Natural Products Targeting ER Stress, and the Functional Link to Mitochondria

Naringenin, a flavanone constituent from Sea buckthorn pulp extract, prevents ultraviolet (UV)-B radiation-induced skin damage via alleviation of impaired mitochondrial dynamics mediated inflammation in human dermal fibroblasts and Balb/c mice models

Ultraviolet-B (UV-B) irradiation has been reported to cause oxidative stress and inflammation-mediated skin photo-damage. Furthermore, mitochondrial dynamics have been implicated to play a critical role in these processes. For the first time, we describe in this study how UVB-induced aberrant mitochondrial dynamics and inflammation interact in primary human dermal fibroblasts (HDFs). Our findings demonstrated that UV-B irradiation induced -impairment in mitochondrial dynamics by increasing mitochondrial fragmentation in HDFs. Imbalanced mitochondrial dynamics lead to the activation of NFкB and pro-inflammatory cytokines. The current study further aimed to investigate the protective effect of Naringenin (a naturally occurring flavonoid isolated from Sea buckthorn fruit pulp) against UV-B-induced mitochondrial fragmentation and inflammation in HDFs and Balb/c mice. Although Naringenin has been shown to have anti-inflammatory and antioxidant potential, its effects and mechanisms of action on UVB-induced inflammation remained unclear. We observed that Naringenin restored the UV-B-induced imbalance in mitochondrial fission and fusion in HDFs. It also inhibited the phosphorylation of NFкB and reduced the generation of pro-inflammatory cytokines. Naringenin also alleviated UV-B-induced oxidative stress by scavenging the reactive oxygen species and up-regulating the cellular antioxidant enzymes (Catalase and Nrf2). Topical application of Naringenin to the dorsal skin of Balb/c mice exposed to UV-B radiation prevented mitochondrial fragmentation and progression of inflammatory responses. Naringenin treatment prevented neutrophil infiltration and epidermal thickening in mice's skin. These findings provide an understanding for further research into impaired mitochondrial dynamics as a therapeutic target for UV-B-induced inflammation. Our findings imply that Naringenin could be developed as a therapeutic remedy against UVB-induced inflammation.

Anticancer Therapies Based on Oxidative Damage: Lycium barbarum Inhibits the Proliferation of MCF-7 Cells by Activating Pyroptosis through Endoplasmic Reticulum Stress

Lycium barbarum, commonly recognized as goji berry or wolfberry, is highly appreciated not only for its organoleptic and nutritional properties but also as an important source of bioactive compounds such as polysaccharides, carotenoids, phenolics, and various other non-nutritive compounds. These constituents give it a multitude of health benefits, including antioxidant, anti-inflammatory, and anticancer properties. However, the precise biochemical mechanisms responsible for its anticancer effects remain unclear, and the comprehensive composition of goji berry extracts is often insufficiently explored. This study aimed to investigate the biochemical pathways modulated in breast cancer cells by an ethanolic extract of Lycium barbarum fruit (LBE). Following metabolomic profiling using UHPLC-HRMS/MS, we assessed the antitumoral properties of LBE on different breast cancer cell lines. This investigation revealed that LBE exhibited cytotoxic effects, inducing a pro-oxidant effect that triggered pyroptosis activation through endoplasmic reticulum (ER) stress and subsequent activation of the P-IRE1α/XBP1/NLRP3 axis in MCF-7 cells. In addition, LBE did not display cytotoxicity toward healthy human cells but demonstrated antioxidant properties by neutralizing ROS generated by doxorubicin. These findings underscore the potential of LBE as a highly promising natural extract in cancer therapy.

Chang'an decoction alleviates endoplasmic reticulum stress by regulating mitofusin 2 to improve colitis

OBJECTIVE

To evaluate the protective effects of Chang'an decoction (, CAD) on colitis, and investigate the potential mechanisms underlying these effects from the perspectives of endoplasmic reticulum (ER) stress induced by mitofusin 2 (MFN2).

METHODS

The composition of CAD was identified by liquid chromatography-mass spectrometry technology. A mice model of dextran sulfate sodium (DSS) induced colitis was established and therapeutic effects of CAD were determined by detecting body weight, disease activity index, colon length and histopathological changes. Then, the expression levels of MFN2, ER stress markers and Nucleotide-binding domain and leucine-rich repeat protein3 (NLRP3) relevant proteins were detected by polymerase chain reaction (PCR), Western blot, immunohistochemistry and immunofluorescence staining. Subsequently, knockdown and overexpression cell model were constructed to further investigate the underlying mechanism of MFN2 mediating ER stress and energy metabolism by PCR, Western blot, electron microscopy and reactive oxygen species (ROS) staining. Finally, inflammatory indicator and tight junction proteins were measured by PCR and immunofluorescence staining to evaluate the protective effects of CAD.

RESULTS

Results showed that the indispensable regulatory role of MFN2 in mediating ER stress and mitochondrial damage was involved in the protective effects of CAD on colitis in mice fed with DSS. Network pharmacology analysis also revealed CAD may play a protective effect on colitis by affecting mitochondrial function. In addition, our data also suggested a causative role for MFN2 in the development of inflammatory responses and energy metabolic alterations by constructing a knockdown and overexpression cell model whereby alter proper ER-mitochondria interaction in Caco-2 cells. Furthermore, relative expression analyses of ER stress markers and NLRP3 inflammasome showed the onset of ER stress and activation of NLRP3 inflammasome, which is consistent with the above findings. In contrast, intervention of CAD could improve the mucosal barrier integrity and colonic inflammatory response effectively through inhibiting ER stress response mediated by MFN2.

CONCLUSION

CAD could alleviate ER stress by regulating MFN2 to exert therapeutic effects on DSS-induced colitis, which might provide an effective natural therapeutic approach for the treatment of ulcerative colitis.

Direct neuronal reprogramming of NDUFS4 patient cells identifies the unfolded protein response as a novel general reprogramming hurdle

Mitochondria account for essential cellular pathways, from ATP production to nucleotide metabolism, and their deficits lead to neurological disorders and contribute to the onset of age-related diseases. Direct neuronal reprogramming aims at replacing neurons lost in such conditions, but very little is known about the impact of mitochondrial dysfunction on the direct reprogramming of human cells. Here, we explore the effects of mitochondrial dysfunction on the neuronal reprogramming of induced pluripotent stem cell (iPSC)-derived astrocytes carrying mutations in the NDUFS4 gene, important for Complex I and associated with Leigh syndrome. This led to the identification of the unfolded protein response as a major hurdle in the direct neuronal conversion of not only astrocytes and fibroblasts from patients but also control human astrocytes and fibroblasts. Its transient inhibition potently improves reprogramming by influencing the mitochondria-endoplasmic-reticulum-stress-mediated pathways. Taken together, disease modeling using patient cells unraveled novel general hurdles and ways to overcome these in human astrocyte-to-neuron reprogramming.

Mitochondria-associated endoplasmic reticulum membrane as a mediator of vanadium-induced endoplasmic reticulum quality control in duck brains

Vanadium (V) plays a crucial role in normal cells, but excess V causes multi-organ toxicity, including neurotoxicity. Mitochondria-associated endoplasmic reticulum membrane (MAM) is a dynamic structure between endoplasmic reticulum (ER) and mitochondria that mediates ER quality control (ERQC). To explore the effects of excess V on MAM and ERQC in the brain, 72 ducks were randomly divided into two groups: the control group (basal diet) and the V group (30 mg V/kg basal diet). On days 22 and 44, brain tissues were collected for histomorphological observation and determination of trace element contents. In addition, the mRNA and protein levels of MAM and ERQC-related factors in the brain were analyzed. Results show that excessive V causes the imbalance of trace elements, the integrity disruption of MAM, rupture of ER and autophagosomes formation. Moreover, it inhibits IP3R and VDAC1 co-localization, down-regulates the expression levels of MAM-related factors, but up-regulates the expression levels of ERQC and autophagy related factors. Together, results indicate that V exposure causes disruption of MAM and activates ERQC, which is further causing autophagy.

Relevance of the endoplasmic reticulum-mitochondria axis in cancer diagnosis and therapy

Dynamic interactions between organelles are responsible for a variety of intercellular functions, and the endoplasmic reticulum (ER)-mitochondrial axis is recognized as a representative interorganelle system. Several studies have confirmed that most proteins in the physically tethered sites between the ER and mitochondria, called mitochondria-associated ER membranes (MAMs), are vital for intracellular physiology. MAM proteins are involved in the regulation of calcium homeostasis, lipid metabolism, and mitochondrial dynamics and are associated with processes related to intracellular stress conditions, such as oxidative stress and unfolded protein responses. Accumulating evidence has shown that, owing to their extensive involvement in cellular homeostasis, alterations in the ER-mitochondrial axis are one of the etiological factors of tumors. An in-depth understanding of MAM proteins and their impact on cell physiology, particularly in cancers, may help elucidate their potential as diagnostic and therapeutic targets for cancers. For example, the modulation of MAM proteins is utilized not only to target diverse intracellular signaling pathways within cancer cells but also to increase the sensitivity of cancer cells to anticancer reagents and regulate immune cell activities. Therefore, the current review summarizes and discusses recent advances in research on the functional roles of MAM proteins and their characteristics in cancers from a diagnostic perspective. Additionally, this review provides insights into diverse therapeutic strategies that target MAM proteins in various cancer types.

