Autophagy and genomic integrity

Rebalancing redox homeostasis: A pivotal regulator of the cGAS-STING pathway in autoimmune diseases

Autoimmune diseases (ADs) arise from the breakdown of immune tolerance to self-antigens, leading to pathological tissue damage. Proinflammatory cytokine overproduction disrupts redox homeostasis across diverse cell populations, generating oxidative stress that induces DNA damage through multiple mechanisms. Oxidative stress-induced alterations in membrane permeability and DNA damage can lead to the recognition of double-stranded DNA (dsDNA), mitochondrial DNA (mtDNA) and micronuclei-DNA (MN-DNA) by DNA sensors, thereby initiating activation of the cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway. While previous reviews have characterized cGAS-STING activation in autoimmunity, the reciprocal regulation between redox homeostasis and cGAS-STING activation remains insufficiently defined. This narrative review examines oxidative stress-mediated DNA damage as a critical driver of pathological cGAS-STING signaling and delineates molecular mechanisms linking redox homeostasis to autoimmune pathogenesis. Furthermore, we propose therapeutic strategies that combine redox restoration with the attenuation of aberrant cGAS-STING activation, thereby establishing a mechanistic foundation for precision interventions in autoimmune disorders. METHODS: The manuscript is formatted as a narrative review. We conducted a comprehensive search strategy using electronic databases such as PubMed, Google Scholar and Web of Science. Various keywords were used, such as "cGAS-STING," "Redox homeostasis," "Oxidative stress," "pentose phosphate pathway," "Ferroptosis," "mtDNA," "dsDNA," "DNA damage," "Micronuclei," "Reactive oxygen species," "Reactive nitrogen species," "Nanomaterial," "Autoimmune disease," "Systemic lupus erythematosus," "Type 1 diabetes," "Rheumatoid arthritis," "Multiple sclerosis," "Experimental autoimmune encephalomyelitis," "Psoriasis," etc. The titles and abstracts were reviewed for inclusion into this review. After removing duplicates and irrelevant studies, 174 articles met inclusion criteria (original research, English language).

Decoding the dual role of autophagy in cancer through transcriptional and epigenetic regulation

Autophagy is a conserved catabolic process that is essential for maintaining cellular homeostasis by degrading and recycling damaged organelles and misfolded proteins. In cancer, autophagy exhibits a context-dependent dual role: In early stages, autophagy acts as a tumor suppressor by preserving genomic integrity and limiting oxidative stress. In advanced stages, autophagy supports tumor progression by facilitating metabolic adaptation, therapy resistance, immune evasion, and metastasis. This review highlights the molecular mechanisms underlying this dual function and focuses on the transcriptional and epigenetic regulation of autophagy in cancer cells. Key transcription factors, including the MiT/TFE family, FOXO family, and p53, as well as additional regulators, are discussed in the context of stress-responsive pathways mediated by mTORC1 and AMPK. A deeper understanding of the transcriptional and epigenetic regulation of autophagy in cancer is crucial for developing context-specific therapeutic strategies to either promote or inhibit autophagy depending on the cancer stage, thereby improving clinical outcomes in cancer treatment.

DRAM2 inhibits white spot syndrome virus infection via activating autophagy in Penaeus vannamei

The DNA damage-regulated autophagy modulators have been identified as key activators of autophagy, an emerging mechanism to combat viral infections. In this study, we cloned and characterized the DNA damage-regulated autophagy modulator 2 homolog from the shrimp Penaeus vannamei (designated as PvDRAM2) and investigated its potential roles during white spot syndrome virus (WSSV) infection. The predicted three-dimensional structure of PvDRAM2 consists of six β-fold regions, which exhibit conservation with similar structures in other species. Phylogenetic analysis revealed that the clusters of PvDRAM2 evolved alongside invertebrate DRAMs, showing a close relationship with DRAMs from Penaeus japonicus and Homarus americanus. Quantitative real-time PCR (qRT-PCR) analysis indicated that PvDRAM2 is ubiquitously expressed across various shrimp tissues, with significantly increased expression levels in hemocytes and intestines following WSSV challenge. RNA interference (RNAi)-mediated knockdown of PvDRAM2 notably elevated WSSV loads and reduced survival rates in shrimps subjected to WSSV challenge. Functionally, the overexpression of PvDRAM2 enhanced autophagy in High Five cells. Additionally, the application of autophagy activators demonstrated that activating autophagy could counteract the increased WSSV replication precipitated by the knockdown of PvDRAM2. Collectively, our findings suggest that PvDRAM2 may inhibit WSSV infection by activating autophagy.

The Role of A20 in Cancer: Friend or Foe?

A20 is a ubiquitin-editing enzyme that has emerged as a key regulator of inflammatory signaling with paradoxical roles in cancer. Acting as both an oncogene and a tumor suppressor gene depending on the cellular context, A20 modulates important cell pathways, such as NF-κB signaling and autophagy. In this review, we summarize the dual roles of A20 in tumorigenesis, highlighting its ability to promote tumor progression in cancers, such as breast and melanoma, while functioning as a tumor suppressor in lymphomas and hepatocellular carcinoma. We discuss the interplay of A20 with autophagy, a process that is important for maintaining cellular homeostasis and influencing tumor dynamics. By integrating recent findings, we provide insight into how dysregulation of A20 and its associated pathways can either suppress or drive cancer development, which may lead to improved therapeutic intervention.

Autophagy-related protein Atg11 is essential for microtubule-mediated chromosome segregation

Emerging studies hint at the roles of autophagy-related proteins in various cellular processes. To understand if autophagy-related proteins influence genome stability, we sought to examine a cohort of 35 autophagy mutants in Saccharomyces cerevisiae. We observe cells lacking Atg11 show poor mitotic stability of minichromosomes. Single-molecule tracking assays and live cell microscopy reveal that Atg11 molecules dynamically localize to the spindle pole bodies (SPBs) in a microtubule (MT)-dependent manner. Loss of Atg11 leads to a delayed cell cycle progression. Such cells accumulate at metaphase at an elevated temperature that is relieved when the spindle assembly checkpoint (SAC) is inactivated. Indeed, atg11∆ cells have stabilized securin levels, that prevent anaphase onset. Ipl1-mediated activation of SAC also confirms that atg11∆ mutants are defective in chromosome biorientation. Atg11 functions in the Kar9-dependent spindle positioning pathway. Stabilized Clb4 levels in atg11∆ cells suggest that Atg11 maintains Kar9 asymmetry by facilitating proper dynamic instability of astral microtubules (aMTs). Loss of Spc72 asymmetry contributes to non-random SPB inheritance in atg11∆ cells. Overall, this study uncovers an essential non-canonical role of Atg11 in the MT-mediated process of chromosome segregation.

TRIM21-driven K63-linked ubiquitination of RBM38c, as a novel interactor of BECN1, contributes to DNA damage-induced autophagy

Autophagy is essential in DNA damage response by limiting damage, but its responsive activation remains unclear. RBM38 (RBM38a), an RNA-binding protein, regulates mRNA metabolism and plays a key role in controlling cell cycle progression, senescence, and cancer. In this study, we uncovered a novel primate-specific isoform, RBM38c, with 32 extra amino acids from exon 2, which imparts a distinct capacity to promote autophagy upon DNA damage. TP53 increases RBM38c expression upon DNA damage, while TRIM21 facilitates its K63-linked ubiquitination at lysine (K) 35. Activated RBM38c enhances its interaction with BECN1, promoting the formation of the ATG14-containing PtdIns3K-C1 complex and thus autophagy initiation. A K35R mutation or TRIM21 deficiency impairs RBM38c ubiquitination, preventing autophagy activation upon DNA damage. Moreover, RBM38c-driven autophagy protects cells from DNA damage-induced apoptosis and promotes survival, with this beneficial effect susceptible to suppression by the autophagy inhibitor 3-methyladenine. Consequently, depleting RBM38c enhances the efficacy of DNA-damaging drugs by impairing autophagy and increasing DNA damage. Clinical lung cancer samples show a positive correlation between RBM38c expression and LC3 expression, and this correlation is linked to chemotherapy resistance. Together, our study reveals a novel mechanism for DNA damage-induced autophagy, involving K63-linked ubiquitination of RBM38c as a critical interactor with BECN1.

A Truncated Mutation of TP53 Promotes Chemoresistance in Tongue Squamous Cell Carcinoma

Tongue squamous cell carcinoma (TSCC), a subtype of head and neck squamous cell carcinoma, is characterized by frequent chemoresistance. Genetic mutations commonly observed in TSCC play a critical role in malignant progression; thus, elucidating their functional significance is essential for developing effective treatment strategies. To more accurately investigate the relationship between mutations and chemoresistance, we established low-passage TSCC cells, CTSC-1, obtained from a chemoresistant patient, and CTSC-2, from a treatment-naïve patient. Sanger sequencing revealed a specific TP53 mutation (Q331*) in CTSC-1, leading to the loss of the tetramerization and C-terminal regulatory domains. Notably, CTSC-1 cells harboring TP53-Q331* and CTSC-2 cells with TP53 knockout that have been engineered to ectopically express TP53-Q331* exhibit enhanced chemoresistance and increased cancer stem cell-like properties. Mechanistically, TP53-Q331* upregulates the expression of inhibitor of DNA binding 2 (ID2), which is crucial for maintaining the stemness of TSCC cells. Subsequently, ID2 activates the expression of nucleotide excision repair (NER) pathway-related genes ERCC4 and ERCC8, thereby enhancing the chemoresistance in TSCC. In conclusion, our study demonstrates that the TP53-Q331* mutation enhances TSCC chemoresistance through an ID2-mediated NER pathway, providing a potential prognostic marker and therapeutic target for TSCC chemotherapy resistance.

