Aberrant DNA methylation patterns of miRNAs and breast cancer racial disparities

背景：总体而言，欧洲血统(EA)女性的乳腺癌发病率高于非洲血统(AA)女性，但非洲血统(AA)女性更有可能被诊断为雌激素受体阴性、组织学分级高的肿瘤，这些肿瘤与总体上更具侵袭性的临床病程和不良预后有关。乳腺癌的这些差异的原因尚不清楚；然而，环境和生活方式风险因素显然有助于AA妇女更容易患上生物侵袭性类型的疾病。重要的是，乳腺癌研究的最新进展表明，这种关联背后的生物学机制可能在于这些危险因素调节DNA甲基化的能力，从而潜在地改变基因表达并导致癌症种族差异。此外，microRNAs的异常DNA甲基化(MiRNAs)可能比改变蛋白质编码基因的甲基化水平具有更广泛的影响，因为单个miRNA可以调节多个靶基因的表达。然而，据我们所知，还没有研究研究miRNAs的异常DNA甲基化对乳腺癌差异的影响，以及环境和生活方式风险因素是否以及如何在这种关系中发挥作用。研究和培训计划：我们建议研究miRNAs中异常的DNA甲基化，这是一个研究较少的领域，以及它与饮食和生活方式因素的关系，以及与乳腺癌种族差异的关系。这项拟议的研究 使用Illumina Infinity 450K阵列平台对AA和EA妇女的乳腺肿瘤组织进行全基因组甲基化分析所产生的数据，以及从大型病例对照研究--妇女健康圈研究(WCHS)--产生的数据，以及来自AA和EA乳腺癌妇女的生物样本和广泛的问卷数据。在目标1中，我们首先建议从全基因组阵列中选择因RACE和ER状态而差异甲基化的miRNA，并通过独立的、基于高通量测序的甲基化分析方法进行验证；我们还将评估miRNA的表达水平。在目标2中，我们将进一步深入研究参与WCHS的500名AA和500名EA患者肿瘤中的差异甲基化基因。最后，在目标3中，我们将检查miRNA甲基化模式与各种饮食和生活方式因素之间的关联，以及它们在AA和EA女性之间的乳腺癌种族差异中的作用。虽然我以前在医学、营养学和癌症流行病学方面的经验和培训为我追求拟议的研究兴趣提供了坚实的基础，但我在分子流行病学方面的知识和专业知识有限，特别是在表观遗传学、复杂数据的分析及其在人类群体中的应用方面。这一职业发展奖将使我有机会在几个目标领域获得培训和指导，包括乳腺癌生物学、分子致癌和miRNAs的作用方面的知识，遗传/表观遗传学方面的先进方法和技术，生物统计学和生物信息学方面的技能，以及开展科学研究、拨款和开发的伦理方面的一般培训。这些领域的新知识和技能将通过导师(Christine Ambrosone博士、Michael Higgins博士、Song Liu和Steven Belinsky博士)、正式课程、实用实验室培训、研讨会、讲习班和会议获得。从这个奖项中获得的经验和知识最终将为我开发和提交R01资金申请做好准备，这是建立我作为独立研究人员所必需的。目的：这个职业发展奖的主要目的是在上述目标领域获得培训和指导，以发展和扩大我作为癌症流行病学家的职业生涯，使我对DNA甲基化和miRNAs及其在癌症发生和癌症预防中的作用有更深入和全面的了解。我的长期目标是发展专业知识，并能够将最新的表观遗传学、分子和统计学方法整合到基于人群的研究中，特别是研究表观遗传学变化的贡献及其与环境、饮食和生活方式因素之间的关系与癌症风险的关系。我对乳腺癌和种族差异特别感兴趣，但也希望将通过这次培训获得的知识和技能应用于其他癌症。总而言之，这个职业发展奖将为我成功过渡到分子癌症流行病学的科学独立性提供宝贵的经验，重点是表观遗传学及其在癌症预防中的作用。癌症相关性：这项拟议的工作涉及一个研究不足的乳腺癌领域，并将有助于更好地理解表观遗传学作用，特别是miRNAs上异常甲基化在乳腺癌种族差异中的作用的有限文献。我们还将能够评估与异常甲基化模式相关的可修改因素。研究结果可为发现新的生物标记物和制定有针对性的预防和治疗策略提供重要信息。

DESCRIPTION (provided by applicant): Background: Breast cancer incidence is higher in women of European ancestry (EA) than in women of African ancestry (AA) overall, yet AA women are more likely to be diagnosed with estrogen receptor negative, high histological grade tumors that are associated with an overall more aggressive clinical course and poor prognosis. The reasons for these disparities in breast cancer remain unknown; however, environmental and lifestyle risk factors clearly contribute to an increased susceptibility for biologically aggressive types of the disease in AA women. Importantly, recent progress in breast cancer research has indicated that the biological mechanisms behind the association may lie in the ability of these risk factors to modulate DNA methylation, thus potentially altering the gene expression and contributing to cancer racial differences. Further, aberrant DNA methylation of microRNAs (miRNAs) may have a much broader effect than altering the methylation level in protein-coding genes, because a single miRNA can regulate expression of multiple target genes. However, to our knowledge, no study has examined the impact of aberrant DNA methylation of miRNAs on breast cancer disparities and whether and how environmental and lifestyle risk factors play a role in this relationship. Research and Training Plan: We propose to study aberrant DNA methylation in miRNAs, an understudied area, and its association with dietary and lifestyle factors, in relation to breast cancer racial disparities. This proposed study utilizes the data generated from a genome-wide methylation analysis in breast tumor tissue from AA and EA women using the Illumina Infinity 450K array platform and from a large case-control study, the Women's Circle of Health Study (WCHS), with biospecimens and extensive questionnaire data from AA and EA women with breast cancer. In Aim 1, we first propose to select miRNA that are differentially methylated by race and ER status from the genome-wide array, and verify these by an independent, high-throughput sequencing-based methylation analysis method; we will also assess miRNA expression levels. In Aim 2, we will further examine the differentially methylated loci in depth in tumors from 500 AA and 500 EA patients participating in WCHS. Lastly in Aim 3, we will examine associations between miRNA methylation patterns and various dietary and lifestyle factors, and their role in relation to breas cancer racial differences between AA and EA women. While my previous experience and training in medicine, nutrition, and cancer epidemiology provides a solid foundation for me to pursue the proposed research interests, I have limited knowledge and expertise in molecular epidemiology, particularly in epigenetics, and analysis of complex data, and their applications to human populations. This career development award will provide me the opportunity to gain training and mentoring in several targeted areas, including knowledge in breast cancer biology, molecular carcinogenesis and the role of miRNAs, advanced methods and techniques in genetic/epigenetics, skills in biostatistics and bioinformatics, and general training in the ethica conduct of scientific research, grant writing and development. New knowledge and skills in these areas will be obtained through mentorship (Drs. Christine Ambrosone, Michael Higgins, Song Liu, and Steven Belinsky),formal courses, practical laboratory training, seminars, workshops, and conferences. The experience and knowledge gained from this award will ultimately prepare me to develop and submit a R01 application for funding that is necessary to establish myself as an independent researcher. Objective: The main objective of this career development award is to gain training and mentoring in above mentioned targeted areas in order to develop and expand my career as a cancer epidemiologist with a deeper and comprehensive knowledge of DNA methylation and miRNAs and their roles in carcinogenesis and cancer prevention. My long-term goal is to develop expertise and be able to integrate the most current epigenetic, molecular and statistical methods into population-based studies, especially to study the contribution of epigenetic alterations and their associations with environmental, dietary and lifestyle factors in relation to cancer risk. I am particularly interestd in breast cancer and racial disparities, but also would like to apply the knowledge and skills gained through this training to other cancers. In summary, this career development award will provide me invaluable experience for a successful transition into scientific independence in molecular cancer epidemiology with a focus on epigenetics and its role of cancer prevention. Cancer Relevance: The proposed work addresses an understudied area of breast cancer and will contribute to the limited literature for a better understanding of the epigenetic role, in particular aberrant methylation on miRNAs, in breast cancer racial disparities. We will also be able to evaluate modifiable factors that are associated with aberrant methylation patterns. Findings could provide important information for the discovery of novel biomarkers and the development of targeted preventive and therapeutic strategies.