Autophagy as a decisive process for cell death

Live and let die: analyzing ultrastructural features in cell death

Cell death is an important process that supports morphogenesis during development and tissue homeostasis during adult life by removing damaged or unwanted cells and its dysregulation is associated with numerous disease states. There are different pathways through which a cell can undergo cell death, each relying on peculiar molecular mechanisms and morpho-ultrastructural features. To date, however, while molecular and genetic approaches have been successfully integrated into the field, cell death studies rarely incorporate ultrastructural data from electron microscopy. This review article reports a gallery of original transmission electron microscopy images to describe the ultrastructural features of cells undergoing different types of cell death programs, including necrosis, apoptosis, autophagy, mitotic catastrophe, ferroptosis, methuosis, and paraptosis. TEM has been an important technology in cell biology for well over 50 years and still continues to offer significant advantages in the area of cell death research. TEM allows detailed characterization of the ultrastructural changes within the cell, such as the alteration of organelles and subcellular structures, the nuclear reorganization, and the loss of membrane integrity that enable a distinction between the different forms of cell death based on morphological criteria. Possible pitfalls are also described.

Study on the Effect of Quinoa Saponins on Human Colon Cancer HT-29 Cells

Quinoa saponins can inhibit the survival of specific cancer cells. However, there is still a lack of systematic research on the effects of quinoa saponins on colon cancer cells. This experiment confirmed that quinoa saponins prevented human colon cancer HT-29 cells from growing in vitro. The MTT experiment revealed that quinoa saponins significantly decreased the proliferative vitality of HT-29 cells. In comparison to the control group, the proportion of cell number in the G0/G1 phase increased by 22.97% and the rate of apoptosis increased by 22.55% after treating cells with quinoa saponins (40 μg/mL). By regulating the expression of Cyclin D1 and p21, it caused the cell cycle to be blocked in the G0/G1 phase. It also promoted the expression of Caspase3 and Bax while suppressing the expression of Bcl-2, which led to the apoptosis of HT-29 cells. In addition, quinoa saponins caused cells to undergo autophagy by upregulating the expression of LC-3II and Beclin1, while the addition of autophagy inhibitors significantly reduced the inhibitory effect on cell proliferation. Finally, the migration of HT-29 cells was also inhibited by quinoa saponins. After treating cells with quinoa saponins (40 μg/mL), compared with that in the control group, the wound healing rate of cells decreased by 38.21% and the migration ability decreased by 69.48%. The potential mechanism could be connected to increasing E-cadherin expression while decreasing N-cadherin expression. Importantly, all of these changes induced by quinoa saponins were dose dependent. Overall, these findings give a scientific basis for the anticancer mechanism of quinoa saponins.

Dead or Alive: Exploratory Analysis of Selected Apoptosis- and Autophagy-Related Proteins in Human Endometrial Stromal Cells of Fertile Females and Their Potential Role During Embryo Implantation

To date, very little is known about how apoptosis and autophagy affect human endometrial stromal cells (ESCs), particularly how these processes might determine the depth of implantation in humans. Before investigating how apoptosis and autophagy might modulate the implantation process in an infertile population, it is necessary to clarify how these processes are regulated in healthy individuals. This study examined the protein expression related to apoptosis and autophagy in primary ESCs from fertile women, particularly in the context of decidualization and embryo contact, using Western blot analysis. This study evaluated the protein expression of apoptosis receptors and autophagy markers during the window of implantation. Previous research has shown that a syndecan 1 (Sdc1) knockdown (kd) in endometrial stromal cell lines increased the sensitivity to apoptosis induced by embryonic stimuli. We aimed to determine if this effect is also present in primary cells and if Sdc1 regulates autophagy. The expression of autophagy- and apoptosis-associated proteins in primary ESCs from fertile individuals was investigated in this preliminary study, along with their impact on the process of human embryo implantation. During decidualization and exposure to embryo contact, we observed an upregulation of apoptosis- and autophagy-related proteins in ESCs. Decidualized ESCs exhibited higher levels of apoptosis receptors, indicating increased sensitivity to embryo-induced apoptosis. Additionally, the increase in basal autophagy proteins suggests a significant role in the implantation process. Sdc1 is potentially involved in regulating apoptosis and autophagy, demonstrating its possible role in modulating implantation-related cell activities. These findings suggest a complex interplay between apoptosis and autophagy in regulating human embryo implantation. The changes in the expression of apoptotic and autophagic proteins in ESCs after decidualization and upon contact with the embryo provide new insights into the cellular mechanisms that underlie successful implantation. These results have potential implications for understanding the pathophysiology of implantation disorders and improving assisted reproductive technologies. The first results of this pilot study need to be verified with a larger sample size in the future.

The Critical Role of Autophagy and Phagocytosis in the Aging Brain

As the organism ages, there is a decline in effective energy supply, and this retards the ability to elaborate new proteins. The consequences of this are especially marked in the gradual decline in brain function. The senescence of cells and their constituent organelles is ultimately the cause of aging of the entire nervous system. What is less immediately obvious is that brain aging is also accompanied by the failure of catabolic events that lead to the removal of non-functional cells and ineffective subcellular components. The removal of non-working cellular and subcellular elements within the brain is essential in order to allow the appearance of fresh cells and organelles with a full range of capacities. Thus, the maintenance of operative mechanisms for the dispersal of failed tissue components is important, and its diminished capacity with aging is a significant contributory factor to the onset and progression of age-related neurological disorder. This report discusses the mechanisms underlying autophagy and phagocytosis and how these can be adversely modulated as aging proceeds. The means by which the effective recycling of cellular components may be reinstated in the aged brain are considered.

Redox homeostasis of one-carbon metabolism-dependent reprogramming is critical for RCC progression under exogenous serine/glycine-deprived conditions

BACKGROUND

Serine/glycine are critical for the growth and survival of cancer cells. Some cancer cells are more dependent on exogenous serine/glycine than endogenously synthesized serine/glycine. However, the function and underlying mechanisms of exogenous serine/glycine in renal cell carcinoma (RCC) remain unclear.

METHODS

We conducted a comprehensive assessment of RCC progression under conditions of exogenous serine/glycine deprivation and explored the underlying mechanism via immunofluorescence, autophagic flux analysis, extracellular acidification rate (ECAR) and oxygen consumption rate (OCR) measurements.

RESULTS

The expression of the serine synthesis pathway enzymes was decreased in RCC specimens, the de novo serine synthesis pathway (SSP) was reduced in RCC. And the levels of endogenously synthesized serine/glycine were little. Yet, the exogenous serine/glycine deprivation significantly inhibited the growth of RCC cells both in vitro and in vivo, indicating that exogenous serine/glycine were important for RCC progression. Mechanistically, the deprivation of exogenous serine/glycine disrupted one-carbon metabolism and increased the ratio of NAD(P)+/NAD(P)H, resulting in the accumulation of reactive oxygen species (ROS) and oxidative stress, which induced autophagic flux and enhanced lysosome membrane permeabilization (LMP), leading to the release of lysosomal cathepsins into the cytoplasm, which ultimately triggered lysosomal dependent cell death (LDCD) and inhibited the progression of RCC.

CONCLUSIONS

Our results indicate that exogenous serine/glycine are critical for RCC progression by maintaining one-carbon metabolism-dependent redox homeostasis, which provides new insights for the development of dietary serine/glycine starvation-based therapeutic approaches for RCC.

Castration-resistant prostate cancer is resensitized to androgen deprivation by autophagy-dependent apoptosis induced by blocking SKP2

Resistance to androgen receptor (AR)-targeted therapies for prostate cancer (PCa) is characteristic of an aggressive subtype called castration-resistant prostate cancer (CRPC) and is often associated with tumor relapse. Both relapse and poor prognosis in patients with CRPC are associated with increased abundance of the E3 ubiquitin ligase SKP2. Therefore, we investigated the therapeutic potential of combined inhibition of AR and SKP2 for CRPC. We found that combined targeting of AR and SKP2 with small-molecule inhibitors decreased proliferation in two CRPC cell lines in culture and in xenografts in humanized mice. Furthermore, combined therapy in mice markedly decreased the growth of Pten/Trp53 double-knockout tumors, a particularly invasive model of CRPC, whereas disruption of either AR or SKP2 alone only modestly suppressed their growth. Mechanistically, the inhibition of SKP2 in CRPC cells induced autophagy-dependent apoptosis and promoted luminal-associated phenotypes, which promoted responsiveness to AR-targeted therapy. These effects were further enhanced by coinhibition of AR and were not induced by the AR inhibitor alone. Our findings indicate that targeting both AR and SKP2 signaling pathways is necessary to treat CRPC.

