection (VIP) analysis were used to identify differential lipids. The possible molecular mechanisms and targets were obtained by metabolite set enrichment analysis and potential gene network screened. Finally, verified them by immunohistochemical of a tissue microarray.

RESULTS

There were 71 differential lipid metabolites identified in GC samples between the chemotherapy-sensitivity group and the chemotherapy resistance group. According to Foldchange (FC) value, VIP value, P values (FC > 2, VIP > 1.5, p < 0.05), a total of 15 potential biomarkers were obtained, including MGDG(43:11)-H, Cer(d18:1/24:0) + HCOO, PI(18:0/18:1)-H, PE(16:1/18:1)-H, PE(36:2) + H, PE(34:2p)-H, Cer(d18:1 + hO/24:0) + HCOO, Cer(d18:1/23:0) + HCOO, PC(34:2e) + H, SM(d34:0) + H, LPC(18:2) + HCOO, PI(18:1/22:5)-H, PG(18:1/18:1)-H, Cer(d18:1/24:0) + H and PC(35:2) + H. Furthermore, we obtained five potential key targets (PLA2G4A, PLA2G3, DGKA, ACHE, and CHKA), and a metabolite-reaction-enzyme-gene interaction network was built to reveal the biological process of how they could disorder the endogenous lipid profile of platinum resistance in GC patients through the glycerophospholipid metabolism pathway. Finally, we further identified PLA2G4A and ACHE as core targets of the process by correlation analysis and tissue microarray immunohistochemical verification.

CONCLUSION

PLA2G4A and ACHE regulated endogenous lipid profile in the platinum resistance in GC patients through the glycerophospholipid metabolism pathway. The screening of lipid biomarkers will facilitate earlier precision medicine interventions for chemotherapy-resistant gastric cancer. The development of therapies targeting PLA2G4A and ACHE could enhance platinum chemotherapy effectiveness.

Review on the Applications of Selected Metal-Based Complexes on Infectious Diseases

Fatalities caused by infectious diseases (i.e., diseases caused by parasite, bacteria, and viruses) have become reinstated as a major public health threat globally. Factors such as antimicrobial resistance and viral complications are the key contributors to the death numbers. As a result, new compounds with structural diversity classes are critical for controlling the virulence of pathogens that are multi-drug resistant. Derivatization of bio-active organic molecules with organometallic synthons is a promising strategy for modifying the inherent and enhanced properties of biomolecules. Due to their redox chemistry, bioactivity, and structural diversity, organometallic moieties make excellent candidates for lead structures in drug development. Furthermore, organometallic compounds open an array of potential in therapy that existing organic molecules lack, i.e., their ability to fulfill drug availability and resolve the frequent succumbing of organic molecules to drug resistance. Additionally, metal complexes have the potential towards metal-specific modes of action, preventing bacteria from developing resistance mechanisms. This review's main contribution is to provide a thorough account of the biological efficacy (in vitro and in vitro) of metal-based complexes against infectious diseases. This resource can also be utilized in conjunction with corresponding journals on metal-based complexes investigated against infectious diseases.

Bioanalytical strategies to evaluate cisplatin nanodelivery systems: From synthesis to incorporation in individual cells and biological response

Cisplatin metallodrugs have been widely used in the treatment of multiple cancers over the last years. Nevertheless, its limited effectiveness, development of acquired drug resistances, and toxic effects decrease nowadays their application in clinical settings. Aiming at improving their features, investigations have been oriented towards the coupling of cisplatin to nanocarriers, like liposomes or inorganic nanoparticles. Moreover, these systems can be further developed to allow targeted co-delivery of drugs. In this review, we describe the major nanosystems and the optimal analytical strategies for their assessment. Finally, we describe the main biological effects of these metallodrug conjugates and the available approaches for their study.

Targeted inhibition of BET proteins in HPV-16 associated head and neck squamous cell carcinoma reveals heterogeneous transcription response

Integrated human papillomavirus (HPV-16) associated head and neck squamous cell carcinoma (HNSCC) tumors have worse survival outcomes compared to episomal HPV-16 HNSCC tumors. Therefore, there is a need to differentiate treatment for HPV-16 integrated HNSCC from other viral forms. We analyzed TCGA data and found that HPV+ HNSCC expressed higher transcript levels of the bromodomain and extra terminal domain (BET) family of transcriptional coregulators. However, the mechanism of BET protein-mediated transcription of viral-cellular genes in the integrated viral-HNSCC genomes needs to be better understood. We show that BET inhibition downregulates E6 significantly independent of the viral transcription factor, E2, and there was overall heterogeneity in the downregulation of viral transcription in response to the effects of BET inhibition across HPV-associated cell lines. Chemical BET inhibition was phenocopied with the knockdown of BRD4 and mirrored downregulation of viral E6 and E7 expression. Strikingly, there was heterogeneity in the reactivation of p53 levels despite E6 downregulation, while E7 downregulation did not alter Rb levels significantly. We identified that BET inhibition directly downregulated c-Myc and E2F expression and induced CDKN1A expression. Overall, our studies show that BET inhibition provokes a G1-cell cycle arrest with apoptotic activity and suggests that BET inhibition regulates both viral and cellular gene expression in HPV-associated HNSCC.

The mechanism of antiproliferative activity of the oxaliplatin pyrophosphate derivative involves its binding to nuclear DNA in cancer cells

(1R,2R-diaminocyclohexane)(dihydropyrophosphato) platinum(II), also abbreviated as RRD2, belongs to a class of potent antitumor platinum cytostatics called phosphaplatins. Curiously, several published studies have suggested significant mechanistic differences between phosphaplatins and conventional platinum antitumor drugs. Controversial findings have been published regarding the role of RRD2 binding to DNA in the mechanism of its antiproliferative activity in cancer cells. This prompted us to perform detailed studies to confirm or rule out the role of RRD2 binding to DNA in its antiproliferative effect in cancer cells. Here, we show that RRD2 exhibits excellent antiproliferative activity in various cancer cell lines, with IC50 values in the low micromolar or submicromolar range. Moreover, the results of this study demonstrate that DNA lesions caused by RRD2 contribute to killing cancer cells treated with this phosphaplatin derivative. Additionally, our data indicate that RRD2 accumulates in cancer cells but to a lesser extent than cisplatin. On the other hand, the efficiency of cisplatin and RRD2, after they accumulate in cancer cells, in binding to nuclear DNA is similar. Our results also show that RRD2 in the medium, in which the cells were cultured before RRD2 accumulated inside the cells, remained intact. This result is consistent with the view that RRD2 is activated by releasing free pyrophosphate only in the environment of cancer cells, thereby allowing RRD2 to bind to nuclear DNA.

