From Pinocytosis to Methuosis-Fluid Consumption as a Risk Factor for Cell Death

Methuosis key gene ARF6 as a diagnostic, prognostic and immunotherapeutic marker for prostate cancer: based on a comprehensive pan-cancer multi-omics analysis

BACKGROUND

Prostate cancer (PCa) is a leading cause of cancer-related mortality among men worldwide. Despite progress in the understanding of tumor biology, the prognosis for advanced prostate cancer remains poor, necessitating the identification of novel diagnostic, prognostic, and therapeutic biomarkers. Methuosis, a recently identified form of programmed cell death (PCD), is characterized by cytoplasmic vacuole accumulation and subsequent cell rupture, distinct from classical apoptosis and necrosis. The key regulatory gene in Methuosis, ARF6 (ADP-ribosylation factor 6), has emerged as a potential marker for cancer diagnosis and treatment. However, its role in prostate cancer and other malignancies remains insufficiently understood.

METHODS

In this study, we performed a comprehensive pan-cancer multi-omics analysis to investigate the role of ARF6 in Methuosis across multiple cancer types, with a specific focus on PCa as the primary context. Using data from public databases, including RNA sequencing, gene expression profiling, and clinical outcomes, we assessed the association between ARF6 expression and patient prognosis in PCa within this broader pan-cancer framework. Additionally, we employed functional enrichment analyses and survival analysis to explore the potential of ARF6 as a diagnostic and prognostic marker for prostate cancer. Immunotherapy-related gene expression signatures were also evaluated to determine the therapeutic relevance of ARF6.

RESULTS

ARF6 was significantly overexpressed in PCa tissues compared to normal tissues and was associated with poor prognosis (p < 0.05), particularly in advanced and metastatic stages. Receiver operating characteristic (ROC) analysis revealed a diagnostic AUC of 0.792 for ARF6. Functional analyses indicated that ARF6 regulates pathways critical to cell migration, invasion, and drug resistance. Moreover, ARF6 expression showed a strong negative correlation with immune checkpoint markers, such as PD-L1 (r = - 0.74), suggesting its potential as an immunotherapy target. These findings underscore ARF6's pivotal role in Methuosis and its promise as a biomarker in PCa.

CONCLUSION

ARF6 is a key regulator of Methuosis in prostate cancer, contributing to tumor progression, metastasis, and resistance to treatment. Our findings support the potential of ARF6 as a diagnostic, prognostic, and immunotherapeutic target in prostate cancer. Further experimental validation is needed to confirm these observations and to explore the therapeutic implications of targeting ARF6 in cancer treatment.

Lytic photoreceptor cell death caused by Rab escort protein deficiency in Drosophila

Choroideremia (CHM) is a rare X-linked recessive form of inherited retinal degeneration caused by the deficiency of the Rab escort protein 1 (REP1)-encoding CHM gene. REP1 is essential for the post-translational prenylation of the key players in intracellular membrane trafficking, the Rab GTPases. In this study, we aimed to analyze the mechanisms of retinal degeneration caused by Rep deficiency using the Drosophila retina as a model system. Rab GTPases lost their membrane association ability and diffused into the cytoplasm, and the accumulation of unprenylated Rab6 and Rab7 was observed in Rep-deficient photoreceptors. Notably, Rep-deficient photoreceptors underwent progressive cell death via cell swelling and rupture rather than apoptosis. These findings provide new insight to seek a therapeutic approach to CHM. Impact statement Choroideremia is an inherited retinal degeneration caused by a deficiency of Rab escort protein 1 (Rep-1). We used the Drosophila retina as a model to study the mechanism of retinal degeneration in Rep-deficiency and found that Rep-deficient photoreceptors undergo progressive cell death via cell swelling and rupture rather than apoptosis.

Survival strategies of cancer cells: the role of macropinocytosis in nutrient acquisition, metabolic reprogramming, and therapeutic targeting

