Birt D F, White L T, Choi B, Pelling J C
Eppley Institute for Research in Cancer, University of Nebraska Medical Center, Omaha 68105-1065.
Cancer Res. 1989 Aug 1;49(15):4170-4.
We investigated the influence of dietary corn oil on initiation of skin tumors in SENCAR mice with 7,12-dimethylbenz(a)anthracene (DMBA) (10 nmol at 8 to 9 wk of age) and the promotion of these tumors with 12-O-tetradecanoylphorbol-13-acetate (TPA) (3.2 nmol twice weekly for 20 wk). Diet high in corn oil (24.6%) was fed, in comparison with control diet (5%), to mice during two time schedules: (a) high-fat diet was fed preceding and for 1 wk following DMBA to assess the effects of high corn oil diet on initiation; and (b) high-fat diet was fed starting at the time of the first TPA treatment (1 wk following DMBA initiation) until the end of the experiment to assess effects of high corn oil diet on promotion. Mice were trained to consume equivalent caloric allotments of the low- and high-fat diets to ensure that the observed effects on tumor development were for dietary fat at constant calorie intake. Feeding high corn oil diet during DMBA treatment did not influence the incidence of skin papilloma or carcinoma, but the number of papillomas per effective mouse was reduced in mice fed the high-fat diet during initiation. Consumption of the high corn oil diet during and following TPA treatment resulted in an increase in the incidence of papillomas up until Wk 14 of the experiment, an increase in the number of papillomas per effective mouse throughout the experiment, and an increase in the number of carcinomas per effective mouse during Wk 25 to 34. However, cumulative carcinoma yield (Wk 25-44) did not differ between the diet groups. Dietary treatment did not influence food consumption, body weight, or survival in the mice treated with DMBA and TPA. Northern blot hybridization studies were carried out on RNA purified from tumors of high- and low-fat mice to determine if diet influenced the pattern of Ha-ras oncogene expression. The results of this experiment indicated that elevated levels of Ha-ras-specific RNA, in comparison with normal epidermal RNA, were present in papillomas and carcinomas from DMBA-initiated, TPA-promoted mice irrespective of the diet the mice were fed.
我们研究了膳食玉米油对SENCAR小鼠皮肤肿瘤起始的影响，这些小鼠在8至9周龄时用7,12 - 二甲基苯并(a)蒽（DMBA）（10 nmol）处理，并用12 - O - 十四烷酰佛波醇 - 13 - 乙酸酯（TPA）（3.2 nmol，每周两次，共20周）促进这些肿瘤的生长。将富含玉米油（24.6%）的饮食与对照饮食（5%）相比，在两个时间段喂给小鼠：(a) 在DMBA处理之前及之后1周喂高脂饮食，以评估高玉米油饮食对肿瘤起始的影响；(b) 从第一次TPA处理时（DMBA处理后1周）开始喂高脂饮食直至实验结束，以评估高玉米油饮食对肿瘤促进的影响。训练小鼠消耗等量热量的低脂和高脂饮食，以确保观察到的对肿瘤发展的影响是由于恒定热量摄入下的膳食脂肪所致。在DMBA处理期间喂高玉米油饮食并不影响皮肤乳头瘤或癌的发生率，但在起始阶段喂高脂饮食的小鼠中，每只有效小鼠的乳头瘤数量减少。在TPA处理期间及之后消耗高玉米油饮食导致直至实验第14周乳头瘤发生率增加，在整个实验过程中每只有效小鼠的乳头瘤数量增加，并且在第25至34周期间每只有效小鼠的癌数量增加。然而，饮食组之间累积癌产量（第25 - 44周）没有差异。膳食处理不影响用DMBA和TPA处理的小鼠的食物消耗、体重或存活率。对从高脂和低脂小鼠肿瘤中纯化的RNA进行Northern印迹杂交研究，以确定饮食是否影响Ha - ras癌基因的表达模式。该实验结果表明，与正常表皮RNA相比，无论小鼠喂食何种饮食，在由DMBA起始、TPA促进的小鼠的乳头瘤和癌中都存在Ha - ras特异性RNA水平升高的情况。
