The Tricky Connection between Extracellular Vesicles and Mitochondria in Inflammatory-Related Diseases.

Mitochondria are organelles present in almost all eukaryotic cells, where they represent the main site of energy production. Mitochondria are involved in several important cell processes, such as calcium homeostasis, OXPHOS, autophagy, and apoptosis. Moreover, they play a pivotal role also in inflammation through the inter-organelle and inter-cellular communications, mediated by the release of mitochondrial damage-associated molecular patterns (mtDAMPs). It is currently well-documented that in addition to traditional endocrine and paracrine communication, the cells converse via extracellular vesicles (EVs). These small membrane-bound particles are released from cells in the extracellular milieu under physio-pathological conditions. Importantly, EVs have gained much attention for their crucial role in inter-cellular communication, translating inflammatory signals into recipient cells. EVs cargo includes plasma membrane and endosomal proteins, but EVs also contain material from other cellular compartments, including mitochondria. Studies have shown that EVs may transport mitochondrial portions, proteins, and/or mtDAMPs to modulate the metabolic and inflammatory responses of recipient cells. Overall, the relationship between EVs and mitochondria in inflammation is an active area of research, although further studies are needed to fully understand the mechanisms involved and how they may be targeted for therapeutic purposes. Here, we have reported and discussed the latest studies focused on this fascinating and recent area of research, discussing of tricky connection between mitochondria and EVs in inflammatory-related diseases.

Interorganellar calcium signaling in the regulation of cell metabolism: A cancer perspective.

Organelles were originally considered to be individual cellular compartments with a defined organization and function. However, recent studies revealed that organelles deeply communicate within each other via Ca2+ exchange. This communication, mediated by specialized membrane regions in close apposition between two organelles, regulate cellular functions, including metabolism and cell fate decisions. Advances in microscopy techniques, molecular biology and biochemistry have increased our understanding of these interorganelle platforms. Research findings suggest that interorganellar Ca2+ signaling, which is altered in cancer, influences tumorigenesis and tumor progression by controlling cell death programs and metabolism. Here, we summarize the available data on the existence and composition of interorganelle platforms connecting the endoplasmic reticulum with mitochondria, the plasma membrane, or endolysosomes. Finally, we provide a timely overview of the potential function of interorganellar Ca2+ signaling in maintaining cellular homeostasis.

Calcium dysregulation in heart diseases: Targeting calcium channels to achieve a correct calcium homeostasis.

Intracellular calcium signaling is a universal language source shared by the most part of biological entities inside cells that, all together, give rise to physiological and functional anatomical units, the organ. Although preferentially recognized as signaling between cell life and death processes, in the heart it assumes additional relevance considered the importance of calcium cycling coupled to ATP consumption in excitation-contraction coupling. The concerted action of a plethora of exchangers, channels and pumps inward and outward calcium fluxes where needed, to convert energy and electric impulses in muscle contraction. All this without realizing it, thousands of times, every day. An improper function of those proteins (i.e., variation in expression, mutations onset, dysregulated channeling, differential protein-protein interactions) being part of this signaling network triggers a short circuit with severe acute and chronic pathological consequences reported as arrhythmias, cardiac remodeling, heart failure, reperfusion injury and cardiomyopathies. By acting with chemical, peptide-based and pharmacological modulators of these players, a correction of calcium homeostasis can be achieved accompanied by an amelioration of clinical symptoms. This review will focus on all those defects in calcium homeostasis which occur in the most common cardiac diseases, including myocardial infarction, arrhythmia, hypertrophy, heart failure and cardiomyopathies. This part will be introduced by the state of the art on the proteins involved in calcium homeostasis in cardiomyocytes and followed by the therapeutic treatments that to date, are able to target them and to revert the pathological phenotype.

Glyceryl Tristearate-Based Lipid Microparticles Loaded with the Tattoo Colorant, Acid Red 87: Colorant Retention Capacity in Excised Porcine Skin.

