Deacetylation by SIRT1 Reprograms Inflammation and Cancer

Hesperetin protects against rotenone-induced motor disability and neurotoxicity via the regulation of SIRT1/NLRP3 signaling

Rotenone is a pesticide that causes complex I inhibition and is widely known to induce motor disability and experimental Parkinson's disease (PD) in rodents. Evidence suggests a crucial role for sirtuin/nuclear factor-kappaB/nod-like receptor family, pyrin domain-containing 3 (SIRT1/NFκB/NLRP3) signaling and inflammation in PD and rotenone neurotoxicity. Hesperetin (C16H14O6) is a citrus flavonoid with documented anti-inflammatory activity. We investigated the value of hesperetin in delaying rotenone-induced PD in mice and the possible modulation of inflammatory burden. PD was induced in mice via rotenone injections. Groups were assigned as a vehicle, PD, or PD + hesperetin (50 or 100 mg/kg) and compared for the motor function, protein level (by ELISA), and gene expression (by real-time PCR) of the target proteins, histopathology, and immunohistochemistry for tyrosine hydroxylase enzyme. Hesperetin (50 or 100 mg/kg) alleviated the motor disability and the striatal dopamine level and decreased the expression of NLRP3 and NF-κB but increased SIRT1 expression (p < 0.05). Further, it enhanced the neural viability and significantly decreased neural degeneration in the substantia nigra, hippocampus, and cerebral cortex (p < 0.05). Taken together, we propose that hesperetin mediates its neuroprotective function via alleviating modulation of the SIRT1/NFκB/NLRP3 pathway. Therefore, hesperetin might delay the PD progression.

SIRT1 is an actionable target to restore p53 function in HPV-associated cancer therapy

BACKGROUND

Our aim was to evaluate the efficacy and anti-cancer action of a precision medicine approach involving a novel SIRT1-dependent pathway that, when disrupted, leads to the restoration of a functional p53 in human papillomavirus (HPV)-transformed cells.

METHODS

The anticancer potential of inhibiting SIRT1 was evaluated by examining the effects of the specific SIRT1 inhibitor EX527 (also known as Selisistat) or genetic silencing, either individually or in conjunction with standard chemotherapeutic agents, on a range of HPV+ cancer cells and a preclinical mouse model of HPV16-induced cancer.

RESULTS

We show that SIRT1 inhibition restores a transcriptionally active K382-acetylated p53 in HPV+ but not HPV- cell lines, which in turn promotes G0/G1 cell cycle arrest and inhibits clonogenicity specifically in HPV+ cells. Additionally, EX527 treatment increases the sensitivity of HPV+ cells to sublethal doses of standard genotoxic agents. The enhanced sensitivity to cisplatin as well as p53 restoration were also observed in an in vivo tumorigenicity assay using syngeneic C3.43 cells harbouring an integrated HPV16 genome, injected subcutaneously into C57BL/6J mice.

CONCLUSIONS

Our findings uncover an essential role of SIRT1 in HPV-driven oncogenesis, which may have direct translational implications for the treatment of this type of cancer.

Oral Nicotinamide for Actinic Keratosis Prevention in Kidney Transplant Recipients: A Pilot Double-Blind, Randomized, Placebo-Controlled Trial

BACKGROUND

Oral nicotinamide (NAM) has shown promise in preventing actinic keratoses (AKs) in trials based outside of the United States. We assessed the efficacy of oral NAM supplementation in kidney transplant recipients with a history of keratinocyte carcinoma.

MATERIAL AND METHODS

Patients enrolled in a 2-week run-in phase, during which NAM 1000 mg was taken twice daily. After a washout period, patients who tolerated the run-in phase were randomized to NAM 500 mg twice daily or placebo. At baseline, 4, 8, and 12 months, dermatologists conducted full-body skin exams to document area-specific AKs. Routine lab work was collected to ensure the stability of renal allograft function.

RESULTS

The dosage was reduced from 1000 to 500 mg due to gastrointestinal symptoms in the run-in phase. Patients were randomized to NAM (n = 10) or placebo (n = 11). At 12 months, mean AK count was 30.8 (95% CI -11.7-73.4) for NAM and 26.6 (95% CI 10.8-42.5) for placebo. The difference in percent AK count change at 12 months compared with baseline was 259.8% (95% CI -385.9 to 905.5) for NAM and 72.4% (95% CI -118.6 to 263.5) for placebo. The between-group difference in percent AK change was not significant (P = .38). There was no attrition in the placebo group and 40% attrition in the NAM arm.

DISCUSSION

Nicotinamide did not decrease AK development among kidney transplant recipients. Limitations include drug tolerability, small sample size, and single-center trial nature.

Early Resveratrol Treatment Mitigates Joint Degeneration and Dampens Pain in a Mouse Model of Pseudoachondroplasia (PSACH)

Pseudoachondroplasia (PSACH), a severe dwarfing condition associated with early-onset joint degeneration and lifelong joint pain, is caused by mutations in cartilage oligomeric matrix protein (COMP). The mechanisms underlying the mutant-COMP pathology have been defined using the MT-COMP mouse model of PSACH that has the common D469del mutation. Mutant-COMP protein does not fold properly, and it is retained in the rough endoplasmic reticulum (rER) of chondrocytes rather than being exported to the extracellular matrix (ECM), driving ER stress that stimulates oxidative stress and inflammation, driving a self-perpetuating cycle. CHOP (ER stress signaling protein) and TNFα inflammation drive high levels of mTORC1 signaling, shutting down autophagy and blocking ER clearance, resulting in premature loss of chondrocytes that negatively impacts linear growth and causes early joint degeneration in MT-COMP mice and PSACH. Previously, we have shown that resveratrol treatment from birth to 20 weeks prevents joint degeneration and decreases the pathological processes in articular chondrocytes. Resveratrol's therapeutic mechanism of action in the mutant-COMP pathology was shown to act by primarily stimulating autophagy and reducing inflammation. Importantly, we demonstrated that MT-COMP mice experience pain consistent with PSACH joint pain. Here, we show, in the MT-COMP mouse, that resveratrol treatment must begin within 4 weeks to preserve joint health and reduce pain. Resveratrol treatment started at 6 or 8 weeks (to 20 weeks) was not effective in preventing joint degeneration. Collectively, our findings in MT-COMP mice show that there is a postnatal resveratrol treatment window wherein the inevitable mutant-COMP joint degeneration and pain can be prevented.

Astilbin targeted Sirt1 to inhibit acetylation of Nrf2 to alleviate grass carp hepatocyte apoptosis caused by PCB126-induced mitochondrial kinetic and metabolism dysfunctions

3, 3', 4, 4', 5-pentachlorobiphenyl (PCB126) is extensively utilized in electronic products, lubricant, and insecticide due to its excellent chemical stability and insulation prosperity, resulting in its frequent detection in environment. In addition, atmospheric deposition, as well as industrial and urban wastewater discharge can also lead to PCB126 contamination in marine environment, triggering damages to the tissues of aquatic organisms through oxidative stress. Astilbin is a type of flavonoid compound found in plants that plays a crucial role in providing powerful antioxidant and anti-inflammatory properties. In this study, we aimed to investigate the specific mechanism of PCB126-induced damage and the potential protective effect of Astilbin. To achieve this, we treated grass carp hepatocytes (L8824) with 75 μM PCB126 and/or 0.5 mM Astilbin for 24 h and used experimental methods such as Flow cytometry, molecular docking, PPI analysis, detection of commercial kits (ATP concentration and ATPnase activity) and measurement of mitochondrial membrane potential (ΔΨm). Our findings revealed that PCB126 exposure resulted in a decrease in expression levels of Sirt1, factors related to mitochondrial fusion (Opa1, Mfn1, and Mfn2), antioxidant (CAT, SOD1, and SOD2), energy metabolism (PKM2, IDH, and SDH) and anti-apoptosis (Bcl-2), and an increase in expression levels of Nrf2 acetylation, mitochondrial fission (Drp1), factors that promote apoptosis (Cytc, Bax, Cas9, and Cas3) in L8824 cells. Furthermore, our findings revealed a decrease in ΔΨm, ATP concentration and ATPnase activity and apoptosis levels in L8824 cells. Noteworthy, treatment with Astilbin reversed these results. Molecular docking provides solid evidence for the interaction between Astilbin and Sirt1. In summary, our findings suggested that Astilbin promoted the deacetylation of Nrf2 by interacting with Sirt1, thereby alleviating PCB126-induced mitochondrial apoptosis mediated by mitochondrial dynamics imbalance and energy metabolism disorder through the inhibition of oxidative stress in L8824 cells. Our research has initially revealed the correlation between acetylation and apoptosis induced by PCB126, which provided a foundation for a better comprehension of PCB126 toxicity. Additionally, it expanded the potential application value of Astilbin.