Elucidation of cytotoxicity of α-Synuclein fibrils on immune cells

Progressive aggregation of α-synuclein (α-Syn), a small cytosolic protein involved in cell vesicle trafficking, in the midbrain, hypothalamus, and thalamus is linked to Parkinson's disease (PD). Amyloid oligomers and fibrils formed as a result of such aggregation are highly toxic to neurons. However, it remains unclear whether amyloid-induced toxicity of neurons is the primary mechanism of the progressive neurodegeneration observed upon PD. In the current study, we investigated cytotoxicity exerted by α-Syn fibrils formed in the lipid-free environment, as well as in the presence of two phospholipids, on macrophages, dendritic cells, and microglia. We found that α-Syn fibrils are far more toxic to dendritic cells and microglia compared to neurons. We also observe low toxicity levels of such amyloids to macrophages. Real-time polymerase chain reaction (RT-PCR) results suggest that toxicity of amyloids aggregates is linked to the levels of autophagy in cells. These results suggest that a strong impairment of the immune system in the brain may be the first stop of neurodegenerative processes that are taking place upon the onset of PD.

A FRET Autophagy Imaging Platform by Macrocyclic Amphiphile

Autophagy is a ubiquitous process of organelle interaction in eukaryotic cells, in which various organelles or proteins are recycled and operated through the autophagy pathway to ensure nutrient and energy homeostasis. Although numerous fluorescent probes have been developed to image autophagy, these environment-responsive probes suffer from inherent deficiencies such as inaccuracy and limited versatility. Here, we present a modular macrocyclic amphiphile Förster Resonance Energy Transfer (FRET) platform (SC6A12C/NCM, SN), constructed through the amphiphilic assembly of sulfonatocalix[6]arene (SC6A12C) with N-cetylmorpholine (NCM) for lysosome targeting. The hydrophobic fluorophore BPEA (FRET donor) was entrapped within the inner hydrophobic phase and showed strong fluorescence emission. Attributed to the broad-spectrum encapsulation of SC6A12C, three commercially available organelle probes (Mito-Tracker Red, ER Tracker Red, and RhoNox-1) were selected as SC6A12C guests (FRET acceptors). During autophagy process, the formation of intracellular host-guest complexes leads to strong FRET signal, allowing us to visualize the fusion of mitochondria, endoplasmic reticulum, and Golgi apparatus with lysosomes, respectively. This study provides a versatile and accessible platform for imaging organelle autophagy.

Lysosomal gene ATP6AP1 promotes doxorubicin resistance via up-regulating autophagic flux in breast cancer

BACKGROUND

Breast cancer remains the most prevalent malignancy in women. Chemotherapy is the primary systemic treatment modality, and the effectiveness of treatment is often hampered by chemoresistance. Autophagy has been implicated in promoting chemoresistance, as elevated autophagic flux supports tumor cell survival under therapeutic stress. Since lysosomes are essential for the completion of autophagy, their role in autophagy-related chemoresistance has been insufficiently studied. This study aims to elucidate the role of the lysosomal gene ATP6AP1 in promoting chemoresistance in breast cancer by upregulating autophagic flux.

METHODS

Doxorubicin-induced cell death was assessed by cytotoxicity, flow cytometry, lactate dehydrogenase (LDH) release assays in various breast cancer cell lines. Autophagic flux was assessed with western blot and the mRFP-GFP-LC3 fluorescence imaging. Breast cancer cells were infected with shRNA lentivirus targeting ATP6AP1, allowing investigation its tole in doxorubicin-induced cell death. ATP6AP1 expression and its association with prognosis were evaluated using public databases and immunohistochemistry.

RESULTS

Doxorubicin-induced cell death in breast cancer cells is negatively correlated with increased autophagic flux and lysosomal acidification. The lysosomal gene ATP6AP1, which plays a role in autophagic processes, is upregulated in breast cancer tissues. Knocking down ATP6AP1 reduces autophagy-mediated doxorubicin resistance by inhibiting autophagic flux and lysosomal acidification in breast cancer cells. Data analysis from public databases and our cohort indicate that elevated ATP6AP1 expression correlates with poor response to doxorubicin-based neoadjuvant chemotherapy (NAC) and worse prognosis.

CONCLUSIONS

Doxorubicin-induced cytotoxicity is associated with autophagy flux in breast cancer. The lysosomal gene ATP6AP1 facilitates autolysosome acidification and contributes to doxorubicin resistance in breast cancer.

In vitro effects of l-kynurenine and quinolinic acid on adhesion, migration and apoptosis in B16 F10 melanoma cells

INTRODUCTION

The inhibition of melanoma adhesion through adhesion molecules, such as integrins and E-cadherin, may represent a promising strategy for managing melanoma metastasis. Compounds, namely l-kynurenine (L-kyn) and quinolinic acid (Quin), previously displayed anti-cancer effects at half-maximal inhibitory concentration (IC50) against B16 F10 melanoma cells in vitro. However, the role of these compounds in B16 F10 melanoma cell adhesion, migration and apoptosis remain unknown.

METHODS

Post-exposure to the compounds, flow cytometry was used to analyse the expression of very late antigen-5 (VLA-5), E-cadherin and cleaved caspase-3 in B16 F10 melanoma and RAW 264.7 murine macrophage cells. An adhesion assay was used to quantify the adhesion of both cell lines to vitronectin. A scratch migration assay was used to measure the possible inhibition of cell migration in B16 F10 cells in response to L-kyn and Quin.

RESULTS

In both B16 F10 and RAW 264.7 cells, neither L-kyn nor Quin induced significant effects on VLA-5 expression or cell adhesion to vitronectin. In B16 F10 cells, both L-kyn and Quin elevated E-cadherin expression and displayed a trend of suppressed migration. However, only L-kyn elevated E-cadherin in RAW 264.7 cells. L-kyn induced apoptosis by elevating cleaved caspase-3 expression in both cell lines.

CONCLUSION

L-kyn and Quin demonstrated promising antimetastatic effects in their ability to elevate E-cadherin expression and induce apoptosis in B16 F10 melanoma cells. However, these effects did not occur in response to vitronectin or VLA-5 integrin alterations. Furthermore, it cannot be excluded that L-kyn also induced apoptosis in RAW 264.7 cells. As such, these effects should be confirmed in additional control cell lines and substantiated with in vivo models.

TMEM164 promotes ferroptosis by selectively mediating ATG5-dependent autophagosome formation to inhibit the progression of LUAD

The study focuses on lung adenocarcinoma (LUAD), a predominant type of lung cancer. Despite advancements in diagnostics and molecular therapies, treatment remains challenging due to its low five-year survival rate. This study aims to investigate the role of the transmembrane protein TMEM164 in ferroptosis and anti-tumor immunity in LUAD, and to evaluate its potential as a therapeutic target. Through cellular experiments (such as QPCR, WB, CCK-8, EdU, Transwell, flow cytometry, CO-IP) and animal model experiments (including HE staining and IHC analysis), the relationship between TMEM164 expression and LUAD progression was explored, with particular attention to its mechanisms in ferroptosis and autophagy. The results show that TMEM164 expression is downregulated in LUAD and is associated with poor prognosis. Increasing TMEM164 expression significantly inhibits cell proliferation, migration, and invasion, while promoting an autophagy process dependent on ATG5 for autophagosome formation, thus facilitating ferroptosis. In mouse models, high TMEM164 expression combined with anti-PD-1 antibodies demonstrated synergistic anti-tumor effects. These findings highlight the critical role of TMEM164 in LUAD, suggesting that modulating TMEM164 expression could open new avenues for LUAD treatment.

