Differential expression of oestrogen receptor and oestrogen inducible genes in gastric mucosa and cancer

Abstract

Background: Evidence exists for a role for oestrogen in gastric cancer. The incidence of gastric cancer is much higher in men than in woman, and a similar sex difference is also seen in a rat experimental model of gastric cancer.

Aims: Evidence for a functional oestrogen receptor in normal gastric mucosa and cancer has been sought.

Methods: Oestrogen receptor and the oestrogen inducible genes pS2 and ERD5 were sought by northern blot analysis and in situ hybridisation and immunohistochemistry. Oestrogen receptor protein was studied by enzyme immunoassay.

Results: mRNA for oestrogen receptor was detected in cancer and normal gastric mucosa. Enzyme immunoassay for oestrogen receptor showed a mean of 1.8 fmol/mg protein in cancer and 13.7 fmol/mg in paired normal mucosa. The oestrogen inducible genes pS2 and ERD5 were also detected in both cancer and normal mucosa, with expression localised to epithelium. Expression of pS2 was lower in cancer compared with normal mucosa, whereas ERD5 expression was higher in cancer.

Conclusions: Significant amounts of oestrogen receptor were expressed in gastric mucosa with a lower amount in cancer. Oestrogen inducible genes were also expressed differentially but were not found to correlate closely with oestrogen receptor. Oestrogen receptor functionality remains to be demonstrated in the stomach.