Till Death Do Us Part: The Marriage of Autophagy and Apoptosis

The multifaceted role of autophagy in skin autoimmune disorders: a guardian or culprit?

Autophagy is a cellular process that functions to maintain intracellular homeostasis via the degradation and recycling of defective organelles or damaged proteins. This dynamic mechanism participates in various biological processes, such as the regulation of cellular differentiation, proliferation, survival, and the modulation of inflammation and immune responses. Recent evidence has demonstrated the involvement of polymorphisms in autophagy-related genes in various skin autoimmune diseases. In addition, autophagy, along with autophagy-related proteins, also contributes to homeostasis maintenance and immune regulation in the skin, which is associated with skin autoimmune disorders. This review aims to provide an overview of the multifaceted role of autophagy in skin autoimmune diseases and shed light on the potential of autophagy-targeting therapeutic strategies in dermatology.

Deterministic and stochastic approaches to a minimal model for the transition from autophagy to apoptosis

Autophagy and apoptosis are crucial cellular mechanisms. The cytoprotective function of autophagy is mediated by the negative regulation of apoptosis, which in turn inhibits autophagy. Although research into the molecular connection between autophagy and apoptosis is booming, the intricate regulatory mechanisms of this process are still not completely understood. Therefore, the objective of this study was to develop a minimal model to explore the transition from autophagy to apoptosis. This biological system was analyzed by comprehensively integrating both the deterministic and the stochastic dynamics of the cells. The system exhibited bistability, and the statistical properties of cells undergoing autophagy and apoptosis were analyzed at two different stress levels with varying noise strengths. Moreover, we investigated how noise affected the double negative feedback loops between autophagy and apoptosis and further triggered transitions at two different stress levels and initial conditions. Finally, the effect of noise on transition was comprehensively studied under continuous stress variations and the two different initial conditions, showing that stronger noise results in more randomness during the switching process. Our work may provide novel insights for further experiments and modeling.

Flavonoids as promising molecules in the cancer therapy: An insight

Cancer continues to increase global morbidity and mortality rates. Despite substantial progress in the development of various chemically synthesized anti-cancer drugs, the poor prognosis of the disease still remains a big challenge. The most common drawback of conventional cancer therapies is the emergence of drug resistance eventually leading to the discontinuation of chemotherapy. Moreover, advanced target-specific therapies including immunotherapy and stem cell therapy are expensive enough and are unaffordable for most patients in poorer nations. Therefore, alternative and cheaper therapeutic strategies are needed to complement the current cancer treatment approaches. Phytochemicals are bioactive compounds produced naturally by plants and have great potential in human health and disease. These compounds possess antiproliferative, anti-oxidant, and immunomodulatory properties. Among the phytochemicals, flavonoids are very effective in treating a wide range of diseases from cardiovascular diseases and immunological disorders to cancer. They scavenge reactive oxygen species (ROS), inhibit cancer metastasis, modulate the immune system and induce apoptotic or autophagic cell death in cancers. This review will discuss the potential of various phytochemicals particularly flavonoids in attempts to target various cancers.

Autophagy: Regulator of cell death

Autophagy is the process by which cells degrade and recycle proteins and organelles to maintain intracellular homeostasis. Generally, autophagy plays a protective role in cells, but disruption of autophagy mechanisms or excessive autophagic flux usually leads to cell death. Despite recent progress in the study of the regulation and underlying molecular mechanisms of autophagy, numerous questions remain to be answered. How does autophagy regulate cell death? What are the fine-tuned regulatory mechanisms underlying autophagy-dependent cell death (ADCD) and autophagy-mediated cell death (AMCD)? In this article, we highlight the different roles of autophagy in cell death and discuss six of the main autophagy-related cell death modalities, with a focus on the metabolic changes caused by excessive endoplasmic reticulum-phagy (ER-phagy)-induced cell death and the role of mitophagy in autophagy-mediated ferroptosis. Finally, we discuss autophagy enhancement in the treatment of diseases and offer a new perspective based on the use of autophagy for different functional conversions (including the conversion of autophagy and that of different autophagy-mediated cell death modalities) for the clinical treatment of tumors.

H1Innovative approaches to combat anti-cancer drug resistance: Targeting lncRNA and autophagy

BACKGROUND

To date, standardizing clinical predictive biomarkers for assessing the response to immunotherapy remains challenging due to variations in personal genetic signatures, tumour microenvironment complexities and epigenetic onco-mechanisms.

MAIN BODY

Early monitoring of key non-coding RNA (ncRNA) biomarkers may help in predicting the clinical efficacy of cancer immunotherapy and come up with standard predictive ncRNA biomarkers. For instance, reduced miR-125b-5p level in the plasma of non-small cell lung cancer patients treated with anti-PD-1 predicts a positive outcome. The level of miR-153 in the plasma of colorectal cancer patients treated with chimeric antigen receptor T lymphocyte (CAR-T) cell therapy may indicate the activation of T-cell killing activity. miR-148a-3p and miR-375 levels may forecast favourable responses to CAR-T-cell therapy in B-cell acute lymphoblastic leukaemia. In cancer patients treated with the GPC3 peptide vaccine, serum levels of miR-1228-5p, miR-193a-5p and miR-375-3p were reported as predictive biomarkers of good response and improved overall survival. Therefore, there is a critical need for further studies to elaborate on the key ncRNA biomarkers that have the potential to predict early clinical responses to immunotherapy.

CONCLUSIONS

This review summarises important predictive ncRNA biomarkers that were reported in cancer patients treated with different immunotherapeutic modalities including monoclonal antibodies, small molecule inhibitors, cancer vaccines and CAR-T cells. In addition, a concise discussion on forthcoming perspectives is provided, outlining technical approaches for the optimal utilisation of immune-modulatory ncRNA biomarkers as predictive tools and therapeutic targets.

Nano selenium-doped TiO2 nanotube arrays on orthopedic implants for suppressing osteosarcoma growth

Osteosarcoma, the most common primary malignant bone tumor, is characterized by malignant cells producing osteoid or immature bone tissue. Most osteosarcoma patients require reconstructive surgery to restore the functional and structural integrity of the injured bone. Metal orthopedic implants are commonly used to restore the limb integrity in postoperative patients. However, conventional metal implants with a bioinert surface cannot inhibit the growth of any remaining cancer cells, resulting in a higher risk of cancer recurrence. Herein, we fabricate a selenium-doped TiO2 nanotube array (Se-doped TNA) film to modify the surface of medical pure titanium substrate, and evaluate the anti-tumor effect and biocompatibility of Se-doped TNA film. Moreover, we further explore the anti-tumor potential mechanism of Se-doped TNA film by studying the behaviors of human osteosarcoma cells in vitro. We provide a new pathway for achieving the anti-tumor function of orthopedic implants while keeping the biocompatibility, aiming to suppress the recurrence of osteosarcoma.

The Synergistic Antitumor Effect of Decitabine and Vorinostat Combination on HepG2 Human Hepatocellular Carcinoma Cell Line via Epigenetic Modulation of Autophagy-Apoptosis Molecular Crosstalk

Hepatocellular carcinoma (HCC) is a worldwide health issue. Epigenetic alterations play a crucial role in HCC tumorigenesis. Using epigenetic modulators for HCC treatment confers a promising therapeutic effect. The aim of this study was to explore the effect of a decitabine (DAC) and vorinostat (VOR) combination on the crosstalk between apoptosis and autophagy in the HCC HepG2 cell line at 24 h and 72 h. Median inhibitory concentrations (IC₅₀s) of VOR and DAC were assessed in the HepG2 cell line. The activity of caspase-3 was evaluated colorimetrically, and Cyclin D1(CCND1), Bcl-2, ATG5, ATG7, and P62 levels were assessed using ELISA at different time intervals (24 h and 72 h), while LC3IIB and Beclin-1gene expression were measured by using qRT-PCR. The synergistic effect of VOR and DAC was confirmed due to the observed combination indices (CIs) and dose reduction indices (DRIs). The combined treatment with both drugs inhibited the proliferation marker (CCND1), and enhanced apoptosis compared with each drug alone at 24 h and 72 h (via active caspase-3 upregulation and Bcl-2 downregulation). Moreover, the combination induced autophagy as an early event via upregulation of Beclin-1, LC3IIB, ATG5, and ATG7 gene expression. The initial induction of autophagy started to decrease after 72 h due to Beclin-1 downregulation, and there was decreased expression of LC3IIB compared with the value at 24 h. Herein, epigenetic modulation via the VOR/DAC combination showed an antitumor effect through the coordination of an autophagy-apoptosis crosstalk and promotion of autophagy-induced apoptosis, which ultimately led to the cellular death of HCC cancer cells.

