Hormone-sensitive gene expression in breast tumours.

The expression of genes specifically induced by estrogens (pS2), prolactin (PIP) or progestins (Pg8) was measured in primary breast tumours. A highly augmented pS2 gene expression was evident in 55% of estrogen receptor (ER)+, progesterone receptor (PR)+ tumours but was absent in ER- PR- tumours. There was no clear cut correlation between augmented levels of PIP and Pg8 mRNAs in tumours and ER and PR status. Tumours from premenopausal patients were more likely to contain high levels of Pg8 mRNA (P less than 0.038), whereas tumours from postmenopausal patients tended to have augmented levels of PIP mRNA (P less than 0.053).