Genistein (NPI 031L), a phytoestrogen found in soy products, is a highly specific inhibitor ofprotein tyrosine kinase (PTK)which blocks the mitogenic effect mediated by EGF on NIH-3T3 cells withIC50of 12μM or by insulin withIC50of 19 μM. In vitro
Genistein is an ATP competitive inhibitor. Genistein inhibits tyrosine phosphorylation in isolated enzyme and receptor preparations and in whole cells including platelets, lymphocytes and a variety of cultured cells. It also inhibits EGF-stimulated phosphorylation in cultured cells as well as inhibition of Topo II (topoisomerase II). Genistein inhibits EGF-stimulated tyrosine phosphorylation in cultured A431 epidermoid carcinoma cells. Inhibition is competitive with ATP and noncompetitive with substrate. Genistein blocks the mitogenic effect mediated by EGF, insulin and thrombin on NIH-3T3 cells. Genistein also acts as an agonist at the GPR30 receptor and binds to PPARγ and estrogen receptors. Genistein also binds to PPARγ, acting as an agonist at this receptor with Ki of 5.7 μM.
In vivo
Genistein has chemopreventive effects on breast, prostate, and other endocrine-dependent tumors in adult animals. Genistein in the diet reduced the incidence of poorly differentiated prostatic adenocarcinomas in a dose-dependent manner and down-regulated androgen receptor, estrogen receptor-alpha, progesterone receptor, epidermal growth factor receptor, insulin-like growth factor-I, and extracellular signal-regulated kinase-1 but not estrogen receptor-beta and transforming growth factor-alpha mRNA expressions. Dietary genistein protects against mammary and prostate cancers by regulating specific sex steroid receptors and growth factor signaling pathways. Genistein combined with prostate tumor irradiation causes greater inhibition of primary tumor growth and increases control of spontaneous metastasis to para-aortic lymph nodes, increasing mouse survival. Paradoxically, treatment with genistein alone increases metastasis to lymph nodes. Cell Data
cell lines：RL, H9, SKI, HBL-2, Granta and JJN-3 cell lines
