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，因为与这种疾病相关的许多危险因素不容易改变。此外，目前针对乳腺癌的一些可用的化学预防方案是次优的。不用说，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。这项研究项目的持续目标是开发一种使用十字花科植物成分异硫氰酸苄酯(BITC)化学预防乳腺癌的非内分泌策略。通过著名的出版物，目前资助的赠款的研究目标几乎完全实现。例如，我们在转基因小鼠模型(MMTV-neu)中证明了在饮食中给予BITC对乳腺癌具有显著的保护作用，而没有任何明显的毒性迹象。我们非常兴奋的是，我们最近发表的和未发表的观察结果支持了BITC可能有助于其化学预防作用的新作用，包括在体外和体内抑制上皮-间充质转化(EMT)(已发表)和在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处理激活了Notch信号，而Notch信号是EMT和CSC自我更新的正向调节因子。因此，只有在实验上测试BITC激活Notch是否对其化学预防反应有负面影响才是合乎逻辑的。同时，BITC可显著下调尿激酶型纤溶酶原激活物(UPA)及其受体(UPAR)的表达。由于uPAR的过表达足以驱动乳腺癌细胞的EMT和干细胞分化，进一步研究uPA/uPAR在BITC介导的抑制EMT和BCSC自我更新中的作用同样是有价值的。假设：目前更新应用中的研究设计在逻辑上建立在这些令人兴奋和新颖的观察结果的基础上，以测试一个刺激性的假设，即BITC的乳腺癌化学预防是通过抑制uPA/uPAR系统介导的，导致抑制EMT和BCSC的自我更新，这可能是通过使用分泌酶抑制剂从药物上抑制Notch来增强的。具体目的：拟议的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对其有助于乳腺癌化学预防的影响；(2)uPA/uPAR抑制在BITC介导的EMT抑制中的作用；(3)获得BITC抑制BCSC自我更新的体内证据，并研究uPA/uPAR系统在这一反应中的作用。拟议研究的翻译影响：到目前为止进行的研究为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了解。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提出的研究的翻译价值以及新的研究方向。例如，目标1中提出的研究的内在价值在于可能合理地设计一种包括BITC和β-分泌酶抑制剂的联合方案，以实现更好的化学预防效果。目的2可能识别BITC反应的生物标志物(例如，uPA和uPAR)，在未来的临床研究中可能有用。发现生物标记物(S)预测BITC反应是一个同样有价值的目标，因为癌症发病率对于乳腺癌等潜伏期较长的恶性肿瘤来说过于严格。同样，BITC对BCSC体内疗效的实验验证可能(在未来)导致基于BITC的乳腺癌临床治疗的新方案，因为现有的机制模型规定BCSC不仅在癌症的发生发展中起关键作用，而且在治疗耐药中也发挥关键作用。

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 We are extremely excited with our more recent published as well as unpublished observations underpinning novel actions of BITC potentially contributing to its chemopreventive effect, including inhibition of epithelial-mesenchymal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.