Ishigaki Y, Yasuda K, Hashimoto N, Hayakawa J, Hiai H, Nikaido O
Department of Radiation Biology, Faculty of Pharmaceutical Sciences, Kanazawa University, Japan.
J Radiat Res. 1998 Jun;39(2):119-27. doi: 10.1269/jrr.39.119.
To gain an insight into the relationship between UVB-carcinogenesis and natural killer activity, we examined ultraviolet light-induced carcinogenesis in mice with high natural killer, activity (KSN) and mice with natural killer deficiency (KSN-bg). We exposed mice six times a week to three levels of daily ultraviolet B (UVB) doses; 320, 160 and 0 J/m2/day. During the latency period of skin tumor development in KSN mice, we detected no suppression of the natural killer activity at both 320 and 160 J/m2/day. Even at 1340 J/m2/day, we could not detect any significant suppression of NK activity in KSN mice. When we irradiated spleen cells in vitro, we observed NK activity suppression. Next, we compared the carcinogenic effects of UVB-irradiation on KSN and KSN-bg mice. At 320 J/m2/day, we detected no significant differences between them. In contrast, at 160 J/m2/day, KSN-bg mice showed a significantly higher rate of skin tumor induction than KSN mice (p < 0.05). Most UVB-induced tumors were squamous cell carcinoma, the rest were spindle cell carcinoma, papilloma and mixed type. Our results suggest that NK activity plays a protective role against UVB-carcinogenesis from low daily-doses of UVB-irradiation.
为深入了解紫外线B致癌作用与自然杀伤细胞活性之间的关系，我们研究了高自然杀伤细胞活性的小鼠（KSN）和自然杀伤细胞缺陷的小鼠（KSN-bg）在紫外线诱导下的致癌情况。我们每周对小鼠进行六次照射，设置三个每日紫外线B（UVB）剂量水平：320、160和0焦耳/平方米/天。在KSN小鼠皮肤肿瘤发生的潜伏期内，我们发现在320和160焦耳/平方米/天的剂量下，自然杀伤细胞活性均未受到抑制。即使在1340焦耳/平方米/天的剂量下，我们也未在KSN小鼠中检测到自然杀伤细胞活性有任何显著抑制。当我们在体外照射脾细胞时，观察到了自然杀伤细胞活性的抑制。接下来，我们比较了UVB照射对KSN和KSN-bg小鼠的致癌作用。在320焦耳/平方米/天的剂量下，我们未发现它们之间有显著差异。相比之下，在160焦耳/平方米/天的剂量下，KSN-bg小鼠的皮肤肿瘤诱发率显著高于KSN小鼠（p < 0.05）。大多数UVB诱导的肿瘤为鳞状细胞癌，其余为梭形细胞癌、乳头状瘤和混合型。我们的结果表明，自然杀伤细胞活性对低剂量每日UVB照射所致的UVB致癌作用具有保护作用。
