Preclinical activity of the repurposed drug auranofin in classical Hodgkin lymphoma

The rheumatoid arthritis drug auranofin exerts potent anti-lymphoma effect by stimulating TXNRD-mediated ROS generation and inhibition of energy metabolism

Since the survival of lymphoma patients who experience disease progression or relapse remains very poor, new therapeutic approaches and effective drugs are urgently needed. Here we show that auranofin (AF), an anti-rheumatoid drug thought to inhibit thioredoxin reductases (TXNRDs) as its mechanism of action, exhibited potent activity against multiple cancer types, especially effective against B cell lymphoma. Surprisingly, a knockdown of TXNRD1 and TXNRD2 did not cause significant cytotoxicity, suggesting that abrogation of TXNRD enzyme per se was insufficient to cause cancer cell death. Further mechanistic study showed that the interaction of AF with TXNRD could convert this antioxidant enzyme to a ROS-generating molecule via disrupting its electron transport, leading to a leak of electrons that interact with molecular oxygen to form superoxide. AF also suppressed energy metabolism by inhibiting both mitochondria complex II and the glycolytic enzyme GAPDH, leading to a significant depletion of ATP and inhibition of cancer growth in vitro and in vivo. Importantly, we found that the AF-mediated ROS stress could induce PD-L1 expression, revealing an unwanted effect of AF in causing immune suppression. We further showed that a combination of AF with anti-PD-1 antibody could enhance the anticancer activity in a syngeneic immune-competent mouse B-cell lymphoma model. Our study suggests that AF could be a potential drug for lymphoma treatment, and its combination with immune checkpoint inhibitors would be a logical strategy to increase the therapeutic activity.

Auranofin repurposing for lung and pancreatic cancer: low CA12 expression as a marker of sensitivity in patient-derived organoids, with potentiated efficacy by AKT inhibition

BACKGROUND

This study explores the repurposing of Auranofin (AF), an anti-rheumatic drug, for treating non-small cell lung cancer (NSCLC) adenocarcinoma and pancreatic ductal adenocarcinoma (PDAC). Drug repurposing in oncology offers a cost-effective and time-efficient approach to developing new cancer therapies. Our research focuses on evaluating AF's selective cytotoxicity against cancer cells, identifying RNAseq-based biomarkers to predict AF response, and finding the most effective co-therapeutic agents for combination with AF.

METHODS

Our investigation employed a comprehensive drug screening of AF in combination with eleven anticancer agents in cancerous PDAC and NSCLC patient-derived organoids (n = 7), and non-cancerous pulmonary organoids (n = 2). Additionally, we conducted RNA sequencing to identify potential biomarkers for AF sensitivity and experimented with various drug combinations to optimize AF's therapeutic efficacy.

RESULTS

The results revealed that AF demonstrates a preferential cytotoxic effect on NSCLC and PDAC cancer cells at clinically relevant concentrations below 1 µM, sparing normal epithelial cells. We identified Carbonic Anhydrase 12 (CA12) as a significant RNAseq-based biomarker, closely associated with the NF-κB survival signaling pathway, which is crucial in cancer cell response to oxidative stress. Our findings suggest that cancer cells with low CA12 expression are more susceptible to AF treatment. Furthermore, the combination of AF with the AKT inhibitor MK2206 was found to be particularly effective, exhibiting potent and selective cytotoxic synergy, especially in tumor organoid models classified as intermediate responders to AF, without adverse effects on healthy organoids.

CONCLUSION

Our research offers valuable insights into the use of AF for treating NSCLC and PDAC. It highlights AF's cancer cell selectivity, establishes CA12 as a predictive biomarker for AF sensitivity, and underscores the enhanced efficacy of AF when combined with MK2206 and other therapeutics. These findings pave the way for further exploration of AF in cancer treatment, particularly in identifying patient populations most likely to benefit from its use and in optimizing combination therapies for improved patient outcomes.

Dinuclear gold(I) complexes based on carbene and diphosphane ligands: bis[2-(dicyclohexylphosphano)ethyl]amine complex inhibits the proteasome activity, decreases stem cell markers and spheroid viability in lung cancer cells

Three new dinuclear gold(I) complexes (1-3) containing a carbene (1,3-Bis(2,6-di-isopropylphenyl)imidazol-2-ylidene (IPr)) and diphosphane ligands [bis(1,2-diphenylphosphano)ethane (Dppe), bis(1,3-diphenylphosphano)propane (Dppp) and bis[2-(dicyclohexylphosphano)ethyl]amine (DCyPA)], were synthesized and characterized by elemental analysis and, ESI-MS, mid FT-IR and NMR spectroscopic methods. The structures of complexes 2 and 3 were determined by X-ray crystallography, which revealed that the complexes are dinuclear having gold(I) ions linearly coordinated. The anticancer activities of the complexes (1-3) were evaluated in lung (A549), breast (MC-F7), prostate (PC-3), osteosarcoma (MG-63) and ovarian (A2780 and A2780cis) cancer models. Growth inhibition by the new complexes was higher than cisplatin in all cell lines tested. The mechanism of action of complex 3 was investigated in A549 cells using 2-dimensional (2D) models and 3D-multicellular tumor spheroids. Treatment of A549 cells with complex 3 caused: the induction of apoptosis and the generation of reactive oxygen species; the cell cycle arrest in the G0/G1 phase; the inhibition of both the proteasome and the NF-kB activity; the down-regulation of lung cancer stem cell markers (NOTCH1, CD133, ALDH1 and CD44). Complex 3 was more active than cisplatin also in 3D models of A549 lung cancer cells.

