Abstract
Pheochromocytomas are tumors that may produce a variety of substances in addition to catecholamines. To date, among several cases of systemic inflammatory syndrome associated with interleukin-6 (IL-6) secretion, IL-6-producing pheochromocytomas, have been reported. However, the mechanism underlying IL-6 oversecretion in these cases has not yet been clarified. This report describes a patient with pheochromocytoma who exhibited pyrexia and marked inflammatory signs including C-reactive protein elevation. The inflammatory symptoms were easily controlled by the administration of loxoprofen, a nonsteroidal anti-inflammatory drug. The plasma concentration of IL-6 and 11-d-TXB2 , a stable metabolite of thromboxane A2 (TXA2 ), were significantly elevated in parallel with an elevation of norepinephrine in the samples obtained by selective venous sampling. A left adrenalectomy was performed, and the acute inflammatory symptoms naturally diminished without loxoprofen. Cultured tumor cells obtained from the resected specimen spontaneously released IL-6, and indomethacin inhibited the IL-6 release. According to a cDNA microarray analysis, mRNA of protein kinase C-δ (PKC-δ), prostaglandin D synthase, and arachidonate release-relating enzymes were significantly overexpressed in the tumor tissue in comparison to the adjacent nontumor tissue. The constitutive phosphorylation of PKC-δ was observed in the tumor tissue. These results strongly suggest that the systemic inflammatory syndrome in IL-6-producing pheochromocytoma, at least in part, is caused by the overexpression of PKC-δ, resulting in an excess of arachidonate derivatives such as prostaglandins.
Key words
adrenal mass - cytokines - pheochromocytoma
References
Endocrinology 5th edn . Phyladelphia: Elsevier 2006: 2501-2534
The Pharmacological Basis of Therapeutics 11th edn . New York: McGraw-Hill 2006: 653-670
Correspondence
tokuda@ncgg.go.jp
