RANKL/RANK/OPG cytokine receptor system: mRNA expression pattern in BPH, primary and metastatic prostate cancer disease
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The cytokine system RANKL (receptor activator of NF-κB ligand), its receptor RANK and the antagonist OPG (osteoprotegerin) play a critical role in bone turnover. Our investigation was conducted to describe the gene expression at primary tumour site in prostate cancer patients and correlate the results with Gleason Score and PSA level.
Seventy-one samples were obtained from prostate cancer patients at the time of radical prostatectomy and palliative prostate resection (n = 71). Patients with benign prostate hyperplasia served as controls (n = 60). We performed real-time RT-PCR after microdissection of the samples.
The mRNA expression of RANK was highest in tumour tissue from patients with bone metastases (p < 0.001) as compared to BPH or locally confined tumours, also shown in clinical subgroups distinguished by Gleason Score (< 7 or ≥ 7, p = 0.028) or PSA level (< 10 or ≥ 10 µg/l, p = 0.004). RANKL and OPG mRNA expression was higher in tumour tissue from patients with metastatic compared to local disease. The RANKL/OPG ratio was low in normal prostate tissue and high tumours with bone metastases (p < 0.05). Expression of all three cytokines was high in BPH tissue but did not exceed as much as in the tumour tissue.
We demonstrated that RANK, RANKL and OPG are directly expressed by prostate cancer cells at the primary tumour site and showed a clear correlation with Gleason Score, serum PSA level and advanced disease. In BPH, mRNA expression is also detectable, but RANK expression does not exceed as much as compared to tumour tissue.
KeywordsBone metastasis OPG (Osteoprotegerin) Prostate cancer RANK (Receptor activator of NF-κB ligand) RANKL
The authors gratefully acknowledge the support Prof. Dr. André Schrattenholz, ProteoSys AG, Mainz, Germany.
FC: project development, manuscript writing, FK: manuscript writing, SL: manuscript editing, BJ: data analysis, HK: data analysis, RS: data collection, MS: manuscript editing.
Compliance with ethical standards
Conflict of interest
The author(s) declare that they have no competing interests.
Informed consent was obtained from all individual participants included in the study.
All procedures performed in this study involving human participants were in accordance with the ethical standards of the institutional and national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
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