Effects of dietary isoflavones on proliferation and DNA integrity of myoblasts derived from newborn piglets

Abstract

Soy-based formulas are consumed by growing numbers of infants and used as regular food supplements in livestock production. Moreover, constituent dietary phytoestrogens may compete with endogenous estrogens and affect individual growth. This study aimed to investigate the in vitro effects of isoflavones in comparison with estrogens on the proliferation of porcine satellite cells derived from neonatal muscle. After 7 h of exposure in serum-free medium, 17β-estradiol (1 nM, 1 μM), estrone (1 μM), and daidzein (1, 100 μM) slightly decreased whereas 100 μM genistein substantially lowered DNA synthesis. Declines in DNA amount were observed with genistein (1, 100 μM) and daidzein (100 μM). After 26 h of exposure, 100 μM genistein reduced DNA synthesis, whereas it was increased by 10 μM genistein and 10 and 100 μM daidzein. In the case of 10 μM genistein and 100 μM daidzein, these increases apparently resulted from the repair of damaged DNA. Genistein and daidzein (100 μM) reduced protein synthesis, caused a G2/M phase block, and decreased DNA amount in association with higher rates of cell death partially resulting from apoptosis. Conclusively, isoflavones at concentrations of greater than 1 μM act as inhibitors of porcine skeletal muscle cell proliferation. © International Pediatrics Research Foundation, Inc. 2008. All Rights Reserved.