青海藏族胃癌组织和循环microRNA的表达及特异性分子标志物的筛选

There is the highest Incidence rates and mortality of gastric cancer in Qinghai Province. Tibetan population is the second only to the Han in Qinghai province. But the incidence rates of gastric cancer of Tibetan was significantly higher than Han , and the average age of the gastric cancer occurrence is younger compared to the others. The study showed that detection rate of gastric cancer in the native Tibetan is higher than the settlers who moved here more than 25 years. Infection rates of H pylori had no difference among different ethnic groups. These results indicate that the geographical environment, diet habit, the infection rates of H pylori cannot be the reason of different incidence rates of gastric cancer between Tibetan and Han. Tibetan has strict customs of intermarriage, shows relatively independent genes, studies have shown that some genes expression are differences between Tibetan and Han. Therefore, in this study the expression of microRNA in native Tibetan and the Han gastric cancer tissues, normal gastric mucosa and plasma of cancer patients and healthy will be detected by microRNA hybridization and real time-PCR. Combined with statistical analysis , we can find if there are any different expression of microRNA in gastric cancer between Tibetan and Han which has been reported; if there are any differences of microRNA in the gastric tissue and plasma; find out the pathogenesis of higher incidence rate and specific circulating microRNA will be selected as biomarkers of the Tibetan gastric cancer.

青海省胃癌发病率及死亡率均居全国之首，藏族是青海省人口仅次于汉族的第二大民族，而藏族人群胃癌发病率明显高于汉族,且平均发病年龄较汉，回族为低，调查显示青藏高原地区世居藏族胃癌检出率高于25年以上的移居者，但HP感染率各民族间无差异。事实表明地理环境、饮食习惯、HP感染率均不能解释藏汉族胃癌发病率的差异。藏族有较严格不通婚习俗,保持了相对的基因独立，有研究表明藏族与汉族部分基因确实存在差异。因此，本课题采用microRNA芯片杂交和荧光定量PCR技术，系统检测青海世居藏族和汉族人群中胃癌组织、正常胃粘膜和循环血液中microRNA的表达量，结合统计学分析，阐明世居藏族与汉族胃癌组织及循环中microRNA的表达是否存在民族差异，明晰胃癌组织与外分泌到血浆中microRNA的表达是否一致，从分子水平探讨高原藏族胃癌高发的机制并且筛选出藏族胃癌特异性循环microRNA作为藏族胃癌早期筛检的分子标志物。

青海省胃癌发病率及死亡率均居全国之首，本省人口仅次于汉族的藏族人群胃癌发病率明显高于汉族，且藏族有较严格的异族之间不通婚习俗,所以保持了相对的基因独立，有研究表明藏族与汉族之间某些基因确实存在如多态性等方面差异。因此，本项目收集了藏族和汉族肠型、弥漫型胃癌患者和健康人群的血浆、冰冻新鲜和石蜡包埋的癌和癌旁组织及正常胃粘膜进行不同分组间microRNA表达谱的芯片检测，并对差异表达microRNA中的6条进行了较大样本量的qPCR验证。然后根据已验证的6条microRNA的靶基因预测分析，选出其调控蛋白CCND1,DENND2D和MAPK1在组织芯片上进行了免疫组织化学的染色。结果显示标本的保存方式不同（新鲜冰冻或石蜡包埋）会导致microRNA表达谱的改变，因此用福尔马林固定石蜡包埋组织中microRNA表达的绝对值来用于研究，结论可能不准确，但配对的新鲜冰冻和福尔马林固定石蜡包埋组织中microRNA的表达有很高的相关性，所以福尔马林固定石蜡包埋样本可用于microRNA表达相对关系的研究；在弥漫型胃癌组织和血浆中部分microRNA的表达量呈相反趋势，且患者血浆中的let-7a、let-7b、let-7c的过高表达可以作为弥漫型胃癌诊断的分子标志；在肠型和弥漫型胃癌和癌旁组织中藏族和汉族的microRNA的表达无显著性差异，提示microRNA在胃癌的发生发展中的作用在不同民族之间无差异；在lauren分型中，肠型和弥漫型胃癌组织中microRNA表达谱呈显著性差异表达，提示二者细胞来源，生长速度，浸润转移的能力，靶向药物治疗的效果等等的不相同可能是由于microRNA表达不同引起，这对不同分型胃癌的靶向治疗提供新的方向及思路。