We found ER-b expression in all of our low and intermediate grade cancers and in 83% of high grade cancers but 17% of high grade cancers were negative (P value 0.019). Our study reveals reduced expression of ER-b in higher grade prostatic adenocarcinoma compared to low & intermediate grade ones (P value 0.027).
In this study, we used immunohistochemichal staining on paraffin-embedded blocks of prostate needle biopsy for determining ER-b expression. Using prostate needle biopsy specimen for immunohistochemichal studies of prostate carcinoma has both advantages and disadvantages. Considering the uniform thickness of specimens in prostatic needle biopsies, tissue fixation is more rapid and even in compare with prostatectomy specimens. However, the small size of the specimen has some limitations, such as missing focal small lesions in recut sections. An additional advantage of primary diagnostic needle biopsy is that the patients usually have not received any treatment before the biopsy.
Our data supports that rate of ER-b expression is significantly lower in high grade tumors than in low & intermediate ones (P value 0.027). These findings are agreed with most of currently reported articles.
Leav.et al, using a different monoclonal anti ER-b antibody (anti GC-17), showed ER-b staining present in the majority of grade 3 carcinomas of the peripheral zone but greatly diminished or absent in most grade 4/5 carcinomas [14
Lisa G. Horvath et al studied patterns of ER-b expression in normal, hyperplastic, and prostate carcinoma using a different primary antibody (chicken polyclonal antibody (ER-b 503 IgY3) for immuonohistochemistry. In their study; all normal prostates showed strong ER-b nuclear staining in > 95% of the epithelium and 35% of the stromal cells. The number of ER-b positive cases declined to 24.2% (38/157) in prostatic hyperplasia adjacent to carcinoma and 11.3% (18/159) in prostate cancers. They conclude that ER-b is highly expressed in normal human prostate and there is a progressive loss of expression in prostatic hyperplasia and, to a greater extent, in invasive cancer [15
On the other hand, Bonkhoff et al, have tested two commercially available antibodies in routinely processed and frozen prostate carcinoma tissue sections. The 65-kd anti-rat estrogen receptor b (Upstate Biotechnology, Lake Placid, NY) and 210-180-C050 antibody (Alexis Corporation, Nottingham, UK). They showed that low and intermediate grade adenocarcinoma expressed ER-b in a minority of cases and high grade (primary Gleason grades 4 and 5) cancers revealed at least focal ER positivity in 43% (respectively 61%) of cases [4
In 2003 Fixemer T. et al use a different monoclonal antibody in immuonohistochemistry, reports higher ER-b expression in cancer with Gleason grade IV than in cancers with grades III and V and suggest that ER-b protein expression decreases during cancer progression, but no correlation was found between the ER-b status and the primary Gleason grade [16
It seems there is no obvious explanation for these controversies between different reported results on the levels of ER-b expression. It is well known that imperfect antibody specificity or different primary antibodies, ineffective antigen retrieval and tissue-processing methods, or the presence of unknown isoforms of ER protein may affect immuonohistochemistry performance. A possible implication of ER-b in neoplastic growth control is suggested by the findings of a selective loss of ER-b protein in colon adenocarcinoma and ovarian cancer [17
]. ER-b seems to have a role in the control of proliferation and the prevention of hyperplasia in the rodent prostate, as ER-b knockout mice show prostatic hyperplasia on aging [13