Insights into the protective effect of omega-3 nanoemulsion against colistin-induced nephrotoxicity in experimental rats: regulation of autophagy and necroptosis via AMPK/mTOR and RIPK1/RIPK3/MLKL signaling pathways

Colistin is considered one of the most effective antibiotics against gram-negative bacteria. However, nephrotoxicity is one of the dose-limiting factors in its treatment. This study aimed to evaluate the outcome of omega-3 nanoemulsion against colistin-induced nephrotoxicity and its possible underlying mechanism. Four rat groups were involved in the present research; each group containing ten rats was divided as follows: Group I (control) rats received normal saline; Group II (omega-3 nanoemulsion) rats received a dose of 500 mg/kg/body weight orally; Group III (colistin) rats received colistin intraperitoneally (300.000 IU/kg/day); and Group IV (colistin/omega-3 nanoemulsion) rats were treated for six days. The results revealed that colistin administration caused deterioration in renal functions such as creatinine, blood urea nitrogen, 24 h proteinuria, and kidney injury molecule-1 with decrease in creatinine clearance, resulting in histological alternation and tubular damage with diffuse interstitial inflammation. Additionally, colistin significantly increased the lipid peroxidation marker malonaldehyde, proinflammatory cytokines tumor necrosis alpha, interleukin-6, interleukin-1 beta. Also, autophagy influx marker microtubule-associated protein light chain 3B, Beclin-1, and necroptotic related proteins, receptor-interacting protein kinase-3 (RIPK-3), RIPK-1, mixed lineage kinase domain-like protein, and autophagy pathway regulatory kinase AMP-activated protein kinase, with a decrease in antioxidant enzymes catalase, superoxide dismutase, and total antioxidant capacity, autophagic marker ubiquitin-binding protein (p62), and regulator Mammalian target of rapamycin. Interestingly, omega-3 nanoemulsion reversed the results above, dramatically improving renal function and histological picture. Thus, omega-3 nanoemulsion provided a notable method for suppressing colistin-induced nephrotoxicity via its antioxidant and anti-inflammatory power, inhibiting pathological autophagy and necroptosis.

Redistribution of PU.1 partner transcription factor RUNX1 binding secures cell survival during leukemogenesis

Transcription factors (TFs) orchestrating lineage-development often control genes required for cellular survival. However, it is not well understood how cells survive when such TFs are lost, for example in cancer. PU.1 is an essential TF for myeloid fate, and mice with downregulated PU.1 levels develop acute myeloid leukemia (AML). Combining a multi-omics approach with a functional genetic screen, we reveal that PU.1-downregulated cells fundamentally change their survival control from cytokine-driven pathways to overexpression of an autophagy-predominated stem cell gene program, for which we also find evidence in human AML. Control of this program involves redirected chromatin occupancy of the PU.1 partner TF Runx1 to a lineage-inappropriate binding site repertoire. Hence, genomic reallocation of TF binding upon loss of a partner TF can act as a pro-oncogenic failsafe mechanism by sustaining cell survival during leukemogenesis.

Lipids determine the toxicity of human islet polypeptide aggregates in vivo

The onset and progression of type 2 diabetes is linked to the accumulation and aggregation of human islet amyloid polypeptide (hIAPP) in the pancreas. Amyloid oligomers and fibrils formed as a result of such aggregation exert high cytotoxicity. Although some pieces of evidence suggest that lipids could alter the rate of hIAPP aggregation, the effect of lipids on the aggregation properties of this peptide remains unclear. In this study, we investigate the effect of sphingophospholipid and anionic and zwitterionic phospholipids with different lengths of fatty acids on the aggregation of hIAPP. We found that anionic lipids drastically accelerate peptide aggregation, whereas this effect was substantially weaker for sphingophospholipid and zwitterionic phospholipid. Biophysical analysis revealed that the presence of lipids resulted in substantial differences in morphology and secondary structure of hIAPP fibrils compared to the protein aggregates grown in the lipid-free environment. We also found that zwitterionic phospholipids drastically increased cytotoxicity of hIAPP aggregates, whereas this effect was less evident for sphingophospholipid and anionic phospholipid. Our results showed that drastic differences in lipid-determined cytotoxicity of hIAPP aggregates were linked to molecular mechanisms of autophagy, exocytosis, and unfolded protein response. These findings suggest that molecular candidates that could disrupt protein-lipid interactions would allow for deceleration of the onset and progression of type 2 diabetes.

Repurposing of the Antipsychotic Trifluoperazine Induces SLC7A11/GPX4- Mediated Ferroptosis of Oral Cancer via the ROS/Autophagy Pathway

Ferroptosis, a mode of cell death characterized by iron-dependent phospholipid peroxidation, has a substantial therapeutic potential for the treatment of various cancers. This study investigated the effects of trifluoperazine (TFP), an FDA-approved drug traditionally utilized for mental health disorder, on oral cancer cells, with a particular focus on the mechanisms involved in its potential anti-tumor properties. Our findings indicate that TFP significantly elevates the levels of lipid-derived reactive oxygen species (ROS) and induces ferroptotic cell death in oral cancer cells through pathways involving autophagy, the SLC7A11/GPX4 axis, and mitochondrial damage. Additionally, molecular docking analyses revealed that TFP acts as an inhibitor of GPX4. The elevated expression level of GPX4 in oral cancer biopsies was also found to correlate with a poor prognosis. Together, these results provide evidence that TFP selectively induces GPX4-mediated, autophagy-dependent ferroptosis, thereby exerting anti-cancer effects against oral cancer and preventable death.

Migfilin promotes autophagic flux through direct interaction with SNAP29 and Vamp8

Autophagy plays a crucial role in cancer cell survival by facilitating the elimination of detrimental cellular components and the recycling of nutrients. Understanding the molecular regulation of autophagy is critical for developing interventional approaches for cancer therapy. In this study, we report that migfilin, a focal adhesion protein, plays a novel role in promoting autophagy by increasing autophagosome-lysosome fusion. We found that migfilin is associated with SNAP29 and Vamp8, thereby facilitating Stx17-SNAP29-Vamp8 SNARE complex assembly. Depletion of migfilin disrupted the formation of the SNAP29-mediated SNARE complex, which consequently blocked the autophagosome-lysosome fusion, ultimately suppressing cancer cell growth. Restoration of the SNARE complex formation rescued migfilin-deficiency-induced autophagic flux defects. Finally, we found depletion of migfilin inhibited cancer cell proliferation. SNARE complex reassembly successfully reversed migfilin-deficiency-induced inhibition of cancer cell growth. Taken together, our study uncovers a new function of migfilin as an autophagy-regulatory protein and suggests that targeting the migfilin-SNARE assembly could provide a promising therapeutic approach to alleviate cancer progression.

No energy, no autophagy-Mechanisms and therapeutic implications of autophagic response energy requirements

Autophagy is a lysosome-mediated self-degradation process of central importance for cellular quality control. It also provides macromolecule building blocks and substrates for energy metabolism during nutrient or energy deficiency, which are the main stimuli for autophagy induction. However, like most biological processes, autophagy itself requires ATP, and there is an energy threshold for its initiation and execution. We here present the first comprehensive review of this often-overlooked aspect of autophagy research. The studies in which ATP deficiency suppressed autophagy in vitro and in vivo were classified according to the energy pathway involved (oxidative phosphorylation or glycolysis). A mechanistic insight was provided by pinpointing the critical ATP-consuming autophagic events, including transcription/translation/interaction of autophagy-related molecules, autophagosome formation/elongation, autophagosome fusion with the lysosome, and lysosome acidification. The significance of energy-dependent fine-tuning of autophagic response for preserving the cell homeostasis, and potential implications for the therapy of cancer, autoimmunity, metabolic disorders, and neurodegeneration are discussed.

The mode of action of sorafenib in MDA-MB-231 breast carcinoma cells involves components of apoptotic, necroptotic and autophagy-dependent cell death pathways

We report the identification of an interesting mode of action by sorafenib (SF) (Nexavar) in triple-negative breast adenocarcinoma MDA-MB-231 cells. The dying cells presented features of apoptosis, such as externalization of phosphatidylserine and cleaved caspase-3, and autophagy-mediated cell death, such as formation of autophagosomes and autolysosomes, the overexpression of LC3-II, and the presence of LAMP1-positive vacuoles, while displaying insufficient autophagic flux. Components of endoplasmic reticulum stress (ER stress; PERK and CHOP) and of necroptosis (p-MLKL) were also elevated considerably. Investigating potential target proteins that could modulate this form of cell death, we next investigated the role of tubulin disruption, which is known to induce necroptosis, apoptosis, and autophagy-dependent cell death. Interactions of SF with purified tubulin were investigated in detail using a combination of cellular and biophysical assays, transmission electron microscopy, and computer simulations. A marked reduction in the intrinsic tryptophan fluorescence of tubulin, a concentration-dependent elevation of anilinonaphthalene sulfonate-tubulin complex fluorescence, electron micrographs of deformed in vitro-assembled microtubules, and disrupted and hyper-stabilized cellular microtubules evinced the ability of SF to target tubulin and disrupt cellular microtubules. Molecular docking and molecular dynamic simulations positioned the drug between the α and β subunits of tubulin with considerable stability (ΔGbind, -31.43 kcal/mol), suggesting that drug-induced perturbation of tubulin could contribute to this mode of cell death.