The Medium Obtained from the Culture of Hodgkin Lymphoma Cells Affects the Biophysical Characteristics of a Fibroblast Cell Model

The neoplastic Hodgkin-Reed-Sternberg (HRS) cells in Hodgkin lymphoma (HL) represent only 1-10% of cells and are surrounded by an inflammatory microenvironment. The HL cytokine network is a key point for the proliferation of HRS cells and for the maintenance of an advantageous microenvironment for HRS survival. In the tumor microenvironment (TME), the fibroblasts are involved in crosstalk with HRS cells. The aim of this work was to study the effect of lymphoma cell conditioned medium on a fibroblast cell population and evaluate modifications of cell morphology and proliferation. Hodgkin lymphoma-derived medium was used to obtain a population of "conditioned" fibroblasts (WS-1 COND). Differences in biophysical parameters were detected by the innovative device Celector^®. Fibroblast-HL cells interactions were reproduced in 3D co-culture spheroids. WS-1 COND showed a different cellular morphology with an enlarged cytoplasm and enhanced metabolism. Area and diameter cell values obtained by Celector^® measurement were increased. Co-culture spheroids created with WS-1 COND showed a tighter aggregation than those with non-conditioned WS-1. The presence of soluble factors derived from HRS cells in the conditioned medium was adequate for the proliferation of fibroblasts and conditioned fibroblasts in a 3D HL model allowed to develop a representative model of the in vivo TME.

Omics-based identification of an NRF2-related auranofin resistance signature in cancer: Insights into drug repurposing

Auranofin is a thioredoxin reductase-1 inhibitor originally approved for the treatment of rheumatoid arthritis. Recently, auranofin has been repurposed as an anticancer drug, with pharmacological activity reported in multiple cancer types. In this study, we characterized transcriptional and genetic alterations associated with auranofin response in cancer. By integrating data from an auranofin cytotoxicity screen with transcriptome profiling of lung cancer cell lines, we identified an auranofin resistance signature comprising 29 genes, most of which are classical targets of the transcription factor NRF2, such as genes involved in glutathione metabolism (GCLC, GSR, SLC7A11) and thioredoxin system (TXN, TXNRD1). Pan-cancer analysis revealed that mutations in NRF2 pathway genes, namely KEAP1 and NFE2L2, are strongly associated with overexpression of the auranofin resistance gene set. By clustering cancer types based on auranofin resistance signature expression, hepatocellular carcinoma, and a subset of non-small cell lung cancer, head-neck squamous cell carcinoma, and esophageal cancer carrying NFE2L2/KEAP1 mutations were predicted resistant, whereas leukemia, lymphoma, and multiple myeloma were predicted sensitive to auranofin. Cell viability assays in a panel of 20 cancer cell lines confirmed the augmented sensitivity of hematological cancers to auranofin; an effect associated with dependence upon glutathione and decreased expression of NRF2 target genes involved in GSH synthesis and recycling (GCLC, GCLM and GSR) in these cancer types. In summary, the omics-based identification of sensitive/resistant cancers and genetic alterations associated with these phenotypes may guide an appropriate repurposing of auranofin in cancer therapy.

Drug Resistance: The Role of Exosomal miRNA in the Microenvironment of Hematopoietic Tumors

Extracellular vesicles (EVs), including exosomes, have an important role thanks to their ability to communicate and exchange information between tumor cells and the tumor microenvironment (TME), and have also been associated with communicating anti-cancer drug resistance (DR). The increase in proliferation of cancer cells alters oxygen levels, which causes hypoxia and results in a release of exosomes by the cancer cells. In this review, the results of studies examining the role of exosomal miRNA in DR, and their mechanism, are discussed in detail in hematological tumors: leukemia, lymphoma, and multiple myeloma. In conclusion, we underline the exosome's function as a possible drug delivery vehicle by understanding its cargo. Engineered exosomes can be used to be more specific for personalized therapy.

Optimization of the Solvent and In Vivo Administration Route of Auranofin in a Syngeneic Non-Small Cell Lung Cancer and Glioblastoma Mouse Model

The antineoplastic activity of the thioredoxin reductase 1 (TrxR) inhibitor, auranofin (AF), has already been investigated in various cancer mouse models as a single drug, or in combination with other molecules. However, there are inconsistencies in the literature on the solvent, dose and administration route of AF treatment in vivo. Therefore, we investigated the solvent and administration route of AF in a syngeneic SB28 glioblastoma (GBM) C57BL/6J and a 344SQ non-small cell lung cancer 129S2/SvPasCrl (129) mouse model. Compared to daily intraperitoneal injections and subcutaneous delivery of AF via osmotic minipumps, oral gavage for 14 days was the most suitable administration route for high doses of AF (10-15 mg/kg) in both mouse models, showing no measurable weight loss or signs of toxicity. A solvent comprising 50% DMSO, 40% PEG300 and 10% ethanol improved the solubility of AF for oral administration in mice. In addition, we confirmed that AF was a potent TrxR inhibitor in SB28 GBM tumors at high doses. Taken together, our results and results in the literature indicate the therapeutic value of AF in several in vivo cancer models, and provide relevant information about AF's optimal administration route and solvent in two syngeneic cancer mouse models.

