Membrane blebbing during apoptosis results from caspase-mediated activation of ROCK I

AT101-Loaded Cubosomes as an Alternative for Improved Glioblastoma Therapy

Introduction

AT101, the R-(-)-enantiomer of the cottonseed-derived polyphenol gossypol, is a promising drug in glioblastoma multiforme (GBM) therapy due to its ability to trigger autophagic cell death but also to facilitate apoptosis in tumor cells. It does have some limitations such as poor solubility in water-based media and consequent low bioavailability, which affect its response rate during treatment. To overcome this drawback and to improve the anti-cancer potential of AT101, the use of cubosome-based formulation for AT101 drug delivery has been proposed. This is the first report on the use of cubosomes as AT101 drug carriers in GBM cells.

Materials and Methods

Cubosomes loaded with AT101 were prepared from glyceryl monooleate (GMO) and the surfactant Pluronic F-127 using the top-down approach. The drug was introduced into the lipid prior to dispersion. Prepared formulations were then subjected to complex physicochemical and biological characterization.

Results

Formulations of AT101-loaded cubosomes were highly stable colloids with a high drug entrapment efficiency (97.7%) and a continuous, sustained drug release approaching 35% over 72 h. Using selective and sensitive NMR diffusometry, the drug was shown to be efficiently bound to the lipid-based cubosomes. In vitro imaging studies showed the high efficiency of cubosomal nanoparticles uptake into GBM cells, as well as their marked ability to penetrate into tumor spheroids. Treatment of GBM cells with the AT101-loaded cubosomes, but not with the free drug, induced cytoskeletal rearrangement and shortening of actin fibers. The prepared nanoparticles revealed stronger in vitro cytotoxic effects against GBM cells (A172 and LN229 cell lines), than against normal brain cells (SVGA and HMC3 cell lines).

Conclusion

The results indicate that GMO-AT101 cubosome formulations are a promising basic tool for alternative approaches to GBM treatment.

Extracellular Vesicles Derived From Apoptotic Cells: An Essential Link Between Death and Regeneration

Apoptosis is a universal and continuous event during tissue development, restoration, repair, and regeneration. Mounting evidence has demonstrated that apoptosis is essential for the activation of tissue regeneration. However, the underlying mechanism remains elusive. A striking development in recent years comes from research on extracellular vesicles (EVs) derived from apoptotic cells. During apoptosis, cells secrete vesicles of various sizes containing various components. Apoptotic cell-derived EVs (ApoEVs) have been found to transit to neighboring cells or cells in distant tissues through the circulation. These vesicles could act as containers to transmit the nucleic acid, protein, and lipid signals to target cells. ApoEVs have been shown to promote regeneration in the cardiovascular system, skin, bone, muscle, kidney, etc. Moreover, several specific signaling pathways mediating the anabolic effects of ApoEVs have been classified. In this review, we comprehensively discussed the latest findings on the function of ApoEVs in tissue regeneration and disease prevention. These findings may reveal unexpected clues regarding the regulatory network between cell death and tissue regeneration and suggest novel targets for regenerative medicine. The findings discussed here also raise the question whether and to what extent ApoEVs contribute to embryonic development. This question is all the more urgent because the exact functions of apoptotic events during numerous developmental processes are still largely unclear.

Cell Death in the Tumor Microenvironment: Implications for Cancer Immunotherapy

The physiological fate of cells that die by apoptosis is their prompt and efficient removal by efferocytosis. During these processes, apoptotic cells release intracellular constituents that include purine nucleotides, lysophosphatidylcholine (LPC), and Sphingosine-1-phosphate (S1P) that induce migration and chemo-attraction of phagocytes as well as mitogens and extracellular membrane-bound vesicles that contribute to apoptosis-induced compensatory proliferation and alteration of the extracellular matrix and the vascular network. Additionally, during efferocytosis, phagocytic cells produce a number of anti-inflammatory and resolving factors, and, together with apoptotic cells, efferocytic events have a homeostatic function that regulates tissue repair. These homeostatic functions are dysregulated in cancers, where, aforementioned events, if not properly controlled, can lead to cancer progression and immune escape. Here, we summarize evidence that apoptosis and efferocytosis are exploited in cancer, as well as discuss current translation and clinical efforts to harness signals from dying cells into therapeutic strategies.

Molecular signatures of beef tenderness: Underlying mechanisms based on integromics of protein biomarkers from multi-platform proteomics studies

Over the last two decades, proteomics have been employed to decipher the underlying factors contributing to variation in the quality of muscle foods, including beef tenderness. One such approach is the application of high-throughput protein analytical platforms in the identification of meat quality biomarkers. To broaden our understanding about the biological mechanisms underpinning meat tenderization across a large number of studies, an integromics study was performed to review the current status of protein biomarker discovery targeting beef tenderness. This meta-analysis is the first to gather and propose a comprehensive list of 124 putative protein biomarkers derived from 28 independent proteomics-based experiments, from which 33 robust candidates were identified worthy of evaluation using targeted or untargeted data-independent acquisition proteomic methods. We further provide an overview of the interconnectedness of the main biological pathways impacting tenderness determination after multistep analyses including Gene Ontology annotations, pathway and process enrichment and literature mining, and specifically discuss the major proteins and pathways most often reported in proteomics research.

Plexin B2 Is a Regulator of Monocyte Apoptotic Cell Disassembly

Billions of cells undergo apoptosis daily and often fragment into small, membrane-bound extracellular vesicles termed apoptotic bodies (ApoBDs). We demonstrate that apoptotic monocytes undergo a highly coordinated disassembly process and form long, beaded protrusions (coined as beaded apoptopodia), which fragment to release ApoBDs. Here, we find that the protein plexin B2 (PlexB2), a transmembrane receptor that regulates axonal guidance in neurons, is enriched in the ApoBDs of THP1 monocytes and is a caspase 3/7 substrate. To determine whether PlexB2 is involved in the disassembly of apoptotic monocytes, we generate PlexB2-deficient THP1 monocytes and demonstrate that lack of PlexB2 impairs the formation of beaded apoptopodia and ApoBDs. Consequently, the loss of PlexB2 in apoptotic THP1 monocytes impairs their uptake by both professional and non-professional phagocytes. Altogether, these data identify PlexB2 as a positive regulator of apoptotic monocyte disassembly and demonstrate the importance of this process in apoptotic cell clearance.

Switching of cell fate through the regulation of cell growth during drug-induced intrahepatic cholestasis

Understanding the fundamental mechanisms that govern the fate of cells during drug-induced intrahepatic cholestasis provides strategies for the establishment of evaluation methods for drug screening. In the present study, the aggregates of a differentiated human hepatic cell line, HepaRG, were incubated in medium with Y27632 or bosentan to clarify the changes in the behavior of bile canaliculi (BC) with the growth of cells during drug-induced intrahepatic cholestasis. With elapsed exposure time, the aggregates in the culture with bosentan caused the dilation of BC, and the hepatocytes ultimately exhibited apoptotic death after the disruption of BC. Y27632 caused the disruption of BC in the aggregates after dilation. However, there was no change in the number of cells within the aggregates in the culture with Y27632, in spite of its cytotoxicity. After 144 h from the start of Y27632 exposure, the aggregates showed the rearrangement of BC. To inhibit cell division, the aggregates exposed to Y27632, which exhibited disruption of BC, were treated with mitomycin C for 2 h and continuously exposed to Y27632. The inhibition of cell division could not induce the rearrangement of BC within these aggregates, which was similar to the phenomenon observed in the aggregates exposed to bosentan. These findings indicate that growth is an important factor that influences the switching of cell fate toward survival or death in drug-induced intrahepatic cholestasis process. Thus, the autoregulation of growth is a major contributor to the rearrangement of BC within aggregates.

