High mobility group A1 protein modulates autophagy in cancer cells

Bioinformatic and experimental data pertaining to the role of the NLRP3 inflammasome in ovarian cancer

The Nod-Like Receptor (NLR) family pyrin domain containing 3 (NLRP3) inflammasome plays a role in regulating inflammatory signaling and is a well-established contributor to pyroptotic cell death. It has been investigated extensively in cancer but there remains limited evidence of its role within ovarian cancer (OC). Bioinformatic investigation of gene expression data has highlighted that higher expression of NLRP3 and genes associated with the NLRP3 complex appear to be positively correlated with OC and may also have prognostic significance. However, heterogeneity exists within the results and experimental data is limited and contradictory. If the NLRP3 inflammasome is to be exploited as a therapeutic target, further laboratory-based investigation is required to determine its role in cancer. Furthermore, its relationship with clinically important characteristics such as histopathological subtype may be of key significance in developing targeted therapies towards specific cohorts of patients.

HMGA1 regulates trabectedin sensitivity in advanced soft-tissue sarcoma (STS): A Spanish Group for Research on Sarcomas (GEIS) study

HMGA1 is a structural epigenetic chromatin factor that has been associated with tumor progression and drug resistance. Here, we reported the prognostic/predictive value of HMGA1 for trabectedin in advanced soft-tissue sarcoma (STS) and the effect of inhibiting HMGA1 or the mTOR downstream pathway in trabectedin activity. The prognostic/predictive value of HMGA1 expression was assessed in a cohort of 301 STS patients at mRNA (n = 133) and protein level (n = 272), by HTG EdgeSeq transcriptomics and immunohistochemistry, respectively. The effect of HMGA1 silencing on trabectedin activity and gene expression profiling was measured in leiomyosarcoma cells. The effect of combining mTOR inhibitors with trabectedin was assessed on cell viability in vitro studies, whereas in vivo studies tested the activity of this combination. HMGA1 mRNA and protein expression were significantly associated with worse progression-free survival of trabectedin and worse overall survival in STS. HMGA1 silencing sensitized leiomyosarcoma cells for trabectedin treatment, reducing the spheroid area and increasing cell death. The downregulation of HGMA1 significantly decreased the enrichment of some specific gene sets, including the PI3K/AKT/mTOR pathway. The inhibition of mTOR, sensitized leiomyosarcoma cultures for trabectedin treatment, increasing cell death. In in vivo studies, the combination of rapamycin with trabectedin downregulated HMGA1 expression and stabilized tumor growth of 3-methylcholantrene-induced sarcoma-like models. HMGA1 is an adverse prognostic factor for trabectedin treatment in advanced STS. HMGA1 silencing increases trabectedin efficacy, in part by modulating the mTOR signaling pathway. Trabectedin plus mTOR inhibitors are active in preclinical models of sarcoma, downregulating HMGA1 expression levels and stabilizing tumor growth.

Definition of a Novel Immunogenic Cell Death-Relevant Gene Signature Associated with Immune Landscape in Gastric Cancer

Immunogenic cell death (ICD) induces anti-tumor immunity and aids in dismantling the immunosuppressive immune microenvironment (TME), which belongs to a type of regulated cell death. The differentiation of gastric cancer (GC) subtypes and the discovery of prognostic biomarkers are crucial for its treatment because GC is a disease that is both highly heterogeneous and aggressive. However, although the induction of ICD in tumor cells is associated with a favorable prognosis, the exact mechanism of its role in GC remains unclear. Transcriptome profiling data and clinical data of GC patients were retrieved from The Cancer Genome Atlas (TCGA) database. Herein, patients were classified with the consensus clustering algorithm, and the associated biological functions and immune microenvironment infiltration were explored based on the expression of ICD-associated genes. A risk score signature consisting of 11 ICD-related genes was established via the least absolute shrinkage and selection operator regression (LASSO) method. We have retrieved similar studies in recent years and compared them with our study using the time-dependent receiver operating characteristic (ROC) curves. Gene set variation analysis (GSVA) and single sample gene set enrichment analysis (ssGSEA) were performed to explore the association between the signature and tumor microenvironment (TME). Two distinct subtypes associated with ICD in GC were identified, each with a different prognosis. The ICD-high expression subtype was associated with higher immune cell infiltration and a better prognosis. The ICD-related gene signature containing 11 genes (CGB5, Z84468.1, APOA5, EPHA8, CLEC18C, TLR7, MUC7, MUC15, CTLA4, CALB2, and UGT2B28), could independently and accurately predict the prognosis of GC. In this study, an ICD-based classification was conducted to assist in the diagnosis and personalized therapy for GC. The ICD-related genes risk score model was established to predict prognosis.

Differential effects of the LncRNA RNF157-AS1 on epithelial ovarian cancer cells through suppression of DIRAS3- and ULK1-mediated autophagy

Analyses of several databases showed that the lncRNA RNF157 Antisense RNA 1 (RNF157-AS1) is overexpressed in epithelial ovarian cancer (EOC) tissues. In our study, suppressing RNF157-AS1 strikingly reduced the proliferation, invasion, and migration of EOC cells compared with control cells, while overexpressing RNF157-AS1 greatly increased these effects. By RNA pulldown assays, RNA binding protein immunoprecipitation (RIP) assays, and mass spectrometry, RNF157-AS1 was further found to be able to bind to the HMGA1 and EZH2 proteins. Chromatin immunoprecipitation (ChIP) assays showed that RNF157-AS1 and HMGA1 bound to the ULK1 promoter and prevented the expression of ULK1. Additionally, RNF157-AS1 interacted with EZH2 to bind to the DIRAS3 promoter and diminish DIRAS3 expression. ULK1 and DIRAS3 were found to be essential for autophagy. Combination autophagy inhibitor and RNF157-AS1 overexpression or knockdown, a change in the LC3 II/I ratio was found using immunofluorescence (IF) staining and western blot (WB) analysis. The autophagy level also was confirmed by autophagy/cytotoxicity dual staining. However, the majority of advanced EOC patients require platinum-based chemotherapy, since autophagy is a cellular catabolic response to cell stress. As a result, RNF157-AS1 increased EOC cell sensitivity to chemotherapy and death under cis-platinum (DDP) treatment by suppressing autophagy, as confirmed by cell count Kit-8 (CCK8) assays, flow cytometry, and autophagy/cytotoxicity dual staining. Therefore, the OS and PPS times were longer in EOC patients with elevated RNF157-AS1 expression. RNF157-AS1-mediated autophagy has potential clinical significance in DDP chemotherapy for EOC patients.

