Cytoplasmic vacuolization during exposure to drugs and other substances

Sublethal Effects Induced by a Cyflumetofen Formulation on Honeybee Apis mellifera L. Workers: Assessment of Midgut, Hypopharyngeal Glands, and Fat Body Integrity

Worldwide, both cultivated and wild plants are pollinated by the honey bee, Apis mellifera. Bee numbers are declining as a result of a variety of factors, including increased pesticide use. Cyflumetofen controls pest mites in some plantations pollinated by bees, which may be contaminated with residual sublethal concentrations of this pesticide, in nectar and pollen. We evaluated the effects of a sublethal concentration of a cyflumetofen formulation on the midgut, hypopharyngeal gland, and fat body of A. mellifera workers orally exposed for 72 h or 10 days. The midgut epithelium of treated bees presented digestive cells with cytoplasm vacuoles and some cell fragmentation, indicating autophagy and cell death. After being exposed to the cyflumetofen formulation for 72 h, the midgut showed a higher injury rate than the control bees, but after 10 days, the organs had recovered. In the hypopharyngeal gland of treated bees, the end apparatus was filled with secretion, suggesting that the acaricide interferes with the secretory regulation of this gland. Histochemical tests revealed differences in the treated bees in both exposure periods in the midgut and hypopharyngeal glands. The acaricide caused cytotoxic effects on the midgut digestive cells, with apical protrusions, plasma membrane rupture, and several vacuoles in the cytoplasm, features of cell degeneration. In the hypopharyngeal glands of the treated bees, the secretory cells presented small electron-dense and large electron-lucent secretory granules. The fat body cells had no changes in comparison with the control bees. In conclusion, the cyflumetofen formulation at sublethal concentrations causes damage to the midgut and the hypopharyngeal glands of honey bee, which may compromise the functions of these organs and colony fitness. Environ Toxicol Chem 2024;00:1-11. © 2024 SETAC.

m6A demethylation of FOSL1 mRNA protects hepatoma cells against necrosis under glucose deprivation

Stress-adaptive mechanisms enabling cancer cells to survive under glucose deprivation remain elusive. N6-methyladenosine (m6A) modification plays important roles in determining cancer cell fate and cellular stress response to nutrient deficiency. However, whether m6A modification functions in the regulation of cancer cell survival under glucose deprivation is unknown. Here, we found that glucose deprivation reduced m6A modification levels. Increasing m6A modification resulted in increased hepatoma cell necrosis under glucose deprivation, whereas decreasing m6A modification had an opposite effect. Integrated m6A-seq and RNA-seq revealed potential targets of m6A modification under glucose deprivation, including the transcription factor FOSL1; further, glucose deprivation upregulated FOSL1 by inhibiting FOSL1 mRNA decay in an m6A-YTHDF2-dependent manner through reducing m6A modification in its exon1 and 5'-UTR regions. Functionally, FOSL1 protected hepatoma cells against glucose deprivation-induced necrosis in vitro and in vivo. Mechanistically, FOSL1 transcriptionally repressed ATF3 by binding to its promoter. Meanwhile, ATF3 and MAFF interacted via their leucine zipper domains to form a heterodimer, which competed with NRF2 for binding to antioxidant response elements in the promoters of NRF2 target genes, thereby inhibiting their transcription. Consequently, FOSL1 reduced the formation of the ATF3-MAFF heterodimer, thereby enhancing NRF2 transcriptional activity and the antioxidant capacity of glucose-deprived-hepatoma cells. Thus, FOSL1 alleviated the necrosis-inducing effect of glucose deprivation-induced reactive oxygen species accumulation. Collectively, our study uncovers the protective role of m6A-FOSL1-ATF3 axis in hepatoma cell necrosis under glucose deprivation, and may provide new targets for cancer therapy.

Drug-induced impairment of mitochondrial fatty acid oxidation and steatosis: assessment of causal relationship with 45 pharmaceuticals

Drug-induced liver injury (DILI) represents a major issue for pharmaceutical companies, being a potential cause of black-box warnings on marketed pharmaceuticals, or drug withdrawal from the market. Lipid accumulation in the liver also referred to as steatosis, may be secondary to impaired mitochondrial fatty acid oxidation (mtFAO). However, an overall causal relationship between drug-induced mtFAO inhibition and the occurrence of steatosis in patients has not yet been established with a high number of pharmaceuticals. Hence, 32 steatogenic and 13 nonsteatogenic drugs were tested for their ability to inhibit mtFAO in isolated mouse liver mitochondria. To this end, mitochondrial respiration was measured with palmitoyl-l-carnitine, palmitoyl-CoA + l-carnitine, or octanoyl- l-carnitine. This mtFAO tri-parametric assay was able to predict the occurrence of steatosis in patients with a sensitivity and positive predictive value above 88%. To get further information regarding the mechanism of drug-induced mtFAO impairment, mitochondrial respiration was also measured with malate/glutamate or succinate. Drugs such as diclofenac, methotrexate, and troglitazone could inhibit mtFAO secondary to an impairment of the mitochondrial respiratory chain, whereas dexamethasone, olanzapine, and zidovudine appeared to impair mtFAO directly. Mitochondrial swelling, transmembrane potential, and production of reactive oxygen species were also assessed for all compounds. Only the steatogenic drugs amiodarone, ketoconazole, lovastatin, and toremifene altered all these 3 mitochondrial parameters. In conclusion, our tri-parametric mtFAO assay could be useful in predicting the occurrence of steatosis in patients. The combination of this assay with other mitochondrial parameters could also help to better understand the mechanism of drug-induced mtFAO inhibition.

Transcriptome Analysis of Transiently Reversible Cell Vacuolization Caused by Excessive Serum Concentration in Scophthalmus maximus

As an important research tool, cell lines play a vital role in life science research, medical research, and drug development. During the culture of the Scophthalmus maximus head kidney (TK) cell line, we found a phenomenon of cell vacuolization caused by excessive serum concentration. Moreover, the vacuolization of the cells gradually disappeared after passage by trypsin digestion. In clarifying the formation mechanism of this reversible cellular vacuolation, transcriptomics was utilized to explore the mechanism of cell vacuolization caused by excessive serum concentration. Transcriptome analysis indicated that excessive serum concentration could cause the up-regulated expression of PORCN and other genes to promote cell proliferation. Compared with cells whose vacuolization disappeared after trypsin digestion and passage, the expression of mitosis-related genes (BUB1, ttk, Mad2, Cdc20, CDK1, CCNB1), nuclear stability-related genes LMNB1 and tissue stress and repair-related genes HMMR in vacuolated cells caused by excessive serum concentration was significantly up-regulated. There is a regulatory system related to adaptation and stress repair in the cells, which can maintain cell stability to a certain extent. This study provides a theoretical basis for the stable culture of fish cell lines and the solution to the problem of cell vacuolation.

New hemisynthetic derivatives of sphaeropsidin phytotoxins triggering severe endoplasmic reticulum swelling in cancer cells

Sphaeropsidins are iso-pimarane diterpenes produced by phytopathogenic fungi that display promising anticancer activities. Sphaeropsidin A, in particular, has been shown to counteract regulatory volume increase, a process used by cancer cells to avoid apoptosis. This study reports the hemi-synthesis of new lipophilic derivatives obtained by modifications of the C15,C16-alkene moiety. Several of these compounds triggered severe ER swelling associated with strong proteasomal inhibition and consequently cell death, a feature that was not observed with respect to mode of action of the natural product. Significantly, an analysis from the National Cancer Institute sixty cell line testing did not reveal any correlations between the most potent derivative and any other compound in the database, except at high concentrations (LC50). This study led to the discovery of a new set of sphaeropsidin derivatives that may be exploited as potential anti-cancer agents, notably due to their maintained activity towards multidrug resistant models.

Interaction of acetamiprid, Varroa destructor, and Nosema ceranae in honey bees

Health of honey bees is threatened by a variety of stressors, including pesticides and parasites. Here, we investigated effects of acetamiprid, Varroa destructor, and Nosema ceranae, which act either alone or in combination. Our results suggested that interaction between the three factors was additive, with survival risk increasing as the number of stressors increased. Although exposure to 150 μg/L acetamiprid alone did not negatively impact honey bee survival, it caused severe damage to midgut tissue. Among the three stressors, V. destructor posed the greatest threat to honey bee survival, and N. ceranae exacerbated intestinal damage and increased thickness of the midgut wall. Transcriptomic analysis indicated that different combinations of stressors elicited specific gene expression responses in honey bees, and genes involved in energy metabolism, immunity, and detoxification were altered in response to multiple stressor combinations. Additionally, genes associated with Toll and Imd signalling, tyrosine metabolism, and phototransduction pathway were significantly suppressed in response to different combinations of multiple stressors. This study enhances our understanding of the adaptation mechanisms to multiple stressors and aids in development of suitable protective measures for honey bees. ENVIRONMENTAL IMPLICATION: We believe our study is environmentally relevant for the following reasons: This study investigates combined effects of pesticide, Varroa destructor, and Nosema ceranae. These stressors are known to pose a threat to long-term survival of honey bees (Apis mellifera) and stability of the ecosystems. The research provides valuable insights into the adaptive mechanisms of honey bees in response to multiple stressors and developing effective conservation strategies. Further research can identify traits that promote honey bee survival in the face of future challenges from multiple stressors to maintain the overall stability of environment.

