Sec1 regulates intestinal mucosal immunity in a mouse model of inflammatory bowel disease.

Inflammatory bowel disease (IBD) is a common immune-mediated condition with its molecular pathogenesis remaining to be fully elucidated. This study aimed to deepen our understanding of the role of FUT2 in human IBD, by studying a new surrogate gene Sec1, a neighboring gene of Fut2 and Fut1 that co-encodes the α 1,2 fucosyltransferase in mice. CRISPR/Cas9 was used to prepare Sec1 knockout (Sec1-/-) mice. IBD was induced in mice using 3% w/v dextran sulphate sodium. Small interfering RNA (siRNA) was employed to silence Sec1 in murine colon cancer cell lines CT26.WT and CMT93. IBD-related symptoms, colonic immune responses, proliferation and apoptosis of colon epithelial cells were assessed respectively to determine the role of Sec1 in mouse IBD. Impact of Sec1 on the expression of death receptor 5 (DR5) and other apoptosis-associated proteins were determined. Sec1 knockout was found to be associated with deterioration of IBD in mice and elevated immune responses in the colonic mucosa. Silencing Sec1 in CT26.WT and CMT93 cells led to greater secretion of inflammatory cytokines IL-1ß, IL-6 and TNF-α. Cell counting kit 8 (CCK8) assay, flow cytometry and TUNEL detection suggested that Sec1 expression promoted the proliferation of colon epithelial cells, inhibited cell apoptosis, reduced cell arrest in G0/G1 phase and facilitated repair of inflammatory injury. Over-expression of DR5 and several apoptosis-related effector proteins was noticed in Sec1-/- mice and Sec1-silenced CT26.WT and CMT93 cells, supporting a suppressive role of Sec1 in cell apoptosis. Our results depicted important regulatory roles of Sec1 in mouse IBD, further reflecting the importance of FUT2 in the pathogenesis of human IBD.

Linc00852 from cisplatin-resistant gastric cancer cell-derived exosomes regulates COMMD7 to promote cisplatin resistance of recipient cells through microRNA-514a-5p.

OBJECTIVE: Cisplatin (DDP)-based chemotherapy is commonly referred to as advanced gastric cancer (GC). The purpose of this study was to unravel whether Linc00852 from DDP-resistant tumor cell-derived exosomes (Exos) promotes DDP resistance of GC cells. METHODS: Reverse transcription quantitative polymerase chain reaction was used to detect the expression of Linc00852, miR-514a-5p, COMM domain protein 7 (COMMD7) mRNA, Bax mRNA, and Bcl-2 mRNA. Western blot was used to measure the expression of COMMD7 protein. The IC50 value of DDP is determined by MTT assay. The cell proliferation ability was measured by colony formation test. The apoptosis ability was measured by flow cytometry. The interaction between Linc00852, miR-514a-5p, and COMMD7 was confirmed by luciferase reporter gene assay and RNA pull-down assay. Xenograft tumor model was used to study the effect of Linc00852 on DDP resistance in vivo. RESULTS: Linc00852 was up-regulated in DDP-resistant GC cells and their secreted exosomes. Down-regulating Linc00852 facilitated the sensitivity of DDP-resistant GC cells to DDP. Linc00852 bound to miR-514a-5p and COMMD7 was a target of miR-514a-5p. Linc00852 could regulate COMMD7 expression via targeting miR-514a-5p. Exosomes from DDP-resistant GC cells enhanced the resistance of recipient GC cells to DDP via exosomal delivery of Linc00852. Depletion of Linc00852 repressed the growth and DDP resistance of GC cells in vivo. CONCLUSION: Linc00852 from DDP-resistant tumor cell-derived Exos regulates COMMD7 to promote drug resistance of GC cells through miR-514a-5p.