G9a and Sirtuin6 epigenetically modulate host cholesterol accumulation to facilitate mycobacterial survival

Cholesterol derived from the host milieu forms a critical factor for mycobacterial pathogenesis. However, the molecular circuitry co-opted by Mycobacterium tuberculosis (Mtb) to accumulate cholesterol in host cells remains obscure. Here, we report that the coordinated action of WNT-responsive histone modifiers G9a (H3K9 methyltransferase) and SIRT6 (H3K9 deacetylase) orchestrate cholesterol build-up in in vitro and in vivo mouse models of Mtb infection. Mechanistically, G9a, along with SREBP2, drives the expression of cholesterol biosynthesis and uptake genes; while SIRT6 along with G9a represses the genes involved in cholesterol efflux. The accumulated cholesterol in Mtb infected macrophages promotes the expression of antioxidant genes leading to reduced oxidative stress, thereby supporting Mtb survival. In corroboration, loss-of-function of G9a in vitro and pharmacological inhibition in vivo; or utilization of BMDMs derived from Sirt6-/- mice or in vivo infection in haplo-insufficient Sirt6-/+ mice; hampered host cholesterol accumulation and restricted Mtb burden. These findings shed light on the novel roles of G9a and SIRT6 during Mtb infection and highlight the previously unknown contribution of host cholesterol in potentiating anti-oxidative responses for aiding Mtb survival.

Metabolo-epigenetic interplay provides targeted nutritional interventions in chronic diseases and ageing

Epigenetic modifications are chemical modifications that affect gene expression without altering DNA sequences. In particular, epigenetic chemical modifications can occur on histone proteins -mainly acetylation, methylation-, and on DNA and RNA molecules -mainly methylation-. Additional mechanisms, such as RNA-mediated regulation of gene expression and determinants of the genomic architecture can also affect gene expression. Importantly, depending on the cellular context and environment, epigenetic processes can drive developmental programs as well as functional plasticity. However, misbalanced epigenetic regulation can result in disease, particularly in the context of metabolic diseases, cancer, and ageing. Non-communicable chronic diseases (NCCD) and ageing share common features including altered metabolism, systemic meta-inflammation, dysfunctional immune system responses, and oxidative stress, among others. In this scenario, unbalanced diets, such as high sugar and high saturated fatty acids consumption, together with sedentary habits, are risk factors implicated in the development of NCCD and premature ageing. The nutritional and metabolic status of individuals interact with epigenetics at different levels. Thus, it is crucial to understand how we can modulate epigenetic marks through both lifestyle habits and targeted clinical interventions -including fasting mimicking diets, nutraceuticals, and bioactive compounds- which will contribute to restore the metabolic homeostasis in NCCD. Here, we first describe key metabolites from cellular metabolic pathways used as substrates to "write" the epigenetic marks; and cofactors that modulate the activity of the epigenetic enzymes; then, we briefly show how metabolic and epigenetic imbalances may result in disease; and, finally, we show several examples of nutritional interventions - diet based interventions, bioactive compounds, and nutraceuticals- and exercise to counteract epigenetic alterations.

Stilbenes, a Versatile Class of Natural Metabolites for Inflammation-An Overview

Stilbenes are polyphenolic allelochemicals synthesized by plants, especially grapes, peanuts, rhubarb, berries, etc., to defend themselves under stressful conditions. They are now exploited in medicine for their antioxidant, anti-proliferative and anti-inflammatory properties. Inflammation is the immune system's response to invading bacteria, toxic chemicals or even nutrient-deprived conditions. It is characterized by the release of cytokines which can wreak havoc on healthy tissues, worsening the disease condition. Stilbenes modulate NF-κB, MAPK and JAK/STAT pathways, and reduce the transcription of inflammatory factors which result in maintenance of homeostatic conditions. Resveratrol, the most studied stilbene, lowers the Michaelis constant of SIRT1, and occupies the substrate binding pocket. Gigantol interferes with the complement system. Besides these, oxyresveratrol, pterostilbene, polydatin, viniferins, etc., are front runners as drug candidates due to their diverse effects from different functional groups that affect bioavailability and molecular interactions. However, they each have different thresholds for toxicity to various cells of the human body, and thus a careful review of their properties must be conducted. In animal models of autoinflammatory diseases, the mode of application of stilbenes is important to their absorption and curative effects, as seen with topical and microemulsion gel methods. This review covers the diversity seen among stilbenes in the plant kingdom and their mechanism of action on the different inflammatory pathways. In detail, macrophages' contribution to inflamed conditions in the liver, the cardiac, connective and neural tissues, in the nephrons, intestine, lungs and in myriad other body cells is explored, along with detailed explanation on how stilbenes alleviate the symptoms specific to body site. A section on the bioavailability of stilbenes is included for understanding the limitations of the natural compounds as directly used drugs due to their rapid metabolism. Current delivery mechanisms include sulphonamides, or using specially designed synthetic drugs. It is hoped that further research may be fueled by this comprehensive work that makes a compelling argument for the exploitation of these compounds in medicine.

Discovery and design of dual inhibitors targeting Sphk1 and Sirt1

CONTEXT

Leukaemia has become a serious threat to human health. Although tyrosine kinase inhibitors (TKIs) have been developed as targets for the remedy of leukaemia, drug resistance occurs. Research demonstrated that the simultaneous targeting of sphingosine kinase 1 (Sphk1) and Sirtuin 1 (Sirt1) can downregulate myeloid cell leukaemia-1 (MCL-1), overcome the resistance of tyrosine kinase inhibitors, and play a synergistic inhibitory impact on leukaemia treatment.

METHODS

In this study, virtual screening of 7.06 million small molecules was done by sphingosine kinase 1 and Sirtuin 1 pharmacophore models using Schrödinger version 2019; after that, ADME and Toxicity molecule properties were predicted using Discovery Studio. Molecular docking using Schrödinger selected five molecules, which have the best binding affinity with sphingosine kinase 1 and Sirtuin 1. The five molecules and reference inhibitors were constructed with a total of 12 systems with GROMACS that carried out 100 ns molecular dynamics simulation and molecular mechanics/Poisson-Boltzmann surface area (MM/PBSA) calculation. Due to compound 3 has the lowest binding energy, its structure was modified. A series of compounds docked with sphingosine kinase 1 and Sirtuin 1, respectively. Among them, QST-LC03, QST-LD05, QST-LE03, and QST-LE04 have the better binding affinity than reference inhibitors. Moreover, the SwissADME and PASS platforms predict that 1, 3, QST-LC03, and QST-LE04 have further study value.

Immunometabolic interference between cancer and COVID-19

Even though cancer patients are generally considered more susceptible to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, the mechanisms driving their predisposition to severe forms of coronavirus disease 2019 (COVID-19) have not yet been deciphered. Since metabolic disorders are associated with homeostatic frailty, which increases the risk of infection and cancer, we asked whether we could identify immunometabolic pathways intersecting with cancer and SARS-CoV-2 infection. Thanks to a combined flow cytometry and multiomics approach, here we show that the immunometabolic traits of COVID-19 cancer patients encompass alterations in the frequency and activation status of circulating myeloid and lymphoid subsets, and that these changes are associated with i) depletion of tryptophan and its related neuromediator tryptamine, ii) accumulation of immunosuppressive tryptophan metabolites (i.e., kynurenines), and iii) low nicotinamide adenine dinucleotide (NAD+) availability. This metabolic imbalance is accompanied by altered expression of inflammatory cytokines in peripheral blood mononuclear cells (PBMCs), with a distinctive downregulation of IL-6 and upregulation of IFNγ mRNA expression levels. Altogether, our findings indicate that cancer not only attenuates the inflammatory state in COVID-19 patients but also contributes to weakening their precarious metabolic state by interfering with NAD+-dependent immune homeostasis.

MicroRNA-34a, Prostate Cancer Stem Cells, and Therapeutic Development

Prostate cancer (PCa) is a highly heterogeneous disease and typically presents with multiple distinct cancer foci. Heterogeneity in androgen receptor (AR) expression levels in PCa has been observed for decades, from untreated tumors to castration-resistant prostate cancer (CRPC) to disseminated metastases. Current standard-of-care therapies for metastatic CRPC can only extend life by a few months. Cancer stem cells (CSCs) are defined as a subpopulation of cancer cells that exists in almost all treatment-naive tumors. Additionally, non-CSCs may undergo cellular plasticity to be reprogrammed to prostate cancer stem cells (PCSCs) during spontaneous tumor progression or upon therapeutic treatments. Consequently, PCSCs may become the predominant population in treatment-resistant tumors, and the "root cause" for drug resistance. microRNA-34a (miR-34a) is a bona fide tumor-suppressive miRNA, and its expression is dysregulated in PCa. Importantly, miR-34a functions as a potent CSC suppressor by targeting many molecules essential for CSC survival and functions, which makes it a promising anti-PCSC therapeutic. Here, we conducted a comprehensive literature survey of miR-34a in the context of PCa and especially PCSCs. We provided an updated overview on the mechanisms of miR-34a regulation followed by discussing its tumor suppressive functions in PCa. Finally, based on current advances in miR-34a preclinical studies in PCa, we offered potential delivery strategies for miR-34a-based therapeutics for treating advanced PCa.

Platinum-induced mitochondrial OXPHOS contributes to cancer stem cell enrichment in ovarian cancer

Background

Platinum based agents—cisplatin and carboplatin in combination with taxanes are used for the treatment of ovarian cancer (OC) patients. However, the majority of OC patients develop recurrent, platinum resistant disease that is uniformly fatal. Platinum treatment enriches for chemoresistant aldehyde dehydrogenase (ALDH) + ovarian cancer stem cells (OCSCs), which contribute to tumor recurrence and disease relapse. Acquired platinum resistance also includes metabolic reprograming and switching to oxidative phosphorylation (OXPHOS). Chemosensitive cells rely on glycolysis while chemoresistant cells have the ability to switch between glycolysis and OXPHOS, depending on which pathway drives a selective advantage for growth and chemoresistance. High expression of genes involved in OXPHOS and high production of mitochondrial ROS are characteristics of OCSCs, suggesting that OCSCs favor OXPHOS over glycolysis. Based on connections between OCSCs, chemoresistance and OXPHOS, we hypothesize that platinum treatment induces changes in metabolism that contribute to platinum-induced enrichment of OCSCs.