Multifunctional zeolitic imidazolate framework-8 for real-time monitoring ATP fluctuation in mitochondria during photodynamic therapy

Zeolitic imidazolate framework-8 (ZIF-8) is emerging as a promising vector in encapsulation and delivery of imaging agents or drugs. Adenosine triphosphate (ATP) is the primary energy source in cells and plays a key role in many cellular processes. Although numerous probes have been developed for ATP detection, only a few of them were used to real-time monitor ATP fluctuation in mitochondria during photodynamic therapy (PDT). Here, an ATP-responsive and fluorescent ZIF-8 is synthesized for real-time monitoring mitochondrial ATP fluctuation in living cells during photodynamic therapy. Rhodamine B (RhB) as a fluorescent indicator is encapsulated into ZIF-8 to form multifunctional RhB@ZIF-8 via a one step process. RhB@ZIF-8 can rapidly respond to ATP with ZIF-8 decomposition and fluorescence off-on switch via a competitive coordination interaction and exhibits good sensitivity and selectivity to ATP with a detection limit of 35 μM. Furthermore, RhB@ZIF-8 is successfully utilized for real-time monitoring and imaging mitochondrial ATP fluctuation in living cells during photodynamic therapy with good biocompatibility and high cell permeability. It is found that the ATP levels in mitochondria increased within 1 min of light irradiation and then decreased with further increase of the light irradiation time during PDT using an Ir(iii) complex. This work demonstrates that RhB@ZIF-8 can serve as a promising fluorescent probe to monitor mitochondrial ATP fluctuation with fast response, good sensitivity and endogenous molecule-responsive properties inside living cells.

Defining the role of cytoskeletal components in the formation of apoptopodia and apoptotic bodies during apoptosis

During apoptosis, dying cells undergo dynamic morphological changes that ultimately lead to their disassembly into fragments called apoptotic bodies (ApoBDs). Reorganisation of the cytoskeletal structures is key in driving various apoptotic morphologies, including the loss of cell adhesion and membrane bleb formation. However, whether cytoskeletal components are also involved in morphological changes that occur later during apoptosis, such as the recently described generation of thin apoptotic membrane protrusions called apoptopodia and subsequent ApoBD formation, is not well defined. Through monitoring the progression of apoptosis by confocal microscopy, specifically focusing on the apoptopodia formation step, we characterised the presence of F-actin and microtubules in a subset of apoptopodia generated by T cells and monocytes. Interestingly, targeting actin polymerisation and microtubule assembly pharmacologically had no major effect on apoptopodia formation. These data demonstrate apoptopodia as a novel type of membrane protrusion that could be formed in the absence of actin polymerisation and microtubule assembly.

Effect of Physical Exercise on the Release of Microparticles with Angiogenic Potential

Cellular communication has a fundamental role in both human physiological and pathological states and various mechanisms are involved in the crosstalk between organs. Among these, microparticles (MPs) have an important involvement. MPs are a subtype of extracellular vesicles produced by a variety of cells following activation or apoptosis. They are normally present in physiological conditions, but their concentration varies in pathological states such as cardiovascular disease, diabetes mellitus, or cancer. Acute and chronic physical exercise are able to modify MPs amounts as well. Among various actions, exercise-responsive MPs affect angiogenesis, the process through which new blood vessels grow from pre-existing vessels. Usually, the neo vascular growth has functional role; but an aberrant neovascularization accompanies several oncogenic, ischemic, or inflammatory diseases. In addition, angiogenesis is one of the key adaptations to physical exercise and training. In the present review, we report evidence regarding the effect of various typologies of exercise on circulating MPs that are able to affect angiogenesis.

Celastrol inhibits ezrin-mediated migration of hepatocellular carcinoma cells

Progression of hepatocellular carcinoma involves multiple genetic and epigenetic alterations that promote cancer invasion and metastasis. Our recent study revealed that hyperphosphorylation of ezrin promotes intrahepatic metastasis in vivo and cell migration in vitro. Celastrol is a natural product from traditional Chinese medicine which has been used in treating liver cancer. However, the mechanism of action underlying celastrol treatment was less clear. Here we show that ROCK2 is a novel target of celastrol and inhibition of ROCK2 suppresses elicited ezrin activation and liver cancer cell migration. Using cell monolayer wound healing, we carried out a phenotype-based screen of natural products and discovered the efficacy of celastrol in inhibiting cell migration. The molecular target of celastrol was identified as ROCK2 using celastrol affinity pull-down assay. Our molecular docking analyses indicated celastrol binds to the active site of ROCK2 kinase. Mechanistically, celastrol inhibits the ROCK2-mediated phosphorylation of ezrin at Thr567 which harnesses liver cancer cell migration. Our findings suggest that targeting ROCK2-ezrin signaling is a potential therapeutic niche for celastrol-based intervention of cancer progression in hepatocellular carcinoma.

Emerging Function and Clinical Significance of Exosomal circRNAs in Cancer

Exosomes are a type of extracellular vesicles (EVs) secreted by almost all cells, with a diameter range of 30-150 nm and a lipid bilayer membrane. Exosomes are now considered as vital mediators of intercellular communication and participate in multiple cellular processes, such as signal transduction and antigen presentation. Recently, circular RNAs (circRNAs), a novel class of noncoding RNAs (ncRNAs), have been found to be abundant and stable in exosomes. Increasing evidence indicates that exosome-derived circRNAs act as signaling molecules to regulate cancer growth, angiogenesis, invasion, metastasis, and sensitivity to chemotherapy. Moreover, circulating exosomal circRNAs can reflect the progression and malignant characteristics of cancer, implying their great potential as promising, non-invasive biomarkers for cancer diagnosis and prognosis. In this review, we summarize the recent progress on the functional roles of exosomal circRNAs in cancer progression, discussing their potential as promising biomarkers and therapeutic targets in cancer. Comprehensive elucidation of molecular mechanisms relevant to the implications of exosomal circRNAs in cancer progression will be conducive to the development of innovative diagnostic and therapeutic approaches in cancer.

Symmetry Breaking and Epithelial Cell Extrusion

Cell extrusion is a striking morphological event found in epithelia and endothelia. It is distinguished by two symmetry-breaking events: a loss of planar symmetry, as cells are extruded in either apical or basal directions; and loss of mechanochemical homogeneity within monolayers, as cells that are fated to be extruded become biochemically and mechanically distinct from their neighbors. Cell extrusion is elicited by many diverse events, from apoptosis to the expression of transforming oncogenes. Does the morphological outcome of extrusion reflect cellular processes that are common to these diverse biological phenomena? To address this question, in this review we compare the progress that has been made in understanding how extrusion is elicited by epithelial apoptosis and cell transformation.

Focal adhesion kinase is activated by microtubule-depolymerizing agents and regulates membrane blebbing in human endothelial cells

Microtubule‐depolymerizing agents can selectively disrupt tumor vessels via inducing endothelial membrane blebbing. However, the mechanism regulating blebbing is largely unknown. IMB5046 is a newly discovered microtubule‐depolymerizing agent. Here, the functions of focal adhesion kinase (FAK) during IMB5046‐induced blebbing and the relevant mechanism are studied. We found that IMB5046 induced membrane blebbing and reassembly of focal adhesions in human vascular endothelial cells. Both FAK inhibitor and knock‐down expression of FAK inhibited IMB5046‐induced blebbing. Mechanism study revealed that IMB5046 induced the activation of FAK via GEF‐H1/ Rho/ ROCK/ MLC2 pathway. cRGD peptide, a ligand of integrin, also blocked IMB5046‐induced blebbing. After activation, FAK further promoted the phosphorylation of MLC2. This positive feedback loop caused more intensive actomyosin contraction and continuous membrane blebbing. FAK inhibitor blocked membrane blebbing via inhibiting actomyosin contraction, and stimulated stress fibre formation via promoting the phosphorylation of HSP27. Conclusively, these results demonstrate that FAK is a molecular switch controlling endothelial blebbing and stress fibre formation. Our study provides a new molecular mechanism for microtubule‐depolymerizing agents to be used as vascular disrupting agents.

