Marine-derived antimicrobial peptide piscidin-1 triggers extrinsic and intrinsic apoptosis in oral squamous cell carcinoma through reactive oxygen species production and inhibits angiogenesis

Cancer of the head and neck encompasses a wide range of cancers, including oral and oropharyngeal cancers. Oral cancer is often diagnosed at advanced stages and has a dismal prognosis. Piscidin-1, a marine antimicrobial peptide (AMP) containing approximately 22 amino acids, also exhibits significant anticancer properties. We investigated the possible anti-oral cancer effects of piscidin-1 and clarified the mechanisms underlying these effects. We treated the oral squamous cell carcinoma cell lines OC2 and SCC4 with piscidin-1. Cell viability and the expression of different hallmark apoptotic molecules, including reactive oxygen species (ROS), were tested using the appropriate MTT assay, flow cytometry and western blotting assays, and human umbilical vein endothelial cell (HUVEC) wound healing, migration, and tube formation (angiogenesis) assays. Piscidin-1 increases cleaved caspase 3 levels to induce apoptosis. Piscidin-1 also increases ROS levels and intensifies oxidative stress in the endoplasmic reticulum and mitochondria, causing mitochondrial dysfunction. Additionally, it decreases the oxygen consumption rates and activity of mitochondrial complexes I-V. As expected, the antioxidants MitoTEMPOL and N-acetylcysteine reduce piscidin-1-induced ROS generation and intracellular calcium accumulation. Piscidin-1 also inhibits matrix metalloproteinase (MMP)-2/-9 expression in HUVECs, affecting migration and tube formation angiogenesis. We demonstrated that piscidin-1 can promote apoptosis via both intrinsic and extrinsic apoptotic pathways and findings indicate that piscidin-1 has anti-proliferative and anti-angiogenic properties in oral cancer treatment. Our study on piscidin-1 thus provides a basis for future translational anti-oral cancer drug research and a new theoretical approach for anti-oral cancer clinical research.

Synthesis and biological activity of 11-Oxygenated and heterocyclic estrone analogs in pancreatic cancer monolayers and 3D spheroids

Pancreatic Ductal Adenocarcinoma (PDAC), representing over 90 % of pancreatic cancer diagnoses, is an aggressive disease with survivability among the worst of all cancers due to its difficulty in detection and its high metastatic properties. Current therapies for PDAC show limited success at extending life expectancies, primarily due to cancer resistance and lack of patient-specific targeted therapies. This work highlights the design and evaluation of estrone-derived analogs with both heterocyclic side-chain functionality and 11-oxygenated functionality for use in pancreatic cancer. First-round heterocyclic analogs show preliminary promise in AsPC-1 and Panc-1 cell lines, with IC50 values as low as 10.16 ± 0.83 µM. Their success, coupled with design choices from other studies, led to the synthesis of novel 11-hydroxyl and 11-keto estrone analogs that show potent in-vitro toxicity against various pancreatic cancer models. The three most cytotoxic analogs, KA1, KA2, and KA9 demonstrated low micromolar activities in both MTT and CellTiter assays in three pancreatic cancer cell lines: AsPC-1, Panc-1, and BxPC-3, as well as in a co-culture of Panc-1 and pancreatic stellate cells. IC50 values for KA9 (4.17 ± 0.90, 5.28 ± 1.87, and 5.70 ± 0.65 µM respectively) shows consistency in all cell lines tested. KA9 is also able to cause an increase in caspases 3 and 7 activity, key markers for apoptosis, at non-cytotoxic concentrations. Additional work was performed by generating 3D pancreatic cancer spheroids to better modulate the pancreatic tumor microenvironment, and KA9 continued to show the best IC50 values (21.0 and 24.3 µM) in both cell types tested. KA9 was also able to prevent the growth of spheroids whereas the standard chemotherapy, Gemcitabine, could not, suggesting that it may be a potent analog for future development of treatments. Molecular dynamic simulations were also performed to confirm biological findings and uncovered that KA9's preferential binding location is in the active site pocket of key proteins involved in cytotoxicity.

Apoptotic and non-apoptotic roles of caspases in placenta physiology and pathology

Caspases, a family of cysteine proteases, are pivotal regulators of apoptosis, the tightly controlled cell death process crucial for eliminating excessive or unnecessary cells during development, including placental development. Collecting research has unveiled the multifaceted roles of caspases in the placenta, extending beyond apoptosis. Apart from their involvement in placental tissue remodeling via apoptosis, caspases actively participate in essential regulatory processes, such as trophoblast fusion and differentiation, significantly influencing placental growth and functionality. In addition, growing evidence indicates an elevation in caspase activity under pathological conditions like pre-eclampsia (PE) and intrauterine growth restriction (IUGR), leading to excessive cell death as well as inflammation. Drawing from advancements in caspase research and placental development under both normal and abnormal conditions, we examine the significance of caspases in both cell death (apoptosis) and non-cell death-related processes within the placenta. We also discuss potential therapeutics targeting caspase-related pathways for placenta disorders.

Toward a predictive understanding of epithelial cell death

Epithelial cell death is highly prevalent during development and tissue homeostasis. While we have a rather good understanding of the molecular regulators of programmed cell death, especially for apoptosis, we still fail to predict when, where, how many and which specific cells will die in a tissue. This likely relies on the much more complex picture of apoptosis regulation in a tissular and epithelial context, which entails cell autonomous but also non-cell autonomous factors, diverse feedback and multiple layers of regulation of the commitment to apoptosis. In this review, we illustrate this complexity of epithelial apoptosis regulation by describing these different layers of control, all demonstrating that local cell death probability is a complex emerging feature. We first focus on non-cell autonomous factors that can locally modulate the rate of cell death, including cell competition, mechanical input and geometry as well as systemic effects. We then describe the multiple feedback mechanisms generated by cell death itself. We also outline the multiple layers of regulation of epithelial cell death, including the coordination of extrusion and regulation occurring downstream of effector caspases. Eventually, we propose a roadmap to reach a more predictive understanding of cell death regulation in an epithelial context.

Cytotoxicity of bismuth(III) dithiocarbamate derivatives by promoting a mitochondrial-dependent apoptotic pathway and suppressing MCF-7 breast adenocarcinoma cell invasion

We previously reported that the bismuth(III) dithiocarbamate derivative, bismuth diethyldithiocarbamate (1) exhibited greater cytotoxicity while inducing apoptosis via the intrinsic pathway in MCF-7 cells. We further evaluated the other bismuth(III) dithiocarbamate derivatives, Bi[S2CNR]3, with R = (CH2CH2OH)(iPr), (CH2)4, and (CH2CH2OH)(CH3), denoted as 2, 3, and 4, respectively, in the same MCF-7 cell line. 2-4 were found to exhibit IC50 values of 10.33 ± 0.06 µM, 1.07 ± 0.01 µM and 25.37 ± 0.12 µM, respectively, compared to that of cisplatin at 30.53 ± 0.23 µM. Apoptotic promotion via the mitochondrial-dependent pathway was due to the elevation of intracellular reactive oxygen species (ROS), promotion of caspases, release of cytochrome c, fragmentation of DNA, and results of staining assay observed in all compound-treated cells. 2-4 are also capable of suppressing MCF-7 cell invasion and modulate Lys-48 also Lys-63 linked polyubiquitination, leading to proteasomal degradation. Analysis of gene expression via qRT-PCR revealed their modulation, which supported all activities conducted upon treatment with 2-4. Altogether, bismuth dithiocarbamate derivatives, with bismuth(III) as the metal center bound to ligands, isopropyl ethanol, pyrrolidine, and methyl ethanol dithiocarbamate, are potential anti-breast cancer agents that induce apoptosis and suppress metastasis. Further studies using other breast cancer cell lines and in vivo studies are recommended to clarify the anticancer effects of these compounds.

Exploring the significance of caspase-cleaved tau in tauopathies and as a complementary pathology to phospho-tau in Alzheimer's disease: implications for biomarker development and therapeutic targeting

Tauopathies are neurodegenerative diseases that typically require postmortem examination for a definitive diagnosis. Detecting neurotoxic tau fragments in cerebrospinal fluid (CSF) and serum provides an opportunity for in vivo diagnosis and disease monitoring. Current assays primarily focus on total tau or phospho-tau, overlooking other post-translational modifications (PTMs). Caspase-cleaved tau is a significant component of AD neuropathological lesions, and experimental studies confirm the high neurotoxicity of these tau species. Recent evidence indicates that certain caspase-cleaved tau species, such as D13 and D402, are abundant in AD brain neurons and only show a modest degree of co-occurrence with phospho-tau, meaning caspase-truncated tau pathology is partially distinct and complementary to phospho-tau pathology. Furthermore, these caspase-cleaved tau species are nearly absent in 4-repeat tauopathies. In this review, we will discuss the significance of caspase-cleaved tau in the development of tauopathies, specifically emphasizing its role in AD. In addition, we will explore the potential of caspase-cleaved tau as a biomarker and the advantages for drug development targeting caspase-6. Developing specific and sensitive assays for caspase-cleaved tau in biofluids holds promise for improving the diagnosis and monitoring of tauopathies, providing valuable insights into disease progression and treatment efficacy.

