Research Project 3: Role of the NF-kB/Rel in Mammary Carcinogenesis

在过去的50年里，乳腺癌的发病率有所上升，现在它是导致癌症的第二大原因 美国女性的死亡。为了找出发病率增加的原因，遗传， 环境和饮食因素正在研究中。核因子-KB二聚体转录因子家族，它 控制对肿瘤转化、细胞增殖和生存至关重要的基因，由五个成员组成： 3个有反式激活结构域(c-rel、relA、RelB)，2个没有(p50和p52)，它们促进更强 有约束力的。在大多数细胞中，核因子-KB以非活性复合体的形式被隔离在细胞质中。协作性 该计划项目成员的研究表明，c-Rel、RelA或 P50核因子-KB亚基在-90%的人乳腺癌中的表达，以及暴露于多环芳香族化合物 碳氢化合物(PAHs)，如7，12-二甲基苯并(A)菲(DMBA)或苯并(A)芘，上调表达 核因子-kB在乳腺癌中的表达。这将我们引向了最初应用中的中心假设，即致癌物可以 结构性地激活核因子-kB，从而促进转化。在与项目1和项目2的合作中，我们 最近的研究表明，暴露于多环芳烃所诱导的核因子-KB复合体在 通过上皮向间充质转化(EMT)促进乳腺癌的侵袭性表型。(1)多环芳烃 暴露于小鼠激活的多个核因子-KB复合体、IKKE/I激酶和乳腺侵袭性表型 肿瘤；(2)暴露于c-Rel驱动的乳腺癌细胞的PAH进一步激活了NF-KB，这是 侵袭性表型；(3)c-rel亚单位在乳腺肿瘤发生中可能起因果作用并协同作用。 用蛋白激酶CK2诱导AhR和Slug，它是EMT的主要调节因子；(4)一种新的从头RelB 确定了合成途径，通过诱导Bcl-2促进EMT；(5)RelB由 DMBA或c-Rel，在人乳腺癌标本中表达。值得注意的是，绿茶及其多酚 表没食子儿茶素没食子酸酯(EGCG)降低DMBA诱导的乳腺肿瘤的侵袭表型 乳腺癌细胞。EGCG抑制耐药乳腺癌细胞株HER-2/neu的增殖 曲妥珠单抗，建议绿茶多酚的翻译应用。因此，环境 已知致癌物可在乳腺组织中诱发遗传和表观遗传事件。在本修订版中 续订申请，我们建议检验假设，这些扰动诱导或增强 多个核因子-KB复合体的活性，从而促进乳腺癌的更具侵袭性的表型： 抑制这些通路将逆转EMT的过程。提出了三个目标：(1)明确角色定位 (2)确定IKKE/I在肿瘤发生中的作用， 以及IKKS/I启动子激活的机制；(3)进行临床前的活体实验 茶多酚减少HER-2/neu介导的转化。这些研究将提供重要的 环境激活核因子-kB因子异常表达机制的研究进展 致癌物，并描述它们在促进浸润性乳腺癌方面的作用。绿茶多酚是 潜在的乳腺癌抑制剂，可以很容易地转化到临床上进行联合治疗。

The incidence of breast cancer has risen over the past 50 years, and it is now the second leading cause of death among American women. In an attempt to find the reasons for this increase in incidence, genetic, environmental and dietary factors are being studied. The NF-KB family of dimeric transcription factors, which controls genes critical for neoplastic transformation, cell proliferation and survival, consists of five members: 3 with transactivation domains (c-Rel, RelA, RelB), and 2 without (p50 and p52), which promote stronger binding. NF-KB factors are sequestered in the cytoplasm in inactive complexes in most cells. Collaborative studies by members of the Program Project demonstrated constitutive aberrant activation of c-Rel, RelA or p50 NF-KB subunits in -90% of primary human breast cancers, and that exposure to polycyclic aromatic hydrocarbons (PAHs), such as 7,12-dimethylbenz(a)anthracene (DMBA) or benzo(a)pyrene, up-regulated NF-KB in breast cancer. This led us to the central hypothesis in the original application that carcinogens can constitutively activate NF-KB, which will promote transformation. In collaboration with Projects 1 and 2, we have more recently shown that NF-KB complexes, which are induced by PAH exposure, play key roles in promoting an invasive phenotype of breast cancer via epithelial to mesenchymal transition (EMT). (1) PAH exposure of mice activated multiple NF-KB complexes, the IKKe/i kinase and an invasive phenotype of mammary tumors; (2) PAH exposure of c-Rel-driven breast cancer cells further activated NF-KB, which was required for an invasive phenotype; (3) the c-Rel subunit can play a causal role in mammary tumorigenesis and cooperated with protein kinase CK2 to induce the AhR and Slug, a master regulator of EMT; (4) a novel de novo RelB synthesis pathway was identified, which promoted EMT via induction of Bcl-2; (5) RelB was induced by DMBA or c-Rel and expressed in human breast cancer specimens. Of note, green tea and its polyphenol epigallocatechin-3 gallate (EGCG) reduced invasive phenotype of DMBA-induced mammary tumors and breast cancer cells. EGCG slowed proliferation of Her-2/neu breast cancer cell lines resistant to trastuzumab, suggesting translational applications of green tea polyphenols. Thus, environmental carcinogens are known to induce genetic as well as epigenetic events in mammary tissue. In this revised renewal application, we propose to test the hypothesis that these perturbations induce or enhance the activity of multiple NF-KB complexes thereby promoting a more invasive phenotype of breast cancer: thus inhibition of these pathways will revert the process of EMT. Three aims are proposed: (1) elucidate the roles of c-Rel and RelB NF-KB in promoting carcinogenesis; (2) determine the function of IKKe/i in carcinogenesis, and the mechanism of IKKs/i promoter activation; (3) perform pre-clinical in vivo testing of the ability of green tea polyphenols to reduce Her-2/neu-mediated transformation. These studies will provide important information on the mechanisms of activation of aberrant expression of NF-KB factors by environmental carcinogens, and characterize their roles in promoting invasive breast cancer. Green tea polyphenols are potential inhibitors of breast cancer that can readily be translated to the clinic for combinatorial therapies.