Targeting Cell Metabolism as Cancer Therapy

Clinical research framework proposal for ketogenic metabolic therapy in glioblastoma

Glioblastoma (GBM) is the most aggressive primary brain tumor in adults, with a universally lethal prognosis despite maximal standard therapies. Here, we present a consensus treatment protocol based on the metabolic requirements of GBM cells for the two major fermentable fuels: glucose and glutamine. Glucose is a source of carbon and ATP synthesis for tumor growth through glycolysis, while glutamine provides nitrogen, carbon, and ATP synthesis through glutaminolysis. As no tumor can grow without anabolic substrates or energy, the simultaneous targeting of glycolysis and glutaminolysis is expected to reduce the proliferation of most if not all GBM cells. Ketogenic metabolic therapy (KMT) leverages diet-drug combinations that inhibit glycolysis, glutaminolysis, and growth signaling while shifting energy metabolism to therapeutic ketosis. The glucose-ketone index (GKI) is a standardized biomarker for assessing biological compliance, ideally via real-time monitoring. KMT aims to increase substrate competition and normalize the tumor microenvironment through GKI-adjusted ketogenic diets, calorie restriction, and fasting, while also targeting glycolytic and glutaminolytic flux using specific metabolic inhibitors. Non-fermentable fuels, such as ketone bodies, fatty acids, or lactate, are comparatively less efficient in supporting the long-term bioenergetic and biosynthetic demands of cancer cell proliferation. The proposed strategy may be implemented as a synergistic metabolic priming baseline in GBM as well as other tumors driven by glycolysis and glutaminolysis, regardless of their residual mitochondrial function. Suggested best practices are provided to guide future KMT research in metabolic oncology, offering a shared, evidence-driven framework for observational and interventional studies.

Intervention of Tanshinone IIA on the PGK1-PDHK1 Pathway to Reprogram Macrophage Phenotype After Myocardial Infarction

BACKGROUND

Myocardial infarction remains a disease with high morbidity and death rate among cardiovascular diseases. Macrophages are abundant immune cells in the heart. Under different stimulatory factors, macrophages can differentiate into different phenotypes and play a dual pro-inflammatory and anti-inflammatory role. Therefore, a potential strategy for the treatment of myocardial infarction is to regulate the energy metabolism of macrophages and thereby regulate the polarization of macrophages. Tan IIA is an effective liposolubility component extracted from the root of Salvia miltiorrhiza and plays an important role in the treatment of cardiovascular diseases. On this basis, this study proposed whether Tan IIA could affect phenotype changes by regulating energy metabolism of macrophages, and thus exert its potential in the treatment of MI.

METHODS

Establishing a myocardial infarction model, Tan IIA was given for 3 days and 7 days for intervention. Cardiac function was detected by echocardiography, and cardiac pathological sections of each group were stained with HE and Masson to observe the inflammatory cell infiltration and fibrosis area after administration. The expression and secretion of inflammatory factors in heart tissue and serum of each group, as well as the proportion of macrophages at the myocardial infarction site, were detected using RT-PCR, ELISA, and immunofluorescence. The mitochondrial function of macrophages was evaluated using JC-1, calcium ion concentration detection, reactive oxygen species detection, and mitochondrial electron microscopic analysis. Mechanically, single-cell transcriptome data mining, cell transcriptome sequencing, and molecular docking technology were used to anchor the target of Tan IIA and enrich the pathways to explore the mechanism of Tan IIA regulating macrophage energy metabolism and phenotype. The target of Tan IIA was further determined by gene knockdown and overexpression assay.

RESULTS

The intervention of Tan IIA can improve the cardiac function, inflammatory cell infiltration and fibrosis after MI, reduce the expression of inflammatory factors in the heart, enhance the secretion of anti-inflammatory factors, increase the proportion of M2-type macrophages, reduce the proportion of M1-type macrophages, and promote tissue repair, suggesting that Tan IIA has pharmacological effects in the treatment of MI. In terms of mechanism, RNA-seq results suggest that the phenotype of macrophages is strongly correlated with energy metabolism, and Tan IIA can regulate the PGK1-PDHK1 signaling pathway, change the energy metabolism mode of macrophages, and then affect its phenotype.

CONCLUSION

Tan IIA regulates the energy metabolism of macrophages and changes its phenotype through the PGK1-PDHK1 signaling pathway, thus playing a role in improving MI.

Nrf2-mediated adenylosuccinate lyase promotes resistance to gemcitabine in pancreatic ductal adenocarcinoma cells through ferroptosis escape

Pancreatic cancer has one of the highest fatality rates and the poorest prognosis among all cancer types worldwide. Gemcitabine is a commonly used first-line therapeutic drug for pancreatic cancer; however, the rapid development of resistance to gemcitabine treatment has been observed in numerous patients with pancreatic cancer, and this phenomenon limits the survival benefit of gemcitabine. Adenylosuccinate lyase (ADSL) is a crucial enzyme that serves dual functions in de novo purine biosynthesis, and it has been demonstrated to be associated with clinical aggressiveness, prognosis, and worse patient survival for various cancer types. In the present study, we observed significantly lower ADSL levels in gemcitabine-resistant cells (PANC-1/GemR) than in parental PANC-1 cells, and the knockdown of ADSL significantly increased the gemcitabine resistance of parental PANC-1 cells. We further demonstrated that ADSL repressed the expression of CARD-recruited membrane-associated protein 3 (Carma3), which led to increased gemcitabine resistance, and that nuclear factor erythroid 2-related factor 2 (Nrf2) regulated ADSL expression in parental PANC-1 cells. These results indicate that ADSL is a candidate therapeutic target for pancreatic cancer involving gemcitabine resistance and suggest that the Nrf2/ADSL/Carma3 pathway has therapeutic value for pancreatic cancer with acquired resistance to gemcitabine.

