Mitochondrial Dysfunction in Aging and Cancer

Mitochondria-Selective Dicationic Small-Molecule Ligand Targeting G-Quadruplex Structures for Human Colorectal Cancer Therapy

Mitochondria are important drug targets for anticancer and other disease therapies. Certain human mitochondrial DNA sequences capable of forming G-quadruplex structures (G4s) are emerging drug targets of small molecules. Despite some mitochondria-selective ligands being reported for drug delivery against cancers, the ligand design is mostly limited to the triphenylphosphonium scaffold. The ligand designed with lipophilic small-sized scaffolds bearing multipositive charges targeting the unique feature of high mitochondrial membrane potential (MMP) is lacking and most mitochondria-selective ligands are not G4-targeting. Herein, we report a new small-sized dicationic lipophilic ligand to target MMP and mitochondrial DNA G4s to enhance drug delivery for anticancer. The ligand showed marked alteration of mitochondrial gene expression and substantial induction of ROS production, mitochondrial dysfunction, DNA damage, cellular senescence, and apoptosis. The ligand also exhibited high anticancer activity against HCT116 cancer cells (IC50, 3.4 μM) and high antitumor efficacy in the HCT116 tumor xenograft mouse model (∼70% tumor weight reduction).

Mendelian randomization combined with multi-omics explores the relationship between heart failure and cancer

Background: Whether there is an association between HF (HF) and cancer has not been conclusively established, and it is not clear whether patients with cancer can share similar hospitalization strategies and outcomes with patients with HF. Methods: Genome-wide association summary statistics were performed using a two-sample Mendelian randomization (MR) method for HF patients and cancer patients from the GWAS directory, with co-localization and Summary Data-Based Mendelian Randomization (SMR) analyses to identify HF-associated genes, and transcriptomic analyses to analyze the roles of these genes in the clinical diagnosis and targeted therapies of multiple cancer types. Results: Two-sample MR analysis showed that increased risk of HF was associated with decreased risk of cervical, brain, breast, colorectal, lung, and skin cancers, and co-localization combined with SMR analysis identified ABO and SURF1 as HF-associated genes, and transcriptomic analyses showed that ABO is a risk factor for HF and a protective factor against cancer, whereas SURF1 is a protective factor against HF and a protective factor against cancer. Conclusion: There was no causal relationship between heart failure and cancers (Cervical, brain, breast, colorectal, lung and skin cancers) risk factors, however there was a trend toward a negative causal relationship between heart failure and cancers (Cervical, brain, breast, colorectal, lung and skin cancers) occurrence.

Advancements in the study of synaptic plasticity and mitochondrial autophagy relationship

Synapses serve as the points of communication between neurons, consisting primarily of three components: the presynaptic membrane, synaptic cleft, and postsynaptic membrane. They transmit signals through the release and reception of neurotransmitters. Synaptic plasticity, the ability of synapses to undergo structural and functional changes, is influenced by proteins such as growth-associated proteins, synaptic vesicle proteins, postsynaptic density proteins, and neurotrophic growth factors. Furthermore, maintaining synaptic plasticity consumes more than half of the brain's energy, with a significant portion of this energy originating from ATP generated through mitochondrial energy metabolism. Consequently, the quantity, distribution, transport, and function of mitochondria impact the stability of brain energy metabolism, thereby participating in the regulation of fundamental processes in synaptic plasticity, including neuronal differentiation, neurite outgrowth, synapse formation, and neurotransmitter release. This article provides a comprehensive overview of the proteins associated with presynaptic plasticity, postsynaptic plasticity, and common factors between the two, as well as the relationship between mitochondrial energy metabolism and synaptic plasticity.

Anti-aging Strategies and Topical Delivery of Biopolymer-based Nanocarriers for Skin Cancer Treatment

Environmental factors like UV radiation and epigenetic changes are significant factors for skin cancer that trigger early aging. This review provides essential information on cancer development concerning aging, the receptors involved, and the therapeutic targets. Biopolymers like polysaccharide, polyphenols, proteins, and nucleic acid plays a vital role in the regulation of normal cell homeostasis. Therefore, it is pertinent to explore the role of biopolymers as antiaging formulations and the possibility of these formulations being used against cancer via topical administrations. As UV radiation is one of the predominant factors in causing skin cancer, the association of receptors between aging and cancer indicated that insulin receptor, melatonin receptor, toll-like receptor, SIRT 1 receptor, tumor-specific T cell receptor and mitochondria-based targeting could be used to direct therapeutics for suppression of cancer and prevent aging. Biopolymer-based nanoformulations have tremendously progressed by entrapment of drugs like curcumin and resveratrol which can prevent cancer and aging simultaneously. Certain protein signaling or calcium and ROS signaling pathways are different for cancer and aging. The involvement of mitochondrial DNA mutation along with telomere shortening with a change in cellular energetics leading to genomic instability in the aging process can also induce mitochondrial dysfunction and epigenetic alterations leading to skin cancer. Therefore, the use of biopolymers as a topical supplement during the aging process can result in the prevention of cancer.

Mitochondrial Dysfunction in the Pathogenesis and Treatment of Oral Inflammatory Diseases

Oral inflammatory diseases (OIDs) include many common diseases such as periodontitis and pulpitis. The causes of OIDs consist microorganism, trauma, occlusal factors, autoimmune dis-eases and radiation therapy. When treated unproperly, such diseases not only affect oral health but also pose threat to people's overall health condition. Therefore, identifying OIDs at an early stage and exploring new therapeutic strategies are important tasks for oral-related research. Mitochondria are crucial organelles for many cellular activities and disruptions of mitochondrial function not only affect cellular metabolism but also indirectly influence people's health and life span. Mitochondrial dysfunction has been implicated in many common polygenic diseases, including cardiovascular and neurodegenerative diseases. Recently, increasing evidence suggests that mitochondrial dysfunction plays a critical role in the development and progression of OIDs and its associated systemic diseases. In this review, we elucidated the critical insights into mitochondrial dysfunction and its involvement in the inflammatory responses in OIDs. We also summarized recent research progresses on the treatment of OIDs targeting mitochondrial dysfunction and discussed the underlying mechanisms.