High Mobility Group A1 (HMGA1): Structure, Biological Function, and Therapeutic Potential

High mobility group A1 (HMGA1) is a nonhistone chromatin structural protein characterized by no transcriptional activity. It mainly plays a regulatory role by modifying the structure of DNA. A large number of studies have confirmed that HMGA1 regulates genes related to tumours in the reproductive system, digestive system, urinary system and haematopoietic system. HMGA1 is rare in adult cells and increases in highly proliferative cells such as embryos. After being stimulated by external factors, it will produce effects through the Wnt/β-catenin, PI3K/Akt, Hippo and MEK/ERK pathways. In addition, HMGA1 also affects the ageing, apoptosis, autophagy and chemotherapy resistance of cancer cells, which are linked to tumorigenesis. In this review, we summarize the mechanisms of HMGA1 in cancer progression and discuss the potential clinical application of targeted HMGA1 therapy, indicating that targeted HMGA1 is of great significance in the diagnosis and treatment of malignancy.

Autophagy and beyond: Unraveling the complexity of UNC-51-like kinase 1 (ULK1) from biological functions to therapeutic implications

UNC-51-like kinase 1 (ULK1), as a serine/threonine kinase, is an autophagic initiator in mammals and a homologous protein of autophagy related protein (Atg) 1 in yeast and of UNC-51 in Caenorhabditis elegans. ULK1 is well-known for autophagy activation, which is evolutionarily conserved in protein transport and indispensable to maintain cell homeostasis. As the direct target of energy and nutrition-sensing kinase, ULK1 may contribute to the distribution and utilization of cellular resources in response to metabolism and is closely associated with multiple pathophysiological processes. Moreover, ULK1 has been widely reported to play a crucial role in human diseases, including cancer, neurodegenerative diseases, cardiovascular disease, and infections, and subsequently targeted small-molecule inhibitors or activators are also demonstrated. Interestingly, the non-autophagy function of ULK1 has been emerging, indicating that non-autophagy-relevant ULK1 signaling network is also linked with diseases under some specific contexts. Therefore, in this review, we summarized the structure and functions of ULK1 as an autophagic initiator, with a focus on some new approaches, and further elucidated the key roles of ULK1 in autophagy and non-autophagy. Additionally, we also discussed the relationships between ULK1 and human diseases, as well as illustrated a rapid progress for better understanding of the discovery of more candidate small-molecule drugs targeting ULK1, which will provide a clue on novel ULK1-targeted therapeutics in the future.

DNAJC24 is a potential therapeutic target in hepatocellular carcinoma through affecting ammonia metabolism

Evolutionarily conserved heat shock proteins are involved in the heat shock response of cells in response to changes in the external environment. In normal tissues, heat shock proteins can help cells survive in a rapidly changing environment. Likewise, in malignant tumors heat shock proteins may help tumor cells cope with external stresses as well as the stress of treatment. In this way they become accomplices of malignant tumors. Here we demonstrated for the first time that high expression of DNAJC24 (a heat shock protein) shortens survival in patients with HCC by immunohistochemical staining of 167 paired hepatocellular carcinomas and paraneoplastic tissues as well as data from public databases. In vitro experiments demonstrated that stimuli such as hypoxia, starvation and heat could upregulate DNAJC24 expression in HCC cells through transcriptional regulation of HSF2, and high expression of DNAJC24 in HCC cells could promote the proliferation and motility of HCC cells. In addition, we also verified that targeting DNAJC24 under normal culture conditions can affect the proliferation and autophagy of HCC cells by interfering with ammonia metabolism, thereby inhibiting the malignant progression of HCC. Overall, we suggested that DNAJC24 may become a new target for the treatment of HCC.

Down Syndrome Fetal Fibroblasts Display Alterations of Endosomal Trafficking Possibly due to SYNJ1 Overexpression

Endosomal trafficking is essential for cellular homeostasis. At the crossroads of distinct intracellular pathways, the endolysosomal system is crucial to maintain critical functions and adapt to the environment. Alterations of endosomal compartments were observed in cells from adult individuals with Down syndrome (DS), suggesting that the dysfunction of the endosomal pathway may contribute to the pathogenesis of DS. However, the nature and the degree of impairment, as well as the timing of onset, remain elusive. Here, by applying imaging and biochemical approaches, we demonstrate that the structure and dynamics of early endosomes are altered in DS cells. Furthermore, we found that recycling trafficking is markedly compromised in these cells. Remarkably, our results in 18–20 week-old human fetal fibroblasts indicate that alterations in the endolysosomal pathway are already present early in development. In addition, we show that overexpression of the polyphosphoinositide phosphatase synaptojanin 1 (Synj1) recapitulates the alterations observed in DS cells, suggesting a role for this lipid phosphatase in the pathogenesis of DS, likely already early in disease development. Overall, these data strengthen the link between the endolysosomal pathway and DS, highlighting a dangerous liaison among Synj1, endosomal trafficking and DS.

Biological causes of immunogenic cancer cell death (ICD) and anti-tumor therapy; Combination of Oncolytic virus-based immunotherapy and CAR T-cell therapy for ICD induction

Chimeric antigen receptor (CAR) T-cell therapy is a promising and rapidly expanding therapeutic option for a wide range of human malignancies. Despite the ongoing progress of CAR T-cell therapy in hematologic malignancies, the application of this therapeutic strategy in solid tumors has encountered several challenges due to antigen heterogeneity, suboptimal CAR T-cell trafficking, and the immunosuppressive features of the tumor microenvironment (TME). Oncolytic virotherapy is a novel cancer therapy that employs competent or genetically modified oncolytic viruses (OVs) to preferentially proliferate in tumor cells. OVs in combination with CAR T-cells are promising candidates for overcoming the current drawbacks of CAR T-cell application in tumors through triggering immunogenic cell death (ICD) in cancer cells. ICD is a type of cellular death in which danger-associated molecular patterns (DAMPs) and tumor-specific antigens are released, leading to the stimulation of potent anti-cancer immunity. In the present review, we discuss the biological causes of ICD, different types of ICD, and the synergistic combination of OVs and CAR T-cells to reach potent tumor-specific immunity.

