Abstract
Background: Benign prostatic hyperplasia (BPH) is a common condition that occurs in over 25% of men aged 50+, increasing to 50% amongst those over 80. Although the etiology of the condition has not been ascertained, the majority of BPH specimens contain inflammatory infiltrates indicating inflammation plays an important role in the progression of the disease. Furthermore, a role for inflammation has also been suggested in prostate cancer (PCa). BPH is not a pre-cursor of PCa but using BPH as a model of inflammation could result in findings that may apply and add to our understanding of PCa. Previous work has demonstrated that the consumption of broccoli can alter inflammatory pathways in the human prostate, and this may be due to the action of the isothiocyanate sulforaphane (SF), a phytochemical derived from broccoli. This dietary compound has a range of biological activities, including reducing inflammation.
Hypothesis: Sulforaphane reduces inflammatory pathways and beneficially alters protein expression in BPH tissue.
Methods: We obtained and cultured human BPH tissue for 24 hours with or without 10µM SF and collected tissue and media for further analysis using two distinct approaches. Firstly, in a targeted approach, known inflammatory markers were measured in the media of five tissue samples by commercially available ELISA. Secondly, a global proteomic analysis was carried out to give an unbiased view of the effect of SF on the protein expression within the tissue. Initially, protein was extracted from the tissue of three individuals, run on 2D gels and spots of interest excised from the gel and in-gel trypsin digested. The resulting peptides were analyzed on an LTQ-Orbitrap Mass Spectrometer and the proteins identified by Mascot. Selected proteins were then further quantified in additional tissue samples.
Results: Analysis of the effect of SF on inflammatory markers revealed that SF significantly reduced levels of secreted IL-6 and to a lesser extent IL-8 and FGF-2. Global proteomic analysis demonstrated that there was, as expected, considerable variation between individuals, and that SF altered expression of several proteins in BPH tissue. Reduction of GRP94, an endoplasmic reticulum chaperone protein observed in one individual, was further verified in independent BPH samples. Initial immunohistochemistry in sections of BPH tissue suggests that SF reduces the nuclear localization of this protein. Further experiments are currently ongoing to investigate these effects in more individuals and also to look at the biological consequences.
Conclusion: Natural variation present within humans highlights the need to use a larger number of samples in order to understand the complex effects of SF on prostate tissue. The results suggest that SF can reduce inflammatory markers and alter proteins within the human prostate indicating a possible protective role for SF in pathogenesis of the prostate.
Citation Information: Cancer Prev Res 2010;3(12 Suppl):B46.
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