[Aberrant crypt foci as biomarkers in chemoprevention for colorectal cancer].

Aberrant crypt foci (ACF) are small lesions identifiable in whole-mount preparations of normal-appearing human colonic mucosa with the aid of methyleneblue staining under stereoscopic microscope. Highly frequent mutations of K-ras genes were found, and increased proliferative activities were also observed. Therefore, K-ras gene mutation may have some role in formation of ACF. Using rat experimental model, formation of ACF was shown to be enhanced by cancer promoters (such as secondary bile acids), and to be suppressed by chemopreventive agents (deoxycholic acid and aspirin). Based on these findings, ACF are considered to be precursors of colon cancer. We demonstrated that ACF are the precursors of adenoma-carcinoma sequence. Moreover, we showed that ACF may be suitable biomarkers of chemopreventive agents for colon cancers.