Prostate cancer is the most common form of non-skin cancer and the second leading cause of cancer deaths within the United States. The five year survival rate has increased from 69% to 99% over the last 25 years for the local and regional disease, but has remained fairly low (approximately 34%) for the advanced disease. Therefore, current research is aimed at finding complementary or alternative treatments that will specifically target components of the signal transduction, cell-cycle and apoptosis pathways to induce cell death, with little or no toxic-side effects to the patient. In this study we investigated the effect of genistein on expression levels of genes involved in these pathways.

Genistein is a (4', 5', 7-trihydroxyisoflavone) is a major isoflavone constituent of soy that has been shown to inhibit growth proliferation and induce apoptosis in cancer cells. The mechanism of genistein-induced cell death and potential molecular targets for cells. The mechanism of genistein-induced cell death and potential molecular targets for genistein in LNCaP prostate cancer cells was investigated using several techniques. The chemosensitivity of genistein towards the prostate cancer cells was investigated using the ATP and MTS assays and apoptosis induction was determined using apoptosis and caspase assays. Several molecular targets were also identified using cDNA microarray and RT-PCR analysis.

Our results revealed that genistein induces cell death in a time and dose-dependent manner and regulates expression levels of several genes involved in carcinogenesis and immunogenicity. Several cell cycle genes were down-regulated, including the mitotic kinesins, cyclins and cyclin dependent kinases, indicating that genistein is able to halt cell cycle progression through the regulation of genes involved in this process. Several members of the Bcl-2 family which are involved in apoptosis were also affected and a number of genes involved in immunogenicity were up-regulated including the DefB1 and HLA membrane receptors.

The results of this study provide evidence of genistein's ability to inhibit growth proliferation and induce apoptosis and indicates its potential as an adjuvant in chemotherapy and immunotherapy.