Costunolide, an active sesquiterpene lactone, induced apoptosis via ROS-mediated ER stress and JNK pathway in human U2OS cells

Inhibiting AGS Cancer Cell Proliferation through the Combined Application of Aucklandiae Radix and Hyperthermia: Investigating the Roles of Heat Shock Proteins and Reactive Oxygen Species

Cancer is a major global health concern. To address this, the combination of traditional medicine and newly appreciated therapeutic modalities has been gaining considerable attention. This study explores the combined effects of Aucklandiae Radix (AR) and 43 °C hyperthermia (HT) on human gastric adenocarcinoma (AGS) cell proliferation and apoptosis. We investigated the synergistic effects of AR and HT on cell viability, apoptosis, cell cycle progression, and reactive oxygen species (ROS)-dependent mechanisms. Our findings suggest that the combined treatment led to a notable decrease in AGS cell viability and increased apoptosis. Furthermore, cell cycle arrest at the G2/M phase contributed to the inhibition of cancer cell proliferation. Notably, the roles of heat shock proteins (HSPs) were highlighted, particularly in the context of ROS regulation and the induction of apoptosis. Overexpression of HSPs was observed in cells subjected to HT, whereas their levels were markedly reduced following AR treatment. The suppression of HSPs and the subsequent increase in ROS levels appeared to contribute to the activation of apoptosis, suggesting a potential role for HSPs in the combined therapy's anti-cancer mechanisms. These findings provide valuable insights into the potential of integrating AR and HT in cancer and HSPs.

Sesquiterpene lactones as emerging biomolecules to cease cancer by targeting apoptosis

Apoptosis is a programmed cell death comprising two signaling cascades including the intrinsic and extrinsic pathways. This process has been shown to be involved in the therapy response of different cancer types, making it an effective target for treating cancer. Cancer has been considered a challenging issue in global health. Cancer cells possess six biological characteristics during their developmental process known as cancer hallmarks. Hallmarks of cancer include continuous growth signals, unlimited proliferation, resistance to proliferation inhibitors, apoptosis escaping, active angiogenesis, and metastasis. Sesquiterpene lactones are one of the large and diverse groups of planet-derived phytochemicals that can be used as sources for a variety of drugs. Some sesquiterpene lactones possess many biological activities such as anti-inflammatory, anti-viral, anti-microbial, anti-malarial, anticancer, anti-diabetic, and analgesic. This review article briefly overviews the intrinsic and extrinsic pathways of apoptosis and the interactions between the modulators of both pathways. Also, the present review summarizes the potential effects of sesquiterpene lactones on different modulators of the intrinsic and extrinsic pathways of apoptosis in a variety of cancer cell lines and animal models. The main purpose of the present review is to give a clear picture of the current knowledge about the pro-apoptotic effects of sesquiterpene lactones on various cancers to provide future direction in cancer therapeutics.

Insulin-like growth factor 1 in heat stress-induced neuroinflammation: novel perspective about the neuroprotective role of chromium

Heat stress (HS) can cause a series of stress responses, resulting in numerous negative effects on the body, such as the diminished food intake, carcass quality and reproductive capacity. In addition to the negative effects on the peripheral system, HS leads to central nervous system (CNS) disorders given its toll on neuroinflammation. This neuroinflammatory process is mainly mediated by microglia and astrocytes, which are involved in the activation of glial cells and the secretion of cytokines. While the regulation of inflammatory signaling has a close relationship with the expression of heat shock protein 70 (Hsp70), HS-induced neuroinflammation is closely related to the activation of the TLR4/NF-κB pathway. Moreover, oxidative stress and endoplasmic reticulum (ER) stress are key players in the development of neuroinflammation. Chromium (Cr) has been widely shown to have neuroprotective effects in both humans and animals, despite the lack of mechanistic evidence. Evidence has shown that Cr supplementation can increase the levels of insulin-like growth factor 1 (IGF-1), a major neurotrophic factor with anti-inflammatory and antioxidant effects. This review highlights recent advances in the attenuating effects and potential mechanisms of Cr-mediated IGF-1 actions on HS-induced neuroinflammation, providing presently existing evidence supporting the neuroprotective role of Cr.

