Autophagy inhibitors

Tong-Xie-Yao-Fang induces mitophagy in colonic epithelial cells to inhibit colitis-associated colorectal cancer

ETHNOPHARMACOLOGICAL RELEVANCE

Based on the core pathogenesis of hepatosplenic disorder and qi transformation disorder in ulcerative colitis, Tong-Xie-Yao-Fang (TXYF) is a classical traditional Chinese medicine commonly used to treat ulcerative colitis. Our study revealed that it has the potential to prevent colitis-associated colorectal cancer, which embodies the academic concept in traditional Chinese medicine of treating the disease before it develops.

AIM OF THE STUDY

This study was aimed at evaluating the therapeutic role of TXYF in treating colitis-associated colorectal cancer and exploring its possible underlying mechanisms.

MATERIALS AND METHODS

A colitis-associated colorectal cancer model was established in mice using azoxymethane and dextran sulfate sodium salt to examine the therapeutic effect of TXYF. The mouse body weights were observed. Hematoxylin-eosin staining was used to evaluate mouse colon histopathology. Colon cancer cells and colon epithelial cells were used to explore the potential molecular mechanisms. The proliferation and apoptosis of cells were detected by CCK8 and cell colony assays, flow cytometry and western blotting. The epithelial-mesenchymal transition (EMT) and mitophagy markers were examined by immunohistochemistry, western blotting, quantitative real-time PCR and immunofluorescence staining.

RESULTS

TXYF inhibited the tumorigenesis of mice with colitis-associated colorectal cancer and the growth of inflammatory colon cells. TXYF induced mitophagy in colon cancer cells through the PTEN-induced putative kinase 1 (PINK1)/Parkin pathway to reverse EMT, which was consistent with the results in mice with colitis-associated colorectal cancer.

CONCLUSIONS

The results of the present study demonstrated that TXYF effectively inhibited the progression of colitis-associated colorectal cancer through the PINK1/Parkin pathway, which provides new evidence for prevention strategies for this disease.

Tao-Hong-Si-Wu-Tang improves thioacetamide-induced liver fibrosis by reversing ACSL4-mediated lipid accumulation and promoting mitophagy

ETHNOPHARMACOLOGICAL RELEVANCE

Liver fibrosis is a generic fibrous scarring event resulting from accumulation of extracellular matrix (ECM) proteins, easily progressing to end-stage liver diseases. Tao-Hong-Si-Wu-Tang (THSWT) is a traditional Chinese medicine formula applied in clinics to treat gynecological and chronic liver diseases. However, the role of THSWT on thioacetamide (TAA)-induced hepatic fibrosis and the specific mechanisms remains unclear.

AIM OF THE STUDY

To investigate the improving effects of THSWT on TAA-insulted hepatic fibrosis and the underlying mechanisms.

MATERIALS AND METHODS

UHPLC-MS/MS was performed to explore the chemical characterization of THSWT. Mice were orally administered with THSWT once daily for 6 weeks along with TAA challenge. Liver function was reflected through serum biomarkers and histopathological staining. RNA sequencing, non-targeted metabolomics and molecular biology experiments were applied to investigate the underlying mechanisms.

RESULTS

THSWT profoundly repaired lipid metabolism dysfunction and blocked collagen accumulation both in TAA-stimulated mice and in hepatocytes. Results of RNA sequencing and non-targeted metabolomics revealed that the anti-fibrotic effects of THSWT mostly relied on lipid metabolism repairment by increasing levels of acetyl-CoA, phosphatidylcholine, phosphatidylethanolamine, lysophosphatidylcholine and lysophosphatidylethanolamine, and decreasing relative abundances of acyl-CoA, total cholesterol, diacylglycerol, triacylglycerol and phosphatidylinositol. Mechanically, long-chain acyl-CoA synthetases 4 (ACSL4) was a key profibrotic target both in human and mice by disrupting lipid oxidation and metabolism in hepatic mitochondria. THSWT effectively blocked ACSL4 and promoted mitophagy to reverse above outcomes, which was verified by mitophagy depletion.

CONCLUSION

THSWT may be a promising therapeutic option for treating hepatic fibrosis and its complications by modulating lipid metabolism and promoting mitophagy in livers.

Treatment with autophagic inhibitors enhances oligonol‑induced apoptotic effects in nasopharyngeal carcinoma cells

Although the combination of chemotherapy and radiotherapy has increased the survival rate of patients with nasopharyngeal carcinoma (NPC), certain patients do not respond well to the treatment and have a poor prognosis. Therefore, novel therapeutic drugs and strategies to improve prognosis of patients with NPC are required. As certain plant extracts can suppress the viability of cancer cells, the present study investigated whether oligonol, a polyphenolic compound primarily found in lychee fruit, exerts anticancer activities in NPC cells. MTT, ELISA and immunoblotting were performed to investigate cell survival, cytokeratin-18 fragment release, and the expression of apoptosis and autophagy markers, respectively. Oligonol decreased the viability of NPC-TW01 and NPC/HK1NPC cell lines. Oligonol increased the protein expression of several apoptosis markers, including cleaved caspase-8 and -3, cleaved PARP and cytokeratin 18 fragment. Moreover, it also increased expression of autophagy markers Beclin 1 and LC3-II, as well as LC3-II/LC3-I ratio in both NPC cell lines. Furthermore, treatment with autophagy inhibitors 3-methyladenine or LY294002 significantly increased oligonol-induced viability inhibition in NPC-TW01 cells. Combined treatment of oligonol + LY294002 reduced LC3-II expression and the LC3II/LC3I ratio while increasing cleaved caspase-8 and -3, cleaved PARP and cytokeratin 18 fragment expression in NPC-TW01 cells. These findings indicated autophagy inhibitors could enhance viability inhibition and apoptotic effects induced by oligonol in NPC cells.

Dehydroandrographolide ameliorates doxorubicin-mediated cardiotoxicity by regulating autophagy through the mTOR-TFEB pathway

The clinical application of doxorubicin (DOX) was limited by the serious cardiotoxicity. The traditional Chinese medicine Andrographis paniculata and its principal active component (Dehydroandrographolide, DA) have been well known for their diverse cardiovascular protective effects. However, the effects of DA on DOX-induced cardiotoxicity (DIC) were still unknown. In this study, we evaluated the effects and revealed the potential mechanisms of DA on DIC both in vivo and in vitro. The effects of DA on DIC were systematically assessed by echocardiography and histological assays. Western blot and flow cytometry were used to measure apoptosis of cardiomyocytes. Transmission electron microscopy and StubRFP-SensGFP-LC3 lentivirus were further used to assay autophagic flux. Our results showed that DA administration significantly improved cardiac function and attenuated DOX-induced cardiomyocyte apoptosis. Mechanically, DA restored autophagic flux and lysosome functions via inhibiting DOX-induced mTOR signal pathway activation and increasing the translocation of TFEB to the nucleus. However, activation of mTOR or knockdown of TFEB significantly inhibited the protective effects of DA against DIC by impacting lysosomal functions and autophagic flux. In conclusion, our results revealed that DA might be a potential cardioprotective agent against DIC.

Discovery of novel ULK1 inhibitors through machine learning-guided virtual screening and biological evaluation

Aim: Build a virtual screening model for ULK1 inhibitors based on artificial intelligence. Materials & methods: Build machine learning and deep learning classification models and combine molecular docking and biological evaluation to screen ULK1 inhibitors from 13 million compounds. And molecular dynamics was used to explore the binding mechanism of active compounds. Results & conclusion: Possibly due to less available training data, machine learning models significantly outperform deep learning models. Among them, the Naive Bayes model has the best performance. Through virtual screening, we obtained three inhibitors with IC50 of μM level and they all bind well to ULK1. This study provides an efficient virtual screening model and three promising compounds for the study of ULK1 inhibitors.

Cellular and molecular mechanisms of gastrointestinal cancer liver metastases and drug resistance

Distant metastases and drug resistance account for poor survival of patients with gastrointestinal (GI) malignancies such as gastric cancer, pancreatic cancer, and colorectal cancer. GI cancers most commonly metastasize to the liver, which provides a unique immunosuppressive tumour microenvironment to support the development of a premetastatic niche for tumor cell colonization and metastatic outgrowth. Metastatic tumors often exhibit greater resistance to drugs than primary tumors, posing extra challenges in treatment. The liver metastases and drug resistance of GI cancers are regulated by complex, intertwined, and tumor-dependent cellular and molecular mechanisms that influence tumor cell behavior (e.g. epithelial-to-mesenchymal transition, or EMT), tumor microenvironment (TME) (e.g. the extracellular matrix, cancer-associated fibroblasts, and tumor-infiltrating immune cells), tumor cell-TME interactions (e.g. through cytokines and exosomes), liver microenvironment (e.g. hepatic stellate cells and macrophages), and the route and mechanism of tumor cell dissemination (e.g. circulating tumor cells). This review provides an overview of recent advances in the research on cellular and molecular mechanisms that regulate liver metastases and drug resistance of GI cancers. We also discuss recent advances in the development of mechanism-based therapy for these GI cancers. Targeting these cellular and molecular mechanisms, either alone or in combination, may potentially provide novel approaches to treat metastatic GI malignancies.