Transcriptional and Post-Transcriptional Regulation of Autophagy

Autophagy is a widely conserved process in eukaryotes that is involved in a series of physiological and pathological events, including development, immunity, neurodegenerative disease, and tumorigenesis. It is regulated by nutrient deprivation, energy stress, and other unfavorable conditions through multiple pathways. In general, autophagy is synergistically governed at the RNA and protein levels. The upstream transcription factors trigger or inhibit the expression of autophagy- or lysosome-related genes to facilitate or reduce autophagy. Moreover, a significant number of non-coding RNAs (microRNA, circRNA, and lncRNA) are reported to participate in autophagy regulation. Finally, post-transcriptional modifications, such as RNA methylation, play a key role in controlling autophagy occurrence. In this review, we summarize the progress on autophagy research regarding transcriptional regulation, which will provide the foundations and directions for future studies on this self-eating process.

Overexpression of HMGA1 confers radioresistance by transactivating RAD51 in cholangiocarcinoma

Cholangiocarcinomas (CCAs) are rare but aggressive tumors of the bile ducts. CCAs are often diagnosed at an advanced stage and respond poorly to current conventional radiotherapy and chemotherapy. High mobility group A1 (HMGA1) is an architectural transcription factor that is overexpressed in multiple malignant tumors. In this study, we showed that the expression of HMGA1 is frequently elevated in CCAs and that the high expression of this gene is associated with a poor prognosis. Functionally, HMGA1 promotes CCA cell proliferation/invasion and xenograft tumor growth. Furthermore, HMGA1 transcriptionally activates RAD51 by binding to its promoter through two HMGA1 response elements. Notably, overexpression of HMGA1 promotes radioresistance whereas its knockdown causes radiosensitivity of CCA cells to X-ray irradiation. Moreover, rescue experiments reveal that inhibition of RAD51 reverses the effect of HMGA1 on radioresistance and proliferation/invasion. These findings suggest that HMGA1 functions as a novel regulator of RAD51 and confers radioresistance in cholangiocarcinoma.

LINC00963/miR-4458 regulates the effect of oxaliplatin in gastric cancer by mediating autophagic flux through targeting of ATG16L1

Oxaliplatin resistance is the greatest obstacle to the management of local recurrence in gastric cancer patients after surgery. Accumulating evidence has suggested that inhibiting autophagy may be a novel approach for reversing resistance to oxaliplatin treatment. In this manuscript, we aimed to investigate the role of LINC00963 in regulating autophagy and oxaliplatin resistance. qRT-PCR, immunochemistry staining, and western blotting were used to detect gene expression. Plasmids were used to up- and downregulate the expression of LINC00963 and miR-4458. A caspase 3/7 activity kit and flow cytometry were used to detect the apoptosis rate. CCK8 and Transwell assays were used to test cell proliferation and migration, respectively. Transmission electron microscopy and a dual fluorescent lentivirus autophagy system were used to evaluate autophagic flux. Dual luciferase reporter gene assays and RNA pulldown assays were used to evaluate the potential crosstalk. LINC00963 was highly expressed in gastric cancer patients and cell lines. In addition, high LINC00963 expression was found to be associated with poor prognosis and local recurrence in gastric cancer patients, indicating that LINC00963 might be involved in oxaliplatin resistance. Moreover, we found that LINC00963 was aberrantly highly expressed in oxaliplatin-resistant SGC-7901 (SGC-7901-R) cells and promoted proliferation and migration and reduced the apoptosis rate in SGC-7901-R cells. Furthermore, among all potential target microRNAs, miR-4458 was found to be negatively regulated by LINC00963 both in vivo and in vitro. In addition, miR-4458 overexpression led to impaired proliferation and migration and enhanced cell apoptosis and G1 arrest in SGC-7901-R cells. Further RNA pulldown and dual luciferase reporter gene assays indicated the interaction between LINC00963 and miR-4458. Moreover, we found enhanced autophagic flux in SGC-7901-R cells compared with SGC-7901 cells; in addition, an inhibitor of autophagy induced apoptosis in SGC-7901-R cells. Then, we found that downregulation of LINC00963 expression and upregulation of miR-4458 expression significantly suppressed autophagic flux in SGC-7901-R cells. Based on starBase V3.0 and dual luciferase reporter gene assays, we predicted and confirmed that ATG16L1 might be the target of miR-4458 to regulate autophagy. In conclusion, LINC00963 and miR-4458 are potential biomarkers for predicting the overall survival of gastric cancer patients. Moreover, targeting LINC00963 to inhibit autophagic flux sensitizes gastric cancer cells to oxaliplatin treatment, suggesting that it is a potential novel therapeutic target for improving oxaliplatin sensitivity.

FOXO1: a pivotal pioneer factor in oral squamous cell carcinoma

The transcription factor FOXO1 regulates cell cycle progression, apoptosis and oxidative stress. Interestingly, numerous studies have implicated their positive role in tumor suppression, angiogenesis and metastasis in oral squamous cell carcinoma (OSCC). Distinct post-transcriptional and post-translational modifications actuate the physiological role of FOXO1 in OSCC. Here, we evaluate the role of FOXO1 proteins in OSCC, their fundamental structure and the major players involved in FOXO1 regulation and how they are Pharmacologically modulated in OSCC. Finally, their role in regulating epithelial-mesenchymal transition (EMT), autophagy, stress tolerance and stemness, which would significantly aid in novel potential oversight for future research and thus developing strategies to prevent or reverse OSCC.

Critical role of the high mobility group A proteins in hematological malignancies

The high mobility group A (HMGA) protein family is composed of three non‐histone chromatin remodeling proteins that act as architectural transcriptional factors. Indeed, although HMGA proteins lack transcriptional activity per se, they bind the minor groove of DNA at AT‐rich sequences, and, interacting with the transcription machinery, are able to modify chromatin modeling, thus regulating the expression of several genes. HMGA proteins have been deeply involved in embryogenesis process, and a large volume of studies has pointed out their key role in human cancer. Here, we review the studies on the role of the HMGA proteins in human hematological malignancies: they are overexpressed in most of the cases and their expression correlates with a reduced survival. In some cases, such as in acute lymphoblastic leukemia and acute myelogenous leukemia, HMGA2 gene rearrangements have been also described. Finally, recent studies evidence a synergism between HMGA and EZH2 in diffuse B‐cell lymphomas, suggesting an innovative therapy for this disease based on the inhibition of the function of both these proteins.