Loss of Fanconi anemia proteins causes a reliance on lysosomal exocytosis

Mutations in the FA pathway lead to a rare genetic disease that increases risk of bone marrow failure, acute myeloid leukemia, and solid tumors. FA patients have a 500 to 800-fold increase in head and neck squamous cell carcinoma compared to the general population and the treatment for these malignancies are ineffective and limited due to the deficiency in DNA damage repair. Using unbiased CRISPR-interference screening, we found the loss of FA function renders cells dependent on key exocytosis genes such as SNAP23. Further investigation revealed that loss of FA pathway function induced deficiencies in lysosomal health, dysregulation of autophagy and increased lysosomal exocytosis. The compromised cellular state caused by the loss of FA genes is accompanied with decreased lysosome abundance and increased lysosomal membrane permeabilization in cells. We found these signatures in vitro across multiple cell types and cell lines and in clinically relevant FA patient cancers. Our findings are the first to connect the FA pathway to lysosomal exocytosis and thus expands our understanding of FA as a disease and of induced dependencies in FA mutant cancers.

The DNA damage response and autophagy during cancer development: an antagonistic pleiotropy entanglement

The DNA damage response (DDR) pathway is a cardinal cellular stress response mechanism that during cancer development follows an antagonistic pleiotropy mode of action. Given that DDR activation is an energy demanding process, interplay with macroautophagy/autophagy, a stress response and energy providing mechanism, is likely to take place. While molecular connections between both mechanisms have been reported, an open question regards whether autophagy activation follows solely or is entangled with DDR in a similar antagonistic pleiotropy pattern during cancer development. Combing evidence on the spatiotemporal relationship of DDR and autophagy in the entire spectrum of carcinogenesis from our previous studies, we discuss these issues in the current addendum.Abbreviation: AMPK: AMP-dependent protein kinase; DDR: DNA damage response.

Zebrafish reveal new roles for Fam83f in hatching and the DNA damage-mediated autophagic response

The FAM83 (Family with sequence similarity 83) family is highly conserved in vertebrates, but little is known of the functions of these proteins beyond their association with oncogenesis. Of the family, FAM83F is of particular interest because it is the only membrane-targeted FAM83 protein. When overexpressed, FAM83F activates the canonical Wnt signalling pathway and binds to and stabilizes p53; it therefore interacts with two pathways often dysregulated in disease. Insights into gene function can often be gained by studying the roles they play during development, and here we report the generation of fam83f knock-out (KO) zebrafish, which we have used to study the role of Fam83f in vivo. We show that endogenous fam83f is most strongly expressed in the hatching gland of developing zebrafish embryos, and that fam83f KO embryos hatch earlier than their wild-type (WT) counterparts, despite developing at a comparable rate. We also demonstrate that fam83f KO embryos are more sensitive to ionizing radiation than WT embryos-an unexpected finding, bearing in mind the previously reported ability of FAM83F to stabilize p53. Transcriptomic analysis shows that loss of fam83f leads to downregulation of phosphatidylinositol-3-phosphate (PI(3)P) binding proteins and impairment of cellular degradation pathways, particularly autophagy, a crucial component of the DNA damage response. Finally, we show that Fam83f protein is itself targeted to the lysosome when overexpressed in HEK293T cells, and that this localization is dependent upon a C' terminal signal sequence. The zebrafish lines we have generated suggest that Fam83f plays an important role in autophagic/lysosomal processes, resulting in dysregulated hatching and increased sensitivity to genotoxic stress in vivo.

GABA(A) Receptor Activation Drives GABARAP-Nix Mediated Autophagy to Radiation-Sensitize Primary and Brain-Metastatic Lung Adenocarcinoma Tumors

In non-small cell lung cancer (NSCLC) treatment, radiotherapy responses are not durable and toxicity limits therapy. We find that AM-101, a synthetic benzodiazepine activator of GABA(A) receptor, impairs the viability and clonogenicity of both primary and brain-metastatic NSCLC cells. Employing a human-relevant ex vivo 'chip', AM-101 is as efficacious as docetaxel, a chemotherapeutic used with radiotherapy for advanced-stage NSCLC. In vivo, AM-101 potentiates radiation, including conferring a significant survival benefit to mice bearing NSCLC intracranial tumors generated using a patient-derived metastatic line. GABA(A) receptor activation stimulates a selective-autophagic response via the multimerization of GABA(A) receptor-associated protein, GABARAP, the stabilization of mitochondrial receptor Nix, and the utilization of ubiquitin-binding protein p62. A high-affinity peptide disrupting Nix binding to GABARAP inhibits AM-101 cytotoxicity. This supports a model of GABA(A) receptor activation driving a GABARAP-Nix multimerization axis that triggers autophagy. In patients receiving radiotherapy, GABA(A) receptor activation may improve tumor control while allowing radiation dose de-intensification to reduce toxicity.

The mechanism of reactive oxygen species generation, DNA damage and apoptosis in hemocytes of Litopenaeus vannamei under ammonia nitrogen exposure

Ammonia-N poses a significant threat to aquatic animals. However, the mechanism of ROS production leading to DNA damage in hemocytes of crustaceans is still unclear. Additionally, the mechanism that cells respond to DNA damage by activating complex signaling networks has not been well studied. Therefore, we exposed shrimp to 0, 2, 10, and 20 mg/L NH4Cl for 0, 3, 6, 12, 24, 48, and 72 h, and explored the alterations in endoplasmic reticulum stress and mitochondrial fission, DNA damage, repair, autophagy and apoptosis. The findings revealed that ammonia exposure led to an increase in plasma ammonia content and neurotransmitter content (DA, 5-HT, ACh), and significant changes in gene expression of PLC and Ca2+ levels. The expression of disulfide bond formation-related genes (PDI, ERO1) and mitochondrial fission-related genes (Drp1, FIS1) were significantly increased, and the unfolded protein response was initiated. Simultaneously, ammonia-N exposure leads to an increase in ROS levels in hemocytes, resulting in DNA damage. DNA repair and autophagy were considerably influenced by ammonia-N exposure, as evidenced by changes in DNA repair and autophagy-related genes in hemocytes. Subsequently, apoptosis was induced by ammonia-N exposure, and this activation was associated with a caspase-dependent pathway and caspase-independent pathway, ultimately leading to a decrease in total hemocytes count. Overall, we hypothesized that neurotransmitters in the plasma of shrimp after ammonia-N exposure bind to receptors on hemocytes membrane, causing endoplasmic reticulum stress through the PLC-IP3R-Ca2+ signaling pathway and leading to mitochondrial fission. Consequently, this process resulted in increased ROS levels, hindered DNA repair, suppressed autophagy, and activated apoptosis. These cascading effects ultimately led to a reduction in total hemocytes count. The present study provides a molecular support for the understanding of the detrimental toxicity of ammonia-N exposure to crustaceans.

Human Aging and Age-Related Diseases: From Underlying Mechanisms to Pro-Longevity Interventions

As human life expectancy continues to rise, becoming a pressing global concern, it brings into focus the underlying mechanisms of aging. The increasing lifespan has led to a growing elderly population grappling with age-related diseases (ARDs), which strains healthcare systems and economies worldwide. While human senescence was once regarded as an immutable and inexorable phenomenon, impervious to interventions, the emerging field of geroscience now offers innovative approaches to aging, holding the promise of extending the period of healthspan in humans. Understanding the intricate links between aging and pathologies is essential in addressing the challenges presented by aging populations. A substantial body of evidence indicates shared mechanisms and pathways contributing to the development and progression of various ARDs. Consequently, novel interventions targeting the intrinsic mechanisms of aging have the potential to delay the onset of diverse pathological conditions, thereby extending healthspan. In this narrative review, we discuss the most promising methods and interventions aimed at modulating aging, which harbor the potential to mitigate ARDs in the future. We also outline the complexity of senescence and review recent empirical evidence to identify rational strategies for promoting healthy aging.

