Berberine induces apoptosis in SW620 human colonic carcinoma cells through generation of reactive oxygen species and activation of JNK/p38 MAPK and FasL

Berberine is the major constituent of Coptidis Rhizoma with multiple pharmacological activities, including anti-inflammation, promotion of apoptosis and anticancer potential effect. Mitogen-activated protein kinase (MAPK) and reactive oxygen species (ROS) may contribute to the causal relationship between tumorigenesis and pro-apoptotic function. Berberine is studied for the mechanism of its action in apoptotic pathway in human colonic carcinoma cell. Treatment of SW620 cells with 50 μM berberine resulted in activation of the caspase 3 and caspase 8, cleavage of poly ADP-ribose polymerase (PARP) and the release of cytochrome c; whereas, the expression of BID and anti-apoptosis factor c-IAP1, Bcl-2, and Bcl-_XL were decreased markedly. Berberine-induced, dose-dependent induction of apoptosis was accompanied by sustained phosphorylation of JNK and p38 MAPK, as well as generation of the ROS. Furthermore, the induction of apoptosis was alleviated by inhibitors specific for JNK and p38. In addition, there was an increase in the cellular levels of phospho-c-Jun, FasL and t-BID in the berberine-induced apoptosis via the activation of JNK and p38 signaling modules. NAC administration, a scavenger of ROS, reversed berberine-induced apoptosis effects via inhibition of JNK, p38 and c-jun activation, and FasL and t-BID expression. These results leads us to speculate that berberine may play an apoptotic cascade in SW620 cells by activation of the JNK/p38 pathway and induction of ROS production, providing a new mechanism for berberine-induced cell death in human colon cancer cells.     

酪酸梭菌对HT-29细胞水通道蛋白3表达的影响及JNK和p38信号通路对其调控作用

目的明确酪酸梭菌对人结肠腺癌细胞HT-29细胞水通道蛋白3(AQP3)m RNA和蛋白表达的影响以及c-Jun氨基末端激酶(JNK)和p38信号转导通路对其表达的调控作用。方法用酪酸梭菌上清液作用于HT-29细胞后,应用实时定量反转录聚合酶链反应(RT-PCR)和蛋白印迹方法检测AQP3 m RNA和蛋白表达水平。AQP3表达水平有差异后测定总JNK、p38以及磷酸化的JNK(P-JNK)和磷酸化的p38(P-p38)蛋白表达水平。后分别加用JNK抑制剂SP600125和p38抑制剂SB203580后测定AQP3蛋白表达量,观察JNK和p38对AQP3表达的调控作用。统计学处理采用单因素方差分析。结果实时定量RT-PCR和蛋白印迹法结果显示酪酸梭菌上清液不同浓度(1∶4和1∶8组)作用HT-29细胞12 h以及同一浓度1∶4作用不同时间(24、12、6 h组)的AQP3 m RNA和蛋白表达水平均较无酪酸梭菌上清液作用组明显上调(P均<0.05)。蛋白印迹法结果显示酪酸梭菌上清液组的Pp38/p38和P-JNK/JNK蛋白相对量较空白对照组表达水平明显上调(F=26.065和65.034,P<0.05)。蛋白印迹法结果显示加入p38抑制剂SB203580 10μg/ml组和20μg/ml的AQP3蛋白表达相对量为(0.7±0.4)和(0.6±0.6)、加入JNK抑制剂SP600125 10μg/ml组和20μg/ml的AQP3蛋白表达相对量为(0.7±0.4)和(0.5±0.4)均较未加入抑制剂组(1.1±0.7)AQP3蛋白表达水平明显下调(F=36.225,P<0.05)。结论酪酸梭菌上清液能够上调HT-29细胞的AQP3表达进而调节肠道的水代谢。JNK和p38信号转导通路可能参与调控AQP3的表达。     

Mycotoxin patulin activates the p38 kinase and JNK signaling pathways in human embryonic kidney cells.

