Molecular definitions of cell death subroutines: recommendations of the Nomenclature Committee on Cell Death 2012

Evaluation of lymphocyte apoptosis in patients with oral cancer

Objectives

To evaluate apoptotic levels of peripheral blood mononuclear cells (PBMCs) and apoptotic regulatory proteins (Bax and Bcl-2) in lymphocyte subsets of oral cancer (OC) patients and healthy controls (HC).

Methodology

The percentage of apoptotic cells and lymphocyte counts were measured in the first cohort using PBMCs obtained from 23 OC patients and 6 HC. In the second cohort, (OC, 33; HC, 13), the mean fluorescence intensity (MFI) of Bax and Bcl-2 in CD19⁺ B, CD4⁺ T, CD8⁺ T, and CD16⁺56⁺ natural killer (NK) cells was determined via flow cytometry.

Results

The percentage of apoptotic cells was higher in the PBMCs of OC patients than in HC patients, particularly in patients with stage IV cancer (p<0.05). However, lymphocyte counts were significantly lower in stage IV patients (p<0.05). NK CD19⁺ B and CD16⁺56⁺ cell counts were significantly lower in OC patients compared with HC patients (p<0.001 and p<0.01, respectively), but CD4⁺ T cells were interestingly significantly higher in OC patients (p<0.001). While Bax MFI was slightly higher, Bcl-2 MFI was significantly lower for all four lymphocyte subsets in OC samples, particularly in stage IV patients, when compared with HC. Consequently, Bax/Bcl-2 ratios showed an upward trend from HC to OC patients, particularly those in stage IV. We found similar trends in Bax and Bcl-2 MFI for tumor stage, tumor size, and lymph node involvement.

Conclusions

The increased lymphocyte apoptosis in stage IV OC patients may be related to higher Bax levels and lower Bcl-2 levels. The Bax/Bcl-2 ratio in lymphocytes may be useful to determine the prognosis of OC patients, and could be considered a mean for supportive treatment in the future.

Increased expression of hras induces early, but not full, senescence in the immortal fish cell line, EPC

In contrast to most mammals including human, fish cell lines have long been known to be immortal, with little sign of cellular senescence, despite the absence of transformation. Recently, our laboratory reported that DNA demethylation with 5-aza-2'-deoxycytidine (5-Aza-dC) induces telomere-independent cellular senescence and senescence-associated secretory phenotype (SASP) in an immortal fish cell line, EPC (Epithelioma papulosum cyprini). However, it is not known how fish derived cultured cells are usually resistant to aging in vitro. In this study, we focused on Ras, which carries out the main role of Ras-induced senescence (RIS), and investigated the role of Ras in the regulation of senescence in EPC cells. Our results show that 5-Aza-dC induced the expression of the ras (hras, kras, nras) gene in EPC cells. EPC cells overexpressing HRas or its constitutively active form (HRas^V12) showed p53-dependent senescence-like growth arrest and senescence-associated β-galactosidase (SA-β-gal) activity with a large and/or flat morphology characteristic of cell senescence. On the other hand, the SASP was not induced. These results imply that the increased expression of HRas contributes to early senescence in EPC cells, but it alone may not be sufficient for the full senescence, even if HRas is aberrantly activated. Thus, the limited mechanism of RIS may play a role in the senescence-resistance of fish cell lines.

CRISPR/Cas9-Mediated OC-2 Editing Inhibits the Tumor Growth and Angiogenesis of Ovarian Cancer

Ovarian cancer is the leading cancer-related cause of death in women worldwide. It is of great relevance to understand the mechanism responsible for tumor progression and identify unique oncogenesis markers for a higher chance of preventing this malignant disease. The high-expression OC-2 gene has been shown to be a potential candidate for regulating oncogenesis and angiogenesis in ovarian cancer. Hence, we wished to investigate the impact of OC-2 gene on ovarian cancer aggressiveness. CRISPR/Cas9, a gene editing tool, allows for direct ablation of OC-2 at the genomic level, and we successfully generated OC-2 KO cell lines from SKOV3 and CAOV3 cells. In an apoptosis assay, OC-2 KO induced the apoptosis activation of tumor cells, with the up-regulation of Bax/Caspase-8 and the down-regulation of Bcl-2. Consequently, the proliferation, migration, and invasion of OC-2 KO cell lines were significantly inhibited. Assays of qRT-PCR and Western blotting showed that the expression levels of pro-angiogenic growth factors VEGFA, FGF2, HGF, and HIF-1α and the activation of Akt/ERK pathways were significantly down-regulated at the loss of OC-2. In the xenograft model, OC-2 KO potently suppressed the subcutaneous tumor growth, with the inhibition exceeding 56%. The down-regulation of CD31 and relevant pro-angiogenic growth factors were observed in OC-2 KO tumor tissues. Taken together, OC-2 depletion negatively regulated the ovarian cancer progression possibly by apoptosis activation and angiogenesis inhibition. This work revealed a pivotal regulator of apoptosis and angiogenesis networks in ovarian cancer, and we applied the CRISPR/Cas9 system to the transcription factor pathway for developing a broad-acting anti-tumor gene therapy.

RIP1 promotes proliferation through G2/M checkpoint progression and mediates cisplatin-induced apoptosis and necroptosis in human ovarian cancer cells

Receptor-interacting protein 1 (RIP1, also known as RIPK1) is not only a tumor-promoting factor in several cancers but also mediates either apoptosis or necroptosis in certain circumstances. In this study we investigated what role RIP1 plays in human ovarian cancer cells. We showed that knockout (KO) of RIP1 substantially suppressed cell proliferation, accompanied by the G2/M checkpoint arrest in two human ovarian cancer cell lines SKOV3 and A2780. On the other hand, RIP1 KO remarkably attenuated cisplatin-induced cytotoxicity, which was associated with reduction of the apoptosis markers PARP cleavage and the necroptosis marker phospho-MLKL. We found that RIP1 KO suppressed cisplatin-induced ROS accumulation in both SKOV3 and A2780 cells. ROS scavenger BHA, apoptosis inhibitor Z-VAD or necroptosis inhibitor NSA could effectively suppress cisplatin’s cytotoxicity in the control cells, suggesting that ROS-mediated apoptosis and necroptosis were involved in cisplatin-induced cell death. In addition, blocking necroptosis with MLKL siRNA effectively attenuated cisplatin-induced cytotoxicity. In human ovarian cancer A2780 cell line xenograft nude mice, RIP1 KO not only significantly suppressed the tumor growth but also greatly attenuated cisplatin’s anticancer activity. Our results demonstrate a dual role of RIP1 in human ovarian cancer: it acts as either a tumor-promoting factor to promote cancer cell proliferation or a tumor-suppressing factor to facilitate anticancer effects of chemotherapeutics such as cisplatin.

Ru(II)-Based Amino Acid Complexes Show Promise for Leukemia Treatment: Cytotoxicity and Some Light on their Mechanism of Action

Ruthenium is attracting considerable interest as the basis for new compounds to treat diseases, and studies have shown that complexes with different structures have significant antineoplastic and antimetastatic potential against several types of tumors, including tumors resistant to cisplatin drugs. We examined the cytotoxic, genotoxic, and pro-apoptotic activities of six ruthenium complexes containing amino acid with general formulation [Ru(AA)(bipy)(dppb)]PF₆, where AA = amino acid (alanine, glycine, leucine, lysine, methionine, or tryptophan); bipy = 2,2´-bipyridine; and dppb = [1,4-bis(diphenylphosphine)butane], against A549 (lung carcinoma) and K562 (chronic myelogenous leukemia) cancer cells. The results show that the ruthenium complexes tested were able to induce cytotoxicity in A549 and K562 cancer cells. Complex 1 containing alanine inhibited the cell viability of A549 and K562 tumor cells by inducing apoptosis, as evidenced by an increased number of Annexin V-positive cells and the induction of DNA damage and cell cycle arrest. Complex 1 was able to induce caspase-mediated apoptosis in K562 cells through the mitochondrial dysfunction, the upregulation of apoptotic genes, and the downregulation of Bcl2 anti-apoptotic gene. Besides being cytotoxic to K562 and A549 cells, ruthenium complex containing alanine shows low cytotoxicity and genotoxicity against non-tumor cells. These results suggest that the ruthenium (II) complex is a potential safe and efficient antineoplastic candidate for leukemia treatment.