In Vitro and In Vivo Biological Activities of Dipicolinate Oxovanadium(IV) Complexes

The work is focused on anticancer properties of dipicolinate (dipic)-based vanadium(IV) complexes [VO(dipic)(N^∩N)] bearing different diimines (2-(1H-imidazol-2-yl)pyridine, 2-(2-pyridyl)benzimidazole, 1,10-phenanthroline-5,6-dione, 1,10-phenanthroline, and 2,2'-bipyridine), as well as differently 4,7-substituted 1,10-phenanthrolines. The antiproliferative effect of V(IV) systems was analyzed in different tumors (A2780, HCT116, and HCT116-DoxR) and normal (primary human dermal fibroblasts) cell lines, revealing a high cytotoxic effect of [VO(dipic)(N^∩N)] with 4,7-dimethoxy-phen (5), 4,7-diphenyl-phen (6), and 1,10-phenanthroline (8) against HCT116-DoxR cells. The cytotoxicity differences between these complexes can be correlated with their different internalization by HCT116-DoxR cells. Worthy of note, these three complexes were found to (i) induce cell death through apoptosis and autophagy pathways, namely, through ROS production; (ii) not to be cytostatic; (iii) to interact with the BSA protein; (iv) do not promote tumor cell migration or a pro-angiogenic capability; (v) show a slight in vivo anti-angiogenic capability, and (vi) do not show in vivo toxicity in a chicken embryo.

Hydrogen inhalation enhances autophagy via the AMPK/mTOR pathway, thereby attenuating doxorubicin-induced cardiac injury

AIMS

Doxorubicin is a drug widely used in clinical cancer treatment, but severe cardiotoxicity limits its clinical application. Autophagy disorder is an important factor in the mechanism of doxorubicin-induced cardiac injury. As the smallest molecule in nature, hydrogen has various biological effects such as anti-oxidation, anti-apoptosis and regulation of autophagy. Hydrogen therapy is currently considered to be an emerging therapeutic method, but the effect and mechanism of hydrogen on doxorubicin-induced myocardial injury have not been determined. The purpose of this study was to investigate the protective effect of hydrogen inhalation on doxorubicin-induced chronic myocardial injury and its effect and mechanism on autophagy.

METHODS

In this study, we established a chronic heart injury model by intraperitoneal injection of doxorubicin in rats for 30 days, accumulating 20 mg/kg. The effect of hydrogen inhalation on the cardiac function in rats was explored by echocardiography, Elisa, and H&E staining. To clarify the influence of autophagy, we detected the expression of LC3 and related autophagy proteins in vivo and in vitro by immunofluorescence and western blot.In order to further explore the mechanism of autophagy, we added pathway inhibitors and used western blot to preliminarily investigate the protective effect of hydrogen inhalation on myocardial injury caused by doxorubicin.

RESULTS

Hydrogen inhalation can improve doxorubicin-induced cardiac function decline and pathological structural abnormalities in rats. It was confirmed by immunofluorescence that hydrogen treatment could restore the expression of autophagy marker protein LC3 (microtubule-associated protein 1 light chain 3) in cardiomyocytes reduced by doxorubicin, while reducing cardiomyocyte apoptosis. Mechanistically, Western blot results consistently showed that hydrogen treatment up-regulated the ratio of p-AMPK (phosphorylated AMP-dependent protein kinase) to AMPK and down-regulated p-mTOR (phosphorylated mammalian target of rapamycin) and mTOR ratio.

CONCLUSIONS

These results suggest that hydrogen inhalation can activate autophagy through the AMPK/mTOR pathway and protect against myocardial injury induced by doxorubicin. Hydrogen inhalation therapy may be a potential treatment for doxorubicin-induced myocardial injury.

Red porgy's (Pagrus pagrus) cellular physiology and antioxidant defense in response to seasonality

Physiological stress patterns of marine organisms in their natural habitats are considerably complex in space and time. These patterns can eventually contribute in the shaping of fish' thermal limits under natural conditions. In the view of the knowledge gap regarding red porgy's thermal physiology, in combination with the characterization of the Mediterranean Sea as a climate change ''hotspot'', the aim of the present study was to investigate this species biochemical responses to constantly changing field conditions. To achieve this goal, Heat Shock Response (HSR), MAPKs pathway, autophagy, apoptosis, lipid peroxidation and antioxidant defense were estimated and exhibited a seasonal pattern. In general, all the examined biochemical indicators expressed high levels parallel to the increasing seawater temperature in spring, although several bio-indicators have shown increased levels when fish were cold-acclimatized. Similar to other sparids, the observed patterns of physiological responses in red porgy may support the concept of eurythermy.

Piceatannol enhances Beclin-1 activity to suppress tumor progression and its combination therapy strategy with everolimus in gastric cancer

The effects and regulation of Beclin-1-an autophagy-related protein-have not been fully defined, however, a negative correlation has been reported between Beclin-1 expression and carcinogenesis. Meanwhile, no compound has been shown to directly inhibit its activity. Here, we evaluate piceatannol, a naturally occurring polyphenolic compound, as a potential targeting agonist of Beclin-1, to assess its efficacy as an antitumor agent against gastric cancer. More specifically, we determine the effects of piceatannol treatment on cell viability using a monitoring system and colony forming assay. Piceatannol was found to efficiently inhibit the proliferation of several human gastric cancer cell lines. Autophagic flux is increased by piceatannol treatment, and correlates with inhibition of cell proliferation and colony formation. Additionally, microscale thermophoresis and surface plasmon resonance results show a direct interaction between piceatannol and Beclin-1, which reduces the phosphorylation activity of Beclin-1 at the Ser-295 site. Notably, piceatannol impairs the binding of Beclin-1 to Bcl-2 and enhances the recruitment of binding of UV radiation resistance-associated gene protein, which further triggers Beclin-1-dependent autophagy signaling. An increase in autophagic activity via treatment with the mTOR inhibitor, everolimus, effectively sensitizes piceatannol-induced antitumor effects. Xenograft models confirmed that piceatannol inhibits tumor development and elicits a potent synergistic effect with everolimus in vivo. Taken together, the findings of this study strongly support the application of combinatorial piceatannol and everolimus therapy in future clinical trials for gastric cancer patients.

Role of Rapamycin and 3-MA in oxidative damage of HLECs caused by two doses of UVB radiation

Background

This study compared the role of autophagy regulators Rapamycin and 3-MA in oxidative damage and apoptosis of human lens epithelial cells (HLECs) caused by two doses of Ultraviolet Radiation B (UVB).

Methods

HLECs were irradiated with UVB, and two doses of UVB damage models were constructed. After treatment with autophagy regulators, cell damage tests such as CCK-8, LDH activity, and Ros detection were performed. Western blotting was used to detect the levels of autophagy-related proteins and apoptosis-related proteins. Quantitative real-time PCR (RT-qPCR) was used to detect the mRNA leve of secondary antioxidant enzymes.Flow cytometry was used to examine cell viability and apoptosis. Finally, the proportion of autophagy and apoptosis was observed by electron microscope.

Results

Autophagy inhibitor 3-MA promoted oxidative damage and apoptosis of HLECs at low doses of UVB (5 mJ/cm2), which corresponds to 1.3 ​h of exposure to sunlight in human eyes. Under the high dose of UVB (50mJ/cm2), which is equivalent to 13 ​h of exposure to sunlight in human eyes, the autophagy inducer Rapamycin caused more extensive oxidative damage and apoptosis of HLECs. 3-MA was able to reduce this damage, indicating that moderate autophagy is necessary for HLECs to cope with mild oxidative stress. For high dose UVB-induced oxidative stress, the use of 3-MA inhibiting autophagy is more beneficial to reduce cell damage and apoptosis. The mechanisms include degradation of damaged organelles, regulation of the expression of antioxidant enzymes HO-1, NQO1, GCS and regulation of apoptosis-related proteins.

Conclusions

Autophagy played different roles in HLECs oxidative stress induced by two doses of UVB. It provides new ideas for reducing oxidative damage and apoptosis of HLECs to prevent or delay the progression of age-related cataract (ARC).

