Auranofin-mediated inhibition of PI3K/AKT/mTOR axis and anticancer activity in non-small cell lung cancer cells

The rheumatoid arthritis drug Auranofin targets peroxiredoxin 1 and peroxiredoxin 2 to trigger ROS-endoplasmic reticulum stress axis-mediated cell death and cytoprotective autophagy

Auranofin (AF) is a gold-based compound and it has been used in the treatment of rheumatoid arthritis for over four decades. Recently, it has been demonstrated to show significant antitumor activity across various cancer types and is being repurposed as an anticancer drug. However, the precise mechanisms underlying its antitumor effects, particularly its binding targets, remain poorly understood. Here, we demonstrate that Auranofin (AF) exerts cytotoxic effects in 786-O renal cancer cells via inducing apoptosis. Mechanistic studies reveal that AF induces reactive oxygen species (ROS) accumulation, which is a key factor in mediating AF-induced stress and subsequently apoptosis. Notably, both ROS and ER stress induce autophagy, and inhibition of autophagy further enhances AF-induced cytotoxicity. Interestingly, activity-based protein profiling (ABPP) analysis identifies two key antioxidant enzymes, peroxiredoxin 1 (PRDX1) and peroxiredoxin 2 (PRDX2), as direct binding targets of AF. Importantly, overexpression of PRDX1 or PRDX2 inhibits AF-induced ROS accumulation and subsequent apoptosis. Overall, our findings demonstrate that AF induces apoptosis by covalently binding to PRDX1/2 to inhibit its activity, leading to ROS accumulation, which triggers ER stress and apoptosis. At the same time, ER stress triggers a cytoprotective autophagic response. These findings provide novel insights into the mechanism of AF-induced cytotoxicity and suggest PRDX1/2 as critical targets for the development of anti-renal cancer therapies.

Antibacterial and anticancer properties of Solanum mauritianum fruit components analyzed using LC-QTOF-MS/MS

This study evaluated the antibacterial and anticancer properties of S. mauritianum fruit components through LC-QTOF-MS/MS metabolomic profiling. The samples were extracted, and the antibacterial activity was conducted using a standard Resazurin microtiter assay. The minimum inhibitory concentrations (MICs) of the crude extracts were evaluated against reference pathogenic bacterial isolates. The anticancer activity of the extracts was tested against U-87 MG glioblastoma and A549 lung carcinoma cells (ATCC cancer cell lines). The real-time toxicity assay and comprehensive metabolomic profiling were evaluated for the crude extracts. Results revealed that the ripe fruit coat exhibited the richest chemical diversity, with 15 unique metabolites, while the unripe fruit had 5. Detailed classification of the identified metabolites showed that alkaloids accounted for 33.3%, followed by terpenoids (21.2%). The extracts of the fruit components had significant antibacterial activity against the referenced pathogens of public health importance. Extracts from the ripe fruit coat demonstrated significant cytotoxicity on U-87 MG glioblastoma cell viability, suggesting potential anticancer activity, while the effect on A549 lung carcinoma cells showed high viability across all treatments. The real-time cytotoxicity assays further highlighted the dose-dependent inhibition of glioblastoma cells by crude extracts from the ripe fruit coat, emphasizing its therapeutic potential.

Searching for New Gold(I)-Based Complexes as Anticancer and/or Antiviral Agents

Approaches capable of simultaneously treating cancer and protecting susceptible patients from lethal infections are highly desirable, although they prove challenging. Taking inspiration from the well-known anticancer platinum complexes, successive studies about the complexation of organic compounds with other late transition metals, such as silver, gold, palladium, rhodium, ruthenium, iridium, and osmium, have led to remarkable anticancer activities. Among the numerous chemical moieties studied, N-heterocyclic carbenes (NHCs) have revealed very attractive activities due to their favorable chemical properties. Specifically, gold-NHC complexes emerged as some of the most active complexes acting as antitumor agents. On the other hand, some recent studies have highlighted the involvement of these complexes in antiviral research as well. The well-known gold-based, orally available complex auranofin approved by the Food and Drug Administration (FDA) for the treatment of rheumatoid arthritis has been suggested as a repositioned drug for both cancer and viral infections. In the era of the COVID-19 pandemic, the most interesting goal could be the discovery of gold-NHC complexes as dual antiviral and anticancer agents. In this review, the most recent studies regarding the anticancer and antiviral activities of gold(I)-NHC complexes will be analyzed and discussed, offering an interesting insight into the research in this field.

Inhibition of Thioredoxin-Reductase by Auranofin as a Pro-Oxidant Anticancer Strategy for Glioblastoma: In Vitro and In Vivo Studies

Reactive oxygen species (ROS) play a key role in cancer progression and antitumor therapy. Glioblastoma is a highly heterogeneous tumor with different cell populations exhibiting various redox statuses. Elevated ROS levels in cancer cells promote tumor growth and simultaneously make them more sensitive to anticancer drugs, but further elevation leads to cell death and apoptosis. Meanwhile, various subsets of tumor cells, such a glioblastoma stem cells (GSC) or the cells in tumor microenvironment (TME), demonstrate adaptive mechanisms to excessive ROS production by developing effective antioxidant systems such as glutathione- and thioredoxin-dependent. GSCs demonstrate higher chemoresistance and lower ROS levels than other glioma cells, while TME cells create a pro-oxidative environment and have immunosuppressive effects. Both subpopulations have become an attractive target for developing therapies. Increased expression of thioredoxin reductase (TrxR) is often associated with tumor progression and poor patient survival. Various TrxR inhibitors have been investigated as potential anticancer therapies, including nitrosoureas, flavonoids and metallic complexes. Gold derivatives are irreversible inhibitors of TrxR. Among them, auranofin (AF), a selective TrxR inhibitor, has proven its effectiveness as a drug for the treatment of rheumatoid arthritis and its efficacy as an anticancer agent has been demonstrated in preclinical studies in vitro and in vivo. However, further clinical application of AF could be challenging due to the low solubility and insufficient delivery to glioblastoma. Different delivery strategies for hydrophobic drugs could be used to increase the concentration of AF in the brain. Combining different therapeutic approaches that affect the redox status of various glioma cell populations could become a new strategy for treating brain tumor diseases.

Bioactivity and metabolic profiling of crude extracts from endophytic bacteria linked to Solanum mauritianum scope: Discovery of antibacterial and anticancer properties

Bacterial endophytes associated with Solanum mauritianum Scop. represent a promising source of novel bioactive compounds with potential antibacterial and anticancer properties. This study aimed to investigate the diversity, distribution, and bioactivity of crude extracts derived from endophytic bacteria, focusing on their effects against bacterial pathogens of public health relevance and two cancer cell lines. Fresh, healthy plant samples were collected, and endophytes were isolated using standard cultural techniques. Identification of the endophytes was carried out through conventional and molecular methods. The comprehensive profiling and characterization of crude secondary metabolites were conducted using Liquid Chromatography-Quadrupole Time-of-Flight Mass Spectrometry (LC-QTOF-MS/MS) and Gas Chromatography-High Resolution Time-of-Flight Mass Spectrometry (GC-HRTOF-MS). The antibacterial activity and minimum inhibitory concentration were evaluated for the secondary metabolites using the Resazurin Microtitre assay. The anticancer activity of the metabolites was evaluated against A549 Lung carcinoma cells and U87MG Glioblastoma cells (ATCC culture cell lines). The result revealed a diversity of bacterial endophytes, including Pantoea species, Luteibacter sp. Bacillus safensis, Arthrobacter sp., and Bacillus licheniformis. These endophytes displayed distinct-tissue-specific distribution patterns within S. mauritianum. Metabolic profiling of three endophytes (P. ananatis, B. licheniformis, and Arthrobacter sp.) revealed 14 common and numerous unique metabolites. The crude secondary metabolites exhibited broad-spectrum antibacterial activity against reference strains of Bacillus cereus, Pseudomonas aeruginosa, and Staphylococcus epidermidis, where MICs as low as 0.125 mg/ml were recorded across several secondary metabolites of Pantoea ananatis, Bacillus licheniformis, and Arthrobacter sp. The cytotoxicity assays on UMG87 glioblastoma and A549 lung carcinoma cells revealed that the secondary metabolites did not induce cell death but instead promoted cell proliferation with different viability rates. While this proliferative effect limits their direct application as anticancer agents, it raises intriguing possibilities for their role in tissue regeneration or repair. This study provides critical insights into the microbial diversity of S. mauritianum and underscores the potential of its endophytic bacteria as sources of bioactive compounds with diverse biotechnological applications.