Nanomedicines with high drug availability and drug sensitivity overcome hypoxia-associated drug resistance

Tumor hypoxia heterogeneity, a hallmark of the tumor microenvironment, confers resistance to conventional chemotherapy due to insufficient drug availability and drug sensitivity in hypoxic regions. To overcome these challenges, we develope a nanomedicine, NP_HPaPN, constructed with hyaluronic acid (HA) grafted with cisplatin prodrug and PEG-azobenzene for hypoxia-responsive PEG shell deshielding and loaded with a DNA damage repair inhibitor (NERi). After arriving at the tumor site, NP_HPaPN deshields the PEG shell in response to hypoxia due to the enzymolysis of azobenzene and thus exposes HA. The exposed HA binds to the highly expressed CD44 on cisplatin-resistant tumor cells and mediates drug internalization, thus increasing drug availability to hypoxic tumor cells. After intracellular hyaluronidase-mediated cleavage, the HA NPs release the cisplatin prodrug and NERi, and cause enhanced DNA damage and consequent cell death, thus enhancing the drug sensitivity of hypoxic tumor cells. Eventually, NP_HPaPN achieves distinct tumor growth suppression with an ∼84.4% inhibition rate.

Single-cell and bulk ICP-MS investigation of accumulation patterns of Pt-based metallodrugs in cisplatin-sensitive and -resistant cell models

In research enabling preclinical development and attaining a deeper understanding of the behavior of metallodrugs in cancer cells with acquired resistance, intracellular Pt accumulation could be considered an important biomarker and analytical focus. In this work, Pt accumulation patterns in terms of the number of cells and Pt mass in single cells were precisely defined by using inductively coupled plasma-mass spectrometry (ICP-MS) operating in a fast time-resolved analysis mode. This technique is otherwise known as single-cell (SC)-ICP-MS. By applying the nascent and validated SC-ICP-MS technique, comparisons across three Pt drugs (cisplatin, carboplatin, and oxaliplatin) in the A2780 and A2780cis ovarian cancer cell models could be made. Additional roles of transporters on top of passive diffusion and the drugs' bioactivity could be postulated. The SC-ICP-MS-based observations also served as a cross-validation point to augment preexisting research findings on Pt-resistance mechanisms. Conjectures regarding S and Fe metabolism were also derived based on an additional and direct ICP-MS analysis of endogenous elements. Overall, our work not only confirms the utility of SC-ICP-MS in chemotherapeutic research, but also provided insights into further ICP-MS-based analytical capacities to be developed.

Gold(III) Complexes with Phenanthroline-derivatives Ligands Induce Apoptosis in Human Colorectal and Breast Cancer Cell Lines

Due to their promising effects, gold(III) complexes recently drew increasing attention in the design of new metal-based anticancer therapeutics. Two gold(III) complexes, square-planar [Au(DPP)Cl2]+ - Complex 1 and distorted square-pyramidal [Au(DMP)Cl3] - Complex 2 (where DPP=4,7-diphenyl-1,10-phenanthroline and DMP=2,9-dimethyl-1,10-phenanthroline) were previously synthetized, described and approved as complexes with pronounced cytotoxic effects on colorectal HCT-116 and breast MDA-MB-231 cancer cells. This study investigated the type of cell death by AO/EB double staining, and identification of possible targets responsible for their cytotoxicity, monitored by immunofluorescence and qPCR methods. Both complexes induced apoptosis in all applied concentrations. In the HCT-116 cells apoptosis was activated by external apoptotic pathway, via increase of Fas receptor protein expression and Caspase 8 gene expression. Also, the mitochondrial pathway was triggered by affecting the Bcl-2 members of regulatory proteins and increased caspase 9 protein expression. In MDA-MB-231 cells, apoptosis was initiated from the mitochondria, due to disbalance between expressions of pro- and anti-apoptotic Bcl-2 family members and caspase 9 activation. Complex 1 shows better activity compared to Complex 2, which is in accordance with its structural characteristics. The results deal weighty data about proapoptotic activity of gold(III) complexes and highlighted potential targets for cancer therapy.

PT-112 Induces Mitochondrial Stress and Immunogenic Cell Death, Targeting Tumor Cells with Mitochondrial Deficiencies

Simple Summary

PT-112 is a novel pyrophosphate–platinum conjugate under Phase 1/2 clinical development for the treatment of several tumor types. In this study, using mouse tumor cells with well-characterized mitochondrial and metabolic status, we investigated the mechanisms underlying PT-112’s cancer cell death effects. Our results showed that cells with defective mitochondria were more sensitive to PT-112 when compared to cells with normal mitochondrial function. Moreover, PT-112 induced tumor cell death in those sensitive cells through non-conventional mechanisms, including increased mitochondrial stress, free radical generation and immunogenic cell death, a form of cell death that elicits an immune response. Taken together, the present findings suggest the potential for predictors of PT-112 sensitivity in the clinical setting on the basis of metabolic function.

