Abstract 4416: The pre-neoplastic lesion, mucin-depleted foci, reveals as de novo high-grade dysplasia in rat colon carcinogenesis

Abstract

Abstract Aberrant crypt foci (ACF) and mucin-depleted foci (MDF) have recently been recognized as the pre-neoplastic lesions in the colon of carcinogen-treated rodents. In the present study, we analyzed the sequential development of ACF and MDF histopathologically in the colon of rats from 5 to 40 weeks after DMH treatment. The number of ACF per colon increased over time during the experiment, and was much more than the numbers of tumor, while the number of MDF per colon remained unchanged from the early stage (the 5th week after carcinogen exposure), and approximate to that of tumor. The incidence of ACF, which was much higher than that of tumor, also increased gradually in a time-dependent way. The incidence of MDF, however, was similar to that of tumor and did not have significant change during the whole experiment. No the lesion as dysplasia with high-grade (DHG) or adenocarcinoma (AC) was found in any large ACF from the 5th to 40th week histopathologically, whereas all of the large MDF showed DHG or AC. Even at 5 weeks, MDF shows the appearance as DHG. We classified to two forms of MDF, a flat and a protruded MDF. At the 40 weeks, the number of a flat MDF per colon decreased significantly compared with that in the 20 weeks (p<0.05), but number of a protruded MDF per colon increased (p<0.01), and the percentage of DHG in a protruded MDF decreased but that of AC increased remarkably. In conclusion, MDF might develop into cancer through the so-called “de novo cancer” pathway. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4416. doi:1538-7445.AM2012-4416