BACKGROUND: With the increasing diffusion of tattooing, the photolability of tattoo inks has become a critical issue, as available data indicated that several tattoo colorants are unstable under sunlight, generating potentially toxic photodegradation products. Therefore, it is desirable to enhance the photostability of coloring agents contained in tattoo inks. AIMS: Lipid microparticles (LMs) highly loaded with Acid Red 87 (C.I. 45380), a colorant used in tattoo inks, were evaluated for their effect on the colorant photoinstability. In addition, the capacity of the LMs to retain the incorporated C.I. 45380 colorant after their intradermal administration in excised porcine skin was investigated. METHODS: LMs loaded with C.I. 45380 were prepared using glyceryl tristearate as the lipidic material and phosphatidylcholine as the surfactant. Non-encapsulated C.I. 45380 or the colorant-loaded LMs were irradiated with a solar simulator for photodecomposition studies or introduced in the excised porcine skin mounted in Franz diffusion cells for stability evaluation in the dermal tissue. RESULTS AND CONCLUSION: The colorant content of the microparticles was 17.7%, and their size ranged from 25 to 170 µm. The light-induced degradation of C.I. 45380 was significantly decreased by its incorporation in the LMs from 20.2 ± 5.8% to 1.9 ± 2.1%. Moreover, after intradermal injection of free or microencapsulated C.I. 45380 in the excised pig skin, the LMs reduced by 93.7% (from 24.6 to 1.5%) the quantity of the colorant diffused and hence lost in the Franz cell receptor fluid. Hence, the LM carrier efficiently retained the entrapped C.I. 45380 following incubation in the dermal region of the isolated porcine skin, which is in favor of a long-lasting tattoo. Based on these data, the incorporation of C.I. 45380 in the LMs could represent a potentially useful strategy to reduce the photodecomposition of the tattoo colorant and its harmful interactions with the skin tissue.

PLCB3 Loss of Function Reduces Pseudomonas aeruginosa-Dependent IL-8 Release in Cystic Fibrosis.

The lungs of patients with cystic fibrosis (CF) are characterized by an exaggerated inflammation driven by secretion of IL-8 from bronchial epithelial cells and worsened by Pseudomonas aeruginosa infection. To identify novel antiinflammatory molecular targets, we previously performed a genetic study of 135 genes of the immune response, which identified the c.2534C>T (p.S845L) variant of phospholipase C-ß3 (PLCB3) as being significantly associated with mild progression of pulmonary disease. Silencing PLCB3 revealed that it potentiates the Toll-like receptor's inflammatory signaling cascade originating from CF bronchial epithelial cells. In the present study, we investigated the role of the PLCB3-S845L variant together with two synthetic mutants paradigmatic of impaired catalytic activity or lacking functional activation in CF bronchial epithelial cells. In experiments in which cells were exposed to P. aeruginosa, the supernatant of mucopurulent material from the airways of patients with CF or different agonists revealed that PLCB3-S845L has defects of 1) agonist-induced Ca2+ release from endoplasmic reticulum and rise of Ca2+ concentration, 2) activation of conventional protein kinase C isoform ß, and 3) induction of IL-8 release. These results, besides identifying S845L as a loss-of-function variant, strengthen the importance of targeting PLCB3 to mitigate the CF inflammatory response in bronchial epithelial cells without blunting the immune response.

Pharmaco-toxicological effects of the novel third-generation fluorinate synthetic cannabinoids, 5F-ADBINACA, AB-FUBINACA, and STS-135 in mice. In vitro and in vivo studies.

INTRODUCTION: 5F-ADBINACA, AB-FUBINACA, and STS-135 are 3 novel third-generation fluorinate synthetic cannabinoids that are illegally marketed as incense, herbal preparations, or research chemicals for their psychoactive cannabis-like effects. METHODS: The present study aims at investigating the in vitro and in vivo pharmacological activity of 5F-ADBINACA, AB-FUBINACA, and STS-135 in male CD-1 mice, comparing their in vivo effects with those caused by the administration of Δ9 -THC and JWH-018. In vitro competition binding experiments revealed a nanomolar affinity and potency of the 5F-ADBINACA, AB-FUBINACA, and STS-135 on mouse and human CB1 and CB2 receptors. Moreover, these synthetic cannabinoids induced neurotoxicity in murine neuro-2a cells. RESULTS: In vivo studies showed that 5F-ADBINACA, AB-FUBINACA, and STS-135 induced hypothermia; increased pain threshold to both noxious mechanical and thermal stimuli; caused catalepsy; reduced motor activity; impaired sensorimotor responses (visual, acoustic, and tactile); caused seizures, myoclonia, and hyperreflexia; and promoted aggressiveness in mice. Behavioral and neurological effects were fully prevented by the selective CB1 receptor antagonist/inverse agonist AM 251. Differently, the visual sensory response induced by STS-135 was only partly prevented by the AM 251, suggesting a CB1 -independent mechanism. CONCLUSIONS: For the first time, the present study demonstrates the pharmaco-toxicological effects induced by the administration of 5F-ADBINACA, AB-FUBINACA, and STS-135 in mice and suggests their possible detrimental effects on human health.

