Expression of oestrogen receptor and oestrogen-inducible genes pS2 and ERD5 in large bowel mucosa and cancer.

Since there is a preponderance of large bowel cancer in males, both in humans and in experimental models, and hormone replacement therapy is protective, a role for sex steroid hormones in the pathogenesis of this neoplasm seems likely. Evidence of functional oestrogen receptor has been looked for in large bowel mucosa and cancer. Expression of oestrogen receptor, and of the oestrogen-inducible receptor-associated genes pS2 and ERD5, was sought. Oestrogen receptor mRNA was detected in cancers and paired normal mucosae in equal amounts. In situ hybridization identified stromal cells above the muscularis mucosae that were positive for oestrogen receptor mRNA. pS2 mRNA was also detected, with a signal intensity significantly higher in normal mucosa compared with cancers, whereas the reverse was seen with ERD5 mRNA levels. pS2 and ERD5 were expressed in epithelium, with the former in a greater amount in distal colon and rectum than proximal colon. Although oestrogen-inducible and receptor-associated genes are expressed in large bowel mucosa, their expression does not correlate with oestrogen receptor.