Isoorientin Suppresses the Invasion of Breast and Colon Cancer Cells by Inhibition of CXC Chemokine Receptor 4 Expression.

Cancer metastasis still accounts for up to 90% of cancer-related deaths, but the molecular mechanism for metastasis is unclear. Several chemokines and their receptors mediate tumor cell metastasis, particularly through long-term effects that regulate angiogenesis, tumor cell proliferation and apoptosis. Among them, CXC chemokine receptor 4 (CXCR4) has been shown to play a pivotal role in cancer metastasis through interaction with a ligand (CXCL12), also known as stromal cell-derived factor 1α (SDF-1α). The CXCR4 promoter region is well characterized, and its expression is controlled by various transcriptional factors, including NF-κB, HIF-1α, and so forth. Isoorientin (ISO) is a 3', 4', 5, 7-tetrahydroxy-6-C-glucopyranosyl flavone. ISO has been reported to exhibit anti-oxidant, anti-cancer, and anti-inflammatory properties. However, the anti-metastatic effect of ISO following downregulation of CXCR4 is unknown, and the mechanism underlying the antitumor activity has yet to be elucidated. In our present study, we showed that ISO inhibited the expression of CXCR4 through NF-κB regulation in breast and colon cancer cells. We have also demonstrated that ISO inhibits CXCR4 expression in a variety of tumor cells. Furthermore, we found that CXCR4 expression is regulated through inhibition of the transcription process. Inhibition of CXCR4 expression also reduced the invasion of cancer cells by CXCL12. In conclusion, our results suggest that ISO is a novel inhibitor to regulate CXCR4 expression and the key molecule contributing to antitumor activity.

[Corrigendum] Saffron carotenoids inhibit STAT3 activation and promote apoptotic progression in IL­6­stimulated liver cancer cells.

Following the publication of the above article, an interested reader drew to the authors' attention that, in Fig. 1E on p. 1885, the STAT3 blots shown for the A549 and A2780 cell lines were strikingly similar, such that these data were possibly derived from the same original source where the panels were intended to show the results from differently performed experiments. Upon examining their original data, the authors have realized that an inadvertent error was made in assembling the data in the figure, and the STAT3 data shown correctly for the A549 cell line were erroneously copied across for the A2780 cell line. The corrected version of Fig. 1, showing the correct STAT3 blot for the A2780 cell line in Fig. 1E, is shown on the next page. Note that this error did not affect the overall conclusions reported in the paper. All the authors agree with the publication of this corrigendum, and are grateful to the Editor of Oncology Reports for allowing them the opportunity to publish this. They also apologize to the readership for any inconvenience caused. [Oncology Reports 39: 1883­1891, 2018; DOI: 10.3892/or.2018.6232].

Retraction notice to "Effects of geniposide on hepatocytes undergoing epithelial-mesenchymal transition in hepatic fibrosis by targeting TGFß/Smad and ERK-MAPK signaling pathways" [Biochimie 113 (2015) 26-34].

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the Editor-in-Chief. The corresponding author, Dr Byoungduck Park, requested publication of a corrigendum to correct Fig. 2B which reused control data from a different publication (doi: 10.1016/j.intimp.2015.02.014). Upon further inspection, the Biochimie editorial team noticed that: Comparison of Fig. 2B with Fig. 4C of a previous publication in International Immunopharmacology by two co-authors (doi: 10.1016/j.intimp.2015.02.014) reveals that western blot ß-actin control data from the earlier paper were re-used in a different experiment shown in Fig. 2B of the article in Biochimie, after adjustment of the brightness/contrast. Furthermore, the same bands, after more image manipulation were presented as Smad3 data in Fig. 4C of the Biochimie article. Here the image manipulation involved notably the rotation of the set of bands by 180° and some adjustment of the height/width ratio. The authors apologise for any confusion that may have arisen from their article.

Minecoside promotes apoptotic progression through STAT3 inactivation in breast cancer cells.

