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.

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Hypoxia-inducible factor-1 (HIF-1) is the central mediator of cellular responses to low oxygen and vital to many aspects of cancer biology. In a search for HIF-1 inhibitors, we identified celastrol as an inhibitor of HIF-1 activation from Tripterygium wilfordii. In the present study, we demonstrated the effect of celastrol on HIF-1 activation. Celastrol 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). Furthermore, celastrol prevented hypoxia-induced expression of HIF-1 target genes for vascular endothelial growth factor (VEGF) and erythropoietin (EPO). Further analysis revealed that celastrol inhibited HIF-1α protein synthesis, without affecting the expression level of HIF-1α mRNA or degradation of HIF-1α protein. Markedly, we found that suppression of HIF-1α accumulation by celastrol correlated with strong dephosphorylation of mammalian target of rapamycin (mTOR) and its effectors, ribosomal protein S6 kinase (p70S6K) and eukaryotic initiation factor 4E (eIF4E) and extracellular signal-regulated kinase (ERK), pathways known to regulate HIF-1α expression at the translational level. In vivo studies further confirmed the inhibitory effect of celastrol on the expression of HIF-1α proteins, leading to a decreased growth of Hep3B cells in a xenograft tumor model. Our data suggested that celastrol is an effective inhibitor of HIF-1 and provide new perspectives into the mechanism of its anticancer activity.

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.

The nuclear factor-κB (NF-κB) transcription factors control many physiological processes including inflammation, immunity, apoptosis and angiogenesis. In our search for NF-κB inhibitors from natural resources, we identified baicalein from Scutellaria baicalensis as an inhibitor of NF-κB activation. As examined by the NF-κB luciferase reporter assay, we found that baicalein suppressed TNF-α-induced NF-κB activation in a dose-dependent manner. It also inhibited TNF-α-induced nuclear translocation of p65 through inhibition of phosphorylation and degradation of IκBα. Furthermore, baicalein blocked the TNF-α-induced expression of NF-κB target genes involved in anti-apoptosis (cIAP-1, cIAP-2, FLIP and BCL-2), proliferation (COX-2, cyclin D1 and c-Myc), invasion (MMP‑9), angiogenesis (VEGF) and major inflammatory cytokines (IL-8 and MCP1). The flow cytometric analysis indicated that baicalein potentiated TNF-α-induced apoptosis and induced G1 phase arrest in HeLa cells. Moreover, baicalein significantly blocked activation of p38, extracellular signal-regulated kinase 1/2 (ERK1/2). Our results imply that baicalein could be a lead compound for the modulation of inflammatory diseases as well as certain cancers in which inhibition of NF-κB activity may be desirable.