Caspase-8 activity mediates TNFα production and restricts Coxiella burnetii replication during murine macrophage infection

Coxiella burnetii is an obligate intracellular bacteria which causes the global zoonotic disease Q Fever. Treatment options for infection are limited, and development of novel therapeutic strategies requires a greater understanding of how C. burnetii interacts with immune signaling. Cell death responses are known to be manipulated by C. burnetii, but the role of caspase-8, a central regulator of multiple cell death pathways, has not been investigated. In this research, we studied bacterial manipulation of caspase-8 signaling and the significance of caspase-8 to C. burnetii infection, examining bacterial replication, cell death induction, and cytokine signaling. We measured caspase, RIPK, and MLKL activation in C. burnetii-infected TNFα/CHX-treated THP-1 macrophage-like cells and TNFα/ZVAD-treated L929 cells to assess apoptosis and necroptosis signaling. Additionally, we measured C. burnetii replication, cell death, and TNFα induction over 12 days in RIPK1-kinase-dead, RIPK3-kinase-dead, or RIPK3-kinase-dead-caspase-8-/- BMDMs to understand the significance of caspase-8 and RIPK1/3 during infection. We found that caspase-8 is inhibited by C. burnetii, coinciding with inhibition of apoptosis and increased susceptibility to necroptosis. Furthermore, C. burnetii replication was increased in BMDMs lacking caspase-8, but not in those lacking RIPK1/3 kinase activity, corresponding with decreased TNFα production and reduced cell death. As TNFα is associated with the control of C. burnetii, this lack of a TNFα response may allow for the unchecked bacterial growth we saw in caspase-8-/- BMDMs. This research identifies and explores caspase-8 as a key regulator of C. burnetii infection, opening novel therapeutic doors.

Attenuation of acrylamide-induced neurotoxicity by supplementation of sitagliptin in Wistar rats

Objectives

Acrylamide (ACR) induces neurotoxicity in humans and animals through different mechanisms. Sitagliptin is a type-2 diabetes medication with neuroprotective properties. The effects of sitagliptin against neurotoxicity stimulated by ACR were examined.

Materials and Methods

Male Wistar rats were classified as follows: 1. Control (normal saline, 11 days, IP), 2. ACR (50 mg/kg, 11 days, IP), 3. ACR (11 days, days 11-20 normal saline), 4-7. ACR+sitagliptin (5, 10, 20, and 40 mg/kg, 11 days, IP), 8. ACR+sitagliptin (10 mg/kg, days 6-11), 9. ACR+sitagliptin (10 mg/kg, days 6-20), 10. Sitagliptin (40 mg/kg, 11 days), 11. ACR+vitamin E (200 mg/kg, IP). Finally, the gait score was evaluated. Reduced glutathione (GSH) and malondialdehyde (MDA) levels were measured in cortex tissue. Also, IL-1β, TNF-α, and caspase-3 levels were assessed in the cortex by western blotting.

Results

ACR caused movement disorders, triggered oxidative stress, and raised TNF-α, IL-1β, and caspase-3 cleaved levels. Supplementation of sitagliptin (10 mg/kg) along with ACR, in 3 protocols, reduced gait disorders compared to the ACR group. Receiving sitagliptin in all doses plus ACR and injection of sitagliptin (10 mg/kg) from days 6 to11 reduced the MDA level of cortex tissue. Sitagliptin (all doses) plus ACR increased the GSH level of the cortex tissue. Sitagliptin (10 mg/kg) with ACR dropped the amounts of TNF-α and caspase-3 cleaved proteins in cortex tissue but did not affect the IL-1β level.

Conclusion

Sitagliptin disclosed preventive and therapeutic effects on ACR neurotoxicity. Sitagliptin possesses antioxidant, anti-inflammatory, and anti-apoptotic properties and inhibits CR neurotoxicity in rats.

Preventive and therapeutic effects of azithromycin on acrylamide-induced neurotoxicity in rats

BACKGROUND

Acrylamide (ACR) can induce neurotoxicity through different pathways, including oxidative stress and apoptosis. Azithromycin is well-known for its antioxidant and anti-apoptotic properties.

OBJECTIVE

To evaluate the potential neuroprotective effect of azithromycin in an in vivo model of ACR-induced neurotoxicity, by investigating its impact on oxidative stress and apoptosis pathways.

METHODS

Male rats were divided into eleven groups at random (n = 6). 1:control (vehicle), 2:ACR (50 mg/kg, 11 days, I.P.), 3-7:ACR+ azithromycin (3.1, 6.25, 12.5, 25, 50 mg/kg, 11 days, I.P.), 8-9:ACR+ azithromycin (3.1, 6.25 mg/kg, from day 3-11), 10: ACR+ vitamin E (200 mg/kg, every other day, I.P.), 11. Azithromycin (50 mg/kg). Following the treatment period, a gait score examination was performed, and malondialdehyde (MDA), glutathione (GSH), Bcl-2-associated X protein (Bax)/B-cell lymphoma 2 (Bcl-2) ratio and caspase-3 levels in the cerebral cortex were measured.

RESULTS

Gait abnormality, a drop in GSH, and an increase in lipid peroxidation, Bax/Bcl-2 ratio, and caspase-3 levels were all significantly triggered by ACR in the cerebral cortex versus the control group. Azithromycin 3.1 and 6.25 mg/kg with ACR and azithromycin 6.25 mg/kg with ACR from day 3-11 ameliorated movement disorders caused by ACR. Azithromycin in all doses and both protocols along with ACR decreased the MDA level. Azithromycin (3.1, 6.25 mg/kg) along with ACR in both protocols increased the level of GSH, reduced the Bax/Bcl-2 ratio and caspase-3 amounts in the brain tissue versus the ACR group.

CONCLUSIONS

Administration of azithromycin had both preventive and therapeutic effects on ACR-induced neurotoxicity through its antioxidant and antiapoptotic properties.

Pyroptosis in microbial infectious diseases

Pyroptosis is a gasdermins-mediated programmed cell death that plays an essential role in immune regulation, and its role in autoimmune disease and cancer has been studied extensively. Increasing evidence shows that various microbial infections can lead to pyroptosis, associated with the occurrence and development of microbial infectious diseases. This study reviews the recent advances in pyroptosis in microbial infection, including bacterial, viral, and fungal infections. We also explore potential therapeutic strategies for treating microbial infection-related diseases by targeting pyroptosis.

Caspases in Alzheimer's Disease: Mechanism of Activation, Role, and Potential Treatment

With the aging of the population, treatment of conditions emerging in old age, such as neurodegenerative disorders, has become a major medical challenge. Of these, Alzheimer's disease, leading to cognitive dysfunction, is of particular interest. Neuronal loss plays an important role in the pathophysiology of this condition, and over the years, a great effort has been made to determine the role of various factors in this process. Unfortunately, until now, the exact pathomechanism of this condition remains unknown. However, the most popular theories associate AD with abnormalities in the Tau and β-amyloid (Aβ) proteins, which lead to their deposition and result in neuronal death. Neurons, like all cells, die in a variety of ways, among which pyroptosis, apoptosis, and necroptosis are associated with the activation of various caspases. It is worth mentioning that Tau and Aβ proteins are considered to be one of the caspase activators, leading to cell death. Moreover, the protease activity of caspases influences both of the previously mentioned proteins, Tau and Aβ, converting them into more toxic derivatives. Due to the variety of ways caspases impact the development of AD, drugs targeting caspases could potentially be useful in the treatment of this condition. Therefore, there is a constant need to search for novel caspase inhibitors and evaluate them in preclinical and clinical trials.

Spectroscopic imaging to assess biochemical alterations in liver carcinoma cells exposed to transition metals

Despite the invaluable role of transition metals in every living organism, it should be remembered that failure to maintain the proper balance and exceed the appropriate dose may have the opposite effect. In the era of such a popular and propagated need for supplementation in the media, one should bear in mind the harmful effects that may become the result of improper and excessive intake of transition metals. This article establishes the feasibility of Raman (RS) and Fourier-transform infrared (FT-IR) spectroscopic imaging at the single-cell level to investigate the cellular response to various transition metals. These two non-destructive and perfectly complementary methods allow for in-depth monitoring of changes taking place within the cell under the influence of the agent used. HepG2 liver carcinoma cells were exposed to chromium, iron, cobalt, molybdenum, and nickel at 1 and 2 mM concentrations. Spectroscopic results were further supported by biological evaluation of selected caspases concentration. The caspase- 3, 6, 8, 9, and 12 concentrations were determined with the use of the enzyme-linked immunosorbent assay (ELISA) method. This study shows the induction of apoptosis in the intrinsic pathway by all studied transition metals. Cellular metabolism alterations are induced by mitochondrial metabolism changes and endoplasmic reticulum (ER) metabolism variations. Moreover, nickel induces not only the intrinsic pathway of apoptosis but also the extrinsic pathway of this process.

Apoptosis is mediated by FeHV-1 through the intrinsic pathway and interacts with the autophagic process

BACKGROUND

Although FeHV-1 is a primary feline pathogen, little is known about its interactions with host cells. Its relationship with several cellular pathways has recently been described, whereas its interplay with the apoptotic process, unlike other herpesviruses, has not yet been clarified. The aim of this work was to evaluate whether FeHV-1 induces apoptosis in its permissive cells, as well as the pathway involved and the effects of induction and inhibition of apoptosis on viral replication.

