NAD- and NADPH-Contributing Enzymes as Therapeutic Targets in Cancer: An Overview

A comparative study on the dose-effect of low-dose radiation based on microdosimetric analysis and single-cell sequencing technology

The biological mechanisms triggered by low-dose exposure still need to be explored in depth. In this study, the potential mechanisms of low-dose radiation when irradiating the BEAS-2B cell lines with a Cs-137 gamma-ray source were investigated through simulations and experiments. Monolayer cell population models were constructed for simulating and analyzing distributions of nucleus-specific energy within cell populations combined with the Monte Carlo method and microdosimetric analysis. Furthermore, the 10 × Genomics single-cell sequencing technology was employed to capture the heterogeneity of individual cell responses to low-dose radiation in the same irradiated sample. The numerical uncertainties can be found both in the specific energy distribution in microdosimetry and in differential gene expressions in radiation cytogenetics. Subsequently, the distribution of nucleus-specific energy was compared with the distribution of differential gene expressions to guide the selection of differential genes bioinformatics analysis. Dose inhomogeneity is pronounced at low doses, where an increase in dose corresponds to a decrease in the dispersion of cellular-specific energy distribution. Multiple screening of differential genes by microdosimetric features and statistical analysis indicate a number of potential pathways induced by low-dose exposure. It also provides a novel perspective on the selection of sensitive biomarkers that respond to low-dose radiation.

WWP2 Regulates Renal Fibrosis and the Metabolic Reprogramming of Profibrotic Myofibroblasts

Key Points

Background

Renal fibrosis is a common pathologic end point in CKD that is challenging to reverse, and myofibroblasts are responsible for the accumulation of a fibrillar collagen–rich extracellular matrix. Recent studies have unveiled myofibroblasts' diversity in proliferative and fibrotic characteristics, which are linked to different metabolic states. We previously demonstrated the regulation of extracellular matrix genes and tissue fibrosis by WWP2, a multifunctional E3 ubiquitin–protein ligase. Here, we investigate WWP2 in renal fibrosis and in the metabolic reprograming of myofibroblasts in CKD.

Methods

We used kidney samples from patients with CKD and WWP2-null kidney disease mice models and leveraged single-cell RNA sequencing analysis to detail the cell-specific regulation of WWP2 in fibrotic kidneys. Experiments in primary cultured myofibroblasts by bulk-RNA sequencing, chromatin immunoprecipitation sequencing, metabolomics, and cellular metabolism assays were used to study the metabolic regulation of WWP2 and its downstream signaling.

Results

The tubulointerstitial expression of WWP2 was associated with fibrotic progression in patients with CKD and in murine kidney disease models. WWP2 deficiency promoted myofibroblast proliferation and halted profibrotic activation, reducing the severity of renal fibrosis in vivo. In renal myofibroblasts, WWP2 deficiency increased fatty acid oxidation and activated the pentose phosphate pathway, boosting mitochondrial respiration at the expense of glycolysis. WWP2 suppressed the transcription of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), a metabolic mediator of fibrotic response, and pharmacologic inhibition of PGC-1α partially abrogated the protective effects of WWP2 deficiency on myofibroblasts.

Conclusions

WWP2 regulates the metabolic reprogramming of profibrotic myofibroblasts by a WWP2-PGC-1α axis, and WWP2 deficiency protects against renal fibrosis in CKD.

Comprehensive analysis of a NAD+ metabolism-derived gene signature to predict the prognosis and immune landscape in endometrial cancer

As a crucial regulator influencing tumor progression, nicotinamide adenine dinucleotide (NAD+) is widely acknowledged. However, its role in endometrial cancer (EC) is not completely understood. In this study, we aimed to develop an NAD+metabolic-related genes (NMRGs) risk signature that could reflect the prognosis of EC patients and their responsiveness to immunotherapy and chemotherapy. Data from The Cancer Genome Atlas (TCGA) databases and the Molecular Signatures Database (MSigDB) confirmed two distinct NMRG subtypes in EC patients using consensus clustering, and a risk score was constructed utilizing an NAD+-related prognostic signature depending on the least absolute shrinkage and selection operator (LASSO) Cox regression analysis. Receiver operating characteristic (ROC) curves were employed to assess the model's precision. Additionally, we used Gene Set Enrichment Analysis (GSEA) to predict the biological signaling pathways that might be involved. We also explored the role of the risk score in immune cell infiltration, tumor mutation burden (TMB), immunotherapy, and chemotherapy. Our study established a prognostic risk signature based on six NMRGs, and we observed that the high-risk group was associated with a poorer prognosis. Furthermore, we identified a strong correlation between the high-risk group and several pathways, including DNA replication, cell cycle, and mismatch repair. Lastly, our findings highlighted the influence of NMRGs on the regulation of immune infiltration in EC. Therefore, this signature holds potential value in predicting the prognosis of EC patients and guiding their management, including decisions regarding immunotherapy and chemotherapy, ultimately improving the accuracy of EC patient care.

CircRNA-regulated glucose metabolism in ovarian cancer: an emerging landscape for therapeutic intervention

Ovarian cancer (OC) has the highest mortality rate among female reproductive system tumours, with limited efficacy of traditional treatments and 5-year survival rates that rarely exceed 40%. Circular RNA (circRNA) is a stable endogenous circular RNA that typically regulates protein expression by binding to downstream miRNA. It has been demonstrated that circRNAs play an important role in the proliferation, migration, and glucose metabolism (such as the Warburg effect) of OC and can regulate the expression of glucose metabolism-related proteins such as GLUT1 and HK2, promoting anaerobic glycolysis of cancer cells, increasing glucose uptake and ATP production, and affecting energy supply and biosynthetic substances to support tumour growth and invasion. This review summarises the formation and characteristics of circRNAs and focuses on their role in regulating glucose metabolism in OC cells and their potential therapeutic value, providing insights for identifying new therapeutic targets.

Inhibitors of NAD+ Production in Cancer Treatment: State of the Art and Perspectives

The addiction of tumors to elevated nicotinamide adenine dinucleotide (NAD+) levels is a hallmark of cancer metabolism. Obstructing NAD+ biosynthesis in tumors is a new and promising antineoplastic strategy. Inhibitors developed against nicotinamide phosphoribosyltransferase (NAMPT), the main enzyme in NAD+ production from nicotinamide, elicited robust anticancer activity in preclinical models but not in patients, implying that other NAD+-biosynthetic pathways are also active in tumors and provide sufficient NAD+ amounts despite NAMPT obstruction. Recent studies show that NAD+ biosynthesis through the so-called "Preiss-Handler (PH) pathway", which utilizes nicotinate as a precursor, actively operates in many tumors and accounts for tumor resistance to NAMPT inhibitors. The PH pathway consists of three sequential enzymatic steps that are catalyzed by nicotinate phosphoribosyltransferase (NAPRT), nicotinamide mononucleotide adenylyltransferases (NMNATs), and NAD+ synthetase (NADSYN1). Here, we focus on these enzymes as emerging targets in cancer drug discovery, summarizing their reported inhibitors and describing their current or potential exploitation as anticancer agents. Finally, we also focus on additional NAD+-producing enzymes acting in alternative NAD+-producing routes that could also be relevant in tumors and thus become viable targets for drug discovery.

Sensitive monitoring of NAD(P)H levels within cancer cells using mitochondria-targeted near-infrared cyanine dyes with optimized electron-withdrawing acceptors

A series of near-infrared fluorescent probes, labeled A to E, were developed by combining electron-rich thiophene and 3,4-ethylenedioxythiophene bridges with 3-quinolinium and various electron deficient groups, enabling the sensing of NAD(P)H. Probes A and B exhibit absorptions and emissions in the near-infrared range, offering advantages such as minimal interference from autofluorescence, negligible photo impairment in cells and tissues, and exceptional tissue penetration. These probes show negligible fluorescence when NADH is not present, and their absorption maxima are at 438 nm and 470 nm, respectively. In contrast, probes C-E feature absorption maxima at 450, 334 and 581 nm, respectively. Added NADH triggers the transformation of the electron-deficient 3-quinolinium units into electron-rich 1,4-dihydroquinoline units resulting in fluorescence responses which were established at 748, 730, 575, 625 and 661 for probes AH-EH, respectively, at detection limits of 0.15 μM and 0.07 μM for probes A and B, respectively. Optimized geometries based on theoretical calculations reveal non-planar geometries for probes A-E due to twisting of the 3-quinolinium and benzothiazolium units bonded to the central thiophene group, which all attain planarity upon addition of hydride resulting in absorption and fluorescence in the near-IR region for probes AH and BH in contrast to probes CH-EH which depict fluorescence in the visible range. Probe A has been successfully employed to monitor NAD(P)H levels in glycolysis and specific mitochondrial targeting. Furthermore, it has been used to assess the influence of lactate and pyruvate on the levels of NAD(P)H, to explore how hypoxia in cancer cells can elevate levels of NAD(P)H, and to visualize changes in levels of NAD(P)H under hypoxic conditions with CoCl2 treatment. Additionally, probe A has facilitated the examination of the potential impact of chemotherapy drugs, namely gemcitabine, camptothecin, and cisplatin, on metabolic processes and energy generation within cancer cells by affecting NAD(P)H levels. Treatment of A549 cancer cells with these drugs has been shown to increase NAD(P)H levels, which may contribute to their anticancer effects ultimately leading to programmed cell death or apoptosis. Moreover, probe A has been successfully employed in monitoring NAD(P)H level changes in D. melanogaster larvae treated with cisplatin.