Investigation of Molecular Mechanisms Involved in Sensitivity to the Anti-Cancer Activity of Costunolide in Breast Cancer Cells

Costunolide (CTL), an active compound isolated from Saussurea lappa Clarke and Laurus nobilis L, has been shown to induce apoptosis via reactive oxygen species (ROS) generation in various types of cancer cells. However, details of molecular mechanisms underlying the difference in sensitivity of cancer cells to CTL are still largely unknown. Here, we tested the effect of CTL on the viability of breast cancer cells and found that CTL had a more efficient cytotoxic effect against SK-BR-3 cells than MCF-7 cells. Mechanically, ROS levels were significantly increased upon CTL treatment only in SK-BR-3 cells, which leads to lysosomal membrane permeabilization (LMP) and cathepsin D release, and subsequent activation of the mitochondrial-dependent intrinsic apoptotic pathway by inducing mitochondrial outer membrane permeabilization (MOMP). In contrast, treatment of MCF-7 cells with CTL activated PINK1/Parkin-dependent mitophagy to remove damaged mitochondria, which prevented the elevation of ROS levels, thereby contributing to their reduced sensitivity to CTL. These results suggest that CTL is a potent anti-cancer agent, and its combination with the inhibition of mitophagy could be an effective method for treating breast cancer cells that are less sensitive to CTL.

Naturally Isolated Sesquiterpene Lactone and Hydroxyanthraquinone Induce Apoptosis in Oral Squamous Cell Carcinoma Cell Line

Oral squamous cell carcinoma (OSCC) is one of the most prevalent cancers worldwide, especially in Asian countries. The emergence of its drug resistance and its side effects demands alternatives, to improve prognosis. Since the majority of cancer drugs are derived from natural sources, it provides a window to look for more biocompatible alternatives. In this study, two natural compounds, costunolide (CE) and aloe emodin (AE), were isolated from the stem of Lycium shawii. The compounds were examined for their anticancer and apoptotic potentials against OSCC (CAL 27) cells, using an in vitro analysis, such as a MTT assay, scratch assay, gene, and protein expressions. Both compounds, CE and AE, were found to be cytotoxic against the cancer cells with an IC₅₀ value of 32 and 38 µM, respectively. Moreover, the compounds were found to be non-toxic against normal NIH-3T3 cells and comparable with the standard drug i.e., 5-fluorouracil (IC₅₀ = 97.76 µM). These compounds were active against normal cells at higher concentrations. Nuclear staining displayed the presence of apoptosis-associated morphological changes, i.e., karyopyknosis and karyorrhexis in the treated cancer cells. Flow cytometry results further confirmed that these compounds induce apoptosis rather than necrosis, as the majority of the cells were found in the late apoptotic phase. Gene and protein expression analyses showed an increased expression of apoptotic genes, i.e., BAK, caspase 3, 6, and 9. Moreover, the compounds significantly downregulated the expression of the anti-apoptotic (BCL-2 L1), metastatic (MMP-2), and pro-inflammatory (COX-2) genes. Both compounds have shown promising anticancer, apoptotic, and anti-migratory activities against the OSCC cell line (i.e., CAL-27). However, further in vivo studies are required to explore these compounds as anticancer agents.

Epithelial Cell Adhesion Molecule (EpCAM) Expression Can Be Modulated via NFκB

The epithelial cell adhesion molecule (EpCAM) is considered an essential proliferation signature in cancer. In the current research study, qPCR induced expression of EpCAM was noted in acute lymphoblastic leukemia (ALL) cases. Costunolide, a sesquiterpene lactone found in crepe ginger and lettuce, is a medicinal herb with anticancer properties. Expression of EpCAM and its downstream target genes (Myc and TERT) wasdownregulated upon treatment with costunolide in Jurkat cells. A significant change in the telomere length of Jurkat cells was not noted at 72 h of costunolide treatment. An in silico study revealed hydrophobic interactions between EpCAM extracellular domain and Myc bHLH with costunolide. Reduced expression of NFκB, a transcription factor of EpCAM, Myc, and TERT in costunolide-treated Jurkat cells, suggested that costunolide inhibits gene expression by targeting NFκB and its downstream targets. Overall, the study proposes that costunolide could be a promising therapeutic biomolecule for leukemia.