Upregulated Nuclear Expression of Soluble Epoxide Hydrolase Predicts Poor Outcome in Breast Cancer Patients: Importance of the Digital Pathology Approach

Breast cancer (BC) is the most common cancer in women, with incidence rates increasing globally in recent years. Therefore, it is important to find new molecules with prognostic and therapeutic value to improve therapeutic response and quality of life. The polyunsaturated fatty acids (PUFAs) metabolic pathway participates in various physiological processes, as well as in the development of malignancies. Although aberrancies in the PUFAs metabolic pathway have been implicated in carcinogenesis, the functional and clinical relevance of this pathway has not been well explored in BC. To evaluate the clinical significance of soluble epoxide hydrolase (EPHX2) expression in Mexican patients with BC using tissue microarrays (TMAs) and digital pathology (DP). Immunohistochemical analyses were performed on 11 TMAs with 267 BC samples to quantify this enzyme. Using DP, EPHX2 protein expression was evaluated solely in tumor areas. The association of EPHX2 with overall survival (OS) was detected through bioinformatic analysis in public databases and confirmed in our cohort via Cox regression analysis. Clear nuclear expression of EPHX2 was identified. Receiver operating characteristics (ROC) curves revealed the optimal cutoff point at 2.847062 × 10-3 pixels, with sensitivity of 69.2% and specificity of 67%. Stratification based on this cutoff value showed elevated EPHX2 expression in multiple clinicopathological features, including older age and nuclear grade, human epidermal growth factor receptor 2 (HER2) and triple negative breast cancer (TNBC) subtypes, and recurrence. Kaplan-Meier curves demonstrated how higher nuclear expression of EPHX2 predicts shorter OS. Consistently, multivariate analysis confirmed EPHX2 as an independent predictor of OS, with a hazard ratio (HR) of 3.483 and a 95% confidence interval of 1.804-6.724 (p < 0.001). Our study demonstrates for the first time that nuclear overexpression of EPHX2 is a predictor of poor prognosis in BC patients. The DP approach was instrumental in identifying this significant association. Our study provides valuable insights into the potential clinical utility of EPHX2 as a prognostic biomarker and therapeutic target in BC.

Targeted immunotherapy to cancer stem cells: A novel strategy of anticancer immunotherapy

Cancer is a major disease that endangers human health. Cancer drug resistance and relapse are the two main causes contributing to cancer treatment failure. Cancer stem cells (CSCs) are a small fraction of tumor cells that are responsible for tumorigenesis, metastasis, relapse, and resistance to conventional anticancer therapies. Therefore, CSCs are considered to be the root of cancer recurrence, metastasis, and drug resistance. Novel anticancer strategies need to face this new challenge and explore their efficacy against CSCs. Recently, immunotherapy has made rapid advances in cancer treatment, and its potential against CSCs is also an interesting area of research. Meanwhile, immunotherapy strategies are novel therapeutic modalities with promising results in targeting CSCs. In this review, we summarize the targeting of CSCs by various immunotherapy strategies such as monoclonal antibodies(mAb), tumor vaccines, immune checkpoint inhibitors, and chimeric antigen receptor-T cells(CAR-T) in pre-clinical and clinical studies. This review provides new insights into the application of these immunotherapeutic approaches to potential anti-tumor therapies in the future.

Cellular and clinical impact of protein phosphatase enzyme epigenetic silencing in multiple cancer tissues

BACKGROUND

Protein Phosphatase Enzymes (PPE) and protein kinases simultaneously control phosphorylation mechanisms that tightly regulate intracellular signalling pathways and stimulate cellular responses. In human malignancies, PPE and protein kinases are frequently mutated resulting in uncontrolled kinase activity and PPE suppression, leading to cell proliferation, migration and resistance to anti-cancer therapies. Cancer associated DNA hypermethylation at PPE promoters gives rise to transcriptional silencing (epimutations) and is a hallmark of cancer. Despite recent advances in sequencing technologies, data availability and computational capabilities, only a fraction of PPE have been reported as transcriptionally inactive as a consequence of epimutations.

METHODS

In this study, we examined promoter-associated DNA methylation profiles in Protein Phosphatase Enzymes and their Interacting Proteins (PPEIP) in a cohort of 705 cancer patients in five tissues (Large intestine, Oesophagus, Lung, Pancreas and Stomach) in three cell models (primary tumours, cancer cell lines and 3D embedded cancer cell cultures). As a subset of PPEIP are known tumour suppressor genes, we analysed the impact of PPEIP promoter hypermethylation marks on gene expression, cellular networks and in a clinical setting.

RESULTS

Here, we report epimutations in PPEIP are a frequent occurrence in the cancer genome and manifest independent of transcriptional activity. We observed that different tumours have varying susceptibility to epimutations and identify specific cellular signalling networks that are primarily affected by epimutations. Additionally, RNA-seq analysis showed the negative impact of epimutations on most (not all) Protein Tyrosine Phosphatase transcription. Finally, we detected novel clinical biomarkers that inform on patient mortality and anti-cancer treatment sensitivity.

CONCLUSIONS

We propose that DNA hypermethylation marks at PPEIP frequently contribute to the pathogenesis of malignancies and within the precision medicine space, hold promise as biomarkers to inform on clinical features such as patient survival and therapeutic response.

