implanted growth promoter used on cattle suspected of role in bc

[Lani]

Serum Derived from Zeranol-implanted ACI Rats Promotes the Growth of Human Breast Cancer Cells In Vitro
SAIYI ZHONG1,2, WEI-PING YE2, ERIC FENG2, SHU-HONG LIN2, JIE-YU LIU2, JOHN LEONG2, CHANGWEI MA1 and YOUNG C. LIN2,3
+ Author Affiliations

1College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, P.R. China
2Laboratory of Reproductive and Molecular Endocrinology, College of Veterinary Medicine, The Ohio State University, Columbus, OH, 43210 U.S.A.
3The Ohio State University Comprehensive Cancer Center, Columbus, OH, 43210 U.S.A.
Correspondence to: Young C. Lin, DVM, Ph.D., Laboratory of Reproductive and Molecular Endocrinology, College of Veterinary Medicine, The Ohio State University, Columbus, OH, 43210. Tel: +1 6142929607, Fax: +1 6142926473, e-mail: lin.15@osu.edu; Changwei Ma, Ph.D., College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, P.R. China. Tel: +86 1062737643, Fax: +86 1062731265, e-mail: chwma@cau.edu.cn
Abstract

Background: Zeranol (Z) is a non-steroidal anabolic growth promoter with potent estrogenic activity that is widely used as a growth promoter in the US beef industry. Consumption of beef derived from zeranol-implanted cattle may be a risk factor for breast cancer. Materials and Methods: The effect of serum on the proliferation of human breast cancer MCF-7 cell line and primary cultured human breast epithelial cells (PCHBECs) was investigated. ACI rats were implanted with 12 mg zeranol pellet and the serum was harvested at day 110 after implantation. The effect of zeranol-serum on mRNA expression of cell cycle regulating gene (cyclin D1) and tumor suppressor genes (p53, and p21) was evaluated using real-time RT-PCR. Results: The serum derived from ACI rats 110 days post-zeranol implantation significantly promoted the proliferation of MCF-7 cells and primary cultured human breast epithelial cells compared to control serum. Zeranol-serum up-regulated cyclin D1 and down-regulated p53 and p21 expression in PCHBECs compared with control serum. Conclusion: Bio-active zeranol metabolites contained in meat produced from cattle after zeranol implantation may be a risk factor for breast cancer.