METHODS

Monolayers of CRFK cells were infected at different times with different viral doses. A cytofluorimetric approach allowed the quantification of cells in early and late apoptosis. All infections and related controls were also subjected to Western blot analysis to assess the expression of apoptotic markers (caspase 3-8-9, Bcl-2, Bcl-xL, NF-κB). An inhibitor (Z-VAD-FMK) and an inducer (ionomycin) were used to evaluate the role of apoptosis in viral replication. Finally, the expression of autophagy markers during the apoptosis inhibition/induction and the expression of apoptosis markers during autophagy inhibition/induction were evaluated to highlight any crosstalk between the two pathways.

RESULTS

FeHV-1 triggered apoptosis in a time- and dose-dependent manner. Caspase 3 cleavage was evident 48 h after infection, indicating the completeness of the process at this stage. While caspase 8 was not involved, caspase 9 cleavage started 24 h post-infection. The expression of other mitochondrial damage markers also changed, suggesting that apoptosis was induced via the intrinsic pathway. NF- κB was up-regulated at 12 h, followed by a gradual decrease in levels up to 72 h. The effects of apoptosis inhibitors and inducers on viral replication and autophagy were also investigated. Inhibition of caspases resulted in an increase in viral glycoprotein expression, higher titers, and enhanced autophagy, whereas induction of apoptosis resulted in a decrease in viral protein expression, lower viral titer, and attenuated autophagy. On the other hand, the induction of autophagy reduced the cleavage of caspase 3.

CONCLUSIONS

In this study, we established how FeHV-1 induces the apoptotic process, contributing to the understanding of the relationship between FeHV-1 and this pathway.

How does caspases regulation play role in cell decisions? apoptosis and beyond

Caspases are a family of cysteine proteases, and the key factors behind the cellular events which occur during apoptosis and inflammation. However, increasing evidence shows the non-conventional pro-survival action of apoptotic caspases in crucial processes. These cellular events include cell proliferation, differentiation, and migration, which may appear in the form of metastasis, and chemotherapy resistance in cancerous situations. Therefore, there should be a precise and strict control of caspases activity, perhaps through maintaining the threshold below the required levels for apoptosis. Thus, understanding the regulators of caspase activities that render apoptotic caspases as non-apoptotic is of paramount importance both mechanistically and clinically. Furthermore, the functions of apoptotic caspases are affected by numerous post-translational modifications. In the present mini-review, we highlight the various mechanisms that directly impact caspases with respect to their anti- or non-apoptotic functions. In this regard, post-translational modifications (PTMs), isoforms, subcellular localization, transient activity, substrate availability, substrate selection, and interaction-mediated regulations are discussed.

Innate immune inflammatory cell death: PANoptosis and PANoptosomes in host defense and disease

Regulated cell death (RCD) triggered by innate immune activation is an important strategy for host survival during pathogen invasion and perturbations of cellular homeostasis. There are two main categories of RCD, including nonlytic and lytic pathways. Apoptosis is the most well-characterized nonlytic RCD, and the inflammatory pyroptosis and necroptosis pathways are among the best known lytic forms. While these were historically viewed as independent RCD pathways, extensive evidence of cross-talk among their molecular components created a knowledge gap in our mechanistic understanding of RCD and innate immune pathway components, which led to the identification of PANoptosis. PANoptosis is a unique innate immune inflammatory RCD pathway that is regulated by PANoptosome complexes upon sensing pathogens, pathogen-associated molecular patterns (PAMPs), damage-associated molecular patterns (DAMPs) or the cytokines produced downstream. Cytosolic innate immune sensors and regulators, such as ZBP1, AIM2 and RIPK1, promote the assembly of PANoptosomes to drive PANoptosis. In this review, we discuss the molecular components of the known PANoptosomes and highlight the mechanisms of PANoptosome assembly, activation and regulation identified to date. We also discuss how PANoptosomes and mutations in PANoptosome components are linked to diseases. Given the impact of RCD, and PANoptosis specifically, across the disease spectrum, improved understanding of PANoptosomes and their regulation will be critical for identifying new therapeutic targets and strategies.

BAK contributes critically to necrosis and infarct generation during reperfused myocardial infarction

At least seven cell death programs are activated during myocardial infarction (MI), but which are most important in causing heart damage is not understood. Two of these programs are mitochondrial-dependent necrosis and apoptosis. The canonical function of the pro-cell death BCL-2 family proteins BAX and BAK is to mediate permeabilization of the outer mitochondrial membrane during apoptosis allowing apoptogen release. BAX has also been shown to sensitize cells to mitochondrial-dependent necrosis, although the underlying mechanisms remain ill-defined. Genetic deletion of Bax or both Bax and Bak in mice reduces infarct size following reperfused myocardial infarction (MI/R), but the contribution of BAK itself to cardiomyocyte apoptosis and necrosis and infarction has not been investigated. In this study, we use Bak-deficient mice and isolated adult cardiomyocytes to delineate the role of BAK in the pathogenesis of infarct generation and post-infarct remodeling during MI/R and non-reperfused MI. Generalized homozygous deletion of Bak reduced infarct size ∼50% in MI/R in vivo, which was attributable primarily to decreases in necrosis. Protection from necrosis was also observed in BAK-deficient isolated cardiomyocytes suggesting that the cardioprotection from BAK loss in vivo is at least partially cardiomyocyte-autonomous. Interestingly, heterozygous Bak deletion, in which the heart still retains ∼28% of wild type BAK levels, reduced infarct size to a similar extent as complete BAK absence. In contrast to MI/R, homozygous Bak deletion did not attenuate acute infarct size or long-term scar size, post-infarct remodeling, cardiac dysfunction, or mortality in non-reperfused MI. We conclude that BAK contributes significantly to cardiomyocyte necrosis and infarct generation during MI/R, while its absence does not appear to impact the pathogenesis of non-reperfused MI. These observations suggest BAK may be a therapeutic target for MI/R and that even partial pharmacological antagonism may provide benefit.

Delineating involvement of MAPK/NF-κB pathway during mitigation of permethrin-induced oxidative damage in fish gills by melatonin

Present study evaluated involvement of transcription factors during permethrin-induced gill toxicity and its amelioration by melatonin. First, adult Notoptertus notopterus females were exposed to permethrin at nominal concentrations [C: 0.0, P1: 0.34, P2: 0.68 µg/L] for 15 days followed by intramuscular melatonin administration (100 µg/kg body weight) for 7 days. Gill MDA, XO, LDH levels increased, while Na+-K+-ATPase, SDH, cytochrome C oxidase levels decreased with increasing permethrin concentrations. Glutathione, SOD, CAT, GST, GRd levels increased in P1 than C, but decreased in P2 than P1, C. Melatonin administration restored gill enzyme and antioxidant levels in P1, P2. Next, isolated gill tissues were exposed to permethrin at 25, 50 µM doses along with melatonin administration (100 μg/mL). NF-κB, NRF2, Keap1, ERK, Akt, caspases protein expression changed significantly during permethrin-induced gill damage. Melatonin administration amended permethrin-induced molecular imbalance through modulation of caspase proteins and MAPK/NF-κB signal transduction pathway via melatonin receptor 1.

Legionella pneumophila exploits the endo-lysosomal network for phagosome biogenesis by co-opting SUMOylated Rab7

L. pneumophila strains harboring wild-type rpsL such as Lp02rpsLWT cannot replicate in mouse bone marrow-derived macrophages (BMDMs) due to induction of extensive lysosome damage and apoptosis. The mechanism of this unique infection-induced cell death remains unknown. Using a genome-wide CRISPR/Cas9 screening, we identified Hmg20a and Nol9 as host factors important for restricting strain Lp02rpsLWT in BMDMs. Depletion of Hmg20a protects macrophages from infection-induced lysosomal damage and apoptosis, allowing productive bacterial replication. The restriction imposed by Hmg20a was mediated by repressing the expression of several endo-lysosomal proteins, including the small GTPase Rab7. We found that SUMOylated Rab7 is recruited to the bacterial phagosome via SulF, a Dot/Icm effector that harbors a SUMO-interacting motif (SIM). Moreover, overexpression of Rab7 rescues intracellular growth of strain Lp02rpsLWT in BMDMs. Our results establish that L. pneumophila exploits the lysosomal network for the biogenesis of its phagosome in BMDMs.

Evaluating the effect of alpha-mangostin on neural toxicity induced by acrylamide in rats

Acrylamide (ACR) is known to be a neurotoxic agent for humans and animals that has many applications in industry. Alpha-mangostin is a natural antioxidant that is extracted from mangosteen. This study aimed to investigate the protective effects of alpha-mangostin against ACR-induced neurotoxicity in rats and PC12 cells. Male Wistar rats were used in this investigation for 11 days, divided into 8 groups: 1. control group (normal saline), 2. ACR (50 mg/kg, i.p.), 3-6. ACR + alpha-mangostin (20, 40, 60 mg/kg, p.o.), 7. ACR + vitamin E (200 mg/kg, i.p., every other day) 8. alpha-mangostin (60 mg/kg, p.o.). On the last day of the study, the behavioral test was performed. The amounts of malondialdehyde (MDA) and glutathione (GSH) were measured. Also, the effects of ACR and alpha-mangostin were assessed by MTT assay on PC12 cells, and the levels of reactive oxygen species (ROS), B-cell lymphoma 2 (Bcl-2), Bcl-2-associated X protein (Bax), and cleaved caspase-3 proteins were measured by Western blotting. Receiving ACR caused motor disorders in animals, increased MDA, and decreased GSH levels of the cerebral cortex versus the control group. Alpha-mangostin (60 mg/kg) reduced ACR motility disorders, MDA amounts, and augmented GSH levels. The concurrent administration of vitamin E and ACR reduced gait score, MDA level, and amplified GSH content versus the ACR group. In the in vitro section, alpha-mangostin (1.25 µM, 24 h) increased cell viability, attenuated ROS, Bax/Bcl-2, and cleaved caspase-3 levels versus the ACR group. Alpha-mangostin reduced the toxicity of ACR by inhibiting oxidative stress and apoptosis. Therefore, it could be a promising compound for managing ACR-induced neurotoxicity.

