Improvement of gefitinib-resistance of PC9/GR by thapsigargin combined with gefitinib / 药学实践杂志

Objective To study the effect and mechanism of the thapsigargin combined with gefitinib on the proliferation of human lung adenocarcinoma gefitinib resistance cell line PC9/GR. Methods The cell viability of PC9/GR treated with gefitinib alone or gefitinib combined with thapsigargin was evaluated by CCK8 assay. The flow cytometry was used to analyze the PC9/GR cell apoptosis indued by the two group drugs. The ATF-6 and IRE1α protein expression of PC9/GR cells treated with the two group drugs were detected by Western blotting. Results The group of drug combination exhibited enhanced ability to inhibit cell proliferation, promote cell apoptosis and upregulate the ATF-6 and IRE1α protein expression of the PC9/GR compared with the group gefitinib used alone. Conclusion The sensitivity of PC9/GR to gefitinib was increased when the cells were treated by thapsigargin, which may be related with the state of endoplasmic reticulum stress（ERS） induced by thapsigargin.

Translocation of IGF-1R in endoplasmic reticulum enhances SERCA2 activity to trigger Ca2+ER perturbation in hepatocellular carcinoma

The well-known insulin-like growth factor 1 (IGF1)/IGF-1 receptor (IGF-1R) signaling pathway is overexpressed in many tumors, and is thus an attractive target for cancer treatment. However, results have often been disappointing due to crosstalk with other signals. Here, we report that IGF-1R signaling stimulates the growth of hepatocellular carcinoma (HCC) cells through the translocation of IGF-1R into the ER to enhance sarco-endoplasmic reticulum calcium ATPase 2 (SERCA2) activity. In response to ligand binding, IGF-1Rβ is translocated into the ER by β-arrestin2 (β-arr2). Mass spectrometry analysis identified SERCA2 as a target of ER IGF-1Rβ. SERCA2 activity is heavily dependent on the increase in ER IGF-1Rβ levels. ER IGF-1Rβ phosphorylates SERCA2 on Tyr990 to enhance its activity. Mutation of SERCA2-Tyr990 disrupted the interaction of ER IGF-1Rβ with SERCA2, and therefore ER IGF-1Rβ failed to promote SERCA2 activity. The enhancement of SERCA2 activity triggered Ca2+ER perturbation, leading to an increase in autophagy. Thapsigargin blocked the interaction between SERCA2 and ER IGF-1Rβ and therefore SERCA2 activity, resulting in inhibition of HCC growth. In conclusion, the translocation of IGF-1R into the ER triggers Ca2+ER perturbation by enhancing SERCA2 activity through phosphorylating Tyr990 in HCC.

TRPC6 involves in endoplasmic reticulum stress induced apoptosis of glomerular mesangial cells / 西安交通大学学报(医学版)

【Objective】 To explore the role and mechanism of TRPC6 in apoptosis of glomerular mesangial cells (HBZY-1) induced by endoplasmic reticulum stress (ERS). 【Methods】 The experiment groups were classified as follows: normal control (NC), thapsigargin (TG), TG+SKF96365, and TG+TRPC6 siRNA groups. Transcription and protein expressions of TRPC6 and ERS related proteins (GRP78 and Caspase12) were detected by qRT-PCR and Western blotting. Additionally, cell apoptosis was measured by flow cytometry and Hoechst33258. Finally, Fluo-4 AM Ca2+ imaging technique was used to determine changes of intracellular calcium ( [Ca2+] i) by laser scanning confocal microscope. 【Results】 Morphological changes of apoptotic cells were characterized by nuclear enrichment or nuclear fragmentation, and the apoptosis rate was increased after TG stimulation. The expressions of TRPC6 and ERS related proteins (GRP78 and Caspase12) were elevated in TG group compared with NC group (P<0.05). Pre-incubation of HBZY-1 cells with SKF96365 and TRPC6 siRNA decreased cell apoptosis (P<0.05). The entry of [Ca2+] i also increased after TG stimulation (P<0.05). The expressions of TRPC6, GRP78 and Caspase12 were downregulated compared with TG group after treatment with SKF96365 and TRPC6 siRNA accompanied by decreased [Ca2+] i (P<0.05). 【Conclusion】 Taken together, this study suggests that inhibition of TRPC6 can alleviate TG-induced HBZY-1 cell apoptosis.