Perezone and its phenyl glycine derivative induce cytotoxicity via caspases on human glial cancer cells

The new phenyl glycine derivative of perezone was obtained in a single reaction step in ca. 80% yield which showed remarkable cytotoxic activity against the astrocytoma U-251 cell line. After 24 h of exposure, both perezone (IC50 = 6.83 ± 1.64 µM) and its phenyl glycine derivative (2.60 ± 1.69 µM) showed cytotoxic effect on U-251 cells but were five times less cytotoxic on the non-tumoral SVGp12 cell line (IC50 = 28.54 ± 1.59 and 31.87 ± 1.54 µM respectively). Both compounds induced cellular morphological changes (pyknosis or cytoplasmic vacuolization) and increased the expression of caspases 3, 8, and 9 genes related to apoptosis. In the acute toxicity study, phenyl glycine perezone (DL50 = 2000 mg/Kg) demonstrated to be less toxic than perezone (DL50 = 500 mg/Kg). Phenylglycine-perezone can envisage a beneficial therapeutic potential.

Developmental toxicity of pyriproxyfen induces changes in the ultrastructure of neural cells and in the process of skull ossification

Some studies relate the use of pyriproxyfen (PPF) in drinking water with damage to embryonic neurodevelopment, including a supposed association with cases of microcephaly. However, the effects on neural cells and skull ossification in embryos remain unclear. This study aims to investigate the effects of PPF on the structure and ultrastructure of brain cells and its influence on the skull ossification process during embryonic development. Chicken embryos, used as an experimental model, were exposed to concentrations of 0.01 and 10 mg/l PPF at E1. The findings demonstrated that PPF led to notable ultrastructural alterations such as reduced cilia and microvilli of ependymal cells and damage to mitochondria, endoplasmic reticulum, Golgi bodies, and cell membranes in neural cells. The frequency of changes and the degree of these cell damage between the forebrain and midbrain were similar. PPF induced a reduction in fox3 transcript levels, specific for differentiation of neurons, and a reduction in the NeuN protein content related to mature neurons and dendritic branches. PPF impacted the ossification process of the skull, as evidenced by the increase in the ossified area and the decrease in inter-bone spacing. In conclusion, this study highlights the ability of PPF to affect neurodevelopmental processes by inducing ultrastructural damage to neural cells, concomitant with a reduction in NeuN and fox3 expression. This detrimental impact coupled with deficiencies in skull ossification can prevent the proper growth and development of the brain.

Cell death induced by nicotine in human neuroblastoma SH-SY5Y cells is mainly attributed to cytoplasmic vacuolation originating from the trans-Golgi network

Humans are usually exposed to nicotine through the use of tobacco products. Although it is generally believed that nicotine is relatively harmless in tobacco consumption, it is, in fact, a toxic substance that warrants careful consideration of its potential toxicity. However, the current understanding of the neurotoxicity of nicotine is still very limited. In this study, we aim to reveal the toxic risk of nicotine to key target neuronal cells and its potential toxic mechanisms. The results showed that nicotine induced cell death, ROS increase, mitochondrial membrane potential decrease, and DNA damage in SH-SY5Y human neuroblastoma cells at millimolar concentrations, but did not cause toxic effects at the physiological concentration. These toxic effects were accompanied by cytoplasmic vacuolation. The inhibition of cytoplasmic vacuolation by bafilomycin A1 greatly reduced nicotine-induced cell death, indicating that cytoplasmic vacuolation is the key driving factor of cell death. These cytoplasmic vacuoles originated from the trans-Golgi network (TGN) and expressed microtubule-associated protein 1 light chain 3-II (LC3-II) and lysosomal associated membrane protein 1(LAMP1). The presence of LC3-II and LAMP1 within these vacuoles serves as evidence of compromised TGN structure and function. These findings provide valuable new insights into the potential neurotoxic risk and mechanisms of nicotine.

Effects of Spermine Synthase Deficiency in Mesenchymal Stromal Cells Are Rescued by Upstream Inhibition of Ornithine Decarboxylase

Despite the well-known relevance of polyamines to many forms of life, little is known about how polyamines regulate osteogenesis and skeletal homeostasis. Here, we report a series of in vitro studies conducted with human-bone-marrow-derived pluripotent stromal cells (MSCs). First, we show that during osteogenic differentiation, mRNA levels of most polyamine-associated enzymes are relatively constant, except for the catabolic enzyme spermidine/spermine N1-acetyltransferase 1 (SAT1), which is strongly increased at both mRNA and protein levels. As a result, the intracellular spermidine to spermine ratio is significantly reduced during the early stages of osteoblastogenesis. Supplementation of cells with exogenous spermidine or spermine decreases matrix mineralization in a dose-dependent manner. Employing N-cyclohexyl-1,3-propanediamine (CDAP) to chemically inhibit spermine synthase (SMS), the enzyme catalyzing conversion of spermidine into spermine, also suppresses mineralization. Intriguingly, this reduced mineralization is rescued with DFMO, an inhibitor of the upstream polyamine enzyme ornithine decarboxylase (ODC1). Similarly, high concentrations of CDAP cause cytoplasmic vacuolization and alter mitochondrial function, which are also reversible with the addition of DFMO. Altogether, these studies suggest that excess polyamines, especially spermidine, negatively affect hydroxyapatite synthesis of primary MSCs, whereas inhibition of polyamine synthesis with DFMO rescues most, but not all of these defects. These findings are relevant for patients with Snyder-Robinson syndrome (SRS), as the presenting skeletal defects-associated with SMS deficiency-could potentially be ameliorated by treatment with DFMO.

Effects of the insecticide imidacloprid on the post-embryonic development of the honey bee Apis mellifera (Hymenoptera: Apidae)

The widespread use of pesticides in agriculture has been linked to declines in bee populations worldwide. Imidacloprid is a widely used systemic insecticide that can be found in the pollen and nectar of plants and has the potential to negatively impact the development of bee larvae. We investigated the effects of oral exposure to a realistic field concentration (20.5 ng g-1) of imidacloprid on the midgut and fat body of Apis mellifera worker larvae. Our results showed that larvae exposed to imidacloprid exhibited changes in the midgut epithelium, including disorganization of the brush border, nuclear chromatin condensation, cytoplasm vacuolization, and release of cell fragments indication cell death. Additionally, histochemical analysis revealed that the midgut brush border glycocalyx was disorganized in exposed larvae. The fat body cells of imidacloprid-exposed larvae had a decrease in the size of lipid droplets from 50 to 8 μm and increase of 100 % of protein content, suggesting possible responses to the stress caused by the insecticide. However, the expression of de cdc20 gene, which plays a role in cell proliferation, was not affected in the midgut and fat body of treated larvae. These results suggest that imidacloprid negatively affects non-target organs during the larval development of A. mellifera potentially impacting this important pollinator species.

Effect of Tagetes minuta essential oil on the central nervous system of unfed Rhipicephalus sanguineus sensu lato 'tropical lineage' ticks

Rhipicephalus sanguineus sensu lato 'tropical lineage' (Acari: Ixodidae) is considered a sanitary concern due to its role as a disease vector. Tick strains resistant to synthetic acaricides have caused difficulties in their control, besides synthetic acaricides are harmful to the environment and to the health of non-target animals. The research of plants with acaricidal and repellent properties has proved to be an efficient alternative in tick control. The genus Tagetes spp. excels for its use as traditional pest control in households and plantations and also for its potential as an acaricide against R. sanguineus under laboratory conditions. The first aim of the present study was to evaluate the effect of different doses of Tagetes minuta essential oil (TMEO) on the central nervous system (synganglion) in unfed R. sanguineus adults. The histological analysis of synganglion exposed to the different concentrations of TMEO and amitraz 12.5% (50% of the recommended dose in the package insert) showed a significant effect with signs of cell damage including volume increase, loss of shape, and vacuolization, in addition to chromatin alterations such as condensation, margination, and fragmentation. TMEO were analyzed by gas chromatography coupled with mass spectrometry showing the presence of 21 compounds that according to their chemical structure are classified as terpenoids. Among them (Z)-β-ocimene, ocimene, (Z)-tagetone, and verbenone were found in major quantities.

