Phenotype-based approach to find gene interactions underlying breast cancer risk

描述(由申请人提供)：确定导致常见(非孟德尔)乳腺癌的基因将有助于及早识别有风险的个人并制定预防和治疗方案。这是一个极其困难的问题，因为常见乳腺癌的可遗传风险是多个基因-基因相互作用的结果，每个单独的基因对风险只有很小的贡献。标准方法(例如遗传关联研究)不足以检测潜在风险的许多基因-基因相互作用。我们提出了一种基于表型的方法来预测常见乳腺癌潜在风险的基因-基因交互作用。该方法基于这样的观察，即细胞DNA损伤反应(乳腺癌易感性的中间表型)中的缺陷是可遗传的，从而有可能定位导致这种表型的基因-基因相互作用。我们假设，控制DNA损伤敏感性的基因-基因相互作用在酵母和人类之间是保守的。我们的方法将是：i)使用酵母S.cerevisiae在全基因组范围内筛选与人类乳腺癌抑癌基因的同源物协同作用的突变，以增强对DNA损伤的敏感性；以及ii)在这些已知的合成相互作用中筛选那些在人类乳腺上皮细胞中保守的相互作用。 具体目标1：在酿酒酵母中进行全基因组筛选，以确定与人乳腺癌抑癌基因的酵母同源物协同作用的突变，从而产生对DNA损伤的敏感性。 具体目的2：利用RNA干扰技术，构建稳定下调乳腺肿瘤抑制基因的人乳腺上皮细胞系。 具体目标3：确定在酵母中发现的遗传相互作用是否在人类乳房上皮细胞中保守。 项目简介：确定一个人罹患癌症的风险可能在以下几个方面对公众健康产生巨大影响：i)确定乳腺癌的风险等位基因将促进根据个人风险状况量身定做的具有成本效益的癌症筛查计划；ii)确定风险等位基因将使确定谁将从预防策略中受益最大；iii)确定风险等位基因将阐明疾病的病理生理机制，导致有针对性的治疗或化学预防药物，如现有的靶向激素和抗体治疗。

DESCRIPTION (provided by applicant): Identification of genes contributing to common (non-Mendelian) forms of breast cancer would enable early identification of individuals at risk and tailoring of prevention and treatment regimens. This is an extremely difficult problem since heritable risk for common forms of breast cancer is a result of multiple gene-gene interactions, with each individual gene making only a minor contribution to risk. Standard approaches (e.g. genetic association studies) are underpowered to detect the many gene-gene interactions underlying risk. We propose a phenotype-based approach to predict gene-gene interactions underlying risk for common forms of breast cancer. The approach is based on the observation that defects in the cellular DNA damage response (an intermediate phenotype for breast cancer susceptibility) are heritable, making it possible to map gene-gene interactions responsible for this phenotype. We hypothesize that gene-gene interactions governing sensitivity to DNA damage are conserved between yeast and humans. Our approach will be to: i) use the yeast S. cerevisiae to perform genome-wide screens for mutations that synergize with homologs of human breast cancer tumor suppressor genes to confer sensitivity to DNA damage, and ii) to screen amongst these identified synthetic interactions for those that are conserved in human mammary epithelial cells. Specific Aim 1: Perform genome-wide screens in S. cerevisiae to identify mutations that synergize with yeast homologs of human breast cancer tumor suppressor genes to produce sensitivity to DNA damage. Specific Aim 2: Using RNA interference, build human mammary epithelial cell lines that have stable knock- down of breast tumor suppressor genes. Specific Aim 3: Determine if genetic interactions discovered in yeast are conserved in human breast epithelial cells. PROJECT NARRATIVE: Determination of an individual's risk for developing cancer could have tremendous public health impact in several ways: i) identifying risk alleles for breast cancer will facilitate cost-effective cancer screening programs tailored to an individual's risk profile; ii) identifying risk alleles will allow identification of women who will most benefit from prevention strategies; iii) identifying risk alleles will elucidate the pathophysiology of the disease, leading to targeted therapeutics or chemoprevention agents such as existing targeted hormonal and antibody therapies.