Calreticulin promotes thapsigargin induced epithelial mesenchymal transition in pancreatic cancer cells / 中华普通外科杂志

Objective:To investigate the effect of CRT on thapsigargin (TG)-induced epithelial mesenchymal transition (EMT) of pancreatic cancer (PC) cells.Methods:Immunohistochemistry was used to investigate the differential CRT expression in PC tissues. Western blot (WB) and transwell were used to detect the effect of CRT silencing on TG induced EMT phenotype. Fluro-4/AM and confocal microscopy were used to detect intracellular calcium level in PC cells.Results:CRT was overexpressed in PC tissues ( P<0.01). Overexpression of CRT was positively associated with lymph node metastasis ( P=0.017) and UICC stage ( P=0.021) of PC patients, and negatively associated with E-cadherin expression ( P=0.013). High CRT and low E-cad expression contributed to the poor prognosis of PC patients ( P=0.023). In PC cells, TG induced EMT phenotype was reversed by siRNA-mediated CRT silencing. TG induced EMT was significantly reversed by CRT silencing in vitro. Conclusions:CRT mediates TG induced intracytoplasmic Ca 2+, and ultimately promotes EMT of PC cells.

A preliminary study on thapsigargin promoting coxsackievirus B3 replication through activating transcription factor 6 pathway / 中华实验和临床病毒学杂志

Objective@#To investigate the effect of thapsigargin (TG) which can induce endoplasmic reticulum stress (ERS) on the replication of coxsackievirus B 3 (CV-B3).@*Methods@#After 10 MOI CV-B3 infected HeLa cells were exposed 0.25 μmol/L TG for 3 h, 6 h and 9 h, virus RNA of HeLa cells were extracted and viral replication was evaluated by real time PCR. After 0.25 μmol/L、0.08 μmol/L and 0.025 μmol/L TG exposed, the plaque of CV-B3 was used to confirm further replication of CV-B3. To verify TG induced ERS through three signal pathway, one of among PERK, ATF6 and IRE1 inhibitors GSK2656157, AEBSF and STF-083010, and 0.25 μmol/L TG were used in HeLa cells infected with 10 MOI CV-B3, replication of CV-B3 was evaluated by qRT-PCR.@*Results@#The stimulation of TG did not induce increase of virus replication after post-infection 3 h. However, TG induced replication of virus to increase 2.5 times after post-infection 6 h and 158.6 times after post-infection 9 h. And, the area of viral plaque was significantly increased. ATF6 inhibitors AEBSF significantly inhibited promotion of virus replication from TG.@*Conclusions@#TG can promote the replication of CV-B3 through ATF6 signal pathway.

Thapsigargin Increases IL-2 Production in T Cells at Nanomolar Concentrations

Thapsigargin (TGN) is a potent and selective inhibitor of sarco-endoplasmic Ca²⁺-ATPase, leading to rapid elevation of cytoplasmic Ca2+ concentration. Previous reports have shown that TGN increases the production of various cytokines from macrophages and dendritic cells. Here, we examine the effects of TGN on murine T cells. Nanomolar concentrations of TGN are a significant inducer of IL-2 production with full activity at 50 nM. Micromolar concentrations of TGN, however, are inhibitory to IL-2 production and T cell proliferation. The IL-2 production-inducing activity of TGN is much more prominent when T cells are primed with concanavalin A or anti-CD3 mAb, and is due to the increase of cytoplasmic Ca²⁺ concentration. TGN at 50 nM does not affect interferon-gamma or IL-4 production from T cells. Thus, the present study shows that low nanomolar concentrations of TGN could be useful in potentiating IL-2 production from antigen-primed T cells.