Costunolide-Induced Apoptosis via Promoting the Reactive Oxygen Species and Inhibiting AKT/GSK3β Pathway and Activating Autophagy in Gastric Cancer

Objective: Costunolide (Cos) is a sesquiterpene lactone extracted from chicory. Although it possesses anti-tumor effects, the underlying molecular mechanism against gastric cancer cells remains unclear. This study aimed to explore the effect and potential mechanism of Cos on gastric cancer.

Methods: The effect of Cos on HGC-27 and SNU-1 proliferation was detected by CCK-8 and clone formation assay. The changes in cell apoptosis were determined using Hoechst 33258 and tunel staining. The morphology of autophagy was analyzed by autophagosomes with the electron microscope and LC3-immunofluorescence with the confocal microscope. The related protein levels of the cell cycle, apoptosis, autophagy and AKT/GSK3β pathway were determined by Western blot. The anti-tumor activity of Cos was evaluated by subcutaneously xenotransplanting HGC-27 into Balb/c nude mice. The Ki67 and P-AKT levels were examined by immunohistochemistry.

Results: Cos significantly inhibited HGC-27 and SNU-1 growth and induced cell cycle arrest in the G2/M phase. Cos activated intrinsic apoptosis and autophagy through promoting cellular reactive oxygen species (ROS) levels and inhibiting the ROS-AKT/GSK3β signaling pathway. Moreover, preincubating gastric carcinoma cells with 3-methyladenine (3-MA), a cell-autophagy inhibitor, significantly alleviated the effects of Cos in inducing cell apoptosis.

Conclusion: Cos induced apoptosis of gastric carcinoma cells via promoting ROS and inhibiting AKT/GSK3β pathway and activating pro-death cell autophagy, which may be an effective strategy to treat gastric cancer.

Exploring the Potential Mechanism of Costunolide-Induced MCF-7 Cells Apoptosis by Multi-Spectroscopy, Molecular Docking and Cell Experiments

Breast cancer is one of the most common cancer with high morbidity and mortality in women. This study aimed to explore the potential mechanism of costunolide inducing MCF-7 cells apoptosis by multi-spectroscopy, molecular docking, and cell experiments. The results manifested that costunolide interacted with calf thymus DNA (ct-DNA) in a spontaneous manner, and the minor groove as the preferential binding mode. Furthermore, costunolide inhibited cell proliferation and colony formation. Hoechst 33258 staining showed that cell apoptosis induced by costunolide might be related to DNA damage. The apoptosis mechanism relied on regulating the protein expression of Bax, Bcl-2, p53, Caspase-3 and the activation of p38MAPK and nuclear factor κB (NF-κB) pathways. This study will provide some experimental basis and potential therapeutic strategy for breast cancer treatment.

Natural and Synthetic Lactones Possessing Antitumor Activities

Cancer is one of the leading causes of death globally, accounting for an estimated 8 million deaths each year. As a result, there have been urgent unmet medical needs to discover novel oncology drugs. Natural and synthetic lactones have a broad spectrum of biological uses including anti-tumor, anti-helminthic, anti-microbial, and anti-inflammatory activities. Particularly, several natural and synthetic lactones have emerged as anti-cancer agents over the past decades. In this review, we address natural and synthetic lactones focusing on their anti-tumor activities and synthetic routes. Moreover, we aim to highlight our journey towards chemical modification and biological evaluation of a resorcylic acid lactone, L-783277 (4). We anticipate that utilization of the natural and synthetic lactones as novel scaffolds would benefit the process of oncology drug discovery campaigns based on natural products.

