H-RAS RARE ALLELES IN BREAST CANCER SUSCEPTIBILITY

我们和其他人发现了罕见的H-ras VNTR的显著关联 然而，乳腺癌的等位基因，其生物学机制 这种关系仍不明朗。有两个假设可以解释这一点 协会。第一，罕见的H-ras VNTR等位基因是由 另一个关键基因的突变，因此是基因组的标志 不稳定，但不是遗传的直接责任 对癌症易感性。第二种可能性是稀有等位基因 通过其转录增强子直接参与癌变 效果。这里提出的研究旨在区分 这两个交替的假设。 我们最近对H-ras VNTR的小卫星变异重复(MVR)分析 表明大多数稀有等位基因的特征是内部异常 暗示DNA重排的序列。使用在 在加勒特研究人口的时候，我们将进一步探索 H-ras是遗传不稳定性的罕见等位基因，无论是在种系还是在 卡罗莱纳州乳腺癌研究中的更大人群中的肿瘤 (CBCS)。我们将确定种系H-ras稀有等位基因的关联性 在乳腺肿瘤中存在遗传不稳定性，通过测量 微卫星不稳定性和基因扩增，代际 CEPH家系和CBCs亲属H-VNTR的稳定性 乳腺癌患者罕见的等位基因，H-ras之间的交互作用罕见 乳房的等位基因与潜在的流行病学和环境因素 乳腺癌和罕见H-ras等位基因修饰对乳腺癌的影响 与已知癌症易感基因BRCA1和BRCA1相关的癌症 MSH2。 为了确定H-ras VNTR是否在 乳腺癌的发生发展，我们将评估其可能的功能。 这个区域作为转录增强子，决定了是否 调节作用由核因子-kappaB转录因子介导，并且 确定罕见的H-ras等位基因是否具有异常的调节功能 与它们共同的祖先等位基因进行比较。我们还将确定 常见等位基因在乳腺肿瘤中是否优先缺失 表现出杂合性的丧失，因为这将支持 这一区域处于致癌过程中。 最后，我们将把我们的分子技术曲目扩展到更多 充分描述H-ras VNTR的长度和内部结构 变种。通过提高我们对5‘序列的检测水平，并通过 开发3‘MVR方法，我们将获得完整的MVR序列 每个等位基因的全长，从而确保所有变异/罕见 检测到等位基因，特别是那些通过重组产生的等位基因。

We and others have found a significant association of rare H-ras VNTR alleles with breast cancer, however, the biological mechanism underlying this relationship remains unclear. Two hypotheses can explain this association. The first is that rare H-ras VNTR alleles are caused by a mutation in another critical gene and are therefore markers of genomic instability, but are not directly responsible for the inherited susceptibility to cancer. The second possibility is that rare alleles directly participate in carcinogenesis via their transcriptional enhancer effects. The studies proposed here are aimed at distinguishing between these two alternate hypotheses. Our recent minisatellite variant repeat (MVR) analyses of the H-ras VNTR show that most rare alleles are characterized by aberrant internal sequences suggestive of DNA rearrangements. Using technology developed in the Garrett study population, we will further explore the relationship of H-ras rare alleles to genetic instability, both in the germline and in tumors, in the larger population of the Carolina Breast Cancer Study (CBCS). We will determine the association of germline H-ras rare alleles with the presence of genetic instability in breast tumors, as measured by microsatellite instability and gene amplification, the inter-generational stability of the H-VNTR both in CEPH pedigrees and in relatives of CBCS breast cancer patients with rare alleles, interactions between H-ras rare alleles and potential epidemiologic and environmental factors for breast cancer and modification by rare H-ras alleles of the risk for breast cancer associated with the known cancer susceptibility genes, BRCA1 and MSH2. In order to determine whether the H-ras VNTR plays a direct role in the development of breast cancer, we will evaluate the putative function of this region as a transcriptional enhancer, determine whether the regulatory effects are mediated by NF-kappaB transcription factors, and determine if rare H-ras alleles have abnormal regulatory functions as compared with their common progenitor alleles. We will also determine whether common alleles are preferentially deleted in breast tumors which exhibit loss of heterozygosity since this would support a direct role for this region in the carcinogenic process. Finally, we will expand our repertoire of molecular techniques to more fully characterize the H-ras VNTR for both length and internal structural variation. By increasing our level of detection of 5' sequences and by developing 3' MVR methodologies, we will obtain complete MVR sequence for the entire length of each allele, thus ensuring that all variant/rare alleles are detected, especially those which arose by recombination.