Short-term effects of pure anti-oestrogen ICI 182780 treatment on oestrogen receptor, epidermal growth factor receptor and transforming growth factor-alpha protein expression in human breast cancer.

Expression of oestrogen receptor (ER), epidermal growth factor receptor (EGFR) and transforming growth factor-alpha (TGF alpha) proteins was assessed by immunocytochemistry on primary breast cancer specimens obtained before and following short-term (7-day) presurgical exposure to pure anti-oestrogen (7 alpha- [9- (4,4,5,5,5-pentafluoropentylsulphinyl) nonyl] estra-1,3,5, (10)-triene-3,17 beta-diol, ICI 182780) treatment and compared with no-treatment controls. Paired needle-core and mastectomy samples were obtained from 21 patients. Effects of ICI 182780 (10(-7)M) on MCF7 breast cancer cell ER, EGFR and TGF alpha expression were also examined over 14 days. ER protein was significantly suppressed by ICI 182780 in vivo (P = 0.009) and comparative analysis of short term ICI 182780 effects in vitro, using ER-positive MCF7 cells, gave largely equivalent results. EGFR and TGF alpha protein levels were unaltered by treatment. ICI 182780 suppresses ER without a concomitant rise in either EGFR or TGF alpha.