Reduced mrna expression level of corticotropin-releasing hormone-binding protein is associated with aggressive human kidney cancer

Hossein Tezval,Inga Peters,Jürgen Serth,Markus A Kuczyk,Axel S Merseburger,Jan U Becker,Sandra Waalkes,Faranaz Atschekzei,Arnulf Stenzl,Jörg Hennenlotter

doi:10.1186/1471-2407-13-199

Abstract

BackgroundSignificance of Urocortin (Ucn or UcnI), Ucn2, Ucn3 and their receptors, Corticotropin Releasing Factor Receptor 1 and 2 (CRFR1 and CRFR2), and the binding protein, Corticotropin-Releasing Hormone-Binding Protein (CRHBP) in oncology is growing rapidly. The objective of our study was to assess the expression of the CRHBP mRNA and protein in renal cancer.MethodsTumoral tissues of 78 patients with clear cell renal cell cancer and their corresponding normal tissues were analyzed using quantitative mRNA expression analysis for detection of mRNA expression level. Protein expression and tissue localization of CRHBP protein in renal specimens was evaluated using western blotting, immunohistochemistry and double immunofluorescence, respectively.ResultsWe found an approx. 33 fold decrease of average CRHBP mRNA level in tumoral tissues compared to paired normal tissues (p<0.001). Diminished CRHBP mRNA expression was positively correlated with advanced, metastasized and higher stage of disease (p<0.001, p=0.026, p=0.028 respectively). CRHBP protein was detected in glomeruli and proximal tubules of normal kidney while none or weak immunopositivity was found in cc-RCC (p<0.001).ConclusionsThe expression analysis of CRHBP shows that cc-RCC is characterized by a significant loss of CRHBP mRNA expression that furthermore is associated with a more aggressive state of tumors. Depletion of CRHBP proteins also indicate that the protein as part of the UCN system may be involved in renal carcinogenesis.

Highlights

Significance of Urocortin (Ucn or UcnI), Urocortin 2 (Ucn2), Urocortin 3 (Ucn3) and their receptors, Corticotropin Releasing Factor Receptor 1 and 2 (CRFR1 and Corticotropin-Releasing Factor Receptor 2 (CRFR2)), and the binding protein, Corticotropin-Releasing Hormone-Binding Protein (CRHBP) in oncology is growing rapidly
Analysis of mRNA expression of CRHBP in normal kidney and kidney cancer Using 5 ́ exonuclease fluorogenic real-time PCR assays for quantitative expression analysis of CRHBP mRNA levels, we found in pairwise comparisons in most of cases a loss of expression in tumor tissues as indicated by the negative differences of sorted pairwise relative expressions in tumor and normal tissue (Figure 1A)
Here we demonstrate that CRHBP expression is depleted both on mRNA and most likely on protein level in clear cell renal cell carcinoma (cc-RCC)

Summary

Introduction

Significance of Urocortin (Ucn or UcnI), Ucn, Ucn and their receptors, Corticotropin Releasing Factor Receptor 1 and 2 (CRFR1 and CRFR2), and the binding protein, Corticotropin-Releasing Hormone-Binding Protein (CRHBP) in oncology is growing rapidly. The Corticotropin releasing factor (CRF) system in human includes all naturally occurring CRF peptide analogues namely Urocortin (Ucn) and Urocortin 3 (Ucn3), known as CRF counterparts in the periphery, the CRF receptors 1 and 2 (CRFR1 and CRFR2), and Corticotropin-releasing hormone-binding protein (CRHBP) [1,2,3,4]. To assess a potential relevance of CRHBP expression alterations for cc-RCC we first compared the mRNA expression levels of CRHBP in cc-RCC fresh frozen specimens and paired normal appearing tissue samples using quantitative RT-PCR analysis. Presence and localization of CRHBP protein expression in normal and malignant kidney tissues were investigated using immunohistochemistry and immunofluorescence

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