Correlation of LF-PRL-R expression with ER/PR and HER-2 expression in breast cancer

Background and objective: The activation of prolactin receptor (PRL-R) may contribute to the development and progression of breast cancer, which is mainly mediated by the long form of PRL-R (LF-PRL-R). Therefore, we analyzed the correlation of LF-PRL-R with ER, PR, and HER-2 expression in breast cancer. Methods: One hundred and thirty female patients with breast cancer (median age, 46 years; age range 26-77 years) undergone surgery without new adjuvant therapy at Sun Yat-sen University Cancer Center between Jan 2000 and Jun 2001 were included. The expression of LF-PRL-R, ER, PR, and HER-2 in the primary lesion from each patient was detected by immunohistochemistry. The correlation of LF-PRL-R expression with ER, PR, and HER-2 in breast cancer was assessed by Chi-square test. Results: Among 130 patients, 89 showed positive LF-PRL-R expression. Stratification of the statistical analysis showed that in the HER-2-positive sub-layer, LF-PRL-R expression was positively correlated with ER and PR expression (P < 0.05), while no correlation was noted in the HER-2-negative sub-layer (P > 0.05). In the ER (or PR) positive sub-layer, LF-PRL-R expression was positively correlated with HER-2 expression (P < 0.05), while no such correlation was noted in the ER (or PR)-negative sub-layer (P > 0.05). Conclusion: The positive correlation of LF-PR-LR expression with ER/PR in breast cancer relies on the positive expression of HER-2, while the positive correlation with HER-2 expression relies on the positive expression of ER/PR, which suggesting combined anticancer therapy based on the individual target site may benefit patients with breast cancer.