Phenotypic Effects of Homeodomain-Interacting Protein Kinase 2 Deletion in Mice

Homeodomain-interacting protein kinase 2 (HIPK2) is a serine-threonine kinase that phosphorylates various transcriptional and chromatin regulators, thus modulating numerous important cellular processes, such as proliferation, apoptosis, DNA damage response, and oxidative stress. The role of HIPK2 in the pathogenesis of cancer and fibrosis is well established, and evidence of its involvement in the homeostasis of multiple organs has been recently emerging. We have previously demonstrated that Hipk2-null (Hipk2-KO) mice present cerebellar alterations associated with psychomotor abnormalities and that the double ablation of HIPK2 and its interactor HMGA1 causes perinatal death due to respiratory failure. To identify other alterations caused by the loss of HIPK2, we performed a systematic morphological analysis of Hipk2-KO mice. Post-mortem examinations and histological analysis revealed that Hipk2 ablation causes neuronal loss, neuronal morphological alterations, and satellitosis throughout the whole central nervous system (CNS); a myopathic phenotype characterized by variable fiber size, mitochondrial proliferation, sarcoplasmic inclusions, morphological alterations at neuromuscular junctions; and a cardiac phenotype characterized by fibrosis and cardiomyocyte hypertrophy. These data demonstrate the importance of HIPK2 in the physiology of skeletal and cardiac muscles and of different parts of the CNS, thus suggesting its potential relevance for different new aspects of human pathology.

MicroRNA-296-5p inhibits cell proliferation by targeting HMGA1 in colorectal cancer

An increasing body of evidence indicates the involvement of microRNAs (miRNAs/miRs) in the initiation and progression of colorectal cancer (CRC). miR-296-5p was recently identified as a tumor suppressor in a variety of human cancer types; however, its function in CRC remains largely unknown. The present study demonstrated that the expression of miR-296-5p was significantly downregulated in CRC tissues and cell lines. The overexpression of miR-296-5p markedly inhibited proliferation, and induced cell cycle arrest and apoptosis in CRC cells. Bioinformatics analysis suggested that high mobility group AT-hook 1 (HMGA1) may be a target of miR-296-5p in CRC cells. Further experiments showed that miR-296-5p bound the 3'-untranslated region of HMGA1 and decreased its expression in CRC cells. HMGA1 was overexpressed in CRC tissues and was inversely correlated with the expression of miR-296-5p. The restoration of HMGA1 significantly reversed the inhibitory effect of miR-296-5p on the proliferation of CRC cells. Overall, the findings of the present study indicate that miR-296-5p suppressed the progression of CRC, at least partially via targeting HMGA1. Thus, miR-296-5p is a potential target for novel therapies in CRC.

Mechanisms of Regulated Cell Death: Current Perspectives

Balancing cell survival and cell death is fundamental to development and homeostasis. Cell death is regulated by multiple interconnected signaling pathways and molecular mechanisms. Regulated cell death (RCD) is implicated in fundamental processes such as organogenesis and tissue remodeling, removal of unnecessary structures or cells, and regulation of cell numbers. RCD can also be triggered by exogenous perturbations of the intracellular or extracellular microenvironment when the adaptive processes that respond to stress fail. During the past few years, many novel forms of non-apoptotic RCD have been identified, and the characterization of RCD mechanisms at a molecular level has deepened our understanding of diseases encountered in human and veterinary medicine. Given the complexity of these processes, it has become clear that the identification of RCD cannot be based simply on morphologic characteristics and that descriptive and diagnostic terms presently used by pathologists-such as individual cell apoptosis or necrosis-appear inadequate and possibly misleading. In this review, the current understanding of the molecular machinery of each type of non-apoptotic RCD mechanisms is outlined. Due to the continuous discovery of new mechanisms or nuances of previously described processes, the limitations of the terms apoptosis and necrosis to indicate microscopic findings are also reported. In addition, the need for a standard panel of biomarkers and functional tests to adequately characterize the underlying RCD and its role as a mechanism of disease is considered.

HMGA1 Induction of miR-103/107 Forms a Negative Feedback Loop to Regulate Autophagy in MPTP Model of Parkinson's Disease

Autophagy dysfunction has been directly linked with the onset and progression of Parkinson’s disease (PD), but the underlying mechanisms are not well understood. High-mobility group A1 (HMGA1), well-known chromatin remodeling proteins, play pivotal roles in diverse biological processes and diseases. Their function in neural cell death in PD, however, have not yet been fully elucidated. Here, we report that HMGA1 is highly induced during dopaminergic cell death in vitro and mice models of PD in vivo. Functional studies using genetic knockdown of endogenous HMGA1 show that HMGA1 signaling inhibition accelerates neural cell death, at least partially through aggravating MPP⁺-induced autophagic flux reduction resulting from partial block in autophagic flux at the terminal stages, indicating a novel potential neuroprotective role for HMGA1 in dopaminergic neurons death. MicroRNA-103/107 (miR-103/107) family, which is highly expressed in neuron, coordinately ensures proper end-stage autophagy. We further illustrate that MPP⁺/1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced HMGA1 elevation counterparts the effect of miR-103/107 downregulation by directly binding to their promoters, respectively, sustaining their expression in MPP⁺-damaged MN9D cells and modulates autophagy through CDK5R1/CDK5 signaling pathway. We also find that HMGA1 is a direct target of miR-103/107 family. Thus, our results suggest that HMGA1 forms a negative feedback loop with miR-103/107-CDK5R1/CDK5 signaling to regulate the MPP⁺/MPTP-induced autophagy impairment and neural cell death. Collectively, we identify a paradigm for compensatory neuroprotective HMGA1 signaling in dopaminergic neurons that could have important therapeutic implications for PD.

Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)1

In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field.