An alternative pathway for cellular protection in BRAF inhibitor resistance in aggressive melanoma type skin cancer

Oncogenic alterations in the BRAF gene are identified in an estimate of 50% of melanomas and cause melanoma development. BRAF kinase inhibitors (BRAFi), including vemurafenib and dabrafenib, were discovered and used in the clinical treatment of BRAF-mutant metastatic melanoma. Though, BRAFi's therapeutic advantages are short term and short-lived associated with drug resistance. Although a few pathways of developed BRAFi resistance have also been established, in approximately 40% of melanomas, the cause for inherited resistance remains unclear. Recognizing a new process of developed BRAFi resistance might provide new possibilities to successfully treat BRAF mutant melanoma. In this study, we are exploring the compensatory alternative pathway followed by BRAFi/MEKi treated resistant cell for maintaining the long-term integrity and survival.

Proeryptotic Activity of 4-Hydroxynonenal: A New Potential Physiopathological Role for Lipid Peroxidation Products

Background: Eryptosis is a physiological, apoptosis-like death of injured erythrocytes crucial to prevent premature haemolysis and the pathological sequalae generated by cell-free haemoglobin. When dysregulated, the process is associated to several inflammatory-based pathologies. 4-Hydroxy-trans-2-nonenal (HNE) is an endogenous signalling molecule at physiological levels and, at higher concentrations, is involved in the pathogenesis of several inflammatory-based diseases. This work evaluated whether HNE could induce eryptosis in human erythrocytes. Methods: Measurements of phosphatidylserine, cell volume, intracellular oxidants, Ca⁺⁺, glutathione, ICAM-1, and ceramide were assessed by flow cytometry. Scanning electron microscopy evaluated morphological alterations of erythrocytes. Western blotting assessed caspases. PGE₂ was measured by ELISA. Adhesion of erythrocytes on endothelial cells was evaluated by gravity adherence assay. Results: HNE in the concentration range between 10–100 µM induces eryptosis, morphological alterations correlated to caspase-3 activation, and increased Ca⁺⁺ levels. The process is not mediated by redox-dependent mechanisms; rather, it strongly depends on PGE₂ and ceramide. Interestingly, HNE induces significant increase of erythrocytes adhesion to endothelial cells (ECs) that are in turn dysfunctionated as evident by overexpression of ICAM-1. Conclusions: Our results unveil a new physiopathological role for HNE, provide mechanistic details of the HNE-induced eryptosis, and suggest a novel mechanism through which HNE could exert pro-inflammatory effects.

Extracellular Vesicle- and Extracellular Vesicle Mimetics-Based Drug Delivery Systems: New Perspectives, Challenges, and Clinical Developments

Extracellular vesicles (EVs) are small membrane-based nanovesicles naturally released from cells. Extracellular vesicles mimetics (EVMs) are artificial vesicles engineered from cells or in combination with lipid materials, and they mimic certain characteristics of EVs. As such, EVs facilitate intracellular communication by carrying and delivering biological materials, such as proteins, lipids, and nucleic acids, and they have been found to find organ tropism in preclinical studies. Because of their native structure and characteristics, they are considered promising drug carriers for future clinical use. This review outlines the origin and composition of natural EVs and EVM engineering and internalization. It then details different loading approaches, with examples of the drug delivery of therapeutic molecules. In addition, the advantages and disadvantages of loading drugs into EVs or EVMs as a drug delivery system are discussed. Finally, the advantages of EVMs over EVs and the future clinical translation of EVM-based drug delivery platforms are outlined.

Recombinant human lactoferrin induces apoptosis, disruption of F-actin structure and cell cycle arrest with selective cytotoxicity on human triple negative breast cancer cells

Breast cancer is the most frequently diagnosed cancer among women worldwide. Here, recombinant human lactoferrin (rhLf) expressed in Pichia pastoris was tested for its potential cytotoxic activity on a panel of six human breast cancer cell lines. The rhLf cytotoxic effect was determined via a live-cell HTS imaging assay. Also, confocal microscopy and flow cytometry protocols were employed to investigate the rhLf mode of action. The rhLf revealed an effective CC₅₀ of 91.4 and 109.46 µg/ml on non-metastatic and metastatic MDA-MB-231 cells, with favorable selective cytotoxicity index values, 11.68 and 13.99, respectively. Moreover, rhLf displayed satisfactory SCI values on four additional cell lines, MDA-MB-468, HCC70, MCF-7 and T-47D (1.55-3.34). Also, rhLf provoked plasma membrane blebbing, chromatin condensation and cell shrinkage in MDA-MB-231 cells, being all three apoptosis-related morphological changes. Also, rhLf was able to shrink the microfilaments, forming a punctuated cytoplasmic pattern in both the MDA-MB-231 and Hs-27 cells, as visualized in confocal photomicrographs. Moreover, performing flow cytometric analysis, rhLf provoked significant phosphatidylserine externalization, cell cycle arrest in the S phase and apoptosis-induced DNA fragmentation in MDA-MB-231 cells. Hence, rhLf possesses selective cytotoxicity on breast cancer cells. Also, rhLf caused apoptosis-associated morphologic changes, disruption of F-actin cytoskeleton organization, phosphatidylserine externalization, DNA fragmentation, and arrest of the cell cycle progression on triple-negative breast cancer MDA-MB-231 cells. Overall results suggest that rhLf is using the apoptosis pathway as its mechanism to inflict cell death. Findings warranty further evaluation of rhLf as a potential anti-breast cancer drug option.

Optical control of MAP kinase kinase 6 (MKK6) reveals that it has divergent roles in pro-apoptotic and anti-proliferative signaling

The selective pressure imposed by extrinsic death signals and stressors adds to the challenge of isolating and interpreting the roles of proteins in stress-activated signaling networks. By expressing a kinase with activating mutations and a caged lysine blocking the active site, we can rapidly switch on catalytic activity with light and monitor the ensuing dynamics. Applying this approach to MAP kinase 6 (MKK6), which activates the p38 subfamily of MAPKs, we found that decaging active MKK6 in fibroblasts is sufficient to trigger apoptosis in a p38-dependent manner. Both in fibroblasts and in a murine melanoma cell line expressing mutant B-Raf, MKK6 activation rapidly and potently inhibited the pro-proliferative extracellular signal-regulated kinase (ERK) pathway; to our surprise, this negative cross-regulation was equally robust when all p38 isoforms were inhibited. These results position MKK6 as a new pleiotropic signal transducer that promotes both pro-apoptotic and anti-proliferative signaling, and they highlight the utility of caged, light-activated kinases for dissecting stress-activated signaling networks.