Combined inhibition of pyruvate dehydrogenase kinase 1 and lactate dehydrogenase a induces metabolic and signaling reprogramming and enhances lung adenocarcinoma cell killing

Lung adenocarcinoma (LUAD) is one of the most prevalent and aggressive types of lung cancer. Metabolic reprogramming plays a critical role in the development and progression of LUAD. Pyruvate dehydrogenase kinase 1 (PDK1) and lactate dehydrogenase A (LDHA) are two key enzymes involved in glucose metabolism, whilst their aberrant expressions are often associated with tumorigenesis. Herein, we investigated the anticancer effects of combined inhibition of PDK1 and LDHA in LUAD in vitro and in vivo and its underlying mechanisms of action. The combination of a PDK1 inhibitor, 64, and a LDHA inhibitor, NHI-Glc-2, led to a synergistic growth inhibition in 3 different LUAD cell lines and more than additively suppressed tumor growth in the LUAD xenograft H1975 model. This combination also inhibited cellular migration and colony formation, while it induced a metabolic shift from glycolysis to oxidative phosphorylation (OXPHOS) resulting in mitochondrial depolarization and apoptosis in LUAD cells. These effects were related to modulation of multiple cell signaling pathways, including AMPK, RAS/ERK, and AKT/mTOR. Our findings demonstrate that simultaneous inhibition of multiple glycolytic enzymes (PDK1 and LDHA) is a promising novel therapeutic approach for LUAD.

The interplay between microbial metabolites and macrophages in cardiovascular diseases: A comprehensive review

The gut microbiome has emerged as a crucial player in developing and progressing cardiovascular diseases (CVDs). Recent studies have highlighted the role of microbial metabolites in modulating immune cell function and their impact on CVD. Macrophages, which have a significant function in the pathogenesis of CVD, are very vulnerable to the effects of microbial metabolites. Microbial metabolites, such as short-chain fatty acids (SCFAs) and trimethylamine-N-oxide (TMAO), have been linked to atherosclerosis and the regulation of immune functions. Butyrate has been demonstrated to reduce monocyte migration and inhibit monocyte attachment to injured endothelial cells, potentially contributing to the attenuation of the inflammatory response and the progression of atherosclerosis. On the other hand, TMAO, another compound generated by gut bacteria, has been linked to atherosclerosis due to its impact on lipid metabolism and the accumulation of cholesterol in macrophages. Indole-3-propionic acid, a tryptophan metabolite produced solely by microbes, has been found to promote the development of atherosclerosis by stimulating macrophage reverse cholesterol transport (RCT) and raising the expression of ABCA1. This review comprehensively discusses how various microbiota-produced metabolites affect macrophage polarization, inflammation, and foam cell formation in CVD. We also highlight the mechanisms underlying these effects and the potential therapeutic applications of targeting microbial metabolites in treating CVD.

Targeting cancer metabolic vulnerabilities for advanced therapeutic efficacy

Cancer metabolism is how cancer cells utilize nutrients and energy to support their growth and proliferation. Unlike normal cells, cancer cells have a unique metabolic profile that allows them to generate energy and the building blocks they need for rapid growth and division. This metabolic profile is marked by an increased reliance on glucose and glutamine as energy sources and changes in how cancer cells use and make key metabolic intermediates like ATP, NADH, and NADPH. This script analyzes a comprehensive overview of the latest advances in tumor metabolism, identifying the key unresolved issues, elaborates on how tumor cells differ from normal cells in their metabolism of nutrients, and explains how tumor cells conflate growth signals and nutrients to proliferate. The metabolic interaction of tumorigenesis and lipid metabolism within the tumor microenvironment and the role of ROS as an anti-tumor agent by mediating various signaling pathways for clinical cancer therapeutic targeting are outlined. Cancer metabolism is highly dynamic and heterogeneous; thus, advanced technologies to better investigate metabolism at the unicellular level without altering tumor tissue are necessary for better research and clinical transformation. The study of cancer metabolism is an area of active research, as scientists seek to understand the underlying metabolic changes that drive cancer growth and to identify potential therapeutic targets.

Cancer-associated fibroblasts facilitate DNA damage repair by promoting the glycolysis in non-small cell lung cancer

Radiotherapy is an essential treatment modality for the management of non-small cell lung cancer (NSCLC) patients. Tumor radioresistance is the major factor limiting the efficacy of radiotherapy in NSCLC patients. Our study aimed to reveal whether cancer-associated fibroblasts (CAFs), one main component of the tumor microenvironment, regulated DNA damage response of NSCLC cells following irradiation and clarify the involved mechanisms. We found CAFs inhibited irradiation-induced DNA damage while promoted DNA repair of NSCLC cells and caused cell cycle arrest in the radioresistant S phase. CAFs have the ability of up-regulating and stabilizing c-Myc, leading to the transcription activation of HK2 kinase, a key rate-limiting enzyme in glycolysis by activating Wnt/β-catenin pathway. Attenuation of glycolysis significantly reversed the effect of CAFs on DNA damage response of NSCLC cells. By high-throughput screening of human cytokines/chemokines array, we found CAFs-secreted midkine led to the promotion of glycolysis by activating Wnt/β-catenin pathway in NSCLC cells. In vivo, CAFs caused the radioresistance of NSCLC cells also by promoting the glycolysis in a β-catenin signaling-dependent manner. These findings may provide novel strategies for reversing the radioresistance of NSCLC cells.

Oxidatively Damaged Nucleic Acid: Linking Diabetes and Cancer

Significance: Our current knowledge of the mechanism between diabetes and cancer is limited. Oxidatively damaged nucleic acid is considered a critical factor to explore the connections between these two diseases. Recent Advances: The link between diabetes mellitus and cancer has attracted increasing attention in recent years. Emerging evidence supports that oxidatively damaged nucleic acid caused by an imbalance between reactive oxygen species generation and elimination is a bridge connecting diabetes and cancer. 8-Oxo-7,8-dihydro-2'-deoxyguanosine and 8-oxo-7,8-dihydroguanosine assume important roles as biomarkers in assessing the relationship between oxidatively damaged nucleic acid and cancer. Critical Issues: The consequences of diabetes are extensive and may lead to the occurrence of cancer by influencing a combination of factors. At present, there is no direct evidence that diabetes causes cancer by affecting a single factor. Furthermore, the difficulty in controlling variables and differences in detection methods lead to poor reliability and repeatability of results, and there are no clear cutoff values for biomarkers to indicate cancer risk. Future Directions: A better understanding of connections as well as mechanisms between diabetes and cancer is still needed. Both diabetes and cancer are currently intractable diseases. Further exploration of the specific mechanism of oxidatively damaged nucleic acid in the connection between diabetes and cancer is urgently needed. In the future, it is necessary to further take oxidatively damaged nucleic acid as an entry point to provide new ideas for the diagnosis and treatment of diabetes and cancer. Experimental drugs targeting the repair process of oxidatively generated damage require an extensive preclinical evaluation and could ultimately provide new treatment strategies for these diseases. Antioxid. Redox Signal. 37, 1153-1167.