Developing Bi-Gold Compound BGC2a to Target Mitochondria for the Elimination of Cancer Cells

Reactive oxygen species (ROS) homeostasis and mitochondrial metabolism are critical for the survival of cancer cells, including cancer stem cells (CSCs), which often cause drug resistance and cancer relapse. Auranofin is a mono-gold anti-rheumatic drug, and it has been repurposed as an anticancer agent working by the induction of both ROS increase and mitochondrial dysfunction. Hypothetically, increasing auranofin’s positive charges via incorporating more gold atoms to enhance its mitochondria-targeting capacity could enhance its anti-cancer efficacy. Hence, in this work, both mono-gold and bi-gold compounds were designed and evaluated to test our hypothesis. The results showed that bi-gold compounds generally suppressed cancer cells proliferation better than their mono-gold counterparts. The most potent compound, BGC2a, substantially inhibited the antioxidant enzyme TrxR and increased the cellular ROS. BGC2a induced cell apoptosis, which could not be reversed by the antioxidant agent vitamin C, implying that the ROS induced by TrxR inhibition might not be the decisive cause of cell death. As expected, a significant proportion of BGC2a accumulated within mitochondria, likely contributing to mitochondrial dysfunction, which was further confirmed by measuring oxygen consumption rate, mitochondrial membrane potential, and ATP production. Moreover, BGC2a inhibited colony formation and reduced stem-like side population (SP) cells of A549. Finally, the compound effectively suppressed the tumor growth of both A549 and PANC-1 xenografts. Our study showed that mitochondrial disturbance may be gold-based compounds’ major lethal factor in eradicating cancer cells, providing a new approach to developing potent gold-based anti-cancer drugs by increasing mitochondria-targeting capacity.

Ferroptosis and Autoimmune Diseases

Adequate control of autoimmune diseases with an unclear etiology resulting from autoreactivation of the immune system remains a major challenge. One of the factors that trigger autoimmunity is the abnormal induction of cell death and the inadequate clearance of dead cells that leads to the exposure or release of intracellular contents that activate the immune system. Different from other cell death subtypes, such as apoptosis, necroptosis, autophagy, and pyroptosis, ferroptosis has a unique association with the cellular iron load (but not the loads of other metals) and preserves its distinguishable morphological, biological, and genetic features. This review addresses how ferroptosis is initiated and how it contributes to the pathogenesis of autoimmune diseases, including systemic lupus erythematosus, rheumatoid arthritis, and inflammatory bowel diseases. The mechanisms responsible for ferroptosis-associated events are discussed. We also cover the perspective of targeting ferroptosis as a potential therapeutic for patients with autoimmune diseases. Collectively, this review provides up-to-date knowledge regarding how ferroptosis occurs and its significance in autoimmune diseases.

Current and Emerging Approaches to Study Microenvironmental Interactions and Drug Activity in Classical Hodgkin Lymphoma

Simple Summary

In classical Hodgkin Lymphoma (cHL), the tumor microenvironment (TME) plays an important role in tumor progression and treatment response, making its evaluation critical for determining prognosis, treatment strategies and predicting an increase in drug toxicity. Therefore, there is a need to utilize more complex systems to study the cHL-TME and its interplay with tumor cells. To evaluate new anticancer drugs and to find the mechanisms of drug resistance, this review summarizes emerging approaches for the analysis of the TME composition and to identify the state of the disease; the in vitro techniques used to determine the mechanisms involved in the building of an immunosuppressive and protective TME; new 3-dimensional (3D) models, the heterospheroids (HS), developed to mimic TME interactions. Here, we describe the present and likely future clinical applications indicated by the results of these studies and propose a classification for the in vitro culture methods used to study TME interactions in cHL.

Abstract

Classic Hodgkin lymphoma is characterized by a few tumor cells surrounded by a protective and immunosuppressive tumor microenvironment (TME) composed by a wide variety of noncancerous cells that are an active part of the disease. Therefore, new techniques to study the cHL-TME and new therapeutic strategies targeting specifically tumor cells, reactivating the antitumor immunity, counteracting the protective effects of the TME, were developed. Here, we describe new methods used to study the cell composition, the phenotype, and the spatial distribution of Hodgkin and Reed–Sternberg (HRS) cells and of noncancerous cells in tumor tissues. Moreover, we propose a classification, with increasing complexity, of the in vitro functional studies used to clarify the interactions leading not only to HRS cell survival, growth and drug resistance, but also to the immunosuppressive tumor education of monocytes, T lymphocytes and fibroblasts. This classification also includes new 3-dimensional (3D) models, obtained by cultivating HRS cells in extracellular matrix scaffolds or in sponge scaffolds, under non-adherent conditions with noncancerous cells to form heterospheroids (HS), implanted in developing chick eggs (ovo model). We report results obtained with these approaches and their applications in clinical setting.

A Novel Cyclic Dinuclear Gold(I) Complex Induces Anticancer Activity via Oxidative Stress-Mediated Intrinsic Apoptotic Pathway in MDA-MB-231 Cancer Cells

A new dinuclear cyclic gold(I) complex [Au2(DCyPA)2](PF6)2, 1 based on bis[2-(dicyclohexylphosphano)ethyl]amine (DCyPA) has been synthesized and characterized by elemental analysis, IR and NMR spectroscopies, and X-ray crystallography. In the dinuclear...

