Di Chen

Gasdermin D plays a key role as a pyroptosis executor of non-alcoholic steatohepatitis in humans and mice

BACKGROUND & AIMSnGasdermin D (GSDMD)-executed programmed necrosis is involved in inflammation and controls interleukin (IL)-1β release. However, the role of GSDMD in non-alcoholic steatohepatitis (NASH) remains unclear. We investigated the role of GSDMD in the pathogenesis of steatohepatitis.nnnMETHODSnHuman liver tissues from patients with non-alcoholic fatty liver disease (NAFLD) and control individuals were obtained to evaluate GSDMD expression. Gsdmd knockout (Gsdmd-/-) mice, obese db/db mice and their wild-type (WT) littermates were fed with methionine-choline deficient (MCD) or control diet to induce steatohepatitis. The Gsdmd-/- and WT mice were also used in a high-fat diet (HFD)-induced NAFLD model. In addition, Alb-Cre mice were administered an adeno-associated virus (AAV) vector that expressed the gasdermin-N domain (AAV9-FLEX-GSDMD-N) and were fed with either MCD or control diet for 10u202fdays.nnnRESULTSnGSDMD and its pyroptosis-inducing fragment GSDMD-N were upregulated in liver tissues of human NAFLD/NASH. Importantly, hepatic GSDMD-N protein levels were significantly higher in human NASH and correlated with the NAFLD activity score and fibrosis. GSDMD-N remained a potential biomarker for the diagnosis of NASH. MCD-fed Gsdmd-/- mice exhibit decreased severity of steatosis and inflammation compared with WT littermates. GSDMD was associated with the secretion of pro-inflammatory cytokines (IL-1β, TNF-α, and MCP-1 [CCL2]) and persistent activation of the NF-ĸB signaling pathway. Gsdmd-/- mice showed lower steatosis, mainly because of reduced expression of the lipogenic gene Srebp1c (Srebf1) and upregulated expression of lipolytic genes, including Pparα, Aco [Klk15], Lcad [Acadl], Cyp4a10 and Cyp4a14. Alb-Cre mice administered with AAV9-FLEX-GSDMD-N showed significantly aggravated steatohepatitis when fed with MCD diet.nnnCONCLUSIONnAs an executor of pyroptosis, GSDMD plays a key role in the pathogenesis of steatohepatitis, by controlling cytokine secretion, NF-ĸB activation, and lipogenesis.nnnLAY SUMMARYnNon-alcoholic fatty liver disease has become one of the most feared chronic liver diseases, because it is the most rapidly growing indication for adult liver transplantation and a major cause of hepatocellular carcinoma. However, the mechanisms involved in the transformation of simple steatosis to steatohepatitis remain unclear. Herein, we show that gasdermin D driven pyroptosis is prominent in patients with non-alcoholic steatohepatitis (NASH), and gasdermin-N domain remains a potential biomarker for the diagnosis of NASH. Gasdermin D plays a key role in the pathogenesis of NASH by regulating lipogenesis, the inflammatory response, and the NF-ĸB signaling pathway, revealing potential treatment targets for NASH in humans.

Downregulation of leucine-rich repeats and immunoglobulin-like domains 1 by microRNA-20a modulates gastric cancer multidrug resistance

Multidrug resistance (MDR) significantly restricts the clinical efficacy of gastric cancer (GC) chemotherapy, and it is critical to search novel targets to predict and overcome MDR. Leucine‐rich repeats and immunoglobulin‐like domains 1 (LRIG1) has been proved to be correlated with drug resistance in several cancers. The present study revealed that LRIG1 was overexpressed in chemosensitive GC tissues and decreased expression of LRIG1 predicted poor survival in GC patients. We observed that upregulation of LRIG1 enhanced chemosensitivity in GC cells. Interestingly, miR‐20a, which was overexpressed in GC MDR cell lines and tissues, was identified to regulate LRIG1 expression by directly targeting its 3′ untranslated region. We also found that inhibition of miR‐20a suppressed GC MDR, and upregulation showed opposite effects. Moreover, we demonstrated that the miR‐20a/LRIG1 axis regulated GC cell MDR through epidermal growth factor receptor (EGFR)‐mediated PI3K/AKT and MAPK/ERK signaling pathways. Finally, LRIG1 expression in human GC tissues is inversely correlated with miR‐20a and EGFR. Taken together, the newly identified miR‐20a/LRIG1/EGFR link provides insight into the MDR process of GC, and targeting this axis represents a novel potential therapeutic strategy to block GC chemoresistance.