Autophagy-mediated metabolic effects of aspirin

Salicylate, the active derivative of aspirin (acetylsalicylate), recapitulates the mode of action of caloric restriction inasmuch as it stimulates autophagy through the inhibition of the acetyltransferase activity of EP300. Here, we directly compared the metabolic effects of aspirin medication with those elicited by 48 h fasting in mice, revealing convergent alterations in the plasma and the heart metabolome. Aspirin caused a transient reduction of general protein acetylation in blood leukocytes, accompanied by the induction of autophagy. However, these effects on global protein acetylation could not be attributed to the mere inhibition of EP300, as determined by epistatic experiments and exploration of the acetyl-proteome from salicylate-treated EP300-deficient cells. Aspirin reduced high-fat diet-induced obesity, diabetes, and hepatosteatosis. These aspirin effects were observed in autophagy-competent mice but not in two different models of genetic (Atg4b^−/− or Bcln1^+/−) autophagy-deficiency. Aspirin also improved tumor control by immunogenic chemotherapeutics, and this effect was lost in T cell-deficient mice, as well as upon knockdown of an essential autophagy gene (Atg5) in cancer cells. Hence, the health-improving effects of aspirin depend on autophagy.

Immunogenic Cell Death and Elimination of Immunosuppressive Cells: A Double-Edged Sword of Chemotherapy

Chemotherapy is initially used to kill proliferative cells. In the current area of emerging immunotherapy, chemotherapies have shown their ability to modulate the tumor micro environment and immune response. We focus here on two main effects: first, immunogenic cell death, defined as a form of regulated cell death (RCD) that is sufficient to activate an adaptive immune response in immunocompetent hosts; and second, the depletion of suppressive cells, known to play a major role in immune escape and resistance to immunotherapy. In this review, we present a review of different classically used chemotherapies focusing on this double effect on immunity. These immunological effects of chemotherapy could be exploited to promote efficacy of immunotherapy. Broadening our understanding will make it possible to provide rationales for the combination of chemoimmunotherapy in early clinical trials.

Heme Induces BECN1/ATG5-Mediated Autophagic Cell Death via ER Stress in Neurons

Intracerebral hemorrhage (ICH) is a serious medical problem, and effective treatment is limited. Hemorrhaged blood is highly toxic to the brain, and heme, which is mainly released from hemoglobin, plays a vital role in neurotoxicity. However, the specific mechanism involved in heme-mediated neurotoxicity has not been well studied. In this study, we investigated the neurotoxicity of heme in neurons. Neurons were treated with heme, and cell death, autophagy, and endoplasmic reticulum (ER) stress were analyzed. In addition, the relationship between autophagy and apoptosis in heme-induced cell death and the downstream effects were also assessed. We showed that heme induced cell death and autophagy in neurons. The suppression of autophagy using either pharmacological inhibitors (3-methyladenine) or RNA interference of essential autophagy genes (BECN1 and ATG5) decreased heme-induced cell death in neurons. Moreover, the ER stress activator thapsigargin increased cell autophagy and the cell death ratio following heme treatment. Autophagy promoted heme-induced cell apoptosis and cell death through the BECN1/ATG5 pathway. Our findings suggest that heme potentiates neuronal autophagy via ER stress, which in turn induces cell death via the BECN1/ATG5 pathway. Targeting ER stress-mediated autophagy might be a promising therapeutic strategy for ICH.

Downregulation of HMGA1 Mediates Autophagy and Inhibits Migration and Invasion in Bladder Cancer via miRNA-221/TP53INP1/p-ERK Axis

MicroRNAs (miRNAs) have been implicated in regulating the development and metastasis of human cancers. MiR-221 is reported to be an oncogene in multiple cancers, including bladder cancer (BC). Deregulation of autophagy is associated with multiple human malignant cancers. Whether and how miR-221 regulates autophagy and how miR-221 has been regulated in BC are poorly understood. This study explored the potential functions and mechanisms of miR-221 in the autophagy and tumorigenesis of BC. We showed that the downregulation of miR-221 induces autophagy via increasing TP53INP1 (tumor protein p53 inducible nuclear protein 1) and inhibits migration and invasion of BC cells through suppressing activation of extracellular signal-regulated kinase (ERK). Furthermore, the expression of miR-221 is regulated by high-mobility group AT-hook 1 (HMGA1) which is overexpressed in BC. And both miR-221 and HMGA1 are correlated with poor patient survival in BC. Finally, the downregulation of HMGA1 suppressed the proliferative, migrative, and invasive property of BC by inducing toxic autophagy via miR-221/TP53INP1/p-ERK axis. Collectively, our findings demonstrate that the downregulation of miR-221 and HMGA1 mediates autophagy in BC, and both of them are valuable therapeutic targets for BC.

MYC-regulated pseudogene HMGA1P6 promotes ovarian cancer malignancy via augmenting the oncogenic HMGA1/2

Pseudogenes have long been considered as nonfunctional genomic sequences. Recent studies have shown that they can potentially regulate the expression of protein-coding genes and are dysregulated in diseases including cancer. However, the potential roles of pseudogenes in ovarian cancer have not been well studied. Here we characterized the pseudogene expression profile in HGSOC (high-grade serous ovarian carcinoma) by microarray. We identified 577 dysregulated pseudogenes and most of them were up-regulated (538 of 577). HMGA1P6 (High mobility group AT-hook 1 pseudogene 6) was one of the overexpressed pseudogenes and its expression was inversely correlated with patient survival. Mechanistically, HMGA1P6 promoted ovarian cancer cell malignancy by acting as a ceRNA (competitive endogenous RNA) that led to enhanced HMGA1 and HMGA2 expression. Importantly, HMGA1P6 was transcriptionally activated by oncogene MYC in ovarian cancer. Our findings reveal that MYC may contribute to oncogenesis through transcriptional regulation of pseudogene HMGA1P6 in ovarian cancer.

