Growth factor-mediated proliferation and differentiation of insulin-producing INS-1 and RINm5F cells: identification of betacellulin as a novel beta-cell mitogen.
It is not clear which growth factors are crucial for the survival, proliferation, and differentiation of pancreatic beta-cells. We used the relatively differentiated rat insulinoma cell line INS-1 to elucidate this issue. Responsiveness of the DNA synthesis of serum-starved cells was studied to a wide variety of growth factors. The most potent stimulators were PRL, GH, and betacellulin, a member of the epidermal growth factor (EGF) family that has not previously been shown to be mitogenic for beta-cells. In addition to these, only vascular endothelial growth factor, insulin-like growth factor-1 and -2, had significant mitogenic activity, whereas hepatocyte growth factor, nerve growth factor-beta, platelet-derived growth factors, basic fibroblast growth factor, EGF, transforming growth factor-alpha (TGF-alpha), neu differentiation factor, and TGF-beta were inactive. None of these factors affected the insulin content of INS-1 cells. In contrast, certain differentiation factors, including nicotinamide, sodium butyrate, activin A, and 1,25-dihydroxyvitamin D3 inhibited the DNA synthesis and increased the insulin content. Also all-trans-retinoic acid had an inhibitory effect on cell DNA synthesis but no effect on insulin content. From these findings betacellulin emerges as a novel growth factor for the beta-cell. Half-maximal stimulation of INS-1 DNA synthesis was obtained with 25 pM betacellulin. Interestingly, betacellulin had no effect on RINm5F cells, whereas both EGF and TGF-alpha were slightly mitogenic. These effects may possibly be explained by differential expression of the erbB receptor tyrosine kinases. In RINm5F cells a spectrum of erbB gene expression was detected (EGF receptor/erbB-1, erbB-2/neu, and erbB-3), whereas INS-1 cells showed only expression of EGF receptor. Expression of the erbB-4 gene was undetectable in these cell lines. In summary, our results suggest that the INS-1 cell line is a suitable model for the study of beta-cell growth and differentiation because the responses to previously identified beta-cell mitogens were essentially similar to those reported in primary cells. In addition, we have identified betacellulin as a possible modulator of beta-cell growth.
Huotari
M A
MA
Transplantation Laboratory, Haartman Institute and Children's Hospital, University of Helsinki, Finland. mari.huotari@helsinki.fi
Palgi
J
J
Otonkoski
T
T
D000818:Animals; D066259:Betacellulin; D002454:Cell Differentiation / Q000187:drug effects*; D002455:Cell Division / Q000187:drug effects*; D002460:Cell Line; D004247:DNA / Q000096:biosynthesis; D066246:ErbB Receptors / Q000235:genetics; D015870:Gene Expression; D006133:Growth Substances / Q000494:pharmacology*; D019382:Human Growth Hormone / Q000494:pharmacology; D006801:Humans; D007328:Insulin / Q000096:biosynthesis*; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D007335:Insulin-Like Growth Factor II / Q000494:pharmacology; D007340:Insulinoma; D036341:Intercellular Signaling Peptides and Proteins; D007515:Islets of Langerhans / Q000166:cytology* / Q000187:drug effects; D008934:Mitogens / Q000494:pharmacology*; D010190:Pancreatic Neoplasms; D011388:Prolactin / Q000494:pharmacology; D051381:Rats; D011994:Recombinant Proteins / Q000494:pharmacology
C587851:BTC protein, human; D066259:Betacellulin; C587853:Btc protein, rat; D006133:Growth Substances; D007328:Insulin; D036341:Intercellular Signaling Peptides and Proteins; D008934:Mitogens; D011994:Recombinant Proteins; D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D011388:Prolactin; D004247:DNA; D066246:ErbB Receptors