Tumour necrosis factor-α modulates oestradiol responsiveness of MCF-7 breast cancer cells in vitro

Abstract

ABSTRACT We studied the effect of tumour necrosis factor-α (TNF) on oestradiol regulation of growth and metabolism of MCF-7 breast cancer cells to determine whether TNF altered the oestradiol responsivness of these cells. We found that TNF antagonized oestradiol stimulation of cell growth in a dose-dependent manner, with partial inhibition at 1·0 U/ml and complete inhibition at 1000 U/ml. TNF inhibited cell cycle progression, increasing cells in the G0G1 phase and blocking oestradiol-stimulated progression into the S phase. We examined the effect of TNF on three oestrogen-regulated proteins, the oestrogen receptor (ER), the progesterone receptor (PR) and insulin-like growth factor-I (IGF-I). TNF down-regulated the ER and up-regulated the PR. Both of these processes were enhanced by the addition of oestradiol. The effects of TNF on the ER and PR were dose-dependent and occurred without a change in the Kd of the receptor. TNF did not change the respective steady-state mRNA levels. In addition, TNF did not alter secretion of IGF-I either in the absence or presence of oestradiol, indicating that the effects of TNF on oestrogen-regulated proteins is selective. These findings indicate an important interaction between the immune and endocrine systems. The cytokine TNF has a prominent effect on oestradiol stimulation of MCF-7 cells, blocking its proliferative response and enhancing certain metabolic effects. These actions may be mediated in part through modulation of the ER, although other pathways appear to be involved. Journal of Endocrinology (1993) 138, 517–528