FOXK1 plays an oncogenic role in the development of esophageal cancer

Forkhead box k1 (FOXK1) is a member of the FOX class of transcription factors and it is dysregulated in many solid tumors including hepatocellular carcinoma, gastric cancer, colorectal cancer and prostate cancer. However, the expression status of FOXK1 and its clinical significance in esophageal cancer (EC) is still uncertain. Our study aimed at investigating the significance of FOXK1 expression in human EC and its biological function in the development of EC. We found that FOXK1 was overexpressed in EC tissues compared with corresponding non-tumor tissues using immunohistochemistry. And high FOXK1 expression was related to poor differentiation of EC. The Kaplan-Meier curve indicated that high FOXK1 expression may result in poor prognosis of EC patients. Furthermore, overexpression of FOXK1 in EC9706xa0cell inhibited cell apoptosis and promoted cell proliferation and migration, and suppression of FOXK1 in EC109xa0cell obtained reverse results. Our data suggest that FOXK1 plays an oncogenic role in EC pathogenesis and can serve as a therapeutic target for patients with EC.

O-GlcNAcylation promotes colorectal cancer metastasis via the miR-101-O-GlcNAc/EZH2 regulatory feedback circuit

Advanced colorectal cancer (CRC) is one of the deadliest cancers, and the 5-year survival rate of patients with metastasis is extremely low. The epithelial–mesenchymal transition (EMT) is considered essential for metastatic CRC, but the fundamental molecular basis underlying this effect remains unknown. Here, we identified that O-GlcNAcylation, a unique posttranslational modification (PTM) involved in cancer metabolic reprogramming, increased the metastatic capability of CRC. The levels of O-GlcNAcylation were increased in the metastatic CRC tissues and cell lines, which likely promoted the EMT by enhancing EZH2 protein stability and function. The CRC patients with higher levels of O-GlcNAcylation exhibited greater lymph node metastasis potential and lower overall survival. Bioinformatic analysis and luciferase reporter assays revealed that both O-GlcNAcylation transferase (OGT) and EZH2 are posttranscriptionally inhibited by microRNA-101. In addition, O-GlcNAcylation and H3K27me3 modification in the miR-101 promoter region further inhibited the transcription of miR-101, resulting in the upregulation of OGT and EZH2 in metastatic CRC, thus forming a vicious cycle. In this study, we demonstrated that O-GlcNAcylation, which is negatively regulated by microRNA-101, likely promotes CRC metastasis by enhancing EZH2 protein stability and function. Reducing O-GlcNAcylation may be a potential therapeutic strategy for metastatic CRC.

miR-148b-3p inhibits gastric cancer metastasis by inhibiting the Dock6/Rac1/Cdc42 axis

BackgroundOur previous work showed that some Rho GTPases, including Rho, Rac1 and Cdc42, play critical roles in gastric cancer (GC); however, how they are regulated in GC remains largely unknown. In this study, we aimed to investigate the roles and molecular mechanisms of Dock6, an atypical Rho guanine nucleotide exchange factor (GEF), in GC metastasis.MethodsThe expression levels of Dock6 and miR-148b-3p in GC tissues and paired nontumor tissues were determined by immunohistochemistry (IHC) and in situ hybridization (ISH), respectively. The correlation between Dock6/miR-148b-3p expression and the overall survival of GC patients was calculated by the Kaplan-Meier method and log-rank test. The roles of Dock6 and miR-148b-3p in GC were investigated by in vitro and in vivo functional studies. Rac1 and Cdc42 activation was investigated by GST pull-down assays. The inhibition of Dock6 transcription by miR-148b-3p was determined by luciferase reporter assays.ResultsA significant increase in Dock6 expression was found in GC tissues compared with nontumor tissues, and its positive expression was associated with lymph node metastasis and a higher TNM stage. Patients with positive Dock6 expression exhibited shorter overall survival periods than patients with negative Dock6 expression. Dock6 promoted GC migration and invasion by increasing the activation of Rac1 and Cdc42. miR-148b-3p expression was negatively correlated with Dock6 expression in GC, and it decreased the motility of GC cells by inhibiting the Dock6/Rac1/Cdc42 axis.ConclusionsDock6 was over-expressed in GC tissues, and its positive expression was associated with GC metastasis and indicated poor prognosis of GC patients. Targeting of Dock6 by miR-148b-3p could activate Rac1 and Cdc42, directly affecting the motility of GC cells. Targeting the Dock6-Rac1/Cdc42 axis could serve as a new therapeutic strategy for GC treatment.

Downregulation of gasdermin D promotes gastric cancer proliferation by regulating cell cycle-related proteins: Gasdermin D and gastric cancer proliferation

To explore the relationship between gasdermin D (GSDMD) and gastric cancer (GC) cell proliferation, and to determine whether the downregulated expression of GSDMD contributed to the tumorigenesis and proliferation of GC cells.

