Zeranol (Z) is a non-steroidal agent with estrogenic activity (E2) that is used as an anobolic growth promoter[unreadable] in the U.S. beef industries. Consumption of bio-active Z containing-beef has a potential risk in human normal[unreadable] and cancerous breast cells. Previous work suggests that PTP gamma (PTPG) is an E2-regulated breast[unreadable] cancer suppressor gene. Z is capable in down-regulating the PTPG both in mRNA and protein levels in[unreadable] human normal and cancerous breast tissues and cells. The overall HYPOTHESIS to be evaluated is that the[unreadable] consumption of beef products, derived from Z-implanted beef cattle may possess a potential health impact[unreadable] on human consumers, particularly with respect to reproductive endocrinology and hormone-sensitive breast[unreadable] tissues.[unreadable] Specific Aims: (1): Define epigenetic and gene expression alterations in primary cultured normal human[unreadable] breast epithelial cells, stromal cells, and tissues exposed to serum and meat extracts collected from Zimplanted[unreadable] beef heifers. (2): Define DNA methylation changes in the estrogen inducible mammary tumor ACI[unreadable] rat model exposed to bio-active Z-containing diets formulated from Z-implanted beef heifers. (3) Investigate[unreadable] mammary tumorigenesis in the estrogen inducible mammary tumor ACI rat model after long-term[unreadable] consumption of low level of bio-active Z containing experimental diets formulated from meat collected from[unreadable] Z- implanted beef heifers.[unreadable] The team of researchers assembles expertise in 3 areas to systematically study the mitogenic effects of Z in[unreadable] reproductive and hormone sensitive breast. These include modeling of in vitro and in vivo effects of Z (Lin),[unreadable] mapping and quantification of global and unique epigenetic alterations in gene promoters (Huang & Yan),[unreadable] and comparative quantification of global gene expression and identification of biomarkers (Wick).[unreadable] Significance: The proposed experiments will provide a clear linkage between bio-active dietary Z and PTPG[unreadable] down-regulation to eventual tumorigenesis via epigenetic regulation of the expression of PTPG and other[unreadable] tumor relevant genes. To translate our findings from bench top to bedside, selected biomarkers uncovered[unreadable] from the in vitro experiments will be further validated by proteomic analysis. It is our intent to provide[unreadable] comprehensive data (exposure levels during Z-implantation and after Z withdrawal from the beef heifers) to[unreadable] raise awareness of environmental exposure to the estrogen mimic, beef growth promoter, Z.