title: In vitro transformation of MCF-10A cells by sera harvested from heifers two months post-Zeranol implantation.
abstract: Among many risk factors of breast cancer, estrogens and non-estrogenic endocrine disruptors are considered to play critical roles in human breast carcinogenesis. Zeranol (Z) is a non-steroidal agent with potent estrogenic activity and has been widely used as an FDA approved beef growth promoter in the US. Recently, concerns have been raised about the potential adverse health risk by consumption of products containing biologically active Z and its metabolites. By utilizing cell proliferation assay, soft agar assay, quantitative real-time PCR and Western blotting analysis, we examined the potentially tumorigenic activity of bio-active Z containing sera harvested from heifers two months post Z-implantation and the underlying mechanisms. Our results showed that the growth of MCF-10A exposed to 0.2, 1 and 5% Z-containing serum (ZS) treatment for 3 weeks was 1.3, 1.75 and 1.8-fold faster compared to that of the control sera. After further investigation, we found that ZS increased cyclin D1 and decreased p53 expression at the mRNA and protein levels in MCF-10A compared to the controls. More importantly, treatment of 1% Z-containing sera for 21 days stimulated MCF-10A cells anchorage-independent colony formation in soft agar which illustrates its capability of inducing human normal breast epithelial cell neoplastic transformation. Our experimental results suggest that long-term exposure of low levels of Z and its metabolites contained in beef products might be a potential risk factor in human breast cancer initiation and development.
authors.affiliation: Laboratory of Reproductive and Molecular Endocrinology, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43210, USA.
authors.forename: Weiping
authors.initials: W
authors.lastname: Ye
authors.forename: Pingping
authors.initials: P
authors.lastname: Xu
authors.forename: Saiyi
authors.initials: S
authors.lastname: Zhong
authors.forename: Robert
authors.initials: R
authors.lastname: Jen
authors.forename: Walter R
authors.initials: WR
authors.lastname: Threlfall
authors.forename: Christopher V
authors.initials: CV
authors.lastname: Frasure
authors.forename: Eric
authors.initials: E
authors.lastname: Feng
authors.forename: Hong
authors.initials: H
authors.lastname: Li
authors.forename: Shu-Hong
authors.initials: SH
authors.lastname: Lin
authors.forename: Jie-Yu
authors.initials: JY
authors.lastname: Liu
authors.forename: Young C
authors.initials: YC
authors.lastname: Lin
mesh_terms: D000818:Animals; D002417:Cattle; D002448:Cell Adhesion / Q000187:drug effects; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D002471:Cell Transformation, Neoplastic / Q000139:chemically induced*; D003470:Culture Media; D019938:Cyclin D1 / Q000235:genetics / Q000378:metabolism; D004343:Drug Implants; D004847:Epithelial Cells / Q000187:drug effects; D004968:Estrogens, Non-Steroidal / Q000633:toxicity*; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D044967:Serum; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism; D019155:Veterinary Drugs; D015029:Zeranol / Q000633:toxicity*
chemical_list: D003470:Culture Media; D004343:Drug Implants; D004968:Estrogens, Non-Steroidal; D016159:Tumor Suppressor Protein p53; D019155:Veterinary Drugs; D019938:Cyclin D1; D015029:Zeranol