Enhancer of zeste homolog 2 contributes to apoptosis by inactivating janus kinase 2/ signal transducer and activator of transcription signaling in inflammatory bowel disease

The roles of EZH2 in cancer and its inhibitors

The enhancer of zeste homolog 2 (EZH2) is encoded by the Enhancer of zeste 2 polycomb repressive complex 2 subunit gene. EZH2 is involved in the cell cycle, DNA damage repair, cell differentiation, autophagy, apoptosis, and immunological modulation. The main function of EZH2 is to catalyze the methylation of H3 histone of H3K27Me3, which inhibits the transcription of target genes, such as tumor suppressor genes. EZH2 also forms complexes with transcriptions factors or directly binds to the promoters of target genes, leading to regulate gene transcriptions. EZH2 has been as a prominent target for cancer therapy and a growing number of potential targeting medicines have been developed. This review summarized the mechanisms that EZH2 regulates gene transcription and the interactions between EZH2 and important intracellular signaling molecules (Wnt, Notch, MEK, Akt) and as well the clinical applications of EZH2-targeted drugs.

Mechanism of interventional effect and targets of Zhuyu pill in regulating and suppressing colitis and cholestasis

Zhuyu pill (ZYP) is a traditional Chinese medicine prescription composed of two drugs, Coptis chinensis Franch. and Tetradium ruticarpum (A. Jussieu) T. G. Hartley, and is commonly used in the clinical treatment of diseases of the digestive system. However, the mechanism underlying the effect of ZYP on colitis remains unclear. In this study, a colitis rat model was induced with 2,4,6-trinitro-benzenesulfonic acid (TNBS, 100 mg/kg) and treated with ZYP (low dose: 0.6 g/kg, high dose: 1.2 g/kg). Disease activity index, colonic weight index, and weight change ratio were used to evaluate the model and efficacy. LC-MS and 16S rRNA gene sequencing were used to measure differences in fecal metabolism and microorganism population among the control, model, low-dose ZYP, and high-dose ZYP groups. To elucidate the mechanism of interventional effect of ZYP, Spearman correlation analysis was used to analyze the correlation between fecal metabolism and fecal microbial number. High-dose and low-dose ZYP both exhibited significant interventional effects on colitis rat models, and high-dose ZYP produced a better interventional effect compared with low-dose ZYP. Based on a metabolomics test of fecal samples, significantly altered metabolites in the model and high-dose ZYP treatment groups were identified. In total, 492 metabolites were differentially expressed. Additionally, sequencing of the 16S rRNA gene in fecal samples revealed that the high-dose ZYP could improve TNBS-induced fecal microbiota dysbiosis. Ultimately, changes in tryptophan metabolism and Firmicutes and Gammaproteobacteria populations were detected after ZYP treatment in both colitis and cholestasis. Therefore, we conclude that tryptophan metabolism and Firmicutes and Gammaproteobacteria populations are the core targets of the anti-inflammatory effect of ZYP. These findings provide a scientific basis for further investigation of the anti-inflammatory mechanism of ZYP in the future.

miR-146b suppresses LPS-induced M1 macrophage polarization via inhibiting the FGL2-activated NF-κB/MAPK signaling pathway in inflammatory bowel disease

OBJECTIVES

M1 macrophage polarization and phenotype in Inflammatory Bowel Disease (IBD) are common biological responses.

METHOD

Herein, IBD mice models were constructed and macrophages were derived.

RESULTS

It was discovered that microRNA-146b (miR-146b) was downregulated in IBD mice and Lipopolysaccharide (LPS)-induced macrophages. Moreover, the inhibitory role of overexpressed miR-146b in reducing the inflammation level and blocking M1 macrophage polarization was confirmed. Further investigation indicated that Fibrinogen Like 2 (FGL2) acted as the target gene of miR-146b, and FGL2 mediated activation of NLRP3, NF-κB-p65, and p38-MAPK. More importantly, it was validated that miR-146b could ameliorate inflammatory phenotype and prevent M1 macrophage polarization via inhibiting FGL2 in vitro, and miR-146b overexpression alleviated the intestinal injury of IBD mice in vivo.