Functional utility of gold complexes with phosphorus donor ligands in biological systems

Metallo-phosphines are ubiquitous in organometallic chemistry with widespread applications as catalysts in various chemical transformations, precursors for organic electronics, and chemotherapeutic agents or chemical probes. Here, we provide a comprehensive review of the exploration of the current biological applications of Au complexes bearing phosphine donor ligands. The goal is to deepen our understanding of the synthetic utility and reactivity of Au-phosphine complexes to provide insights that could lead to the design of new molecules and enhance the cross-application or repurposing of these complexes.

Second-Generation Antipsychotics Induce Metabolic Disruption in Adipose Tissue-Derived Mesenchymal Stem Cells Through an aPKC-Dependent Pathway

Metabolic syndrome (MetS) is a cluster of metabolic abnormalities, including visceral obesity, dyslipidemia, and insulin resistance. In this regard, visceral white adipose tissue (vWAT) plays a critical role, influencing energy metabolism, immunomodulation, and oxidative stress. Adipose-derived stem cells (ADSCs) are key players in these processes within vWAT. While second-generation antipsychotics (SGAs) have significantly improved treatments for mental health disorders, their chronic use is associated with an increased risk of MetS. In this study, we explored the impact of SGAs on ADSCs to better understand their role in MetS and identify potential therapeutic targets. Our findings reveal that olanzapine disrupts lipid droplet formation during adipogenic differentiation, impairing insulin receptor endocytosis, turnover, and signaling. SGAs also alter the endolysosomal compartment, leading to acidic vesicle accumulation and increased lysosomal biogenesis through TFEB activation. PKCζ is crucial for the SGA-induced nuclear translocation of TFEB and acidic vesicle formation. Notably, inhibiting PKCζ restored insulin receptor tyrosine phosphorylation, normalized receptor turnover, and improved downstream signaling following olanzapine treatment. This activation of PKCζ by olanzapine is driven by increased phosphatidic acid synthesis via phospholipase D (PLD), following G protein-coupled receptor (GPCR) signaling activation. Overall, olanzapine and clozapine disrupt endolysosomal homeostasis and insulin signaling in a PKCζ-dependent manner. These findings highlight SGAs as valuable tools for uncovering cellular dysfunction in vWAT during MetS and may guide the development of new therapeutic strategies to mitigate the metabolic side effects of these drugs.

Auranofin Suppresses the Growth of Canine Mammary Tumour Cells and Induces Apoptosis via the PI3K/AKT Pathway

Canine mammary gland tumour (CMT) is the most common spontaneous tumour in intact female dogs and often exhibits metastases. Auranofin (AF) is a gold complex used for treating rheumatism. The excellent anti-tumour ability of AF has been demonstrated in various types of human and canine tumours. In this study, five CMT cell lines (CIPp, CMT-7364, CHMp, CIPm and CTBp) and three CMT primary cells (G7894, L1883 and L6783) were used to explore the anti-tumour effect of AF on CMT. Two CMT cell lines (CIPp and CMT-7364) were used to search the underlying mechanism of the effect of AF on CMT. The results showed that AF inhibited the growth, migration, invasion, and colony formation abilities of CMT cells. Additionally, the growth of CMT in a 3D cell culture model was effectively suppressed by AF. Furthermore, AF induced cell apoptosis of CMT cells via the PI3K/AKT pathway. In conclusion, AF effectively induces CMT apoptosis by regulating the PI3K/AKT pathway, indicating that AF should be explored as a potential CMT treatment in future studies.

A new herbal extract carbon nanodot nanomedicine for anti-renal cell carcinoma through the PI3K/AKT signaling pathway

New Re carbon nanodots with narrow size distribution, good water solubility and high cell membrane permeability were prepared from a herbal extract. They exhibited high inhibitory effects on renal cancer A498 cells and renal cell carcinoma. They could stimulate the production of ROS, induce mitochondrial dysfunction, and accelerate the release of intracellular calcium ions in the A498 cells. Transcriptomic tests were performed on A498 cells after administration, and the results were analyzed by qPCR and immunofluorescence. The results suggested that the Re carbon nanodots could downregulate the abnormally activated PI3K/AKT signaling pathway and perform cell cycle arrest in the S phase along with the inhibition of cell proliferation. Finally, in conjunction with the abnormal mitochondrial function, the Re carbon nanodots could ultimately promote the apoptosis of the A498 cells. In vivo tumor-bearing mouse experiments further showed that the Re carbon nanodots had a strong inhibitory effect on xenograft kidney cancer tumors. The prepared Re carbon nanodots have good anti-renal cancer A498 cell and renal cell carcinoma bioactivity and are expected to be a potential drug for the treatment of kidney cancer with low toxicity and high safety.

Targeting USP14/UCHL5: A Breakthrough Approach to Overcoming Treatment-Resistant FLT3-ITD-Positive AML

FMS-like tyrosine kinase 3 (FLT3) internal tandem duplication (ITD) mutations in acute myeloid leukemia (AML) are associated with poor prognosis and therapy resistance. This study aimed to demonstrate that inhibiting the deubiquitinating enzymes ubiquitin-specific peptidase 14 (USP14) and ubiquitin C-terminal hydrolase L5 (UCHL5) (USP14/UCHL5) with b-AP15 or the organogold compound auranofin (AUR) induces apoptosis in the ITD-transformed human leukemia cell line MV4-11 and mononuclear leukocytes derived from patients with FLT3-ITD-positive AML. This study included patients diagnosed with AML at Tokyo Medical and Dental University Hospital between January 2018 and July 2024. Both treatments blocked downstream FLT3 pathway events, with the effects potentiated by USP14 knockdown. Both treatments inhibited FLT3 deubiquitination via K48 and disrupted translation initiation via 4EBP1, a downstream FLT3 target. FLT3 was downregulated in the leukemic cells, with the associated activation of stress-related MAP kinase pathways and increased NF-E2-related factor 2. Furthermore, the overexpression of B-cell lymphoma-extra-large and myeloid cell leukemia-1 prevented the cell death caused by b-AP15 and AUR. These results suggest that inhibiting USP14/UCHL5, which involves multiple regulatory mechanisms, is a promising target for novel therapies for treatment-resistant FLT3-ITD-positive AML.

Repurposing auranofin and meclofenamic acid as energy-metabolism inhibitors and anti-cancer drugs

OBJECTIVE

Cytotoxicity of the antirheumatic drug auranofin (Aur) and the non-steroidal anti-inflammatory drug meclofenamic acid (MA) on several cancer cell lines and isolated mitochondria was examined to assess whether these drugs behave as oxidative phosphorylation inhibitors.

METHODS

The effect of Aur or MA for 24 h was assayed on metastatic cancer and non-cancer cell proliferation, energy metabolism, mitophagy and metastasis; as well as on oxygen consumption rates of cancer and non-cancer mitochondria.

RESULTS

Aur doses in the low micromolar range were required to decrease proliferation of metastatic HeLa and MDA-MB-231 cells, whereas one or two orders of magnitude higher levels were required to affect proliferation of non-cancer cells. MA doses required to affect cancer cell growth were one order of magnitude higher than those of Aur. At the same doses, Aur impaired oxidative phosphorylation in isolated mitochondria and intact cells through mitophagy induction, as well as glycolysis. Consequently, cell migration and invasiveness were severely affected. The combination of Aur with very low cisplatin concentrations promoted that the effects on cellular functions were potentiated.

