DIET CANCER AND ONCOGENE EXPRESSION IN INBRED MICE

本研究的目标是：1.确定饮食是否 促脂蛋白(蛋氨酸、胆碱、叶酸和维生素)水平 B12)可以影响肿瘤的发病时间和/或严重程度 近亲繁殖的小鼠具有高自发发病率的品系 白血病或肝癌；2.确定饮食的影响 脂代谢水平对DNA甲基化的影响(总体和 几个特定基因)；以及3.确定 饮食降脂对癌基因表达时间和数量的影响 表情。AKR/J、C3H/HeJ、B6C3F1/J和B6C3F1/J株小鼠 C57BL/6J将喂以半纯饲料， 足够的，或富含亲脂物质的。在收到其中一个 以上列出的饮食时间从一周到三周不等 几个月后，动物将被牺牲，RNA和DNA将被 从他们切除的组织中分离出来。的低甲基化程度 DNA将通过测量DNA接受的能力来进行检测 用同源酶体外测定甲基，通过 5-甲基胞嘧啶与胞嘧啶比值的测定 DNA，并通过测定基因组DNA对 限制性内切酶的切割，其作用对 5-甲基胞嘧啶或胞嘧啶残留物的存在 识别/切割位点。我们会研究这项限制 C-myc、c-Ha-ras、c-ki-ras、c-myc、c-Ha-ras和 其他几个致癌基因。我们将利用DNA：RNA杂交 确定这些癌基因信使核糖核酸水平的技术。 长期饲喂不同脂蛋白含量的日粮将 ，以查看这是否会导致 自发性发病时间或肝脏的数量和严重程度 C3H型和B6C3F1型小鼠的荷瘤时间及荷瘤时间。 方舟小鼠白血病的严重程度。C57BL/6小鼠，它们有 低自发性癌症发病率将作为对照。它是 已知促脂饮食促进化学物质 在啮齿动物中的致癌作用，而饮食中补充 蛋氨酸和胆碱可导致对某些疾病的反应减弱 致癌物质，但目前尚不清楚补充剂是否 蛋氨酸和胆碱能否抑制或是否有促脂作用 缺乏可加速动物癌症的发展 有遗传性高发病率的肿瘤。

The goals of this research are: 1. to determine whether dietary levels of lipotropes (methionine, choline, folic acid, and Vitamin B12) can influence the time of onset and/or severity of tumors in inbred mice of strains that have a high spontaneous incidence of leukemia or hepatomas; 2. to determine what effect the dietary level of lipotropes has on methylation of DNA (overall and of several specific genes); and 3. to determine whether the level of dietary lipotropes affects time and quantity of oncogene expression. Mice of the strains AKR/J, C3H/HeJ, B6C3F1/J and C57BL/6J will be fed semipurified diets that are either deficient, adequate, or enriched with lipotropes. After receiving one of the diets listed above for periods ranging from one week to three months, the animals will be sacrificed and RNA and DNA will be isolated from their excised tissues. Extent of hypomethylation of DNA will be assayed by measuring the ability of DNA to accept methyl groups in vitro in assays with homologous enzymes, by determining the ratio of 5-methylcytosine to cytosine of the DNA, and by determining the susceptibility of genomic DNA to cleavage by restriction endonucleases, whose action is sensitive to the presence of 5-methylcytosine or cytsine residues in their recognition/cleavage sites. We will study the restriction endonuclease digestion patterns of c-myc, c-Ha -ras, c-Ki-ras and several other oncogenes. We will utilize DNA:RNA hybridization techniques to determine the levels of mRNA for these oncogenes. Long term feeding of the diets of differing lipotrope content will be carried out to see whether this results in alterations in the time of spontaneous onset or number and severity of hepatic tumors in C3H and B6C3F1 mice, and the time of on set and severity of leukemia in ARK mice. C57BL/6 mice, which have low spontaneous cancer incidence will be used as controls. It is known that lipotrope-deficient diets promote chemical carcinogenesis in rodents, and that diets supplemented with methionine and choline can cause a decreased response to some carcinogens, but it is not known whether supplements of methionine and choline can suppress or whether lipotrope deficiency can accelerate the development of cancer in animals with an inherited high frequency of neoplasia.