Department of Neurosurgery, The Affiliated Hospital of Qingdao University, Qingdao, 266003, People's Republic of China.
Department of Gastroenterology, The Affiliated Hospital of Qingdao University, No. 16, Jiangsu Road, Qingdao, 266003, Shandong Province, People's Republic of China.
J Exp Clin Cancer Res. 2020 Sep 29;39(1):202. doi: 10.1186/s13046-020-01677-w.
Globally, colorectal cancer (CRC) affects more than 1 million people each year. In addition to non-modifiable and other environmental risk factors, Fusobacterium nucleatum infection has been linked to CRC recently. In this study, we explored mechanisms underlying the role of Fusobacterium nucleatum infection in the progression of CRC in a mouse model.
C57BL/6 J-Adenomatous polyposis coli (APC) Min/J mice [APC (Min/+)] were treated with Fusobacterium nucleatum (10 cfu/mL, 0.2 mL/time/day, i.g., 12 weeks), saline, or FadA knockout (FadA-/-) Fusobacterium nucleatum. The number, size, and weight of CRC tumors were determined in isolated tumor masses. The human CRC cell lines HCT29 and HT116 were treated with lentiviral vectors overexpressing chk2 or silencing β-catenin. DNA damage was determined by Comet assay and γH2AX immunofluorescence assay and flow cytometry. The mRNA expression of chk2 was determined by RT-qPCR. Protein expression of FadA, E-cadherin, β-catenin, and chk2 were determined by Western blot analysis.
Fusobacterium nucleatum treatment promoted DNA damage in CRC in APC (Min/+) mice. Fusobacterium nucleatum also increased the number of CRC cells that were in the S phase of the cell cycle. FadA-/- reduced tumor number, size, and burden in vivo. FadA-/- also reduced DNA damage, cell proliferation, expression of E-cadherin and chk2, and cells in the S phase. Chk2 overexpression elevated DNA damage and tumor growth in APC (Min/+) mice.
In conclusion, this study provided evidence that Fusobacterium nucleatum induced DNA damage and cell growth in CRC through FadA-dependent activation of the E-cadherin/β-catenin pathway, leading to up-regulation of chk2.
全球范围内，每年有超过 100 万人罹患结直肠癌（CRC）。除了不可改变的和其他环境风险因素外，最近有研究表明具核梭杆菌感染与 CRC 有关。在本研究中，我们在小鼠模型中探索了具核梭杆菌感染在 CRC 进展中的作用机制。
C57BL/6J-腺瘤性结肠息肉病（APC）Min/J 小鼠（APC（Min/+））接受具核梭杆菌（10cfu/mL，0.2mL/次/天，灌胃，共 12 周）、生理盐水或 FadA 敲除（FadA-/-）具核梭杆菌处理。分离肿瘤块以确定 CRC 肿瘤的数量、大小和重量。用慢病毒载体过表达 chk2 或沉默 β-连环蛋白处理人 CRC 细胞系 HCT29 和 HT116。彗星试验和 γH2AX 免疫荧光和流式细胞术检测 DNA 损伤。通过 RT-qPCR 检测 chk2 的 mRNA 表达。Western blot 分析检测 FadA、E-钙黏蛋白、β-连环蛋白和 chk2 的蛋白表达。
具核梭杆菌处理促进 APC（Min/+）小鼠 CRC 中的 DNA 损伤。具核梭杆菌还增加了处于细胞周期 S 期的 CRC 细胞数量。FadA-/-减少体内肿瘤数量、大小和负担。FadA-/-还降低了 DNA 损伤、细胞增殖、E-钙黏蛋白和 chk2 的表达以及 S 期细胞数量。chk2 的过表达增加了 APC（Min/+）小鼠的 DNA 损伤和肿瘤生长。
总之，本研究提供了证据表明，具核梭杆菌通过 FadA 依赖性激活 E-钙黏蛋白/β-连环蛋白通路诱导 CRC 中的 DNA 损伤和细胞生长，导致 chk2 上调。