The Role of Nicotinamide as Chemo-Preventive Agent in NMSCs: A Systematic Review and Meta-Analysis

BACKGROUND

Nicotinamide is the active form of vitamin B3 (niacin) obtained through endogenous synthesis, mainly through tryptophan metabolism and dietary supplements, fish, meats, grains, and dairy products. It participates in cellular energy metabolism and modulates multiple cellular survival and death pathways. Nicotinamide has been widely studied as a safe chemopreventive agent that reduces actinic keratosis (AKs) and non-melanoma skin cancers (NMSC).

METHODS

We used the Medline, EMBASE, PubMed, and Cochrane databases to search the concepts "nicotinamide", "chemoprevention", and "skin cancer" up to August 2023. Three independent authors screened titles and abstracts for intervention and study design before searching full texts for eligibility criteria. The primary outcome was the impact of oral nicotinamide on the incidence of NMSC in high-risk patients. We also conducted a systematic search to identify relevant epidemiological studies published evaluating dietary niacin intake and the risk of NMSC.

RESULTS

Two hundred and twenty-five studies were reviewed, and four met the inclusion criteria. There was no association between NAM consumption and risk for squamous cell carcinoma (SCC) (rate ratio (RR) 0.81, 95% CI 0.48-1.37; I2 = 0%), basal cell carcinoma (BCC) (RR 0.88, 95% CI 0.50-1.55; I2 = 63%), and NMSC (RR 0.82, 95% CI 0.61-1.12; I2 = 63%). Adverse events were rare and acceptable, allowing optimal compliance of patients to the treatment. We found only one article evaluating the association between niacin dietary intake and NMSC risk, supporting a potential beneficial role of niacin intake concerning SCC but not BCC or melanoma.

CONCLUSIONS

The present meta-analysis shows, by pooling immunocompetent and immunosuppressed patients, that there is insufficient evidence that oral nicotinamide therapy significantly reduces the number of keratinocyte cancers.

NADPH Dynamics: Linking Insulin Resistance and β-Cells Ferroptosis in Diabetes Mellitus

This review offers an in-depth exploration of Nicotinamide Adenine Dinucleotide Phosphate (NADPH) in metabolic health. It delves into how NADPH affects insulin secretion, influences insulin resistance, and plays a role in ferroptosis. NADPH, a critical cofactor in cellular antioxidant systems and lipid synthesis, plays a central role in maintaining metabolic homeostasis. In adipocytes and skeletal muscle, NADPH influences the pathophysiology of insulin resistance, a hallmark of metabolic disorders such as type 2 diabetes and obesity. The review explores the mechanisms by which NADPH contributes to or mitigates insulin resistance, including its role in lipid and reactive oxygen species (ROS) metabolism. Parallelly, the paper investigates the dual nature of NADPH in the context of pancreatic β-cell health, particularly in its relation to ferroptosis, an iron-dependent form of programmed cell death. While NADPH's antioxidative properties are crucial for preventing oxidative damage in β-cells, its involvement in lipid metabolism can potentiate ferroptotic pathways under certain pathological conditions. This complex relationship underscores the delicate balance of NADPH homeostasis in pancreatic health and diabetes pathogenesis. By integrating findings from recent studies, this review aims to illuminate the nuanced roles of NADPH in different tissues and its potential as a therapeutic target. Understanding these dynamics offers vital insights into the development of more effective strategies for managing insulin resistance and preserving pancreatic β-cell function, thereby advancing the treatment of metabolic diseases.

Folate trapping is lethal to cancer cells

Regulation of formate flux by a key folate enzyme, MTHFD2 (methylene tetrahydrofolate dehydrogenase 2) in cancer cells remains poorly understood. Green et al. (Nature Metabolism, 2023; 5: 642-659) showed an interesting phenomenon of "folate trapping" toxicity leads to cancer cell kill using a potent inhibitor (TH9619) against the dehydrogenase and cyclohydrolase (DC) activities of cytosolic methylenetetrahydrofolate dehydrogenase 1 (cMTHFD1) and nuclear methylenetetrahydrofolate dehydrogenase 2 (nMTHFD2), but not the mitochondrial MTHFD2 (mTHFD2). But, mMTHFD2 is required for formate flow to cytosol which leads to the trapping of 10-formyl tetrahydrofolate and causes toxicity by TH9619 treatment, to kill cancer cells expressing mMTHFD2. This article opens new avenues to be evaluated for therapeutic benefits of cancer patients where MTHFD2 shows overexpression viz-a-viz breast, prostate, colorectal, acute myeloid leukemia, and other cancer types.

Cytosolic malic enzyme and glucose-6-phosphate dehydrogenase modulate redox balance in NSCLC with acquired drug resistance

Lung cancer cells often show elevated levels of reactive oxygen species (ROS) and nicotinamide adenine dinucleotide phosphate (NADPH). However, the connections between deregulated redox homeostasis in different subtypes of lung cancer and acquired drug resistance in lung cancer have not yet been fully established. Herein, we analyzed different subtypes of lung cancer data reported in the Cancer Cell Line Encyclopedia (CCLE) database, the Cancer Genome Atlas program (TCGA), and the sequencing data obtained from a gefitinib-resistant non-small-cell lung cancer (NSCLC) cell line (H1975GR). Using flux balance analysis (FBA) model integrated with multiomics data and gene expression profiles, we identified cytosolic malic enzyme 1 (ME1) and glucose-6-phosphate dehydrogenase as the major contributors to the significantly upregulated NADPH flux in NSCLC tissues as compared with normal lung tissues, and gefitinib-resistant NSCLC cell line as compared with the parental cell line. Silencing the gene expression of either of these two enzymes in two osimertinib-resistant NSCLC cell lines (H1975OR and HCC827OR) exhibited strong antiproliferative effects. Our findings not only underscored the pivotal roles of cytosolic ME1 and glucose-6-phosphate dehydrogenase in regulating redox states in NSCLC cells but also provided novel insights into their potential roles in drug-resistant NSCLC cells with disturbed redox states.

Nitrogen-15 dynamic nuclear polarization of nicotinamide derivatives in biocompatible solutions

Dissolution dynamic nuclear polarization (dDNP) increases the sensitivity of magnetic resonance imaging by more than 10,000 times, enabling in vivo metabolic imaging to be performed noninvasively in real time. Here, we are developing a group of dDNP polarized tracers based on nicotinamide (NAM). We synthesized 1-15N-NAM and 1-15N nicotinic acid and hyperpolarized them with dDNP, reaching (13.0 ± 1.9)% 15N polarization. We found that the lifetime of hyperpolarized 1-15N-NAM is strongly field- and pH-dependent, with T1 being as long as 41 s at a pH of 12 and 1 T while as short as a few seconds at neutral pH and fields below 1 T. The remarkably short 1-15N lifetime at low magnetic fields and neutral pH drove us to establish a unique pH neutralization procedure. Using 15N dDNP and an inexpensive rodent imaging probe designed in-house, we acquired a 15N MRI of 1-15N-NAM (previously hyperpolarized for more than an hour) in less than 1 s.

SLC25A51 promotes tumor growth through sustaining mitochondria acetylation homeostasis and proline biogenesis

Solute carrier family 25 member 51 (SLC25A51) was recently identified as the mammalian mitochondrial NAD+ transporter essential for mitochondria functions. However, the role of SLC25A51 in human disease, such as cancer, remains undefined. Here, we report that SLC25A51 is upregulated in multiple cancers, which promotes cancer cells proliferation. Loss of SLC25A51 elevates the mitochondrial proteins acetylation levels due to SIRT3 dysfunctions, leading to the impairment of P5CS enzymatic activity, which is the key enzyme in proline biogenesis, and the reduction in proline contents. Notably, we find fludarabine phosphate, an FDA-approved drug, is able to bind with and inhibit SLC25A51 functions, causing mitochondrial NAD+ decrease and proteins hyperacetylation, which could further synergize with aspirin to reinforce the anti-tumor efficacy. Our study reveals that SLC25A51 is an attractive anti-cancer target, and provides a novel drug combination of fludarabine phosphate with aspirin as a potential cancer therapy strategy.