Abstract

PT-112 is a novel pyrophosphate–platinum conjugate, with clinical activity reported in advanced pretreated solid tumors. While PT-112 has been shown to induce robust immunogenic cell death (ICD) in vivo but only minimally bind DNA, the molecular mechanism underlying PT-112 target disruption in cancer cells is still under elucidation. The murine L929 in vitro system was used to test whether differential metabolic status alters PT-112’s effects, including cell cytotoxicity. The results showed that tumor cells presenting mutations in mitochondrial DNA (mtDNA) (L929dt and L929^dt cybrid cells) and reliant on glycolysis for survival were more sensitive to cell death induced by PT-112 compared to the parental and cybrid cells with an intact oxidative phosphorylation (OXPHOS) pathway (L929 and dt^L929 cybrid cells). The type of cell death induced by PT-112 did not follow the classical apoptotic pathway: the general caspase inhibitor Z-VAD-fmk did not inhibit PT-112-induced cell death, alone or in combination with the necroptosis inhibitor necrostatin-1. Interestingly, PT-112 initiated autophagy in all cell lines, though this process was not complete. Autophagy is known to be associated with an integrated stress response in cancer cells and with subsequent ICD. PT-112 also induced a massive accumulation of mitochondrial reactive oxygen species, as well as changes in mitochondrial polarization—only in the sensitive cells harboring mitochondrial dysfunction—along with calreticulin cell-surface exposure consistent with ICD. PT-112 substantially reduced the amount of mitochondrial CoQ10 in L929 cells, while the basal CoQ10 levels were below our detection limits in L929dt cells, suggesting a potential relationship between a low basal level of CoQ10 and PT-112 sensitivity. Finally, the expression of HIF-1α was much higher in cells sensitive to PT-112 compared to cells with an intact OXPHOS pathway, suggesting potential clinical applications.

Phase I study of PT-112, a novel pyrophosphate-platinum immunogenic cell death inducer, in advanced solid tumours

BACKGROUND

PT-112, the first pyrophosphate-platinum conjugate, causes immunogenic cell death in experimental models, leading to recruitment of tumour-infiltrating lymphocytes. PT-112 also associates with bone (osteotropism), likely driven by its pyrophosphate moiety. This is the first-in-human study of PT-112 monotherapy, exploring its safety and efficacy in a patient population where standard of care therapies were exhausted and novel treatment options are needed.

METHODS

Patients with progressing, advanced solid tumours received PT-112 intravenously (1 h) on days 1, 8, 15 of a 28-day cycle in an open-label, multi-centre 3 + 3 dose-escalation trial, conducted at four US research sites. The primary objective was to assess safety and pharmacokinetics, and to identify a recommended phase 2 dose (RP2D). Eligibility criteria included: age ≥18 years, Eastern Collaborative Oncology Group (ECOG) Performance Status of 0-1, and disease evaluable by Response Evaluation Criteria in Solid Tumours (RECIST) v1·1 or by informative tumour markers. Patients receiving ≥1 dose of PT-112 were included in the safety and pharmacokinetic analyses, with the exploratory efficacy analysis including patients receiving ≥1 dose at 125 mg/m². This study is registered at ClinicalTrials.gov, number NCT02266745, with the dose-escalation portion of the study closed.

FINDINGS

Between July 7th, 2014 and September 18th, 2018, 66 heavily pre-treated patients (median 4 prior lines, IQR 2-6) were enrolled and treated across 11 doses (12-420 mg/m²). Treatment-related adverse events included fatigue (23 patients, 35%), nausea (16 patients, 24%), and peripheral neuropathy (14 patients, 21%). Grade 3 events were experienced by 18 patients (27%), with no grade 4-5 events observed. The recommended phase 2 dose was determined to be 360 mg/m². Nine (17%) of the 54 efficacy evaluable patients achieved progression-free survival ≥6 months. Durable partial responses were induced in non-small cell lung cancer (NSCLC), small cell lung cancer (SCLC), and thymoma. Radiographic and serum marker reductions were observed among ten patients with metastatic castration resistant prostate cancer, four of whom survived two years or longer.

INTERPRETATION

PT-112 is safe and well-tolerated in a heavily pre-treated population. Prolonged responses were noted against thymoma and lung cancer, along with radiographic and serum marker improvement in prostate cancer. Given the heterogeneous patient population, subsequent studies will be needed to characterize the risk/benefit ratio in more homogenous settings. Further development of PT-112 is ongoing, as single-agent and in combination with immune checkpoint inhibition.

FUNDING

Funding was provided by Promontory Therapeutics Inc.

Antitumor Properties of a New Macrocyclic Tetranuclear Oxidovanadium(V) Complex with 3-Methoxysalicylidenvaline Ligand

A wide variety of metal-based compounds have been obtained and studied for their antitumor activity since the intensely used cytostatic drugs (e.g., cisplatin) failed to accomplish their expected pharmacological properties. Thus, we aimed to develop a new vanadium-based drug and assess its antitumor properties using the human hepatocarcinoma (HepG2) cell line. The compound was synthesized from vanadyl sulfate, DL-valine, and o-vanillin and was spectrally and structurally characterized (UV-Vis, IR, CD, and single-crystal/powder-XRD). Compound stability in biological media, cell uptake, and the interaction with albumin were assessed. The mechanisms of its antitumor activity were determined compared to cisplatin by performing cytotoxicity, oxidative and mitochondrial status, DNA fragmentation, β-Tubulin synthesis investigation, and cell cycle studies. Herein, we developed a macrocyclic tetranuclear oxidovanadium(V) compound, [(V^VO)(L)(CH₃O)]₄, having coordinated four Schiff base (H₂L) ligands, 3-methoxysalicylidenvaline. We showed that [(V^VO)(L)(CH₃O)]₄: (i) has pH-dependent stability in biological media, (ii) binds to albumin in a dose-dependent manner, (iii) is taken up by cells in a time-dependent way, (iv) has a higher capacity to induce cell death compared to cisplatin (IC₅₀ = 6 μM vs. 10 μM), by altering the oxidative and mitochondrial status in HepG2 cells. Unlike cisplatin, which blocks the cell cycle in the S-phase, the new vanadium-based compound arrests it in S and G2/M-phase, whereas no differences in the induction of DNA fragmentation and reduction of β-Tubulin synthesis between the two were determined. Thus, the [(V^VO)(L)(CH₃O)]₄ antitumor mechanism involved corroboration between the generation of oxidative species, mitochondrial dysfunction, degradation of DNA, cell cycle arrest in the S and G2/M-phase, and β-Tubulin synthesis reduction. Our studies demonstrate the potent antitumor activity of [(V^VO)(L)(CH₃O)]₄ and propose it as an attractive candidate for anticancer therapy.

