α-Tocopheryl succinate induces apoptosis in erbB2-expressing breast cancer cell via NF-κB pathway

Aim:

To study the molecular mechanisms underlying α-tocopheryl succinate (α-TOS)-induced apoptosis in erbB2-positive breast cancer cells and to determine whether α-TOS and the human recombinant TNF-related apoptosis-inducing ligand (hrTRAIL) act synergically to induce cell death of erbB2-expressing breast cancer cells.

Methods:

The annexin V binding method was used to measure apoptosis induced by α-TOS and/or hrTRAIL. RT-PCR and Western blotting were performed to detect gene and protein expression. A colorimetric assay was performed to detect caspase activity. The TransAM^TM NF-κB p65 kit was used to assess NF-κB activation.

Results:

α-TOS (100 μmol/L) significantly inhibited NF-κB nuclear translocation in erbB2-expressing breast cancer cells; this inhibition is expected to result in the inactivation of NF-κB. α-TOS (50 and 100 μmol/L) inhibited the expression of Flice-like inhibitory protein (FLIP) and cellular inhibitor of apoptosis protein 1 (c-IAP1) in erbB2-positive cells. α-TOS (100 μmol/L) inhibited Akt activation and augmented the activity of caspase 3 and caspase 8 in breast cancer cells expressing erbB2. α-TOS (50 μmol/L) and hrTRAIL (30 mg/mL) acted synergically to induce apoptosis in breast cancer cells. α-TOS also decreased the hrTRAIL-induced transient activation of NF-κB .

Conclusion:

Our results suggest that α-TOS mediates the apoptosis of erbB2-positive breast cancer cells and acts synergically with hrTRAIL via the NF-κB pathway.     

Thiocolchicoside suppresses osteoclastogenesis induced by RANKL and cancer cells through inhibition of inflammatory pathways: a new use for an old drug

BACKGROUND AND PURPOSE

Most patients with cancer die not because of the tumour in the primary site, but because it has spread to other sites. Common tumours, such as breast, multiple myeloma, and prostate tumours, frequently metastasize to the bone. To search for an inhibitor of cancer-induced bone loss, we investigated the effect of thiocolchicoside, a semi-synthetic colchicoside derived from the plant Gloriosa superba and clinically used as a muscle relaxant, on osteoclastogenesis induced by receptor activator of NF-κB ligand (RANKL) and tumour cells.

EXPERIMENTAL APPROACH

We used RAW 264.7 (murine macrophage) cells, a well-established system for osteoclastogenesis, and evaluated the effect of thiocolchicoside on RANKL-induced NF-κB signalling and osteoclastogenesis as well as on osteoclastogenesis induced by tumour cells.

KEY RESULTS

Thiocolchicoside suppressed osteoclastogenesis induced by RANKL, and by breast cancer and multiple myeloma cells. Inhibition of the NF-κB pathway was responsible for this effect since the colchicoside inhibited RANKL-induced NF-κB activation, activation of IκB kinase (IKK) and suppressed inhibitor of NF-κBα (IκBα) phosphorylation and degradation, an inhibitor of NF-κB. Furthermore, an inhibitor of the IκBα kinase γ or NF-κB essential modulator, the regulatory component of the IKK complex, demonstrated that the NF-κB signalling pathway is mandatory for osteoclastogenesis induced by RANKL.

CONCLUSIONS AND IMPLICATIONS

Together, these data suggest that thiocolchicoside significantly suppressed osteoclastogenesis induced by RANKL and tumour cells via the NF-κB signalling pathway. Thus, thiocolchicoside, a drug that has been used for almost half a century to treat muscle pain, may also be considered as a new treatment for bone loss.

LINKED ARTICLE

This article is commented on by Micheau et al., pp. 2124–2126 of this issue. To view this commentary visit http://dx.doi.org/10.1111/j.1476-5381.2011.01792.x     

Plumbagin inhibits cell growth and potentiates apoptosis in human gastric cancer cells in vitro through the NF-κB signaling pathway

Aim:

To investigate the effects and underlying mechanisms of plumbagin, a naphthoquinone derived from medicinal plant Plumbago zeylanica, on human gastric cancer (GC) cells.