Sequestration of sorcin by aberrant forms of tau results in the defective calcium homeostasis

Neurofi brillary tangles (NFTs) of microtubule-associated protein tau are a pathological hallmark of Alzheimer's disease (AD). Endoplasmic reticulum (ER) stress has been known to be involved in the pathogenesis of AD. However, the exact role of ER stress in tau pathology has not yet been clearly elucidated. In present study, the possible relationship between tau pathology and ER stress was examined in terms of sorcin, which is a calcium binding protein and plays an important role in calcium homeostasis. Our previous yeast two hybrid study showed that sorcin is a novel tau interacting protein. Caspase-3-cleaved tau (T4C3) showed significantly increased tau-sorcin interaction compared to wild type tau (T4). Thapsigargin-induced ER stress and co-expression of constitutively active GSK3β (GSK3β-S9A) also exhibited significantly increased tau-sorcin interactions. T4C3-expressing cells showed potentiated thapsigargin-induced apoptosis and disruption of intracellular calcium homeostasis compared to T4-expressing cells. Overexpression of sorcin signifi cantly attenuated thapsigargin-induced apoptosis and disruption of calcium homeostasis. In contrary, siRNA-mediated knock-down of sorcin showed significantly increased thapsigargin-induced apoptosis and disruption of calcium homeostasis. These data strongly suggest that sequestration of sorcin by aberrant forms of tau compromises the function of sorcin, such as calcium homeostasis and cellular resistance by ER stress, which may consequently result in the contribution to the progression of AD.

Development of cell models for high-throughput screening system of Charcot-Marie-Tooth disease type 1

PURPOSE: Charcot-Marie-Tooth disease (CMT) is a peripheral neuropathy mainly divided into CMT type 1 (CMT1) and CMT2 according to the phenotype and genotype. Although molecular pathologies for each genetic causative have not been revealed in CMT2, the correlation between cell death and accumulation of misfolded proteins in the endoplasmic reticulum (ER) of Schwann cells is well documented in CMT1. Establishment of in vitro models of ER stress-mediated Schwann cell death might be useful in developing drug-screening systems for the treatment of CMT1. MATERIALS AND METHODS: To develop high-throughput screening (HTS) systems for CMT1, we generated cell models using transient expression of mutant proteins and chemical induction. RESULTS: Overexpression of wild type and mutant peripheral myelin protein 22 (PMP22) induced ER stress. Similar results were obtained from mutant myelin protein zero (MPZ) proteins. Protein localization revealed that expressed mutant PMP22 and MPZ proteins accumulated in the ER of Schwann cells. Overexpression of wild type and L16P mutant PMP22 also reduced cell viability, implying protein accumulation-mediated ER stress causes cell death. To develop more stable screening systems, we mimicked the ER stress-mediated cell death in Schwann cells using ER stress inducing chemicals. Thapsigargin treatment caused cell death via ER stress in a dose dependent manner, which was measured by expression of ER stress markers. CONCLUSION: We have developed genetically and chemically induced ER stress models using Schwann cells. Application of these models to HTS systems might facilitate the elucidation of molecular pathology and development of therapeutic options for CMT1.

PQS attenuates cardiomyocyte apoptosis induced by thapsigargin through inhibiting endoplasmic reticulum stress / 中国病理生理杂志

AIM:To study the effect of Panax quinquefolium saponin (PQS) on cardiomyocyte apoptosis in-duced by thapsigargin ( TG) .METHODS:Primary cultured cardiomyocytes from neonatal SD rats were divided into con-trol group, TG group, PQS (40 mg/L, 80 mg/L and 160 mg/L) +TG group, si-PERK+TG group, and mock+TG group.The cells were treated with 1 μmol/L TG for 24 h to induce apoptosis.The PERK gene in the cardiomyocytes was knocked down by RNAi.The cell viability was detected by CCK-8 assay.Apoptosis was analyzed by flow cytometry.Wes-tern blotting was used to determine the expression of ERS molecules GRP78, CRT, ATF4 and CHOP, anti-apoptosis pro-tein Bcl-2 and pro-apoptosis protein Bax.RESULTS: Compared with control group, TG significantly and the apoptosis, reduced the cell viability (P<0.05), increased the phosphorylation of PERK and eIF2α, increased the expression of GRP78, CRT, ATF4, CHOP and pro-apoptosis protein Bax, and decreased the expression of anti-apoptosis protein Bcl-2 (P<0.05).Compared with TG group, PQS treatment (160 mg/L) significantly reduced the apoptosis and increased the cell viability (P<0.05).All the 3 different concentrations of PQS significantly increased the expression of anti-apoptosis protein Bcl-2 and reduced the expression of pro-apoptosis protein Bax (P<0.05) in a dose-dependent manner.PQS pre-treatment and knockdown of PERK both reduced the protein levels of GRP78, CRT, PERK, p-PERK, eIF2α, p-eIF2α, ATF4, CHOP and pro-apoptosis protein Bax, and increased the expression of anti-apoptosis protein Bcl-2 (P<0.05). CONCLUSION:PQS at concentration of 160 mg/L attenuated cardiomyocyte apoptosis induced by TG.PQS had the simi-lar effect as PERK knockdown on cardiomyocyte apoptosis.The mechanism may be associated with inhibiting PERK-eIF2α-ATF4-CHOP pathway of ERS-related apoptosis.