Knockdown of NR3C1 inhibits the proliferation and migration of clear cell renal cell carcinoma through activating endoplasmic reticulum stress-mitophagy

BACKGROUND

Clear cell renal cell carcinoma (ccRCC) is closely associated with steroid hormones and their receptors affected by lipid metabolism. Recently, there has been growing interest in the carcinogenic role of NR3C1, the sole gene responsible for encoding glucocorticoid receptor. However, the specific role of NR3C1 in ccRCC remains unclear. The present study was thus developed to explore the underlying mechanism of NR3C1's carcinogenic effects in ccRCC.

METHODS

Expression of NR3C1 was verified by various tumor databases and assessed using RT-qPCR and western blot. Stable transfected cell lines of ccRCC with NR3C1 knockdown were constructed, and a range of in vitro and in vivo experiments were performed to examine the effects of NR3C1 on ccRCC proliferation and migration. Transcriptomics and lipidomics sequencing were then conducted on ACHN cells, which were divided into control and sh-NR3C1 group. Finally, the sequencing results were validated using transmission electron microscopy, mitochondrial membrane potential assay, immunofluorescence co-localization, cell immunofluorescent staining, and Western blot. The rescue experiments were designed to investigate the relationship between endoplasmic reticulum stress (ER stress) and mitophagy in ccRCC cells after NR3C1 knockdown, as well as the regulation of their intrinsic signaling pathways.

RESULTS

The expression of NR3C1 in ccRCC cells and tissues was significantly elevated. The sh-NR3C1 group, which had lower levels of NR3C1, exhibited a lower proliferation and migration capacity of ccRCC than that of the control group (P < 0.05). Then, lipidomic and transcriptomic sequencing showed that lipid metabolism disorders, ER stress, and mitophagy genes were enriched in the sh-NR3C1 group. Finally, compared to the control group, ER stress and mitophagy were observed in the sh-NR3C1 group, while the expression of ATF6, CHOP, PINK1, and BNIP3 was also up-regulated (P < 0.05). Furthermore, Ceapin-A7, an inhibitor of ATF6, significantly down-regulated the expression of PINK1 and BNIP3 (P < 0.05), and significantly increased the proliferation and migration of ccRCC cells (P < 0.05).

CONCLUSIONS

This study confirms that knockdown of NR3C1 activates ER stress and induces mitophagy through the ATF6-PINK1/BNIP3 pathway, resulting in reduced proliferation and migration of ccRCC. These findings indicate potential novel targets for clinical treatment of ccRCC.

In Response to Precision Medicine: Current Subcellular Targeting Strategies for Cancer Therapy

Emerging as a potent anticancer treatment, subcellular targeted cancer therapy has drawn increasing attention, bringing great opportunities for clinical application. Here, two targeting strategies for four main subcellular organelles (mitochondria, lysosome, endoplasmic reticulum, and nucleus), including molecule- and nanomaterial (inorganic nanoparticles, micelles, organic polymers, and others)-based targeted delivery or therapeutic strategies, are summarized. Phototherapy, chemotherapy, radiotherapy, immunotherapy, and "all-in-one" combination therapy are among the strategies covered in detail. Such materials are constructed based on the specific properties and relevant mechanisms of organelles, enabling the elimination of tumors by inducing dysfunction in the corresponding organelles or destroying specific structures. The challenges faced by organelle-targeting cancer therapies are also summarized. Looking forward, a paradigm for organelle-targeting therapy with enhanced therapeutic efficacy compared to current clinical approaches is envisioned.

Methods to Evaluate Changes in Mitochondrial Structure and Function in Cancer

Mitochondria are regulators of key cellular processes, including energy production and redox homeostasis. Mitochondrial dysfunction is associated with various human diseases, including cancer. Importantly, both structural and functional changes can alter mitochondrial function. Morphologic and quantifiable changes in mitochondria can affect their function and contribute to disease. Structural mitochondrial changes include alterations in cristae morphology, mitochondrial DNA integrity and quantity, and dynamics, such as fission and fusion. Functional parameters related to mitochondrial biology include the production of reactive oxygen species, bioenergetic capacity, calcium retention, and membrane potential. Although these parameters can occur independently of one another, changes in mitochondrial structure and function are often interrelated. Thus, evaluating changes in both mitochondrial structure and function is crucial to understanding the molecular events involved in disease onset and progression. This review focuses on the relationship between alterations in mitochondrial structure and function and cancer, with a particular emphasis on gynecologic malignancies. Selecting methods with tractable parameters may be critical to identifying and targeting mitochondria-related therapeutic options. Methods to measure changes in mitochondrial structure and function, with the associated benefits and limitations, are summarized.

Mitochondrial Bioenergy in Neurodegenerative Disease: Huntington and Parkinson

Strong evidence suggests a correlation between degeneration and mitochondrial deficiency. Typical cases of degeneration can be observed in physiological phenomena (i.e., ageing) as well as in neurological neurodegenerative diseases and cancer. All these pathologies have the dyshomeostasis of mitochondrial bioenergy as a common denominator. Neurodegenerative diseases show bioenergetic imbalances in their pathogenesis or progression. Huntington's chorea and Parkinson's disease are both neurodegenerative diseases, but while Huntington's disease is genetic and progressive with early manifestation and severe penetrance, Parkinson's disease is a pathology with multifactorial aspects. Indeed, there are different types of Parkinson/Parkinsonism. Many forms are early-onset diseases linked to gene mutations, while others could be idiopathic, appear in young adults, or be post-injury senescence conditions. Although Huntington's is defined as a hyperkinetic disorder, Parkinson's is a hypokinetic disorder. However, they both share a lot of similarities, such as neuronal excitability, the loss of striatal function, psychiatric comorbidity, etc. In this review, we will describe the start and development of both diseases in relation to mitochondrial dysfunction. These dysfunctions act on energy metabolism and reduce the vitality of neurons in many different brain areas.