Nanotherapeutics targeting autophagy regulation for improved cancer therapy

The clinical efficacy of current cancer therapies falls short, and there is a pressing demand to integrate new targets with conventional therapies. Autophagy, a highly conserved self-degradation process, has received considerable attention as an emerging therapeutic target for cancer. With the rapid development of nanomedicine, nanomaterials have been widely utilized in cancer therapy due to their unrivaled delivery performance. Hence, considering the potential benefits of integrating autophagy and nanotechnology in cancer therapy, we outline the latest advances in autophagy-based nanotherapeutics. Based on a brief background related to autophagy and nanotherapeutics and their impact on tumor progression, the feasibility of autophagy-based nanotherapeutics for cancer treatment is demonstrated. Further, emerging nanotherapeutics developed to modulate autophagy are reviewed from the perspective of cell signaling pathways, including modulation of the mammalian target of rapamycin (mTOR) pathway, autophagy-related (ATG) and its complex expression, reactive oxygen species (ROS) and mitophagy, interference with autophagosome-lysosome fusion, and inhibition of hypoxia-mediated autophagy. In addition, combination therapies in which nano-autophagy modulation is combined with chemotherapy, phototherapy, and immunotherapy are also described. Finally, the prospects and challenges of autophagy-based nanotherapeutics for efficient cancer treatment are envisioned.

Autophagy suppression in DNA damaged cells occurs through a newly identified p53-proteasome-LC3 axis

Macroautophagy is thought to have a critical role in shaping and refining cellular proteostasis in eukaryotic cells recovering from DNA damage. Here, we report a mechanism by which autophagy is suppressed in cells exposed to bacterial toxin-, chemical-, or radiation-mediated sources of genotoxicity. Autophagy suppression is directly linked to cellular responses to DNA damage, and specifically the stabilization of the tumor suppressor p53, which is both required and sufficient for regulating the ubiquitination and proteasome-dependent reduction in cellular pools of microtubule-associated protein 1 light chain 3 (LC3A/B), a key precursor of autophagosome biogenesis and maturation, in both epithelial cells and an ex vivo organoid model. Our data indicate that suppression of autophagy, through a newly identified p53-proteasome-LC3 axis, is a conserved cellular response to multiple sources of genotoxicity. Such a mechanism could potentially be important for realigning proteostasis in cells undergoing DNA damage repair.

LC3B drives transcription-associated homologous recombination via direct interaction with R-loops

Exploring the connection between ubiquitin-like modifiers (ULMs) and the DNA damage response (DDR), we employed several advanced DNA damage and repair assay techniques and identified a crucial role for LC3B. Notably, its RNA recognition motif (RRM) plays a pivotal role in the context of transcription-associated homologous recombination (HR) repair (TA-HRR), a particular subset of HRR pathways. Surprisingly, independent of autophagy flux, LC3B interacts directly with R-loops at DNA lesions within transcriptionally active sites via its RRM, promoting TA-HRR. Using native RNA immunoprecipitation (nRIP) coupled with high-throughput sequencing (nRIP-seq), we discovered that LC3B also directly interacts with the 3'UTR AU-rich elements (AREs) of BRCA1 via its RRM, influencing its stability. This suggests that LC3B regulates TA-HRR both proximal to and distal from DNA lesions. Data from our LC3B depletion experiments showed that LC3B knockdown disrupts end-resection for TA-HRR, redirecting it towards the non-homologous end joining (NHEJ) pathway and leading to chromosomal instability, as evidenced by alterations in sister chromatid exchange (SCE) and interchromosomal fusion (ICF). Thus, our findings unveil autophagy-independent functions of LC3B in DNA damage and repair pathways, highlighting its importance. This could reshape our understanding of TA-HRR and the interaction between autophagy and DDR.

UBC9-mediated SUMOylation of Lamin B1 enhances DNA-damage-induced nuclear DNA leakage and autophagy after spinal cord injury

Recent studies have shown that nucleophagy can mitigate DNA damage by selectively degrading nuclear components protruding from the nucleus. However, little is known about the role of nucleophagy in neurons after spinal cord injury (SCI). Western blot analysis and immunofluorescence were performed to evaluate the nucleophagy after nuclear DNA damage and leakage in SCI neurons in vivo and NSC34 expression in primary neurons cultured with oxygen-glucose deprivation (OGD) in vitro, as well as the interaction and colocalization of autophagy protein LC3 with nuclear lamina protein Lamin B1. The effect of UBC9, a Small ubiquitin-related modifier (SUMO) E2 ligase, on Lamin B1 SUMOylation and nucleophagy was examined by siRNA transfection or 2-D08 (a small-molecule inhibitor of UBC9), immunoprecipitation, and immunofluorescence. In SCI and OGD injured NSC34 or primary cultured neurons, neuronal nuclear DNA damage induced the SUMOylation of Lamin B1, which was required by the nuclear Lamina accumulation of UBC9. Furthermore, LC3/Atg8, an autophagy-related protein, directly bound to SUMOylated Lamin B1, and delivered Lamin B1 to the lysosome. Knockdown or suppression of UBC9 with siRNA or 2-D08 inhibited SUMOylation of Lamin B1 and subsequent nucleophagy and protected against neuronal death. Upon neuronal DNA damage and leakage after SCI, SUMOylation of Lamin B1 is induced by nuclear Lamina accumulation of UBC9. Furthermore, it promotes LC3-Lamin B1 interaction to trigger nucleophagy that protects against neuronal DNA damage.

USP24-i-101 targeting of USP24 activates autophagy to inhibit drug resistance acquired during cancer therapy

Drug resistance in cancer therapy is the major reason for poor prognosis. Addressing this clinically unmet issue is important and urgent. In this study, we found that targeting USP24 by the specific USP24 inhibitors, USP24-i and its analogues, dramatically activated autophagy in the interphase and mitotic periods of lung cancer cells by inhibiting E2F4 and TRAF6, respectively. USP24 functional knockout, USP24C1695A, or targeting USP24 by USP24-i-101 inhibited drug resistance and activated autophagy in gefitinib-induced drug-resistant mice with doxycycline-induced EGFRL858R lung cancer, but this effect was abolished after inhibition of autophagy, indicating that targeting USP24-mediated induction of autophagy is required for inhibition of drug resistance. Genomic instability and PD-L1 levels were increased in drug resistant lung cancer cells and were inhibited by USP24-i-101 treatment or knockdown of USP24. In addition, inhibition of autophagy by bafilomycin-A1 significantly abolished the effect of USP24-i-101 on maintaining genomic integrity, decreasing PD-L1 and inhibiting drug resistance acquired in chemotherapy or targeted therapy. In summary, an increase in the expression of USP24 in cancer cells is beneficial for the induction of drug resistance and targeting USP24 by USP24-i-101 optimized from USP24-i inhibits drug resistance acquired during cancer therapy by increasing PD-L1 protein degradation and genomic stability in an autophagy induction-dependent manner.

Autophagy and nuclear morphometry are associated with histopathologic features in esophageal squamous cell carcinoma

Less than 15% of patients with esophageal squamous cell carcinoma (ESCC) survive 5 years after diagnosis. A better understanding of the biology of these tumors and the development of clinical biomarkers is needed. Autophagy is a physiological mechanism involved in the turnover of cellular components that plays a key role in cancer. This study evaluated the differential levels of three key regulators of autophagy (SQSTM1, MAP1LC3B, and BECN1) in patients with ESCC, associating autophagy with histopathologic features, including the grade of differentiation, mitotic rate, inflammation score, and the intensity of tumor-infiltrating lymphocytes. Nuclear morphometry of the tumor parenchyma was also assessed, associating it with autophagy and histopathology. All three markers significantly increased in patients with ESCC compared to the control group. Based on the mean expression of each protein in the control group, 57% of patients with ESCC had high levels of all three markers compared to control patients (14%). The most frequent profiles found in ESCC were BECNhigh/MAP1LC3high and BECNhigh/SQSTM1high. According to the TCGA database, we found that the main autophagy genes were upregulated in ESCC. Moreover, high levels of autophagy markers were associated with a poor prognosis. Considering nuclear morphometry, ESCC samples showed a significant reduction in nuclear area, which was strongly negatively correlated with autophagy. Finally, the percentage of normal nuclei was associated with tumor differentiation, while poorly differentiated tumors showed lower SQSTM1 levels. ESCC progression may involve increased autophagy and changes in nuclear structure, associated with clinically relevant histopathological features. KEY MESSAGES: Autophagy markers are co-increased in primary ESCC. Autophagy negatively correlates with nuclear morphometry in ESCC parenchyma. Autophagy and nuclear morphometry are associated with histopathological features. Autophagy is increased in ESCC-TCGA database and associated with poor prognosis.

Temporal Dynamic Regulation of Autophagy and Senescence Induction in Response to Radiation Exposure

Autophagy and senescence are closely related cellular responses to genotoxic stress, and play significant roles in the execution of cellular responses to radiation exposure. However, little is known about their interplay in the fate-decision of cells receiving lethal doses of radiation. Here, we report that autophagy precedes the establishment of premature senescence in normal human fibroblasts exposed to lethal doses of radiation. Activation of the p53-dependent DNA damage response caused sustained dephosphorylation of RB proteins and consequent cell cycle arrest, concurrently with Ulk1 dephosphorylation at Ser638 by PPM1D, which promoted autophagy induction 1-2 days after irradiation. In addition, mitochondrial fragmentation became obvious 1-2 days after irradiation, and autophagy was further enhanced. However, Ulk1 levels decreased significantly after 2 days, resulting in lower LC3-II levels. An autophagic flux assay using chloroquine (CQ) also revealed that the flux in irradiated cells gradually decreased over 30 days. In contrast, lysosomal augmentation started at 1 day, became significantly upregulated after 5 days, and continued for over 30 days. After a rapid decrease in autophagy, p16 expression increased and senescence was established, but autophagic activity remained reduced. These results demonstrated that X-ray irradiation triggered two processes, autophagy and senescence, with the former being temporary and regulated by DNA damage response and mitophagy, and the latter being sustained and regulated by persistent cell cycle arrest. The interplay between autophagy and senescence seems to be essential for the proper implementation of the cellular response to radiation exposure.