Rat vas deferens SERCA2 is modulated by Ca2+/calmodulin protein kinase II-mediated phosphorylation

Ca2+ pumps are important players in smooth muscle contraction. Nevertheless, little information is available about these pumps in the vas deferens. We have determined which subtype of sarco(endo)plasmic reticulum Ca2+-ATPase isoform (SERCA) is expressed in rat vas deferens (RVD) and its modulation by calmodulin (CaM)-dependent mechanisms. The thapsigargin-sensitive Ca2+-ATPase from a membrane fraction containing the highest SERCA levels in the RVD homogenate has the same molecular mass (∼115 kDa) as that of SERCA2 from the rat cerebellum. It has a very high affinity for Ca2+ (Ca0.5 = 780 nM) and a low sensitivity to vanadate (IC50 = 41 µM). These facts indicate that SERCA2 is present in the RVD. Immunoblotting for CaM and Ca2+/calmodulin-dependent protein kinase II (CaMKII) showed the expression of these two regulatory proteins. Ca2+ and CaM increased serine-phosphorylated residues of the 115-kDa protein, indicating the involvement of CaMKII in the regulatory phosphorylation of SERCA2. Phosphorylation is accompanied by an 8-fold increase of thapsigargin-sensitive Ca2+ accumulation in the lumen of vesicles derived from these membranes. These data establish that SERCA2 in the RVD is modulated by Ca2+ and CaM, possibly via CaMKII, in a process that results in stimulation of Ca2+ pumping activity.

alpha-Mangostin Reduced ER Stress-mediated Tumor Growth through Autophagy Activation

alpha-Mangostin is a xanthon derivative contained in the fruit hull of mangosteen (Garcinia mangostana L.), and the administration of alpha-Mangostin inhibited the growth of transplanted colon cancer, Her/CT26 cells which expressed Her-2/neu as tumor antigen. Although alpha-Mangostin was reported to have inhibitory activity against sarco/endoplasmic reticulum Ca2+ ATPase like thapsigargin, it showed different activity for autophagy regulation. In the current study, we found that alpha-Mangostin induced autophagy activation in mouse intestinal epithelial cells, as GFP-LC3 transgenic mice were orally administered with 20 mg/kg of alpha-Mangostin daily for three days. However, the activation of autophagy by alpha-Mangostin did not significantly increase OVA-specific T cell proliferation. As we assessed ER stress by using XBP-1 reporter system and phosphorylation of eIF2alpha, thapsigargin-induced ER stress was significantly reduced by alpha-Mangostin. However, coadministration of thapsigargin with alpha-Mangostin completely blocked the antitumor activity of alpha-Mangostin, suggesting ER stress with autophagy blockade accelerated tumor growth in mouse colon cancer model. Thus the antitumor activity of alpha-Mangostin can be ascribable to the autophagy activation rather than ER stress induction.

Baicalein protects HT22 murine hippocampal neuronal cells against endoplasmic reticulum stress-induced apoptosis through inhibition of reactive oxygen species production and CHOP induction