The effects of non-functionalized polystyrene nanoparticles of different diameters on the induction of apoptosis and mTOR level in human peripheral blood mononuclear cells

Particles of various types of plastics, including polystyrene nanoparticles (PS-NPs), have been determined in human blood, placenta, and lungs. These findings suggest a potential detrimental effect of PS-NPs on bloodstream cells. The purpose of this study was to assess the mechanism underlying PS-NPs-induced apoptosis in human peripheral blood mononuclear cells (PBMCs). Non-functionalized PS-NPs of three diameters: 29 nm, 44 nm, and 72 nm were studied used in this research. PBMCs were isolated from human leukocyte-platelet buffy coat and treated with PS-NPs at concentrations ranging from 0.001 to 200 μg/mL for 24 h. Apoptotic mechanism of action was evaluated by determining the level of cytosolic calcium ions, as well as mitochondrial transmembrane potential, and ATP levels. Furthermore, detection of caspase-8, -9, and -3 activation, as well as mTOR level was conducted. The presence of apoptotic PBMCs was confirmed by the method of double staining of the cells with propidium iodide and FITC-conjugated Annexin V. We found that all tested NPs increased calcium ion and depleted mitochondrial transmembrane potential levels. The tested NPs also activated caspase-9 and caspase-3, and the smallest NPs of 29 nm of diameter also activated caspase-8. The results clearly showed that apoptotic changes and an increase of mTOR level depended on the size of the tested NPs, while the smallest particles caused the greatest alterations. PS-NPs of 26 nm of diameter activated the extrinsic pathway (increased caspase-8 activity), as well as intrinsic (mitochondrial) pathway (increased caspase-9 activity, raised calcium ion level, and decreased transmembrane mitochondrial potential) of apoptosis. All PS-NPs increased mTOR level at the concentrations smaller than those that induced apoptosis and its level returned to control value when the process of apoptosis escalated.

Nyctanthes arbor-tristis alkaloids activates p53 independent cell death receptor and necroptosis pathways in HepG2 cells

Nyctanthes arbor-tristis is a traditional medicinal plant with potential anti-cancer properties. In this study, crude and alkaloid extracts were prepared from different parts of the plant, and their cytotoxicity was evaluated on four different cancer cell lines. The alkaloid extracts from the leaf and fruit showed promising results, with the HepG2 cell line exhibiting significant cytotoxicity. The promising extracts were further studied for their apoptotic potential using various methods, including DNA fragmentation, TUNEL, Caspase-3 activity, Giemsa, and Hoechst staining. Our results indicated that the fruit extract had the highest apoptotic potential, with clear nuclear condensation, fragmentation, and apoptotic bodies observed. We also investigated the alteration of the Bax/Bcl-2 ratio both at the mRNA and protein levels. Our results showed a significant upregulation of the Bax gene and downregulation of the Bcl-2 gene for the fruit alkaloid extract. This indicates that the phenomenon of cell death expression might be following a p53-independent extrinsic pathway and Bax-activated caspase-independent AIF-mediated necroptosis in the HepG2 cancer cell line. Overall, our findings suggest that Nyctanthes arbor-tristis has potential as a therapeutic option for cancer treatment. The alkaloid extracts from the leaf and fruit may hold promise as a source of bioactive compounds for further development into anti-cancer agents. Further studies are needed to explore the underlying mechanisms of their cytotoxic and apoptotic effects and to evaluate their safety and efficacy in animal models and clinical trials.

Novel insights into the biomolecular mechanism of action of 4'-geranyloxyferulic acid, a colon cancer chemopreventive agent

In this manuscript the biomolecular mechanism of action of the natural colon cancer chemopreventive agent 4'-geranyloxyferulic acid in cultured Caco-2 cells has been investigated. It was first demonstrated how the application of this phytochemical led to a time- and dose-dependent decrease of cell viability and in parallel to a massive generation of reactive oxygen species and induction of caspases 3 and 9, finally providing apoptosis. This event is accompanied by deep modifications in key pro-apoptotic targets like CD95, DR4 and 5, cytochrome c, Apaf-1, Bcl-2, and Bax. Such effects can explain the large apoptosis recorded in Caco-2 cells treated with 4'-geranyloxyferulic acid.

Gamma irradiation induces a pro-apoptotic state in longer stored platelets, without progressing to an overt apoptosis by day 7 of storage

BACKGROUND

Although gamma-irradiation to platelet products is a standard method to prevent the risk of TA-GVHD in vulnerable recipients, it induces some proteomic and redox changes, of which irradiation-induced ROS increments may potentiate platelet mitochondrial dysfunction. However, whether these changes cause platelet apoptosis, or affect their viability during storage, is the main subject of this study.

METHODS

PLT-rich plasma PC was split into two bags, one kept as control while other was subjected to gamma-irradiation. Within 7-days storage, cytosolic and mitochondrial levels of cytochrome c and pro-apoptotic molecules of Bak and Bax were evaluated by western-blotting. Intraplatelet active caspase (using FAM-DEVD-FMK) and PS-exposure were detected by flowcytometry. Caspase activity in platelet lysate was also confirmed by immunofluorescence detection of Caspase-3/7 Substrate N-Ac-DEVD-N'-MC-R110 while platelet viability was evaluated with MTT assays.

RESULTS

Cytosolic cytochrome c gradually increased while its mitochondrial content steadily declined during 7 days of storage. In a contrary trend, reverse patterns were observed for Bak and Bax expressions. Gamma-irradiated platelets showed higher release of mitochondrial cytochrome c that reflected by higher cytosolic cytochrome c levels on day 7 of storage. Concurrently mitochondrial pro-apoptotic Bak and Bax proteins increased on day 7 in irradiated products. However, gamma-irradiation didn't significantly increase caspase activity or PS-exposure, nor did it decrease platelet viability.

CONCLUSION

Here, consistent with studies on "gamma-irradiation-induced oxidative stress", we showed that gamma-ray also increases platelet pro-apoptotic signals during storage, although not strongly enough to affect platelet viability by overt apoptosis induction. Conclusively, whether supplementing ROS scavengers or antioxidants to irradiated platelets can improve their quality during storage may be of interest for future research.

Rosmarinic acid decreases viability, inhibits migration and modulates expression of apoptosis-related CASP8/CASP3/NLRP3 genes in human metastatic melanoma cells

Cutaneous melanoma is the most aggressive type of skin cancer; it is difficult to treat, and has been highlighted in recent years due to increasing numbers of cases worldwide. The use of antitumoral therapeutics for this neoplasm has been associated with severe side effects, low quality of life, and resistance. We aimed in this study to explore the effect of the phenolic compound rosmarinic acid (RA) on human metastatic melanoma cells. SK-MEL-28 melanoma cells were treated for 24 h with different concentrations of RA. In parallel, peripheral blood mononuclear cells (PBMCs) also were treated with RA under the same experimental conditions to verify the cytotoxic effect on non-tumoral cells. Then, we assessed cell viability and migration, levels of intracellular and extracellular reactive oxygen species (ROS), as well as nitric oxide (NOx), non-protein thiols (NPSH), and total thiol (PSH). Gene expression of the caspase 8, caspase 3 and NLRP3 inflammasome was evaluated by RT-qPCR. The enzymatic activity of the caspase 3 protein was assessed by a sensitive fluorescent assay. Fluorescence microscopy was employed to corroborate the effects of RA on melanoma cell viability, mitochondria transmembrane potential and apoptotic bodies formation. We found that RA potently reduces melanoma cell viability and migration after 24 h of treatment. On the other hand, it has no cytotoxic effect on non-tumoral cells. The fluorescence micrographics indicated that RA reduces transmembrane potential of mitochondria and induces apoptotic bodies formation. Moreover, RA significantly decreases intracellular and extracellular ROS levels, and increases the antioxidant defenders NPSH and PSH. A remarkable feature found in our study was that RA strongly upregulates the gene expression of the caspase 8 and caspase 3, and downregulates NLRP3 inflammasome expression. Similar to gene expression, RA greatly increases the enzymatic activity of caspase 3 protein. Taken together, we have shown for the first time that RA reduces cell viability and migration of human metastatic melanoma cells, in addition to modulates apoptosis-related gene expression. We suggest that RA may have the potential to be used in a therapeutic perspective, particularly for CM cell treatment.

Higher replication potential of West Nile virus governs apoptosis induction in human neuroblastoma cells

The extent of neuronal cell damage caused by West Nile virus (WNV) infection governs the disease severity ranging from mild, febrile illness to fatal encephalitis. Availability of naturally occurring genetic variants is helpful to study viral factors governing differential pathogenesis. During WNV infection, apoptosis serves as a virulence determinant positively contributing to viral pathogenesis. We investigated the levels of apoptosis induced by a low neurovirulent WNV lineage 5 strain 804994 and a high neurovirulent lineage 1 strain 68856 in human neuroblastoma cells, IMR-32. Our investigations clearly show the correlation between higher multiplication capacities of 68856 with higher levels of cytopathology induced by apoptosis. We observed activation of both the extrinsic and intrinsic apoptotic pathways during WNV infection. Infection with higher neurovirulent strain resulted in higher upregulation of pro-apoptotic proteins including death receptors (DR), adaptor protein, BH3-only regulatory proteins and higher cleavage of initiator caspases of both pathways. These results suggest that the virulence of a WNV strain may correlate with its higher replication fitness and ability to cause more cellular damage.