Costunolide Induces Autophagy and Apoptosis by Activating ROS/MAPK Signaling Pathways in Renal Cell Carcinoma

Although costunolide (Cos), a natural sesquiterpene compound isolated from various medicinal plants, exhibits antiproliferative and pro-apoptotic effects in diverse types of cancers, the mechanism associated with the anticancer property of Cos has not been elucidated. The present investigation was carried out to study the anticarcinogenic influence of Cos on kidney cancer cells. Several human renal cancer cell lines were used and biological and molecular studies were conducted. It was found that Cos significantly suppressed renal carcinoma cell growth via stimulation of apoptosis and autophagy in a concentration-dependent manner. Further studies revealed that Cos increased Bax/Bcl-2 ratio, decreased mitochondrial transmembrane potential (MMP), and enhanced cytoplasmic levels of cytochrome c, and activation of caspase-9, caspase-3, and cleaved PARP, resulting in cell apoptosis. The autophagy induced by Cos resulted from the formation of GFP-LC3 puncta and upregulation of LC3B II and Beclin-1 proteins. Compared with Cos treatment, the autophagy inhibitor 3-MA or ROS scavenger NAC significantly inhibited apoptosis and autophagy. Moreover, NAC and JNK-specific inhibitor SP600125 attenuated the effect of Cos. Taken together, Cos exerted autophagic and apoptotic effects on renal cancer through the ROS/JNK-dependent signal route. These findings suggest that Cos could be a beneficial anticarcinogenic agent.

Cetuximab enhances oridonin-induced apoptosis through mitochondrial pathway and endoplasmic reticulum stress in laryngeal squamous cell carcinoma cells

Cetuximab plus oridonin showed a synergistic way to kill laryngeal squamous cell carcinoma (LSCC), as been reported previously. The present work further mechanistically extended action of the synergistic effects of combination treatment. Firstly, two LSCC cells displayed higher sensitivity to oridonin, whereas both low EGFR expression tumor cells and EGFR knockdown LSCC cells were less sensitive to oridonin. Next, cetuximab/oridonin significantly enhanced the mitochondrial apoptosis through NF-κB. Meanwhile, PI3K/Akt and JAK2/STAT3 pathways are associated with the nucleus translocation of NF-κB by combination treatment. Additionally, cetuximab enhanced oridonin-promoted ER stress-related apoptosis. Interestingly, both ER stress and mitochondrial apoptosis by combination treatment are abrogated by ROS scavenger. Furthermore, oridonin/cetuximab induced ROS production after 1.5 h, followed by G2/M arrest and apoptosis, indicating that ROS generation might be an early and key event. Taken together, cetuximab enhances oridonin-induced ER stress and mitochondrial apoptotic pathway, which contributes to the synergistic antitumor effects of cetuximab/oridonin.

Ameliorative effects of Magnolia sieboldii buds hexane extract on experimental reflux esophagitis

Gastroesophageal reflux disease (GERD) is a disease that stomach contents continually refluxing into esophagus causes symptoms and/or complications. The study was working to find natural plant extracts with good effects and small side effects to treat reflux esophagitis (RE). The anti-inflammatory effects of hexane extract of Magnolia sieboldii (MsHE) were conducted on lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophage cells. The ameliorative effects of MsHE on esophageal damage in rats induced by gastric acid reflux was explored in vivo. The results showed that MsHE decreased the production of nitric oxide (NO) and expression levels of iNOS, COX-2 and TNF-α on LPS-stimulated RAW 264.7 cells and MsHE treatment ameliorated the rats' esophageal tissue damage induced by gastric acid and inhibited the increase of inflammatory mediators and pro-inflammatory cytokines by regulating NF-κB signaling pathway. In addition, MsHE protected the function of barrier of epithelial cells against inflammatory conditions through increasing the expression of tight junctions. Furthermore, liquid chromatography-mass spectrometry analysis was used for determine the active ingredients contained in MsHE. The results show that MsHE can alleviate experimental rat RE by regulating NF-κB signaling pathway. In summary, MsHE may be used as a source material of drug candidate for the treatment of RE.