Label-Free Intracellular Multi-Specificity in Yeast Cells by Phase-Contrast Tomographic Flow Cytometry

In-flow phase-contrast tomography provides a 3D refractive index of label-free cells in cytometry systems. Its major limitation, as with any quantitative phase imaging approach, is the lack of specificity compared to fluorescence microscopy, thus restraining its huge potentialities in single-cell analysis and diagnostics. Remarkable results in introducing specificity are obtained through artificial intelligence (AI), but only for adherent cells. However, accessing the 3D fluorescence ground truth and obtaining accurate voxel-level co-registration of image pairs for AI training is not viable for high-throughput cytometry. The recent statistical inference approach is a significant step forward for label-free specificity but remains limited to cells' nuclei. Here, a generalized computational strategy based on a self-consistent statistical inference to achieve intracellular multi-specificity is shown. Various subcellular compartments (i.e., nuclei, cytoplasmic vacuoles, the peri-vacuolar membrane area, cytoplasm, vacuole-nucleus contact site) can be identified and characterized quantitatively at different phases of the cells life cycle by using yeast cells as a biological model. Moreover, for the first time, virtual reality is introduced for handling the information content of multi-specificity in single cells. Full fruition is proofed for exploring and interacting with 3D quantitative biophysical parameters of the identified compartments on demand, thus opening the route to a metaverse for 3D microscopy.

Candesartan exhibits low intrinsic permeation capacity and affects buccal tissue viability and integrity: An ex vivo study in porcine buccal mucosa

Candesartan is a nonpeptide angiotensin II receptor blocker that selectively binds to angiotensin II receptor subtype 1. It is administered orally in its ester form (candesartan cilexetil). However, its poor aqueous solubility results in its low bioavailability; therefore, other routes of administration must be explored. The buccal mucosa has been extensively studied as an alternative route for drug delivery as it improves the bioavailability of drugs administered via the peroral route. Porcine buccal mucosa has been widely used as an ex vivo model to study the permeability of various diffusants; however, studies on candesartan are limited. This study aimed to evaluate the ex vivo permeation profile of candesartan and its effects on the viability and integrity of porcine buccal mucosa. Initially, we evaluated the viability, integrity, and barrier function of the buccal tissue before performing permeability tests using freshly excised tissues or tissues after 12 h of resection. Here, three indicators were used: caffeine, β-estradiol, and FD-20 penetration; mucosal metabolic activity, as determined using MTT reduction assay; and haematoxylin and eosin staining. Our results indicated that the porcine buccal mucosa preserved its viability, integrity, and barrier function before the permeation assay, allowing the passage of molecules with a molecular mass of less than 20 kDa, such as caffeine, but not β-estradiol and FD-20. Furthermore, we analyzed the intrinsic capacity of candesartan to diffuse through the fresh porcine buccal mucosa under two pH conditions. The concentration of candesartan in the receptor chamber of Franz diffusion cell was quantified using ultra-high liquid chromatography. In the permeation assay, candesartan exhibited a low intrinsic permeation capacity that impacted the buccal tissue viability and integrity, suggesting that using the buccal mucosa as an alternative route of administration requires developing a pharmaceutical formulation that reduces the adverse effects on mucosa and increasing the buccal permeability of candesartan.

V-ATPase V0 subunit activation mediates maduramicin-induced methuosis through blocking endolysosomal trafficking in vitro and in vivo

Methuosis, a novel cell death phenotype, is characterized by accumulation of cytoplasmic vacuolization upon external stimulus. Methuosis plays a critical role in maduramicin-induced cardiotoxicity despite the underlying mechanism is largely unknown. Herein, we aimed to investigate the origin and intracellular trafficking of cytoplasmic vacuoles, as well as the molecular mechanism of methuosis caused by maduramicin (1 μg/mL) in myocardial cells. H9c2 cells and broiler chicken were used and were exposed to maduramicin at doses of 1 μg/mL in vitro and 5 ppm-30 ppm in vivo. Morphological observation and dextran-Alexa Fluor 488 tracer experiment showed that endosomal compartments swelling and excessive macropinocytosis contributed to madurdamcin-induced methuosis. Cell counting kit-8 assay and morphology indicated pharmacological inhibition of macropinocytosis largely prevent H9c2 cells from maduramicin-triggered methuosis. In addition, late endosomal marker Rab7 and lysosomal associated membrane protein 1 (LAMP1) increased in a time-dependent manner after maduramicin treatment, and the recycling endosome marker Rab11 and ADP-ribosylation factor 6 (Arf6) were decreased by maduramicin. Vacuolar-H⁺-ATPase (V-ATPase) was activated by maduramicin, and pharmacological inhibition and genetic knockdown V0 subunit of V-ATPase restore endosomal-lysosomal trafficking and prevent H9c2 cells methuosis. Animal experiment showed that severe cardiac injury included the increase of creatine kinase (CK) and creatine kinase-MB (CK-MB), and vacuolar degeneration resembled methuosis in vivo after maduramicin treatment. Taken together, these findings demonstrate that targeting the inhibition of V-ATPase V0 subunit will prevent myocardial cells methuosis by restoring endosomal-lysosomal trafficking.

The Chemical Profile, and Antidermatophytic, Anti-Inflammatory, Antioxidant and Antitumor Activities of Withania chevalieri A.E. Gonç. Ethanolic Extract

Withania chevalieri, endogenous from Cape Verde, is a medicinal plant used in ethnomedicine with a large spectrum of applications, such as treating skin fungal infections caused by dermatophytes. The aim of this work was to chemically characterize the W. chevalieri crude ethanolic extract (WcCEE), and evaluate its bioactivities as antidermatophytic, antioxidant, anti-inflammatory and anticancer, as well as its cytotoxicity. WcCEE was chemically characterized via HPLC-MS. The minimal inhibitory concentration, minimal fungicidal concentration, time-kill and checkerboard assays were used to study the antidermatophytic activity of WcCEE. As an approach to the mechanism of action, the cell wall components, β-1,3-glucan and chitin, and cell membrane ergosterol were quantified. Transmission electron microscopy (TEM) allowed for the study of the fungal ultrastructure. WcCEE contained phenolic acids, flavonoids and terpenes. It had a concentration-dependent fungicidal activity, not inducing relevant resistance, and was endowed with synergistic effects, especially terbinafine. TEM showed severely damaged fungi; the cell membrane and cell wall components levels had slight modifications. The extract had antioxidant, anti-inflammatory and anti-cancer activities, with low toxicity to non-tumoral cell lines. The results demonstrated the potential of WcCEE as an antidermatophytic agent, with antioxidant, anti-inflammatory and anticancer activity, to be safely used in pharmaceutical and dermocosmetic applications.

Lysosomal trapping of 4-dimethylamino-1-{3-(1-methyl-1H-imidazole-2-yl)propanoyl}piperidine, a hydrophilic and weakly basic amine, in human aortic vascular smooth muscle cells

Some weakly basic compounds lead to cell death accompanied by cellular vacuolation. The novel analgesic agent, 4-dimethylamino-1-{3-(1-methyl-1H-imidazole-2-yl)propanoyl}piperidine (DMIP), is a hydrophilic and weakly basic compound that induces vacuolation in the vascular smooth muscle cells in dogs. Here, we investigated the vacuolation mechanism and the potential cytotoxicity of DMIP using human aortic vascular smooth muscle cells. When cells were treated with DMIP (0.1, 0.3, and 1 mM) for 6, 24, and 48 h, clear cytoplasmic vacuolation was observed at 1 mM after 24 and 48 h, along with an increase in the intracellular DMIP concentration. The vacuolation and intracellular DMIP were markedly reduced by bafilomycin A1, a vacuolar H⁺-ATPase inhibitor. The late endosome marker Rab7 and lysosome marker LAMP-2 were highly expressed but the early endosome marker Rab5 and autophagosome marker LC3 were not expressed specifically on the vacuolar membranes. These results suggested that the most vacuoles were enlarged late endosomes/lysosomes, resulting from the accumulation of DMIP by ion trapping. Moreover, DMIP did not affect lysosomal membrane integrity and was less cytotoxic than chloroquine, an inducer of phospholipidosis. The current study provides further insight into the mechanisms of vacuolation and lysosomal trapping induced by the hydrophilic and weakly basic amine DMIP.

Exploring the anticancer activity and the mechanism of action of pyrrolomycins F obtained by microwave-assisted total synthesis

Pyrrolomycins (PMs) are a family of naturally occurring antibiotic agents, isolated from the fermentation broth of Actinosporangium and Streptomyces species. Pursuing our studies on pyrrolomycins, we performed the total synthesis of the F-series pyrrolomycins (1-4) by microwave-assisted synthesis (MAOS), thus obtaining the title compounds in excellent yields (63-69%). Considering that there is no evidence so far of the anticancer effect of this class of compounds, we investigated PMs for their antiproliferative activity against HCT116 and MCF-7 cancer cell lines. PMs showed anticancer activity at submicromolar level with a minimal effect on normal epithelial cell line (hTERT RPE-1), and they were able to induce several morphological changes including elongated cells, cytoplasm vacuolization, long and thin filopodia as well as the appearance of tunneling nanotubes (TNTs). These data suggest that PMs could act by impairing the cell membranes and the cytoskeleton organization, with subsequent increase of ROS generation and the activation of different forms of non-apoptotic cell death.