Macropinocytosis is a nonselective form of endocytosis that allows cancer cells to largely take up the extracellular fluid and its contents, including nutrients, growth factors, etc. We first elaborate meticulously on the process of macropinocytosis. Only by thoroughly understanding this entire process can we devise targeted strategies against it. We then focus on the central role of the MTOR (mechanistic target of rapamycin kinase) complex 1 (MTORC1) in regulating macropinocytosis, highlighting its significance as a key signaling hub where various pathways converge to control nutrient uptake and metabolic processes. The article covers a comprehensive analysis of the literature on the molecular mechanisms governing macropinocytosis, including the initiation, maturation, and recycling of macropinosomes, with an emphasis on how these processes are hijacked by cancer cells to sustain their growth. Key discussions include the potential therapeutic strategies targeting macropinocytosis, such as enhancing drug delivery via this pathway, inhibiting macropinocytosis to starve cancer cells, blocking the degradation and recycling of macropinosomes, and inducing methuosis - a form of cell death triggered by excessive macropinocytosis. Targeting macropinocytosis represents a novel and innovative approach that could significantly advance the treatment of cancers that rely on this pathway for survival. Through continuous research and innovation, we look forward to developing more effective and safer anti-cancer therapies that will bring new hope to patients.Abbreviation: AMPK: AMP-activated protein kinase; ASOs: antisense oligonucleotides; CAD: carbamoyl-phosphate synthetase 2, aspartate transcarbamylase, and dihydroorotase; DC: dendritic cell; EGF: epidermal growth factor; EGFR: epidermal growth factor receptor; ERBB2: erb-b2 receptor tyrosine kinase 2; ESCRT: endosomal sorting complex required for transport; GAP: GTPase-activating protein; GEF: guanine nucleotide exchange factor; GRB2: growth factor receptor bound protein 2; LPP: lipopolyplex; MTOR: mechanistic target of rapamycin kinase; MTORC1: mechanistic target of rapamycin kinase complex 1; MTORC2: mechanistic target of rapamycin kinase complex 2; NSCLC: non-small cell lung cancer; PADC: pancreatic ductal adenocarcinoma; PDPK1: 3-phosphoinositide dependent protein kinase 1; PI3K: phosphoinositide 3-kinase; PIK3C3: phosphatidylinositol 3-kinase catalytic subunit type 3; PtdIns(3,4,5)P3: phosphatidylinositol-(3,4,5)-trisphosphate; PtdIns(4,5)P2: phosphatidylinositol-(4,5)-bisphosphate; PTT: photothermal therapies; RAC1: Rac family small GTPase 1; RPS6: ribosomal protein S6; RPS6KB1: ribosomal protein S6 kinase B1; RTKs: receptor tyrosine kinases; SREBF: sterol regulatory element binding transcription factor; TFEB: transcription factor EB; TNBC: triple-negative breast cancer; TSC2: TSC complex subunit 2; ULK1: unc-51 like autophagy activating kinase 1; UPS: ubiquitin-proteasome system.

The Formation and Features of Massive Vacuole Induced by Nutrient Deficiency in Human Embryonic Kidney Cells

BACKGROUND

Cellular vacuolization is a commonly observed phenomenon under physiological and pathological conditions. However, the mechanisms underlying vacuole formation remain largely unresolved.

METHODS

LysoTracker Deep Red probes and Enhanced Green Fluorescent Protein-tagged light chain 3B (LC3B) plasmids were employed to differentiate the types of massive vacuoles. By confocal microscopy, lysosome-like massive vacuoles (LysoTracker Deep Red+), autophagosome-like massive vacuoles (LC3B-enhanced green fluorescent protein (EGFP+)), and autolysosome-like massive vacuoles (LC3B-EGFP+ LysoTracker Deep Red+) in starved HEK293T cells were observed.

RESULTS

In this study, we demonstrated that nutrient deficiency can induce the formation of massive vacuoles that appear highly electron-lucent in HEK293T cells. Additionally, these massive vacuoles, resulting from nutrient depletion, can originate from various organelles, including small vacuoles, autophagosomes, lysosomes, and autolysosomes. We found that massive vacuoles could form through two primary mechanisms: the accumulation of small vacuoles into larger vacuoles or the fusion of homogeneous or heterogeneous vacuoles. Further analysis revealed that the membranes of massive vacuoles, regardless of origin, were composed of a bilayer membrane structure. As the volume of the massive vacuoles increased, the cytoplasm and nucleus were displaced toward the periphery of the cells, leading to the formation of signet ring-like cells. Interestingly, we provided evidence that complete massive vacuoles or autophagosome-like massive vacuoles can be released and exist independently outside HEK293T cells.

CONCLUSIONS

Nutrient deprivation induces the formation of heterogeneous, massive vacuoles in human embryonic kidney cells, some of which contribute to the development of signet ring cells, while others lead to extracellular vacuole formation.

Methuosis, Alkaliptosis, and Oxeiptosis and Their Significance in Anticancer Therapy

Understanding morphological, biochemical, and functional aspects of cell death is essential for targeting new cancer therapies. Even though many different mechanisms of cell death are identified, it is crucial to highlight the role of new and lesser-known pathways, including methuosis, alkaliptosis, and oxeiptosis. The aim of this review was to summarize the data about cell death mechanisms-methuosis, alkaliptosis, and oxeiptosis-and their role in cancer treatment. Unique molecular mechanisms and cellular outcomes characterize each of these forms of cell death. This research on methuosis, alkaliptosis, and oxeiptosis provides a better understating of cell death biology and creates novel opportunities for neoplasm management.