Costunolide reduces glycolysis-associated activation of hepatic stellate cells via inhibition of hexokinase-2

Background

Hepatic stellate cell (HSC) activation is a central event during hepatic fibrosis. Aerobic glycolysis is one of its metabolic hallmarks. Blocking glycolysis is a novel therapeutic option for liver fibrosis. This study investigated the effects of costunolide, a natural product demonstrated to have hepatoprotective effects, on HSC activation and glycolysis.

Methods

Primary HSCs were isolated from rats and cultured through 5 to 6 passages. Cell viability, activation markers, and glycolytic metabolism were examined in primary HSCs using various cellular and molecular approaches.

Results

At 30 μM, costunolide reduced the viability of HSCs and inhibited the expression of α-smooth muscle actin and collagen I, two key markers of HSC activation. It also decreased glucose uptake and consumption, and reduced the intracellular levels of lactate in HSCs. At 10 mM, the glycolysis inhibitor 2-DG had a similar impact to costunolide at 30 μM: it significantly downregulated the expression of HSC activation markers. The combination of the two compounds produced more remarkable effects. Furthermore, costunolide repressed the expression and activity of hexokinase 2 (HK2), a pivotal rate-limiting enzyme that regulates glycolysis. However, overexpression of HK2 via plasmid transfection significantly reversed the costunolide-mediated downregulation of activation markers in HSCs, indicating that suppression of HK2 was required for costunolide to inhibit glycolysis-associated HSC activation.

Conclusions

Our results show that costunolide can suppress HSC activation, and this is associated with inhibition of HK2, which blocks aerobic glycolysis. This suggests that costunolide is an antifibrotic candidate with potential for further development.

Costunolide-A Bioactive Sesquiterpene Lactone with Diverse Therapeutic Potential

Sesquiterpene lactones constitute a major class of bioactive natural products. One of the naturally occurring sesquiterpene lactones is costunolide, which has been extensively investigated for a wide range of biological activities. Multiple lines of preclinical studies have reported that the compound possesses antioxidative, anti-inflammatory, antiallergic, bone remodeling, neuroprotective, hair growth promoting, anticancer, and antidiabetic properties. Many of these bioactivities are supported by mechanistic details, such as the modulation of various intracellular signaling pathways involved in precipitating tissue inflammation, tumor growth and progression, bone loss, and neurodegeneration. The key molecular targets of costunolide include, but are not limited to, intracellular kinases, such as mitogen-activated protein kinases, Akt kinase, telomerase, cyclins and cyclin-dependent kinases, and redox-regulated transcription factors, such as nuclear factor-kappaB, signal transducer and activator of transcription, activator protein-1. The compound also diminished the production and/expression of proinflammatory mediators, such as cyclooxygenase-2, inducible nitric oxide synthase, nitric oxide, prostaglandins, and cytokines. This review provides an overview of the therapeutic potential of costunolide in the management of various diseases and their underlying mechanisms.

Protective Effects of Costunolide Against D-Galactosamine and Lipopolysaccharide-Induced Acute Liver Injury in Mice

