Ke Si Wang

Dihydromyricetin suppresses TNF-α-induced NF-κB activation and target gene expression

Nuclear factor-kappa B (NF-κB) has been reported to play a pivotal role in many physiological processes including inflammation, apoptosis, and angiogenesis. We discovered a potent natural NF-κB inhibitor, dihydromyricetin, from the traditional herb Ampelopsis grossedentata, which has a long history of use in food and medicine. In this study, we demonstrated the effect of dihydromyricetin on NF-κB activation in TNF-α-induced HeLa cells. Dihydromyricetin was found to markedly inhibit the phosphorylation and degradation of the inhibitor of NF-κB alpha (IκBα), and subsequent nuclear translocation of p65. Dihydromyricetin also has an impact on upstream signaling of IKK through the inhibition of expression of adaptor proteins, TNF receptor-associated factor 2 (TRAF2), and receptor-interacting protein 1 (RIP1). Furthermore, the current results reveal that dihydromyricetin led to the downregulation of target genes involved in inflammation, proliferation, as well as potentiation of TNF-α-induced apoptosis through suppressing the activation of NF-κB. In conclusion, our data indicate that dihydromyricetin may be a potentially useful therapeutic agent for inflammatory diseases.

Artemisinin inhibits inflammatory response via regulating NF-κB and MAPK signaling pathways.

Abstract Artemisinin, isolated from the Chinese plant Artemisia annua, has been used for many years to treat different forms of malarial parasites. In this study, we explored the anti-inflammatory activity of artemisinin and the underlying mechanism of this action. We demonstrated that the anti-inflammatory effects of artemisinin in TPA-induced skin inflammation in mice. Then the artemisinin significantly inhibited the expression of NF-κB reporter gene induced by TNF-α in a dose-dependent manner. Artemisinin also inhibited TNF-α induced phosphorylation and degradation of IκBα, p65 nuclear translocation. Artemisinin also has an impact on upstream signaling of IKK through the inhibition of expression of adaptor proteins, TNF receptor-associated factor 2 (TRAF2) and receptor interacting protein 1 (RIP1). Furthermore, pretreatment of cells with artemisinin prevented the TNF-α-induced expression of NF-κB target genes, such as anti-apoptosis (c-IAP1, Bcl-2, and FLIP), proliferation (COX-2, cyclinD1), invasion (MMP-9), angiogenesis (VEGF), and major inflammatory cytokines (TNF-α, iNOS, and MCP1). We also proved that artemisinin potentiated TNF-α-induced apoptosis. Moreover, artemisinin significantly impaired the ROS production and phosphorylation of p38 and ERK, but did not affect the phosphorylation of JNK. Taken together, artemisinin may be a potentially useful therapeutic agent for inflammatory-related diseases.

Blockade of TNF-α-induced NF-κB signaling pathway and anti-cancer therapeutic response of dihydrotanshinone I

The nuclear factor-κB (NF-κB) transcription factors control many physiological processes including inflammation, immunity, apoptosis, and angiogenesis. We identified dihydrotanshinone I as an inhibitor of NF-κB activation through our research on Salvia miltiorrhiza Bunge. In this study, we found that dihydrotanshinone I significantly inhibited the expression of NF-κB reporter gene induced by TNF-α in a dose-dependent manner. And dihydrotanshinone I also inhibited TNF-α induced phosphorylation and degradation of IκBα, phosphorylation and nuclear translocation of p65. Furthermore, pretreatment of cells with this compound prevented the TNF-α-induced expression of NF-κB target genes, such as anti-apoptosis (cIAP-1 and FLIP), proliferation (COX-2), invasion (MMP-9), angiogenesis (VEGF), and major inflammatory cytokines (TNF-α, IL-6, and MCP1). We also demonstrated that dihydrotanshinone I potentiated TNF-α-induced apoptosis. Moreover, dihydrotanshinone I significantly impaired activation of extracellular signal-regulated kinase 1/2 (ERK1/2), p38 and stress-activated protein kinase/c-Jun NH2-terminal kinase (JNK/SAPK). In vivo studies demonstrated that dihydrotanshinone I suppressed the growth of HeLa cells in a xenograft tumor model, which could be correlated with its modulation of TNF-α production. Taken together, dihydrotanshinone I could be a valuable candidate for the intervention of NF-κB-dependent pathological conditions such as inflammation and cancer.