Methods

The effect of cisplatin on mitochondrial activity was assessed by JC1 staining and expression of OXPHOS genes by RT-qPCR. Cisplatin-induced changes in Sirtuin 1 (SIRT1) levels and activity were assessed by western blot. Small molecule inhibitors of mitochondrial complex I and SIRT1 were used to determine if their enzymatic activity contributes to the platinum-induced enrichment of OCSCs. The percentage of ALDH + OCSCs in OC cells and tumor tissue from xenograft models across different treatment conditions was analyzed using ALDEFLUOR assay and flow cytometry.

Results

We demonstrate that platinum treatment increases mitochondrial activity. Combined treatment of platinum agents and OXPHOS inhibitors blocks the platinum-induced enrichment of ALDH + OCSCs in vitro and in vivo. Furthermore, platinum treatment increases SIRT1 levels and subsequent deacetylase activity, which likely contributes to the increase in platinum-induced mitochondrial activity.

Conclusions

These findings on metabolic pathways altered by platinum-based chemotherapy have uncovered key targets that can be exploited therapeutically to block the platinum-induced enrichment of OCSCs, ultimately improving the survival of OC patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03447-y.

Inflammasome Activation and Pyroptosis via a Lipid-regulated SIRT1-p53-ASC Axis in Macrophages From Male Mice and Humans

Obesity-linked diabetes is associated with accumulation of proinflammatory macrophages into adipose tissue leading to inflammasome activation and pyroptotic secretion of interleukin (IL)-1β and IL-18. Targeting fatty acid binding protein 4 (FABP4) uncouples obesity from inflammation, attenuates characteristics of type 2 diabetes and is mechanistically linked to the cellular accumulation of monounsaturated fatty acids in macrophages. Herein we show that pharmacologic inhibition or genetic deletion of FABP4 activates silent mating type information regulation 2 homolog 1 (SIRT1) and deacetylates its downstream targets p53 and signal transducer and activator of transcription 3 (STAT3). Pharmacologic inhibition of fatty acid synthase or stearoyl-coenzyme A desaturase inhibits, whereas exogenous addition of C16:1 or C18:1 but not their saturated acyl chain counterparts, activates SIRT1 and p53/STAT3 signaling and IL-1β/IL-18 release. Expression of the p53 target gene ASC [apoptosis-associated speck-like protein containing a C-terminal caspase recruitment domain (CARD)] required for assembly of the NLR family pyrin domain containing 3 (NLRP3) inflammasome is downregulated in FABP4 null mice and macrophage cell lines leading to loss of procaspase 1 activation and pyroptosis. Concomitant with loss of ASC expression in FABP4-/- macrophages, inflammasome activation, gasdermin D processing, and functional activation of pyroptosis are all diminished in FABP4 null macrophages but can be rescued by silencing SIRT1 or exogenous expression of ASC. Taken together, these results reveal a novel lipid-regulated pathway linking to SIRT1-p53-ASC signaling and activation of inflammasome action and pyroptosis.

Sirtuin Control of Mitochondrial Dysfunction, Oxidative Stress, and Inflammation in Chagas Disease Models

Trypanosoma cruzi is a digenetic parasite that requires triatomines and mammalian host to complete its life cycle. T. cruzi replication in mammalian host induces immune-mediated cytotoxic proinflammatory reactions and cellular injuries, which are the common source of reactive oxygen species (ROS) and reactive nitrogen species (RNS) during the acute parasitemic phase. Mitochondrial dysfunction of electron transport chain has been proposed as a major source of superoxide release in the chronic phase of infection, which renders myocardium exposed to sustained oxidative stress and contributes to Chagas disease pathology. Sirtuin 1 (SIRT1) is a class III histone deacetylase that acts as a sensor of redox changes and shapes the mitochondrial metabolism and inflammatory response in the host. In this review, we discuss the molecular mechanisms by which SIRT1 can potentially improve mitochondrial function and control oxidative and inflammatory stress in Chagas disease.

Viral Manipulation of the Host Epigenome as a Driver of Virus-Induced Oncogenesis

Tumorigenesis due to viral infection accounts for a high fraction of the total global cancer burden (15–20%) of all human cancers. A comprehensive understanding of the mechanisms by which viral infection leads to tumor development is extremely important. One of the main mechanisms by which viruses induce host cell proliferation programs is through controlling the host’s epigenetic machinery. In this review, we dissect the epigenetic pathways through which oncogenic viruses can integrate their genome into host cell chromosomes and lead to tumor progression. In addition, we highlight the potential use of drugs based on histone modifiers in reducing the global impact of cancer development due to viral infection.

Resveratrol Reduces COMPopathy in Mice Through Activation of Autophagy

Misfolding mutations in cartilage oligomeric matrix protein (COMP) cause it to be retained within the endoplasmic reticulum (ER) of chondrocytes, stimulating a multitude of damaging cellular responses including ER stress, inflammation, and oxidative stress, which ultimately culminates in the death of growth plate chondrocytes and pseudoachondroplasia (PSACH). Previously, we demonstrated that an antioxidant, resveratrol, substantially reduces the intracellular accumulation of mutant-COMP, dampens cellular stress, and lowers the level of growth plate chondrocyte death. In addition, we showed that resveratrol reduces mammalian target of rapamycin complex 1 (mTORC1) signaling, suggesting a potential mechanism. In this work, we investigate the role of autophagy in treatment of COMPopathies. In cultured chondrocytes expressing wild-type COMP or mutant-COMP, resveratrol significantly increased the number of Microtubule-associated protein 1A/1B-light chain 3 (LC3) vesicles, directly demonstrating that resveratrol-stimulated autophagy is an important component of the resveratrol-driven mechanism responsible for the degradation of mutant-COMP. Moreover, pharmacological inhibitors of autophagy suppressed degradation of mutant-COMP in our established mouse model of PSACH. In contrast, blockage of the proteasome did not substantially alter resveratrol clearance of mutant-COMP from growth plate chondrocytes. Mechanistically, resveratrol increased SIRT1 and PP2A expression and reduced MID1 expression and activation of phosphorylated protein kinase B (pAKT) and mTORC1 signaling in growth plate chondrocytes, allowing clearance of mutant-COMP by autophagy. Importantly, we show that optimal reduction in growth plate pathology, including decreased mutant-COMP retention, decreased mTORC1 signaling, and restoration of chondrocyte proliferation was attained when treatment was initiated between birth to 1 week of age in MT-COMP mice, translating to birth to approximately 2 years of age in children with PSACH. These results clearly demonstrate that resveratrol stimulates clearance of mutant-COMP by an autophagy-centric mechanism. © 2020 The Authors. JBMR Plus published by Wiley Periodicals LLC. on behalf of American Society for Bone and Mineral Research.

Mitochondrial Deoxyguanosine Kinase Regulates NAD+ Biogenesis Independent of Mitochondria Complex I Activity

Overexpression of DGUOK promotes mitochondria oxidative phosphorylation and lung adenocarcinoma progression. However, the role and mechanism of DGUOK in regulation of mitochondria function and lung cancer progression still poorly understood. Here we demonstrated that DGUOK regulated NAD⁺ biogenesis. Depletion of the DGUOK significantly decreased NAD⁺ level. Furthermore, knockout of the DGUOK considerably reduced expression of the NMNAT2, a key molecule controlling NAD⁺ synthesis, at both mRNA and protein levels. Ectopic expression of the NMNAT2 abrogated the effect of knockdown of DGUOK on NAD⁺. Notably, this regulation is independent of DGUOK -mediated mitochondria complex I activity. We also showed that NMNAT2 was highly expressed in lung adenocarcinoma and negatively correlated with the patient overall survival. Our study suggested that DGUOK regulates NAD⁺ in a NMNAT2 dependent manner and DGUOK-NMNAT2-NAD⁺ axis could be a potential therapeutic target in lung adenocarcinoma.

Circular and linear: a tale of aptamer selection for the activation of SIRT1 to induce death in cancer cells

It is a challenge to select the right target to treat conditions without affecting non-diseased cells. Cancer belongs to the top 10 causes of death in the world and it remains difficult to treat. Amongst cancer emerging targets, silent information regulator 1 (SIRT1) - a histone deacetylase - has shown many roles in cancer, ageing and metabolism. Here we report novel SIRT1 ligands that bind and modulate the activity of SIRT1 within cells and enhance its enzymatic activity. We developed a modified aptamer capable of binding to and forming a complex with SIRT1. Our ligands are aptamers, they can be made of DNA or RNA oligonucleotides, their binding domain can recognise a target with very high affinity and specificity. We used the systematic evolution of ligands by exponential enrichment (SELEX) technique to develop circular and linear aptamers selectively binding to SIRT1. Cellular consequences of the interaction were monitored by fluorescence microscopy, cell viability assay, stability and enzymatic assays. Our results indicate that from our pool of aptamers, circular AC3 penetrates cancerous cells and is recruited to modulate the SIRT1 activity. This modulation of SIRT1 resulted in anticancer activity on different cancer cell lines. Furthermore, this modified aptamer showed no toxicity on one non-cancerous cell line and was stable in human plasma. We have demonstrated that aptamers are efficient tools for localisation of internal cell targets, and in this particular case, anticancer activity through modulation of SIRT1.