Cucurbitacin IIb, a steroidal triterpene from Ibervillea sonorae induces antiproliferative and apoptotic effects on cervical and lung cancer cells

Chemical studies on Ibervillea sonorae (S. Watson) Greene root led to isolation and chemical characterization of diverse cucurbitacin triterpenoid compounds such as kinoin A, B, C, and their glucosides. In previous studies, we demonstrated that kinoin A inhibits the cell proliferation on diverse cell line and induce apoptosis in HeLa cells. Therefore, the study of the isolated compounds from the extracts continued to be necessary. The objective of the present work was to isolate and chemically characterize the active compounds of the methanolic extract of the roots of I. sonorae and to evaluate their antiproliferative activity and induction of apoptosis. By chromatographic column separation and using NMR spectroscopy experiments, cucurbitacin IIb (CIIb), known as 23,24-dihydrocucurbitacin F or hemslecin B, was isolated and identified for the first time as a chemical constituent of the crude methanolic extract of this plant. The antiproliferative activity of CIIb was evaluated by MTT assay, and the apoptosis induction capacity was monitored by annexin V-FITC/propidium iodide using flow cytometry. CIIb showed a pronounced effect on the proliferation of HeLa and A549 tumor cells, with IC₅₀ of 7.3 and 7.8 µM, respectively, but was less effective against L929 non-cancerous murine cell line. Apoptosis induction capacity of CIIb on HeLa and A549 was monitored by annexin V-FITC/propidium iodide using flow cytometry. Exposure of HeLa and A549 with CIIb (8 µM) for 24 h increased 56.9 and 52.3% respectively of the total apoptosis compared to the negative control (p < 0.005). CIIb, isolated for the first time from I. sonorae, showed antiproliferative activity against HeLa and A549 cell lines by inducing cell death by apoptosis.

RhoA/Rho-kinases in asthma: from pathogenesis to therapeutic targets

Asthma is a chronic and heterogeneous disease characterised by airway inflammation and intermittent airway narrowing. The key obstacle in the prevention and treatment of asthma has been our incomplete understanding of its aetiology and biological mechanisms. The ras homolog family member A (RhoA) of the Rho family GTPases has been considered to be one of the most promising and novel therapeutic targets for asthma. It is well known that RhoA/Rho‐kinases play an important role in the pathophysiology of asthma, including airway smooth muscle contraction, airway hyper‐responsiveness, β‐adrenergic desensitisation and airway remodelling. However, recent advances have suggested novel roles for RhoA in regulating allergic airway inflammation. Specifically, RhoA has been shown to regulate allergic airway inflammation through controlling Th2 or Th17 cell differentiation and to regulate airway remodelling through regulating mesenchymal stem cell (MSC) differentiation. In this review, we evaluate the literature regarding the recent advances in the activation of RhoA/Rho‐kinase, cytokine and epigenetic regulation of RhoA/Rho‐kinase, and the role of RhoA/Rho‐kinase in regulating major features of asthma, such as airway hyper‐responsiveness, remodelling and inflammation. We also discuss the importance of the newly identified role of RhoA/Rho‐kinase signalling in MSC differentiation and bronchial epithelial barrier dysfunction. These findings indicate the functional significance of the RhoA/Rho‐kinase pathway in the pathophysiology of asthma and suggest that RhoA/Rho‐kinase signalling may be a promising therapeutic target for the treatment of asthma.

Co-Loaded Curcumin and Methotrexate Nanocapsules Enhance Cytotoxicity against Non-Small-Cell Lung Cancer Cells

Background: As part of the efforts to find natural alternatives for cancer treatment and to overcome the barriers of cellular resistance to chemotherapeutic agents, polymeric nanocapsules containing curcumin and/or methotrexate were prepared by an interfacial deposition of preformed polymer method. Methods: Physicochemical properties, drug release experiments and in vitro cytotoxicity of these nanocapsules were performed against the Calu-3 lung cancer cell line. Results: The colloidal suspensions of nanocapsules showed suitable size (287 to 325 nm), negative charge (-33 to -41 mV) and high encapsulation efficiency (82.4 to 99.4%). Spherical particles at nanoscale dimensions were observed by scanning electron microscopy. X-ray diffraction analysis indicated that nanocapsules exhibited a non-crystalline pattern with a remarkable decrease of crystalline peaks of the raw materials. Fourier-transform infrared spectra demonstrated no chemical bond between the drug(s) and polymers. Drug release experiments evidenced a controlled release pattern with no burst effect for nanocapsules containing curcumin and/or methotrexate. The nanoformulation containing curcumin and methotrexate (NCUR/MTX-2) statistically decreased the cell viability of Calu-3. The fluorescence and morphological analyses presented a predominance of early apoptosis and late apoptosis as the main death mechanisms for Calu-3. Conclusions: Curcumin and methotrexate co-loaded nanocapsules can be further used as a novel therapeutic strategy for treating non-small-cell lung cancer.

Nanomorphological and mechanical reconstruction of mesenchymal stem cells during early apoptosis detected by atomic force microscopy

Stem cell apoptosis exists widely in embryonic development, tissue regeneration, repair, aging and pathophysiology of disease. The molecular mechanism of stem cell apoptosis has been extensively investigated. However, alterations in biomechanics and nanomorphology have rarely been studied. Therefore, an apoptosis model was established for bone marrow mesenchymal stem cells (BMSCs) and the reconstruction of the mechanical properties and nanomorphology of the cells were investigated in detail. Atomic force microscopy (AFM), scanning electron microscopy (SEM), laser scanning confocal microscopy (LSCM), flow cytometry and Cell Counting Kit-8 analysis were applied to assess the cellular elasticity modulus, geometry, nanomorphology, cell surface ultrastructure, biological viability and early apoptotic signals (phosphatidylserine, PS). The results indicated that the cellular elastic modulus and volume significantly decreased, whereas the cell surface roughness obviously increased during the first 3 h of cytochalasin B (CB) treatment. Moreover, these alterations preceded the exposure of biological apoptotic signal PS. These findings suggested that cellular mechanical damage is connected with the apoptosis of BMSCs, and the alterations in mechanics and nanomorphology may be a sensitive index to detect alterations in cell viability during apoptosis. The results contribute to further understanding of apoptosis from the perspective of cell mechanics.

Investigating the Suitability of High Content Image Analysis as a Tool to Assess the Reversibility of Foamy Alveolar Macrophage Phenotypes In Vitro

Many potential inhaled medicines fail during development due to the induction of a highly vacuolated or “foamy” alveolar macrophage phenotype response in pre-clinical studies. There is limited understanding if this response to an inhaled stimulus is adverse or adaptive, and additionally if it is a transient or irreversible process. The aim of this study was to evaluate whether high content image analysis could distinguish between different drug-induced foamy macrophage phenotypes and to determine the extent of the reversibility of the foamy phenotypes by assessing morphological changes over time. Alveolar-like macrophages derived from the human monocyte cell line U937 were exposed for 24 h to compounds known to induce a foamy macrophage phenotype (amiodarone, staurosporine) and control compounds that are not known to cause a foamy macrophage phenotype in vitro (fluticasone and salbutamol). Following drug stimulation, the cells were rested in drug-free media for the subsequent 24 or 48 h. Cell morphometric parameters (cellular and nuclear area, vacuoles numbers and size) and phospholipid content were determined using high content image analysis. The foamy macrophage recovery was dependent on the mechanism of action of the inducer compound. Amiodarone toxicity was associated with phospholipid accumulation and morphometric changes were reversed when the stimulus was removed from culture environment. Conversely cells were unable to recover from exposure to staurosporine which initiates the apoptosis pathway. This study shows that high content analysis can discriminate between different phenotypes of foamy macrophages and may contribute to better decision making in the process of new drug development.