The fungicide azoxystrobin causes histopathological and cytotoxic changes in the midgut of the honey bee Apis mellifera (Hymenoptera: Apidae)

Apis mellifera is an important bee pollinating native and crop plants but its recent population decline has been linked to the use of pesticides, including fungicides that have been commonly classified as safe for bees. However, many pesticides, in addition to direct mortality cause sublethal effects, including damage to target selective honey bee organs. The midgut is the organ responsible for the digestion and absorption of nutrients and the detoxification of ingested substances, such as pesticides. This study evaluated the histopathological and cytotoxic changes in the midgut of A. mellifera workers caused by the pesticide azoxystrobin. The limit-test was performed, and a 100 µg a.i./bee dose was administered orally and midgut analyzed with light and transmission electron microscopies after 24 h and 48 h of pesticide exposure. The midgut of the control bees has a single layer of digestive cells, with spherical nuclei, nests of regenerative cells, and the lumen coated with the peritrophic matrix. The bees fed on azoxystrobin showed morphological changes, including intense cytoplasm vacuolization and cell fragments released into the gut lumen. The protein detection test showed greater staining intensity in the nests of regenerative cells after 24 h of exposure to azoxystrobin. The occurrence of damage to the midgut in A. mellifera exposed to azoxystrobin indicates that although this fungicide has been classified as low toxicity for bees, it has sublethal effects in the midgut, and effects in other organs should be investigated.

Swainsonine-induced vacuolar degeneration is regulated by mTOR-mediated autophagy in HT22 cells

The indolizidine alkaloid, swainsonine (SW), is the main toxic component of locoweed, which can cause locoism in animals with characteristic neurological dysfunction. Pathological manifestations at cellular level include extensive vacuolar degeneration. Studies have shown that SW can induces autophagy, but the role and mechanism of autophagy in SW-induced vacuolar degeneration is unclear. In this study, we analyzed the role of autophagy in SW-induced cell injury in mouse hippocampal neurons cell line (HT22) using western blotting, qRT-PCR, transmission electron microscopy and immunofluorescence microscopy. The results showed that the expressions of LC3-II, ATG5, Beclin1 and p62 proteins and their mRNAs in HT22 cells were induced by SW treatment. The SW treatment increased the number of autophagosomes with enhanced fluorescence intensity of monodansylcadaverine (MDC) and LC3-II in a time-dose dependent manner. The results of lysosome staining showed that SW could increase the number of lysosomes, increase the intraluminal pH. Transmission electron microscopy results indicate that SW induced autophagosomes, and Baf A1 could effectively alleviate SW-induced vacuolar degeneration. At the molecular level, SW treatment inhibited the expression of p-PI3K, p-AKT, p-ERK, p-AMPK, p-mTOR, p-p70S6K and p-4EBP1 and promoted the expression of p53. Our results collectively suggest, PI3K/AKT/mTOR, ERK/mTOR and p53/mTOR signaling pathways are involved in the regulation of SW-induced autophagy in HT22 cells, while the AMPK/mTOR signaling pathway is not involved in this regulation. Inhibition of autophagic degradation can effectively alleviate SW-induced vacuolar degeneration.

Effects of bepridil on early cardiac development of zebrafish

Bepridil is a commonly used medication for arrhythmia and heart failure. It primarily exerts hemodynamic effects by inhibiting Na⁺/K⁺ movement and regulating the Na⁺/Ca²⁺ exchange. In comparison to other Ca²⁺ inhibitors, bepridil has a long half-life and a complex pharmacology. Additionally, it is widely used in antiviral research and the treatment of various diseases. However, the toxicity of this compound and its other possible effects on embryonic development are unknown. In this study, we investigated the toxicity of bepridil on rat myocardial H9c2 cells. After treatment with bepridil, the cells became overloaded with Ca²⁺ and entered a state of cytoplasmic vacuolization and nuclear abnormality. Bepridil treatment resulted in several morphological abnormalities in zebrafish embryo models, including pericardium enlargement, yolk sac swelling, and growth stunting. The hemodynamic effects on fetal development resulted in abnormal cardiovascular circulation and myocardial weakness. After inhibiting the Ca²⁺ transmembrane, the liver of zebrafish larvae also displayed an ectopic and deficient spatial location. Additionally, the results of the RNA-seq analysis revealed the detailed gene expression profiles and metabolic responses to bepridil treatment in zebrafish embryonic development. Taken together, our study provides an important evaluation of antiarrhythmic agents for clinical use in prenatal heart patients.

Potent anticancer activity of a novel iridium metallodrug via oncosis

Oncosis (from Greek ónkos, meaning "swelling") is a non-apoptotic cell death process related to energy depletion. In contrast to apoptosis, which is the main form of cell death induced by anticancer drugs, oncosis has been relatively less explored but holds potential to overcome drug resistance phenomena. In this study, we report a novel rationally designed mitochondria-targeted iridium(III) complex (OncoIr3) with advantageous properties as a bioimaging agent. OncoIr3 exhibited potent anticancer activity in vitro against cancer cells and displayed low toxicity to normal dividing cells. Flow cytometry and fluorescence-based assays confirmed an apoptosis-independent mechanism involving energy depletion, mitochondrial dysfunction and cellular swelling that matched with the oncotic process. Furthermore, a Caenorhabditis elegans tumoral model was developed to test this compound in vivo, which allowed us to prove a strong oncosis-derived antitumor activity in animals (with a 41% reduction of tumor area). Indeed, OncoIr3 was non-toxic to the nematodes and extended their mean lifespan by 18%. Altogether, these findings might shed new light on the development of anticancer metallodrugs with non-conventional modes of action such as oncosis, which could be of particular interest for the treatment of apoptosis-resistant cancers.

Ammonia in the presence of nano titanium dioxide (nano-TiO2) induces greater oxidative damage in the gill and liver of female zebrafish

Water pollution caused by a highly hazardous chemical ammonia and a widespread application nanomaterials-nano titanium dioxide (n-TiO₂) in nature water has attracted extensive concern of the world. However, the potential joint effects of the two factors are unknown. Aim to investigate the potential interactive effects of ammonia and n-TiO₂ and the behind mechanisms, adult female zebrafish (Danio rerio) were co-exposed for 8 weeks by total ammonia nitrogen (TAN; 0, 3, 30 mg/L) and n-TiO₂ (0, 0.1, 1 mg/L) in different combination conditions based on a full-factorial design. The analysis of absorption kinetics confirmed that n-TiO₂ could absorb free ammonia (NH₃) in aqueous solution and the loss rate of free NH₃ increased with the rise of n-TiO₂ concentration. Consistent with this, free NH₃ concentrations in the gill and liver were higher in the presence of n-TiO₂ compared to TAN exposure alone. The increases of MDA and PC concentrations in the gill and liver of fish indicated that TAN and n-TiO₂ alone or in combination caused oxidative stress. Simultaneously, the activity and transcription of antioxidant enzymes (T-SOD, CuZn-SOD, Mn-SOD, CAT, GPx and GST) as well as antioxidant GSH contents were extensively inhibited by TAN and n-TiO₂ via Nrf2-Keap1 signaling. The significant interactive effects of TAN and n-TiO₂ were detected on levels of GSH, GST and gstr1 mRNA in the gill, and on levels of GSH, T-SOD, Mn-SOD, CAT levels as well as gpx1a and keap1 mRNAs in the liver, implying synergistic toxic risk of TAN and n-TiO₂. The more severe histopathological alterations and higher IBR analysis in co-treatment groups further proved that the existence of n-TiO₂ excavated ammonia-induced toxicity in the gill and liver, especially in liver. In conclusion, ammonia and n-TiO₂ have a synergistic toxic risk of fish health because ammonia and n-TiO₂ cause oxidative-antioxidative imbalance by inducing ROS overproduction.

Silver Nanoparticles Induce Time- and Tissue-Specific Genotoxicity in Oreochromis niloticus: Utilizing the Adsorptive Capacities of Fruit Peels to Minimize Genotoxicity

Fish were exposed to a sub-lethal concentration of silver nanoparticles with and without orange and banana peels water treatment for 24, 48, and 96 h. The adsorption of AgNPs on both peels was recognized by scanning electron microscopic, energy dispersive X-ray spectroscopy, and laser ablation imaging. The % of DNA damage in liver and muscle tissues (comet assay) showed significant elevations in all studied groups with the maximum level in liver tissues after 24 h. DNA damage was markedly decreased after 48, and 96 h signifying the presence of an effective repairing mechanism. Micronucleus and nine nuclear anomalies were recorded in the peripheral blood cells. All anomalies were observed in all studied groups with a maximum induction rate after 96 h. of exposure. Based on the % of DNA damage and the frequencies of nuclear anomalies, water treatment with orange and banana peel succeeded to reduce AgNPs-induced genotoxic damage.