Oxidative Stress, Inflammation and Colorectal Cancer: An Overview

Colorectal cancer (CRC) represents the second leading cause of cancer-related deaths worldwide. The pathogenesis of CRC is a complex multistep process. Among other factors, inflammation and oxidative stress (OS) have been reported to be involved in the initiation and development of CRC. Although OS plays a vital part in the life of all organisms, its long-term effects on the human body may be involved in the development of different chronic diseases, including cancer diseases. Chronic OS can lead to the oxidation of biomolecules (nucleic acids, lipids and proteins) or the activation of inflammatory signaling pathways, resulting in the activation of several transcription factors or the dysregulation of gene and protein expression followed by tumor initiation or cancer cell survival. In addition, it is well known that chronic intestinal diseases such as inflammatory bowel disease (IBD) are associated with an increased risk of cancer, and a link between OS and IBD initiation and progression has been reported. This review focuses on the role of oxidative stress as a causative agent of inflammation in colorectal cancer.

Alpha-ketoglutarate as a potent regulator for lifespan and healthspan: Evidences and perspectives

Aging is a natural process that determined by a functional decline in cells and tissues as organisms are growing old, resulting in an increase at risk of disease and death. To this end, many efforts have been made to control aging and increase lifespan and healthspan. These efforts have led to the discovery of several anti-aging drugs and compounds such as rapamycin and metformin. Recently, alpha-ketoglutarate (AKG) has been introduced as a potential anti-aging metabolite that can control several functions in organisms, thereby increases longevity and improves healthspan. Unlike other synthetic anti-aging drugs, AKG is one of the metabolites of the tricarboxylic acid (TCA) cycle, also known as the Krebs cycle, and synthesized in the body. It plays a crucial role in the cell energy metabolism, amino acid/protein synthesis, epigenetic regulation, stemness and differentiation, fertility and reproductive health, and cancer cell behaviors. AKG exerts its effects through different mechanisms such as inhibiting mTOR and ATP-synthase, modulating DNA and histone demethylation and reducing ROS formation. Herein, we summarize the recent findings of AKG-related lifespan and healthspan studies and discuss AKG associated cell and molecular mechanisms involved in increasing longevity, improving reproduction, and modulating stem cells and cancer cells behavior. We also discuss the promises and limitations of AKG for delaying aging and other potential applications.

Non-Coding RNA-Dependent Regulation of Mitochondrial Dynamics in Cancer Pathophysiology

Mitochondria are essential organelles which dynamically change their shape and number to adapt to various environmental signals in diverse physio-pathological contexts. Mitochondrial dynamics refers to the delicate balance between mitochondrial fission (or fragmentation) and fusion, that plays a pivotal role in maintaining mitochondrial homeostasis and quality control, impinging on other mitochondrial processes such as metabolism, apoptosis, mitophagy, and autophagy. In this review, we will discuss how dysregulated mitochondrial dynamics can affect different cancer hallmarks, significantly impacting tumor growth, survival, invasion, and chemoresistance. Special emphasis will be given to emerging non-coding RNA molecules targeting the main fusion/fission effectors, acting as novel relevant upstream regulators of the mitochondrial dynamics rheostat in a wide range of tumors.

Antioxidant Intervention to Improve Cognition in the Aging Brain: The Example of Hydroxytyrosol and Resveratrol

Both physiological and pathological aging processes induce brain alterations especially affecting the speed of processing, working memory, conceptual reasoning and executive functions. Many therapeutic approaches to reduce the impact of brain aging on cognitive functioning have been tested; unfortunately, there are no satisfactory results as a single therapy. As aging is partly contributed by free radical reactions, it has been proposed that exogenous antioxidants could have a positive impact on both aging and its associated manifestations. The aim of this report is to provide a summary and a subsequent review of the literature evidence on the role of antioxidants in preventing and improving cognition in the aging brain. Manipulation of endogenous cellular defense mechanisms through nutritional antioxidants or pharmacological compounds represents an innovative approach to therapeutic intervention in diseases causing brain tissue damage, such as neurodegeneration. Coherently with this notion, antioxidants, especially those derived from the Mediterranean diet such as hydroxytyrosol and resveratrol, seem to be able to delay and modulate the cognitive brain aging processes and decrease the occurrence of its effects on the brain. The potential preventive activity of antioxidants should be evaluated in long-term exposure clinical trials, using preparations with high bioavailability, able to bypass the blood-brain barrier limitation, and that are well standardized.

5-aminolevulinic acid and sodium ferrous citrate decreased cell viability of gastric cancer cells by enhanced ROS generation through improving COX activity

BACKGROUND

Mitochondrial dysfunctions are related to cancer development.. 5-aminolevulinic acid (ALA) is used for photodynamic therapy (PDT). In this PDT, protoporphyrin IX (PpIX), which is converted from ALA, can generate reactive oxygen species (ROS) that kill the cancer cell. ALA is also reported to promote cytochrome c oxidase (COX) activity, which can generate ROS itself. Therefore, this study focused on the effect of ALA during PDT. In addition, in the previous study, sodium ferrous citrate (SFC) is reported to increase COX activity. So, this study also aims to improve the COX activity by the addition of SFC that can promote ROS generation, which has a cytotoxic effect.

METHODS

In this study, we used ALA and SFC, then evaluated the effects of the treatment on the human gastric cancer cell line MKN45, including the induction of cell death.