Nanoparticle-Based Antioxidants in Stress Signaling and Programmed Cell Death in Breast Cancer Treatment

Breast cancer (BC) is a complex and heterogeneous disease, and oxidative stress is a hallmark of BC. Oxidative stress is characterized by an imbalance between the production of reactive oxygen species (ROS) and antioxidant defense mechanisms. ROS has been implicated in BC development and progression by inducing DNA damage, inflammation, and angiogenesis. Antioxidants have been shown to scavenge ROS and protect cells from oxidative damage, thereby regulating signaling pathways involved in cell growth, survival, and death. Plants contain antioxidants like ascorbic acid, tocopherols, carotenoids, and flavonoids, which have been found to regulate stress signaling and PCD in BC. Combining different antioxidants has shown promise in enhancing the effectiveness of BC treatment. Antioxidant nanoparticles, when loaded with antioxidants, can effectively target breast cancer cells and enhance their cellular uptake. Notably, these nanoparticles have shown promising results in inducing PCD and sensitizing breast cancer cells to chemotherapy, even in cases where resistance is observed. This review aims to explore how nanotechnology can modulate stress signaling and PCD in breast cancer. By summarizing current research, it underscores the potential of nanotechnology in enhancing antioxidant properties for the treatment of breast cancer.

The Role of Selected Adipocytokines in Ovarian Cancer and Endometrial Cancer

Due to their multidirectional influence, adipocytokines are currently the subject of numerous intensive studies. Significant impact applies to many processes, both physiological and pathological. Moreover, the role of adipocytokines in carcinogenesis seems particularly interesting and not fully understood. For this reason, ongoing research focuses on the role of these compounds in the network of interactions in the tumor microenvironment. Particular attention should be drawn to cancers that remain challenging for modern gynecological oncology-ovarian and endometrial cancer. This paper presents the role of selected adipocytokines, including leptin, adiponectin, visfatin, resistin, apelin, chemerin, omentin and vaspin in cancer, with a particular focus on ovarian and endometrial cancer, and their potential clinical relevance.

Fluorescent and theranostic probes for imaging nicotinamide phosphoribosyl transferase (NAMPT)

Nicotinamide phosphoribosyl transferase (NAMPT) has been regarded as an attractive target for cancer therapy. However, there is a lack of chemical tools for real-time visualization and detection of NAMPT. Herein, the first fluorescent and theranostic probes were designed for imaging NAMPT, which had dual functions of diagnosis and treatment. The designed probes possessed good affinity and environmental sensitivity to NAMPT with a turn-on mechanism and were successfully applied in fluorescence detecting and imaging of NAMPT at the level of living cells and tissue sections. They also effectively inhibited tumor cell proliferation and arrested cell cycle at the G2 phase. These fluorescent probes enabled detection and visualization of NAMPT, representing effective chemical tools for the pathological diagnosis and treatment of cancer.

TNFα-induced IDH1 hyperacetylation reprograms redox homeostasis and promotes the chemotherapeutic sensitivity

The heterogeneity and drug resistance of colorectal cancer (CRC) often lead to treatment failure. Isocitrate dehydrogenase 1 (IDH1), a rate-limiting enzyme in the tricarboxylic acid cycle, regulates the intracellular redox environment and mediates tumor cell resistance to chemotherapeutic drugs. The aim of this study was to elucidate the mechanism underlying the involvement of IDH1 acetylation in the development of CRC drug resistance under induction of TNFα. We found TNFα disrupted the interaction between SIRT1 and IDH1 and increased the level of acetylation at K115 of IDH1. Hyperacetylation of K115 was accompanied by protein ubiquitination, which increased its susceptibility to degradation compared to IDH1 K115R. TNFα-mediated hyperacetylation of K115 sensitized the CRC cells to 5FU and reduced the NADPH/NADP ratio to that of intracellular ROS. Furthermore, TNFα and 5FU inhibited CRC tumor growth in vivo, while the K115R-expressing tumor tissues developed 5FU resistance. In human CRC tissues, K115 acetylation was positively correlated with TNFα infiltration, and K115 hyperacetylation was associated with favorable prognosis compared to chemotherapy-induced deacetylation. Therefore, TNFα-induced hyperacetylation at the K115 site of IDH1 promotes antitumor redox homeostasis in CRC cells, and can be used as a marker to predict the response of CRC patients to chemotherapy.

Immunohistochemical Analysis of Nicotinamide Phosphoribosyltransferase Expression in Gastric and Esophageal Adenocarcinoma (AEG)

Nicotinamide phosphoribosyltransferase (NAMPT) represents a major component in cellular energy metabolism, which is also crucial for cancer cells that have elevated aerobic glycolysis; moreover, targeting the NAD salvage pathway by inhibition of NAMPT was shown effective in a subgroup of gastric cancer cell lines. In order to study the expression levels of NAMPT in adenocarcinoma of the esophagogastric junction and stomach (AEG/S) we performed immunohistochemical analysis in a cohort of 296 tumor samples using tissue-microarrays (TMAs). In the present investigation, we saw a high expression of NAMPT in only a minority of our large AEG/S cohort. Although we did not find a correlation between NAMPT expression and survival, subgroup analysis showed that NAMPT expression was more frequent in older patients (>65 years, p = 0.049) and was associated with a numerical shorter survival that did not reach statistical significance within this age group. In conclusion, we did not find significance for any prognostic effect of NAMPT in our AEG/S cohort; however, the evaluation of other NAD metabolic enzymes is needed as molecular predictors of response to potential NAMPT inhibition in the treatment of patients with AEG/S.

Gankyrin and TIGAR cooperatively accelerate glucose metabolism toward the PPP and TCA cycle in hepatocellular carcinoma

Oncogene-derived metabolic reprogramming is important for anabolic growth of cancer cells, which is now considered to be not simply rely on glycolysis. Pentose phosphate pathway and tricarboxylic acid cycle also play pivotal roles in helping cancer cells to meet their anabolic and energy demands. The present work focused on gankyrin, a relatively specific oncogene in hepatocellular carcinoma (HCC), and its impact on glycolysis and mitochondrial homeostasis. Metabolomics, RNA-seq analysis, and subsequent conjoint analysis illustrated that gankyrin regulated the pentose phosphate pathway (PPP), tricarboxylic acid (TCA) cycle, and mitochondrial function and homeostasis, which play pivotal roles in tumor development. Mechanistically, gankyrin was found to modulate HCC metabolic reprogramming via TIGAR. Gankyrin positively regulated the transcription of TIGAR through Nrf2, which bound to the antioxidant response elements (AREs) in the promoter of TIGAR. Interestingly, TIGAR feedback regulated the transcription of Nrf2 and subsequently gankyrin by promoting nuclear importation of PGC1α. The loop between gankyrin, Nrf2, and TIGAR accelerated glucose metabolism toward the PPP and TCA cycle, which provided vital building blocks, such as NADPH, ATP, and ribose of tumor and further facilitated the progression of HCC.

Clinical stratification improves the diagnostic accuracy of small omics datasets within machine learning and genome-scale metabolic modelling methods

BACKGROUND

Recently, multi-omic machine learning architectures have been proposed for the early detection of cancer. However, for rare cancers and their associated small datasets, it is still unclear how to use the available multi-omics data to achieve a mechanistic prediction of cancer onset and progression, due to the limited data available. Hepatoblastoma is the most frequent liver cancer in infancy and childhood, and whose incidence has been lately increasing in several developed countries. Even though some studies have been conducted to understand the causes of its onset and discover potential biomarkers, the role of metabolic rewiring has not been investigated in depth so far.

METHODS

Here, we propose and implement an interpretable multi-omics pipeline that combines mechanistic knowledge from genome-scale metabolic models with machine learning algorithms, and we use it to characterise the underlying mechanisms controlling hepatoblastoma.

RESULTS AND CONCLUSIONS

While the obtained machine learning models generally present a high diagnostic classification accuracy, our results show that the type of omics combinations used as input to the machine learning models strongly affects the detection of important genes, reactions and metabolic pathways linked to hepatoblastoma. Our method also suggests that, in the context of computer-aided diagnosis of cancer, optimal diagnostic accuracy can be achieved by adopting a combination of omics that depends on the patient's clinical characteristics.

