The main objective of this project is to determine whether the xenoestrogenic substances bisphenol A (BPA) and butyl benzyl phthalate (BBP) play a role in the initiation of human breast cancer, and if so, whether this effect is mediated by epigenetic mechanisms. The proposed study is based on the growing concern that estrogenic environmental compounds that act as endocrine disrupting chemicals might have potentially adverse effects on hormone-sensitive organs such as the breast. This concern is further fueled by evidence indicating that natural estrogens, namely 17ß-estradiol (E2), are important factors in the initiation and progression of breast cancer. Therefore, the concern that BPA and BBP, which have estrogenic properties and are widely distributed in the environment, might also be carcinogenic for the human breast is well justified. In order to accomplish these goals we will utilize our in vitro in vivo model (Estrogens and Breast Cancer) in which we have demonstrated the carcinogenicity of E2 in the human breast epithelial cells MCF-10F. The use of this powerful and unique model will provide us a tool for exploring whether BPA and BBP have relevance in the initiation of breast cancer. Furthermore, we have found that the expression of E2-induced transformation phenotypes are associated with hyper or hypomethylation of genes controlling branching and ductulogenesis. These findings are the basis for our postulation that the xenoestrogens BPA and BBP can induce neoplastic transformation by behaving as epigenetic modulators inducing the silencing of critical genes by hypermethylation and/or histone modification that lead to the initiation and progression of breast cancer.
|These studies will determine if xenoestrogenic substances are able to induce neoplastic transformation in HBEC and if epigenetic mechanisms are involved.|
For this purpose, we propose the following specific aim: To determine whether the xenoestrogens BPA and BBP induce neoplastic transformation in human breast epithelial cells, and whether the expression of transformation phenotypes is associated with epigenetic changes in genes controlling branching and ductulogenesis. If the latter is the case, we further aim to determine whether modifying their methylation status reverts the neoplastic process. To accomplish this we will use MCF-10F cells and primary cultures of human breast epithelial cells obtained from reduction mammoplasty. The cells will be treated with BPA and BBP using a protocol similar to that used for the treatment of these cells with E2, which will serve as a control. Methylation studies will be performed using Restriction Landmark Genomic Scanning (RLGS) and the identified genes will be further studied using methylation specific PCR (MSP) followed by confirmation of their expression and functional role. Altogether, these studies will provide first-hand evidence on whether xenoestrogenic substances are able to induce neoplastic transformation in HBEC and that epigenetic mechanisms are involved in this process. Furthermore, the manipulation of the methylated status and silencing of those epigenetically modified genes will provide not only an understanding of how these environmental contaminants are involved in breast cancer initiation, but will also give us tools for developing preventive strategies to counteract their effect in the general population.