Breast cancer is one of the most common malignant tumors in women worldwide, and is a major cause of mortality and morbidity in cancer patients. Constitutive activation of STAT3 has been found in a variety of malignant tumors, including breast cancer. Since STAT3 activation is capable of regulating various important features of tumor cells, identification of a novel STAT3 inhibitor is considered a potential strategy for treating breast cancer. The aim of the present study was to examine whether minecoside (MIN), an active compound extracted from Veronica peregrina L., exerts an antitumor effect by inhibiting STAT3 signaling pathway in MDA-MB-231 cells. The results revealed that MIN inhibited the constitutive STAT3 activation in a dose- and time-dependent manner. MIN also blocked the nuclear translocation of STAT3 and suppressed STAT3-DNA binding. In addition, MIN downregulated the STAT3-mediated expression of proteins such as Bcl-xL, Bcl-2, CXCR4, VEGF, and cyclin D1. Subsequently, MIN promoted the caspase-dependent apoptosis in MDA-MB-231 cells. Overall, results of the present study provide evidence that MIN exerted anticancer activity via inhibition of the STAT3 signaling pathway. Further studies using animal models are required to determine the potential of this molecule as an anticancer drug.

Isoorientin Inhibits Amyloid ß25-35-Induced Neuronal Inflammation in BV2 Cells by Blocking the NF-κB Signaling Pathway.

Alzheimer's disease (AD) is a severe neurodegenerative disorder. AD is pathologically characterized by the formation of intracellular neurofibrillary tangles, and extracellular amyloid plaques which were comprised of amyloid-beta (Aß) peptides. Aß induces neurodegeneration by activating microglia, which triggers neurotoxicity by releasing various inflammatory mediators and reactive oxygen species (ROS). Nuclear factor-kappa B (NF-κB) is expressed in human tissues including the brain and plays an important role in Aß-mediated neuronal inflammation. Thus, the identification of molecules that inhibit the NF-κB pathway is considered an attractive strategy for the treatment and prevention of AD. Isoorientin (3',4',5,7-Tetrahydroxy-6-C-glucopyranosyl flavone; ISO), which can be extracted from several plant species, such as Philostachys and Patrinia is known to have various pharmacological activities such as anticancer, antioxidant, and antibacterial activity. However, the effect of ISO on Aß-mediated inflammation and apoptosis in the brain has yet to be elucidated. In the present study, we investigated whether ISO regulated Aß-induced neuroinflammation in microglial cells and further explored the underlying mechanisms. Our results showed that ISO inhibited the expression of iNOS and COX-2 induced by Aß25-35. And, it inhibited the secretion of pro-inflammatory cytokines such as tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). In addition, ISO reduced the ROS production in Aß25-35-induced BV2 cells and inhibited NF-κB activation. Furthermore, ISO blocked Aß25-35-induced apoptosis of BV2 cells. Based on these findings, we suggest that ISO represents a promising therapeutic drug candidate for the treatment and prevention of AD.

Characterization and Optimization of the Tyrosinase Inhibitory Activity of Vitis amurensis Root Using LC-Q-TOF-MS Coupled with a Bioassay and Response Surface Methodology.

Vitis amurensis roots have been reported to have the potential for skin whitening through the evaluation of melanogenesis and tyrosinase inhibitory activities. In this study, V. amurensis roots were utilized to quickly select whitening ingredients using LC-Q-TOF-MS coupled with tyrosinase inhibitory assay, and to optimize the extraction process for use as a skin whitening functional material by response surface methodology. Results showed that V. amurensis roots exhibited tyrosinase inhibitory effects by two stilbene oligomers, ε-viniferin (1) and vitisin B (2), as predicted by LC-Q-TOF-MS coupled with bioassay. The optimal extraction conditions (methanol concentration 66%, solvent volume 140 mL, and extraction time 100 min) for skin whitening ingredients were established with the yields 6.20%, and tyrosinase inhibitory activity was 87.27%. The relationship between each factor and its corresponding response was confirmed by Pearson's correlation analysis. The solvent volume showed clear linear relationship with yields, and methanol concentration had a strong linear relationship with tyrosinase inhibitory activity for compounds 1 and 2, as well as their combination. Overall, LC-Q-TOF-MS coupled with bioassay was proved to have the potential to effectively find new active constituents, as well as known active constituents; vitisin B can be proposed as a new natural potential whitening agent.

PBN inhibits a detrimental effect of methamphetamine on brain endothelial cells by alleviating the generation of reactive oxygen species.

