L-selenomethionine modulates high LET radiation-induced alterations of gene expression in cultured human thyroid cells.

Abstract. L-selenomethionine (SeM) is emerging as a highly effective protective agent against radiation-induced biological effects. We have shown its protective effect on space radiationinduced death of MCF-10 cells as well as on space radiationinduced transformation of HTori-3 cells. The present study was aimed at elucidation of molecular mechanisms and cellular pathways involved in SeM-mediated radioprotection. Human thyroid epithelial cells (HTori-3 cells), in the presence or absence of SeM, were exposed to a non-toxic or a slightly toxic radiation dose from 1 GeV/n iron ions (10 cGy and 20 cGy, respectively). Total RNA was prepared and changes in gene expression were analyzed using microarray technology. Our analysis has revealed a dramatic effect of SeM on alterations of gene expression caused by space radiation. This study provides a basis for furthering our knowledge about radiation-induced molecular and cellular changes that lead to cellular transformation and death.