胃癌是我国常见肿瘤，YAP1在胃癌发生过程具备癌基因功能。我们最新发现miR-15a/16 可调控YAP1 表达，但miR-15a/16在临床胃癌标本中的表达水平、应用价值及在胃癌发生过程中的功能尚不清楚。本课题拟在已有实验基础上进行如下研究：1）探讨miR-15a/16 在胃癌中的的表达，分析与胃癌临床参数的相关性；研究miR-15a/16的表达下调机制；2)在胃癌细胞中过表达或沉默miR-15a/16，观察对细胞增殖及凋亡、集落形成能力、侵袭能力、细胞周期及对裸鼠皮下成瘤性的影响，从而揭示其功能；3）在胃癌细胞与标本中研究miR-15a/16 和YAP1 的表达关系，确定miR-15a/16结合YAP1的3'非翻译区识别位点并下调YAP1的表达；4）验证miR-15a/16其它可能靶基因（CCND1、CCND3和CCNE1），再用共转染试验证实miR-15a/16和可能靶基因的关系。

Gastric cancer is one of the most common malignancies worldwide and is the second most frequent cause of cancer related death. A variety of genetic and epigenetic aberrations underlie development abnormality of gastric cancer. In our previous study, we have validated that YAP1 (Yes-associated protein 1) is involved in gastric tumorigenesis and functions as an oncogene. Recently we found that miR-15a and miR-16 could down-regulate YAP1 expression in gastric cancer cell lines, AGS and MKN1. However, the expression level and function of miR-15a/16 together with its application value for clinical gastric cancer patients are still unclear...In this study, we will focus on the following issues on the former basic research. First, we will explore the expression level of miR-15a/16 in gastric cancer cell lines and clinical samples. We will evaluate the correlation between miR-15a/16 expression and other clinical parameters to check if miR-15a/16 could be a prognostic maker for gastric cancer. Also, the downregulation expression mechanism of miR-15a/16 in gastric tumors should be investigated. Second, we will overexpress or knockdown miR-15a/16 in gastric cancer cell lines to observe the influence of its expression on cell proliferation, monolayer colony formation ability, cell invasion ability, cell distribution in cell cycle, xenograft proliferation in animal model. Also, we would investigate the possible signaling pathways miR-15a/16 might be involved in. Third, we will evaluate the expression correlation between YAP1 and miR-15a/16 and confirm YAP1 could be regulated by miR-15a/16 through the seed region in its 3' untranslated region (3'UTR), which has two complementary binding sites for miR-15a/16 recognize. Finally, we will continue to investigate other putative target genes of miR-15a/16, such as cyclin D1, Cyclin D3 and Cyclin E1. ..All these will enrich the understanding on microRNAs in gastric cancer and the regulation mechanism of YAP1.