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

描述（由申请人提供）：鉴定导致常见（非孟德尔）乳腺癌形式的基因将使早期识别高危个体和定制预防和治疗方案成为可能。这是一个极其困难的问题，因为常见形式的乳腺癌的遗传风险是多基因-基因相互作用的结果，每个基因对风险的贡献很小。标准方法（如遗传关联研究）在检测潜在风险的许多基因-基因相互作用方面能力不足。我们提出了一种基于表型的方法来预测常见形式乳腺癌的潜在风险的基因-基因相互作用。该方法是基于观察到细胞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，这使得绘制导致这种表型的基因-基因相互作用成为可能。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)使用酿酒酵母进行全基因组筛选，寻找与人类乳腺癌肿瘤抑制基因同源物协同作用的突变，从而赋予其对DNA损伤的敏感性；ii)在这些已确定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。

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.