Secretogranin III in human neuroendocrine tumours

Background Different epitopes of the granin family of proteins, chromogranin (Cg) A, CgB and secretogranin (Sg) II, have been demonstrated in normal human pancreas, gastrointestinal tract, adrenal medulla and in several neuroendocrine tumours (NETs). SgIII has been recently reported in endocrine pancreas. The aim of the present study was to examine the expression of SgIII in different NETs and compare it with the expression of CgA, CgB and SgII epitopes. Material and methods Tissue specimens from 47 NETs were analyzed. Antibodies to CgA 250–284, CgB 244–255, SgII 172–186 (C-terminal secretoneurin) and SgIII 348–361 were used for immunostaining. Results SgIII was expressed in 41 of 47 NETs. The expression of SgIII agreed well with that of CgA, CgB and SgII, with exceptions of phaeochromocytomas, where more CgB and SgII immunoreactive cells were observed and parathyroid adenomas, which were only stained by CgA. In rectal NETs more cells expressed SgIII than CgA. Conclusions This is the first report on SgIII expression in various NETs. A majority of tumours studied displayed SgIII immunostaining, which indicates a functional relationship with the other granins.