Methamphetamine (METH) is a powerful psychostimulant that is causing serious health problems worldwide owing to imprudent abuses. Recent studies have suggested that METH has deleterious effects on the blood-brain barrier (BBB). A few studies have also been conducted on the mechanisms whereby METH-induced oxidative stress causes BBB dysfunction. We investigated whether N-tert-butyl-α-phenylnitrone (PBN) has protective effects on BBB function against METH exposure in primary human brain microvascular endothelial cells (HBMECs). We found that METH significantly increased reactive oxygen species (ROS) generation in HBMECs. Pretreatment with PBN decreased METH-induced ROS production. With regard to BBB functional integrity, METH exposure elevated the paracellular permeability and reduced the monolayer integrity; PBN treatment reversed these effects. An analysis of the BBB structural properties, by immunostaining junction proteins and cytoskeleton in HBMECs, indicated that METH treatment changed the cellular localization of the tight (ZO-1) and adherens junctions (VE-cadherin) from the membrane to cytoplasm. Furthermore, METH induced cytoskeletal reorganization via the formation of robust stress fibers. METH-induced junctional protein redistribution and cytoskeletal reorganization were attenuated by PBN treatment. Our results suggest that PBN can act as a therapeutic reagent for METH-induced BBB dysfunction by inhibiting excess ROS generation.

Characterization of Anti-Inflammatory and Antioxidant Constituents from Scutellaria baicalensis Using LC-MS Coupled with a Bioassay Method.

An effective and previously demonstrated screening method for active constituents in natural products using LC-MS coupled with a bioassay was reported in our earlier studies. With this, the current investigation attempted to identify bioactive constituents of Scutellaria baicalensis through LC-MS coupled with a bioassay. Peaks at broadly 17-20 and 24-25 min on the MS chromatogram displayed an inhibitory effect on NO production in lipopolysaccharide-induced BV2 microglia cells. Similarly, peaks at roughly 17-19 and 22 min showed antioxidant activity with an 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS)/2,2-diphenyl-1- picrylhydrazyl (DPPH) assay. For confirmation of LC-MS coupled with a bioassay, nine compounds (1-9) were isolated from an MeOH extract of S. baicalensis. As we predicted, compounds 1, 8, and 9 significantly reduced lipopolysaccharide (LPS)-induced NO production in BV2 cells. Likewise, compounds 5, 6, and 8 exhibited free radical-scavenging activities with the ABTS/DPPH assay. In addition, the structural similarity of the main components was confirmed by analyzing the total extract and EtOAc fractions through molecular networking. Overall, the results suggest that the method comprised of LC-MS coupled with a bioassay can effectively predict active compounds without an isolation process, and the results of molecular networking predicted that other components around the active compound node may also be active.

Methamphetamine-Induced Neuronal Damage: Neurotoxicity and Neuroinflammation.

Methamphetamine (METH) is a highly addictive psychostimulant and one of the most widely abused drugs worldwide. The continuous use of METH eventually leads to drug addiction and causes serious health complications, including attention deficit, memory loss and cognitive decline. These neurological complications are strongly associated with METH-induced neurotoxicity and neuroinflammation, which leads to neuronal cell death. The current review investigates the molecular mechanisms underlying METH-mediated neuronal damages. Our analysis demonstrates that the process of neuronal impairment by METH is closely related to oxidative stress, transcription factor activation, DNA damage, excitatory toxicity and various apoptosis pathways. Thus, we reach the conclusion here that METH-induced neuronal damages are attributed to the neurotoxic and neuroinflammatory effect of the drug. This review provides an insight into the mechanisms of METH addiction and contributes to the discovery of therapeutic targets on neurological impairment by METH abuse.

GKT136901 protects primary human brain microvascular endothelial cells against methamphetamine-induced blood-brain barrier dysfunction.