Karyoptosis as a novel type of UVB-induced regulated cell death

Karyoptosis is a type of regulated cell death (RCD) characterized by explosive nuclear rupture caused by a loss of nuclear membrane integrity, resulting in the release of genomic DNA and other nuclear components into the cytosol and extracellular environment. The mechanism underlying karyoptosis involves a delicate balance between the following forces: the expansion force exerted by the tightly packed DNA in the nucleus, the resistance provided by the nuclear lamina at the inner nuclear membrane (INM), and the tensile force from the cytoskeleton that helps position the nucleus at the center of the cytoplasm, allowing it to remain maximally expanded. In addition, CREB3, a type II integral membrane protein with DNA-binding ability, tethers chromatin to the INM, providing a tightening force through chromatin interactions that prevent nuclear membrane rupture. UVB radiation can trigger this process, inducing CREB3-FL cleavage and producing CREB3-CF. Therefore, UVB acts as an intrinsic factor in the induction of karyoptosis. Importantly, biochemical analysis of RCD markers shows that karyoptosis is distinct from other forms of cell death, such as apoptosis, autophagy, necroptosis, and pyroptosis. This review explores the mechanisms involved in maintaining nuclear membrane integrity and the role of CREB3 in triggering karyoptosis and provides brief suggestions on the potential implications for targeting cancer cells.

Targeting selective autophagy in CNS disorders by small-molecule compounds

Autophagy functions as the primary cellular mechanism for clearing unwanted intracellular contents. Emerging evidence suggests that the selective elimination of intracellular organelles through autophagy, compared to the increased bulk autophagic flux, is crucial for the pathological progression of central nervous system (CNS) disorders. Notably, autophagic removal of mitochondria, known as mitophagy, is well-understood in an unhealthy brain. Accumulated data indicate that selective autophagy of other substrates, including protein aggregates, liposomes, and endoplasmic reticulum, plays distinctive roles in various pathological stages. Despite variations in substrates, the molecular mechanisms governing selective autophagy can be broadly categorized into two types: ubiquitin-dependent and -independent pathways, both of which can be subjected to regulation by small-molecule compounds. Notably, natural products provide the remarkable possibility for future structural optimization to regulate the highly selective autophagic clearance of diverse substrates. In this context, we emphasize the selectivity of autophagy in regulating CNS disorders and provide an overview of chemical compounds capable of modulating selective autophagy in these disorders, along with the underlying mechanisms. Further exploration of the functions of these compounds will in turn advance our understanding of autophagic contributions to brain disorders and illuminate precise therapeutic strategies for these diseases.

Let's talk about flux: the rising potential of autophagy rate measurements in disease

Macroautophagy/autophagy is increasingly implicated in a variety of diseases, making it an attractive therapeutic target. However, many aspects of autophagy are not fully understood and its impact on many diseases remains debatable and context-specific. The lack of systematic and dynamic measurements in these cases is a key reason for this ambiguity. In recent years, Loos et al. 2014 and Beesabathuni et al. 2022 developed methods to quantitatively measure autophagy holistically. In this commentary, we pose some of the unresolved biological questions regarding autophagy and consider how quantitative measurements may address them. While the applications are ever-expanding, we provide specific use cases in cancer, virus infection, and mechanistic screening. We address how the rate measurements themselves are central to developing cancer therapies and present ways in which these tools can be leveraged to dissect the complexities of virus-autophagy interactions. Screening methods can be combined with rate measurements to mechanistically decipher the labyrinth of autophagy regulation in cancer and virus infection. Taken together, these approaches have the potential to illuminate the underlying mechanisms of various diseases.Abbreviation MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; R1: rate of autophagosome formation; R2: rate of autophagosome-lysosome fusion; R3: rate of autolysosome turnover.

Piperine induces autophagy of colon cancer cells: Dual modulation of AKT/mTOR signaling pathway and ROS production

BACKGROUND

Colorectal cancer (CRC) is a prevalent malignancy and poses a significant clinical challenge. Piperine, an alkaloid molecule extracted from Piper nigrum and Piper longum, has emerged as a promising anticancer agent. However, the molecular mechanisms of piperine' antitumor effects in CRC need to be further elucidated.

METHODS

Human colorectal cancer cells were treated with piperine in vitro. CCK-8 and clone formation assays were adopted to detect cell viability. The accumulation of autophagosomes was assessed by Western blotting and immunofluorescence. Apoptosis and reactive oxygen species (ROS) levels were analyzed by flow. In vivo, a xenograft tumor mouse model was constructed using CT26 cells.

RESULTS

Piperine inhibited CRC cell viability and suppressed tumor weight and volume in a mouse model. Additionally, piperine treatment induced the accumulation of autophagosomes in CRC cells. This effect was attributed to the inhibition of the AKT/mTOR pathway and the accumulation of ROS. activation of AKT or clearance of ROS attenuated piperine-mediated tumor suppression.

CONCLUSION

This study shows that piperine induces autophagy-dependent cell death in CRC cells by increasing ROS production and inhibiting Akt/mTOR signaling.

LINC00941 is a diagnostic biomarker for lung adenocarcinoma and promotes tumorigenesis through cell autophagy

Non-small cell lung cancer (NSCLC) is a lethal malignancy. There is mounting evidence indicating that lncRNAs are crucial players with dual roles as both biomarkers and regulators across various cancers. It was reported that LINC00941 plays a cancer-promoting role in NSCLC. However, its impact on tumour autophagy remains poorly understood. In this study, we developed a risk assessment model and identified an autophagy-related lncRNA LINC00941, which has independent predictive and early diagnostic potential. Using RT-qPCR analysis, we confirmed the upregulation of LINC00941 in tumour tissues and cell lines of human lung adenocarcinoma (LUAD). Functional assays, such as CCK8, colony formation and xenograft models, demonstrated the cancer-promoting activity of LINC00941 both in vitro and in vivo. Further analysis using Western blotting analysis, mRFP-GFP-LC3 double fluorescence lentivirus vector and transmission electron microscopy (TEM) confirmed that the knockdown of LINC00941 triggered autophagy. These results indicate that knockdown of LINC00941 induces autophagy and impairs the proliferation of LUAD. Therefore, we propose LINC00941 as an independent biomarker for early diagnosis as well as a therapeutic target in LUAD.

TGM2-Mediated Autophagy Contributes to the Radio-Resistance of Non-Small Cell Lung Cancer Stem-like Cells

Objectives: Cancer cells with 'stemness' are generally resistant to chemoradiotherapy. This study aims to compare the differences in radiation sensitivity of A549 and CD44+A549 stem-like cells to X-rays and carbon ion radiation (C-ions), and to find a target that can kill cancer stem-like cells (CSCs) of non-small cell lung cancer (NSCLC). Methods: The study used two cell lines (A549 and CD44+A549). The tumorigenicity of cells was tested with animal experiments. The cells were irradiated with X-rays and C-ions. Cell viability was detected using the CCK-8 and EdU assay. A liquid chromatograph-mass spectrometer (LC-MS) helped detect metabolic differences. Protein and mRNA expression were detected using a Western blot, reverse transcription-quantitative (RT-qPCR), and PCR array. The autophagic activity was monitored with a CYTO-ID® Autophagy Detection Kit 2.0. Immunofluorescence and co-immunoprecipitation helped to observe the localization and interaction relationships. Results: First, we verified the radio-resistance of CD44+A549 stem-like cells. LC-MS indicated the difference in autophagy between the two cells, followed by establishing a correlation between the radio-resistance and autophagy. Subsequently, the PCR array proved that TGM2 is significantly upregulated in CD44+A549 stem-like cells. Moreover, the TGM2 knockdown by small interfering RNA could decrease the radio-resistance of CD44+A549 cells. Bioinformatic analyses and experiments showed that TGM2 is correlated with the expression of CD44 and LC3B. Additionally, TGM2 could directly interact with LC3B. Conclusions: We established the CD44-TGM2-LC3 axis: CD44 mediates radio-resistance of CD44+A549 stem-like cells through TGM2 regulation of autophagy. Our study may provide new biomarkers and strategies to alleviate the radio-resistance of CSCs in NSCLC.