RESULTS

This study showed that treatment with ALA and SFC increases intracellular heme and heme proteins. Moreover, COX activity was promoted, resulting in the production of intracellular reactive oxygen species (ROS), which eventually reduced the cell viability in human gastric cancer cell line MKN45.

CONCLUSION

Our study can detect ROS generation with ALA and SFC. Furthermore, we found this generation of ROS has a cytotoxic effect. Therefore, this phenomenon contributes to the effect of PDT.

Lamin A/C impairments cause mitochondrial dysfunction by attenuating PGC1α and the NAMPT-NAD+ pathway

Mutations in the lamin A/C gene (LMNA) cause laminopathies such as the premature aging Hutchinson Gilford progeria syndrome (HGPS) and altered lamin A/C levels are found in diverse malignancies. The underlying lamin-associated mechanisms remain poorly understood. Here we report that lamin A/C-null mouse embryo fibroblasts (Lmna-/- MEFs) and human progerin-expressing HGPS fibroblasts both display reduced NAD+ levels, unstable mitochondrial DNA and attenuated bioenergetics. This mitochondrial dysfunction is associated with reduced chromatin recruitment (Lmna-/- MEFs) or low levels (HGPS) of PGC1α, the key transcription factor for mitochondrial homeostasis. Lmna-/- MEFs showed reduced expression of the NAD+-biosynthesis enzyme NAMPT and attenuated activity of the NAD+-dependent deacetylase SIRT1. We find high PARylation in lamin A/C-aberrant cells, further decreasing the NAD+ pool and consistent with impaired DNA base excision repair in both cell models, a condition that fuels DNA damage-induced PARylation under oxidative stress. Further, ATAC-sequencing revealed a substantially altered chromatin landscape in Lmna-/- MEFs, including aberrantly reduced accessibility at the Nampt gene promoter. Thus, we identified a new role of lamin A/C as a key modulator of mitochondrial function through impairments of PGC1α and the NAMPT-NAD+ pathway, with broader implications for the aging process.

Coenzyme Q10 + alpha lipoic acid for chronic COVID syndrome

Chronic COVID syndrome is characterized by chronic fatigue, myalgia, depression and sleep disturbances, similar to chronic fatigue syndrome (CFS) and fibromyalgia syndrome. Implementations of mitochondrial nutrients (MNs) with diet are important for the clinical effects antioxidant. We examined if use of an association of coenzyme Q10 and alpha lipoic acid (Requpero®) could reduce chronic covid symptoms. The Requpero study is a prospective observational study in which 174 patients, who had developed chronic-covid syndrome, were divided in two groups: The first one (116 patients) received coenzyme Q10 + alpha lipoic acid, and the second one (58 patients) did not receive any treatment. Primary outcome was reduction in Fatigue Severity Scale (FSS) in treatment group compared with control group. complete FSS response was reached most frequently in treatment group than in control group. A FSS complete response was reached in 62 (53.5%) patients in treatment group and in two (3.5%) patients in control group. A reduction in FSS core < 20% from baseline at T1 (non-response) was observed in 11 patients in the treatment group (9.5%) and in 15 patients in the control group (25.9%) (p < 0.0001). To date, this is the first study that tests the efficacy of coenzyme Q10 and alpha lipoic acid in chronic Covid syndrome. Primary and secondary outcomes were met. These results have to be confirmed through a double blind placebo controlled trial of longer duration.

Novel mitochondria-targeting compounds selectively kill human leukemia cells

Acute myeloid leukemia (AML) is a heterogeneous group of aggressive hematological malignancies commonly associated with treatment resistance, high risk of relapse, and mitochondrial dysregulation. We identified six mitochondria-affecting compounds (PS compounds) that exhibit selective cytotoxicity against AML cells in vitro. Structure-activity relationship studies identified six analogs from two original scaffolds that had over an order of magnitude difference between LD50 in AML and healthy peripheral blood mononuclear cells. Mechanistically, all hit compounds reduced ATP and selectively impaired both basal and ATP-linked oxygen consumption in leukemic cells. Compounds derived from PS127 significantly upregulated production of reactive oxygen species (ROS) in AML cells and triggered ferroptotic, necroptotic, and/or apoptotic cell death in AML cell lines and refractory/relapsed AML primary samples. These compounds exhibited synergy with several anti-leukemia agents in AML, acute lymphoblastic leukemia (ALL), or chronic myelogenous leukemia (CML). Pilot in vivo efficacy studies indicate anti-leukemic efficacy in a MOLM14/GFP/LUC xenograft model, including extended survival in mice injected with leukemic cells pre-treated with PS127B or PS127E and in mice treated with PS127E at a dose of 5 mg/kg. These compounds are promising leads for development of future combinatorial therapeutic approaches for mitochondria-driven hematologic malignancies such as AML, ALL, and CML.

The mitochondrial unfolded protein response (UPRmt): shielding against toxicity to mitochondria in cancer

Mitochondria are essential for tumor growth and progression. However, the heavy demand for mitochondrial activity in cancer leads to increased production of mitochondrial reactive oxygen species (mtROS), accumulation of mutations in mitochondrial DNA, and development of mitochondrial dysfunction. If left unchecked, excessive mtROS can damage and unfold proteins in the mitochondria to an extent that becomes lethal to the tumor. Cellular systems have evolved to combat mtROS and alleviate mitochondrial stress through a quality control mechanism called the mitochondrial unfolded protein response (UPR^mt). The UPR^mt system is composed of chaperones and proteases, which promote protein folding or eliminate mitochondrial proteins damaged by mtROS, respectively. UPR^mt is conserved and activated in cancer in response to mitochondrial stress to maintain mitochondrial integrity and support tumor growth. In this review, we discuss how mitochondria become dysfunctional in cancer and highlight the tumor-promoting functions of key components of the UPR^mt.