Allosteric Tuning of Caspase-7: Establishing the Nexus of Structure and Catalytic Power

Caspase-7 (C7), a cysteine protease involved in apoptosis, is a valuable drug target for its role in human diseases (e.g. Parkinson's, Alzheimer's, sepsis). The C7 allosteric site has great potential for small molecule targeting, but numerous drug discovery efforts have identified precious few allosteric inhibitors. Here we present the first selective, drug-like inhibitor of C7 along with several other improved inhibitors based on our previous fragment hit. We also provide a rational basis for the impact of allosteric binding on the C7 catalytic cycle using an integrated approach including X-ray crystallography, stopped-flow kinetics, and molecular dynamics simulations. Our findings suggest allosteric binding disrupts C7 pre-acylation via neutralization of the catalytic dyad, displacement of substrate from the oxyanion hole, and altered dynamics of substrate binding loops. This work advances drug targeting efforts and bolsters our understanding of allosteric structure activity relationships (ASARs).

Anticancer Effect of Fluorouracil and Gum-Based Cerium Oxide Nanoparticles on Human Malignant Colon Carcinoma Cell Line (Caco2)

OBJECTIVE

We investigated whether co-incubation of 5-FU and gum-based cerium oxide nanoparticles (CeO₂ NPs) would improve half-maximal inhibitory concentration (IC₅₀) and apoptosis in the Caco-2 cancer cell line Materials and Methods: In this experimental study, we synthesized Ceo-2-XG by the nano perception method. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), dynamic light scattering (DLS) and vibrating sample magnetometer (VSM) techniques were employed to characterize the synthesized nanoparticles. The Caco-2 cancer cells were cultured and treated with Ceo-2- XG and 5-FU. Cytotoxicity analysis was carried out using MTT assay on Caco-2 cancer cells. CXCR1, CXCR2, CXCL8, BAX, BCL-2, P53, CASPASE-3, CASPASE-8 and CASPASE-9 gene expression changes were assessed by quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR). The Caco-2 cancer cell mortality mechanism was analyzed using Annexin V-FITC/PI flow cytometry. Using the inverted microscope morphology changes of the Caco-2 cancer cells was observed.

RESULTS

With a sample size of roughly 11 nm, TEM analysis revealed spherical structures. Interestingly, after 72 hours, 400 μg/ml nanoparticles significantly lowered the ₅₀ of 5-FU from 101 to 71 μg/ml (P<000.1). Furthermore, qRT-PCR analysis showed that BCL-2, CXCR1, CXCR2 and CXCR8 expressions were significantly decreased in the 5-FU and Ceo-2-XG nanoparticles co-incubated group, compared to the 5-FU alone (P<0.001). Notably, gene expressions of BAX, P53, CASPASE-3, CASPASE-8 and CASPASE-9 were significantly higher in the 5-FU and Ceo- 2-XG nanoparticles co-incubated group, compared to the 5-FU alone (P<0.001). The findings revealed that dead cells owing to apoptosis were more than two times higher in 5-FU and Ceo-2-XG nanoparticles cancer cells than in 5-FU alone treated cancer cells.

CONCLUSION

Co-incubation of 5-FU and Ceo-2-XG nanoparticles significantly increased apoptosis in the Caco-2 cancer cells. The antiproliferative activity of co-incubated 5-FU and Ceo-2-XG nanoparticles on Caco-2 cancer cells was substantially higher than that of 5-FU alone.

LACTB induces cancer cell death through the activation of the intrinsic caspase-independent pathway in breast cancer

BACKGROUND

LACTB was recently identified as a mitochondrial tumour suppressor that negatively affects cancer cell proliferation by inducing cell death and/or differentiation, depending on the cell type and tissue. However, the detailed mechanism underlying the LACTB-induced cancer cell death is largely unknown.

METHODS

We used cell-based, either in 2D or 3D conditions, and in vivo experiments to understand the LACTB mechanisms. In this regard, protein array followed by an enrichment analysis, cell proliferation assays using different compounds, western blot analysis, flow cytometry and immunofluorescence were performed. Differences between quantitative variables following normal distribution were valuated using Student t test for paired or no-paired samples according to the experiment. For in vivo experiments differences in tumour growth were analyzed by 2-way ANOVA.

RESULTS

We show, that LACTB expression leads to cell cycle arrest in G1 phase and increase of DNA oxidation that leads to activation of intrinsic caspase-independent cell death pathway. This is achieved by an increase of mitochondrial reactive oxygen species since early time points of LACTB induction.

CONCLUSION

Our work provides a deeper mechanistic insight into LACTB-mediated cancer-cell death and shows the dynamics of the cellular responses a particular tumor suppressive stimulus might evoke under different genetic landscapes.

Pyroptosis in Antiviral Immunity

Pyroptosis is a form of lytic, programmed cell death that functions as an innate immune effector mechanism to facilitate host defense against pathogenic microorganisms, including viruses. This type of proinflammatory cell death is orchestrated by proteolytic activation of human or mouse caspase-1, mouse caspase-11 and human caspase-4 and caspase-5 in response to infectious and inflammatory stimuli. Induction of pyroptosis requires either a canonical inflammasome responsible for caspase-1 activation or a noncanonical complex composed of caspase-11 in mice or caspase-4 or caspase-5 in humans. Recent studies have identified the pore-forming protein gasdermin D, a substrate of these inflammatory caspases, as an executioner of pyroptosis. The membrane pores formed by gasdermin D facilitate release of proinflammatory cytokines IL-1β and IL-18 and consequent biologic effects of these cytokines together with other released components. Pyroptosis, like other forms of programmed cell death, helps eliminate infected cells and thereby restricts the replicative niche, undermining survival and proliferation of intracellular pathogens. This includes viruses as well as bacteria, where ample evidence supports a critical role for inflammasome effector functions and cell death in host defense. Viruses have evolved their own mechanisms to modulate inflammasome signaling and pyroptosis. Here, we review the current literature regarding the role of pyroptosis in antiviral immune responses.

Interlacing the relevance of caspase activation in the onset and progression of Alzheimer's disease

Caspases, a family of cysteine proteases is a renowned regulator of apoptosis. Members of this family are responsible for the proteolytic dismantling of numerous cellular structures. Apart from apoptosis, caspases remarkably contribute to a diverse range of molecular processes. Being the imperative members of several cellular cascades their abnormal activation/deactivation has severe implications and also leads to various diseased conditions. Similar aberrant activation of caspases is one of the several causes of neuropathologies associated with Alzheimer's disease (AD), a form of dementia severely affecting neuropsychiatric and cognitive functions. Emerging studies are providing deeper insights into the mechanisms of caspase action in the progression of AD. Current article is an attempt to review these studies and present the action mechanisms of different mammalian caspases in the advancement of AD associated neuropathologies.

Research progress on pyroptosis-mediated immune-inflammatory response in ischemic stroke and the role of natural plant components as regulator of pyroptosis: A review

Ischemic stroke (IS) is one of the leading causes of death and disability. Its pathogenesis is not completely clear, and inflammatory cascade is one of its main pathological processes. The current clinical practice of IS is to restore the blood supply to the ischemic area after IS as soon as possible through thrombolytic therapy to protect the vitality and function of neurons. However, blood reperfusion further accelerates ischemic damage and cause ischemia-reperfusion injury. The pathological process of cerebral ischemia-reperfusion injury involves multiple mechanisms, and the exact mechanism has not been fully elucidated. Pyroptosis, a newly discovered form of inflammatory programmed cell death, plays an important role in the initiation and progression of inflammation. It is a pro-inflammatory programmed death mediated by caspase Caspase-1/4/5/11, which can lead to cell swelling and rupture, release inflammatory factors IL-1β and IL-18, and induce an inflammatory cascade. Recent studies have shown that pyroptosis and its mediated inflammatory response are important factors in aggravating ischemic brain injury, and inhibition of pyroptosis may alleviate the ischemic brain injury. Furthermore, studies have found that natural plant components may have a regulatory effect on pyroptosis. Therefore, this review not only summarizes the molecular mechanism of pyroptosis and its role in ischemic stroke, but also the role of natural plant components as regulator of pyroptosis, in order to provide reference information on pyroptosis for the treatment of IS in the future.

Photosensitization of human skin fibroblasts by vemurafenib promotes pleiotropic effects on membrane-enclosed organelles and apoptosis

Vemurafenib (VB), a BRAF inhibitor and a first-line treatment for unresectable or metastatic melanoma, is strongly phototoxic towards normal skin cells. Herein, we show that in cultured HS 68 human diploid dermal fibroblasts, low concentrations of VB suffice to promote photosensitization to low doses of UVA (∼ 5 J/cm²), as evidenced by a significant decrease in cell viability. In contrast to data obtained in chemico our results support a role for ROS (reactive oxygen species). Indeed, peroxidation of cellular lipids was observed which could be alleviated by the lipophilic antioxidant BHT (2,6-di-tert-butyl-4-methylphenol). Using in vivo confocal laser scanning microscopy and vital fluorescent probes it was shown at the single cell level that the plasma membrane and lipid-rich organelles, namely mitochondria, endoplasmic reticulum, and lysosomes, as well as actin filaments, were severely damaged by the UVA-induced VB-photosensitization. Finally, we showed that mitochondrial impairment was concurrent with caspase 3/7 activation and cell death by apoptosis.

