Objective: The discovery of a novel estrogen receptor (ER), ER-beta, has given rise to new possibilities regarding estrogen's roles in the prostate. Although ER-beta is reported to be expressed preferentially in the rat prostate, its expression in the human prostate and relationship to cancer development has not been investigated. Thus the purpose of the study was to examine mRNA levels of ER-alpha and ER-beta in benign prostatic hyperplasia and prostate carcinoma.
Methods: Samples of 15 prostate cancers obtained at radical prostatectomy were examined. All the patients had been maintained on androgen withdrawal therapy for at least 3 months. ER-alpha and ER-beta mRNAs were measured with a competitive PCR technique.
Results: Both ER-alpha and ER-beta mRNAs were detected in all of the prostate cancer tissues examined, as well as in PC3 and LNCap cells, although the levels varied among specimens. Interestingly, both types were significantly decreased in cases with lymph node metastasis. However, there was no correlation between ER mRNA levels and any other clinicopathological parameters.
Conclusions: (1) Both ER-alpha and ER-beta mRNAs are expressed in prostate cancer and (2) expression of ER mRNA may not be related to cancer progression but may be negatively correlated with metastasis.