Berton T R, Fischer S M, Conti C J, Locniskar M F
Division of Nutritional Sciences, University of Texas at Austin 78712, USA.
Nutr Cancer. 1996;26(3):353-63. doi: 10.1080/01635589609514491.
To investigate the effect of various levels of corn oil and coconut oil on ultraviolet (UV) light-induced skin tumorigenesis and ornithine decarboxylase (ODC) activity, Sencar and SKH-1 mice were fed one of three 15% (weight) fat semipurified diets containing three ratios of corn oil to coconut oil: 1.0%:14.0%, 7.9%:7.1%, and 15.0%:0.0% in Diets A, B, and C, respectively. Groups of 30 Sencar and SKH-1 mice were fed one of the diets for three weeks before UV irradiation; then both strains were UV irradiated with an initial dose of 90 mJ/cm2. The dose was given three times a week and increased 25% each week. For Sencar mice (irradiated 33 wks for a total dose of 48 J/cm2), tumor incidence reached a maximum of 60%, 60%, and 53% for Diets A, B, and C, respectively, with an overall average of one to two tumors per tumor-bearing animal. For the SKH-1 mice (irradiated 29 wks for a total dose of 18 J/cm2), all diet groups reached 100% incidence by 29 weeks, with approximately 12 tumors per tumor-bearing mouse. No significant effect of dietary corn oil/coconut oil was found for tumor latency, incidence, or yield in either strain. The effect of increasing corn oil on epidermal ODC activity in chronically UV-irradiated Sencar and SKH-1 mice was assessed. Three groups of mice from each strain were fed one of the experimental diets and UV irradiated for six weeks. Sencar mice showed no increase in ODC activity until six weeks of treatment, when the levels of ODC activity in the UV-irradiated mice fed Diet A were significantly higher than those in mice fed Diet B or Diet C: 1.27, 0.55, and 0.52 nmol/mg protein/hr, respectively. In the SKH-1 mice, ODC activity was increased by the first week of UV treatment, and by three weeks of treatment a dietary effect was observed; ODC activity was significantly higher in mice fed Diet C (0.70 nmol/mg protein/hr) than in mice fed Diet A (0.18 nmol/mg protein/hr). Although there was no significant effect of dietary corn oil/coconut oil on UV-induced tumor incidence, the data indicate that chronically UV-irradiated hairless SKH-1 mice are more susceptible to UV-induced skin carcinogenesis than Sencar mice and that this susceptibility is correlated with increased in ODC activity, a parameter of cell proliferation.
为研究不同水平的玉米油和椰子油对紫外线（UV）诱导的皮肤肿瘤发生及鸟氨酸脱羧酶（ODC）活性的影响，给Sencar小鼠和SKH - 1小鼠喂食三种含15%（重量）脂肪的半纯化日粮之一，日粮中玉米油与椰子油的比例分别为：日粮A为1.0%:14.0%，日粮B为7.9%:7.1%，日粮C为15.0%:0.0%。30只Sencar小鼠和30只SKH - 1小鼠分为一组，在紫外线照射前喂食其中一种日粮三周；然后对两种品系的小鼠进行紫外线照射，初始剂量为90 mJ/cm²。每周照射三次，每次剂量增加25%。对于Sencar小鼠（照射33周，总剂量为48 J/cm²），日粮A、B、C的肿瘤发生率分别最高达到60%、60%和53%，每只荷瘤动物平均有一到两个肿瘤。对于SKH - 1小鼠（照射29周，总剂量为18 J/cm²），到29周时所有日粮组的肿瘤发生率均达到100%，每只荷瘤小鼠约有12个肿瘤。在两种品系中，未发现日粮中玉米油/椰子油比例对肿瘤潜伏期、发生率或产量有显著影响。评估了增加玉米油对长期紫外线照射的Sencar和SKH - 1小鼠表皮ODC活性的影响。从每个品系中选取三组小鼠，喂食其中一种实验日粮并进行六周紫外线照射。Sencar小鼠在治疗六周前ODC活性没有增加，此时喂食日粮A的紫外线照射小鼠的ODC活性显著高于喂食日粮B或C的小鼠，分别为1.27、0.55和0.52 nmol/mg蛋白/小时。在SKH - 1小鼠中，紫外线治疗第一周ODC活性就增加了，到治疗三周时观察到日粮的影响；喂食日粮C的小鼠（0.70 nmol/mg蛋白/小时）的ODC活性显著高于喂食日粮A的小鼠（0.18 nmol/mg蛋白/小时）。尽管日粮中玉米油/椰子油比例对紫外线诱导的肿瘤发生率没有显著影响，但数据表明，长期紫外线照射的无毛SKH - 1小鼠比Sencar小鼠更容易受到紫外线诱导的皮肤致癌作用，并且这种易感性与ODC活性增加相关，ODC活性是细胞增殖的一个参数。
