UC Berkeley

Non-communicable diseases (NCDs), including type 2 diabetes (T2D) and breast cancer, account for a vast majority of deaths worldwide. The incidence rates of these morbidities vary widely among different ethnic groups with racial minorities disproportionately affected by these chronic pathologies. Known risk factors among those afflicted with T2D and breast cancer include genetic markers, diet, obesity, and other lifestyle factors. However, these risk factors cannot fully explain the observed incidence rates across different ethnic populations. For migrant populations whose environment is often altered throughout their lifetime, environmental factors play a significant role in the development of chronic diseases. For this reason, approaches that are aimed at identifying non-genetic factors are necessary. This dissertation makes use of an exposome approach known as the receptorome. This methodology was used to investigate differences in hormone receptor activity and their association to breast cancer and T2D in migrant populations. The introduction in Chapter 1 provides an overview of the exposome approach highlighting the role of steroid hormones and environmental mimics in the development of two chronic diseases that disproportionately affect migrant populations. Chapter 2 investigates the association between estrogenic activity and nativity, genetic ancestry, and lifestyle factors among Mexican women. Chapter 3 is an extension of the previous chapter, providing further evidence that ancestry and other breast cancer risk factors may be associated with mechanisms linked through the endocrine system. This study demonstrates the importance of endogenous and exogenous estrogens among different racial/ethnic groups and their potential role in breast cancer incidence rates. Chapter 4 examines hormone receptor activity and the association to T2D and persistent organic pollutants in South Indian Asians and European Whites living in London. Lastly, Chapter 5 summarizes all findings and elucidates a secondary technique, known as metabolomics, to aid in the identification of novel environmental risk factors affecting the incidence rates of NCDs in migrant groups.