glucagon-like-peptide-1 and Carcinoid-Tumor

Tumor-induced hypoglycemia (TIH) is a rare clinical entity that may occur in patients with diverse kinds of tumor lineages and that may be caused by different mechanisms. These pathogenic mechanisms include the eutopic insulin secretion by a pancreatic islet β-cell tumor, and also the ectopic tumor insulin secretion by non-islet-cell tumor, such as bronchial carcinoids and gastrointestinal stromal tumors. Insulinoma is, by far, the most common tumor associated with clinical and biochemical hypoglycemia. Insulinomas are usually single, small, sporadic, and intrapancreatic benign tumors. Only 5-10% of insulinomas are malignant. Insulinoma may be associated with the multiple endocrine neoplasia type 1 in 4-6% of patients. Medical therapy with diazoxide or somatostatin analogs has been used to control hypoglycemic symptoms in patients with insulinoma, but only surgical excision by enucleation or partial pancreatectomy is curative. Other mechanisms that may, more uncommonly, account for tumor-associated hypoglycemia without excess insulin secretion are the tumor secretion of peptides capable of causing glucose consumption by different mechanisms. These are the cases of tumors producing IGF2 precursors, IGF1, somatostatin, and glucagon-like peptide 1. Tumor autoimmune hypoglycemia occurs due to the production of insulin by tumor cells or insulin receptor autoantibodies. Lastly, massive tumor burden with glucose consumption, massive tumor liver infiltration, and pituitary or adrenal glands destruction by tumor are other mechanisms for TIH in cases of large and aggressive neoplasias.

Topics: Autoantibodies; Bronchial Neoplasms; Carcinoid Tumor; Gastrointestinal Neoplasms; Gastrointestinal Stromal Tumors; Glucagon-Like Peptide 1; Humans; Hypoglycemia; Insulin-Like Growth Factor I; Insulin-Like Growth Factor II; Insulinoma; Neoplasms; Pancreatic Neoplasms; Paraneoplastic Syndromes; Receptor, Insulin; Somatostatin

We have previously demonstrated that gastric and intestinal endocrine cell (End-cell) marker expression is important for assessment of the histogenesis of endocrine cell tumors. However, the End-cell phenotypes of carcinoid tumors in the rectum remain largely unclear. We therefore examined marker expression of rectal carcinoid tumors. We evaluated 20 rectal carcinoid tumors (as well as 8 from the stomach for comparison) phenotypically, using gastrin, gastric inhibitory polypeptide (GIP) and glucagons-like peptide-1 (GLP-1) as End-cell markers. Rectal carcinoid tumors were divided into 3 endocrine-gastric (e-G), 16 endocrine-gastric-and-intestinal mixed (e-GI), 1 endocrine-intestinal (e-I), and 0 endocrine-null (e-N) types, thus 19 (e-G+ e-GI types, 95%) had gastric phenotypic expression, while 17 (e-GI+ e-I types, 85%) harbored intestinal elements. Stomach carcinoid tumors were classified as 6 e-G and 2 e-N types, respectively. In conclusion, most rectal carcinoid tumors exhibited the e-GI type, suggesting the importance of gastric End-cell marker expression for histogenesis of the rectal carcinoid tumors. Further studies of pathological and biological analyses are needed to clarify the histogenesis of the carcinoid tumors.

Topics: Animals; Biomarkers, Tumor; Carcinoid Tumor; Endocrine Cells; Female; Gastric Inhibitory Polypeptide; Gastrins; Glucagon-Like Peptide 1; Humans; Immunohistochemistry; Male; Middle Aged; Phenotype; Rectal Neoplasms

Glucagon-like peptide 1 (GLP-1), an insulinotropic hormone normally synthesised in the intestinal mucosa and released in response to a meal, is essential for normal glucose homoeostasis. There is much interest in the use of GLP-1 to treat diabetes, since the risk of hypoglycaemia is thought to be low. We report an instance of a 45-year-old woman with a GLP-1 and somatostatin secreting neuroendocrine tumour who presented with reactive hypoglycaemia and hyperglycaemia, but who was subsequently cured by surgery. This case, of a neuroendocrine tumour secreting GLP-1 and causing reactive hypoglycaemia, indicates a potential adverse effect of GLP-1 therapy for diabetes.

Topics: Blood Glucose; Carcinoid Tumor; Diabetes Complications; Female; Glucagon; Glucagon-Like Peptide 1; Glucose Tolerance Test; Humans; Hypoglycemia; Hysterectomy; Middle Aged; Ovarian Neoplasms; Peptide Fragments; Protein Precursors; Somatostatin