leptin and Adrenal-Cortex-Neoplasms

Obesity is highly complicated by hypertension and hyperglycemia. In particular, it has been proposed that obesity-related hypertension is caused by adipocyte-derived factors that are recognized as undetermined proteins secreted from adipocytes. Adipocyte-derived factors have been known to be related to aldosterone secretion in the adrenal gland. So far, Wnt proteins, CTRP-1, VLDL, LDL, HDL and leptin have been demonstrated to stimulate aldosterone secretion. In contrast, it has not yet been clarified whether adipocyte-derived factors also affect adrenal cortisol secretion.. In the present study, we investigated the effect of adipocyte-derived factors on cortisol synthase gene CYP11B1 mRNA expression in vitro study using adrenocortical carcinoma H295R cells and mouse fibroblast 3T3-L1cells. Interestingly, adipocyte-derived factors were demonstrated to have the ability to stimulate CYP11B1 mRNA expression.. Since CYP11B1 is well known as a limiting enzyme of cortisol synthesis, our study suggests that adipocyte-derived factors may stimulate cortisol secretion, as well as aldosterone secretion. Taken together, adipocyte-derived factors may be the cause of metabolic syndrome due to their stimulating effects on aldosterone/cortisol secretion. Therefore, the innovation of novel drugs against them may possibly be a new approach against metabolic syndrome.

Topics: Adipocytes; Adrenal Cortex; Adrenal Cortex Neoplasms; Animals; Carcinoma; Cell Line; Cell Line, Tumor; Cytochrome P-450 CYP11B2; Fibroblasts; Gene Expression Regulation; Humans; Hydrocortisone; Leptin; Lipoproteins, LDL; Mice; Proteins; RNA, Messenger; Steroid 11-beta-Hydroxylase; Wnt Proteins; Zona Fasciculata

Obesity has adverse effects on adrenocortical functions. Adipocyte-derived leptin, a biomarker molecule of obesity, may directly control adrenal steroidogenesis via an unclear mechanism.. We studied the mechanism underlying leptin action on adrenal steroidogenesis in human adrenocortical NCI-H295 tumor cell line.. Levels of progesterone, cortisol, and cAMP were determined by ELISA. Western blotting was used to detect protein amounts of P450 side-chain cleavage (P450scc), Janus kinase 2 (JAK2), Akt, and their phosphorylated forms. The mRNA expressions of P450scc and leptin receptors were measured by RT-PCR and real-time PCR. P450scc promoter activity was analyzed with a luciferase reporter system.. Cholera toxin mimicked ACTH action by increasing adrenal cAMP levels and steroid secretion. Leptin did not affect basal release but significantly inhibited ACTH/cholera toxin-induced steroid secretion. The concomitant inhibitions by leptin on cholera toxin-induced protein and ACTH/cholera toxin-induced mRNA expression of P450scc were confirmed. Leptin inhibited ACTH/cholera toxin-induced CYP11A1 promoter activity via a known cAMP-responsive region located between -1.7 and -1.5 kb. Leptin activated phosphorylations of JAK2 and Akt. Inhibitory effects of leptin on ACTH/cholera toxin-induced cAMP levels, CYP11A1 promoter activity, and steroid secretion were blunted by either inhibitor of JAK2 (AG490) or phosphatidylinositol 3-kinase/Akt (wortmannin) as well as inhibitors of cAMP-degrading phosphodiesterases (PDEs), including nonspecific 3-isobutyl-1-methylxanthine and PDE3-specific SKF94836. Leptin failed to affect the inductions of CYP11A1 promoter activity and steroid secretion by PDE-nonhydrolyzable N(6)-monobutyryl-cAMP.. Leptin interferes with ACTH/cAMP signaling, possibly through a cAMP-degrading mechanism involving activation of JAK2, phosphatidylinositol 3-kinase, and PDE3, to down-regulate P450scc expression and consequent adrenal steroidogenesis.