Intricate subcellular journey of nanoparticles to the enigmatic domains of endoplasmic reticulum

It is evident that site-specific systemic drug delivery can reduce side effects, systemic toxicity, and minimal dosage requirements predominantly by delivering drugs to particular pathological sites, cells, and even subcellular structures. The endoplasmic reticulum (ER) and associated cell organelles play a vital role in several essential cellular functions and activities, such as the synthesis of lipids, steroids, membrane-associated proteins along with intracellular transport, signaling of Ca2+, and specific response to stress. Therefore, the dysfunction of ER is correlated with numerous diseases where cancer, neurodegenerative disorders, diabetes mellitus, hepatic disorder, etc., are very common. To achieve satisfactory therapeutic results in certain diseases, it is essential to engineer delivery systems that can effectively enter the cells and target ER. Nanoparticles are highly biocompatible, contain a variety of cargos or payloads, and can be modified in a pliable manner to achieve therapeutic effectiveness at the subcellular level when delivered to specific organelles. Passive targeting drug delivery vehicles, or active targeting drug delivery systems, reduce the nonselective accumulation of drugs while reducing side effects by modifying them with small molecular compounds, antibodies, polypeptides, or isolated bio-membranes. The targeting of ER and closely associated organelles in cells using nanoparticles, however, is still unsymmetrically understood. Therefore, here we summarized the pathophysiological prospect of ER stress, involvement of ER and mitochondrial response, disease related to ER dysfunctions, essential therapeutics, and nanoenabled modulation of their delivery to optimize therapy.

Isoliquiritigenin pretreatment regulates ER stress and attenuates cisplatin-induced nephrotoxicity in male Wistar rats

Cisplatin (CP) is a chemotherapeutic drug used to treat solid tumors. However, studies have revealed its nephrotoxic effect. Oxidative stress, endoplasmic reticulum (ER) stress, and mitochondrial dysfunction are involved in CP-induced renal damage. Thus, preconditioning (hormetic effect) of ER stress is a strategy to prevent CP-induced renal damage. On the other hand, isoliquiritigenin (IsoLQ) is recognized as a flavonoid with antioxidant properties and an inducer of ER stress. Therefore, we evaluated the ER stress-inducing capacity of IsoLQ and its possible protective effect against CP-induced nephrotoxicity in adult male Wistar rats. The findings reflected that IsoLQ pretreatment might decrease renal damage by reducing plasma creatinine and blood urea nitrogen levels in animals with CP-induced nephrotoxicity. These may be associated with IsoLQ activating ER stress and unfolded protein response (UPR). We found increased messenger RNA levels of the ER stress marker glucose-related protein 78 kDa (GRP78). In addition, we also found that pretreatment with IsoLQ reduced the levels of CCAAT/enhancer-binding protein-homologous protein (CHOP) and X-box-binding protein 1 (XBP1) in the renal cortex, reflecting that IsoLQ can regulate the UPR and activation of the apoptotic pathway. Moreover, this preconditioning with IsoLQ of ER stress had oxidative stress-regulatory effects, as it restored the activity of glutathione peroxidase and glutathione reductase enzymes. Finally, IsoLQ modifies the protein expression of mitofusin 2 (Mfn-2) and voltage-dependent anion channel (VDAC). In conclusion, these data suggest that IsoLQ pretreatment has a nephroprotective effect; it could functionally regulate the ER and mitochondria and reduce CP-induced renal damage by attenuating hormesis-mediated ER stress.

Evaluation of the therapeutic effects of arbutin on cisplatin-induced ovarian toxicity in rats through endoplasmic reticulum stress and Nrf2 pathway

Arbutin (ARB) is a glycosylated hydroquinone with potent antioxidant effects. Although cisplatin (CP) is widely used in chemotherapy, its toxicity in healthy tissues, including ovotoxicity, is an insurmountable problem. This study aimed to evaluate the therapeutic effect of ARB against CP-related ovototoxicity by including nuclear factor erythroid 2-related factor 2 (Nrf2) pathway in rats for the first time. Rats treated one dose of CP (5 mg/kg) on the first day, followed by ARB (5 and 10 mg/kg) for three days. Serum reproductive hormone levels were determined using ELISA kits. Oxidative stress (OS), inflammation, endoplasmic reticulum stress (ERS) and apoptosis markers in ovarian tissue were also determined colorimetrically. In addition, how CP affects Nrf2 pathway and the effect of ARB on this situation were also addressed. ARB treatment reduced the levels of markers of OS, inflammation, ERS and apoptosis in ovarian tissue of CP-stimulated animals. ARB regenerated the depleted antioxidant system by triggering Nrf2 pathway in the ovarian tissues of animals stimulated by CP. Histological findings also supported the therapeutic efficacy of ARB. The results indicate that ARB may have therapeutic effects against CP-induced reproductive toxicity with its Nrf2 activator potential. ARB should be tested in more extensive studies as a new generation chemopreventive candidate molecule.

Undesirable ER stress induced by bavachin contributed to follicular atresia in zebrafish ovary

Fructus psoraleae (FP) is a commonly used herb with potential reproductive toxicity. Bavachin (BV), one of essential active ingredients of FP, was found to exhibit estrogenic activity, but its effect on female reproductive system remains unknown. In this study, the impact of BV on the female zebrafish reproductive system and underlying molecular mechanism were determined in vivo and ex vivo. The results showed that BV could accumulate in zebrafish ovary, leading to obvious follicular atresia and increase in gonadal index and vitellogenin content. Endoplasmic reticulum (ER) swelling and hypertrophy were observed in the BV-treated zebrafish ovary, accompanied by an increase in the expressions of ER stress and unfolded protein response (UPR) related genes, namely atf6, ire-1α and xbp1s. In the ex vivo study, BV was found to decrease the survival rate and maturation rate of oocytes, while increasing the expression of Ca2+. Additionally, BV led to an elevation in the level of estrogen receptor ESR1 and the expressions of genes involved in ER stress and UPR, including atf6, ire-1α, xbp1s, chop and perk. Moreover, molecular docking revealed that BV could directly bind to immunoglobulin heavy chain binding protein (BiP) and estrogen receptor 1 (ESR1). Besides, the alterations induced by BV could be partially reversed by fulvestrant (FULV) and 4-phenylbutyric acid (4-PBA), respectively. Thus, long-termed BV-containing medicine treatment could generate reproductive toxicity in female zebrafish by causing follicular atresia through BiP- and ESR-mediated ER stress and UPR, providing a potential target for the prevention of reproductive toxicity caused by BV.

Probiotic effects of Lactococcus lactis and Leuconostoc mesenteroides on stress and longevity in Caenorhabditis elegans

The short lifespan of Caenorhabditis elegans enables the efficient investigation of probiotic interventions affecting stress and longevity involving the potential therapeutic value of Lactococcus lactis and Leuconostoc mesenteroides isolated from organic basil. The lactic acid bacteria were cultured from the produce collected from a local grocery store in Tulsa, Oklahoma, and then identified through 16S rDNA sequencing and biochemical tests. To dive deep into this analysis for potential probiotic therapy, we used fluorescent reporters that allow us to assess the differential induction of multiple stress pathways such as oxidative stress and the cytoplasmic, endoplasmic reticulum, and the mitochondrial unfolded protein response. This is combined with the classic health span measurements of survival, development, and fecundity, allowing a wide range of organismal observations of the different communities of microbes supported by probiotic supplementation with Lactococcus lactis and Leuconostoc mesenteroides. These strains were initially assessed in relation to the Escherichia coli feeding strain OP50 and the C. elegans microbiome. The supplementation showed a reduction in the median lifespan of the worms colonized within the microbiome. This was unsurprising, as negative results are common when probiotics are introduced into healthy microbiomes. To further assess the supplementation potential of these strains on an unhealthy (undifferentiated) microbiome, the typical axenic C. elegans diet, OP50, was used to simulate this single-species biome. The addition of lactic acid bacteria to OP50 led to a significant improvement in the median and overall survival in simulated biomes, indicating their potential in probiotic therapy. The study analyzed the supplemented cultures in terms of C. elegans' morphology, locomotor behavior, reproduction, and stress responses, revealing unique characteristics and stress response patterns for each group. As the microbiome's influence on the health span gains interest, the study aims to understand the microbiome relationships that result in differential stress resistance and lifespans by supplementing microbiomes with Lactococcus lactis and Leuconostoc mesenteroides isolated from organic basil in C. elegans.