Citrus hystrix Extracts Protect Human Neuronal Cells against High Glucose-Induced Senescence

Citrus hystrix (CH) is a beneficial plant utilized in traditional folk medicine to relieve various health ailments. The antisenescent mechanisms of CH extracts were investigated using human neuroblastoma cells (SH-SY5Y). Phytochemical contents and antioxidant activities of CH extracts were analyzed using a gas chromatograph–mass spectrometer (GC-MS), 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) assay and 2,2′-azino-bis (3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) assay. Effects of CH extracts on high glucose-induced cytotoxicity, reactive oxygen species (ROS) generation, cell cycle arrest and cell cycle-associated proteins were assessed using a 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide tetrazolium (MTT) assay, non-fluorescent 2′, 7′-dichloro-dihydrofluorescein diacetate (H₂DCFDA) assay, flow cytometer and Western blot. The extracts protected neuronal senescence by inhibiting ROS generation. CH extracts induced cell cycle progression by releasing senescent cells from the G1 phase arrest. As the Western blot confirmed, the mechanism involved in cell cycle progression was associated with the downregulation of cyclin D1, phospho-cell division cycle 2 (pcdc2) and phospho-Retinoblastoma (pRb) proteins. Furthermore, the Western blot showed that extracts increased Surtuin 1 (SIRT1) expression by increasing the phosphorylation of Glyceraldehyde 3-phosphate dehydrogenase (GAPDH). Collectively, CH extracts could protect high glucose-induced human neuronal senescence by inducing cell cycle progression and up-regulation of SIRT1, thus leading to the improvement of the neuronal cell functions.

Cycloastragenol upregulates SIRT1 expression, attenuates apoptosis and suppresses neuroinflammation after brain ischemia

Cycloastragenol (CAG) is the active form of astragaloside IV isolated from Astragalus Radix, which displays multiple pharmacological effects. Silent information regulator 1 (SIRT1), a class III histone deacetylase, has been shown to play an important role in neuroprotection against cerebral ischemia. In this study, we investigated whether CAG protected against ischemic brain injury and, if so, whether the beneficial effects were associated with the regulation of SIRT1 in the ischemic brain. Mice were subjected to 45 min of middle cerebral artery occlusion (MCAO) followed by reperfusion. CAG (5, 10, 20 mg/kg) was injected intraperitoneally at the onset of reperfusion, 12 h later and then twice daily for up to three days. CAG dose-dependently reduced brain infarct volume, significantly ameliorated functional deficits, and prevented neuronal cell loss in MCAO mice. Meanwhile, CAG significantly reduced matrix metalloproteinase-9 activity, prevented tight junction degradation and subsequently ameliorated blood-brain barrier disruption. Moreover, CAG significantly upregulated SIRT1 expression in the ischemic brain but did not directly activate its enzymatic activity. Concomitant with SIRT1 upregulation, CAG reduced p53 acetylation and the ratio of Bax to Bcl-2 in the ischemic brain. CAG also inhibited NF-κB p65 nuclear translocation. As a result, CAG suppressed the mRNA expression of pro-inflammatory cytokines, including TNF-α and IL-1β, and inhibited the activation of microglia and astrocytes in the ischemic brain. Our findings suggest that CAG is neuroprotective against ischemic brain injury in mice and that its beneficial effect may involve SIRT1 upregulation and the inhibition of apoptosis and neuroinflammation in the ischemic brain.

Impact of glucocorticoids on systemic sirtuin 1 expression and activity in rats with adjuvant-induced arthritis

The class III histone deacetylase sirtuin 1 (SIRT1) plays a pivotal role in numerous biological and physiological functions, including inflammation. An association between SIRT1 and proinflammatory cytokines might exist. In addition to their important role in inflammation associated with rheumatoid arthritis (RA), proinflammatory cytokines mediate the development of systemic effects. Here, we evaluated systemic SIRT1 expression and enzymatic activity, in peripheral blood mononuclear cells (PBMCs) and in liver isolated from rats with adjuvant-induced arthritis (AIA), treated or not with low or high doses of glucocorticoids (GCs). We also measured the production of tumour necrosis factor alpha (TNF) and interleukin-1 beta (IL-1 beta) in PBMCs and liver. We found that SIRT1 expression and activity increased in PBMCs of AIA rats compared to healthy controls and decreased under GC treatment. Similarly, we observed an increased SIRT1 activity in the liver of AIA rats compared to healthy controls which decreased under high doses of GCs. We also found an increase in IL-1 beta and TNF levels in the liver of AIA rats compared to healthy controls, which decreased under high doses of GC. We did not observe a significant correlation between SIRT1 activity and proinflammatory cytokine production in PBMC or liver. In contrast, a strong positive correlation was found between the liver levels of TNF and IL-1 beta (rho=0.9503, p=7.5x10^-21). Our results indicate that increased inflammation in AIA rats compared to healthy control is accompanied by an increased SIRT1 activity in both PBMCs and liver, which could be decreased under GC treatment.

Nuclear Respiratory Factor 1 (NRF1) Transcriptional Activity-Driven Gene Signature Association with Severity of Astrocytoma and Poor Prognosis of Glioblastoma

Despite tremendous progress in understanding the pathobiology of astrocytoma, major gaps remain in our knowledge of the molecular basis underlying the aggressiveness of high-grade astrocytoma (glioblastoma - GBM). Recently, we and others have shown nuclear respiratory factor 1 (NRF1) transcription factor being highly active in human cancers, but its role in astrocytoma remains unknown. Therefore, the purpose of this study was to uncover the role of NRF1 in the progression of GBM. NRF1 has higher mRNA expression and transcription factor activity in astrocytoma compared to non-tumor brain tissue. NRF1 activity also correlated with the aggressiveness of cancer. Increased NRF1 TF activity coupled with overexpression of RHOG was associated with poor survival of GBM patients. NRF1 activity was associated with transcriptomic signatures of neurogenesis, cell stemness, epithelial-mesenchymal transition and cell cycle progression. Overexpression of CDK4, AKT1, APAF1, HDAC1, NBN, TGFB1, & TNFRSF1A and downregulation of CASP3, IL7, STXBP1 and OPA1 predicted GBM malignancy in high expressors of NRF1 activity. Increased expression of the NRF1 motif containing genes, H6PD, NAT10, NBEAL2, and RNF19B predicted poor survival of IDH1 wild-type GBM patients. Poor survival outcomes and resistance to Temozolomide therapy were associated with higher NRF1 expression including its targets - LDHA, ZMAT3, NSUN2, ARMC5, NDEL1, CLPTM1L, ALKBH5, YIPF5, PPP2CA, and TFG. These findings suggest that aberrant NRF1 activity may contribute to the pathogenesis of GBM and severity of astrocytoma. Further analyses of NRF1 gene signatures will pave the way for next generation targeted therapies and drug combination strategies for GBM patients.

Glucose as a Major Antioxidant: When, What for and Why It Fails?

A human organism depends on stable glucose blood levels in order to maintain its metabolic needs. Glucose is considered to be the most important energy source, and glycolysis is postulated as a backbone pathway. However, when the glucose supply is limited, ketone bodies and amino acids can be used to produce enough ATP. In contrast, for the functioning of the pentose phosphate pathway (PPP) glucose is essential and cannot be substituted by other metabolites. The PPP generates and maintains the levels of nicotinamide adenine dinucleotide phosphate (NADPH) needed for the reduction in oxidized glutathione and protein thiols, the synthesis of lipids and DNA as well as for xenobiotic detoxification, regulatory redox signaling and counteracting infections. The flux of glucose into a PPP—particularly under extreme oxidative and toxic challenges—is critical for survival, whereas the glycolytic pathway is primarily activated when glucose is abundant, and there is lack of NADP⁺ that is required for the activation of glucose-6 phosphate dehydrogenase. An important role of glycogen stores in resistance to oxidative challenges is discussed. Current evidences explain the disruptive metabolic effects and detrimental health consequences of chronic nutritional carbohydrate overload, and provide new insights into the positive metabolic effects of intermittent fasting, caloric restriction, exercise, and ketogenic diet through modulation of redox homeostasis.

Differential Expression of KRAS and SIRT1 in Ovarian Cancers with and Without Endometriosis

Accumulating research shows that ovarian cancer progression can be influenced by both gene mutations and endometriosis. However, the exact mechanism at hand is poorly understood. In the current study, we explored the expression of KRAS and SIRT1, two genes previously identified as altered in endometriosis and ovarian cancer. Human endometrial samples were obtained from regularly cycling women with endometriosis, ovarian cancer, and endometriosis-associated ovarian cancer between 18 and 50 of age undergoing hysterectomy, and immunohistochemical analyses were performed. The cytoplasmic expression of KRAS was low in eutopic endometrium from women without endometriosis or ovarian cancer; however, it was elevated in those who have been diagnosed with endometriosis, as well as ovarian cancer with or without the presence of endometriosis. Nuclear and cytoplasmic SIRT1 expression was also low within endometrium without either disease. However, nuclear SIRT1 expression was increased in those with endometriosis and ovarian cancer associated with endometriosis. Nuclear but not the cytoplasmic expression of SIRT1 correlated with KRAS expression in ovarian cancers associated with endometriosis. These results suggest roles of KRAS and SIRT1 in endometriosis and endometriosis-associated ovarian cancer. Cytoplasmic KRAS expression proves to be a key biomarker in both diseases, while nuclear SIRT1 may be a new biomarker specific to those with endometriosis and those with both endometriosis and ovarian cancer. Further research of these genes could aid in determining the pathogenesis of both diseases and help in clarifying the development of endometriosis-associated ovarian cancer.

