Expression and significance of aberrant crypt foci in rat colon cancer model

Abstract

Objective To observe the development of aberrant crypt foci(ACF)in Wistar rat colon cancer model and to evaluate the correlation between ACF and tumor. Methods Sixty adult Wistar rats were randomly divided into 2 groups. Thirty Wistar rats in group A were subjected to the subcutaneous injection of 1,2- dimethylhydrazine(DMH)(20 mg/kg, once every week for 18 weeks), and those in group B were intraperitoneally injected with physiological saline for one week as the normal control group. The rats in groups A and B group were killed at 6th, 12th and 18th week respectively, and served as three subgroups. The colon tissues subject to methylene blue staining were observed under a microscope. Results ACF were distributed in the middle and distal colon(mostly 50%-80% of the cecum), and 12 tumors were seen. Four tumors were poorly differentiated mucinous adenocarcinoma, and located in the proximal colon(10%-20% of the cecum). In the rest 8 tumors, three were adenoma and 5 highly differentiated adenocarcinoma, and located in 50%-80% of the distal colon. The number of ACF in the colorectum could significantly influence the incidence of colorectal cancer. In group A of rats with ACF in colorectal, the pathological examination showed that the incidence of colonic lesions was 46.67%(14/30)and that of rectal cancer was 16.67%(5/30) respectively, which was significantly higher than in the rats without ACR odds ratio(OR)[95% confidence interval(CI)]: 13.352(5.529-32.581)and 6.582(1.374-17.494),P< 0.05]. Conclusion The number of ACF in the colorectum has significant influence on the development of colorectal cancer. Key words: Aberrant crypt foci; Colorectal cancer; Expression