Imperatorin suppresses proliferation and angiogenesis of human colon cancer cell by targeting HIF-1α via the mTOR/p70S6K/4E-BP1 and MAPK pathways

ETHNOPHARMACOLOGICAL RELEVANCE Angelica dahurica is a commonly used traditional Chinese medicine to treat migraine headache, toothache and cancer. Imperatorin is an active natural furocoumarin component originating from Angelica dahurica and has been shown to exhibit multiple bioeffector functions, including anti-cancer activity. However, the mechanism by which imperatorin inhibits tumor growth is not fully understood. AIM OF THE STUDY The aim of this study was to investigate the effectiveness of imperatorin as a treatment of cancer and to identify the underlying mechanisms of its anticancer activity. MATERIALS AND METHODS HCT116, HeLa, and Hep3B cells were used in this study. Major assays were promoter-reporter gene assay, MTT, western blot analysis, immunofluorescence assay, reverse transcription-PCR (RT-PCR), flow cytometric analysis, clonogenic assay, EdU labeling and immunofluorescence, xenografted assay, and VEGF ELISA. RESULTS We here demonstrated the effect of imperatorin on hypoxia-inducible factor-1 (HIF-1) activation. Imperatorin showed a potent inhibitory activity against HIF-1 activation induced by hypoxia in various human cancer cell lines. This compound markedly decreased the hypoxia-induced accumulation of HIF-1α protein dose-dependently, whereas it did not affect the expressions of HIF-1β and topoisomerase-I (Topo-I). Further analysis revealed that imperatorin inhibited HIF-1α protein synthesis, without affecting the expression level of HIF-1α mRNA or degradation of HIF-1α protein. Moreover, the phosphorylation levels of mammalian target of rapamycin (mTOR), ribosomal protein S6 kinase (p70S6K), eIF4E binding protein-1 (4E-BP1), eukaryotic initiation factor 4E (eIF4E), extracellular signal-regulated kinase-1/2 (ERK1/2), SAPK/JNK and p38 were significantly suppressed by imperatorin. Furthermore, imperatorin prevented hypoxia-induced expression of HIF-1 target genes and flow cytometric analysis indicated that imperatorin induced G1 phase arrest in human colon cancer cell (HCT116). We found that imperatorin administration inhibits tumor growth and blocks tumor angiogenesis in a xenograft tumor model. CONCLUSIONS These results show that imperatorin inhibited HIF-1α protein synthesis by downregulating the mTOR/p70S6K/4E-BP1 and MAPK pathways. These conclusions suggest that imperatorin is an effective inhibitor of HIF-1 and provide new perspectives into the mechanism of its anticancer activity.

Zinc finger protein 91 (ZFP91) activates HIF-1α via NF-κB/p65 to promote proliferation and tumorigenesis of colon cancer

Zinc finger protein 91 (ZFP91) has been reported to be involved in various biological processes. However, the clinical significance and biological role of ZFP91 in colon cancer remains unknown. Here, we show that ZFP91 expression is upregulated in patients with colon cancer. We found that ZFP91 upregulated HIF-1α at the levels of promoter and protein in colon cancer cells. Using chromatin immunoprecipitation, electrophoretic mobility shift assay and luciferase reporter gene assay, we found that NF-κB/p65 is required for the binding of ZFP91 to the HIF-1α promoter at −197/−188 base pairs and for the transcriptional activation of HIF-1α gene mediated by ZFP91. Flow cytometry, 5-ethynyl-2′-deoxyuridine (EdU) incorporation and tumor xenograft assay demonstrated that ZFP91 enhanced cell proliferation of colon cancer through upregulating HIF-1α in vitro and in vivo. Furthermore, ZFP91 is positively associated with HIF-1α in human colon cancer. Thus, we concluded that ZFP91 activates transcriptional coregulatory protein HIF-1α through transcription factor NF-κB/p65 in the promotion of proliferation and tumorigenesis in colon cancer cell. ZFP91 may serve as a driver gene to activate HIF-1α transcription in the development of cancer.

Perillyl alcohol efficiently scavenges activity of cellular ROS and inhibits the translational expression of hypoxia-inducible factor-1α via mTOR/4E-BP1 signaling pathways.

