Table_2_Cancer-Preventive Role of Bone Marrow-Derived Mesenchymal Stem Cells on Colitis-Associated Colorectal Cancer: Roles of Gut Microbiota Involved.DOCX

BackgroundMesenchymal stem cells (MSCs) treatment showed promising results in inflammatory bowel disease in both rodent models and patients. Nevertheless, previous studies conducted conflicting results on preclinical tumor models treated with MSCs concerning their influence on tumor initiation and progression. This study is designed to demonstrate the role of bone marrow-derived MSCs and the potential mechanism in the colitis-associated colon cancer (CAC) model. MethodsBone marrow-derived MSCs were isolated from green fluorescent protein-transgenic mice, cultured, and identified by flow cytometry. Azoxymethane and dextran sulfate sodium were administrated to establish the CAC mouse model, and MSCs were infused intraperitoneally once per week. The mice were weighed weekly, and colon length, tumor number, and average tumor size were assessed after the mice were killed. MSC localization was detected by immunofluorescence staining; tumor cell proliferation and apoptosis were measured by immunohistochemistry staining of Ki-67 and terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling assay, respectively. The colonic tumor tissues were isolated for RNA-seq, and fecal samples were collected for 16S ribosomal RNA sequencing of the microbiome. ResultsAfter injection intraperitoneally, MSCs migrated to the intestine and inhibited the initiation of colitis-associated colorectal cancer. This inhibition effect was marked by less weight loss, longer colon length, and reduced tumor numbers. Moreover, MSCs reduced tumor cell proliferation and induced tumor cell apoptosis. Furthermore, MSCs could inhibit chronic inflammation assessed by RNA-sequencing and promote gut microbiome normalization detected by 16S ribosomal RNA sequencing. ConclusionThe results proved that MSCs could migrate to the colon, inhibit chronic inflammation, and regulate gut microbiome dysbiosis to suppress the development of CAC.背景：间充质干细胞（mesenchymal stem cells, MSCs）在炎症性肠病的治疗中，于啮齿类动物模型及患者群体内均展现出良好的应用前景。然而，既往针对经MSCs处理的临床前肿瘤模型开展的研究，关于MSCs对肿瘤发生与进展的影响，所得结论存在矛盾。本研究旨在阐明骨髓来源MSCs在结肠炎相关结直肠癌（colitis-associated colon cancer, CAC）模型中的作用及其潜在分子机制。 方法：从绿色荧光蛋白转基因小鼠体内分离骨髓来源MSCs，进行体外培养，并通过流式细胞术进行鉴定。采用氧化偶氮甲烷与葡聚糖硫酸钠联合造模，构建CAC小鼠模型，每周经腹腔注射一次MSCs。每周称量小鼠体重，处死后评估结肠长度、肿瘤数量及平均肿瘤体积。通过免疫荧光染色检测MSCs的体内定位；分别采用Ki-67抗原免疫组化染色及末端脱氧核苷酸转移酶dUTP缺口末端标记（terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling, TUNEL）测定法，检测肿瘤细胞增殖与凋亡情况。分离结肠肿瘤组织进行RNA测序（RNA-seq），收集粪便样本进行微生物组16S核糖体RNA测序。 结果：经腹腔注射后，MSCs可迁移至肠道，并抑制结肠炎相关结直肠癌的发生。该抑制效应体现为小鼠体重丢失减少、结肠长度更长及肿瘤数量降低。此外，MSCs可抑制肿瘤细胞增殖并诱导肿瘤细胞凋亡。进一步研究显示，通过RNA测序分析可知，MSCs可抑制慢性炎症；而16S核糖体RNA测序结果表明，MSCs可促进肠道微生物组恢复稳态。 结论：本研究结果证实，MSCs可迁移至结肠，通过抑制慢性炎症及调节肠道微生物群失调，从而抑制CAC的发生发展。