GLUCAGON-LIKE PEPTIDE-1 (GLP-1) MOLECULAR-FORMS IN HUMAN PANCREATIC ENDOCRINE TUMORS RESEMBLE THOSE IN INTESTINE RATHER THAN PANCREAS

Different glucagon-like peptide-1 (GLP-1) molecular forms are produced in the pancreas and the small intestine by differential processing of proglucagon. In this report, molecular forms of GLP-1 in two human pa ncreatic endocrine tumors were studied and compared with those in the pancreas and small intestine. A predominant GLP-1 immunoreactive form in the pancreas was eluted at the position of GLP-1(1-36) amide, where as a predominant immunoreactive form in the ileal mucosa was eluted at the position of GLP-1(7-36) amide. In a glucagonoma, GLP-1 immunoreac tive forms corresponding to GLP-1(7-36) amide and GLP-1(7-37) were pre dominant and immunoreactive forms at the position of GLP-1(1-36) amide and GLP-1(1-37) were minor. In another tumor, an insulinoma, immunore active forms were detected at the positions of GLP-1(7-36) amide, GLP- 1(7-37), GLP-1(1-36) amide and GLP-1(1-37). Thus, the pattern of GLP-1 molecules in pancreatic tumors was not a pancreatic pattern and mimic ked that found in the small intestine or consisted of both the pattern s found in the small intestine and the pancreas. These data suggest th at neoplastic transformation of the islet cells is associated with a s witching in processing phenotype from islet (A) cells to intestinal (L ) cells.