Distribution of insulin mRNA transcripts within the human body

Here we sought evidence for the existence of insulin mRNA-producing cells outside the human pancreas. Commercially available complementary DNA (cDNA) arrays prepared from 72 different types of adult human tissues were screened by PCR for transcripts encoding insulin, and other classic pancreatic hormones. Insulin mRNA transcripts were detected by standard PCR in the pancreas, stomach, pylorus region of the stomach, and the duodenum; and additionally by nested PCR in the jejunum, ileum and cecum, but not in other body tissues including the brain and colon. Most of these tissues also variably expressed mRNA transcripts for amylase α2B, amylin, glucagon, somatostatin, and pancreatic polypeptide. In summary, using sensitive PCR methods we have provided evidence for the presence of rare insulin mRNA-expressing cells within the stomach, small intestine, and cecum. Their role at these sites may be to support classical enteroendocrine cells as sentinels to sense and monitor gastric contents passing into and through the bowel.