Autophagy in benign prostatic hyperplasia: insights and therapeutic potential

Autophagy is a cellular homeostatic mechanism characterized by cyclic degradation. It plays an essential role in maintaining cellular quality and survival by eliminating dysfunctional cellular components. This process is pivotal in various pathophysiological processes. Benign prostatic hyperplasia (BPH) is a common urological disorder in middle-aged and elderly men. It frequently presents as lower urinary tract symptoms due to an increase in epithelial and stromal cells surrounding the prostatic urethra. The precise pathogenesis of BPH is complex. In recent years, research on autophagy in BPH has gained significant momentum, with accumulating evidence indicating its crucial role in the onset and progression of the disease. This review aims to outline the various roles of autophagy in BPH and elucidate potential therapeutic strategies targeting autophagy for managing BPH.

Dual perspective on autophagy in glioma: Detangling the dichotomous mechanisms of signaling pathways for therapeutic insights

Autophagy is a normal physiological process that aids the recycling of cellular nutrients, assisting the cells to cope with stressed conditions. However, autophagy's effect on cancer, including glioma, is uncertain and involves complicated molecular mechanisms. Several contradictory reports indicate that autophagy may promote or suppress glioma growth and progression. Autophagy inhibitors potentiate the efficacy of chemotherapy or radiation therapy in glioma. Numerous compounds stimulate autophagy to cause glioma cell death. Autophagy is also involved in the therapeutic resistance of glioma. This review article aims to detangle the complicated molecular mechanism of autophagy to provide a better perception of the two-sided role of autophagy in glioma and its therapeutic implications. The protein and epigenetic modulators of the cytoprotective and cytotoxic role of autophagy are described in this article. Moreover, several signaling pathways are associated with autophagy and its effects on glioma. We have reviewed the molecular pathways and highlighted the signaling axis involved in cytoprotective and cytotoxic autophagy. Additionally, this article discusses the role of autophagy in therapeutic resistance, including glioma stem cell maintenance and tumor microenvironment regulation. It also summarizes several investigations on the anti-glioma effects of autophagy modulators to understand the associated mechanisms and provide insights regarding its therapeutic implications.

Leptin protects chondrocytes by inhibiting autophagy via phosphoinositide 3 kinase/protein kinase B/mammalian target of rapamycin signaling pathway

Leptin has been widely studied and found to have a significant impact on the development of osteoarthritis (OA). However, there are conflicting findings regarding the impact of leptin on chondrocytes. The study aimed to examine the impact of leptin on human chondrocytes and rats with OA. In the in vitro experiment, cartilage tissue obtained from patients hospitalized for knee replacement due to OA was collected for primary culture of chondrocytes. The proliferation and apoptosis of chondrocytes were assessed using cell counting kit-8 and flow cytometry. Autophagy levels were evaluated through monodansylcadaverine staining, mRFP-GFP-LC3 fluorescence, and transmission electron microscopy. Additionally, the expression of autophagy-related genes and proteins was analyzed using qRT-PCR and western blotting. In the in vivo experiment, an OA rat model was established. Following treatment with leptin and leptin antagonists, the cartilage tissues were examined using histology analysis (hematoxylin-eosin and Safranin O/fast green staining) and immunohistochemical. Mankin's score was utilized to assess the severity of OA, while qRT-PCR and western blotting were employed to detect the expression of autophagy-related genes and proteins in the cartilage. The ability of leptin to protect chondrocytes is achieved through the inhibition of autophagy via phosphoinositide 3 kinase/protein kinase B/mammalian target of rapamycin signaling pathway.

Antidepressant Sertraline Synergistically Enhances Paclitaxel Efficacy by Inducing Autophagy in Colorectal Cancer Cells

Colorectal cancer (CRC) is the second leading cause of cancer-related death worldwide. It is important to discover new therapeutic regimens for treating CRC. Depression is known to be an important complication of cancer diseases. Repurposing antidepressants into anticancer drugs and exploring the combinational efficacy of antidepressants and chemotherapy are potentially good options for developing CRC treatment regimens. In this study, sertraline, an antidepressant drug, and paclitaxel, an anticancer drug, were chosen to study their antitumor effects in the treatment of colorectal cancer, alone or in combination, and to explore their underlying mechanisms. The data showed that sertraline exerted a dose-dependent cytotoxic effect on MC38 and CT26 colorectal cancer cell lines with IC50 values of 10.53 μM and 7.47 μM, respectively. Furthermore, sertraline synergistically sensitized chemotherapeutic agent paclitaxel efficacy in CRC cells with combination index (CI) values at various concentrations consistently lower than 1. Sertraline remarkably augmented paclitaxel-induced autophagy by increasing autophagosome formation indicated by elevated LC3-II/I ratio and promoting autophagic flux by degrading autophagy cargo receptor SQSTM1/p62, which may explain the synergistically cytotoxic effect of sertraline and paclitaxel combination therapy on CRC cells. This study provides important evidence to support repurposing sertraline as an anticancer agent and suggests a novel combinational regimen for effectively treating CRC as well as in the simultaneous treatment of CRC and depression.

NCAPH, ubiquitinated by TRIM21, promotes cell proliferation by inhibiting autophagy of cervical cancer through AKT/mTOR dependent signaling

Autophagy is closely related to the occurrence and development of human malignancies; however, the detailed mechanisms underlying autophagy in cervical cancer require further investigation. Previously, we found that the ectopic expression of NCAPH, a regulatory subunit of condensed protein complexes, significantly enhanced the proliferation of tumor cells; however, the underlying mechanisms were unclear. Here, we revealed that NCAPH is a novel autophagy-associated protein in cervical cancer that promotes cell proliferation by inhibiting autophagosome formation and reducing autophagy, with no effect on the cell cycle, apoptosis, or aging. Tripartite motif-containing protein 21 (TRIM21) is well known to be involved in inflammation, autoimmunity and cancer, mainly via its E3 ubiquitin ligase activity. Mass spectrometry and immunoprecipitation assays showed that TRIM21 interacted with NCAPH and decreased the protein stability of NCAPH via ubiquitination at the K11 lysine residue. Structural domain mutation analysis revealed that TRIM21 combined with NCAPH through its PRY/SPRY and CC domains and accelerated the degradation of NCAPH through the RING domain. Furthermore, TRIM21 promoted autophagosome formation and reduced cell proliferation by inhibiting NCAPH expression and the downstream AKT/mTOR pathway in cervical cancer cells. Immunohistochemical staining revealed that the protein expression of TRIM21 was negatively correlated with that of NCAPH and positively correlated with that of beclin-1 in cervical cancer tissues. Therefore, we provide evidence for the role of the TRIM21-NCAPH axis in cervical cancer autophagy and proliferation and the involvement of the AKT/mTOR signaling pathway in this process. These results deepen our understanding of the carcinogenesis of cervical cancer, broaden the understanding of the molecular mechanisms of TRIM21 and NCAPH, and provide guidance for individualized treatment of cervical cancer in the future.

A novel chromone-based as a potential inhibitor of ULK1 that modulates autophagy and induces apoptosis in colon cancer

Aim: Chromones are promising for anticancer drug development.Methods & results: 12 chromone-based compounds were synthesized and tested against cancer cell lines. Compound 8 showed the highest cytotoxicity (LC50 3.2 μM) against colorectal cancer cells, surpassing 5-fluorouracil (LC50 4.2 μM). It suppressed colony formation, induced cell cycle arrest and triggered apoptotic cell death, confirmed by staining and apoptosis markers. Cell death was accompanied by enhanced reactive oxygen species formation and modulation of the autophagic machinery (autophagy marker light chain 3B (LC3B); adenosine monophosphate-activated protein kinase (AMPK); protein kinase B (PKB); UNC-51-like kinase (ULK)-1; and ULK2). Molecular docking and dynamic simulations revealed that compound 8 directly binds to ULK1.Conclusion: Compound 8 is a promising lead for autophagy-modulating anti-colon cancer drugs.

Whole-body replacement of larval myofibers generates permanent adult myofibers in zebrafish

Drastic increases in myofiber number and size are essential to support vertebrate post-embryonic growth. However, the collective cellular behaviors that enable these increases have remained elusive. Here, we created the palmuscle myofiber tagging and tracking system for in toto monitoring of the growth and fates of ~5000 fast myofibers in developing zebrafish larvae. Through live tracking of individual myofibers within the same individuals over extended periods, we found that many larval myofibers readily dissolved during development, enabling the on-site addition of new and more myofibers. Remarkably, whole-body surveillance of multicolor-barcoded myofibers further unveiled a gradual yet extensive elimination of larval myofiber populations, resulting in near-total replacement by late juvenile stages. The subsequently emerging adult myofibers are not only long-lasting, but also morphologically and functionally distinct from the larval populations. Furthermore, we determined that the elimination-replacement process is dependent on and driven by the autophagy pathway. Altogether, we propose that the whole-body replacement of larval myofibers is an inherent yet previously unnoticed process driving organismic muscle growth during vertebrate post-embryonic development.