CONCLUSION

Aur surges as a highly promising anticancer drug, suggesting that efforts to establish this drug in the clinical treatment protocols are warranted and worthy to undertake.

Targeting the redox vulnerability of acute myeloid leukaemia cells with a combination of auranofin and vitamin C

Acute myeloid leukaemia (AML) is a heterogeneous disease characterized by complex molecular and cytogenetic abnormalities. Pro-oxidant cellular redox status is a common hallmark of AML cells, providing a rationale for redox-based anticancer strategy. We previously discovered that auranofin (AUF), initially used for the treatment of rheumatoid arthritis and repositioned for its anticancer activity, can synergize with a pharmacological concentration of vitamin C (VC) against breast cancer cell line models. In this study, we observed that this drug combination synergistically and efficiently killed cells of leukaemic cell lines established from different myeloid subtypes. In addition to an induced elevation of reactive oxygen species and ATP depletion, a rapid dephosphorylation of 4E-BP1 and p70S6K, together with a strong inhibition of protein synthesis were early events in response to AUF/VC treatment, suggesting their implication in AUF/VC-induced cytotoxicity. Importantly, a study on 22 primary AML specimens from various AML subtypes showed that AUF/VC combinations at pharmacologically achievable concentrations were effective to eradicate primary leukaemic CD34+ cells from the majority of these samples, while being less toxic to normal cord blood CD34+ cells. Our findings indicate that targeting the redox vulnerability of AML with AUF/VC combinations could present a potential anti-AML therapeutic approach.

High-throughput Screening for Cushing Disease: Therapeutic Potential of Thiostrepton via Cell Cycle Regulation

Cushing disease is a life-threatening disorder caused by autonomous secretion of ACTH from pituitary neuroendocrine tumors (PitNETs). Few drugs are indicated for inoperative Cushing disease, in particular that due to aggressive PitNETs. To explore agents that regulate ACTH-secreting PitNETs, we conducted high-throughput screening (HTS) using AtT-20, a murine pituitary tumor cell line characterized by ACTH secretion. For the HTS, we constructed a live cell-based ACTH reporter assay for high-throughput evaluation of ACTH changes. This assay was based on HEK293T cells overexpressing components of the ACTH receptor and a fluorescent cAMP biosensor, with high-throughput acquisition of fluorescence images. We treated AtT-20 cells with compounds and assessed ACTH concentrations in the conditioned media using the reporter assay. Of 2480 screened bioactive compounds, over 50% inhibition of ACTH secreted from AtT-20 cells was seen with 84 compounds at 10 μM and 20 compounds at 1 μM. Among these hit compounds, we focused on thiostrepton (TS) and determined its antitumor effects in both in vitro and in vivo xenograft models of Cushing disease. Transcriptome and flow cytometry analyses revealed that TS administration induced AtT-20 cell cycle arrest at the G2/M phase, which was mediated by FOXM1-independent mechanisms including downregulation of cyclins. Simultaneous TS administration with a cyclin-dependent kinase 4/6 inhibitor that affected the cell cycle at the G0/1 phase showed cooperative antitumor effects. Thus, TS is a promising therapeutic agent for Cushing disease. Our list of hit compounds and new mechanistic insights into TS effects serve as a valuable foundation for future research.

Strategies for the design of analogs of auranofin endowed with anticancer potential

INTRODUCTION

Auranofin (AF) is a well-established, FDA-approved, antiarthritic gold drug that is currently being reevaluated for a variety of therapeutic indications through drug repurposing. AF has shown great promise as a potential anticancer agent and has been approved for a few clinical trials in cancer. The renewed interest in AF has led to extensive research into the design, preparation and biological evaluation of auranofin analogs, which may have an even better pharmacological profile than the parent drug.

AREAS COVERED

This article reviews the strategies for chemical modification of the AF scaffold. Several auranofin analogs have been prepared and characterized for medical application in the field of cancer treatment over the last 20 years. Some emerging structure-function relationships are proposed and discussed.

EXPERT OPINION

The chemical modification of the AF scaffold has been the subject of intense activity in recent years and this strategy has led to the preparation and evaluation of several AF analogs. The case of iodauranofin is a particularly promising example. The availability of homogeneous biological data for a group of AF derivatives allows some initial structure-function relationships to be proposed, which may inspire the design and synthesis of new and better AF analogs for cancer treatment.

Pro-Oxidant Auranofin and Glutathione-Depleting Combination Unveils Synergistic Lethality in Glioblastoma Cells with Aberrant Epidermal Growth Factor Receptor Expression

Glioblastoma (GBM) is the most prevalent and advanced malignant primary brain tumor in adults. GBM frequently harbors epidermal growth factor receptor (EGFR) wild-type (EGFRwt) gene amplification and/or EGFRvIII activating mutation. EGFR-driven GBM relies on the thioredoxin (Trx) and/or glutathione (GSH) antioxidant systems to withstand the excessive production of reactive oxygen species (ROS). The impact of EGFRwt or EGFRvIII overexpression on the response to a Trx/GSH co-targeting strategy is unknown. In this study, we investigated Trx/GSH co-targeting in the context of EGFR overexpression in GBM. Auranofin is a thioredoxin reductase (TrxR) inhibitor, FDA-approved for rheumatoid arthritis. L-buthionine-sulfoximine (L-BSO) inhibits GSH synthesis by targeting the glutamate-cysteine ligase catalytic (GCLC) enzyme subunit. We analyzed the mechanisms of cytotoxicity of auranofin and the interaction between auranofin and L-BSO in U87MG, U87/EGFRwt, and U87/EGFRvIII GBM isogenic GBM cell lines. ROS-dependent effects were assessed using the antioxidant N-acetylsteine. We show that auranofin decreased TrxR1 activity and increased ROS. Auranofin decreased cell vitality and colony formation and increased protein polyubiquitination through ROS-dependent mechanisms, suggesting the role of ROS in auranofin-induced cytotoxicity in the three cell lines. ROS-dependent PARP-1 cleavage was associated with EGFRvIII downregulation in U87/EGFRvIII cells. Remarkably, the auranofin and L-BSO combination induced the significant depletion of intracellular GSH and synergistic cytotoxicity regardless of EGFR overexpression. Nevertheless, molecular mechanisms associated with cytotoxicity were modulated to a different extent among the three cell lines. U87/EGFRvIII exhibited the most prominent ROS increase, P-AKT(Ser-473), and AKT decrease along with drastic EGFRvIII downregulation. U87/EGFRwt and U87/EGFRvIII displayed lower basal intracellular GSH levels and synergistic ROS-dependent DNA damage compared to U87MG cells. Our study provides evidence for ROS-dependent synergistic cytotoxicity of auranofin and L-BSO combination in GBM in vitro. Unraveling the sensitivity of EGFR-overexpressing cells to auranofin alone, and synergistic auranofin and L-BSO combination, supports the rationale to repurpose this promising pro-oxidant treatment strategy in GBM.

Synergistic targeting of TrxR1 and ATM/AKT pathway in human colon cancer cells

Thioredoxin reductase 1 (TrxR1) has emerged as a promising target for cancer therapy. In our previous research, we discovered several new TrxR1 inhibitors and found that they all have excellent anti-tumor activity. At the same time, we found these TrxR1 inhibitors all lead to an increase in AKT phosphorylation in cancer cells, but the detailed role of AKT phosphorylation in TrxR1 inhibitor-mediated cell death remains unclear. In this study, we identified the combination of AKT and TrxR1 inhibitor displayed a strong synergistic effect in colon cancer cells. Furthermore, we demonstrated that the synergistic effect of auranofin (TrxR1 inhibitor) and MK-2206 (AKT inhibitor) was caused by ROS accumulation. Importantly, we found that ATM inhibitor KU-55933 can block the increase of AKT phosphorylation caused by auranofin, and exhibited a synergistic effect with auranofin. Taken together, our study demonstrated that the activation of ATM/AKT pathway is a compensatory mechanism to cope with ROS accumulation induced by TrxR1 inhibitor, and synergistic targeting of TrxR1 and ATM/AKT pathway is a promising strategy for treating colon cancer.

