Glucagon, glicentin, proglucagon, PYY, PP and proPP-icosapeptide immunoreactivities of rectal carcinoid tumors and related non-tumor cells.
Glucagon/PP-related peptides were detected immunohistochemically in 18 out of 22 cases of rectal tumors investigated. The reactive tumors showed prevalence of trabecular or mixed trabecular-acinar structure and moderate staining with Grimelius' silver and lead-hematoxylin. Three of the remaining 4 cases were characterized by reactivity for 5-hydroxytryptamine only, prevalence of a solid nest structural component and intense staining with Grimelius' silver technique and lead-hematoxylin. Fifteen of the 18 glucagon/PP-reactive cases were investigated immunohistochemically with a series of 6 sera directed against different sequences of glucagon, glicentin and proglucagon, and of 7 sera directed against PP, PYY and proPP-icosapeptide. A large spectrum of glucagon-related immunoreactivities, including C-terminus and mid-portion glucagon-immunoreactivity, N- and C-terminus glicentin-immunoreactivity, GLP1- and GLP2-immunoreactivity, were detected in human rectal L cells and most rectal carcinoids. With the exception of a few scattered cells in the rectal mucosa and in 3 tumors, C-terminus glucagon-immunoreactivity was obtained only after trypsin or subtilisin treatment of tissue sections. Both PYY and PP/proPP-like peptide(s) were detected in rectal L cells and carcinoids, with prevalence of PYY in normal cells and PP/proPP-like peptides in tumor cells. It is concluded that the same or closely related hormone/prohormone sequences are synthesized and stored in rectal endocrine cells and carcinoid tumors although differences of quantitative expression, post-translational cleavage or reactivity to antibodies may occur. The usefulness of protease treatments of tissue sections to unmask immunoreactivities of uncleaved propeptides or fixative-denatured peptides is outlined.
D000818:Animals; D002276:Carcinoid Tumor / Q000378:metabolism*; D002417:Cattle; D005934:Glucagon / Q000378:metabolism*; D006801:Humans; D007158:Immunologic Techniques; D009496:Neurotensin / Q000378:metabolism; D010191:Pancreatic Polypeptide / Q000378:metabolism*; D019894:Peptide YY; D010455:Peptides / Q000378:metabolism; D052336:Proglucagon; D011498:Protein Precursors / Q000378:metabolism*; D012004:Rectal Neoplasms / Q000378:metabolism*; D012701:Serotonin / Q000378:metabolism; D013004:Somatostatin / Q000378:metabolism
D010455:Peptides; D011498:Protein Precursors; D019894:Peptide YY; D012701:Serotonin; D009496:Neurotensin; D013004:Somatostatin; D052336:Proglucagon; D010191:Pancreatic Polypeptide; D005934:Glucagon