NeuroD1-GPX4 signaling leads to ferroptosis resistance in hepatocellular carcinoma

Cell death resistance is a hallmark of tumor cells that drives tumorigenesis and drug resistance. Targeting cell death resistance-related genes to sensitize tumor cells and decrease their cell death threshold has attracted attention as a potential antitumor therapeutic strategy. However, the underlying mechanism is not fully understood. Recent studies have reported that NeuroD1, first discovered as a neurodifferentiation factor, is upregulated in various tumor cells and plays a crucial role in tumorigenesis. However, its involvement in tumor cell death resistance remains unknown. Here, we found that NeuroD1 was highly expressed in hepatocellular carcinoma (HCC) cells and was associated with tumor cell death resistance. We revealed that NeuroD1 enhanced HCC cell resistance to ferroptosis, a type of cell death caused by aberrant redox homeostasis that induces lipid peroxide accumulation, leading to increased HCC cell viability. NeuroD1 binds to the promoter of glutathione peroxidase 4 (GPX4), a key reductant that suppresses ferroptosis by reducing lipid peroxide, and activates its transcriptional activity, resulting in decreased lipid peroxide and ferroptosis. Subsequently, we showed that NeuroD1/GPX4-mediated ferroptosis resistance was crucial for HCC cell tumorigenic potential. These findings not only identify NeuroD1 as a regulator of tumor cell ferroptosis resistance but also reveal a novel molecular mechanism underlying the oncogenic function of NeuroD1. Furthermore, our findings suggest the potential of targeting NeuroD1 in antitumor therapy.

Cytotoxic n-Hexane Fraction of the Egyptian Pteris vittata Functions as Anti-breast Cancer Through Coordinated Actions on Apoptotic and Autophagic Pathways

We investigated the possible anticancer mechanisms of Pteris vittata [PV] n-hexane extract on MCF-7 [breast cancer cell line]. Cultured cell lines were treated with various concentrations of this extract ± Baf-A1 [autophagic inhibitor]. Cells' viability, apoptotic markers [caspase-7, Bax, and Bcl-2], autophagic markers [light chain 3 [LC-3] and P62/SQSTM1]], and the tumor suppressor P53 and its mRNA were checked by their corresponding methods. Treated cell lines showed significant concentration and time-dependent reductions in cell viability in response to PV-n-hexane extract and also exhibited a concomitant induction of apoptosis [increased chromatin condensation, nuclear fragmentation, and pro-apoptotic Bax, and cleaved caspase-7 levels while decreased Bcl-2 levels] and autophagy [increased autophagosomes vacuoles, and LC3B II levels while decreased P62/SQSTM1 levels]. Moreover, PV-n-hexane extract-treated cells showed significant increases in the P53 and its mRNA levels. The addition of Baf-A1 reversed the PV-n-hexane extract autophagic effects and increased apoptotic cell percentage with a much increase in the cleaved caspase-7 and P53 protein and its mRNA levels. We concluded that the PV-n-hexane extract exhibits cytotoxic effects on the MCF-7 cell line with significant reductions in cell viability and concomitant autophagy and apoptosis induction. Inhibition of autophagy in the PV-treated MCF-7 cells enhances apoptosis via a p35-dependent pathway.

A new vulnerability to BET inhibition due to enhanced autophagy in BRCA2 deficient pancreatic cancer

Pancreatic cancer is one of the deadliest diseases in human malignancies. Among total pancreatic cancer patients, ~10% of patients are categorized as familial pancreatic cancer (FPC) patients, carrying germline mutations of the genes involved in DNA repair pathways (e.g., BRCA2). Personalized medicine approaches tailored toward patients' mutations would improve patients' outcome. To identify novel vulnerabilities of BRCA2-deficient pancreatic cancer, we generated isogenic Brca2-deficient murine pancreatic cancer cell lines and performed high-throughput drug screens. High-throughput drug screening revealed that Brca2-deficient cells are sensitive to Bromodomain and Extraterminal Motif (BET) inhibitors, suggesting that BET inhibition might be a potential therapeutic approach. We found that BRCA2 deficiency increased autophagic flux, which was further enhanced by BET inhibition in Brca2-deficient pancreatic cancer cells, resulting in autophagy-dependent cell death. Our data suggests that BET inhibition can be a novel therapeutic strategy for BRCA2-deficient pancreatic cancer.

CDKL3 Promotes Non-small Cell Lung Cancer by Suppressing Autophagy Via Activation of PI3K/Akt/mTOR Pathway

This study aimed to assess the role of cyclin-dependent kinase-like 3 (CDKL3) in the progression of non-small cell lung cancer (NSCLC) as well as the underlying mechanisms. Western blot and qRT-PCR were utilized to analyze CDKL3 expression in 30 pairs of NSCLC and paraneoplastic tissues. A549 cells with CDKL3 knockdown and PC9 cells with CDKL3 overexpression were constructed by infecting cells with lentiviruses expressing shRNA of CDKL3 and expressing a full-length CDKL3 mRNA, respectively. The CCK-8 assay, flow cytometry, wound healing assay, and Transwell assay were carried out to detect cell viability, apoptosis, migration, and invasion, respectively. Autophagosome morphology was observed by electron microscopy experiments, the expression of key components of the PI3K/Akt/mTOR pathway was examined via Western blot and their mRNA expression levels were determined. Besides, the stably infected NSCLC cells with reduced expression or overexpression of CDKL3 were inoculated into the right-back flank of mice to generate tumors. The results showed that CDKL3 expression was dramatically increased in NSCLC tissues. Moreover, CDKL3 promoted the viability and migration of NSCLC cells by suppressing autophagy in vitro and in vivo. In addition, CDKL3 might modulate PI3K/Akt/mTOR signaling in NSCLC. Overall, CDKL3 might promote NSCLC cell viability and metastasis by inhibiting autophagy and activating the PI3K/Akt/mTOR signaling pathway.

Relating aging and autophagy: a new perspective towards the welfare of human health

The most common factor that contributes to aging is the loss of proteostasis, resulting in an excess amount of non-functional/damaged proteins. These proteins lead to various age-associated phenotypes such as cellular senescence and dysfunction in the nutrient-sensing pathways. Despite the various factors that can contribute to aging, it is still a process that can be changed. According to recent advances in the field of biology, the ability to alter the pathways that are involved in aging can improve the lifespan of a person. Autophagy is a process that helps in preserving survival during stressful situations, such as starvation. It is a common component of various anti-aging interventions, including those that target the insulin/IGF-1 and rapamycin signaling pathways. It has been shown that altered autophagy is a common feature of old age and its impaired regulation could have significant effects on the aging process. This review aims to look into the role of autophagy in aging and how it can be used to improve one's health.

Inhibition of autophagy; an opportunity for the treatment of cancer resistance

The process of macroautophagy plays a pivotal role in the degradation of long-lived, superfluous, and damaged proteins and organelles, which are later recycled for cellular use. Normal cells rely on autophagy to combat various stressors and insults to ensure survival. However, autophagy is often upregulated in cancer cells, promoting a more aggressive phenotype that allows mutated cells to evade death after exposure to therapeutic treatments. As a result, autophagy has emerged as a significant factor in therapeutic resistance across many cancer types, with underlying mechanisms such as DNA damage, cell cycle arrest, and immune evasion. This review provides a comprehensive summary of the role of autophagy in therapeutic resistance and the limitations of available autophagic inhibitors in cancer treatment. It also highlights the urgent need to explore new inhibitors that can synergize with existing therapies to achieve better patient treatment outcomes. Advancing research in this field is crucial for developing more effective treatments that can help improve the lives of cancer patients.

A new vulnerability to BET inhibition due to enhanced autophagy in BRCA2 deficient pancreatic cancer

Pancreatic cancer is one of the deadliest diseases in human malignancies. Among total pancreatic cancer patients, ∼10% of patients are categorized as familial pancreatic cancer (FPC) patients, carrying germline mutations of the genes involved in DNA repair pathways ( e.g., BRCA2 ). Personalized medicine approaches tailored toward patients' mutations would improve patients' outcome. To identify novel vulnerabilities of BRCA2 -deficient pancreatic cancer, we generated isogenic Brca2 -deficient murine pancreatic cancer cell lines and performed high-throughput drug screens. High-throughput drug screening revealed that Brca2 -deficient cells are sensitive to Bromodomain and Extraterminal Motif (BET) inhibitors, suggesting that BET inhibition might be a potential therapeutic approach. We found that BRCA2 deficiency increased autophagic flux, which was further enhanced by BET inhibition in Brca2 -deficient pancreatic cancer cells, resulting in autophagy-dependent cell death. Our data suggests that BET inhibition can be a novel therapeutic strategy for BRCA2 -deficient pancreatic cancer.