The effect of Ginsenoside Rg1 in hepatic ischemia reperfusion (I/R) injury ameliorates ischemia-reperfusion-induced liver injury by inhibiting apoptosis

Hepatic ischemia reperfusion (I/R) injury (HIRI) HIRI is a complex, multifactorial pathophysiological process and in liver surgery has been known to significantly affect disease prognosis, surgical success rates, and patient survival. Ginsenoside Rgl (Rgl) monomer is one of the main active ingredients of ginseng. Previous studies have demonstrated that Rgl exerts various pharmacological effects through several mechanisms including suppression of apoptosis-related proteins levels, downregulation of inflammatory mediators and as well as antioxidant, which effectively exerts an organ protective effect I/R-induced damage. However, the exact mechanisms of Rg1 on HIRI remain to be elucidated. In the present study, we investigated the protective effect of Rg1 on hepatic ischemia-reperfusion (I/R) injury (HIRI) and explored its underlying molecular mechanism. A rat warm I/R injury model in vivo and an oxygen-glucose deprivation/reperfusion (OGD/R)-treated BRL-3A cell model in vitro were established after pretreating with Rg1(20 mg/kg). The results showed that Rg1 reduced the levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST). TUNEL staining showed that pretreated with Rg1 inhibited the apoptosis rate compared with the I/R group. Moreover, pretreated with Rg1 significantly reduced the expression of Cyt-C, Caspase-9 and Caspase-3 to inhibit the cell apoptosis. Flow cytometry analysis showed the MMP in the I/R group was significantly increased, whereas pretreated with Rg1 effectively stabilized the MMP compared with the I/R group. in vitro, the proliferation of BRL-3A cells was significantly decreased by the OGD/R treatment, while Rg1 effectively reversed this phenomenon. In addition, western blotting showed that the increase of Cyt-C, Caspase-9 and Caspase-3 was inhibited by H2O2. These observations suggest that Rg1 exerts the protective effect by inhibiting the CypD protein-mediated mitochondrial apoptotic pathway.

The Latest View on the Mechanism of Ferroptosis and Its Research Progress in Spinal Cord Injury

Ferroptosis is a recently identified nonapoptotic form of cell death whose major markers are iron dependence and accumulation of lipid reactive oxygen species, accompanied by morphological changes such as shrunken mitochondria and increased membrane density. It appears to contribute to the death of tumors, ischemia-reperfusion, acute renal failure, and nervous system diseases, among others. The generative mechanism of ferroptosis includes iron overloading, lipid peroxidation, and downstream execution, while the regulatory mechanism involves the glutathione/glutathione peroxidase 4 pathway, as well as the mevalonate pathway and the transsulfuration pathway. In-depth research has continuously developed and enriched knowledge on the mechanism by which ferroptosis occurs. In recent years, reports of the noninterchangeable role played by selenium in glutathione peroxidase 4 and its function in suppressing ferroptosis and the discovery of ferroptosis suppressor protein 1, identified as a ferroptosis resistance factor parallel to the glutathione peroxidase 4 pathway, have expanded and deepened our understanding of the mechanism by which ferroptosis works. Ferroptosis has been reported in spinal cord injury animal model experiments, and the inhibition of ferroptosis could promote the recovery of neurological function. Here, we review the latest studies on mechanism by which ferroptosis occurs, focusing on the ferroptosis execution and the contents related to selenium and ferroptosis suppressor protein 1. In addition, we summarize the current research status of ferroptosis in spinal cord injury. The aim of this review is to better understand the mechanisms by which ferroptosis occurs and its role in the pathophysiological process of spinal cord injury, so as to provide a new idea and frame of reference for further exploration.

Autosis: A New Target to Prevent Cell Death

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Autosis is an autophagy-dependent, nonapoptotic, and non-necrotic form of cell death that is characterized by unique morphological and biochemical features, including the presence of ballooning of perinuclear space (PNS) and sensitivity to cardiac glycosides, respectively.

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Autotic cell death may be initiated by excessive accumulation of autophagosomes rather than lysosomal degradation.

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Autosis is stimulated during the late phase of reperfusion after a period of ischemia in the heart when up-regulation of rubicon in the presence of continuous autophagosome production induces massive accumulation of autophagosomes.

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Suppression of autosis, which may reduce death of cardiomyocytes during the late phase of reperfusion, in combination with inhibition of apoptosis and necrosis targeting the early phase of injury, may enhance the effectiveness of treatment for I/R injury in the heart.

Excessive autophagy induces a defined form of cell death called autosis, which is characterized by unique morphological features, including ballooning of perinuclear space and biochemical features, including sensitivity to cardiac glycosides. Autosis is observed during the late phase of reperfusion after a period of ischemia and contributes to myocardial injury. This review discusses unique features of autosis, the involvement of autosis in myocardial injury, and the molecular mechanism of autosis. Because autosis promotes myocardial injury under some conditions, a better understanding of autosis may lead to development of novel interventions to protect the heart against myocardial stress.

Anticancer Strategy Targeting Cell Death Regulators: Switching the Mechanism of Anticancer Floxuridine-Induced Cell Death from Necrosis to Apoptosis

Cell death can be broadly characterized as either necrosis or apoptosis, depending on the morphological and biochemical features of the cell itself. We have previously reported that the treatment of mouse mammary carcinoma FM3A cells with the anticancer drug floxuridine (FUdR) induces necrosis in the original clone F28-7 but apoptosis in the variant F28-7-A. We have identified regulators, including heat shock protein 90, lamin-B1, cytokeratin-19, and activating transcription factor 3, of cell death mechanisms by using comprehensive gene and protein expression analyses and a phenotype-screening approach. We also observed that the individual inhibition or knockdown of the identified regulators in F28-7 results in a shift from necrotic to apoptotic morphology. Furthermore, we investigated microRNA (miRNA, miR) expression profiles in sister cell strains F28-7 and F28-7-A using miRNA microarray analyses. We found that several unique miRNAs, miR-351-5p and miR-743a-3p, were expressed at higher levels in F28-7-A than in F28-7. Higher expression of these miRNAs in F28-7 induced by transfecting miR mimics resulted in a switch in the mode of cell death from necrosis to apoptosis. Our findings suggest that the identified cell death regulators may play key roles in the decision of cell death mechanism: necrosis or apoptosis.

Ferroptosis, necroptosis, and pyroptosis in anticancer immunity

In recent years, cancer immunotherapy based on immune checkpoint inhibitors (ICIs) has achieved considerable success in the clinic. However, ICIs are significantly limited by the fact that only one third of patients with most types of cancer respond to these agents. The induction of cell death mechanisms other than apoptosis has gradually emerged as a new cancer treatment strategy because most tumors harbor innate resistance to apoptosis. However, to date, the possibility of combining these two modalities has not been discussed systematically. Recently, a few studies revealed crosstalk between distinct cell death mechanisms and antitumor immunity. The induction of pyroptosis, ferroptosis, and necroptosis combined with ICIs showed synergistically enhanced antitumor activity, even in ICI-resistant tumors. Immunotherapy-activated CD8+ T cells are traditionally believed to induce tumor cell death via the following two main pathways: (i) perforin-granzyme and (ii) Fas-FasL. However, recent studies identified a new mechanism by which CD8+ T cells suppress tumor growth by inducing ferroptosis and pyroptosis, which provoked a review of the relationship between tumor cell death mechanisms and immune system activation. Hence, in this review, we summarize knowledge of the reciprocal interaction between antitumor immunity and distinct cell death mechanisms, particularly necroptosis, ferroptosis, and pyroptosis, which are the three potentially novel mechanisms of immunogenic cell death. Because most evidence is derived from studies using animal and cell models, we also reviewed related bioinformatics data available for human tissues in public databases, which partially confirmed the presence of interactions between tumor cell death and the activation of antitumor immunity.

Brain-Specific Serine-47 Modification of Cytochrome c Regulates Cytochrome c Oxidase Activity Attenuating ROS Production and Cell Death: Implications for Ischemia/Reperfusion Injury and Akt Signaling

We previously reported that serine-47 (S47) phosphorylation of cytochrome c (Cytc) in the brain results in lower cytochrome c oxidase (COX) activity and caspase-3 activity in vitro. We here analyze the effect of S47 modification in fibroblast cell lines stably expressing S47E phosphomimetic Cytc, unphosphorylated WT, or S47A Cytc. Our results show that S47E Cytc results in partial inhibition of mitochondrial respiration corresponding with lower mitochondrial membrane potentials (ΔΨm) and reduced reactive oxygen species (ROS) production. When exposed to an oxygen-glucose deprivation/reoxygenation (OGD/R) model simulating ischemia/reperfusion injury, the Cytc S47E phosphomimetic cell line showed minimal ROS generation compared to the unphosphorylated WT Cytc cell line that generated high levels of ROS upon reoxygenation. Consequently, the S47E Cytc cell line also resulted in significantly lower cell death upon exposure to OGD/R, confirming the cytoprotective role of S47 phosphorylation of Cytc. S47E Cytc also resulted in lower cell death upon H2O2 treatment. Finally, we propose that pro-survival kinase Akt (protein kinase B) is a likely mediator of the S47 phosphorylation of Cytc in the brain. Akt inhibitor wortmannin abolished S47 phosphorylation of Cytc, while the Akt activator SC79 maintained S47 phosphorylation of Cytc. Overall, our results suggest that loss of S47 phosphorylation of Cytc during brain ischemia drives reperfusion injury through maximal electron transport chain flux, ΔΨm hyperpolarization, and ROS-triggered cell death.

