Breast cancer (BC) is the most common cancer among women. It is known that the prolactin receptor (PRLR) may play a role in breast carcinogenesis, but the available data are often contradictory. In order to obtain more comprehensive information about the relationship between the PRLR and mammary gland carcinogenesis, we have investigated the association between changes in the receptor expression level and the tumor subtype (and its main characteristics). Using real-time PCR, we have evaluated the PRLR mRNA level in BC tissue samples and normal tissue samples adjacent to tumors (89 pairs). Since the androgen receptor (AR) is now considered as a prognostic marker in BC, we have also evaluated the association between the mRNA levels of AR and PRLR. We have found a significant increase in PRLR expression in luminal subtypes of BC; the highest level of PRLR mRNA was detected in luminal A BC. In HER2-positive ER-, PR-negative BC, the PRLR mRNA level decreased in tumor tissues compared with untransformed tissues. In luminal B HER2-negative BC the high PRLR expression was also associated with a smaller tumor size. In ER-, PR-negative tumors, PRLR expression was associated with AR expression: the PRLR mRNA level increased when AR mRNA level reduced by more than 8 times in triple-negative tumors; in contrast, in HER2-positive subtype it demonstrated a more significant decrease when AR expression reduced by more than 3 times. A tendency towards an increase in PRLR expression with an increase in the AR mRNA level was also observed in the luminal subtypes of BC. The level of PRLR expression also depended on the age of patients. In luminal A BC, PRLR expression was higher in patients under 65 years. In contrast, in luminal B HER2-negative and triple-negative BC, reduced PRLR expression was observed in patients under the age of 40 years and under the age of 50 years, respectively. In this group, patients under 40 years with luminal B HER2-negative BC, also had decreased ER expression (immunohistochemical score 0–4). Thus, PRLR obviously plays different roles in the development and progression of these subtypes of BC: in luminal A BC and luminal B HER2-positive BC PRLR may act as an oncogene, while in luminal B HER2-negative BC and ER-, PR-negative BC subtypes it can play a role of tumor suppressor.
|Number of pages||6|
|Journal||Biochemistry (Moscow) Supplement Series B: Biomedical Chemistry|
|Publication status||Published - Jul 2020|
- breast cancer
- prolactin receptor
- molecular subtypes