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.
Department of Internal Medicine, Shiga University of Medical Science, Otsu, Japan.
M
M
Fukuda
Y
Y
Fujiyama
M
M
Sasaki
A
A
Andoh
T
T
Bamba
T
T
Fushiki
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