Limited Chemopreventive Effects of Oral Administration of Polyphenol-60 from Green Tea in the MNU-Induced Rat Mammary Tumor Model

Breast cancer remains one of the most prevalent and lethal malignancies in women and female dogs. Nature offers a plethora of nontoxic medicinal compounds that could be an excellent source of antineoplastic molecules for breast cancer prevention. Due to the closeness of human and rat mammary tumors, one of the best models to study breast cancer is in rats. Accordingly, this study investigated the chemoprophylactic potential of polyphenol-60 (PO-60) from green tea on the mammary tumorigenesis model using female Sprague-Dawley rats. Forty 30-day-old female rats were randomly assigned to four groups (n = 10/group): Group 1 received N-methyl-N-nitrosourea (MNU) intraperitoneally (i.p.), Group 2 received MNU i.p. and 0.5% PO-60 in drinking water, Group 3 received saline i.p. and PO-60, and Group 4 received saline i.p. only. Eventually, rats were subjected to necropsy, histopathology, blood biochemical analysis, and assessment of antioxidative status in liver and mammary tissues. The chronic daily ingestion for 298 days of PO-60 in the MNU-induced mammary tumorigenesis model did not interfere with mammary tumor occurrence and evolution. Still, a decline in GPx and SOD levels in the MNU-inoculated animals (G1/G2 vs. G4) was observed. Catalase activity increased in all groups, except for liver from the individuals inoculated with MNU (G1).