The phytoestrogen genistein has been demonstrated to possess anti-tumor properties by mechanisms not yet clearly established. The present study was designed to investigate the effects of isoflavone genistein exposure at concentrations ranging from 0.01 microM to 50 microM on the LDL receptor and HMGCoA reductase gene expression in the estrogen receptor positive DLD-1 human colon cancer cell line. LDL receptor and HMGCoA reductase gene expressions were evaluated by reverse transcription followed by real-time PCR. Genistein induced an early increase of LDL receptor gene expression and later decreased HMGCoA reductase mRNA expression in DLD-1 cells. These findings provide direct evidence on the role of genistein in regulating LDL receptor and HMGCoA reductase gene expression in colon cancer.