Prevention of initiation and promotion of colon cancer by dietary fiber and design of highly functional dietary fiber.

本研究的目的是通过电离辐射建立大鼠结肠癌模型，并比较膳食纤维喂养与化学诱导的结肠癌模型对肿瘤发生的影响。我们首次通过电离辐射在大鼠结肠粘膜上成功地形成了癌前病变军团--异常隐窝病灶(ACF)。与化学诱导的ACF相比，辐射诱导的ACF的特性是低频的，但与化学诱导的ACF相比，高发酵膳食纤维甜菜纤维在化学模型中抑制了ACF，而在辐射模型中没有。在化学模型中，一种低可发酵的、可溶的纤维在仅仅喂食纤维之前阻止了结肠ACF的发展，但在致癌物的挑战之后并不能阻止ACF的发展。此外，利用化学诱导的癌症模型，结肠发酵的产物丁酸可以防止ACF在大鼠结肠中的发展。

The aims of this study were to establish a model of colon cancer by ionizing radiation in rats and to compare the effects of dietary fiber feeding on cancer development with those in a chemically-induced colon cancer model. We first succeed to develop precancerous legion, aberrant crypt foci (ACF), in rat colonic mucosa by ionizing radiation. The properties of radiation-induced ACF were low frequency, but high multiplicity compared with the chemically induced ACF Feeding of a highly fermentable dietary fibers, sugarbeet fiber, suppressed ACF in the chemical model, but not the radiation model. In the chemical model, a low fermentable, soluble fiber prevent the development of colonic ACF just feeding fiber before, but not after a challenge of carcinogen. Also, a product of the colonic fermentation, butyric acid, prevented the development of ACF in the rat colon using the chemically-induced cancer model.