Diverse therapeutic efficacies and more diverse mechanisms of nicotinamide

BACKGROUND

Nicotinamide (NAM) is a form of vitamin B3 that, when administered at near-gram doses, has been shown or suggested to be therapeutically effective against many diseases and conditions. The target conditions are incredibly diverse ranging from skin disorders such as bullous pemphigoid to schizophrenia and depression and even AIDS. Similar diversity is expected for the underlying mechanisms. In a large portion of the conditions, NAM conversion to nicotinamide adenine dinucleotide (NAD⁺) may be a major factor in its efficacy. The augmentation of cellular NAD⁺ level not only modulates mitochondrial production of ATP and superoxide, but also activates many enzymes. Activated sirtuin proteins, a family of NAD⁺-dependent deacetylases, play important roles in many of NAM's effects such as an increase in mitochondrial quality and cell viability countering neuronal damages and metabolic diseases. Meanwhile, certain observed effects are mediated by NAM itself. However, our understanding on the mechanisms of NAM's effects is limited to those involving certain key proteins and may even be inaccurate in some proposed cases.

AIM OF REVIEW

This review details the conditions that NAM has been shown to or is expected to effectively treat in humans and animals and evaluates the proposed underlying molecular mechanisms, with the intention of promoting wider, safe therapeutic application of NAM.

KEY SCIENTIFIC CONCEPTS OF REVIEW

NAM, by itself or through altering metabolic balance of NAD⁺ and tryptophan, modulates mitochondrial function and activities of many molecules and thereby positively affects cell viability and metabolic functions. And, NAM administration appears to be quite safe with limited possibility of side effects which are related to NAM's metabolites.

Hydrolyzed Rutin Decreases Worsening of Anaplasia in Glioblastoma Relapse

Background:

Gliomas are aggressive and resilient tumors. Progression to advanced stages of malignancy, characterized by cell anaplasia, necrosis, and reduced response to conventional surgery or therapeutic adjuvant, are critical challenges in glioma therapy. Relapse of the disease poses a considerable challenge for management. Hence, new compounds are required to improve therapeutic response. As hydrolyzed rutin (HR), a compound modified via rutin deglycosylation, as well as some flavonoids demonstrated antiproliferative effect for glioblastoma, these are considered potential epigenetic drugs.

Objective:

The purpose of this study was to determine the antitumor activity and evaluate the potential for modifying tumor aggressivity of rutin hydrolysates for treating both primary and relapsed glioblastoma.

Methods:

The glioblastoma cell line, U251, was used for analyzing cell cycle inhibition and apoptosis and for establishing the GBM mouse model. Mice with GBM were treated with HR to verify antitumor activity. Histological analysis was used to evaluate HR interference in aggressive behavior and glioma grade. Immunohistochemistry, comet assay, and thiobarbituric acid reactive substance (TBARS) values were used to evaluate the mechanism of HR action.

Results:

HR is an antiproliferative and antitumoral compound that inhibits the cell cycle via a p53- independent pathway. HR reduces tumor growth and aggression, mainly by decreasing mitosis and necrosis rates without genotoxicity, which is suggestive of epigenetic modulation.

Conclusion:

HR possesses antitumor activity and decreases anaplasia in glioblastoma, inhibiting progression to malignant stages of the disease. HR can improve the effectiveness of response to conventional therapy, which has a crucial role in recurrent glioma.

Knockout of longevity gene Sirt1 in zebrafish leads to oxidative injury, chronic inflammation, and reduced life span

Sirt1, a member of the sirtuin gene family, encodes the most conserved mammalian NAD⁺-dependent deacetylase enzyme responsible for removing acetyl groups from many proteins. The Sirt1 gene is known as a longevity gene whose knockout in mice leads to decreased lifespan relative to the wild type. This study aimed to explore phenotypic changes in zebrafish Sirt1-knockouts and to investigate the function of the Sirt1 gene. Targeted knockout of Sirt1 in zebrafish (Danio rerio) was achieved using the CRISPR-Cas9 genome editing system. We created a 4-bp insertion-homozygote Sirt1-knockout zebrafish. Although there was no evident difference in appearance in the early stages of development, a significant increase in reactive oxygen species and in the extent of apoptosis in Sirt1-knockout zebrafish was observed. Sirt1 knockout caused inflammatory genes, including IL-1b, IL-6 and TNF-α to be highly expressed. Additionally, the lack of Sirt1 caused chronic inflammation and intestinal atrophy, thereby increasing pro-apoptotic events, which ultimately reduced the lifespan of transgenic zebrafish. Overall, our data demonstrate that lack of Sirt1 caused a significantly increased generation of reactive oxygen species that resulted in chronic inflammation and regeneration. Continuous repetition of these events played an important role in accelerating aging, thereby decreasing lifespan. Our findings using the knockout zebrafish model confirmed the association of the Sirt1 gene to aging processes and lifespan. Furthermore, the Sirt1-knockout mutant zebrafish developed in our study will surely be a valuable model to explore the mechanism of chronic inflammation.

Sirtuin-1 in immunotherapy: A Janus-headed target

Sirtuin-1 (Sirt1), a member of the NAD-dependent sirtuin family of histone/protein deacetylases (HDAC), is an important target for immunotherapy due to its role in deacetylating the transcription factors Foxp3 and thymic retinoid acid receptor related orphan receptor gamma (RORγt). Sirt1 inhibition can increase Foxp3 acetylation and promote the production and functions of Foxp3+ T-regulatory (Treg) cells, whereas the acetylation of RORγt decreases its transcriptional activity DNA binding and decreases the differentiation of proinflammatory Th17 cells. Pharmacologic inhibitors of Sirt1 increase allograft survival and decrease autoimmune colitis and experimental allergic encephalomyelitis. However, in contrast to its role in T cells, Sirt1 has anti-inflammatory effects in myeloid cells, and, context dependent, in Th17 cells. Here, inhibition of Sirt1 can have proinflammatory effects. In addition to effects arising from the central role of Sirt1 in cellular metabolism and NAD-dependent reactions, such proinflammatory effects further complicate the potential of Sirt1 for therapeutic immunosuppression. This review aims to reconcile the opposing literature on pro- and anti-inflammatory effects of Sirt1, provides an overview of the role of Sir1 in the immune system, and discusses the pros and cons associated with inhibiting Sirt1 for control of inflammation and immune responses.

NAD-Biosynthetic and Consuming Enzymes as Central Players of Metabolic Regulation of Innate and Adaptive Immune Responses in Cancer

Cancer cells, particularly in solid tumors, are surrounded by non-neoplastic elements, including endothelial and stromal cells, as well as cells of immune origin, which can support tumor growth by providing the right conditions. On the other hand, local hypoxia, and lack of nutrients induce tumor cells to reprogram their metabolism in order to survive, proliferate, and disseminate: the same conditions are also responsible for building a tumor-suppressive microenvironment. In addition to tumor cells, it is now well-recognized that metabolic rewiring occurs in all cellular components of the tumor microenvironment, affecting epigenetic regulation of gene expression and influencing differentiation/proliferation decisions of these cells. Nicotinamide adenine dinucleotide (NAD) is an essential co-factor for energy transduction in metabolic processes. It is also a key component of signaling pathways, through the regulation of NAD-consuming enzymes, including sirtuins and PARPs, which can affect DNA plasticity and accessibility. In addition, both NAD-biosynthetic and NAD-consuming enzymes can be present in the extracellular environment, adding a new layer of complexity to the system. In this review we will discuss the role of the “NADome” in the metabolic cross-talk between cancer and infiltrating immune cells, contributing to cancer growth and immune evasion, with an eye to therapeutic implications.

MiRNA-210 induces microglial activation and regulates microglia-mediated neuroinflammation in neonatal hypoxic-ischemic encephalopathy

Neuroinflammation is a major contributor to secondary neuronal injury that accounts for a significant proportion of final brain cell loss in neonatal hypoxic-ischemic encephalopathy (HIE). However, the immunological mechanisms that underlie HIE remain unclear. MicroRNA-210 (miR-210) is the master "hypoxamir" and plays a key role in hypoxic-ischemic tissue damage. Herein, we report in an animal model of neonatal rats that HIE significantly upregulated miR-210 expression in microglia in the neonatal brain and strongly induced activated microglia. Intracerebroventricular administration of miR-210 antagomir effectively suppressed microglia-mediated neuroinflammation and significantly reduced brain injury caused by HIE. We demonstrated that miR-210 induced microglial M1 activation partly by targeting SIRT1, thereby reducing the deacetylation of the NF-κB subunit p65 and increasing NF-κB signaling activity. Thus, our study identified miR-210 as a novel regulator of microglial activation in neonatal HIE, highlighting a potential therapeutic target in the treatment of infants with hypoxic-ischemic brain injury.