Topics: Adrenal Cortex; Adrenal Cortex Neoplasms; Adrenocorticotropic Hormone; Cell Line, Tumor; Cholera Toxin; Cholesterol Side-Chain Cleavage Enzyme; Cyclic AMP; Gene Expression; Humans; Janus Kinase 2; Leptin; Phosphatidylinositol 3-Kinases; Phosphoric Diester Hydrolases; Phosphorylation; Promoter Regions, Genetic; Protein-Tyrosine Kinases; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-akt; RNA, Messenger; Signal Transduction; Steroids

Leptin, a hormone mainly secreted from adipose tissue, communicates a metabolic signal to the adrenal gland. Ob-Receptor (Ob-R) expression was reported in rat, mice and human adrenal glands. This study intended to investigate possible differences in the Ob-R expression and distribution of Ob-R protein in human adrenal tumors as compared to normal adrenal tissue. Proliferative effects of leptin were analyzed in the human adrenocortical carcinoma cell line (NCI-H295). The full length Ob-R mRNA and the isoforms B219.1 and B219.3 could be demonstrated by RT-PCR in all adrenal tumors (n=8), the tumor cell line (NCI-H295) and normal tissue. In contrast the Ob-R isoform B219.2 was absent in the carcinoma cell line and in most of the adrenal tumors (n=5), whereas it was present in normal adrenals. The Ob-R protein could be demonstrated in benign and malignant adrenocortical tumors. Pheochromocytomas showed only a weak immunostaining with the human Ob-R antibody. Human leptin did not affect the proliferation or variability of adrenal tumor cells as demonstrated by [3H]-thymidine assay and WST-1 test. In conclusion, although functional leptin receptors are expressed in human adrenal tumors, leptin does not regulate tumor cell proliferation.

Topics: Adenoma; Adrenal Cortex Neoplasms; Adrenal Gland Neoplasms; Adrenal Glands; Adult; Carrier Proteins; Cell Division; Cell Survival; Gene Expression; Humans; Immunohistochemistry; Leptin; Middle Aged; Pheochromocytoma; Proteins; Receptors, Cell Surface; Receptors, Leptin; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Tumor Cells, Cultured

Because glucocorticoids stimulate leptin release and, at least in vitro, leptin inhibits cortisol secretion, a feedback system between glucocorticoids and leptin has been proposed. However, in humans and non-human primates there are no in vivo studies to support any role for leptin in the control of the hypothalamic-pituitary-adrenal axis. In this study, we investigated the effect of leptin on (i) ACTH-stimulated secretion of cortisol in six male rhesus monkeys and (ii) basal and forskolin (FSK)-stimulated cortisol secretion by the human adrenal carcinoma cell H295R in vitro.. In vivo studies: after suppression of endogenous ACTH with either dexamethasone (n=6) or a corticotropin-releasing factor (CRF) antagonist (d-Phe CRF(12-41)) (n=3), 1 microg bolus of human ACTH(1-24) was administered to stimulate adrenal cortisol release. Blood samples were collected every 15 min for 3 h. Leptin (1 mg) was infused over 4 h, starting 1 h before ACTH bolus.. NCI-H295R cells were incubated for 6, 12, 24 and 48 h in the absence or presence of 20 micromol/l FSK in combination with leptin (100 ng/ml medium). Cortisol levels in serum and medium were measured by solid phase radioimmunoassay.. Acute leptin infusion to rhesus monkeys did not change basal cortisol levels, peak cortisol levels after ACTH(1-24) or the area under the curve when compared with studies in which leptin was not given. FSK increased cortisol levels in medium at 24 and 48 h, but leptin did not change cortisol release in either control or FSK-stimulated cells.. Short-term leptin infusion affected neither the cortisol response to ACTH in non-human primates in vivo nor cortisol release (basal or FSK stimulated) by H295R cells, in vitro. These data suggest that leptin may not be an acute regulator of primate adrenal cortisol secretion.

Topics: Adrenal Cortex; Adrenal Cortex Neoplasms; Animals; Area Under Curve; Colforsin; Corticotropin-Releasing Hormone; Cosyntropin; Dexamethasone; Humans; Hydrocortisone; Leptin; Macaca mulatta; Male; Mice; Mice, Obese; Radioimmunoassay; Tumor Cells, Cultured