Comparison of the antiproliferative effects of colon mitosis inhibitor, thyroliberin and the somatostatin analog octreotide on rat colonic mucosal epithelial cells.

The effects of colon mitosis inhibitor (CMI), thyroliberin (TRH), and the somatostatin analogue octreotide (SMS 201-995) on rat colonic mucosal epithelial cell proliferation were studied. As an index of cell proliferation the incorporation of bromodeoxyuridine (BrDU) into cell nuclei was used. It was found that all three peptides inhibited the colonic mucosal epithelial cells proliferation, but the time course of inhibition was different. The effect of SMS 201-995 occurred 12 h after the peptide injection, while CMI and TRH suppressed the proliferation after 24 h. These observations suggest that the mechanisms of the antiproliferative actions of somatostatin and of related tripeptides CMI and TRH are different.