Upconversion nanoparticles as an immunocomplexing agent for selective detection of caspases via sandwich-like supracomplexes

In this study, a nanoparticle-based sandwich-like immunoassay was designed in dispersion medium to precisely detect apoptosis over caspase antibodies in order to overcome the disadvantages of traditional apoptosis determination methods such as high cost, large sampling requirement, and appropriate laboratory and equipment conditions. For this purpose, a complementary particulate system including magnetic (MNPs) and upconversion silica (UC-SiNPs) nanoparticles while immobilizing antibodies (primary antibody to MNPs, secondary antibody to UC-SiNPs) were synthesized and characterized. Optimization and selectivity studies of the complex formed by primary antibody immobilized MNPs with standard caspase proteins were examined by the HPLC system. Within the scope of optimization studies, protein concentrations, optimal duration, and temperature parameters were evaluated. Optimal conditions were determined for pH, initial concentration, time, and temperature as 7.4, 5.6 μg/mL, 45 min, and room temperature, respectively. Furthermore, the adsorption of competitive proteins was investigated in selectivity studies as well. Moreover, the primary antibody immobilized MNPs were treated with standard caspase proteins under optimal conditions; subsequently, they were interacted with secondary antibody immobilized UC-SiNPs to demonstrate the supracomplex formation meanwhile zeta potential/size measurements and fluorescence emission spectrometry analyses were performed. As a result of these analyses, it was observed that the sandwich-like supracomplexes were successfully formed that significantly varied upconversion emission intensities of UC-SiNPs in dependence on the amounts of caspase proteins. Because this approach enabled a quantitative result, the nanoparticle-based sandwich-like immunoassay should be classified as an easy-to-handled, fast, and promising alternative to benchmark apoptosis assays.

Influence of furan and lead co-exposure at environmentally relevant concentrations on neurobehavioral performance, redox-regulatory system and apoptotic responses in rats

Furan and lead are contaminants of global concern due to the potential public health threat associated with their exposure. Herein, the neurobehavioral performance, biochemical effects and histological alterations associated with co-exposure to furan (8 mg/kg) and lead acetate at low, environmentally realistic concentrations (1, 10 and 100 µg PbAc/L) for 28 uninterrupted days were investigated in rats. The results demonstrated that locomotor, motor and exploratory deficits associated with separate exposure to furan and lead was exacerbated in the co-exposed rats. Furan and lead co-exposure aggravated the marked decrease in acetylcholinesterase activity and antioxidant status, elevation in oxido-inflammatory stress indices and caspases activation in the cerebrum and cerebellum of exposed rats compared with control. Furan and lead co-exposure worsened neuronal degeneration as verified by histomorphometry and histochemical staining. Collectively, furan and lead acts together to exacerbate neurotoxicity via inhibition of cholinergic system, induction of oxido-inflammatory stress and caspases activation in rats.

Gold(III) Complexes with Phenanthroline-derivatives Ligands Induce Apoptosis in Human Colorectal and Breast Cancer Cell Lines

Due to their promising effects, gold(III) complexes recently drew increasing attention in the design of new metal-based anticancer therapeutics. Two gold(III) complexes, square-planar [Au(DPP)Cl2]+ - Complex 1 and distorted square-pyramidal [Au(DMP)Cl3] - Complex 2 (where DPP=4,7-diphenyl-1,10-phenanthroline and DMP=2,9-dimethyl-1,10-phenanthroline) were previously synthetized, described and approved as complexes with pronounced cytotoxic effects on colorectal HCT-116 and breast MDA-MB-231 cancer cells. This study investigated the type of cell death by AO/EB double staining, and identification of possible targets responsible for their cytotoxicity, monitored by immunofluorescence and qPCR methods. Both complexes induced apoptosis in all applied concentrations. In the HCT-116 cells apoptosis was activated by external apoptotic pathway, via increase of Fas receptor protein expression and Caspase 8 gene expression. Also, the mitochondrial pathway was triggered by affecting the Bcl-2 members of regulatory proteins and increased caspase 9 protein expression. In MDA-MB-231 cells, apoptosis was initiated from the mitochondria, due to disbalance between expressions of pro- and anti-apoptotic Bcl-2 family members and caspase 9 activation. Complex 1 shows better activity compared to Complex 2, which is in accordance with its structural characteristics. The results deal weighty data about proapoptotic activity of gold(III) complexes and highlighted potential targets for cancer therapy.

Role of Lactiplantibacillus plantarum strain RD1 (Lpb RD1) in mitochondria-mediated apoptosis: an in vitro analysis

The purpose of this study was to determine the cytotoxicity of Lactiplantibacillus plantarum strain RD1 (Lpb RD1), which was isolated and identified from the curd by 16 S rRNA sequencing. The probiotic properties of the isolated strain were studied by bile and NaCl tolerance and the ethyl acetate extract of Ea-LpRD1, was used to determine the toxicity against human breast cancer (MCF-7) cell lines and human embryonic kidney (HEK-293) cell lines by MTT assay. DNA fragmentation assay was carried out to study apoptosis induction. Flow cytometry analysis was done to determine the % of a cell population using the FTIC-Annexin V staining method. RT-PCR was used to assess gene expression levels in both cell lines. The IC₅₀ concentration of the Ea-LpRD1 in MCF-7 cells was 0.30 mg/ml and in HEK-293 was 0.47 mg/ml. The expression levels of the BCL-2 gene anti-apoptotic genes in humans were reduced and BAX, caspase-8, caspase-3, and caspase-9 were an increased expression in MCF-7 cell lines.

Modeled microgravity alters apoptotic gene expression and caspase activity in the squid-vibrio symbiosis

Background

Spaceflight is a novel and profoundly stressful environment for life. One aspect of spaceflight, microgravity, has been shown to perturb animal physiology thereby posing numerous health risks, including dysregulation of normal developmental pathways. Microgravity can also negatively impact the interactions between animals and their microbiomes. However, the effects of microgravity on developmental processes influenced by beneficial microbes, such as apoptosis, remains poorly understood. Here, the binary mutualism between the bobtail squid, Euprymna scolopes, and the gram-negative bacterium, Vibrio fischeri, was studied under modeled microgravity conditions to elucidate how this unique stressor alters apoptotic cell death induced by beneficial microbes.

Results

Analysis of the host genome and transcriptome revealed a complex network of apoptosis genes affiliated with extrinsic/receptor-mediated and intrinsic/stress-induced apoptosis. Expression of apoptosis genes under modeled microgravity conditions occurred earlier and at high levels compared to gravity controls, in particular the expression of genes encoding initiator and executioner caspases. Functional assays of these apoptotic proteases revealed heightened activity under modeled microgravity; however, these increases could be mitigated using caspase inhibitors.

Conclusions

The outcomes of this study indicated that modeled microgravity alters the expression of both extrinsic and intrinsic apoptosis gene expression and that this process is mediated in part by caspases. Modeled microgravity-associated increases of caspase activity can be pharmacologically inhibited suggesting that perturbations to the normal apoptosis signaling cascade can be mitigated, which may have broader implications for maintaining animal-microbial homeostasis in spaceflight.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-022-02614-x.

Clostridioides difficile toxin B alone and with pro-inflammatory cytokines induces apoptosis in enteric glial cells by activating three different signalling pathways mediated by caspases, calpains and cathepsin B

Clostridioides difficile infection (CDI) causes nosocomial/antibiotic-associated gastrointestinal diseases with dramatically increasing global incidence and mortality rates. The main C. difficile virulence factors, toxins A and B (TcdA/TcdB), cause cytopathic/cytotoxic effects and inflammation. We demonstrated that TcdB induces caspase-dependent, mitochondria-independent enteric glial cell (EGC) apoptosis that is enhanced by the pro-inflammatory cytokines TNF-α and IFN-γ (CKs) by increasing caspase-3/7/9 and PARP activation. Because this cytotoxic synergism is important for CDI pathogenesis, we investigated the apoptotic pathways involved in TcdB- and TcdB + CK-induced apoptosis indepth. EGCs were pre-treated with the inhibitors BAF or Q-VD-OPh (pan-caspase), Z-DEVD-fmk (caspase-3/7), Z-IETD-fmk (caspase-8), PD150606 (calpains), and CA-074Me (cathepsin B) 1 h before TcdB exposure, while CKs were given 1.5 h after TcdB exposure, and assays were performed at 24 h. TcdB and TcdB + CKs induced apoptosis through three signalling pathways activated by calpains, caspases and cathepsins, which all are involved both in induction and execution apoptotic signalling under both conditions but to different degrees in TcdB and TcdB + CKs especially as regards to signal transduction mediated by these proteases towards downstream effects (apoptosis). Calpain activation by Ca²⁺ influx is the first pro-apoptotic event in TcdB- and TcdB + CK-induced EGC apoptosis and causes caspase-3, caspase-7 and PARP activation. PARP is also directly activated by calpains which are responsible of about 75% of apoptosis in TcdB and 62% in TcdB + CK which is both effector caspase-dependent and -independent. Initiator caspase-8 activation mediated by TcdB contributes to caspase-3/caspase-7 and PARP activation and is responsible of about 28% of apoptosis in both conditions. Caspase-3/caspase-7 activation is weakly responsible of apoptosis, indeed we found that it mediates 27% of apoptosis only in TcdB. Cathepsin B contributes to triggering pro-apoptotic signal and is responsible in both conditions of about 35% of apoptosis by a caspase-independent manner, and seems to regulate the caspase-3 and caspase-7 cleaved fragment levels, highlighting the complex interaction between these cysteine protease families activated during TcdB-induced apoptosis. Further a relevant difference between TcdB- and TcdB + CK-induced apoptosis is that TcdB-induced apoptosis increased slowly reaching at 72 h the value of 18.7%, while TcdB + CK-induced apoptosis increased strongly reaching at 72 h the value of 60.6%. Apoptotic signalling activation by TcdB + CKs is enriched by TNF-α-induced NF-κB signalling, inhibition of JNK activation and activation of AKT. In conclusion, the ability of C. difficile to activate three apoptotic pathways represents an important strategy to overcome resistance against its cytotoxic activity.