Endoplasmic Reticulum-Mitochondria Communication Through Ca2+ Signaling: The Importance of Mitochondria-Associated Membranes (MAMs).

The execution of proper Ca2+ signaling requires close apposition between the endoplasmic reticulum (ER) and mitochondria. Hence, Ca2+ released from the ER is "quasi-synaptically" transferred to mitochondrial matrix, where Ca2+ stimulates mitochondrial ATP synthesis by activating the tricarboxylic acid (TCA) cycle. However, when the Ca2+ transfer is excessive and sustained, mitochondrial Ca2+ overload induces apoptosis by opening the mitochondrial permeability transition pore. A large number of regulatory proteins reside at mitochondria-associated ER membranes (MAMs) to maintain the optimal distance between the organelles and to coordinate the functionality of both ER and mitochondrial Ca2+ transporters or channels. In this chapter, we discuss the different pathways involved in the regulation of ER-mitochondria Ca2+ flux and describe the activities of the various Ca2+ players based on their primary intra-organelle localization.

Transient Receptor Potential Ankyrin 1 Channels Modulate Inflammatory Response in Respiratory Cells from Patients with Cystic Fibrosis.

Pseudomonas aeruginosa colonization, prominent inflammation with massive expression of the neutrophil chemokine IL-8, and luminal infiltrates of neutrophils are hallmarks of chronic lung disease in patients with cystic fibrosis (CF). The nociceptive transient receptor potential ankyrin (TRPA) 1 calcium channels have been recently found to be involved in nonneurogenic inflammation. Here, we investigate the role of TRPA1 in CF respiratory inflammatory models in vitro. Expression of TRPA1 was evaluated in CF lung tissue sections and cells by immunohistochemistry and immunofluorescence. Epithelial cell lines (A549, IB3-1, CuFi-1, CFBE41o-) and primary cells from patients with CF were used to: (1) check TRPA1 function modulation, by Fura-2 calcium imaging; (2) down-modulate TRPA1 function and expression, by pharmacological inhibitors (HC-030031 and A-967079) and small interfering RNA silencing; and (3) assess the effect of TRPA1 down-modulation on expression and release of cytokines upon exposure to proinflammatory challenges, by quantitative RT-PCR and 27-protein Bioplex assay. TRPA1 channels are expressed in the CF pseudostratified columnar epithelium facing the bronchial lumina exposed to bacteria, where IL-8 is coexpressed. Inhibition of TRPA1 expression results in a relevant reduction of release of several cytokines, including IL-8 and the proinflammatory cytokines IL-1ß and TNF-α, in CF primary bronchial epithelial cells exposed to P. aeruginosa and to the supernatant of mucopurulent material derived from the chronically infected airways of patients with CF. In conclusion, TRPA1 channels are involved in regulating the extent of airway inflammation driven by CF bronchial epithelial cells.

A novel chimeric aequorin fused with caveolin-1 reveals a sphingosine kinase 1-regulated Ca²âº microdomain in the caveolar compartment.

Caveolae are plasma membrane invaginations enriched in sterols and sphingolipids. Sphingosine kinase 1 (SK1) is an oncogenic protein that converts sphingosine to sphingosine 1-phosphate (S1P), which is a messenger molecule involved in calcium signaling. Caveolae contain calcium responsive proteins, but the effects of SK1 or S1P on caveolar calcium signaling have not been investigated. We generated a Caveolin-1-Aequorin fusion protein (Cav1-Aeq) that can be employed for monitoring the local calcium concentration at the caveolae ([Ca²âº]cav). In HeLa cells, Cav1-Aeq reported different [Ca²âº] as compared to the plasma membrane [Ca²âº] in general (reported by SNAP25-Aeq) or as compared to the cytosolic [Ca²âº] (reported by cyt-Aeq). The Ca²âº signals detected by Cav1-Aeq were significantly attenuated when the caveolar structures were disrupted by methyl-ß-cyclodextrin, suggesting that the caveolae are specific targets for Ca²âº signaling. HeLa cells overexpressing SK1 showed increased [Ca²âº]cav during histamine-induced Ca²âº mobilization in the absence of extracellular Ca²âº as well as during receptor-operated Ca²âº entry (ROCE). The SK1-induced increase in [Ca²âº]cav during ROCE was reverted by S1P receptor antagonists. In accordance, pharmacologic inhibition of SK1 reduced the [Ca²âº]cav during ROCE. S1P treatment stimulated the [Ca²âº]cav upon ROCE. The Ca²âº responses at the plasma membrane in general were not affected by SK1 expression. In summary, our results show that SK1/S1P-signaling regulates Ca²âº signals at the caveolae. This article is part of a Special Issue entitled: 13th European Symposium on Calcium.