Cycloartane triterpenoid from Euphorbia macrostegia modulates ER stress signaling pathways to induce apoptosis in MDA-MB231 and MCF-7 breast cancer cell lines

Unfolded protein response (UPR) is involved in breast cancer (BC) progression and drug resistance. Many natural products (NPs) could modulate UPR and used for therapeutic purposes. Herein, we aimed to investigate the molecular mechanism of Cycloart-23E-ene-3β, 25-diol (Cycloart-E25), cytotoxicity, as a NP extracted from Euphorbia macrostegia and focused on endoplasmic-reticulum stress (ERS) and UPR signaling pathways. Reactive oxygen species (ROS) were probed by DCFDA fluorescence dye. Apoptosis was assayed by annexin V/propidium iodide (PI), immunoblotting of anti- and proapoptotic, Bcl-2 and Bax proteins, and mitochondrial transmembrane potential (ΔΨm) changes. Thioflavin T (ThT) staining and immunoblotting of UPR signaling components (CHOP, PERK, ATF6, BiP, and XBP1) were recruited for the assessment of ERS. Our results indicated that Cycloart-E25 noticeably increases ROS levels in both MB-231 MDA-MB-231 and MCF-7 cell lines, p>0.05. Flow cytometry assessments revealed an increase in the cell population undergoing apoptosis. Also, the Bax/Bcl-2 ratio increased in a dose-dependent manner following Cycloart-E25 treatment, significantly, p>0.05. Mitochondrial involvement could be deduced by significant decreases in ΔΨm, p>0.05. Cycloart-E25 potently induces protein aggregation and upregulated CHOP, PERK, ATF6, BiP, and XBP1 factors in both MDA-MB-231 MB-231 and MCF-7 cell lines, indicating the involvement of ERS in Cycloart-E25-mediated apoptosis. In conclusion, Cycloart-E25 increased the accumulation of misfolded proteins and upregulated UPR components. Therefore, induction of ERS may be involved in the trigger of apoptosis in BC cell lines. Cycloart-E25 induced apoptosis in breast cancer cell lines through ERS. More assessments are needed to confirm its in vivo anti-tumoral effects.

Curcumae radix Reduces Endoplasmic Reticulum Stress in Mice with Chronic Neuroinflammation

Endoplasmic reticulum (ER) stress is a condition in which the ER protein-folding machinery is impaired, leading to the accumulation of improperly folded proteins and triggering an unfolded-protein response. Excessive ER stress causes cell death and contributes to the development of chronic diseases. Interestingly, there is a bidirectional relationship between ER stress and the nuclear factor-kappa B (NF-κB) pathway. Curcumin, a natural polyphenolic compound found in Curcumae radix, exerts its neuroprotective effects by regulating ER stress and inflammation. Therefore, investigating the potential protective and regulatory effects of curcumin on ER stress, inflammation, and neurodegeneration under chronic neuroinflammatory conditions is of great interest. Mice were pretreated with Curcumae radix extract (CRE) for 19 days and then treated with CRE plus lipopolysaccharide for 1 week. We monitored pro-inflammatory cytokine levels in the serum and ER stress-, inflammation-, and neurodegeneration-related markers in the mouse cerebrum and hippocampus using Western blotting and qRT-PCR. CRE reduced Interleukin-1 beta levels in the blood and brain of mice with lipopolysaccharide-induced chronic inflammation. CRE also suppressed the expression of markers related to the ER stress and NF-κB signaling pathways. The expression of neurodegeneration-related markers was reduced in the mouse cerebrum and hippocampus. CRE exerts neuroprotective effects under chronic inflammatory conditions via multifaceted anti-inflammatory and ER stress-pathway regulatory mechanisms.

Mitochondrial dysfunction in heart diseases: Potential therapeutic effects of Panax ginseng

Heart diseases have a high incidence and mortality rate, and seriously affect people's quality of life. Mitochondria provide energy for the heart to function properly. The process of various heart diseases is closely related to mitochondrial dysfunction. Panax ginseng (P. ginseng), as a traditional Chinese medicine, is widely used to treat various cardiovascular diseases. Many studies have confirmed that P. ginseng and ginsenosides can regulate and improve mitochondrial dysfunction. Therefore, the role of mitochondria in various heart diseases and the protective effect of P. ginseng on heart diseases by regulating mitochondrial function were reviewed in this paper, aiming to gain new understanding of the mechanisms, and promote the clinical application of P. ginseng.

Oncogenic Proteomics Approaches for Translational Research and HIV-Associated Malignancy Mechanisms

Recent advances in the field of proteomics have allowed extensive insights into the molecular regulations of the cell proteome. Specifically, this allows researchers to dissect a multitude of signaling arrays while targeting for the discovery of novel protein signatures. These approaches based on data mining are becoming increasingly powerful for identifying both potential disease mechanisms as well as indicators for disease progression and overall survival predictive and prognostic molecular markers for cancer. Furthermore, mass spectrometry (MS) integrations satisfy the ongoing demand for in-depth biomarker validation. For the purpose of this review, we will highlight the current developments based on MS sensitivity, to place quantitative proteomics into clinical settings and provide a perspective to integrate proteomics data for future applications in cancer precision medicine. We will also discuss malignancies associated with oncogenic viruses such as Acquire Immunodeficiency Syndrome (AIDS) and suggest novel mechanisms behind this phenomenon. Human Immunodeficiency Virus type-1 (HIV-1) proteins are known to be oncogenic per se, to induce oxidative and endoplasmic reticulum stresses, and to be released from the infected or expressing cells. HIV-1 proteins can act alone or in collaboration with other known oncoproteins, which cause the bulk of malignancies in people living with HIV-1 on ART.

The abrogation of GRP78 sensitizes liver cancer cells to lysionotin by enhancing ER stress-mediated pro-apoptotic pathway

Glucose-regulated protein 78 (GRP78) is frequently and highly expressed in various human malignancies and protects cancer cells against apoptosis induced by multifarious stresses, particularly endoplasmic reticulum stress (ER stress). The inhibition of GRP78 expression or activity could enhance apoptosis induced by anti-tumor drugs or compounds. Herein, we will evaluate the efficacy of lysionotin in the treatment of human liver cancer as well as the molecular mechanism. Moreover, we will examine whether inhibition of GRP78 enhanced the sensitivity of hepatocellular carcinoma cells to lysionotin. We found that lysionotin significantly suppressed proliferation and induced apoptosis of liver cancer cells. TEM showed that lysionotin-treated liver cancer cells showed an extensively distended and dilated endoplasmic reticulum lumen. Meanwhile, the levels of the ER stress hallmark GRP78 and UPR hallmarks (e.g., IRE1α and CHOP) were significantly increased in response to lysionotin treatment in liver cancer cells. Moreover, the reactive oxygen species (ROS) scavenger NAC and caspase-3 inhibitor Ac-DEVD-CHO visibly attenuated the induction of GRP78 and attenuated the decrease in cell viability induced by lysionotin. More importantly, the knockdown of GRP78 expression by siRNAs or treatment with EGCG, both induced remarkable increase in lysionotin-induced PARP and pro-caspase-3 cleavage and JNK phosphorylation. In addition, knockdown of GRP78 expression by siRNA or suppression GRP78 activity by EGCG both significantly improved the effectiveness of lysionotin. These data indicated that pro-survival GRP78 induction may contribute to lysionotin resistance. The combination of EGCG and lysionotin is suggested to represent a novel approach in cancer chemo-prevention and therapeutics.

Apigenin Alleviates Endoplasmic Reticulum Stress-Mediated Apoptosis in INS-1 β-Cells

The improvement of type 2 diabetes mellitus induced by naturally occurring polyphenols, known as flavonoids, has received considerable attention. However, there is a dearth of information regarding the effect of the trihydroxyflavone apigenin on pancreatic β-cell function. In the present study, the anti-diabetic effect of apigenin on pancreatic β-cell insulin secretion, apoptosis, and the mechanism underlying its anti-diabetic effects, were investigated in the INS-ID β-cell line. The results showed that apigenin concentration-dependently facilitated 11.1-mM glucose-induced insulin secretion, which peaked at 30 µM. Apigenin also concentration-dependently inhibited the expression of endoplasmic reticulum (ER) stress signaling proteins, CCAAT/enhancer binding protein (C/EBP) homologous protein (CHOP) and cleaved caspase-3, which was elevated by thapsigargin in INS-1D cells, with peak suppression at 30 µM. This was strongly correlated with the results of flow cytometric analysis of annexin V/propidium iodide (PI) staining and DNA fragmentation analysis. Moreover, the increased expression of thioredoxin-interacting protein (TXNIP) induced by thapsigargin was remarkably reduced by apigenin in a concentration-dependent manner. These results suggest that apigenin is an attractive candidate with remarkable and potent anti-diabetic effects on β-cells, which are mediated by facilitating glucose-stimulated insulin secretion and preventing ER stress-mediated β-cell apoptosis, the latter of which may be possibly mediated by reduced expression of CHOP and TXNIP, thereby promoting β-cell survival and function.