Extracellular Vesicles Could Carry an Evolutionary Footprint in Interkingdom Communication

Extracellular vesicles (EVs) are minute particles secreted by the cells of living organisms. Although the functional role of EVs is not yet clear, recent work has highlighted their role in intercellular communication. Here, we expand on this view by suggesting that EVs can also mediate communication among interacting organisms such as hosts, pathogens and vectors. This inter-kingdom communication via EVs is likely to have important evolutionary consequences ranging from adaptation of parasites to specialized niches in the host, to host resistance and evolution and maintenance of parasite virulence and transmissibility. A potential system to explore these consequences is the interaction among the human host, the mosquito vector and Plasmodium parasite involved in the malaria disease. Indeed, recent studies have found that EVs derived from Plasmodium infected red blood cells in humans are likely mediating the parasite's transition from the asexual to sexual stage, which might facilitate transmission to the mosquito vector. However, more work is needed to establish the adaptive consequences of this EV signaling among different taxa. We suggest that an integrative molecular approach, including a comparative phylogenetic analysis of the molecules (e.g., proteins and nucleic acids) derived from the EVs of interacting organisms (and their closely-related species) in the malaria system will prove useful for understanding interkingdom communication. Such analyses will also shed light on the evolution and persistence of host, parasite and vector interactions, with implications for the control of vector borne infectious diseases.

Inside(sight) of tiny communicator: exosome biogenesis, secretion, and uptake

Discovered in the late 1980s as an extracellular vesicle of endosomal origin secreted from reticulocytes, exosomes recently gained scientific attention due to its role in intercellular communication. Exosomes have now been identified to carry cell-specific cargo of nucleic acids, proteins, lipids, and other biologically active molecules. Exosomes can be selectively taken up by neighboring or distant cells, which has shown to result in structural and functional responses in the recipient cells. Recent advances indicate the regulation of exosomes at various steps, including their biogenesis, selection of their cargo, as well as cell-specific uptake. This review will shed light on the differences between the type of extracellular vesicles. In this review, we discuss the recent progress in our understanding of the regulation of exosome biogenesis, secretion, and uptake.

Reactive oxygen species in cardiovascular health and disease: special references to nitric oxide, hydrogen peroxide, and Rho-kinase

The interaction between endothelial cells and vascular smooth muscle cells (VSMC) plays an important role in regulating cardiovascular homeostasis. Endothelial cells synthesize and release endothelium-derived relaxing factors (EDRFs), including vasodilator prostaglandins, nitric oxide (NO), and endothelium-dependent hyperpolarization (EDH) factors. Importantly, the contribution of EDRFs to endothelium-dependent vasodilatation markedly varies in a vessel size-dependent manner; NO mainly mediates vasodilatation of relatively large vessels, while EDH factors in small resistance vessels. We have previously identified that endothelium-derived hydrogen peroxide (H₂O₂) is an EDH factor especially in microcirculation. Several lines of evidence indicate the importance of the physiological balance between NO and H₂O₂/EDH factor. Rho-kinase was identified as the effectors of the small GTP-binding protein, RhoA. Both endothelial NO production and NO-mediated signaling in VSMC are targets and effectors of the RhoA/Rho-kinase pathway. In endothelial cells, the RhoA/Rho-kinase pathway negatively regulates NO production. On the contrary, the pathway enhances VSMC contraction with resultant occurrence of coronary artery spasm and promotes the development of oxidative stress and vascular remodeling. In this review, I will briefly summarize the current knowledge on the regulatory roles of endothelium-derived relaxing factors, with special references to NO and H₂O₂/EDH factor, in relation to Rho-kinase, in cardiovascular health and disease.

Coordinated changes in cell membrane and cytoplasm during maturation of apoptotic bleb

Apoptotic cells form membrane blebs, but little is known about how the formation and dynamics of membrane blebs are regulated. The size of blebs gradually increases during the progression of apoptosis, eventually forming large extracellular vesicles called apoptotic bodies that have immune-modulating activities. In this study, we investigated the molecular mechanism involved in the differentiation of blebs into apoptotic blebs by comparing the dynamics of the bleb formed during cell migration and the bleb formed during apoptosis. We revealed that the enhanced activity of ROCK1 is required for the formation of small blebs in the early phase of apoptosis, which leads to the physical disruption of nuclear membrane and the degradation of Lamin A. In the late phase of apoptosis, the loss of asymmetry in phospholipids distribution caused the enlargement of blebs, which enabled translocation of damage-associated molecular patterns to the bleb cytoplasm and maturation of functional apoptotic blebs. Thus, changes in cell membrane dynamics are closely linked to cytoplasmic changes during apoptotic bleb formation.

Essential role of the Crk family-dosage in DiGeorge-like anomaly and metabolic homeostasis

CRK and CRKL (CRK-like) encode adapter proteins with similar biochemical properties. Here, we show that a 50% reduction of the family-combined dosage generates developmental defects, including aspects of DiGeorge/del22q11 syndrome in mice. Like the mouse homologs of two 22q11.21 genes CRKL and TBX1, Crk and Tbx1 also genetically interact, thus suggesting that pathways shared by the three genes participate in organogenesis affected in the syndrome. We also show that Crk and Crkl are required during mesoderm development, and Crk/Crkl deficiency results in small cell size and abnormal mesenchyme behavior in primary embryonic fibroblasts. Our systems-wide analyses reveal impaired glycolysis, associated with low Hif1a protein levels as well as reduced histone H3K27 acetylation in several key glycolysis genes. Furthermore, Crk/Crkl deficiency sensitizes MEFs to 2-deoxy-D-glucose, a competitive inhibitor of glycolysis, to induce cell blebbing. Activated Rapgef1, a Crk/Crkl-downstream effector, rescues several aspects of the cell phenotype, including proliferation, cell size, focal adhesions, and phosphorylation of p70 S6k1 and ribosomal protein S6. Our investigations demonstrate that Crk/Crkl-shared pathways orchestrate metabolic homeostasis and cell behavior through widespread epigenetic controls.

The Quantitative-Phase Dynamics of Apoptosis and Lytic Cell Death

Cell viability and cytotoxicity assays are highly important for drug screening and cytotoxicity tests of antineoplastic or other therapeutic drugs. Even though biochemical-based tests are very helpful to obtain preliminary preview, their results should be confirmed by methods based on direct cell death assessment. In this study, time-dependent changes in quantitative phase-based parameters during cell death were determined and methodology useable for rapid and label-free assessment of direct cell death was introduced. The goal of our study was distinction between apoptosis and primary lytic cell death based on morphologic features. We have distinguished the lytic and non-lytic type of cell death according to their end-point features (Dance of Death typical for apoptosis versus swelling and membrane rupture typical for all kinds of necrosis common for necroptosis, pyroptosis, ferroptosis and accidental cell death). Our method utilizes Quantitative Phase Imaging (QPI) which enables the time-lapse observation of subtle changes in cell mass distribution. According to our results, morphological and dynamical features extracted from QPI micrographs are suitable for cell death detection (76% accuracy in comparison with manual annotation). Furthermore, based on QPI data alone and machine learning, we were able to classify typical dynamical changes of cell morphology during both caspase 3,7-dependent and -independent cell death subroutines. The main parameters used for label-free detection of these cell death modalities were cell density (pg/pixel) and average intensity change of cell pixels further designated as Cell Dynamic Score (CDS). To the best of our knowledge, this is the first study introducing CDS and cell density as a parameter typical for individual cell death subroutines with prediction accuracy 75.4% for caspase 3,7-dependent and -independent cell death.

NMMHC IIA Inhibition Ameliorates Cerebral Ischemic/Reperfusion-Induced Neuronal Apoptosis Through Caspase-3/ROCK1/MLC Pathway

Purpose

Our previous studies have indicated that non-muscle myosin heavy chain IIA (NMMHC IIA) is involved in H₂O₂-induced neuronal apoptosis, which is associated with the positive feedback loop of caspase-3/ROCK1/MLC pathway. However, the neuroprotective effect of NMMHC IIA inhibition with an adeno-associated virus (AAV) vector after transient middle cerebral artery occlusion (MCAO) and its role in caspases-3/ROCK1/MLC pathway remain blurred.