Novel dinuclear gold(i) complexes containing bis(diphenylphosphano)alkanes and (biphenyl-2-yl)(di-tert-butyl)phosphane: synthesis, structural characterization and anticancer activity

Four novel dinuclear phosphanegold(I) complexes containing bis(diphenylphosphano)alkanes and related phosphano alkanes were synthesized and characterized by elemental analysis, FTIR, NMR spectroscopy, and X-ray crystallography.

Upgrade of an old drug: Auranofin in innovative cancer therapies to overcome drug resistance and to increase drug effectiveness

Auranofin is an oral gold(I) compound, initially developed for the treatment of rheumatoid arthritis. Currently, Auranofin is under investigation for oncological application within a drug repurposing plan due to the relevant antineoplastic activity observed both in vitro and in vivo tumor models. In this review, we analysed studies in which Auranofin was used as a single drug or in combination with other molecules to enhance their anticancer activity or to overcome chemoresistance. The analysis of different targets/pathways affected by this drug in different cancer types has allowed us to highlight several interesting targets and effects of Auranofin besides the already well-known inhibition of thioredoxin reductase. Among these targets, inhibitory-κB kinase, deubiquitinates, protein kinase C iota have been frequently suggested. To rationalize the effects of Auranofin by a system biology-like approach, we exploited transcriptomic data obtained from a wide range of cell models, extrapolating the data deposited in the Connectivity Maps website and we attempted to provide a general conclusion and discussed the major points that need further investigation.

Analogs of a Natural Peptaibol Exert Anticancer Activity in Both Cisplatin- and Doxorubicin-Resistant Cells and in Multicellular Tumor Spheroids

Peptaibols, by disturbing the permeability of phospholipid membranes, can overcome anticancer drug resistance, but their natural hydrophobicity hampers their administration. By a green peptide synthesis protocol, we produced two water-soluble analogs of the peptaibol trichogin GA IV, termed K6-Lol and K6-NH2. To reduce production costs, we successfully explored the possibility of changing the naturally occurring 1,2-aminoalcohol leucinol to a C-terminal amide. Peptaibol activity was evaluated in ovarian cancer (OvCa) and Hodgkin lymphoma (HL) cell lines. Peptaibols exerted comparable cytotoxic effects in cancer cell lines that were sensitive—and had acquired resistance—to cisplatin and doxorubicin, as well as in the extrinsic-drug-resistant OvCa 3-dimensional spheroids. Peptaibols, rapidly taken up by tumor cells, deeply penetrated and killed OvCa-spheroids. They led to cell membrane permeabilization and phosphatidylserine exposure and were taken up faster by cancer cells than normal cells. They were resistant to proteolysis and maintained a stable helical structure in the presence of cancer cells. In conclusion, these promising results strongly point out the need for further preclinical evaluation of our peptaibols as new anticancer agents.

The Molecular Mechanisms of Regulating Oxidative Stress-Induced Ferroptosis and Therapeutic Strategy in Tumors

Ferroptosis is an atypical form of regulated cell death, which is different from apoptosis, necrosis, pyroptosis, and autophagy. Ferroptosis is characterized by iron-dependent oxidative destruction of cellular membranes following the antioxidant system's failure. The sensitivity of ferroptosis is tightly regulated by a series of biological processes, the metabolism of iron, amino acids, and polyunsaturated fatty acids, and the interaction of glutathione (GSH), NADPH, coenzyme Q10 (CoQ10), and phospholipids. Elevated oxidative stress (ROS) level is a hallmark of cancer, and ferroptosis serves as a link between nutrition metabolism and redox biology. Targeting ferroptosis may be an effective and selective way for cancer therapy. The underlying molecular mechanism of ferroptosis occurrence is still not enough. This review will briefly summarize the process of ferroptosis and introduce critical molecules in the ferroptotic cascade. Furthermore, we reviewed the occurrence and regulation of reduction-oxidation (redox) for ferroptosis in cancer metabolism. The role of the tumor suppressor and the epigenetic regulator in tumor cell ferroptosis will also be described. Finally, old drugs that can be repurposed to induce ferroptosis will be characterized, aiming for drug repurposing and novel drug combinations for cancer therapy more efficiently and economically.

Angiogenesis in Lymph Nodes Is a Critical Regulator of Immune Response and Lymphoma Growth

