IGF-1R信号通路参与循环肿瘤细胞EMT调控与胃癌转移的关系

Gastric cancer is a very common type of digestive tract cancer. CTCs (circulating tumor cells) plays a critical role in gastric cancer metastasis. While IGF-1R pathway is widely involved in tumor proliferation, anti-apoptosis and EMT, but its effect mechanisms on CTCs are still unknown. Our previous studies suggested that overexpression of IGF-1R can promote gastric cancer cell proliferation and metastasis,CTCs in gastric cancer undergo EMT, and mesenchymal phenotype of CTCs is significantly correlated with stage and distant metastasis. It is postulated that IGF-1R pathway boost CTCs undergo EMT is one of the important mechanism of gastric cancer metastasis. To make it clear,we will recruit patients with previously untreated resectable gastric cancer, peripheral blood samples are collected from participants preoperatively and 12w postoperatively to detect CTCs and its phenotype of mesenchymal or epithelial,serum IGF-1 level is detected at the same time, and the expression of IGF-1R and EMT related genes in gastric cancer tissue are also measured, in order to study the relationship between those markers with cancer stage and metastasis. Then we compare the expression of genes associated with EMT and gastric cancer cell characteristics between activated and inhibited IGF-1R pathway, establish gastric cancer xenograft mouse model and verify the effects of IGF-1R pathway on CTCs in gastric cancer metastasis.

胃癌是常见的消化道恶性肿瘤，循环肿瘤细胞（CTCs）是胃癌转移的重要原因。胰岛素样生长因子-1受体（IGF-1R）通路广泛参与肿瘤的增殖、抗凋亡及上皮-间质转化（EMT），但该通路对胃癌CTCs的影响及机制尚未清楚。前期研究显示过表达IGF-1R促进胃癌细胞的增殖及转移；胃癌CTCs存在EMT现象且间质型CTCs与肿瘤分期及远处转移显著相关。我们推测IGF-1R通路促进胃癌CTCs EMT可能是胃癌转移的重要机制之一。因此，本项目以初治可切除胃癌病人为研究对象，动态检测病人术前及术后12周血清IGF-1及外周血CTCs并分型；检测胃癌组织磷酸化IGF-1R、EMT相关基因的表达；研究上述指标与胃癌分期及转移相关性；利用胃癌细胞模型研究激活及阻断IGF-1R通路前后胃癌细胞生物学行为及EMT相关基因表达变化；通过裸鼠模型进一步验证IGF-1R通路的激活对胃癌CTCs转移的影响。

胃癌循环肿瘤细胞（CTCs）的临床意义及调控机制尚未明确，IGF-1R信号通路可能通过EMT机制参与胃癌CTCs调控并促进远处转移。本项目采用CanpatrolTM技术平台对60例进展期胃癌患者术前及术后12周外周血CTCs进行富集和分离，多重原位mRNA杂交技术对 CTCs 进行鉴定、分型并计数；分析 CTCs 及其亚型与患者临床病理特征关系；检测胃癌患者术前外周血清IGF水平，检测胃癌组织IGF-1R及EMT相关基因表达情况；利用细胞模型进一步研究IGF-1R信号通路对胃癌细胞EMT调控机制。结果：基于上述检测技术，将CTCs分为上皮型、混合型及间质型3类；总CTCs检出率90.7%，上皮型CTCs检出率68.5%，混合型CTCs检出率74.1%，间质型CTCs检出率61.1%；年龄≤60岁的胃癌患者外周血CTCs总数及混合型CTCs显著低于年龄＞60岁的胃癌患者，脉管侵犯阳性胃CTCs总数显著高于脉管侵犯阴性胃癌，P＜0.05；Lauren肠型胃癌中CTCs总数及间质型CTCs数量显著高于弥漫型胃癌，P＜0.05；CTCs及其亚型数量与病理分期无显著相关性，但当按Lauren分型进行分层后，肠型胃癌组上皮型CTCs数量与病理分期显著相关；CTCs及其亚型数量与性别、神经侵犯、肿瘤部位、浸润深度、淋巴结转移无显著相关，P＞0.05；上皮型CTCs阴性组病例总生存时间显著低于阳性组（P=0.017）；肠型胃癌生存预后显著好于弥漫型胃癌，P=0.035；因入组病例远处转移或随访过程出现远处转移病例数较少，本研究目前尚无法临床验证CTCs及与远处转移或术后复发的关系；胃癌患者术前外周血清IGF水平与临床病理特征无显著相关性；IGF-1R在胃癌组织的表达显著高于癌旁组织，P<0.05；细胞模型实验显示IGF-1R信号通路沉默后胃癌细胞增殖转移能力下降，而IGF-1R信号通路激活则促进胃癌细胞的增殖转移能力；IGF-1R信号通路的抑制或激活与EMT相关蛋白的表达变化无明显相关性。结论：Lauren肠型胃癌总CTCs及间质型CTCs数量比弥漫型胃癌显著增加并与病理分期和预后相关，提示CTCs检测可作为肠型胃癌的预后监测指标；胃癌CTCs存在EMT现象并广泛表达IGF-1R，细胞模型实验提示IGF-1R信号通路可能在胃癌CTCs EMT中发挥作用，但具体机制还需进一步研究证实