H-RAS RARE ALLELES IN BREAST CANCER SUSCEPTIBILITY

我们和其他人已经发现罕见的H-ras VNTR 然而，与乳腺癌相关的等位基因， 这种关系仍然不清楚。有两种假设可以解释这一点 协会第一种是罕见的H-ras VNTR等位基因是由一种 另一个关键基因的突变，因此是基因组 不稳定，但不直接负责继承 对癌症的易感性。第二种可能是稀有等位基因 通过其转录增强子直接参与致癌作用 方面的影响.这里提出的研究旨在区分 这两种假设。 我们最近对H-ras VNTR进行了小卫星变异重复（MVR）分析， 表明大多数罕见等位基因的特征是异常的内部 暗示DNA重排的序列使用的技术开发于 在加勒特研究人群中，我们将进一步探讨 H-ras罕见等位基因遗传不稳定性，无论是在生殖系和 在卡罗莱纳乳腺癌研究的较大人群中， （CBCS）。我们将确定生殖系H-ras稀有等位基因与 与乳腺肿瘤中存在遗传不稳定性有关， 微卫星不稳定性和基因扩增，代际 CEPH家系和CBCS亲属中H-VNTR的稳定性 乳腺癌患者罕见等位基因，H-ras之间的相互作用罕见 乳腺癌的等位基因和潜在的流行病学和环境因素 乳腺癌和罕见H-ras等位基因对乳腺癌风险的修饰 与已知的癌症易感基因BRCA 1和 MSH2。 为了确定H-ras VNTR是否在细胞凋亡中起直接作用， 乳腺癌的发展，我们将评估假定的功能， 该区域作为转录增强子，决定是否 调节作用由NF-κ B转录因子介导， 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相比。我们还将确定 是否在乳腺肿瘤中常见等位基因优先缺失， 表现出杂合性缺失，因为这将支持一个直接的作用， 这个区域在致癌过程中。 最后，我们将扩大我们的分子技术的剧目， 完全表征H-ras VNTR的长度和内部结构 变化量通过提高我们对5'序列的检测水平， 开发3' MVR方法，我们将获得完整的MVR序列， 每个等位基因的整个长度，从而确保所有变异/罕见 检测等位基因，尤其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.