Expression of adiponectin receptors 1 and 2 and the leptin receptor in human adrenal tumors

INTRODUCTION: The role of adipokines in neoplasms not related to obesity is unclear. The presence of adiponectin receptors 1 and 2 (AdipoR1 and AdipoR2) as well as the leptin receptor (Ob-R) has been recognized in human adrenal tumors. The authors of the present study were the first to compare the expression of these receptors in histopathologically distinct adrenal tumors. MATERIAL AND METHODS: The study encompassed tissue specimens of 128 patients with adrenal tumors (28 adrenal cortical adenomas (CA), 35 cortical nodular hyperplasia tumors (CNH), 20 cortical carcinomas (CC), 40 pheochromocytomas (PHEO), 5 malignant pheochromocytomas (PHEOM)) operated on at a single clinical center. The expression of the adiponectin receptors AdipoR1 and AdipoR2 as well as the leptin receptor Ob-R was assessed by immunohistochemistry. The results were correlated with body mass index (BMI) and gender of the patients. RESULTS: AdipoR1 expression was significantly higher in cortical cancers (p < 0.001) and pheochromocytomas (p < 0.001) as compared to benign cortical tumors. AdipoR2 expression was significantly higher in cortical carcinomas as compared to cortical adenomas and hyperplasia tumors (p = 0.01), and also significantly higher in pheochromocytomas in comparison to adrenocortical cancers (p = 0.004). Leptin receptor expression was absent or minimal in half of nodular hyperplasia tumors and adrenal cortex adenomas. This receptor’s expression was significantly higher in adrenocortical cancers (p = 0.038). In pheochromocytomas this receptor was expressed more abundantly than in adrenocortical cancers (p = 0.004). CONCLUSIONS: These novel findings suggest that adiponectin and leptin receptors could play a regulatory role in human adrenal neoplasms.