Transcriptome Sequencing Analysis of circRNA in Skeletal Muscle between Fast- and Slow-Growing Chickens at Embryonic Stages

Skeletal muscle growth has always been the focus of the broiler industry, and circRNAs play a significant role in this process. We collected leg muscles of slow- and fast-growing Bian chicken embryos in the study at 14 (S14 and F14) and 20 (S20 and F20) days for RNA-seq. Finally, 123 and 121 differentially expressed circRNAs (DECs) were identified in S14 vs. F14 and S20 vs. F20, respectively. GO enrichment analysis for DECs obtained important biological process (BP) terms including nicotinate nucleotide biosynthetic process, nicotinate nucleotide salvage, and NAD salvage in S20 vs. F20 and protein mannosylation in S14 vs. F14. KEGG pathway analysis showed Wnt signaling pathway, Tight junction, Ubiquitin mediated proteolysis, and Notch signaling pathway were enriched in the top 20. Based on the GO and KEGG analysis results, we found some significant host genes and circRNAs such as NAPRT and novel_circ_0004547, DVL1 and novel_circ_0003578, JAK2 and novel_circ_0010289, DERA and novel_circ_0003082, etc. Further analysis found 19 co-differentially expressed circRNAs between the two comparison groups. We next constructed a circRNA-miRNA network for them, and some candidate circRNA-miRNA pairs related to skeletal muscle were obtained, such as novel_circ_0002153-miR-12219-5p, novel_circ_0003578-miR-3064-3p, and novel_circ_0010661-miR-12260-3p. These results would help to reveal the mechanism for circRNAs in skeletal muscle and also provide some guidance for the breeding of broilers.

(-)-Epigallocatechin Gallate is a Noncompetitive Inhibitor of NAD Kinase

Nicotinamide adenine dinucleotide kinase (NADK) controls the intracellular NADPH content and provides reducing power for the synthesis of macromolecules and anti-ROS. Moreover, NADK is considered to be a synthetic lethal gene for KRAS mutations. To discover NADK-targeted probes, a high-throughput screening assay was established and optimized with a Z factor of 0.71. The natural product (-)-epigallocatechin gallate (EGCG) was found to be a noncompetitive inhibitor of NADK with K i = 3.28 ± 0.32 μΜ. The direct binding of EGCG to NADK was determined by several biophysical methods, including NMR spectroscopy, surface plasmon resonance (SPR) assay, and hydrogen-deuterium exchange mass spectrometry (HDX-MS). The SPR assay showed a K d of 1.78 ± 1.15 μΜ. The HDX-MS experiment showed that EGCG was bound at the non-substrate-binding sites of NADK. Besides, binding mode prediction and derivative activity analysis revealed a potential structure-activity relationship between EGCG and NADK. Furthermore, EGCG can specifically inhibit the proliferation of KRAS-mutated lung cancer cell lines without affecting KRAS wild-type lung cancer cell lines.

Review of various NAMPT inhibitors for the treatment of cancer

Nicotinamide phosphoribosyltransferase (NAMPT) is a rate-limiting enzyme in the NAD salvage pathway of mammalian cells and is overexpressed in numerous types of cancers. These include breast cancer, ovarian cancer, prostate cancer, gastric cancer, colorectal cancer, glioma, and b-cell lymphoma. NAMPT is also known to impact the NAD and NADPH pool. Research has demonstrated that NAMPT can be inhibited. NAMPT inhibitors are diverse anticancer medicines with significant anti-tumor efficacy in ex vivo tumor models. A few notable NAMPT specific inhibitors which have been produced include FK866, CHS828, and OT-82. Despite encouraging preclinical evidence of the potential utility of NAMPT inhibitors in cancer models, early clinical trials have yielded only modest results, necessitating the adaptation of additional tactics to boost efficacy. This paper examines a number of cancer treatment methods which target NAMPT, including the usage of individual inhibitors, pharmacological combinations, dual inhibitors, and ADCs, all of which have demonstrated promising experimental or clinical results. We intend to contribute further ideas regarding the usage and development of NAMPT inhibitors in clinical therapy to advance the field of research on this intriguing target.

KIF11 manipulates SREBP2-dependent mevalonate cross talk to promote tumor progression in pancreatic ductal adenocarcinoma

Cholesterol metabolism is highly correlated with risks of pancreatic ductal adenocarcinoma (PDAC). Nevertheless, the underlying mechanisms of activation of cholesterol biogenesis remain inconclusive. KIF11 is a key component of the bipolar spindle and expresses highly in various malignancies. However, its functional role in PDAC tumorigenesis is still unclear. This study aims to elucidate the oncogenic functions of KIF11 in stimulating cholesterol metabolism, thereby driving PDAC progression. We utilized bioinformatics analysis to identify that KIF11 expressed highly in tumor samples versus paired normal tissues and high KIF11 correlated with high clinical stages of patients. Patients with high KIF11 had worse survival outcomes relative to those with low KIF11. Gene set enrichment analysis (GSEA) revealed that KIF11 correlated intensively with the mevalonate (MVA) metabolic pathway. Positive associations were observed between KIF11 and MVA-signature (HMGCR, FDFT1, SQLE, and MSMO1). KIF11 could elevate the free cholesterol content of PDAC cells and targeting MVA inhibited the in vitro growth of KIF11-overexpressing cells. Mechanistically, we found KIF11 could interact with SREBP2, the master regulator of MVA. High KIF11 could increase SREBP2 proteins, but not alter their mRNA levels. KIF11 could attenuate the ubiquitination-mediated degradation of SREBP2, thereby enhancing its stability and accumulation. Accordingly, KIF11 stimulated the expressions of MVA-signature and free cholesterol contents depending on SREBP2. In addition, KIF11 depended on SREBP2 to promote cell growth, migration, stemness, and colony formation abilities. The subcutaneous xenograft models indicated that targeting MVA biogenesis (atorvastatin) is effective to restrict the in vivo growth of KIF11high PDAC. Taken together, our study identified that KIF11 could activate the MVA cross talk to drive PDAC progression and inhibiting the KIF11/MVA axis provided a therapeutic vulnerability in the treatment of PDAC.

Nicotinamide Adenine Dinucleotide (NAD) Metabolism as a Relevant Target in Cancer

NAD+ is an important metabolite in cell homeostasis that acts as an essential cofactor in oxidation–reduction (redox) reactions in various energy production processes, such as the Krebs cycle, fatty acid oxidation, glycolysis and serine biosynthesis. Furthermore, high NAD+ levels are required since they also participate in many other nonredox molecular processes, such as DNA repair, posttranslational modifications, cell signalling, senescence, inflammatory responses and apoptosis. In these nonredox reactions, NAD+ is an ADP-ribose donor for enzymes such as sirtuins (SIRTs), poly-(ADP-ribose) polymerases (PARPs) and cyclic ADP-ribose (cADPRs). Therefore, to meet both redox and nonredox NAD+ demands, tumour cells must maintain high NAD+ levels, enhancing their synthesis mainly through the salvage pathway. NAMPT, the rate-limiting enzyme of this pathway, has been identified as an oncogene in some cancer types. Thus, NAMPT has been proposed as a suitable target for cancer therapy. NAMPT inhibition causes the depletion of NAD+ content in the cell, leading to the inhibition of ATP synthesis. This effect can cause a decrease in tumour cell proliferation and cell death, mainly by apoptosis. Therefore, in recent years, many specific inhibitors of NAMPT have been developed, and some of them are currently in clinical trials. Here we review the NAD metabolism as a cancer therapy target.

Characterization of Fatty Acid Metabolism-Related Genes Landscape for Predicting Prognosis and Aiding Immunotherapy in Glioma Patients

Glioma is a highly malignant brain tumor with a poor survival rate. The involvement of fatty acid metabolism in glioma was examined to find viable treatment options. The information was gathered from the Cancer Genome Atlas (TCGA) and the Chinese Glioma Genome Atlas (CGGA) databases. A prognostic signature containing fatty acid metabolism-dependent genes (FAMDs) was developed to predict glioma outcome by multivariate and most minor absolute shrinkage and selection operator (LASSO) regression analyses. In the TCGA cohort, individuals with a good score had a worse prognosis than those with a poor score, validated in the CGGA cohort. According to further research by “pRRophetic” R package, higher-risk individuals were more susceptible to crizotinib. According to a complete study of the connection between the predictive risk rating model and tumor microenvironment (TME) features, high-risk individuals were eligible for activating the immune cell-associated receptor pathway. We also discovered that anti-PD-1/PD-L1 and anti-CTLA4 immunotherapy are more effective in high-risk individuals. Furthermore, we demonstrated that CCNA2 promotes glioma proliferation, migration, and invasion and regulates macrophage polarization. Therefore, examining the fatty acid metabolism pathway aids our understanding of TME invasion properties, allowing us to develop more effective immunotherapies for glioma.