Methods:

Human gastric cancer cell lines SGC-7901, MKN-28, and AGS were used. The cell viability was examined using CCK-8 viability assay. Cell proliferation rate was determined using both clonogenic assay and EdU incorporation assay. Apoptosis was detected via Annexin V/propidium iodide double-labeled flow cytometry. Western blotting was used to assess the expression of both NF-κB-regulated gene products and TNF-α-induced activation of p65, IκBα, and IKK. The intracellular location of NF-κB p65 was detected using confocal microscopy.

Results:

Plumbagin (2.5–40 μmol/L) concentration-dependently reduced the viability of the GC cells. The IC₅₀ value of plumbagin in SGC-7901, MKN-28, and AGS cells was 19.12, 13.64, and 10.12 μmol/L, respectively. The compound (5–20 μmol/L) concentration-dependently induced apoptosis of SGC-7901 cells, and potentiated the sensitivity of SGC-7901 cells to chemotherapeutic agents TNF-αand cisplatin. The compound (10 μmol/L) downregulated the expression of NF-κB-regulated gene products, including IAP1, XIAP, Bcl-2, Bcl-xL, tumor factor (TF), and VEGF. In addition to inhibition of NF-κB p65 nuclear translocation, the compound also suppressed TNF-α-induced phosphorylation of p65 and IKK, and the degradation of IκBα.

Conclusion:

Plumbagin inhibits cell growth and potentiates apoptosis in human GC cells through the NF-κB pathway.     

Gemcitabine combined with gum mastic causes potent growth inhibition and apoptosis of pancreatic cancer cells

Aim:

To investigate the antiproliferative and apoptotic effects of gemcitabine combined with gum mastic and the underlying mechanisms in human pancreatic cancer cell lines.

Methods:

Cell proliferation and apoptosis were examined using the methyl thiazolyl tetrazolium (MTT) assay and propidium iodine staining, respectively. The expression of Bcl-2, Bax, NF-κB p65 subunit, and IκBα protein was measured using Western blotting.

Results:

Gemcitabine 0.01−100 μg/mL inhibited cell proliferation and induced apoptosis in both pancreatic cancer BxPC-3 and COLO 357 cells. Gum mastic 40 μg/mL significantly potentiated the antiproliferative and apoptotic effects of gemcitabine 10 μg/mL after 72-h treatment. When cells were treated with gemcitabine in combination with gum mastic, the IκBα level was increased, whereas NF-κB activation was blocked; the expression of Bax protein was substantially increased, but Bcl-2 protein was down-regulated.

Conclusion:

Gemcitabine combined with gum mastic causes potent apoptosis in pancreatic cancer cells. The combination may be an effective therapeutic strategy for pancreatic cancer.     

Glycyrrhetinic acid inhibits ICAM-1 expression via blocking JNK and NF-KB pathways in TNF-α-activated endothelial cells

Aim:

To investigate the effects of glycyrrhetinic acid (GA), an active component extracted from the root of Glycyrrhizae glabra, on the expression of intercellular adhesion molecule-1 (ICAM-1) in tumor necrosis factor-α (TNF-α)-activated human umbilical vein endothelial cells (HUVEC).

Methods:

ICAM-1 mRNA and protein levels were detected using RT-PCR and cell enzyme-linked immunosorbent assays. The adherence of human monocytic THP-1 cells labeled with [³H]thymidine to HUVEC was determined by counting radioactivity with a scintillation counter. The activation of mitogen-activated protein kinases as well as the degradation of IκB and nuclear factor-κB (NF-κB) or phospho-c-Jun in the nucleus were detected by western blots. NF-κB binding activity was detected using electrophoretic mobility shift assay.

Results:

GA (50 and 100 μmol/L) significantly inhibits TNF-α-induced ICAM-1 mRNA and protein expressions, as well as THP-1 cell adhesiveness in HUVEC. GA selectively inhibited TNF-α-activated signal pathway of c-Jun N-terminal kinase (JNK), without affecting extracellular signal-regulated kinase 1/2 and p38. Furthermore, GA apparently inhibited IκB/NF-κB signaling system by preventing IκB degradation, NF-κB translocation, and NF-κB/DNA binding activity. Finally, pretreatment with GA or the inhibitors of NF-κB, JNK, and p38 reduced the ICAM-1 protein expression induced by TNF-α.