High-mobility group AT-hook 1 promotes cardiac dysfunction in diabetic cardiomyopathy via autophagy inhibition

High-mobility group AT-hook1 (HMGA1, formerly HMG-I/Y), an architectural transcription factor, participates in a number of biological processes. However, its effect on cardiac remodeling (refer to cardiac inflammation, apoptosis and dysfunction) in diabetic cardiomyopathy remains largely indistinct. In this study, we found that HMGA1 was upregulated in diabetic mouse hearts and high-glucose-stimulated cardiomyocytes. Overexpression of HMGA1 accelerated high-glucose-induced cardiomyocyte inflammation and apoptosis, while HMGA1 knockdown relieved inflammation and apoptosis in cardiomyocytes in response to high glucose. Overexpression of HMGA1 in mice heart by adeno-associated virus 9 (AAV9) delivery system deteriorated the inflammatory response, increased apoptosis and accelerated cardiac dysfunction in streptozotocin-induced diabetic mouse model. Knockdown of HMGA1 by AAV9-shHMGA1 in vivo ameliorated cardiac remodeling in diabetic mice. Mechanistically, we found that HMGA1 inhibited the formation rather than the degradation of autophagy by regulating P27/CDK2/mTOR signaling. CDK2 knockdown or P27 overexpression blurred HMGA1 overexpression-induced deteriorating effects in vitro. P27 overexpression in mice heart counteracted HMGA1 overexpression-induced increased cardiac remodeling in diabetic mice. The luciferase reporter experiment confirmed that the regulatory effect of HMGA1 on P27 was mediated by miR-222. In addition, a miR-222 antagomir counteracted HMGA1 overexpression-induced deteriorating effects in vitro. Taken together, our data indicate that HMGA1 aggravates diabetic cardiomyopathy by directly regulating miR-222 promoter activity, which inhibits P27/mTOR-induced autophagy.

High Mobility Group A (HMGA): Chromatin Nodes Controlled by a Knotty miRNA Network

High mobility group A (HMGA) proteins are oncofoetal chromatin architectural factors that are widely involved in regulating gene expression. These proteins are unique, because they are highly expressed in embryonic and cancer cells, where they play a relevant role in cell proliferation, stemness, and the acquisition of aggressive tumour traits, i.e., motility, invasiveness, and metastatic properties. The HMGA protein expression levels and activities are controlled by a connected set of events at the transcriptional, post-transcriptional, and post-translational levels. In fact, microRNA (miRNA)-mediated RNA stability is the most-studied mechanism of HMGA protein expression modulation. In this review, we contribute to a comprehensive overview of HMGA-targeting miRNAs; we provide detailed information regarding HMGA gene structural organization and a comprehensive evaluation and description of HMGA-targeting miRNAs, while focusing on those that are widely involved in HMGA regulation; and, we aim to offer insights into HMGA-miRNA mutual cross-talk from a functional and cancer-related perspective, highlighting possible clinical implications.

Double knock-out of Hmga1 and Hipk2 genes causes perinatal death associated to respiratory distress and thyroid abnormalities in mice

The serine–threonine kinase homeodomain-interacting protein kinase 2 (HIPK2) modulates important cellular functions during development, acting as a signal integrator of a wide variety of stress signals, and as a regulator of transcription factors and cofactors. We have previously demonstrated that HIPK2 binds and phosphorylates High-Mobility Group A1 (HMGA1), an architectural chromatinic protein ubiquitously expressed in embryonic tissues, decreasing its binding affinity to DNA. To better define the functional role of HIPK2 and HMGA1 interaction in vivo, we generated mice in which both genes are disrupted. About 50% of these Hmga1/Hipk2 double knock-out (DKO) mice die within 12 h of life (P1) for respiratory failure. The DKO mice present an altered lung morphology, likely owing to a drastic reduction in the expression of surfactant proteins, that are required for lung development. Consistently, we report that both HMGA1 and HIPK2 proteins positively regulate the transcriptional activity of the genes encoding the surfactant proteins. Moreover, these mice display an altered expression of thyroid differentiation markers, reasonably because of a drastic reduction in the expression of the thyroid-specific transcription factors PAX8 and FOXE1, which we demonstrate here to be positively regulated by HMGA1 and HIPK2. Therefore, these data indicate a critical role of HIPK2/HMGA1 cooperation in lung and thyroid development and function, suggesting the potential involvement of their impairment in the pathogenesis of human lung and thyroid diseases.

The FoxO-Autophagy Axis in Health and Disease

Autophagy controls cellular remodeling and quality control. Dysregulated autophagy has been implicated in several human diseases including obesity, diabetes, cardiovascular disease, neurodegenerative diseases, and cancer. Current evidence has revealed that FoxO (forkhead box class O) transcription factors have a multifaceted role in autophagy regulation and dysregulation. Nuclear FoxOs transactivate genes that control the formation of autophagosomes and their fusion with lysosomes. Independently of transactivation, cytosolic FoxO proteins induce autophagy by directly interacting with autophagy proteins. Autophagy is also controlled by FoxOs through epigenetic mechanisms. Moreover, FoxO proteins can be degraded directly or indirectly by autophagy. Cutting-edge evidence is reviewed that the FoxO-autophagy axis plays a crucial role in health and disease.

Anti-Apoptotic and Anti-Oxidant Proteins in Glioblastomas: Immunohistochemical Expression of Beclin and DJ-1 and Its Correlation with Prognosis

DJ-1 deglycase is a protein with anti-oxidative and anti-apoptotic properties and its role in oncogenesis is controversial. Indeed in primary breast cancer and non-small-cell lung carcinoma, its higher expression was shown in more aggressive tumors while in other neoplasms (e.g., pancreatic adenocarcinoma), higher expression was related to better prognosis. Beclin has a relevant role in autophagy and cellular death regulation, processes that are well known to be impaired in neoplastic cells. DJ-1 shows the ability to modulate signal transduction. It can modulate autophagy through many signaling pathways, a process that can mediate either cell survival or cell death depending on the circumstances. Previously, it has been suggested that the involvement of DJ-1 in autophagy regulation may play a role in tumorigenesis. The aim of our study was to investigate the link between DJ-1 and Beclin-1 in glioblastoma through the immunohistochemical expression of such proteins and to correlate the data obtained with prognosis. Protein expression was assessed by immunohistochemistry and the immunoscores were correlated with clinicopathologic parameters. Kaplan–Meier survival curves were generated. A statistically significant association between DJ-1 score and recurrence (p = 0.0189) and between the former and Isocitrate Dehydrogenase 1 (IDH1) mutation (p = 0.0072) was observed. Kaplan–Meier survival curve analysis revealed that a higher DJ-1 score was associated with longer overall survival (p = 0.0253, ĸ2 = 5.005). Furthermore, an unexpected direct correlation (p = 0.0424, r = 0.4009) between DJ-1 and Beclin score was evident. The most significant result of the present study was the evidence of high DJ-1 expression in IDH-mutant tumors and in cases with longer overall survival. This finding could aid, together with IDH1, in the identification of glioblastomas with better prognosis.