AIMS: Methamphetamine (METH) is an abused psychostimulant causing public health concern worldwide. While most studies have focused on the neurotoxic effects of METH, METH-induced cerebrovascular dysfunction has recently drawn attention as an important facet of METH-related pathophysiology. In this study, we investigated the protective role of GKT136901, a NOX1/4 inhibitor, against METH-induced blood-brain barrier (BBB) dysfunction. MAIN METHODS: Primary human brain microvascular endothelial cells (HBMECs) were used as an in vitro BBB model. HBMECs were treated with GKT136901, followed by METH exposure for 24 h. The generation of reactive oxidative species (ROS) was measured using 2',7'-dichlorofluorescin diacetate (DCF-DA) staining. To examine the BBB function, paracellular permeability of HBMEC monolayer was measured using FITC-labeled dextran. To evaluate structural properties of BBB in HBMECs, tight junction (TJ), adherent junction (AJ), and cytoskeletal proteins were stained and analyzed by confocal microscopy. KEY FINDINGS: METH treatment rapidly increased ROS generation in HBMECs but GKT136901 treatment inhibited METH-induced ROS generation. Although METH increased the permeability of HBMEC monolayer, this effect was abolished upon GKT136901 treatment. Following METH exposure, the proteins Zonula occludens-1 (ZO-1) and vascular endothelial cadherin (VE-cadherin) were translocalized from the cell membrane to the cytoplasm, thereby destroying intercellular tight junction (TJ) and adherent junction (AJ) structures, which were ameliorated upon GKT136901 treatment. METH exposure altered the cellular morphology of HBMECs and induced stress fiber formation. However, GKT136901 prevented METH-induced morphological and cytoskeletal changes in HBMECs. SIGNIFICANCE: These results suggest that GKT136901 prevents METH-induced BBB dysfunction in HBMECs through the inhibition of ROS generation.

MeBib Suppressed Methamphetamine Self-Administration Response via Inhibition of BDNF/ERK/CREB Signal Pathway in the Hippocampus.

Methamphetamine (MA) is one of the most commonly abused drugs in the world by illegal drug users. Addiction to MA is a serious public health problem and effective therapies do not exist to date. It has also been reported that behavior induced by psychostimulants such as MA is related to histone deacetylase (HDAC). MeBib is an HDAC6 inhibitor derived from a benzimidazole scaffold. Many benzimidazole-containing compounds exhibit a wide range of pharmacological activity. In this study, we investigated whether HDAC6 inhibitor MeBib modulates the behavioral response in MA self-administered rats. Our results demonstrated that the number of active lever presses in MA self-administered rats was reduced by pretreatment with MeBib. In the hippocampus of rats, we also found MA administration promotes GluN2B, an NMDA receptor subunit, expression, which results in sequential activation of ERK/CREB/BDNF pathway, however, MeBib abrogated it. Collectively, we suggest that MeBib prevents the MA seeking response induced by MA administration and therefore, represents a potent candidate as an MA addiction inhibitor.

In vitro synergistic effect of retapamulin with erythromycin and quinupristin against Enterococcus faecalis.

To find a therapeutic alternative for the treatment of skin and soft tissue infections, we evaluated the effects of combinations of retapamulin with macrolide, lincosamide, and streptogramin (MLS) antibiotics against Staphylococcus aureus, Streptococcus pyogenes, Enterococcus faecium, and Enterococcus faecalis. Using both the disk diffusion test and checkerboard assay, we initially examined the effects of combinations of retapamulin with MLS antibiotics against standard strains of these species. Combinations of retapamulin with erythromycin, quinupristin/dalfopristin and quinupristin showed synergistic activity against E. faecalis only. Synergy of retapamulin with clindamycin and dalfopristin was not observed. Then, a checkerboard assay was performed to evaluate the effects of the combinations against 15 clinical strains of E. faecalis. Retapamulin and quinupristin, the most synergistic combination, showed activity against all erythromycin-susceptible, -intermediate, and -resistant strains tested. Among the eight strains with high-level erythromycin resistance, five strains were synergistically inhibited in the presence of only 1 µg of retapamulin per ml. Time-kill assay revealed that combinations of retapamulin with erythromycin and quinupristin were bacteriostatic. These results suggest that combinations of retapamulin with erythromycin and quinupristin have in vitro synergistic activity against E. faecalis, including strains with high-level erythromycin resistance.

Icariin sensitizes human colon cancer cells to TRAIL­induced apoptosis via ERK­mediated upregulation of death receptors.