Conclusion:

GA inhibits TNF-α-stimulated ICAM-1 expression, leading to a decrease in adherent monocytes to HUVEC. This inhibition is attributed to GA interruption of both JNK/c-Jun and IκB/NF-κB signaling pathways, which decrease activator protein-1 (AP-1) and NF-κB mediated ICAM-1 expressions. The results suggest that GA may provide a beneficial effect in treating vascular diseases associated with inflammation, such as atherosclerosis.     

Puerarin inhibits angiotensin II-induced cardiac hypertrophy via the redox-sensitive ERK1/2, p38 and NF-κB pathways

Aim： To investigate the effects of puerarin （Pue）, an isoflavone derived from Kudzu roots, on angiotensin II （Ang II）-induced hypertrophy of cardiomyocytes in vivo and in vitro.
Methods： C57BL/6J mice were infused with Ang II and treated with Pue （100 mg·kg-1·d-1, po） for 15 d. After the treatment, systolic blood pressure （SBP） and left ventricular wall thickness were assessed. The ratios of heart weight to body weight （HW/BW） and left ventricular weight to body weight （LVW/BW） were determined, and heart morphometry was assessed. Expression of fetal-type genes （ANP, BNP and β-MHC） in left ventricles was measured using semi-quantitative RT-PCR. Mouse primary cardiomyocytes were treated with Pue （50, 100, 200 μmol/L）, then exposed to Ang II （1 μmol/L）. ROS level was examined with flow cytometry, the binding activity of NF-κB was determined using EMSA. Western blot was used to measure the levels of ERK1/2, p38 and NF-κB pathway proteins. [3H]leucine incorporation was used to measure the rate of protein synthesis.
Results： Oral administration of Pue significantly suppressed Ang II-induced increases in the myocyte surface area, HW/BW, LVW/BW, SBP and left ventricular wall thickness. Furthermore, Pue significantly suppressed Ang II-induced increases in ANP, BNP and β-MHC expression in the left ventricles in vivo. Treatment of cardiomyocytes with Pue （50–500 μmol/L） did not affect the viability of cardiomyocytes in vitro. Pretreatment of cardiomyocytes with Pue dose-dependently inhibited Ang II-induced increases in ROS production, NF-κB binding activity, protein synthesis and cell breadth. Furthermore, pretreatment with Pue significantly suppressed Ang II-induced activation of ERK1/2, p38 and the NF-κB pathway proteins and the expression of ANP and β-MHC in cardiomyocytes. The positive drug valsartan exerted similar effects on Ang II-induced cardiac hypertrophy in vivo and in vitro.
Conclusion： Pue attenuates Ang II-induced cardiac hypertrophy by inhibiting activation of the redox-sensitive ERK1/2, p38 and the NF-κB pathways.     

Kaempferol acts through mitogen-activated protein kinases and protein kinase B/AKT to elicit protection in a model of neuroinflammation in BV2 microglial cells

BACKGROUND AND PURPOSE

Kaempferol, a dietary flavonoid and phyto-oestrogen, is known to have anti-inflammatory properties. Microglial activation has been implicated in various neurodegenerative diseases. Anti-inflammatory effects of kaempferol and the underlying mechanisms were investigated by using LPS-stimulated microglial BV2 cells.

EXPERIMENTAL APPROACH

Cell viability was measured using MTT and neutral red assays. elisa, Western blot, immunocytochemistry and electrophoretic mobility-shift assay were used to analyse NO, PGE₂, TNF-α and IL-1β production, inducible NOS (iNOS), COX-2 expression and the involvement of signalling pathways such as toll-like receptor-4 (TLR4), MAPK cascades, PKB (AKT) and NF-κB. Accumulation of reaction oxygen species (ROS) was measured by nitroblue tetrazolium and 2′7′-dichlorofluorescein diacetate assay. Matrix metalloproteinase activity was investigated by zymography and immunoblot assay. Phagocytotic activity was assessed by use of latex beads.