Patulin (PAT), a mycotoxin mainly produced by Penicillium and Aspergillus, is frequently detected in moldy fruits and fruit products. Exposure of human embryonic kidney (HEK293) cells to PAT led to a dose- and time-dependent increase in the phosphorylation of two major mitogen-activated protein kinases (MAPKs), p38 kinase and c-Jun N-terminal kinase (JNK). The phosphorylated forms of MAPK kinase 4 (MKK4), c-Jun, and ATF-2 were also seen in PAT-treated cultures. The cell death caused by PAT was significantly reduced by the p38 kinase inhibitor, SB203580, but not by the JNK inhibitor, SP600125. Neither p38 kinase nor JNK played a role in the PAT-induced DNA damage. In PAT-treated cells, inactivation of double-stranded RNA-activated protein kinase R (PKR) by the inhibitor, adenine, markedly suppressed JNK and ERK phosphorylation. Treatment of HEK293 cells with PAT-cysteine adduct, a chemical derivative of PAT, showed no effect on MAPK signaling pathways, cell viability, or DNA integrity. These results indicate that PAT causes rapid activation of p38 kinase and JNK in HEK293 cells, but only the p38 kinase signaling pathway contributes to the PAT-induced cell death. PKR also plays a role in PAT-mediated MAPK activation.     

胡桃醌通过p38/JNK MAPK信号通路调控口腔鳞癌Tac8113细胞增殖和凋亡

目的:探讨胡桃醌通过p38/c-Jun氨基末端激酶(JNK)丝裂原活化蛋白激酶(MAPK)信号通路调控口腔鳞癌Tac8113细胞增殖和凋亡。方法:体外培养口腔鳞癌Tac8113细胞,分别给予终浓度为0,5,10,20μmol·L^-1的胡桃醌,继续培养24 h,检测细胞增殖、细胞凋亡和活性氧(ROS)水平,同时检测Tac8113细胞中p38、p-p38、JNK、p-JNK和Caspase-3蛋白表达水平。结果:与空白对照组比较,给予胡桃醌处理后,Tac8113细胞增殖率降低,Tac8113细胞凋亡率和ROS水平增加(P<0.05),且随着胡桃醌剂量增加,细胞增殖率、凋亡率和ROS变化越显著(P<0.05)。与空白对照组比较,给予胡桃醌处理后,Tac8113细胞p38和JNK蛋白表达变化不显著(P>0.05);p-p38、p-JNK和Caspase-3蛋白表达增加(P<0.05),且随着胡桃醌剂量增加,增加越显著(P<0.05)。结论:胡桃醌可能通过激活p38/JNK MAPK信号通路来诱导Tac8113细胞凋亡,从而达到抑制Tac8113细胞的目的。     

In‐vitro promoted differentiation of mesenchymal stem cells towards hepatocytes induced by salidroside

Objectives The present study aimed to investigate whether salidroside can induce differentiation of rat mesenchymal stem cells (rMSCs) towards hepatocytes in vitro and the mechanism of hepatic differentiation of rMSCs. Methods rMSCs were subject to hepatic differentiation. One, two and three weeks later, the expression of alpha fetoprotein (AFP) and albumin (ALB), cytochrome P450 (CYP450)‐dependent activity and inducibility, cellular uptake of low density lipoprotein (LDL) and urea synthesis were assessed and the hepatic differentiation of rMSCs was evaluated. In order to unravel the mechanism of hepatic differentiation of rMSCs in vitro, inhibitors of extracellular regulated kinase1/2 (ERK1/2), phosphatidylinositol 3‐kinase (PI3K) and p38 were applied. When the process of hepatic differentiation was completed, special proteins of hepatic differentiation were detected and blocking of inhibitors was evaluated. Key findings Salidroside significantly induce differentiation of rMSCs towards hepatocytes. Differentiated rMSCs have typical functional hepatic characteristics. The results also showed that the ERK1/2 and PI3K signalling pathways play important roles in the regulatory effects of salidroside on hepatic differentiation of rMSCs and are involved in cell fate determinations, while the p38 signalling pathway does not. Conclusions Salidroside can induce differentiation of rMSCs towards hepatocytes in vivo, and the ERK1/2 or PI3K signalling pathway underlie the process of hepatic differentiation.     