Baicalein is one of the major flavonoids in Scutellaria baicalensis Georgi and possesses various effects, including cytoprotection and anti-inflammation. Because endoplasmic reticulum (ER) stress has been implicated in neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, and cerebral ischemia, we investigated the effects of baicalein on apoptotic death of HT22 mouse hippocampal neuronal cells induced by thapsigargin (TG) and brefeldin A (BFA), two representative ER stress inducers. Apoptosis, reactive oxygen species (ROS) production, and mitochondrial membrane potential (MMP) were measured by flow cytometry. Expression level and phosphorylation status of ER stress-associated proteins and activation and cleavage of apoptosis-associated proteins were analyzed by Western blot. Baicalein reduced TG- and BFA-induced apoptosis of HT22 cells and activation and cleavage of apoptosis-associated proteins, such as caspase-12 and -3 and poly(ADP-ribose) polymerase. Baicalein also reduced the TG- and BFA-induced expression of ER stress-associated proteins, including C/EBP homologous protein (CHOP) and glucose-regulated protein 78, the cleavage of X-box binding protein-1 and activating transcription factor 6alpha, and the phosphorylation of eukaryotic initiation factor-2alpha and mitogen-activated protein kinases, such as p38, JNK, and ERK. Knock-down of CHOP expression by siRNA transfection and specific inhibitors of p38 (SB203580), JNK (SP600125), and ERK (PD98059) as well as anti-oxidant (N-acetylcysteine) reduced TG- or BFA-induced cell death. Baicalein also reduced TG- and BFA-induced ROS accumulation and MMP reduction. Taken together, these results suggest that baicalein could protect HT22 neuronal cells against ER stress-induced apoptosis by reducing CHOP induction as well as ROS accumulation and mitochondrial damage.

Effect of N-acetyl-L-cysteine on endoplasmic reticulum oxidative stress mediated HepG2 cells apoptosis / 中华传染病杂志

Objective To analyze the effect of N-acetyl-L-cysteine(NAC)on endoplasmic reticulum stress mediated HepG2 cells apoptosis and evaluate the role of NAC in the treatment of liver injury.Methods HepG2 cells were treated with thapsigargin(TG)to establish the model of oxidative endoplasmic reticulum stress mediated apoptosis,and NAC was used to intervene in apoptosis.To evaluate the apoptosis,various methods such as MTT assay,flow cytometry,DNA ladder and Western blot were performed.Results After treated with 2 μmol/L TG for 0,24,36 and 48 hours,the vitality of HepG2 cells decreased.The ratio of apoptotic cells increased along with the prolonged treatment duration of TG(0.7%±0.5%,27.6%±6.3%,29.7%±3.3%,47.9%±3.5% respectively,P<0.05),and the production of reactive oxygen species(ROS)also increased in time-dependent manner(14.0%±0.5%,36.1%±3.0%,38.2%±6.0%,48.3%±12.4%,P<0.05).The HepG2 cells showed typical morphologic change of endoplasmic retieulum stress induced by 2 μmol/L TG after 36 h and 48 h.DNA ladder was observed at the same concentration and time point correspondingly.Endoplasmic reticulum stress mediated-apoptosis was confirmed by Western blot.Both 10 mmol/L and 20 mmol/L NAC could protect ceils from apoptosis.The ratio of apoptotic cells decreased to 14.0%±1.3% and 11.0%±0.3%,respectively.The production of ROS decreased to 34.7%±0.8% and 31.5%±2.9%,respectively.The effect was related to the concentration of NAC.Conclusions As a Ca2+-adenosine triphoshatase inhibitor,TG may disrupt intracellular calcium homeostasis,which can induce endoplasmie reticulum stress and apoptosis.NAC,the precursor of the synthesis of-SH,can directly inhibit the ROS reaction and alleviate liver damage,which may play a role in the treatment of liver failure.

Effects of ClC-3 chloride channel on the Ca~(2+) movement induced by Thapsigargin in PC12 cells / 中国药理学通报

0.05).SK & F96365 at the concentration of 5～20 ?mol?L-1 inhibited the Ca2+ influx induced by 1.0 ?mol?L-1 Thapsigargin in a concentration-dependent manner.The inhibitory effect of SK & F96365 on Ca2+ influx was decreased by overexpression of ClC-3 protein.Conclusion ClC-3 chloride channel was involved in the regulation of store-operated Ca2+ entry(SOCE).

Research on the Induction of Apoptosis in MCF-7 Cells Enhanced by Thapsigargin / 中国普外基础与临床杂志

Objective To study the apoptotic induction effect of Thapsigargin on estrogen receptor positive human breast cancer cell lines MCF 7. Methods Cells were treated with Thapsigargin and 5 FU in vitro . The rate of cell apoptosis and distribution of cell cycle were detected on flow cytometry. The cell viability was measured by MTT assay and ultrastructural changes in apoptotic cells were confirmed by transmission electron microscopy.Results Thapsigargin could increase the rates both of cell apoptosis and growth supression of MCF 7 cells induced by 5 FU and alter the distribution of cell cycle. Under electron microscope, apoptotic bodies in MCF 7 cells considerably increased.Conclusion Thapsigargin apparently enhances the effect of apoptotic induction of 5 FU on MCF 7 cells, it is worthy of being further studied.

