Expression of somatostatin type-2 and -4 receptor and correlation with histological type in breast cancer.

BACKGROUND Somatostatin is produced by hypothalamic cells and also by tumors. We were interested to evaluate the somatostatin type 2 (SSTR2) and type 4 (SSTR4) receptor expression on a large sample cohort of breast cancer cases. MATERIALS AND METHODS We used two different Tissue Micro Arrays (TMA) to evaluate SSTR2 and SSTR4 distribution. We evaluated the correlation between SSTR2 and SSTR4 expression and 18 tumor cells markers. We also assessed SSTR mRNA expression on an independent breast cancer population and correlated levels of SSTR2 and SSTR4 expression to molecular breast cancer subtypes. RESULTS 268 tumors were analyzed. The tumor overexpression of estrogen receptor was significantly correlated to the expression of SSTR2 (p=0.05) and SSTR4 (p=0.04). On principal component analysis, SSTR2 subtype characterized the luminal tumor type. On an independent breast cancer population, expression of SSTR2 and SSTR4 are independent from Human Epidermal Growth Factor Receptor 2 (Her2) and correlated with luminal tumors. CONCLUSION Expression of somatostatin receptors is a marker of luminal breast tumors.