Acquired drug resistance interferes with the susceptibility of prostate cancer cells to metabolic stress

Background

Metformin is an inhibitor of oxidative phosphorylation that displays an array of anticancer activities. The interference of metformin with the activity of multi-drug resistance systems in cancer cells has been reported. However, the consequences of the acquired chemoresistance for the adaptative responses of cancer cells to metformin-induced stress and for their phenotypic evolution remain unaddressed.

Methods

Using a range of phenotypic and metabolic assays, we assessed the sensitivity of human prostate cancer PC-3 and DU145 cells, and their drug-resistant lineages (PC-3_DCX20 and DU145_DCX20), to combined docetaxel/metformin stress. Their adaptation responses have been assessed, in particular the shifts in their metabolic profile and invasiveness.

Results

Metformin increased the sensitivity of PC-3 wild-type (WT) cells to docetaxel, as illustrated by the attenuation of their motility, proliferation, and viability after the combined drug application. These effects correlated with the accumulation of energy carriers (NAD(P)H and ATP) and with the inactivation of ABC drug transporters in docetaxel/metformin-treated PC-3 WT cells. Both PC-3 WT and PC-3_DCX20 reacted to metformin with the Warburg effect; however, PC-3_DCX20 cells were considerably less susceptible to the cytostatic/misbalancing effects of metformin. Concomitantly, an epithelial–mesenchymal transition and Cx43 upregulation was seen in these cells, but not in other more docetaxel/metformin-sensitive DU145_DCX20 populations. Stronger cytostatic effects of the combined fenofibrate/docetaxel treatment confirmed that the fine-tuning of the balance between energy supply and expenditure determines cellular welfare under metabolic stress.

Conclusions

Collectively, our data identify the mechanisms that underlie the limited potential of metformin for the chemotherapy of drug-resistant tumors. Metformin can enhance the sensitivity of cancer cells to chemotherapy by inducing their metabolic decoupling/imbalance. However, the acquired chemoresistance of cancer cells impairs this effect, facilitates cellular adaptation to metabolic stress, and prompts the invasive front formation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s11658-022-00400-1.

Long-Term Fenofibrate Treatment Stimulates the Phenotypic Microevolution of Prostate Cancer Cells In Vitro

Fenofibrate is a widely used anti-hyperlipidemic agonist of peroxisome proliferator-activated receptor alpha (PPARα). As a metabolic blocker, fenofibrate interferes with cancer promotion/progression via its misbalancing effects on cellular metabolism. However, the consequences of its long-term application for patients with diagnosed drug-resistant cancers are unknown. We addressed this point by tracing the phenotypic microevolution of naïve and drug-resistant prostate cancer PC3_DCX20 cells that underwent a long-term exposition to 10 μM and 50 μM fenofibrate. Their resistance to fenofibrate, metabolic profile and invasive phenotype were estimated in the control conditions and under fenofibrate-induced stress. Apparently, drug efflux systems are not effective against the cytostatic FF action. However, wtPC3 and PC3_DCX20 cells that survived the long-term 50 μM fenofibrate treatment gave rise to lineages that displayed an increased proliferation rate, lower motility in the control conditions and enhanced fenofibrate resistance. Attenuated fenofibrate bioavailability modified the pattern of PC3 microevolution, as illustrated by phenotypic differences between wtPC3/PC3_DCX20 lineages propagated in the presence of 50 μM and 10 μM fenofibrate. Collectively, our observations indicate that fenofibrate acts as a selective factor that affects prostate cancer microevolution. We also pinpoint potential consequences of long-term exposition of prostate cancer patients to metabolic blockers.

Archaea Microbiome Dysregulated Genes and Pathways as Molecular Targets for Lung Adenocarcinoma and Squamous Cell Carcinoma

The human microbiome is a vast collection of microbial species that exist throughout the human body and regulate various bodily functions and phenomena. Of the microbial species that exist in the human microbiome, those within the archaea domain have not been characterized to the extent of those in more common domains, despite their potential for unique metabolic interaction with host cells. Research has correlated tumoral presence of bacterial microbial species to the development and progression of lung cancer; however, the impacts and influences of archaea in the microbiome remain heavily unexplored. Within the United States lung cancer remains highly fatal, responsible for over 100,000 deaths every year with a 5-year survival rate of roughly 22.9%. This project attempts to investigate specific archaeal species' correlation to lung adenocarcinoma (LUAD) and lung squamous cell carcinoma (LUSC) incidence, patient staging, death rates across individuals of varying ages, races, genders, and smoking-statuses, and potential molecular targets associated with archaea microbiome. Archaeal species abundance was assessed across lung tissue samples of 527 LUAD patients, 479 LUSC patients, and 99 healthy individuals. Nine archaeal species were found to be of significantly altered abundance in cancerous samples as compared to normal counterparts, 6 of which are common to both LUAD and LUSC subgroups. Several of these species are of the taxonomic class Thermoprotei or the phylum Euryarchaeota, both known to contain metabolic processes distinct from most bacterial species. Host-microbe metabolic interactions may be responsible for the observed correlation of these species' abundance with cancer incidence. Significant microbes were correlated to patient gene expression to reveal genes of altered abundance with respect to high and low archaeal presence. With these genes, cellular oncogenic signaling pathways were analyzed for enrichment across cancer and normal samples. In comparing gene expression between LUAD and adjacent normal samples, 2 gene sets were found to be significantly enriched in cancers. In LUSC comparison, 6 sets were significantly enriched in cancer, and 34 were enriched in normals. Microbial counts across healthy and cancerous patients were then used to develop a machine-learning based predictive algorithm, capable of distinguishing lung cancer patients from healthy normal with 99% accuracy.