The tale of caspase homologues and their evolutionary outlook: deciphering programmed cell death in cyanobacteria

Programmed cell death (PCD), a genetically orchestrated mechanism of cellular demise, is paradoxically required to support life. As in lower eukaryotes and bacteria, PCD in cyanobacteria is poorly appreciated, despite recent biochemical and molecular evidence that supports its existence. Cyanobacterial PCD is an altruistic reaction to stressful conditions that significantly enhances genetic diversity and inclusive fitness of the population. Recent bioinformatic analysis has revealed an abundance of death-related proteases, i.e. orthocaspases (OCAs) and their mutated variants, in cyanobacteria, with the larger genomes of morphologically complex strains harbouring most of them. Sequence analysis has depicted crucial accessory domains along with the proteolytic p20-like sub-domain in OCAs, predicting their functional versatility. However, the cascades involved in sensing death signals, their transduction, and the downstream expression and activation of OCAs remain to be elucidated. Here, we provide a comprehensive description of the attempts to identify mechanisms of PCD and the existence and importance of OCAs based on in silico approaches. We also review the evolutionary and ecological significance of PCD in cyanobacteria. In the future, the analysis of cyanobacterial PCD will identify novel proteins that have varied functional roles in signalling cascades and also help in understanding the incipient mechanism of PCD morphotype(s) from where eukaryotic PCD might have originated.

Targeting ferroptosis for cancer therapy: exploring novel strategies from its mechanisms and role in cancers

Ferroptosis is a novel form of non-apoptotic regulated cell death (RCD), with distinct characteristics and functions in physical conditions and multiple diseases such as cancers. Unlike apoptosis and autophagy, this new RCD is an iron-dependent cell death with features of lethal accumulation of reactive oxygen species (ROS) and over production of lipid peroxidation. Excessive iron from aberrant iron metabolisms or the maladjustment of the two main redox systems thiols and lipid peroxidation role as the major causes of ROS generation, and the redox-acrive ferrous (intracellular labile iron) is a crucial factor for the lipid peroxidation. Regulation of ferrroptosis also involves different pathways such as mevalonate pathway, P53 pathway and p62-Keap1-Nuclear factor (erythroid-derived 2)-like 2 (Nrf2) pathway. Ferroptosis roles as a double-edged sword either suppressing or promoting tumor progression with the release of multiple signaling molecules in the tumor microenvironment. Emerging evidence suggests ferroptosis as a potential target for cancer therapy and ferroptosis inducers including small molecules and nanomaterials have been developed. The application of ferroptosis inducers also relates to overcoming drug resistance and preventing tumor metastasis, and may become a promising strategy combined with other anti-cancer therapies. Here, we summarize the ferroptosis characters from its underlying basis and role in cancer, followed by its possible applications in cancer therapies and challenges maintained.

Pseudomonas Aeruginosa Induced Cell Death in Acute Lung Injury and Acute Respiratory Distress Syndrome

Pseudomonas aeruginosa is an important opportunistic pathogen responsible for the cause of acute lung injury and acute respiratory distress syndrome. P. aeruginosa isthe leading species isolated from patients with nosocomial infection and is detected in almost all the patients with long term ventilation in critical care units. P. aeruginosa infection is also the leading cause of deleterious chronic lung infections in patients suffering from cystic fibrosis as well as the major reason for morbidity in people with chronic obstructive pulmonary disease. P. aeruginosa infections are linked to diseases with high mortality rates and are challenging for treatment, for which no effective remedies have been developed. Massive lung epithelial cell death is a hallmark of severe acute lung injury and acute respiratory distress syndrome caused by P. aeruginosa infection. Lung epithelial cell death poses serious challenges to air barrier and structural integrity that may lead to edema, cytokine secretion, inflammatory infiltration, and hypoxia. Here we review different types of cell death caused by P. aeruginosa serving as a starting point for the diseases it is responsible for causing. We also review the different mechanisms of cell death and potential therapeutics in countering the serious challenges presented by this deadly bacterium.

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.

PI3K Catalytic Subunits α and β Modulate Cell Death and IL-6 Secretion Induced by Talc Particles in Human Lung Carcinoma Cells

Hydrated magnesium silicate (or "talc" particles) is a sclerosis agent commonly used in the management of malignant pleural effusions, a common symptom of metastatic diseases, including lung cancers. However, the direct effects of talc particles to lung carcinoma cells, which can be found in the malignant pleural effusion fluids from patients with lung cancer, are not fully understood. Here, we report a study of the signaling pathways that can modulate the cell death and IL-6 secretion induced by talc particles in human lung carcinoma cells. We found that talc-sensitive cells have higher mRNA and protein expression of PI3K catalytic subunits α and β. Further experiments confirmed that modulation (inhibition or activation) of the PI3K pathway reduces or enhances cellular sensitivity to talc particles, respectively, independent of the inflammasome. By knocking down specific PI3K isoforms, we also confirmed that both PI3Kα and -β mediate the observed talc effects. Our results suggest a novel role of the PI3K pathway in talc-induced cell death and IL-6 secretion in lung carcinoma cells. These cellular events are known to drive fibrosis, and thus further studies of the PI3K pathway may provide a better understanding of the mechanisms of talc sclerosis in the malignant pleural space.

Estrogens decrease osteoclast number by attenuating mitochondria oxidative phosphorylation and ATP production in early osteoclast precursors

Loss of estrogens at menopause is a major cause of osteoporosis and increased fracture risk. Estrogens protect against bone loss by decreasing osteoclast number through direct actions on cells of the myeloid lineage. Here, we investigated the molecular mechanism of this effect. We report that 17β-estradiol (E₂) decreased osteoclast number by promoting the apoptosis of early osteoclast progenitors, but not mature osteoclasts. This effect was abrogated in cells lacking Bak/Bax-two pro-apoptotic members of the Bcl-2 family of proteins required for mitochondrial apoptotic death. FasL has been previously implicated in the pro-apoptotic actions of E₂. However, we show herein that FasL-deficient mice lose bone mass following ovariectomy indistinguishably from FasL-intact controls, indicating that FasL is not a major contributor to the anti-osteoclastogenic actions of estrogens. Instead, using microarray analysis we have elucidated that ERα-mediated estrogen signaling in osteoclast progenitors decreases "oxidative phosphorylation" and the expression of mitochondria complex I genes. Additionally, E₂ decreased the activity of complex I and oxygen consumption rate. Similar to E₂, the complex I inhibitor Rotenone decreased osteoclastogenesis by promoting osteoclast progenitor apoptosis via Bak/Bax. These findings demonstrate that estrogens decrease osteoclast number by attenuating respiration, and thereby, promoting mitochondrial apoptotic death of early osteoclast progenitors.

Magnetic field boosted ferroptosis-like cell death and responsive MRI using hybrid vesicles for cancer immunotherapy

We report a strategy to boost Fenton reaction triggered by an exogenous circularly polarized magnetic field (MF) to enhance ferroptosis-like cell-death mediated immune response, as well as endow a responsive MRI capability by using a hybrid core-shell vesicles (HCSVs). HCSVs are prepared by loading ascorbic acid (AA) in the core and poly(lactic-co-glycolic acid) shell incorporating iron oxide nanocubes (IONCs). MF triggers the release of AA, resulting in the increase of ferrous ions through the redox reaction between AA and IONCs. A significant tumor suppression is achieved by Fenton reaction-mediated ferroptosis-like cell-death. The oxidative stress induced by the Fenton reaction leads to the exposure of calreticulin on tumor cells, which leads to dendritic cells maturation and the infiltration of cytotoxic T lymphocytes in tumor. Furthermore, the depletion of ferric ions during treatment enables monitoring of the Fe reaction in MRI-R2* signal change. This strategy provides a perspective on ferroptosis-based immunotherapy.