Microbial Lipopeptide Supramolecular Self-Assemblies as a Methuosis-Like Cell Death Inducer with In Vivo Antitumor Activity

Discovering new drugs and improving action mechanisms is a promising strategy to overcome chemotherapy ineffectiveness caused by cancer cell apoptosis resistance. Natural products (like cyclic lipopeptides, CLPs) are potential sources of nonapoptotic cell death inducers and can form diverse supramolecular structures, closely relating to their bioactivities. Herein, it is found for the first time that fatty chain is the key to maintain self-assembled form and antitumor activity of microbial-derived amphiphilic CLP bacillomycin Lb (B-Lb). Compared with B-Lb analogues assemblies without antitumor activity, B-Lb supramolecular self-assemblies (including nanomicelles, nanofibers, giant micrometer rods) can be generated in a multilevel and cross-scale manner and served as a methuosis-like cell death inducer triggered by cytoplasmic vacuolation through macropinocytosis in MDA-MB-231-Luc and MCF-7 cells and in vivo tumor-bearing mice. This study will promote constructing of customized CLP micro-/nanostructures with multipurposes and functions, and boost designing of new antitumor drugs as nonapoptotic cell death modulators based on structure-activity relationship.

PEGylated Recombinant Human Growth Hormone Jintrolong® Exhibits Good Long-Term Safety in Cynomolgus Monkeys and Human Pediatric Growth Hormone Deficiency Patients

Jintrolong^® is a long-acting PEGylated recombinant human growth hormone (PEG-rhGH) developed for weekly injection in patients with pediatric growth hormone deficiency (PGHD). Although PEG modification of therapeutic proteins is generally considered safe, concerns persist about the potential for adverse vacuolation in tissues with long-term exposure to PEG-included therapies, particularly in children. We assessed the safety of Jintrolong^® in cynomolgus monkeys with an examination of vacuolation in the brain choroid plexus (CP) and reported long-term clinical safety data obtained from children with PGHD. The toxicity of Jintrolong^® was assessed following the 52-week administration with doses at 0.3, 1, or 3 mg/kg/week. The levels of vacuolation of CP in animals were dose-dependent and at least partially reversible after a 104- or 157-week recovery period. Vacuolation in the CP epithelium did not lead to obvious subcellular structural or cell functional abnormalities. Compared with the clinical dose of 0.2 mg/kg/week Jintrolong^® in PGHD patients, exposure in monkeys under NOAEL 3 mg/kg/week exhibited safety margins greater than 120.5, the predicted minimum dose to induce vacuolation in monkeys is equivalent to 1.29 mg/kg/week in humans, which is 6.45-fold higher than the clinical dose. The safety data acquired in clinical trials for Jintrolong^® were also analyzed, which included phase III (360 patients), phase IV (3,000 patients) of 26-week treatment, and a follow-up study with treatment lasting for 3 years. There was no statistically significant difference in the incidence of adverse reactions between the Jintrolong^® group and the daily rhGH control group (no PEG), and no new adverse effects (AE) were observed in the Jintrolong^® group at the clinical therapeutic dose of 0.2 mg/kg/week.

Reactive Oxygen Species Mediate 6c-Induced Mitochondrial and Lysosomal Dysfunction, Autophagic Cell Death, and DNA Damage in Hepatocellular Carcinoma

Increasing the level of reactive oxygen species (ROS) in cancer cells has been suggested as a viable approach to cancer therapy. Our previous study has demonstrated that mitochondria-targeted flavone-naphthalimide-polyamine conjugate 6c elevates the level of ROS in cancer cells. However, the detailed role of ROS in 6c-treated cancer cells is not clearly stated. The biological effects and in-depth mechanisms of 6c in cancer cells need to be further investigated. In this study, we confirmed that mitochondria are the main source of 6c-induced ROS, as demonstrated by an increase in 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA) and MitoSox fluorescence. Compound 6c-induced mitochondrial ROS caused mitochondrial dysfunction and lysosomal destabilization confirmed by absolute quantitation (iTRAQ)-based comparative proteomics. Compound 6c-induced metabolic pathway dysfunction and lysosomal destabilization was attenuated by N-acetyl-L-cysteine (NAC). iTRAQ-based comparative proteomics showed that ROS regulated the expression of 6c-mediated proteins, and treatment with 6c promoted the formation of autophagosomes depending on ROS. Compound 6c-induced DNA damage was characterized by comet assay, p53 phosphorylation, and γH2A.X, which was diminished by pretreatment with NAC. Compound 6c-induced cell death was partially reversed by 3-methyladenine (3-MA), bafilomycin (BAF) A1, and NAC, respectively. Taken together, the data obtained in our study highlighted the involvement of mitochondrial ROS in 6c-induced autophagic cell death, mitochondrial and lysosomal dysfunction, and DNA damage.

Histological Changes in Renal, Hepatic and Cardiac Tissues of Wistar Rats after 6 Weeks Treatment with Bipyridine Gold (III) Complex with Dithiocarbamate Ligands

Bipyridine gold (III) dithiocarbamate compounds are Gold-III complexes with promising cytotoxic properties. In this study, the subacute toxicity of a Gold (III) complex with dithiocarbamate ligand was evaluated. In the acute toxicity component, an initial LD₅₀ (38.46 mg/kg) was calculated by the administration of 50, 100, 200, 400, and 800 mg/kg of the compound to five groups of rats, respectively (n = 4 each). The sixth group was the control. The sub-acute toxicity component comprised the control group A (n = 6) and the study groups B (n = 10) and C (n = 4), which were administered 1 mL distilled water, 1/10 LD₅₀ (3.8 mg/kg), and 1/5 LD₅₀ (7.6 mg/kg), respectively, daily for 6 weeks. The alive animals were then sacrificed. Autopsy; preservation of renal, hepatic and cardiac tissue in buffered formalin; histopathological processing; microscopic evaluation; and comparison with the controls were sequentially conducted. In the subacute toxicity study at dosages of 3.8 mg/kg and 7.6 mg/kg, the renal tubules remained unaffected with no necrosis or vacuolization. Mild to moderate renal interstitial, hepatic capsular, lobular and portal inflammation along with mild focal hepatic vacuolization were present. At 3.8 mg/kg, the cardiac muscle fibers were unremarkable in 80% (n = 8) of the specimens, with mild focal hyalinization in 20% (n = 2) of the specimens. The same was observed in 50% (n = 2) of the specimens at 7.6 mg/kg. Variable congestion was evident in all of the groups. In the subacute toxicity study, the absence of renal tubular necrosis or vacuolization, the presence of mild inflammatory hepatic and renal alterations, and predominantly unremarkable cardiac muscle fibers suggest that Bipyridine gold (III)-dithiocarbamate is safe in animal studies and is a potential candidate for clinical trials.

Combined morphological and proteome profiling reveals target-independent impairment of cholesterol homeostasis

Unbiased profiling approaches are powerful tools for small-molecule target or mode-of-action deconvolution as they generate a holistic view of the bioactivity space. This is particularly important for non-protein targets that are difficult to identify with commonly applied target identification methods. Thereby, unbiased profiling can enable identification of novel bioactivity even for annotated compounds. We report the identification of a large bioactivity cluster comprised of numerous well-characterized drugs with different primary targets using a combination of the morphological Cell Painting Assay and proteome profiling. Cluster members alter cholesterol homeostasis and localization due to their physicochemical properties that lead to protonation and accumulation in lysosomes, an increase in lysosomal pH, and a disturbed cholesterol homeostasis. The identified cluster enables identification of modulators of cholesterol homeostasis and links regulation of genes or proteins involved in cholesterol synthesis or trafficking to physicochemical properties rather than to nominal targets.

Pendimethalin-based herbicide impairs cellular immune response and haemocyte morphology in a beneficial ground beetle

Herbicides have become the most commonly applied agrochemicals in agroecosystems. Thus, basic knowledge of their physiological effects on insects is needed, especially for understanding their impact on beneficial insect species. In this study, we evaluated the effect of a pendimethalin-based herbicide (PND) on the cellular immune response of the carabid beetle Harpalus (Pseudoophonus) rufipes (De Geer 1774) (Coleoptera, Carabidae), acting as biocontrol agent in agroecosystems. Total and differential haemocyte counts and phagocytosis assay, performed by injecting in vivo carboxylate-modified polystyrene latex beads, were measured in beetles exposed to a recommended field dose (4L per ha) of PND to evaluate the exposure effects over the time. The pattern of haemocyte subpopulations and the decrease of the phagocytic index after the exposure to PND suggested a lowering of P. rufipes ability to face an infection performing a cell-mediated response. PND was also found to cause cytotoxic effects on the haemocyte ultrastructure. Ultrastructural alterations such as irregular shape, large vacuolization of the cytoplasm, and condensation of marginated chromatin were recorded from 2d of exposure. The loss of RER, Golgi apparatus, mitochondria integrity and the swelling of the outer nuclear membrane found in some haemocytes suggested an interference of PND with the membrane permeability. Results indicated that the exposure to PND impairs the distribution, morphology and physiological functions of haemocytes causing a decrease of P. rufipes immunocompetence. Moreover, the sensitivity to herbicide exposure makes this species a suitable model and a useful bioindicator for monitoring exposure effects on non-target species. This study provides useful information to protect and preserve biodiversity of insects in agroecosystems.