XBP1s activates METTL3/METTL14 for ER-phagy and paclitaxel sensitivity regulation in breast cancer

Cancer cells employ the unfolded protein response (UPR) or induce autophagy, especially selective removal of certain ER domains via reticulophagy (termed ER-phagy), to mitigate endoplasmic reticulum (ER) stress for ER homeostasis when encountering microenvironmental stress. N6-methyladenosine (m6A) is one of the most abundant epitranscriptional modifications and plays important roles in various biological processes. However, the molecular mechanism of m6A modification in the ER stress response is poorly understood. In this study, we first found that ER stress could dramatically elevate m6A methylation levels through XBP1s-dependent transcriptional upregulation of METTL3/METTL14 in breast cancer (BC) cells. Further MeRIP sequencing and relevant validation results confirmed that ER stress caused m6A methylation enrichment on target genes for ER-phagy. Mechanistically, METTL3/METTL14 increased ER-phagy machinery formation by promoting m6A modification of the ER-phagy regulators CALCOCO1 and p62, thus enhancing their mRNA stability. Of note, we further confirmed that the chemotherapeutic drug paclitaxel (PTX) could induce ER stress and increase m6A methylation for ER-phagy. Furthermore, the combination of METTL3/METTL14 inhibitors with PTX demonstrated a significant synergistic therapeutic effect in both BC cells and xenograft mice. Thus, our data built a novel bridge on the crosstalk between ER stress, m6A methylation and ER-phagy. Most importantly, our work provides novel evidence of METTL3 and METTL14 as potential therapeutic targets for PTX sensitization in breast cancer.

Porphyromonas gingivalis activates Heat-Shock-Protein 27 to drive a LC3C-specific probacterial form of select autophagy that is redox sensitive for intracellular bacterial survival in human gingival mucosa

Porphyromonas gingivalis , a major oral pathobiont, evades canonical host pathogen clearance in human primary gingival epithelial cells (GECs) by initiating a non-canonical variant of autophagy consisting of Microtubule-associated protein 1A/1B-light chain 3 (LC3)-rich autophagosomes, which then act as replicative niches. Simultaneously, P. gingivalis inhibits apoptosis and oxidative-stress, including extracellular-ATP (eATP)-mediated reactive-oxygen-species (ROS) production via phosphorylating Heat Shock Protein 27 (HSp27) with the bacterial nucleoside-diphosphate-kinase (Ndk). Here, we have mechanistically identified that P. gingivalis -mediated induction of HSp27 is crucial for the recruitment of the LC3 isoform, LC3C, to drive the formation of live P. gingivalis -containing Beclin1-ATG14-rich autophagosomes that are redox sensitive and non-degrading. HSp27 depletions of both infected GECs and gingiva-mimicking organotypic-culture systems resulted in the collapse of P. gingivalis -mediated autophagosomes, and abolished P. gingivalis -induced LC3C-specific autophagic-flux in a HSp27-dependent manner. Concurrently, HSp27 depletion accompanied by eATP treatment abrogated protracted Beclin 1-ATG14 partnering and decreased live intracellular P. gingivalis levels. These events were only partially restored via treatments with the antioxidant N-acetyl cysteine (NAC), which rescued the cellular redox environment independent of HSp27. Moreover, the temporal phosphorylation of HSp27 by the bacterial Ndk results in HSp27 tightly partnering with LC3C, hindering LC3C canonical cleavage, extending Beclin 1-ATG14 association, and halting canonical maturation. These findings pinpoint how HSp27 pleiotropically serves as a major platform-molecule, redox regulator, and stepwise modulator of LC3C during P. gingivalis -mediated non-canonical autophagy. Thus, our findings can determine specific molecular strategies for interfering with the host-adapted P. gingivalis ' successful mucosal colonization and oral dysbiosis.

Exploring the Link Between Autophagy-Lysosomal Dysfunction and Early Heterotopic Ossification in Tendons

Heterotopic ossification (HO), the pathological formation of bone within soft tissues such as tendon and muscle, is a notable complication resulting from severe injury. While soft tissue injury is necessary for HO development, the specific molecular pathology responsible for trauma-induced HO remains a mystery. The previous study detected abnormal autophagy function in the early stages of tendon HO. Nevertheless, it remains to be determined whether autophagy governs the process of HO generation. Here, trauma-induced tendon HO model is used to investigate the relationship between autophagy and tendon calcification. In the early stages of tenotomy, it is observed that autophagic flux is significantly impaired and that blocking autophagic flux promoted the development of more rampant calcification. Moreover, Gt(ROSA)26sor transgenic mouse model experiments disclosed lysosomal acid dysfunction as chief reason behind impaired autophagic flux. Stimulating V-ATPase activity reinstated both lysosomal acid functioning and autophagic flux, thereby reversing tendon HO. This present study demonstrates that autophagy-lysosomal dysfunction triggers HO in the stages of tendon injury, with potential therapeutic targeting implications for HO.

PDX proteins from Arabidopsis thaliana as novel substrates of cathepsin B: implications for vitamin B6 biosynthesis regulation

Vitamin B6 is a critical molecule for metabolism, development, and stress sensitivity in plants. It is a cofactor for numerous biochemical reactions, can serve as an antioxidant, and has the potential to increase tolerance against both biotic and abiotic stressors. Due to the importance of vitamin B6, its biosynthesis is likely tightly regulated. Plants can synthesize vitamin B6 de novo via the concerted activity of Pyridoxine Biosynthesis Protein 1 (PDX1) and PDX2. Previously, PDX proteins have been identified as targets for ubiquitination, indicating they could be marked for degradation by two highly conserved pathways: the Ubiquitin Proteasome Pathway (UPP) and the autophagy pathway. Initial experiments show that PDXs are in fact degraded, but surprisingly, in a ubiquitin-independent manner. Inhibitor studies pointed toward cathepsin B, a conserved lysosomal cysteine protease, which is implicated in both programed cell death and autophagy in humans and plants. In plants, cathepsin Bs are poorly described, and no confirmed substrates have been identified. Here, we present PDX proteins from Arabidopsis thaliana as interactors and substrates of a plant Cathepsin B. These findings not only describe a novel cathepsin B substrate in plants, but also provide new insights into how plants regulate de novo biosynthesis of vitamin B6.

Matrine induces autophagic cell death by triggering ROS/AMPK/mTOR axis and apoptosis in multiple myeloma

Despite significant advancements in multiple myeloma (MM) treatment in recent years, most patients will eventually develop resistance or experience relapse. Matrine, a primary active compound of traditional Chinese medicinal herb Sophora flavescens Ait, has been found to have anti-tumor properties in various types of malignant tumors. Whether autophagy plays a crucial role in the anti-MM effect of matrine remain unknown. Herein, we found that matrine could trigger apoptosis and cell cycle arrest, and meanwhile induce autophagy in MM cells in vitro. We further ascertained the role of autophagy by using ATG5 siRNA or the autophagy inhibitor spautin-1, which partially reversed matrine's inhibitory effect on MM cells. Conversely, the combination of matrine with the autophagy inducer rapamycin enhanced their anti-tumor activity. These findings suggest that autophagy induced by matrine can lead to cell death in MM cells. Further mechanism investigation revealed that matrine treatment increased the levels of reactive oxygen species (ROS) and AMPKα1 phosphorylation and decreased the phosphorylation of mTOR in MM cells. Additionally, co-treatment with AMPKα1 siRNA or the ROS scavenger N-acetyl-1-cysteine weakened the increase in autophagy that was induced by matrine. Finally, we demonstrated a synergistic inhibitory effect of matrine and rapamycin against MM in a xenograft mouse model. Collectively, our findings provided novel insights into the anti-MM efficacy of matrine and suggest that matrine induces autophagy by triggering ROS/AMPK/mTOR axis in MM cells, and combinatorial treatment of matrine and rapamycin may be a promising therapeutic strategy against MM.

Dual inhibition of oxidative phosphorylation and glycolysis to enhance cancer therapy

Dual suppression of oxidative phosphorylation (OXPHOS) and glycolysis can disrupt metabolic adaption of cancer cells, inhibiting energy supply and leading to successful cancer therapy. Herein, we have developed an α-tocopheryl succinate (α-TOS)-functionalized iridium(III) complex Ir2, a highly lipophilic mitochondria targeting anticancer molecule, could inhibit both oxidative phosphorylation (OXPHOS) and glycolysis, resulting in the energy blockage and cancer growth suppression. Mechanistic studies reveal that complex Ir2 induces reactive oxygen species (ROS) elevation and mitochondrial depolarization, and triggers DNA oxidative damage. These damages could evoke the cancer cell death with the mitochondrial-relevant apoptosis and autophagy. 3D tumor spheroids experiment demonstrates that Ir2 owned superior antiproliferation performance, as the potent anticancer agent in vivo. This study not only provided a new path for dual inhibition of both mitochondrial OXPHOS and glycolytic metabolisms with a novel α-TOS-functionalized metallodrug, but also further demonstrated that the mitochondrial-relevant therapy could be effective in enhancing the anticancer performance.