Melatonin protects the heart and endothelium against high fructose corn syrup consumption-induced cardiovascular toxicity via SIRT-1 signaling

High fructose corn syrup (HFCS) has been shown to cause cardiovascular toxicity via oxidative stress and inflammation. The aim of this study is to demonstrate the protective effects of melatonin (MLT) against HFCS-induced endothelial and cardiac dysfunction via oxidative stress and inflammation. Thirty-two Sprague Dawley male rats were distributed into three groups as control, HFCS, and HFCS + MLT. HFCS form F55 was prepared as 20% fructose syrup solution and given to the rats through drinking water for 10 weeks, and MLT administrated 10 mg/kg/day orally for last 6 weeks in addition to F55. After decapitation, blood and half of the heart samples were collected for biochemical analysis and other half of the tissues for histopathological and immunohistochemical analysis. Aspartate transaminase, creatine kinase MB, lactate dehydrogenase, total oxidant status and oxidative stress index, and caspase-3 levels increased and total antioxidant status levels decreased significantly in HFCS group. MLT treatment reversed all these parameters. Histopathologically, hyperemia, endothelial cell damage and increased levels of angiogenin, C-reactive protein, inducible nitric oxide synthase, myeloperoxidase and decreased sirtuin-1 (SIRT-1) expressions were observed in HFCS group. MLT ameliorated all these changes. MLT has an anti-inflammatory, antioxidant, antiapoptotic effects on HFCS-induced cardiovascular toxicity through enhancing the expression of SIRT-1.

Heme Oxygenase-1 Inhibition Sensitizes Human Prostate Cancer Cells towards Glucose Deprivation and Metformin-Mediated Cell Death

High levels of heme oxygenase (HO)-1 have been frequently reported in different human cancers, playing a major role in drug resistance and regulation of cancer cell redox homeostasis. Metformin (MET), a drug widely used for type 2 diabetes, has recently gained interest for treating several cancers. Recent studies indicated that the anti-proliferative effects of metformin in cancer cells are highly dependent on glucose concentration. The present work was directed to determine whether use of a specific inhibitor of HO-1 activity, alone or in combination with metformin, affected metastatic prostate cancer cell viability under different concentrations of glucose. MTT assay and the xCELLigence system were used to evaluate cell viability and cell proliferation in DU145 human prostate cancer cells. Cell apoptosis and reactive oxygen species were analyzed by flow cytometry. The activity of HO-1 was inhibited using a selective imidazole-based inhibitor; genes associated with antioxidant systems and cell death were evaluated by qRT-PCR. Our study demonstrates that metformin suppressed prostate cancer growth in vitro and increased oxidative stress. Disrupting the antioxidant HO-1 activity, especially under low glucose concentration, could be an attractive approach to potentiate metformin antineoplastic effects and could provide a biochemical basis for developing HO-1-targeting drugs against solid tumors.

Celastrol Protects From Cholestatic Liver Injury Through Modulation of SIRT1-FXR Signaling

Celastrol, derived from the roots of the Tripterygium Wilfordi, shows a striking effect on obesity. In the present study, the role of celastrol in cholestasis was investigated using metabolomics and transcriptomics. Celastrol treatment significantly alleviated cholestatic liver injury in mice induced by α-naphthyl isothiocyanate (ANIT) and thioacetamide (TAA). Celastrol was found to activate sirtuin 1 (SIRT1), increase farnesoid X receptor (FXR) signaling and inhibit nuclear factor-kappa B and P53 signaling. The protective role of celastrol in cholestatic liver injury was diminished in mice on co-administration of SIRT1 inhibitors. Further, the effects of celastrol on cholestatic liver injury were dramatically decreased in Fxr-null mice, suggesting that the SIRT1-FXR signaling pathway mediates the protective effects of celastrol. These observations demonstrated a novel role for celastrol in protecting against cholestatic liver injury through modulation of the SIRT1 and FXR.

Inhibition of SIRT1 deacetylase and p53 activation uncouples the anti-inflammatory and chemopreventive actions of NSAIDs

Background

Nonsteroidal anti-inflammatory drugs (NSAIDs) have been proposed as chemopreventive agents for many tumours; however, the mechanism responsible for their anti-neoplastic activity remains elusive and the side effects due to cyclooxygenase (COX) inhibition prevent this clinical application.

Methods

Molecular biology, in silico, cellular and in vivo tools, including innovative in vivo imaging and classical biochemical assays, were applied to identify and characterise the COX-independent anti-cancer mechanism of NSAIDs.

Results

Here, we show that tumour-protective functions of NSAIDs and exisulind (a sulindac metabolite lacking anti-inflammatory activity) occur through a COX-independent mechanism. We demonstrate these NSAIDs counteract carcinogen-induced proliferation by inhibiting the sirtuin 1 (SIRT1) deacetylase activity, augmenting acetylation and activity of the tumour suppressor p53 and increasing the expression of the antiproliferative gene p21. These properties are shared by all NSAIDs except for ketoprofen lacking anti-cancer properties. The clinical interest of the mechanism identified is underlined by our finding that p53 is activated in mastectomy patients undergoing intraoperative ketorolac, a treatment associated with decreased relapse risk and increased survival.

Conclusion

Our study, for the first-time, links NSAID chemopreventive activity with direct SIRT1 inhibition and activation of the p53/p21 anti-oncogenic pathway, suggesting a novel strategy for the design of tumour-protective drugs.

Modulating Effect of Diet on Alzheimer's Disease

As life expectancy is growing, neurodegenerative disorders, such as Alzheimer's disease, are increasing. This disease is characterised by the accumulation of intracellular neurofibrillary tangles formed by hyperphosphorylated tau protein, senile plaques composed of an extracellular deposit of β-amyloid peptide (Aβ), and neuronal loss. This is accompanied by deficient mitochondrial function, increased oxidative stress, altered inflammatory response, and autophagy process impairment. The present study gathers scientific evidence that demonstrates that specific nutrients exert a direct effect on both Aβ production and Tau processing and their elimination by autophagy activation. Likewise, certain nutrients can modulate the inflammatory response and the oxidative stress related to the disease. However, the extent to which these effects come with beneficial clinical outcomes remains unclear. Even so, several studies have shown the benefits of the Mediterranean diet on Alzheimer's disease, due to its richness in many of these compounds, to which can be attributed their neuroprotective properties due to the pleiotropic effect they show on the aforementioned processes. These indications highlight the potential role of adequate dietary recommendations for clinical management of both Alzheimer's diagnosed patients and those in risk of developing it, emphasising once again the importance of diet on health.

Nicotinamide Mononucleotide: Exploration of Diverse Therapeutic Applications of a Potential Molecule

Nicotinamide mononucleotide (NMN) is a nucleotide that is most recognized for its role as an intermediate of nicotinamide adenine dinucleotide (NAD+) biosynthesis. Although the biosynthetic pathway of NMN varies between eukaryote and prokaryote, two pathways are mainly followed in case of eukaryotic human-one is through the salvage pathway using nicotinamide while the other follows phosphorylation of nicotinamide riboside. Due to the unavailability of a suitable transporter, NMN enters inside the mammalian cell in the form of nicotinamide riboside followed by its subsequent conversion to NMN and NAD+. This particular molecule has demonstrated several beneficial pharmacological activities in preclinical studies, which suggest its potential therapeutic use. Mostly mediated by its involvement in NAD+ biosynthesis, the pharmacological activities of NMN include its role in cellular biochemical functions, cardioprotection, diabetes, Alzheimer's disease, and complications associated with obesity. The recent groundbreaking discovery of anti-ageing activities of this chemical moiety has added a valuable essence in the research involving this molecule. This review focuses on the biosynthesis of NMN in mammalian and prokaryotic cells and mechanism of absorption along with the reported pharmacological activities in murine model.

Cancer Etiology: A Metabolic Disease Originating from Life's Major Evolutionary Transition?

A clear understanding of the origins of cancer is the basis of successful strategies for effective cancer prevention and management. The origin of cancer at the molecular and cellular levels is not well understood. Is the primary cause of the origin of cancer the genomic instability or impaired energy metabolism? An attempt was made to present cancer etiology originating from life's major evolutionary transition. The first evolutionary transition went from simple to complex cells when eukaryotic cells with glycolytic energy production merged with the oxidative mitochondrion (The Endosymbiosis Theory first proposed by Lynn Margulis in the 1960s). The second transition went from single-celled to multicellular organisms once the cells obtained mitochondria, which enabled them to obtain a higher amount of energy. Evidence will be presented that these two transitions, as well as the decline of NAD+ and ATP levels, are the root of cancer diseases. Restoring redox homeostasis and reactivation of mitochondrial oxidative metabolism are important factors in cancer prevention.

S-Adenosylmethionine regulates apoptosis and autophagy in MCF-7 breast cancer cells through the modulation of specific microRNAs

Background

To get insight into the molecular mechanisms underlying the anti-tumor activity of S-adenosyl-l-methionine (AdoMet), we analyzed AdoMet-induced modulation of microRNAs (miRNAs) expression profile in MCF-7 breast cell line and its correlation with cancer-related biological pathways.