KEY RESULTS

Kaempferol significantly attenuated LPS-induced NO, PGE₂, TNF-α, IL-1β and ROS production and phagocytosis in a concentration-dependent manner. Kaempferol suppressed the expression of iNOS, COX-2, MMP-3 and blocked the TLR4 activation. Moreover, kaempferol inhibited LPS-induced NF-κB activation and p38 MAPK, JNK and AKT phosphorylation.

CONCLUSION AND IMPLICATIONS

Kaempferol was able to reduce LPS-induced inflammatory mediators through the down-regulation of TLR4, NF-κB, p38 MAPK, JNK and AKT suggesting that kaempferol has therapeutic potential for the treatment of neuroinflammatory diseases.     

Okadaic acid induces matrix metalloproteinase-9 expression in fibroblasts: crosstalk between protein phosphatase inhibition and β-adrenoceptor signalling

BACKGROUND AND PURPOSE

Interactions between protein phosphatase inhibition and matrix metalloproteinase (MMP)-9 expression have implications for tissue remodelling after injury. Stimulation of β-adrenoceptors could affect such interactions as isoprenaline increases protein phosphatase 2A (PP2A) activity and MMP-9 abundance. We investigated the effect of okadaic acid (OA) on MMP-9 expression to assess interactions between phosphatase inhibition and β-adrenoceptor signalling in fibroblasts.

EXPERIMENTAL APPROACH

Fibroblasts were exposed to OA alone and in combination with isoprenaline. Effects on MMP-9 expression and intracellular signalling were studied using promoter assays, Western blot analysis and siRNA methodologies.

KEY RESULTS

Okadaic acid increased MMP-9 abundance in human cardiac ventricular fibroblasts, NIH3T3 fibroblasts and hepatic stellate cells. This effect was unaffected by PP2A knockdown in NIH3T3 cells. OA increased phosphorylation of NF-κB, but not NF-κB promoter activity, IκBα degradation, or nuclear translocation of p65-NF-κB. Exposure to SB202190 (p38 MAPK), U0126 (ERK1/2) and NF-κB III inhibitor revealed that OA induced MMP-9 activity through p38 MAPK. Isoprenaline inhibited OA-mediated MMP-9 expression in NIH3T3, in a β-arrestin 2- and PP2A-dependent manner. Mutation of the activator protein-1 (AP-1) and NF-κB binding sites demonstrated that OA-induced MMP-9 activity was mediated through the AP-1 but not NF-κB sites. The latter mediated the inhibitory effect of isoprenaline on OA-induced MMP-9 promoter activity.

CONCLUSION AND IMPLICATIONS

Okadaic acid induced MMP-9 activity through p38 MAPK and was inhibited by isoprenaline via a pathway involving β-arrestin 2, PP2A and an NF-κB binding motif. These findings elucidate how phosphoprotein phosphatases and adrenoceptors may modulate tissue remodelling by affecting fibroblast function.     

The antioxidant activity of chondroitin-4-sulphate, in carbon tetrachloride-induced acute hepatitis in mice, involves NF-kappaB and caspase activation

Background and purpose:

Reactive oxygen species (ROC) are the main causes of carbon tetrachloride (CCl₄)-induced acute liver injury. Chondroitin-4-sulphate (C4S) is known to inhibit lipid peroxidation through antioxidant mechanisms. Activation of nuclear factor (NF)-κB and caspases may strongly intensify inflammation and cell damage, in addition to that directly exerted by ROS. We investigated whether treatment with C4S, besides exerting antioxidant activity, was able to modulate NF-κB and apoptosis activation in CCl₄-induced liver injury in mice.

Experimental approach:

Acute hepatitis was induced in mice by an i.p. injection of CCl₄. Varying doses of C4S were administered i.p. 1 h before, 6 and 12 h after CCl₄ injection. 24 h after CCl₄ injection, the mice were killed for biochemical and histological analysis.