PI3K/AKT/JNK/p38 signalling pathway‐mediated neural apoptosis in the prefrontal cortex of mice is involved in the antidepressant‐like effect of pioglitazone

Numerous studies have reported that inflammation is involved in the pathophysiology of depression. Pioglitazone, a PPAR‐γ agonist, has potential anti‐inflammatory and antidepressive effects. However, the underlying molecular mechanisms of the antidepressant‐like effect of pioglitazone on an inflammation‐related mouse model of depression remain to be fully elucidated. Herein, we aimed to explore the effects of pioglitazone on depressive‐like behaviours of mice exposed to lipopolysaccharides (LPS), and elucidate the underlying mechanisms. We assessed behaviour changes of mice pretreated with pioglitazone exposed to LPS. Additionally, neural apoptosis, and the expression of apoptosis‐related (cleaved caspase‐3, Bax, Bcl‐2, cyt c) and signalling proteins (AKT, JNK, p38) were assessed in the prefrontal cortex (PFC) of these mice. Furthermore, we assessed the influence of anisomycin, a JNK/p38 agonist, and LY294002, a PI3K/AKT inhibitor, on the antidepressant‐like effect of pioglitazone in mice. We show that pioglitazone pretreatment (20 mg/kg, intragastrically) attenuated LPS‐induced (10 ng/μL per site) depressive‐like behaviours. GW9662, a PPAR‐γ antagonist, significantly blocked the antidepressant‐like effect of pioglitazone. Furthermore, at the molecular level, pioglitazone significantly reversed, via PPAR‐γ‐dependent increase in neural apoptosis in the PFC of mice, accompanied by upregulation of the PI3K/AKT pathway and down‐regulation of the JNK/p38 pathway. Moreover, both anisomycin and LY294002 abrogated the antidepressant‐like effect of pioglitazone.; In conclusion, our results showed that PI3K/AKT/JNK/p38 signalling pathway‐mediated neural apoptosis in the PFC of mice may be involved in the antidepressant‐like effect of pioglitazone. This provides novel insights into and therapeutic targets for inflammation‐related depression.     

Mig-2 attenuates cisplatin-induced apoptosis of human glioma cells in vitro through AKT/JNK and AKT/p38 signaling pathways

Aim:

Mig-2 (also known as Kindlin-2 and FERMT2) is an important regulator of integrin activation and cell-extracellular matrix adhesion, and involved in carcinogenesis and tumor progression. The aim of this study was to investigate the role of mig-2 in cisplatin-induced apoptosis of human glioma cells in vitro.

Methods:

The expression of mig-2 was modulated in human glioma H4, HS 683 and U-87 MG cells by transfection with a plasmid carrying mig-2 or mig-2 siRNA. Cisplatin-induced apoptosis was detected using Annexin V/PI staining and flow cytometry, as well as MTS analyses. The expression of apoptosis-related or signaling proteins was examined using Western blotting analysis. H4 cells were transfected with plasmids carrying mig-2 mutants to determine the functional domain of mig-2.

Results:

In the 3 glioma cell lines tested, overexpression of mig-2 significantly attenuated cisplatin-induced apoptosis, whereas knock-down of mig-2 potentiated the apoptosis. The mechanisms of action of mig-2 were further addressed in H4 cells: overexpression of mig-2 markedly reduced cleaved caspase-9, caspase-8, caspase-3 and PARP, as well as p-JNK and p-p38, and increased p-AKT in cisplatin-treated H4 cells, whereas mig-2 siRNA reversely changed these apoptosis-related and signaling proteins. Furthermore, pretreatment with JNK inhibitor SP600125 and p38 inhibitor SB203580, or with AKT inhibitor {"type":"entrez-nucleotide","attrs":{"text":"LY294002","term_id":"1257998346","term_text":"LY294002"}}LY294002 abolished the effects of mig-2 on cisplaxtin-induced apoptosis. In H4 cells, GFP-mig-2 F3 plasmid that contained only the F3 subdomain showed the same efficiency in attenuating cisplatin-induced apoptosis, as the mig-2 wild-type vector did, whereas GFP-mig-2 (1-541) plasmid that lacked the F3 subdomain was inactive.

Conclusion:

Mig-2 significantly attenuates the antitumor action of cisplatin against human glioma cells in vitro through AKT/JNK and AKT/p38 signaling pathways. The F3 subdomain of mig-2 is necessary and sufficient for this effect.     