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.

Advances in the regulatory mechanisms of mTOR in necroptosis

The mammalian target of rapamycin (mTOR), an evolutionarily highly conserved serine/threonine protein kinase, plays a prominent role in controlling gene expression, metabolism, and cell death. Programmed cell death (PCD) is indispensable for maintaining homeostasis by removing senescent, defective, or malignant cells. Necroptosis, a type of PCD, relies on the interplay between receptor-interacting serine-threonine kinases (RIPKs) and the membrane perforation by mixed lineage kinase domain-like protein (MLKL), which is distinguished from apoptosis. With the development of necroptosis-regulating mechanisms, the importance of mTOR in the complex network of intersecting signaling pathways that govern the process has become more evident. mTOR is directly responsible for the regulation of RIPKs. Autophagy is an indirect mechanism by which mTOR regulates the removal and interaction of RIPKs. Another necroptosis trigger is reactive oxygen species (ROS) produced by oxidative stress; mTOR regulates necroptosis by exploiting ROS. Considering the intricacy of the signal network, it is reasonable to assume that mTOR exerts a bifacial effect on necroptosis. However, additional research is necessary to elucidate the underlying mechanisms. In this review, we summarized the mechanisms underlying mTOR activation and necroptosis and highlighted the signaling pathway through which mTOR regulates necroptosis. The development of therapeutic targets for various diseases has been greatly advanced by the expanding knowledge of how mTOR regulates necroptosis.

Saeed H, del Solar V, López-Hernández JE, Michel A, Mathew J, Lewis JS, Contel M. Shifting the Antibody-Drug Conjugate Paradigm: A Trastuzumab-Gold-Based Conjugate Demonstrates High Efficacy against Human Epidermal Growth Factor Receptor 2-Positive Breast Cancer Mouse Model

Antibody-drug conjugates (ADCs) combine the selectivity of monoclonal antibodies (mAbs) with the efficacy of chemotherapeutics to target cancers without toxicity to normal tissue. Clinically, most chemotherapeutic ADCs are based on complex organic molecules, while the conjugation of metallodrugs to mAbs has been overlooked, despite the resurgent interest in metal-based drugs as cancer chemotherapeutics. In 2019, we described the first gold ADCs containing gold-triphenylphosphane fragments as a proof of concept. The ADCs (based on the antibody trastuzumab) were selective and highly active against HER2-positive breast cancer cells. In this study, we developed site-specific ADCs (Thio-1b and Thio-2b) using the cysteine-engineered trastuzumab derivative THIOMAB antibody technology with gold(I)-containing phosphanes and a maleimide-based linker amenable to bioconjugation (1b and 2b). In addition, we developed lysine-directed ADCs with gold payloads based on phosphanes and N-heterocyclic carbenes featuring an activated ester moiety (2c and 5c) with trastuzumab (Tras-2c and Tras-5c) and another anti-HER2 antibody, pertuzumab (Per-2c and Per-5c). Both sets of ADCs demonstrated significant anticancer potency in vitro assays. Based on these results, one ADC (Tras-2c), containing the [Au(PEt3)] fragment present in FDA-approved auranofin, was selected for an in vivo antitumor efficacy study. Immunocompromised mice xenografted with the HER2-positive human cancer cell line SKBR-3 exhibited almost complete tumor reduction and low toxicity with intravenous administration of Tras-2c. With this highly selective targeting system, we demonstrated that a subnanomolar cytotoxicity profile in cells is not required for an impressive antitumor effect in a mouse xenograft model.

Arsenic exposure and increased C-reactive protein are independently associated with lower erythrocyte glutathione peroxidase activity in Bangladeshi children

Toxic metal contaminants present in food and water have widespread effects on health and disease. Chalcophiles, such as arsenic, cadmium, and mercury, show a high affinity to selenium and exposure to these metals could have a modulating effect on enzymes dependent on selenocysteine in their active sites. The aim of this study was to assess the influence of these metals on the activity of the selenoprotein glutathione peroxidase 1 (GPX1) in erythrocytes of 100 children residing in rural Bangladesh, where drinking water often contains arsenic. GPX1 expression, as measured using high-throughput immunoblotting, showed little correlation with GPX activity (rs = 0.02, p = 0.87) in blood samples. Toxic metals and selenium measured in erythrocytes using inductively coupled plasma mass spectrometry (ICP-MS) and C-reactive protein (CRP) measured in plasma, were all considered as effectors of this divergence in GPX enzymatic activity. Arsenic concentrations in erythrocytes were most influential for GPX1 activity (rs = -0.395, p < 0.0001), and CRP levels also negatively impacted GPX1 activity (rs = -0.443, p < 0.0001). These effects appear independent of each other as arsenic concentrations and CRP showed no correlation (rs = 0.124, p = 0.2204). Erythrocyte selenium, cadmium, and mercury did not show any correlation with GPX1 activity, nor with CRP or arsenic. Our findings suggest that childhood exposure to inorganic arsenic, as well as inflammation triggering the release of CRP, may negatively affect GPX1 activity in erythrocytes.

Next Generation Gold Drugs and Probes: Chemistry and Biomedical Applications

The gold drugs, gold sodium thiomalate (Myocrisin), aurothioglucose (Solganal), and the orally administered auranofin (Ridaura), are utilized in modern medicine for the treatment of inflammatory arthritis including rheumatoid and juvenile arthritis; however, new gold agents have been slow to enter the clinic. Repurposing of auranofin in different disease indications such as cancer, parasitic, and microbial infections in the clinic has provided impetus for the development of new gold complexes for biomedical applications based on unique mechanistic insights differentiated from auranofin. Various chemical methods for the preparation of physiologically stable gold complexes and associated mechanisms have been explored in biomedicine such as therapeutics or chemical probes. In this Review, we discuss the chemistry of next generation gold drugs, which encompasses oxidation states, geometry, ligands, coordination, and organometallic compounds for infectious diseases, cancer, inflammation, and as tools for chemical biology via gold-protein interactions. We will focus on the development of gold agents in biomedicine within the past decade. The Review provides readers with an accessible overview of the utility, development, and mechanism of action of gold-based small molecules to establish context and basis for the thriving resurgence of gold in medicine.

Auranofin Synergizes with the PARP Inhibitor Olaparib to Induce ROS-Mediated Cell Death in Mutant p53 Cancers

Auranofin (AF) is a potent, off-patent thioredoxin reductase (TrxR) inhibitor that efficiently targets cancer via reactive oxygen species (ROS)- and DNA damage-mediated cell death. The goal of this study is to enhance the efficacy of AF as a cancer treatment by combining it with the poly(ADP-ribose) polymerase-1 (PARP) inhibitor olaparib (referred to as ‘aurola’). Firstly, we investigated whether mutant p53 can sensitize non-small cell lung cancer (NSCLC) and pancreatic ductal adenocarcinoma (PDAC) cancer cells to AF and olaparib treatment in p53 knock-in and knock-out models with varying p53 protein expression levels. Secondly, we determined the therapeutic range for synergistic cytotoxicity between AF and olaparib and elucidated the underlying molecular cell death mechanisms. Lastly, we evaluated the effectiveness of the combination strategy in a murine 344SQ 3D spheroid and syngeneic in vivo lung cancer model. We demonstrated that high concentrations of AF and olaparib synergistically induced cytotoxicity in NSCLC and PDAC cell lines with low levels of mutant p53 protein that were initially more resistant to AF. The aurola combination also led to the highest accumulation of ROS, which resulted in ROS-dependent cytotoxicity of mutant p53 NSCLC cells through distinct types of cell death, including caspase-3/7-dependent apoptosis, inhibited by Z-VAD-FMK, and lipid peroxidation-dependent ferroptosis, inhibited by ferrostatin-1 and alpha-tocopherol. High concentrations of both compounds were also needed to obtain a synergistic cytotoxic effect in 3D spheroids of the murine lung adenocarcinoma cell line 344SQ, which was interestingly absent in 2D. This cell line was used in a syngeneic mouse model in which the oral administration of aurola significantly delayed the growth of mutant p53 344SQ tumors in 129S2/SvPasCrl mice, while either agent alone had no effect. In addition, RNA sequencing results revealed that AF- and aurola-treated 344SQ tumors were negatively enriched for immune-related gene sets, which is in accordance with AF’s anti-inflammatory function as an anti-rheumatic drug. Only 344SQ tumors treated with aurola showed the downregulation of genes related to the cell cycle, potentially explaining the growth inhibitory effect of aurola since no apoptosis-related gene sets were enriched. Overall, this novel combination strategy of oxidative stress induction (AF) with PARP inhibition (olaparib) could be a promising treatment for mutant p53 cancers, although high concentrations of both compounds need to be reached to obtain a substantial cytotoxic effect.

