Local renin-angiotensin system is involved in K+-induced aldosterone secretion from human adrenocortical NCI-H295 cells

NCI-H295, a human adrenocarcinoma cell line, has been proposed as a model s ystem to define the role of the renin-angiotensin system in the regulation of aldosterone production in humans. Because the precise cellular localizat ion of the components of the renin-angiotensin system in human adrenal cort ical cells remains unclear, we investigated their localization in this defi ned cell system. NCI-H295 cells expressed both angiotensinogen and renin as shown by reverse transcriptase polymerase chain reaction and immunohistoch emistry. Human angiotensin-converting enzyme (ACE) was not detectable by im munocytochemistry, ACE binding, or reverse transcriptase polymerase chain r eaction. However, 3.5 mmol/L K+ stimulated the formation of both angiotensi n I and angiotensin II 1.9- and 2.5-fold, respectively, and increased aldos terone release 3.0-fold. The K+-induced stimulation of aldosterone release was decreased by captopril and enalaprilat (24% and 26%, respectively) and by the angiotensin type 1 (AT(1))-receptor antagonist losartan (28%). Angio tensin II-induced stimulation of aldosterone release was abolished by losar tan treatment. Specific [I-125]Sar1-angiotensin II binding was detected by receptor autoradiography. The binding of [I-125]Sar(1)-angiotensin II was c ompletely displaced by the AT(1) antagonist losartan but not by the AT(2) r eceptor ligand PD 123319, confirming the expression of angiotensin II AT(1) receptors in NCI-H295 cells. Our results demonstrate that NCI-H295 cells e xpress most of the components of the renin-angiotensin system. Our failure to detect ACE, however, suggests that the production of angiotensin II in N CI-H295 cells may be ACE independent. NCI-H295 cells are able to produce an giotensin II, and K+ increases aldosterone secretion in part through an ang iotensin-mediated pathway. The production of angiotensin II in NCI-H295 cel ls demonstrates that this human cell line can be useful to characterize the role of locally produced angiotensin II in the regulation of aldosterone r elease.