Sodium propionate exerts anticancer effect in mice bearing breast cancer cell xenograft by regulating JAK2/STAT3/ROS/p38 MAPK signaling

Propionate is a short-chain fatty acid (SCFA) mainly produced from carbohydrates by gut microbiota. Sodium propionate (SP) has shown to suppress the invasion in G protein-coupled receptor 41 (GPR41) and GPR43-overexpressing breast cancer cells. In this study we investigated the effects of SP on the proliferation, apoptosis, autophagy, and antioxidant production of breast cancer cells. We showed that SP (5−20 mM) dose-dependently inhibited proliferation and induced apoptosis in breast cancer cell lines JIMT-1 (ER-negative and HER2-expressing) and MCF7 (ER-positive type), and this effect was not affected by PTX, thus not mediated by the GPR41 or GPR43 SCFA receptors. Meanwhile, we demonstrated that SP treatment increased autophagic and antioxidant activity in JIMT-1 and MCF7 breast cancer cells, which might be a compensatory mechanism to overcome SP-induced apoptosis, but were not sufficient to overcome SP-mediated suppression of proliferation and induction of apoptosis. We revealed that the anticancer effect of SP was mediated by inhibiting JAK2/STAT3 signaling which led to cell-cycle arrest at G₀/G₁ phase, and increasing levels of ROS and phosphorylation of p38 MAPK which induced apoptosis. In nude mice bearing JIMT-1 and MCF7 cells xenograft, administration of SP (20 mg/mL in drinking water) significantly suppressed tumor growth by regulating STAT3 and p38 in tumor tissues. These results suggest that SP suppresses proliferation and induces apoptosis in breast cancer cells by inhibiting STAT3, increasing the ROS level and activating p38. Therefore, SP is a candidate therapeutic agent for breast cancer.     

Silymarin augments human cervical cancer HeLa cell apoptosis via P38/JNK MAPK pathways in serum-free medium

Silymarin was proved to have a protective effect of UV-induced A375-S2 cell apoptosis in our previous research. In this study, its pro-apoptotic and anti-apoptotic activities on human cervical cancer (HeLa) cells in vitro were investigated. Silymarin induced HeLa cell death through both apoptotic and necrotic pathways. At low doses (below 80 μmol l^? 1), it induced cell apoptosis, but caused necrosis at high dose (160 μmol l^? 1). Silymarin induced typical chromatin condensation and nuclear fragmentation as a hallmark of apoptosis. In this case, mitochondrial Bcl-2 family, Bcl-2 and Bax, were not involved in apoptotic effects; however, silymarin-induced cell death was regulated by the activation of p38 and JNK MAPKs. We also found that pan-caspase inhibitor and caspase-3 inhibitor could not antagonise silymarin-induced apoptosis. Therefore, silymarin induced and augmented HeLa cell apoptosis through p38/JNK MAPKs in the serum-free medium.     

植物雌激素金雀异黄酮通过p38MAPK通路促进骨髓间充质干细胞向成骨细胞分化

目的研究丝裂原激活的蛋白激酶(m itogen-activatedprote in k inases,MAPKs)的亚型p38 MAPK在植物雌激素金雀异黄酮(Gen iste in)促进小鼠骨髓间充质干细胞(bone m ar-row-derived m esenchym al stem cells,BMSCs)向成骨细胞分化过程中的作用。方法BMSCs用无酚红-αMEM(含经活性碳吸附的10%FBS、β-磷酸甘油、维生素C)培养,先用Gen iste in处理细胞,观察BMSCs向成骨细胞分化情况,然后用SB203580(p38 MAPK通路阻断剂)以及PD98059(p44/42MAPK通路阻断剂)阻断相应的通路后,再用Gen iste in处理细胞,观察BMSCs向成骨细胞分化情况,并同时观察上述处理后MAPK通路的变化。测定碱性磷酸酶(ALP)活性和钙(Ca)沉积量反映BMSCs向成骨细胞分化状况,用W esternb lot来检测MAPK通路是否激活。结果Gen iste in(0.01,0.1,1μmol.L-1)剂量依赖性增加小鼠BMSCs细胞内ALP活性和细胞外Ca沉积量,并同时引起p38MAPK通路的激活和p44/42MAPK通路的抑制。SB203580预处理能减弱Gen iste in刺激引起的p38MAPK通路的激活并同时阻止Gen iste in诱导的BMSCs向成骨细胞分化。结论Gen iste in在0.01~1μmol.L-1剂量范围内可通过p38MAPK通路促进小鼠BMSCs向成骨细胞分化。     

ROS activates JNK-mediated autophagy to counteract apoptosis in mouse mesenchymal stem cells in vitro

Aim:

Transplantation of mesenchymal stem cells (MSCs) for the treatment of diabetic erectile dysfunction (ED) is hampered by apoptosis of the transplanted cells. In diabetic ED, there is increased oxidative stress and decreased NO in the corpora cavernosa, and reactive oxygen species (ROS) induce apoptosis of the transplanted cells. In this study we examined whether and how autophagy was involved in ROS-induced apoptosis of MSCs.

