Detection of oestrogen receptors (ER) alpha and beta in conjunctiva, lacrimal gland, and tarsal plates.

PURPOSE: Lack of Oestrogen and androgen may be of importance in the pathogenesis of keratoconjunctivitis sicca (KCS). The signal of Oestrogens is transmitted via specific Oestrogen receptors (ER). It was the purpose of this study to evaluate the expression of ER alpha and ER beta in tear-producing tissues. METHODS: Reverse transcriptase-polymerase chain reaction (RT-PCR, ER alpha + beta) and immunohistochemical evaluation (ER alpha only) were performed for ER detection and localization in tissue samples of bulbar conjunctiva (20 samples of 20 patients undergoing cataract surgery), tarsal plates (14 samples of 12 patients undergoing eye lid surgery), and lacrimal glands (20 samples of 13 cornea donors). RESULTS: Messenger RNA ER alpha was identified via RT-PCR in all tissue samples with variable expression, ER beta predominantly in lacrimal gland tissue. Immunohistochemical staining for ER alpha was negative in most cases, probably due to the thermolability of ERs and very small sample sizes. CONCLUSIONS: The detection of ER alpha and ER beta mRNA expression supports the concept of a receptor-based effect of Oestrogen in these tissues contributing to KCS. This may encourage therapeutical efforts including topical Oestrogen administration.

Gene amplification and expression of the steroid receptor coactivator SRC3 (AIB1) in sporadic breast and endometrial carcinomas.

Steroid receptor coactivator 3 (SRC3) functions as a coactivator for nuclear receptor mediated transcriptional activation. It binds to nuclear receptors in a ligand-dependent fashion and recruits other factors such as CBP and p300 to the transactivation complex. Due to its function as activator of nuclear receptors, overexpression of SRC3 might enhance their effects. Gene amplification is a common mechanism that causes overexpression, already described for oncogenes like c-erbB2, c-myc and int2. In this study, SRC3 gene amplification and expression levels were analyzed in 127 sporadic breast carcinomas, 30 endometrial carcinomas and different cell lines (MCF7, HeLa, Ishikawa, T47D, BT-20, SK-BR-3, HEC-1a, RL 95-2, OVCAR3 and A-431). To determine gene amplification and mRNA expression levels, quantitative differential PCR and RT-PCR were performed in combination with fluorescent DNA technology. Gene amplification was not found in any of the breast and endometrial carcinomas, but was found in the carcinoma cell lines MCF7 (10-fold) and HeLa (3-fold). SRC3 overexpression was detected in 13% (3/23) of breast carcinomas and 17% (5/30) of endometrial carcinomas, as well as in MCF7 and HeLa cells. Thus, SRC3 overexpression found in breast and endometrial tumors is not caused by SRC3 gene amplification. A carcinogenic potential provided by SRC3 overexpression has to be elucidated in further studies.