Exploring the interplay between stress mediators and skin microbiota in shaping age-related hallmarks: A review

Psychological stress is a major contributing factor to several health problems (e.g., depression, cardiovascular disease). Around 35 % of the world's population suffers from it, including younger generations. Physiologically, stress manifests through neuroendocrine pathways (Hypothalamic-Pituitary-Adrenal (HPA) axis and Sympathetic-Adrenal-Medullary (SAM) system) which culminate in the production of stress mediators like cortisol, epinephrine and norepinephrine. Stress and its mediators have been associated to body aging, through molecular mechanisms such as telomere attrition, mitochondrial dysfunction, cellular senescence, chronic inflammation, and dysbiosis, among others. Regarding its impact in the skin, stress impacts its structural integrity and physiological function. Despite this review focusing on several hallmarks of aging, emphasis was placed on skin microbiota dysbiosis. In this line, several studies, comprising different age groups, demographic contexts and body sites, have reported skin microbiota alterations associated with aging, and some effects of stress mediators on skin microbiota have also been reviewed in this paper. From a different perspective, since it is not a "traditional" stress mediator, oxytocin, a cortisol antagonist, has been related to glucorticoids inhibition and to display positive effects on cellular aging. This hormone dysregulation has been associated to psychological issues such as depression, whereas its upregulation has been linked to positive social interaction.

Golm1 facilitates the CaO2-DOPC-DSPE200-PEI -CsPbBr3 QDs -induced apoptotic death of hepatocytes through the stimulation of mitochondrial autophagy and mitochondrial reactive oxygen species production through interactions with P53/Beclin-1/Bcl-2

Mitophagy is a distinct physiological process that can have beneficial or deleterious effects in particular tissues. Prior research suggests that mitophagic activity can be triggered by CaO2-PM-CsPbBr3 QDs, yet the specific role that mitophagy plays in hepatic injury induced by CaO2-PM-CsPbBr3 QDs has yet to be established. Accordingly, in this study a series of mouse model- and cell-based experiments were performed that revealed the ability of CaO2-PM-CsPbBr3 QDs to activate mitophagic activity. Golm1 was upregulated in response to CaO2-PM-CsPbBr3 QDs treatment, and overexpressing Golm1 induced autophagic flux in the murine liver and hepatocytes, whereas knocking down Golm1 had the opposite effect. CaO2-PM-CsPbBr3 QDs were also able to Golm1 expression, in turn promoting the degradation of P53 and decreasing the half-life of this protein. Overexpressing Golm1 was sufficient to suppress the apoptotic death of hepatocytes in vitro and in vivo, whereas the knockdown of Golm1 had the opposite effect. The ability of Golm1 to promote p53-mediated autophagy was found to be associated with the disruption of Beclin-1 binding to Bcl-2, and the Golm1 N-terminal domain was determined to be required for p53 interactions, inducing autophagic activity in a manner independent of helicase activity or RNA binding. Together, these results indicate that inhibiting Golm1 can promote p53-dependent autophagy via disrupting Beclin-1 binding to Bcl-2, highlighting a novel approach to mitigating liver injury induced by CaO2-PM-CsPbBr3 QDs.

Identifying autophagy-related mRNAs and potential ceRNA networks in meniscus degeneration based on RNA sequencing and experimental validation

Purpose

The intimate connection between long noncoding RNA (lncRNA) and autophagy has been established in cartilage degeneration. However, their roles in meniscal degeneration remain ambiguous. This study aimed to identify the key autophagy-related lncRNA and its associated regulatory network in meniscal degeneration in the context of osteoarthritis (OA).

Methods

RNA sequencing was performed to identify differentially expressed lncRNAs (DELs) and mRNAs (DEMs), which were then conducted to enrichment analyses using the DAVID database and Metascape. Autophagy-related DEMs were identified by combining DEMs with data from the Human Autophagy Database. Three databases were used to predict miRNA, and the DIANA LncBase Predicted database was utilized to predict miRNA-lncRNA interactions. Based on these predictions, comprehensive competitive endogenous RNA (ceRNA) network were constructed. The expression levels of the classical autophagy markers and autophagy-related ceRNA network were validated. Additionally, Gene Set Enrichment Analysis (GSEA) was performed using autophagy-related DEMs.

Results

310 DELs and 320 DEMs were identified, with five upregulated and one downregulated autophagy-related DEMs. Through reverse prediction of miRNA, paired miRNA-lncRNA interactions, and verification using RT-qPCR, two lncRNAs (PCAT19, CLIP1-AS1), two miRNA (has-miR-3680-3p and has-miR-4795-3p) and two mRNAs (BAG3 and HSP90AB1) were included in the constructed ceRNA regulatory networks. GSEA indicated that the increased expression of autophagy-related mRNAs inhibited glycosaminoglycan biosynthesis in the degenerative meniscus.

Conclusion

This study presented the first construction of regulatory ceRNA network involving autophagy-related lncRNA-miRNA-mRNA interactions in OA meniscus. These findings offered valuable insights into the mechanisms underlying meniscal degeneration and provided potential targets for therapeutic intervention.

The Flavoring Agent Ethyl Vanillin Induces Cellular Stress Responses in HK-2 Cells

Flavored e-cigarettes are a popular alternative to cigarette smoking; unfortunately, the extrapulmonary effects are not well-characterized. Human proximal tubule cells were cultured for 24 or 48 h with 0-1000 µM ethyl vanillin (ETH VAN) and cytotoxicity evaluated. Mitochondrial health was significantly diminished following 48 h of exposure, accompanied by significantly decreased spare capacity, coupling efficiency, and ATP synthase expression. ETH VAN at 24 h inhibited glycolysis. The endoplasmic reticulum (ER) stress marker C/EBP homologous protein (CHOP) was increased at 100 μM relative to 500-1000 μM. The downstream proapoptotic marker cleaved caspase-3 subsequently showed a decreasing trend in expression after 48 h of exposure. The autophagy biomarkers microtubule-associated proteins 1A/1B light chain 3 (LC3B-I and LC3B-II) were measured by Western blot. LC3B-II levels and the LC3B-II/LC3B-I ratio increased at 24 h, which suggested activation of autophagy. In contrast, by 48 h, the autophagy biomarker LC3B-II decreased, resulting in no change in the LC3B-II/LC3B-I ratio. Mitophagy biomarker PTEN-induced putative kinase 1 (PINK1) expression decreased after 48 h of exposure. The downstream marker Parkin was not significantly changed after 24 or 48 h. These findings indicate that the flavoring ETH VAN can induce energy pathway dysfunction and cellular stress responses in a renal model.

SPRED2 Is a Novel Regulator of Autophagy in Hepatocellular Carcinoma Cells and Normal Hepatocytes

Sprouty-related enabled/vasodilator-stimulated phosphoprotein homology 1 domain containing 2 (SPRED2) is an inhibitor of the mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) pathway and has been shown to promote autophagy in several cancers. Here, we aimed to determine whether SPRED2 plays a role in autophagy in hepatocellular carcinoma (HCC) cells. The Cancer Genome Atlas (TCGA) Liver Cancer Database showed a negative association between the level of SPRED2 and p62, a ubiquitin-binding scaffold protein that accumulates when autophagy is inhibited. Immunohistochemically, accumulation of p62 was detected in human HCC tissues with low SPRED2 expression. Overexpression of SPRED2 in HCC cells increased the number of autophagosomes and autophagic vacuoles containing damaged mitochondria, decreased p62 levels, and increased levels of light-chain-3 (LC3)-II, an autophagy marker. In contrast, SPRED2 deficiency increased p62 levels and decreased LC3-II levels. SPRED2 expression levels were negatively correlated with translocase of outer mitochondrial membrane 20 (TOM20) expression levels, suggesting its role in mitophagy. Mechanistically, SPRED2 overexpression reduced ERK activation followed by the mechanistic or mammalian target of rapamycin complex 1 (mTORC1)-mediated signaling pathway, and SPRED2 deficiency showed the opposite pattern. Finally, hepatic autophagy was impaired in the liver of SPRED2-deficient mice with hepatic lipid droplet accumulation in response to starvation. These results indicate that SPRED2 is a critical regulator of autophagy not only in HCC cells, but also in hepatocytes, and thus the manipulation of this process may provide new insights into liver pathology.

