Background: The tripeptide pyroGlu-His-GlyOH (pEHG), isolated from intestinal extracts (1), suppresses growth of human colonic epithelial cells and human colorectal adenocarcinoma cells (HT-29) both in vitro and in vivo. The present study represents the first attempt to relate alterations in relevant gene expression to the effect on cell growth.
Materials and methods: Northern blot with RNA, extracted from HT-29 cells exposed to pEHG, was hybridised with c-fos and c-myc probes.
Results: c-fos gene expression was doubled in HT-29 cells after 20 minutes of incubation with pEHG and decreased to half the initial value after 2 hours. The increase at 20 minutes was concentration-dependent at a peptide concentration range from 10(-6)-10(-12) M. The expression of the oncogene c-myc showed only marginal alternations at the concentrations and times tested.
Conclusion: The colon mitosis-inhibiting peptide pEHG increases gene expression of c-fos, but not that of c-myc.