Delayed vacuolation in mammalian cells caused by hypotonicity and ion loss

Prolonged exposure of mammalian cells to hypotonic environments stimulates the development of sometimes large and numerous vacuoles of unknown origin. Here, we investigate the nature and formation of these vacuoles, which we term LateVacs. Vacuolation starts after osmotic cell swelling has subsided and continues for many hours thereafter. Most of the vacuoles are positive for the lysosomal marker LAMP-1 but not for the autophagosomal marker LC3. Vacuoles do not appear to have acidic pH, as they exclude LysoTracker and acridine orange; inhibiting the V-ATPase with bafilomycin A1 has no effect on their formation. No LateVacs were formed in cells with a knockout of the essential LRRC8A subunit of the volume-regulated anion channel (VRAC). Since the main feature of cells recovered from hypotonic swelling should be reduced chloride concentration, we tested if chloride depletion can act as a signal for vacuolation. Indeed, four different low-chloride buffers resulted in the development of similar vacuoles. Moreover, vacuolation was suppressed in WNK1/WNK3 double knockouts or by the inhibition of WNK kinase, which is activated by low chloride; in hypotonic media, the WNK inhibitor had a similar effect. However, exposing cells to a low-sodium, high-potassium medium also resulted in vacuoles, which were insensitive to WNK. We conclude that vacuole development can be triggered either by the loss of chloride or by the loss of sodium.

Lipid-nanoparticle-induced vacuolization in microglia

Lipid-containing vacuoles in microglia were discovered more than one hundred years ago in the brain of patients showing neurodegenerative processes. Recently, molecular-biological studies demonstrated specific changes in lipid-metabolism related to neurodegeneration. Despite that already Alzheimer described a distinct glia phenotype having large, lipid-containing vacuoles (Gitterzellen), little is known about how microglia convert lipid metabolites into a vacuolated phenotype. We studied the impact of liver-derived, insoluble, lipid-enriched nanoparticles (Lef-NP) ( ~ 20 nm) and of ceramide-coated Percoll-nanoparticles (Cer-NP) ( ~ 20 nm) on vacuolization in microglia. Lipidomic analysis of Lef-NP revealed numerous distinct lipids, including pro-inflammatory ceramides, which are enriched in the brain of Alzheimer patients. Video microscopy revealed that hepatocyte-derived Lef-NP and Cer-NP enhanced macropinocytosis, followed by macropinosome swelling and formation of the Gitterzellen phenotype. Neither ceramide nor Percoll-nanoparticles induced Gitterzellen-formation. Electron-tomography visualized membrane contact-sites between nanoparticle-loaded endosomes, endoplasmic reticulum cisternae and mitochondria. Suppression of lipid-nanoparticle-induced Gitterzellen-formation by amiloride, which supresses macropinocytosis, and bafilomycin A, an endosomal acidification inhibitor, further confirmed a pinocytotic pathway in Gitterzellen-formation. Bafilomycin A also reversed Gitterzellen to a ramified microglia phenotype. Our experimental findings suggest that lipid-nanoparticles but not emulsified lipids provoke vacuolization in microglia, and provide a simple in-vitro model for a pathogenic process taking years in the human brain.

Exploring paraptosis as a therapeutic approach in cancer treatment

A variety of cell death pathways play critical roles in the onset and progression of multiple diseases. Paraptosis, a unique form of programmed cell death, has gained significant attention in recent years. Unlike apoptosis and necrosis, paraptosis is characterized by cytoplasmic vacuolization, swelling of the endoplasmic reticulum and mitochondria, and the absence of caspase activation. Numerous natural products, synthetic compounds, and newly launched nanomedicines have been demonstrated to prime cell death through the paraptotic program and may offer novel therapeutic strategies for cancer treatment. This review summarizes recent findings, delineates the intricate network of signaling pathways underlying paraptosis, and discusses the potential therapeutic implications of targeting paraptosis in cancer treatment. The aim of this review is to expand our understanding of this unique cell death process and explore the potential therapeutic implications of targeting paraptosis in cancer treatment.

Growing Macrophages Regulate High Rates of Solute Flux by Pinocytosis

In metazoan cells, growth factors stimulate solute ingestion by pinocytosis. To examine the role of pinocytosis in cell growth, this study measured cell proliferation and the attendant rates of solute flux by pinocytosis in murine macrophages in response to the growth factor colony-stimulating factor-1 (CSF1). During CSF1-dependent growth in rich medium, macrophages internalized 72 percent of their cell volume in extracellular fluid every hour. Removal of the essential amino acid leucine from growth medium limited rates of protein synthesis and growth, but increased rates of solute accumulation by macropinocytosis. The amount of protein synthesized during leucine-dependent growth exceeded the capacity of pinocytosis to internalize enough soluble leucine to support growth and proliferation. Fluid-phase solute recycling from lysosomes secreted small molecules from the cells at high rates. Inhibitors of pinocytosis and the mechanistic target-of-rapamycin (mTOR) reduced cell growth and solute recycling, indicating roles for pinocytosis in growth and for nutrient sensing in the regulation of solute flux by pinocytosis.

