Vang O, Jensen H, Autrup H
Laboratory of Environmental Carcinogenesis, Fibiger Institute, Danish Cancer Society, Copenhagen.
Chem Biol Interact. 1991;78(1):85-96. doi: 10.1016/0009-2797(91)90105-g.
Ingestion of broccoli or other cruciferous vegetables inhibits the induction of cancer by chemicals and modifies some cytochrome P-450 enzyme activities. The effect of dietary broccoli on the levels of P450IA and IIB mRNA and proteins in rat liver and colon has been studied. Rats were fed a ten percent broccoli diet for 7 days. The expression of the cytochrome P-450 forms was altered to a different extent in the liver and colon. The level of total P450IA mRNA in the liver was increased by the broccoli together with the P450IA1 and IA2 proteins. Colonic P450IA1 mRNA and protein were induced by the broccoli diet, whereas only P450IA2 protein and not mRNA was detectable in colon, but the protein level was unaffected by the broccoli diet. Liver P450IIB and IIE1 proteins were increased by the broccoli diet, whereas the level of P450IIB mRNAs was not affected. In contrast, the P450IIB mRNA levels were reduced but the protein levels were increased in colon and we suggest that a feedback mechanism caused the decrease of the P450IIB mRNAs levels. Because the ratio between activation and deactivation may be an important risk determinant, we conclude that the protective effect of the broccoli diet on chemically induced tumors in rodents may be caused by the broccoli-induced changes in P450IA and IIB associated enzyme activities.
食用西兰花或其他十字花科蔬菜可抑制化学物质诱导的癌症发生，并改变某些细胞色素P - 450酶的活性。本研究了膳食西兰花对大鼠肝脏和结肠中P450IA和IIB mRNA及蛋白质水平的影响。给大鼠喂食含10%西兰花的饲料7天。细胞色素P - 450各亚型的表达在肝脏和结肠中发生了不同程度的改变。西兰花使肝脏中总P450IA mRNA水平以及P450IA1和IA2蛋白质水平升高。西兰花饮食诱导结肠中P450IA1 mRNA和蛋白质表达，而在结肠中仅可检测到P450IA2蛋白质，mRNA未检测到，但其蛋白质水平不受西兰花饮食影响。西兰花饮食使肝脏中P450IIB和IIE1蛋白质增加，而P450IIB mRNA水平未受影响。相反，结肠中P450IIB mRNA水平降低，但蛋白质水平升高，我们认为存在一种反馈机制导致了P450IIB mRNA水平下降。由于激活与失活之间的比例可能是一个重要的风险决定因素，我们得出结论，西兰花饮食对啮齿动物化学诱导肿瘤的保护作用可能是由西兰花诱导的P450IA和IIB相关酶活性变化所致。