Remote ischemic preconditioning-induced neuroprotection in cerebral ischemia-reperfusion injury: Preclinical evidence and mechanisms

Remote ischemic preconditioning (RIPC) is an intrinsic protective phenomenon in which 3 to 4 interspersed cycles of non-fatal regional ischemia followed by reperfusion to the remote tissues protect the vital organs including brain, heart and kidney against sustained ischemia-reperfusion-induced injury. There is growing preclinical evidence supporting the usefulness of RIPC in eliciting neuroprotection against focal and global cerebral ischemia-reperfusion injury. Scientists have explored the involvement of HIF-1α, oxidative stress, apoptotic pathway, Lcn-2, platelets-derived microparticles, splenic response, adenosine A₁ receptors, adenosine monophosphate activated protein kinase and neurogenic pathway in mediating RIPC-induced neuroprotection. The present review discusses the early and late phases of neuroprotection induced by RIPC against cerebral ischemic injury in animals along with the various possible mechanisms.

Kinetic and protective role of autophagy in manganese-exposed BV-2 cells

Manganese (Mn) plays an important role in many physiological processes. Nevertheless, Mn accumulation in the brain can cause a parkinsonian-like syndrome known as manganism. Unfortunately, the therapeutic options for this disease are scarce and of limited efficacy. For this reason, a great effort is being made to understand the cellular and molecular mechanisms involved in Mn toxicity in neuronal and glial cells. Even though evidence indicates that Mn activates autophagy in microglia, the consequences of this activation in cell death remain unknown. In this study, we demonstrated a key role of reactive oxygen species in Mn-induced damage in microglial cells. These species generated by Mn²⁺ induce lysosomal alterations, LMP, cathepsins release and cell death. Besides, we described for the first time the kinetic of Mn²⁺-induced autophagy in BV-2 microglial cells and its relevance to cell fate. We found that Mn promotes a time-dependent increase in LC3-II and p62 expression levels, suggesting autophagy activation. Possibly, cells trigger autophagy to neutralize the risks associated with lysosomal rupture. In addition, pre-treatment with both Rapamycin and Melatonin enhanced autophagy and retarded Mn²⁺ cytotoxicity. In summary, our results demonstrated that, despite the damage inflicted on a subset of lysosomes, the autophagic pathway plays a protective role in Mn-induced microglial cell death. We propose that 2 h Mn²⁺ exposure will not induce disturbances in the autophagic flux. However, as time passes, the accumulated damage inside the cell could trigger a dysfunction of this mechanism. These findings may represent a valuable contribution to future research concerning manganism therapies.

Mitochondria-targeted paraquat and metformin mediate ROS production to induce multiple pathways of retrograde signaling: A dose-dependent phenomenon

The mitochondrial electron transport chain is a major source of reactive oxygen species (ROS) and is also a target of ROS, with an implied role in the stabilization of hypoxia-inducible factor (HIF) and induction of the AMPK pathway. Here we used varying doses of two agents, Mito-Paraquat and Mito-Metformin, that have been conjugated to cationic triphenylphosphonium (TPP⁺) moiety to selectively target them to the mitochondrial matrix compartment, thereby resulting in the site-specific generation of ROS within mitochondria. These agents primarily induce superoxide (O₂^•-) production by acting on complex I. In Raw264.7 macrophages, C2C12 skeletal myocytes, and HCT116 adenocarcinoma cells, we show that mitochondria-targeted oxidants can induce ROS (O₂^•- and H₂O₂). In all three cell lines tested, the mitochondria-targeted agents disrupted membrane potential and activated calcineurin and the Cn-dependent retrograde signaling pathway. Hypoxic culture conditions also induced Cn activation and HIF1α activation in a temporally regulated manner, with the former appearing at shorter exposure times. Together, our results indicate that mitochondrial oxidant-induced retrograde signaling is driven by disruption of membrane potential and activation of Ca²⁺/Cn pathway and is independent of ROS-induced HIF1α or AMPK pathways.

Salidroside protects mice against CCl4-induced acute liver injury via down-regulating CYP2E1 expression and inhibiting NLRP3 inflammasome activation

Salidroside (Sal), a natural phenolic compound isolated from Rhodiola sachalinensis, has been utilized as anti-inflammatory and antioxidant for centuries, however, its effects against liver injury and the underlying mechanisms are unclear. This study was designed to evaluate the protective effects and underlying mechanisms of Sal on carbon tetrachloride (CCl4)-induced acute liver injury (ALI) in mice. C57BL/6 mice were pretreated with Sal before CCl4 injection, the serum and liver tissue were collected to evaluate liver damage and molecular indices. The results showed that Sal pretreatment dose-dependently attenuated CCl4-induced acute liver injury, as indicated by lowering the activities of serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT), and inhibiting hepatic pathological damage and apoptosis. In addition, Sal alleviated CCl4-primed oxidative stress and inflammatory response by restoring hepatic glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA), and inhibiting cytokines. Finally, Sal also down-regulated the expression of cytochrome P4502E1 (CYP2E1), and Nod-like receptor protein 3 (NLRP3) inflammasome activation in the liver of mice by CCl4. Our study demonstrates that Sal exerts its hepatoprotective effects on ALI through its antioxidant and anti-inflammatory effects, which might be mediated by down-regulating CYP2E1 expression and inhibiting NLRP3 inflammasome activation.

2,3,5,4'-tetrahydroxystilbene-2-O-β-D-glucoside induces autophagy of liver by activating PI3K/Akt and Erk pathway in prediabetic rats

BACKGROUND

2,3,5,4'-tetrahydroxystilbene-2-O-β-D-glucoside (TSG) is an active compound derived from Polygonum multiflorum Thunb., a Chinese Taoist herbal medicine, which exerts lipid lowering, anti-cancer, anti-aging, anti-inflammatory and hepatoprotective effects. However, its role in protecting hepatocytes under pre-diabetic condition remains unclear.

METHODS

In this study, we developed prediabetic SD rats by feeding high-fat and high-sugar diet. The body weight, blood lipid, blood glucose, and fasting insulin (FINS) and insulin resistance index (HOMA-IR) were detected and calculated to assess the potential risk of prediabetes. HE and Oil Red O staining was used, and blood level of biochemical index was detected to observe the liver injury. The autophagic cell death-associated signaling proteins, and the potential signaling factors p-Akt/Akt and p-Erk/Erk were detected using western blot to explore the potential effects of TSG on pre-diabetic liver and the underlying mechanisms.

RESULTS

The results showed that the body weight in TSG-treated group was significantly decreased vs. the model group. The blood glucose, the level of FINS and HOMA-IR, TC and TG were decreased in TSG-treated group as well. Furthermore, TSG treatment significantly ameliorated lipid droplet accumulation, enhanced liver anti-oxidative response which may be associated with an increased activity of SOD and GSH-Px, and a decrease of LDLC and MDA. The autophagic cell death-associated proteins, p-AMPK, ATG12, LC3 II, and Beclin 1 were up-regulated in the TSG-treated group, while the upstream signaling pathway, PI3K/Akt and Erk, were activated.

CONCLUSIONS

TSG induced liver autophagic cell death to protect liver from prediabetic injury by activating PI3K/Akt and Erk.

Master Sculptor at Work: Enteropathogenic Escherichia coli Infection Uniquely Modifies Mitochondrial Proteolysis during Its Control of Human Cell Death

Enteropathogenic Escherichia coli (EPEC) causes severe diarrheal disease and is present globally. EPEC virulence requires a bacterial type III secretion system to inject >20 effector proteins into human intestinal cells. Three effectors travel to mitochondria and modulate apoptosis; however, the mechanisms by which effectors control apoptosis from within mitochondria are unknown. To identify and quantify global changes in mitochondrial proteolysis during infection, we applied the mitochondrial terminal proteomics technique mitochondrial stable isotope labeling by amino acids in cell culture-terminal amine isotopic labeling of substrates (MS-TAILS). MS-TAILS identified 1,695 amino N-terminal peptides from 1,060 unique proteins and 390 N-terminal peptides from 215 mitochondrial proteins at a false discovery rate of 0.01. Infection modified 230 cellular and 40 mitochondrial proteins, generating 27 cleaved mitochondrial neo-N termini, demonstrating altered proteolytic processing within mitochondria. To distinguish proteolytic events specific to EPEC from those of canonical apoptosis, we compared mitochondrial changes during infection with those reported from chemically induced apoptosis. During infection, fewer than half of all mitochondrial cleavages were previously described for canonical apoptosis, and we identified nine mitochondrial proteolytic sites not previously reported, including several in proteins with an annotated role in apoptosis, although none occurred at canonical Asp-Glu-Val-Asp (DEVD) sites associated with caspase cleavage. The identification and quantification of novel neo-N termini evidences the involvement of noncaspase human or EPEC protease(s) resulting from mitochondrial-targeting effectors that modulate cell death upon infection. All proteomics data are available via ProteomeXchange with identifier PXD016994.