Methods

MiRNA expression profiling was performed using a TaqMan MiRNA Array, following 500 µM AdoMet-treatment. The results were confirmed by Quantitative real-time PCR analysis. MCF-7 were transfected with miR-34a, miR-34c and miR-486-5p, mimics and inhibitors in presence or not of 500 µM AdoMet for 72 h. Apoptosis and autophagy were analyzed by flow cytometry and the modulation of the main antiproliferative signaling pathways were evaluated by Western blotting. The potential mRNA targets for each miRNA were identified by the TargetScan miRNA target prediction software.

Results

Twenty-eight microRNAs resulted differentially expressed in AdoMet-treated MCF-7 cells compared to control cells. Among them, miRNA-34a and miRNA-34c were up-regulated while miRNA-486-5p was down-regulated. Moreover, we confirmed the ability of AdoMet to regulate these miRNAs in MDA-MB 231 breast cancer cell line. We demonstrate that, in MCF7 cells, the combination of either miR-34a or miR-34c mimic with AdoMet greatly potentiated the pro-apoptotic effect of AdoMet, by a caspase-dependent mechanism and activates p53 acetylation by inhibiting SIRT1 and HDAC1 expression. We also showed that miR-486-5p inhibitor induces autophagy and enhances AdoMet-induced autophagic process by increasing PTEN expression and by inhibiting AKT signaling.

Conclusions

Our findings provide the first evidence that AdoMet can regulate miRNA expression in MCF-7 increasing our knowledge on the molecular basis of the antitumor effect of the sulfonium compound and suggest the use of AdoMet as an attractive miRNA-mediated chemopreventive and therapeutic strategy in breast cancer.

Sirtuin1 Targeting Reverses Innate and Adaptive Immune Tolerance in Septic Mice

Resistance and tolerance to infection are two universal fitness and survival strategies used by inflammation and immunity in organisms and cells to guard homeostasis. During sepsis, however, both strategies fail, and animal and human victims often die from combined innate and adaptive immune suppression with persistent bacterial and viral infections. NAD⁺-sensing nuclear sirtuin1 (SIRT1) epigenetically guards immune and metabolic homeostasis during sepsis. Pharmacologically inhibiting SIRT1 deacetylase activity in septic mice reverses monocyte immune tolerance, clears infection, rebalances glycolysis and glucose oxidation, resolves organ dysfunction, and prevents most septic deaths. Whether SIRT1 inhibition during sepsis treatment concomitantly reverses innate and T cell antigen-specific immune tolerance is unknown. Here, we show that treating septic mice with a SIRT1 selective inhibitor concordantly reverses immune tolerance splenic dendritic and antigen-specific tolerance of splenic CD4+ and CD8+ T cells. SIRT1 inhibition also increases the ratio of IL12 p40+ and TNFα proinflammatory/immune to IL10 and TGFβ anti-inflammatory/immune cytokines and decreases the ratio of CD4+ T_Reg repressor to CD4+ activator T cells. These findings support the unifying concept that nuclear NAD⁺ sensor SIRT1 broadly coordinates innate and adaptive immune reprogramming during sepsis and is a druggable immunometabolic enhancement target.

Resveratrol stimulates the metabolic reprogramming of human CD4+ T cells to enhance effector function

The polyphenol resveratrol activates the deacetylase Sirt1, resulting in various antioxidant, chemoprotectant, neuroprotective, cardioprotective, and anti-inflammatory properties. We found that at high concentrations of resveratrol, human CD4⁺ T cells showed defective antigen receptor signaling and arrest at the G₁ stage of the cell cycle, whereas at low concentrations, cells were readily activated and exhibited enhanced Sirt1 deacetylase activity. Nevertheless, low-dose resveratrol rapidly stimulated genotoxic stress in the T cells, which resulted in engagement of a DNA damage response pathway that depended on the kinase ATR [ataxia telangiectasia-mutated (ATM) and Rad3-related], but not ATM, and subsequently in premitotic cell cycle arrest. The concomitant activation of p53 was coupled to the expression of gene products that regulate cell metabolism, leading to a metabolic reprogramming that was characterized by decreased glycolysis, increased glutamine consumption, and a shift to oxidative phosphorylation. These alterations in the bioenergetic homeostasis of CD4⁺ T cells resulted in enhanced effector function, with both naïve and memory CD4⁺ T cells secreting increased amounts of the inflammatory cytokine interferon-γ. Thus, our data highlight the wide range of metabolic adaptations that CD4⁺ T lymphocytes undergo in response to genomic stress.

p53 inhibits the upregulation of sirtuin 1 expression induced by c-Myc

Sirtuin 1 (Sirt1), a conserved NAD⁺ dependent deacetylase, is a mediator of life span by calorie restriction. However, Sirt1 may paradoxically increase the risk of cancer. Accordingly, the expression level of Sirt1 is selectively elevated in numerous types of cancer cell; however, the mechanisms underlying the differential regulation remain largely unknown. The present study demonstrated that oncoprotein c-Myc was a direct regulator of Sirt1, which accounts for the upregulation of Sirt1 expression only in the cells without functional p53. In p53 deficient cells, the overexpression of c-Myc increased Sirt1 mRNA and protein expression levels as well as its promoter activity, whereas the inhibitor of c-Myc, 10058-F4, induced decreased Sirt1 basal mRNA and protein expression levels. Deletion/mutation mapping analyses revealed that c-Myc bound to the conserved E-box[-189 to -183 base pair (bp)] of the Sirt1 promoter. In addition, p53 and c-Myc shared at least response element and the presence of p53 may block the binding of c-Myc to the Sirt1 promoter, thus inhibit the c-Myc mediated upregulation of Sirt1 promoter activity. The present study indicated that the expression level of Sirt1 was tightly regulated by oncoprotein c-Myc and tumor suppressor p53, which aids an improved understanding of its expression regulation and tumor promoter role in certain conditions.

6-Methoxyethylamino-numonafide inhibits hepatocellular carcinoma xenograft growth as a single agent and in combination with sorafenib

Hepatocellular carcinoma (HCC) is the third leading form of cancer worldwide, and its incidence is increasing rapidly in the United States, tripling over the past 3 decades. The current chemotherapeutic strategies against localized and metastatic HCC are ineffective. Here we report that 6-methoxyethylamino-numonafide (MEAN) is a potent growth inhibitor of murine xenografts of 2 human HCC cell lines. At the same dose and with the same treatment strategies, MEAN was more efficacious in inhibiting tumor growth in mice than sorafenib, the only approved drug for HCC. Treatment by MEAN at an effective dose for 6 wk was well tolerated by animals. Combined therapy using both sorafenib and MEAN enhanced tumor growth inhibition over monotherapy with either agent. Additional experiments revealed that MEAN inhibited tumor growth through mechanisms distinct from those of either its parent compound, amonafide, or sorafenib. MEAN suppressed C-MYC expression and increased expression of several tumor suppressor genes, including Src homology region 2 domain-containing phosphatase-1 (SHP-1) and TXNIP (thioredoxin-interacting protein). As an encouraging feature for envisioned clinical application, the IC₅₀ of MEAN was not significantly changed in several drug-resistant cell lines with activated P-glycoprotein drug efflux pumps compared to drug-sensitive parent cells, demonstrating the ability of MEAN to be effective in cells resistant to existing chemotherapy regimens. MEAN is a promising candidate for clinical development as a single-agent therapy or in combination with sorafenib for the management of HCC.-Liu, Y., Lou, G., Norton, J. T., Wang, C., Kandela, I., Tang, S., Shank, N. I., Gupta, P., Huang, M., Avram, M. J., Green, R., Mazar, A., Appella, D., Chen, Z., Huang, S. 6-Methoxyethylamino-numonafide inhibits hepatocellular carcinoma xenograft growth as a single agent and in combination with sorafenib.

Nicotinamide Ameliorates Disease Phenotypes in a Human iPSC Model of Age-Related Macular Degeneration

Age-related macular degeneration (AMD) affects the retinal pigment epithelium (RPE), a cell monolayer essential for photoreceptor survival, and is the leading cause of vision loss in the elderly. There are no disease-altering therapies for dry AMD, which is characterized by accumulation of subretinal drusen deposits and complement-driven inflammation. We report the derivation of human-induced pluripotent stem cells (hiPSCs) from patients with diagnosed AMD, including two donors with the rare ARMS2/HTRA1 homozygous genotype. The hiPSC-derived RPE cells produce several AMD/drusen-related proteins, and those from the AMD donors show significantly increased complement and inflammatory factors, which are most exaggerated in the ARMS2/HTRA1 lines. Using a panel of AMD biomarkers and candidate drug screening, combined with transcriptome analysis, we discover that nicotinamide (NAM) ameliorated disease-related phenotypes by inhibiting drusen proteins and inflammatory and complement factors while upregulating nucleosome, ribosome, and chromatin-modifying genes. Thus, targeting NAM-regulated pathways is a promising avenue for developing therapeutics to combat AMD.

Cyanidin 3-O-β-Glucoside Ameliorates Ethanol-Induced Acute Liver Injury by Attenuating Oxidative Stress and Apoptosis: The Role of SIRT1/FOXO1 Signaling

BACKGROUND

The aim of this study was to examine the effects of Cyanidin 3-O-β-glucoside (C3G) on ethanol (EtOH)-induced acute liver injury in mice as well as in cultured hepatic cells exposed to EtOH, with a focus on the involvement of Silent Mating Type Information Regulation 2 Homolog 1 (SIRT1)/Forkhead fox-O-1 (FOXO1) signaling pathway, and to explore the underlying molecular mechanisms.

