Inhibitory effect of selenite on invasion of HT1080 tumor cells

Selenium, an essential biological trace element, has been shown to reduce a nd prevent the incidence of cancer. Our previous studies have shown that se lenite is involved in the chemoprevention of cancer and induction of apopto sis of cancer cells. In this study, we demonstrate that selenite also inhib its the invasion of tumor cells. Cancer cell invasion requires coordinated processes, such as changes in cell-cell and cell-matrix adhesion, degradati on of the extracellular matrix, and cell migration. We found that selenite inhibited invasion of HT1080 human fibrosarcoma cells. Adhesion of HT1080 c ells to the collagen matrix was also inhibited by treatment with selenite, but cell-cell interaction and cell motility were not affected by selenite. Moreover, selenite reduced expression of matrix metalloproteinase-2 and -9 and urokinase-type plasminogen activator, which are involved in matrix degr adation, but increased a tissue inhibitor of metalloproteinase-1. This inhi bitory effect of selenite on the protease expressions was mediated by the s uppression of transcription factors, NF-kappaB and AP-1. However, selenate showed no remarkable effect on all the steps of cancer cell invasion.