Caspase-mediated regulation of the distinct signaling pathways and mechanisms in neuronal survival

Caspases are intimately associated with altering various signaling pathways, resulting in programmed cell death or apoptosis. Apoptosis is necessary for the normal homeostasis of cells and their development. The untoward activation of apoptotic pathways indirectly or directly results in pathologies of various diseases. Identifying different caspases in apoptotic pathways directed the research to develop caspase inhibitors as therapeutic agents. However, no drug is available in the market that targets caspase inhibition and produces a therapeutic effect. Here, we will shed light on the role of caspases in the number of neuronal disorders and neurodegenerative diseases. The article reviews the findings about the activation of various upstream mechanisms associated with caspases in neurodegenerative disorders along with the recent progress in the generation of caspase inhibitors and the challenge faced in their development as therapeutic agents for neurological indications.

Sesquiterpene from Polygonum barbatum disrupts mitochondrial membrane potential to induce apoptosis and inhibits metastasis by downregulating matrix metalloproteinase and osteopontin in NCI-H460 cells

Globally, lung cancer accounts for 18% of cancer-associated mortalities. Among the subtypes, non-small cell lung cancer (NSCLC) is the most prevalent. The increased resistance and poor survival rates signify disease aggressiveness and thus require a search for an alternative anticancer molecule. Earlier, the sesquiterpene, i.e., compound 3 ((E)-methyl 6-acetoxy-7-methoxy-1-(2-methylpropylidene)-1H-indene-3-carboxylate) from Polygonum barbatum, was isolated, characterized by us, and reported for preliminary anticancer activity. Therefore, based on these results, this study was designed to explore the underlying molecular mechanism of apoptosis and metastasis against NCI-H460 cells. The molecular mechanism of compound 3 inducing apoptosis and inhibiting metastasis was elucidated by analyzing mitochondrial membrane potential, DNA fragmentation, clonogenic assay, invasion assay, and expression of apoptotic (caspases 3, 6, 8, 9, and BAK) and metastatic markers (MMP 2, MMP 9, and osteopontin). Compound 3 significantly inhibited cell proliferation and induced apoptosis via the intrinsic route, i.e., the mitochondrial pathway, by disrupting mitochondrial membrane potential. The enhanced expression of caspases 6, 9, BAK, and HRK with downregulation of Bcl-2L1 and Ki67 further confirmed the involvement of the intrinsic apoptotic pathway. Moreover, compound 3 restricted the invasive nature of NCI-H460 cells evinced by reduced cell invasion in Boyden chamber invasion assay and downregulating the expression of metastatic markers, i.e., matrix metalloproteinase 2/9 and VEGF. It was also found to block osteopontin by negatively regulating its expression, a marker protein in cancer management. Conclusively, this sesquiterpene exhibited potent anticancer and antimetastatic activity and can be explored further as possible pharmacophores.

Ars moriendi: Proteases as sculptors of cellular suicide

The Ars moriendi, which translates to "The Art of Dying," encompasses two Latin texts that gave advice on how to die well and without fear according to the Christian precepts of the late Middle Ages. Given that ten to hundred billion cells die in our bodies every day, it is obvious that the concept of a well and orderly ("regulated") death is also paramount at the cellular level. In apoptosis, as the most well-studied form of regulated cell death, proteases of the caspase family are the central mediators. However, caspases are not the only proteases that act as sculptors of cellular suicide, and therefore, we here provide an overview of the impact of proteases in apoptosis and other forms of regulated cell death.

Pharmacological, Biochemical and Immunological Studies on Protective Effect of Mangiferin in 6-Hydroxydopamine (6-OHDA)-Induced Parkinson's Disease in Rats

Background:

Parkinson’s disease is a neurodegenerative disorder and is marked by inflammation and death of neurons in the striatum region of the midbrain. It has been reported that expression of NF-κB increases during Parkinson’s disease, which promotes oxidative stress, stimulates release of proinflammatory cytokines, and induces expression of nitric oxide. Therefore, in this study, we have used mangiferin a specific NF-κB inhibitor. Mangiferin is a polyphenolic compound traditionally used for its antioxidant and anti-inflammatory properties.

Methods:

The study utilized male Wistar rats weighing 200–250 g (56 rats; n = 8/group). On day “0,” stereotaxic surgery of rats was done to induce 6-hydroxydopamine lesioning in rats. Coordinates for substantia nigra were anteroposterior-2 mm, mediolateral-5 mm and dorsoventral-8.2 mm. After 14 days, those rats which show at least 210 contralateral rotations after administration of apomorphine (0.5 mg/kg S.C.) were selected for the study and were given treatment for 28 days. On day 28 of treatment, rats were subjected to behavioral studies to evaluate the effect of mangiferin and their brains were taken out after euthanasia to perform biochemical, molecular and immunological studies.

Results:

Treatment with mangiferin significantly improves the key parameters of locomotor activity and oxidative stress and reduces the parameters of inflammatory stress. Also, the activity of caspases was reduced. Significant decrease in activity of both cyclooxygenase 1 and 2 was also observed. Maximum improvement in all parameters was observed in rats treated with grouping of mangiferin 45 µg/kg and levodopa 10 mg/kg. Treatment with levodopa alone has no significant effect on biochemical and molecular parameters though it significantly improves behavioral parameters.

Conclusion:

Current treatment of Parkinson’s disease does not target progression of Parkinson’s disease. Results of this study suggest that mangiferin has protective effect in hemi-Parkinsonian rats. Therefore, the combination therapy of mangiferin and levodopa can be helpful in management of Parkinson’s disease.

Caspase Inhibition Restores NEP Expression and Rescues Olfactory Deficit in Rats Caused by Prenatal Hypoxia

Development of the olfactory system begins early in embryogenesis and is important for the survival of new-borns in postnatal life. Olfactory malfunction in early life disrupts development of behavioural patterns while with ageing manifests development of neurodegenerative disorders. Previously, we have shown that prenatal hypoxia in rats leads to impaired olfaction in the offspring and correlates with reduced expression of a neuropeptidase neprilysin (NEP) in the brain structures involved in processing of the olfactory stimuli. Prenatal hypoxia also resulted in an increased activity of caspases in rat brain and its inhibition restored NEP content in the brain tissue and improved rat memory. In this study, we have analysed effects of intraventricular administration of a caspase inhibitor Ac-DEVD-CHO on NEP mRNA expression, the number of dendritic spines and olfactory function of rats subjected to prenatal hypoxia on E14. The data obtained demonstrated that a single injection of the inhibitor on P20 restored NEP mRNA levels and number of dendritic spines in the entorhinal and parietal cortices, hippocampus and rescued rat olfactory function in food search and odour preference tests. The data obtained suggest that caspase activation caused by prenatal hypoxia contributes to the olfactory dysfunction in developing animals and that caspase inhibition restores the olfactory deficit via upregulating NEP expression and neuronal networking. Because NEP is a major amyloid-degrading enzyme, any decrease in its expression and activity not only impairs brain functions but also predisposes to accumulation of the amyloid-β peptide and development of neurodegeneration characteristic of Alzheimer's disease.

Guanylate Binding Protein 1 (GBP1): A Key Protein in Inflammatory Pyroptosis

Scientists recently made a significant breakthrough in the recognition of pathogens via guanylate binding protein 1 (GBP1). Wandel et al. [1] in Nature Immunology described their findings where GBP1 acts as a pattern recognition receptor that directly connects to lipopolysaccharide (LPS). GBP1 identifies gram-negative bacteria such as the enteric pathogen, Salmonella enterica serovar Typhimurium, that enter the cytoplasm of the host cell. GBP1 then quickly connects to LPS and stimulates the assembly of more GBPs in the order of GBP2, GBP3, and GBP4. Subsequently, inflammatory caspase-4 arrives at the GBP1-4 activation platform. Next, the activated caspase-4 drives the cleavage of Gasdermin D, triggering the release of the pro-inflammatory cytokine, interleukin-18 (IL-18) leading to inflammatory pyroptosis and cell death. Not only do these remarkable results expand our current understanding of GBP1, but they also carry the potential to develop therapeutic targets for inflammasome-mediated human disorders.

NSAIDs and Kelleni's protocol as potential early COVID-19 treatment game changer: could it be the final countdown?