Tumor necrosis factor­associated apoptosis­inducing ligand (TRAIL) is considered to be a potential therapeutic target for various types of cancer. However, colon cancer is difficult to treat due to its resistance to TRAIL. Therefore, various trials have been conducted to overcome TRAIL resistance in colon cancer. The present study aimed to determine whether icariin (ICA) may sensitize human colon cancer cells to TRAIL­induced apoptosis in vitro and in vivo. In the investigation of the effect of ICA on TRAIL­induced apoptosis, the LIVE/DEAD assay results demonstrated that TRAIL plus ICA synergistically induced apoptosis in 49% of HCT116 colon cancer cells. These results were confirmed using long­term colony formation assay. ICA potentiated TRAIL­induced apoptosis by modulating the expression of apoptotic proteins and the induction of cell surface death receptors (DRs) 4 and 5. Upregulation of DRs by ICA was also observed at the transcriptional level by RT­PCR. The expression of DR by ICA was increased through the production of reactive oxygen species (ROS). The results also suggested that increased expression of DR by ICA may be due to the activation of ERK and induction of the transcription factor CCAAT enhancer­binding protein homologous protein (CHOP). NAC, a ROS scavenger, reduced the effect of ICA on ERK activation, DR induction and sensitization of TRAIL­induced apoptosis. In addition, ICA enhanced the effects of TRAIL to reduce tumor growth in an in vivo xenograft mouse model. Overall, the present study provided evidence that ICA sensitized tumor cells to TRAIL­induced apoptosis via ROS­, ERK­ and CHOP­mediated upregulation of DR5 and DR4. Based on these results, it is suggested that the antitumor activity of ICA and TRAIL co­treatment in vitro and in vivo may be used as an effective therapeutic agent in chemotherapy.

Minecoside Modulates Cell Invasion via Regulation of CXCR4 Expression in Breast and Colon Cancer Cells.

Metastasis, which is closely linked to cancer-related deaths, is a highly complex process. It is an organ-specific process and involves interactions between the host and cancer cells. CXC chemokine receptor 4 is known to be expressed in various tumors and the binding with CXC ligand 12 induces signaling in cancer cell survival, migration, and proliferation. Particularly, the CXC chemokine receptor 4/CXC ligand 12 axis is known to promote the metastasis of breast cancer. Thus, agents that can downregulate CXC chemokine receptor 4 expression have potential against cancer metastasis. Minecoside is an active compound extracted from Veronica peregrina L. It is widely distributed in Korea and has been used as a traditional drug for the treatment of various chronic diseases. However, the anticancer and anti-inflammatory effects of minecoside have yet to be clarified. In this study, we found that minecoside downregulates constitutive CXC chemokine receptor 4 expression in MDA-MB-231 breast cancer cells. This downregulation also occurred at the transcriptional level. Minecoside-mediated suppression of CXC chemokine receptor 4 expression inhibited CXC ligand 12-induced invasion of breast and colorectal cancer cells. Overall, our results suggest that minecoside can be a novel anticancer agent that can inhibit cancer metastasis through inhibition of CXC chemokine receptor 4 expression.

Development of Thiazolidinedione-Based HDAC6 Inhibitors to Overcome Methamphetamine Addiction.

Thiazolidinedione is a five-membered heterocycle that is widely used in drug discovery endeavors. In this study, we report the design, synthesis, and biological evaluation of a series of thiazolidinedione-based HDAC6 inhibitors. In particular, compound 6b exerts an excellent inhibitory activity against HDAC6 with an IC50 value of 21 nM, displaying a good HDAC6 selectivity over HDAC1. Compound 6b dose-dependently induces the acetylation level of α-tubulin via inhibition of HDAC6 in human neuroblastoma SH-SY5Y cell line. Moreover, compound 6b efficiently reverses methamphetamine-induced morphology changes of SH-SY5Y cells via regulating acetylation landscape of α-tubulin. Collectively, compound 6b represents a novel HDAC6-isoform selective inhibitor and demonstrates promising therapeutic potential for the treatment of methamphetamine addiction.

Activation of Mevalonate Pathway via LKB1 Is Essential for Stability of Treg Cells.