Methods:

Mouse C3H10 MSCs were treated with H₂O₂ to simulate the high oxidative condition in diabetic ED. Cell viability was measured using MTT assay. Apoptosis was analyzed by flow cytometry. Apoptosis- and autophagy-related proteins were detected with Western blot assays. Intracellular autophagosome accumulation was studied using transmission electron microscopy.

Results:

Treatment of MSCs with H₂O₂ (50–400 μmol/L) inhibited the cell viability in concentration- and time-dependent manners. Furthermore, H₂O₂ (300 μmol/L) induced apoptosis, as well as activated autophagy in MSCs. Pretreatment with lysosome inhibitor chloroquine (10 μmol/L) or PI3K inhibitor 3-methyladenine (5 mmol/L) significantly enhanced H₂O₂-induced cell death. Pretreatment with JNK inhibitor SP600125 (10 μmol/L) abrogated H₂O₂-induced accumulation of LC3-II, and attenuated H₂O₂-induced reduction of Bcl-2 levels in MSCs.

Conclusion:

ROS induce autophagy to counteract apoptosis in MSCs by activation of JNK. Thus, augmentation of autophagy may reduce apoptosis, prolonging MSC survival and improving MSC-based therapeutic efficacy for diabetic ED.     

Antitumour effect of odoroside A and its derivative on human leukaemia cells through the ROS/JNK pathway

Oleandrigenin-3-O-β-D-diginoside (a derivative of odoroside A), isolated and purified by our group, has seldom been explored for its pharmacological activity. This study aimed at clarifying the mechanisms towards the leukaemia-suppressive role of odoroside A (compound #1 ) and its derivative, oleandrigenin-3-O-β-D-diginoside (compound #2 ) isolated from Nerium oleander. Viability and nuclear morphology change were assessed by CCK-8 assay and fluorescence microscope, respectively. Then, the cell apoptosis and autophagy induced by the compounds were detected by flow cytometry and Western blot. Xenograft model of nude mice was also applied to measure the leukaemia-suppressive effects of compound #2 in vivo. The result displayed that compound #1 and compound #2 inhibited the proliferation of HL60 and K562 cells and stronger effects were found in HL60 than K562 cells. Both of the compounds induced a dose-dependent apoptosis and autophagy in HL60 cells, where compound #2 was more potent than compound #1 . Compound #2 also demonstrated a time-dependent apoptosis and autophagy in HL60 cells. Furthermore, ROS generation and JNK phosphorylation occurred in a dose-dependent manner in the cells treated with compound #2 . Mitochondria also played critical role, proved by the decrease of Bcl-2, the release of cyto c to cytosol and the activation of caspase-3 and caspase-9. Moreover, the antitumour effects of compound #2 were validated in the nude mouse xenograft model in vivo. Odoroside A and its derivative inhibited the growth of leukaemia by inducing apoptosis and autophagy through the activation of ROS/JNK pathway. These results suggest that the compounds can serve as potential antitumour agents against leukaemia, especially acute myeloid leukaemia (AML).     

Piperlongumine induces apoptotic and autophagic death of the primary myeloid leukemia cells from patients via activation of ROS-p38/JNK pathways

Aim:

To investigate the effects of piperlongumine (PL), an anticancer alkaloid from long pepper plants, on the primary myeloid leukemia cells from patients and the mechanisms of action.

Methods:

Human BM samples were obtained from 9 patients with acute or chronic myeloid leukemias and 2 patients with myelodysplastic syndrome (MDS). Bone marrow mononuclear cells (BMMNCs) were isolated and cultured. Cell viability was determined using MTT assay, and apoptosis was examined with PI staining or flow cytometry. ROS levels in the cells were determined using DCFH-DA staining and flow cytometry. Expression of apoptotic and autophagic signaling proteins was analyzed using Western blotting.