Specific changes of enteric mycobiota and virome in inflammatory bowel disease: Mycobiota and virome in IBD

One of the important features of inflammatory bowel disease (IBD) is dysbiosis of the gut microbiota. It has been well documented that changes in the commensal bacterial population are involved in IBD development. However, the function of the fungal and viral communities in IBD remains unclear. Moreover, the optimal treatment for IBD patients with opportunistic infections is still undecided. This review focused on how the enteric mycobiota and virome changes during the pathogenesis of IBD and discussed potential treatment strategies that open new insights into the managements of IBD.

miR‐204‐5p suppresses hepatocellular cancer proliferation by regulating homeoprotein SIX1 expression

Fewer than 30% of patients with hepatocellular carcinoma (HCC) are eligible to receive curative therapies, and so a better understanding of the molecular mechanisms of HCC is needed to identify potential therapeutic targets. The role of microRNA (miRNA) in modulating tumour progression has been demonstrated, and therapies targeting miRNA appear promising. miR‐204‐5p has been shown to function in numerous types of cancer, but its role in HCC remains unclear. In this study, we found that miR‐204‐5p expression was downregulated in cancerous HCC tissues compared to nontumour tissues. Kaplan–Meier survival curve analysis also showed that low expression of miR‐204‐5p predicted worse outcomes of HCC patients. In addition, miR‐204‐5p expression was significantly lower in HCC cell lines. The function of miR‐204‐5p was also assessed both in vitro and in vivo. We demonstrated that ectopic expression of miR‐204‐5p in HCC cell lines inhibited HCC cell proliferation and clonogenicity using CCK8, BrdU and colony‐forming assays, while the inhibition of miR‐204‐5p enhanced proliferation and clonogenicity. Further in vivo studies in mice further confirmed the proliferation capacity of miR‐204‐5p. We also identified sine oculis homeobox homologue 1 (SIX1) as a direct target of miR‐204‐5p and showed that it was inversely correlated with miR‐204‐5p in both human and mouse HCC tissues. Transfection of miR‐204‐5p mimics in BEL‐7404 cells blocked the cell cycle by inhibiting the expression of cyclin‐D1 and cyclin‐A1, cell cycle‐related factors regulated by SIX1. More importantly, overexpression of the 3′UTR mutant SIX1 but not the wild‐type SIX1 abolished the suppressive effect of miR‐204‐5p, and downregulated SIX1 in BEL‐7402 cells that transfected with miR‐204 inhibitors could partly block the inhibitory effect of miR‐204‐5p on proliferation. Thus, we have demonstrated that miR‐204‐5p suppresses HCC proliferation by directly regulating SIX1 and its downstream factors.

Novel peptide GX1 inhibits angiogenesis by specifically binding to transglutaminase-2 in the tumorous endothelial cells of gastric cancer

The clinical application of GX1, an optimal gastric cancer (GC) targeting peptide, is greatly limited because its receptor in the GC vasculature is unknown. In this study, we screened the candidate receptor of GX1, transglutaminase-2(TGM2), by co-immunoprecipitation (co-IP) combined with mass spectrometry. We found that TGM2 was up-regulated in GC vascular endothelial cells and that GX1 receptor expression was suppressed correspondingly after TGM2 downregulation. A highly consistent co-localization of GX1 receptor and TGM2 was detected at both the cellular and tissue levels. High TGM2 expression was evident in GC tissues from patients with poor prognosis. After TGM2 downregulation, the GX1-mediated inhibition of proliferation and migration and the induction of the apoptosis of GC vascular endothelial cells were weakened or even reversed. Finally, we observed that GX1 could inhibit the GTP-binding activity of TGM2 by reducing its intracellular distribution and downregulating its downstream molecular targets (nuclear factor-kappa B, NF-κB; hypoxia-inducible factor 1-α, HIF1α) in GC vascular endothelial cells. Our study confirms that peptide GX1 can inhibit angiogenesis by directly binding to TGM2, subsequently reducing the GTP-binding activity of TGM2 and thereby suppressing its downstream pathway(NF-κB/HIF1α). Our conclusions suggest that GX1/TGM2 may provide a new target for the diagnosis and treatment of GC.

MicroRNA-495-3p inhibits multidrug resistance by modulating autophagy through GRP78/mTOR axis in gastric cancer

Multidrug resistance (MDR) accounts for poor prognosis in gastric cancer (GC). MicroRNAs (miRNAs) are critical regulators of MDR via modulation of the target genes. The present study revealed that miR-495-3p could act via a target gene, GRP78, to regulate the process of autophagy and inhibit MDR. Based on the in vitro and in vivo gain-of-function or loss-of-function experiments, overexpression of miR-495-3p was sufficient to reverse the MDR to four chemotherapeutics in vitro and inhibit the tumor growth in vivo. Moreover, GRP78 was positively associated with the occurrence of autophagy. Thus, reducing the expression of GRP78 by siRNA resulted in autophagy-suppressive activity similar to that of miR-495-3p on mammalian target of rapamycin (mTOR) and its substrates activation and autophagy inhibition, while restoring GRP78 attenuated the anti-autophagy effects caused by miR-495-3p. Clinically, either miR-495-3p downregulation or GRP78 upregulation was associated with malignant phenotypes in patients with GC. In conclusion, these findings demonstrate that miR-495-3p is an important regulator of autophagy balance and MDR by modulating the GRP78/mTOR axis. In addition, miR-495-3p and GRP78 could be used as prognostic factors for overall survival in GC, which implicates miR-495-3p as a therapeutic target in cancer.