Matsumoto T, Ando K, Koike S
Section of Laboratory Animals and Plants, National Institute of Radiological Sciences, Chiba, Japan.
Cancer Res. 1988 Jun 1;48(11):3031-4.
We have previously reported that abdominal irradiation prior to i.v. injection of syngeneic tumor cells reduced metastases in lung. Our report described an investigation of the significance of intestinal organisms in the radiation effect. We found that eliminating intestinal organisms with antibiotics totally abolished the radiation effect. Monoassociation of germ-free mice revealed that the radiation effect was observable only for Enterobacter cloacae, never for Streptococcus faecium, Bifidobacterium adlesentis, or Escherichia coli. After abdominal irradiation of regular mice, E. cloacae multiplied in cecal contents, adhered to mucous membranes, invaded the cecal wall, and translocated to mesenteric lymph nodes. Intravenous administration of E. cloacae in place of abdominal irradiation inhibited metastases. E. cloacae-monoassociated mice developed fewer metastases than germ-free mice, and the reduction was further enhanced by abdominal irradiation. We concluded that abdominal irradiation caused the invasion of E. cloacae from the mucous membrane of the intestine and inhibited formation of lung metastases.
我们之前报道过，在静脉注射同基因肿瘤细胞之前进行腹部照射可减少肺部转移。我们的报告描述了一项关于肠道微生物在辐射效应中的意义的研究。我们发现，用抗生素消除肠道微生物会完全消除辐射效应。对无菌小鼠进行单菌定植研究发现，只有阴沟肠杆菌能观察到辐射效应，而粪肠球菌、青春双歧杆菌或大肠杆菌均无此效应。对正常小鼠进行腹部照射后，阴沟肠杆菌在盲肠内容物中繁殖，粘附于粘膜，侵入盲肠壁，并转移至肠系膜淋巴结。静脉注射阴沟肠杆菌代替腹部照射可抑制转移。与无菌小鼠相比，单定植阴沟肠杆菌的小鼠发生的转移较少，腹部照射进一步增强了这种减少。我们得出结论，腹部照射导致阴沟肠杆菌从肠道粘膜侵入，并抑制肺转移的形成。