In-vitro anticancer profile of recent ruthenium complexes against liver cancer

Ruthenium complexes are considered as the most favorable alternatives to traditional platinum-based cancer drugs owing to their acceptable toxicity level, selectivity, variant oxidation states and ability to treat platinum-resistant cancer cells. They have similar ligand exchange kinetics as platinum drugs but can be tailored according to our desire by ligands influence. In the current study, we illustrate the in-vitro anticancer profile of some ruthenium complexes (2016–2021) against human hepatocellular carcinoma (HepG2). The anticancer activity of ruthenium complexes is determined by comparing their IC50 values with one another and positive controls. Fortunately, some ruthenium complexes including 3, 4, 6, 14, 15, 20, 42, and 48 exhibit surpassed in-vitro anticancer profile than that of positive controls promising as potential candidates against liver cancer. We also explored the structure-activity relationship (SAR) which is a key factor in the rational designing and synthesis of new ruthenium drugs. It covers the factors affecting anticancer activity including lipophilicity, planarity, area and bulkiness, the steric influence of different ligands, and electronic effects induced by ligands, stability, aqueous solubility and bioavailability to the target sites. The data reported here will provide strong support in the plausible design and synthesis of ruthenium anticancer drugs in the upcoming days.

Genomic Characterization of Cisplatin Response Uncovers Priming of Cisplatin-Induced Genes in a Resistant Cell Line

Cisplatin is a chemotherapy drug that kills cancer cells by damaging their DNA. In human cells, this damage is repaired primarily by nucleotide excision repair. While cisplatin is generally effective, many cancers exhibit initial or acquired resistance to it. Here, we studied cisplatin resistance in a defined cell line system. We conducted a comprehensive genomic characterization of the cisplatin-sensitive A2780 ovarian cancer cell line compared to A2780cis, its resistant derivative. The resistant cells acquired less damage, but had similar repair kinetics. Genome-wide mapping of nucleotide excision repair showed a shift in the resistant cells from global genome towards transcription-coupled repair. By mapping gene expression changes following cisplatin treatment, we identified 56 upregulated genes that have higher basal expression in the resistant cell line, suggesting they are primed for a cisplatin response. More than half of these genes are novel to cisplatin- or damage-response. Six out of seven primed genes tested were upregulated in response to cisplatin in additional cell lines, making them attractive candidates for future investigation. These novel candidates for cisplatin resistance could prove to be important prognostic markers or targets for tailored combined therapy in the future.

Ultrasmall iron oxide nanoparticles cisplatin (IV) prodrug nanoconjugate: ICP-MS based strategies to evaluate the formation and drug delivery capabilities in single cells

Ultrasmall iron oxide nanoparticles (<10 nm) were explored here as nanotransporters of cis-diamminetetrachloroplatinum (IV) (a cisplatin prodrug) in cellular models. The coating of the particles containing reactive carboxylic acid groups enabled the formation of a stable conjugate between the prodrug and the nanoparticles using one pot reaction. The nanoconjugate was characterized by different techniques exhibiting diameters of about 6.6 ± 1.0 nm. The use of a hyphenated strategy based on high performance liquid chromatography (HPLC) coupled to inductively coupled plasma mass spectrometry (ICP-MS) permitted the quantitative evaluation of Fe and Pt in the nanoconjugate. Furthermore, the cellular uptake of the synthetic nanoconjugate was explored by single cell-ICP-MS (SC-ICP) which was used for the first time in this type of studies. The experiments in A2780 and A2780cis, sensitive and resistant ovarian cancer cell models respectively, revealed intracellular platinum concentrations of 12 fg/cell and 4 fg/cell, respectively which were 4-fold higher with respect to the uptake of cisplatin in both models. Intracellular drug release from the nanoconjugate was proved by measuring DNA platination in the same cells. In this case, levels of about 250 ng Pt/mg DNA were observed, about 5-fold higher when the nanoconjugate was used in comparison to cisplatin. Furthermore, the differences between the two lines turned to be significantly smaller than in the case of using cisplatin. The quantitative analytical tools developed here provided essential information required to fully characterize the developed nanoplatforms particularly important to overcome drug resistance.

Sequenced Combinations of Cisplatin and Selected Phytochemicals towards Overcoming Drug Resistance in Ovarian Tumour Models

In the present study, cisplatin, artemisinin, and oleanolic acid were evaluated alone, and in combination, on human ovarian A2780, A2780^ZD0473R, and A2780^cisR cancer cell lines, with the aim of overcoming cisplatin resistance and side effects. Cytotoxicity was assessed by MTT reduction assay. Combination index (CI) values were used as a measure of combined drug effect. MALDI TOF/TOF MS/MS and 2-DE gel electrophoresis were used to identify protein biomarkers in ovarian cancer and to evaluate combination effects. Synergism from combinations was dependent on concentration and sequence of administration. Generally, bolus was most synergistic. Moreover, 49 proteins differently expressed by 2 ≥ fold were: CYPA, EIF5A1, Op18, p18, LDHB, P4HB, HSP7C, GRP94, ERp57, mortalin, IMMT, CLIC1, NM23, PSA3,1433Z, and HSP90B were down-regulated, whereas hnRNPA1, hnRNPA2/B1, EF2, GOT1, EF1A1, VIME, BIP, ATP5H, APG2, VINC, KPYM, RAN, PSA7, TPI, PGK1, ACTG and VDAC1 were up-regulated, while TCPA, TCPH, TCPB, PRDX6, EF1G, ATPA, ENOA, PRDX1, MCM7, GBLP, PSAT, Hop, EFTU, PGAM1, SERA and CAH2 were not-expressed in A2780^cisR cells. The proteins were found to play critical roles in cell cycle regulation, metabolism, and biosynthetic processes and drug resistance and detoxification. Results indicate that appropriately sequenced combinations of cisplatin with artemisinin (ART) and oleanolic acid (OA) may provide a means to reduce side effects and circumvent platinum resistance.