IMPORTANCE To our knowledge, this is the first study of the mitochondrial proteome or N-terminome during bacterial infection. Identified cleavage sites that had not been previously reported in the mitochondrial N-terminome and that were not generated in canonical apoptosis revealed a pathogen-specific strategy to control human cell apoptosis. These data inform new mechanisms of virulence factors targeting mitochondria and apoptosis during infection and highlight how enteropathogenic Escherichia coli (EPEC) manipulates human cell death pathways during infection, including candidate substrates of an EPEC protease within mitochondria. This understanding informs the development of new antivirulence strategies against the many human pathogens that target mitochondria during infection. Therefore, mitochondrial stable isotope labeling by amino acids in cell culture-terminal amine isotopic labeling of substrates (MS-TAILS) is useful for studying other pathogens targeting human cell compartments.

Pathogenic roles of autoantibodies in systemic sclerosis: Current understandings in pathogenesis

The potential pathogenic role for autoantibodies in systemic sclerosis has captivated researchers for the past 40 years. This review answers the question whether there is yet sufficient knowledge to conclude that certain serum autoantibodies associated with systemic sclerosis contribute to its pathogenesis. Definitions for pathogenic, pathogenetic and functional autoantibodies are formulated, and the need to differentiate these autoantibodies from natural autoantibodies is emphasized. In addition, seven criteria for the identification of pathogenic autoantibodies are proposed. Experimental evidence is reviewed relevant to the classic systemic sclerosis antinuclear autoantibodies, anti-topoisomerase I and anticentromere, and to functional autoantibodies to endothelin 1 type A receptor, angiotensin II type 1 receptor, muscarinic receptor 3, platelet-derived growth factor receptor, chemokine receptors CXCR3 and CXCR4, estrogen receptor α, and CD22. Pathogenic evidence is also reviewed for anti-matrix metalloproteinases 1 and 3, anti-fibrillin 1, anti-IFI16, anti-eIF2B, anti-ICAM-1, and anti-RuvBL1/RuvBL2 autoantibodies. For each autoantibody, objective evidence for a pathogenic role is scored qualitatively according to the seven pathogenicity criteria. It is concluded that anti-topoisomerase I is the single autoantibody specificity with the most evidence in favor of a pathogenic role in systemic sclerosis, followed by anticentromere. However, these autoantibodies have not been demonstrated yet to fulfill completely the seven proposed criteria for pathogenicity. Their contributory roles to the pathogenesis of systemic sclerosis remain possible but not yet conclusively demonstrated. With respect to functional autoantibodies and other autoantibodies, only a few criteria for pathogenicity are fulfilled. Their common presence in healthy and disease controls suggests that major subsets of these immunoglobulins are natural autoantibodies. While some of these autoantibodies may be pathogenetic in systemic sclerosis, establishing that they are truly pathogenic is a work in progress. Experimental data are difficult to interpret because high serum autoantibody levels may be due to polyclonal B-cell activation. Other limitations in experimental design are the use of total serum immunoglobulin G rather than affinity-purified autoantibodies, the confounding effect of other systemic sclerosis autoantibodies present in total immunoglobulin G and the lack of longitudinal studies to determine if autoantibody titers fluctuate with systemic sclerosis activity and severity. These intriguing new specificities expand the spectrum of autoantibodies observed in systemic sclerosis. Continuing elucidation of their potential mechanistic roles raises hope of a better understanding of systemic sclerosis pathogenesis leading to improved therapies.

The Role of Neutrophils and Their Extracellular Traps in the Synergy of Pre-eclampsia and HIV Infection

PURPOSE OF THE REVIEW

In our innate immune system, neutrophils are the first cells to sense signals of infection and to proceed to kill the invading pathogen. This is mediated by their production of neutrophil extracellular traps (NETS) to entrap pathogenic micro-organisms, preventing their amplification and dissemination. Pre-eclampsia (PE) is the leading cause of global maternal mortality, yet to date, there is no cure nor a gold-standard diagnostic strategy. The purpose of this review is to discover the role of neutrophils in PE as early identification markers. Additionally, this review aims to explore the role of neutrophils in HIV-infected pregnancies with PE as a source of synergy.

RECENT FINDINGS

Recent findings demonstrate an elevation of neutrophils and neutrophil extracellular traps (NETs) in PE placentae. This is due to their activation by excessive release of syncytiotrophoblast microparticles (STBM). There is also an elevation of NETs in HIV-infected placentae-where histone H3 entraps HIV by binding to its glycoprotein envelope. Additionally, histones H1 and H2A inhibit HIV infection. It is interesting to note that women with both PE and HIV infection have supressed NETs. This review focuses on the role of neutrophils in the synergy of PE and HIV infection. It is plausible that the deregulation of NETs in the synergy of pre-eclamptic HIV-infected women is strategic for the entrapment of the HIV-1 virus. Finally, it is plausible that neutrophils and NETS may act as early biomarkers of PE development. Graphical abstract.

Differential cell death decisions in the testis: evidence for an exclusive window of ferroptosis in round spermatids

Oxidative stress is a major aetiology in many pathologies, including that of male infertility. Recent evidence in somatic cells has linked oxidative stress to the induction of a novel cell death modality termed ferroptosis. However, the induction of this iron-regulated, caspase-independent cell death pathway has never been explored outside of the soma. Ferroptosis is initiated through the inactivation of the lipid repair enzyme glutathione peroxidase 4 (GPX4) and is exacerbated by the activity of arachidonate 15-lipoxygenase (ALOX15), a lipoxygenase enzyme that facilitates lipid degradation. Here, we demonstrate that male germ cells of the mouse exhibit hallmarks of ferroptosis including; a caspase-independent decline in viability following exposure to oxidative stress conditions induced by the electrophile 4-hydroxynonenal or the ferroptosis activators (erastin and RSL3), as well as a reciprocal upregulation of ALOX15 and down regulation of GPX4 protein expression. Moreover, the round spermatid developmental stage may be sensitized to ferroptosis via the action of acyl-CoA synthetase long-chain family member 4 (ACSL4), which modifies membrane lipid composition in a manner favourable to lipid peroxidation. This work provides a clear impetus to explore the contribution of ferroptosis to the demise of germline cells during periods of acute stress in in vivo models.

HOTTIP Predicts Poor Survival in Gastric Cancer Patients and Contributes to Cisplatin Resistance by Sponging miR-216a-5p

Gastric cancer (GC) is a significant public health burden worldwide, and cisplatin resistance is the leading cause for the failure of chemotherapy in this disease. Previous studies have revealed that HOXA transcript at the distal tip (HOTTIP) is involved in the pathology of GC and is associated with poor overall survival. However, the functional role of HOTTIP in GC chemoresistance remains unclear. In this study, quantitative real-time PCR was used to analyze HOTTIP expression in GC cell lines and in tissues of GC patients who received cisplatin-based chemotherapy. The mechanism of HOTTIP-mediated chemoresistance was assessed using cell viability, apoptosis, and autophagy assays. The relationships among HOTTIP, miR-216a-5p, and Bcl-2 were determined using luciferase reporter and western blot assays. HOTTIP was markedly upregulated in the tissues of GC patients who were treated with gastrectomy and cisplatin chemotherapy, especially in those with recurrent tumors. Further, HOTTIP was increased in the cisplatin-resistant cell line, SGC7901/DDP, compared to the parental cells, SGC7901. Functional assays demonstrated that HOTTIP expression promoted cisplatin resistance and inhibited apoptosis and autophagy in GC cells. Mechanistic investigations revealed that HOTTIP may regulate the functions of GC cells by sponging miR-216a-5p. MiR-216a-5p overexpression decreased Bcl-2 expression, enhanced Beclin1 expression, and active autophagy. Taken together, our study demonstrated that HOTTIP is closely associated with recurrence in GC patients. HOTTIP expression confers cisplatin resistance by regulating the miR-216a-5p/BCL-2/Beclin1/autophagy pathway, which provides a novel strategy to overcome resistance to chemotherapy in GC.

