Monitor peptide (rat pancreatic secretory trypsin inhibitor) directly stimulates the proliferation of the nontransformed intestinal epithelial cell line, IEC-6.
OBJECTIVE
The growth-stimulating activity of monitor peptide [rat pancreatic secretory trypsin inhibitor (PSTI)-61] was evaluated in the rat intestinal epithelial cell line IEC-6. In response to food intake, monitor peptide induces cholecystokinin release and the subsequent secretion of pancreatic enzyme into the rat small intestine.


METHODS
Monitor peptide was purified from rat bile-pancreatic juice. The proliferation of IEC-6 cells was determined by both counting cell number and [3H]-thymidine incorporation. Ornithine decarboxylase (ODC) activity was assessed by radiometric technique using L-[1-14C]-ornithine.


RESULTS
Monitor peptide (10(2)-10(5) ng/ml) induced a significant increase in the incorporation of [3H]-thymidine into IEC-6 cells, and this effect was observed in a dose-dependent manner. A significant increase in the cell number was also observed. An antibody specific for the synthetic NH2-terminal fragment of monitor peptide completely abrogated the growth-stimulating effects of this peptide. In addition, monitor peptide effectively increased the ODC activity of IEC-6 cells.


CONCLUSIONS
These results indicate that monitor peptide stimulates the growth of intestinal epithelial cells, and suggest that polyamine metabolism may be involved in this mechanism of growth induction.
Fukuda
M
M
Department of Internal Medicine, Shiga University of Medical Science, Otsu, Japan.
Fujiyama
Y
Y
Sasaki
M
M
Andoh
A
A
Bamba
T
T
Fushiki
T
T
D000818:Animals; D002452:Cell Count; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D006133:Growth Substances / Q000494:pharmacology*; D036341:Intercellular Signaling Peptides and Proteins; D007413:Intestinal Mucosa / Q000166:cytology* / Q000187:drug effects / Q000254:growth & development; D007421:Intestine, Small / Q000166:cytology / Q000187:drug effects; D008297:Male; D010187:Pancreatic Hormones / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D013268:Stimulation, Chemical; D013936:Thymidine; D014359:Trypsin Inhibitor, Kazal Pancreatic / Q000494:pharmacology*
D006133:Growth Substances; D036341:Intercellular Signaling Peptides and Proteins; D010187:Pancreatic Hormones; C504705:Spink1 protein, rat; D014359:Trypsin Inhibitor, Kazal Pancreatic; D013936:Thymidine