Antitumor effect of melatonin on breast cancer in experimental models: A systematic review

Breast cancer is the most frequent malignant neoplasm in females. While conventional treatments such as chemotherapy and radiotherapy are available, they are highly invasive and toxic to oncological patients. Melatonin is a promising molecule for the treatment of breast cancer with antitumor effects on tumorigenesis and tumor progression. The aim of this systematic review was to synthesize knowledge about the antitumor effect of melatonin on breast cancer in experimental models and propose the main mechanisms of action already described in relation to the processes regulated by melatonin. PubMed, Web of Science, and Embase databases were used. The inclusion criteria were in vitro and in vivo experimental studies that used different formulations of melatonin as a treatment for breast cancer, without year or language restrictions. Risk of bias for studies was assessed using the Systematic Review Center for Laboratory Animal Experimentation (SYRCLE) tool. Data from selected articles were presented as narrative descriptions and tables. Seventy-five articles on different breast cancer cell lines and experimental models treated with melatonin alone, or in combination with other compounds were included. Melatonin showed antitumor effects on proliferative pathways related to the cell cycle and tumorigenesis, tumor death, angiogenesis, and tumor metastasis, as well as on oxidative stress and immune regulatory pathways. These effects were either dependent or independent of melatonin receptors. Herein, we clarify the antitumor action of melatonin on different tumorigenic processes in breast cancer in experimental models. Systematic review registration: PROSPERO database (CRD42022309822/https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022309822).

Increasing Stress to Induce Apoptosis in Pancreatic Cancer via the Unfolded Protein Response (UPR)

High rates of cell proliferation and protein synthesis in pancreatic cancer are among many factors leading to endoplasmic reticulum (ER) stress. To restore cellular homeostasis, the unfolded protein response (UPR) activates as an adaptive mechanism through either the IRE1α, PERK, or ATF6 pathways to reduce the translational load and process unfolded proteins, thus enabling tumor cells to proliferate. Under severe and prolonged ER stress, however, the UPR may promote adaptation, senescence, or apoptosis under these same pathways if homeostasis is not restored. In this review, we present evidence that high levels of ER stress and UPR activation are present in pancreatic cancer. We detail the mechanisms by which compounds activate one or many of the three arms of the UPR and effectuate downstream apoptosis and examine available data on the pre-clinical and clinical-phase ER stress inducers with the potential for anti-tumor efficacy in pancreatic cancer. Finally, we hypothesize a potential new approach to targeting pancreatic cancer by increasing levels of ER stress and UPR activation to incite apoptotic cell death.

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.

The Impact of Oxidative Stress and AKT Pathway on Cancer Cell Functions and Its Application to Natural Products

Oxidative stress and AKT serine-threonine kinase (AKT) are responsible for regulating several cell functions of cancer cells. Several natural products modulate both oxidative stress and AKT for anticancer effects. However, the impact of natural product-modulating oxidative stress and AKT on cell functions lacks systemic understanding. Notably, the contribution of regulating cell functions by AKT downstream effectors is not yet well integrated. This review explores the role of oxidative stress and AKT pathway (AKT/AKT effectors) on ten cell functions, including apoptosis, autophagy, endoplasmic reticulum stress, mitochondrial morphogenesis, ferroptosis, necroptosis, DNA damage response, senescence, migration, and cell-cycle progression. The impact of oxidative stress and AKT are connected to these cell functions through cell function mediators. Moreover, the AKT effectors related to cell functions are integrated. Based on this rationale, natural products with the modulating abilities for oxidative stress and AKT pathway exhibit the potential to regulate these cell functions, but some were rarely reported, particularly for AKT effectors. This review sheds light on understanding the roles of oxidative stress and AKT pathway in regulating cell functions, providing future directions for natural products in cancer treatment.

Anti-Cancer Effects of Auranofin in Human Lung Cancer Cells by Increasing Intracellular ROS Levels and Depleting GSH Levels

Auranofin, as a thioredoxin reductase (TrxR) inhibitor, has promising anti-cancer activity in several cancer types. However, little is known about the inhibitory effect of auranofin on lung cancer cell growth. We, therefore, investigated the antigrowth effects of auranofin in various lung cancer cells with respect to cell death, reactive oxygen species (ROS), and glutathione (GSH) levels. Treatment with 0~5 µM auranofin decreased cell proliferation and induced cell death in Calu-6, A549, SK-LU-1, NCI-H460, and NCI-H1299 lung cancer cells at 24 h. In addition, 0~5 µM auranofin increased ROS levels, including O2•−, and depleted GSH levels in these cells. N-acetyl cysteine (NAC) prevented growth inhibition and mitochondrial membrane potential (MMP, ∆Ψm) loss in 3 and 5 µM auranofin-treated Calu-6 and A549 cells at 24 h, respectively, and decreased ROS levels and GSH depletion in these cells. In contrast, L-buthionine sulfoximine (BSO) enhanced cell death, MMP (∆Ψm) loss, ROS levels, and GSH depletion in auranofin-treated Calu-6 and A549 cells. Treatment with 3 and 5 µM auranofin induced caspase-3 activation and poly (ADP ribose) polymerase (PARP) cleavage in Calu-6 and A549 cells, respectively. Both were prevented by NAC, but enhanced by BSO. Moreover, TrxR activity was reduced in auranofin-treated Calu-6 and A549 cells. That activity was decreased by BSO, but increased by NAC. In conclusion, these findings demonstrate that auranofin-induced cell death is closely related to oxidative stress resulted from increased ROS levels and GSH depletion in lung cancer cells.

Drug repurposing: An emerging strategy in alleviating skin cancer

Skin cancer is one of the most common forms of cancer. Several million people are estimated to have affected with this condition worldwide. Skin cancer generally includes melanoma and non-melanoma with the former being the most dangerous. Chemotherapy has been one of the key therapeutic strategies employed in the treatment of skin cancer, especially in advanced stages of the disease. It could be also used as an adjuvant with other treatment modalities depending on the type of skin cancer. However, there are several shortfalls associated with the use of chemotherapy such as non-selectivity, tumour resistance, life-threatening toxicities, and the exorbitant cost of medicines. Furthermore, new drug discovery is a lengthy and costly process with minimal likelihood of success. Thus, drug repurposing (DR) has emerged as a new avenue where the drug approved formerly for the treatment of one disease can be used for the treatment of another disease like cancer. This approach is greatly beneficial over the de novo approach in terms of time and cost. Moreover, there is minimal risk of failure of repurposed therapeutics in clinical trials. There are a considerable number of studies that have reported on drugs repurposed for the treatment of skin cancer. Thus, the present manuscript offers a comprehensive overview of drugs that have been investigated as repurposing candidates for the efficient treatment of skin cancers mainly melanoma and its oncogenic subtypes, and non-melanoma. The prospects of repurposing phytochemicals against skin cancer are also discussed. Furthermore, repurposed drug delivery via topical route and repurposed drugs in clinical trials are briefed. Based on the findings from the reported studies discussed in this manuscript, drug repurposing emerges to be a promising approach and thus is expected to offer efficient treatment at a reasonable cost in devitalizing skin cancer.

