Interactions between oestradiol and danazol on the growth of gastrointestinal tumour cells.

The gastrointestinal tumour cell lines, MKN45G and C146 possessed oestrogen receptors (ER) of affinities 1.8 x 10(-8) and 5.2 x 10(-9) M respectively. C146 and MKN45G had enhanced proliferation in the presence of oestradiol (10(-8) and 10(-10) M). Fifty-six percent (5/9) of primary gastric and colorectal tumours had their proliferation enhanced by oestradiol. The anti-steroidal drug, danazol, inhibited the basal growth of MKN45G (10 micrograms ml-1 45% of the untreated control), C146 (10 and 5 micrograms ml-1, 20 and 48% of control, respectively) and 3/9 GI primary tumours (10 micrograms ml-1). Danazol competed with 3 [H]-Oestradiol for binding to ER on MKN45G and C146, at concentrations from 10 to 1 micrograms ml-1.