The Atomically Precise Gold/Captopril Nanocluster Au25(Capt)18 Gains Anticancer Activity by Inhibiting Mitochondrial Oxidative Phosphorylation

Atomically precise gold nanoclusters (AuNCs) are an emerging class of quantum-sized nanomaterials with well-defined molecular structures and unique biophysical properties, rendering them highly attractive for biological applications. We set out to study the impact of different ligand shells of atomically similar nanoclusters on cellular recognition and response. To understand the effects of atomically precise nanoclusters with identical composition on cells, we selected two different water-soluble gold nanoclusters protected with captopril (Capt) and glutathione (GSH): Au₂₅(Capt)₁₈ (CNC) and Au₂₅(GSH)₁₈ (GNC), respectively. We demonstrated that a change of the ligand of the cluster completely changes its biological functions. Whereas both nanoclusters are capable of internalization, only CNC exhibits remarkable cytotoxicity, more specifically on cancer cells. CNC shows enhanced cytotoxicity by inhibiting the OXPHOS of mitochondria, possibly by inhibiting the ATP synthase complex of the electron transport chain (ETC), and by initiating the leakage of electrons into the mitochondrial lumen. The resulting increase in both mitochondrial and total cellular ROS triggers cell death indicated by the appearance of cellular markers of apoptosis. Remarkably, this effect of nanoclusters is independent of any external light source excitation. Our findings point to the prevailing importance of the ligand shell for applications of atomically precise nanoclusters in biology and medicine.

Aryl hydrocarbon receptor blocks aging-induced senescence in the liver and fibroblast cells

Aging impairs organismal homeostasis leading to multiple pathologies. Yet, the mechanisms and molecular intermediates involved are largely unknown. Here, we report that aged aryl hydrocarbon receptor-null mice (AhR-/-) had exacerbated cellular senescence and more liver progenitor cells. Senescence-associated markers β-galactosidase (SA-β-Gal), p16^Ink4a and p21^Cip1 and genes encoding senescence-associated secretory phenotype (SASP) factors TNF and IL1 were overexpressed in aged AhR-/- livers. Chromatin immunoprecipitation showed that AhR binding to those gene promoters repressed their expression, thus adjusting physiological levels in AhR+/+ livers. MCP-2, MMP12 and FGF secreted by senescent cells were overproduced in aged AhR-null livers. Supporting the relationship between senescence and stemness, liver progenitor cells were overrepresented in AhR-/- mice, probably contributing to increased hepatocarcinoma burden. These AhR roles are not liver-specific since adult and embryonic AhR-null fibroblasts underwent senescence in culture, overexpressing SA-β-Gal, p16^Ink4a and p21^Cip1. Notably, depletion of senescent cells with the senolytic agent navitoclax restored expression of senescent markers in AhR-/- fibroblasts, whereas senescence induction by palbociclib induced an AhR-null-like phenotype in AhR+/+ fibroblasts. AhR levels were downregulated by senescence in mouse lungs but restored upon depletion of p16^Ink4a-expressing senescent cells. Thus, AhR restricts age-induced senescence associated to a differentiated phenotype eventually inducing resistance to liver tumorigenesis.

Oxidative distress in aging and age-related diseases: Spatiotemporal dysregulation of protein oxidation and degradation

The concept of oxidative distress had arisen from the assessment of cellular response to high concentrations of reactive species that result from an imbalance between oxidants and antioxidants and cause biomolecular damage. The intracellular distribution and flux of reactive species dramatically change in time and space contributing to the remodeling of the redox landscape and sensitivity of protein residues to oxidants. Here, we hypothesize that compromised spatiotemporal control of generation, conversions, and removal of reactive species underlies protein damage and dysfunction of protein degradation machineries. This leads to the accumulation of oxidatively damaged proteins resulted in an age-dependent decline in the organismal adaptability to oxidative stress. We highlight recent data obtained with the use of various cell cultures, animal models, and patients on irreversible and non-repairable oxidation of key redox-sensitive residues. Multiple reaction products include peptidyl hydroperoxides, alcohols, carbonyls, and carbamoyl moieties as well as Tyr-Tyr, Trp-Tyr, Trp-Trp, Tyr-Cys, His-Lys, His-Arg, and Tyr-Lys cross-links. These lead to protein fragmentation, misfolding, covalent cross-linking, oligomerization, aggregation, and ultimately, causing impaired protein function and turnover. 20S proteasome and autophagy-lysosome pathways are two major types of machinery for the degradation and elimination of oxidatively damaged proteins. Spatiotemporal dysregulation of these pathways under oxidative distress conditions is implicated in aging and age-related disorders such as neurodegenerative and cardiovascular diseases and diabetes. Future investigations in this field allow the discovery of new drugs to target components of dysregulated cell signaling and protein degradation machinery to combat aging and age-related chronic diseases.

Biomedical applications of metal oxide nanoparticles in aging and age-associated diseases

Metal oxide nanoparticles are known to exhibit unique properties such as catalyzing the neutralization of superoxide anions, hydroxyl radicals, hydrogen peroxides and behave as antioxidant enzymes. Oxidative stress, damage and chronic inflammation are major causes and consequences of aging and age-associated disorders. With the increasing popularity of metal oxide nanoparticles, they have been applied in various age-related pathologies using their antioxidant property. Metal oxide nanoparticles have been used as diagnostic, therapeutic, and as theranostics. This review summarizes the applications of metal oxide nanoparticles in aging and age-associated disorders such as cardiovascular diseases, diabetes, cancer, neurodegenerative disorders. Oxidative stress plays a central role in the activation of inflammatory pathways, disturbing the mitochondrial function, decreasing the telomere length and leading the cell towards senescence or death. Oxidative damage is the common pathway in the progression of aging and related diseases. Metal oxide nanoparticles scavenge or precisely detect the generated reactive oxygen species, hence applied in both diagnostics and therapeutics.

