Breast Cancer Prevention by Dietary Phytochemicals

描述（由申请人提供）：乳腺癌化学预防的新方法是可取的，因为与该疾病相关的许多危险因素不易改变。此外，目前针对乳腺癌的一些化学预防选择是次优的。无需强调，尽管在靶向治疗方面取得了巨大进展，但乳腺癌仍然是全世界妇女癌症相关死亡的主要原因。本研究项目的持续目标是利用十字花科植物成分异硫氰酸苄酯（BITC）开发一种非内分泌的乳腺癌化学预防策略。本次资助的研究目标已基本实现，并发表了著名的论文。例如，我们在转基因小鼠模型（MMTV-neu）中证明，在饮食中给予BITC可以显著保护乳腺癌，而没有任何明显的毒性迹象。我们最近发表的和未发表的观察结果表明，BITC的新作用可能有助于其化学预防作用，包括体外和体内抑制上皮-间充质转化（EMT）（已发表）和体外抑制乳腺癌干细胞（bCSC）的自我更新（未发表的观察结果）。我们还发现，BITC治疗激活了Notch信号，这是EMT和CSC自我更新的积极调节因子。因此，通过实验测试BITC激活Notch是否会对其化学预防反应产生负面影响是合乎逻辑的。同时，尿激酶型纤溶酶原激活物（uPA）及其受体（uPAR）的表达在BITC治疗后显著下调。由于uPAR过表达足以在乳腺癌细胞中驱动EMT和干细胞，因此进一步研究uPA/uPAR在比特币介导的EMT和bCSC自我更新抑制中的作用同样有价值。假设：目前更新应用中的研究设计逻辑上建立在这些令人兴奋和新颖的观察结果之上，以测试一个令人兴奋的假设，即BITC通过抑制uPA/uPAR系统介导乳腺癌化学预防，从而抑制EMT和bCSC的自我更新，这可能可以通过使用a ？分泌酶抑制剂。具体目的：拟研究利用相关的乳腺癌细胞和体内动物模型来确定：(1)BITC激活Notch对其促进乳腺癌化学预防作用的影响；(2) uPA/uPAR抑制在bitc介导的EMT抑制中的作用；(3)获得BITC对bCSC自我更新有效的体内证据，并研究uPA/uPAR系统在这种反应中的作用。建议研究的转化影响：迄今为止进行的研究为BITC对乳腺癌的化学预防效果提供了令人信服的临床前证据，但将这些发现有效地转化为临床环境取决于对BITC驱动其化学预防反应的分子药理学的充分理解。没有充分了解BITC分子药理学的临床试验设计可能是次优的。定义当前应用的创新包括所提出的研究的转化价值以及新的研究方向。例如，Aim 1中提出的研究的内在价值在于潜在的合理设计涉及BITC和a ？-分泌酶抑制剂，以达到更大的化学预防效果。目标2可能确定在未来临床研究中可能有用的BITC反应的生物标志物（例如，uPA和uPAR）。发现可预测BITC反应的生物标志物同样是一个值得称赞的目标，因为对于乳腺癌等具有长潜伏期的恶性肿瘤来说，癌症发病率的终点过于严格。同样，实验验证BITC对bCSC的体内疗效可能（在未来）导致新的基于BITC的乳腺癌临床治疗方案，因为现有的机制模型规定了bCSC不仅在癌症的发生和进展中起关键作用，而且在治疗耐药中也起关键作用。

DESCRIPTION (provided by applicant): Novel approaches for chemoprevention of breast cancer are desirable because many risk factors associated with this disease are not easily modifiable. Moreover, some of the currently available chemopreventive options targeted against breast cancer are sub-optimal. Needless to emphasize that breast cancer continues to be a leading cause of cancer-related death in women worldwide despite tremendous advances towards targeted therapies. Ongoing objective of this research project is to develop a non-endocrine strategy for chemoprevention of breast cancer using cruciferous vegetable constituent Benzyl Isothiocyanate (BITC). Research objectives of the current funded grant were nearly fully achieved with notable publications. For example, we demonstrated that BITC administration in the diet confers significant protection against mammary cancer in a transgenic mouse model (MMTV-neu) without any signs of overt toxicity. We are extremely excited with our more recent published as well as unpublished observations underpinning novel actions of BITC potentially contributing to its chemopreventive effect, including inhibition of epithelial-mesenchymal transition (EMT) in vitro and in vivo (published) and suppression of self-renewal of breast cancer stem cells (bCSC) in vitro (unpublished observations). We also found that BITC treatment activates Notch signaling, which is a positive regulator of EMT as well as CSC self-renewal. Thus it is only logical to experimentally test whether Notch activation by BITC has negative impact on its chemopreventive response. At the same time, expression of urokinase-type plasminogen activator (uPA) and its receptor (uPAR) is significantly downregulated by BITC treatment. Because uPAR overexpression is sufficient to drive both EMT and stemness in breast cancer cells, further investigation of the role of uPA/uPAR in BITC-mediated inhibition of EMT and bCSC self-renewal is equally meritorious. Hypothesis: Research design in the present renewal application logically builds upon these exciting and novel observations to test a stimulating hypothesis that mammary cancer chemoprevention by BITC is mediated by inhibition of the uPA/uPAR system leading to suppression of EMT and self-renewal of bCSC, which may be amenable to augmentation by pharmacological suppression of Notch using a ?-secretase inhibitor. Specific Aims: Proposed research utilizes relevant cellular and in vivo animal models of breast cancer to determine: (1) the impact of Notch activation by BITC on its effects contributing to mammary cancer chemoprevention; (2) the contribution of uPA/uPAR suppression in BITC-mediated inhibition of EMT; and (3) obtain in vivo evidence for efficacy of BITC against bCSC self-renewal and to study the role of uPA/uPAR system in this response. Translational Impact of the Proposed Research: Studies conducted thus far provide compelling preclinical evidence for chemopreventive efficacy of BITC against breast cancer, but efficient translation of these findings into a clinical setting is dependent on a full understanding of the molecular pharmacology of BITC driving its chemopreventive responses. Clinical trial design without a full appreciation of the molecular pharmacology of BITC may be sub-optimal. Defining innovation of the current application includes translational merit of the proposed research as well as novel research directions. For example, intrinsic value of the studies proposed in Aim 1 resides in potential rational design of a combination regimen involving BITC and a ?-secretase inhibitor to achieve even greater chemopreventive efficacy. Aim 2 may identify biomarkers of BITC response (e.g., uPA and uPAR) potentially useful in future clinical investigations. Discovery of biomarker(s) predictive of BITC response is an equally meritorious objective because cancer incidence is too rigorous of an end point for malignancies with long latency such as breast cancer. Likewise, experimental validation of the in vivo efficacy of BITC against bCSC may (in future) lead to novel BITC- based regimens for clinical management of breast cancer because the existing mechanistic model stipulates critical role for bCSC not only in cancer development and progression but also in resistance to therapy.