SHORT-TERM EFFECTS OF PURE ANTIESTROGEN ICI-182780 TREATMENT ON ESTROGEN-RECEPTOR, EPIDERMAL GROWTH-FACTOR RECEPTOR AND TRANSFORMING GROWTH-FACTOR-ALPHA PROTEIN EXPRESSION IN HUMAN BREAST-CANCER

Expression of oestrogen receptor (ER), epidermal growth factor recepto r (EGFR) and transforming growth factor-alpha (TGF alpha) proteins was assessed by immunocytochemistry on primary breast cancer specimens ob tained before and following short-term (7-day) presurgical exposure to pure anti-oestrogen (7 alpha- [9- (4,4,5,5,5-pentafluoropentylsulphin yl) nonyl] estra-1,3,5, (10)-triene-3,17 beta-diol, ICI 182780) treatm ent and compared with no-treatment controls. Paired needle-core and ma stectomy samples were obtained from 21 patients. Effects of ICI 182780 (10(-7) M) on IMCF7 breast cancer cell ER, EGFR and TGF alpha express ion were also examined over 14 days. ER protein was significantly supp ressed by ICI 182780 in vivo (P = 0.009) and comparative analysis of s hort term ICI 182780 effects in vitro, using ER-positive MCF7 cells, g ave largely equivalent results. EGFR and TGF alpha protein levels were unaltered by treatment. ICI 182780 suppresses ER without a concomitan t rise in either EGFR or TGF alpha.