Early oncogene mRNA expression in HT-29 cells treated with the endogenous colon mitosis inhibitor pyroglutamyl-histidyl-glycine.

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.