The function of regulatory T (Treg) cells depends on lipid oxidation. However, the molecular mechanism by which Treg cells maintain lipid metabolism after activation remains elusive. Liver kinase B1 (LKB1) acts as a coordinator by linking cellular metabolism to substrate AMP-activated protein kinase (AMPK). We show that deletion of LKB1 in Treg cells exhibited reduced suppressive activity and developed fatal autoimmune inflammation. Mechanistically, LKB1 induced activation of the mevalonate pathway by upregulating mevalonate genes, which was essential for Treg cell functional competency and stability by inducing Treg cell proliferation and suppressing interferon-gamma and interleukin-17A expression independently of AMPK. Furthermore, LKB1 was found to regulate intracellular cholesterol homeostasis and to promote the mevalonate pathway. In agreement, mevalonate and its metabolite geranylgeranyl pyrophosphate inhibited conversion of Treg cells and enhanced survival of LKB1-deficient Treg mice. Thus, LKB1 is a key regulator of lipid metabolism in Treg cells, involved in optimal programming of suppressive activity, immune homeostasis, and tolerance.

Hair Metabolomics in Animal Studies and Clinical Settings.

Metabolomics is a powerful tool used to understand comprehensive changes in the metabolic response and to study the phenotype of an organism by instrumental analysis. It most commonly involves mass spectrometry followed by data mining and metabolite assignment. For the last few decades, hair has been used as a valuable analytical sample to investigate retrospective xenobiotic exposure as it provides a wider window of detection than other biological samples such as saliva, plasma, and urine. Hair contains functional metabolomes such as amino acids and lipids. Moreover, segmental analysis of hair based on its growth rate can provide information on metabolic changes over time. Therefore, it has great potential as a metabolomics sample to monitor chronic diseases, including drug addiction or abnormal conditions. In the current review, the latest applications of hair metabolomics in animal studies and clinical settings are highlighted. For this purpose, we review and discuss the characteristics of hair as a metabolomics sample, the analytical techniques employed in hair metabolomics and the consequence of hair metabolome alterations in recent studies. Through this, the value of hair as an alternative biological sample in metabolomics is highlighted.

Correction to: Development of a column-switching LC-MS/MS method of tramadol and its metabolites in hair and application to a pharmacogenetic study.

In the original version of the article titled "Development of a column-switching LC-MS/MS method of tramadol and its metabolites in hair and application to a pharmacogenetic study", published in 41(5):554-563 (https://doi.org/10.1007/s12272-018-1013-7), unfortunately an important statement was missing in the Clinical study section by the author.

Neotuberostemonine inhibits osteoclastogenesis via blockade of NF-κB pathway.

Osteoporosis has been attributed to low bone mass arising from cellular communications between bone formation and bone resorption. Osteoclastogenesis is induced by M-CSF and RANKL in hematopoietic lineage cells. Once RANK/RANKL complex is formed, TRAF6 is recruited and triggers the activation of NF-κB pathway and the expression of osteoclast-related genes including NFATc1. Neotuberostemonine (NTS) is an active compound isolated from Stemona tuberosa Lour. Pharmacologically, NTS has been known to possess antitussive, anti-fibrotic and anti-inflammatory activities through regulation of macrophage. However, the influence of NTS to osteoclastogenesis has not been reported. The purpose of this study is to investigate whether NTS can modulate the osteoclastogenesis induced by RANKL or cancer cells. We found that NTS inhibits RANKL- or cancer cell-mediated osteoclastogenesis via blockade of TRAF6 and NF-κB activation. NTS also impairs the formation of F-actin ring structure, an important feature of osteoclast differentiation and function. These results indicate that NTS can be a preventive and therapeutic candidate for bone-related disease and that NTS provides insights underlying molecular mechanisms that influence osteoclastogenesis.

Epicatechin Prevents Methamphetamine-Induced Neuronal Cell Death via Inhibition of ER Stress.

Methamphetamine (METH) acts strongly on the nervous system and damages neurons and is known to cause neurodegenerative diseases such as Alzheimer's and Parkinson's. Flavonoids, polyphenolic compounds present in green tea, red wine and several fruits exhibit antioxidant properties that protect neurons from oxidative damage and promote neuronal survival. Especially, epicatechin (EC) is a powerful flavonoid with antibacterial, antiviral, antitumor and antimutagenic effects as well as antioxidant effects. We therefore investigated whether EC could prevent METH-induced neurotoxicity using HT22 hippocampal neuronal cells. EC reduced METH-induced cell death of HT22 cells. In addition, we observed that EC abrogated the activation of ERK, p38 and inhibited the expression of CHOP and DR4. EC also reduced METH-induced ROS accumulation and MMP. These results suggest that EC may protect HT22 hippocampal neurons against METH-induced cell death by reducing ER stress and mitochondrial damage.