Divergence of acetate uptake in proinflammatory and inflammation-resolving macrophages: implications for imaging atherosclerosis

BACKGROUND

Metabolic divergence of macrophages polarized into different phenotypes represents a mechanistically relevant target for non-invasive characterization of atherosclerotic plaques using positron emission tomography (PET). Carbon-11 (11C)-labeled acetate is a clinically available tracer which accumulates in atherosclerotic plaques, but its biological and clinical correlates in atherosclerosis are undefined.

METHODS AND RESULTS

Histological correlates of 14C-acetate uptake were determined in brachiocephalic arteries of western diet-fed apoE-/- mice. The effect of polarizing stimuli on 14C-acetate uptake was determined by proinflammatory (interferon-γ + lipopolysaccharide) vs inflammation-resolving (interleukin-4) stimulation of murine macrophages and human carotid endarterectomy specimens over 2 days. 14C-acetate accumulated in atherosclerotic regions of arteries. CD68-positive monocytes/macrophages vs smooth muscle actin-positive smooth muscle cells were the dominant cells in regions with high vs low 14C-acetate uptake. 14C-acetate uptake progressively decreased in proinflammatory macrophages to 25.9 ± 4.5% of baseline (P < .001). A delayed increase in 14C-acetate uptake was induced in inflammation-resolving macrophages, reaching to 164.1 ± 21.4% (P < .01) of baseline. Consistently, stimulation of endarterectomy specimens with interferon-γ + lipopolysaccharide decreased 14C-acetate uptake to 66.5 ± 14.5%, while interleukin-4 increased 14C-acetate uptake to 151.5 ± 25.8% compared to non-stimulated plaques (P < .05).

CONCLUSIONS

Acetate uptake by macrophages diverges upon proinflammatory and inflammation-resolving stimulation, which may be exploited for immunometabolic characterization of atherosclerosis.

Thioredoxin-Interacting Protein in Cancer and Diabetes

Significance: Thioredoxin-interacting protein (Txnip) is an α-arrestin protein that acts as a cancer suppressor. Txnip is simultaneously a critical regulator of energy metabolism. Other alpha-arrestin proteins also play key roles in cell biology and cancer. Recent Advances: Txnip expression is regulated by multilayered mechanisms, including transcriptional regulation, microRNA, messenger RNA (mRNA) stabilization, and protein degradation. The Txnip-based connection between cancer and metabolism has been widely recognized. Meanwhile, new aspects are proposed for the mechanism of action of Txnip, including the regulation of RNA expression and autophagy. Arrestin domain containing 3 (ARRDC3), another α-arrestin protein, regulates endocytosis and signaling, whereas ARRDC1 and ARRDC4 regulate extracellular vesicle formation. Critical Issues: The mechanism of action of Txnip is yet to be elucidated. The regulation of intracellular protein trafficking by arrestin family proteins has opened an emerging field of biology and medical research, which needs to be examined further. Future Directions: A fundamental understanding of the mechanism of action of Txnip and other arrestin family members needs to be explored in the future to combat diseases such as cancer and diabetes. Antioxid. Redox Signal. 36, 1001-1022.

EPHX2 Inhibits Colon Cancer Progression by Promoting Fatty Acid Degradation

Tumor cells use metabolic reprogramming to keep up with the need for bioenergy, biosynthesis, and oxidation balance needed for rapid tumor division. This phenomenon is considered a marker of tumors, including colon cancer (CRC). As an important pathway of cellular energy metabolism, fatty acid metabolism plays an important role in cellular energy supply and oxidation balance, but presently, our understanding of the exact role of fatty acid metabolism in CRC is limited. Currently, no lipid metabolism therapy is available for the treatment of CRC. The establishment of a lipidmetabolism model regulated by oncogenes/tumor suppressor genes and associated with the clinical characteristics of CRC is necessary to further understand the mechanism of fatty acid metabolism in CRC. In this study, through multi-data combined with bioinformatic analysis and basic experiments, we introduced a tumor suppressor gene, EPHX2, which is rarely reported in CRC, and confirmed that its inhibitory effect on CRC is related to fatty acid degradation.

Impact of cancer metabolism on therapy resistance - Clinical implications

Despite an increasing arsenal of anticancer therapies, many patients continue to have poor outcomes due to the therapeutic failures and tumor relapses. Indeed, the clinical efficacy of anticancer therapies is markedly limited by intrinsic and/or acquired resistance mechanisms that can occur in any tumor type and with any treatment. Thus, there is an urgent clinical need to implement fundamental changes in the tumor treatment paradigm by the development of new experimental strategies that can help to predict the occurrence of clinical drug resistance and to identify alternative therapeutic options. Apart from mutation-driven resistance mechanisms, tumor microenvironment (TME) conditions generate an intratumoral phenotypic heterogeneity that supports disease progression and dismal outcomes. Tumor cell metabolism is a prototypical example of dynamic, heterogeneous, and adaptive phenotypic trait, resulting from the combination of intrinsic [(epi)genetic changes, tissue of origin and differentiation dependency] and extrinsic (oxygen and nutrient availability, metabolic interactions within the TME) factors, enabling cancer cells to survive, metastasize and develop resistance to anticancer therapies. In this review, we summarize the current knowledge regarding metabolism-based mechanisms conferring adaptive resistance to chemo-, radio-and immunotherapies as well as targeted therapies. Furthermore, we report the role of TME-mediated intratumoral metabolic heterogeneity in therapy resistance and how adaptations in amino acid, glucose, and lipid metabolism support the growth of therapy-resistant cancers and/or cellular subpopulations. We also report the intricate interplay between tumor signaling and metabolic pathways in cancer cells and discuss how manipulating key metabolic enzymes and/or providing dietary changes may help to eradicate relapse-sustaining cancer cells. Finally, in the current era of personalized medicine, we describe the strategies that may be applied to implement metabolic profiling for tumor imaging, biomarker identification, selection of tailored treatments and monitoring therapy response during the clinical management of cancer patients.