Tumor-induced remodeling of the microenvironment in lymph nodes (LNs) includes the formation of blood vessels, which goes beyond the regulation of metabolism, and shaping a survival niche for tumor cells. In contrast to solid tumors, which primarily rely on neo-angiogenesis, hematopoietic malignancies usually grow within pre-vascularized autochthonous niches in secondary lymphatic organs or the bone marrow. The mechanisms of vascular remodeling in expanding LNs during infection-induced responses have been studied in more detail; in contrast, insights into the conditions of lymphoma growth and lodging remain enigmatic. Based on previous murine studies and clinical trials in human, we conclude that there is not a universal LN-specific angiogenic program applicable. Instead, signaling pathways that are tightly connected to autochthonous and infiltrating cell types contribute variably to LN vascular expansion. Inflammation related angiogenesis within LNs relies on dendritic cell derived pro-inflammatory cytokines stimulating vascular endothelial growth factor-A (VEGF-A) expression in fibroblastic reticular cells, which in turn triggers vessel growth. In high-grade B cell lymphoma, angiogenesis correlates with poor prognosis. Lymphoma cells immigrate and grow in LNs and provide pro-angiogenic growth factors themselves. In contrast to infectious stimuli that impact on LN vasculature, they do not trigger the typical inflammatory and hypoxia-related stroma-remodeling cascade. Blood vessels in LNs are unique in selective recruitment of lymphocytes via high endothelial venules (HEVs). The dissemination routes of neoplastic lymphocytes are usually disease stage dependent. Early seeding via the blood stream requires the expression of the homeostatic chemokine receptor CCR7 and of L-selectin, both cooperate to facilitate transmigration of tumor and also of protective tumor-reactive lymphocytes via HEV structures. In this view, the HEV route is not only relevant for lymphoma cell homing, but also for a continuous immunosurveillance. We envision that HEV functional and structural alterations during lymphomagenesis are not only key to vascular remodeling, but also impact on tumor cell accessibility when targeted by T cell-mediated immunotherapies.

Auranofin mitigates systemic iron overload and induces ferroptosis via distinct mechanisms

Iron homeostasis is essential for health; moreover, hepcidin-deficiency results in iron overload in both hereditary hemochromatosis and iron-loading anemia. Here, we identified iron modulators by functionally screening hepcidin agonists using a library of 640 FDA-approved drugs in human hepatic Huh7 cells. We validated the results in C57BL/6J mice and a mouse model of hemochromatosis (Hfe^−/− mice). Our screen revealed that the anti-rheumatoid arthritis drug auranofin (AUR) potently upregulates hepcidin expression. Interestingly, we found that canonical signaling pathways that regulate iron, including the Bmp/Smad and IL-6/Jak2/Stat3 pathways, play indispensable roles in mediating AUR’s effects. In addition, AUR induces IL-6 via the NF-κB pathway. In C57BL/6J mice, acute treatment with 5 mg/kg AUR activated hepatic IL-6/hepcidin signaling and decreased serum iron and transferrin saturation. Whereas chronically treating male Hfe^−/− mice with 5 mg/kg AUR activated hepatic IL-6/hepcidin signaling, decreasing systemic iron overload, but less effective in females. Further analyses revealed that estrogen reduced the ability of AUR to induce IL-6/hepcidin signaling in Huh7 cells, providing a mechanistic explanation for ineffectiveness of AUR in female Hfe^−/− mice. Notably, high-dose AUR (25 mg/kg) induces ferroptosis and causes lipid peroxidation through inhibition of thioredoxin reductase (TXNRD) activity. We demonstrate the ferroptosis inhibitor ferrostatin significantly protects liver toxicity induced by high-dose AUR without comprising its beneficial effect on iron metabolism. In conclusion, our findings provide compelling evidence that TXNRD is a key regulator of ferroptosis, and AUR is a novel activator of hepcidin and ferroptosis via distinct mechanisms, suggesting a promising approach for treating hemochromatosis and hepcidin-deficiency related disorders.

Conjugation of a gold(iii) complex with vitamin B1 and chlorambucil derivatives: anticancer evaluation and mechanistic insights

A gold(iii) complex containing vitamin B1 and chlorambucil derivatives was investigated for mechanistic insights in colon and breast cancer treatment.

Antineoplastic effects of auranofin in human pancreatic adenocarcinoma preclinical models

Background

Auranofin, a Food and Drug Administration–approved anti-rheumatic agent with anticancer properties for lung and ovarian cancer, has never been studied for pancreatic cancer. We hypothesize that auranofin may prevent pancreatic ductal adenocarcinoma progression by inhibition of Txnrd1 and HIF-1α.

Methods

In vitro sensitivity of human pancreatic ductal adenocarcinoma cell lines was determined based on IC50. Western blot assays were used to interrogate mechanisms of apoptosis and resistance. Ex vivo live tissue slice assays of xenografts allowed for testing of a larger number of PDX samples with high efficiency. In vivo pancreatic ductal adenocarcinoma orthotopic mouse models using MiaPaCa-2 Luc + cells were designed to determine optimal dose and antitumor effect.

Results

We found that 10 of 15 tested pancreatic ductal adenocarcinoma cell lines were sensitive to auranofin based on IC50s below 5 μmol/L. Ex vivo tissue growth inhibition greater than 44% was observed for 13 PDX tissue cases treated with 10 μmol/L auranofin. High Txnrd1 expression was observed for resistant cell lines. In vivo studies showed 15 mg/kg IP as the optimal dose with absence of gross solid organ metastasis up to 13 weeks post-treatment (median survival 8 and 12 weeks, respectively; P = .0953).

Conclusions

We have demonstrated that auranofin prevents pancreatic ductal adenocarcinoma progression using multiple models. Our study suggests inhibition of Txnrd1 and HIF-1α as possible mechanisms of action, and Txnrd1 as a biomarker of resistance. Based on these data, an off-label Phase 0 clinical trial with this FDA-approved drug should be considered for patients with pancreatic cancer.

