TGF-Beta/Smads信号通路调控基因多态性与乳腺癌遗传易感性及其机制研究

Defect or deficiency in the TGF-β/Smads pathway has been proved to be closely associated with the occurrence of breast cancer. Researchers both in China and abroad, using candidate gene approach and candidate signal pathway approach, found that genetic polymorphisms of the TGF-β/Smads pathway’s regulatory genes can affect susceptibility to breast cancer. However, the functional loci in the area of the SNPs are yet to be found, and their mechanisms still elude us. Our prior research in the polymorphisms of the regulatory sequence of the 5’ terminal of TGFB1 showed a decline in risk of breast cancer by 24% and 32% respectively when carrying a minor loci of SNP rs1800469 (C>T) or Indel rs11466313 (AGG/Del); Carriers of the haplotype Del-T have their risk of breast cancer reduced by 69%; Bioinformatics suggest that rs11466313 (AGG/Del) may very likely be a functional loci, but its mechanisms require further research. Our project here proposes a plan using a series of methods such as case-control study and precise positioning to determine 3--5 potential functional loci, and explore their mechanism to affect susceptibility of breast cancer, in the hope that it might help provide theoretical support for assessment and prediction of breast cancer risk.

TGF-β/Smads信号通路异常与乳腺癌发生与发展密切相关。国内外研究人员通过候选基因策略及候选信号通路策略，发现TGF-β/Smads信号通路调控基因的遗传多态性可以影响乳腺癌的易感性。但是，对于易感SNP位点所在区域的功能性位点及作用机制尚不清楚。我们前期对TGFB1基因5’端调控区的多态性研究发现：SNP rs1800469（C>T）、Indel rs11466313（AGG/Del）次要等位基因携带者，发生乳腺癌的风险分别降低24%和32%；单体型Del-T携带者，发生乳腺癌的风险降低69%；生物信息学提示rs11466313（AGG/Del）很可能是一个功能性位点。本课题拟通过病例-对照分析、精细定位等方法，确定TGF-β/Smads信号通路调控基因中,与乳腺癌发生风险关联性较强的3--5个功能性变异位点，并进行深入机制探讨，为乳腺癌的风险预测提供理论依据。

肿瘤是遗传因素和环境因素共同作用的结果。在遗传水平，单核苷酸多态性（SNP）和短序列插入/缺失等常见多态性，可以影响肿瘤发生风险。本课题研究了TGFB1、SNAI1、TWIST1、CDH1基因遗传多态性与乳腺癌、卵巢癌、子宫内膜癌易感性的关联性、功能预测及作用机制。应用多因素逻辑回归等统计学方法分析候选位点与肿瘤发生风险的相关性；应用基因型填补（imputation）和表达数量性状基因座（eQTL）分析，对基因型-表型关联性进行预测；利用多种生物信息学在线工具对肿瘤易感性多态位点进行功能注释；采用一系列功能学实验，分析肿瘤易感性多态位点的功能及作用机制。重要研究结果如下：① TGFB1启动子区域的多态性位点rs11466313 (-2389_-2391 AGG/Del)次要等位基因Del结合转录因子FAM98B和HSP90B的能力降低，从而影响TGFB1表达量及乳腺癌易感性；②SNAI1 rs6125849，TWIST1基因rs4721746、rs4721745多态影响乳腺癌/卵巢癌的发病风险；③CDH1基因rs13689、rs10431923、rs10431924是影响子宫内膜癌发病风险的独立因素。本科学研究的应用前景：对TGFB1、SNAI1、TWIST1、CDH1影响肿瘤易感性的变异位点检测，有利于科学评价女性罹患乳腺癌、卵巢癌、子宫内膜癌的风险，筛查高危人群，及早采取干预措施，对降低这些肿瘤的发病率具有重要意义。.另外，本课题研究了细胞外ATP影响乳腺癌细胞侵袭和转移的机制，首次揭示ATP-P2Y2-β-catenin轴在乳腺癌侵袭和转移方面的作用；并揭示细胞外ATP通过上调肿瘤细胞的S100A4从而促进其伪足形成及迁移，还能增强肿瘤细胞激活成纤维细胞的能力，转化后的成纤维细胞能够大量分泌S100A4，从而反馈性促进肿瘤细胞的转移。这些研究结果为乳腺癌的靶向治疗提供科学依据。.本基金资助培养博士研究生3名、本科生2名。发表SCI论文4篇（累计影响因子15.503）：Cancer Letters 2018, 430: 1-10；Cancer Science 2017, 108: 1318–1327；Oncology Report 2018, 40: 3573-35843； Oncology Letters 2018, 16: 6868-6878.