Costunolide, a sesquiterpene isolated from Vladimiria souliei (Franch.) Ling, is known to exhibit anti-inflammatory, anti-viral, and anti-tumor activities. However, the effects of costunolide on liver injury are poorly understood. The current study aimed to investigate the hepatoprotective effects of costunolide against lipopolysaccharide (LPS) and D-galactosamine-induced acute liver injury (ALI) in mice. The results indicated that costunolide (40 mg/kg) could significantly improve the pathological changes of hepatic tissue, and reduced the LPS and D-galactosamine-induced increases of alanine aminotransferase (from 887.24 ± 21.72 to 121.67 ± 6.56 IU/L) and aspartate aminotransferase (from 891.01 ± 45.24 to 199.94 ± 11.53 IU/L) activities in serum. Further research indicated that costunolide significantly reduced malondialdehyde content (from 24.56 ± 1.39 to 9.17 ± 0.25 nmol/ml) and reactive oxygen species (from 203.34 ± 7.68 to 144.23 ± 7.12%), increased the activity of anti-oxidant enzymes superoxide dismutase (from 153.74 ± 10.33 to 262.27 ± 8.39 U/ml), catalase (from 6.12 ± 0.30 to 12.44 ± 0.57 U/ml), and total anti-oxidant capacity (from 0.64 ± 0.06 to 6.29 ± 0.11 U/ml) in hepatic tissues. Western blot results revealed that costunolide may trigger the anti-oxidative defense system by inhibiting kelch-like ECH-associated protein 1 and nuclear factor-related factor 2 (cytosol), increasing nuclear factor-related factor 2 (nucleus), heme oxygenase-1 and NAD (P) H quinone oxidoreductase 1 activity. Moreover, costunolide significantly decreased the protein expression of proinflammatory cytokines including interleukin 1β, interleukin 6, and tumor necrosis factor. Pretreatment with costunolide could reduce the expression of toll-like receptor 4, myeloid differentiation factor 88, p65 (Nucleus), phosphorylated IκB kinase α/β, inhibitor of nuclear factor kappa-B kinase, inhibitor kappa Bα and prevent the expression of phosphorylated inhibitor kappa B kinase which repressed translocation of p65 from cytoplasm to nucleus. In addition, pretreatment with costunolide also inhibited hepatocyte apoptosis by reducing the expression of B-cell lymphoma 2 associated X, cytochrome C, cysteinyl aspartate specific proteinase 3, cysteinyl aspartate specific proteinase 8 and cysteinyl aspartate specific proteinase 9, and by increasing B-cell lymphoma 2. From the above analysis, the protective effects of costunolide against LPS and D-galactosamine-induced ALI in mice may be attributed to its anti-oxidative activity in nuclear factor-related factor 2 signaling pathways, anti-inflammatory suppression in nuclear factor-kappa B signaling pathways, and inhibition of hepatocyte apoptosis. Thus, costunolide may be a potential therapeutic agent in attenuating LPS and D-galactosamine -induced ALI in the future.

Costunolide isolated from Vladimiria souliei inhibits the proliferation and induces the apoptosis of HepG2 cells

Costunolide (cos) is one of the major sesquiterpenes isolated from the ethyl acetate soluble fraction of the roots of Vladimiria souliei. In order to explore the effects and molecular mechanism of cos, the anti‑proliferative and apoptotic effects of cos against the human hepatoblastoma HepG2 cell line was examined in vitro in the current study. Cell viability was measured using an MTT assay, and IC50 values (indicating the concentration required to achieve half‑maximal inhibition) were calculated to detect the inhibitory effect of cos on HepG2 cell growth. Cell morphology was subsequently observed under an inverted microscope, and cell cycle distribution and apoptosis were detected using flow cytometric analysis. In addition, changes in the protein expression levels of B‑cell lymphoma 2 (Bcl‑2), Bcl‑2‑associated X protein (Bax), and caspases‑3, ‑8 and ‑9 were detected by western blotting. The results of cell analyses indicated that cos treatment inhibited the proliferation and promoted the apoptosis of HepG2 cells in vitro. Cos markedly induced HepG2 cell apoptosis by arresting the cell cycle at the G2/M phase in a dose‑dependent manner. In terms of the underlying mechanism, cos was revealed to inhibit the anti‑apoptotic capacity of the cells, possibly via upregulating the expression levels of Bax protein and caspases‑3, ‑8 and ‑9, and downregulating the expression of Bcl‑2 protein. Taken together, the results of the present study indicate that cos may be a promising candidate for liver cancer therapy, and have provided an insight into the mechanism of action involved in its anti‑cancer properties.

