Roles of NF-kB/Rel in the pathogenesis of breast cancer

描述(申请人提供)：在过去的50年里，乳腺癌的发病率一直在上升，目前已成为美国女性的第二大死因。为了找到原因，正在对环境暴露和饮食因素进行研究。核因子？B家族转录因子在许多疾病中发挥重要作用，包括癌症、心血管疾病、肺部疾病、肥胖和糖尿病。在几乎所有的非B细胞中，核因子？B因子都以不活跃的复合体形式隔离在细胞质中。令人惊讶的是，在典型致癌物7，12-二甲基苯并(A)菲(DMBA)诱发的大鼠乳腺肿瘤和95%以上的原发人类乳腺癌标本中，观察到了核因子-βB的异常激活。抑制核因子？B诱导细胞凋亡或减慢生长，而MMTV-c-Rel转基因小鼠则表明c-Rel在迟发性乳腺肿瘤的发生中起因果作用。重要的是，DMBA可以诱导突变型RAS和HER-2/neu的过表达，从而激活小鼠乳腺肿瘤和c-Rel驱动的乳腺癌细胞株中的多个NF-B复合体。最近，PI的实验室发现了一条新的RelB合成途径，表明RelB促进乳腺癌上皮向间充质转化(EMT)，并证明在人乳腺肿瘤和细胞系中，IKK5/I激酶的诱导在维持核因子-βB的活性和转化中发挥着重要作用，并涉及CK2参与IKK5/I的激活。在这项修订后的应用中，PI建议检验中心假设，即由环境致癌物介导的遗传和表观遗传改变会聚在一起，诱导或增强多个核因子？B复合体的活性，从而促进乳腺癌细胞的更具侵袭性的表型。因此，抑制核因子？B将逆转恶性表型。癌症流行病学研究表明，饮用绿茶与乳腺癌发病率呈负相关。绿茶富含具有抗氧化功能的多酚(GTP)；最丰富的是表没食子儿茶素没食子酸酯(EGCG)。EGCG通过HER-2/neu信号通路抑制核因子？B的活化。最近，绿茶或EGCG被证明可以减少DMBA诱导的大鼠乳腺肿瘤的侵袭表型和Rel驱动的细胞，并减缓对曲妥珠单抗耐药的HER-2/neu乳腺癌细胞的增殖。在这个修订的新的RO1应用中，提出了三个目标：(1)阐明NF-B复合体在促进转化中的作用；(2)阐明IKK5/I在乳腺癌发生中的功能作用和IKK5/I启动子激活的机制；(3)进行临床前动物试验，研究GTP抑制HER-2/neu肿瘤生长的能力，包括对曲妥珠单抗耐药的肿瘤。阳性的发现可以很容易地转化为临床。关于环境致癌物或癌基因异常激活的单个核因子-？B复合体在促进浸润性乳腺癌中的作用的重要信息将会公布；研究结果应适用于涉及核因子-？B的广泛疾病。该应用侧重于环境暴露在美国女性乳腺癌发病率增加中的潜在作用，特别是针对已成为包括癌症在内的广泛疾病的治疗靶点的核因子家族(NF-？B家族)。致癌物通过这一因子家族诱导致癌基因的过度表达或突变，Pi的团队已经确定了导致致癌基因表达的新途径，并表明绿茶成分可以逆转它们的激活，即使在对常用疗法耐药的细胞中也是如此。因此，将对对抗体治疗具有抵抗力的乳腺癌细胞进行绿茶成分的临床前测试，如果成功，这种方法可以很容易地转化为临床。

DESCRIPTION (provided by applicant): Breast cancer incidence has been increasing over the past 50 years, and is now the second leading cause of death among American women. In an attempt to find the reasons, environmental exposure and dietary factors are being studied. The NF-?B family of transcription factors plays critical roles in many diseases, including cancer, cardiovascular, pulmonary disease, obesity and diabetes. NF-?B factors are sequestered in the cytoplasm in an inactive complex in almost all non-B cells. Surprisingly, aberrant activation of NF-?B was observed in rat mammary tumors induced by the prototypic carcinogen 7,12-dimethylbenz(a)anthracene (DMBA) and over 95% of primary human breast cancer specimens. Inhibition of NF-?B induced apoptosis or slowed growth, while an MMTV-c-Rel transgenic mouse showed that c-Rel can play a causal role in late onset mammary tumorigenesis. Importantly, mutant Ras and Her-2/neu overexpression, which can be induced by DMBA exposure, were found to activate NF-?B. DMBA activated multiple NF-?B complexes in mouse mammary tumors and in a c-Rel-driven mammary cancer cell line. More recently, the PI's lab has identified a de novo RelB synthesis pathway, shown that RelB promotes epithelial to mesenchymal transition (EMT) of breast cancer, demonstrated that induction of the IKK5/i kinase in human breast tumors and cell lines plays an important role in maintenance of NF-?B activity and transformation, and implicated CK2 in IKK5/i activation. In this revised application, the PI proposes to test the central hypothesis that genetic and epigenetic alterations mediated by environmental carcinogens converge to induce or enhance the activity of multiple NF-?B complexes, thereby promoting a more invasive phenotype of breast cancer cells. Thus, inhibition of NF-?B will revert the malignant phenotype. Cancer epidemiological studies have shown an inverse association between green tea consumption and breast cancer incidence. Green tea is rich in polyphenols (GTPs) with anti-oxidant properties; the most abundant is epigallocatechin-3 gallate (EGCG). EGCG inhibits activation of NF-?B by Her- 2/neu signaling. Recently, green tea or EGCG was shown to reduce the invasive phenotype of DMBA-induced rat mammary tumors and Rel-driven cells in culture, and to slow proliferation of Her-2/neu breast cancer cell lines resistant to trastuzumab. In this revised new RO1 application, three aims are proposed: to (1) elucidate the roles of NF-?B complexes in promoting transformation; (2) elucidate the functional roles of IKK5/i in mammary carcinogenesis and the mechanism of IKK5/i promoter activation; (3) perform pre-clinical animal testing of the ability of GTPs to inhibit growth of Her-2/neu cancers, including those resistant to trastuzumab. Positive findings can readily be translated to the clinic. Important information on the roles of individual NF-?B complexes that are aberrantly activated by environmental carcinogens or oncogenes in promoting invasive breast cancer will be forthcoming; findings should be applicable to wide-spectrum of diseases involving NF-?B. PUBLIC HEALTH RELEVANCE. This application focuses on the potential role of environmental exposure in the increase in breast cancer incidence in American women, and specifically on a family of nuclear factors (NF-?B family) that have become a target for therapy in a wide spectrum of diseases, including cancer. Carcinogens induce overexpression or mutation in cancer-causing genes that signal via this family of factors, and the PI's group has identified new pathways leading to their expression and shown that green tea components can reverse their activation, even in cells resistant to commonly used therapies. Thus, pre-clinical testing of green tea components on breast cancer cells that are resistant to antibody therapy will be performed, and if successful, this approach can readily be translated to the clinic.