Autophagy and Apoptosis in Acute Brain Injuries: From Mechanism to Treatment

Significance: Autophagy and apoptosis are two important cellular mechanisms behind brain injuries, which are severe clinical situations with increasing incidences worldwide. To search for more and better treatments for brain injuries, it is essential to deepen the understanding of autophagy, apoptosis, and their interactions in brain injuries. This article first analyzes how autophagy and apoptosis participate in the pathogenetic processes of brain injuries respectively and mutually, then summarizes some promising treatments targeting autophagy and apoptosis to show the potential clinical applications in personalized medicine and precision medicine in the future. Recent Advances: Most current studies suggest that apoptosis is detrimental to brain recovery. Several studies indicate that autophagy can cause unnecessary death of neurons after brain injuries, while others show that autophagy is beneficial for acute brain injuries (ABIs) by facilitating the removal of damaged proteins and organelles. Whether autophagy is beneficial or detrimental in ABIs depends on many factors, and the results from different research groups are diverse or even controversial, making this topic more appealing to be explored further. Critical Issues: Neuronal autophagy and apoptosis are two primary pathological processes in ABIs. How they interact with each other and how their regulations affect the outcome and prognosis of brain injuries remain uncertain, making these answers more critical. Future Directions: Insights into the interplay between autophagy and apoptosis and the accurate regulations of their balance in ABIs may promote personalized and precise treatments in the field of brain injuries. Antioxid. Redox Signal. 38, 234-257.

Dynamics of a model for the degradation mechanism of aggregated α-synuclein in Parkinson's disease

Accumulation of the misfolded synaptic protein α-synuclein (αSyn^*) is a hallmark of neurodegenerative disease in Parkinson's disease (PD). Recent studies suggest that the autophagy lysosome pathway (ALP) including both the Beclin1-associated and mTOR-signaling pathways is involved in the αSyn^* clearance mechanism. In this study, a mathematical model is proposed for the degradation of αSyn^* by ALP with the crosstalk element of mTOR. Using codimension-1 bifurcation analysis, the tri-stability of αSyn^* is surveyed under three different stress signals and, in addition, consideration is given to the regulatory mechanisms for the Beclin1- and mTOR-dependent rates on αSyn^* degradation using the codimension-1 and-2 bifurcation diagrams. It was found that, especially under internal and external oxidative stresses (S ₁), the bistable switch of the aggregation of αSyn^* can be transformed from an irreversible to a reversible condition through the ALP degradation pathways. Furthermore, the robustness of the tri-stable state for the stress S ₁ to the parameters related to mTOR-mediated ALP was probed. It was confirmed that mTOR-mediated ALP is important for maintaining the essential dynamic features of the tri-stable state. This study may provide a promising avenue for conducting further experiments and simulations of the degradation mechanism of dynamic modeling in PD.

The Role of Apoptosis and Autophagy in the Hypothalamic-Pituitary-Adrenal (HPA) Axis after Traumatic Brain Injury (TBI)

Traumatic brain injury (TBI) is a major health problem affecting millions of people worldwide and leading to death or permanent damage. TBI affects the hypothalamic-pituitary-adrenal (HPA) axis either by primary injury to the hypothalamic-hypophyseal region or by secondary vascular damage, brain, and/or pituitary edema, vasospasm, and inflammation. Neuroendocrine dysfunctions after TBI have been clinically described in all hypothalamic-pituitary axes. We established a mild TBI (mTBI) in rats by using the controlled cortical impact (CCI) model. The hypothalamus, pituitary, and adrenals were collected in the acute (24 h) and chronic (30 days) groups after TBI, and we investigated transcripts and protein-related autophagy (Lc3, Bcln1, P150, Ulk, and Atg5) and apoptosis (pro-caspase-3, cleaved caspase-3). Transcripts related to autophagy were reduced in the hypothalamus, pituitary, and adrenals after TBI, however, this was not reflected in autophagy-related protein levels. In contrast, protein markers related to apoptosis increased in the adrenals during the acute phase and in the pituitary during the chronic phase. TBI stresses induce a variation of autophagy-related transcripts without modifying the levels of their proteins in the HPA axis. In contrast, protein markers related to apoptosis are increased in the acute phase in the adrenals, which could lead to impaired communication via the hypothalamus, pituitary, and adrenals. This may then explain the permanent pituitary damage with increased apoptosis and inflammation in the chronic phase. These results contribute to the elucidation of the mechanisms underlying endocrine dysfunctions such as pituitary and adrenal insufficiency that occur after TBI. Although the adrenals are not directly affected by TBI, we suggest that the role of the adrenals along with the hypothalamus and pituitary should not be ignored in the acute phase after TBI.

Advances in understanding the mitogenic, metabolic, and cell death signaling in teleost development: the case of greater amberjack (Seriola dumerili, Risso 1810)

Cell growth and differentiation signals of insulin-like growth factor-1 (IGF-1), a key regulator in embryonic and postnatal development, are mediated through the IGF-1 receptor (IGF-1R), which activates several downstream pathways. The present study aims to address crucial organogenesis and development pathways including Akt, MAPKs, heat shock response, apoptotic and autophagic machinery, and energy metabolism in relation to IGF-1R activation during five developmental stages of reared Seriola dumerili: 1 day prior to hatching fertilized eggs (D-1), hatching day (D0), 3 days post-hatching larvae (D3), 33 (D33) and 46 (D46) days post-hatching juveniles. During both the fertilized eggs stage and larval-to-juvenile transition, IGF-1R/Akt pathway activation may mediate the hypertrophic signaling, while p44/42 MAPK phosphorylation was apparent at S. dumerili post-hatching processes and juvenile organs completion. On the contrary, apoptosis was induced during embryogenesis and autophagy at hatching day indicating a potential involvement in morphogenetic rearrangements and yolk-sac reserves depletion. Larvae morphogenesis was accompanied by a metabolic turnover with increased substantial energy consumption. The findings of the present study demonstrate the developmental stages-specific shift in critical signaling pathways during the ontogeny of reared S. dumerili.

Mitochondrial toxicants in Xian-Ling-Gu-Bao induce liver injury by regulating the PI3K/mTOR signaling pathway: an in vitro study

BACKGROUND

Drug-induced mitochondrial toxicity is thought to be a common mechanism of drug hepatotoxicity. Xian-Ling-Gu-Bao (XLGB) oral preparation is a commonly used drug for osteoporosis in China. Classical safety evaluation studies have shown that the entire preparation and six Chinese herbal medicines have high safety, but the incidence of drug-induced liver damage due to XLGB remains high, the mechanism and toxic substances causing liver injury are still unclear. The purpose of this study is to identify compounds with potential mitochondrial liabilities in XLGB, and to clarify their underlying mechanisms and related pathways.

METHODS

The mitochondrial function analysis was performed using an extracellular flux assay, which simultaneously monitored both oxygen consumption rate (OCR) and extracellular acidification rate (ECAR). Through network pharmacology and in vitro experimental verification, the potential protein targets, signaling pathways and molecular mechanism of mitochondrial toxicity have been studied.

RESULTS

We observed a significant decrease in mitochondrial respiration of Psoraleae Fructus and its five compounds in fundamental bioenergetics parameters such as basal respiration, ATP-linked production and maximal respiration, indicating mitochondrial dysfunction. The network pharmacology results showed that the influence of XLGB on mitochondrial dysfunction was closely related to PI3K-Akt signaling pathway, mTOR signaling pathway and Apoptosis. Western blot showed that the levels of mTOR, p-mTOR (Ser2448), Raptor, PI3K (p110α), Beclin 1, ATG5 and Caspase-9 were up-regulated after treatment with psoralidin, psoralen and bavachin, and the expression of Bcl-2 was down-regulated after bavachinin treatment.

CONCLUSIONS

The hepatotoxicity of XLGB is associated with mitochondrial dysfunction. Five compounds in Psoraleae Fructus showed mitochondrial damage, they are psoralidin, isobavachalcone, bavachinin, bavachin and psoralen, especially psoralidin showed significant reduction in reserve capacity and respiratory control ratios. The molecular mechanism is related to the activation of PI3K/mTOR signaling pathway to inhibit autophagy and induce mitochondrial apoptosis.