Results:

PL inhibited the viability of BMMNCs from the patients with myeloid leukemias (with IC₅₀ less than 20 μmol/L), but not that of BMMNCs from a patient with MDS. Furthermore, PL (10 and 20 μmol/L) induced apoptosis of BMMNCs from the patients with myeloid leukemias in a dose-dependent manner. PL markedly increased ROS levels in BMMNCs from the patients with myeloid leukemias, whereas pretreatment with the antioxidant N-acetyl-L-cysteine abolished PL-induced ROS accumulation and effectively reduced PL-induced cytotoxicity. Moreover, PL markedly increased the expression of the apoptotic proteins (Bax, Bcl-2 and caspase-3) and autophagic proteins (Beclin-1 and LC3B), and phosphorylation of p38 and JNK in BMMNCs from the patients with myeloid leukemias, whereas pretreatment with the specific p38 inhibitor SB203580 or the specific JNK inhibitor SP600125 partially reversed PL-induced ROS production, apoptotic/autophagic signaling activation and cytotoxicity.

Conclusion:

Piperlongumine induces apoptotic and autophagic death of the primary myeloid leukemia cells from patients via activation of ROS-p38/JNK pathways.     

阿霉素诱导胰腺癌BxPC-3细胞凋亡过程中p38MAPK的表达

目的研究阿霉素诱导胰腺癌细胞凋亡过程中p38MAPK表达的变化,探讨p38MAPK在其中的作用。方法用膜联蛋白V-PI(annexinV-PI)染色及流式细胞技术分析阿霉素及应用p38MAPK抑制剂SB203580对胰腺癌细胞凋亡的影响,同时利用免疫细胞化学法观察经阿霉素及SB203580处理人胰腺癌BxPC-3细胞后,p38MAPK的表达水平。结果SB203580(20μmol/L)干预组胰腺癌BxPC-3细胞凋亡率为(20.1±1.4)%,阿霉素作用24 h后诱导胰腺癌BxPC-3细胞凋亡,凋亡率为(31.1±2.7)%,加用SB203580抑制p38MAPK通路后可增强阿霉素诱导的凋亡作用,凋亡率达(40.4±2.6)%。采用单因素方差分析F=136.79,组间比较组与组之间差异有统计学意义。以20μmol/L阿霉素作用BxPC-3胰腺癌细胞24 h后可见p38MAPK在细胞染色后呈现深褐色颗粒散在分布于部分或整个细胞核及细胞质内,联合应用SB203580后可见p38MAPK表达颗粒密度减低,数量减少。结论阿霉素可以活化p38MAPK通路,p38MAPK可能起到保护胰腺癌BxPC-3细胞逃避阿霉素诱导的凋亡,阻断该通路可增强阿霉素诱导胰腺癌细胞凋亡的作用。     

Cadmium induces apoptotic cell death through p38 MAPK in brain microvessel endothelial cells

Cadmium (Cd), an ubiquitous heavy metal, is known to be accumulated outside of the blood-brain barrier. In this study, we investigated whether Cd has cytotoxicity in mouse brain microvascular endothelial cells (bEnd.3). Results from the cell viability assay showed that Cd caused a remarkable decrease in cell viability in a dose-dependent manner. The cell death induced by Cd appeared to involve apoptosis, based on our results from annexin V staining, electron microscopy and TUNEL staining. And the cell death induced by Cd was inhibited by caspase inhibitor ZVAD-fmk. To further investigate the mechanism of the Cd-induced cell death, we examined the effects of selective inhibitors for mitogen activated protein kinase (MAPK) pathways on the cell death. The Cd-induced cell death was significantly inhibited by p38 MAPK inhibitor SB202190, but not by either, c-Jun N-terminal kinase (JNK) inhibitor SP600125 or extracellular signal-regulated kinase (ERK) inhibitor U0126. Phosphorylations of p38 MAPK, JNK and ERK were stimulated by treatment with CdCl(2). In summary, our results suggest that Cd can induce apoptotic cell death, at least in part, through the p38 MAPK pathway in brain microvascular endothelial cells.     