Palliative Role of Zamzam Water against Cyclosporine-Induced Nephrotoxicity through Modulating Autophagy and Apoptosis Crosstalk

Cyclosporine (CsA) is considered one of the main components of treatment protocols for organ transplantation owing to its immunosuppressive effect. However, its use is very restricted due to its nephrotoxic effect. ZW is an alkaline fluid rich in various trace elements and has a great ability to stimulate antioxidant processes. This study aimed to investigate the possible mitigating effect of ZW on CsA-induced nephrotoxicity and its underlying mechanisms. Forty rats were allocated into four groups (n = 10): a control group, ZW group, cyclosporine A group (injected subcutaneously (SC) with CsA (20 mg/kg/day)), and cyclosporine A+ Zamzam water group (administered CsA (SC) and ZW as their only drinking water (100 mL/cage/day) for 21 days). Exposure to CsA significantly (p < 0.001) increased the serum creatinine level, lipid peroxidation marker level (malondialdehyde; MDA), and the expression of apoptotic markers procaspase-8, caspase-8, caspase- 9, calpain, cytochrome c, caspas-3, P62, and mTOR in renal tissues. Meanwhile, it markedly decreased (p< 0.001) the autophagic markers (AMPK, ULK-I, ATag5, LC3, and Beclin-1), antiapoptotic Bcl-2, and antioxidant enzymes. Moreover, the administration of CsA caused histological alterations in renal tissues. ZW significantly (p < 0.001) reversed all the changes caused by CsA and conclusively achieved a positive outcome in restraining CsA-induced nephrotoxicity, as indicated by the restoration of the histological architecture, improvement of renal function, inhibition of apoptosis, and enhancement of autophagy via the AMPK/mTOR pathway.

cGAS-STING signalling in cancer: striking a balance with chromosomal instability

Chromosomal instability (CIN) is a hallmark of cancer that drives tumour evolution. It is now recognised that CIN in cancer leads to the constitutive production of misplaced DNA in the form of micronuclei and chromatin bridges. These structures are detected by the nucleic acid sensor cGAS, leading to the production of the second messenger 2'3'-cGAMP and activation of the critical hub of innate immune signalling STING. Activation of this immune pathway should instigate the influx and activation of immune cells, resulting in the eradication of cancer cells. That this does not universally occur in the context of CIN remains an unanswered paradox in cancer. Instead, CIN-high cancers are notably adept at immune evasion and are highly metastatic with typically poor outcomes. In this review, we discuss the diverse facets of the cGAS-STING signalling pathway, including emerging roles in homeostatic processes and their intersection with genome stability regulation, its role as a driver of chronic pro-tumour inflammation, and crosstalk with the tumour microenvironment, which may collectively underlie its apparent maintenance in cancers. A better understanding of the mechanisms whereby this immune surveillance pathway is commandeered by chromosomally unstable cancers is critical to the identification of new vulnerabilities for therapeutic exploitation.

AKG induces cell apoptosis by inducing reactive oxygen species-mediated endoplasmic reticulum stress and by suppressing PI3K/AKT/mTOR-mediated autophagy in renal cell carcinoma

BACKGROUND

Alpha-ketoglutarate (AKG) or 2-oxoglutarate is a key substance in the tricarboxylic acid cycle (TCA) and has been known to play an important role in cancerogenesis and tumor progression. Renal cell carcinoma (RCC) is the most common type of kidney cancer, and it has a high mortality rate. Autophagy is a phenomenon of self-digestion, and its significance in tumor genesis and progression remains debatable. However, the mechanisms underlying how AKG regulates autophagy in RCC remain unknown. Thus, the purpose of this study was to assess the therapeutic efficacy of AKG and its molecular mechanisms.

METHODS

RCC cell lines 786O and ACHN were treated with varying doses of AKG for 24 h. CCK-8, Transwell, and scratch wound healing assays were utilized to evaluate the role of AKG in RCC cells. Autophagy protein and PI3K/AKT/mTOR pathway protein levels were analyzed by Western blot.

RESULTS

AKG inhibited the proliferation of RCC cells 786O and ACHN in a dose-dependent manner according to the CCK-8 assay. In addition, flow cytometry and Western blot analysis revealed that AKG dose-dependently triggered apoptosis and autophagy in RCC cells. By promoting cell apoptosis and autophagy, AKG dramatically suppressed tumor growth. Mechanistically, AKG induces autophagy by promoting ROS generation and inhibiting the PI3K/AKT/mTOR pathway.

CONCLUSIONS

The anti-tumor effect of AKG promotes autophagy in renal cancer cells via mediating ROS-PI3K/Akt/mTOR, and may be used as a potential anticancer drug for kidney cancer.

P2Y12 receptor antagonism inhibits proliferation, migration and leads to autophagy of glioblastoma cells

Glioblastoma (GBM) is the most aggressive and lethal among the primary brain tumors, with a low survival rate and resistance to radio and chemotherapy. The P2Y₁₂ is an adenosine diphosphate (ADP) purinergic chemoreceptor, found mainly in platelets. In cancer cells, its activation has been described to induce proliferation and metastasis. Bearing in mind the need to find new treatments for GBM, this study aimed to investigate the role of the P2Y₁₂R in the proliferation and migration of GBM cells, as well as to evaluate the expression of this receptor in patients' data obtained from the TCGA data bank. Here, we used the P2Y₁₂R antagonist, ticagrelor, which belongs to the antiplatelet agent's class. The different GBM cells (cell line and patient-derived cells) were treated with ticagrelor, with the agonist, ADP, or both, and the effects on cell proliferation, colony formation, ADP hydrolysis, cell cycle and death, migration, and cell adhesion were analyzed. The results showed that ticagrelor decreased the viability and the proliferation of GBM cells. P2Y₁₂R antagonism also reduced colony formation and migration potentials, with alterations on the expression of metalloproteinases, and induced autophagy in GBM cells. Changes were observed at the cell cycle level, and only the U251 cell line showed a significant reduction in the ADP hydrolysis profile. TCGA data analysis showed a higher expression of P2Y₁₂R in gliomas samples when compared to the other tumors. These data demonstrate the importance of the P2Y₁₂ receptor in gliomas development and reinforce its potential as a pharmacological target for glioma treatment.

Potential bioactivity of Phoenix dactylifera fruits, leaves, and seeds against prostate and pancreatic cancer cells

The use of functional foods' phytochemicals in the chemoprevention of different cancer diseases has become one of the hot scientific areas in the clinical nutrition field. For instance, the Khalas palm cultivar (KPC; Phoenix dactylifera) is one of the natural sustainable resources that have high bioactivity and functionality. This study aimed to investigate the antiproliferative activity and mode of action of KPC's different parts on prostate (Pc3) and pancreatic (panc1) cancer cells at a molecular level. In the methods, KPC's leaves, seeds, and fruits' chemical composition and phytochemical analysis were analyzed. Also, the cytotoxic effects of each extract were assessed against pc3 and panc1 cell lines. Besides, induction of apoptosis, cell cycle analysis, and gene expression of both Cap3 and Cap9 were studied. The obtained results indicated that KPC leaves extract exhibited the highest significant (P < 0.01) anti-proliferation activity against the utilized cancer cell lines compared to fruits and seeds extracts. Also, there were significant (P < 0.05) differences in the phenolic contents, flavonoid of compounds, and antioxidant power of the leaves when compared to the seeds and fruits. Additionally, the highest cytotoxic effect (lowest IC50) was recorded with leave extract than seeds and fruits. Meanwhile, the seeds extract induced (P < 0.05) the apoptosis and arrested cells in the G2/M phase as well as up-regulated the gene expression of the apoptotic-related genes (Casp3 and Casp9) compared to the control group. In conclusion, this study showed that the presence of bioactive components in the KPC different parts extracts have the significant ability to induce the apoptotic pathway that could down-regulate the proliferation of prostate (pc3) and pancreatic (panc1) cancer cells. The pathway mechanism of action was induced by the phytol molecule presented in its leaves extract.

Macrophage autophagy in macrophage polarization, chronic inflammation and organ fibrosis

As the essential regulators of organ fibrosis, macrophages undergo marked phenotypic and functional changes after organ injury. These changes in macrophage phenotype and function can result in maladaptive repair, causing chronic inflammation and the development of pathological fibrosis. Autophagy, a highly conserved lysosomal degradation pathway, is one of the major players to maintain the homeostasis of macrophages through clearing protein aggregates, damaged organelles, and invading pathogens. Emerging evidence has shown that macrophage autophagy plays an essential role in macrophage polarization, chronic inflammation, and organ fibrosis. Because of the high heterogeneity of macrophages in different organs, different macrophage types may play different roles in organ fibrosis. Here, we review the current understanding of the function of macrophage autophagy in macrophage polarization, chronic inflammation, and organ fibrosis in different organs, highlight the potential role of macrophage autophagy in the treatment of fibrosis. Finally, the important unresolved issues in this field are briefly discussed. A better understanding of the mechanisms that macrophage autophagy in macrophage polarization, chronic inflammation, and organ fibrosis may contribute to developing novel therapies for chronic inflammatory diseases and organ fibrosis.

