Annals of Nutrition & Metabolism, 2010, 57(3-4):183-189.

Epigenetic Control of Estrogen Receptor Expression and Tumor Suppressor Genes Is Modulated by Bioactive Food Compounds

Carolin Berner, Eva Aumüller, Anne Gnauck, Manuela Nestelberger, A. Just, Alexander G. Haslberger

Department of Nutritional Sciences, University of Vienna, and Department of Obstetrics and Gynecology, Medical University of Vienna, Vienna , Austria

BACKGROUND: The tumor suppressor genes p15^INK4b and p16^INK4a as well as the estrogen receptor-α (ESR1) gene are abnormally methylated and expressed in colon cancer. The cancer-preventative abilities of several bioactive food components have been linked to their estrogenic and epigenetic activities.

METHODS: The effect of folic acid, zebularine, resveratrol, genistein and epigallocatechin-3-gallate (EGCG) on tumor cell growth, promoter methylation of ESR1, p15^INK4b and p16^INKa and gene expression of ESR1 and ESR2 was analyzed in Caco-2 cells. Gene expression was measured using real-time PCR, and promoter CpG methylation was assessed using bisulfite conversion and methylation-specific PCR.

RESULTS: After exposure to a high concentration of folic acid (20 μmol/l), enhanced cancer cell growth and concomitant increased methylation of the ESR1 (3.6-fold), p16^INK4a and p15^INK4b promoters was observed. A lower concentration of folic acid (2 μmol/l) decreased cell growth. The phytoestrogens genistein and resveratrol enhanced expression of ESR1 (genistein 200 μmol/l: 2.1-fold; resveratrol 50 μmol/l: 6.3-fold) and ESR2 (2.6- and 3.6-fold, respectively). Genistein and resveratrol treatment increased promoter methylation of ESR1 (genistein 200 μmol/l: 2.9-fold; resveratrol 50 μmol/l: 1.4-fold). For p16^INK4a, increased methylation was found after exposure to 10 μmol/l resveratrol, but for p15^INK4b, decreased methylation was found. Both components showed growth-inhibitory activities. For EGCG, growth inhibition at 100 μmol/l and suppressed promoter methylation of tumor suppressor genes (p16^INK4a: 0.9-fold; p15^INK4b: 0.6-fold) was seen.

CONCLUSIONS: Our results show that these food compounds regulate ESR and tumor suppressor gene expression by multiple mechanisms including epigenetic processes. An improved understanding of these epigenetic effects could therefore support specific dietary concepts of epigenetic cancer prevention and intervention.

瑞士《营养与代谢年鉴》2010年11月

具有生物活性的食品化合物可以调节雌激素受体表达和肿瘤抑癌基因的表观遗传控制

卡罗琳 伯纳，伊娃 奥姆勒，安妮 格瑙克，玛努薇拉 内斯特尔贝格尔，A.扎斯特，亚历山大 G 豪斯欧伯格

维也纳大学营养科学学院和奥地利维也纳医科大学产科与妇科学院

背景︰ 肿瘤抑癌基因 p15^INK4b 和 p16^INK4a 以及雌激素受体 α (ESR1) 基因在结肠癌中的甲基化和表达都不正常。几种具有生物活性的食品成分的癌症预防能力与其雌激素和表观遗传的活动有关。

方法︰ 叶酸、嘧啶酮-B-核甙、 白藜芦醇、 金雀异黄素和儿茶素-3-没食子酸酯 (EGCG) 对肿瘤细胞生长的影响，ESR1的启动子甲基化， p15^INK4b 和 p16^INKa 以及 ESR1和 ESR2的基因表达等均在 Caco-2 细胞中进行分析。使用实时 PCR测试基因表达，使用亚硫酸氢盐转换和甲基化特异性PCR评估启动子 CpG 甲基化。

结果︰ 在暴露于高浓度叶酸 （20 μmol/l）以后，观察到肿瘤细胞生长的加快，伴随着ESR1 (3.6倍)以及 p16^INK4a 和 p15^INK4b 启动子甲基化的提高。低浓度的叶酸 （2 μmol/l）降低细胞的生长。植物雌激素金雀异黄素和白藜芦醇增强了ESR1 (金雀异黄素 200 μmol/l: 2.1倍; 白藜芦醇 50 μmol/l: 6.3倍) 和 ESR2的表达(2.6和 3.6倍，分别)。金雀异黄素和白藜芦醇的治疗促进了ESR1的启动子甲基化(金雀异黄素 200 μmol/l: 2.9 倍; 白藜芦醇 50μmol/l: 1.4倍)。对于P16^ink4a，甲基化的促进在暴露于10 μmol/l的白藜芦醇之后被发现，但是 p15^INK4b被发现甲基化降低。这两种成分均显示出生长抑制活性。对于 EGCG，在100 μmol/l浓度下，肿瘤抑癌基因的生长抑制和启动子甲基化抑制(p16^INK4a: 0.9倍; p15^INK4b: 0.6倍) 被发现。

结论︰ 我们的研究结果表明这些食物化合物通过表观遗传过程等多种机制可以调控ESR和肿瘤抑制基因的表达。因此，对这些表观遗传效应更好的理解支持预防和干预癌症的特定饮食概念。