Induction of insulin release in fibroblasts transfected with genomic rat islet DNA

L cells (tk-) were cotransfected with total genomic rat islet DNA and a plasmid containing thymidine kinase gene (ptk). Transfectants were tested for their ability to release insulin into the medium. At least 10% of the colonies contained immunoreactive insulin (IRI) during the initial two weeks. The insulin secreted competed linearly with rat insulin in RIA, the majority of the insulin antigenicity comigrating with rat insulin on G-50 Sephadex chromatography. With continuing propagation the IRI activity diminished; however 3 selected cultures demonstrated increased secretion of IRI following stimulation with glucose. These findings indicate that glucose-induced insulin secretion can be obtained in non-beta cells; however the frequency of success was below one stable transfection for every 5 X 10(8) Ltk- cells exposed to the transfection procedure.