Molecular basis of transdifferentiation of pancreas to liver

The appearance of hepatic foci in the pancreas has been described in animal experiments and in human pathology. Here we show that pancreatic cells can be converted into hepatocytes by treatment with a synthetic glucocorticoid , dexamethasone. This occurs both in a pancreatic cell line, AR42J-B13, and in organ cultures of pancreatic buds from mouse embryos. We have establish ed several features of the mechanism behind this transdifferentiation. We s how that a proportion of the hepatocytes arises directly from differentiate d exocrine-like cells, with no intervening cell division. This conversion i s associated with induction of the transcription factor C/EBP beta and the activation of differentiated hepatic products. Transfection of C/EBP beta i nto the cells can provoke transdifferentiation; conversely, a dominant-nega tive form of C/EBP beta can inhibit the process. These results indicate tha t C/EBP beta is a key component that distinguishes the liver and pancreatic programmes of differentiation.