Protein persulfidation: Rewiring the hydrogen sulfide signaling in cell stress response

The past few decades have witnessed significant progress in the discovery of hydrogen sulfide (H₂S) as a ubiquitous gaseous signaling molecule in mammalian physiology, akin to nitric oxide and carbon monoxide. As the third gasotransmitter, H₂S is now known to exert a wide range of physiological and cytoprotective functions in the biological systems. However, endogenous H₂S concentrations are usually low, and its potential biologic mechanisms responsible have not yet been fully clarified. Recently, a growing body of evidence has demonstrated that protein persulfidation, a posttranslational modification of cysteine residues (RSH) to persulfides (RSSH) elicited by H₂S, is a fundamental mechanism of H₂S-mediated signaling pathways. Persulfidation, as a biological switch for protein function, plays an important role in the maintenance of cell homeostasis in response to various internal and external stress stimuli and is also implicated in numerous diseases, such as cardiovascular and neurodegenerative diseases and cancer. In this review, the biological significance of protein persulfidation by H₂S in cell stress response is reviewed providing a framework for understanding the multifaceted roles of H₂S. A mechanism-guided perspective can help open novel avenues for the exploitation of therapeutics based on H₂S-induced persulfidation in the context of diseases.

Tangeretin alleviates Tunicamycin-induced endoplasmic reticulum stress and associated complications in skeletal muscle cells

Endoplasmic reticulum (ER) stress and associated oxidative stress are involved in the genesis and progression of skeletal muscle diseases such as myositis and atrophy or muscle wasting. Targeting the ER stress and associated downstream pathways can aid in the development of better treatment strategies for these diseases with limited therapeutic approaches. There is a growing interest in identifying natural products against ER stress due to the lower toxicity and cost effectiveness. In the present study, we investigated the protective effect of Tangeretin, a citrus methoxyflavone found in citrus peels against Tunicamycin (pharmacological ER stress inducer)-induced ER stress and associated complications in rat skeletal muscle L6 cell lines. Treatment with Tunicamycin for a period of 24 h resulted in the upregulation of ER stress marker proteins, ER resident oxidoreductases and cellular reactive oxygen species (ROS). Co-treatment with Tangeretin was effective in alleviating Tunicamycin-induced ER stress and associated redox-related complications by significantly downregulating the unfolded protein response (UPR), ER resident oxidoreductase proteins, cellular ROS and improving the antioxidant enzyme activity. Tunicamycin also induced upregulation of phosphorylated p38 MAP Kinase and loss of mitochondrial membrane potential. Tangeretin significantly reduced the levels of phosphorylated p38 MAP Kinase and improved the mitochondrial membrane potential. From the results, it is evident that Tangeretin can be explored further as a potential candidate for skeletal muscle diseases involving protein misfolding and ER stress.

The multifaceted roles of natural products in mitochondrial dysfunction

Mitochondria are the primary source of energy production in cells, supporting the metabolic demand of tissue. The dysfunctional mitochondria are implicated in various diseases ranging from neurodegeneration to cancer. Therefore, regulating dysfunctional mitochondria offers a new therapeutic opportunity for diseases with mitochondrial dysfunction. Natural products are pleiotropic and readily obtainable sources of therapeutic agents, which have broad prospects in new drug discovery. Recently, many mitochondria-targeting natural products have been extensively studied and have shown promising pharmacological activity in regulating mitochondrial dysfunction. Hence, we summarize recent advances in natural products in targeting mitochondria and regulating mitochondrial dysfunction in this review. We discuss natural products in terms of their mechanisms on mitochondrial dysfunction, including modulating mitochondrial quality control system and regulating mitochondrial functions. In addition, we describe the future perspective and challenges in the development of mitochondria-targeting natural products, emphasizing the potential value of natural products in mitochondrial dysfunction.

Syringic acid ameliorates ischemia/reperfusion-induced testicular injury in rats via suppressing of HMGB1/NF-κB axis and endoplasmic reticulum stress

PURPOSE

To investigate the possible protective role of syringic acid on torsion/detorsion-induced testicular injury using biochemical and histopathological approaches for the first time.

METHODS

A total of 24 rats were divided into 4 groups: sham control, torsion/detorsion, torsion/detorsion + syringic acid (50 mg/kg and 100 mg/kg). Tissue malondialdehyde, total oxidant status and total antioxidant status levels were determined using colorimetric methods. Tissue 8-hydroxy-2'-deoxyguanosine, superoxide dismutase, catalase, high mobility group box 1, nuclear factor kappa B protein 65, tumor necrosis factor-alpha, interleukin-6, myeloperoxidase, 78-kDa glucose-regulated protein, activating transcription factor-6, C/EBP homologous protein and caspase-3 levels were determined using commercial enzyme-linked immunosorbent assay kits. Johnsen's testicle scoring system was used for histological evaluation.

RESULTS

Compared with the control group, the levels of oxidative stress, inflammation, endoplasmic reticulum stress and apoptosis were significantly increased in the torsion/detorsion group (p < 0.05). Syringic acid administrations statistically significantly restored these damage in a dose dependent manner (p < 0.05). Moreover, it was found that the results of histological examinations supported the biochemical results to a statistically significant extent.

CONCLUSION

The overall results suggest that syringic acid emerges as a potential compound for the treatment of testicular torsion and may be subject to clinical trials.

Sicilian Populations of Capparis spinosa L. and Capparis orientalis Duhamel as Source of the Bioactive Flavonol Quercetin

The genus Capparis is a taxon of difficult delimitation that has several species and ecotypes due to its wide heterogeneity, its extreme phenotypic diversity, and the presence of intermediate forms linked to hybridization phenomena. The Sicilian territory hosts numerous wild and cultivated populations of two spp. Capparis spinosa L. and Capparis orientalis Duhamel, which are ecologically and morphologically distinct. The caper has considerable interest and economic value for its medicinal properties, culinary uses, and cultivation characteristics. It is one of the foods with the highest quercetin content. Quercetin is a flavonol with antioxidant, anti-inflammatory, and immunostimulant properties. Recently, patents and clinical studies have highlighted the inhibitory effect of this compound against several SARS-CoV-2 enzymes (MPro, PLPro, and RdRp). Therefore, the aim of this study was to quantify the amount of quercetin in C. spinosa and C. orientalis by LC-ESI/QTrap/MS/MS and to correlate it with the pedoclimatic features. The results obtained showed that quercetin is more abundant in C. orientalis than in C. spinosa. The highest values of quercetin were recorded in C. orientalis flowers, leaves, and flower buttons of volcanic islands with southwest and east warm exposures. In conclusion, the data acquired can provide a good basis for further scientific investigations to support the identification of possible ecotypes as a source of quercetin for food or pharmaceutical purposes.

Pathological and Therapeutic Advances in Parkinson's Disease: Mitochondria in the Interplay

Parkinson's disease (PD) is the second most common neurodegenerative illness majorly affecting the population between the ages of 55 to 65 years. Progressive dopaminergic neuronal loss and the collective assemblage of misfolded alpha-synuclein in the substantia nigra, remain notable neuro-pathological hallmarks of the disease. Multitudes of mechanistic pathways have been proposed in attempts to unravel the pathogenesis of PD but still, it remains elusive. The convergence of PD pathology is found in organelle dysfunction where mitochondria remain a major contributor. Mitochondrial processes like bioenergetics, mitochondrial dynamics, and mitophagy are under strict regulation by the mitochondrial genome and nuclear genome. These processes aggravate neurodegenerative activities upon alteration through neuroinflammation, oxidative damage, apoptosis, and proteostatic stress. Therefore, the mitochondria have grabbed a central position in the patho-mechanistic exploration of neurodegenerative diseases like PD. The management of PD remains a challenge to physicians to date, due to the variable therapeutic response of patients and the limitation of conventional chemical agents which only offer symptomatic relief with minimal to no disease-modifying effect. This review describes the patho-mechanistic pathways involved in PD not only limited to protein dyshomeostasis and oxidative stress, but explicit attention has been drawn to exploring mechanisms like organelle dysfunction, primarily mitochondria and mitochondrial genome influence, while delineating the newer exploratory targets such as GBA1, GLP, LRRK2, and miRNAs and therapeutic agents targeting them.

Zn2+ protect cardiac H9c2 cells from endoplasmic reticulum stress by preventing mPTP opening through MCU

Zn2+ regulates endoplasmic reticulum stress (ERS) and is essential for myocardial protection through gating the mitochondrial permeability transition pore (mPTP). However, the underlining mechanism of the mPTP opening remains uncertain. Cells under sustained ERS induce unfolded protein responses (UPR) and cell apoptosis. Glucose regulatory protein 78 (GRP 78) and glucose regulatory protein 94 (GRP 94) are marker proteins of ERS and regulate the onset of apoptosis through the endoplasmic reticulum signaling pathway. We found tunicamycin (TM) treatment activates ERS and significantly increases intracellular Ca2+ and mitochondrial reactive oxygen species (ROS) levels in H9c2 cardiomyocyte cells. Zn2+ markedly decreased protein level of GRP 78/94 and suppressed intracellular Ca2+ and ROS elevation. Mitochondrial calcium uniporter (MCU) is an important Ca2+ transporter protein, through which Zn2+ enter mitochondria. MCU inhibitor ruthenium red (RR) or siRNA significantly reversed the Zinc effect on GRP 78, mitochondrial Ca2+ and ROS. Additionally, Zn2+ prevented TM-induced mPTP opening and decreased mitochondrial Ca2+ concentration, which were blocked through inhibiting or knockdown MCU with siRNA. In summary, our study suggests that Zn2+ protected cardiac ERS by elevating Ca2+ and closing mPTP through MCU.