Mxc, a Drosophila homolog of mental retardation-associated gene NPAT, maintains neural stem cell fate

BACKGROUND

Mental retardation is a complex neurodevelopmental disorder. NPAT, a component of the histone locus body (HLB), has been implicated as a candidate gene for mental retardation, with a mechanism yet to be elucidated.

RESULTS

We identified that mxc, the Drosophila ortholog of NPAT, is required for the development of nervous system. Knockdown of mxc resulted in a massive loss of neurons and locomotion dysfunction in adult flies. In the mxc mutant or RNAi knockdown larval brains, the neuroblast (NB, also known as neural stem cell) cell fate is prematurely terminated and its proliferation potential is impeded concurrent with the blocking of the differentiation process of ganglion mother cells (GMCs). A reduction of transcription levels of histone genes was shown in mxc knockdown larval brains, accompanied by DNA double-strand breaks (DSBs). The subsidence of histone transcription levels leads to prematurely termination of NB cell fate and blockage of the GMC differentiation process. Our data also show that the increase in autophagy induced by mxc knockdown in NBs could be a defense mechanism in response to abnormal HLB assembly and premature termination of NB cell fate.

CONCLUSIONS

Our study demonstrate that Mxc plays a critical role in maintaining neural stem cell fate and GMC differentiation in the Drosophila larval brain. This discovery may shed light on the understanding of the pathogenesis of NPAT-related mental retardation in humans.

Tight association of autophagy and cell cycle in leukemia cells

Background

Autophagy plays an essential role in maintaining cellular homeostasis and in the response to cellular stress. Autophagy is also involved in cell cycle progression, yet the relationship between these processes is not clearly defined.

Results

In exploring this relationship, we observed that the inhibition of autophagy impaired the G2/M phase-arresting activity of etoposide but enhanced the G1 phase-arresting activity of palbociclib. We further investigated the connection of basal autophagy and cell cycle by utilizing the autophagosome tracer dye Cyto-ID in two ways. First, we established a double-labeling flow-cytometric procedure with Cyto-ID and the DNA probe DRAQ5, permitting the cell cycle phase-specific determination of autophagy in live cells. This approach demonstrated that different cell cycle phases were associated with different autophagy levels: G1-phase cells had the lowest level, and G2/M-phase cells had the highest one. Second, we developed a flow-cytometric cell-sorting procedure based on Cyto-ID that separates cell populations into fractions with low, medium, and high autophagy. Cell cycle analysis of Cyto-ID-sorted cells confirmed that the high-autophagy fraction contained a much higher percentage of G2/M-phase cells than the low-autophagy fraction. In addition, Cyto-ID-based cell sorting also proved to be useful for assessing other autophagy-related processes: extracellular flux analysis revealed metabolic differences between the cell populations, with higher autophagy being associated with higher respiration, higher mitochondrial ATP production, and higher glycolysis.

Conclusion

This work provides clear evidence of high autophagy in G2/M-phase cells by establishing a novel cell sorting technique based on Cyto-ID.

Supplementary Information

The online version contains supplementary material available at 10.1186/s11658-022-00334-8.

PPARγ regulates the expression of genes involved in the DNA damage response in an inflamed endometrium

Inflammation is a biological response of the immune system, which can be triggered by many factors, including pathogens. These factors may induce acute or chronic inflammation in various organs, including the reproductive system, leading to tissue damage or disease. In this study, the RNA-Seq technique was used to determine the in vitro effects of peroxisome proliferator-activated receptor gamma (PPARγ) ligands on the expression of genes and long non-coding RNA, and alternative splicing events (ASEs) in LPS-induced inflammation of the porcine endometrium during the follicular phase of the estrous cycle. Endometrial slices were incubated in the presence of LPS and PPARγ agonists (PGJ2 or pioglitazone) and a PPARγ antagonist (T0070907). We identified 169, 200, 599 and 557 differentially expressed genes after LPS, PGJ2, pioglitazone or T0070907 treatment, respectively. Moreover, changes in differentially expressed long non-coding RNA and differential alternative splicing events were described after the treatments. The study revealed that PPARγ ligands influence the LPS-triggered expression of genes controlling the DNA damage response (GADD45β, CDK1, CCNA1, CCNG1, ATM). Pioglitazone treatment exerted a considerable effect on the expression of genes regulating the DNA damage response.

3,3'-Diindolylmethane induces apoptosis and autophagy in fission yeast

3,3'-Diindolylmethane (DIM) is a compound derived from the digestion of indole-3-carbinol, found in the broccoli family. It induces apoptosis and autophagy in some types of human cancer. DIM extends lifespan in the fission yeast Schizosaccharomyces pombe. The mechanisms by which DIM induces apoptosis and autophagy in humans and expands lifespan in fission yeasts are not fully understood. Here, we show that DIM induces apoptosis and autophagy in log-phase cells, which is dose-dependent in fission yeast. A high concentration of DIM disrupted the nuclear envelope (NE) structure and induced chromosome condensation at an early time point. In contrast, a low concentration of DIM induced autophagy but did not disrupt NE structure. The mutant defective in autophagy was more sensitive to a low concentration of DIM, demonstrating that the autophagic pathway contributes to the survival of cells against DIM. Moreover, our results showed that the lem2 mutant is more sensitive to DIM. NE in the lem2 mutant was disrupted even at the low concentration of DIM. Our results demonstrate that the autophagic pathway and NE integrity are important to maintain viability in the presence of a low concentration of DIM. The mechanism of apoptosis and autophagy induction by DIM might be conserved in fission yeast and humans. Further studies will contribute to the understanding of the mechanism of apoptosis and autophagy by DIM in fission yeast and humans.

Over Fifty Years of Life, Death, and Cannibalism: A Historical Recollection of Apoptosis and Autophagy

Research in biomedical sciences has changed dramatically over the past fifty years. There is no doubt that the discovery of apoptosis and autophagy as two highly synchronized and regulated mechanisms in cellular homeostasis are among the most important discoveries in these decades. Along with the advancement in molecular biology, identifying the genetic players in apoptosis and autophagy has shed light on our understanding of their function in physiological and pathological conditions. In this review, we first describe the history of key discoveries in apoptosis with a molecular insight and continue with apoptosis pathways and their regulation. We touch upon the role of apoptosis in human health and its malfunction in several diseases. We discuss the path to the morphological and molecular discovery of autophagy. Moreover, we dive deep into the precise regulation of autophagy and recent findings from basic research to clinical applications of autophagy modulation in human health and illnesses and the available therapies for many diseases caused by impaired autophagy. We conclude with the exciting crosstalk between apoptosis and autophagy, from the early discoveries to recent findings.

Autophagy and Aging: Roles in Skeletal Muscle, Eye, Brain and Hepatic Tissue

Autophagy is an evolutionary conserved degradative process contributing to cytoplasm quality control, metabolic recycling and cell defense. Aging is a universal phenomenon characterized by the progressive accumulation of impaired molecular and reduced turnover of cellular components. Recent evidence suggests a unique role for autophagy in aging and age-related disease. Indeed, autophagic activity declines with age and enhanced autophagy may prevent the progression of many age-related diseases and prolong life span. All tissues experience changes during aging, while the role of autophagy in different tissues varies. This review summarizes the links between autophagy and aging in the whole organism and discusses the physiological and pathological roles of autophagy in the aging process in tissues such as skeletal muscle, eye, brain, and liver.

Mechanism of interaction between autophagy and apoptosis in cancer

The mechanisms of two programmed cell death pathways, autophagy, and apoptosis, are extensively focused areas of research in the context of cancer. Both the catabolic pathways play a significant role in maintaining cellular as well as organismal homeostasis. Autophagy facilitates this by degradation and elimination of misfolded proteins and damaged organelles, while apoptosis induces canonical cell death in response to various stimuli. Ideally, both autophagy and apoptosis have a role in tumor suppression, as autophagy helps in eliminating the tumor cells, and apoptosis prevents their survival. However, as cancer proceeds, autophagy exhibits a dual role by enhancing cancer cell survival in response to stress conditions like hypoxia, thereby promoting chemoresistance to the tumor cells. Thus, any inadequacy in either of their levels can lead to tumor progression. A complex array of biomarkers is involved in maintaining coordination between the two by acting as either positive or negative regulators of one or both of these pathways of cell death. The resulting crosstalk between the two and its role in influencing the survival or death of malignant cells makes it quintessential, among other challenges facing chemotherapeutic treatment of cancer. In view of this, the present review aims to highlight some of the factors involved in maintaining their diaphony and stresses the importance of inhibition of cytoprotective autophagy and deletion of the intermediate pathways involved to facilitate tumor cell death. This will pave the way for future prospects in designing drug combinations facilitating the synergistic effect of autophagy and apoptosis in achieving cancer cell death.