Formation of the Immunosuppressive Microenvironment of Classic Hodgkin Lymphoma and Therapeutic Approaches to Counter It

Classic Hodgkin lymphoma (cHL) is characterized by a few tumor cells surrounded by a protective, immunosuppressive tumor microenvironment composed of normal cells that are an active part of the disease. Hodgkin and Reed-Sternberg (HRS) cells evade the immune system through a variety of different mechanisms. They evade antitumor effector T cells and natural killer cells and promote T cell exhaustion. Using cytokines and extracellular vesicles, they recruit normal cells, induce their proliferation and "educate" (i.e. reprogram) them to become immunosuppressive and protumorigenic. Therefore, alternative treatment strategies are being developed to target not only tumor cells but also the tumor microenvironment. Here we summarize current knowledge on the ability of HRS cells to build their microenvironment and to educate normal cells to become immunosuppressive. We also describe therapeutic strategies to counteract formation of the tumor microenvironment and related processes leading to T cell exhaustion and repolarization of immunosuppressive tumor-associated macrophages.

Potent In Vitro and In Vivo Anticancer Activity of New Bipyridine and Bipyrimidine Gold (III) Dithiocarbamate Derivatives

We synthesized eight new bipyridine and bipyrimidine gold (III) dithiocarbamate-containing complexes (C1-C8) and tested them in a panel of human cancer cell lines. We used osteosarcoma (MG-63), lung (A549), prostate (PC3 and DU145), breast (MCF-7), ovarian (A2780 and A2780cis, cisplatin- and doxorubicin-resistant), and cervical (ME-180 and R-ME-180, cisplatin resistant) cancer cell lines. We found that C2, C3, C6, and C7 were more cytotoxic than cisplatin in all cell lines tested and overcame cisplatin and doxorubicin resistance in A2780cis and R-ME-180 cells. In the PC3 prostate cancer cell line, the gold (III) complex C6 ([Au₂(BPM)(DMDTC)₂]Cl₄) induced apoptosis and double-stranded DNA breaks, modified cell cycle phases, increased Reactive Oxigen Species (ROS) generation, and reduced thioredoxin reductase and proteasome activities. It inhibited PC3 cell migration and was more cytotoxic against PC3 cells than normal human adipose-derived stromal cells. In mice bearing PC3 tumor xenografts, C6 reduced tumor growth by more than 70% without causing weight loss. Altogether, our results demonstrate the anticancer activity of these new gold (III) complexes and support the potential of C6 as a new agent for prostate cancer treatment.

Inhibition of thioredoxin-dependent H2O2 removal sensitizes malignant B-cells to pharmacological ascorbate

L-ascorbate (L-ASC) is a widely-known dietary nutrient which holds promising potential in cancer therapy when given parenterally at high doses. The anticancer effects of L-ASC involve its autoxidation and generation of H₂O₂, which is selectively toxic to malignant cells. Here we present that thioredoxin antioxidant system plays a key role in the scavenging of extracellularly-generated H₂O₂ in malignant B-cells. We show that inhibition of peroxiredoxin 1, the enzyme that removes H₂O₂ in a thioredoxin system-dependent manner, increases the sensitivity of malignant B-cells to L-ASC. Moreover, we demonstrate that auranofin (AUR), the inhibitor of the thioredoxin system that is used as an antirheumatic drug, diminishes the H₂O₂-scavenging capacity of malignant B-cells and potentiates pharmacological ascorbate anticancer activity in vitro and in vivo. The addition of AUR to L-ASC-treated cells triggers the accumulation of H₂O₂ in the cells, which results in iron-dependent cytotoxicity. Importantly, the synergistic effects are observed at as low as 200 µM L-ASC concentrations. In conclusion, we observed strong, synergistic, cancer-selective interaction between L-ASC and auranofin. Since both of these agents are available in clinical practice, our findings support further investigations of the efficacy of pharmacological ascorbate in combination with auranofin in preclinical and clinical settings.

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Lack of peroxiredoxin 1 potentiates antileukemic activity of L-ascorbate in vitro and in vivo.

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Auranofin and L-ascorbate synergistically kill malignant B cells.

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Auranofin leads to intracellular accumulation of H₂O₂ generated by L-ascorbate.

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Auranofin and L-ascorbate trigger iron-dependent oxidative damage and cytotoxicity.

CCR5 antagonism by maraviroc inhibits Hodgkin lymphoma microenvironment interactions and xenograft growth

Classic Hodgkin lymphoma tumor cells express a functional CCR5 receptor, and tumor tissues express high CCL5 levels, suggesting that CCL5-CCR5 signaling is involved in tumor-microenvironment formation and tumor growth. Using the CCR5 antagonist, maraviroc, and a neutralizing anti-CCL5 antibody, we found that CCL5 secreted by classic Hodgkin lymphoma cells recruited mesenchymal stromal cells and monocytes. The “education” of mesenchymal stromal cells by tumor cell-conditioned medium enhanced mesenchymal stromal cells’ proliferation and CCL5 secretion. In turn, educated mesenchymal stromal cell-conditioned medium increased the clonogenic growth of tumor cells and monocyte migration, but these effects were reduced by maraviroc. Monocyte education by tumor cell-conditioned medium induced their growth and reprogrammed them towards immunosuppressive tumor-associated macrophages that expressed IDO and PD-L1 and secreted IL-10, CCL17 and TGF-β. Educated monocyte-conditioned medium slowed the growth of phytohemagglutinin-activated lymphocytes. Maraviroc decreased tumor cell growth and synergized with doxorubicin and brentuximab vedotin. A three-dimensional heterospheroid assay showed that maraviroc counteracted both the formation and viability of heterospheroids generated by co-cultivation of tumor cells with mesenchymal stromal cells and monocytes. In mice bearing tumor cell xenografts, maraviroc reduced tumor growth by more than 50% and inhibited monocyte accumulation, without weight loss. Finally, in classic Hodgkin lymphoma human tumor tissues, CCL5 and CD68 expression correlated positively, and patients with high CCL5 levels had poor prognosis. In conclusion, since the present challenges are to find molecules counteracting the formation of the immunosuppressive tumor microenvironment or new, less toxic drug combinations, the repurposed drug maraviroc may represent a new opportunity for classic Hodgkin lym phoma treatment.