Roles of Mitochondria in Oral Squamous Cell Carcinoma Therapy: Friend or Foe?

Oral squamous cell carcinoma (OSCC) therapy is unsatisfactory, and the prevalence of the disease is increasing. The role of mitochondria in OSCC therapy has recently attracted increasing attention, however, many mechanisms remain unclear. Therefore, we elaborate upon relative studies in this review to achieve a better therapeutic effect of OSCC treatment in the future. Interestingly, we found that mitochondria not only contribute to OSCC therapy but also promote resistance, and targeting the mitochondria of OSCC via nanoparticles is a promising way to treat OSCC.

Flavonoids Modulate Aspergillus flavus Proliferation and Aflatoxin Production

Aflatoxins are carcinogenic mycotoxins produced by Aspergillus flavus. They contaminate major food crops, particularly corn, and pose a worldwide health concern. Flavonoid production has been correlated to resistance to aflatoxin accumulation in corn. The effects of flavonoids on fungal proliferation and aflatoxin production are not well understood. In this study, we performed bioassays, fluorescence and scanning electron microscopy, and total antioxidant analysis to determine the effects of three flavonoids (apigenin, luteolin, and quercetin) on proliferation and aflatoxin production in A. flavus NRRL 3357. Results showed that concentrations of apigenin and luteolin modulated fungal proliferation and aflatoxin production in a dose-dependent manner, leading to inhibition or promotion of proliferation and toxin production. Microscopy studies of fungi exposed to flavonoids showed mycelial cell wall disruption, abnormal cell wall invaginations, and tears. Fluorescent enhancement of apigenin and luteolin using Naturstoff reagent A showed that these chemicals localized in sphere-like structures on the mycelia surface. Fungi exposed to low concentrations of apigenin, luteolin, and quercetin lowered the total antioxidant capacity in the environment compared to controls. Our results indicate that flavonoids disrupt cell wall integrity and may localize in vesicle-like structures. We hypothesize that flavonoids could act as potential signaling molecules at low concentrations and change the oxidative state of the microenvironment, either or both of which may lead to reduction of fungal proliferation and aflatoxin production.

The role of nanomaterials in enhancing natural product translational potential and modulating endoplasmic reticulum stress in the treatment of ovarian cancer

Ovarian cancer, and particularly its most frequent type, epithelial ovarian carcinoma, constitutes one of the most dangerous malignant tumors among females. Substantial evidence has described the potential of phytochemicals against ovarian cancer. The effect of natural compounds on endoplasmic reticulum (ER) stress is of great relevance in this regard. In ovarian cancer, the accumulation of misfolded proteins in the ER lumen results in decompensated ER stress. This leads to deregulation in the physiological processes for the posttranslational modification of proteins, jeopardizes cellular homeostasis, and increases apoptotic signaling. Several metabolites and metabolite extracts of phytochemical origin have been studied in the context of ER stress in ovarian cancer. Resveratrol, quercetin, curcumin, fucosterol, cleistopholine, fucoidan, and epicatechin gallate, among others, have shown inhibitory potential against ER stress. The chemical structure of each compound plays an important role concerning its pharmacodynamics, pharmacokinetics, and overall effectiveness. Studying and cross-comparing the chemical features that render different phytochemicals effective in eliciting particular anti-ER stress actions can help improve drug design or develop multipotent combination regimens. Many studies have also investigated the properties of formulations such as nanoparticles, niosomes, liposomes, and intravenous hydrogel based on curcumin and quercetin along with some other phytomolecules in ovarian cancer. Overall, the potential of phytochemicals in targeting genetic mechanisms of ovarian cancer warrants further translational and clinical investigation.

The Role of Mitochondrial Quality Control in Anthracycline-Induced Cardiotoxicity: From Bench to Bedside

Cardiotoxicity is the major side effect of anthracyclines (doxorubicin, daunorubicin, epirubicin, and idarubicin), though being the most commonly used chemotherapy drugs and the mainstay of therapy in solid and hematological neoplasms. Advances in the field of cardio-oncology have expanded our understanding of the molecular mechanisms underlying anthracycline-induced cardiotoxicity (AIC). AIC has a complex pathogenesis that includes a variety of aspects such as oxidative stress, autophagy, and inflammation. Emerging evidence has strongly suggested that the loss of mitochondrial quality control (MQC) plays an important role in the progression of AIC. Mitochondria are vital organelles in the cardiomyocytes that serve as the key regulators of reactive oxygen species (ROS) production, energy metabolism, cell death, and calcium buffering. However, as mitochondria are susceptible to damage, the MQC system, including mitochondrial dynamics (fusion/fission), mitophagy, mitochondrial biogenesis, and mitochondrial protein quality control, appears to be crucial in maintaining mitochondrial homeostasis. In this review, we summarize current evidence on the role of MQC in the pathogenesis of AIC and highlight the therapeutic potential of restoring the cardiomyocyte MQC system in the prevention and intervention of AIC.

Flavones: Six Selected Flavones and Their Related Signaling Pathways That Induce Apoptosis in Cancer

Cancer is a horrific disease that, to date, has no cure. It is caused by various factors and takes many lives. Apoptosis is a programmed cell death mechanism and if it does not function correctly in cancer cells, it can lead to severe disease. There are various signaling pathways for regulating apoptosis in cancer cells. Flavonoids are non-artificial natural bioactive compounds that are gaining attention as being capable of for inducing apoptosis in cancer cells. Among these, in this study, we focus on flavones. Flavones are a subclass of the numerous available flavonoids and possess several bioactive functions. Some of the most reported and well-known critical flavones, namely apigenin, acacetin, baicalein, luteolin, tangeretin, and wogonin, are discussed in depth in this review. Our main aim is to investigate the effects of the selected flavones on apoptosis and cell signaling pathways that contribute to death due to various types of cancers.

Pro-Apoptotic and Pro-Autophagic Properties of Cardenolides from Aerial Parts of Pergularia tomentosa

Pergularia tomentosa L., a milkweed tropical plant belonging to the family Asclepiadaceae, is a rich source of unusual cardiac glycosides, characterised by transfused A/B rings and a sugar moiety linked by a double link, generating a dioxanoid structure. In the present report, five cardenolides isolated from the aerial parts of the plant (calactin, calotropin, 12β-hydroxycalactin, 12β,6'-dihydroxycalotropin, and 16α-hydroxycalotropin) were investigated for their biological effects on a human hepatocarcinoma cell line. Cell viability was monitored by an MTT assay. The occurrence of apoptosis was evaluated by detecting caspase-3 activation and chromatin fragmentation. The ability of these compounds to induce autophagy was analysed by monitoring two markers of the autophagic process, LC3 and p62. Our results indicated that all cardenolides had cytotoxic effects, with IC₅₀ ranging from 0.127 to 6.285 μM. All compounds were able to induce apoptosis and autophagy, calactin being the most active one. Some of them also caused a reduction in cell migration and a partial block of the cell cycle into the S-phase. The present study suggests that selected cardenolides from aerial parts of P. tomentosa, particularly calactin, possess potentially desirable properties for further investigation as anticancer agents.

Apoptosis Induction Associated with Enhanced ER Stress Response and Up-Regulation of c-Jun/p38 MAPK Proteins in Human Cervical Cancer Cells by Colocasia esculenta var. aquatilis Hassk Extract

Colocasia esculenta var. Aquatilis Hassk, elephant ear (CF-EE) has been widely used as traditional food and medicine. It also shows other therapeutic properties, such as antimicrobial and anti-cancer activity. In this study, we aim to investigate the effect of CF-EE extract on apoptosis induction associated with ER stress in cervical cancer HeLa cells. Cell viability was determined by MTT assay. Assessments of nuclear morphological changes, mitochondrial membrane potential, and intracellular reactive oxygen species (ROS) production were conducted by hoeshst33342, JC-1, and DCFH-DA fluorescence staining, respectively. Sub-G1 DNA content was analyzed by flow cytometry, and protein expression was determined by Western blotting. The results demonstrate that CF-EE extract suppressed HeLa cell growth and induced nuclear condensation and apoptotic bodies. There was also a loss of mitochondrial membrane potential and increased apoptosis marker protein expression, including Bax, cleaved-caspase-7, and cleaved-PARP. In addition, the results show that CF-EE extract induced ROS, increased ER stress proteins (GRP78 and CHOP), enhanced p38 and c-Jun phosphorylation, and inhibited Akt expression in HeLa cells. In summary, CF-EE extract induced apoptotic cell death-associated ROS-induced ER stress and the MAPK/AKT signaling pathway. Therefore, CF-EE extract has anticancer therapeutic potential for cervical cancer treatment in the future.