Application of sesquiterpene lactone: A new promising way for cancer therapy based on anticancer activity

Cancer is one of the most dangerous diseases that are rapidly increasing globally. After heart disease, it is the second leading cause of death, accounting for seven million deaths each year. Chemotherapy is the use of cytotoxic drugs on cancer cells. But the use of common chemotherapy drugs poses a problem due their high side effects and low efficacy. As a result, efforts are on to find new potent compounds with low side effects. The compounds extracted from plants have been studied in this regard due to their prevalence. Sesquiterpene lactones are a group of natural compounds that were first detected in Asteraceae dark plants. These compounds exercise their effects by reacting with functional groups available on proteins and enzymes, especially the thiol group. Owing to the high side effects as an antitumor synthetic drugs, efforts are being made to find drugs with high efficiency and low side effects. Their high structural ranges have attracted the attention of many researchers as a potential source of new anticancer drugs.

Costunolide enhances doxorubicin-induced apoptosis in prostate cancer cells via activated mitogen-activated protein kinases and generation of reactive oxygen species

The management of castration-resistant prostate cancer (CRPC) is challenging, attributable to a lack of efficacious therapies. Chemotherapy is one of the most important treatments for CRPC. Doxorubicin has been extensively used in many different tumors and is often combined with other drugs to enhance effects and reduce toxicity. Costunolide is a natural sesquiterpene lactone with anti-cancer properties. In this study, we first demonstrated that the combination of costunolide and doxorubicin induced apoptosis significantly more than either drug alone in prostate cancer cell lines. Costunolide combined with doxorubicin induced mitochondria-mediated apoptosis through a loss of mitochondrial membrane potential and modulation of Bcl-2 family proteins. We found that this drug combination significantly increased the production of reactive oxygen species (ROS), as well as phosphorylation of c-jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinases, which play upstream roles in mitochondria-mediated apoptosis. Further studies showed that N-acetyl cysteine blocked JNK and p38 phosphorylation, suggesting that ROS were upstream activators of JNK and p38. However, a JNK inhibitor, but not a p38 inhibitor, blocked the increase in ROS observed in cells treated with a combination of costunolide and doxorubicin, suggesting that ROS and JNK could activate each other. In vivo, inhibition of tumor growth and induction of apoptosis were greater in mice treated with the costunolide and doxorubicin combination than in mice treated with either drug alone, without an increase in toxicity. Therefore, we suggested that costunolide in combination with doxorubicin was a new potential chemotherapeutic strategy for treating prostate cancer.

Inhibition of the mitochondrial calcium uniporter inhibits Aβ-induced apoptosis by reducing reactive oxygen species-mediated endoplasmic reticulum stress in cultured microglia

Amyloid-beta (Aβ) has been shown to induce microglial apoptosis, which is itself sensitive to disturbed mitochondrial calcium (Ca²⁺) homeostasis. The mitochondrial calcium uniporter (MCU) plays an important regulatory role in mitochondrial Ca²⁺ homeostasis, but its role in Aβ-induced microglia apoptosis is unknown. In this study, we found increased mitochondrial Ca²⁺ concentration in Aβ-treated primary microglia and BV-2 cells; also, the MCU inhibitor Ru360 significantly attenuated Aβ-induced microglial apoptosis, whereas the MCU activator spermine augmented it. In addition, Ru360 significantly attenuated Aβ-induced mitochondrial reactive oxygen species (ROS) production, as well as endoplasmic reticulum (ER) stress characterized by glucose-regulated protein 78 (GRP78) and C/-EBP homologous protein (CHOP) expression. Spermine, however, exerted the opposite effects on mitochondrial ROS production and ER stress. We also found that mitochondria-targeted antioxidant (Mito-TEMPO) treatment decreased GRP78 and CHOP expression in Aβ-treated microglia. Moreover, blocking endogenous CHOP expression using a CHOP small interfering RNA (siRNA) attenuated Aβ-induced cell death. Altogether, our data suggested that 1) inhibition of MCU exerts a neuroprotective effect on Aβ-induced microglia apoptosis, and 2) that the underlying mechanism may be related to reducing mitochondrial ROS-mediated ER stress.