Reactions of Auranofin and Its Pseudohalide Derivatives with Serum Albumin Investigated through ESI-Q-TOF MS

The reactions of auranofin and three pseudohalide derivatives with bovine serum albumin were explored by ESI-Q-TOF mass spectrometry; a detailed molecular description of the resulting adducts is achieved revealing even subtle differences in reactivity within this series of gold(I) complexes. Our study shows that this kind of investigative approach, formerly applied to the interactions of metal-based drugs with small model proteins of MW 10-15 kDa, e.g., cytochrome c and lysozyme, may now be extended with success to far larger proteins such as serum albumin (MW 66 kDa).

Inhibition of the CCL5/CCR5 Axis against the Progression of Gastric Cancer

Despite the progress made in molecular and clinical research, patients with advanced-stage gastric cancer (GC) have a bad prognosis and very low survival rates. Furthermore, it is challenging to find the complex molecular mechanisms that are involved in the development of GC, its progression, and its resistance to therapy. The interactions of chemokines, also known as chemotactic cytokines, with their receptors regulate immune and inflammatory responses. However, updated research demonstrates that cancer cells subvert the normal chemokine role, transforming them into fundamental constituents of the tumor microenvironment (TME) with tumor-promoting effects. C-C chemokine ligand 5 (CCL5) is a chemotactic cytokine, and its expression and secretion are regulated in T cells. C-C chemokine receptor type 5 (CCR5) is expressed in T cells, macrophages, other leukocytes, and certain types of cancer cells. The interaction between CCL5 and CCR5 plays an active role in recruiting leukocytes into target sites. This review summarizes recent information on the role of the CCL5 chemokine and its receptor CCR5 in GC cell proliferation, metastasis formation, and in the building of an immunosuppressive TME. Moreover, it highlights the development of new therapeutic strategies to inhibit the CCL5/CCR5 axis in different ways and their possible clinical relevance in the treatment of GC.

Comparative oncology approach to drug repurposing in osteosarcoma

BACKGROUND

Osteosarcoma is an orphan disease for which little improvement in survival has been made since the late 1980s. New drug discovery for orphan diseases is limited by the cost and time it takes to develop new drugs. Repurposing already approved FDA-drugs can help overcome this limitation. Another limitation of cancer drug discovery is the lack of preclinical models that accurately recapitulate what occurs in humans. For OS using dogs as a model can minimize this limitation as OS in canines develops spontaneously, is locally invasive and metastasizes to the lungs as it does in humans.

METHODS

In our present work we used high-throughput screens to identify drugs from a library of 2,286 FDA-approved drugs that demonstrated selective growth inhibition against both human and canine OS cell lines. The identified lead compound was then tested for synergy with 7 other drugs that have demonstrated activity against OS. These results were confirmed with in vitro assays and an in vivo murine model of OS.

RESULTS

We identified 13 drugs that demonstrated selective growth inhibition against both human and canine OS cell lines. Auranofin was selected for further in vitro combination drug screens. Auranofin showed synergistic effects with vorinostat and rapamycin on OS viability and apoptosis induction. Auranofin demonstrated single-agent growth inhibition in both human and canine OS xenografts, and cooperative growth inhibition was observed in combination with rapamycin or vorinostat. There was a significant decrease in Ki67-positive cells and an increase in cleaved caspase-3 levels in tumor tissues treated with a combination of auranofin and vorinostat or rapamycin.

CONCLUSIONS

Auranofin, alone or in combination with rapamycin or vorinostat, may be useful new treatment strategies for OS. Future studies may evaluate the efficacy of auranofin in dogs with OS as a prelude to human clinical evaluation.

New bipyridine gold(III) dithiocarbamate-containing complexes exerted a potent anticancer activity against cisplatin-resistant cancer cells independent of p53 status

We synthesized, characterized and tested in a panel of cancer cell lines, nine new bipyridine gold(III) dithiocarbamate-containing complexes. In vitro studies demonstrated that compounds 1, 2, 4, 5, 7 and 8 were the most cytotoxic in prostate, breast, ovarian cancer cell lines and in Hodgkin lymphoma cells with IC₅₀ values lower than the reference drug cisplatin. The most active compound 1 was more active than cisplatin in ovarian (A2780cis and 2780CP-16) and breast cancer cisplatin-resistant cells. Compound 1 determined an alteration of the cellular redox homeostasis leading to increased ROS levels, a decrease in the mitochondrial membrane potential, cytochrome-c release from the mitochondria and activation of caspases 9 and 3. The ROS scavenger NAC suppressed ROS generation and rescued cells from damage. Compound 1 resulted more active in tumor cells than in normal human Mesenchymal stromal cells. Gold compounds were active independent of p53 status: exerted cytotoxic effects on a panel of non-small cell lung cancer cell lines with different p53 status and in the ovarian A2780 model where the p53 was knocked out. In conclusion, these promising results strongly indicate the need for further preclinical evaluation to test the clinical potential of these new gold(III) complexes.