Inhibitive effect of cliary neurotrophic factor on thapsigargin-induced increase of intracellular -[Ca~(2+)-]_i in cultured hippocampal neurons / 第二军医大学学报

Objective:To observe the effect of ciliary neurotrophic factor (CNTF) on the increase of hippocampal neurons -[Ca~(2+)-]_i induced by thapsigargin (Tg), a sarco/endoplasmic reticulum Ca~(2+)-ATPase (SERCA2a) inhibitor. Methods: The primarily cultured hippocampal neurons of newborn SD rats(within 24 h of delivery) were prepared after 10-14 d culture. The intracellular -[Ca~(2+)-]_i was measured with Fura-2/AM in real time. The neurons were divided into 3 groups. Group A (n=20), EGTA (3 mmol/L);Group B (n=40), EGTA (3 mmol/L) + Tg (10 ?mol/L);and Group C (n=12), EGTA (3 mmol/L) +Tg (10 ?mol/L) +CNTF (500 U/?l). Results: When the extracellular Ca~(2+) was chelated by enough EGTA, -[Ca~(2+)-]_i was ≤(30.73?7.25) nmol/L; after EGTA+Tg was added, -[Ca~(2+)-]_i significantly increased(-[Ca~(2+)-]_i≥-[91.55?12.24-] nmol/L); and after EGTA+Tg+CNTF was added, -[Ca~(2+)-]_i was markedly reduced compared with that in group B (-[Ca~(2+)-]_i≤-[26.09?7.16-] nmol/L, P

Capacitative Ca~(2+) entry mediate contraction in rat distal colon smooth muscle / 中国药理学通报

Aim To investigate whether capacitative Ca~(2+) entry involved in excitation-contraction coupling in rat distal colon smooth muscle.Methods Changes of isolated organ's tension were monitored with force-displacement transducer and Powerlab 4/25T recording system.Results Thapsigargin(10 nmol?L~(-1)～1 ?mol?L~(-1))produced slowly developing sustained contractions in isolated distal colon smooth muscle strips of rats.The timed contractile responses to thapsigargin(10 n mol?L~(1)-1 ?mol?L~(-1)) were significantly different.The contractile response to Ca~(2+) reintroduction following incubation of strips in a Ca~(2+)-free Krebs in the presense of thapsigargin was significantly higher than in its absence(99%?28% vs 70%?8%).Contractile responses to Ca~(2+)reintroduction following depletion of sarcoplasmic reticulum Ca~(2+) stores with thapsigargin were attenuated by La~(3+),while unaffected by verapamil.Conclusion Contractile responses to Ca~(2+)reintroduction following depletion of sarcoplasmic reticulum Ca~(2+)stores with thapsigargin,are mediated by capacitative Ca~(2+)entry.The results suggested that CCE provided activator Ca~(2+)for the contraction and participated in excitation-contraction process in rat distal colon smooth muscle.

The effect of ClC-3 antisense oligonucleotide on apoptosis induced by thapsigargin in PC12 cells / 中国药理学通报

AIM To investigate the effect of ClC-3 antisense oligonucleotide on apoptosis induced by thapsigargin in PC12 cells. METHODS Western-blot was performed to detect the protein expression of ClC-3 in PC12 cells. MTT assay was used to measure the effect of ClC-3 antisense oligonucleotide on growth inhibition induced by thapsigargin. The effect of ClC-3 antisense oligonucleotide on apoptosis was studied with the fluorescent microscopy, DNA agarose gel electrophoresis, flow cytometry analysis. RESULTS Compared with control group, transient transfection of PC12 cells with antisense oligonucleotide specific to ClC-3 caused an inhibitory effect on expression of ClC-3 protein in a time-and concentration-dependent manner,whereas the thapsigargin-induced reductions of viability of PC12 cells and apoptosis were markedly enhanced (P