Structure-Based Identification and Biological Characterization of New NAPRT Inhibitors

NAPRT, the rate-limiting enzyme of the Preiss–Handler NAD biosynthetic pathway, has emerged as a key biomarker for the clinical success of NAMPT inhibitors in cancer treatment. Previous studies found that high protein levels of NAPRT conferred resistance to NAMPT inhibition in several tumor types whereas the simultaneous blockade of NAMPT and NAPRT results in marked anti-tumor effects. While research has mainly focused on NAMPT inhibitors, the few available NAPRT inhibitors (NAPRTi) have a low affinity for the enzyme and have been scarcely characterized. In this work, a collection of diverse compounds was screened in silico against the NAPRT structure, and the selected hits were tested through cell-based assays in the NAPRT-proficient OVCAR-5 ovarian cell line and on the recombinant hNAPRT. We found different chemotypes that efficiently inhibit the enzyme in the micromolar range concentration and for which direct engagement with the target was verified by differential scanning fluorimetry. Of note, the therapeutic potential of these compounds was evidenced by a synergistic interaction between the NAMPT inhibitor FK866 and the new NAPRTi in terms of decreasing OVCAR-5 intracellular NAD levels and cell viability. For example, compound IM29 can potentiate the effect of FK866 of more than two-fold in reducing intracellular NAD levels. These results pave the way for the development of a new generation of human NAPRTi with anticancer activity.

NAMPT Inhibition Induces Neuroblastoma Cell Death and Blocks Tumor Growth

High-risk neuroblastoma (NB) portends very poor prognoses in children. Targeting tumor metabolism has emerged as a novel therapeutic strategy. High levels of nicotinamide-adenine-dinucleotide (NAD+) are required for rapid cell proliferation. Nicotinamide phosphoribosyl transferase (NAMPT) is the rate-limiting enzyme for NAD+ salvage and is overexpressed in several cancers. Here, we determine the potential of NAMPT as a therapeutic target for NB treatment. NAMPT inhibition cytotoxicity was determined by trypan blue exclusion and LDH assays. Neuroblastoma stem cell self-renewal was evaluated by neurosphere assay. Protein expression was evaluated via Western blot. The effect of targeting NAMPT in vivo was determined using an NB1691-xenografted mouse model. Robust NAMPT expression was demonstrated in multiple N-MYC amplified, high-risk neuroblastoma cell lines. NAMPT inhibition with STF-118804 (STF) decreased ATP, induced apoptosis, and reduced NB stem cell neurosphere formation. STF treatment down-regulated N-MYC levels and abrogated AKT activation. AKT and glycolytic pathway inhibitors in combination with NAMPT inhibition induced robust, greater-than-additive neuroblastoma cell death. Lastly, STF treatment blocked neuroblastoma tumor growth in mouse xenograft models. NAMPT is a valid therapeutic target as inhibition promoted neuroblastoma cell death in vitro and prevented tumor growth in vivo. Further investigation is warranted to establish this therapy’s role as an adjunctive modality.

NAD+ attenuates bilirubin-induced augmentation of voltage-gated calcium currents in neurons of the ventral cochlear nucleus

Nicotinamide adenine dinucleotide (NAD+) is a ubiquitous molecule with wide-ranging roles in several cell processes, such as regulation of calcium homeostasis and protection against cell injuries. However, the roles of NAD+ in neuroprotection is poorly understood. The main neurons in ventral cochlear nucleus (VCN) are highly susceptible to bilirubin-associated excitotoxicity. We investigated the effects of NAD+ on VCN neurons by whole cell patch-clamp recordings. We found that NAD+ effectively reverses and inhibits bilirubin-mediated enhancement of voltage-gated calcium (VGCC) currents in VCN neurons. Moreover, NAD+ itself did not affect VGCC currents. These results collectively suggest that NAD+ may be neuroprotective by attenuating Ca²⁺ influx to suppress bilirubin-induced intracellular Ca²⁺ overloads. Our research provides a basis for evaluation of NAD+ as a promising therapeutic target for bilirubin encephalopathy and excitotoxicity associated with other neurological disorders.

Identification of NAD+ Metabolism-Derived Gene Signatures in Ovarian Cancer Prognosis and Immunotherapy

Background: Nicotinamide adenine dinucleotide (NAD⁺) has emerged as a critical regulator of cell signaling and survival pathways, affecting tumor initiation and progression. In this study it was investigated whether circulating NAD⁺ metabolism-related genes (NMRGs) could be used to predict immunotherapy response in ovarian cancer (OC) patients.

Method: In this study, NMRGs were comprehensively examined in OC patients, three distinct NMRGs subtypes were identified through unsupervised clustering, and an NAD⁺-related prognostic model was generated based on LASSO Cox regression analysis and generated a risk score (RS). ROC curves and an independent validation cohort were used to assess the model’s accuracy. A GSEA enrichment analysis was performed to investigate possible functional pathways. Furthermore, the role of RS in the tumor microenvironment, immunotherapy, and chemotherapy was also investigated.

Result: We found three different subgroups based on NMRGs expression patterns. Twelve genes were selected by LASSO regression to create a prognostic risk signature. High-RS was founded to be linked to a worse prognosis. In Ovarian Cancer Patients, RS is an independent prognostic marker. Immune infiltrating cells were considerably overexpressed in the low-RS group, as immune-related functional pathways were significantly enriched. Furthermore, immunotherapy prediction reveal that patients with low-RS are more sensitive to immunotherapy.

Conclusion: For a patient with OC, NMRGs are promising biomarkers. Our prognostic signature has potential predictive value for OC prognosis and immunotherapy response. The results of this study may help improve our understanding of NMRG in OCs.

Investigation of the effects of overexpression of jumping translocation breakpoint (JTB) protein in MCF7 cells for potential use as a biomarker in breast cancer

Jumping translocation breakpoint (JTB) gene acts as a tumor suppressor or an oncogene in different malignancies, including breast cancer (BC), where it was reported as overexpressed. However, the molecular functions, biological processes and underlying mechanisms through which JTB protein causes increased cell growth, proliferation and invasion is still not fully deciphered. Our goal is to identify the functions of JTB protein by cellular proteomics approaches. MCF7 breast cancer cells were transfected with sense orientation of hJTB cDNA in HA, His and FLAG tagged CMV expression vector to overexpress hJTB and the expression levels were confirmed by Western blotting (WB). Proteins extracted from transfected cells were separated by SDS-PAGE and the in-gel digested peptides were analyzed by nano-liquid chromatography tandem mass spectrometry (nanoLC-MS/MS). By comparing the proteome of cells with upregulated conditions of JTB vs control and identifying the protein dysregulation patterns, we aim to understand the function of this protein and its contribution to tumorigenesis. Gene Set Enrichment Analysis (GSEA) algorithm was performed to investigate the biological processes and pathways that are associated with the JTB protein upregulation. The results demonstrated four significantly enriched gene sets from the following significantly upregulated pathways: mitotic spindle assembly, estrogen response late, epithelial-to-mesenchymal transition (EMT) and estrogen response early. JTB protein itself is involved in mitotic spindle pathway by its role in cell division/cytokinesis, and within estrogen response early and late pathways, contributing to discrimination between luminal and mesenchymal breast cancer. Thus, the overexpressed JTB condition was significantly associated with an increased expression of ACTNs, FLNA, FLNB, EZR, MYOF, COL3A1, COL11A1, HSPA1A, HSP90A, WDR, EPPK1, FASN and FOXA1 proteins related to deregulation of cytoskeletal organization and biogenesis, mitotic spindle organization, ECM remodeling, cellular response to estrogen, proliferation, migration, metastasis, increased lipid biogenesis, endocrine therapy resistance, antiapoptosis and discrimination between different breast cancer subtypes. Other upregulated proteins for overexpressed JTB condition are involved in multiple cellular functions and pathways that become dysregulated, such as tumor microenvironment (TME) acidification, the transmembrane transport pathways, glycolytic flux, iron metabolism and oxidative stress, metabolic reprogramming, nucleocytosolic mRNA transport, transcriptional activation, chromatin remodeling, modulation of cell death pathways, stress responsive pathways, and cancer drug resistance. The downregulated proteins for overexpressed JTB condition are involved in adaptive communication between external and internal environment of cells and maintenance between pro-apoptotic and anti-apoptotic signaling pathways, vesicle trafficking and secretion, DNA lesions repair and suppression of genes involved in tumor progression, proteostasis, redox state regulation, biosynthesis of macromolecules, lipolytic pathway, carbohydrate metabolism, dysregulation of ubiquitin-mediated degradation system, cancer cell immune escape, cell-to-cell and cell-to-ECM interactions, and cytoskeletal behaviour. There were no significantly enriched downregulated pathways.