Methuosis Inducer SGI-1027 Cooperates with Everolimus to Promote Apoptosis and Pyroptosis by Triggering Lysosomal Membrane Permeability in Renal Cancer

The mTOR inhibitor everolimus has been approved as a sequential or second-line therapy for renal cell carcinoma (RCC). However, the development of drug resistance limits its clinical applications. This study aims to address the challenge of everolimus resistance and provide new insights into the treatment of advanced RCC. Here, the cytotoxicity of the DNA methyltransferase 1 (DNMT1) inhibitor SGI-1027 in inducing cell vacuolation and methuosis is discovered and demonstrated for the first time. Additionally, SGI-1027 exerts synergistic effects with everolimus, as their combination suppresses the growth, migration, and invasion of renal cancer cells. Mechanistically, apoptosis and GSDME-dependent pyroptosis triggered by lysosomal membrane permeability (LMP) are observed. The upregulation of GSDME expression and increased lysosomal activity in renal cancer cells provide a therapeutic window for the combination of these two drugs to treat renal cancer. The combination treatment exhibits effective anti-tumor activity and is well tolerated in a subcutaneous tumor model. Overall, this study validates and reveals the specific cytotoxicity property of SGI-1027 and its potent synergistic effect with everolimus, offering new insights into advanced RCC therapy and everolimus-resistance overcoming.

Ultrastructural changes in cardiac and skeletal myoblasts following in vitro exposure to monensin, salinomycin, and lasalocid

Carboxylic ionophores are polyether antibiotics used in production animals as feed additives, with a wide range of benefits. However, ionophore toxicosis often occurs as a result of food mixing errors or extra-label use and primarily targets the cardiac and skeletal muscles of livestock. The ultrastructural changes induced by 48 hours of exposure to 0.1 μM monensin, salinomycin, and lasalocid in cardiac (H9c2) and skeletal (L6) myoblasts in vitro were investigated using transmission electron microscopy and scanning electron microscopy. Ionophore exposure resulted in condensed mitochondria, dilated Golgi apparatus, and cytoplasmic vacuolization which appeared as indentations on the myoblast surface. Ultrastructurally, it appears that both apoptotic and necrotic myoblasts were present after exposure to the ionophores. Apoptotic myoblasts contained condensed chromatin and apoptotic bodies budding from their surface. Necrotic myoblasts had disrupted plasma membranes and damaged cytoplasmic organelles. Of the three ionophores, monensin induced the most alterations in myoblasts of both cell lines.

Repurposing methuosis-inducing anticancer drugs for anthelmintic therapy

Drug-resistant parasitic nematodes pose a grave threat to plants, animals, and humans. An innovative paradigm for treating parasitic nematodes is emphasized in this opinion. This approach relies on repurposing methuosis (a death characterized by accumulation of large vacuoles) inducing anticancer drugs as anthelmintics. We review drugs/chemicals that have shown to kill nematodes or cancerous cells by inducing multiple vacuoles that eventually coalesce and rupture. This perspective additionally offers a succinct summary on Structure-Activity Relationship (SAR) of methuosis-inducing small molecules. This strategy holds promise for the development of broad-spectrum anthelmintics, shedding light on shared molecular mechanisms between cancer and nematodes in response to these inducers, thereby potentially transforming both therapeutic domains.

Mechanism and therapeutic targets of the involvement of a novel lysosomal proton channel TMEM175 in Parkinson's disease

Parkinson's disease (PD), recognized as the second most prevalent neurodegenerative disease in the aging population, presents a significant challenge due to the current lack of effective treatment methods to mitigate its progression. Many pathogenesis of PD are related to lysosomal dysfunction. Moreover, extensive genetic studies have shown a significant correlation between the lysosomal membrane protein TMEM175 and the risk of developing PD. Building on this discovery, TMEM175 has been identified as a novel potassium ion channel. Intriguingly, further investigations have found that potassium ion channels gradually close and transform into hydrion "excretion" channels in the microenvironment of lysosomes. This finding was further substantiated by studies on TMEM175 knockout mice, which exhibited pronounced motor dysfunction in pole climbing and suspension tests, alongside a notable reduction in dopamine neurons within the substantia nigra compacta. Despite these advancements, the current research landscape is not without its controversies. In light of this, the present review endeavors to methodically examine and consolidate a vast array of recent literature on TMEM175. This comprehensive analysis spans from the foundational research on the structure and function of TMEM175 to expansive population genetics studies and mechanism research utilizing cellular and animal models.A thorough understanding of the structure and function of TMEM175, coupled with insights into the intricate mechanisms underpinning lysosomal dysfunction in PD dopaminergic neurons, is imperative. Such knowledge is crucial for pinpointing precise intervention targets, thereby paving the way for novel therapeutic strategies that could potentially alter the neurodegenerative trajectory of PD.

Forms of Non-Apoptotic Cell Death and Their Role in Gliomas-Presentation of the Current State of Knowledge

In addition to necrosis and apoptosis, the two forms of cell death that have been known for many decades, other non-apoptotic forms of cell death have been discovered, many of which also play a role in tumors. Starting with the description of autophagy more than 60 years ago, newer forms of cell death have become important for the biology of tumors, such as ferroptosis, pyroptosis, necroptosis, and paraptosis. In this review, all non-apoptotic and oncologically relevant forms of programmed cell death are presented, starting with their first descriptions, their molecular characteristics, and their role and their interactions in cell physiology and pathophysiology. Based on these descriptions, the current state of knowledge about their alterations and their role in gliomas will be presented. In addition, current efforts to therapeutically influence the molecular components of these forms of cell death will be discussed. Although research into their exact role in gliomas is still at a rather early stage, our review clarifies that all these non-apoptotic forms of cell death show significant alterations in gliomas and that important insight into understanding them has already been gained.