Targeting lipid droplet lysophosphatidylcholine for cisplatin chemotherapy

This study aims to explore lipidic mechanism towards low‐density lipoprotein receptor (LDLR)‐mediated platinum chemotherapy resistance. By using the lipid profiling technology, LDLR knockdown was found to increase lysosomal lipids and decrease membranous lipid levels in EOC cells. LDLR knockdown also down‐regulated ether‐linked phosphatidylethanolamine (PE‐O, lysosomes or peroxisomes) and up‐regulated lysophosphatidylcholine [LPC, lipid droplet (LD)]. This implies that the manner of using Lands cycle (conversion of lysophospholipids) for LDs might affect cisplatin sensitivity. The bioinformatics analyses illustrated that LDLR‐related lipid entry into LD, rather than an endogenous lipid resource (eg Kennedy pathway), controls the EOC prognosis of platinum chemotherapy patients. Moreover, LDLR knockdown increased the number of platinum‐DNA adducts and reduced the LD platinum amount. By using a manufactured LPC‐liposome‐cisplatin (LLC) drug, the number of platinum‐DNA adducts increased significantly in LLC‐treated insensitive cells. Moreover, the cisplatin content in LDs increased upon LLC treatment. Furthermore, lipid profiles of 22 carcinoma cells with differential cisplatin sensitivity (9 sensitive vs 13 insensitive) were acquired. These profiles revealed low storage lipid levels in insensitive cells. This result recommends that LD lipidome might be a common pathway in multiple cancers for platinum sensitivity in EOC. Finally, LLC suppressed both cisplatin‐insensitive human carcinoma cell training and testing sets. Thus, LDLR‐platinum insensitivity can be due to a defective Lands cycle that hinders LPC production in LDs. Using lipidome assessment with the newly formulated LLC can be a promising cancer chemotherapy method.

Preclinical studies on metal based anticancer drugs as enabled by integrated metallomics and metabolomics

Resistance development is a major obstacle for platinum-based chemotherapy, with the anticancer drug oxaliplatin being no exception. Acquired resistance is often associated with altered drug accumulation. In this work we introduce a novel -omics workflow enabling the parallel study of platinum drug uptake and its distribution between nucleus/protein and small molecule fraction along with metabolic changes after different treatment time points. This integrated metallomics/metabolomics approach is facilitated by a tailored sample preparation workflow suitable for preclinical studies on adherent cancer cell models. Inductively coupled plasma mass spectrometry monitors the platinum drug, while the metabolomics tool-set is provided by hydrophilic interaction liquid chromatography combined with high-resolution Orbitrap mass spectrometry. The implemented method covers biochemical key pathways of cancer cell metabolism as shown by a panel of >130 metabolite standards. Furthermore, the addition of yeast-based 13C-enriched internal standards upon extraction enabled a novel targeted/untargeted analysis strategy. In this study we used our method to compare an oxaliplatin sensitive human colon cancer cell line (HCT116) and its corresponding resistant model. In the acquired oxaliplatin resistant cells distinct differences in oxaliplatin accumulation correlated with differences in metabolomic rearrangements. Using this multi-omics approach for platinum-treated samples facilitates the generation of novel hypotheses regarding the susceptibility and resistance towards oxaliplatin.

EFHD2 contributes to non-small cell lung cancer cisplatin resistance by the activation of NOX4-ROS-ABCC1 axis

Recurrence and metastasis remain the major cause of cancer mortality. Even for early-stage lung cancer, adjuvant chemotherapy yields merely slight increase to patient survival. EF-hand domain-containing protein D2 (EFHD2) has recently been implicated in recurrence of patients with stage I lung adenocarcinoma. In this study, we investigated the correlation between EFHD2 and chemoresistance in non-small cell lung cancer (NSCLC). High expression of EFHD2 was significantly associated with poor overall survival of NSCLC patients with chemotherapy in in silica analysis. Ectopic EFHD2 overexpression increased cisplatin resistance, whereas EFHD2 knockdown improved chemoresponse. Mechanistically, EFHD2 induced the production of NADPH oxidase 4 (NOX4) and in turn the increase of intracellular reactive oxygen species (ROS), consequently activating membrane expression of the ATP-binding cassette subfamily C member 1 (ABCC1) for drug efflux. Non-steroidal anti-inflammatory drug (NSAID) ibuprofen suppressed EFHD2 expression by leading to the proteasomal and lysosomal degradation of EFHD2 through a cyclooxygenase (COX)-independent mechanism. Combining ibuprofen with cisplatin enhanced antitumor responsiveness in a murine xenograft model in comparison with the individual treatment. In conclusion, we demonstrate that EFHD2 promotes chemoresistance through the NOX4-ROS-ABCC1 axis and therefore developing EFHD2-targeting strategies may offer a new avenue to improve adjuvant chemotherapy of lung cancer.

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EFHD2 increases resistance of lung cancer to cisplatin.

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EFHD2 enhances the NOX4-ROS-ABCC1signalingfor cisplatin efflux.

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Ibuprofen suppresses EFHD2 through both proteasomal and lysosomal degradationmechanisms

High Throughput Approaches to Unravel the Mechanism of Action of a New Vanadium-Based Compound against Trypanosoma cruzi

Treatment for Chagas disease, a parasitosis caused by Trypanosoma cruzi, has always been based on two drugs, nifurtimox and benznidazole, despite the toxic side effects described after prolonged prescription. In this work, we study a new prospective antitrypanosomal drug based on vanadium, here named V^IVO(5Brsal)(aminophen). We found a good IC₅₀ value, (3.76 ± 0.08) μM, on CL Brener epimastigotes. The analysis of cell death mechanism allowed us to rule out the implication of a mechanism based on early apoptosis or necrosis. Recovery assays revealed a trypanostatic effect, accompanied by cell shape and motility alterations. An uptake mostly associated with the insoluble fraction of the parasites was deduced through vanadium determinations. Concordantly, no drastic changes of the parasite transcriptome were detected after 6 h of treatment. Instead, proteomic analysis uncovered the modulation of proteins involved in different processes such as energy and redox metabolism, transport systems, detoxifying pathways, ribosomal protein synthesis, and proteasome protein degradation. Overall, the results here presented lead us to propose that V^IVO(5Brsal)(aminophen) exerts a trypanostatic effect on T. cruzi affecting parasite insoluble proteins.

