Colin W. Bayne

Serenoa repens (Permixon®) : A 5α-reductase types I and II inhibitor-New evidence in a coculture model of BPH

The aim of this study was to determine the effect of the phytotherapeutic agent, Permixon®, on a novel coculture model of benign prostatic hyperplasia (BPH) in an effort to better understand the mode of action of the drug in vivo.

Expression of oestrogen receptor beta (ERβ1) protein in human breast cancer biopsies

Oestrogen action is mediated via specific receptors that act as ligand-activated transcription factors. A monoclonal antibody specific to the C-terminus of human oestrogen receptor beta has been characterized and the prevalence of expression of oestrogen receptor beta protein investigated in a well defined set of breast cancers. Reverse transcription-polymerase chain reaction analysis of RNA from tissue biopsies detected oestrogen receptor beta in all samples examined. The anti-oestrogen receptor beta antibody cross reacted specifically with both long (∼59 Kd) and short (∼53 Kd) forms of recombinant oestrogen receptor beta. Western blot analysis of breast tumours contained both forms of oestrogen receptor beta protein although in some samples lower molecular weight species (32–45 Kd) were identified. Fifty-one breast cancer biopsies were examined using immunohistochemistry; 41 (80%) were immunopositive for oestrogen receptor alpha, 48 (94%) were immunopositive for oestrogen receptor beta and 38 (74.5%) co-expressed both receptors. Expression of oestrogen receptor beta was exclusively nuclear and occurred in multiple cell types. There was no quantitative relationship between staining for the two ERs although in tumours in which both receptors were present immunoexpression of oestrogen receptor alpha was invariably more intense. The significance of oestrogen receptor beta protein expression in breast cancers to therapy remains to be determined but the availability of a well characterized antibody capable of detecting oestrogen receptor beta in archive material will facilitate the process.

THE SELECTIVITY AND SPECIFICITY OF THE ACTIONS OF THE LIPIDO-STEROLIC EXTRACT OF SERENOA REPENS (PERMIXON®) ON THE PROSTATE

PURPOSE To investigate the effects of the phytotherapeutic agent, Permixon(R), on primary cultures of fibroblast and epithelial cells from the prostate, epididymis, testes, kidney, skin and breast and to determine the selectivity and specificity of the action of the drug. MATERIALS AND METHODS All primary cultures were examined by electron microscopy before and following treatment with Permixon(R) (10 microg./ml.). In addition the apoptotic index was assessed by flow cytometry employing propidium iodide as a fluorophore. The impact of the drug on 5alpha-reductase (5alphaR) isoenzymes was also tested utilizing a pH specific assay. RESULTS There were changes in the morphology of prostate cells after treatment including accumulation of lipid in the cytoplasm and damage to the nuclear and mitochondrial membranes; no similar changes were observed in other cells. Permixon(R) increased the apoptotic index for prostate epithelial cells by 35% and 12% in the prostate stromal/fibroblast. A lesser apoptotic effect was demonstrated in skin fibroblast (3%) whereas none of the other primary cultures showed any increase in apoptosis when compared with the controls. Permixon(R) was also an effective inhibitor of both 5alphaR type I and II isoenzymes in prostate cells, but other cells showed no inhibition of 5alphaR activity following treatment with the plant extract. CONCLUSIONS This investigation demonstrated the selectivity of the action of Permixon(R) for prostate cells. The morphological changes in the prostate are accompanied by an increase in the apoptotic index along with an inhibition in the activity of the nuclear membrane bound 5alphaR isoenzymes. No similar changes were observed in any of the other cells under investigation.

Selective Interactions between Prostate Fibroblast and Epithelial Cells in Co-Culture Maintain the BPH Phenotype

Paracrine interactions between primary cultured prostate epithelial cells and stromal fibroblasts were investigated in relation to morphology, growth, androgen sensitivity and secretory activities using co-cultures in which the two populations were separated by a microporous membrane. In this new model system, both cell types maintained several aspects of the differentiated phenotype including the capacity to express 5α-reductase iso-enzymes and androgen receptors, to respond to androgens and to secrete prostate-specific antigen by the epithelial cells. Morphological studies demonstrated that the cells grown in co-culture exhibited round nuclei, tonofibrils and microvilli in epithelial cells and elongated nuclei, large amounts of Golgi apparatus and cilia in the fibroblasts, all indicative of the differentiated state. The co-culture system highlights the importance of the metabolic co-operation between prostate fibroblast and epithelial cells for preserving the phenotypic characteristics associated with the human prostate in vivo.

Development of a new in vitro model for the study of benign prostatic hyperplasia.

The search for novel agents for the treatment of the lower urinary tract symptoms (LUTS) associated with benign prostatic hyperplasia (BPH) is dependent on an increased understanding of the pathophysiology of the disease. Unfortunately, in vitro and animal models have been of limited value.

Factors Controlling the Expression of 5α-Reductase in Human Prostate: A Possible New Approach for the Treatment of Prostate Cancer

The functional activity of the 5α-reductase isoenzyme in the human prostate is gradually depleted as the gland undergoes transformation from the normal to the metastatic state. There are two isoforms of this enzyme expressed in the prostate and recent studies have demonstrated that the type II isoenzyme is the one most affected by the onset of neoplasia. To elucidate the mechanism(s) responsible for the down-regulation of the isoenzyme activity, we re-examined the nature of the interaction between stroma and epithelial cells in the human prostate. We noted that the control of the isoenzyme expression in the epithelial cells was regulated by a paracrine factor specific to the prostate fibroblast. In the absence of this factor the human prostate loses its capacity to express the 5α-reductase type II isoenzyme – a characteristic manifested simultaneously with the loss of differentiation in the tissues. This finding presents a totally new concept to the control of 5α-reductase in the human prostate and offers a possibility for an interesting and alternative approach to the management of prostate cancer.