Chemoprevention of 4NQO-Induced Mouse Tongue Carcinogenesis by AKT Inhibitor through the MMP-9/RhoC Signaling Pathway and Autophagy

Oral cancer (OC), the most common cancer in the head and neck, which has a poor prognosis, histopathologically follows a stepwise pattern of hyperplasia, dysplasia, and cancer. Blocking the progression of OC in the precancer stage could greatly improve the survival and cure rates. AKT protein plays a critical role in the signal transduction of cancer cells, and we found that AKT was overexpressed in human OC samples through analysis of TCGA database. Therefore, this study is aimed at investigating the chemopreventive effect of an AKT inhibitor (MK2206 2HCl) on OC. In vivo, we established a 4-nitroquinoline-1-oxide- (4NQO-) induced mouse tongue carcinogenesis model to investigate the potential chemopreventive effect of MK2206 2HCl on mouse OC resulting from 4NQO. The results showed that MK2206 2HCl could significantly reduce the incidence rate and growth of OC, inhibit the transformation of dysplasia to cancer in the 4NQO-induced mouse tongue carcinogenesis model, and simultaneously markedly suppress cell proliferation, angiogenesis, and mast cell (MC) infiltration in 4NQO-induced mouse tongue cancers. In vitro, our results revealed that MK2206 2HCl could also inhibit oral squamous cell carcinoma (OSCC) cell malignant biological behaviors, including cell proliferation, colony formation, cell invasion, and migration, while promoting apoptosis. Mechanistic studies revealed that MK2206 2HCl suppressed matrix metalloproteinase 9 (MMP-9) and RhoC expression and promoted autophagy gene LC3 II expression. In summary, our findings demonstrated the chemopreventive effect of MK2206 2HCl on the 4NQO-induced mouse tongue carcinogenesis model, which likely has an underlying mechanism mediated by the MMP-9/RhoC signaling pathway and autophagy.

Interaction between apoptosis and autophagy in testicular function

Several processes including oxidative stress, apoptosis, inflammation and autophagy are related to testicular function. Recent studies indicate that a crosstalk between apoptosis and autophagy is essential in regulating testicular function. Autophagy and apoptosis communicate with each other in a complex way, allowing them to work for or against each other in testicular cell survival and death. Several xenobiotics especially endocrine-disrupting chemicals (EDCs) have caused reproductive toxicity because of their potential to modify the rate of autophagy and trigger apoptosis. Therefore, the purpose of the present review was to shed light on how autophagy and apoptosis interact together in the testis.

Albendazole-induced autophagy blockade contributes to elevated apoptosis in cholangiocarcinoma cells through AMPK/mTOR activation

Albendazole (ABZ) is a broad-spectrum anti-parasitic drug that exhibits antitumor effects against several carcinomas. The effects of ABZ on cholangiocarcinoma (CCA) and its underlying mechanisms are still unclear. Our study aims to investigate the role of ABZ in inducing autophagy-mediated apoptosis of cholangiocarcinoma cells. The antitumor effects of ABZ were evaluated against CCA cells and HIBEC intrahepatic biliary epithelial cells. Furthermore, the apoptosis rates, and autophagy flux in RBE and FRH-0201 cells treated with ABZ were investigated. ABZ inhibited proliferation, induced cell death and apoptosis in CCA cells in vitro. In vivo, tumors from ABZ- treated BALB/c nude mice were significantly smaller than untreated mice. ABZ also induced the initiation of autophagy via AMPK/mTOR pathways, resulting in the formation of autophagosome. In addition, ABZ blocked autophagic flux by inhibiting the fusion of autophagosome-lysosome, which increased the apoptotic death of CCA cells. However, the apoptotic death of CCA cells induced by ABZ was reversed by 3-methyladenine (3-MA), an autophagosome formation inhibitor, but increased by chloroquine (CQ), an autophagosome-lysosome fusion inhibitor.Our work provides novel mechanisms for anti-tumor effects of ABZ on CCA, suggesting that ABZ may be used as a potent autophagy inhibitor in the treatment of CCA.

Mitochondrial Dysfunction and Oxidative Stress in Rheumatoid Arthritis

Control of excessive mitochondrial oxidative stress could provide new targets for both preventive and therapeutic interventions in the treatment of chronic inflammation or any pathology that develops under an inflammatory scenario, such as rheumatoid arthritis (RA). Increasing evidence has demonstrated the role of mitochondrial alterations in autoimmune diseases mainly due to the interplay between metabolism and innate immunity, but also in the modulation of inflammatory response of resident cells, such as synoviocytes. Thus, mitochondrial dysfunction derived from several danger signals could activate tricarboxylic acid (TCA) disruption, thereby favoring a vicious cycle of oxidative/mitochondrial stress. Mitochondrial dysfunction can act through modulating innate immunity via redox-sensitive inflammatory pathways or direct activation of the inflammasome. Besides, mitochondria also have a central role in regulating cell death, which is deeply altered in RA. Additionally, multiple evidence suggests that pathological processes in RA can be shaped by epigenetic mechanisms and that in turn, mitochondria are involved in epigenetic regulation. Finally, we will discuss about the involvement of some dietary components in the onset and progression of RA.

Autophagy modulation by irbesartan mitigates the pulmonary fibrotic alterations in bleomycin challenged rats: Comparative study with rapamycin

AIMS

In pulmonary fibrosis, autophagy handles the maintenance of alveolar epithelial cells, prevents epithelial-mesenchymal transition (EMT), and controls collagen turnover. The mammalian target of rapamycin (mTOR) and its translational-dependent proteins are essential regulators of autophagy. Irbesartan (IRB) has earlier ameliorative effects in experimental pulmonary fibrosis. The current study aimed to explore therapeutic autophagy-modulated pulmonary fibrotic changes by IRB versus rapamycin (RAPA) in bleomycin (BLM)-challenged rats.

MATERIALS AND METHODS

A single intratracheal BLM dose at day (0), IRB in different doses (10, 20, and 40 mg/kg) or RAPA (2.5 mg/kg) was given daily for 14 continuous days.

KEY FINDINGS

IRB significantly diminished the fibrotic lung scores. Pulmonary levels of transforming growth factor (TGF)-β1 and hydroxyproline exhibited marked attenuation in IRB (40 mg/kg)-treated rats compared to other treated groups. IRB (40 mg/kg) was not significantly different from RAPA. It downregulated the fibrotic lung phosphorylated mammalian target of rapamycin (p-mTOR) levels and augmented lung Unc-51-like autophagy activating kinase 1 (ULK1), LC3-I and LC3-II more than IRB (10 and 20 mg/kg)-treated fibrotic groups.

SIGNIFICANCE

Autophagic effects via the mTOR signalling pathway may play a role in IRB's antifibrotic effects. Consideration of IRB as a therapeutic antifibrotic agent in pulmonary fibrosis needs further experimental and clinical long-term validation, especially in comorbid with primary hypertension, heart failure, and diabetic renal insults.

Current Understanding of Long-Term Cognitive Impairment After Sepsis

Sepsis is recognized as a life-threatening multi-organ dysfunction resulting from a dysregulated host response to infection. Although the incidence and mortality of sepsis decrease significantly due to timely implementation of anti-infective and support therapies, accumulating evidence suggests that a great proportion of survivors suffer from long-term cognitive impairment after hospital discharge, leading to decreased life quality and substantial caregiving burdens for family members. Several mechanisms have been proposed for long-term cognitive impairment after sepsis, which are not mutually exclusive, including blood-brain barrier disruption, neuroinflammation, neurotransmitter dysfunction, and neuronal loss. Targeting these critical processes might be effective in preventing and treating long-term cognitive impairment. However, future in-depth studies are required to facilitate preventive and/or treatment strategies for long-term cognitive impairment after sepsis.

Quercetin mediates TSC2-RHEB-mTOR pathway to regulate chondrocytes autophagy in knee osteoarthritis

OBJECTIVE

This study aimed to explore the specific molecular mechanism of the therapeutic effect of quercetin in knee osteoarthritis (KOA).

METHODS

The KOA rat model was constructed by excising the medial meniscus and transecting the anterior meniscus. Joint injuries in rats were determined by Hematoxylin-Eosin (H&E) and Safranin O staining. The severity of KOA was then assessed according to the Osteoarthritis Research Society International (OARSI). The expressions of TSC2 and LC2B in joint tissue were measured by immunohistochemistry. Besides, chondrocytes treated with 10 ng/ml IL-1β were used to construct a chondrocyte arthritis model, while those treated with 4 or 8 μM quercetin were served as treatment groups. MTT, flow cytometry and toluidine blue staining were used to detect cell viability, apoptosis and mucopolysaccharide synthesis, respectively. qRT-PCR or Western blot was performed to determine the expressions of MMP-13, collagen II, Aggrecan, TSC2, RHEB, mTOR, p-mTOR, ULK1, p-ULK1, LC3B-I, LC3B-II and P62 in chondrocytes.

RESULTS

Quercetin alleviated the joint injury and suppressed the increase in MMP-13 expression and the decreases in collagen II and Aggrecan expressions in KOA rats. In addition, quercetin suppressed RHEB, p-mTOR, p-ULK1 and P62 expressions but promoted TSC2 and LC3BII expressions in KOA rats. Furthermore, quercetin could relieve the decrease of cell viability and the increase of apoptosis that induced by IL-1β, and promote the synthesis of IL-1β-inhibited mucopolysaccharide in chondrocytes. Nevertheless, siTSC2 partially offset the therapeutic effects of quercetin in chondrocytes.

