HUMAN PROXIMAL TUBULAR EPITHELIAL-CELLS EXPRESS SOMATOSTATIN - REGULATION BY GROWTH-FACTORS AND CAMP

Somatostatin modulates several renal tubular cell functions, including gluconeogenesis and proliferation. In this study, we demonstrate that cultured human proximal tubular epithelial cells (PTEC) express somat ostatin. We also demonstrate positive and negative regulation of PTEC somatostatin production. We found that PTEC derived from 14 different human donors consistently expressed somatostatin mRNA and/or peptide a s detected by RT-PCR and enzyme-linked immunoassay. Furthermore, North ern blot analysis revealed that PTEC express the same size mRNA transc ript (750 nucleotides) as human thyroid carcinoma (TT) cells. The PTEC mitogens, epidermal growth factor (EGF) and hydrocortisone, inhibit P TEC somatostatin secretion, whereas forskolin (a direct stimulator of adenylate cyclase) and fetal bovine serum stimulate secretion. These f indings raise the possibility that renal-derived somatostatin modulate s tubular cell function in an autocrine/paracrine manner. Manipulation of this pathway may lead to novel methods with which to alter tubular cell proliferation and function in vivo.