Expression of Estrogen Receptors in Relation to Hormone Levels and the Nottingham Prognostic Index.

BACKGROUND: Estrogen hormones have a large impact on both normal development and tumorigenesis of the breast.

MATERIALS AND METHODS: Breast tissue samples from 49 women undergoing surgery were included. The estrogen receptors (ERα and ERβ), ERα36 and G-coupled estrogen receptor-1 (GPER) were determined in benign and malignant breast tissue.

RESULTS: The ERα36 and ERα mRNA levels were highest in malignant tumors. Stromal ERβ immunostaining in benign tumors was higher than in the paired normal tissue. GPER expression was lowest in benign tumors. In the malignant tumors, the Nottingham Prognostic Index (NPI) correlated positively with stromal GPER and the serum testosterone level. The serum insulin-like growth factor-1 (IGF-1) level correlated negatively with GPER mRNA and glandular ERα.

CONCLUSION: The expression of ERα36 is stronger in malignant breast tissue. The strong positive correlation between NPI and GPER in malignant breast stroma indicates an important role for GPER in breast cancer prognosis.