The Role of Mitochondrial Dysfunction in Vascular Disease, Tumorigenesis, and Diabetes

Mitochondrial dysfunction is known to be associated with a wide range of human pathologies, such as cancer, metabolic, and cardiovascular diseases. One of the possible ways of mitochondrial involvement in the cellular damage is excessive production of reactive oxygen and nitrogen species (ROS and RNS) that cannot be effectively neutralized by existing antioxidant systems. In mitochondria, ROS and RNS can contribute to protein and mitochondrial DNA (mtDNA) damage causing failure of enzymatic chains and mutations that can impair mitochondrial function. These processes further lead to abnormal cell signaling, premature cell senescence, initiation of inflammation, and apoptosis. Recent studies have identified numerous mtDNA mutations associated with different human pathologies. Some of them result in imbalanced oxidative phosphorylation, while others affect mitochondrial protein synthesis. In this review, we discuss the role of mtDNA mutations in cancer, diabetes, cardiovascular diseases, and atherosclerosis. We provide a list of currently described mtDNA mutations associated with each pathology and discuss the possible future perspective of the research.

CD4+ T-cell differentiation and function: Unifying glycolysis, fatty acid oxidation, polyamines NAD mitochondria

The progression through different steps of T-cell development, activation, and effector function is tightly bound to specific cellular metabolic processes. Previous studies established that T-effector cells have a metabolic bias toward aerobic glycolysis, whereas naive and regulatory T cells mainly rely on oxidative phosphorylation. More recently, the field of immunometabolism has drifted away from the notion that mitochondrial metabolism holds little importance in T-cell activation and function. Of note, T cells possess metabolic promiscuity, which allows them to adapt their nutritional requirements according to the tissue environment. Altogether, the integration of these metabolic pathways culminates in the generation of not only energy but also intermediates, which can regulate epigenetic programs, leading to changes in T-cell fate. In this review, we discuss the recent literature on how glycolysis, amino acid catabolism, and fatty acid oxidation work together with the tricarboxylic acid cycle in the mitochondrion. We also emphasize the importance of the electron transport chain for T-cell immunity. We also discuss novel findings highlighting the role of key enzymes, accessory pathways, and posttranslational protein modifications that distinctively regulate T-cell function and might represent prominent candidates for therapeutic purposes.

Mitochondrial dysfunction attenuates rapid regeneration in livers with toxin-induced fibrosis

BACKGROUND

The mechanism of associating liver partition and portal vein ligation for staged hepatectomy (ALPPS)-induced rapid liver regeneration remains poorly documented, especially in patients with fibrosis. Therefore, this study aims to investigate the underlying mechanism of ALPPS-induced accelerated regeneration in toxin-induced fibrosis models.

METHODS

The ALPPS-induced regeneration model was established in livers with thioacetamide (TAA)-induced fibrosis to determine the regenerative pathways involved in rapid regeneration. Confirmatory experiments were performed in transforming growth factor beta 1 (TGFβ1)-treated AML12 cells and mice with carbon tetrachloride (CCl4)-induced fibrosis. Finally, mitochondrial dysfunction was validated in fibrotic/non-fibrotic patients.

RESULTS

In TAA-induced fibrotic mice, ALPPS-induced regeneration was significantly inferior to that of the control group (P=0.027 at day 2 and P<0.001 at day 7). Furthermore, mitochondria-associated genes were significantly downregulated in TAA-challenged mice. Accordingly, the reduced production of ATP and elevated levels of malondialdehyde indicated disturbances in intracellular energy metabolism during the ALPPS-induced regenerative process after TAA treatment. Further investigations were performed in TGF-β1-treated AML12 cells and CCl4-treated mice, which indicated that mitochondrial dysfunction attenuated the capacity for rapid regeneration after ALPPS.

CONCLUSIONS

In summary, this study revealed that mitochondrial dysfunction led to inferior regeneration in livers with toxin-induced fibrosis and identified new therapeutic targets to improve the feasibility and safety of the ALPPS procedure. Further studies in human patients are required in the future.

Epigenetic Regulation of Mitochondrial Quality Control Genes in Multiple Myeloma: A Sequenom MassARRAY Pilot Investigation on HMCLs

The mitochondrial quality control network includes several epigenetically-regulated genes involved in mitochondrial dynamics, mitophagy, and mitochondrial biogenesis under physiologic conditions. Dysregulated expression of such genes has been reported in various disease contexts, including cancer. However, their expression pattern and the possible underlying epigenetic modifications remain to be defined within plasma cell (PC) dyscrasias. Herein, we compared the mRNA expression of mitochondrial quality control genes from multiple myeloma, plasma cell leukemia patients and human myeloma cell lines (HMCLs) with healthy plasma cells; moreover, by applying the Sequenom MassARRAY EpiTYPER technology, we performed a pilot investigation of their CpG methylation status in HMCLs. Overall, the results provided indicate dysregulated expression of several mitochondrial network’s genes, and alteration of the CpG methylation profile, underscoring novel potential myeloma biomarkers deserving in-depth functional investigation in the future.

Disturbance of Mitochondrial Dynamics and Mitochondrial Therapies in Atherosclerosis

Mitochondrial dysfunction is associated with a wide range of chronic human disorders, including atherosclerosis and diabetes mellitus. Mitochondria are dynamic organelles that undergo constant turnover in living cells. Through the processes of mitochondrial fission and fusion, a functional population of mitochondria is maintained, that responds to the energy needs of the cell. Damaged or excessive mitochondria are degraded by mitophagy, a specialized type of autophagy. These processes are orchestrated by a number of proteins and genes, and are tightly regulated. When one or several of these processes are affected, it can lead to the accumulation of dysfunctional mitochondria, deficient energy production, increased oxidative stress and cell death—features that are described in many human disorders. While severe mitochondrial dysfunction is known to cause specific and mitochondrial disorders in humans, progressing damage of the mitochondria is also observed in a wide range of other chronic diseases, including cancer and atherosclerosis, and appears to play an important role in disease development. Therefore, correction of mitochondrial dynamics can help in developing new therapies for the treatment of these conditions. In this review, we summarize the recent knowledge on the processes of mitochondrial turnover and the proteins and genes involved in it. We provide a list of known mutations that affect mitochondrial function, and discuss the emerging therapeutic approaches.