Autophagy initiation triggers p150Glued-AP-2β interaction on the lysosomes and facilitates their transport

The endocytic adaptor protein 2 (AP-2) complex binds dynactin as part of its noncanonical function, which is necessary for dynein-driven autophagosome transport along microtubules in neuronal axons. The absence of this AP-2-dependent transport causes neuronal morphology simplification and neurodegeneration. The mechanisms that lead to formation of the AP-2-dynactin complex have not been studied to date. However, the inhibition of mammalian/mechanistic target of rapamycin complex 1 (mTORC1) enhances the transport of newly formed autophagosomes by influencing the biogenesis and protein interactions of Rab-interacting lysosomal protein (RILP), another dynein cargo adaptor. We tested effects of mTORC1 inhibition on interactions between the AP-2 and dynactin complexes, with a focus on their two essential subunits, AP-2β and p150Glued. We found that the mTORC1 inhibitor rapamycin enhanced p150Glued-AP-2β complex formation in both neurons and non-neuronal cells. Additional analysis revealed that the p150Glued-AP-2β interaction was indirect and required integrity of the dynactin complex. In non-neuronal cells rapamycin-driven enhancement of the p150Glued-AP-2β interaction also required the presence of cytoplasmic linker protein 170 (CLIP-170), the activation of autophagy, and an undisturbed endolysosomal system. The rapamycin-dependent p150Glued-AP-2β interaction occurred on lysosomal-associated membrane protein 1 (Lamp-1)-positive organelles but without the need for autolysosome formation. Rapamycin treatment also increased the acidification and number of acidic organelles and increased speed of the long-distance retrograde movement of Lamp-1-positive organelles. Altogether, our results indicate that autophagy regulates the p150Glued-AP-2β interaction, possibly to coordinate sufficient motor-adaptor complex availability for effective lysosome transport.

NUPR1 induces autophagy and promotes the progression of Esophageal squamous cell carcinoma via the MAPK-mTOR pathway

PURPOSE

Esophageal squamous cell carcinoma (ESCC) is a dominant pathological type in China. NUPR1 is a complex molecule implicated in various physiological and biological functions whose expression is upregulated in response to stress. Furthermore, autophagy is a vital physiological mechanism in the onset and metastasis of malignancies. This study aims to uncover the influence of NUPR1 on ESCC occurrence and development by regulating autophagy while also exploring its association with the MAPK signaling pathway.

METHODS

First, the differences in NUPR1 between ESCC and normal tissues were analyzed through online databases. Subsequently, the pathological tissues of clinical samples were stained and scored using immunohistochemistry. And NUPR1 expression in ESCC cells was investigated, as was the function of NUPR1 in the modulation of ESCC's malignant behavior. Furthermore, a nude mouse ESCC xenograft model was developed. Finally, RNA sequencing was performed on NUPR1-downregulated ESCC cells, which was verified using WB.

RESULTS

Our findings initially uncovered differences in the expression of NUPR1 in ESCC and normal tissues. In vitro experiments demonstrated that NUPR1 downregulation significantly inhibited ESCC cell proliferation, invasion, and migration, as well as promoted their apoptosis. Our xenograft model exhibited significant inhibition of ESCC tumors upon NUPR1 downregulation. Subsequently, RNA sequencing uncovered that NUPR1 regulates its malignant biological behavior through MAPK-mTOR signaling pathway. Finally, we found that NUPR1 downregulation can inhibit autophagic flux in ESCC.

CONCLUSION

Collectively, our findings show that NUPR1 enhances the progression of ESCC by triggering autophagy and is associated with the MAPK-mTOR signaling pathway.

Caspase-1 Deficiency Modulates Adipogenesis through Atg7-Mediated Autophagy: An Inflammatory-Independent Mechanism

Obesity stands as a significant risk factor for type 2 diabetes, hyperlipidemia, and cardiovascular diseases, intertwining increased inflammation and decreased adipogenesis with metabolic disorders. Studies have highlighted the correlation between Caspase-1 and inflammation in obesity, elucidating its essential role in the biological functions of adipose tissue. However, the impact of Caspase-1 on adipogenesis and the underlying mechanisms remain largely elusive. In our study, we observed a positive correlation between Caspase-1 expression and obesity and its association with adipogenesis. In vivo experiments revealed that, under normal diet conditions, Caspase-1 deficiency improved glucose homeostasis, stimulated subcutaneous adipose tissue expansion, and enhanced adipogenesis. Furthermore, our findings indicate that Caspase-1 deficiency promotes the expression of autophagy-related proteins and inhibits autophagy with 3-MA or CQ blocked Caspase-1 deficiency-induced adipogenesis in vitro. Notably, Caspase-1 deficiency promotes adipogenesis via Atg7-mediated autophagy activation. In addition, Caspase-1 deficiency resisted against high-fat diet-induced obesity and glucose intolerance. Our study proposes the downregulation of Caspase-1 as a promising strategy for mitigating obesity and its associated metabolic disorders.

A Conversation with ChatGPT on Contentious Issues in Senescence and Cancer Research

Artificial intelligence (AI) platforms, such as Generative Pretrained Transformer (ChatGPT), have achieved a high degree of popularity within the scientific community due to their utility in providing evidence-based reviews of the literature. However, the accuracy and reliability of the information output and the ability to provide critical analysis of the literature, especially with respect to highly controversial issues, has generally not been evaluated. In this work, we arranged a question/answer session with ChatGPT regarding several unresolved questions in the field of cancer research relating to therapy-induced senescence (TIS), including the topics of senescence reversibility, its connection to tumor dormancy, and the pharmacology of the newly emerging drug class of senolytics. ChatGPT generally provided responses consistent with the available literature, although occasionally overlooking essential components of the current understanding of the role of TIS in cancer biology and treatment. Although ChatGPT, and similar AI platforms, have utility in providing an accurate evidence-based review of the literature, their outputs should still be considered carefully, especially with respect to unresolved issues in tumor biology. SIGNIFICANCE STATEMENT: Artificial Intelligence platforms have provided great utility for researchers to investigate biomedical literature in a prompt manner. However, several issues arise when it comes to certain unresolved biological questions, especially in the cancer field. This work provided a discussion with ChatGPT regarding some of the yet-to-be-fully-elucidated conundrums of the role of therapy-induced senescence in cancer treatment and highlights the strengths and weaknesses in utilizing such platforms for analyzing the scientific literature on this topic.

Syntaxin17 Restores Lysosomal Function and Inhibits Pyroptosis Caused by Acinetobacter baumannii

Acinetobacter baumannii (A. baumannii) causes autophagy flux disorder by degrading STX17, resulting in a serious inflammatory response. It remains unclear whether STX17 can alter the inflammatory response process by controlling autolysosome function. This study aimed to explore the role of STX17 in the regulation of pyroptosis induced by A. baumannii. Our findings indicate that overexpression of STX17 enhances autophagosome degradation, increases LAMP1 expression, reduces Cathepsin B release, and improves lysosomal function. Conversely, knockdown of STX17 suppresses autophagosome degradation, reduces LAMP1 expression, augments Cathepsin B release, and accelerates lysosomal dysfunction. In instances of A. baumannii infection, overexpression of STX17 was found to improve lysosomal function and reduce the expression of mature of GSDMD and IL-1β, along with the release of LDH, thus inhibiting pyroptosis caused by A. baumannii. Conversely, knockdown of STX17 led to increased lysosomal dysfunction and further enhanced the expression of mature of GSDMD and IL-1β, and increased the release of LDH, exacerbating pyroptosis induced by A. baumannii. These findings suggest that STX17 regulates pyroptosis induced by A. baumannii by modulating lysosomal function.

The potential role of hydrogen sulfide in regulating macrophage phenotypic changes via PINK1/parkin-mediated mitophagy in sepsis-related cardiorenal syndrome

OBJECTIVE

Sepsis is one of major reasons of cardiorenal syndrome type 5 (CRS-5), resulting in irreversible tissue damage and organ dysfunction. Macrophage has been demonstrated to play key role in the pathophysiology of sepsis, highlighting the need to identify therapeutic targets for modulating macrophage phenotype in sepsis.

METHODS AND RESULTS

In this study, a rapid-releasing hydrogen sulfide (H2S) donor NaSH, and a slow-releasing H2S compound S-propargyl-cysteine (SPRC) which is derived from garlic, have been studied for the immune-regulatory effects on macrophages. The NaSH and SPRC showed the potential to protect the heart and kidney from tissue injury induced by LPS. The immunohistochemistry of F4/80+ revealed that the infiltration of macrophages in the heart and kidney tissues of LPS-treated mice was reduced by NaSH and SPRC. In addition, in the LPS-triggered inflammatory cascade of RAW264.7 macrophage cells, NaSH and SPRC exhibited significantly inhibitory effects on the secretion of inflammatory cytokines, production of reactive oxygen species (ROS), and regulation of the macrophage phenotype from M1-like to M2-like. Moreover, autophagy, a crucial process involved in the elimination of impaired proteins and organelles during oxidative stress and immune response, was induced by NaSH and SPRC in the presence of LPS stimulation. Consequently, there was an increase in the number of mitochondria and an improvement in mitochondrial membrane potential. This process was mainly mediated by PINK1/Parkin pathway mediated mitophagy.

DISCUSSION

These results demonstrated that the immunoregulatory effects of H2S donors were through the PINK1/Parkin-mediated mitophagy pathway. Overall, our study provided a new therapeutic direction in LPS-induced cardiorenal injury.

Friends and Foes: The Ambivalent Role of Autophagy in HIV-1 Infection

Autophagy has emerged as an integral part of the antiviral innate immune defenses, targeting viruses or their components for lysosomal degradation. Thus, successful viruses, like pandemic human immunodeficiency virus 1 (HIV-1), evolved strategies to counteract or even exploit autophagy for efficient replication. Here, we provide an overview of the intricate interplay between autophagy and HIV-1. We discuss the impact of autophagy on HIV-1 replication and report in detail how HIV-1 manipulates autophagy in infected cells and beyond. We also highlight tissue and cell-type specifics in the interplay between autophagy and HIV-1. In addition, we weigh exogenous modulation of autophagy as a putative double-edged sword against HIV-1 and discuss potential implications for future antiretroviral therapy and curative approaches. Taken together, we consider both antiviral and proviral roles of autophagy to illustrate the ambivalent role of autophagy in HIV-1 pathogenesis and therapy.

