新型溴阻燃剂对Igf2/H19甲基化的影响及其在ER阳性乳腺癌中的作用机制研究

乳腺癌已成为女性发病率首位的恶性肿瘤。其发生机制尚不清楚；目前认为可能是遗传和环境的共同作用，如具内分泌干扰和致癌潜力的污染物可通过雌激素受体（ER）促进乳腺上皮细胞恶性转化与侵袭。面向这一科学问题，本项目拟构建H19过表达和敲降的ER阳性人乳腺细胞模型，探索新型溴阻燃剂（NBFRs）-TBB、TBPH暴露后对正常人乳腺上皮细胞恶性转化、乳腺癌细胞侵袭和转移能力的影响；检测AhR-ER受体在Igf2/H19雌激素元件（ERE）的募集作用，及其对Igf2/H19甲基化的改变。在前期人群外暴露研究的基础上，在不同水平区域开展人组织样本验证：开发色谱-质谱联用技术检测血液/癌变/癌旁正常乳腺组织中的NBFRs；比较Igf2/H19表达和甲基化改变。通过探究NBFRs对Igf2/H19 DNA甲基化的改变，及其在ER阳性乳腺癌发生发展过程中的分子机制，为“环境-表观遗传-恶性肿瘤”提供科学线索。

Breast cancer has become the leading type of malignant tumors in women worldwide including China. However, the mechanism is still unclear; genetic and environmental factors might be the two major risk factors of breast cancer. The preliminary studies showed that environmental organic pollutants with endocrine disrupting and carcinogenicity could promote malignant transformation and invasion of mammary epithelial cells in vitro through activating the estrogen receptor (ER). To solve those scientific issue, estrogen receptor (ER) positive breast cells will be transfected with H19 overexpression or siRNA-H19 vector to explore the effects on malignant transformation of normal mammary epithelial cells and invasion/migration of breast cancer cells, after exposure to novel brominated flame retardants (NBFRs)-[2-ethylhexyl-2,3,4,5-tetrabromobenzoate (TBB), bis(2-ethylhexyl) tetrabromophthalate (TBPH)]. The protein interactions of AhR-ER and their combinations on estrogen receptor elements (ERE) of Igf2/H19 will be tested. DNA methylation of target genes will be detected and compared. Our previous study has measured the atmospheric exposure levels of NBFRs of population in Tianjin. Based on those results, this study will choose ER-positive breast cancer female patients from high and low environmental NBFRs levels regions, respectively. A high-throughput method based on chromatography-mass spectrometry will be established to explore NBFRs in blood, cancerous and pericarcinoma normal breast adipose tissues. DNA methylation and expression of Igf2/H19 will be conducted to verify epigenetic mechanisms mediated by BFRs-AhR/ER-Igf2/H19. This study can promote the understanding of effects of NBFRs on Igf2/H19 epigenetic changes and its association with breast cancer. This study will provide the scientific evidence for environment-epigenetic mechanisms-cancer interactions from population study view.