辅助性T细胞17与结直肠肿瘤细胞的交叉对话：肿瘤发生和上皮间质转化

The T helper 17 subset (Th17) has been found in augmented the invasion of colorectal cancer (CRC) recently, however, the underlying molecular mechanisms as well as the relationship between Th17 cells and tumorigenesis remain elusive. Our preliminary studies showed: ① The density of Th17 cells in the normal epithelium, adenoma, early CRC and advanced CRC tissues had a significant ascent tendency; ② The density of intratumoral Th17 cells were associated with poor survival in CRC patients; ③ The density of intratumoral Th17 cells negatively correlated with E-cadherin expression in advanced CRC; IL-17 mediated tumor-promoting role involved a direct effect on epithelial-mesenchymal transition (EMT) through intranuclear enrichment of Snail by activating the AKT pathway. Taking into account the potential crosstalk between immune cells and tumor cells, we aim: ① to ex vivo polarize and culture human and mouse Th17 cells; ② to systematically investigate the promoting role of Th17 cells on tumorigenesis and tumor progeression, as well as the feedback regulation effect of tumor cells on Th17 cell polarization and characteristics using phosphoprotein antibody and PCR microarrays in both adenoma and adenocarcinoma cells; ③ to investigate the positive feedbank loop between Th17 cells and tumor cells with EMT features in vitro and in vivo. Thus, the network diagram of crosstalk between Th17 cells and CRC cells could be well demonstrated.

近年发现辅助性Th17细胞（Th17细胞）与结直肠癌侵袭转移相关，但其具体机制及Th17细胞与肠癌发生关系尚不清楚。我们前期研究示：①"正常-腺瘤-早期癌-进展期癌"这一经典的肠癌发病过程中，Th17细胞密度逐渐上升；②肠癌组织Th17细胞密度是手术患者预后不良的独立风险因素；③肠癌组织Th17细胞密度与肿瘤E-钙粘素表达明显负相关；IL-17通过激活AKT诱导Snail核内聚集，促进上皮间质转化（EMT）和肠癌侵袭。考虑到免疫细胞、肿瘤细胞及其EMT行为之间可能存在交叉对话，我们拟：①体外诱导扩增Th17细胞；②在结肠腺瘤及腺癌细胞中，体内外实验并结合磷酸化抗体芯片和PCR芯片，研究Th17细胞对肿瘤发生发展的促进以及肿瘤细胞对Th17细胞分化和表型的反馈调节；③体内外实验探讨Th17细胞与肠癌EMT行为间互相促进的正反馈环路。由此描绘出Th17细胞与结直肠肿瘤细胞交叉对话的网络图。

研究背景：近年发现辅助性Th17 细胞（Th17 细胞）与多种肿瘤进展相关。在不同免疫背景下，Th17细胞存在促瘤/抑瘤的双向作用。有研究提示Th17细胞与结直肠癌侵袭转移相关，但其具体机制尚不清楚。.研究目的：阐明Th17 细胞在结直肠癌侵袭转移中扮演的角色及相关分子机制。.主要研究结果：①Th17细胞及其主要细胞因子IL-17在“正常结直肠上皮-腺瘤-腺癌”这一经典的肠癌发病过程呈逐渐上升趋势；体内外研究显示Th17细胞及IL-17可促进结直肠癌生长和侵袭。②癌组织中Th17细胞密度与患者预后负相关，且与肿瘤细胞E-cadherin表达水平呈明显负相关；分选Th17细胞与肿瘤细胞共培养，体内外研究发现Th17细胞及IL-17可诱导结直肠癌细胞发生上皮间质转化（EMT）。③磷酸化蛋白质芯片检测发现PI3K-AKT-Snail信号通路在IL-17调控EMT的过程中起着关键作用；采用IL-17mAb 干预可逆转Th17细胞对EMT行为的促进，说明Th17对结直肠癌EMT的促进依赖于IL-17；Th17细胞及IL-17对EMT行为的促进作用均可被AKT磷酸化抑制剂LY294002逆转。.结论及意义：Th17细胞通过活化IL17-PI3K-AKT-Snail信号通路，诱导结直肠癌细胞发生EMT，从而促进肿瘤侵袭转移。该成果有望作为结直肠癌预防和靶向干预的靶点。