Rodríguez-Miguel Cristina, Moral Raquel, Escrich Raquel, Vela Elena, Solanas Montserrat, Escrich Eduard
Grup Multidisciplinari per a l'Estudi del Càncer de Mama, Physiology Unit, Department of Cell Biology, Physiology and Immunology, Faculty of Medicine, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain.
PLoS One. 2015 Sep 24;10(9):e0138980. doi: 10.1371/journal.pone.0138980. eCollection 2015.
Disruption of epigenetic patterns is a major change occurring in all types of cancers. Such alterations are characterized by global DNA hypomethylation, gene-promoter hypermethylation and aberrant histone modifications, and may be modified by environment. Nutritional factors, and especially dietary lipids, have a role in the etiology of breast cancer. Thus, we aimed to analyze the influence of different high fat diets on DNA methylation and histone modifications in the rat dimethylbenz(a)anthracene (DMBA)-induced breast cancer model. Female Sprague-Dawley rats were fed a low-fat, a high corn-oil or a high extra-virgin olive oil (EVOO) diet from weaning or from induction with DMBA. In mammary glands and tumors we analyzed global and gene specific (RASSF1A, TIMP3) DNA methylation by LUMA and bisulfite pyrosequencing assays, respectively. We also determined gene expression and enzymatic activity of DNA methyltransferases (DNMT1, DNMT3a and DNMT3b) and evaluated changes in histone modifications (H3K4me2, H3K27me3, H4K20me3 and H4K16ac) by western-blot. Our results showed variations along time in the global DNA methylation of the mammary gland displaying decreases at puberty and with aging. The olive oil-enriched diet, on the one hand, increased the levels of global DNA methylation in mammary gland and tumor, and on the other, changed histone modifications patterns. The corn oil-enriched diet increased DNA methyltransferase activity in both tissues, resulting in an increase in the promoter methylation of the tumor suppressor genes RASSF1A and TIMP3. These results suggest a differential effect of the high fat diets on epigenetic patterns with a relevant role in the neoplastic transformation, which could be one of the mechanisms of their differential promoter effect, clearly stimulating for the high corn-oil diet and with a weaker influence for the high EVOO diet, on breast cancer progression.
表观遗传模式的破坏是各类癌症中发生的主要变化。此类改变的特征为全基因组DNA低甲基化、基因启动子高甲基化及异常的组蛋白修饰，且可能受环境影响。营养因素，尤其是膳食脂质，在乳腺癌的病因学中发挥作用。因此，我们旨在分析不同高脂饮食对大鼠二甲基苯并(a)蒽（DMBA）诱导的乳腺癌模型中DNA甲基化和组蛋白修饰的影响。从断奶时或用DMBA诱导后开始，给雌性斯普拉格-道利大鼠喂食低脂、高玉米油或高特级初榨橄榄油（EVOO）饮食。在乳腺和肿瘤中，我们分别通过LUMA和亚硫酸氢盐焦磷酸测序法分析全基因组和基因特异性（RASSF1A、TIMP3）DNA甲基化。我们还测定了DNA甲基转移酶（DNMT1、DNMT3a和DNMT3b）的基因表达和酶活性，并通过蛋白质免疫印迹法评估组蛋白修饰（H3K4me2、H3K27me3、H4K20me3和H4K16ac）的变化。我们的结果显示，乳腺全基因组DNA甲基化随时间变化，在青春期和衰老时降低。一方面，富含橄榄油的饮食增加了乳腺和肿瘤中的全基因组DNA甲基化水平，另一方面，改变了组蛋白修饰模式。富含玉米油的饮食增加了两个组织中的DNA甲基转移酶活性，导致肿瘤抑制基因RASSF1A和TIMP3的启动子甲基化增加。这些结果表明，高脂饮食对表观遗传模式有不同影响，在肿瘤转化中起相关作用，这可能是它们不同启动子效应的机制之一，高玉米油饮食对乳腺癌进展有明显促进作用，而高EVOO饮食的影响较弱。