CONCLUSIONS

Overall, it is potential to use miR-146b for the amelioration of IBD.

Extracts of Waste from Poplar Wood Processing Alleviate Experimental Dextran Sulfate-Induced Colitis by Ameliorating Oxidative Stress, Inhibiting the Th1/Th17 Response and Inducing Apoptosis in Inflammatory Lymphocytes

As a fast-growing tree, poplar is widely planted and typically used for wood processing in China. During poplar wood processing, a large amount of poplar sawdust (PS) and poplar leaves (PL) are produced and abandoned. To make full use of poplar resources and clarify the use of poplar as a feed additive, the active ingredients in PS and PL were extracted and isolated, and the anti-inflammatory effects of the extracts on mice with dextran sulfate sodium (DSS)-induced colitis were investigated. In vitro anti-inflammatory experiments showed that the ethyl acetate extract of PS and PL (PSE and PLE, respectively) could significantly inhibit the proliferation of concanavalin A (Con A)-activated lymphocytes. Salicortin, tremulacin and salireposide were identified in both PSE and PLE. Oral administration of PSE and PLE rescued DSS-induced colonic shortening, repaired tissue damage, and decreased the disease activity index (DAI). The antioxidant capacity, including the increased activities of glutathione peroxidase (GSH-Px), total superoxide dismutase (T-SOD and catalase (CAT) and decreased activity of myeloperoxidase (MPO), in the colons of mice with colitis was enhanced through the activation of ERK after treatment with PSE and PLE. The ratio of Th1 to Th17 cells, which can lead to inflammation in the spleen, was significantly decreased by the administration of PSE and PLE, while the phosphorylation of related transcription factors (p65, STAT1, and STAT3) was inhibited. Furthermore, PSE and PLE could induce apoptosis in Con A-activated lymphocytes, which may be associated with the increase in p-TBK1, as the molecular docking results also indicated that salireposide in PSE and PLE could interact with the TBK1 protein. Overall, our study provides a promising feed additive for improving intestinal inflammation in animals and a method for the full utilization of poplar resources.

EZH2 Knockout in Oral Cavity Basal Epithelia Causes More Invasive Squamous Cell Carcinomas

Oral squamous cell carcinoma (oral SCC) is an aggressive disease and despite intensive treatments, 5-year survival rates for patients have remained low in the last 20 years. Enhancer of zeste homolog 2 (EZH2), part of polycomb repressive complex 2 (PRC2), is highly expressed in human oral SCC samples and cell lines and has been associated with greater epithelia-to-mesenchymal transition (EMT), invasion, and metastasis. Here we developed a tamoxifen-regulated, transgenic mouse line (KcEZH2) in which EZH2 is selectively knocked out (KO) in some tongue epithelial basal stem cells (SCs) in adult mice. EZH2 KO SCs do not show the H3K27me3 mark, as assessed by double-label immunofluorescence. We used this mouse line to assess EZH2 actions during oral tumorigenesis with our immunocompetent 4-nitroquinoline 1-oxide (4-NQO) model of oral SCC. We report that higher percentages of mice with invasive SCCs and high-grade neoplastic lesions are observed in mice containing EZH2 KO SCs (KcEZH2-2TΔ and KcEZH2-5TΔ mice). Moreover, EZH2 expression does not correlate with the expression of markers of invasive SCCs. Finally, EZH2 KO cells that are E-cadherin+ are present at invasion fronts infiltrating underlying muscle tissue. Our findings indicate that the knockout of EZH2 in basal SCs of tongue epithelia results in more aggressive carcinomas, and this should be considered when targeting EZH2 as a therapeutic strategy.