Oestrogen and progesterone receptors in gastrointestinal cancer cell lines

Expression of sex steroid receptors by gastrointestinal (GI) tumours may indicate a role for hormonal manipulation in their management. A panel of seven established cell lines derived from primary human GI tumours were assayed for oestrogen and progesterone receptor (ER and PgR) expression by ligand binding, immunocytochemistry and enzyme-immunoassay methods. It was possible to demonstrate very low levels of both ER and PgR in the GI cell lines using enzyme immunoassay (EIA), with levels of PgR generally higher than those for ER. Neither ER nor PgR were detected in cytosols made from the GI cell lines in a classical dextran coated charcoal ligand binding assay. Similarly, immunohistological analysis (Abbott ERICA, PgRICA) of cultured cell preparations or of frozen and paraffin sections of xenograft tumour failed to demonstrate receptors. This confirms that low PgR levels are measurable by EIA in GI tumour cell lines. Upregulation of PgR expression in tumours by exposure to oestradiol in vitro was not observed.