PPARδ agonist protects against osteoarthritis by activating AKT/mTOR signaling pathway-mediated autophagy

Osteoarthritis (OA) is the most prevalent degenerative joint disease, and PPARs are involved in its pathogenesis; however, the specific mechanisms by which changes in PPARδ impact the OA pathogenesis yet to be discovered. The purpose of this study was to ascertain how PPARδ affects the onset and development of OA. In vitro, we found that PPARδ activation ameliorated apoptosis and extracellular matrix (ECM) degradation in OA chondrocytes stimulated by IL-1β. In addition, PPARδ activation may modulate AKT/mTOR signaling to partially regulate chondrocyte autophagy and apoptosis. In vivo, injection of PPARδ agonist into the articular cavity improved ECM degradation, apoptosis and autophagy in rats OA models generated by destabilization medial meniscus (DMM), eventually delayed degeneration of articular cartilage. Thus, targeting PPARδ for OA treatment may be a possibility.

A matter of new life and cell death: programmed cell death in the mammalian ovary

BACKGROUND

The mammalian ovary is a unique organ that displays a distinctive feature of cyclic changes throughout the entire reproductive period. The estrous/menstrual cycles are associated with drastic functional and morphological rearrangements of ovarian tissue, including follicular development and degeneration, and the formation and subsequent atrophy of the corpus luteum. The flawless execution of these reiterative processes is impossible without the involvement of programmed cell death (PCD).

MAIN TEXT

PCD is crucial for efficient and careful clearance of excessive, depleted, or obsolete ovarian structures for ovarian cycling. Moreover, PCD facilitates selection of high-quality oocytes and formation of the ovarian reserve during embryonic and juvenile development. Disruption of PCD regulation can heavily impact the ovarian functions and is associated with various pathologies, from a moderate decrease in fertility to severe hormonal disturbance, complete loss of reproductive function, and tumorigenesis. This comprehensive review aims to provide updated information on the role of PCD in various processes occurring in normal and pathologic ovaries. Three major events of PCD in the ovary-progenitor germ cell depletion, follicular atresia, and corpus luteum degradation-are described, alongside the detailed information on molecular regulation of these processes, highlighting the contribution of apoptosis, autophagy, necroptosis, and ferroptosis. Ultimately, the current knowledge of PCD aberrations associated with pathologies, such as polycystic ovarian syndrome, premature ovarian insufficiency, and tumors of ovarian origin, is outlined.

CONCLUSION

PCD is an essential element in ovarian development, functions and pathologies. A thorough understanding of molecular mechanisms regulating PCD events is required for future advances in the diagnosis and management of various disorders of the ovary and the female reproductive system in general.

The mechanism of UNC-51-like kinase 1 and the applications of small molecule modulators in cancer treatment

Autophagy is a process of self-renewal in cells, which not only provides the necessary nutrients for cells, but also clears necrotic organelles. Autophagy disorders are closely related to diseases such as cancer. UNC-51-like kinase 1 (ULK1) is a serine/threonine protein kinase that plays a crucial role in receiving input from energy and nutrient sensors, activating autophagy to maintain cellular homeostasis under stressful conditions. In recent years, targeting ULK1 has become a highly promising strategy for cancer treatment. This review introduces the regulatory mechanism of ULK1 in autophagy through the AMPK/mTOR/ULK1 pathway and reviews the research progress of ULK1 activators and inhibitors and their applications in cancer treatment. In addition, we analyze the binding modes between ULK1 and modulators through virtual molecular docking, which will provide a reliable basis and theoretical guidance for the design and development of new therapeutic drugs targeting ULK1.

Qingfei Tongluo Mixture Attenuates Bleomycin-Induced Pulmonary Inflammation and Fibrosis through mTOR-Dependent Autophagy in Rats

As an interstitial fibrosis disease characterized by diffuse alveolitis and structural alveolar disorders, idiopathic pulmonary fibrosis (IPF) has high lethality but lacks limited therapeutic drugs. A hospital preparation used for the treatment of viral pneumonia, Qingfei Tongluo mixture (QFTL), is rumored to have protective effects against inflammatory and respiratory disease. This study aims to confirm whether it has a therapeutic effect on bleomycin-induced IPF in rats and to elucidate its mechanism of action. Male SD rats were randomly divided into the following groups: control, model, CQ + QFTL (84 mg/kg chloroquine (CQ) + 3.64 g/kg QFTL), QFTL-L, M, H (3.64, 7.28, and 14.56 g/kg, respectively) and pirfenidone (PFD 420 mg/kg). After induction modeling and drug intervention, blood samples and lung tissue were collected for further detection. Body weight and lung coefficient were examined, combined with hematoxylin and eosin (H&E) and Masson staining to observe lung tissue lesions. The enzyme-linked immunosorbent assay (ELISA) and the hydroxyproline (HYP) assay kit were used to detect changes in proinflammatory factors (transforming growth factor-β (TGF-β), tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β)) and HYP. Immunohistochemistry and Western blotting were performed to observe changes in proteins related to pulmonary fibrosis (α-smooth muscle actin (α-SMA) and matrix metalloproteinase 12 (MMP12)) and autophagy (P62 and mechanistic target of rapamycin (mTOR)). Treatment with QFTL significantly improved the adverse effects of bleomycin on body weight, lung coefficient, and pathological changes. Then, QFTL reduced bleomycin-induced increases in proinflammatory mediators and HYP. The expression changes of pulmonary fibrosis and autophagy marker proteins are attenuated by QFTL. Furthermore, the autophagy inhibitor CQ significantly reversed the downward trend in HYP levels and α-SMA protein expression, which QFTL improved in BLM-induced pulmonary fibrosis rats. In conclusion, QFTL could effectively attenuate bleomycin-induced inflammation and pulmonary fibrosis through mTOR-dependent autophagy in rats. Therefore, QFTL has the potential to be an alternative treatment for IPF in clinical practice.

Pyrimethamine upregulates BNIP3 to interfere SNARE-mediated autophagosome-lysosomal fusion in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common tumor types and remains a major clinical challenge. Increasing evidence has revealed that mitophagy inhibitors can enhance the effect of chemotherapy on HCC. However, few mitophagy inhibitors have been approved for clinical use in humans. Pyrimethamine (Pyr) is used to treat infections caused by protozoan parasites. Recent studies have reported that Pyr may be beneficial in the treatment of various tumors. However, its mechanism of action is still not clearly defined. Here, we found that blocking mitophagy sensitized cells to Pyr-induced apoptosis. Mechanistically, Pyr potently induced the accumulation of autophagosomes by inhibiting autophagosome-lysosome fusion in human HCC cells. In vitro and in vivo studies revealed that Pyr blocked autophagosome-lysosome fusion by upregulating BNIP3 to inhibit synaptosomal-associated protein 29 (SNAP29)-vesicle-associated membrane protein 8 (VAMP8) interaction. Moreover, Pyr acted synergistically with sorafenib (Sora) to induce apoptosis and inhibit HCC proliferation in vitro and in vivo. Pyr enhances the sensitivity of HCC cells to Sora, a common chemotherapeutic, by inhibiting mitophagy. Thus, these results provide new insights into the mechanism of action of Pyr and imply that Pyr could potentially be further developed as a novel mitophagy inhibitor. Notably, Pyr and Sora combination therapy could be a promising treatment for malignant HCC.

Targeted Mevalonate Pathway and Autophagy in Antitumor Immunotherapy

Tumors of the digestive system are currently one of the leading causes of cancer-related death worldwide. Despite considerable progress in tumor immunotherapy, the prognosis for most patients remains poor. In the tumor microenvironment (TME), tumor cells attain immune escape through immune editing and acquire immune tolerance. The mevalonate pathway and autophagy play important roles in cancer biology, antitumor immunity, and regulation of the TME. In addition, there is metabolic crosstalk between the two pathways. However, their role in promoting immune tolerance in digestive system tumors has not previously been summarized. Therefore, this review focuses on the cancer biology of the mevalonate pathway and autophagy, the regulation of the TME, metabolic crosstalk between the pathways, and the evaluation of their efficacy as targeted inhibitors in clinical tumor immunotherapy.

Diosmin Promotes Myogenesis via Activating the Akt/FOXO1 Pathway to Facilitate the Proliferation of C2C12 Myoblasts

Our previous study with artificial intelligence (AI)-assisted screening found that diosmin, a natural flavonoid extracted from citrus, may affect myoblast proliferation and differentiation. At present, few studies have been conducted regarding the biological function of diosmin in muscle cells. Here, using molecular biological techniques, we found that diosmin elevated the proliferation ability of C2C12 myoblasts via activating the Akt/FOXO1 pathway to promote FOXO1 nuclear export, thus repressing p27 protein expression, increasing CDK2, CDK4, and cyclin D1 and cyclin E1 protein expression and accelerating cell cycle transformation, which contributed to myogenesis. Moreover, diosmin suppressed differentiation of C2C12 myoblasts by delaying the terminal exit of the cell cycle in early differentiated myoblasts and inhibiting autophagic flux in mature myotubes. Furthermore, diosmin promoted myogenesis by activating the Akt/FOXO1 pathway to facilitate myoblast proliferation, which had a positive biological effect on the repair of muscle injury. This study revealed the effect and mechanism of diosmin on skeletal muscle cells and simultaneously provided a new candidate drug for the treatment of myopathy.