Phospholipase C-ß3 is a key modulator of IL-8 expression in cystic fibrosis bronchial epithelial cells.

Respiratory insufficiency is the major cause of morbidity and mortality in patients affected by cystic fibrosis (CF). An excessive neutrophilic inflammation, mainly orchestrated by the release of IL-8 from bronchial epithelial cells and amplified by chronic bacterial infection with Pseudomonas aeruginosa, leads to progressive tissue destruction. The anti-inflammatory drugs presently used in CF patients have several limitations, indicating the need for identifying novel molecular targets. To address this issue, we preliminarily studied the association of 721 single nucleotide polymorphisms from 135 genes potentially involved in signal transduction implicated in neutrophil recruitment in a cohort of F508del homozygous CF patients with either severe or mild progression of lung disease. The top ranking association was found for a nonsynonymous polymorphism of the phospholipase C-ß3 (PLCB3) gene. Studies in bronchial epithelial cells exposed to P. aeruginosa revealed that PLCB3 is implicated in extracellular nucleotide-dependent intracellular calcium signaling, leading to activation of the protein kinase Cα and Cß and of the nuclear transcription factor NF-κB p65. The proinflammatory pathway regulated by PLCB3 acts by potentiating the Toll-like Receptors' signaling cascade and represents an interesting molecular target to attenuate the excessive recruitment of neutrophils without completely abolishing the inflammatory response.

Control of mitochondrial functions by Pseudomonas aeruginosa in cystic fibrosis.

Cystic fibrosis (CF) is a genetic disease characterized by mutations of cystic fibrosis transmembrane conductance regulator (CFTR) gene, which lead to a dysfunctional chloride and bicarbonate channel. Abnormal mucus viscosity, persistent infections and hyperinflammation that preferentially affect the airways, referred to the pathogenesis of CF lung disease. It has largely demonstrated that Pseudomonas aeruginosa (P. aeruginosa) represents the most important pathogen that affect CF patients, leading to worsen inflammation by stimulating pro-inflammatory mediators release and tissue destruction. The conversion to mucoid phenotype and formation of biofilms, together with the increased frequency of mutations, are only few changes that characterize the P. aeruginosa's evolution during CF lung chronic infection. Recently, mitochondria received increasing attention due to their involvement in inflammatory-related diseases, including in CF. Alteration of mitochondrial homeostasis is sufficient to stimulate immune response. Exogenous or endogenous stimuli that perturb mitochondrial activity are used by cells, which, through the mitochondrial stress, potentiate immunity programs. Studies show the relationship between mitochondria and CF, supporting the idea that mitochondrial dysfunction endorses the exacerbation of inflammatory responses in CF lung. In particular, evidences suggest that mitochondria in CF airway cells are more susceptible to P. aeruginosa infection, with consequent detrimental effects that lead to amplify the inflammatory signals. This review discusses the evolution of P. aeruginosa in relationship with the pathogenesis of CF, a fundamental step to establish chronic infection in CF lung disease. Specifically, we focus on the role of P. aeruginosa in the exacerbation of inflammatory response, by triggering mitochondria in CF.

The NLRP3 Inflammasome in Neurodegenerative Disorders: Insights from Epileptic Models.

