Detection of Ob-receptor in human adrenal neoplasms and effect of leptin on adrenal cell proliferation

Leptin, a hormone mainly secreted from adipose tissue, communicates a metab olic signal to the adrenal gland. Ob-Receptor (Ob-R) expression was reporte d in rat, mice and human adrenal glands. This study intended to investigate possible differences in the Ob-R expression acid distribution of Ob-R prot ein in human adrenal tumors as compared to normal adrenal tissue. Prolifera tive effects of leptin were analyzed in the human adrenocortical carcinoma cell line (NCl-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 tu mor cell line (NCl-H295) and normal tissue. In contrast the Ob-R isoform B2 19.2 was absent in the carcinoma cell line and in most of the adrenal tumor s (n = 5), whereas it was present in normal adrenals. The Ob-R protein coul d be demonstrated in benign and malignant adrenocortical tumors. Pheochromo cytomas showed only a weak immunostaining with the human Ob-R antibody. Hum an leptin did not affect the proliferation or variability of adrenal tumor cells as demonstrated by [H-3]-thymidine assay and WST-1 test. In conclusio n, although functional leptin receptors are expressed in human adrenal tumo rs, leptin does not regulate tumor cell proliferation.