Downregulation of TRPC6 regulates ERK1/2 to prevent sublytic C5b‑9 complement complex‑induced podocyte injury through activating autophagy

Idiopathic membranous nephropathy (IMN) is a common glomerular disease, in which 50-60% of patients can progress to end-stage renal disease within 10-20 years, seriously endangering human health. Podocyte injury is the direct cause of IMN. Sublytic C5b-9 complement complex induces damage in podocytes' structure and function. In sublytic C5b-9 treated podocytes, the expression of canonical transient receptor potential 6 (TRPC6) is increased. However, the specific mechanism of TRPC6 in sublytic C5b-9 treated podocytes is unclear. The present study aimed to reveal the effect and mechanism of TRPC6 on sublytic C5b-9-induced podocytes. Normal human serum was stimulated using zymosan to form C5b-9. A lactate dehydrogenase release assay was used to examine C5b-9 cytotoxicity in podocytes. The RNA and protein expression levels were analyzed using reverse transcription-quantitative PCR, western blotting and immunofluorescent assay, respectively. Cell Counting Kit-8 assay and flow cytometry were carried out to test the viability and apoptosis of podocytes, respectively. Transmission electron microscopy was used to observe autophagic vacuole. F-actin was tested through phalloidin staining. Sublytic C5b-9 was deposited and TRPC6 expression was boosted in podocytes stimulated through zymosan activation serum. Knockdown of TRPC6 raised the viability and reduced the apoptosis rate of sublytic C5b-9-induced podocytes. Meanwhile, transfection of small-interfering (si)TRPC6 facilitated autophagy progression and enhanced the activation of cathepsin B/L in sublytic C5b-9-induced podocytes. The phosphorylation level of ERK1/2 was receded in siTRPC6 and sublytic C5b-9 co-treated podocytes. Moreover, the addition of the ERK1/2 activator partially reversed the effect of TRPC6 inhibition on sublytic C5b-9-induced podocytes. TRPC6 knockdown reduced the damage of sublytic C5b-9 to podocytes by weakening the ERK1/2 phosphorylation level to activate autophagy. These results indicated that targeting TRPC6 reduced the injury of sublytic C5b-9 on podocytes.

Exosomes derived from cardiac fibroblasts with angiotensin II stimulation provoke hypertrophy and autophagy inhibition in cardiomyocytes

Although accumulating evidence has revealed that autophagy inhibition contributes to the development of pathological cardiac hypertrophy, the mechanisms leading to declined autophagy activity in the hypertrophic heart remain to be elucidated. Exosomes are known to be important mediators of intercellular communication, and the involvement of exosomes in cardiovascular abnormities has attracted increasing attentions. Cardiac fibroblasts (CFs) are the most abundant cell type in the heart. Here, we investigated the potential role of CFs-derived exosomes in regulating cardiomyocyte hypertrophy and autophagy. Exosomes from rat CFs treated with angiotensin II (Ang II-CFs-exosomes) were collected and characterized. Our experiments showed that these exosomes could induce hypertrophic responses and impair autophagy activity in primary neonatal rat cardiomyocytes (NRCMs). Ang II-CFs-exosomes blocked the autophagic flux of NRCMs via inhibiting the formation of autolysosomes. Moreover, the pro-hypertrophic effects and autophagy inhibition induced by Ang II-CFs-exosomes was validated in mice receiving injection of the exosomes. These findings highlight a novel role of Ang II-CFs-exosomes in suppressing cardiomyocyte autophagy, which may help to better understand the pathogenesis of cardiac hypertrophy.

Improved anti-tumor activity of fluorinated camptothecin derivatives 9-fluorocamptothecin and 7-ethyl-9-fluorocamptothecin on hepatocellular carcinoma by targeting topoisomerase I

Primary liver cancer is one of the most common malignant cancers of the digestive system that lacks effective chemotherapeutic drugs in clinical settings. Camptothecin (CPT) and its derivatives have been approved for cancer treatment; however, their application is limited by their systemic toxicity. For lead optimization in new drug discovery stages, fluorination is an effective and robust approach to increase the bioavailability and optimize the pharmacokinetics of candidate compounds, thereby improving their efficacy. To obtain new and highly active CPT derivatives, we designed, synthesized, and evaluated two new fluorinated CPT derivatives, 9-fluorocamptothecin (A1) and 7-ethyl-9-fluorocamptothecin (A2), in this study. In vitro, A1 and A2 exhibited more robust anti-tumor activity than topotecan (TPT) in various cancer cells, particularly hepatocellular carcinoma (HCC) cells. In vivo, A1 and A2 exhibited greater anti-tumor activity than TPT in both AKT/Met induced primary HCC mouse models and implanted HepG2 cell xenografts. Acute toxicity tests revealed that A1 and A2 were not lethal and did not cause significant body weight loss at high doses. Moreover, A1 and A2 exhibited no significant toxicity in the mouse liver, heart, lung, spleen, kidney, and hematopoietic systems at therapeutic doses. Mechanistically, A1 and A2 blocked HCC cell proliferation by inhibiting the enzymatic activity of Topo I, subsequently inducing DNA damage, cell cycle arrest, and apoptosis. In summary, our results indicate that fluorination improves the anti-tumor activity of CPT while decreasing its toxicity and highlight the application potential of fluorination products A1 and A2 in clinical settings.

Corylifol A ameliorates muscle atrophy by inhibiting TAOK1/p38-MAPK/FoxO3 pathway in cancer cachexia

BACKGROUND

Corylifol A (CYA) is one of the main active components of Psoralea corylifolia L. CYA had been reported to have ameliorating effects on dexamethasone-induced atrophy of C2C12 mouse skeletal myotubes, but its effects on cancer cachexia were unclear. Here, we checked the influence of CYA on muscle atrophy in cancer cachexia mice and tried to clarify its mechanisms.

METHODS

C26 tumour-bearing mice were applied as the animal model to examine the effects of CYA in attenuating cachexia symptoms. The in vitro cell models of TNF-α-induced C2C12 myotubes or ad-mRFP-GFP-LC3B-transfected C2C12 myotubes were used to check the influence of CYA on myotube atrophy based on both ubiquitin proteasome system (UPS) and autophagy-lysosome system. The possible direct targets of CYA were searched using the biotin-streptavidin pull-down assay and then confirmed using the Microscale thermophoresis binding assay. The levels of related signal proteins in both in vitro and in vivo experiments were examined using western blotting and immunocytochemical assay.

RESULTS

The administration of CYA prevented body weight loss and muscle wasting in C26 tumour-bearing mice without affecting tumour growth. At the end of the experiment, the body weight of mice treated with 30 mg/kg of CYA (23.59 ± 0.94 g) was significantly higher than that of the C26 model group (21.66 ± 0.56 g) with P < 0.05. The values of gastrocnemius muscle weight/body weight of mice treated with 15 or 30 mg/kg CYA (0.53 ± 0.02% and 0.54 ± 0.01%, respectively) were both significantly higher than that of the C26 model group (0.45 ± 0.01%) with P < 0.01. CYA decreased both UPS-mediated protein degradation and autophagy in muscle tissues of C26 tumour-bearing mice as well as in C2C12 myotubes treated with TNF-α. The thousand-and-one amino acid kinase 1 (TAOK1) was found to be the direct binding target of CYA. CYA inhibited the activation of TAOK1 and its downstream p38-MAPK pathway thus decreased the level and nuclear location of FoxO3. siRNA knockdown of TAOK1 or regulation of the p38-MAPK pathway using activator or inhibitor could affect the ameliorating effects of CYA on myotube atrophy.

CONCLUSIONS

CYA ameliorates cancer cachexia muscle atrophy by decreasing both UPS degradation and autophagy. The ameliorating effects of CYA on muscle atrophy might be based on its binding with TAOK1 and inhibiting the TAOK1/p38-MAPK/FoxO3 pathway.

Autophagy Modulation as a Potential Therapeutic Strategy in Osteosarcoma: Current Insights and Future Perspectives

Autophagy, the process that enables the recycling and degradation of cellular components, is essential for homeostasis, which occurs in response to various types of stress. Autophagy plays an important role in the genesis and evolution of osteosarcoma (OS). The conventional treatment of OS has limitations and is not always effective at controlling the disease. Therefore, numerous researchers have analyzed how controlling autophagy could be used as a treatment or strategy to reverse resistance to therapy in OS. They highlight how the inhibition of autophagy improves the efficacy of chemotherapeutic treatments and how the promotion of autophagy could prove positive in OS therapy. The modulation of autophagy can also be directed against OS stem cells, improving treatment efficacy and preventing cancer recurrence. Despite promising findings, future studies are needed to elucidate the molecular mechanisms of autophagy and its relationship to OS, as well as the mechanisms underlying the functioning of autophagic modulators. Careful evaluation is required as autophagy modulation may have adverse effects on normal cells, and the optimization of autophagic modulators for use as drugs in OS is imperative.