The Antibacterial, Antitumor Activities, and Bioactive Constituents’ Identification of Alectra sessiliflora Bacterial Endophytes

Due to increased antimicrobial resistance against current drugs, new alternatives are sought. Endophytic bacteria associated with medicinal plants are recognized as valuable sources of novel secondary metabolites possessing antimicrobial, antitumor, insecticidal, and antiviral activities. In this study, five bacterial endophytes were isolated and identified from the medicinal plant, Alectra sessiliflora, and their antibacterial and antitumor activities were investigated. In addition, the crude extracts of the endophytes were analyzed using gas chromatography (GC) coupled with time-of-flight mass spectrometry (TOF-MS). The identified bacterial endophytes belong to three genera viz Lysinibacillus, Peribacillus, and Bacillus, with the latter as the dominant genus with three species. Ethyl acetate extracts from the endophytes were used for antimicrobial activity against eleven pathogenic strains through minimum inhibitory concentration (MIC). The antitumor activity against the Hela cervical, Hek 293 kidney, and A549 lung carcinoma cells was determined by the MTS [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxy-phenyl)-2-(4-sulfophenyl)-2H-tetrazolium] assay. Lysinibacillus sp. strain AS_1 exhibited broad antibacterial activity against the pathogenic strains with MIC values ranging from 4 to 8 mg/ml, while Bacillus sp. strain AS_3 displayed MIC of 0.25 mg/ml. Crude extracts of Lysinibacillus sp. strain AS_1, Peribacillus sp. strain AS_2, and Bacillus sp. strain AS_3 showed growth inhibition of more than 90% against all the cancer cell lines at a concentration of 1,000 μg/ml. Untargeted secondary metabolite profiling of the crude extracts revealed the presence of compounds with reported biological activity, such as antimicrobial, antioxidant, anti-inflammatory, antitumor, and antidiabetic properties. This study reported for the first time, bacterial endophytes associated with A. sessiliflora with antibacterial and antitumor activities.

Bone Marrow Mesenchymal Stem Cells (BMSCs)-Triggered Up-Regulation of miR-1297/NLR Family Pyrin Domain Containing 3 (NLRP3) Facilitates the Aggressive Proliferation of Lung Cancer Cells via Inducing Inflammatory Factor Release

miR-1297 derived from BMSC-originated exosomes participates in modulating multiple malignancies. Our study aims to clarify the effect of miR-1297 derived from BMSC-originated exosomes on the oxidative stress and inflammatory damage of lung cancer cells. miR-1297 and NLRP3 level was measured in lung cancer tissues and para-cancerous tissues, as well as in lung cancer cell lines and pulmonary epithelial cells. After miR-1297-mimics transfection or BMSC co-cultivation, cell viability was assessed by MTT and cytokines were evaluated by ELISA along with analysis of SOD activity and cell apoptosis. miR-1297 and NLRP3 were significantly elevated in lung cancer tissues and cell lines. Overexpression of miR-1297 enhanced oxidative stress and inflammatory response, along with increased cell viability and decreased apoptosis. Additionally, co-culture with BMSC protect the viability of lung cancer cells by facilitating miR-1297/NLRP3. In conclusion, a significant elevation of miR-1297 is found in lung cancer tissues and cells. Its overexpression induced the release of inflammatory factors, thereby protecting the proliferating activity of lung cancer cells and restraining apoptosis, indicating that miR-1297 may serve a promising target for early diagnosis of lung cancers.

Di-(2-ethyl hexyl) phthalate induced oxidative stress promotes microplastics mediated apoptosis and necroptosis in mice skeletal muscle by inhibiting PI3K/AKT/mTOR pathway

The plastic decomposition product microplastics (MPs) and the plastic additive Di (2-ethylhexyl) phthalate (DEHP) in the environment can damage various organs of the organism by inducing oxidative stress. The PI3K/AKT/mTOR signaling pathway participate in toxin-induced apoptosis and necroptosis. However, the effects of DEHP/MPs alone and combined exposure on skeletal muscle cell injury in mice and the role of PI3K/AKT/mTOR axis remain unclear. To investigate the effect of DEHP or/and MPs on skeletal muscle in mice and its possible toxicological mechanism, 60 mice were randomly divided into control group, DEHP group (DEHP 200 mg/kg dissolved in 50 mL corn oil mixed with 2.5 kg diet), MPs group (10 mg/L MPs in drinking water) and combined exposure group. In vitro, C2C12 cells were exposed to DEHP 600 μM/MPs 800 μM alone or in combination for 24 h. The results showed that DEHP/MPs exposure alone or in combination increased MDA content, decreased activities of CAT, T-AOC, SOD and GSH-Px, increased mRNA and protein expressions of Caspase-3, BAX, RIPK1, RIPK3 and MLKL, and decreased BCL-2 expression. The expression of PI3K/AKT/mTOR signaling pathway was significantly down-regulated. All the above results showed that the combined exposure group was more toxic, and similar experimental results were obtained by DEHP/MPs exposure test of C2C12 cells in vitro. It is suggested that DEHP/MPs can induce apoptosis and necroptosis by activating oxidative stress and down-regulating PI3K/AKT/mTOR pathway. This study provides new evidence for clarifying the possible mechanism of toxicity of DEHP and MPs to skeletal muscle of mice.

The Role of the Thioredoxin Detoxification System in Cancer Progression and Resistance

The intracellular redox homeostasis is a dynamic balancing system between the levels of free radical species and antioxidant enzymes and small molecules at the core of cellular defense mechanisms. The thioredoxin (Trx) system is an important detoxification system regulating the redox milieu. This system is one of the key regulators of cells’ proliferative potential as well, through the reduction of key proteins. Increased oxidative stress characterizes highly proliferative, metabolically hyperactive cancer cells, which are forced to mobilize antioxidant enzymes to balance the increase in free radical concentration and prevent irreversible damage and cell death. Components of the Trx system are involved in high-rate proliferation and activation of pro-survival mechanisms in cancer cells, particularly those facing increased oxidative stress. This review addresses the importance of the targetable redox-regulating Trx system in tumor progression, as well as in detoxification and protection of cancer cells from oxidative stress and drug-induced cytotoxicity. It also discusses the cancer cells’ counteracting mechanisms to the Trx system inhibition and presents several inhibitors of the Trx system as prospective candidates for cytostatics’ adjuvants. This manuscript further emphasizes the importance of developing novel multitarget therapies encompassing the Trx system inhibition to overcome cancer treatment limitations.

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.

A novel cyclic dinuclear gold(I) complex induces anticancer activity via an 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 spectroscopy, and X-ray crystallography. In the dinuclear complex cation [Au2(DCyPA)2]2+, the two gold(I) ions are bridged by the ligand bis[2-(dicyclohexylphosphano)ethyl]amine (DCyPA) giving rise to a 16-membered ring centrosymmetric metallacycle. The cytotoxicity of the complex was evaluated against the triple-negative human breast cancer cells MDA-MB-231. In order to understand the mechanism of the cytotoxic behavior, a variety of assays, including Annexin V-FITC/Propidium iodide double staining, ROS production, and mitochondrial membrane potential and migration assays were carried out. The results indicated that complex 1 induced cytotoxicity via an oxidative stress-mediated intrinsic apoptotic pathway in MDA-MB-231 cancer cells.

Breast Cancer Treatment: The Case of Gold(I)-Based Compounds as a Promising Class of Bioactive Molecules

Breast cancers (BCs) may present dramatic diagnoses, both for ineffective therapies and for the limited outcomes in terms of lifespan. For these types of tumors, the search for new drugs is a primary necessity. It is widely recognized that gold compounds are highly active and extremely potent as anticancer agents against many cancer cell lines. The presence of the metal plays an essential role in the activation of the cytotoxicity of these coordination compounds, whose activity, if restricted to the ligands alone, would be non-existent. On the other hand, gold exhibits a complex biochemistry, substantially variable depending on the chemical environments around the central metal. In this review, the scientific findings of the last 6–7 years on two classes of gold(I) compounds, containing phosphane or carbene ligands, are reviewed. In addition to this class of Au(I) compounds, the recent developments in the application of Auranofin in regards to BCs are reported. Auranofin is a triethylphosphine-thiosugar compound that, being a drug approved by the FDA—therefore extensively studied—is an interesting lead gold compound and a good comparison to understand the activities of structurally related Au(I) compounds.

