No abstract

The beneficial effects of beta-sitosterol treatment recorded in the 6-month double-blind trial were maintained for 18 months. Further clinical trials should be conducted to confirm these results before concluding that phytotherapy with beta-sitosterol is effective.

BACKGROUND LNCaP cells are androgen‐sensitive human prostate cancer cells. They are characterized by a bell‐shaped growth curve in response to increasing doses of dihydrotestosterone (DHT) in culture. At a low concentration of DHT (0.1 nM), these cells show an increase in proliferation, but their growth is arrested at a high concentration (100 nM) of DHT. Results of our previous study demonstrated that the inhibitory effect of DHT at a high concentration was mediated through the action of TGF‐β1. The objective of the present study was to elucidate the mechanism of the proliferative effect of DHT in LNCaP cells. METHODS AND RESULTS DHT stimulated LNCaP proliferation only when cells were cultured in the presence of serum. In serum‐free cultures, the characteristic DHT‐induced proliferation was not observed. The addition of neutralizing antibody against FGF‐2 (basic fibroblast growth factor) was able to inhibit this DHT‐induced proliferation. These results suggest that the proliferative effect of DHT was mediated through the action of FGF‐2. However, results of the reverse transcriptase polymerase chain reaction indicated that LNCaP cells did not express FGF‐2 message. As a result, the source of FGF‐2 in these cultures must be the serum supplemented in the culture media. FGF‐2 can bind to heparin sulfate chains within the extracellular matrix (ECM). In cultures treated with exogenous heparin, the proliferative effect of DHT was abolished. These results led to the development of the hypothesis that DHT treatment mediates the release of FGF‐2 entrapped in the ECM through increased heparinase activity. The addition of heparinase to cultures of LNCaP cells, in the absence of DHT, was able to stimulate cell proliferation. Moreover, 0.1 nM DHT caused a significant increase in heparinase activity. CONCLUSIONS These results provide a possible mechanism for DHT action in LNCaP cells. In the absence of DHT, FGF‐2 in culture was trapped in the extracellular matrix and was not available to interact with LNCaP cells. However, in the presence of 0.1 nM DHT, heparinase activity in the culture was elevated and, as a result, it liberated the trapped FGF‐2 which, in turn, stimulated proliferation in LNCaP cells. Prostate 44:124–132, 2000. © 2000 Wiley‐Liss, Inc.

No abstract

SummaryDie Firma Loges kombiniert westliche und fernöstliche Heilpflanzen zu homöopathischen Komplexen