Neuroinflammation represents a dynamic process of defense and protection against the harmful action of infectious agents or other detrimental stimuli in the central nervous system (CNS). However, the uncontrolled regulation of this physiological process is strongly associated with serious dysfunctional neuronal issues linked to the progression of CNS disorders. Moreover, it has been widely demonstrated that neuroinflammation is linked to epilepsy, one of the most prevalent and serious brain disorders worldwide. Indeed, NLRP3, one of the most well-studied inflammasomes, is involved in the generation of epileptic seizures, events that characterize this pathological condition. In this context, several pieces of evidence have shown that the NLRP3 inflammasome plays a central role in the pathophysiology of mesial temporal lobe epilepsy (mTLE). Based on an extensive review of the literature on the role of NLRP3-dependent inflammation in epilepsy, in this review we discuss our current understanding of the connection between NLRP3 inflammasome activation and progressive neurodegeneration in epilepsy. The goal of the review is to cover as many of the various known epilepsy models as possible, providing a broad overview of the current literature. Lastly, we also propose some of the present therapeutic strategies targeting NLRP3, aiming to provide potential insights for future studies.

SARS-CoV-2 viral entry and replication is impaired in Cystic Fibrosis airways due to ACE2 downregulation.

As an inherited disorder characterized by severe pulmonary disease, cystic fibrosis could be considered a comorbidity for coronavirus disease 2019. Instead, current clinical evidence seems to be heading in the opposite direction. To clarify whether host factors expressed by the Cystic Fibrosis epithelia may influence coronavirus disease 2019 progression, here we describe the expression of SARS-CoV-2 receptors in primary airway epithelial cells. We show that angiotensin converting enzyme 2 (ACE2) expression and localization are regulated by Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) channel. Consistently, our results indicate that dysfunctional CFTR channels alter susceptibility to SARS-CoV-2 infection, resulting in reduced viral entry and replication in Cystic Fibrosis cells. Depending on the pattern of ACE2 expression, the SARS-CoV-2 spike (S) protein induced high levels of Interleukin 6 in healthy donor-derived primary airway epithelial cells, but a very weak response in primary Cystic Fibrosis cells. Collectively, these data support that Cystic Fibrosis condition may be at least partially protecting from SARS-CoV-2 infection.

ATP synthesis and storage.

Since 1929, when it was discovered that ATP is a substrate for muscle contraction, the knowledge about this purine nucleotide has been greatly expanded. Many aspects of cell metabolism revolve around ATP production and consumption. It is important to understand the concepts of glucose and oxygen consumption in aerobic and anaerobic life and to link bioenergetics with the vast amount of reactions occurring within cells. ATP is universally seen as the energy exchange factor that connects anabolism and catabolism but also fuels processes such as motile contraction, phosphorylations, and active transport. It is also a signalling molecule in the purinergic signalling mechanisms. In this review, we will discuss all the main mechanisms of ATP production linked to ADP phosphorylation as well the regulation of these mechanisms during stress conditions and in connection with calcium signalling events. Recent advances regarding ATP storage and its special significance for purinergic signalling will also be reviewed.

Mitochondria-associated membranes (MAMs) as hotspot Ca(2+) signaling units.

The tight interplay between endoplasmic reticulum (ER) and mitochondria is a key determinant of cell function and survival through the control of intracellular calcium (Ca(2+)) signaling. The specific sites of physical association between ER and mitochondria are known as mitochondria-associated membranes (MAMs). It has recently become clear that MAMs are crucial for highly efficient transmission of Ca(2+) from the ER to mitochondria, thus controlling fundamental processes involved in energy production and also determining cell fate by triggering or preventing apoptosis. In this contribution, we summarize the main features of the Ca(2+)-signaling toolkit, covering also the latest breakthroughs in the field, such as the identification of novel candidate proteins implicated in mitochondrial Ca(2+) transport and the recent direct characterization of the high-Ca(2+) microdomains between ER and mitochondria. We review the main functions of these two organelles, with special emphasis on Ca(2+) handling and on the structural and molecular foundations of the signaling contacts between them. Additionally, we provide important examples of the physiopathological role of this cross-talk, briefly describing the key role played by MAMs proteins in many diseases, and shedding light on the essential role of mitochondria-ER interactions in the maintenance of cellular homeostasis and the determination of cell fate.

Intramitochondrial calcium regulation by the FHIT gene product sensitizes to apoptosis.