Increased DNMT1 Involvement in the Activation of LO2 Cell Death Induced by Silver Nanoparticles via Promoting TFEB-Dependent Autophagy

The accumulation of exogenous silver nanoparticles (AgNPs) will terminally bring about liver injury, including cell death, where DNA methylation tends to be a crucial epigenetic modulator. The change in the cell autophagy level verified to be closely associated with hepatocyte death has been followed with wide interest. But the molecular toxicological mechanisms of AgNPs in relation to DNA methylation, autophagy, and cell death remain inconclusive. To address the issue above, in LO2 cells treated with increasing concentrations of AgNPs (0, 5, 10, and 20 μg/mL), a cell cytotoxicity assay was performed to analyze the level of cell death, which also helped to choose an optimal concentration for next experiments. An immunofluorescence assay was used to determine the autophagic flux as well as TFEB translocation, with qRT-PCR and western blot being used to analyze the expression level of autophagy-related genes and proteins. According to our findings, in the determination of cell viability, 20 μg/mL (AgNPs) was adopted as the best working concentration. LO2 cell death, autophagy, and TFEB nuclear translocation were induced by AgNPs, which could be inhibited by lysosome inhibitor chloroquine (CQ) or siRNA specific for TFEB. Moreover, AgNP exposure led to DNA hypermethylation, with DNMT1 taking part mainly, which could be obviously prevented by 5-Aza-2'-deoxycytidine (5-AzaC) or trichostatin A (TSA) treatment or DNMT1 knockout in LO2 cells. Our studies suggest that through TFEB-dependent cell autophagy, increased DNMT1 may facilitate cell death induced by AgNPs.

Glycogen-binding protein STBD1: Molecule and role in pathophysiology

Starch-binding domain-containing protein 1 (STBD1) is a glycogen-binding protein discovered in skeletal muscle gene differential expression that is pivotal to cellular energy metabolism. Recent studies have indicated that STBD1 is involved in many physiological processes, such as glycophagy, glycogen accumulation, and lipid droplet formation. Moreover, dysregulation of STBD1 causes multiple diseases, including cardiovascular disease, metabolic disease, and even cancer. Deletions and/or mutations in STBD1 promote tumorigenesis. Therefore, STBD1 has garnered considerable interest in the pathology community. In this review, we first summarized the current understanding of STBD1, including its structure, subcellular localization, tissue distribution, and biological functions. Next, we examined the roles and molecular mechanisms of STBD1 in related diseases. Based on available research, we discussed the novel function and future of STBD1, including its potential application as a therapeutic target in glycogen-related diseases. Given the significance of STBD1 in energy metabolism, an in-depth understanding of the protein is crucial for understanding physiological processes and developing therapeutic strategies for related diseases.

An Investigation of Structure-Activity Relationships and Cell Death Mechanisms of the Marine Alkaloids Discorhabdins in Merkel Cell Carcinoma Cells

A library of naturally occurring and semi-synthetic discorhabdins was assessed for their effects on Merkel cell carcinoma (MCC) cell viability. The set included five new natural products and semi-synthetic compounds whose structures were elucidated with NMR, HRMS, and ECD techniques. Several discorhabdins averaged sub-micromolar potency against the MCC cell lines tested and most of the active compounds showed selectivity towards virus-positive MCC cell lines. An investigation of structure-activity relationships resulted in an expanded understanding of the crucial structural features of the discorhabdin scaffold. Mechanistic cell death assays suggested that discorhabdins, unlike many other MCC-active small molecules, do not induce apoptosis, as shown by the lack of caspase activation, annexin V staining, and response to caspase inhibition. Similarly, discorhabdin treatment failed to increase MCC intracellular calcium and ROS levels. In contrast, the rapid loss of cellular reducing potential and mitochondrial membrane potential suggested that discorhabdins induce mitochondrial dysfunction leading to non-apoptotic cell death.

Kaempferol induces mitochondrial dysfunction and mitophagy by activating the LKB1/AMPK/MFF pathway in breast precancerous lesions

Kaempferol has been suggested to be an effective anticancer agent in several malignant tumors. However, its function and mechanisms in breast precancerous lesions remain largely elusive. Here, we showed that kaempferol induced excessive mitochondrial fission and mitochondrial damage with activated mitochondrial fission factor (MFF)-mediated dynamin-related protein (DRP) 1 mitochondrial translocation. As a result, the PTEN-induced putative kinase 1 (PINK1)/Parkin signaling pathway was activated, accompanied by excessive mitophagy and reduced mitochondrial mass in cells. We also revealed that kaempferol-induced lethal mitophagy contributed to inhibiting breast precancerous lesion growth in vitro and in vivo. Furthermore, we verified serine/threonine kinase 11 (STK11/LKB1)/AMP-activated protein kinase (AMPK) pathway deficiency in breast precancerous lesions. Moreover, LKB1/AMPK pathway reactivation by kaempferol was required for excessive mitochondrial fission and lethal mitophagy. Taken together, our findings shed new light on the molecular mechanisms related to breast cancer prevention by kaempferol and provide evidence for its potential clinical application.

Identifying a selective inhibitor of autophagy that targets ATG12-ATG3 protein-protein interaction

Macroautophagy/autophagy is a catabolic process by which cytosolic content is engulfed, degraded and recycled. It has been implicated as a critical pathway in advanced stages of cancer, as it maintains tumor cell homeostasis and continuous growth by nourishing hypoxic or nutrient-starved tumors. Autophagy also supports alternative cellular trafficking pathways, providing a mechanism of non-canonical secretion of inflammatory cytokines. This opens a significant therapeutic opportunity for using autophagy inhibitors in cancer and acute inflammatory responses. Here we developed a high throughput compound screen to identify inhibitors of protein-protein interaction (PPI) in autophagy, based on the protein-fragment complementation assay (PCA). We chose to target the ATG12-ATG3 PPI, as this interaction is indispensable for autophagosome formation, and the analyzed structure of the interaction interface predicts that it may be amenable to inhibition by small molecules. We screened 41,161 compounds yielding 17 compounds that effectively inhibit the ATG12-ATG3 interaction in the PCA platform, and which were subsequently filtered by their ability to inhibit autophagosome formation in viable cells. We describe a lead compound (#189) that inhibited GFP-fused MAP1LC3B/LC3B (microtubule associated protein 1 light chain 3 beta) puncta formation in cells with IC50 value corresponding to 9.3 μM. This compound displayed a selective inhibitory effect on the growth of autophagy addicted tumor cells and inhibited secretion of IL1B/IL-1β (interleukin 1 beta) by macrophage-like cells. Compound 189 has the potential to be developed into a therapeutic drug and its discovery documents the power of targeting PPIs for acquiring specific and selective compound inhibitors of autophagy.Abbreviations: ANOVA: analysis of variance; ATG: autophagy related; CQ: chloroquine; GFP: green fluorescent protein; GLuc: Gaussia Luciferase; HEK: human embryonic kidney; IL1B: interleukin 1 beta; LPS: lipopolysaccharide; MAP1LC3B/LC3B: microtubule associated protein 1 light chain 3 beta; PCA: protein-fragment complementation assay; PDAC: pancreatic ductal adenocarcinoma; PMA: phorbol 12-myristate 13-acetate; PPI: protein-protein interaction. VCL: vinculin.

Modulation of Autophagy Direction to Enhance Antitumor Effect of Endoplasmic-Reticulum-Targeted Therapy: Left or Right?

Strategies that induce dysfunction in the endoplasmic reticulum (ER) hold great promise for anticancer therapy, but remain unsatisfactory due to the compensatory autophagy induction after ER disruption. Moreover, as autophagy can either promote or suppress cell survival, which direction of autophagy better suits ER-targeting therapy remains controversial. Here, a targeted nanosystem is constructed, which efficiently escorts anticancer therapeutics into the ER, triggering substantial ER stress and autophagy. Concurrently, an autophagy enhancer or inhibitor is combined into the same nanoparticle, and their impacts on ER-related activities are compared. In the orthotopic breast cancer mouse model, the autophagy enhancer increases the antimetastasis effect of ER-targeting therapy and suppresses over 90% of cancer metastasis, while the autophagy inhibitor has a bare effect. Mechanism studies reveal that further enhancing autophagy accelerates central protein snail family transcriptional repressor 1 (SNAI1) degradation, suppressing downstream epithelial-mesenchymal transition, while inhibiting autophagy does the opposite. With the same trend, ER-targeting therapy combined with an autophagy enhancer provokes stronger immune response and tumor inhibition than the autophagy inhibitor. Mechanism studies reveal that the autophagy enhancer elevates Ca2+ release from the ER and functions as a cascade amplifier of ER dysfunction, which accelerates Ca2+ release, resulting in immunogenic cell death (ICD) induction and eventually triggering immune responses. Together, ER-targeting therapy benefits from the autophagy-enhancing strategy more than the autophagy-inhibiting strategy for antitumor and antimetastasis treatment.

Autophagy up-regulation upon FeHV-1 infection on permissive cells

FeHV-1 is a member of the Herpesviridae family that is distributed worldwide and causes feline viral rhinotracheitis (FVR). Since its relationship with the autophagic process has not yet been elucidated, the aim of this work was to evaluate the autophagy mediated by FeHV-1 and to determine its proviral or antiviral role. Our data showed that autophagy is induced by FeHV-1 in a viral dose and time-dependent manner. Phenotypic changes in LC3/p62 axis (increase of LC3-II and degradation of p62) were detected from 12 h post infection using western blot and immuno-fluorescence assays. In a second step, by using late autophagy inhibitors and inducers, the possible proviral role of autophagy during FeHV-1 infection was investigating by assessing the effects of each chemical in terms of viral yield, cytotoxic effects, and expression of viral glycoproteins. Our findings suggest that late-stage autophagy inhibitors (bafilomycin and chloroquine) have a negative impact on viral replication. Interestingly, we observed an accumulation of gB, a viral protein, when cells were pretreated with bafilomycin, whereas the opposite effect was observed when an autophagy inducer was used. The importance of autophagy during FeHV-1 infection was further supported by the results obtained with ATG5 siRNA. In summary, this study demonstrates FeHV-1-mediated autophagy induction, its proviral role, and the negative impact of late autophagy inhibitors on viral replication.