We have previously published several papers illustrating numerous immunomodulatory and anti-inflammatory potential benefits when we repurposed safe, generic non-steroidal anti-inflammatory drugs (NSAIDs)/nitazoxanide/azithromycin (Kelleni's protocol), to early manage our COVID-19 pediatric, adult, and pregnant patients. In this manuscript, we discuss some recently published meta-analysis and clinical studies supporting our practice and discuss a molecular study that might be interpreted as an academic proof that our protocol might also prevent SARS-CoV-2 replication. Moreover, after aspirin has been suggested to be independently associated with reduced risk of mechanical ventilation, ICU admission and in-hospital mortality of COVID-19, we claim that the molecular interpretation of the results that led to this suggestion was not scientifically accurate, and we provide our academic interpretation confirming that low-dose aspirin is least likely to improve COVID-19 mortality through anticoagulation as was suggested. Furthermore, we describe other potential benefits related to aspirin-triggered lipoxins and resolvins while illustrating how NSAIDs interfere with COX-1, COX-2, SARS-CoV-2/ SARS-CoV-2 ORF protein-dependent activation of caspases and their subsequent mitochondrial dysfunction, endoplasmic reticulum stress, apoptosis and necroptosis which were associated with COVID-19 complications. Similarly, NSAIDs are known caspase inhibitors and thus they might independently inhibit other caspase-related COVID-19-associated downstream pathological signaling mechanisms. Finally, we postulated that CARD-14, a caspase recruitment domain-containing protein, polymorphisms might play a role in the development of severe and critical COVID-19 and confirmed our old call to early adopt NSAIDs, as an integral part of Kelleni's protocol, as of choice in its management aiming to end this pandemic.

EPEC-induced activation of the Ca2+ transporter TRPV2 leads to pyroptotic cell death

The enteropathogenic Escherichia coli (EPEC) type III secretion system effector Tir, which mediates intimate bacterial attachment to epithelial cells, also triggers Ca2+ influx followed by LPS entry and caspase-4-dependent pyroptosis, which could be antagonized by the effector NleF. Here we reveal the mechanism by which EPEC induces Ca2+ influx. We show that in the intestinal epithelial cell line SNU-C5, Tir activates the mechano/osmosensitive cation channel TRPV2 which triggers extracellular Ca2+ influx. Tir-induced Ca2+ influx could be blocked by siRNA silencing of TRPV2, pre-treatment with the TRPV2 inhibitor SET2 or by growing cells in low osmolality medium. Pharmacological activation of TRPV2 in the absence of Tir failed to initiate caspase-4-dependent cell death, confirming the necessity of Tir. Consistent with the model implicating activation on translocation of TRPV2 from the ER to plasma membrane, inhibition of protein trafficking by either brefeldin A or the effector NleA prevented TRPV2 activation and cell death. While infection with EPECΔnleA triggered pyroptotic cell death, this could be prevented by NleF. Taken together this study shows that while integration of Tir into the plasma membrane activates TRPV2, EPEC uses NleA to inhibit TRPV2 trafficking and NleF to inhibit caspase-4 and pyroptosis.

Exploring the MEN1 dependent modulation of caspase 8 and caspase 3 in human pancreatic and murine embryo fibroblast cells

MEN1 mutation causes pancreatic neuroendocrine neoplasia and benign malignancies of the parathyroid, the adrenal cortex and pituitary gland. The transcriptional activity of its product menin promotes the expression of genes deputed to several cellular mechanism including cell death. Here, we focused on its implication in the activation of the initiator and executioner caspases after staurosporine mediated cell death in 2D and 3D human and murine cell models. The administration of staurosporine, a well-known inducer of apoptotic cell death, caused a significant reduction of BON1, QGP1 and HPSC2.2 cell viability. The transient knockdown of MEN1, performed by using a specific siRNA, caused a significant down-regulation of CDKN1A and TP53 transcripts. The treatment with 1 µM of staurosporine caused also a significant down-regulation of MEN1 and was able to restore the basal expression of TP53 only in QGP1 cells. Transient or permanent MEN1 inactivation caused a decrease of caspase 8 activity in BON1, HPSC2.2 cells and MEN1^-/- MEFs treated with staurosporine. Caspase 3/7 activity was suppressed after administration of staurosporine in MEN1 knocked down HPSC2.2 and MEN1^-/- MEFs as well. The cleaved caspase 8 and caspase 3 decreased in human cells after MEN1 knockdown and in MEN1^-/- MEFs. The treatment with staurosporine caused a reduction of the size of MEN1^+/+ MEFs spheroids. Instead, MEN1^-/- MEFs spheroids did not show any significant reduction of their size. In conclusion, MEN1 controls the activity of the initiator caspase 8 and the executioner caspase 3 in human and murine cells. Restoring of a functional MEN1 and interfering with the apoptotic mechanism could represent a future strategy for the treatment of MEN1-related malignancies.

The roles of cellular protease interactions in viral infections and programmed cell death: a lesson learned from the SARS-CoV-2 outbreak and COVID-19 pandemic

The unprecedented pandemic of SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2), which leads to COVID-19, is threatening global health. Over the last 2 years, we have witnessed rapid progress in research focusing on developing new antiviral vaccines and drugs, as well as in academic and clinical efforts to understand the biology and pathology of COVID-19. The roles of proteases among master regulators of SARS-CoV-2 invasion and replication and their pivotal roles in host defence against this pathogen, including programmed cell death, have not been well established. Our understanding of protease function in health and disease has increased considerably over the last two decades, with caspases, matrix metalloproteases, and transmembrane serine proteases representing the most prominent examples. Therefore, during the COVID-19 pandemic, these enzymes have been investigated as potential molecular targets for therapeutic interventions. Proteases that are responsible for SARS-CoV-2 cell entry and replication, such as TMPRSS2, ACE2 or cathepsins, are screened with inhibitor libraries to discover lead structures for further drug design that would prevent virus multiplication. On the other hand, proteases that orchestrate programmed cell death can also be harnessed to enhance the desired demise of infected cells through apoptosis or to attenuate highly inflammatory lytic cell death that leads to undesired cytokine storms, a major hallmark of severe COVID-19. Given the prominent role of proteases in SARS-CoV-2-induced cell death, we discuss the individual roles of these enzymes and their catalytic interactions in the pathology of COVID-19 in this article. We provide a rationale for targeting proteases participating in cell death as potential COVID-19 treatments and identify knowledge gaps that might be investigated to better understand the mechanism underlying SARS-CoV-2-induced cell death.

Daidzin inhibits growth and induces apoptosis through the JAK2/STAT3 in human cervical cancer HeLa cells

Daidzin, 4′, 7-dihydroxyisoflavone is an isoflavonic phytoestrogen present in leguminous plants. Traditional Chinese medicine utilizes daidzin to treat various diseases such diarrhea, fever, hepatitis, cardiac problems etc. In current study we examined the anticancer activity of daidzin against human cervical cancer in vitro. HeLa, human cervical cancer cell line was purchased from ATCC and the cells were cultured with DMEM medium. The cytotoxic effect of daidzin against HeLa cell line was analyzed with MTT assay. The IC-50 value was obtained at 20 µM hence the cells were treated with 20 µM of daidzin for further analysis. ROS generation was assessed with DCFH-DA staining and the induction of apoptosis was examined with Rhoadmine-123 staining. Acridine orange and ethidium bromide staining was done to examine the apoptotic and viable cells. Further the matrigel cell adhesion assay was done to analyze the inhibitory property of daidzin against cancer cell adhesion. Apoptotic induction of daidzin was examined by estimating the levels of Caspase 8 & 9 using ELISA technique. Inflammatory and cell proliferation signaling proteins were analyzed with qPCR analysis to confirm the anticancer activity of daidzin against human cervical cancer HeLa cell line. Daidzin significantly generated ROS and altered the mitochondrial membrane permeability in HeLa cell line. The results of AO/EtBr staining prove daidzin induced apoptosis in HeLa cell line and it also inhibited the cell adhesion property of HeLa which is reported in our matrigel cell adhesion assay. It also increased the caspases 8 & 9 which are key regulators of apoptosis. Daidzin significantly decreased the expression of inflammatory gene and cell proliferating signaling molecule. To, conclude our results confirm daidzin effectively decreased inflammation and induced apoptosis in human cervical cancer HeLa cell line.

Designing of various biosensor devices for determination of apoptosis: A comprehensive review

Apoptosis is a type of cell death caused by the occurrence of both pathological and physiological conditions triggered by ligation of death receptors outside the cell or triggered by DNA damage and/or cytoskeleton disruption. Timely monitoring of apoptosis can effectively help early diagnosis of related diseases and continuous assessment of the effectiveness of drugs. Detecting caspases, a protease family closely related to cellular apoptosis, and its identification as markers of apoptosis is a popular procedure. Biosensors are used for early diagnosis and play a very important role in preventing disease progression in various body sections. Recently, there has been a widespread increase in the desire to use materials made of paper (e.g. nitrocellulose membrane) for Point-of-Care (POC) testing systems since paper and paper-like materials are cheap, abundant and degradable. Microfluidic paper-based analytical devices (μPADs) are highly promising as they are cost-effective, easy to use, fast, precise and sustainable over time and under different environmental conditions. In this review, we focused our efforts on compiling the different approaches on identifying apoptosis pathway while giving brief information about apoptosis and biosensors. This review includes recent advantages in biosensing techniques to simply determine what happened in the cell life and which direction it would continue. As a conclusion, we believed that the review may help to researchers to compare/update the knowledge about diagnosis of the apoptosis pathway while reminding the basic definitions about the apoptosis and biosensor technologies.