Effects of insulin-like growth factors I and II on oestrone sulphatase activity in human breast cancer cell lines

Oestrogens play an important role in the development of breast cancer. A ve ry important source of active oestrogens in the breast is oestrone sulphate which is converted to oestrone by oestrone sulphatase. The aim of this stu dy was to assess the effects of IGF-I and IGF-II on oestrone sulphatase act ivity in, as well as cell growth of, MCF-7 and MDA-MB-231 human breast canc er cell lines. Cells were grown in supplemented DMEM and treated with varyi ng concentrations of IGFs. At the end of the treatment period, intact cell monolayers were washed and assayed for oestrone sulphatase activity and the number of cell nuclei determined on a Coulter Counter. Oestrone sulphatase activity was significantly stimulated by IGF-I and II at concentrations of 100 ng/ml and 200 ng/ml in MCF-7 cells. IGF-I had no effect on oestrone su lphatase activity in MDA-MB-231 cells over the range of concentrations test ed. Significant inhibition of oestrone sulphatase was observed in MDA-MB-23 1 cells at higher concentrations of IGF-II (50 ng/ml, 100 ng/ml and 200 ng/ ml). Both IGF-I and IGF-II at higher concentrations (100 ng/ml and 200 ng/m l) significantly inhibited MCF-7 and stimulated MDA-MB-231 cell growth. Sin ce IGF-I and II have effects on cell growth and oestrone sulphatase activit y in breast cancer cell lines they may play a role in the development and p rogression of human breast cancer.