USP1-Associated Factor 1 Modulates Japanese Encephalitis Virus Replication by Governing Autophagy and Interferon-Stimulated Genes

Japanese encephalitis virus (JEV) is a typical mosquito-borne flavivirus that can cause central nervous system diseases in humans and animals. Host factors attempt to limit virus replication when the viruses invade the host by using various strategies for replication. It is essential to clarify the host factors that affect the life cycle of JEV and explore its underlying mechanism. Here, we found that USP1-associated factor 1 (UAF1; also known as WD repeat-containing protein 48) modulated JEV replication. We found that JEV propagation significantly increased in UAF1-depleted Huh7 cells. Moreover, we found that knockdown of UAF1 activated cell autophagic flux in further functional analysis. Subsequently, we demonstrated that autophagy can be induced by JEV, which promotes viral replication by inhibiting interferon-stimulated gene (ISG) expression in Huh7 cells. The knockdown of UAF1 reduced ISG expression during JEV infection. To explore the possible roles of autophagy in UAF1-mediated inhibition of JEV propagation, we knocked out ATG7 to generate autophagy-deficient cells and found that depletion of UAF1 failed to promote JEV replication in ATG7 knockout cells. Moreover, in ATG7-deficient Huh7 cells, interference with UAF1 expression did not lead to the induction of autophagy. Taken together, these findings indicate that UAF1 is a critical regulator of autophagy and reveal a mechanism by which UAF1 knockdown activates autophagy to promote JEV replication. IMPORTANCE Host factors play an essential role in virus replication and pathogenesis. Although UAF1 is well known to form complexes with ubiquitin-specific proteases, little is known about the function of the UAF1 protein itself. In this study, we confirmed that UAF1 is involved in JEV replication. Notably, we discovered a novel function for UAF1 in regulating autophagy. Furthermore, we demonstrated that UAF1 modulated JEV replication through its autophagy regulation. This study is the first description of the novel function of UAF1 in regulating autophagy, and it clarifies the underlying mechanism of the antiviral effect of UAF1 against JEV. These results provide a new mechanistic insight into the functional annotation of UAF1 and provide a potential target for increasing virus production during vaccine production.

NDV-induced autophagy enhances inflammation through NLRP3/Caspase-1 inflammasomes and the p38/MAPK pathway

Newcastle disease (ND), caused by the Newcastle disease virus (NDV), is a highly virulent infectious disease of poultry. Virulent NDV can cause severe autophagy and inflammation in host cells. While studies have shown a mutual regulatory relationship between autophagy and inflammation, this relationship in NDV infection remains unclear. This study confirmed that NDV infection could trigger autophagy in DF-1 cells to promote cytopathic and viral replication. NDV-induced autophagy was positively correlated with the mRNA levels of inflammatory cytokines such as IL-1β, IL-8, IL-18, CCL-5, and TNF-α, suggesting that NDV-induced autophagy promotes the expression of inflammatory cytokines. Further investigation demonstrated that NLRP3 protein expression, Caspase-1 activity, and p38 phosphorylation level positively correlated with autophagy, suggesting that NDV-induced autophagy could promote the expression of inflammatory cytokines through NLRP3/Caspase-1 inflammasomes and p38/MAPK pathway. In addition, NDV infection also triggered mitochondrial damage and mitophagy in DF-1 cells, but did not result in a large leakage of reactive oxygen species (ROS) and mitochondrial DNA (mtDNA), indicating that mitochondrial damage and mitophagy do not contribute to the inflammation response during NDV infection.

Cyclic helix B peptide alleviates proinflammatory cell death and improves functional recovery after traumatic spinal cord injury

BACKGROUND

Necroptosis and pyroptosis, two types of proinflammatory programmed cell death, were recently found to play important roles in spinal cord injury (SCI). Moreover, cyclic helix B peptide (CHBP) was designed to maintain erythropoietin (EPO) activity and protect tissue against the adverse effects of EPO. However, the protective mechanism of CHBP following SCI is still unknown. This research explored the necroptosis- and pyroptosis-related mechanism underlying the neuroprotective effect of CHBP after SCI.

METHODS

Gene Expression Omnibus (GEO) datasets and RNA sequencing were used to identify the molecular mechanisms of CHBP for SCI. A mouse model of contusion SCI was constructed, and HE staining, Nissl staining, Masson staining, footprint analysis and the Basso Mouse Scale (BMS) were applied for histological and behavioural analyses. qPCR, Western blot analysis, immunoprecipitation and immunofluorescence were utilized to analyse the levels of necroptosis, pyroptosis, autophagy and molecules associated with the AMPK signalling pathway.

RESULTS

The results revealed that CHBP significantly improved functional restoration, elevated autophagy, suppressed pyroptosis, and mitigated necroptosis after SCI. 3-Methyladenine (3-MA), an autophagy inhibitor, attenuated these beneficial effects of CHBP. Furthermore, CHBP-triggered elevation of autophagy was mediated by the dephosphorylation and nuclear translocation of TFEB, and this effect was due to stimulation of the AMPK-FOXO3a-SPK2-CARM1 and AMPK-mTOR signalling pathways.

CONCLUSION

CHBP acts as a powerful regulator of autophagy that improves functional recovery by alleviating proinflammatory cell death after SCI and thus might be a prospective therapeutic agent for clinical application.

Role of T cells in the pathogenesis of systemic lupus erythematous: Focus on immunometabolism dysfunctions

Evidence demonstrates that T cells are implicated in developing SLE, and each of them dominantly uses distinct metabolic pathways. Indeed, intracellular enzymes and availability of specific nutrients orchestrate fate of T cells and lead to differentiation of regulatory T cells (Treg), memory T cells, helper T cells, and effector T cells. The function of T cells in inflammatory and autoimmune responses is determined by metabolic processes and activity of their enzymes. Several studies were conducted to determine metabolic abnormalities in SLE patients and clarify how these modifications could control the functions of the involved T cells. Metabolic pathways such as glycolysis, mitochondrial pathways, oxidative stress, mTOR pathway, fatty acid and amino acid metabolisms are dysregulated in SLE T cells. Moreover, immunosuppressive drugs used in treating autoimmune diseases, including SLE, could affect immunometabolism. Developing drugs to regulate autoreactive T cell metabolism could be a promising therapeutic approach for SLE treatment. Accordingly, increased knowledge about metabolic processes paves the way to understanding SLE pathogenesis better and introduces novel therapeutic options for SLE treatment. Although monotherapy with metabolic pathways modulators might not be sufficient to prevent autoimmune disease, they may be an ideal adjuvant to reduce administration doses of immunosuppressive drugs, thus reducing drug-associated adverse effects. This review summarized emerging data about T cells that are involved in SLE pathogenesis, focusing on immunometabolism dysregulation and how these modifications could affect the disease development.

Self-assembled nanocomposites of carboxymethyl β-dextran/protamine sulfate for enhanced chemotherapeutic drug sensitivity of triple-negative breast cancer by autophagy inhibition via a ternary collaborative strategy

Drug resistance in cancer chemotherapy is a major confounding factor affecting the effectiveness of chemotherapeutic agents, thereby leading to poor clinical outcomes. Most chemotherapeutic drugs can induce protective autophagy and increase the resistance of tumors to chemotherapeutic drugs and reduce effective drug delivery to tumor cells. In this study, a tri-drug nanocomposite (NP) delivery system was devised using carboxymethyl β-dextran (CMD) and protamine sulfate (PS), two natural materials with good bio-compatibility. They were designed to carry the chemotherapeutic drug docetaxel (DTX), the autophagy inhibitor chloroquine (CQ), and Atg5 siRNA to cancer cells. The CQ + DTX + Atg5 siRNA NPs was driven by electrostatic interaction and self-assembly methods. The breast cancer cell line MDA-MB-231 was used for both cell culture and establishing mouse xenograft model. Our findings demonstrated that CQ and Atg5 siRNA encapsulated in NPs could enhance the sensitivity of tumor cells to DTX. The NPs exhibited remarkable considerable therapeutic effects for treating triple-negative breast cancer (TNBC) and good biosafety. Therefore, we established a novel multifunctional nanoplatform based on CMD and PS that enhances chemotherapeutic drug sensitivity through an autophagy inhibition strategy, providing new opportunities to overcome conventional drug resistance and enhance therapeutic efficiency against TNBC.

Inhibition of Ceramide Synthesis Attenuates Chronic Ethanol Induced Cardiotoxicity by Restoring Lysosomal Function and Reducing Necroptosis

AIMS

Chronic alcohol misuse could cause alcoholic cardiomyopathy (ACM), and the specific mechanisms remained largely unknown. In this study, we aimed to explore the effects of endogenous ceramides on chronic ethanol-induced myocardial injury or cell loss (e.g. necroptosis).

METHODS

We established chronic alcohol intoxication models in vivo (male C57BL/6 mice) and in vitro (H9c2 cardiomyoblasts). The ceramide profiles were analyzed in mice myocardium and cultured cardiomyocytes. Further research on the role of ceramides and underlying signaling pathways was carried out in H9c2 cells.