A Model to Detect Significant Prostate Cancer Integrating Urinary Peptide and Extracellular Vesicle RNA Data

There is a clinical need to improve assessment of biopsy-naïve patients for the presence of clinically significant prostate cancer (PCa). In this study, we investigated whether the robust integration of expression data from urinary extracellular vesicle RNA (EV-RNA) with urine proteomic metabolites can accurately predict PCa biopsy outcome. Urine samples collected within the Movember GAP1 Urine Biomarker study (n = 192) were analysed by both mass spectrometry-based urine-proteomics and NanoString gene-expression analysis (167 gene-probes). Cross-validated LASSO penalised regression and Random Forests identified a combination of clinical and urinary biomarkers for predictive modelling of significant disease (Gleason Score (Gs) ≥ 3 + 4). Four predictive models were developed: ‘MassSpec’ (CE-MS proteomics), ‘EV-RNA’, and ‘SoC’ (standard of care) clinical data models, alongside a fully integrated omics-model, deemed ‘ExoSpec’. ExoSpec (incorporating four gene transcripts, six peptides, and two clinical variables) is the best model for predicting Gs ≥ 3 + 4 at initial biopsy (AUC = 0.83, 95% CI: 0.77−0.88) and is superior to a standard of care (SoC) model utilising clinical data alone (AUC = 0.71, p < 0.001, 1000 resamples). As the ExoSpec Risk Score increases, the likelihood of higher-grade PCa on biopsy is significantly greater (OR = 2.8, 95% CI: 2.1−3.7). The decision curve analyses reveals that ExoSpec provides a net benefit over SoC and could reduce unnecessary biopsies by 30%.

Interventions in Nicotinamide Adenine Dinucleotide Metabolism, the Intestinal Microbiota and Microcin Peptide Antimicrobials

A proper NADH/NAD + balance allows for the flow of metabolic and catabolic activities determining cellular growth. In Escherichia coli, more than 80 NAD + dependent enzymes are involved in all major metabolic pathways, including the post-transcriptional build-up of thiazole and oxazole rings from small linear peptides, which is a critical step for the antibiotic activity of some microcins. In recent years, NAD metabolism boosting drugs have been explored, mostly precursors of NAD + synthesis in human cells, with beneficial effects on the aging process and in preventing oncological and neurological diseases. These compounds also enhance NAD + metabolism in the human microbiota, which contributes to these beneficial effects. On the other hand, inhibition of NAD + metabolism has been proposed as a therapeutic approach to reduce the growth and propagation of tumor cells and mitigating inflammatory bowel diseases; in this case, the activity of the microbiota might mitigate therapeutic efficacy. Antibiotics, which reduce the effect of microbiota, should synergize with NAD + metabolism inhibitors, but these drugs might increase the proportion of antibiotic persistent populations. Conversely, antibiotics might have a stronger killing effect on bacteria with active NAD + production and reduce the cooperation of NAD + producing bacteria with tumoral cells. The use of NADH/NAD + modulators should take into consideration the use of antibiotics and the population structure of the microbiota.

Cribriform type adenocarcinoma of the colorectum: comprehensive molecular analyses of a distinctive histologic subtype of colorectal cancer

Colorectal adenocarcinoma (CRA) is characterized by marked heterogeneity and may be composed of an admixture of various histologic patterns, including well-formed gland and cribriform types. Although tumors displaying a prominent or predominant cribriform feature are frequently found in CRA, this type may contain specific histologic variants with a characteristic molecular alteration. We investigated the molecular features of 51 primary CRAs with a predominant cribriform histology using array-based analyses (somatic copy number alterations [SCNA]; mRNA expression). Mutations (TP53, KRAS, PIK3CA and BRAF) and DNA methylation status were also analyzed. The crypt isolation method was used to obtain isolated tumor glands of each type separately. All patients were classified by their CRA histologic subtype into two groups: well-formed gland and cribriform. Next, we performed cluster analysis to stratify SCNA and mRNA expression patterns between the two subtypes. Two distinctive subgroups were stratified based on patterns of SCNA and mRNA expression and were correlated with each histologic subtype. The cribriform type was characterized by a high frequency of SCNA compared with that of the well-formed gland type and was closely associated with the expression of specific mRNAs. In addition, the frequency of KRAS mutation was significantly higher in the cribriform type than in the well-formed gland type. Finally, there was no difference in DNA methylation status between the two subtypes. Overall, these data suggest that the cribriform type provides important insights into colorectal carcinogenesis, suggesting specific potential histologic implications based on the molecular profile.

The CD38 glycohydrolase and the NAD sink: implications for pathological conditions

Nicotinamide adenine dinucleotide (NAD) acts as a cofactor in several oxidation-reduction (redox) reactions and is a substrate for a number of nonredox enzymes. NAD is fundamental to a variety of cellular processes including energy metabolism, cell signaling, and epigenetics. NAD homeostasis appears to be of paramount importance to health span and longevity, and its dysregulation is associated with multiple diseases. NAD metabolism is dynamic and maintained by synthesis and degradation. The enzyme CD38, one of the main NAD-consuming enzymes, is a key component of NAD homeostasis. The majority of CD38 is localized in the plasma membrane with its catalytic domain facing the extracellular environment, likely for the purpose of controlling systemic levels of NAD. Several cell types express CD38, but its expression predominates on endothelial cells and immune cells capable of infiltrating organs and tissues. Here we review potential roles of CD38 in health and disease and postulate ways in which CD38 dysregulation causes changes in NAD homeostasis and contributes to the pathophysiology of multiple conditions. Indeed, in animal models the development of infectious diseases, autoimmune disorders, fibrosis, metabolic diseases, and age-associated diseases including cancer, heart disease, and neurodegeneration are associated with altered CD38 enzymatic activity. Many of these conditions are modified in CD38-deficient mice or by blocking CD38 NADase activity. In diseases in which CD38 appears to play a role, CD38-dependent NAD decline is often a common denominator of pathophysiology. Thus, understanding dysregulation of NAD homeostasis by CD38 may open new avenues for the treatment of human diseases.

QPRT Acts as an Independent Prognostic Factor in Invasive Breast Cancer

Background. Quinolinic acid phosphoribosyltransferase (QPRT) is a rate-limiting enzyme that encodes the uronic acid pathway, which is involved in cell cycle progression and cancer cell metabolism. Some studies have demonstrated the progrowth effect of QPRT on breast cancer (BRCA) tumour cells, but its mechanism of action requires further exploration. Methods. We investigated the expression of QPRT and the prognosis of patients with different tumours by performing a pan-cancer analysis of QPRT. Prognostic values for overall survival (OS) were determined using uni- and multivariate Cox proportional hazard analyses. The prognostic survival of patients with a different pathological staging of BRCA and with QPRT high and low expression was also analysed. We also explored the relevant pathways by which QPRT affected BRCA tumorigenesis by gene set enrichment analysis (GSEA) and western blotting. The impact of QPRT on the PI3K/Akt pathway was also evaluated. Results. Pan-cancer analysis revealed significant QPRT expression in pan-cancer and correlated with prognosis in most tumour patients. QPRT was also highly expressed in BRCA when patients had poor prognoses, and its expression was associated with different pathological BRCA subtypes. GSEA revealed an association between BRCA progression and the cell cycle and the phosphatidylinositol 3-kinase (PI3K)/Akt signalling pathway, and this association was confirmed by western blotting. Conclusion. QPRT is highly expressed in breast cancer and particularly in HER2 breast cancer. Upregulated QPRT expression is an independent predictor of breast cancer prognosis and promotes breast cancer progression by activating the PI3K/Akt signalling pathway.

Revisiting therapeutic strategies for ovarian cancer by focusing on redox homeostasis

Recent advances in molecular genetics have expanded our understanding of ovarian cancer. High levels of reactive oxygen species (ROS) and upregulation of antioxidant genes are common characteristic features of human cancers. This review reconsiders novel therapeutic strategies for ovarian cancer by focusing on redox homeostasis. A literature search was performed for preclinical and clinical studies published between January 1998 and October 2021 in the PubMed database using a combination of specific terms. ROS serves a central role in tumor suppression and progression by inducing DNA damage and mutations, genomic instability, and aberrant anti- and pro-tumorigenic signaling. Cancer cells increase their antioxidant capacity to neutralize the extra ROS. Additionally, antioxidants, such as CD44 variant isoform 9 (CD44v9) and nuclear factor erythroid 2-related factor 2 (Nrf2), mediate redox homeostasis in ovarian cancer. Furthermore, studies conducted on different cancer types revealed the dual role of antioxidants in tumor progression and inhibition. However, in animal models, genetic loss of antioxidant capacity in the host cannot block cancer initiation and progression. Host-derived antioxidant systems are essential to suppress carcinogenesis, suggesting that antioxidants serve a pivotal role in suppressing cancer development. By contrast, antioxidant activation in cancer cells confers aggressive phenotypes. Antioxidant inhibitors can promote cancer cell death by enhancing ROS levels. Concurrent inhibition of CD44v9 and Nrf2 may trigger apoptosis induction, potentiate chemosensitivity and enhance antitumor activities through the ROS-activated p38/p21 pathway. Antioxidants may have tumor-promoting and -suppressive functions. Therefore, an improved understanding of the role of antioxidants in redox homeostasis and developing antioxidant-specific inhibitors is necessary for treating ovarian cancer.