Cl-Amidine Improves Survival and Attenuates Kidney Injury in a Rabbit Model of Endotoxic Shock

Objective: Sepsis causes millions of deaths on a global scale annually. Activation of peptidylarginine deiminase (PAD) enzymes in sepsis causes citrullination of histones, which results in neutrophil extracellular trap formation and sepsis progression. This study evaluates pan-PAD inhibitor, Cl-amidine, in a model of lipopolysaccharide (LPS)-induced endotoxic shock in rabbits. We hypothesized that Cl-amidine would improve survival and attenuate kidney injury. Methods: In the survival model, rabbits were injected injected intravenously with 1 mg/kg of LPS, and then randomly assigned either to receive dimethyl sulfoxide (DMSO; 1 mcL/g) or Cl-amidine (10 mg/kg diluted in 1 mcL/g DMSO). They were then monitored for 14 days to evaluate survival. In the non-survival experiment, the same insult and treatment were administered, however; the animals were euthanized 12 hours after LPS injection for kidney harvest. Acute kidney injury (AKI) scoring was performed by a histopathologist who was blinded to the group assignment. Serial blood samples were also collected and compared. Results: Rabbits that received Cl-amidine had a higher survival (72%) compared with the rabbits that received DMSO (14%; p < 0.05). Cl-amidine-treated rabbits had lower (p < 0.05) histopathologic AKI scores, as well as plasma creatinine and blood urea nitrogen (BUN) levels 12 hours after insult. Conclusions: Pan-PAD inhibitor Cl-amidine improves survival and attenuates kidney injury in LPS-induced endotoxic shock in rabbits.

Maduramicin induces cardiotoxicity via Rac1 signaling-independent methuosis in H9c2 cells

Maduramicin frequently induces severe cardiotoxicity in target and nontarget animals in clinic. Apoptotic and non-apoptotic cell death mediate its cardiotoxicity; however, the underlying non-apoptotic cell death induced by maduramicin remains unclear. In current study, a recently described non-apoptotic cell death "methuosis" caused by maduramicin was defined in mammalian cells. Rat myocardial cell H9c2 was used as an in vitro model, showing excessively cytoplasmic vacuolization upon maduramicin (0.0625-5 μg/mL) exposure for 24 h. Maduramicin-induced reversible cytoplasmic vacuolization of H9c2 cells in a time- and concentration-dependent manner. The vacuoles induced by maduramicin were phase lucent with single membrane and were not derived from the swelling of organelles such as mitochondria, endoplasmic reticulum, lysosome, and Golgi apparatus. Furthermore, maduramicin-induced cytoplasmic vacuoles are generated from micropinocytosis, which was demonstrated by internalization of extracellular fluid-phase marker Dextran-Alexa Fluor 488 into H9c2 cells. Intriguingly, these cytoplasmic vacuoles acquired some characteristics of late endosomes and lysosomes rather than early endosomes and autophagosomes. Vacuolar H⁺ -ATPase inhibitor bafilomycin A1 efficiently prevented the generation of cytoplasmic vacuoles and decreased the cytotoxicity of H9c2 cells triggered by maduramicin. Mechanism studying indicated that maduramicin activated H-Ras-Rac1 signaling pathway at both mRNA and protein levels. However, the pharmacological inhibition and siRNA knockdown of Rac1 rescued maduramicin-induced cytotoxicity of H9c2 cells but did not alleviate cytoplasmic vacuolization. Based on these findings, maduramicin induces methuosis in H9c2 cells via Rac-1 signaling-independent seriously cytoplasmic vacuolization.

Aptamer-Driven Toxin Gene Delivery in U87 Model Glioblastoma Cells

A novel suicide gene therapy approach was tested in U87 MG glioblastoma multiforme cells. A 26nt G-rich double-stranded DNA aptamer (AS1411) was integrated into a vector at the 5' of a mammalian codon-optimized saporin gene, under CMV promoter. With this plasmid termed "APTSAP", the gene encoding ribosome-inactivating protein saporin is driven intracellularly by the glioma-specific aptamer that binds to cell surface-exposed nucleolin and efficiently kills target cells, more effectively as a polyethyleneimine (PEI)-polyplex. Cells that do not expose nucleolin at the cell surface such as 3T3 cells, used as a control, remain unaffected. Suicide gene-induced cell killing was not observed when the inactive saporin mutant SAPKQ DNA was used in the (PEI)-polyplex, indicating that saporin catalytic activity mediates the cytotoxic effect. Rather than apoptosis, cell death has features resembling autophagic or methuosis-like mechanisms. These main findings support the proof-of-concept of using PEI-polyplexed APTSAP for local delivery in rat glioblastoma models.

Akebia saponin E, as a novel PIKfyve inhibitor, induces lysosome-associated cytoplasmic vacuolation to inhibit proliferation of hepatocellular carcinoma cells

ETHNOPHARMACOLOGICAL RELEVANCE

Hepatocellular carcinoma (HCC) is an aggressive malignancy with increasing mortality in China. Screening and identifying effective anticancer compounds from active traditional Chinese herbs for HCC are in demand. Akebia trifoliata (Thunb) Koidz, with pharmacological anti-HCC activities in clinical, has been shown in previous research. In the present research, we elucidated a potential anticancer effect of Akebia saponin E (ASE), which is isolated from the immature seeds of Akebia trifoliata (Thunb.) Koidz, and revealed that ASE could induce severe expanded vacuoles in HCC cells. But the potential mechanism of vacuole-formation and the anti-HCC effects by ASE remain uncover.

AIM OF THIS STUDY

To elucidate the potential mechanism of vacuole-formation and the proliferation inhibition effects by ASE in HCC cell lines.

MATERIALS AND METHODS

MTT assay, colony formation assay and flow cytometry were performed to detect cell viability. Immunofluorescence analysis was used to examine the biomarkers of endomembrane. Cells were infected with tandem mRFP-GFP-LC3 lentivirus to assess autophagy flux. RNA-seq was conducted to analyze the genome-wide transcriptional between treatment cell groups. In vitro PIKfyve kinase assay is detected by the ADP-Glo^TM Kinase Assay Kit.

RESULTS

ASE could inhibit the proliferation of HCC with severe expanded vacuoles in vitro, and could significantly reduce the size and weight of xenograft tumor in vivo. Further, the vacuoles induced by ASE were aberrant enlarged lysosomes instead of autophagosome or autolysosomes. With cytoplasmic vacuolation, ASE induced a mTOR-independent TFEB activation for lysosomal biogenesis and a decrement of cholesterol levels in HCC cells. Furthermore, ASE could reduce the activity of PIKfyve (phosphoinositide kinase containing a FYVE-type finger), causing aberrant lysosomal biogenesis and cholesterol dyshomeostasis which triggered the expanded vacuole formation.

CONCLUSION

ASE can prospectively inhibit the kinase activity of PIKfyve to induce lysosome-associated cytoplasmic vacuolation, and may be utilized as an alternative candidate to treat human HCC.

Repurposing Sigma-1 Receptor Ligands for COVID-19 Therapy?

Outbreaks of emerging infections, such as COVID-19 pandemic especially, confront health professionals with the unique challenge of treating patients. With no time to discover new drugs, repurposing of approved drugs or in clinical development is likely the only solution. Replication of coronaviruses (CoVs) occurs in a modified membranous compartment derived from the endoplasmic reticulum (ER), causes host cell ER stress and activates pathways to facilitate adaptation of the host cell machinery to viral needs. Accordingly, modulation of ER remodeling and ER stress response might be pivotal in elucidating CoV-host interactions and provide a rationale for new therapeutic, host-based antiviral approaches. The sigma-1 receptor (Sig-1R) is a ligand-operated, ER membrane-bound chaperone that acts as an upstream modulator of ER stress and thus a candidate host protein for host-based repurposing approaches to treat COVID-19 patients. Sig-1R ligands are frequently identified in in vitro drug repurposing screens aiming to identify antiviral compounds against CoVs, including severe acute respiratory syndrome CoV-2 (SARS-CoV-2). Sig-1R regulates key mechanisms of the adaptive host cell stress response and takes part in early steps of viral replication. It is enriched in lipid rafts and detergent-resistant ER membranes, where it colocalizes with viral replicase proteins. Indeed, the non-structural SARS-CoV-2 protein Nsp6 interacts with Sig-1R. The activity of Sig-1R ligands against COVID-19 remains to be specifically assessed in clinical trials. This review provides a rationale for targeting Sig-1R as a host-based drug repurposing approach to treat COVID-19 patients. Evidence gained using Sig-1R ligands in unbiased in vitro antiviral drug screens and the potential mechanisms underlying the modulatory effect of Sig-1R on the host cell response are discussed. Targeting Sig-1R is not expected to reduce dramatically established viral replication, but it might interfere with early steps of virus-induced host cell reprogramming, aid to slow down the course of infection, prevent the aggravation of the disease and/or allow a time window to mature a protective immune response. Sig-1R-based medicines could provide benefit not only as early intervention, preventive but also as adjuvant therapy.