Simultaneous polychromatic flow cytometric detection of multiple forms of regulated cell death

Currently the study of Regulated Cell Death (RCD) processes is limited to the use of lysed cell populations for Western blot analysis of each separate RCD process. We have previously shown that intracellular antigen flow cytometric analysis of RIP3, Caspase-3 and cell viability dye allowed the determination of levels of apoptosis (Caspase-3^+ ve/RIP3^− ve), necroptosis (RIP3^Hi + ve/Caspase-3^− ve) and RIP1-dependent apoptosis (Caspase-3^+ ve/RIP3^+ ve) in a single Jurkat cell population. The addition of more intracellular markers allows the determination of the incidence of parthanatos (PARP), DNA Damage Response (DDR, H2AX), H2AX hyper-activation of PARP (H2AX/PARP) autophagy (LC3B) and ER stress (PERK), thus allowing the identification of 124 sub-populations both within live and dead cell populations. Shikonin simultaneously induced Jurkat cell apoptosis and necroptosis the degree of which can be shown flow cytometrically together with the effects of blockade of these forms of cell death by zVAD and necrostatin-1 have on specific RCD populations including necroptosis, early and late apoptosis and RIP1-dependent apoptosis phenotypes in live and dead cells. Necrostatin-1 and zVAD was shown to modulate levels of shikonin induced DDR, hyper-action of PARP and parthanatos in the four forms of RCD processes analysed. LC3B was up-regulated by combined treatment of zVAD with chloroquine which also revealed that DNA damage was reduced in live cells but enhanced in dead cells indicating the role of autophagy in maintaining cell health. This approach to RCD research should be a great advance to understanding the mechanisms of drugs and their effects upon RCD populations.

Hexavalent chromium-induced autophagic death of WRL-68 cells is mitigated by aqueous extract of Cuminum cyminum L. seeds

In this study, we assessed the potential of aqueous extract (CSE_aq) of Cuminum cyminum L. (cumin) seeds in protecting WRL-68 cells from hexavalent chromium [Cr(VI)]-induced oxidative injury. Cells exposed to Cr(VI) (10 μM CrO₃) for 24 h demonstrated a twofold increase in ROS, which, in turn, led to extensive oxidative stress, consequently causing colossal decline in cell viability (by 58.82 ± 9.79%) and proliferation (as was evident from a reduced expression of Ki-67, a proliferation marker). Immunofluorescence studies showed that Cr(VI) diminished the expressions of mTOR and survivin in WRL-68 cells. It also led to a substantial elevation of BECN1 expression, which suggested autophagy. Overall, our results indicated that 24 h exposure of WRL-68 cells to Cr(VI) caused oxidative stress-induced autophagic cell death. CSE_aq was found to protect WRL-68 cells from the same fate by refurbishing their viability and proliferation in a dose-dependent manner. The extract reduced ROS in these cells, which consequently decreased the degree of autophagic cell death by restoring expressions of mTOR, survivin and BECN1 to their respective normal levels. Biochemical assays revealed that CSE_aq is rich in phenolic constituents. Total phenolic content of CSE_aq demonstrated positive correlations with (i) its antioxidant potential, (ii) its alleviation of cellular oxidative stress and (iii) its cytoprotective efficacy in Cr(VI)-treated WRL-68 cells. We also identified the major phenolic constituents of CSE_aq. Our study suggested that polyphenols in CSE_aq might be responsible for protecting WRL-68 cells from Cr(VI)-governed oxidative assault that would have otherwise led to survivin/mTOR-mediated autophagic death.

Current Approaches for Combination Therapy of Cancer: The Role of Immunogenic Cell Death

Cell death resistance is a key feature of tumor cells. One of the main anticancer therapies is increasing the susceptibility of cells to death. Cancer cells have developed a capability of tumor immune escape. Hence, restoring the immunogenicity of cancer cells can be suggested as an effective approach against cancer. Accumulating evidence proposes that several anticancer agents provoke the release of danger-associated molecular patterns (DAMPs) that are determinants of immunogenicity and stimulate immunogenic cell death (ICD). It has been suggested that ICD inducers are two different types according to their various activities. Here, we review the well-characterized DAMPs and focus on the different types of ICD inducers and recent combination therapies that can augment the immunogenicity of cancer cells.

Hepatoprotective and Anti-Oxidative Effects of Total Flavonoids From Qu Zhi Qiao (Fruit of Citrus Paradisi cv.Changshanhuyou) on Nonalcoholic Steatohepatitis In Vivo and In Vitro Through Nrf2-ARE Signaling Pathway

Nonalcoholic steatohepatitis (NASH) is a liver disease defined as the dynamic condition of hepatocellular injury during the progress of nonalcoholic fatty liver disease (NAFLD). Total flavonoids from the dry and immature fruits of Citrus Paradisi cv.Changshanhuyou (accepted species name: Citrus × aurantium L) (Qu Zhi Qiao, QZQ) are purified and named TFCH. This study was purposed to investigate and analyze the effect of TFCH on NASH model through Nuclear factor erythroid 2-related factor 2 (Nrf2)- antioxidant response elements pathway in vivo and in vitro. In vivo study was performed using male C57BL/6 mice fed with high fat diet 16 weeks for NASH model. After 7-week modeling, mice in TFCH-treated group were daily treated with intragastric administration of TFCH at 25 mg/kg, 50 mg/kg, 200 mg/kg, respectively, for successive 8 weeks. Histopathological and immunohistochemical analyses were conducted for evaluating severity of NASH-mice model and the effect of TFCH treatment. In vitro experiment was performed by using human LX-2 cells and cultured with Free fatty acid (FFA) (Oleic acid: palmitic: l: 0.5 mmol/L) for 24 h and then treated with TFCH at different concentrations (0, 25, 50, 100, 200 mg/ml) for 6 h,12 h, and 24 h. Anti-apoptosis effect of TFCH on LX-2 cells cultured with FFA was revealed by the CCK-8 assay. Lipid parameters and oxidative stress markers were measured in vivo and in vitro, results showed that TFCH dose-dependently and greatly increased the antioxidant ability and reduced the oxidative damage in NASH model. The protein expression of Nrf2 and the downstream target genes in mice liver and human LX-2 cells were tested by Western blot analysis to investigate the possible molecular mechanisms of TFCH. Our results indicated that TFCH up-regulated protein expression of these genes and have the significant influence in activating the Nrf2-ARE signaling pathway. This study shows Nrf2-ARE signaling pathway may provide novel therapeutic opportunities for NASH therapy in the future.

Hypoxia-Driven Immune Escape in the Tumor Microenvironment

The tumor microenvironment is a complex ecosystem comprised of many different cell types, abnormal vasculature and immunosuppressive cytokines. The irregular growth kinetics with which tumors grow leads to increased oxygen consumption and, in turn, hypoxic conditions. Hypoxia has been associated with poor clinical outcome, increased tumor heterogeneity, emergence of resistant clones and evasion of immune detection. Additionally, hypoxia-driven cell death pathways have traditionally been thought of as tolerogenic processes. However, as researchers working in the field of immunotherapy continue to investigate and unveil new types of immunogenic cell death (ICD), it has become clear that, in some instances, hypoxia may actually induce ICD within a tumor. In this review, we will discuss hypoxia-driven immune escape that drives poor prognostic outcomes, the ability of hypoxia to induce ICD and potential therapeutic targets amongst hypoxia pathways.

Necroptosis in Cholangiocarcinoma

Necroptosis is a type of regulated cell death that is increasingly being recognized as a relevant pathway in different pathological conditions. Necroptosis can occur in response to multiple stimuli, is triggered by the activation of death receptors, and is regulated by receptor-interacting protein kinases 1 and 3 and mixed-lineage kinase domain-like, which form a regulatory complex called the necrosome. Accumulating evidence suggests that necroptosis plays a complex role in cancer, which is likely context-dependent and can vary among different types of neoplasms. Necroptosis serves as an alternative mode of programmed cell death overcoming apoptosis and, as a pro-inflammatory death type, it may inhibit tumor progression by releasing damage-associated molecular patterns to elicit robust cross-priming of anti-tumor CD8+ T cells. The development of therapeutic strategies triggering necroptosis shows great potential for anti-cancer therapy. In this review, we summarize the current knowledge on necroptosis and its role in liver biliary neoplasms, underlying the potential of targeting necroptosis components for cancer treatment.