Treating Metastatic Brain Cancers With Stem Cells

Stem cell therapy may present an effective treatment for metastatic brain cancer and glioblastoma. Here we posit the critical role of a leaky blood-brain barrier (BBB) as a key element for the development of brain metastases, specifically melanoma. By reviewing the immunological and inflammatory responses associated with BBB damage secondary to tumoral activity, we identify the involvement of this pathological process in the growth and formation of metastatic brain cancers. Likewise, we evaluate the hypothesis of regenerating impaired endothelial cells of the BBB and alleviating the damaged neurovascular unit to attenuate brain metastasis, using the endothelial progenitor cell (EPC) phenotype of bone marrow-derived mesenchymal stem cells. Specifically, there is a need to evaluate the efficacy for stem cell therapy to repair disruptions in the BBB and reduce inflammation in the brain, thereby causing attenuation of metastatic brain cancers. To establish the viability of stem cell therapy for the prevention and treatment of metastatic brain tumors, it is crucial to demonstrate BBB repair through augmentation of vasculogenesis and angiogenesis. BBB disruption is strongly linked to metastatic melanoma, worsens neuroinflammation during metastasis, and negatively influences the prognosis of metastatic brain cancer. Using stem cell therapy to interrupt inflammation secondary to this leaky BBB represents a paradigm-shifting approach for brain cancer treatment. In this review article, we critically assess the advantages and disadvantages of using stem cell therapy for brain metastases and glioblastoma.

Prognostic and predictive role of a metabolic rate-limiting enzyme signature in hepatocellular carcinoma

OBJECTIVES

Abnormal expression of metabolic rate-limiting enzymes drives the occurrence and progression of hepatocellular carcinoma (HCC). This study aimed to elucidate the comprehensive model of metabolic rate-limiting enzymes associated with the prognosis of HCC.

MATERIALS AND METHODS

HCC animal model and TCGA project were used to screen out differentially expressed metabolic rate-limiting enzyme. Cox regression, least absolute shrinkage and selection operation (LASSO) and experimentally verification were performed to identify metabolic rate-limiting enzyme signature. The area under the receiver operating characteristic curve (AUC) and prognostic nomogram were used to assess the efficacy of the signature in the three HCC cohorts (TCGA training cohort, internal cohort and an independent validation cohort).

RESULTS

A classifier based on three rate-limiting enzymes (RRM1, UCK2 and G6PD) was conducted and serves as independent prognostic factor. This effect was further confirmed in an independent cohort, which indicated that the AUC at year 5 was 0.715 (95% CI: 0.653-0.777) for clinical risk score, whereas it was significantly increased to 0.852 (95% CI: 0.798-0.906) when combination of the clinical with signature risk score. Moreover, a comprehensive nomogram including the signature and clinicopathological aspects resulted in significantly predict the individual outcomes.

CONCLUSIONS

Our results highlighted the prognostic value of rate-limiting enzymes in HCC, which may be useful for accurate risk assessment in guiding clinical management and treatment decisions.

Ref-1 redox activity alters cancer cell metabolism in pancreatic cancer: exploiting this novel finding as a potential target

BACKGROUND

Pancreatic cancer is a complex disease with a desmoplastic stroma, extreme hypoxia, and inherent resistance to therapy. Understanding the signaling and adaptive response of such an aggressive cancer is key to making advances in therapeutic efficacy. Redox factor-1 (Ref-1), a redox signaling protein, regulates the conversion of several transcription factors (TFs), including HIF-1α, STAT3 and NFκB from an oxidized to reduced state leading to enhancement of their DNA binding. In our previously published work, knockdown of Ref-1 under normoxia resulted in altered gene expression patterns on pathways including EIF2, protein kinase A, and mTOR. In this study, single cell RNA sequencing (scRNA-seq) and proteomics were used to explore the effects of Ref-1 on metabolic pathways under hypoxia.

METHODS

scRNA-seq comparing pancreatic cancer cells expressing less than 20% of the Ref-1 protein was analyzed using left truncated mixture Gaussian model and validated using proteomics and qRT-PCR. The identified Ref-1's role in mitochondrial function was confirmed using mitochondrial function assays, qRT-PCR, western blotting and NADP assay. Further, the effect of Ref-1 redox function inhibition against pancreatic cancer metabolism was assayed using 3D co-culture in vitro and xenograft studies in vivo.

RESULTS

Distinct transcriptional variation in central metabolism, cell cycle, apoptosis, immune response, and genes downstream of a series of signaling pathways and transcriptional regulatory factors were identified in Ref-1 knockdown vs Scrambled control from the scRNA-seq data. Mitochondrial DEG subsets downregulated with Ref-1 knockdown were significantly reduced following Ref-1 redox inhibition and more dramatically in combination with Devimistat in vitro. Mitochondrial function assays demonstrated that Ref-1 knockdown and Ref-1 redox signaling inhibition decreased utilization of TCA cycle substrates and slowed the growth of pancreatic cancer co-culture spheroids. In Ref-1 knockdown cells, a higher flux rate of NADP + consuming reactions was observed suggesting the less availability of NADP + and a higher level of oxidative stress in these cells. In vivo xenograft studies demonstrated that tumor reduction was potent with Ref-1 redox inhibitor similar to Devimistat.

CONCLUSION

Ref-1 redox signaling inhibition conclusively alters cancer cell metabolism by causing TCA cycle dysfunction while also reducing the pancreatic tumor growth in vitro as well as in vivo.