PT-112 induces immunogenic cell death and synergizes with immune checkpoint blockers in mouse tumor models

PT-112 is a novel platinum-pyrophosphate conjugate under clinical development for cancer therapy. PT-112 mediates cytostatic and cytotoxic effects against a variety of human and mouse cancer cell lines in vitro. The cytotoxic response to PT-112 is associated with the emission of danger signals underpinning the initiation of anticancer immunity, including calreticulin exposure on the surface of dying cells, as well as ATP and HMGB1 secretion. Consistently, mouse cancer cells succumbing to PT-112 in vitro can be used to provide syngeneic, immunocompetent mice with immunological protection against a subsequent challenge with living tumor cells of the same type. Moreover, PT-112 administration synergizes with PD-1 or PD-L1 blockade in the control of mouse cancers in immunologically competent settings, as it simultaneously recruits immune effector cells and depletes immunosuppressive cells in the tumor microenvironment. Finally, PT-112 employed intratumorally in the context of immune checkpoint inhibition initiates a robust immune response that has systemic outreach and limits the growth of untreated, distant lesions. Thus, PT-112 induces the immunogenic demise of cancer cells, and hence stands out as a promising combinatorial partner of immune checkpoint blockers, especially for the treatment of otherwise immunologically cold tumors.

Systemic Evaluation on the Pharmacokinetics of Platinum-Based Anticancer Drugs From Animal to Cell Level: Based on Total Platinum and Intact Drugs

Cisplatin, carboplatin, and oxaliplatin are the common platinum-based anticancer drugs widely used in the chemotherapeutic treatment of solid tumors in clinic. However, the comprehensive pharmacokinetics of platinum-based anticancer drugs has not been fully understood yet. This leads to many limitations for the further studies on their pharmacology and toxicology. In this study, we conduct a systemic evaluation on the pharmacokinetics of three platinum analogues at animal and cell levels, with quantification of both total platinum and intact drugs. A detailed animal study to address and compare the different pharmacokinetic behaviors of three platinum analogues has been conducted in three biological matrices: blood, plasma, and ultrafiltrate plasma. Carboplatin showed an obviously different pharmacokinetic characteristic from cisplatin and oxaliplatin. On the one hand, carboplatin has the highest proportion of Pt distribution in ultrafiltrate plasma. On the other hand, carboplatin has the highest intact drug exposure and longest intact drug elimination time in blood, plasma, and ultrafiltrate plasma, which may explain its high hematotoxicity. Additionally, the cellular and subcellular pharmacokinetics of oxaliplatin in two colon cancer HCT-116/LOVO cell lines has been elucidated for the first time. The biotransformation of intact oxaliplatin in cells was rapid with a fast elimination, however, the generated platinum-containing metabolites still exist within cells. The distribution of total platinum in the cytosol is higher than in the mitochondria, followed by the nucleus. Enrichment of platinum in mitochondria may affect the respiratory chain or energy metabolism, and further lead to cell apoptosis, which may indicate mitochondria as another potential target for efficacy and toxicity of oxaliplatin.

Oxidation of Human Copper Chaperone Atox1 and Disulfide Bond Cleavage by Cisplatin and Glutathione

Cancer cells cope with high oxidative stress levels, characterized by a shift toward the oxidized form (GSSG) of glutathione (GSH) in the redox couple GSSG/2GSH. Under these conditions, the cytosolic copper chaperone Atox1, which delivers Cu(I) to the secretory pathway, gets oxidized, i.e., a disulfide bond is formed between the cysteine residues of the Cu(I)-binding CxxC motif. Switching to the covalently-linked form, sulfur atoms are not able to bind the Cu(I) ion and Atox1 cannot play an antioxidant role. Atox1 has also been implicated in the resistance to platinum chemotherapy. In the presence of excess GSH, the anticancer drug cisplatin binds to Cu(I)-Atox1 but not to the reduced apoprotein. With the aim to investigate the interaction of cisplatin with the disulfide form of the protein, we performed a structural characterization in solution and in the solid state of oxidized human Atox1 and explored its ability to bind cisplatin under conditions mimicking an oxidizing environment. Cisplatin targets a methionine residue of oxidized Atox1; however, in the presence of GSH as reducing agent, the drug binds irreversibly to the protein with ammine ligands trans to Cys12 and Cys15. The results are discussed with reference to the available literature data and a mechanism is proposed connecting platinum drug processing to redox and copper homeostasis.

Coexisting Molecular Determinants of Acquired Oxaliplatin Resistance in Human Colorectal and Ovarian Cancer Cell Lines

Oxaliplatin (OHP) treatment of colorectal cancer (CRC) frequently leads to resistance. OHP resistance was induced in CRC cell lines LoVo-92 and LoVo-Li and a platinum-sensitive ovarian cancer cell line, A2780, and related to cellular platinum accumulation, platinum-DNA adducts, transporter expression, DNA repair genes, gene expression arrays, and array-CGH profiling. Pulse (4 h, 4OHP) and continuous exposure (72 h, cOHP) resulted in 4.0 to 7.9-fold and 5.0 to 11.8-fold drug resistance, respectively. Cellular oxaliplatin accumulation and DNA-adduct formation were decreased and related to OCT1-3 and ATP7A expression. Gene expression profiling and pathway analysis showed significantly altered p53 signaling, xenobiotic metabolism, role of BRCA1 in DNA damage response, and aryl hydrocarbon receptor signaling pathways, were related to decreased ALDH1L2, Bax, and BBC3 (PUMA) and increased aldo-keto reductases C1 and C3. The array-CGH profiles showed focal aberrations. In conclusion, OHP resistance was correlated with total platinum accumulation and OCT1-3 expression, decreased proapoptotic, and increased anti-apoptosis and homologous repair genes.

