ESTROGEN AND PROGESTERONE RECEPTORS IN COLORECTAL-CANCER AND HUMAN COLONIC-CANCER CELL-LINES

Receptors for oestrogen (ER) and progesterone (PR) were assayed in tis sue from 17 patients with colorectal cancer and five colonic cancer ce ll lines using enzyme immunoassays. ERs and PRs were detected in 15 an d 17 cancers respectively, although the levels detected were low: medi an (range) ER 1.3 (0-11-3) and PR 3.9 (0.3-10-2) fmol per mg protein. These values were not significantly different from median (range) leve ls of ER (1.1 (0.6-3.0) fmol/mg) and PR (1.9 (0.5-3.2) fmol/mg) detect ed in normal mucosa. There were significant positive correlations betw een the levels of ER and PR for cancer tissue (tau = 0.56, P < 0.005; r(log transform) = 0.68, P < 0.003; n = 17) but not for mucosa, and be tween levels of ER in cancer tissue and mucosa (tau = 0.55, P < 0.05; r(log transform) = 0.70, P < 0.025; n = 10) but not between the corres ponding PR values. In maintenance media, which contained phenol red an d unstripped fetal calf serum, the median (range) concentration of ER was 1.9 (1.2-10-4) fmol/mg and that for PR 24.3 (9-1-63.2) fmol/mg in the five cell lines studied (HT-29, LS174T, SW620, LoVo, COLO 320DM). The addition of oestradiol (10 nmol/l) to phenol red-free medium conta ining 5 per cent dextran-coated charcoal-treated fetal calf serum had little effect on the concentration of ERs or PRs in SW620, LoVo and CO LO 320DM cells after 7 days' culture. It is concluded that ERs and PRs are expressed in malignant and normal colonic mucosa. ERs appear to b e a feature of the colonic mucosa rather than the malignant process, b ut in carcinoma may regulate synthesis of PRs, suggesting a degree of oestrogen responsiveness.