胃腺癌肿瘤干细胞中异常表达的miRNA初筛及miR-199b-5p的初步研究

发布时间：2018-04-26 21:33

本文选题：胃腺癌 + Nanog　；参考：《河北大学》2017年硕士论文

【摘要】：胃癌是世界第二大致死恶性肿瘤,而其中胃腺癌又占95%以上。在中国,胃腺癌具有高发病率和高死亡率,病人的五年存活率非常低,因此胃腺癌是中国严重的公共卫生问题,也是中国医学急需解决的问题之一。本研究探究了 miR-199b-5p与干细胞标志物Nanog及胃癌肿瘤干细胞标志物CD44之间的关系,旨在深入了解miRNA对肿瘤以及肿瘤干细胞的调节作用,并且对胃腺癌肿瘤干细胞和肿瘤细胞进行转录组测序筛选出来差异表达的miRNA,为治疗胃腺癌提供新的分子靶标和研究思路。我们通过肿瘤细胞测序和生物信息学方法,预测出了 miR-199b-5p的靶向序列位于Nanog和CD44的3'UTR区域,可能存在抑制NANOG和CD44蛋白表达的情况。实验部分主要通过在胃腺癌细胞系MGC803中过表达miR-199b-5p以观察其对Nanog和CD44基因表达及蛋白翻译水平的影响。结果说明miR-199b-5p对Nanog没有影响,而CD44的表达在miR-199b-5p过表达的MGC803细胞中明显降低,这一结果提示miR-199b-5p可抑制CD44基因的表达。通过在MGC803细胞中过表达miR-199b-5p,观察miR-199b-5p对胃腺癌细胞生物学功能的影响。研究发现,miR-199b-5p上调能显著抑制胃腺癌细胞MGC803的增殖、迁移、侵袭及耐药程度。这些实验表明,miR-199b-5p可以作为抑癌基因,抑制肿瘤的发生、迁移、侵袭和耐药。miR-199b-5p的细胞生物学作用可能与其抑制CD44相关。我们的结论是:miR-199b-5p是一个潜在的对肿瘤干细胞标志物CD44具有调节作用的miRNA,通过抑制CD44从而抑制一系列肿瘤细胞生物学活性。这为胃腺癌肿瘤干细胞标志物CD44信号通路的研究拓宽了基础,也为肿瘤的诊断和治疗提供给了新的分子靶标。然而,值得注意的是,miR-199b-5p在我们的实验结果中表明可以抑制癌症的发生和发展,但是我们通过smallRNA测序结果来看,miR-199b-5p在类肿瘤干细胞中的表达远远高于肿瘤细胞。我们目前只能猜测这与细胞对抗肿瘤的自救效应或者ceRNA调控有关,而进一步的研究需要通过实验证实。
[Abstract]:Gastric cancer is the second leading malignant tumor in the world, in which gastric adenocarcinoma accounts for more than 95%. In China, gastric adenocarcinoma has a high incidence and high mortality, and the 5-year survival rate of patients is very low. Therefore, gastric adenocarcinoma is a serious public health problem in China and one of the urgent problems to be solved in Chinese medicine. This study explored the relationship between miR-199b-5p and stem cell marker Nanog and gastric cancer tumor stem cell marker CD44 in order to understand the regulatory effect of miRNA on tumor and tumor stem cells. The differentially expressed miRNAs were screened by transcriptome sequencing from gastric adenocarcinoma tumor stem cells and tumor cells, which provided a new molecular target and research idea for the treatment of gastric adenocarcinoma. By means of tumor cell sequencing and bioinformatics, we predicted that the target sequence of miR-199b-5p is located in the 3'UTR region of Nanog and CD44, which may inhibit the expression of NANOG and CD44. The effect of miR-199b-5p on the expression of Nanog and CD44 gene and protein translation was observed by overexpression of miR-199b-5p in gastric adenocarcinoma cell line MGC803. The results showed that miR-199b-5p had no effect on Nanog, but the expression of CD44 was significantly decreased in MGC803 cells with miR-199b-5p overexpression, which suggested that miR-199b-5p could inhibit the expression of CD44 gene. The effect of miR-199b-5p on the biological function of gastric adenocarcinoma cells was observed by overexpression of miR-199b-5pin MGC803 cells. It was found that the upregulation of miR-199b-5p could significantly inhibit the proliferation, migration, invasion and drug resistance of gastric adenocarcinoma cell line MGC803. These results suggest that miR-199b-5p may act as a tumor suppressor gene, inhibit tumorigenesis, migration, invasion and cell biology of drug-resistant .miR-199b-5p, and may be related to its inhibition of CD44. Our conclusion is that: miR-199b-5p is a potential regulator of CD44, a tumor stem cell marker, which inhibits the biological activity of a series of tumor cells by inhibiting CD44. The results provide a new molecular target for the diagnosis and treatment of gastric adenocarcinoma. However, it is worth noting that the expression of miR-199b-5p in tumor-like stem cells is much higher than that in tumor-like stem cells by smallRNA sequencing. We can only speculate that this is related to the cellular antitumor self-rescue effect or ceRNA regulation, and further research needs to be confirmed by experiments.
【学位授予单位】：河北大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R735.2

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