ZnT8 loss-of-function accelerates functional maturation of hESC-derived β cells and resists metabolic stress in diabetes

Human embryonic stem cell-derived β cells (SC-β cells) hold great promise for treatment of diabetes, yet how to achieve functional maturation and protect them against metabolic stresses such as glucotoxicity and lipotoxicity remains elusive. Our single-cell RNA-seq analysis reveals that ZnT8 loss of function (LOF) accelerates the functional maturation of SC-β cells. As a result, ZnT8 LOF improves glucose-stimulated insulin secretion (GSIS) by releasing the negative feedback of zinc inhibition on insulin secretion. Furthermore, we demonstrate that ZnT8 LOF mutations endow SC-β cells with resistance to lipotoxicity/glucotoxicity-triggered cell death by alleviating endoplasmic reticulum (ER) stress through modulation of zinc levels. Importantly, transplantation of SC-β cells with ZnT8 LOF into mice with preexisting diabetes significantly improves glycemia restoration and glucose tolerance. These findings highlight the beneficial effect of ZnT8 LOF on the functional maturation and survival of SC-β cells that are useful as a potential source for cell replacement therapies.

Immature function and fragility hinder application of hESC-derived β cells (SC-β cell) for diabetes cell therapy. Here, the authors identify ZnT8 as a gene editing target to enhance the insulin secretion and cell survival under metabolic stress by abolishing zinc transport in SC-β cells.

High-throughput screening identifies stevioside as a potent agent to induce apoptosis in bladder cancer cells

BACKGROUND

Bladder cancer (BC) is a global health issue that lacks effective treatment strategies. Growing evidence suggests that various natural products possess anti-tumour effects. This study aims to identify a novel agent that can be used in the treatment of BC.

METHODS

High-throughput screening was conducted to search for potential anti-BC natural agents. Cell viabilities were measured by the CCK-8 assay. Cell death, cellular reactive oxygen species (ROS), and mitochondrial outer membrane potential (MOMP) were measured by flow cytometry. RNA sequencing was conducted to identify the affected signalling pathways. Western blots were used to measure the change of proteins. Xenografts models were used to assess the anti-tumour effects in vivo.

RESULTS

Through high-throughput screening, we identified stevioside, a diterpenoid glycoside isolated from Stevia rebaudiana, which selectively inhibited the viability of BC cells and induced their intrinsic apoptosis sparing normal cells. Stevioside also induced mitochondrial stress in BC cells, and activated Bax by downregulating Mcl-1 and upregulating Noxa. RNA sequencing revealed that stevioside treatment caused activation of GSK-3β and endoplasmic reticulum (ER) stress signalling pathways. Activation of GSK-3β induced upregulation of FBXW7, which effectuated the downregulation of Mcl-1. In addition, activation of GSK-3β triggered ER stress, leading to the upregulation of Noxa. Further investigations revealed that the accumulation of ROS was responsible for the activation of the GSK-3β signalling pathway in BC cells. Moreover, we also found that stevioside inhibited the growth of BC cells in vivo.

CONCLUSIONS

Collectively, our data suggest that stevioside can be a potential agent for the treatment of BC.

Endoplasmic Reticulum Stress and Impairment of Ribosome Biogenesis Mediate the Apoptosis Induced by Ocimum x africanum Essential Oil in a Human Gastric Cancer Cell Line

Background and Objectives: Gastric cancer remains a major unmet clinical problem worldwide. Although conventional medical treatments are available, their curative effects are generally unsatisfactory. Consequently, it remains necessary to search natural products for potential alternatives in treating gastric cancer patients. Ocimum x africanum Lour. is a culinary herb that has been used in folk medicine for various diseases, but little is known regarding its anti-cancer activity against gastric cancer cells. In the current study, we focus on the anti-cancer mechanisms of O. x africanum essential oil (OAEO) in the AGS human gastric cancer cell line. Materials and Methods: After OAEO treatment, AGS cell viability was evaluated by MTT assay. Cell migration and apoptotic nuclear morphology were determined by wound-healing assay and DAPI staining, respectively. Gene expression levels of apoptosis-related genes were quantified by qRT–PCR. Differential protein expression was determined with an LC–MS/MS-based proteomics approach to identify the key proteins that may be important in the anti-cancer mechanisms of OAEO on AGS cells. The chemical constituents of OAEO were identified by GC–MS analysis. Results: We found OAEO to exhibit a potent growth-inhibiting effect on AGS cells, with an IC₅₀ value of 42.73 µg/mL. After OAEO treatment for 24 h, AGS cell migration was significantly decreased relative to the untreated control. OAEO-treated AGS cells exhibited common features of apoptotic cell death, including cell shrinkage, membrane blebbing, chromatin condensation, and nuclear fragmentation. Apoptotic cell death was confirmed by qRT–PCR for apoptosis-related genes, revealing that OAEO decreased the expression of anti-apoptotic genes (BCL2 and BCL-xL) and activated pro-apoptotic genes and apoptotic caspase genes (TP53, BAX, CASP9, CASP12, and CASP3). Moreover, expression of CASP8 was not changed after treatment. Proteomic analysis revealed that OAEO may produce a signature effect on protein clusters relating to unfolded protein accumulation, thereby inducing severe ER stress and also impairing ribosome synthesis. STRING analysis revealed seven up-regulated and 11 down-regulated proteins, which were significantly associated with protein folding and ribosome biogenesis, respectively. Using GC–MS analysis, 6-methyl-5-hepten-2-one, citral, neral, and linalool were found to be the major chemical constituents in OAEO. Conclusions: Taken together, these results indicate that OAEO has a potential anti-proliferative effect on AGS cells. Our molecular findings show evidence supporting an important role of ER stress and ribosome biogenesis impairment in mediating the induction of cell death by OAEO through the mitochondrial-apoptotic pathway. This study, therefore, provides fundamental knowledge for future applications using OAEO as an alternative therapy in gastric cancer management.

Chlorogenic acid ameliorates torsion/detorsion-induced testicular injury via decreasing endoplasmic reticulum stress

BACKROUND

Testicular torsion (TT) is an urological emergency situation especially in adolescents and young men. The main pathophysiology of testicular torsion/detorsion (T/D) is ischemia-reperfusion (I/R) injury. I/R induces the production of reactive oxygen species (ROS) thought to play a critical role in tissue injury. Increasing evidence suggests that ER stress may play an important role in I/R-induced cell death. During ischemia, oxygen and glucose deprivation also causes abnormalities in protein folding processes. Antioxidants suppress oxidative stress directly as well as ER stress and thus gain importance in the treatment of pathologies associated with oxidative stress and ER stress, such as I/R damage. Chlorogenic acid (CGA) which is formed by the esterification of caffeic and quinic acids and is one of the most abundant phenolic acids in nature. There is also a growing body of studies reporting protective effects of CGA against I/R injury in different tissues, including intestinal, heart and brain.

OBJECTIVE

To investigate the effects of CGA on oxidative stress and ER stress in an experimental testicular I/R injury model.

DESIGN

Rats were divided into three groups: control, T/D, and T/D + CGA. In the T/D + CGA group, 100 mg/kg CGA was given intraperitoneally 30 min before detorsion. While tissue malondialdehyde (MDA) levels were determined manually using a colorimetric method, tissue superoxide dismutase (SOD), 78-kDa glucose regulatory protein (GRP78), activating transcription factor 6 (ATF6) and C/EBP homologous protein (CHOP) levels were determined enzyme-linked immunosorbent assay (ELISA) kits. Johnsen's testicle scoring system was used for histological evaluation.

RESULTS

In T/D group, tissue MDA, GRP78, ATF6 and CHOP levels were significantly higher than control group (p < 0.05). These increases were significantly reversed with CGA pre-treatment (p < 0.05). The histopathological Johnsen score was significantly lower in the T/D group compared to the control group, but the level of histopathological Johnsen score was significantly restored by CGA pre-treatment (p < 0.05).

DISCUSSION

The relationship between I/R injury and ER stress has been emphasized frequently in recent years. This study in which the effects of CGA on TT were examined for the first time, showed that CGA can inhibit I/R-induced testicular damage.

CONCLUSION

These results may provide a new insight into CGA and may form the first clinical theoretical basis for the possible use of CGA in the treatment of TT in the future. However, the real function of CGA in TT patients needs further investigation.

