The glucagonoma syndrome: stimulus-induced plasma responses of circulating glucagon components IRG9000 and IRG3500

Glucagon-like peptide 1 immunoreactivity in gastroentero-pancreatic endocrine tumors: a light- and electron-microscopic study

The preproglucagon gene encodes, in addition to glucagon, two smaller peptides with structural similarity: glucagon-like peptides 1 and 2. Glucagon-like peptide 1 (GLP-1) 7-36 amide is the most powerful incretin candidate. In the present study, GLP-1 immunoreactivity was investigated in tissue specimens of various types of gastroenteropancreatic tumors, and the serum-levels of GLP-1 were assayed. Immunohistochemical staining of 88 tumors revealed GLP-1 immunoreactivity in 17 neoplasias (19.3%), viz., in 7 out of 33 non-functioning tumors, 4 out of 20 gastrinomas, 4 out of 13 insulinomas, 1 out of 3 vasoactive-intestinal-polypeptide (VIP)omas and 1 adrenocorticotropic-hormone (ACTH)-producing tumor. In these tumors, GLP-1-immunoreactive cells were distributed either diffusely, arranged in clusters, or as single cells. All GLP-1-positive tumors were immunoreactive for glucagon or glicentin, 10 tumors were immunoreactive for pancreatic polypeptide, and 8 tumors for insulin. Ultrastructural analysis of 8 GLP-1-positive tumors, with the immunogold technique, demonstrated GLP-1 immunoreactivity mainly in cells resembling the A-cells of the pancreas or the L-cells of the gut. Of the 17 GLP-1-immunoreactive tumors, 15 were primarily located in the pancreas. Additionally, 2 non-functioning tumors of the rectum were GLP-1 immunoreactive. Five tumors were GLP-1 immunoreactive from 9 patients with multiple endocrine neoplasia I syndrome. Patients with GLP-1-immunoreactive tumors were characterized by a significantly lower rate of distant metastases (P < 0.01) and a higher rate of curative resections (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Glucagonoma syndrome

A 53-year-old Japanese man with a skin eruption characteristic of glucagonoma syndrome had had misdiagnoses for 10 years. The plasma glucagon level was not abnormally high on the first admission, and 4 years later the level was elevated as determined by the 30 gm arginine tolerance test. An alpha cell carcinoma detected in the tail of the pancreas was associated with a lymph node metastasis; the skin eruption cleared up 10 days after the partial pancreatectomy with lymphadenectomy. The clinical features of glucagonoma syndrome should be given attention.

Multiple hormone secretion by a human pancreatic glucagonoma in culture

A patient presenting clinically with the glucagonoma syndrome had high plasma glucagon levels (1920 ng/l) and at laparotomy, a pancreatic islet cell tumour was removed. The tumour was dispersed and placed in culture where it remained viable for 63 days. The tumour cells secreted immunoreactive (IR) glucagon at levels up to 2400 ng/l as detected by a C-terminal glucagon specific antibody and 85 400 ngequiv./l as measured by an N-terminal glucagon specific antibody. The difference between these two levels was attributed to the presence of different molecular forms of glucagon measured with the N-terminal specific antibody. IR insulin (up to 302 mU/l) and IR somatostatin (up to 2500 ng/l) were also detected. There was no direct or inverse correlation between different hormone levels. Small but significant levels of N-terminal and C-terminal vasoactive intestinal peptide (VIP) were detected in some cultures but there was no evidence of gastrin or ACTH. Glucagon and somatostatin secretion persisted for the duration of the culture (63 days) but insulin concentrations declined. Incubation of cultures with somatostatin (1 ng/ml) caused a 75% decrease in glucagon levels, while insulin (1000 mU/l) produced a 70% inhibition of somatostatin.