Methods

Green fluorescent protein (GFP) and a small hairpin RNA targeting Myh9 (encoding NMMHC IIA) were cloned and packaged into the AAV9 vector. AAV-shMyh9 or control vector were injected into C57BL/6J mice four weeks prior to 60 min MCAO. Twenty-four hours after reperfusion, functional and histological analyses of the mice were performed.

Results

In this study, AAV-shMyh9 was used to down-regulate NMMHC IIA expression in mice. We found that down-regulation of NMMHC IIA could improve neurological scores and histological injury in ischemic mice. Ischemic attack also activated neuronal apoptosis, and this effect was partially attenuated when NMMHC IIA was inhibited by AAV-shMyh9. In addition, AAV-shMyh9 significantly reduced cerebral ischemic/reperfusion (I/R)-induced NMMHC IIA-actin interaction, caspase-3 cleavage, Rho-associated kinase1 (ROCK1) activation and myosin light-chains (MLC) phosphorylation.

Conclusion

Consequently, we showed that AAV-shMyh9 inhibits I/R-induced neuronal apoptosis linked with caspase-3/ROCK1/MLC/NMMHC IIA-actin cascade, which has also been confirmed to be a positive feedback loop. These findings put some insights into the neuroprotective effect of AAV-shMyh9 associated with the regulation of NMMHC IIA-related pathway under ischemic attack and provide a therapeutic strategy for ischemic stroke.

Regulation of efferocytosis by caspase-dependent apoptotic cell death in atherosclerosis

During the growing process of the atherosclerotic lesions, lipid-filled macrophage foam cells form, accumulate, and ultimately undergo apoptotic death. If the apoptotic foam cells are not timely removed, they may undergo secondary necrosis, and form a necrotic lipid core which renders the plaque unstable and susceptible to rupture. Therefore, the non-lipid-filled fellow macrophages, as the main phagocytic cells in atherosclerotic lesions, need to effectively remove the apoptotic foam cells. In general, in apoptotic macrophages, caspases are the central regulators of several key processes required for their efficient efferocytosis. The processes include the generation of "Find-Me" signals (such as adenosine triphosphate/uridine triphosphate, fractalkine, lysophosphatidylcholine, and sphingosine-1-phosphate) for the recruitment of viable macrophages, generation of the "Eat-Me" signals (for example, phosphatidylserine) for the engulfment process, and, finally, release of anti-inflammatory mediators (including transforming factor β and interleukin-10) as a tolerance-enhancing and an anti-inflammatory response, and for the motile behavior of the apoptotic cell. The caspase-dependent mechanisms are operative also in apoptotic macrophages driving the atherogenesis. In this review, we explore the role of the molecular pathways related to the caspase-dependent events in efferocytosis in the context of atherosclerosis. Understanding of the molecular mechanisms of apoptotic cell death in atherosclerotic lesions is essential when searching for new leads to treat atherosclerosis.

Extracellular Vesicles: Recent Developments in Technology and Perspectives for Cancer Liquid Biopsy

Extracellular micro- and nanoscale membrane vesicles produced by different cells progressively attract the attention of the scientific community. They function as mediators of intercellular communication and transport genetic material and signaling molecules between the cells. In the context of keeping homeostasis, the extracellular vesicles contribute to the regulation of various systemic and local processes. Vesicles released by the tumor and activated stromal cells exhibit multiple functions including support of tumor growth, preparation of the pre-metastatic niches, and immune suppression. Considerable progress has been made regarding the criteria of classification of the vesicles according to their origin, content, and function: Exosomes, microvesicles, also referred to as microparticles or ectosomes, and large oncosomes were defined as actively released vesicles. Additionally, apoptotic bodies represented by a highly heterogeneous population of particles produced during apoptosis, the programmed cell death, should be considered. Because the majority of isolation techniques do not allow the separation of different types of vesicles, a joined term "extracellular vesicles" (EVs) was recommended by the ISEV community for the definition of vesicles isolated from either the cell culture supernatants or the body fluids. Because EV content reflects the content of the cell of origin, multiple studies on EVs from body fluids in the context of cancer diagnosis, prediction, and prognosis were performed, actively supporting their high potential as a biomarker source. Here, we review the leading achievements in EV analysis from body fluids, defined as EV-based liquid biopsy, and provide an overview of the main EV constituents: EV surface proteins, intravesicular soluble proteins, EV RNA including mRNA and miRNA, and EV DNA as potential biomarkers. Furthermore, we discuss recent developments in technology for quantitative EV analysis in the clinical setting and future perspectives toward miniaturized high-precision liquid biopsy approaches.

Caspase-3 Promotes Diabetic Kidney Disease Through Gasdermin E-Mediated Progression to Secondary Necrosis During Apoptosis

BACKGROUND

Apoptosis has been repeatedly linked with diabetic kidney disease (DKD), which is a programmed cell death mediated by effector caspases-3, 6 and 7, targeting >600 substrates. However, the pathophysiologic correlations of this process remain obscure. As a putative tumor suppressor, gasdermin E (GSDME) was recently reported to be cleaved by caspase-3 to produce a GSDME-N fragment which targets the plasma membrane to switch apoptosis to secondary necrosis. However, it remains elusive whether GSDME is involved in the regulation of DKD.

METHODS

To evaluate the therapeutic potential of caspase-3 inhibition in DKD, we administered caspase-3 inhibitor Z-DEVD-FMK to STZ-induced diabetic mice for eight weeks. Albuminuria, renal function, pathological changes, and indicators of secondary necrosis and fibrosis were evaluated. In vitro, human tubule epithelial cells (HK-2 cells) were subjected to high-glucose treatment. Secondary necrosis was determined by LDH release, GSDME cleavage, and morphological feature under confocal microscopy. Z-DEVD-FMK and GSDME inhibition by shRNA were administered to suppress the cleavage and expression of GSDME. Flow cytometry, cytotoxicity assay and immunoblot were used to assess cell death and fibrogenesis.

RESULTS

Caspase-3 inhibition by Z-DEVD-FMK ameliorated albuminuria, renal function, and tubulointerstitial fibrosis in diabetic mice. The nephroprotection mediated by Z-DEVD-FMK was potentially associated with inhibition of GSDME. In vitro, molecular and morphological features of secondary necrosis were observed in glucose-stressed HK-2 cells, evidenced by active GSDME cleavage, ballooning of the cell membrane, and release of cellular contents. Here we showed that caspase-3 inhibition prevented GSDME activation and cell death in glucose-treated tubular cells. Specifically, knocking down GSDME directly inhibited secondary necrosis and fibrogenesis.

CONCLUSION

These data suggest GSDME-dependent secondary necrosis plays a crucial role in renal injury, and provides a new insight into the pathogenesis of DKD and a promising target for its treatment.

The Contrasting Role of Extracellular Vesicles in Vascular Inflammation and Tissue Repair

Extracellular vesicles are a heterogeneous family of vesicles, generated from different subcellular compartments and released into the extracellular space. Composed of a lipid bilayer encompassing both soluble cytosolic material and nuclear components, these organelles have been recently described as novel regulators of intercellular communication between adjacent and remote cells. Due to their diversified composition and biological content, they portray specific signatures of cellular activation and pathological processes, their potential as diagnostic and prognostic biomarkers has raised significant interest in cardiovascular diseases. Circulating vesicles, especially those released from platelets, leukocytes, and endothelial cells are found to play a critical role in activating several fundamental cells within the vasculature, including endothelial cells and vascular smooth muscle cells. Their intrinsic activity and immunomodulatory properties lends them to not only promote vascular inflammation, but also enhance tissue regeneration, vascular repair, and indeed resolution. In this review we aim to recapitulate the recent findings concerning the roles played by EVs that originate from different circulating cells, with particular reference to their action on the endothelium. We focus herein, on the interaction of platelet and leukocyte EVs with the endothelium. In addition, their potential biological function in promoting tissue resolution and vascular repair will also be discussed.