Perillyl alcohol (POH) is a dietary monoterpene present in a variety of plants with a pure or mixed form, and it is one of the very few natural substances with anticancer activity. However, the mechanism by which POH unleashes its anticancer activity in tumor cells remains unclear. We here demonstrated the effect of POH on hypoxia-inducible factor-1α (HIF-1α) activation. POH showed the potent inhibitory activity against HIF-1 activation induced by hypoxia in various human cancer cell lines and efficient scavenging activity of cellular Reactive oxygen species (ROS) by hypoxia in tumor cells. Further analysis revealed that POH inhibited HIF-1α protein synthesis, without affecting the expression level of HIF-1α mRNA or degradation of HIF-1α protein. Moreover, we found that suppression of HIF-1α accumulation by POH correlated with strong de-phosphorylation of mammalian target of rapamycin (mTOR) and eIF4E binding protein-1 (4E-BP1), and eukaryotic initiation factor 4E (eIF4E). These results showed that POH inhibited HIF-1α protein synthesis through the inhibition of mTOR/4E-BP1 signaling pathways. Furthermore, POH increased the expression of p53, p21, induced cell cycle arrest in the G1 phase as well as decreased cyclin D1, c-Myc, and Skp2 expression. In vivo studies further confirmed the inhibitory effect of POH on the expression of HIF-1α proteins, leading to a decrease growth of HCT116 cells in a xenograft tumor model. There results show that POH is an effective inhibitor of HIF-1 and provide new perspectives in to the mechanism of its anticancer activity.

Chelidonine inhibits TNF-α-induced inflammation by suppressing the NF-κB pathways in HCT116 cells

Nuclear factor kappa‐light‐chain‐enhancer of activated B cells (NF‐κB) is a complex that regulates several hundreds of genes, including those involved in immunity and inflammation, survival, proliferation, and the negative feedback of NF‐κB signaling. Chelidonine, a major bioactive, isoquinoline alkaloid ingredient in Chelidonium majus, exhibits antiinflammatory pharmacological properties. However, its antiinflammatory molecular mechanisms remain unclear. In this work, we explored the effect of chelidonine on TNF‐induced NF‐κB activation in HCT116 cells. We found chelidonine inhibited the phosphorylation and degradation of the inhibitor of NF‐κB alpha and nuclear translocation of RELA. Furthermore, by inhibiting the activation of NF‐κB, chelidonine downregulated target genes involved in inflammation, proliferation, and apoptosis. Chelidonine also inhibited mitogen‐activated protein kinase pathway activation by blocking c‐Jun N‐terminal kinase and p38 phosphorylation. These results suggest that chelidonine may be a potential therapeutic agent against inflammatory diseases in which inhibition of NF‐κB activity plays an important role.

Amorfrutin A inhibits TNF-α induced JAK/STAT signaling, cell survival and proliferation of human cancer cells

Abstract Context: Amorfrutin A is a natural product isolated from the fruits of Amorpha fruticosa L. and has been shown to exhibit multiple bioeffector functions. In the present study, we investigated whether amorfrutin A exerts anticancer effects by inhibiting STAT3 activation in cervical cancer cells. Objective: To investigate the effectiveness of amorfrutin A as a treatment of cancer, and determine the underlying pharmacological mechanism of action. Materials and methods: HeLa, SK-Hep1, MDA-MB-231 and HCT116 cells were used in this study. Major assays were luciferase reporter assay, MTT, Western blot analysis, immunofluorescence assay, reverse transcription-PCR (RT-PCR), flow cytometric analysis, EdU labeling and immunofluorescence, xenografted assay. Results: Amorfrutin A significantly inhibited tumor necrosis factor-α (TNF-α)-induced phosphorylation and nuclear translocation of STAT3 in human cervical carcinoma cells. Amorfrutin A also inhibited activation of the upstream kinases Janus-activated kinase 1 (JAK1), JAK2 and Src signaling pathways. Furthermore, amorfrutin A increased the expression of p53, p21, p27, induced cell cycle arrest in the G1 phase as well as decreased levels of various oncogene protein products. In vivo studies further confirmed the inhibitory effect of amorfrutin A on the expression of STAT3 proteins, leading to a decrease growth of HeLa cells in a xenograft tumor model. Discussion and conclusions: The results indicated that amorfrutin A is a potent inhibitor of STAT3 and provide new perspectives into the mechanism of its anticancer activity.