Targeting the replication stress response through synthetic lethal strategies in cancer medicine

The replication stress response (RSR) involves a downstream kinase cascade comprising ataxia telangiectasia-mutated (ATM), ATM and rad3-related (ATR), checkpoint kinases 1 and 2 (CHK1/2), and WEE1-like protein kinase (WEE1), which cooperate to arrest the cell cycle, protect stalled forks, and allow time for replication fork repair. In the presence of elevated replicative stress, cancers are increasingly dependent on RSR to maintain genomic integrity. An increasing number of drug candidates targeting key RSR nodes, as monotherapy through synthetic lethality, or through rational combinations with immune checkpoint inhibitors and targeted therapies, are demonstrating promising efficacy in early phase trials. RSR targeting is also showing potential in reversing PARP inhibitor resistance, an important area of unmet clinical need. In this review, we introduce the concept of targeting the RSR, detail the current landscape of monotherapy and combination strategies, and discuss emerging therapeutic approaches, such as targeting Polθ.

Synthesis and biological evaluation of 4-phenoxy-phenyl isoxazoles as novel acetyl-CoA carboxylase inhibitors

Acetyl-CoA carboxylase (ACC) is a crucial enzyme in fatty acid metabolism, which plays a major role in the occurrence and development of certain tumours. Herein, one potential ACC inhibitor (6a) was identified through high-throughput virtual screening (HTVS), and a series of 4-phenoxy-phenyl isoxazoles were synthesised for structure-activity relationship (SAR) studies. Among these compounds, 6g exhibited the most potent ACC inhibitory activity (IC₅₀=99.8 nM), which was comparable to that of CP-640186. Moreover, the antiproliferation assay revealed that compound 6l exhibited the strongest cytotoxicity, with IC₅₀ values of 0.22 µM (A549), 0.26 µM (HepG2), and 0.21 µM (MDA-MB-231), respectively. The preliminary mechanistic studies on 6g and 6l suggested that the compounds decreased the malonyl-CoA levels, arrested the cell cycle at the G0/G1 phase, and induced apoptosis in MDA-MB-231 cells. Overall, these results indicated that the 4-phenoxy-phenyl isoxazoles are potential for further study in cancer therapeutics as ACC inhibitors.

The redox-senescence axis and its therapeutic targeting

Significance

Cellular growth arrest, associated with ‘senescence’, helps to safeguard against the accumulation of DNA damage which is often recognized as the underlying mechanism of a wide variety of age-related pathologies including cancer. Cellular senescence has also been described as a ‘double-edged sword’. In cancer, for example, the creation of an immune-suppressive milieu by senescent tumor cells through the senescence-associated secretory phenotype contributes toward carcinogenesis and cancer progression.

Recent advances

The potential for cellular senescence to confer multi-faceted effects on tissue fate has led to a rejuvenated interest in its landscape and targeting. Interestingly, redox pathways have been described as both triggers and propagators of cellular senescence, leading to intricate cross-links between both pathways.

Critical issues

In this review, we describe the mechanisms driving cellular senescence, the interface with cellular redox metabolism as well as the role that chemotherapy-induced senescence plays in secondary carcinogenesis. Notably, the role that anti-apoptotic proteins of the Bcl-2 family play in inducing drug resistance via mechanisms that involve senescence induction.

Future directions

Though the therapeutic targeting of senescent cells as cancer therapy remains in its infancy, we summarize the current development of senotherapeutics, including recognized senotherapies, as well as the repurposing of drugs as senomorphic/senolytic candidates.

Development of antitumor biguanides targeting energy metabolism and stress responses in the tumor microenvironment

To develop antitumor drugs capable of targeting energy metabolism in the tumor microenvironment, we produced a series of potent new biguanide derivatives via structural modification of the arylbiguanide scaffold. We then conducted biological screening using hypoxia inducible factor (HIF)-1- and unfolded protein response (UPR)-dependent reporter assays and selective cytotoxicity assay under low glucose conditions. Homologation studies of aryl-(CH2)n-biguanides (n = 0-6) yielded highly potent derivatives with an appropriate alkylene linker length (n = 5, 6). The o-chlorophenyl derivative 7l (n = 5) indicated the most potent inhibitory effects on HIF-1- and UPR-mediated transcriptional activation (IC50; 1.0 ± 0.1 μM, 7.5 ± 0.1 μM, respectively) and exhibited selective cytotoxicity toward HT29 cells under low glucose condition (IC50; 1.9 ± 0.1 μM). Additionally, the protein expression of HIF-1α induced by hypoxia and of GRP78 and GRP94 induced by glucose starvation was markedly suppressed by the biguanides, thereby inhibiting angiogenesis. Metabolic flux and fluorescence-activated cell sorting analyses of tumor cells revealed that the biguanides strongly inhibited oxidative phosphorylation and activated compensative glycolysis in the presence of glucose, whereas both were strongly suppressed in the absence of glucose, resulting in cellular energy depletion and apoptosis. These findings suggest that the pleiotropic effects of these biguanides may contribute to more selective and effective killing of cancer cells due to the suppression of various stress adaptation systems in the tumor microenvironment.

TFEB Supports Pancreatic Cancer Growth through the Transcriptional Regulation of Glutaminase

Transcription factor EB (TFEB) is a master regulator of lysosomal function and autophagy. In addition, TFEB has various physiological roles such as nutrient sensing, cellular stress responses, and immune responses. However, the precise roles of TFEB in pancreatic cancer growth remain unclear. Here, we show that pancreatic cancer cells exhibit a significantly elevated TFEB expression compared with normal tissue samples and that the genetic inhibition of TFEB results in a significant inhibition in both glutamine and mitochondrial metabolism, which in turn suppresses the PDAC growth both in vitro and in vivo. High basal levels of autophagy are critical for pancreatic cancer growth. The TFEB knockdown had no significant effect on the autophagic flux under normal conditions but interestingly caused a profound reduction in glutaminase (GLS) transcription, leading to an inhibition of glutamine metabolism. We observed that the direct binding of TFEB to the GLS and TFEB gene promotors regulates the transcription of GLS. We also found that the glutamate supplementation leads to a significant recovery of the PDAC growth that had been reduced by a TFEB knockdown. Taken together, our current data demonstrate that TFEB supports the PDAC cell growth by regulating glutaminase-mediated glutamine metabolism.