Cellular Regulation of Macropinocytosis

Interest in macropinocytosis has risen in recent years owing to its function in tumorigenesis, immune reaction, and viral infection. Cancer cells utilize macropinocytosis to acquire nutrients to support their uncontrolled proliferation and energy consumption. Macropinocytosis, a highly dynamic endocytic and vesicular process, is regulated by a series of cellular signaling pathways. The activation of small GTPases in conjunction with phosphoinositide signaling pivotally regulates the process of macropinocytosis. In this review, we summarize important findings about the regulation of macropinocytosis and provide information to increase our understanding of the regulatory mechanism underlying it.

Scd1 and monounsaturated lipids are required for autophagy and survival of adipocytes

OBJECTIVE

Exposure of adipocytes to 'cool' temperatures often found in the periphery of the body induces expression of Stearoyl-CoA Desaturase-1 (Scd1), an enzyme that converts saturated fatty acids to monounsaturated fatty acids. The goal of this study is to further investigate the roles of Scd in adipocytes.

METHOD

In this study, we employed Scd1 knockout cells and mouse models, along with pharmacological Scd1 inhibition to dissect the enzyme's function in adipocyte physiology.

RESULTS

Our study reveals that production of monounsaturated lipids by Scd1 is necessary for fusion of autophagosomes to lysosomes and that with a Scd1-deficiency, autophagosomes accumulate. In addition, Scd1-deficiency impairs lysosomal and autolysosomal acidification resulting in vacuole accumulation and eventual cell death. Blocking autophagosome formation or supplementation with monounsaturated fatty acids maintains vitality of Scd1-deficient adipocytes.

CONCLUSION

This study demonstrates the indispensable role of Scd1 in adipocyte survival, with its inhibition in vivo triggering autophagy-dependent cell death and its depletion in vivo leading to the loss of bone marrow adipocytes.

Casein kinase 2 phosphorylates and induces the SALL2 tumor suppressor degradation in colon cancer cells

Spalt-like proteins are Zinc finger transcription factors from Caenorhabditis elegans to vertebrates, with critical roles in development. In vertebrates, four paralogues have been identified (SALL1-4), and SALL2 is the family's most dissimilar member. SALL2 is required during brain and eye development. It is downregulated in cancer and acts as a tumor suppressor, promoting cell cycle arrest and cell death. Despite its critical functions, information about SALL2 regulation is scarce. Public data indicate that SALL2 is ubiquitinated and phosphorylated in several residues along the protein, but the mechanisms, biological consequences, and enzymes responsible for these modifications remain unknown. Bioinformatic analyses identified several putative phosphorylation sites for Casein Kinase II (CK2) located within a highly conserved C-terminal PEST degradation motif of SALL2. CK2 is a serine/threonine kinase that promotes cell proliferation and survival and is often hyperactivated in cancer. We demonstrated that CK2 phosphorylates SALL2 residues S763, T778, S802, and S806 and promotes SALL2 degradation by the proteasome. Accordingly, pharmacological inhibition of CK2 with Silmitasertib (CX-4945) restored endogenous SALL2 protein levels in SALL2-deficient breast MDA-MB-231, lung H1299, and colon SW480 cancer cells. Silmitasertib induced a methuosis-like phenotype and cell death in SW480 cells. However, the phenotype was significantly attenuated in CRISPr/Cas9-mediated SALL2 knockout SW480 cells. Similarly, Sall2-deficient tumor organoids were more resistant to Silmitasertib-induced cell death, confirming that SALL2 sensitizes cancer cells to CK2 inhibition. We identified a novel CK2-dependent mechanism for SALL2 regulation and provided new insights into the interplay between these two proteins and their role in cell survival and proliferation.

Cell death classification: A new insight based on molecular mechanisms

Cells tend to disintegrate themselves or are forced to undergo such destructive processes in critical circumstances. This complex cellular function necessitates various mechanisms and molecular pathways in order to be executed. The very nature of cell death is essentially important and vital for maintaining homeostasis, thus any type of disturbing occurrence might lead to different sorts of diseases and dysfunctions. Cell death has various modalities and yet, every now and then, a new type of this elegant procedure gets to be discovered. The diversity of cell death compels the need for a universal organizing system in order to facilitate further studies, therapeutic strategies and the invention of new methods of research. Considering all that, we attempted to review most of the known cell death mechanisms and sort them all into one arranging system that operates under a simple but subtle decision-making (If \ Else) order as a sorting algorithm, in which it decides to place and sort an input data (a type of cell death) into its proper set, then a subset and finally a group of cell death. By proposing this algorithm, the authors hope it may solve the problems regarding newer and/or undiscovered types of cell death and facilitate research and therapeutic applications of cell death.