CONCLUSION

Quercetin alleviated KOA by mediating the TSC2-RHBE-mTOR signaling pathway.

Blue light induces skin apoptosis and degeneration through activation of the endoplasmic reticulum stress-autophagy apoptosis axis: Protective role of hydrogen sulfide

Research on the phototoxicity of blue light (BL) to the skin is increasing. Although blue light can induce oxidative stress, inflammation, and inhibition of proliferation in skin cells, the mechanism by which blue light damages the skin is not yet clear. Endoplasmic reticulum (ER) stress and autophagy are two mechanisms by which cells resist external interference factors and maintain cell homeostasis and normal function, and both can affect cell apoptosis. Interestingly, we have found that blue light (435 nm ~ 445 nm, 8000 lx, 6-24 h)-induced oxidative stress triggers the ER stress-CHOP (C/EBP homologous protein) signal and affects the protein levels of B-cell lymphoma-2 (Bcl-2) and Bcl2-associated X (Bax), thereby promoting apoptosis. In addition, blue light activates autophagy in skin cells, which intensifies cell death. When ER stress is inhibited, autophagy is subsequently inhibited, suggesting that blue light-induced autophagy is influenced by ER stress. These evidences suggest that blue light induces activation of reactive oxygen species (ROS)-ER stress-autophagy-apoptosis axis signaling, which further induces skin injury and apoptosis. This is the first report on the relationships among oxidative stress, ER stress, autophagy, and apoptosis in blue light-induced skin injury. Furthermore, we have studied the effect of hydrogen sulfide (H₂S) on blue light-induced skin damage, and found that exogenous H₂S can protect skin from blue light-induced damage by regulating the ROS-ER stress-autophagy-apoptosis axis. Our data shows that when we are exposed to blue light, such as sunbathing and jaundice treatment, H₂S may be developed as a protective agent.

Pathophysiological Responses of Pinna nobilis Individuals Enlightens the Etiology of Mass Mortality Situation in the Mediterranean Populations

Due to the rapid decrease of Pinna nobilis populations during the previous decades, this bivalve species, endemic in the Mediterranean Sea, is characterized as 'critically endangered'. In addition to human pressures, various pathogen infections have resulted in extended reduction, even population extinction. While Haplosporidium pinnae is characterized as one of the major causative agents, mass mortalities have also been attributed to Mycobacterium sp. and Vibrio spp. Due to limited knowledge concerning the physiological response of infected P. nobilis specimens against various pathogens, this study's aim was to investigate to pathophysiological response of P. nobilis individuals, originating from mortality events in the Thermaikos Gulf and Lesvos and Limnos islands (Greece), and their correlation to different potential pathogens detected in the diseased animals. In isolated tissues, several cellular stress indicators of the heat shock and immune response, apoptosis and autophagy, were examined. Despite the complexity and limitations in the study of P. nobilis mortality events, the present investigation demonstrates the cumulative negative effect of co-infection additionally with H. pinnae in comparison to the non-presence of haplosporidian parasite. In addition, impacts of global climate change affecting physiological performance and immune responses result in more vulnerable populations in infectious diseases, a phenomenon which may intensify in the future.

Cdk8 Kinase Module: A Mediator of Life and Death Decisions in Times of Stress

The Cdk8 kinase module (CKM) of the multi-subunit mediator complex plays an essential role in cell fate decisions in response to different environmental cues. In the budding yeast S. cerevisiae, the CKM consists of four conserved subunits (cyclin C and its cognate cyclin-dependent kinase Cdk8, Med13, and Med12) and predominantly negatively regulates a subset of stress responsive genes (SRG’s). Derepression of these SRG’s is accomplished by disassociating the CKM from the mediator, thus allowing RNA polymerase II-directed transcription. In response to cell death stimuli, cyclin C translocates to the mitochondria where it induces mitochondrial hyper-fission and promotes regulated cell death (RCD). The nuclear release of cyclin C requires Med13 destruction by the ubiquitin-proteasome system (UPS). In contrast, to protect the cell from RCD following SRG induction induced by nutrient deprivation, cyclin C is rapidly destroyed by the UPS before it reaches the cytoplasm. This enables a survival response by two mechanisms: increased ATP production by retaining reticular mitochondrial morphology and relieving CKM-mediated repression on autophagy genes. Intriguingly, nitrogen starvation also stimulates Med13 destruction but through a different mechanism. Rather than destruction via the UPS, Med13 proteolysis occurs in the vacuole (yeast lysosome) via a newly identified Snx4-assisted autophagy pathway. Taken together, these findings reveal that the CKM regulates cell fate decisions by both transcriptional and non-transcriptional mechanisms, placing it at a convergence point between cell death and cell survival pathways.

Adverse effects polystyrene microplastics exert on zebrafish heart - Molecular to individual level

In the present study the effects of sublethal concentrations of polystyrene microplastics (PS-MPs) on zebrafish were evaluated at multiple levels, related to fish activity and oxidative stress, metabolic changes and contraction parameters in the heart tissue. Zebrafish were fed for 21 days food enriched with PS-MPs (particle sizes 3-12 µm) and a battery of stress indices like DNA damage, lipid peroxidation, autophagy, ubiquitin levels, caspases activation, metabolite adjustments, frequency and force of ventricular contraction were measured in fish heart, parallel to fish swimming velocity. In particular, exposure to PS-MPs caused significant decrease in heart function and swimming competence, while enhanced levels of oxidative stress indices and metabolic adjustments were observed in the heart of challenged species. Among stress indices, DNA damage was more vulnerable to the effect of PS-MPs. Our results provide evidence on the multiplicity of the PS-MPs effects on cellular function, physiology and metabolic pathways and heart rate of adult fish and subsequent effects on fish activity and fish fitness thus enlightening MPs characterization as a potent environmental pollutant.

A concise review on the role of selenium for bone cancer applications

Cancer is one of the most challenging health problems in the world. Several clinical treatments have been developed, but all presenting several limitations. Among different types of cancer, bone cancer is less common, and limited new clinical treatment strategies have been proposed. Recently, a range of advanced materials has been investigated and applied for bone cancer treatment applications. However, due to the unique physiological properties of the bone tissue (a load-bearing tissue), the selection of the right type of material or the combination of suitable functional materials and base materials are critical. Selenium has been reported to present specific targeting inhibition effects on bone cancer without affecting the surrounding healthy tissue, revealing a huge potential for the development of new bone cancer treatment strategies. This paper presents a concise review on the use of selenium for bone cancer applications, discussing main synthesis methods, biocompatibility, and cytotoxicity aspects and the combination of selenium with a wide range of ceramics, metals, and polymers. Future perspectives and the novel concept of a dual-functional scaffold for both cancer treatment and new bone regeneration are also discussed.

Interconnections among major forms of regulated cell death

As a basic biological phenomenon of cells, regulated cell death (RCD) has irreplaceable influence on the occurrence and development of many processes of life and diseases. RCD plays an important role in the stability of the homeostasis, the development of multiple systems and the evolution of organisms. Thus comprehensively understanding of RCD is undoubtedly helpful in the innovation of disease treatment. Recently, research on the underlying mechanisms of the major forms of RCD, such as apoptosis, autophagy, necroptosis, pyroptosis, paraptosis and neutrophils NETosis has made significant breakthroughs. In addition, the interconnections among them have attracted increasing attention from global scholars in the field of life sciences. Here, recent advances in RCD research field are discussed.

Curcumin-Alleviated Osteoarthritic Progression in Rats Fed a High-Fat Diet by Inhibiting Apoptosis and Activating Autophagy via Modulation of MicroRNA-34a

Purpose

The mechanism underlying curcumin’s protective effect on osteoarthritis (OA) has not been clarified. This study aimed to determine whether curcumin exerts a chondroprotective effect by inhibiting apoptosis via upregulation of E2F1/PITX1 and activation of autophagy via the Akt/mTOR pathway by targeting microRNA-34a (miR-34a).

Methods

Male Sprague–Dawley rats were fed a normal diet (ND) or high-fat diet (HFD) for 28 weeks. Five rats from each diet group were selected randomly for histological analysis of OA characteristics. Rats fed a HFD were given a single intra-stifle joint injection of the miR-34a mimic agomir-34a or negative control agomir (NC), followed by weekly low-dose (200 μg/kg body weight) or high-dose (400 μg/kg body weight) curcumin intra-joint injections from weeks 29 to 32. The rats’ stifle joints were submitted to histological analysis and to an apoptotic assay. Expression of miR-34a was detected using a real-time RT-PCR. E2F1 and PITX1 protein levels were determined by Western blot analysis, and the expressions of Beclin1, LC3B, p62, phosphorylated (p)-Akt, and p-mTOR were measured using immunofluorescence analysis.