Key results:

CCl₄ injection produced: marked elevation of alanine aminotransferase and aspartate aminotransferase; hepatic membrane lipid peroxidation, assayed by 8-isoprostane levels; and depletion of reduced glutathione and superoxide dismutase. CCl₄ also decreased NF-κB translocation and IkBα, and increased gene expression of mRNA and protein of metalloproteases (MMP)-2 and -9, and of pro- and cleaved forms of caspases-3 and -7. There was also increased liver polymorphonuclear infiltration, evaluated by elastase assay, and hepatic cell disruption.C4S treatment inhibited lipid peroxidation; blocked NF-κB activation and IkBα protein loss; decreased mRNA and proteins for MMPs and caspases; restored endogenous antioxidants; limited hepatic polymorphonuclear accumulation and tissue damage.

Conclusions and implications:

As antioxidants may inhibit NF-κB and caspase activation, we hypothesize that treatment with C4S was able to inhibit NF-κB and apoptosis activation in hepatic injury.     

Novel role of curcumin in the prevention of cytokine-induced islet death in vitro and diabetogenesis in vivo

Background and purpose:

Oxidative stress caused by cytokine exposure is a major cause of pancreatic islet death in vitro and of diabetogenesis. Antioxidant compounds may prevent cytokine-induced damage to islet cells. Hence, we studied the potential of curcumin, an antioxidant and anti-inflammatory compound, in vitro to protect islets against pro-inflammatory cytokines and in vivo to prevent the progression of diabetes induced by multiple low doses of streptozotocin (MLD-STZ).

Experimental approach:

Pancreatic islets from C57/BL6J mice were pretreated with curcumin (10 μM) and then exposed to a combination of cytokines. Islet viability, reactive oxygen species (ROS), NO, inducible NO synthase and NF-κB translocation were studied. Curcumin pretreated (7.5 mg kg⁻¹ day⁻¹) C57/BL6J mice were given MLD-STZ (40 mg kg⁻¹), and various parameters of diabetes induction and progression were monitored.

Key results:

Curcumin protected islets from cytokine-induced islet death in vitro by scavenging ROS and normalized cytokine-induced NF-κB translocation by inhibiting phosphorylation of inhibitor of kappa B alpha (IκBα). In vivo, curcumin also prevented MLD-STZ, as revealed by sustained normoglycaemia, normal glucose clearance and maintained pancreatic GLUT2 levels. Pro-inflammatory cytokine concentrations in the serum and pancreas were raised in STZ-treated animals, but not in animals pretreated with curcumin before STZ.

Conclusions and implications:

Here, we have demonstrated for the first time that curcumin in vitro protects pancreatic islets against cytokine-induced death and dysfunction and in vivo prevents STZ-induced diabetes.     

9,10-Dihydro-2,5-dimethoxyphenanthrene-1,7-diol, from Eulophia ochreata, inhibits inflammatory signalling mediated by Toll-like receptors

Background and purpose:

9,10-Dihydro-2,5-dimethoxyphenanthrene-1,7-diol (RSCL-0520) is a phenanthrene isolated from Eulophia ochreata, one of the Orchidaceae family, known by local tradition to exhibit medicinal properties. However, no anti-inflammatory activity or any molecular mechanisms involved have been reported or elucidated. Here, for the first time, we evaluate the anti-inflammatory properties of RSCL-0520 on responses induced by lipopolysaccharide (LPS) and mediated via Toll-like receptors (TLRs).

Experimental approach:

The in vitro anti-inflammatory activities of RSCL-0520 were investigated in LPS-stimulated monocytic cells, measuring activation of cytokine and inflammatory genes regulated by nuclear factor-κB (NF-κB). Tumour necrosis factor (TNF)-α levels in serum following LPS stimulation in mice and carrageenan-induced paw oedema in rats were used as in vivo models.