Despite the growing interest in the Fhit tumor suppressor protein, frequently deleted in human cancers, the mechanism of its powerful proapoptotic activity has remained elusive. We here demonstrate that Fhit sensitizes the low-affinity Ca(2+) transporters of mitochondria, enhancing Ca(2+) uptake into the organelle both in intact and in permabilized cells, and potentiating the effect of apoptotic agents. This effect can be attributed to the fraction of Fhit sorted to mitochondria, as a fully mitochondrial Fhit (a chimeric protein including a mitochondrial targeting sequence) retains the Ca(2+) signaling properties of Fhit and the proapoptotic activity of the native protein (whereas the effects on the cell cycle are lost). Thus, the partial sorting of Fhit to mitochondria allows to finely tune the sensitivity of the organelle to the highly pleiomorphic Ca(2+) signals, synergizing with apoptotic challenges. This concept, and the identification of the molecular machinery, may provide ways to act on apoptotic cell death and its derangement in cancer.

Overview of CF lung pathophysiology.

Defects of the cystic fibrosis (CF) transmembrane conductance regulator (CFTR) protein affect the homeostasis of chloride, bicarbonate, sodium, and water in the airway surface liquid, influencing the mucus composition and viscosity, which induces a severe condition of infection and inflammation along the whole life of CF patients. The introduction of CFTR modulators, novel drugs directly intervening to rescue the function of CFTR protein, opens a new era of experimental research. The review summarizes the most recent advancements to understand the characteristics of the infective and inflammatory pathology of CF lungs.

The "mitochondrial stress responses": the "Dr. Jekyll and Mr. Hyde" of neuronal disorders.

Neuronal disorders are associated with a profound loss of mitochondrial functions caused by various stress conditions, such as oxidative and metabolic stress, protein folding or import defects, and mitochondrial DNA alteration. Cells engage in different coordinated responses to safeguard mitochondrial homeostasis. In this review, we will explore the contribution of mitochondrial stress responses that are activated by the organelle to perceive these dangerous conditions, keep them under control and rescue the physiological condition of nervous cells. In the sections to come, particular attention will be dedicated to analyzing how compensatory mitochondrial hyperfusion, mitophagy, mitochondrial unfolding protein response, and apoptosis impact human neuronal diseases. Finally, we will discuss the relevance of the new concept: the "mito-inflammation", a mitochondria-mediated inflammatory response that is recently found to cover a relevant role in the pathogenesis of diverse inflammatory-related diseases, including neuronal disorders.

The Multifaceted Roles of Autophagy in Infectious, Obstructive, and Malignant Airway Diseases.

Autophagy is a highly conserved dynamic process by which cells deliver their contents to lysosomes for degradation, thus ensuring cell homeostasis. In response to environmental stress, the induction of autophagy is crucial for cell survival. The dysregulation of this degradative process has been implicated in a wide range of pathologies, including lung diseases, representing a relevant potential target with significant clinical outcomes. During lung disease progression and infections, autophagy may exert both protective and harmful effects on cells. In this review, we will explore the implications of autophagy and its selective forms in several lung infections, such as SARS-CoV-2, Respiratory Syncytial Virus (RSV) and Mycobacterium tuberculosis (Mtb) infections, and different lung diseases such as Cystic Fibrosis (CF), Chronic Obstructive Pulmonary Disease (COPD), and Malignant Mesothelioma (MM).

Molecular Mechanisms of Autophagy in Cancer Development, Progression, and Therapy.

Autophagy is an evolutionarily conserved and tightly regulated process that plays an important role in maintaining cellular homeostasis. It involves regulation of various genes that function to degrade unnecessary or dysfunctional cellular components, and to recycle metabolic substrates. Autophagy is modulated by many factors, such as nutritional status, energy level, hypoxic conditions, endoplasmic reticulum stress, hormonal stimulation and drugs, and these factors can regulate autophagy both upstream and downstream of the pathway. In cancer, autophagy acts as a double-edged sword depending on the tissue type and stage of tumorigenesis. On the one hand, autophagy promotes tumor progression in advanced stages by stimulating tumor growth. On the other hand, autophagy inhibits tumor development in the early stages by enhancing its tumor suppressor activity. Moreover, autophagy drives resistance to anticancer therapy, even though in some tumor types, its activation induces lethal effects on cancer cells. In this review, we summarize the biological mechanisms of autophagy and its dual role in cancer. In addition, we report the current understanding of autophagy in some cancer types with markedly high incidence and/or lethality, and the existing therapeutic strategies targeting autophagy for the treatment of cancer.