Therapeutic potentials of genistein: New insights and perspectives

Genistein, a polyphenolic isoflavone compound found abundantly in soy or soy-based products, is widely consumed in the Asian population. Genistein has poor bioavailability, to overcome this problem many advanced nano-drug delivery carrier systems are designed to enhance its water solubility and stability. However, further research is required to develop more efficient bioavailability improvement strategies. Genistein is a phytoestrogen which has been associated with reducing the risk of cancer, cardiovascular disorders, and diabetes mellitus. This plant-based bioactive compound possesses numerous biological activities such as anti-oxidant, anti-inflammatory, anti-obesity, anti-cancer, cardioprotective, and anti-diabetic activities to treat various disease states. Genistein has been used as an active therapeutic agent in many medications. Moreover, several clinical trials are in the ongoing stage to develop more efficient treatment therapies, especially for cancer treatment. This article highlights the protective and therapeutic benefits of genistein in the treatment of different ailments, and more specifically elaborates on the anti-cancer potential of genistein regarding various types of cancers. PRACTICAL APPLICATIONS: Genistein possesses versatile biological activities, including anti-diabetic, anti-inflammatory, anti-oxidant, anti-obesity, and anti-angiogenic. The most studied activity is anti-cancer. Currently, a number of pre-clinical and clinical trials are being carried out on anti-neoplastic and cytotoxic activities of genistein to develop novel therapeutic agents with excellent anti-cancer potential for the treatment of various kinds of cancer. Moreover, many bioavailability enhancement strategies have been developed to improve the bioavailability of genistein. Genistein shows significant hypoglycemic effects alone or in combination with other anti-diabetic agents. Genistein in combination with other chemotherapeutic agents is used for the treatment of prostate, bone, colorectal, glioma, breast, and bladder cancer.

Protective effect of food derived nutrients on cisplatin nephrotoxicity and its mechanism

Platinum-based metal complexes, especially cisplatin (cis-diamminedichloroplatinum II, CDDP), possess strong anticancer properties and a broad anticancer spectrum. However, the clinical application of CDDP has been limited by its side effects including nephrotoxicity, ototoxicity, and neurotoxicity. Furthermore, the therapeutic effects of current clinical protocols are imperfect. Accordingly, it is essential to identify key targets and effective clinical protocols to restrict CDDP-induced nephrotoxicity. Herein, we first analyzed the relevant molecular mechanisms during the process of CDDP-induced nephrotoxicity including oxidative stress, apoptosis, and inflammation. Evidence from current studies was collected and potential targets and clinical protocols are summarized. The evidence indicates an efficacious role of nutrition-based substances in CDDP-induced renal injury.

Zinc Alleviates Arsenic-Induced Inflammation and Apoptosis in the Head Kidney of Common Carp by Inhibiting Oxidative Stress and Endoplasmic Reticulum Stress

Arsenic (As) pollution is ubiquitous in water, which shows immunotoxicity to aquatic organisms. As an indispensable regulator of gene transcription and enzymatic modification, zinc (Zn) may play a preventive and therapeutic effect on As toxicity. The purpose of this study was to investigate the interactions of As and Zn on the head kidney of common carp Cyprinus carpio. Herein the carp were treated alone or in combination with waterborne As³⁺ (2.83 mg/L) and/or Zn²⁺ (1 mg/L). Results suggested a head kidney-toxic effect of As exposure, which was manifested by the histopathological damage of the head kidney, elevation of nuclear translocation of pro-inflammatory nuclear factor-kappa light chain enhancer of B cells (NF-κB), and blockage of the anti-oxidative nuclear factor erythroid 2-related factor 2 (Nrf2) pathway. The global activation of three endoplasmic reticulum (ER) stress pathways led to the execution of programmed cell death, including ER apoptosis mediated by C/EBP-homologous protein (CHOP), death receptor-mediated exogenous cell apoptosis, and the endogenous apoptosis executed by Caspases9. The combined application of Zn can significantly improve the histopathological damage of the head kidney, the imbalance of the antioxidant system, and the apoptosis outcomes due to ER stress. In conclusion, this study indicates that Zn has an antagonistic effect on the head kidney injury of common carp induced by sub-chronic As exposure. The results of this study provide basic data for the risk assessment of As accumulation in an aquatic environment and a reference for the use of Zn preparation in aquaculture.

Flurochloridone Induced Cell Apoptosis via ER Stress and eIF2α-ATF4/ATF6-CHOP-Bim/Bax Signaling Pathways in Mouse TM4 Sertoli Cells

Flurochloridone (FLC), as a novel herbicide, has been widely used in many countries since 1980s. Current studies have shown that FLC has toxic effects on male reproduction and its target organ is testis, while the underlying mechanism is still unknown. Mouse testis Sertoli cell line TM4 cells were used as an in vitro model and treated with FLC at different doses (40, 80, 160 μM) for different times (6, 12, 24 h). Cell viability, cytotoxicity and apoptotic cells were detected by CCK-8 assay, LDH leakage assay and flow cytometry. The protein levels of GRP78, phosphorylated-eIF2α, ATF4, ATF6, CHOP, Bim and Bax were observed by Western Blot and Immunofluorescence staining. FLC inhibited cell viability and induced cytotoxicity in dose-dependent way in TM4 cells. The percentage of apoptotic cells were 6.2% ± 0.6%, 7.3% ± 0.3%, 9.8% ± 0.4%, 13.2% ± 0.2%, respectively. The expression levels of ER stress and UPR related proteins were activated over dose. Meanwhile, the pro-apoptotic proteins (Bim and Bax) were also up-regulated in dose-dependent. After pretreated with ISRIB, the inhibitor of eIF2α phosphorylation, the elevated expression of GRP78, phosphorylated-eIF2α, ATF4, ATF6, CHOP and Bim was down to normal level accordingly. In conclusion, FLC induced apoptosis in TM4 cells mediated by UPR signaling pathways.

Protodioscin Induces Mitochondrial Apoptosis of Human Hepatocellular Carcinoma Cells Through Eliciting ER Stress-Mediated IP3R Targeting Mfn1/Bak Expression

Objective

Protodioscin (PD), a steroidal saponin, has a diverse pharmacological activity including neuroprotection, male fertility improvement, and cytotoxicity against various cancers cell lines of different origins. However, the effect of PD on hepatocellular carcinoma (HCC) is still unclear.

Methods

Cell viability, colony formation and flow cytometry analysis for apoptosis profile, mitochondrial membrane potential endoplasmic reticulum (ER) expansion were employed to determine the effect of PD against HCC cells. Transient transfection of siRNA, immunofluorescent imaging and immunoprecipitation were used to elucidate the anti-cancer mechanism of PD. The in vivo toxicity and efficacy of PD were assessed by a xenograft mouse model.

Results

PD induced apoptosis, loss of mitochondrial membrane potential and ER expansion in HCC cells. Either downregulation of Mfn1 or Bak reversed PD-induced apoptosis and loss of mitochondrial membrane potential. Further analysis revealed that Mfn1 and Bak will form a complex with IP3R to facilitate the transfer of Ca²⁺ from ER to mitochondria and apoptosis. In addition, our tumour xenograft model further verifies the in vivo anti-tumour effect of PD.

Conclusion

Our study sheds light on the understanding of the anti-HCC effects of PD and may open new aspects for the development of novel treatment for human hepatocellular carcinoma.

Pathogenic Role of Endoplasmic Reticulum Stress in Diabetic Corneal Endothelial Dysfunction

Purpose

Progressive corneal edema and endothelial cell loss represent the major corneal complications observed in diabetic patients after intraocular surgery. However, the underlying pathogenesis and potential treatment remain incompletely understood.

Methods

We used streptozotocin-induced type 1 diabetic mice and db/db type 2 diabetic mice as diabetic animal models. These mice were treated with the endoplasmic reticulum (ER) stress agonist thapsigargin; 60-mmHg intraocular pressure (IOP) with the ER stress antagonist 4-phenylbutyric acid (4-PBA); mitochondria-targeted antioxidant SkQ1; or reactive oxygen species scavenger N-acetyl-l-cysteine (NAC). Corneal thickness and endothelial cell density were measured before and after treatment. Human corneal endothelial cells were treated with high glucose with or without 4-PBA. The expression of corneal endothelial- and ER stress–related genes was detected by western blot and immunofluorescence staining. Mitochondrial bioenergetics were measured with an Agilent Seahorse XFp Analyzer.

Results

In diabetic mice, the appearance of ER stress preceded morphological changes in the corneal endothelium. The persistent ER stress directly caused corneal edema and endothelial cell loss in normal mice. Pharmacological inhibition of ER stress was sufficient to mitigate corneal edema and endothelial cell loss in both diabetic mice after high IOP treatment. Mechanistically, inhibiting ER stress ameliorated the hyperglycemia-induced mitochondrial bioenergetic deficits and improved the barrier and pump functional recovery of the corneal endothelium. When compared with NAC, 4-PBA and SkQ1 exhibited better improvement of corneal edema and endothelial cell loss in diabetic mice.

Conclusions

Hyperglycemia-induced ER stress contributes to the dysfunction of diabetic corneal endothelium, and inhibiting ER stress may offer therapeutic potential by improving mitochondrial bioenergetics.