The e-liquid flavoring cinnamaldehyde induces cellular stress responses in human proximal tubule (HK-2) kidney cells

Flavored e-liquid use has become popular among e-cigarette users recently, but the effects of such products outside the lung are not well characterized. In this work, acute exposure to the popular flavoring cinnamaldehyde (CIN) was performed on human proximal tubule (HK-2) kidney cells. Cells were exposed to 0-100 µM CIN for 24-48 h and cellular stress responses were assessed. Mitochondrial viability via MTT assay was significantly decreased at 20 µM for 24 and 48 h exposure. Seahorse XFp analysis showed significantly decreased mitochondrial energy output at 20 µM by 24 h exposure, in addition to significantly reduced ATP Synthase expression. Seahorse analysis also revealed significantly decreased glycolytic function at 20 µM by 24 h exposure, suggesting inability of glycolytic processes to compensate for reduced mitochondrial energy output. Cleaved caspase-3 expression, a mediator of apoptosis, was significantly increased at the 24 h mark. C/EBP homologous protein (CHOP) expression, a mediator of ER-induced apoptosis, was induced by 48 h and subsequently lost at the highest concentration of 100 µM. This decrease was accompanied by a simultaneous decrease in its downstream target cleaved caspase-3 at the 48 h mark. The autophagy marker microtubule-associated protein 1 A/1B light chain 3 (LC3B-I and LC3B-II) expression was significantly increased at 100 µM by 24 h. Autophagy-related 7 (ATG7) protein and mitophagy-related proteins PTEN-induced putative kinase 1 (PINK1) and PARKIN expression were significantly reduced at 24 and 48 h exposure. These results indicate acute exposure to CIN in the kidney HK-2 model induces mitochondrial dysfunction and cellular stress responses.

Dual blockage of PI3K-mTOR and FGFR induced autophagic cell death in cholangiocarcinoma cells

Purpose

To assess the impact of concurrent inhibition of the FGFR and PI3K/mTOR signaling pathways on oncogenic characteristics in cholangiocarcinoma (CCA) cells, including proliferation, autophagy, and cell death.

Materials and methods

KKU-213A, KKU-100, and KKU-213C cells were treated with either infigratinib or PKI-402 alone or in combination. Cell viability and cell death were evaluated using the sulforhodamine B (SRB) assay and acridine orange/ethidium bromide (AO/EB) staining. Cell cycle progression and apoptotic cell death were analyzed by flow cytometry. Western blotting was performed to assess the expression of proteins involved in cell cycle regulation and autophagy. Additionally, AO staining was employed to assess autophagic induction.

Results

The combination of infigratinib and PKI-402 showed a remarked synergistic suppression in cell viability in both CCA cell lines compared to treatment with single inhibitors. This antiproliferative effect was associated with cell cycle arrest in the G2-M phase and a decrease in the expression of cyclin A and cyclin B1 in CCA cells. Furthermore, the combination treatment induced apoptotic cell death to a greater extent than treatment with a single inhibitor. Infigratinib enhanced the induction of autophagy by PKI-402, as evidenced by marked increases of autophagic vacuoles stained acridine orange, levels of LC3B-II and suppression of levels of p-mTOR and. Notably, inhibition of autophagic flux by chloroquine prevented cell death induced by the combination treatment.

Conclusions

This study demonstrated that concurrent inhibition of the key FGFR/PI3K/mTOR pathways in CCA carcinogenesis enhances the suppression of CCA cells. The present findings indicate potential clinical implications for using combination treatment modalities in CCA therapy.

Autophagy in cancer immunotherapy: Perspective on immune evasion and cell death interactions

Both the innate and adaptive immune systems work together to produce immunity. Cancer immunotherapy is a novel approach to tumor suppression that has arisen in response to the ineffectiveness of traditional treatments like radiation and chemotherapy. On the other hand, immune evasion can diminish immunotherapy's efficacy. There has been a lot of focus in recent years on autophagy and other underlying mechanisms that impact the possibility of cancer immunotherapy. The primary feature of autophagy is the synthesis of autophagosomes, which engulf cytoplasmic components and destroy them by lysosomal degradation. The planned cell death mechanism known as autophagy can have opposite effects on carcinogenesis, either increasing or decreasing it. It is autophagy's job to maintain the balance and proper functioning of immune cells like B cells, T cells, and others. In addition, autophagy controls whether macrophages adopt the immunomodulatory M1 or M2 phenotype. The ability of autophagy to control the innate and adaptive immune systems is noteworthy. Interleukins and chemokines are immunological checkpoint chemicals that autophagy regulates. Reducing antigen presentation to induce immunological tolerance is another mechanism by which autophagy promotes cancer survival. Therefore, targeting autophagy is of importance for enhancing potential of cancer immunotherapy.

Sperm freezing damage: the role of regulated cell death

Substantial progress in research on sperm cryopreservation has occurred since the twentieth century, especially focusing on improving sperm freezing procedures and optimizing semen extenders. However, the cellular biological mechanisms of sperm freezing damage are still unclear, which greatly restricts the promotion and development of sperm cryopreservation. An essential component of sperm freezing damage is the occurrence of cell death. Considering the existence of multiple types of cell death pathways, this review discusses connections between characteristics of regulated cell death (e.g., apoptosis and ferroptosis), and accidental cell death (e.g., intracellular ice crystals) with sperm freezing damage and explores possible future research directions in this field.

Structural variety and pharmacological potential of naphthylisoquinoline alkaloids

Naphthylisoquinoline alkaloids are a fascinating class of natural biaryl compounds. They show characteristic mono- and dimeric scaffolds, with chiral axes and stereogenic centers. Since the appearance of the last comprehensive overview on these secondary plant metabolites in this series in 1995, the number of discovered representatives has tremendously increased to more than 280 examples known today. Many novel-type compounds have meanwhile been discovered, among them naphthylisoquinoline-related follow-up products like e.g., the first seco-type (i.e., ring-opened) and ring-contracted analogues. As highlighted in this review, the knowledge on the broad structural chemodiversity of naphthylisoquinoline alkaloids has been decisively driven forward by extensive phytochemical studies on the metabolite pattern of Ancistrocladus abbreviatus from Coastal West Africa, which is a particularly "creative" plant. These investigations furnished a considerable number of more than 80-mostly new-natural products from this single species, with promising antiplasmodial activities and with pronounced cytotoxic effects against human leukemia, pancreatic, cervical, and breast cancer cells. Another unique feature of naphthylisoquinoline alkaloids is their unprecedented biosynthetic origin from polyketidic precursors and not, as usual for isoquinoline alkaloids, from aromatic amino acids-a striking example of biosynthetic convergence in nature. Furthermore, remarkable botanical results are presented on the natural producers of naphthylisoquinoline alkaloids, the paleotropical Dioncophyllaceae and Ancistrocladaceae lianas, including first investigations on the chemoecological role of these plant metabolites and their storage and accumulation in particular plant organs.

The microtubule targeting agent ST-401 triggers cell death in interphase and prevents the formation of polyploid giant cancer cells

Microtubule targeting agents (MTAs) are commonly prescribed to treat cancers and predominantly kill cancer cells in mitosis. Significantly, some MTA-treated cancer cells escape death in mitosis, exit mitosis and become malignant polyploid giant cancer cells (PGCC). Considering the low number of cancer cells undergoing mitosis in tumor tissues, killing them in interphase may represent a favored antitumor approach. We discovered that ST-401, a mild inhibitor of microtubule (MT) assembly, preferentially kills cancer cells in interphase as opposed to mitosis, a cell death mechanism that avoids the development of PGCC. Single cell RNA sequencing identified mRNA transcripts regulated by ST-401, including mRNAs involved in ribosome and mitochondrial functions. Accordingly, ST-401 induces a transient integrated stress response, reduces energy metabolism, and promotes mitochondria fission. This cell response may underly death in interphase and avoid the development of PGCC. Considering that ST-401 is a brain-penetrant MTA, we validated these results in glioblastoma cell lines and found that ST-401 also reduces energy metabolism and promotes mitochondria fission in GBM sensitive lines. Thus, brain-penetrant mild inhibitors of MT assembly, such as ST-401, that induce death in interphase through a previously unanticipated antitumor mechanism represent a potentially transformative new class of therapeutics for the treatment of GBM.