Inhibition of ATR-Chk1 signaling blocks DNA double-strand-break repair and induces cytoplasmic vacuolization in metastatic osteosarcoma

BACKGROUND

Ataxia-telangiectasia and Rad3 related protein kinase (ATR) is an essential regulator of the DNA damage response in various cancers; however, its expression and roles in osteosarcoma are unclear. We therefore chose to evaluate the significance and mechanism of ATR in metastatic osteosarcoma, as well as its potential to be a therapeutic target.

METHODS

The osteosarcoma tissue microarrays constructed from 70 patient specimens underwent immunohistochemistry to quantify ATR and activated phospho-ATR (pATR) expression and their correlation with clinical outcomes. ATR sublocalization within the metastatic osteosarcoma cells was confirmed by immunofluorescence assay. Cell proliferation, apoptosis, and migration were evaluated following treatment with ATR siRNA or the selective inhibitor Berzosertib. Antitumor effects were determined with ex vivo three-dimensional (3D) culture models, and the impacts on the DNA damage repair pathways were measured with Western blotting.

RESULTS

Elevated ATR and activated pATR expression correlated with shorter patient survival and less necrosis following neoadjuvant chemotherapy. Intranuclear sublocalization of ATR and pATR suggested a mechanism related to DNA replication. ATR knockdown with siRNA or inhibition with Berzosertib suppressed cell proliferation in a time- and dose-dependent manner and induced apoptosis. In addition, ATR inhibition decreased Chk1 phosphorylation while increasing γH2AX expression and PARP cleavage, consistent with the interference of DNA damage repair. The ATR inhibitor Berzosertib also produced the characteristic cytoplasmic vacuolization preceding cell death, and suppressed ex vivo 3D spheroid formation and cell motility.

CONCLUSION

The faithful dependence of cells on ATR signaling for survival and progression makes it an emerging therapeutic target in metastatic osteosarcoma.

Low dose novel PARP-PI3K inhibition via nanoformulation improves colorectal cancer immunoradiotherapy

Multimodal therapy is often used in oncology to overcome dosing limitations and chemoresistance. Recently, combination immunoradiotherapy has shown great promise in a select subset of patients with colorectal cancer (CRC). Furthermore, molecularly targeted agents delivered in tandem with immunotherapy regimens have been suggested to improve treatment outcomes and expand the population of responding patients. In this study, radiation-sensitizing small molecules niraparib (PARP inhibitor) and HS-173 (PI3K inhibitor) are identified as a novel combination that synergistically enhance toxicity and induce immunogenic cell death both in vitro and in vivo in a CRC model. These inhibitors were co-encapsulated in a polymer micelle to overcome solubility limitations while minimizing off-target toxicity. Mice bearing syngeneic colorectal tumors (CT26) were administered these therapeutic micelles in combination with X-ray irradiation and anti-CTLA-4 immunotherapy. This combination led to enhanced efficacy demonstrated by improved tumor control and increased tumor infiltrating lymphocytes. This report represents the first investigation of DNA damage repair inhibition combined with radiation to potentiate anti-CTLA-4 immunotherapy in a CRC model.

Maduramicin triggers methuosis-like cell death in primary chicken myocardial cells

Maduramicin frequently induces severe cardiotoxicity in broiler chickens as well as in humans who consume maduramicin accidentally. Apoptosis and non-apoptotic cell death occur concurrently in the process of maduramicin-induced cardiotoxicity; however, the underlying mechanism of non-apoptotic cell death is largely unknown. Here, we report the relationship between maduramicin-caused cytoplasmic vacuolization and methuosis-like cell death as well as the underlying mechanism in primary chicken myocardial cells. Maduramicin induced a significant increase of cytoplasmic vacuoles with a degree of cell specificity in primary chicken embryo fibroblasts and chicken hepatoma cells (LMH), along with a decrease of ATP and an increase of LDH. The accumulated vacuoles were partly derived from cellular endocytosis rather than the swelling of endoplasm reticulum, lysosomes, and mitochondria. Moreover, the broad-spectrum caspase inhibitor carbobenzoxy-Val-Ala-Asp-fluoromethylketone (z-VAD-fmk) did not prevent maduramicin-induced cytoplasmic vacuolization. DNA ladder and cleavage of PARP were not observed in chicken myocardial cells during maduramicin exposure. Pretreatment with 3-methyladenine (3-MA) and cholorquine (CQ) of chicken myocardial cells did not attenuate cytoplasmic vacuolization and cytotoxicity, although LC3 and p62 were activated. Bafilomycin A1 almost completely prevented the generation of cytoplasmic vacuoles and significantly attenuated cytotoxicity induced by maduramicin, along with downregulation of K-Ras and upregulation of Rac1. Taken together, "methuosis" due to excessive cytoplasmic vacuolization mediates the cardiotoxicity of maduramicin. This provides new insights for understanding a nonclassical form of cell death in the field of drug-induced cytotoxicity.

Autophagy Participates in Lysosomal Vacuolation-Mediated Cell Death in RGNNV-Infected Cells

Nervous necrosis virus (NNV) is the etiological agent of viral nervous necrosis (VNN), also known as viral encephalopathy and retinopathy (VER), which results in heavy economic losses to the aquaculture industry worldwide. Dramatic cytoplasmic vacuoles were observed during NNV infection both in vitro and in vivo; however, the origin and mechanism of cytoplasmic vacuolization remains unknown. In this report, we found that the cytoplasmic vacuole morphology became fused and enlarged during infection with red spotted grouper nervous necrosis virus (RGNNV), which was accompanied by increased cell death. Notably, Lyso-Tracker, but not Mito-Tracker or ER-Tracker, was accumulated in the vacuoles, and abnormal lysosome swelling was observed in RGNNV-infected cells, suggesting that the cytoplasmic vacuoles originated from lysosomal organelles. Cytoplasmic vacuolization and cell death in RGNNV-infected cells was completely blocked by the vacuolar H⁺-ATPase inhibitor (bafilomycin A1), and was significantly weakened by chloroquine (CQ), a lysosomotropic agent that induces the acidification of the lysosomes. This suggests that lysosome acidification was essential for vacuole formation. Significant inhibitory effects on vacuolization and cell death were also observed in the RGNNV-infected cells following treatment with nigericin and monensin (ionophores that uncouple the proton gradient present in lysosomes). This indicated that lysosome function was tightly associated with RGNNV infection-induced cell death. In addition, vacuoles were found to be partially co-localized with GFP-LC3II punctate dots during RGNNV infection. Moreover, the severity of vacuolization and cell death were both significantly decreased after treatment with the autophagy inhibitor, 3-MA, suggesting that autophagy was involved in lysosomal vacuolization and cell death evoked by RGNNV infection. Thus, our results demonstrate that autophagy participates in lysosomal vacuolation-mediated cell death during RGNNV infection, and provides new insight into our understanding of the potential mechanisms underlying nodavirus pathogenesis in vitro.

Non-apoptotic cell death induced by opening the large conductance mechanosensitive channel MscL in hepatocellular carcinoma HepG2 cells

Most anticancer therapies trigger apoptosis to eliminate malignant cells. However, the majority of malignant cancer cells are resistant to apoptosis due to genetic mutations or heterogeneity. Here, we report that opening the pore of the bacterial large conductance mechanosensitivity channel (MscL) provides a novel approach of inducing non-apoptotic cell death. The gain-of-function mutant V23A-MscL and chemically responsive mutant G26C-MscL can be functionally expressed in hepatocellular carcinoma HepG2 cells. V23A-MscL spontaneously opens, and G26C-MscL also responds to its chemical activator MTSET. Opening of the MscL channel causes increased intracellular Ca²⁺ concentration and suppressed cell growth and viability. MTSET-activated G26C channels induce necrosis, while V23A-MscL expression leads to cytoplasmic vacuolization cell death in HepG2 cells and suppresses tumor growth in a mouse model. We propose that MscL may act as a nanovalve through which intracellular homeostasis suffers a disruption and results in malignant tumor cell damage, leading to a new strategy for cancer therapy.

