Sumi Y, Miyakawa M
Cancer Res. 1979 Jul;39(7 Pt 1):2733-6.
This study was designed to clarify the role of gut microflora in tumorigenesis by a comparison of tumor production between male germ-free and conventional Wistar rats given N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), 100 microgram/ml in drinking water. Ninety-one % of conventional MNNG-treated rats that died or were killed by Day 314 of the experiment developed tumors in the gastrointestinal tract, whereas only 17% of germ-free treated rats developed such tumors. In addition, large tumors, some 5 cm or more in diameter, were frequently observed in the conventional rats, whereas only small tumors 0.4 to 1.2 cm in diameter were present in the germ-free rats. Furthermore, multiple tumors including double tumors were often found in the conventional rats, while such tumors never appeared in the germ-free rats. The results suggest that gut microflora might exert a promoting influence on tumorigenesis by MNNG in the gastrointestinal tract. The promoting influence of the microflora in conventional rats might not be of a simple nature, since the influence of a variety of factors modified by the micorflora on tumorigenesis by MNNG p.o. is unavoidable.
本研究旨在通过比较饮用含100微克/毫升N-甲基-N'-硝基-N-亚硝基胍（MNNG）的饮用水的雄性无菌Wistar大鼠和常规Wistar大鼠的肿瘤发生情况，阐明肠道微生物群在肿瘤发生中的作用。在实验第314天死亡或被处死的常规MNNG处理大鼠中，91%在胃肠道发生了肿瘤，而无菌处理大鼠中只有17%发生了此类肿瘤。此外，在常规大鼠中经常观察到直径约5厘米或更大的大肿瘤，而无菌大鼠中仅存在直径0.4至1.2厘米的小肿瘤。此外，在常规大鼠中经常发现包括双肿瘤在内的多个肿瘤，而在无菌大鼠中从未出现过此类肿瘤。结果表明，肠道微生物群可能对MNNG在胃肠道中的肿瘤发生起到促进作用。常规大鼠中微生物群的促进作用可能并非简单的性质，因为微生物群改变的多种因素对经口给予MNNG的肿瘤发生的影响是不可避免的。