Dihydroartemisinin Induces ER Stress-Mediated Apoptosis in Human Tongue Squamous Carcinoma by Regulating ROS Production

BACKGROUND

Tongue squamous cell carcinoma is a fatal disease characterized by high invasion and early metastasis. Dihydroartemisinin, an antimalarial drug with multiple biological activities, is reported to be a potential anti-cancer agent.

OBJECTIVE

This study aimed to evaluate the antitumor effect of Dihydroartemisinin on tongue squamous cell carcinoma cells, and to identify the underlying mechanisms of Dihydroartemisinin-induced cell apoptosis.

METHODS

Here, Cell Counting Kit 8 assay and colony formation assay were conducted to study cell proliferation. Annexin V-FITC/propidium iodide staining and western blot analysis were performed to analyze cell apoptosis. DCFH-DA probe was used to measure the generation of cellular reactive oxygen species. Endoplasmic reticulum stress activation was also determined via western blot analysis.

RESULTS

The results showed that Dihydroartemisinin substantially inhibited cell proliferation and induced cell apoptosis in vivo. Moreover, reactive oxygen species production and endoplasmic reticulum stress activation were both observed after stimulation with Dihydroartemisinin. However, the reactive oxygen species inhibitor N-acetylcysteine significantly alleviated Dihydroartemisinin-induced endoplasmic reticulum stress and apoptosis.

CONCLUSION

These results imply that Dihydroartemisinin induced cell apoptosis by triggering reactive oxygen species-mediated endoplasmic reticulum stress in CAL27 cells. In addition, Dihydroartemisinin might be an effective drug for tongue squamous cell carcinoma therapy.

Mitochondrial Targeting Therapeutics: Promising Role of Natural Products in Non-alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) has become one of the most common chronic liver diseases worldwide, and its prevalence is still growing rapidly. However, the efficient therapies for this liver disease are still limited. Mitochondrial dysfunction has been proven to be closely associated with NAFLD. The mitochondrial injury caused reactive oxygen species (ROS) production, and oxidative stress can aggravate the hepatic lipid accumulation, inflammation, and fibrosis. which contribute to the pathogenesis and progression of NAFLD. Therefore, pharmacological therapies that target mitochondria could be a promising way for the NAFLD intervention. Recently, natural products targeting mitochondria have been extensively studied and have shown promising pharmacological activity. In this review, the recent research progress on therapeutic effects of natural-product-derived compounds that target mitochondria and combat NAFLD was summarized, aiming to provide new potential therapeutic lead compounds and reference for the innovative drug development and clinical treatment of NAFLD.

Sirtuins Modulation: A Promising Strategy for HIV-Associated Neurocognitive Impairments

HIV-Associated neurocognitive disorder (HAND) is one of the major concerns since it persists in 40% of this population. Nowadays, HAND neuropathogenesis is considered to be caused by the infected cells that cross the brain-blood barrier and produce viral proteins that can be secreted and internalized into neurons leading to disruption of cellular processes. The evidence points to viral proteins such as Tat as the causal agent for neuronal alteration and thus HAND. The hallmarks in Tat-induced neurodegeneration are endoplasmic reticulum stress and mitochondrial dysfunction. Sirtuins (SIRTs) are NAD+-dependent deacetylases involved in mitochondria biogenesis, unfolded protein response, and intrinsic apoptosis pathway. Tat interaction with these deacetylases causes inhibition of SIRT1 and SIRT3. Studies revealed that SIRTs activation promotes neuroprotection in neurodegenerative diseases such Alzheimer's and Parkinson's disease. Therefore, this review focuses on Tat-induced neurotoxicity mechanisms that involve SIRTs as key regulators and their modulation as a therapeutic strategy for tackling HAND and thereby improving the quality of life of people living with HIV.

The Anti-Proliferative Activity of Secondary Metabolite from the Marine Streptomyces sp. against Prostate Cancer Cells

Many active substances from marine organisms are produced by symbiotic microorganisms such as bacteria, fungi, and algae. Secondary metabolites from marine actinomycetes exhibited several biological activities and provided interesting drug leads. This study reported the isolation of Lu01-M, a secondary metabolite from the marine actinomycetes Streptomyces sp., with potent anti-proliferative activity against prostate cancers. Lu01-M blocked cell proliferation with IC₅₀ values of 1.03 ± 0.31, 2.12 ± 0.38, 1.27 ± 0.25 μg/mL in human prostate cancer PC3, DU145, and LNCaP cells, respectively. Lu01-M induced cytotoxic activity through multiple mechanisms including cell apoptosis, necroptosis, autophagy, ER stress, and inhibiting colony formation and cell migration. Lu01-M induced cell cycle arrest at the G2/M phase and DNA damage. However, the activity of autophagy induced survival response in cancer cells. Our findings suggested that Lu01-M holds the potential to be developed as an anti-cancer agent against prostate cancers.

Effect of Chrysin on Endoplasmic Reticulum Stress in a Rat Model of Testicular Torsion

BACKGROUND

The purpose of this study was to evaluate the possible therapeutic effect of chrysin (CHS) on testicular torsion/detorsion (T/D) injury in vivo through the mechanisms of oxidative stress and endoplasmic reticulum stress (ERS).

METHODS

Eighteen male rats were divided into three groups of six subjects in each group: control, T/D and T/D + CHS (100 mg/kg). To evaluate the degree of oxidative stress, tissue malondialdehyde (MDA), total oxidant status (TOS) and total antioxidant status (TAS) levels were determined using colorimetric methods, while tissue superoxide dismutase (SOD) levels were determined using an ELISA kit. To evaluate the degree of ERS, tissue glucose regulatory protein 78 (GRP78), activating transcription factor 6 (ATF6) and C/EBP homologous protein (CHOP) levels were determined using ELISA kits. Johnsen's testicle scoring system was used for histological evaluation.

RESULTS

In the T/D group, it is determined that statistically significant decreasing in the levels of TAS, SOD and Johnsen score, and increasing in TOS, MDA, GRP78, ATF6 and CHOP levels compared to control group (p < 0.05). CHS administration statistically significantly restored this T/D-induced damage (p < 0.05).

CONCLUSION

This is the first study to show that CHS prevent T/D-induced testicular damage through its ERS inhibitor activity. More comprehensive studies are needed to understand the underlying mechanisms.

Supplemental data for this article is available online at https://doi.org/10.1080/08941939.2021.2015489 .

Astaxanthin Protects Testicular Tissue against Torsion/Detorsion-Induced Injury via Suppressing Endoplasmic Reticulum Stress in Rats

BACKGROUND

The aim of this study was to investigate the effects of astaxanthin (ASX) on testicular torsion/detorsion (T/D) damage in rats in terms of oxidative stress and endoplasmic reticulum (ER) stress.

METHODS

Eighteen male Sprague-Dawley rats were divided into three groups with six rats in each group: control, T/D and T/D + 20 mg/kg ASX. Torsion and detorsion times were applied as 4 h and 2 h, respectively. ASX application was performed 30 minutes before detorsion. At the end of the period, testicular tissues were removed and biochemical and histological analyzes were performed. To evaluate the degree of oxidative stress, tissue malondialdehyde (MDA), total oxidant status (TOS) and total antioxidant status (TAS) were determined using colorimetric methods, while tissue superoxide dismutase (SOD) levels were determined using ELISA kit. To evaluate the degree of ER stress, tissue glucose regulatory protein 78 (GRP78), activating transcription factor 6 (ATF6) and C/EBP homologous protein (CHOP) levels were determined using ELISA kits. Johnsen's testicle scoring system was used for histological evaluation.

RESULTS

In the T/D group, it is determined that statistically significant decreasing in TAS, SOD levels and Johnsen score, and increasing in TOS, OSI, MDA, GRP78, ATF6 and CHOP levels (p < 0.001) compared with control group. ASX administration statistically significantly restored this T/D-induced damage (p < 0.01).

CONCLUSION

This is the first study to show that ASX prevent T/D-induced testicular damage through its antioxidant activity. More comprehensive studies are needed to see the underlying mechanisms.

Role of UPR Sensor Activation in Cell Death-Survival Decision of Colon Cancer Cells Stressed by DPE Treatment

Polyphenols have been shown to possess several beneficial properties, including properties involved in the prevention or treatment of cancer. Among these polyphenols, a leading role is played by dihydroxyphenylethanol (DPE), the most powerful antioxidant compound contained in the olive oil. DPE has been previously reported to induce endoplasmic reticulum (ER) stress and to reduce cell survival in colon cancer, one of the most common and aggressive cancers in developed countries. In this study, we further investigated the activation of UPR by DPE and explored the roles of the three UPR sensors, inositol-requiring enzyme (IRE) 1 alpha, protein kinase RNA-like endoplasmic reticulum kinase (PERK), and activating transcription factor (ATF6), in the cell death-survival decision of wt and mutp53 colon cancer cells and the underlying mechanisms involved. We also unveiled a new interplay between ATF6 and wt, as well as mutp53, which may have important implications in cancer therapy.