Pharmacological Activation of Autophagy Restores Cellular Homeostasis in Ultraviolet-(B)-Induced Skin Photodamage

Ultraviolet (UV) exposure to the skin causes photo-damage and acts as the primary etiological agent in photo-carcinogenesis. UV-B exposure induces cellular damage and is the major factor challenging skin homeostasis. Autophagy allows the fundamental adaptation of cells to metabolic and oxidative stress. Cellular dysfunction has been observed in aged tissues and in toxic insults to cells undergoing stress. Conversely, promising anti-aging strategies aimed at inhibiting the mTOR pathway have been found to significantly improve the aging-related disorders. Recently, autophagy has been found to positively regulate skin homeostasis by enhancing DNA damage recognition. Here, we investigated the geno-protective roles of autophagy in UV-B-exposed primary human dermal fibroblasts (HDFs). We found that UV-B irradiation to HDFs impairs the autophagy response in a time- and intensity-independent manner. However, improving autophagy levels in HDFs with pharmacological activators regulates the UV-B-induced cellular stress by decreasing the induction of DNA photo-adducts, promoting the DNA repair process, alleviating oxidative and ER stress responses, and regulating the expression levels of key cell cycle regulatory proteins. Autophagy also prevents HDFs from UV-B-induced nuclear damage as is evident in TUNEL assay and Acridine Orange/Ethidium Bromide co-staining. Salubrinal (an eIF2α phosphatase inhibitor) relieves ER stress response in cells and also significantly alleviates DNA damage and promotes the repair process in UV-B-exposed HDFs. P62-silenced HDFs show enhanced DNA damage response and also disturb the tumor suppressor PTEN/pAKT signaling axis in UV-B-exposed HDFs whereas Atg7-silenced HDFs reveal an unexpected consequence by decreasing the UV-B-induced DNA damage. Taken together, these results suggest that interventional autophagy offers significant protection against UV-B radiation-induced photo-damage and holds great promise in devising it as a suitable therapeutic strategy against skin pathological disorders.

Targeting autophagy reverses de novo resistance in homologous recombination repair proficient breast cancers to PARP inhibition

BACKGROUND

Poly(ADP-ribose) polymerase inhibitors (PARPi) target tumours defective in homologous recombination (HR). Most BRCA-wild-type (WT) HR-proficient breast cancers are intrinsically resistant to PARP inhibitors, e.g., talazoparib. We evaluated the role of autophagy in this de novo resistance and determined the underlying mechanism to overcome this.

METHODS

Autophagosome formation and autophagic flux were assessed by evaluating endogenous LC3-II levels and ectopic expression of EGFP-LC3 and mRFP-EGFP-LC3 in breast cancer cells. Autophagy-defective cells were generated by genetic depletion of BECN1, ATG5, p62/SQSTM1 and LAMP1 by using CRISPR-Cas9 double nickase system. The response of PARPi was evaluated in autophagy-proficient and -defective breast cancer cells and in xenograft SCID-mice model.

RESULTS

Pro-survival autophagy was significantly enhanced upon talazoparib treatment in BRCA-WT breast cancer cell lines. Autophagy-deficient cells were hypersensitive to talazoparib. Targeting autophagy synergistically enhanced the therapeutic efficacy of talazoparib in BRCA1-WT breast cancer cells in vitro and in vivo xenograft tumour mouse model. Mechanistically, autophagy inhibition by chloroquine promoted deleterious NHEJ mediated DSB-repair, leading to extensive genomic instability and mitotic catastrophe.

CONCLUSIONS

Autophagy confers de novo resistance to PARP inhibitor, talazoparib. Autophagy inhibition improves the therapeutic outcome of PARPi treatment in preclinical mice model, bearing HR-proficient breast tumours, warranting its usage in the clinical settings.

Autophagy and senescence in cancer therapy

Tumor cells can undergo diverse responses to cancer therapy. While apoptosis represents the most desirable outcome, tumor cells can alternatively undergo autophagy and senescence. Both autophagy and senescence have the potential to make complex contributions to tumor cell survival via both cell autonomous and cell non-autonomous pathways. The induction of autophagy and senescence in tumor cells, preclinically and clinically, either individually or concomitantly, has generated interest in the utilization of autophagy modulating and senolytic therapies to target autophagy and senescence, respectively. This chapter summarizes the current evidence for the promotion of autophagy and senescence as fundamental responses to cancer therapy and discusses the complexity of their functional contributions to cell survival and disease outcomes. We also highlight current modalities designed to exploit autophagy and senescence in efforts to improve the efficacy of cancer therapy.

An updated pharmacological insight of resveratrol in the treatment of diabetic nephropathy

As one of the most common complications of diabetes, nephropathy develops in approximately 40% of diabetic individuals. Although end stage kidney disease is known as one of the most consequences of diabetic nephropathy, the majority of diabetic individuals might die from cardiovascular diseases and infections before renal replacement treatment. Moreover, the routine medical treatments for diabetes hold undesirable side effects. The explosive prevalence of diabetes urges clinicians and scientists to investigate the complementary or alternative therapies. Phytochemicals are emerging as alternatives with a wide range of therapeutic effects on various pathologies, including diabetic kidney disease. Of those phytochemicals, resveratrol, a natural polyphenolic stilbene, has been found to exert a broad spectrum of health benefits via various signaling molecules. In particular, resveratrol has gained a great deal of attention because of its anti-oxidative, anti-inflammatory, anti-diabetic, anti-obesity, cardiovascular-protective, and anti-tumor properties. In the renal system, emerging evidence shows that resveratrol has already been used to ameliorate chronic or acute kidney injury. This review critically summarizes the current findings and molecular mechanisms of resveratrol in diabetic renal damage. In addition, we will discuss the adverse and inconsistent effects of resveratrol in diabetic nephropathy. Although there is increasing evidence that resveratrol affords great potential in diabetic nephropathy therapy, these results should be treated with caution before its clinical translation. In addition, the unfavorable pharmacokinetics and/or pharmacodynamics profiles, such as poor bioavailability, may limit its extensive clinical applications. It is clear that further research is needed to unravel these limitations and improve its efficacy against diabetic nephropathy. Increasing investigation of resveratrol in diabetic kidney disease will not only help us better understand its pharmacological actions, but also provide novel potential targets for therapeutic intervention.

Autophagy restricts mitochondrial DNA damage-induced release of ENDOG (endonuclease G) to regulate genome stability

Genotoxic insult causes nuclear and mitochondrial DNA damages with macroautophagy/autophagy induction. The role of mitochondrial DNA (mtDNA) damage in the requirement of autophagy for nuclear DNA (nDNA) stability is unclear. Using site-specific DNA damage approaches, we show that specific nDNA damage alone does not require autophagy for repair unless in the presence of mtDNA damage. We provide evidence that after IR exposure-induced mtDNA and nDNA damages, autophagy suppression causes non-apoptotic mitochondrial permeability, by which mitochondrial ENDOG (endonuclease G) is released and translocated to nuclei to sustain nDNA damage in a TET (tet methylcytosine dioxygenase)-dependent manner. Furthermore, blocking lysosome function is sufficient to increase the amount of mtDNA leakage to the cytosol, accompanied by ENDOG-free mitochondrial puncta formation with concurrent ENDOG nuclear accumulation. We proposed that autophagy eliminates the mitochondria specified by mtDNA damage-driven mitochondrial permeability to prevent ENDOG-mediated genome instability. Finally, we showed that HBx, a hepatitis B viral protein capable of suppressing autophagy, also causes mitochondrial permeability-dependent ENDOG mis-localization in nuclei and is linked to hepatitis B virus (HBV)-mediated hepatocellular carcinoma development.Abbreviations: 3-MA: 3-methyladenine; 5-hmC: 5-hydroxymethylcytosine; ACTB: actin beta; ATG5: autophagy related 5; ATM: ATM serine/threonine kinase; DFFB/CAD: DNA fragmentation factor subunit beta; cmtDNA: cytosolic mitochondrial DNA; ConA: concanamycin A; CQ: chloroquine; CsA: cyclosporin A; Dox: doxycycline; DSB: double-strand break; ENDOG: endonuclease G; GFP: green fluorescent protein; Gy: gray; H2AX: H2A.X variant histone; HBV: hepatitis B virus; HBx: hepatitis B virus X protein; HCC: hepatocellular carcinoma; I-PpoI: intron-encoded endonuclease; IR: ionizing radiation; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MOMP: mitochondrial outer membrane permeability; mPTP: mitochondrial permeability transition pore; mtDNA: mitochondrial DNA; nDNA: nuclear DNA; 4-OHT: 4-hydroxytamoxifen; rDNA: ribosomal DNA; ROS: reactive oxygen species; SQSTM1/p62: sequestosome 1; TET: tet methylcytosine dioxygenase; TFAM: transcription factor A, mitochondrial; TOMM20: translocase of outer mitochondrial membrane 20; VDAC: voltage dependent anion channel.

