Effects Of Daidzein On The Growth Of LoVo Cells In Vitro

[Background and Objective] The worldwide geographical variation in cancer incidence has shown a relation between differences in the dietary habits of populations and high or low risk of cancer, thus the role of diet in the control of cancer risk has drawn widespread attention. The age-adjusted death rates from breast cancer are two to eight fold more in united states and western Europe than in Asian countries where soy is commonly consumed, which made this hypothesis intriguing, especially because the fat/breast cancer connection began to weaken.Meanwhile, in 1991 a case-control study conducted in Singapore showing that the consumption of modest amounts of soy was associated with an ⁵0% reduction in premenopausal breast cancer risk,which did much to further stimulate interest in soy. Finding also showing that the addition of soy protein to a typical laboratory diet significantly decreased chemically induced rat mammary cancer prompted the National Cancer Institute shortly thereafter issuing a request for applications for research in this area.Although soy contains a number of putative anticarcinogens, initial excitement over the hypothesized anticancer effects of this legume was based largely on the possibility that isoflavones might exert antiestrogenic effects on breast tissue.Isoflavones are a subclass of the more ubiquitous flavonoids. In total, there are 12 different soybean isoflavone isomers, The primary isoflavones in soybeans are the glucosides, genistin and daidzin and their respective aglycones genistein (4'57-trihydroxy isoflavone) and daidzein (4'7-dihydroxyisoflavon e).Typically, there is62003somewhat more genist(e)in than daidz(e)in in soybeans and soy foods. There are also small amounts of a third isoflavone in soybeans, ie,glycitein(7,4'-dihydroxy-6-methoxyisoflavone) and its glycoside ,glycidtin.Genistein, which was thought as primary bioactivity isomers in soybean, was studied more often than other isoflacvones and was confirmed to have bioactivity in a variety of areas in addition to the agonist or antagonist properties. It can inhibit tyrosine protein kinase and top-II,and may inhibit angiogenesis and antioxidant activities. Daidzein, also rich in soybean ,has a spatial conformation similar to that of genistein ,but it can not inhibit Tyrosine protein kinase and top- II enmyze and was once seen as an inactive analogue of genistein. More often it was used as a tool with geinistein for identifying whether certain cellular processes were under the control of a variety of kinases.Nevertheless, recently there were some studies reporting daidzein has a lot of bioactivities including estrogen-like effects or estrogen-independent effects. In this work, we study the effect of daidzein on the growth of human colonic cancer line LoVo cell, aimed to describe characteristics of daidzein associated with the estrogen receptor, and compare our result with the characters of genistein published before to stady the cellar mechanism of daidzein effects.[Methods] 1 The human colonic carcinoma cell line LoVo were cultured at 37 癈 in a CO₂ incubator in plastic dishes containing RPMI-1640 supplemented with 10% fetal bovine serum. The culture medium was changed every second day. The cells in the exponential phase of growth were aimed to study. After the cells were removed at the indicated time from culture dishes by trypsinization,They were collected and the density was adjusted to 1 X 104 cells/ml, then seeded the cell into 96-well microplate, each well contained 200ul. 2 Daidzein was solubilized in dimethylsulfoxide(DMSO) and was added into the culture medium to make its concentration at 0.1,1,5,10,50 and l00uMthe final concentration of DMSO was less than l%o. 3 After cells were seeded 24h to allow their adhesion to the plate, the culture72003medium was change to experimental medium supplemented with daidzein. A 96-well microplate was divided into 8 columns with each column representing control or treatment group. A black control column consisted of medium...