Hydroxytyrosol ameliorates stress-induced liver injury through activating autophagy via HDAC1/2 inhibition

Hydroxytyrosol (HT), a phenolic extra-virgin olive oil compound used as a food supplement, has been recognized to protect liver function and alleviate stress-induced depressive-like behaviors. However, its protective effects against stress-induced liver injury (SLI) remain unknown. Here, the anti-SLI effect of HT was evaluated in mice with chronic unpredictable mild stress-induced SLI. Network pharmacology combined with molecular docking was used to clarify the underlying mechanism of action of HT against SLI, followed by experimental verification. The results showed that accompanying with the alleviation of HT on stress-induced depressive-like behaviors, HT was confirmed to exert the protective effects against SLI, as represented by reduced serum corticosterone (CORT), aspartate aminotransferase and alanine aminotransferase activities, as well as repair of liver structure, inhibition of oxidative homeostasis collapse, and inflammation reaction in the liver. Furthermore, core genes including histone deacetylase 1 and 2 (HDAC1/2), were identified as potential targets of HT in SLI based on bioinformatic screening and simulation. Consistently, HT significantly inhibited HDAC1/2 expression to maintain mitochondrial dysfunction in an autophagy-dependent manner, which was confirmed in a CORT-induced AML-12 cell injury and SLI mice models combined with small molecule inhibitors. We provide the first evidence that HT inhibits HDAC1/2 to induce autophagy in hepatocytes for maintaining mitochondrial dysfunction, thus preventing inflammation and oxidative stress for exerting an anti-SLI effect. This constitutes a novel therapeutic modality to synchronously prevent stress-induced depression-like behaviors and liver injury, supporting the advantaged therapeutic potential of HT.

The E-liquid flavoring vanillin alters energy and autophagic pathways in human proximal tubule (HK-2) epithelial cells

The use of flavored e-liquids in electronic nicotine delivery systems (ENDS) has become very popular in recent years, but effects of these products have not been well characterized outside the lung. In this study, acute exposure to the popular flavoring vanillin (VAN) was performed on human proximal tubule (HK-2) kidney cells. Cells were exposed to 0-1000 μM VAN for 24 or 48 h and cellular stress responses were determined. Mitochondrial viability using MTT assay showed a significant decrease between the control and 1000 μM group by 48 h. Seahorse XFp analysis showed significantly increased basal respiration, ATP production, and proton leak after 24 h exposure. By 48 h exposure, these parameters remained significantly increased in addition to non-mitochondrial respiration and maximal respiration. Glycolytic activity after 24 h exposure showed significant decreases in glycolysis, glycolytic capacity, glycolytic reserve, and non-glycolytic acidification. The autophagy markers microtubule-associated protein 1A/1B light chain 3 (LC3B-I and LC3B-II) were probed via western blotting. The ratio of LC3B-II/LC3B-I was significantly increased after 24 h exposure to VAN, but by 48 h this ratio significantly decreased. The mitophagy marker PINK1 showed an increasing trend at 24 h, and its downstream target Parkin was significantly increased between the control and 750 μM group only. Finally, the oxidative stress marker 4-HNE was significantly decreased after 48 h exposure to VAN. These results indicate that acute exposure to VAN in the kidney HK-2 model can induce energy and autophagic changes within the cell.

Autophagy in Its (Proper) Context: Molecular Basis, Biological Relevance, Pharmacological Modulation, and Lifestyle Medicine

Autophagy plays a critical role in maintaining cellular homeostasis and responding to various stress conditions by the degradation of intracellular components. In this narrative review, we provide a comprehensive overview of autophagy's cellular and molecular basis, biological significance, pharmacological modulation, and its relevance in lifestyle medicine. We delve into the intricate molecular mechanisms that govern autophagy, including macroautophagy, microautophagy and chaperone-mediated autophagy. Moreover, we highlight the biological significance of autophagy in aging, immunity, metabolism, apoptosis, tissue differentiation and systemic diseases, such as neurodegenerative or cardiovascular diseases and cancer. We also discuss the latest advancements in pharmacological modulation of autophagy and their potential implications in clinical settings. Finally, we explore the intimate connection between lifestyle factors and autophagy, emphasizing how nutrition, exercise, sleep patterns and environmental factors can significantly impact the autophagic process. The integration of lifestyle medicine into autophagy research opens new avenues for promoting health and longevity through personalized interventions.

The multifaceted role of autophagy in skin autoimmune disorders: a guardian or culprit?

Autophagy is a cellular process that functions to maintain intracellular homeostasis via the degradation and recycling of defective organelles or damaged proteins. This dynamic mechanism participates in various biological processes, such as the regulation of cellular differentiation, proliferation, survival, and the modulation of inflammation and immune responses. Recent evidence has demonstrated the involvement of polymorphisms in autophagy-related genes in various skin autoimmune diseases. In addition, autophagy, along with autophagy-related proteins, also contributes to homeostasis maintenance and immune regulation in the skin, which is associated with skin autoimmune disorders. This review aims to provide an overview of the multifaceted role of autophagy in skin autoimmune diseases and shed light on the potential of autophagy-targeting therapeutic strategies in dermatology.

LVING reveals the intracellular structure of cell growth

The continuous balance of growth and degradation inside cells maintains homeostasis. Disturbance of this balance by internal or external factors cause state of disease, while effective disease treatments seek to restore this balance. Here, we present a method based on quantitative phase imaging (QPI) based measurements of cell mass and the velocity of mass transport to quantify the balance of growth and degradation within intracellular control volumes. The result, which we call Lagrangian velocimetry for intracellular net growth (LVING), provides high resolution maps of intracellular biomass production and degradation. We use LVING to quantify the growth in different regions of the cell during phases of the cell cycle. LVING can also be used to quantitatively compare the effect of range of chemotherapy drug doses on subcellular growth processes. Finally, we applied LVING to characterize the effect of autophagy on the growth machinery inside cells. Overall, LVING reveals both the structure and distribution of basal growth within cells, as well as the disruptions to this structure that occur during alterations in cell state.

Copper(II) Complexes with 2,2':6',2″-Terpyridine Derivatives Displaying Dimeric Dichloro-μ-Bridged Crystal Structure: Biological Activities from 2D and 3D Tumor Spheroids to In Vivo Models

Eight 2,2':6',2″-terpyridines, substituted at the 4'-position with aromatic groups featuring variations in π-conjugation, ring size, heteroatoms, and methoxy groups, were employed to enhance the antiproliferative potential of [Cu2Cl2(R-terpy)2](PF6)2. Assessing the cytotoxicity in A2780 (ovarian carcinoma), HCT116 (colorectal carcinoma), and HCT116DoxR (colorectal carcinoma resistant to doxorubicin) and normal primary fibroblasts revealed that Cu(II) complexes with 4-quinolinyl, 4-methoxy-1-naphthyl, 2-furanyl, and 2-pyridynyl substituents showed superior therapeutic potential in HCT116DoxR cells with significantly reduced cytotoxicity in normal fibroblasts (42-129× lower). Besides their cytotoxicity, the Cu(II) complexes are able to increase intracellular ROS and interfere with cell cycle progression, leading to cell death by apoptosis and autophagy. Importantly, they demonstrated antimetastatic and antiangiogenic properties without in vivo toxicity. In accordance with their nuclear accumulation, the Cu(II) complexes are able to cleave pDNA and interact with bovine serum albumin, which is a good indication of their ability for internalization and transport toward tumor cells.

Targeting autophagy with natural products as a potential therapeutic approach for diabetic microangiopathy

As the quality of life improves, the incidence of diabetes mellitus and its microvascular complications (DMC) continues to increase, posing a threat to people's health and wellbeing. Given the limitations of existing treatment, there is an urgent need for novel approaches to prevent and treat DMC. Autophagy, a pivotal mechanism governing metabolic regulation in organisms, facilitates the removal of dysfunctional proteins and organelles, thereby sustaining cellular homeostasis and energy generation. Anomalous states in pancreatic β-cells, podocytes, Müller cells, cardiomyocytes, and Schwann cells in DMC are closely linked to autophagic dysregulation. Natural products have the property of being multi-targeted and can affect autophagy and hence DMC progression in terms of nutrient perception, oxidative stress, endoplasmic reticulum stress, inflammation, and apoptosis. This review consolidates recent advancements in understanding DMC pathogenesis via autophagy and proposes novel perspectives on treating DMC by either stimulating or inhibiting autophagy using natural products.