Key results:

Pretreatment with RSCL-0520 effectively inhibited LPS-induced, TLR4-mediated, NF-κB-activated inflammatory genes in vitro, and reduced both LPS-induced TNF-α release and carrageenan-induced paw oedema in rats. Treatment with RSCL-0520 reduced LPS-stimulated mRNA expression of TNF-α, COX-2, intercellular adhesion molecule-1, interleukin (IL)-8 and IL-1β, all regulated through NF-κB activation. RSCL-0520, however, did not interfere with any cellular processes in the absence of LPS.

Conclusions and implications:

RSCL-0520 blocked signals generated by TLR4 activation, as shown by down-regulation of NF-κB-regulated inflammatory cytokines. The inhibitory effect involved both MyD88-dependent and -independent signalling cascades. Our data elucidated the molecular mechanisms involved, and support the search for plant-derived TLR antagonists, as potential anti inflammatory agents.     

Diosgenin relieves goiter via the inhibition of thyrocyte proliferation in a mouse model of Graves＇ disease

Aim： To investigate the effects of diosgenin （Dio）, a naturally occurring steroid saponin, on goiter formation in a mouse model of Graves’ disease （GD） and the underlying mechanisms.
Methods： Female BALB/c mice were injected with adenovirus expressing the A subunit of thyrotropin receptor to induce GD. The mice were treated with Dio （20, 100 mg·kg-1·d-1, ip） for 12 or 24 d. The serum levels of TT4 and TRAb were examined using radioimmunoassay and electrochemiluminescence. The size and morphology of thyroid glands were examined. Thyrocyte proliferation was determined using BrdU incorporation assay. The expression of proliferation-associated proteins IGF-1, NF-κB, cyclin D1, and PCNA in thyroids was analyzed using immunohistochemistry and real-time PCR.

Results： The GD mice showed significantly high serum levels of TRAb and TT4 compared to the normal mice. Treatment of the GD mice with Dio for 24 d dose-dependently reduced the TT4 level and thyroid size, but did not affect the abnormal level of TRAb. Furthermore, Dio treatment dose-dependently reversed the morphological changes and reduced excessive thyrocyte proliferation in thyroids of the GD mice. Dio treatment also dose-dependently reduced the mRNA and protein levels of IGF-1, NF-κB, cyclin D1, and PCNA in thyroids of the GD mice.

Conclusion： Dio relieves goiter in a mouse model of GD through the inhibition of thyrocyte proliferation. The mechanisms involve the suppression of IGF-1, NF-κB, cyclin D1, and PCNA expression.     

Geniposide inhibits high glucose-induced cell adhesion through the NF-KB signaling pathway in human umbilical vein endothelial cells

Aim:

To investigate whether geniposide, an iridoid glucoside extracted from gardenia jasminoides ellis fruits, inhibits cell adhesion to human umbilical vein endothelial cells (HUVECs) induced by high glucose and its underlying mechanisms.

Methods:

HUVECs were isolated from human umbilical cords and cultured. The adhesion of monocytes to HUVECs was determined using fluorescence-labeled monocytes. The mRNA and protein levels of vascular cell adhesion molecule-1 (VCAM-1) and endothelial selectin (E-selectin) were measured using real-time RT-PCR and ELISA. Reactive oxygen species (ROS) production was measured using a fluorescent probe. The amounts of nuclear factor-kappa B (NF-κB) and inhibitory factor of NF-κB (IκB) were determined using Western blot analysis. The translocation of NF-κB from the cytoplasm to the nucleus was determined using immunofluorescence.

Results:

Geniposide (10–20 μmol/L) inhibited high glucose (33 mmol/L)-induced adhesion of monocytes to HUVECs in a dose-dependent manner. This compound (5–40 μmol/L) also inhibited high glucose-induced expression of VCAM-1 and E-selectin at the gene and protein levels. Furthermore, geniposide (5–20 μmol/L) decreased ROS production and prevented IκB degradation in the cytoplasm and NF-κB translocation from the cytoplasm to the nucleus in HUVECs.

Conclusion:

Geniposide inhibits the adhesion of monocytes to HUVECs and the expression of CAMs induced by high glucose, suggesting that the compound may represent a new treatment for diabetic vascular injury. The mechanism underlying this inhibitory effect may be related to the inhibition of ROS overproduction and NF-κB signaling pathway activation by geniposide.