Artesunate Affects T Antigen Expression and Survival of Virus-Positive Merkel Cell Carcinoma

Merkel cell carcinoma (MCC) is a rare and highly aggressive skin cancer with frequent viral etiology. Indeed, in about 80% of cases, there is an association with Merkel cell polyomavirus (MCPyV); the expression of viral T antigens is crucial for growth of virus-positive tumor cells. Since artesunate—a drug used to treat malaria—has been reported to possess additional anti-tumor as well as anti-viral activity, we sought to evaluate pre-clinically the effect of artesunate on MCC. We found that artesunate repressed growth and survival of MCPyV-positive MCC cells in vitro. This effect was accompanied by reduced large T antigen (LT) expression. Notably, however, it was even more efficient than shRNA-mediated downregulation of LT expression. Interestingly, in one MCC cell line (WaGa), T antigen knockdown rendered cells less sensitive to artesunate, while for two other MCC cell lines, we could not substantiate such a relation. Mechanistically, artesunate predominantly induces ferroptosis in MCPyV-positive MCC cells since known ferroptosis-inhibitors like DFO, BAF-A1, Fer-1 and β-mercaptoethanol reduced artesunate-induced death. Finally, application of artesunate in xenotransplanted mice demonstrated that growth of established MCC tumors can be significantly suppressed in vivo. In conclusion, our results revealed a highly anti-proliferative effect of the approved and generally well-tolerated anti-malaria compound artesunate on MCPyV-positive MCC cells, suggesting its potential usage for MCC therapy.

Ferroptosis and Its Potential Role in Human Diseases

Ferroptosis is a novel regulated cell death pattern discovered when studying the mechanism of erastin-killing RAS mutant tumor cells in 2012. It is an iron-dependent programmed cell death pathway mainly caused by an increased redox imbalance but with distinct biological and morphology characteristics when compared to other known cell death patterns. Ferroptosis is associated with various diseases including acute kidney injury, cancer, and cardiovascular, neurodegenerative, and hepatic diseases. Moreover, activation or inhibition of ferroptosis using a variety of ferroptosis initiators and inhibitors can modulate disease progression in animal models. In this review, we provide a comprehensive analysis of the characteristics of ferroptosis, its initiators and inhibitors, and the potential role of its main metabolic pathways in the treatment and prevention of various diseased states. We end the review with the current knowledge gaps in this area to provide direction for future research on ferroptosis.

Ammonia regulates chicken tracheal cell necroptosis via the LncRNA-107053293/MiR-148a-3p/FAF1 axis

Ammonia (NH₃) is a known harmful gas that causes injury to the respiratory system. Ammonia also exists in haze, forming secondary organic aerosols. However, the specific damage caused by NH₃ in chicken trachea has not been determined. The regulatory mechanism of ceRNA and its multiple roles have been proposed in many pathomechanisms; therefore, we investigated the functional role of ceRNA in chicken trachea after NH₃ inhalation. Broiler chicken trachea exposed to NH₃ was selected as the research object. The pathological ultrastructure was observed by transmission electron microscopy. Transcriptome analyses were applied and referenced, and lncRNA-107053293 and miR-148a-3p and FAF1 were selected. A dual-luciferase reporter assay verified the target relationship. Real-time quantitative PCR (RT-PCR) and western blotting were performed to examine the expression levels of necroptosis genes, such as RIPK1, RIPK3, MLKL, caspase 8, and FADD. Our results indicated that lncRNA-107053293 regulated necroptosis by acting as a competing endogenous RNA of miR-148a-3p. FAF1, as a gene target of miR-148a-3p, also affects necroptosis.

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.

[Endoplasmic reticulum stress response and pathogenesis of non-alcoholic steatohepatitis]

The incidence of chronic liver disease is constantly increasing, owing to the obesity epidemic. Non-alcoholic fatty liver disease (NAFLD) is currently affecting 20-30% of the general population and 75-100% of obese individuals. NAFLD ranges from simple steatosis to damaging non-alcoholic steatohepatitis (NASH), potentially developing into hepatocellular carcinoma. No efficient pharmacological treatment is yet available. During obesity, the hepatic ER stress response can arise from extracellular stress (lipids, glucose, cytokines) and from intracellular stress including lipid buildup in the hepatocyte (steatosis), a hallmark of NAFLD. The chronic activation of the hepatic ER stress response may be a crucial event in the steatosis-NASH transition, triggering cell death, inflammation and accelerating metabolic disorders. We discuss these aspects and we propose that targeting the ER stress response could be effective in treating NAFLD.

Enhancement of sorafenib-mediated death of Hepatocellular carcinoma cells by Carnosic acid and Vitamin D2 analog combination

Hepatocellular carcinoma (HCC) is the most common form of liver cancer and it is the third leading cause of global cancer mortality. Sorafenib (Sf) is the first oral multi-kinase inhibitor approved for systemic treatment of advanced HCC, and can prolong survival, although only for three months longer than placebo treated patients. Preclinical studies showed that active forms of vitamin D can induce cell differentiation and regulate cell survival in several cell types, and epidemiological data link vitamin D insufficiency to an increased risk of neoplastic diseases, suggesting a potentially important role of vitamin D in cancer therapy. Other studies showed that the effect of vitamin D analogs on human neoplastic cells is potentiated by carnosic acid (CA), a plant polyphenol with anti-oxidant properties. Here we tested if the addition of the vitamin D2 analog Doxercalciferol (D2) together with CA can enhance the cytotoxic effect of Sf on HCC cell lines Huh7 (Sf-sensitive) and HCO2 (Sf-resistant). Indeed, this combination increased HCC cell death in cell lines, enhancing autophagy as well as apoptosis. Autophagy was confirmed by increased cytoplasmic vacuolation, perinuclear aggregation of LC3, and elevated protein levels of autophagy markers Beclin1, Atg3, and LC3. These results suggest that a regimen which combines a vitamin D2 analog/CA mixture with Sf can be a novel and promising therapeutic option for the treatment of HCC.

Kanglexin, a novel anthraquinone compound, protects against myocardial ischemic injury in mice by suppressing NLRP3 and pyroptosis

Pyroptosis is a form of inflammatory cell death that could be driven by the nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome activation following myocardial infarction (MI). Emerging evidence suggests the therapeutic potential for ameliorating MI-induced myocardial damages by targeting NLRP3 and pyroptosis. In this study, we investigated the myocardial protection effect of a novel anthraquinone compound (4,5-dihydroxy-7-methyl-9,10-anthraquinone-2-ethyl succinate) named Kanglexin (KLX) in vivo and in vitro. Male C57BL/6 mice were pre-treated either with KLX (20, 40 mg· kg^-1per day, intragastric gavage) or vehicle for 7 consecutive days prior to ligation of coronary artery to induce permanent MI. KLX administration dose-dependently reduced myocardial infarct size and lactate dehydrogenase release and improved cardiac function as compared to vehicle-treated mice 24 h after MI. We found that MI triggered NLRP3 inflammasome activation leading to conversion of interleukin-1β (IL-1β) and IL-18 into their active mature forms in the heart, which could expand the infarct size and drive cardiac dysfunction. We also showed that MI induced pyroptosis, as evidenced by increased DNA fragmentation, mitochondrial swelling, and cell membrane rupture, as well as increased levels of pyroptosis-related proteins, including gasdermin D, N-terminal GSDMD, and cleaved caspase-1. All these detrimental alterations were prevented by KLX. In hypoxia- or lipopolysaccharide (LPS)-treated neonatal mouse ventricular cardiomyocytes, we showed that KLX (10 μM) decreased the elevated levels of terminal deoxynucleotidyl transferase dUTP nick end labeling- and propidium iodide-positive cells, and pyroptosis-related proteins. We conclude that KLX prevents MI-induced cardiac damages and cardiac dysfunction at least partly through attenuating NLRP3 and subsequent cardiomyocyte pyroptosis, and it is worthy of more rigorous investigations for its potential for alleviating ischemic heart disease.

Kanakugiol, a Compound Isolated from Lindera erythrocarpa, Promotes Cell Death by Inducing Mitotic Catastrophe after Cell Cycle Arrest

A novel compound named 'kanakugiol' was recently isolated from Lindera erythrocarpa and showed free radical-scavenging and antifungal activities. However, the details of the anticancer effect of kanakugiol on breast cancer cells remain unclear. We investigated the effect of kanakugiol on the growth of MCF-7 human breast cancer cells. Kanakugiol affected cell cycle progression, and decreased cell viability in MCF-7 cells in a dose-dependent manner. It also enhanced PARP cleavage (50 kDa), whereas DNA laddering was not induced. FACS analysis with annexin V-FITC/PI staining showed necrosis induction in kanakugiol-treated cells. Caspase-9 cleavage was also induced. Expression of death receptors was not altered. However, Bcl-2 expression was suppressed, and mitochondrial membrane potential collapsed, indicating limited apoptosis induction by kanakugiol. Immunofluorescence analysis using α-tubulin staining revealed mitotic exit without cytokinesis (4N cells with two nuclei) due to kanakugiol treatment, suggesting that mitotic catastrophe may have been induced via microtubule destabilization. Furthermore, cell cycle analysis results also indicated mitotic catastrophe after cell cycle arrest in MCF-7 cells due to kanakugiol treatment. These findings suggest that kanakugiol inhibits cell proliferation and promotes cell death by inducing mitotic catastrophe after cell cycle arrest. Thus, kanakugiol shows potential for use as a drug in the treatment of human breast cancer.

