Vitamin D receptor expression in human adrenal medulla and pheochromocytoma cells.

PURPOSE: We aimed to elucidate the expression of VDR (vitamin D receptor) in human adrenal medulla and pheochromocytoma cells and to investigate the potential associations between VDR and the clinicopathological characteristics of pheochromocytoma. METHODS: The expression of VDR at the mRNA level in FFPE (Formalin-Fixed Paraffin Embedded) tissues from 31 pheochromocytomas, 4 adrenal cortex and 4 adrenal medulla was assessed via highly sensitive digital PCR. For pheochromocytoma patients, the clinical and histopathological features were retrospectively assessed. RESULTS: VDR mRNA expression in adrenal medulla and pheochromocytoma cells was compared to the expression in the adrenal cortex, which was set at 1.0. The median VDR mRNA expression in pheochromocytoma samples was lower than that in both unaltered medulla and cortex. No statistically significant correlations were detected between VDR mRNA expression in pheochromocytomas and most of the clinical parameters. The VDR expression level did not significantly correlate with the vitamin D concentration in the patients’ serum. However, VDR expression in tumors was negatively associated with somatostatin receptor 2 (SSTR2) levels, with the confounding influence of sex and the interaction with elevated 3-methoxytyramine concentrations. CONCLUSION: Our study is the first to characterize the expression of the vitamin D receptor (VDR) in both the intact adrenal medulla and pheochromocytoma cells. The highest median VDR expression was observed in the adrenal cortex, followed by intermediate levels in the adrenal medulla, and the lowest expression in pheochromocytoma cells. However, further studies are needed to clarify the relationship between vitamin D and catecholaminergic cells.