Novel selective hexokinase 2 inhibitor Benitrobenrazide blocks cancer cells growth by targeting glycolysis

Accelerated glucose metabolism is a common feature of cancer cells. Hexokinase 2 (HK2) as the rate-limiting enzyme catalyzes the first step of glucose metabolism. It is overexpressed in most of the human cancers and has been a promising target for cancer therapy. Here, we report a novel selective HK2 inhibitor Benitrobenrazide (BNBZ), with nanomolar inhibitory potency. In vitro, BNBZ directly binds to HK2, induces apoptosis, and inhibits proliferation of HK2-overexpressed cancer cells. BNBZ also significantly inhibits the glycolysis of SW1990 cells by targeting HK2. The knockdown or knockout of HK2 expression in SW1990 cells can reduce their sensitivity to BNBZ. Additionally, oral administration of BNBZ can effectively inhibit tumor growth in SW1990 and SW480 xenograft models. In general, BNBZ significantly inhibited glycolysis and cancer cell proliferation in vitro and in vivo by directly targeting HK2 with high potency and low toxicity, and can be developed as a novel HK2 small-molecule candidate drug for future cancer therapeutics.

Age-related mitochondrial dysfunction as a key factor in COVID-19 disease

SARS-CoV-2 causes a severe pneumonia (COVID-19) that affects essentially elderly people. In COVID-19, macrophage infiltration into the lung causes a rapid and intense cytokine storm leading finally to a multi-organ failure and death. Comorbidities such as metabolic syndrome, obesity, type 2 diabetes, lung and cardiovascular diseases, all of them age-associated diseases, increase the severity and lethality of COVID-19. Mitochondrial dysfunction is one of the hallmarks of aging and COVID-19 risk factors. Dysfunctional mitochondria is associated with defective immunological response to viral infections and chronic inflammation. This review discuss how mitochondrial dysfunction is associated with defective immune response in aging and different age-related diseases, and with many of the comorbidities associated with poor prognosis in the progression of COVID-19. We suggest here that chronic inflammation caused by mitochondrial dysfunction is responsible of the explosive release of inflammatory cytokines causing severe pneumonia, multi-organ failure and finally death in COVID-19 patients. Preventive treatments based on therapies improving mitochondrial turnover, dynamics and activity would be essential to protect against COVID-19 severity.

TERT-Regulation and Roles in Cancer Formation

Telomerase reverse transcriptase (TERT) is a catalytic subunit of telomerase. Telomerase complex plays a key role in cancer formation by telomere dependent or independent mechanisms. Telomere maintenance mechanisms include complex TERT changes such as gene amplifications, TERT structural variants, TERT promoter germline and somatic mutations, TERT epigenetic changes, and alternative lengthening of telomere. All of them are cancer specific at tissue histotype and at single cell level. TERT expression is regulated in tumors via multiple genetic and epigenetic alterations which affect telomerase activity. Telomerase activity via TERT expression has an impact on telomere length and can be a useful marker in diagnosis and prognosis of various cancers and a new therapy approach. In this review we want to highlight the main roles of TERT in different mechanisms of cancer development and regulation.

Drosophila Caliban preserves intestinal homeostasis and lifespan through regulating mitochondrial dynamics and redox state in enterocytes

Precise regulation of stem cell activity is crucial for tissue homeostasis. In Drosophila, intestinal stem cells (ISCs) maintain the midgut epithelium and respond to oxidative challenges. However, the connection between intestinal homeostasis and redox signaling remains obscure. Here we find that Caliban (Clbn) functions as a regulator of mitochondrial dynamics in enterocytes (ECs) and is required for intestinal homeostasis. The clbn knock-out flies have a shortened lifespan and lose the intestinal homeostasis. Clbn is highly expressed and localizes to the outer membrane of mitochondria in ECs. Mechanically, Clbn mediates mitochondrial dynamics in ECs and removal of clbn leads to mitochondrial fragmentation, accumulation of reactive oxygen species, ECs damage, activation of JNK and JAK-STAT signaling pathways. Moreover, multiple mitochondria-related genes are differentially expressed between wild-type and clbn mutated flies by a whole-genome transcriptional profiling. Furthermore, loss of clbn promotes tumor growth in gut generated by activated Ras in intestinal progenitor cells. Our findings reveal an EC-specific function of Clbn in regulating mitochondrial dynamics, and provide new insight into the functional link among mitochondrial redox modulation, tissue homeostasis and longevity.

Monoamine Oxidase A is a Major Mediator of Mitochondrial Homeostasis and Glycolysis in Gastric Cancer Progression

Objective

Monoamine oxidase A (MAO-A) is a mitochondrial protein involved in tumourigenesis in different types of cancer. However, the biological function of MAO-A in gastric cancer development remains unknown.

Methods

We examined MAO-A expression in gastric cancer tissues and in gastric cancer cell lines by immunohistochemistry and Western blot analyses. CCK8, FACS and bromodeoxyuridine incorporation assays were performed to assess the effects of MAO-A on gastric cancer cell proliferation. The role of MAO-A in mitochondrial function was determined through MitoSOX Red staining, ATP generation and glycolysis assays.

