Abstract
BACKGROUND: Prolactin (PRL) is a polypeptide hormone secreted by the anterior pituitary to stimulate growth and differentiation of the normal mammary gland. Together with its receptor, prolactin receptor (PRLR) have been shown to play a role in breast cancer. This study aimed to examine the roles of PRL and PRLR polymorphisms and expression in breast cancer risk and aggressiveness in Thai patients. METHODS: PRL (rs3756824 C/G and rs2244502 T/A) and PRLR (rs37364 G/T and rs249537 A/G) polymorphisms were genotyped by real-time PCR and PRLR expression was assessed by immunohistochemistry (IHC) in breast cancer tissues. The correlations between PRL and PRLR polymorphisms and breast cancer susceptibility/aggressiveness as well as the associations between PRLR expression and clinicopathological parameters were determined. RESULTS: Two hundred and twenty-seven breast cancer patients and 119 matched controls were recruited at the Division of Head Neck and Breast Surgery, Department of Surgery, Faculty of Medicine, Siriraj Hospital, Thailand from 2010-2014. PRL and PRLR polymorphisms were not correlated with breast cancer susceptibility and there was no association between PRLR polymorphisms and PRLR expression. PRLR was frequently overexpressed in breast cancer with positive hormone receptors. High expression of PRLR was significantly related to the presence of axillary nodal metastasis and lymphovascular invasion and showed a trend towards poorer outcome. CONCLUSIONS: There was a correlation between high PRLR expression and aggressive features of breast cancer. PRLR expression might be utilized as a prognostic factor for identification of luminal breast cancer with poorer outcome.