Vacuum ultraviolet irradiation for reduction of the toxicity of wastewater towards mammalian cells: Removal mechanism, changes in organic compounds, and toxicity alternatives

Vacuum ultraviolet (VUV, 185 + 254 nm) irradiation performs well for oxidation of model pollutants. However, oxidation of pollutants does not necessarily lead to a reduction in toxicity. Currently, a comprehensive understanding of the effect of VUV irradiation on the toxicity of real wastewater is still lacking. In this study, the influence of VUV irradiation on the toxicity of secondary effluents to Chinese hamster ovary (CHO) cells was investigated. The induction units of endogenous reactive oxygen species (ROS) and 8-hydroxyguanosine (8-OHdG) in cells continuously decreased with prolonged irradiation time. After 36 min of irradiation, the cytotoxicity and the genotoxicity of the secondary effluents were reduced by 57%-63% and 56%-61%, respectively. The UV (254 nm), •OH, and other substances generated during the VUV irradiation directly drive toxicity changes of wastewater. The contribution of •OH generated during VUV irradiation to the reductions in cytotoxicity and genotoxicity of the secondary effluents reached 72%-78% and 77%-84%, respectively. Hydroxyl radicals generated during VUV irradiation played an important role in the detoxification. The relative signal intensity of dissolved organic carbon (DOC) > 500 Da was partially removed, whereas that of DOC < 500 Da was small changed. Since the content of DOC > 500 Da in the samples was much lower than that of DOC < 500 Da, the removal of total DOC was only 15.8%-20.0% after 36 min of irradiation. The UV254 values and the fluorescence intensity values for different molecular weights (MWs) were all reduced effectively by VUV irradiation. Electron-rich organic compounds of all MWs were all sensitive to VUV irradiation. There were mono-linear relationships between changes in chemical indexes and changes in cytotoxicity or genotoxicity. The total fluorescence intensity (Ex: 220-420 nm, Em: 280-560 nm) was identified as the best indicator of the reduction in toxicity.

Structure and dynamics of the contractile vacuole complex in Tetrahymena thermophila

The contractile vacuole complex (CVC) is a dynamic and morphologically complex membrane organelle, comprising a large vesicle (bladder) linked with a tubular reticulum (spongiome). CVCs provide key osmoregulatory roles across diverse eukaryotic lineages, but probing the mechanisms underlying their structure and function is hampered by the limited tools available for in vivo analysis. In the experimentally tractable ciliate Tetrahymena thermophila, we describe four proteins that, as endogenously tagged constructs, localize specifically to distinct CVC zones. The DOPEY homolog Dop1p and the CORVET subunit Vps8Dp localize both to the bladder and spongiome but with different local distributions that are sensitive to osmotic perturbation, whereas the lipid scramblase Scr7p colocalizes with Vps8Dp. The H+-ATPase subunit Vma4 is spongiome specific. The live imaging permitted by these probes revealed dynamics at multiple scales including rapid exchange of CVC-localized and soluble protein pools versus lateral diffusion in the spongiome, spongiome extension and branching, and CVC formation during mitosis. Although the association with DOP1 and VPS8D implicate the CVC in endosomal trafficking, both the bladder and spongiome might be isolated from bulk endocytic input.

SCD1 and monounsaturated lipids are required for autophagy and survival of adipocytes

Exposure of adipocytes to 'cool' temperatures often found in the periphery of the body induces expression of Stearoyl-CoA Desaturase-1 (SCD1), an enzyme that converts saturated fatty acids to monounsaturated fatty acids. In this study, we employed Scd1 knockout cells and mouse models, along with pharmacological SCD1 inhibition, to investigate further the roles of SCD1 in adipocytes. Our study reveals that production of monounsaturated lipids by SCD1 is necessary for fusion of autophagosomes to lysosomes and that with a SCD1-deficiency, autophagosomes accumulate. In addition, SCD1-deficiency impairs lysosomal and autolysosomal acidification resulting in vacuole accumulation and eventual cell death. Blocking autophagosome formation or supplementation with monounsaturated fatty acids maintains vitality of SCD1-deficient adipocytes. Taken together, our results demonstrate that in vitro inhibition of SCD1 in adipocytes leads to autophagy-dependent cell death, and in vivo depletion leads to loss of bone marrow adipocytes.

Progress in the discovery and development of small molecule methuosis inducers

Current cancer chemotherapies rely mainly on the induction of apoptosis of tumor cells, while drug resistance arising from conventional chemicals has always been a big challenge. In recent years, more and more new types of cell deaths including methuosis have been extensively investigated and recognized as potential alternative targets for future cancer treatment. Methuosis is usually caused by excessive accumulation of macropinosomes owing to ectopic activation of macropinocytosis, which can be triggered by external stimuli such as chemical agents. Increasing reports demonstrate that many small molecule compounds could specifically induce methuosis in tumor cells while showing little or no effect on normal cells. This finding raises the possibility of targeting tumor cell methuosis as an effective strategy for the prevention of cancer. Based on fast-growing studies lately, we herein provide a comprehensive overview on the overall research progress of small molecule methuosis inducers. Promisingly, previous efforts and experiences will facilitate the development of next-generation anticancer therapies.