Results

In the present study, we observed that MAO-A was significantly upregulated in gastric cancer tissues and in AGS and MGC803 cells. The observed MAO-A inhibition indicated decreased cell cycle progression and proliferation. Silencing MAO-A expression was associated with suppressed migration and invasion of gastric cancer cells in vitro. Moreover, alleviated mitochondrial damage in these cells was demonstrated by decreased levels of mitochondrial reactive oxygen species and increased ATP generation. MAO-A knockdown also regulated the expression of the glycolysis rate-limiting enzymes hexokinase 2 and pyruvate dehydrogenase. Finally, we observed that the glycolysis-mediated effect was weakened in AGS and MGC803 cells when MAO-A was blocked.

Conclusion

The findings of the present study indicate that MAO-A is responsible for mitochondrial dysfunction and aerobic glycolysis, which in turn leads to the proliferation and metastasis of human gastric tumour cells.

Mitochondrial F-type ATP synthase: multiple enzyme functions revealed by the membrane-embedded FO structure

Of the two main sectors of the F-type ATP synthase, the membrane-intrinsic F_O domain is the one which, during evolution, has undergone the highest structural variations and changes in subunit composition. The F_O complexity in mitochondria is apparently related to additional enzyme functions that lack in bacterial and thylakoid complexes. Indeed, the F-type ATP synthase has the main bioenergetic role to synthesize ATP by exploiting the electrochemical gradient built by respiratory complexes. The F_O membrane domain, essential in the enzyme machinery, also participates in the bioenergetic cost of synthesizing ATP and in the formation of the cristae, thus contributing to mitochondrial morphology. The recent enzyme involvement in a high-conductance channel, which forms in the inner mitochondrial membrane and promotes the mitochondrial permeability transition, highlights a new F-type ATP synthase role. Point mutations which cause amino acid substitutions in F_O subunits produce mitochondrial dysfunctions and lead to severe pathologies. The F_O variability in different species, pointed out by cryo-EM analysis, mirrors the multiple enzyme functions and opens a new scenario in mitochondrial biology.

Mitochondria at the Crossroads of Physiology and Pathology

Mitochondria play a crucial role in cell life and death by regulating bioenergetic and biosynthetic pathways. They are able to adapt rapidly to different microenvironmental stressors by accommodating the metabolic and biosynthetic needs of the cell. Mounting evidence places mitochondrial dysfunction at the core of several diseases, notably in the context of pathologies of the cardiovascular and central nervous system. In addition, mutations in some mitochondrial proteins are bona fide cancer drivers. Better understanding of the functions of these multifaceted organelles and their components may finetune our knowledge on the molecular bases of certain diseases and suggest new therapeutic avenues.

Genome-Protecting Compounds as Potential Geroprotectors

Throughout life, organisms are exposed to various exogenous and endogenous factors that cause DNA damages and somatic mutations provoking genomic instability. At a young age, compensatory mechanisms of genome protection are activated to prevent phenotypic and functional changes. However, the increasing stress and age-related deterioration in the functioning of these mechanisms result in damage accumulation, overcoming the functional threshold. This leads to aging and the development of age-related diseases. There are several ways to counteract these changes: 1) prevention of DNA damage through stimulation of antioxidant and detoxification systems, as well as transition metal chelation; 2) regulation of DNA methylation, chromatin structure, non-coding RNA activity and prevention of nuclear architecture alterations; 3) improving DNA damage response and repair; 4) selective removal of damaged non-functional and senescent cells. In the article, we have reviewed data about the effects of various trace elements, vitamins, polyphenols, terpenes, and other phytochemicals, as well as a number of synthetic pharmacological substances in these ways. Most of the compounds demonstrate the geroprotective potential and increase the lifespan in model organisms. However, their genome-protecting effects are non-selective and often are conditioned by hormesis. Consequently, the development of selective drugs targeting genome protection is an advanced direction.

The Role of Growth Differentiation Factor 15 in Energy Metabolism

Growth differentiation factor 15 (GDF15) is receiving great interest beyond its role as an aging and disease-related biomarker. Recent discovery of its receptor, glial cell line-derived neurotrophic factor (GDNF) family receptor α-like (GFRAL), suggests a central role in appetite regulation. However, there is also considerable evidence that GDF15 may have peripheral activity through an as-of-yet undiscovered mode of action. This raises the question as to whether increased GDF15 induction during pathophysiologic conditions also suppresses appetite. The present review will briefly introduce the discovery of GDF15 and describe the different contexts under which GDF15 is induced, focusing on its induction during mitochondrial dysfunction. We will further discuss the metabolic role of GDF15 under various pathophysiological conditions and conclude with possible therapeutic applications.

Olfactory cell cultures to investigate health effects of air pollution exposure: Implications for neurodegeneration

Air pollution is a major, global public health concern. A growing body of evidence shows that exposure to air pollutants may impair the brain. Living in highly polluted areas has been linked to several neurodegenerative diseases, where exposure to complex mixtures of air pollutants in urban environments may have harmful effects on brain function. These harmful effects are thought to originate from elevated inflammation and oxidative stress. The olfactory epithelium is a key entry site of air pollutants into the brain as the particles are deposited in the upper airways and the nasal region. A potential source of patient-derived cells for study of air pollutant effects is the olfactory mucosa, which constitutes a central part of the olfactory epithelium. This review first summarizes the current literature on the available in vitro models of the olfactory epithelium. It then describes how alterations of the olfactory mucosa are linked to neurodegeneration and discusses potential therapeutic applications of these cells for neurodegenerative diseases. Finally, it reviews the research performed on the effects of air pollutant exposure in cells of the olfactory epithelium. Patient-derived olfactory epithelial models hold great promise for not only elucidating the molecular and cellular pathophysiology of neurodegenerative disorders, but for providing key understanding about air pollutant particle entry and effects at this key brain entry site.

Mitochondria-targeting monofunctional platinum(ii)–lonidamine conjugates for cancer cell de-energization

We report the rational design and anticancer mechanism studies of novel mitochondria-targeting monofunctional Pt(ii)–lonidamine conjugates for the selective de-energization of cancer cells.