Computational Studies of Au(I) and Au(III) Anticancer MetalLodrugs: A Survey

Owing to the growing hardware capabilities and the enhancing efficacy of computational methodologies, computational chemistry approaches have constantly become more important in the development of novel anticancer metallodrugs. Besides traditional Pt-based drugs, inorganic and organometallic complexes of other transition metals are showing increasing potential in the treatment of cancer. Among them, Au(I)- and Au(III)-based compounds are promising candidates due to the strong affinity of Au(I) cations to cysteine and selenocysteine side chains of the protein residues and to Au(III) complexes being more labile and prone to the reduction to either Au(I) or Au(0) in the physiological milieu. A correct prediction of metal complexes' properties and of their bonding interactions with potential ligands requires QM computations, usually at the ab initio or DFT level. However, MM, MD, and docking approaches can also give useful information on their binding site on large biomolecular targets, such as proteins or DNA, provided a careful parametrization of the metal force field is employed. In this review, we provide an overview of the recent computational studies of Au(I) and Au(III) antitumor compounds and of their interactions with biomolecular targets, such as sulfur- and selenium-containing enzymes, like glutathione reductases, glutathione peroxidase, glutathione-S-transferase, cysteine protease, thioredoxin reductase and poly (ADP-ribose) polymerase 1.

Combination of Auranofin and ICG-001 Suppress the Proliferation and Metastasis of Colon Cancer

Colon cancer is one of the deadliest tumors in the world, and with high metastasis rate and mortality, effective drugs for its treatment are still in need. Auranofin (AF) is a gold complex that has been attested by FDA for treating human rheumatism, and researchers have found that AF acts as a great antitumor drug in recent years. ICG-001 is a small molecule inhibitor of Wnt/β-catenin pathway. In the present study, we aimed to explore the synergistic antitumor effects and the underlying mechanisms of AF and ICG-001 combination therapy on human colon cancer. The results showed that AF and ICG-001 synergistically depressed the growth and invasion of human colon cancer cells by inhibiting the phosphorylation of Signal Transducer and Activator of Transcription 3 (STAT3) and its downstream mediator B-cell lymphoma-2-like 1 (Bcl-xL) and inducing caspase-3-dependent apoptosis. Moreover, AF combined with ICG-001 synergistically inhibited the growth of colon cancer in subcutaneous xenograft mice models and restrained metastasis in lung metastasis mice models. In conclusion, our results demonstrated that combination of AF and ICG-001 suppressed the proliferation and metastasis of colon cancer by inhibiting STAT3 phosphorylation. Therefore, this combination therapy may possess potential therapeutic properties for human colon cancer.

Thioredoxin reductase-1 levels are associated with NRF2 pathway activation and tumor recurrence in non-small cell lung cancer

Activating mutations in the KEAP1/NRF2 pathway characterize a subset of non-small cell lung cancer (NSCLC) associated with chemoresistance and poor prognosis. We herein evaluated the relationship between 64 oxidative stress-related genes and overall survival data from 35 lung cancer datasets. Thioredoxin reductase-1 (TXNRD1) stood out as the most significant predictor of poor outcome. In a cohort of NSCLC patients, high TXNRD1 protein levels correlated with shorter disease-free survival and distal metastasis-free survival post-surgery, including a subset of individuals treated with platinum-based adjuvant chemotherapy. Bioinformatics analysis revealed that NSCLC tumors harboring genetic alterations in the NRF2 pathway (KEAP1, NFE2L2 and CUL3 mutations, and NFE2L2 amplification) overexpress TXNRD1, while no association with EGFR, KRAS, TP53 and PIK3CA mutations was found. In addition, nuclear accumulation of NRF2 overlapped with upregulated TXNRD1 protein in NSCLC tumors. Functional cell assays and gene dependency analysis revealed that NRF2, but not TXNRD1, has a pivotal role in KEAP1 mutant cells' survival. KEAP1 mutants overexpress TXNRD1 and are less susceptible to the cytotoxic effects of the TXNRD1 inhibitor auranofin when compared to wild-type cell lines. Inhibition of NRF2 with siRNA or ML-385, and glutathione depletion with buthionine-sulfoximine, sensitized KEAP1 mutant A549 cells to auranofin. NRF2 knockdown and GSH depletion also augmented cisplatin cytotoxicity in A549 cells, whereas auranofin had no effect. In summary, these findings suggest that TXNRD1 is not a key determinant of malignant phenotypes in KEAP1 mutant cells, although this protein can be a surrogate marker of NRF2 pathway activation, predicting tumor recurrence and possibly other aggressive phenotypes associated with NRF2 hyperactivation in NSCLC.

Repurposing drugs in autophagy for the treatment of cancer: From bench to bedside

Autophagy is a multistep degradation pathway involving the lysosome, which supports nutrient reuse and metabolic balance, and has been implicated as a process that regulates cancer genesis and development. Targeting tumors by regulating autophagy has become a therapeutic strategy of interest. Drugs with other indications can have antitumor activity by modulating autophagy, providing a shortcut to developing novel antitumor drugs (i.e., drug repurposing/repositioning), as successfully performed for chloroquine (CQ); an increasing number of repurposed drugs have since advanced into clinical trials. In this review, we describe the application of different drug-repurposing approaches in autophagy for the treatment of cancer and focus on repurposing drugs that target autophagy to treat malignant neoplasms.

Auranofin: Past to Present, and repurposing

Auranofin (AF), a gold compound, has been used to treat rheumatoid arthritis (RA) for more than 40 years; however, its mechanism of action remains unknown. We revealed that AF inhibited the induction of proinflammatory proteins and their mRNAs by the inflammatory stimulants, cyclooxygenase-2 and inducible nitric oxide synthase, and their upstream regulator, NF-κB. AF also activated the proteins peroxyredoxin-1, Kelch-like ECH-associated protein 1, and NF-E2-related factor 2, and inhibited thioredoxin reductase, all of which are involved in oxidative or electrophilic stress under physiological conditions. Although the cell membrane was previously considered to be permeable to AF because of its hydrophobicity, the mechanisms responsible for transporting AF into and out of cells as well as its effects on the uptake and excretion of other drugs have not yet been elucidated. Antibodies for cytokines have recently been employed in the treatment of RA, which has had an impact on the use of AF. Trials to repurpose AF as a risk-controlled agent to treat cancers or infectious diseases, including severe acute respiratory syndrome coronavirus 2/coronavirus disease 2019, are ongoing. Novel gold compounds are also under development as anti-cancer and anti-infection agents.

The gold complex auranofin: new perspectives for cancer therapy

Advanced stages of cancer are highly associated with short overall survival in patients due to the lack of long-term treatment options following the standard form of care. New options for cancer therapy are needed to improve the survival of cancer patients without disease recurrence. Auranofin is a clinically approved agent against rheumatoid arthritis that is currently enrolled in clinical trials for potential repurposing against cancer. Auranofin mainly targets the anti-oxidative system catalyzed by thioredoxin reductase (TrxR), which protects the cell from oxidative stress and death in the cytoplasm and the mitochondria. TrxR is over-expressed in many cancers as an adaptive mechanism for cancer cell proliferation, rendering it an attractive target for cancer therapy, and auranofin as a potential therapeutic agent for cancer. Inhibiting TrxR dysregulates the intracellular redox state causing increased intracellular reactive oxygen species levels, and stimulates cellular demise. An alternate mechanism of action of auranofin is to mimic proteasomal inhibition by blocking the ubiquitin-proteasome system (UPS), which is critically important in cancer cells to prevent cell death when compared to non-cancer cells, because of its role on cell cycle regulation, protein degradation, gene expression, and DNA repair. This article provides new perspectives on the potential mechanisms used by auranofin alone, in combination with diverse other compounds, or in combination with platinating agents and/or immune checkpoint inhibitors to combat cancer cells, while assessing the feasibility for its repurposing in the clinical setting.

