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Pancreatic Cancer massively deregulates the local Vitamin D receptors and CPY24A1 – July 2014

The vitamin D system is deregulated in pancreatic diseases

The Journal of Steroid Biochemistry and Molecular Biology, online 30 July 2014, DOI: 10.1016/j.jsbmb.2014.07.011
Doris Hummela, 1, Abhishek Aggarwala, 1, Katalin Borkab, Erika Bajnaa, Enikö Kállaya, , , Henrik Csaba Horvathc
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Highlights

  • During PDAC development CYP24A1 levels are reduced in the endocrine islets.
  • During malignant transformation pancreatic ducts accumulate CYP24A1 protein.
  • CYP24A1 expression correlates with VDR in CP patients, but not in PDAC patients.
  • CYP24A1 overexpressing tumors are highly proliferative.
  • CaSR and VDR are co-expressed in the endocrine cells of the islets.

The vitamin D system is deregulated during development and progression of several cancer types. Data on the expression of the vitamin D system in the diseased pancreas are missing.

The aim of this study was to investigate the expression of the vitamin D receptor (VDR), 1,25-dihydroxyvitamin D3 24-hydroxylase (CYP24A1), and the calcium-sensing receptor (CaSR), a vitamin D target gene, in the different regions of the pancreas in patients with chronic pancreatitis (n = 6) and pancreatic ductal adenocarcinomas (PDAC) (n = 17). We analyzed the expression of these genes at mRNA and protein level with quantitative real-time RT-PCR and immunostaining. mRNA expression of CYP24A1 and VDR was significantly increased in tumors compared with the adjacent non-tumorous tissue (p < 0.05), while CaSR mRNA expression decreased. Both the VDR and the CaSR protein were highly expressed in the endocrine compared with the exocrine pancreas. In CP the CYP24A1 expression was highest in the endocrine pancreas, while in PDACs in the transformed ducts. In the PDAC patients CYP24A1 expression in the islets was significantly lower than in CP patients.

Our data suggest that during ductal adenocarcinoma development the vitamin D system in the pancreas becomes deregulated on two levels: in the islets CYP24A1 expression decreases weakening the negative feedback regulation of the vitamin D-dependent insulin synthesis/secretion. In the transformed ducts CYP24A1 expression increases, impairing the antiproliferative effect of vitamin D in these cells.

Tiny portions of the PDF

1. Introduction
Diseases of the pancreas represent a large burden both for patients and for the public health system.
Pancreatic cancer has poor clinical outcome, the 5-year survival rate is less than 6% (http://www.pancreatic.org ).
The management and follow-up of these patients are still a major challenge for health care providers.
Despite of relatively low incidence, death due to pancreatic cancer ranks fourth among cancer-related deaths in the Western world due to the poor survival rate and rapid fatality after diagnosis.
3. Results
MRNA expression of VDR, CYP24A1, and CaSR in pancreatic ductal adenocarcinoma (PDAC)
In our patient cohort (Table 1), we observed a significant upregulation of VDR (mean 3.7-fold) as well as of CYP24A1 (mean 30.78-fold) mRNA expression in PDAC compared with adjacent parts of the pancreas. mRNA expression of the CaSR decreased in the tumors of most patients by 50%, however did not reach statistical significance (Fig. 1A). CYP27B1 levels did not change (data not shown). Our data are consistent with the microarray gene expression data published in the GEO database by Zhang et al. [28] (Fig. 1B), suggesting that our patient cohort was representative, despite the low sample size.


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4216 png PC-incidence-world-map1.png 31 July, 2014 by admin 27.32 Kb 5542 View Download  
4215 jpg Pancreatic Cancer F1.jpg 31 July, 2014 by admin 37.96 Kb 1362 View Download  
4214 pdf pancreatic diseases.pdf PDF 2014 31 July, 2014 by admin 1.37 Mb 877 View Download  
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