HMGA1 exacerbates tumor progression by activating miR-222 through PI3K/Akt/MMP-9 signaling pathway in uveal melanoma

High-mobility group A1 (HMGA1), an architectural transcription factor, participates in different human tumors' biological progression. HMGA1 overexpression is associated with malignant cellular behavior in a wide range of cancers but the underlying mechanism remains poorly illuminated. In this study, we showed PI3K/Akt/MMP9 pathway activity could be positively regulated by HMGA1 using western blotting, real-time polymerase chain reaction (RT-PCR) and immunochemistry both in vitro (C918 and MUM-2B cell lines) and in vivo (xenograft mouse model). Later, MiRTarBase was used to identify the relationship between HMGA1 and miR-222-3p, we found miR-222 is positively regulated by HMGA1. Moreover, the proliferation and migration of UM cells significantly increased in the miR-222 mimics group and decreased in the miR-222 inhibitor group detected by the Annexin V-FITC apoptosis detection kit, CCK-8 and scratch wound-healing. The p-PI3K, p-Akt and MMP9 expressions were elevated in UM cells transfected with miR-222 mimics, and suppressed in the miR-222 inhibitor group. Together, our study highlights that HMGA1 acts as a pivotal regulator in UM tumor growth, proposing a critical viewpoint that HMGA1 expedites progression through the PI3K/Akt/MMP9 pathway and oncogenic miR-222 in UM.

let-7i inhibits proliferation and migration of bladder cancer cells by targeting HMGA1

Background

Let-7 is one of the earliest discovered microRNAs(miRNAs) and has been reported to be down-regulated in multiple malignant tumors. The effects and molecular mechanisms of let-7i in bladder cancer are still unclear. This study was to investigate the effects and potential mechanisms of let-7i on bladder cancer cells.

Methods

Total RNA was extracted from bladder cancer cell lines. The expression levels of let-7i and HMGA1 were examined by quantitative real-time PCR. Cell viability was detected using the CCK-8 and colony formation assays, while transwell and wound healing assays were used to evaluate migration ability. Luciferase reporter assay and western blot were used to confirm the target gene of let-7i.

Results

Compared with the SV-40 immortalized human uroepithelial cell line (SV-HUC-1), bladder cancer cell lines T24 and 5637 had low levels of let-7i expression, but high levels of high mobility group protein A1 (HMGA1) expression. Transfection of cell lines T24 and 5637 with let-7i mimic suppressed cell proliferation and migration. Luciferase reporter assay confirmed HMGA1 may be one of the target genes of let-7i-5p. Protein and mRNA expression of HMGA1 was significantly downregulated in let-7i mimic transfected cell lines T24 and 5637.

Conclusions

Up-regulation of let-7i suppressed proliferation and migration of the human bladder cancer cell lines T24 and 5637 by targeting HMGA1. These findings suggest that let-7i might be considered as a novel therapeutic target for bladder cancer.

Nonhistone human chromatin protein PC4 is critical for genomic integrity and negatively regulates autophagy

Multifunctional human transcriptional positive co-activator 4 (PC4) is a bona fide nonhistone component of the chromatin and plays a pivotal role in the process of chromatin compaction and functional genome organization. Knockdown of PC4 expression causes a drastic decompaction which leads to open conformation of the chromatin, and thereby altered nuclear architecture, defects in chromosome segregation and changed epigenetic landscape. Interestingly, these defects do not induce cellular death but result in enhanced cellular proliferation, possibly through enhanced autophagic activity. Moreover, PC4 depletion confers significant resistance to gamma irradiation. Exposure to gamma irradiation further induced autophagy in these cells. Inhibition of autophagy by small molecule inhibitors as well as by silencing of a critical autophagy gene drastically reduces the ability of PC4 knockdown cells to survive. On the contrary, complementation with wild-type PC4 could reverse this phenomenon, confirming the process of autophagy as the key mechanism for radiation resistance in the absence of PC4. These data connect the unexplored role of chromatin architecture in regulating autophagy during stress conditions such as radiation.

Effects of Long-Term Citrate Treatment in the PC3 Prostate Cancer Cell Line

Acute administration of a high level of extracellular citrate displays an anti-proliferative effect on both in vitro and in vivo models. However, the long-term effect of citrate treatment has not been investigated yet. Here, we address this question in PC3 cells, a prostate-cancer-derived cell line. Acute administration of high levels of extracellular citrate impaired cell adhesion and inhibited the proliferation of PC3 cells, but surviving cells adapted to grow in the chronic presence of 20 mM citrate. Citrate-resistant PC3 cells are significantly less glycolytic than control cells. Moreover, they overexpress short-form, citrate-insensitive phosphofructokinase 1 (PFK1) together with full-length PFK1. In addition, they show traits of mesenchymal-epithelial transition: an increase in E-cadherin and a decrease in vimentin. In comparison with PC3 cells, citrate-resistant cells display morphological changes that involve both microtubule and microfilament organization. This was accompanied by changes in homeostasis and the organization of intracellular organelles. Thus, the mitochondrial network appears fragmented, the Golgi complex is scattered, and the lysosomal compartment is enlarged. Interestingly, citrate-resistant cells produce less total ROS but accumulate more mitochondrial ROS than control cells. Consistently, in citrate-resistant cells, the autophagic pathway is upregulated, possibly sustaining their survival. In conclusion, chronic administration of citrate might select resistant cells, which could jeopardize the benefits of citrate anticancer treatment.

STF-62247 accumulates in lysosomes and blocks late stages of autophagy to selectively target von Hippel-Lindau-inactivated cells

Autophagy is a highly conserved, homeostatic process by which cytosolic components reach lysosomes for degradation. The roles played by different autophagic processes in cancer are complex and remain cancer type and stage dependent. Renal cell carcinoma (RCC) is the most common subtype of kidney cancer and is characterized by the inactivation of the von Hippel-Lindau (VHL) tumor suppressor. Our previous study identified a small compound, STF-62247, as an autophagy-modulating molecule causing selective cytotoxicity for VHL-inactivated cells. This present study investigates the effects of STF-62247 specifically on the macroautophagic flux to better characterize its mechanism of action in RCC. Our results clearly demonstrate that this compound is a potent blocker of late stages of autophagy. We show that inhibiting autophagy by CRISPR knockouts of autophagy-related genes rendered VHL-deficient cells insensitive to STF-62247, uncovering the importance of the autophagic pathway in STF-selective cell death. By exploiting the autofluorescence of STF-62247, we pinpointed its cellular localization to lysosomes. Finally, in response to prolonged STF treatments, we show that VHL-proficient cells are able to surmount the block in late stages of autophagy by restoring their lysosome numbers. Conversely, an increase in autophagic vesicles accompanied by a time-dependent decrease in lysosomes was observed in VHL-deficient cells. This is the first mechanistic study investigating STF-62447’s effects on the autophagic flux in RCC. Importantly, our study reclassifies STF-62247 as a blocker of later stages of autophagy and highlights the possibility of blocking this process through lysosome disruption in VHL-mutated RCCs.

