Differentially Expressed Genes In Benign Hyperplastic Prostate Epithelial And Stromal Cells With Coculture Or Separated Culture

Background Benign prostatic hyperplasia (BPH) is an almost inevitable feature of aging male and is considered to be responsible for lower urinary tract symptoms (LUTS) in the majority of men over the age of 50 years. Androgens, estrogens, growth factors and neurotransmitters may play roles, either singly or in combination, in the etiology of the hyperplastic process. But the precise molecular mechanism of BPH is unknown, and there may be other putative factors involved in the regulation of prostate growth, such as epithelial-stromal interaction. Abundant experimental evidences demonstrate that prostatic stromal and epithelial cells maintain a sophisticated paracrine-type communication. Cells of a multicellular organism function as integral units. The exchange of information helps to balance such vital opposing processes of proliferation and programmed cell death. A defect in this network leads either to the excessive growth of hyperplasia and neoplasia or to the excessive cell death of hypoplasia and atrophy. Stromal cells from the prostate were recently shown to inhibit clonal growth of the prostatic carcinoma cell lines PC-3 (hormone-independent) and LNCaP (hormone-sensitive) in coculture. Recently, a study showed that most histological carcinomas and atypical adenomatous hyperplasia lesions were found in enlarged prostates with intense hypertrophy. It may suggest that BPH and prostate cancer may have some conjunct mechanisms. The interaction between epithelial and stromal cells is concerned much more recently. We hypothesize that the interaction may be mediated by some growth factors. Bayne's study shows that coculture model reflects more closely the in vivo system for human BPH and is thus a far more suitable model for investigating the molecular and cellular events that underlie BPH than current in vitro systems. But they did not screen the signal molecules of the fibroblast-epithelial interaction in BPH. In this study, we tried to find the regulation factors involved in the interaction between fibroblasts and epithelial cells in BPH. We speculate that these differentially expressed genes in cocultured epithelial cells and fibroblasts, compared to separately cultured prostate epithelial cells and fibroblasts, are important for increased proliferation and decreased apoptosis of prostate cells. Therefore, we compared the gene expression profile of cocultured prostate cells and separately cultured prostate cells.Methods Matched prostate samples were obtained from BPH patients who underwent suprapubic prostatectomy. Differentially expressed mRNAs in fibroblasts and epithelial cells at cocultured or separately cultured condition were screened by using differential display reverse transcription PCR (DD-RTPCR), followed by reverse Northern blot. Some highly relevant genes were confirmed by semi-quantity RT-PCR and western blot. We further studied the expression of KLK7, which was up-regulate in prostate epithelium with coculture, and its inhibitor secretory leukocyte peptidase inhibitor (SLPI) in different kind of prostate tissues. Results We confirmed 5 differentially expressed genes and found kallikrein 7 gene expression is up-regulated in prostate epithelium with coculture. S100 calcium binding protein All, tyrosine 3-monooxygenase/ tryptophan 5-monooxygenase activation protein and cyclin I and latexin mRNA were down-regulated in prostate fibroblasts with coculture. However, Expression of the serine protease kallikrein7 (hk7/SCCE) and its inhibitor secretory leukocyte peptidase inhibitor (SLPI/ALP) is decreased in prostate cancer. A significant negative association was found between Gleason grade and expression of KLK7 and its inhibitor SLPI.Conclusions The five differentially expressed genes may mediate the mutual modulation of epithelial cells and fibroblasts. A significant negative association was found between Gleason grade and expression of SLPI and KLK7. KLK7 and its inhibitor SLPI are deceased in prostate cancers, which beg the question of whether it remains an effective inhibitor of hk7 or whether it is discordant in time or space and is ineffective as an inhibitor of hk7.The function of KLK7 and SLPI in prostate should be further studied.