Results

We found that rats fed a HFD had OA-like lesions in their articular cartilage and had increased apoptosis of chondrocytes and decreased autophagy compared to rats fed a ND. Curcumin treatment alleviated OA changes, inhibited apoptosis, and upregulated autophagy. Agomir-34a treatment reduced E2F1, PITX1, Beclin1, and LC3B expression and increased p62, p-Akt, and p-mTOR expression in HFD-fed rats given low- or high-dose curcumin. Greater numbers of apoptotic cells, lesser expression of p62, p-Akt, and p-mTOR, and greater expression of E2F1, PITX1, and LC3B were observed in the agomir-34a and high-dose curcumin-treated group than in agomir-34a and low-dose curcumin-treated group.

Conclusion

Curcumin’s chondroprotective effect was mediated by its suppression of miR-34a, apparently by reducing apoptosis, via upregulation of E2F1/PITX1, and by augmenting autophagy, likely via the Akt/mTOR pathway.

Dexamethasone Downregulates Autophagy through Accelerated Turn-Over of the Ulk-1 Complex in a Trabecular Meshwork Cells Strain: Insights on Steroid-Induced Glaucoma Pathogenesis

Steroid-induced glaucoma is a severe pathological condition, sustained by a rapidly progressive increase in intraocular pressure (IOP), which is diagnosed in a subset of subjects who adhere to a glucocorticoid (GC)-based therapy. Molecular and clinical studies suggest that either natural or synthetic GCs induce a severe metabolic dysregulation of Trabecular Meshwork Cells (TMCs), an endothelial-derived histotype with phagocytic and secretive functions which lay at the iridocorneal angle in the anterior segment of the eye. Since TMCs physiologically regulate the composition and architecture of trabecular meshwork (TM), which is the main outflow pathway of aqueous humor, a fluid which shapes the eye globe and nourishes the lining cell types, GCs are supposed to trigger a pathological remodeling of the TM, inducing an IOP increase and retina mechanical compression. The metabolic dysregulation of TMCs induced by GCs exposure has never been characterized at the molecular detail. Herein, we report that, upon dexamethasone exposure, a TMCs strain develops a marked inhibition of the autophagosome biogenesis pathway through an enhanced turnover of two members of the Ulk-1 complex, the main platform for autophagy induction, through the Ubiquitin Proteasome System (UPS).

Autophagy Modulators in Cancer Therapy

Autophagy is a process of self-degradation that plays an important role in removing damaged proteins, organelles or cellular fragments from the cell. Under stressful conditions such as hypoxia, nutrient deficiency or chemotherapy, this process can also become the strategy for cell survival. Autophagy can be nonselective or selective in removing specific organelles, ribosomes, and protein aggregates, although the complete mechanisms that regulate aspects of selective autophagy are not fully understood. This review summarizes the most recent research into understanding the different types and mechanisms of autophagy. The relationship between apoptosis and autophagy on the level of molecular regulation of the expression of selected proteins such as p53, Bcl-2/Beclin 1, p62, Atg proteins, and caspases was discussed. Intensive studies have revealed a whole range of novel compounds with an anticancer activity that inhibit or activate regulatory pathways involved in autophagy. We focused on the presentation of compounds strongly affecting the autophagy process, with particular emphasis on those that are undergoing clinical and preclinical cancer research. Moreover, the target points, adverse effects and therapeutic schemes of autophagy inhibitors and activators are presented.

Autophagy Induction as a Host-Directed Therapeutic Strategy against Mycobacterium tuberculosis Infection

Tuberculosis (TB), a bacterialinfectious disease caused by Mycobacterium tuberculosis (M.tb), which causes significant mortality in humans worldwide. Current treatment regimen involve the administration of multiple antibiotics over the course of several months that contributes to patient non-compliance leading to relapse and the development of drug-resistant M.tb (MDR and XDR) strains. Together, these facts highlight the need for the development of shorter TB treatment regimens. Host-directed therapy (HDT) is a new and emerging concept that aims to augment host immune response using drugs/compounds with or without adjunct antibiotics against M.tb infection. Autophagy is a natural catabolic mechanism of the cell that involves delivering the cytosolic constituents to the lysosomes for degradation and recycling the components; thereby maintaining the cellular and energy homoeostasis of a cell. However, over the past decade, an improved understanding of the role of autophagy in immunity has led to autophagy activation by using drugs or agents. This autophagy manipulation may represent a promising host-directed therapeutic strategy for human TB. However, current clinical knowledge on implementing autophagy activation by drugs or agents, as a stand-alone HDT or as an adjunct with antibiotics to treat human TB is insufficient. In recent years, many reports on high-throughput drug screening and measurement of autophagic flux by fluorescence, high-content microscopy, flow cytometry, microplate reader and immunoblotting have been published for the discovery of drugs that modulate autophagy. In this review, we discuss the commonly used chemical screening approaches in mammalian cells for the discovery of autophagy activating drugs against M.tbinfection. We also summarize the various autophagy-activating agents, both pre-clinical candidates and compounds approved for advanced clinical investigation during mycobacterial infection. Finally, we discuss the opportunities and challenges in using autophagy activation as HDT strategy to improve TB outcome and shorten treatment regimen.

Polysaccharides from sporoderm-removed spores of Ganoderma lucidum induce apoptosis in human gastric cancer cells via disruption of autophagic flux

The sporoderm-broken spores of Ganoderma lucidum (G. lucidum) polysaccharide (BSGLP) have been demonstrated to inhibit carcinogenesis in several types of cancer. However, to the best of our knowledge, the anticancer effects of polysaccharides extracted from the newly developed sporoderm-removed spores of G. lucidum (RSGLP) have not been assessed. The present study first compared the anticancer effects of RSGLP and BSGLP in three gastric cancer cell lines and it was found that RSGLP was more potent than BSGLP in decreasing gastric cancer cell viability. RSGLP significantly induced apoptosis in AGS cells, accompanied by downregulation of Bcl-2 and pro-caspase-3 expression levels, and upregulation of cleaved-PARP. Furthermore, RSGLP increased LC3-II and p62 expression, indicative of induction of autophagy and disruption of autophagic flux in AGS cells. These results were further verified by combined treatment of AGS cells with the late-stage autophagy inhibitor chloroquine, or early-stage autophagy inducer rapamycin. Adenoviral transfection with mRFP-GFP-LC3 further confirmed that autophagic flux was inhibited by RSGLP in AGS cells. Finally, the present study demonstrated that the RSGLP-induced autophagy and disruption of autophagic flux disruption was, at least in part, responsible for RSGLP-induced apoptosis in AGS cells. The results of the present study demonstrated for the first time that RSGLP is more effective than BSGLP in inhibiting gastric cancer cell viability, and RSGLP may serve as a promising autophagy inhibitor in the management of gastric cancer.

Triptolide inhibits JAK2/STAT3 signaling and induces lethal autophagy through ROS generation in cisplatin‑resistant SKOV3/DDP ovarian cancer cells

Advanced and recurrent ovarian cancer has a poor prognosis and is frequently resistant to numerous therapeutics; thus, safe and effective drugs are needed to combat this disease. Previous studies have demonstrated that triptolide (TPL) exhibits anticancer and sensitization effects against cisplatin (DDP)-resistant ovarian cancer both in vitro and in vivo by inducing apoptosis; however, the involvement of autophagy induced by TPL in resistant ovarian carcinoma remains unclear. In the present study, the results revealed that TPL induced autophagy to facilitate SKOV3/DDP ovarian cancer cell death. The xenograft experiment revealed that the autophagy inhibitor CQ significantly reduced TPL-mediated chemosensitization and tumor growth inhibition. Mechanically, TPL-induced autophagy in SKOV3/DDP cells was associated with the induction of ROS generation and inhibition of the Janus kinase 2 (JAK2)/signal transducer and activator of transcription-3 (STAT3) pathway. The inhibitory effect of TPL on the JAK2/STAT3 pathway could be restored in the presence of the antioxidant NAC. Furthermore, it was further determined that TPL disrupted the interaction between Mcl-1 and Beclin1, which was prevented by the JAK2/STAT3 signaling activator IL-6. Overall, the present results revealed a novel molecular mechanism whereby TPL induced lethal autophagy through the ROS-JAK2/STAT3 signaling cascade in SKOV3/DDP cells. The present study has provided the groundwork for future application of TPL in the treatment of ovarian cancer.

