Serine and methionine enhancement of selenite inhibition of DNA synthesis in a mouse mammary epithelial cell line.

Methionine and serine in combination enhanced the inhibitory effect of selenite on cell growth and DNA synthesis of the MOD mammary epithelial cell line. These amino acids also increased the levels of a 58-kd selenoprotein which has been correlated with selenite's effects in previous studies. The use of the amino acids accelerated the onset of inhibition of DNA synthesis by selenite and increased the rate of actual selenoprotein synthesis. The mechanism of enhancement of selenite's effects was possibly due to the amino acids increasing the levels of essential precursors (i.e. seryltRNA(UGA), HSe-) needed for selenoprotein synthesis.