Rho-kinase pathway activation and apoptosis in circulating leucocytes in patients with heart failure with reduced ejection fraction

Background

Increased Rho‐kinase activity in circulating leucocytes is observed in heart failure with reduced ejection fraction (HFrEF). However, there is little information in HFrEF regarding other Rho‐kinase pathway components an on the relationship between Rho‐kinase and apoptosis. Here, Rho‐kinase activation levels and phosphorylation of major downstream molecules and apoptosis levels were measured for the first time both in HFrEF patients and healthy individuals.

Methods

Cross‐sectional study comparing HFrEF patients (n = 20) and healthy controls (n = 19). Rho‐kinase activity in circulating leucocytes (peripheral blood mononuclear cells, PBMCs) was determined by myosin light chain phosphatase 1 (MYPT1) and ezrin‐radixin‐moesin (ERM) phosphorylation. Rho‐kinase cascade proteins phosphorylation p38‐MAPK, myosin light chain‐2, JAK and JNK were also analysed along with apoptosis.

Results

MYPT1 and ERM phosphorylation were significantly elevated in HFrEF patients, (3.9‐ and 4.8‐fold higher than in controls, respectively). JAK phosphorylation was significantly increased by 300% over controls. Phosphorylation of downstream molecules p38‐MAPK and myosin light chain‐2 was significantly higher by 360% and 490%, respectively, while JNK phosphorylation was reduced by 60%. Catecholamine and angiotensin II levels were significantly higher in HFrEF patients, while angiotensin‐(1‐9) levels were lower. Apoptosis in circulating leucocytes was significantly increased in HFrEF patients by 2.8‐fold compared with controls and significantly correlated with Rho‐kinase activation.

Conclusion

Rho‐kinase pathway is activated in PMBCs from HFrEF patients despite optimal treatment, and it is closely associated with neurohormonal activation and with apoptosis. ROCK cascade inhibition might induce clinical benefits in HFrEF patients, and its assessment in PMBCs could be useful to evaluate reverse remodelling and disease regression.

p75NTR and DR6 Regulate Distinct Phases of Axon Degeneration Demarcated by Spheroid Rupture

The regressive events associated with trophic deprivation are critical for sculpting a functional nervous system. After nerve growth factor withdrawal, sympathetic axons derived from male and female neonatal mice maintain their structural integrity for ∼18 h (latent phase) followed by a rapid and near unison disassembly of axons over the next 3 h (catastrophic phase). Here we examine the molecular basis by which axons transition from latent to catastrophic phases of degeneration following trophic withdrawal. Before catastrophic degeneration, we observed an increase in intra-axonal calcium. This calcium flux is accompanied by p75 neurotrophic factor receptor-Rho-actin-dependent expansion of calcium-rich axonal spheroids that eventually rupture, releasing their contents to the extracellular space. Conditioned media derived from degenerating axons are capable of hastening transition into the catastrophic phase of degeneration. We also found that death receptor 6, but not p75 neurotrophic factor receptor, is required for transition into the catastrophic phase in response to conditioned media but not for the intra-axonal calcium flux, spheroid formation, or rupture that occur toward the end of latency. Our results support the existence of an interaxonal degenerative signal that promotes catastrophic degeneration among trophically deprived axons.SIGNIFICANCE STATEMENT Developmental pruning shares several morphological similarities to both disease- and injury-induced degeneration, including spheroid formation. The function and underlying mechanisms governing axonal spheroid formation, however, remain unclear. In this study, we report that axons coordinate each other's degeneration during development via axonal spheroid rupture. Before irreversible breakdown of the axon in response to trophic withdrawal, p75 neurotrophic factor receptor-RhoA signaling governs the formation and growth of spheroids. These spheroids then rupture, allowing exchange of contents ≤10 kDa between the intracellular and extracellular space to drive death receptor 6 and calpain-dependent catastrophic degeneration. This finding informs not only our understanding of regressive events during development but may also provide a rationale for designing new treatments toward myriad neurodegenerative disorders.

Actinomycin D-Activated RNase L Promotes H2A.X/H2B-Mediated DNA Damage and Apoptosis in Lung Cancer Cells

Background: Chemotherapy is an essential component for comprehensive cancer treatment, while drug resistance usually fails therapy. DNA repair mechanism of cancer cells restrains the efficacy of therapeutics targeting DNA damage. Investigating target-inducing irreversible cell death of cancer cells may be promising. Methods: The present study used lung cancer cell lines, transplanted tumor model of lung cancers derived from patients with lung adenocarcinoma, and molecular experiments to investigate the effects and mechanism of Actinomycin D (Act D)-activated RNase L in lung canceers. Results: We report that RNase L, when activated by Act D, induces Caspase-3/PARP activation. The latter further enables ROCK-1 to initiate subsequent membrane blebbing and, meanwhile, result in DNA cleavage and cell cycle arrest mediated by H2A.X/H2B-p21 axis, leading to irreversible DNA damage, and apoptosis of lung cancer cells. The present study highlighted the crucial role of RNase L in triggering apoptosis mechanism through the Caspase-3/ROCK-1/PARP/H2A.X+H2B/p21 axis during Act D treatment. Moreover, activation of RNase L suppressed the tumor formation and the induction of lung cancer stem cells. Conclusion: This study unveiled the regulatory function and related mechanism of RNase L and implied the promising application of therapeutics targeting RNase L in lung cancer.

Circulating biomarkers of cell death

Numerous disease states are associated with cell death. For many decades, apoptosis and accidental necrosis have been assumed to be the two ways how a cell can die. The recent discovery of additional cell death processes such as necroptosis, ferroptosis or pyroptosis revealed a complex interplay between cell death mechanisms and diseases. Depending on the particular cell death pathway, cells secrete distinct molecular patterns, which differ between cell death types. This review focusses on released molecules, detectable in the blood flow, and their potential role as circulating biomarkers of cell death. We elucidate the molecular background of different biomarkers and give an overview on their correlation with disease stage, therapy response and prognosis in patients.

Characterization of Tissue Transglutaminase as a Potential Biomarker for Tissue Response toward Biomaterials

Tissue transglutaminase (TGase 2) is proposed to be important for biomaterial-tissue interactions due to its presence and versatile functions in the extracellular environment. TGase 2 catalyzes the cross-linking of proteins through its Ca²⁺-dependent acyltransferase activity. Moreover, it enhances the interactions between fibronectin and integrins, which in turn mediates the adhesion, migration, and motility of the cells. TGase 2 is also a key player in the pathogenesis of fibrosis. In this study, we investigated whether TGase 2 is present at the biomaterial-tissue interface and might serve as an informative biomarker for the visualization of tissue response toward gelatin-based biomaterials. Two differently cross-linked hydrogels were used, which were obtained by the reaction of gelatin with lysine diisocyanate ethyl ester. The overall expression of TGase 2 by endothelial cells, macrophages, and granulocytes was partly influenced by contact to the hydrogels or their degradation products, although no clear correlation was evidenced. In contrast, the secretion of TGase 2 differed remarkably between the different cells, indicating that it might be involved in the cellular reaction toward gelatin-based hydrogels. The hydrogels were implanted subcutaneously in immunocompetent, hairless SKH1-Elite mice. Ex vivo immunohistochemical analysis of tissue sections over 112 days revealed enhanced expression of TGase 2 around the hydrogels, in particular at days 14 and 21 post-implantation. The incorporation of fluorescently labeled cadaverine derivatives for the detection of active TGase 2 was in accordance with the results of the expression analysis. The presence of an irreversible inhibitor of TGase 2 led to attenuated incorporation of the cadaverines, which verified the catalytic action of TGase 2. Our in vitro and ex vivo results verified TGase 2 as a potential biomarker for tissue response toward gelatin-based hydrogels. In vivo, no TGase 2 activity was detectable, which is mainly attributed to the unfavorable physicochemical properties of the cadaverine probe used.