RESULTS AND CONCLUSIONS

The ceramide profiles analysis revealed increased long and very long-chain ceramides in alcoholic myocardium and ethanol-treated cardiomyocytes. Next, we proved that endogenous ceramide inhibition could reduce necroptosis and alleviate cardiomyocytes injury as suggested by decreased levels of p-RIPK1, p-RIPK3 and p-MLKL proteins and cardiac injury factors expression. Furthermore, we found that lysosomal dysfunction also contributed to alcohol-induced cardiac damage and inhibiting ceramide biosynthesis could repaired this to some extent. Cells studies with exogenous C6 ceramide confirmed the pleotropic roles of ceramide in myocardial damage by causing both necroptosis and lysosomal dysfunction. Finally, our data suggested that lysosomal dysfunction could sensitize cardiomyocytes to induction of necroptosis due to the restriction on degradation of RIPK1/RIPK3 proteins. In conclusion, chronic ethanol treatment boosted myocardial ceramide synthesis in animal hearts and cultured cardiomyocytes. Moreover, ceramides exerted crucial roles in the intrinsic signaling pathways of alcohol-induced cardiotoxicity. Targeting ceramide biosynthesis to simultaneously attenuate necroptosis and lysosomal dysfunction might be a novel strategy for preventing alcoholic cardiotoxicity.

Autophagy in protists and their hosts: When, how and why?

Pathogenic protists are a group of organisms responsible for causing a variety of human diseases including malaria, sleeping sickness, Chagas disease, leishmaniasis, and toxoplasmosis, among others. These diseases, which affect more than one billion people globally, mainly the poorest populations, are characterized by severe chronic stages and the lack of effective antiparasitic treatment. Parasitic protists display complex life-cycles and go through different cellular transformations in order to adapt to the different hosts they live in. Autophagy, a highly conserved cellular degradation process, has emerged as a key mechanism required for these differentiation processes, as well as other functions that are crucial to parasite fitness. In contrast to yeasts and mammals, protist autophagy is characterized by a modest number of conserved autophagy-related proteins (ATGs) that, even though, can drive the autophagosome formation and degradation. In addition, during their intracellular cycle, the interaction of these pathogens with the host autophagy system plays a crucial role resulting in a beneficial or harmful effect that is important for the outcome of the infection. In this review, we summarize the current state of knowledge on autophagy and other related mechanisms in pathogenic protists and their hosts. We sought to emphasize when, how, and why this process takes place, and the effects it may have on the parasitic cycle. A better understanding of the significance of autophagy for the protist life-cycle will potentially be helpful to design novel anti-parasitic strategies.

USP10 Alleviates Palmitic Acid-induced Steatosis through Autophagy in HepG2 Cells

BACKGROUND AND AIMS

Nonalcoholic fatty liver disease (NAFLD) is a common chronic liver disease caused by over-nutrition. Impaired autophagy is closely related to NAFLD progression. Recently, ubiquitin-specific peptidase-10 (USP10) was reported to ameliorate hepatic steatosis, but the underlying mechanism is still unclear. In view of the potential effects of USP10 on autophagy, we investigated whether USP10 alleviated steatosis through autophagy.

METHODS

HepG2 cells were treated with palmitic acid (PA) to model NAFLD in vitro. Lentivirus was used to regulate USP10 level in cells. Autophagic regulators were used to autophagic progression in cells. Western blotting, real-time fluorescence quantitative polymerase chain reaction, lipid drop staining and immunofluorescent staining were performed to determine the effect of USP10 on lipid autophagy. Student's t-test and Tukey's post hoc test were used to compare the means among groups.

RESULTS

PA induced cellular steatosis with dependance on autophagy. USP10 overexpression alleviated PA-induced steatosis, restored autophagic activity, promoted autophagic flux, including synthesis and degradation of autophagosomes, and lipid-targeted autophagy. In the presence of autophagy inhibitors, the protective effectiveness of USP10 on steatosis decreased. Furthermore, the specific inhibitor to C-jun N-terminal protein kinase-1 (JNK1), DB07268, abolished USP10-induced autophagy. However, during early stage inhibition of JNK1, compensatory expression of tuberous sclerosis complex-2 (TSC2) maintained autophagy. The degree of TSC2-to-JNK1 compensation was positively associated with USP10 level. Functionally, JNK1 and TSC2 were involved in the lipid-lowering effect of USP10.

CONCLUSIONS

USP10 alleviated hepatocellular steatosis in autophagy-dependent manner. JNK1/TSC2 signaling pathways were required for USP10-induced autophagy.

MTSS1 curtails lung adenocarcinoma immune evasion by promoting AIP4-mediated PD-L1 monoubiquitination and lysosomal degradation

Immune checkpoint blockade (ICB) therapy targeting PD-1/PD-L1 has shown durable clinical benefits in lung cancer. However, many patients respond poorly to ICB treatment, underscoring an incomplete understanding of PD-L1 regulation and therapy resistance. Here, we find that MTSS1 is downregulated in lung adenocarcinoma, leading to PD-L1 upregulation, impairment of CD8⁺ lymphocyte function, and enhanced tumor progression. MTSS1 downregulation correlates with improved ICB efficacy in patients. Mechanistically, MTSS1 interacts with the E3 ligase AIP4 for PD-L1 monoubiquitination at Lysine 263, leading to PD-L1 endocytic sorting and lysosomal degradation. In addition, EGFR-KRAS signaling in lung adenocarcinoma suppresses MTSS1 and upregulates PD-L1. More importantly, combining AIP4-targeting via the clinical antidepressant drug clomipramine and ICB treatment improves therapy response and effectively suppresses the growth of ICB-resistant tumors in immunocompetent mice and humanized mice. Overall, our study discovers an MTSS1-AIP4 axis for PD-L1 monoubiquitination and reveals a potential combinatory therapy with antidepressants and ICB.

Autophagy and the Insulin-like Growth Factor (IGF) System in Colonic Cells: Implications for Colorectal Neoplasia

Colorectal cancer (CRC) is one of the most common human malignancies worldwide. Along with apoptosis and inflammation, autophagy is one of three important mechanisms in CRC. The presence of autophagy/mitophagy in most normal mature intestinal epithelial cells has been confirmed, where it has mainly protective functions against reactive oxygen species (ROS)-induced DNA and protein damage. Autophagy regulates cell proliferation, metabolism, differentiation, secretion of mucins and/or anti-microbial peptides. Abnormal autophagy in intestinal epithelial cells leads to dysbiosis, a decline in local immunity and a decrease in cell secretory function. The insulin-like growth factor (IGF) signaling pathway plays an important role in colorectal carcinogenesis. This is evidenced by the biological activities of IGFs (IGF-1 and IGF-2), IGF-1 receptor type 1 (IGF-1R) and IGF-binding proteins (IGF BPs), which have been reported to regulate cell survival, proliferation, differentiation and apoptosis. Defects in autophagy are found in patients with metabolic syndrome (MetS), inflammatory bowel diseases (IBD) and CRC. In neoplastic cells, the IGF system modulates the autophagy process bidirectionally. In the current era of improving CRC therapies, it seems important to investigate the exact mechanisms not only of apoptosis, but also of autophagy in different populations of tumor microenvironment (TME) cells. The role of the IGF system in autophagy in normal as well as transformed colorectal cells still seems poorly understood. Hence, the aim of the review was to summarize the latest knowledge on the role of the IGF system in the molecular mechanisms of autophagy in the normal colon mucosa and in CRC, taking into account the cellular heterogeneity of the colonic and rectal epithelium.

Exploring the repositioning of the amodiaquine as potential drug against visceral leishmaniasis: The in vitro effect against Leishmania infantum is associated with multiple mechanisms, involving mitochondria dysfunction, oxidative stress and loss of cell cycle control

Visceral leishmaniasis (VL) is a progressive, debilitating, and potentially fatal disease if left untreated. As a neglected tropical disease (NTD), the available treatment is restricted to a few drugs, which typically must be administered over a long period but are associated with serious adverse effects and have variability in efficacy. In this sense, drug repositioning has been considered an excellent strategy in the search for alternative treatments, especially in reducing the time and cost of the research. In this work, the repositioning potential of amodiaquine (AQ), a well-known antimalarial drug, was investigated for the treatment of VL. AQ showed significant and selective activity against promastigotes (IC₅₀ = 11.6 μg/mL) and intracellular amastigotes (IC₅₀ = 2.4 μg/mL) of L. infantum, being 10 times more destructive to the intracellular parasites than the host cell. In addition, pre-treatment of macrophages with AQ caused a significant reduction in the infection index, indicating a prophylactic effect of this drug. SEM images showed that AQ induces strong shape alterations of the promastigotes with an increase in cell volume with rounding and ribbing (vertical ridges), as well as a shortened flagellum. In addition, AQ induced depolarization of the ΔΨm, an increase in ROS and neutral lipids levels, and changes in the cell cycle in promastigotes, without alterations to the permeability of the parasite plasma membrane. L. infantum-infected macrophages treated with AQ induced the activation of oxidative mechanisms by infected host cells, with an increase in ROS and NO levels. Finally, in vitro interactions between AQ and miltefosine were found to have an additive effect in both biological stages of the parasite, with the ∑FIC₅₀ values ranging from 0.74 to 1.16 μg/mL and 0.54-1.11 μg/mL for promastigotes and intracellular amastigotes, respectively. Overall, these data highlight the utility of drug repurposing and indicate future preclinical testing for AQ itself or in combination as a potential VL treatment.