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Updated: Oct 16, 2026
An Orthotopic Murine Model of Human Prostate Cancer Metastasis
Published on: September 18, 2013
Effect of beta-sitosterol on transforming growth factor-beta-1 expression and translocation protein kinase C alpha in
1Wissenschaftliches Labor der Urologischen Klinik der Ruhr-Universität Bochum, Deutschland. Annette.Kassen@ruhr-uni-bochum.de
Background:
Today, plant extracts are widely used in the treatment of benign prostatic hyperplasia (BPH). However, the complete mode of action of the active substance, beta-sitosterol, is under investigation. The purpose of this study was to investigate the effect of beta-sitosterol on the expression of transforming growth factor beta 1 (TGF-beta1) and the activity of protein kinase C alpha (PKC-alpha) in primary prostate stromal cell cultures in vitro.
Methods:
Tissue samples for primary cell cultures were obtained from patients undergoing transurethral resection of the prostate (TURP). TGF-beta1 levels in stromal cell conditioned media following a culture with beta-sitosterol were detected in a TGF-beta1 specific ELISA assay. Following different incubation periods with beta-sitosterol, cells were lysed and fractionated into a Triton-soluble membrane fraction and a cytosol fraction. PKC-alpha protein was detected using immunoblot analysis.
Results:
Beta-sitosterol was able to induce the expression and secretion of TGF-beta1 significantly between 1.26- and 1.86-fold compared to a cholesterol and the nonsupplemented control in 6 of 8 individual cultures. The total amount of secreted TGF-beta1 varied in cells from different patients. Based on its presence in both membrane fraction and cytosol, PKC-alpha appeared to be constitutively expressed in stromal cells. In the absence of beta-sitosterol PKC-alpha was predominantly found in its membrane-associated active form. Following a culture with beta-sitosterol, a translocation of PKC-alpha from the membrane to the cytosol was observed. This effect was specific for beta-sitosterol as compared to cholesterol.
Conclusion:
This study describes the effect of beta-sitosterol on the expression of a multifunctional growth factor (TGF-beta1) and the activity of PKC-alpha membrane in stromal cells of the human prostate in vitro.