Are we still on the right path(way)?: the altered expression of the pentose phosphate pathway in solid tumors and the potential of its inhibition in combination therapy

INTRODUCTION

The pentose phosphate pathway (PPP) branches from glycolysis and is crucial for cell growth, since it provides necessary compounds for anabolic reactions, nucleotide synthesis, and detoxification of reactive-oxygen-species (ROS). Overexpression of PPP enzymes has been reported in multiple cancer types and linked to therapy resistance, making their inhibition interesting targets for anti-cancer therapies.

AREAS COVERED

This review summarizes the extent of PPP upregulation across different cancer types, and the non-metabolic functions that PPP-enzymes might contribute to cancer initiation and maintenance. The effects of PPP-inhibition and their combinations with chemotherapeutics are summarized. We searched the databases provided by the University of Amsterdam to characterize the altered expression of the PPP across different cancer types, and to identify the effects of PPP-inhibition.

EXPERT OPINION

It can be concluded that there are synergistic and additive effects of PPP-inhibition and various classes of chemotherapeutics. These effects may be attributed to the increased susceptibility to ROS. However, the toxicity, low efficacy, and off-target effects of PPP-inhibitors make application in clinical practice challenging. Novel inhibitors are currently being developed, which could make PPP-inhibition a potential therapeutic strategy in the future, especially in combination with conventional chemotherapeutics and the inhibition of other metabolic pathways.

Therapeutic Influence on Important Targets Associated with Chronic Inflammation and Oxidative Stress in Cancer Treatment

Simple Summary

There is no doubt that the need for new effective methods of cancer treatment remains challenging, as cancer is the second cause of death based on the number of cases in the world. In this review, we investigated the role of one of the leading determinants in the development and progression of various types of cancer—oxidative stress and inflammation, as well as clinical and experimental data from the studies of promising drugs of natural origin, such as flavonoids, that target these stages of oncogenesis. This can all help in the expansion and systematization of the existing knowledge regarding the fight against cancer, the facilitation of the development of effective anti-cancer drugs, and the progression of research in this field, in order to improve the treatment of these disorders.

Abstract

Chronic inflammation and oxidative stress are the interconnected pathological processes, which lead to cancer initiation and progression. The growing level of oxidative and inflammatory damage was shown to increase cancer severity and contribute to tumor spread. The overproduction of reactive oxygen species (ROS), which is associated with the reduced capacity of the endogenous cell defense mechanisms and/or metabolic imbalance, is the main contributor to oxidative stress. An abnormal level of ROS was defined as a predisposing factor for the cell transformation that could trigger pro-oncogenic signaling pathways, induce changes in gene expression, and facilitate accumulation of mutations, DNA damage, and genomic instability. Additionally, the activation of transcription factors caused by a prolonged oxidative stress, including NF-κB, p53, HIF1α, etc., leads to the expression of several genes responsible for inflammation. The resulting hyperactivation of inflammatory mediators, including TNFα, TGF-β, interleukins, and prostaglandins can contribute to the development of neoplasia. Pro-inflammatory cytokines were shown to trigger adaptive reactions and the acquisition of resistance by tumor cells to apoptosis, while promoting proliferation, invasion, and angiogenesis. Moreover, the chronic inflammatory response leads to the excessive production of free radicals, which further aggravate the initiated reactions. This review summarizes the recent data and progress in the discovery of mechanisms that associate oxidative stress and chronic inflammation with cancer onset and metastasis. In addition, the review provides insights for the development of therapeutic approaches and the discovery of natural substances that will be able to simultaneously inhibit several key oncological and inflammation-related targets.

Insight Into Nicotinamide Adenine Dinucleotide Homeostasis as a Targetable Metabolic Pathway in Colorectal Cancer

Tumour cells modify their cellular metabolism with the aim to sustain uncontrolled proliferation. Cancer cells necessitate adequate amounts of NAD and NADPH to support several enzymes that are usually overexpressed and/or overactivated. Nicotinamide adenine dinucleotide (NAD) is an essential cofactor and substrate of several NAD-consuming enzymes, such as PARPs and sirtuins, while NADPH is important in the regulation of the redox status in cells. The present review explores the rationale for targeting the key enzymes that maintain the cellular NAD/NADPH pool in colorectal cancer and the enzymes that consume or use NADP(H).

Dual Roles of Nicotinamide Phosphoribosyltransferase as a Promising Target for Cancer Radiotherapy

Nicotinamide phosphoribosyltransferase (NAMPT) is the key rate-limiting enzyme in the regulation of nicotinamide adenine dinucleotide (NAD) biosynthesis, and its activity is critical for the replenishment of NAD level as well as cell survival or death. As one of the most important components in the electron transport chain of complex I in mitochondrion, sustained supply of NAD is essential to the maintenance of energy metabolism both in normal and cancer cells. Recent research shown that X-ray radiation sharply downregulated the expression of NAMPT, which may be the main cause of radiation damage in salivary gland. Consistently, upregulation of NAMPT by phenylephrine restored the function and tissue structure of salivary gland, indicating the cytoprotective role of NAMPT in preventing radiation damage in normal tissues of patients with head and neck cancer during radiotherapy. On the other hand, NAMPT downregulation and NAD depletion could induce cell death in oral squamous cell cancer, suggesting that a combination of NAMPT inhibitor and radiotherapy presents a promising therapeutic strategy for cancer treatment. Based on our and other's studies, NAMPT may have dual roles in cancer radiotherapy: the upregulation of NAMPT could serve to suppress radiotherapy complications such as radiation sialadenitis, and combination regimens that involve NAMPT inhibitors may enhance efficacy of radiotherapy for cancer treatment.

Biochemical Mechanisms Associating Alcohol Use Disorders with Cancers

Simple Summary

Of all yearly deaths attributable to alcohol consumption globally, approximately 12% are due to cancers, representing approximately 0.4 million deceased individuals. Ethanol metabolism disturbs cell biochemistry by targeting the structure and function of essential biomolecules (proteins, nucleic acids, and lipids) and by provoking alterations in cell programming that lead to cancer development and cancer malignancy. A better understanding of the metabolic and cell signaling realm affected by ethanol is paramount to designing effective treatments and preventive actions tailored to specific neoplasias.

Abstract

The World Health Organization identifies alcohol as a cause of several neoplasias of the oropharynx cavity, esophagus, gastrointestinal tract, larynx, liver, or female breast. We review ethanol’s nonoxidative and oxidative metabolism and one-carbon metabolism that encompasses both redox and transfer reactions that influence crucial cell proliferation machinery. Ethanol favors the uncontrolled production and action of free radicals, which interfere with the maintenance of essential cellular functions. We focus on the generation of protein, DNA, and lipid adducts that interfere with the cellular processes related to growth and differentiation. Ethanol’s effects on stem cells, which are responsible for building and repairing tissues, are reviewed. Cancer stem cells (CSCs) of different origins suffer disturbances related to the expression of cell surface markers, enzymes, and transcription factors after ethanol exposure with the consequent dysregulation of mechanisms related to cancer metastasis or resistance to treatments. Our analysis aims to underline and discuss potential targets that show more sensitivity to ethanol’s action and identify specific metabolic routes and metabolic realms that may be corrected to recover metabolic homeostasis after pharmacological intervention. Specifically, research should pay attention to re-establishing metabolic fluxes by fine-tuning the functioning of specific pathways related to one-carbon metabolism and antioxidant processes.

Exosomal IDH1 increases the resistance of colorectal cancer cells to 5-Fluorouracil

Chemoresistance challenges the clinical treatment of colorectal cancer and requires an urgent solution. Isocitrate dehydrogenase 1 (IDH1) is a key enzyme involved in glucose metabolism that mediates the malignant transformation of tumors. However, the mechanisms by which IDH1 is involved in colorectal cancer cell proliferation and drug resistance induction remain unclear. In this study, we found that IDH1 was highly expressed in human colorectal cancer tissues and could be used to indicate a high-grade tumor. In vitro gene overexpression and knockdown were used to determine whether IDH1 promoted the proliferation of the colorectal cancer cell line HCT8 and resistance to 5-Fluorouracil (5FU). Further studies have shown that the 5FU-resistant cell line, HCT8FU, secreted exosomes that contained a high level of IDH1 protein. The exosomal IDH1 derived from 5FU-resistant cells enhanced the resistance of 5FU-sensitive cells. Metabolic assays revealed that exosomes derived from 5FU-resistant cells promoted a decrease in the level of IDH1-mediated NADPH, which is associated with the development of 5FU resistance in colorectal cancer cells. Therefore, exosomal IDH1 may be the transmitter and driver of chemoresistance in colorectal cancer and a potential chemotherapy target.