Allantoin reduces cell death induced by cisplatin: possible implications for tumor lysis syndrome management

Massive lysis of tumor mass in cancer patients under chemotherapy regimens generates high levels of uric acid, leading to what is known as tumor lysis syndrome (TLS). Rasburicase, a recombinant urate oxidase, converts urate to allantoin, which is readily excreted by the kidneys. Even though there is a high production of allantoin from urate in cancer patients following rasburicase treatment, there are no studies on how allantoin excess could interfere with chemotherapy. We have evaluated allantoin interference with cisplatin efficiency on the lung cancer cell line H460 in vitro. The cells were treated with cisplatin (33 µM), with or without allantoin, for 48 h, in the presence or absence of UV light, and N-acetyl-L-cysteine (NAC) for 24 h. Cell viability, cell cycle, ROS production, apoptosis and immunoblot assays were performed. We showed that allantoin reduced the apoptosis induced by cisplatin in the H460 cell line. However, the activity of carboplatin and oxaliplatin, betulinic acid, TIBA, UV and H₂O₂ was not affected by allantoin. NMR spectroscopy showed that allantoin reduces cisplatin activity through direct interaction with cisplatin.

Rethinking Alkylating(-Like) Agents for Solid Tumor Management

Although old molecules, alkylating agents and platinum derivatives are still widely used in the treatment of various solid tumors. However, systemic toxicity and cellular resistance mechanisms impede their efficacy. Innovative strategies, including local administration, optimization of treatment schedule/dosage, synergistic combinations, and the encapsulation of bioactive molecules in smart, multifunctional drug delivery systems, have shown promising results in potentiating anticancer activity while circumventing such hurdles. Furthermore, questioning of the old paradigm according to which nuclear DNA is the critical target of their anticancer activity has shed light on subcellular alternative and neglected targets that obviously participate in the mediation of cytotoxicity or resistance. Thus, rethinking of the use of these pivotal antineoplastic agents appears critical to improve clinical outcomes in the management of solid tumors.

A novel screening method for transition metal-based anticancer compounds using zebrafish embryo-larval assay and inductively coupled plasma-mass spectrometry analysis

As novel metallodrugs continue to emerge, they are evaluated using models, including zebrafish, that offer unique sublethal endpoints. Testing metal-based anticancer compounds with high-throughput zebrafish toxicological assays requires analytical methods with the sensitivity to detect these sublethal tissue doses in very small sample masses (e.g., egg mass 100 μg). A robust bioanalytical model, zebrafish embryos coupled with inductively coupled plasma-mass spectrometry (ICPMS) for measurement of delivered dose, creates a very effective means for screening metal-based chemotherapeutic agents. In this study, we used ICPMS quantitation with the zebrafish embryo assays to detect metal equivalents at multiple response endpoints for two compounds, the chemotherapeutic agent cisplatin and ruthenium (Ru)-based prospective metallodrug, PMC79. We hypothesized that cisplatin and PMC79 have different mechanisms for inducing apoptosis and result in similar lesions but different potencies following water-borne exposure. An ICPMS method was developed to detect the metal in waterborne solution and tissue (detection limit: 5 parts per trillion for Ru or platinum [Pt]). The Ru-based compound was more potent (LC₅₀ : 7.8 μm) than cisplatin (LC₅₀ : 158 μm) and induced disparate lesions. Lethality from cisplatin exposure exhibited a threshold (values >15 mg/L) while no threshold was observed for delayed hatching (lowest observed adverse effect level 3.75 mg/L cisplatin; 8.7 Pt (ng)/organism). The Ru organometallic did not have a threshold for lethality. Cisplatin-induced delayed hatching was investigated further by larval-Pt distribution and preferentially distributed to the chorion. We propose that zebrafish embryo-larval assays coupled with ICPMS serve as a powerful platform to evaluate relative potency and toxic effects of metallodrug candidates.

Evaluation of the uptake, storage and cell effects of nano-iron in enterocyte-like cell models

The therapy with nanocompounds is widely used to treat Fe deficiency and an emerging trend to inhibit tumor growth. The present work aims to address the management of different FeONP, comparing sucrose covered FeONP and Fe nanoparticles in the form of the ferritin with non-particulated inorganic Fe (II) by enterocytes-like colon cancer cell lines (Caco-2 and HT-29). Iron uptake results revealed significantly higher Fe incorporation in the case of nanoparticulated Fe, first in the form of FeONP and second in the form of ferritin with respect to inorganic Fe (II). Furthermore, the intracellular Fe fractionation, conducted by size exclusion chromatography coupled on line to inductively coupled plasma mass spectrometry (SEC-ICP-MS) showed a significant increase of the Fe-ferritin peak upon exposure of cells to the following compounds ferritin > FeONP > FeSO_4. Such results point out that the sucrose coated FeONP released Fe into the cell cytosol that was used to replenish the existing cytosolic ferritin without inducing changes in the protein concentration. On the other hand, the increase of the Fe-ferritin peak in cells exposed to ferritin as iron source is due to a significant increase on the intracellular protein concentration, as proved by using an ICP-MS linked ferritin sandwich immune assay. Cell viability experiments conducted with concentrations up to 1000 μmol L^-1 (as Fe) of each compound under scrutiny did not reveal significant differences among Fe species regarding global cellular toxicity. However, significant cell DNA damage was detected when treating the cells with FeONP (500 μmol L^-1).

