Sec62 promotes gastric cancer metastasis through mediating UPR-induced autophagy activation.

BACKGROUND AND AIMS: Sec62 is a membrane protein of the endoplasmic reticulum that facilitates protein transport. Its role in cancer is increasingly recognised, but remains largely unknown. We investigated the functional role of Sec62 in gastric cancer (GC) and its underlying mechanism. METHODS: Bioinformatics, tissue microarray, immunohistochemistry (IHC), western blotting (WB), quantitative polymerase chain reaction (qPCR), and immunofluorescence were used to examine the expression of target genes. Transwell, scratch healing assays, and xenograft models were used to evaluate cell migration and invasion. Transmission electron microscopy and mRFP-GFP-LC3 double-labeled adenoviruses were used to monitor autophagy. Co-immunoprecipitation (CO-IP) was performed to evaluate the binding activity between the proteins. RESULTS: Sec62 expression was upregulated in GC, and Sec62 upregulation was an independent predictor of poor prognosis. Sec62 overexpression promoted GC cell migration and invasion both in vitro and in vivo. Sec62 promoted migration and invasion by affecting TIMP-1 and MMP2/9 balance. Moreover, Sec62 could activate autophagy by upregulating PERK/ATF4 expression and binding to LC3II with concomitant FIP200/Beclin-1/Atg5 activation. Furthermore, autophagy blockage impaired the promotive effects of Sec62 on GC cell migration and invasion, whereas autophagy activation rescued the inhibitory effect of Sec62 knockdown on GC metastasis. Notably, Sec62 inhibition combined with autophagy blockage exerted a synergetic anti-metastatic effect in vitro and in vivo. CONCLUSION: Sec62 promotes GC metastasis by activating autophagy and subsequently regulating TIMP-1 and MMP2/9 balance. The activation of autophagy by Sec62 may involve the unfolded protein response (UPR)-related PERK/ATF4 pathway and binding of LC3II during UPR recovery involving FIP200/Beclin-1/Atg5 upregulation. Specifically, the dual inhibition of Sec62 and autophagy may provide a promising therapeutic strategy for GC metastasis.

Downregulation of gasdermin D promotes gastric cancer proliferation by regulating cell cycle-related proteins.

OBJECTIVE: 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. METHODS: GSDMD expressions in GC tissues and matched adjacent non-cancerous tissues were assessed by quantitative real-time polymerase chain reaction, Western blot and immunohistochemistry. The effect of GSDMD on cell proliferation in vitro was assessed by the colony formation assay and cell viability assays. In vivo, xenografted tumors in nude mice were evaluated. The cell cycle was analyzed by flow cytometry. In addition, the alterations of several cell cycle-related and cell signaling pathway proteins were analyzed by Western blot. RESULTS: GSDMD expression was decreased in GC, and the decreased expression of GSDMD could markedly promote the proliferation of tumors in vivo and in vitro. The downregulation of GSDMD accelerated S/G2 cell transition by activating extracellular signal regulated kinase, signal transducer and activator of transcription 3 and phosphatidylinositol 3 kinase/protein kinase B signaling pathways and regulating cell cycle-related proteins in GC. CONCLUSION: GSDMD may protect against cell proliferation of GC, and it may be used as a diagnostic and treatment strategy for GC.

IL-17 is a protection effector against the adherent-invasive Escherichia coli in murine colitis.

Inflammatory bowel disease (IBD) is caused by aberrant immune responses to the gut microbiota. Among the gut microbiota, adherent-invasive Escherichia Coli (AIEC) is thought to be the pathogen through invading the intestinal epithelial cells and causing inflammation. IL-17 secretion increase, induced by enhanced bacterial adhesion to the intestine epithelium, could on one hand protect the mucosa, but on the other hand, over amount of IL-17 initializes inflammation reactions that in turn damages the mucosa. The relationship between IL-17 and AIEC is still unclear. In this study, we tried to elucidate the function of IL-17 in AIEC-mediated colitis. Wild type (WT) and IL-17 knockout (IL-17 KO) mice were inoculated with AIEC strain E. coli LF82 and treated with dextran sodium sulphate (DSS). Histological examination of the colon was performed. Mucosa damage was assessed and scored. IL-22 and IL-17 in colon tissues were detected by ELISA, qPCR and immunohistochemistry methods. Transient AIEC colonization in IL-17 KO mice resulted in increased intestinal epithelial damage, systemic bacterial burden and mortality compared with WT controls. Moreover, IL-17 is required for the induction of IL-22 in the experimental animal models during AIEC strain E. coli LF82 colonization. These results indicate IL-17 plays a protective role in AIEC strain E. coli LF82 induced colitis by promoting IL-22 secretion.

Specific changes of enteric mycobiota and virome in inflammatory bowel disease.

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.