ROCK inhibitor increases proacinar cells in adult salivary gland organoids

Salisphere-derived adult epithelial cells have been used to improve saliva production of irradiated mouse salivary glands. Importantly, optimization of the cellular composition of salispheres could improve their regenerative capabilities. The Rho Kinase (ROCK) inhibitor, Y27632, has been used to increase the proliferation and reduce apoptosis of progenitor cells grown in vitro. In this study, we investigated whether Y27632 could be used to improve expansion of adult submandibular salivary epithelial progenitor cells or to affect their differentiation potential in different media contexts. Application of Y27632 in medium used previously to grow salispheres promoted expansion of Kit⁺ and Mist1⁺ cells, while in simple serum-containing medium Y27632 increased the number of cells that expressed the K5 basal progenitor marker. Salispheres derived from Mist1^CreERT2; R26^TdTomato mice grown in salisphere media with Y27632 included Mist1-derived cells. When these salispheres were incorporated into 3D organoids, inclusion of Y27632 in the salisphere stage increased the contribution of Mist1-derived cells expressing the proacinar/acinar marker, Aquaporin 5 (AQP5), in response to FGF2-dependent mesenchymal signals. Optimization of the cellular composition of salispheres and organoids can be used to improve the application of adult salivary progenitor cells in regenerative medicine strategies.

The role of microvesicles containing microRNAs in vascular endothelial dysfunction

Many studies have shown that endothelial dysfunction is associated with a variety of cardiovascular diseases. The endothelium is one of the primary targets of circulating microvesicles. Besides, microRNAs emerge as important regulators of endothelial cell function. As a delivery system of microRNAs, microvesicles play an active and important role in regulating vascular endothelial function. In recent years, some studies have shown that microvesicles containing microRNAs regulate the pathophysiological changes in vascular endothelium, such as cell apoptosis, proliferation, migration and inflammation. These studies have provided some clues for the possible roles of microvesicles and microRNAs in vascular endothelial dysfunction‐associated diseases, and opened the door towards discovering potential novel therapeutic targets. In this review, we provide an overview of the main characteristics of microvesicles and microRNAs, summarizing their potential role and mechanism in endothelial dysfunction, and discussing the clinical application and existing problems of microvesicles for better translational applications.

Functional Validation of DownRegulated MicroRNAs in HeLa Cells Treated with Polyalthia longifolia Leaf Extract Using Different Microscopic Approaches: A Morphological Alteration-Based Validation

Several microscopy methods have been developed to assess the morphological changes in cells in the investigations of the mode of cell death in response to a stimulus. Our recent finding on the treatment of the IC50 concentration (26.67 μg/mL) of Polyalthia longifolia leaf extract indicated the induction of apoptotic cell death via the regulation of miRNA in HeLa cells. Hence, the current study was conducted to validate the function of these downregulated microRNAs in P. longifolia-treated HeLa cells using microscopic approaches. These include scanning electron microscope (SEM), transmission electron microscope (TEM), and acridine orange/propidium iodide (AO/PI)-based fluorescent microscopy techniques by observing the morphological alterations to cells after transfection with mimic miRNA. Interestingly, the morphological changes observed in this study demonstrated the apoptotic hallmarks, for instance, cell blebbing, cell shrinkage, cytoplasmic and nuclear condensation, vacuolization, cytoplasmic extrusion, and the formation of apoptotic bodies, which proved the role of dysregulated miRNAs in apoptotic HeLa cell death after treatment with the P. longifolia leaf extract. Conclusively, the current study proved the crucial role of downregulated miR-484 and miR-221-5p in the induction of apoptotic cell death in P. longifolia-treated HeLa cells using three approaches-SEM, TEM, and AO/PI-based fluorescent microscope.

Discovery of thalicthuberine as a novel antimitotic agent from nature that disrupts microtubule dynamics and induces apoptosis in prostate cancer cells

We report for the first time the mechanism of action of the natural product thalicthuberine (TH) in prostate and cervical cancer cells. TH induced a strong accumulation of LNCaP cells in mitosis, severe mitotic spindle defects, and asymmetric cell divisions, ultimately leading to mitotic catastrophe accompanied by cell death through apoptosis. However, unlike microtubule-binding drugs (vinblastine and paclitaxel), TH did not directly inhibit tubulin polymerization when tested in a cell-free system, whereas it reduced cellular microtubule polymer mass in LNCaP cells. This suggests that TH indirectly targets microtubule dynamics through inhibition of a critical regulator or tubulin-associated protein. Furthermore, TH is not a major substrate for P-glycoprotein (Pgp), which is responsible for multidrug resistance in numerous cancers, providing a rationale to further study TH in cancers with Pgp-mediated treatment resistance. The identification of TH's molecular target in future studies will be of great value to the development of TH as potential treatment of multidrug-resistant tumors.

Insights into Ergosterol Peroxide's Trypanocidal Activity

Trypanosoma cruzi, which causes Chagas disease, is a significant health threat in many countries and affects millions of people. Given the magnitude of this disease, a broader understanding of trypanocidal mechanisms is needed to prevent and treat infection. Natural endoperoxides, such as ergosterol peroxide, have been shown to be toxic to parasites without causing harm to human cells or tissues. Although prior studies have demonstrated the trypanocidal activity of ergosterol peroxide, the cellular and molecular mechanisms remain unknown. The results of this study indicate that a free-radical reaction occurs in T. cruzi following ergosterol peroxide exposure, leading to cell death. Using a combination of biochemical, microscopic and in silico experimental approaches, we have identified, for the first time, the cellular and molecular cytotoxic mechanism of an ergosterol peroxide obtained from Pleurotus ostreatus (Jacq) P. Kumm. f. sp. Florida.

DMPK is a New Candidate Mediator of Tumor Suppressor p53-Dependent Cell Death

Tumor suppressor p53 plays an integral role in DNA-damage induced apoptosis, a biological process that protects against tumor progression. Cell shape dramatically changes when cells undergo apoptosis, which is associated with actomyosin contraction; however, it remains entirely elusive how p53 regulates actomyosin contraction in response to DNA-damaging agents. To identify a novel p53 regulating gene encoding the modulator of myosin, we conducted DNA microarray analysis. We found that, in response to DNA-damaging agent doxorubicin, expression of myotonic dystrophy protein kinase (DMPK), which is known to upregulate actomyosin contraction, was increased in a p53-dependent manner. The promoter region of DMPK gene contained potential p53-binding sequences and its promoter activity was increased by overexpression of the p53 family protein p73, but, unexpectedly, not of p53. Furthermore, we found that doxorubicin treatment induced p73 expression, which was significantly attenuated by downregulation of p53. These data suggest that p53 induces expression of DMPK through upregulating p73 expression. Overexpression of DMPK promotes contraction of the actomyosin cortex, which leads to formation of membrane blebs, loss of cell adhesion, and concomitant caspase activation. Taken together, our results suggest the existence of p53-p73-DMPK axis which mediates DNA-damage induced actomyosin contraction at the cortex and concomitant cell death.