幽门螺杆菌致长爪沙鼠胃癌模型高发群体的选育及发病机制研究

Helicobacter pylori (Hp) is a carcinogen of human gastric cancer classified Group I by International Agency for Research on Cancer (IARC). The Mongolian gerbil harbors the most similar animal model of Hp-induced gastric cancer in humans. However, the incidence of this model is a bit low (about 40%). Scientific researches indicated that genetic factors played a vital role in Hp-induced gastric cancer. Our previous studies have confirmed that a biological characteristic of gerbil could be fixed by selectively breeding. Thus, we hypothesized that the prone of Hp-induced gastric cancer in gerbil was mainly affected by genetic factor. Selective breeding could increase or decrease the successful modeling ratio; and the gastric cancer related genes would exist in such gerbil groups. In this project, we will infect 2 outbred populations and 2 inbred strains of gerbils using Hp and selectively breed the litters of sensitive and resistant gerbils separately by identifying and ascertaining the models. Therefore, we could get two different gerbil groups after several generations. Using the tissue samples from the sensitive and resistant groups of Hp-induced gastric cancer, the disease-related genes would be screened by whole genome re-sequencing and RNA sequencing. The mutations and different expression levels of these genes also would be analyzed in each pathological stages of gastric cancer. The function of the selected genes in pathological stages could be validated by biological information and molecular biological assays to primarily reveal the mechanism of every stage in Hp-induced gastric cancer. This research will newly establish the groups of sensitive and resistant Hp infected gastric cancer in gerbils and provide a new animal model for mechanism studies and drug trials in Hp-induced gastric cancer.

幽门螺杆菌（Hp）是人类胃癌Ⅰ类致癌物，长爪沙鼠是与人胃癌病理进程最接近的Hp感染胃癌模型，但其胃癌发生率却较低。研究显示人感染Hp胃癌与遗传组成相关。我们前期证明通过定向培育可以将沙鼠的某一性状固定下来。据此提出假说：长爪沙鼠Hp感染易发胃癌是由遗传因素决定的，通过定向培育可提高或降低胃癌成模率，并有相关差异基因存在。本课题拟利用自行培育的2个封闭群和2个近交系长爪沙鼠感染Hp，模型鉴定后分别繁殖敏感和抵抗后代，经多代选育获得长爪沙鼠Hp感染胃癌高发和低发2个模型群体。以此为材料，采用基因组重测序和转录组测序等技术发现胃癌相关基因，分析胃癌发生过程中各病理阶段基因突变和表达差异，通过生物信息学和分子生物学方法筛选验证这些基因在各病理阶段的作用，初步揭示Hp感染致胃癌的发生机制。本研究将率先在国际上建立长爪沙鼠Hp感染致胃癌高发和低发群体，为Hp诱发胃癌发生机制研究和药物试验提供支撑。

幽门螺杆菌（Hp）是人类胃癌Ⅰ类致癌物，长爪沙鼠能够模拟人胃癌病理进程并具有类似的免疫反应，被认为是最为理想动物模型，但其存在缺乏活体检测方法、胃癌发生率低以及发病机制不清等不足之处。本研究首先建立两种长爪沙鼠Hp活体检测方法（胃液巢式PCR和呼气试验）并利用菌体分离培养、脲酶实验和免疫组化等进行相互印证。在此基础上，利用自行培育的1个封闭群和2个近交系长爪沙鼠群体感染Hp，模型鉴定后繁殖Hp敏感后代，经多代选育获得长爪沙鼠Hp感染胃癌高发群体。现已经选育至第七代，群体规模达到80余只，Hp感染率已经达到100%。以此为材料，对长爪沙鼠进行不同时间的Hp感染，对感染不同时间且发生不同病理变化的沙鼠胃组织进行基因组重测序，发现胃癌相关基因，分析胃癌发生过程中各病理阶段基因突变（测序工作将于1月完成）。此外，本研究还利用动物模型，结合细胞实验，探究了Hp裂解液长期刺激对胃上皮细胞功能及TLR敏感性的影响。研究发现持续的Hp裂解液刺激可促进胃上皮细胞增殖，抑制细胞自噬和凋亡。该过程通过Nod1-NF-kB/MAPK-ERK/FOXO4通路实现。在Hp引起的胃病变过程中，Hp裂解液起到了“帮凶”的作用。同时Hp裂解液短期刺激能使部分TLRs和炎性细胞因子激增。而持续暴露于Hp裂解液后，人胃上皮细胞TLRs的敏感性下降，炎性细胞因子出现耐受。过程可通过TLR6/PI3K/NF-κB轴实现。本研究率先在国际上建立长爪沙鼠Hp感染致胃癌高发群体，为Hp诱发胃癌发生机制研究和药物试验提供支撑。