Abstract
BACKGROUNDS & AIM: X-ray is known to cause genetic damage and induce many types of carcinomas. Mouse model for human familial adenomatous polyposis, APC/min mouse, contains a truncating mutation in APC gene and spontaneously developes intestinal adenomas. To elucidate the role of X-ray in the intestinal tumor, we examined the promotion of carcinogenesis in APC/min mouse by X-ray irradiation.
METHODS: APC/min mice and wild-type were irradiated with a single whole body of 5 Gy X-rays at 8 weeks of age. After 20 weeks, all animals were sacrificed.
RESULTS: Total 51.9% cases of X-ray irradiated APC/min mice were highly observed invasive carcinoma in small intestine. 54.5% in male and 48.5% in female were showed adenocarcinoma with invasion to proprial muscle layer. Only 20.3% cases of non-irradiated APC/min mice were observed invasive carcinoma. 28.1% of male and 12.5% of female in non-irradiated APC/min mice were showed invasive carcinoma. There was statistical difference of the occurrence of invasive carcinoma between X-irradiated and non-irradiated APC/min male or female mice (p=0.019, 0.0017, respectively). X-irradiated APC/min mouse showed higher number of invasive carcinoma than non-irradiated mouse in male (p=0.041). The number of polyps did not show any difference between X-irradiated and non-irradiated Apc/min mice. Wild-type mice with or without X-irradiation were not occurred any invasive carcinoma.
CONCLUSIONS: Our results suggested that X-ray irradiation may promote the invasive activity of intestinal tumor in APC/min mouse.