Selection and characterization of a human ovarian cancer cell line resistant to auranofin

The anti-arthritic drug auranofin exerts also potent antitumour activity in in vitro and in vivo models, whose mechanisms are not yet well defined. From an auranofin-sensitive human ovarian cancer cell line A2780, a highly resistant (>20-fold) subline (A2780/AF-R) was developed and characterized. Marked reduction of gold accumulation occurred in auranofin-resistant A2780 cells. Also, moderately higher thioredoxin reductase activity in A2780/AF-R cells was observed while no changes in intracellular glutathione content occurred. Resistance to auranofin was associated with a low level of cross-resistance to some investigational gold compounds as well as to oxaliplatin and other anticancer drugs with different mode of action (i.e. melphalan, vinblastine, doxorubicin, etoposide, and paclitaxel). Reduced gold accumulation was associated to substantial gene expression changes in various influx (e.g. SLC22A1, SLC47A1, SLCO1B1) and efflux (e.g. ABCB1, ABCC2, ABCC3) transporters. The expression levels of selected proteins (i.e. SLC22A1, SLC47A1, P-gp) were also changed accordingly. These data provide evidence that multiple drug transporters may act as mediators of transport of auranofin and other gold compounds in cancer cells. Further investigation into the molecular mechanisms mediating transport of auranofin and new gold complexes in view of their potential clinical application in the treatment of cancer is warranted.

New insights into redox homeostasis as a therapeutic target in B-cell malignancies

Purpose of review

The goal of this review is to summarize recent advances in our understanding of the regulation of redox homeostasis and the subtype-specific role of antioxidant enzymes in B-cell-derived malignancies. Furthermore, it presents selected prooxidative therapeutic strategies against B-cell neoplasms.

Recent findings

Recent reports have shown that the disturbed redox homeostasis in B-cell malignancies is regulated by cancer-specific signaling pathways and therefore varies between the individual subtypes. For instance, in a subtype of diffuse large B-cell lymphoma with increased oxidative phosphorylation, elevated reactive oxygen species are accompanied by higher levels of thioredoxin and glutathione and inhibition of either of these systems is selectively toxic to this subtype. In addition, growing number of small molecule inhibitors targeting antioxidant enzymes, such as auranofin, SK053, adenanthin, or decreasing glutathione level, such as imexon, buthionine sulfoximine, and L-cysteinase, trigger specific cytotoxic effects against B-cell malignancies. Lastly, attention is drawn to recent reports of effective treatment modalities involving prooxidative agents and interfering with redox homeostasis provided by stromal cells.

Summary

Recent findings reveal important differences in redox homeostasis within the distinct subsets of B-cell-derived malignancies that can be therapeutically exploited to improve existing treatment and to overcome drug resistance.

Dual targeting of the thioredoxin and glutathione systems in cancer and HIV

Although the use of antioxidants for the treatment of cancer and HIV/AIDS has been proposed for decades, new insights gained from redox research have suggested a very different scenario. These new data show that the major cellular antioxidant systems, the thioredoxin (Trx) and glutathione (GSH) systems, actually promote cancer growth and HIV infection, while suppressing an effective immune response. Mechanistically, these systems control both the redox- and NO-based pathways (nitroso-redox homeostasis), which subserve innate and cellular immune defenses. Dual inhibition of the Trx and GSH systems synergistically kills neoplastic cells in vitro and in mice and decreases resistance to anticancer therapy. Similarly, the population of HIV reservoir cells that constitutes the major barrier to a cure for AIDS is exquisitely redox sensitive and could be selectively targeted by Trx and GSH inhibitors. Trx and GSH inhibition may lead to a reprogramming of the immune response, tilting the balance between the immune system and cancer or HIV in favor of the former, allowing elimination of diseased cells. Thus, therapies based on silencing of the Trx and GSH pathways represent a promising approach for the cure of both cancer and AIDS and warrant further investigation.

CD137 signaling in Hodgkin and Reed-Sternberg cell lines induces IL-13 secretion, immune deviation and enhanced growth

CD137 and its ligand, CD137L, are expressed on activated T cells and antigen-presenting cells (APC), respectively, and are powerful inducers of cellular, type 1 immune responses. CD137 is ectopically expressed by Hodgkin and Reed-Sternberg (HRS) cells, the malignant cells in Hodgkin lymphoma (HL). Here we report that CD137 transmits signals into HRS cells, which induce the secretion of IL-13. IL-13 in conditioned supernatants of HRS cell lines inhibits the secretion of IFNγ by peripheral blood mononuclear cells (PBMC). Since IFNγ is essential for the development of a type 1 immune response, CD137-induced IL-13 secretion facilitates escape from immune surveillance. Further, CD137-induced IL-13 enhances the growth of HRS cell lines. CD137, IL-13 double-positive cells could be detected in the majority (58%) of HL patient samples, providing clinical evidence for a role of IL-13 induction by CD137 during HL pathogenesis. This study validates CD137 as a candidate target for immunotherapy of HL.