Molecular Action of Polyphenols in Leukaemia and Their Therapeutic Potential

Leukaemia is a malignant disease of the blood. Current treatments for leukaemia are associated with serious side-effects. Plant-derived polyphenols have been identified as potent anti-cancer agents and have been shown to work synergistically with standard chemotherapy agents in leukaemia cell lines. Polyphenols have multiple mechanisms of action and have been reported to decrease cell proliferation, arrest cell cycle and induce apoptosis via the activation of caspase (3, 8 and 9); the loss of mitochondrial membrane potential and the release of cytochrome c. Polyphenols have been shown to suppress activation of transcription factors, including NF-kB and STAT3. Furthermore, polyphenols have pro-oxidant properties, with increasing evidence that polyphenols inhibit the antioxidant activity of glutathione, causing oxidative DNA damage. Polyphenols also induce autophagy-driven cancer cell death and regulate multidrug resistance proteins, and thus may be able to reverse resistance to chemotherapy agents. This review examines the molecular mechanism of action of polyphenols and discusses their potential therapeutic targets. Here, we discuss the pharmacological properties of polyphenols, including their anti-inflammatory, antioxidant, anti-proliferative, and anti-tumour activities, and suggest that polyphenols are potent natural agents that can be useful therapeutically; and discuss why data on bioavailability, toxicity and metabolism are essential to evaluate their clinical use.

Signalling pathways linking cysteine cathepsins to adverse cardiac remodelling

Adverse cardiac remodelling clinically manifests as deleterious changes to heart architecture (size, mass and geometry) and function. These changes, which include alterations to ventricular wall thickness, chamber dilation and poor contractility, are important because they progressively drive patients with cardiac disease towards heart failure and are associated with poor prognosis. Cysteine cathepsins contribute to key signalling pathways involved in adverse cardiac remodelling including synthesis and degradation of the cardiac extracellular matrix (ECM), cardiomyocyte hypertrophy, impaired cardiomyocyte contractility and apoptosis. In this review, we highlight the role of cathepsins in these signalling pathways as well as their translational potential as therapeutic targets in cardiac disease.

Caspase-8 knockdown suppresses apoptosis, while induces autophagy and chemo-sensitivity in non-small cell lung cancer cells

PURPOSE

Drug resistance remains a major cause of relapse and therapeutic failure in non-small cell lung cancer (NSCLC). The purpose of this investigation is to explore the relationship between caspase-8 level and chemo-sensitivity, as well as its underlying mechanism in NSCLC cells.

METHODS

NSCLC cell line, A549 cells was used to investigate the influence of caspase-8 on the biological behavior in vitro. The abundance of caspase-8 in A549 cells was manipulated by transfection lentivirus containing specific caspase-8 short hairpin RNA (sh-caspase-8) and caspase-8 overexpressed plasmid. Cell viability and the percentage of apoptotic cells was quantified using cell counting kit-8 (CCK-8) assay and flow cytometry following Annexin V-FITC/PI staining, respectively. The formation of acidic vesicle organelles (AVOs) was examined by acridine orange staining and visualized under a fluorescence microscope. The mRNA and protein levels of relative genes were determined by qRT-PCR and western blotting.

RESULTS

Our results indicated that cells infected with sh-caspase-8 exhibited high knockdown efficiency. Knockdown of caspase-8 significantly reduced apoptosis of A549 cells. As evidenced by the decreased number of apoptotic cells and the reduction of Bcl-2/bax ratio. Interestingly, caspase-8 knockdown also enhanced autophagy in A549 cells. Additionally, knockdown of caspase-8 reduced the doxorubicin, carboplatin, cisplatin, and etoposide sensitivity towards A549 cells.

CONCLUSION

In summary, our results revealed that knockdown of caspase-8 could promote cell growth and autophagy, while reduce chemo-sensitivity and apoptotic cell death. These finding suggest caspase-8 might serve as a potential target to improve the chemo-sensitivity for NSCLC patients in clinical setting.

C21 Fraction Refined from Marsdenia tenacissima-Induced Apoptosis is Enhanced by Suppression of Autophagy in Human Gastric Cell Lines

C21 steroidal glycosides have been extensively reported for treating several types of cancer and are widely found in Marsdenia tenacissima. In this study, a C21 fraction was synthesized from M. tenacissima, and its anti-cancer potency was assessed against in vitro gastric cell lines BGC-823, SGC-7901, and AGS. Significant growth inhibition and cell cycle arrest were observed in C21 fraction-treated gastric cancer cells. The results of apoptotic staining techniques in C21 fraction-treated gastric cells were confirmed with excess reactive oxygen species generation. Moreover, SOD and H₂O₂ levels were increased by C21 fraction, especially when combined with chloroquine (CQ). The apoptotic inducing potential of C21 fraction was also evidenced by upregulation of proapoptotic proteins cleaved-PARP and BAX and downregulation of antiapoptotic proteins Bcl-2 and p-AKT by western blot, especially in the presence of the autophagy inhibitor CQ. The results showed that the apoptosis of gastric cancer cells caused by C21 fraction was enhanced by inhibiting autophagy. The current findings reveal a new mechanism for the antitumor activity of C21 fraction on gastric cancer.

LsGRP1, a class II glycine-rich protein of Lilium, confers plant resistance via mediating innate immune activation and inducing fungal programmed cell death

Defence-related LsGRP1 is a leaf-specific plant class II glycine-rich protein (GRP) involved in salicylic acid-induced systemic resistance against grey mould caused by necrotrophic Botrytis elliptica in lily (Lilium) cultivar Stargazer. The C-terminal region of LsGRP1 (LsGRP1^C ) can inhibit fungal growth in vitro via a mechanism of inducing fungal apoptosis programmed cell death (PCD). In this study, the role of LsGRP1 in induced defence mechanism was investigated using LsGRP1-silenced Stargazer lily and LsGRP1-transgenic Arabidopsis thaliana. LsGRP1 silencing in lily was found to slightly inhibit plant growth and greatly increase the susceptibility to B. elliptica by suppressing callose deposition and early reactive oxygen species (ROS) accumulation. In contrast, LsGRP1-transgenic Arabidopsis showed higher resistance to Botrytis cinerea and also to Pseudomonas syringae pv. tomato DC3000 as compared to the wild type, accompanied with the enhancement of callose deposition and ROS accumulation. Additionally, LsGRP1 silencing increased plant cell death caused by B. elliptica secretion and reduced pathogen-associated molecular pattern (PAMP)-triggered defence activation in Stargazer lily. Consistently, LsGRP1 expression boosted PAMP-triggered defence responses and effector recognition-induced hypersensitive response in Arabidopsis. Moreover, fungal apoptosis PCD triggered by LsGRP1 in an LsGRP1^C -dependent manner was demonstrated by leaf infiltration with LsGRP1^C -containing recombinant proteins in Stargazer lily. Based on these results, we presume that LsGRP1 plays roles in plant defence via functioning as a pathogen-inducible switch for plant innate immune activation and acting as a fungal apoptosis PCD inducer to combat pathogen attack.

Autophagy Upregulation by the TFEB Inducer Trehalose Protects against Oxidative Damage and Cell Death Associated with NRF2 Inhibition in Human RPE Cells

Trehalose is a natural dietary molecule that has shown antiaging and neuroprotective effects in several animal models of neurodegenerative diseases. The role of trehalose in the management of age-related macular degeneration (AMD) is yet to be investigated and whether trehalose could be a remedy for the treatment of diseases linked to oxidative stress and NRF2 dysregulation. Here, we showed that incubation of human retinal pigment epithelial (RPE) cells with trehalose enhanced the mRNA and protein expressions of TFEB, autophagy genes ATG5 and ATG7, as well as protein expressions of macroautophagy markers, LC3B and p62/SQTM1, and the chaperone-mediated autophagy (CMA) receptor LAMP2. Cathepsin D, a hydrolytic lysosomal enzyme, was also increased by trehalose, indicating higher proteolytic activity. Moreover, trehalose upregulated autophagy flux evident by an increase in the endogenous LC3B level, and accumulation of GFP-LC3B puncta and free GFP fragments in GFP-LC3 - expressing cells in the presence of chloroquine. In addition, the mRNA levels of key molecular targets implicated in RPE damage and AMD, such as vascular endothelial growth factor- (VEGF-) A and heat shock protein 27 (HSP27), were downregulated, whereas NRF2 was upregulated by trehalose. Subsequently, we mimicked in vitro AMD conditions using hydroquinone (HQ) as the oxidative insult on RPE cells and evaluated the cytoprotective effect of trehalose compared to vehicle treatment. HQ depleted NRF2, increased oxidative stress, and reduced the viability of cells, while trehalose pretreatment protected against HQ-induced toxicity. The cytoprotection by trehalose was dependent on autophagy but not NRF2 activation, since autophagy inhibition by shRNA knockdown of ATG5 led to a loss of the protective effect. The results support the transcriptional upregulation of TFEB and autophagy by trehalose and its protection against HQ-induced oxidative damage in RPE cells. Further investigation is, therefore, warranted into the therapeutic value of trehalose in alleviating AMD and retinal diseases associated with impaired NRF2 antioxidant defense.