METHODS

C57BL/6 adolescent male mice were given EtOH via intraperitoneal injection for 2 consecutive days, and the changes in the livers were detected via hematoxylin-eosin staining. The levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were measured by biochemical methods. Protein expression of SIRT1, FOXO1, acetylated FOXO1 (ac-FOXO1), GRP78, p-eukaryotic initiation factor-2 (eIF2α), and apoptosis (p-JNK, p-c-Jun, and Bax) parameters was determined by Western blot. Reactive oxygen species (ROS) was detected by flow cytometry. Human hepatocytes Chang cell line was used to assay cell apoptosis by Annexin V and propidium iodide. In addition, mRNA levels of SIRT1, tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6), and monocyte chemoattractant protein 1 in liver tissues were detected by real-time polymerase chain reaction.

RESULTS

This study demonstrated that C3G (10 mg/kg) administration diminished EtOH-induced acute liver injury compared to control group, as evidenced by the significant decreases in ALT and AST levels. Pretreatment with C3G exerted anti-inflammatory effects as indicated by the decreased TNF-α and IL-6 levels, as well as decreased inflammatory foci and ballooning cells in liver tissue. The lessened hepatic injury was associated with enhanced SIRT1 protein expression and activity by C3G in vitro and in vivo. C3G treatment also provoked significant attenuation of endoplasmic reticulum stress parameters (GRP78, p-eIF2α), which was consistent with reduced levels of both p-c-Jun and Bax. Interestingly, EX527 inhibitor did not affect the protective function of C3G on alcohol-induced cell apoptosis. Moreover, alcohol exposure increased ROS level and decreased ac-FOXO1, while C3G intervention reversed this abnormality, and this may be related to SIRT1 activity by C3G.

CONCLUSIONS

Anthocyanin C3G has significant potency in antioxidant, anti-inflammatory, and anti-apoptotic effects on hepatocytes exposed to EtOH by modulating the SIRT1/FOXO1 signaling pathway. Our findings illustrate a novel and definitive therapeutic action of C3G and represent an economically feasible therapeutic intervention to treat alcoholic liver disease.

More than skin deep? Potential nicotinamide treatment applications in chronic kidney transplant recipients

Non-melanoma cutaneous carcinomas, or skin cancers, predominantly squamous cell carcinomas (SCCs), are the most common malignancies occurring in kidney transplant recipients (KTRs). Squamous cell carcinoma risk is dramatically elevated in KTRs, occurring at rates of up 45-250 times those reported in general populations. New non-melanoma skin cancers in KTRs with a prior non-melanoma skin cancer also develop at 3-times the rate reported in non-KTRs with the same clinical history. The unique aggressiveness of SCCs in KTRs increases patient morbidity, due to the high rate of new lesions requiring treatment, frequently surgical excision. Oral nicotinamide shows promise in the chemoprevention of the especially aggressive non-melanoma skin cancers which occur in KTRs. This benefit might be conferred via its inhibition of sirtuin enzymatic pathways. Nicotinamide’s concurrent hypophosphatemic effect may also partially ameliorate the disturbed calcium-phosphorus homeostasis in these patients-a putative risk factor for mortality, and graft failure. Conceivably, a phase 3 trial of nicotinamide for the prevention of non-melanoma skin cancers in KTRs, lasting at least 12-mo, could also incorporate imaging and laboratory measures which assess nicotinamide’s impact on subclinical cardiovascular and chronic kidney disease risk, and progression.

Treatment of cardiovascular pathology with epigenetically active agents: Focus on natural and synthetic inhibitors of DNA methylation and histone deacetylation

Cardiovascular disease (CVD) retains a leadership as a major cause of human death worldwide. Although a substantial progress was attained in the development of cardioprotective and vasculoprotective drugs, a search for new efficient therapeutic strategies and promising targets is under way. Modulation of epigenetic CVD mechanisms through administration epigenetically active agents is one of such new approaches. Epigenetic mechanisms involve heritable changes in gene expression that are not linked to the alteration of DNA sequence. Pathogenesis of CVDs is associated with global genome-wide changes in DNA methylation and histone modifications. Epigenetically active compounds that influence activity of epigenetic modulators such as DNA methyltransferases (DNMTs), histone acetyltransferases, histone deacetylases (HDACs), etc. may correct these pathogenic changes in the epigenome and therefore be used for CVD therapy. To date, many epigenetically active natural substances (such as polyphenols and flavonoids) and synthetic compounds such as DNMT inhibitors or HDAC inhibitors are known. Both native and chemical DNMT and HDAC inhibitors possess a wide range of cytoprotective activities such as anti-inflammatory, antioxidant, anti-apoptotic, anti-anfibrotic, and anti-hypertrophic properties, which are beneficial of treatment of a variety of CVDs. However, so far, only synthetic DNMT inhibitors enter clinical trials while synthetic HDAC inhibitors are still under evaluation in preclinical studies. In this review, we consider epigenetic mechanisms such as DNA methylation and histone modifications in cardiovascular pathology and the epigenetics-based therapeutic approaches focused on the implementation of DNMT and HDAC inhibitors.

Anti-aging pharmacology: Promises and pitfalls

Life expectancy has grown dramatically in modern times. This increase, however, is not accompanied by the same increase in healthspan. Efforts to extend healthspan through pharmacological agents targeting aging-related pathological changes are now in the spotlight of geroscience, the main idea of which is that delaying of aging is far more effective than preventing the particular chronic disorders. Currently, anti-aging pharmacology is a rapidly developing discipline. It is a preventive field of health care, as opposed to conventional medicine which focuses on treating symptoms rather than root causes of illness. A number of pharmacological agents targeting basic aging pathways (i.e., calorie restriction mimetics, autophagy inducers, senolytics etc.) are now under investigation. This review summarizes the literature related to advances, perspectives and challenges in the field of anti-aging pharmacology.

SIRT1-PGC1α-NFκB Pathway of Oxidative and Inflammatory Stress during Trypanosoma cruzi Infection: Benefits of SIRT1-Targeted Therapy in Improving Heart Function in Chagas Disease

Chronic chagasic cardiomyopathy (CCM) is presented by increased oxidative/inflammatory stress and decreased mitochondrial bioenergetics. SIRT1 senses the redox changes and integrates mitochondrial metabolism and inflammation; and SIRT1 deficiency may be a major determinant in CCM. To test this, C57BL/6 mice were infected with Trypanosoma cruzi (Tc), treated with SIRT1 agonists (resveratrol or SRT1720), and monitored during chronic phase (~150 days post-infection). Resveratrol treatment was partially beneficial in controlling the pathologic processes in Chagas disease. The 3-weeks SRT1720 therapy provided significant benefits in restoring the left ventricular (LV) function (stroke volume, cardiac output, ejection fraction etc.) in chagasic mice, though cardiac hypertrophy presented by increased thickness of the interventricular septum and LV posterior wall, increased LV mass, and disproportionate synthesis of collagens was not controlled. SRT1720 treatment preserved the myocardial SIRT1 activity and PGC1α deacetylation (active-form) that were decreased by 53% and 9-fold respectively, in chagasic mice. Yet, SIRT1/PGC1α-dependent mitochondrial biogenesis (i.e., mitochondrial DNA content, and expression of subunits of the respiratory complexes and mtDNA replication machinery) was not improved in chronically-infected/SRT1720-treated mice. Instead, SRT1720 therapy resulted in 2-10-fold inhibition of Tc-induced oxidative (H2O2 and advanced oxidation protein products), nitrosative (inducible nitric oxide synthase, 4-hydroxynonenal, 3-nitrotyrosine), and inflammatory (IFNγ, IL1β, IL6 and TNFα) stress and inflammatory infiltrate in chagasic myocardium. These benefits were delivered through SIRT1-dependent inhibition of NFκB transcriptional activity. We conclude that Tc inhibition of SIRT1/PGC1α activity was not a key mechanism in mitochondrial biogenesis defects during Chagas disease. SRT1720-dependent SIRT1 activation led to suppression of NFκB transcriptional activity, and subsequently, oxidative/nitrosative and inflammatory pathology were subdued, and antioxidant status and LV function were enhanced in chronic chagasic cardiomyopathy.

Interplay Between Inflammation and Epigenetic Changes in Cancer

Immune responses can suppress tumorigenesis, but also contribute to cancer initiation and progression suggesting a complex interaction between the immune system and cancer. Epigenetic alterations, which are heritable changes in gene expression without changes to the DNA sequence, also play a role in carcinogenesis through silencing expression of tumor suppressor genes and activating oncogenic signaling. Interestingly, epithelial cells at sites of chronic inflammation undergo DNA methylation alterations that are similar to those present in cancer cells, suggesting that inflammation may initiate cancer-specific epigenetic changes in epithelial cells. Furthermore, epigenetic changes occur during immune cell differentiation and participate in regulating the immune response, including the regulation of inflammatory cytokines. Cancer cells utilize epigenetic silencing of immune-related genes to evade the immune response. This chapter will detail the interactions between inflammation and epigenetics in tumor initiation, promotion, and immune evasion and how these connections are being leveraged in cancer prevention and treatment.