Growth inhibition of mesenchymal stem cells by aspirin: involvement of the WNT/beta-catenin signal pathway

1. Mesenchymal stem cell (MSC) therapy is drawing increasing attention in cardiology. However, the effect of aspirin, an assistant medication used extensively in the treatment of cardiovascular diseases, on MSC is not clear. 2. In the present study, we investigated the effect of aspirin on the growth of MSC in vitro and the underlying mechanism of its action. 3. The 3-(4,5-dimethyl-2 thiazoyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay revealed that 1, 5 and 10 mmol/L aspirin inhibited the growth of MSC by 18, 37 and 62%, respectively. DNA synthesis of MSC was inhibited by 25, 57 and 90% following treatment with 1, 5 and 10 mmol/L aspirin, respectively, as determined by the tritiated thymidine incorporation assay. No cytotoxicity was observed based on Trypan blue dye exclusion and cell morphological observations. Western blot analysis demonstrated that the protein level of phosphorylated beta-catenin increased, whereas that of cyclin D1 decreased, after treatment of MSC with aspirin. Cell cycle analysis showed that aspirin failed to significantly alter the proportion of cells in different stages of the cell cycle. 4. These observations indicate that aspirin inhibits MSC proliferation and that the downregulation of the wnt/beta-catenin signal pathway may be involved in the growth inhibition of MSC by aspirin.     

Curcumin inhibits oxLDL-induced CD36 expression and foam cell formation through the inhibition of p38 MAPK phosphorylation

The uptake of oxidized low density lipoprotein (oxLDL) via scavenger receptors transforms macrophages into foam cells, which are a hallmark of atherosclerosis. OxLDL markedly increases the expression of the CD36 scavenger receptor. Here, we investigated whether curcumin modulate CD36 expression in oxLDL-treated RAW 264.7 murine macrophages. Our results showed that curcumin dramatically inhibits CD36 expression and foam cell formation. Furthermore, oxLDL-induced expression and activity of peroxisome proliferator-activated receptor-gamma (PPAR-γ), which is involved in CD36 expression, is also blocked in curcumin-treated cells. OxLDL activates the mitogen-activated protein kinase (MAPK) signaling transduction pathway, and p38 MAPK is associated with oxLDL-induced CD36 and PPAR-γ expression. Overexpression of dominant negative p38 MAPK blocks oxLDL-induced CD36 and PPAR-γ expression. Furthermore, curcumin markedly inhibits p38 MAPK phosphorylation. Taken together, our results suggest that curcumin modulates oxLDL-induced CD36 expression and foam cell formation via the inhibition of p38 MAPK phosphorylation in RAW 264.7 murine macrophages.     

Inhibition of pro-inflammatory cytokine production by the dual p38/JNK2 inhibitor BIRB796 correlates with the inhibition of p38 signaling

The characterization of the potent p38 inhibitor BIRB796 as a dual inhibitor of p38/Jun N-terminal kinases (JNK) mitogen-activated protein kinases (EC 2.7.11.24) has complicated the interpretation of its reported anti-inflammatory activity. To better understand the contribution of JNK2 inhibition to the anti-inflammatory activities of BIRB796, we explored the relationship between the effects of BIRB796 and analogues on cytokine production and on cellular p38 and JNK signaling. We determined the binding affinity for BIRB796 and structural analogues to p38α and JNK2 and characterized compound 2 as a p38 inhibitor that binds to p38α with an affinity equivalent to BIRB796 but does not bind to any of the JNK isoforms. High-content imaging enabled us to show that the inhibition of p38 signaling by BIRB796 and analogues correlates with the ability of these compounds to inhibit the lipopolysaccharide (LPS)-induced TNF-α production in THP-1 monocytes. This finding was extended to cytokine release by disease-relevant human primary cells: to the production of TNF-α by peripheral blood mononuclear cells, and of IL-8 by neutrophils. Furthermore, BIRB796 and compound 2 inhibited the production of TNF-α in THP-1 monocytes and the IL-12/IL-18-induced production of interferon-γ in human T-cells with similar potencies. In contrast, cellular JNK signaling in response to cytokines or stress stimuli was only weakly inhibited by BIRB796 and analogues and not affected by compound 2. In summary, our data suggest that p38 inhibition alone is sufficient to completely suppress cytokine production and that the added inhibition of JNK2 does not significantly contribute to the effects of BIRB796 on cytokine production.