Activation of Alpha-7 Nicotinic Acetylcholine Receptors (α7nAchR) Promotes the Protective Autophagy in LPS-Induced Acute Lung Injury (ALI) In Vitro and In Vivo

The release of inflammatory cytokines and chemokines and autophagy has been reported to be involved in the pathogenic mechanism of acute lung injury (ALI). Reportedly, alpha-7 nicotinic acetylcholine receptors (α7nAchR) might play a protective role in LPS-induced ALI. In the current research, we established LPS-induced ALI model in mice and α7nAchR agonist PNU-282987 improved LPS-induced injury. In MH-S cells, LPS stimulation inhibited, whereas α7nAchR agonist PNU-282987 enhanced the autophagy. α7nAchR agonist PNU-282987 protected MH-S cells from LPS-induced inflammation by reducing the concentrations of IL-6, TNF-α, and IL-1β. Finally, LPS stimulation dramatically inhibited MH-S cell viability but enhanced cell apoptosis, whereas PNU-282987 treatment exerted opposite effects; α7nAchR might regulate the cellular homeostasis via affecting the crosstalk between the autophagy and apoptosis in MH-S cells; in other words, α7nAChR agonist enhances MH-S cell autophagy and inhibits MH-S cell apoptosis. In conclusion, α7nAchR promote the protective autophagy in LPS-induced ALI model in mice and MH-S cells. The application of α7nAchR agonist is considered a potent target for LPS-induced ALI, which needs further clinical investigation.

Modulation of autophagy for neuroprotection and functional recovery in traumatic spinal cord injury

Spinal cord injury (SCI) is a serious central nervous system trauma that leads to loss of motor and sensory functions in the SCI patients. One of the cell death mechanisms is autophagy, which is 'self-eating' of the damaged and misfolded proteins and nucleic acids, damaged mitochondria, and other impaired organelles for recycling of cellular building blocks. Autophagy is different from all other cell death mechanisms in one important aspect that it gives the cells an opportunity to survive or demise depending on the circumstances. Autophagy is a therapeutic target for alleviation of pathogenesis in traumatic SCI. However, functions of autophagy in traumatic SCI remain controversial. Spatial and temporal patterns of activation of autophagy after traumatic SCI have been reported to be contradictory. Formation of autophagosomes following therapeutic activation or inhibition of autophagy flux is ambiguous in traumatic SCI studies. Both beneficial and harmful outcomes due to enhancement autophagy have been reported in traumatic SCI studies in preclinical models. Only further studies will make it clear whether therapeutic activation or inhibition of autophagy is beneficial in overall outcomes in preclinical models of traumatic SCI. Therapeutic enhancement of autophagy flux may digest the damaged components of the central nervous system cells for recycling and thereby facilitating functional recovery. Many studies demonstrated activation of autophagy flux and inhibition of apoptosis for neuroprotective effects in traumatic SCI. Therapeutic induction of autophagy in traumatic SCI promotes axonal regeneration, supporting another beneficial role of autophagy in traumatic SCI. In contrast, some other studies demonstrated that disruption of autophagy flux in traumatic SCI strongly correlated with neuronal death at remote location and impaired functional recovery. This article describes our current understanding of roles of autophagy in acute and chronic traumatic SCI, cross-talk between autophagy and apoptosis, therapeutic activation or inhibition of autophagy for promoting functional recovery, and future of autophagy in traumatic SCI.

TAF1L promotes development of oral squamous cell carcinoma via decreasing autophagy-dependent apoptosis

This study focused on investigating the relationships of TAF1L expression and clinical features or pathological stages of oral squamous cell carcinoma (OSCC), and its potential roles of TAF1L on OSCC development. Western blot and immunohistochemical staining were used to detect TAF1L expression in OSCC tissues and cells. Effects of TAF1L on OSCC cells in vitro were examined by cell proliferation assay, wound healing assay, transwell chamber assay, flow cytometry analysis and siRNA technique. Cellular key proteins related to cell autophagy and apoptosis were evaluated by Western blot and immunofluorescent staining. Moreover, functions of TAF1L on OSCC process were observed in nude mouse model. Testing results showed that expression of TAF1L protein was higher in OSCC tissues than that in normal oral epithelial or paracancerous tissues. Additionally, the level of TAF1L protein expression was upregulated in OSCC cell lines, compared to that in normal oral epithelial cells. Furthermore, cell proliferation, migration, autophagy and apoptosis were modulated post siRNA-TAF1L treatment in vitro. Especially, TAF1L knockdown-induced apoptotic activation on OSCC cells could be rescued by autophagic activator (Rapamycin). Moreover, that overexpression of TAF1L protein could promote the growth of OSCC cell xenografts was confirmed in nude mouse model. Taken together, it suggests that TAF1L may facilitate OSCC cells to escape cell apoptosis via autophagic activation for enhancing OSCC development.

Autophagy and apoptosis are regulated by stress on Bcl2 by AMBRA1 in the endoplasmic reticulum and mitochondria

BACKGROUND

Autophagy and apoptosis are two important physiological processes that determine cell survival or death in response to different stress signals. The regulatory mechanisms of these two processes share B-cell lymphoma-2 family proteins and AMBRA1, which are present in both the endoplasmic reticulum and mitochondria. B-cell lymphoma-2 family proteins sense different stresses and interact with AMBRA1 to regulate autophagy and apoptosis, which are respectively mediated by Beclin1 and Caspases. Therefore, we investigated how different levels of stress on B-cell lymphoma-2 family proteins that bind to AMBRA1 in the endoplasmic reticulum and mitochondria regulate the switch from autophagy to apoptosis.

METHODS

In this paper, we considered the responses of B-cell lymphoma-2 family proteins, which bind to AMBRA1 in both the endoplasmic reticulum and mitochondria, to two different levels of stress in a model originally proposed by Kapuy et al. We investigated how these two stress levels affect the transition from autophagy to apoptosis and their effects on apoptosis activation over time. Additionally, we analyzed how the feedback regulation in this model affects the bifurcation diagrams of two levels of stress and cell fate decisions between autophagy and apoptosis.

RESULTS

Autophagy is activated for minor stress in mitochondria regardless of endoplasmic reticulum stress, while apoptosis is activated for only significant stress in mitochondria. Apoptosis is only sensitive to mitochondria stress. The time duration before apoptosis activation is longer in the presence of high AMBRA1 levels with high endoplasmic reticulum and mitochondria stress. AMBRA1 can compete with B-cell lymphoma-2 family proteins to bind and activate Beclin1 and thus promote the autophagy process for a long time before apoptosis. Furthermore, apoptosis is prone to occur with increasing activation of Caspases, inactivation of Beclin1-A and the Michaelis constant of Caspases.

CONCLUSION

A novel mathematical model has been developed to understand the complex regulatory mechanisms of autophagy and apoptosis. Our model may be applied to further autophagy-apoptosis dynamic modeling experiments and simulations.

Anthraquinones and autophagy - Three rings to rule them all?

In order to overcome therapy resistance in cancer, scientists search in nature for novel lead structures for the development of improved chemotherapeutics. Anthraquinones belong to a class of tricyclic organic natural compounds with promising anti-cancer effects. Anthraquinone derivatives are rich in structural diversity, and exhibit pleiotropic properties, among which the modulation of autophagy seems promising in the context of overcoming cancer-therapy resistance. Among the most promising derivatives in this regard are emodin, aloe emodin, rhein, physcion, chrysophanol and altersolanol A. On the molecular level, these compounds target autophagy via different upstream pathways including the AKT/mTOR-axis and transcription of autophagy-related proteins. The role of autophagy is pro-survival as well as cell death-promoting, depending on derivatives and their cell type specificity. This review summarizes observed effects of anthraquinone derivatives on autophagy and discusses targeted pathways and crosstalks. A cumulative knowledge about this topic paves the way for further research on modes of action, and aids to find a therapeutic window of anthraquinones in cancer-therapy.