Fibroblast growth factor 21 protects rat cardiomyocytes from endoplasmic reticulum stress by promoting the fibroblast growth factor receptor 1-extracellular signal‑regulated kinase 1/2 signaling pathway

Fibroblast growth factor 21 (FGF21), as an endocrine factor, is secreted into circulation by injured cardiomyocytes. Endoplasmic reticulum (ER) stress-induced apoptosis has been proposed as an important pathophysiological mechanism for cardiomyocyte injury. However, whether the enhanced expression of FGF21 in cardiomyocytes is linked to ER stress, and the effect and underlying mechanism of FGF21 on ER stress-induced cardiomyocyte apoptosis remain unclear. In the present study, it was demonstrated that mild ER stress resulted in upregulated expression levels of FGF21 and its main receptors, as a response to cell compensation, at the induction of ≤5 µM tunicamycin (TM). However, excessive ER stress (TM ≥10 µM) activated the ER stress-mediated apoptosis signaling pathways, including PKR-like ER kinase (PERK)-eukaryotic translational initiation factor 2α (eIF2α)-activating transcription factor 4 (ATF4)-CCAAT/-enhancer-binding protein homologous protein (CHOP) and inositol-requiring kinase 1α (IRE1α)-c-Jun N-terminal kinases (JNK), as well as inhibited the expression of FGF21 and its primary receptors. In addition, FGF21 overexpression provided protection against ER stress-induced cardiomyocyte injury, as evidenced by increased cell viability and reduced apoptosis. These changes were associated with the inhibition of ER stress-mediated apoptosis signaling pathways, as well as increased phosphorylation of FGFR1 and ERK1/2. However, the protective effects of overexpressed FGF21 were abolished following treatment with FGFR1 and ERK1/2 inhibitors. Thus, mild ER stress may induce the expression of FGF21 and its primary receptors in cardiomyocytes. FGF21 inhibits ER stress-induced cardiomyocyte injury as least in part via the FGFR1-ERK1/2 signaling pathway.

Costunolide increases osteoblast differentiation via ATF4-dependent HO-1 expression in C3H10T1/2 cells

AIMS

Costunolide is a sesquiterpene lactones used in many herbal medicines, with well-established anti-inflammatory and anti-oxidant functions modulating endoplasmic reticulum (ER) stress pathways, and which promotes the expression of anti-oxidant genes. The aim of this study is to investigate whether costunolide is involved in osteoblast differentiation and, determine the mechanisms of differentiation in mesenchymal stem cells.

MAIN METHODS

The cytotoxicity of costunolide was identified using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The mRNA and protein expression levels of osteogenic genes were determined by RT-PCR and Western blot analysis. Alkaline phosphate (ALP) staining and Alizarin red S (ARS) staining were performed to evaluate ALP activity and matrix mineralization. Transcriptional activity was detected using a luciferase reporter assay.

KEY FINDINGS

In this study, we determined that costunolide increased the expression of distal-less homeobox 5 (Dlx5), runt-related transcription factor 2 (Runx2), ALP, and osteocalcin (OC) in C3H10T 1/2 cells. Furthermore, costunolide increased ALP activity and matrix mineralization. Interestingly, costunolide increased ER stress by Bip, activating transcription factor 4 (ATF4) and C/EBP homologous protein (CHOP). However, it did not exert effects on expression of activating transcription factor 6 (ATF6). ATF4 activation has a protective role in oxidative stress, and its transcription induces anti-oxidant genes in cells. Heme oxygenase-1 (HO-1) is a major anti-oxidant enzyme, and is regulated by ATF4. We showed that costunolide treatment increased HO-1 expression. Furthermore, the HO-1 inhibitor, Sn(IV) Protoporphyrin IX dichloride (SnPP) was blocked costunolide-induced Runx2 expression.

SIGNIFICANCE

Our results revealed that costunolide-induced osteoblast differentiation is regulated by ATF4-dependent HO-1 expression.