Effects of Temperature, Nucleotides and Sodium Molybdate on Activation and DNA Binding of Estrogen, Glucocorticoid, Progesterone and Androgen Receptors In MCF-7 Human Cancer Cells

Abstract

We studied the effects of temperature, ribonucleotides and sodium molybdate on the activation and DNA cellulose binding of estrogen, glucocorticoid, progesterone and androgen receptor complexes in MCF-7 cells. Using DNA cellulose binding as a measure of receptor activation, we found that ribonucleotides activated all four of these receptor complexes. Temperature also activated glucocorticoid receptor complexes efficiently but activated progesterone and androgen receptor complexes less well. Temperature did not activate estrogen receptor complexes. Sodium molybdate blocked either ATP or temperature induced activation of glucocorticoid, progesterone and androgen receptor complexes but only partially blocked estrogen activation. Sodium molybdate also prevented the formation of multiple forms of estrogen and glucocorticoid receptor complexes seen on DEAE cellulose and hydroxylapatite chromatography of crude cytosol. The mechanism by which ribonucleotide enhances and molybdate inhibits activation are discussed.

Molybdate-stabilized glucocorticoid receptor: evidence for a receptor heteromer

“…Molybdate was also shown to inhibit the activation of GR (Leach et al, 1979) as well as bindin-' of GR to both specific and unspecific DNA sequences (Scheidereit et al, 1983). Similar findings were also obtained with other classes of steroid receptors when studied in the presence of molybdate (Nishigori & Toft, 1980;Noma et al, 1980;Chong & Lippman, 1981). Addition of sodium molybdate to cytosolic preparations after activation of steroid receptors, however, did not reverse the activation process (Leach et al, 1979).…”