In cancer, all roads lead to NADPH

Cancer cells require increased levels of NADPH for increased nucleotide synthesis and for protection from ROS. Recent studies show that increased NADPH is generated in several ways. Activated AKT phosphorylates NAD kinase (NADK), increasing its activity. NADP formed, is rapidly converted to NADPH by glucose 6-phosphate dehydrogenase and malic enzymes, overexpressed in tumor cells with mutant p53. Calmodulin, overexpressed in some cancers, also increases NADK activity. Also, in IDH1/2 mutant cancer, NADPH serves as the cofactor to generate D-2 hydroxyglutarate, an oncometabolite. The requirement of cancer cells for elevated levels of NADPH provides an opportunity to target its synthesis for cancer treatment.

NAD+ metabolism, stemness, the immune response, and cancer

NAD⁺ was discovered during yeast fermentation, and since its discovery, its important roles in redox metabolism, aging, and longevity, the immune system and DNA repair have been highlighted. A deregulation of the NAD⁺ levels has been associated with metabolic diseases and aging-related diseases, including neurodegeneration, defective immune responses, and cancer. NAD⁺ acts as a cofactor through its interplay with NADH, playing an essential role in many enzymatic reactions of energy metabolism, such as glycolysis, oxidative phosphorylation, fatty acid oxidation, and the TCA cycle. NAD⁺ also plays a role in deacetylation by sirtuins and ADP ribosylation during DNA damage/repair by PARP proteins. Finally, different NAD hydrolase proteins also consume NAD⁺ while converting it into ADP-ribose or its cyclic counterpart. Some of these proteins, such as CD38, seem to be extensively involved in the immune response. Since NAD cannot be taken directly from food, NAD metabolism is essential, and NAMPT is the key enzyme recovering NAD from nicotinamide and generating most of the NAD cellular pools. Because of the complex network of pathways in which NAD⁺ is essential, the important role of NAD⁺ and its key generating enzyme, NAMPT, in cancer is understandable. In the present work, we review the role of NAD⁺ and NAMPT in the ways that they may influence cancer metabolism, the immune system, stemness, aging, and cancer. Finally, we review some ongoing research on therapeutic approaches.

Cytoplasmic ADP-ribosylation levels correlate with markers of patient outcome in distinct human cancers

ADP-ribosylation (ADPR) is a posttranslational modification whose importance in oncology keeps increasing due to frequent use of PARP inhibitors (PARPi) to treat different tumor types. Due to the lack of suitable tools to analyze cellular ADPR levels, ADPR's significance for cancer progression and patient outcome is unclear. In this study, we assessed ADPR levels by immunohistochemistry using a newly developed anti-ADP-ribose (ADPr) antibody, which is able to detect both mono- and poly-ADPR. Tissue microarrays containing brain (n = 103), breast (n = 1108), colon (n = 236), lung (n = 138), ovarian (n = 142), and prostate (n = 328) cancers were used to correlate ADPR staining intensities to clinico-pathological data, including patient overall survival (OS), tumor grade, tumor stage (pT), lymph node status (pN), and the presence of distant metastasis (pM). While nuclear ADPR was detected only in a minority of the samples, cytoplasmic ADPR (cyADPR) staining was observed in most tumor types. Strong cyADPR intensities were significantly associated with better overall survival in invasive ductal breast cancer (p < 0.0001), invasive lobular breast cancer (p < 0.005), and high grade serous ovarian cancer patients (p < 0.01). Furthermore, stronger cytoplasmic ADPR levels significantly correlated with early tumor stage in colorectal and in invasive ductal breast adenocarcinoma (p < 0.0001 and p < 0.01, respectively) and with the absence of regional lymph node metastasis in colorectal adenocarcinoma (p < 0.05). No correlation to cyADPR was found for prostate and lung cancer or brain tumors. In conclusion, our new anti-ADP-ribose antibody revealed heterogeneous ADPR staining patterns with predominant cytoplasmic ADPR staining in most tumor types. Different cyADPR staining patterns could help to better understand variable response rates to PARP inhibitors in the future.

Isocitrate dehydrogenase 1 gene variants analysis of glioma patients from Pakistan

Various somatic isocitrate dehydrogenase 1 (IDH1) gene variants have been reported to drive lower-grade gliomas and secondary glioblastomas. In the current study, we explored the IDH1 variants in the glioma biopsy samples of patients from Pakistan. We explored the incidence of isocitrate dehydrogenase 1 gene variants by hotspot sequencing in 80 formalin-fixed paraffin-embedded tissues of different types of glioma biopsy samples. Structural modeling of the identified variants in isocitrate dehydrogenase 1 protein was done to see their possible consequences. The frequently described p.Arg132 variants were not found in any of the glioma types. However, in our study, we identified nonsynonymous variants at the residues p.R109 and p.G136 in astrocytomas and p.R100 in oligodendroglioma. These variants are affecting a part of the conserved domain in isocitrate dehydrogenase 1. Both of p.R100 and p.R109 variants are rare and described before, whereas the p.G136 variant identified in this study has never been described previously. Structural modeling showed that variants of these residues would directly affect the substrate binding and hence the enzyme activity.

A New Twist in Protein Kinase B/Akt Signaling: Role of Altered Cancer Cell Metabolism in Akt-Mediated Therapy Resistance

Cancer resistance to chemotherapy, radiotherapy and molecular-targeted agents is a major obstacle to successful cancer therapy. Herein, aberrant activation of the phosphatidyl-inositol-3-kinase (PI3K)/protein kinase B (Akt) pathway is one of the most frequently deregulated pathways in cancer cells and has been associated with multiple aspects of therapy resistance. These include, for example, survival under stress conditions, apoptosis resistance, activation of the cellular response to DNA damage and repair of radiation-induced or chemotherapy-induced DNA damage, particularly DNA double strand breaks (DSB). One further important, yet not much investigated aspect of Akt-dependent signaling is the regulation of cell metabolism. In fact, many Akt target proteins are part of or involved in the regulation of metabolic pathways. Furthermore, recent studies revealed the importance of certain metabolites for protection against therapy-induced cell stress and the repair of therapy-induced DNA damage. Thus far, the likely interaction between deregulated activation of Akt, altered cancer metabolism and therapy resistance is not yet well understood. The present review describes the documented interactions between Akt, its target proteins and cancer cell metabolism, focusing on antioxidant defense and DSB repair. Furthermore, the review highlights potential connections between deregulated Akt, cancer cell metabolism and therapy resistance of cancer cells through altered DSB repair and discusses potential resulting therapeutic implications.

Role of Oxidative Stress on SARS-CoV (SARS) and SARS-CoV-2 (COVID-19) Infection: A Review

Novel coronavirus disease 2019 (COVID-19) has resulted in a global pandemic and is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Several studies have suggested that a precise disulfide-thiol balance is crucial for viral entry and fusion into the host cell and that oxidative stress generated from free radicals can affect this balance. Here, we reviewed the current knowledge about the role of oxidative stress on SARS-CoV and SARS-CoV-2 infections. We focused on the impact of antioxidants, like NADPH and glutathione, and redox proteins, such as thioredoxin and protein disulfide isomerase, that maintain the disulfide-thiol balance in the cell. The possible influence of these biomolecules on the binding of viral protein with the host cell angiotensin-converting enzyme II receptor protein as well as on the severity of COVID-19 infection was discussed.

NADPH homeostasis in cancer: functions, mechanisms and therapeutic implications

Nicotinamide adenine dinucleotide phosphate (NADPH) is an essential electron donor in all organisms, and provides the reducing power for anabolic reactions and redox balance. NADPH homeostasis is regulated by varied signaling pathways and several metabolic enzymes that undergo adaptive alteration in cancer cells. The metabolic reprogramming of NADPH renders cancer cells both highly dependent on this metabolic network for antioxidant capacity and more susceptible to oxidative stress. Modulating the unique NADPH homeostasis of cancer cells might be an effective strategy to eliminate these cells. In this review, we summarize the current existing literatures on NADPH homeostasis, including its biological functions, regulatory mechanisms and the corresponding therapeutic interventions in human cancers, providing insights into therapeutic implications of targeting NADPH metabolism and the associated mechanism for cancer therapy.