Silencing H19 regulated proliferation, invasion, and autophagy in the placenta by targeting miR-18a-5p

Fetal growth restriction (FGR) is a serious pregnancy complication associated with increased perinatal mortality and morbidity. It may lead to neurodevelopmental impairment and adulthood onset disorders. Recently, long noncoding RNAs (lncRNAs) were found to be associated with the pathogenesis of FGR. Here we report that the lncRNAH19 is significantly decreased in placentae from pregnancies with FGR. Downregulation of H19 leads to reduced proliferation and invasion of extravillous trophoblast cells. This is identified with reduced trophoblast invasion, which has been discovered in FGR. Autophagy is exaggerated in FGR. Downregulation of H19 promotes autophagy via the PI3K/AKT/mTOR and MAPK/ERK/mTOR pathways of extravillous trophoblast cells in FGR. We also found that the expression level of microRNAs miR-18a-5p was negatively correlated with that of H19. H19 can act as an endogenous sponge by directly binding to miR-18a-5p, which targets IRF2. The expression of miR-18a-5p was upregulated, but IRF2 expression was downregulated after the H19 knockdown. In conclusion, our study revealed that H19 downexpressed could inhibit proliferation and invasion, and promote autophagy by targeting miR-18a-5pin HTR8 and JEG3 cells. We propose that aberrant regulation of H19/miR-18a-5p-mediated regulatory pathway may contribute to the molecular mechanism of FGR. We indicated that H19 may be a potential predictive, diagnostic, and therapeutic modality for FGR.

RNA binding protein HuR promotes osteosarcoma cell progression via suppressing the miR-142-3p/HMGA1 axis

The present study aimed to study the roles and underlying mechanisms of human antigen R (HuR) in osteosarcoma (OS) cell progression. It was determined that the HuR mRNA and protein levels were significantly upregulated in OS tissues, compared with that in normal adjacent tissues. HuR expression was negatively associated with miR-142-3p expression, but positively with High Mobility Group AT-Hook 1 (HMGA1). Additionally, knockdown of HuR inhibited OS cells viability, epithelial-mesenchymal transition and promoted cell apoptosis. HuR was determined to harbor binding sites on HMGA1, directly binding to HMGA1, increasing HMGA1 mRNA stability and expression. Notably, the promotion of HuR on HMGA1 expression was attenuated via miR-142-3p overexpression, and miR-142-3p could directly bind to HMGA1 3'untranslated region (UTR). Furthermore, HMGA1 3'UTR with a mutated miR-142-3p binding site did not respond to HuR alterations. Finally, the inhibition of HuR knockdown was attenuated or even reversed via HMGA1 overexpression; therefore, the results of the present study indicated that RNA binding protein HuR may facilitate OS cell progression via competitively binding to HMGA1 with miR-142-3p.

Overexpression of long non-coding RNA H19 promotes invasion and autophagy via the PI3K/AKT/mTOR pathways in trophoblast cells

BACKGROUND

Preeclampsia (PE), characterized by hypertension and proteinuria, is a leading cause of perinatal and maternal mortality. Considering that mutation of H19 gene is closely associated with PE, we aimed to explore the functional role of long non-coding RNA H19 (lncRNA-H19) in trophoblast cells.

METHODS

Expression of lncRNA-H19 in placenta tissues from patients with PE and healthy pregnant women after delivery was determined by quantitative reverse transcription PCR. Then, lncRNA-H19 was abnormally expressed in JEG-3 and HTR-8 cells by stable cell transfection. Cell viability and invasion were assessed by using CCK-8 and Matrigel-coated Millicell system, respectively. Expression of key proteins associated with invasion and autophagy as well as key kinases in the phosphatidylinositol-3-kinase (PI3K)/AKT/mechanistic target of rapamycin (mTOR) pathways were measured by Western blot analysis. Number of GFP-labeled autophagosomes was counted under a confocal microscope.

RESULTS

Level of lncRNA-H19 in the placenta tissues from PE patients was higher than that from healthy controls. LncRNA-H19 overexpression reduced cell viability but increased invasion of JEG-3 and HTR-8 cells. LncRNA-H19 silence showed the opposite effects. In addition, lncRNA-H19 overexpression promoted autophagy in trophoblast cells. Furthermore, phosphorylated levels of key kinases in the PI3K/AKT/mTOR pathways were enhanced by lncRNA-H19 overexpression while were reduced by lncRNA-H19 silence.

CONCLUSION

LncRNA-H19, which was up-regulated in PE, reduced cell viability but promoted invasion and autophagy in trophoblast cells, along with activation of the PI3K/AKT/mTOR pathways. Our study provides a theoretical basis for pathogenesis of PE, aiding to identification of novel therapeutic strategies for PE.

Molecular mechanisms of cell death: recommendations of the Nomenclature Committee on Cell Death 2018

Over the past decade, the Nomenclature Committee on Cell Death (NCCD) has formulated guidelines for the definition and interpretation of cell death from morphological, biochemical, and functional perspectives. Since the field continues to expand and novel mechanisms that orchestrate multiple cell death pathways are unveiled, we propose an updated classification of cell death subroutines focusing on mechanistic and essential (as opposed to correlative and dispensable) aspects of the process. As we provide molecularly oriented definitions of terms including intrinsic apoptosis, extrinsic apoptosis, mitochondrial permeability transition (MPT)-driven necrosis, necroptosis, ferroptosis, pyroptosis, parthanatos, entotic cell death, NETotic cell death, lysosome-dependent cell death, autophagy-dependent cell death, immunogenic cell death, cellular senescence, and mitotic catastrophe, we discuss the utility of neologisms that refer to highly specialized instances of these processes. The mission of the NCCD is to provide a widely accepted nomenclature on cell death in support of the continued development of the field.