CYRI proteins: controllers of actin dynamics in the cellular 'eat vs walk' decision

Cells use actin-based protrusions not only to migrate, but also to sample their environment and take up liquids and particles, including nutrients, antigens and pathogens. Lamellipodia are sheet-like actin-based protrusions involved in sensing the substratum and directing cell migration. Related structures, macropinocytic cups, arise from lamellipodia ruffles and can take in large gulps of the surrounding medium. How cells regulate the balance between using lamellipodia for migration and macropinocytosis is not yet well understood. We recently identified CYRI proteins as RAC1-binding regulators of the dynamics of lamellipodia and macropinocytic events. This review discusses recent advances in our understanding of how cells regulate the balance between eating and walking by repurposing their actin cytoskeletons in response to environmental cues.

Functionalized protein microparticles targeting hACE2 as a novel preventive strategy for SARS-CoV-2 infection

The coronavirus disease 2019 (COVID-19) pandemic is caused by severe acute respiratory syndrome coronavirus 2(SARS-CoV-2), resulting in a serious burden on public health and social economy worldwide. SARS-CoV-2 infection is mainly initialized in the nasopharyngeal cavity through the binding of viral spike (S) protein to human angiotensin-converting enzyme 2 (hACE2) receptors which are widely expressed in many human cells. Thus, blockade of the interaction between viral S protein and hACE2 receptor in the primary entry site is a promising prevention strategy for the management of COVID-19. Here we showed protein microparticles (PMPs) decorated with hACE2 could bind and neutralize SARS-CoV-2 S protein-expressing pseudovirus (PSV) and protect host cells from infection in vitro. In the hACE2 transgenic mouse model, administration of intranasal spray with hACE2-decorated PMPs markedly decreased the viral load of SARS-CoV-2 in the lungs though the inflammation was not attenuated significantly. Our results provided evidence for developing functionalized PMPs as a potential strategy for preventing emerging air-borne infectious pathogens, such as SARS-CoV-2 infection.

Biophysical models of early mammalian embryogenesis

Embryo development is a critical and fascinating stage in the life cycle of many organisms. Despite decades of research, the earliest stages of mammalian embryogenesis are still poorly understood, caused by a scarcity of high-resolution spatial and temporal data, the use of only a few model organisms, and a paucity of truly multidisciplinary approaches that combine biological research with biophysical modeling and computational simulation. Here, we explain the theoretical frameworks and biophysical processes that are best suited to modeling the early mammalian embryo, review a comprehensive list of previous models, and discuss the most promising avenues for future work.

Chitinase-like proteins promoting tumorigenesis through disruption of cell polarity via enlarged endosomal vesicles

Introduction

Chitinase-like proteins (CLPs) are associated with tissue-remodeling and inflammation but also with several disorders, including fibrosis, atherosclerosis, allergies, and cancer. However, CLP's role in tumors is far from clear.

Methods

Here, we utilize Drosophila melanogaster and molecular genetics to investigate the function of CLPs (imaginal disc growth factors; Idgf's) in Ras^V12 dysplastic salivary glands.

Results and discussion

We find one of the Idgf's members, Idgf3, is transcriptionally induced in a JNK-dependent manner via a positive feedback loop mediated by reactive oxygen species (ROS). Moreover, Idgf3 accumulates in enlarged endosomal vesicles (EnVs) that promote tumor progression by disrupting cytoskeletal organization. The process is mediated via the downstream component, aSpectrin, which localizes to the EnVs. Our data provide new insight into CLP function in tumors and identifies specific targets for tumor control.

Lysosomal solute and water transport

Lysosomes mediate hydrolase-catalyzed macromolecule degradation to produce building block catabolites for reuse. Lysosome function requires an osmo-sensing machinery that regulates osmolytes (ions and organic solutes) and water flux. During hypoosmotic stress or when undigested materials accumulate, lysosomes become swollen and hypo-functional. As a membranous organelle filled with cargo macromolecules, catabolites, ions, and hydrolases, the lysosome must have mechanisms that regulate its shape and size while coordinating content exchange. In this review, we discussed the mechanisms that regulate lysosomal fusion and fission as well as swelling and condensation, with a focus on solute and water transport mechanisms across lysosomal membranes. Lysosomal H+, Na+, K+, Ca2+, and Cl- channels and transporters sense trafficking and osmotic cues to regulate both solute flux and membrane trafficking. We also provide perspectives on how lysosomes may adjust the volume of themselves, the cytosol, and the cytoplasm through the control of lysosomal solute and water transport.

