转录因子Yin Yang-1在胰腺癌中发挥抑癌作用的机制研究

Yin Yang-1 (YY1), as a nuclear transcription factor with double transcriptional activity, is aberrantly expressed in several tumor types. We first reported the relationship between YY1 and pancreatic cancer and found that the expression of YY1 in pancreatic cancer was higher compared with their adjacent non-tumorous tissues and normal pancreas tissues. However, the patients with high level overexpression of YY1 had better outcome than those with low level overexpression. In vivo and in vitro experiments also confirmed that YY1 plays the tumor suppressor role in pancreatic cancer by pro-apoptosis, inhibiting proliferation, invasion and metastasis. However, How and by what mechanisms for YY1 to perform such tumor suppressor role? Recently, we found that YY1 could regulate key genes expression in various signal pathways. So we are proposing that YY1 as a transcription factor with double transcriptional activity, regulates key genes transcription on upstream of signal pathways, then cascade to suppress tumorgenesis. This study will try to identify YY1 binding DNA sequence by ChIP-Seq, combined with CO-IP to identify YY1 binding protein complex, aiming to elucidate its direct mechanism and downstream signal pathways.

Yin Yang-1（YY1）在多数人类肿瘤中表达异常，其作为具有双重转录活性的核转录因子参与肿瘤的发生发展。前期我们率先报道了YY1与胰腺癌的关系，发现YY1在胰腺癌中高表达，然而高水平的YY1过表达却与胰腺癌病人预后良好相关；体内外实验证实YY1在胰腺癌中发挥促凋亡、抑制增殖、侵袭与转移的抑癌作用，部分研究结果发表在Molecular Cancer杂志；然而YY1通过何种机制在胰腺癌中发挥抑癌作用？我们通过数字化基因表达谱测序发现YY1显著调节多个关键信号通路基因表达；因此我们设想：YY1作为具有双重转录活性的转录因子，在信号通路上游调节关键基因的转录表达，通过级联放大作用发挥强而广泛的抑癌作用。本课题将在胰腺癌中，采用ChIP-Seq技术明确YY1结合的DNA序列，辅之以CO-IP的方法分离、鉴定出YY1与DNA结合的蛋白复合体，旨在从源头阐明YY1直接作用机制和下游信号通路。

Yin Yang-1（YY1）在多数人类肿瘤中表达异常，其作为具有双重转录活性的核转录因子参与肿瘤的发生发展。前期研究中我们率先报道了YY1与胰腺癌的关系，发现YY1在胰腺癌中高表达，然而高水平的YY1过表达却与胰腺癌病人预后良好相关；体内外实验证实YY1在胰腺癌中发挥促凋亡、抑制增殖、侵袭与转移的抑癌作用；然而YY1通过何种机制在胰腺癌中发挥抑癌作用？我们通过DGE测序发现YY1显著调节多个关键信号通路基因表达；因此设想：YY1作为具有双重转录活性的转录因子，在信号通路上游调节关键基因的转录表达，通过级联放大作用发挥强而广泛的抑癌作用。在本项目中，我们首先采用ChIP-Seq技术及生信分析获取了以下三个方面的信息：①YY1结合序列基序（binding sequence motif）；②转录相关区域定位；③得到43个“峰”（peak）关联基因，及关联基因的GO注释及Pathway分析。然后对YY1结合序列motif及peak关联基因进行验证及功能分析，结合CO-IP辅助分离、鉴定出协助YY1与DNA结合的蛋白复合体。在这43个peak关联基因中，我们已筛选、验证出8个YY1直接调控的、在胰腺癌中发挥重要作用的靶基因，分别是：SOX2OT、miR-30a、miR548t、BAX、CDKN3、FER、TPPP及ROBO1。结论：本项目鉴定了一批YY1直接调控的、在胰腺癌中发挥重要作用的靶基因及其下游信号通路。提示YY1与其靶基因及下游关键信号分子可能成为胰腺癌诊断、预后的新指标及潜在的治疗靶点。