Activators and Inhibitors of Protein Kinase C (PKC): Their Applications in Clinical Trials

Protein kinase C (PKC), a family of phospholipid-dependent serine/threonine kinase, is classed into three subfamilies based on their structural and activation characteristics: conventional or classic PKC isozymes (cPKCs; α, βI, βII, and γ), novel or non-classic PKC isozymes (nPKCs; δ, ε, η, and θ), and atypical PKC isozymes (aPKCs; ζ, ι, and λ). PKC inhibitors and activators are used to understand PKC-mediated intracellular signaling pathways and for the diagnosis and treatment of various PKC-associated diseases, such as cancers, neurological diseases, cardiovascular diseases, and infections. Many clinical trials of PKC inhibitors in cancers showed no significant clinical benefits, meaning that there is a limitation to design a cancer therapeutic strategy targeting PKC alone. This review will focus on the activators and inhibitors of PKC and their applications in clinical trials.

Current Progress and Perspectives on Using Gold Compounds for the Modulation of Tumor Cell Metabolism

Altered cellular metabolism, which is essential for the growth and survival of tumor cells in a specific microenvironment, is one of the hallmarks of cancer. Among the most significant changes in the metabolic pattern of tumor cells is the shift from oxidative phosphorylation to aerobic glycolysis for glucose utilization. Tumor cells also exhibit changes in patterns of protein and nucleic acid metabolism. Recently, gold compounds have been shown to target several metabolic pathways and a number of metabolites in tumor cells. In this review, we summarize how gold compounds modulate glucose, protein, and nucleic acid metabolism in tumor cells, resulting in anti-tumor effects. We also discuss the rationale underlying the anti-tumor effects of these gold compounds and highlight how to effectively utilize against various types of tumors.

Identification of COVID-19 prognostic markers and therapeutic targets through meta-analysis and validation of Omics data from nasopharyngeal samples

Background

While our battle with the COVID-19 pandemic continues, a multitude of Omics data have been generated from patient samples in various studies. Translation of these data into clinical interventions against COVID-19 remains to be accomplished. Exploring host response to COVID-19 in the upper respiratory tract can unveil prognostic markers and therapeutic targets.

Methods

We conducted a meta-analysis of published transcriptome and proteome profiles of respiratory samples of COVID-19 patients to shortlist high confidence upregulated host factors. Subsequently, mRNA overexpression of selected genes was validated in nasal swabs from a cohort of COVID-19 positive/negative, symptomatic/asymptomatic individuals. Guided by this analysis, we sought to check for potential drug targets. An FDA-approved drug, Auranofin, was tested against SARS-CoV-2 replication in cell culture and Syrian hamster challenge model.

Findings

The meta-analysis and validation in the COVID-19 cohort revealed S100 family genes (S100A6, S100A8, S100A9, and S100P) as prognostic markers of severe COVID-19. Furthermore, Thioredoxin (TXN) was found to be consistently upregulated. Auranofin, which targets Thioredoxin reductase, was found to mitigate SARS-CoV-2 replication in vitro. Furthermore, oral administration of Auranofin in Syrian hamsters in therapeutic as well as prophylactic regimen reduced viral replication, IL-6 production, and inflammation in the lungs.

Interpretation

Elevated mRNA level of S100s in the nasal swabs indicate severe COVID-19 disease, and FDA-approved drug Auranofin mitigated SARS-CoV-2 replication in preclinical hamster model.

Funding

This study was supported by the DBT-IISc partnership program (DBT (IED/4/2020-MED/DBT)), the Infosys Young Investigator award (YI/2019/1106), DBT-BIRAC grant (BT/CS0007/CS/02/20) and the DBT-Wellcome Trust India Alliance Intermediate Fellowship (IA/I/18/1/503613) to ST lab.

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

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

Drug Repurposing, an Attractive Strategy in Pancreatic Cancer Treatment: Preclinical and Clinical Updates

Pancreatic cancer (PC) is one of the deadliest malignancies worldwide, since patients rarely display symptoms until an advanced and unresectable stage of the disease. Current chemotherapy options are unsatisfactory and there is an urgent need for more effective and less toxic drugs to improve the dismal PC therapy. Repurposing of non-oncology drugs in PC treatment represents a very promising therapeutic option and different compounds are currently being considered as candidates for repurposing in the treatment of this tumor. In this review, we provide an update on some of the most promising FDA-approved, non-oncology, repurposed drug candidates that show prominent clinical and preclinical data in pancreatic cancer. We also focus on proposed mechanisms of action and known molecular targets that they modulate in PC. Furthermore, we provide an explorative bioinformatic analysis, which suggests that some of the PC repurposed drug candidates have additional, unexplored, oncology-relevant targets. Finally, we discuss recent developments regarding the immunomodulatory role displayed by some of these drugs, which may expand their potential application in synergy with approved anticancer immunomodulatory agents that are mostly ineffective as single agents in PC.

Metabolic Strategies for Inhibiting Cancer Development

The tumor microenvironment is a complex mix of cancerous and noncancerous cells (especially immune cells and fibroblasts) with distinct metabolisms. These cells interact with each other and are influenced by the metabolic disorders of the host. In this review, we discuss how metabolic pathways that sustain biosynthesis in cancer cells could be targeted to increase the effectiveness of cancer therapies by limiting the nutrient uptake of the cell, inactivating metabolic enzymes (key regulatory ones or those linked to cell cycle progression), and inhibiting ATP production to induce cell death. Furthermore, we describe how the microenvironment could be targeted to activate the immune response by redirecting nutrients toward cytotoxic immune cells or inhibiting the release of waste products by cancer cells that stimulate immunosuppressive cells. We also examine metabolic disorders in the host that could be targeted to inhibit cancer development. To create future personalized therapies for targeting each cancer tumor, novel techniques must be developed, such as new tracers for positron emission tomography/computed tomography scan and immunohistochemical markers to characterize the metabolic phenotype of cancer cells and their microenvironment. Pending personalized strategies that specifically target all metabolic components of cancer development in a patient, simple metabolic interventions could be tested in clinical trials in combination with standard cancer therapies, such as short cycles of fasting or the administration of sodium citrate or weakly toxic compounds (such as curcumin, metformin, lipoic acid) that target autophagy and biosynthetic or signaling pathways.

Vitamin D affects the Warburg effect and stemness maintenance of non-small-cell lung cancer cells by regulating PI3K/AKT/mTOR signaling pathway

BACKGROUND

Non-small-cell lung cancer (NSCLC) is the most prevalent form of lung cancer, accounting for approximately 85% of all lung cancer cases and resulting in high morbidity and mortality. Previous studies have demonstrated that 1,25-dihydroxy-vitamin-D3 (vitamin D) exhibited anti-cancer activity against breast and prostate cancer.

OBJECTIVES

The aim of the current study is to investigate the effect of vitamin D on NSCLC and its underlying mechanism.

METHODS

The effects of vitamin D on stemness maintenance and the Warburg effect in NSCLC cells were investigated both in vitro and in vivo.

RESULTS & DISCUSSION

In vitro experiments revealed that vitamin D inhibited glycolysis and stemness maintenance in A549 and NCI-H1975 cells. Both in vitro and in vivo experiments indicated that vitamin D attenuated the expression of metabolism-related enzymes associated with the Warburg effect (GLUT1, LDHA, HK2, and PKM2). In addition, vitamin D down-regulated the expression of stemness-related genes (Oct-4, SOX-2, and Nanog) and the expression of PI3K, AKT, and mTOR.

CONCLUSION

Overall, these findings suggest that vitamin D suppresses the Warburg effect and stemness maintenance in NSCLC cells via the inactivation of PI3K/AKT/mTOR signaling, thereby inhibiting the progression of NSCLC. The current study indicates that vitamin D is a potential candidate in therapeutic strategies against NSCLC.