Cisplatin resistance in cell models: evaluation of metallomic and biological predictive biomarkers to address early therapy failure

Cisplatin, one of the most extensively used metallodrugs in cancer treatment, presents the important drawback of patient resistance. This resistance is the consequence of different processes including those preventing the formation of DNA adducts and/or their quick removal. Thus, a tool for the accurate detection and quantitation of cisplatin-induced adducts might be valuable for predicting patient resistance. To prove the validity of such an assumption, highly sensitive plasma mass spectrometry (ICP-MS) strategies were applied to determine DNA adduct levels and intracellular Pt concentrations. These two metal-relative parameters were combined with an evaluation of biological responses in terms of genomic stability (with the Comet assay) and cell cycle progression (by flow cytometry) in four human cell lines of different origins and cisplatin sensitivities (A549, GM04312, A2780 and A2780cis), treated with low cisplatin doses (5, 10 and 20 μM for 3 hours). Cell viability and apoptosis were determined as resistance indicators. Univariate linear regression analyses indicated that quantitation of cisplatin-induced G-G intra-strand adducts, measured 1 h after treatment, was the best predictor for viability and apoptosis in all of the cell lines. Multivariate linear regression analyses revealed that the prediction improved when the intracellular Pt content or the Comet data were included in the analysis, for all sensitive cell lines and for the A2780 and A2780cis cell lines, respectively. Thus, a reliable cisplatin resistance predictive model, which combines the quantitation of adducts by HPLC-ICP-MS, and their repair, with the intracellular Pt content and induced genomic instability, might be essential to identify early therapy failure.

Quantitative Evaluation of Cisplatin Uptake in Sensitive and Resistant Individual Cells by Single-Cell ICP-MS (SC-ICP-MS)

One of the main limitations to the Pt-therapy in cancer is the development of associated drug resistance that can be associated with a significant reduction of the intracellular platinum concentration. Thus, intracellular Pt concentration could be considered as a biomarker of cisplatin resistance. In this work, an alternative method to address intracellular Pt concentration in individual cells is explored to permit the evaluation of different cell models and alternative therapies in a relatively fast way. For this aim, total Pt analysis in single cells has been implemented using a total consumption nebulizer coupled to inductively coupled plasma mass spectrometric detection (ICP-MS). The efficiency of the proposed device has been evaluated in combination with flow cytometry and turned out to be around 25% (cells entering the ICP-MS from the cells in suspension). Quantitative uptake studies of a nontoxic Tb-containing compound by individual cells were conducted and the results compared to those obtained by bulk analysis of the same cells. Both sets of data were statistically comparable. Thus, final application of the developed methodology to the comparative uptake of Pt-species in cisplatin resistant and sensitive cell lines (A2780cis and A2780) was conducted. The results obtained revealed the potential of this analytical strategy to differentiate between different cell lines of different sensitivity to the drug which might be of high medical interest.

Oxidative stress, metabolomics profiling, and mechanism of local anesthetic induced cell death in yeast

The World Health Organization designates lidocaine as an essential medicine in healthcare, greatly increasing the probability of human exposure. Its use has been associated with ROS generation and neurotoxicity. Physiological and metabolomic alterations, and genetics leading to the clinically observed adverse effects have not been temporally characterized. To study alterations that may lead to these undesirable effects, Saccharomyces cerevisiae grown on aerobic carbon sources to stationary phase was assessed over 6h. Exposure of an LC50 dose of lidocaine, increased mitochondrial depolarization and ROS/RNS generation assessed using JC-1, ROS/RNS specific probes, and FACS. Intracellular calcium also increased, assessed by ICP-MS. Measurement of the relative ATP and ADP concentrations indicates an initial 3-fold depletion of ATP suggesting an alteration in the ATP:ADP ratio. At the 6h time point the lidocaine exposed population contained ATP concentrations roughly 85% that of the negative control suggesting the surviving population adapted its metabolic pathways to, at least partially restore cellular bioenergetics. Metabolite analysis indicates an increase of intermediates in the pentose phosphate pathway, the preparatory phase of glycolysis, and NADPH. Oxidative stress produced by lidocaine exposure targets aconitase decreasing its activity with an observed decrease in isocitrate and an increase citrate. Similarly, increases in α-ketoglutarate, malate, and oxaloacetate imply activation of anaplerotic reactions. Antioxidant molecule glutathione and its precursor amino acids, cysteine and glutamate were greatly increased at later time points. Phosphatidylserine externalization suggestive of early phase apoptosis was also observed. Genetic studies using metacaspase null strains showed resistance to lidocaine induced cell death. These data suggest lidocaine induces perpetual mitochondrial depolarization, ROS/RNS generation along with increased glutathione to combat the oxidative cellular environment, glycolytic to PPP cycling of carbon generating NADPH, obstruction of carbon flow through the TCA cycle, decreased ATP generation, and metacaspase dependent apoptotic cell death.

Selective speciation improves efficacy and lowers toxicity of platinum anticancer and vanadium antidiabetic drugs

Improving efficacy and lowering resistance to metal-based drugs can be addressed by consideration of the coordination complex speciation and key reactions important to vanadium antidiabetic drugs or platinum anticancer drugs under biological conditions. The methods of analyses vary depending on the specific metal ion chemistry. The vanadium compounds interconvert readily, whereas the reactions of the platinum compounds are much slower and thus much easier to study. However, the vanadium species are readily differentiated due to vanadium complexes differing in color. For both vanadium and platinum systems, understanding the processes as the compounds, Lipoplatin and Satraplatin, enter cells is needed to better combat the disease; there are many cellular metabolites, which may affect processing and thus the efficacy of the drugs. Examples of two formulations of platinum compounds illustrate how changing the chemistry of the platinum will result in less toxic and better tolerated drugs. The consequence of the much lower toxicity of the drug, can be readily realized because cisplatin administration requires hospital stay whereas Lipoplatin can be done in an outpatient manner. Similarly, the properties of Satraplatin allow for development of an oral drug. These forms of platinum demonstrate that the direct consequence of more selective speciation is lower side effects and cheaper administration of the anticancer agent. Therefore we urge that as the community goes forward in development of new drugs, control of speciation chemistry will be considered as one of the key strategies in the future development of anticancer drugs.