Protein Kinase-Mediated Decision Between the Life and Death

Protein kinases are intracellular signaling enzymes that catalyze the phosphorylation of specific residues in their target substrate proteins. They play important role for regulation of life and death decisions. The complexity of the relationship between death receptors and protein kinases' cell death decision-making mechanisms create many difficulties in the treatment of various diseases. The most of fifteen different cell death pathways, which are reported by Nomenclature Committee on Cell Death (NCCD) are protein kinase signal transduction-mediated negative or positive selections. Tumor necrosis factor (TNF) as a main player of death pathways is a dual-functioning molecule in that it can promote both cell survival or cell death. All apoptotic and necrotic signal transductions are conveyed through death domain-containing death receptors, which are expressed on the surface of nearly all human cells. In humans, eight members of the death receptor family have been identified. While the interaction of TNF with TNF Receptor 1 (TNFR1) activates various signal transduction pathways, different death receptors activate three main signal transduction pathways: nuclear factor kappa B (NF-ĸB)-mediated differentiation or pro-inflammatory cytokine synthesis, mitogen-activated protein kinase (MAPK)-mediated stress response and caspase-mediated apoptosis. The link between the NF-ĸB and the c-Jun NH₂-terminal kinase (JNK) pathways comprise another check-point to regulate cell death. TNF-α also promotes the "receptor-interacting serine/threonine protein kinase 1" (RIPK1)/RIPK3/ mixed lineage kinase domain-like pseudokinase (MLKL)-dependent necrosis. Thus, necrosome is mainly comprised of MLKL, RIPK3 and, in some cases, RIPK1. In fact, RIPK1 is at the crossroad between life and death, downstream of various receptors as a regulator of endoplasmic reticulum stress-induced death. TNFR1 signaling complex (TNF-RSC), which contains multiple kinase activities, promotes phosphorylation of transforming growth factor β-activated kinase 1 (TAK1), inhibitor of nuclear transcription factor κB (IκB) kinase (IKK) α/IKKβ, IκBα, and NF-κB. IKKs affect cell-survival pathways in NF-κB-independent manner. Toll-like receptor (TLR) stimulation triggers various signaling pathways dependent on myeloid differentiation factor-88 (MyD88), Interleukin-1 receptor (IL-1R)-associated kinase (IRAK1), IRAK2 and IRAK4, lead to post-translational activation of nucleotide and oligomerization domain (NLRP3). Thereby, cell fate decisions following TLR signaling is parallel with death receptor signaling. Inhibition of IKKα/IKKβ or its upstream activators sensitize cells to death by inducing RIPK1-dependent apoptosis or necroptosis. During apoptosis, several kinases of the NF-κB pathway, including IKK1 and NF-κB essential modulator (NEMO), are cleaved by cellular caspases. This event can terminate the NF-κB-derived survival signals. In both canonical and non-canonical pathways, IKK is key to NF-κB activation. Whereas, the activation process of IKK, the functions of NEMO ubiquitination, IKK-related non-canonical pathway and the nuclear transportation of NEMO and functions of IKKα are still debated in cell death. In addition, cluster of differentiation 95 (CD95)-mediated non-apoptotic signaling and CD95- death-inducing signaling complex (DISC) interactions are waiting for clarification.

TIP60 in aging and neurodegeneration

Epigenetic modification of chromatin, including histone methylation and acetylation, plays critical roles in eukaryotic cells and has a significant impact on chromatin structure/accessibility, gene regulation and, susceptibility to aging, neurodegenerative disease, cancer, and other age-related diseases. This article reviews the current advances on TIP60/KAT5, a major histone acetyltransferase with diverse functions in eukaryotes, with emphasis on its regulation of autophagy, proteasome-dependent protein turnover, RNA transcription, DNA repair, circadian rhythms, learning and memory, and other neurological functions implicated in aging and neurodegeneration. Moreover, the promising therapeutic potential of TIP60 is discussed to target Alzheimer's disease and other neurological diseases.

The multifaceted roles of nucleophagy in cancer development and therapy

Autophagy is an evolutionarily conserved process in which the cell degrades its own components and recycles the biomolecules for survival and homeostasis. It is an important cellular process to eliminate pathogens or damaged organelles. Nucleophagy, also termed as nuclear autophagy, is a more recently described subtype of autophagy, in which nuclear components, such as nuclear lamina and DNA, are to be degraded. Nucleophagy plays a double-facet role in the development of cancer. On one hand, the clearance of damaged DNA or nuclear structures via autophagic pathway is crucial to maintain nuclear integrity and prevent tumorigenesis. On the other hand, in later stages of tumor growth, nucleophagy may facilitate cancer cell survival and metastasis in the nutrient-depleted microenvironment. In this review, we discuss the relationship between nucleophagy and cancer along with potential intervention methods to target cancer through manipulating nucleophagy. Given the known observations about nucleophagy, it could be promising to target different nuclear components during the processes of nucleophagy, especially nuclear lamina. Further research on investigating the role of nucleophagy in oncological context could focus on dissecting its remaining molecular pathways and their connection to known tumor suppressors.

Autophagy-deficient Arabidopsis mutant atg5, which shows ultraviolet-B sensitivity, cannot remove ultraviolet-B-induced fragmented mitochondria

Mitochondria damaged by ultraviolet-B radiation (UV-B, 280-315 nm) are removed by mitophagy, a selective autophagic process. Recently, we demonstrated that autophagy-deficient Arabidopsis thaliana mutants exhibit a UV-B-sensitive phenotype like that of cyclobutane pyrimidine dimer (CPD)-specific photolyase (PHR1)-deficient mutants. To explore the relationship between UV-B sensitivity and autophagy in UV-B-damaged plants, we monitored mitochondrial dynamics and autophagy in wild-type Arabidopsis (ecotype Columbia); an autophagy-deficient mutant, atg5; a PHR1-deficient mutant, phr1; an atg5 phr1 double mutant; and AtPHR1-overexpressing (AtPHR1ox) plants following high-dose UV-B exposure (1.5 W m^-2 for 1 h). At 10 h after exposure, the number of mitochondria per mesophyll leaf cell was increased and the volumes of individual mitochondria were decreased independently of UV-B-induced CPD accumulation in all genotypes. At 24 h after exposure, the mitochondrial number had recovered or almost recovered to pre-exposure levels in plants with functional autophagy (WT, phr1, and AtPHR1ox), but had increased even further in atg5. This suggested that the high dose of UV-B led to the inactivation and fragmentation of mitochondria, which were removed by mitophagy activated by UV-B. The UV-B-sensitive phenotype of the atg5 phr1 double mutant was more severe than that of atg5 or phr1. In wild-type, phr1, and AtPHR1ox plants, autophagy-related genes were strongly expressed following UV-B exposure independently of UV-B-induced CPD accumulation. Therefore, mitophagy might be one of the important repair mechanisms for UV-B-induced damage. The severe UV-B-sensitive phenotype of atg5 phr1 is likely an additive effect of deficiencies in independent machineries for UV-B protection, autophagy, and CPD photorepair.

Integrating DNA damage response and autophagy signalling axis in ultraviolet-B induced skin photo-damage: a positive association in protecting cells against genotoxic stress

The skin acts as both physical as well as an immunological barrier against hazardous agents from the outside environment and protects the internal organs against damage. Skin ageing is a dynamic process caused by the influence of various external factors, including damage from ultraviolet (UV-B) radiation, which is known as photo-ageing, and due to internal chronological mechanisms. A normal ageing process requires several orchestrated defense mechanisms to diverse types of stress responses, the concomitant renewal of cellular characteristics, and the homeostasis of different cell types that directly or indirectly protect the integrity of skin. Cumulative oxidative and endoplasmic reticulum (ER) stress responses and their adverse impact on biological systems in the skin are a common mechanism of the ageing process, negatively impacting DNA by causing mutations that lead to many physiological, functional, and aesthetic changes in the skin, culminating in the development of many diseases, including photo-damage and photo-carcinogenesis. Exposure of the skin to ultraviolet-(B) elicits the activation of signal transduction pathways, including DNA damage response, autophagy, and checkpoint signal adaptations associated with clearing radiation-induced DNA damage. Recent experimental reports suggest that autophagy is involved in maintaining skin homeostasis upon encountering different stresses, notably genotoxic stress. It has also been revealed that autophagy positively regulates the recognition of DNA damage by nucleotide excision repair and that skin ageing is associated with defects in the autophagy process. Moreover, autophagy is constitutively active in the skin epithelium, imparting protection to skin cells against a diverse range of outside insults, thus increasing resistance to environmental stressors. It has also been found that the stress-induced suppression of the autophagy response in experimental settings leads to enhanced apoptosis during photo-ageing upon UV-B exposure and that the maintenance of homeostasis depends on cellular autophagy levels. More recent reports in this domain claim that relieving the oxidative-stress-mediated induction of the ER stress response upon UV-B irradiation protects skin cells from photo-damage effects. The integration of autophagy and the DNA damage response under genotoxic stress is being considered as a meaningful partnership for finding novel molecular targets and devising suitable therapeutic strategies against photo-ageing disorders. Here, we summarize and review the current understanding of the mechanisms governing the intricate interplay between autophagy and the DNA damage response and its regulation by UV-B, the roles of autophagy in regulating the cellular response to UV-B-induced photodamage, and the implications of the modulation of autophagy as a meaningful partnership in the treatment and prevention of photoaging disorders.