Fenretinide induces a new form of dynamin-dependent cell death in pediatric sarcoma

Alveolar rhabdomyosarcoma (aRMS) is a highly malicious childhood malignancy characterized by specific chromosomal translocations mostly encoding the oncogenic transcription factor PAX3-FOXO1 and therefore also referred to as fusion-positive RMS (FP-RMS). Previously, we have identified fenretinide (retinoic acid p-hydroxyanilide) to affect PAX3-FOXO1 expression levels as well as FP-RMS cell viability. Here, we characterize the mode of action of fenretinide in more detail. First, we demonstrate that fenretinide-induced generation of reactive oxygen species (ROS) depends on complex II of the mitochondrial respiratory chain, since ROS scavenging as well as complexing of iron completely abolished cell death. Second, we co-treated cells with a range of pharmacological inhibitors of specific cell death pathways including z-vad (apoptosis), necrostatin-1 (necroptosis), 3-methyladenine (3-MA) (autophagy), and ferrostatin-1 (ferroptosis) together with fenretinide. Surprisingly, none of these inhibitors was able to prevent cell death. Also genetic depletion of key players in the apoptotic and necroptotic pathway (BAK, BAX, and RIPK1) confirmed the pharmacological data. Interestingly however, electron microscopy of fenretinide-treated cells revealed an excessive accumulation of cytoplasmic vacuoles, which were distinct from autophagosomes. Further flow cytometry and fluorescence microscopy experiments suggested a hyperstimulation of macropinocytosis, leading to an accumulation of enlarged early and late endosomes. Surprisingly, pharmacological inhibition as well as genetic depletion of large dynamin GTPases completely abolished fenretinide-induced vesicle formation and subsequent cell death, suggesting a new form of dynamin-dependent programmed cell death. Taken together, our data identify a new form of cell death mediated through the production of ROS by fenretinide treatment, highlighting the value of this compound for treatment of sarcoma patients including FP-RMS.

The fungicide iprodione affects midgut cells of non-target honey bee Apis mellifera workers

The honey bee Apis mellifera is an important pollinator of agricultural crops and natural forests. Honey bee populations have declined over the years, as a result of diseases, pesticides, and management problems. Fungicides are the main pesticides found in pollen grains, which are the major source of protein for bees. The objective of this study was to evaluate the cytotoxic effects of the fungicide iprodione on midgut cells of adult A. mellifera workers. Bees were fed on iprodione (LD₅₀, determined by the manufacturer) for 12 or 24 h, and the midgut was examined using light and transmission electron microscopies. The expression level of the autophagy gene atg1 was assessed in midgut digestive cells. Cells of treated bees had signs of apoptosis: cytoplasmic vacuolization, apical cell protrusions, nuclear fragmentation, and chromatin condensation. Ultrastructural analysis revealed some cells undergoing autophagy and necrosis. Expression of atg1 was similar between treated and control bees, which can be explained by the facts that digestive cells had autolysosomes, whereas ATG-1 is found in the initial phases of autophagy. Iprodione acts by inhibiting the synthesis of glutathione, leading to the generation of reactive oxygen species, which in turn can induce different types of cell death. The results indicate that iprodione must be used with caution because it has side effects on non-target organisms, such as pollinator bees.

Loss of MYO5B expression deregulates late endosome size which hinders mitotic spindle orientation

Recycling endosomes regulate plasma membrane recycling. Recently, recycling endosome–associated proteins have been implicated in the positioning and orientation of the mitotic spindle and cytokinesis. Loss of MYO5B, encoding the recycling endosome–associated myosin Vb, is associated with tumor development and tissue architecture defects in the gastrointestinal tract. Whether loss of MYO5B expression affects mitosis is not known. Here, we demonstrate that loss of MYO5B expression delayed cytokinesis, perturbed mitotic spindle orientation, led to the misorientation of the plane of cell division during the course of mitosis, and resulted in the delamination of epithelial cells. Remarkably, the effects on spindle orientation, but not cytokinesis, were a direct consequence of physical hindrance by giant late endosomes, which were formed in a chloride channel–sensitive manner concomitant with a redistribution of chloride channels from the cell periphery to late endosomes upon loss of MYO5B. Rab7 availability was identified as a limiting factor for the development of giant late endosomes. In accordance, increasing rab7 availability corrected mitotic spindle misorientation and cell delamination in cells lacking MYO5B expression. In conclusion, we identified a novel role for MYO5B in the regulation of late endosome size control and identify the inability to control late endosome size as an unexpected novel mechanism underlying defects in cell division orientation and epithelial architecture.

Loss of the recycling endosome-associated motor protein myosin Vb causes the formation of giant late endo-lysosomes; these in turn hinder the orientation of the mitotic spindle and chromosome segregation. Deregulated endosome size thus hampers faithful cell division.

The effects of L-NAME on DU145 human prostate cancer cell line: A cytotoxicity-based study

Of all cancer types, prostate cancer is the second most common one with an age-standardized incidence rate of 29.3 per 100,000 men worldwide. Nitric oxide (NO) is both a radical and versatile messenger molecule involved in many physiological activities. NO was documented to be highly secreted and utilized by cancer cells. Nω-nitro-L-arginine methyl ester (L-NAME) is utilized for inhibiting NO synthase. Its worst long-term side effect is reported to be hypertension, hence less cytotoxic than chemotherapeutic agents. Herein, we carried out a cytotoxicity study on how different doses of L-NAME affect DU145 human prostate cancer cells. First, toxic doses of L-NAME were determined. Then, while antioxidant capacity was determined by glutathione and total antioxidant status, oxidative stress was evaluated by quantifying malondialdehyde, NO, and total oxidant status levels. Inflammatory effects of L-NAME were investigated by measuring tumor necrosis factor-α and interleukin-6 (IL-6) levels. Apoptotic effects of L-NAME were evaluated by measuring cytochrome C somatic and caspase 3 levels and by staining Bax protein. Finally, morphological analysis was performed. IC50 of L-NAME against DU145 cells was 12.2 mM. In L-NAME-treated DU145 cells, a dose-dependent increase in oxidative stress, inflammatory, and apoptotic marker proteins and decrease in antioxidant capacity were observed. While at the moderate dose of L-NAME, apoptotic changes were commonly observed, at higher doses, vacuolated and swollen cells were also recorded. We believe that the present study will encourage future studies by providing insights about dose and effects of L-NAME.

Ganglioside GM2 catabolism is inhibited by storage compounds of mucopolysaccharidoses and by cationic amphiphilic drugs

The catabolism of ganglioside GM2 is dependent on the lysosomal enzyme β-hexosaminidase A and a supporting lipid transfer protein, the GM2 activator protein. A genetically based disturbance of GM2 catabolism, leads to several subtypes of the GM2 gangliosidosis: Tay-Sachs disease, Sandhoff disease, the AB-variant and the B1-variant, all of them having GM2 as major lysosomal storage compound. Further on it is known that the gangliosides GM2 and GM3 accumulate as secondary storage compounds in mucopolysaccharidoses, especially in Hunter disease, Hurler disease, Sanfilippo disease and Sly syndrome, with chondroitin sulfate as primary storage compound. The exact mechanism of ganglioside accumulation in mucopolysaccaridoses is still a matter of debate. Here, we show that chondroitin sulfate strongly inhibits the catabolism of membrane-bound GM2 by β-hexosaminidase A in presence of GM2 activator protein in vitro already at low micromolar concentrations. In contrast, hyaluronan, the major storage compound in mucopolysaccharidosis IX, a milder disease without secondary ganglioside accumulation, is a less effective inhibitor. On the other hand, hydrolysis of micellar-bound GM2 by β-hexosaminidase A without the assistance of GM2AP was not impeded by chondroitin sulfate implicating that the inhibition of GM2 hydrolysis by chondroitin sulfate is most likely based on an interaction with GM2AP, the GM2AP-GM2 complex or the GM2-carrying membranes. We also studied the influence of some cationic amphiphilic drugs (desipramine, chlorpromazine, imipramine and chloroquine), provoking drug induced phospholipidosis and found that all of them inhibited the hydrolysis of GM2 massively.

Cytoplasmic Vacuolation and Tapetal Changes Induced by a Novel Analgesic Agent in Beagle Dogs

Drug-induced unique cytoplasmic vacuolation was found in the subchronic oral toxicity study of 4-dimethylamino-1-{3-(1-methyl-1H-imidazole-2-yl)propanoyl}piperidine (DMIP), a potential therapeutic agent for neuropathic pain, in beagle dogs. In the first study, DMIP was administered at a dose of 250, 500, or 1,000 mg/kg/day once daily for 14 days. Discoloration of tapetum lucidum accompanied by tapetal swelling was observed at ≥250 mg/kg/day. The tapetal swelling was correlated to the light microscopic observation of cytoplasmic vacuolation in tapetal cells, and similar vacuolation was observed in several other tissues, including the coronary artery and aortal arch, in a dose-dependent manner. Immunohistochemistry for lysosomal-associated membrane protein 2 indicated that the vacuoles were enlarged lysosomes. However, the nature of these vacuoles was different from that of phospholipidosis because no lamellar bodies were observed. In the second study, DMIP was administered at a dose of 10, 50, or 250 mg/kg/day once daily for 14 days followed by a 14-day recovery period. Tapetal changes and systemic vacuolation were not observed at ≤50 mg/kg/day, and vacuolation observed at 250 mg/kg/day was reversible. A few reports have described the enlargement of lysosomes not attributable to phospholipid accumulation. Our findings provide further information about the toxicological implications of drug-induced lysosomal swelling.