Inflammatory and Fibrogenic Factors in Proliferative Vitreoretinopathy Development

Purpose

Proliferative vitreoretinopathy (PVR) occurs in 5%-10% of rhegmatogenous retinal detachment cases and is the principle cause for failure of retinal reattachment surgery. Although there are a number of surgical adjunctive agents available for preventing the development of PVR, all have limited efficacy. Discovering predictive molecular biomarkers to determine the probability of PVR development after retinal reattachment surgery will allow better patient stratification for more targeted drug evaluations.

Methods

Narrative literature review.

Results

We provide a summary of the inflammatory and fibrogenic factors found in ocular fluid samples during the development of retinal detachment and PVR and discuss their possible use as molecular PVR predictive biomarkers.

Conclusions

Studies monitoring the levels of the above factors have found that few if any have predictive biomarker value, suggesting that widening the phenotype of potential factors and a combinatorial approach are required to determine predictive biomarkers for PVR.

Translational Relevance

The identification of relevant biomarkers relies on an understanding of disease signaling pathways derived from basic science research. We discuss the extent to which those molecules identified as biomarkers and predictors of PVR relate to disease pathogenesis and could function as useful disease predictors. (http://www.umin.ac.jp/ctr/ number, UMIN000005604).

The Role of CHK1 Varies with the Status of Oestrogen-receptor and Progesterone-receptor in the Targeted Therapy for Breast Cancer

Objective: The therapeutic effects of the checkpoint kinase 1 (CHK1)-targeted inhibition in tumor therapy have been confirmed, but how to choose an effective application method in breast cancer with heterogeneous molecular characteristics has remained unclear.

Methods: We evaluated the status of CHK1 in breast cancer using the cancer genome atlas database. Chemosensitivity and single-agent antitumor activity of CHK1 inhibition were measured by drug sensitivity assay, cell proliferation assay, cell cycle and apoptosis analysis in breast cancer with different ER/PR status. And based on the conjoint transcriptome atlas analyses, the corresponding mechanism were explored.

Results: In ER^-/PR^-/HER2^- breast cancer, CHK1 inhibition enhanced adriamycin (ADR) chemosensitivity which was mediated by the mitotic checkpoint complex (MCC)-anaphase-promoting complex/cyclosome (APC/C)-cyclin B1 axis, Msh homeobox 2 (MSX2) and Bcl-2-like protein 11 (BIM). However, in ER⁺/PR⁺/HER2^- breast cancer, because of the significant suppression for centromere protein F (CENPF)-mediated transcriptional activation of CHK1 induced by ADR itself, CHK1 inhibition fails to sensitize ADR toxicity. Interestingly, CHK1 inhibition showed the single-agent antitumor activity in ER⁺/PR⁺/HER2^- breast cancer which was mediated by the cyclin dependent kinase inhibitor 1A (p21), kinesin family member 11 (Eg5) and cell surface death receptor (Fas).

Conclusions: CHK1's variable role determines the application of CHK1 inhibition in breast cancer with ER/PR heterogeneity.

Mechanisms and Therapeutic Regulation of Pyroptosis in Inflammatory Diseases and Cancer

Programmed Cell Death (PCD) is considered to be a pathological form of cell death when mediated by an intracellular program and it balances cell death with survival of normal cells. Pyroptosis, a type of PCD, is induced by the inflammatory caspase cleavage of gasdermin D (GSDMD) and apoptotic caspase cleavage of gasdermin E (GSDME). This review aims to summarize the latest molecular mechanisms about pyroptosis mediated by pore-forming GSDMD and GSDME proteins that permeabilize plasma and mitochondrial membrane activating pyroptosis and apoptosis. We also discuss the potentiality of pyroptosis as a therapeutic target in human diseases. Blockade of pyroptosis by compounds can treat inflammatory disease and pyroptosis activation contributes to cancer therapy.

Cellular Stress and General Pathological Processes

From the viewpoint of the general pathology, most of the human diseases are associated with a limited number of pathogenic processes such as inflammation, tumor growth, thrombosis, necrosis, fibrosis, atrophy, pathological hypertrophy, dysplasia and metaplasia. The phenomenon of chronic low-grade inflammation could be attributed to non-classical forms of inflammation, which include many neurodegenerative processes, pathological variants of insulin resistance, atherosclerosis, and other manifestations of the endothelial dysfunction. Individual and universal manifestations of cellular stress could be considered as a basic element of all these pathologies, which has both physiological and pathophysiological significance. The review examines the causes, main phenomena, developmental directions and outcomes of cellular stress using a phylogenetically conservative set of genes and their activation pathways, as well as tissue stress and its role in inflammatory and para-inflammatory processes. The main ways towards the realization of cellular stress and its functional blocks were outlined. The main stages of tissue stress and the classification of its typical manifestations, as well as its participation in the development of the classical and non-classical variants of the inflammatory process, were also described. The mechanisms of cellular and tissue stress are structured into the complex systems, which include networks that enable the exchange of information with multidirectional signaling pathways which together make these systems internally contradictory, and the result of their effects is often unpredictable. However, the possible solutions require new theoretical and methodological approaches, one of which includes the transition to integral criteria, which plausibly reflect the holistic image of these processes.

Current Evidence on Cell Death in Preterm Brain Injury in Human and Preclinical Models

Despite tremendous advances in neonatal intensive care over the past 20 years, prematurity carries a high burden of neurological morbidity lasting lifelong. The term encephalopathy of prematurity (EoP) coined by Volpe in 2009 encompasses all aspects of the now known effects of prematurity on the immature brain, including altered and disturbed development as well as specific lesional hallmarks. Understanding the way cells are damaged is crucial to design brain protective strategies, and in this purpose, preclinical models largely contribute to improve the comprehension of the cell death mechanisms. While neuronal cell death has been deeply investigated and characterized in (hypoxic–ischemic) encephalopathy of the newborn at term, little is known about the types of cell death occurring in preterm brain injury. Three main different morphological cell death types are observed in the immature brain, specifically in models of hypoxic–ischemic encephalopathy, namely, necrotic, apoptotic, and autophagic cell death. Features of all three types may be present in the same dying neuron. In preterm brain injury, description of cell death types is sparse, and cell loss primarily concerns immature oligodendrocytes and, infrequently, neurons. In the present review, we first shortly discuss the different main severe preterm brain injury conditions that have been reported to involve cell death, including periventricular leucomalacia (PVL), diffuse white matter injury (dWMI), and intraventricular hemorrhages, as well as potentially harmful iatrogenic conditions linked to premature birth (anesthesia and caffeine therapy). Then, we present an overview of current evidence concerning cell death in both clinical human tissue data and preclinical models by focusing on studies investigating the presence of cell death allowing discriminating between the types of cell death involved. We conclude that, to improve brain protective strategies, not only apoptosis but also other cell death (such as regulated necrotic and autophagic) pathways now need to be investigated together in order to consider all cell death mechanisms involved in the pathogenesis of preterm brain damage.

Mitochondria and Lysosomes Participate in Vip3Aa-Induced Spodoptera frugiperda Sf9 Cell Apoptosis

Vip3Aa, a soluble protein produced by certain Bacillus thuringiensis strains, is capable of inducing apoptosis in Sf9 cells. However, the apoptosis mechanism triggered by Vip3Aa is unclear. In this study, we found that Vip3Aa induces mitochondrial dysfunction, as evidenced by signs of collapse of mitochondrial membrane potential, accumulation of reactive oxygen species, release of cytochrome c, and caspase-9 and -3 activation. Meanwhile, our results indicated that Vip3Aa reduces the ability of lysosomes in Sf9 cells to retain acridine orange. Moreover, pretreatment with Z-Phe-Tyr-CHO (a cathepsin L inhibitor) or pepstatin (a cathepsin D inhibitor) increased Sf9 cell viability, reduced cytochrome c release, and decreased caspase-9 and -3 activity. In conclusion, our findings suggested that Vip3Aa promotes Sf9 cell apoptosis by mitochondrial dysfunction, and lysosomes also play a vital role in the action of Vip3Aa.