The Role and Therapeutic Potential of Macropinocytosis in Cancer

Macropinocytosis, a unique endocytosis pathway characterized by nonspecific internalization, has a vital role in the uptake of extracellular substances and antigen presentation. It is known to have dual effects on cancer cells, depending on cancer type and certain microenvironmental conditions. It helps cancer cells survive in nutrient-deficient environments, enhances resistance to anticancer drugs, and promotes invasion and metastasis. Conversely, overexpression of the RAS gene alongside drug treatment can lead to methuosis, a novel mode of cell death. The survival and proliferation of cancer cells is closely related to macropinocytosis in the tumor microenvironment (TME), but identifying how these cells interface with the TME is crucial for creating drugs that can limit cancer progression and metastasis. Substantial progress has been made in recent years on designing anticancer therapies that utilize the effects of macropinocytosis. Both the induction and inhibition of macropinocytosis are useful strategies for combating cancer cells. This article systematically reviews the general mechanisms of macropinocytosis, its specific functions in tumor cells, its occurrence in nontumor cells in the TME, and its application in tumor therapies. The aim is to elucidate the role and therapeutic potential of macropinocytosis in cancer treatment.

A Tale of Two Cancers: A Current Concise Overview of Breast and Prostate Cancer

Cancer is a global issue, and it is expected to have a major impact on our continuing global health crisis. As populations age, we see an increased incidence in cancer rates, but considerable variation is observed in survival rates across different geographical regions and cancer types. Both breast and prostate cancer are leading causes of morbidity and mortality worldwide. Although cancer statistics indicate improvements in some areas of breast and prostate cancer prevention, diagnosis, and treatment, such statistics clearly convey the need for improvements in our understanding of the disease, risk factors, and interventions to improve life span and quality of life for all patients, and hopefully to effect a cure for people living in developed and developing countries. This concise review compiles the current information on statistics, pathophysiology, risk factors, and treatments associated with breast and prostate cancer.

Proanthocyanidin oligomers extract from hawthorn mediates cell cycle arrest, apoptosis, and lysosome vacuolation on HCT116 cells

In this study, Hawthorn oligomic procyanidins extracts (HPOE) were evaluated for their anticancer activity on colorectal cancer. Our results showed that HPOE arrested HCT116 cells cycle at G2/M phase through P53-Cyclin B pathway and promoted apoptosis partly via mitochondrial (Caspase 9-Caspase 3) and death receptor (Caspase 8-Caspase 3) pathways. Meanwhile, it was found that HPOE aggravated HCT116 cells death through lysosomal vacuolation, which was verified by inhibitor/activator of P53-ILC3 signaling pathway. Taken together, HPOE exerted anticancer effects which lays the foundation for the development of functional foods for clinical colon cancer patients.

Stability of Intracellular Protein Concentration under Extreme Osmotic Challenge

Cell volume (CV) regulation is typically studied in short-term experiments to avoid complications resulting from cell growth and division. By combining quantitative phase imaging (by transport-of-intensity equation) with CV measurements (by the exclusion of an external absorbing dye), we were able to monitor the intracellular protein concentration (PC) in HeLa and 3T3 cells for up to 48 h. Long-term PC remained stable in solutions with osmolarities ranging from one-third to almost twice the normal. When cells were subjected to extreme hypoosmolarity (one-quarter of normal), their PC did not decrease as one might expect, but increased; a similar dehydration response was observed at high concentrations of ionophore gramicidin. Highly dilute media, or even moderately dilute in the presence of cytochalasin, caused segregation of water into large protein-free vacuoles, while the surrounding cytoplasm remained at normal density. These results suggest that: (1) dehydration is a standard cellular response to severe stress; (2) the cytoplasm resists prolonged dilution. In an attempt to investigate the mechanism behind the homeostasis of PC, we tested the inhibitors of the protein kinase complex mTOR and the volume-regulated anion channels (VRAC). The initial results did not fully elucidate whether these elements are directly involved in PC maintenance.

Local Membrane Curvature Pins and Guides Excitable Membrane Waves in Chemotactic and Macropinocytic Cells - Biomedical Insights From an Innovative Simple Model

PIP3 dynamics observed in membranes are responsible for the protruding edge formation in cancer and amoeboid cells. The mechanisms that maintain those PIP3 domains in three-dimensional space remain elusive, due to limitations in observation and analysis techniques. Recently, a strong relation between the cell geometry, the spatial confinement of the membrane, and the excitable signal transduction system has been revealed by Hörning and Shibata (2019) using a novel 3D spatiotemporal analysis methodology that enables the study of membrane signaling on the entire membrane (Hörning and Shibata, 2019). Here, using 3D spatial fluctuation and phase map analysis on actin polymerization inhibited Dictyostelium cells, we reveal a spatial asymmetry of PIP3 signaling on the membrane that is mediated by the contact perimeter of the plasma membrane — the spatial boundary around the cell-substrate adhered area on the plasma membrane. We show that the contact perimeter guides PIP3 waves and acts as a pinning site of PIP3 phase singularities, that is, the center point of spiral waves. The contact perimeter serves as a diffusion influencing boundary that is regulated by a cell size- and shape-dependent curvature. Our findings suggest an underlying mechanism that explains how local curvature can favor actin polymerization when PIP3 domains get pinned at the curved protrusive membrane edges in amoeboid cells.