Expression of neuropeptides and other neuroendocrine markers in human phaeochromocytomas

Phaeochromocytomas may produce several neuropeptides as they are considered neuroendocrine tumours. Nevertheless, studies are scarce and no clear predictive biologic value has been stablished in the case of neuropeptides expression.

We have investigated immunohistochemically the neuropeptides expression of a serie of 36 phaeochromocytomas: 25 sporadic, seven familial type MEN (multiple endocrine neoplasm) and four familial phaeochromocytomas not associated with MEN syndrome. The reactivity for neuron-specific enolase (NSE), synaptophysin, vasoactive intestinal peptide (VIP), chromogranin A, calcitonin, ACTH, somatostatin and HMB-45 was tested according to the avidin-biotin complex (ABC) method using polyclonal antibodies.

Phaeochromocytomas have a multiple synthetic activity as main neuroendocrine feature. Despite phaeochromocytoma tumour cells heterogeneity chromogranin and synaptophysin are the most common neuropeptides synthesised, as they are associated with the presence of neuroendocrine storage granules. We find a statistically significant higher synthesis of corticotrophin hormone in familial phaeochromocytomas than in sporadic forms, on the contrary the synthesis of VIP is statistically associated with sporadic forms of phaeochromocytomas. We also found a direct relation of ACTH and overexpression and malignant tumours and a positive relationship between NSE and benign forms of phaeochromocytomas.