Metformin: Metabolic Rewiring Faces Tumor Heterogeneity

Tumor heterogeneity impinges on all the aspects of tumor history, from onset to metastasis and relapse. It is growingly recognized as a propelling force for tumor adaptation to environmental and micro-environmental cues. Metabolic heterogeneity perfectly falls into this process. It strongly contributes to the metabolic plasticity which characterizes cancer cell subpopulations-capable of adaptive switching under stress conditions, between aerobic glycolysis and oxidative phosphorylation-in both a convergent and divergent modality. The mitochondria appear at center-stage in this adaptive process and thus, targeting mitochondria in cancer may prove of therapeutic value. Metformin is the oldest and most used anti-diabetic medication and its relationship with cancer has witnessed rises and falls in the last 30 years. We believe it is useful to revisit the main mechanisms of action of metformin in light of the emerging views on tumor heterogeneity. We first analyze the most consolidated view of its mitochondrial mechanism of action and then we frame the latter in the context of tumor adaptive strategies, cancer stem cell selection, metabolic zonation of tumors and the tumor microenvironment. This may provide a more critical point of view and, to some extent, may help to shed light on some of the controversial evidence for metformin's anticancer action.

Exploiting replicative stress in gynecological cancers as a therapeutic strategy

Elevated levels of replicative stress in gynecological cancers arising from uncontrolled oncogenic activation, loss of key tumor suppressors, and frequent defects in the DNA repair machinery are an intrinsic vulnerability for therapeutic exploitation. The presence of replication stress activates the DNA damage response and downstream checkpoint proteins including ataxia telangiectasia and Rad3 related kinase (ATR), checkpoint kinase 1 (CHK1), and WEE1-like protein kinase (WEE1), which trigger cell cycle arrest while protecting and restoring stalled replication forks. Strategies that increase replicative stress while lowering cell cycle checkpoint thresholds may allow unrepaired DNA damage to be inappropriately carried forward in replicating cells, leading to mitotic catastrophe and cell death. Moreover, the identification of fork protection as a key mechanism of resistance to chemo- and poly (ADP-ribose) polymerase inhibitor therapy in ovarian cancer further increases the priority that should be accorded to the development of strategies targeting replicative stress. Small molecule inhibitors designed to target the DNA damage sensors, such as inhibitors of ataxia telangiectasia-mutated (ATM), ATR, CHK1 and WEE1, impair smooth cell cycle modulation and disrupt efficient DNA repair, or a combination of the above, have demonstrated interesting monotherapy and combinatorial activity, including the potential to reverse drug resistance and have entered developmental pipelines. Yet unresolved challenges lie in balancing the toxicity profile of these drugs in order to achieve a suitable therapeutic index while maintaining clinical efficacy, and selective biomarkers are urgently required. Here we describe the premise for targeting of replicative stress in gynecological cancers and discuss the clinical advancement of this strategy.

Inhibition of pyruvate dehydrogenase kinase‑1 by dicoumarol enhances the sensitivity of hepatocellular carcinoma cells to oxaliplatin via metabolic reprogramming

The Warburg effect is a unique metabolic feature of the majority of tumor cells and is closely related to chemotherapeutic resistance. Pyruvate dehydrogenase kinase 1 (PDK1) is considered a 'switch' that controls the fate of pyruvate in glucose metabolism. However, to date, to the best of our knowledge, there are only a few studies to available which had studied the reduction of chemotherapeutic resistance via the metabolic reprogramming of tumor cells with PDK1 as a target. In the present study, it was found dicoumarol (DIC) reduced the phosphorylation of pyruvate dehydrogenase (PDH) by inhibiting the activity of PDK1, which converted the metabolism of human hepatocellular carcinoma (HCC) cells to oxidative phosphorylation, leading to an increase in mitochondrial reactive oxygen species ROS (mtROS) and a decrease in mitochondrial membrane potential (MMP), thereby increasing the apoptosis induced by oxaliplatin (OXA). Furthermore, the present study elucidated that the targeting of PDK1 may be a potential strategy for targeting metabolism in the chemotherapy of HCC. In addition, DIC as an 'old drug' exhibits novel efficacy, bringing new hope for antitumor therapy.

Dual inhibition of glycolysis and autophagy as a therapeutic strategy in the treatment of Ehrlich ascites carcinoma

Cancer cells have extra biosynthetic demands to sustain cell growth and redox homeostasis. Glycolysis and autophagy are crucial to fuel and recycle these biosynthetic demands. This plasticity of cancer cell metabolism participates in therapy resistances. The current study was designed to assess the therapeutic efficacy of dual targeting of glycolysis and autophagy in cancer. Using 3-bromopyruvate (3-BP; antiglycolytic inhibitor) and hydroxychloroquine (HCQ; autophagy inhibitor), we demonstrate their antitumor activity in Ehrlich ascites carcinoma (EAC)-bearing mice. A combination of 3-BP and HCQ significantly decreases tumor ascitic volume and cell count as compared with the EAC group and individual treatment groups. The enhanced antitumor activity is accompanied by hexokinase inactivation, inhibition of cellular protective autophagy, elevated antioxidant activity, and reduced oxidative stress levels. Together, these results suggest targeting both pathways in cancer as an effective therapeutic strategy. Further studies are required to validate this strategy in different cancer models and preclinical trials.