Functional Significance of individual p53 mutations in determining the role of estrogen receptor beta in triple negative breast cancer

三阴性乳腺癌（TNBC）不表达雌激素受体-α（ERα）、孕激素受体（PR）， 或人表皮生长因子受体2（HER 2），因此，目前使用的靶向药物 对乳腺癌有效。大约60-80%的TNBC表达雌激素受体-β (ERβ）。然而，ERβ的促肿瘤发生能力与抗肿瘤发生能力仍然存在争议。另一个关键分子 TNBC的特征是高频率（80%）的p53突变。除了失去肿瘤抑制因子 性质和发挥显性负调控超过任何剩余的野生型p53（WTP 53），突变型p53 也获得致癌性功能获得。越来越多的证据表明，并非所有突变型p53都起作用。 同样的。尽管ERβ和p53与TNBC病理学有关，但p53是否在促TNBC发生中起作用， 与ERβ的抗增殖功能二元性相比，ERβ的抗增殖功能二元性仍然是一个悬而未决的问题。长期目标是了解 并探讨ERβ-p53串扰在乳腺癌中的作用，以开发更好的治疗策略。 目的是研究p53中的特定突变如何影响TNBC中的ERβ功能，预测 特异性p53突变将决定其在ERβ-突变型p53-p73信号传导轴中的作用， 肿瘤进展和转移方面。假设ERβ结合并抑制WTp 53和WTp 54， 突变型p53，导致对TNBC的进展和对药剂的治疗反应的相反作用， 他莫昔芬（Tam）。这项研究的基本原理是，了解ERβ是如何发挥相反作用的， 以p53状态依赖性方式的功能对于将TNBC患者分层以重新建立目的至关重要。 治疗剂如Tam用于治疗大百分比的TNBC患者。具体目标是：（1）确定 不同p53突变体与p73和ERβ在TNBC细胞中的相互作用;（2）分析不同p53突变体对TNBC细胞中p73和ERβ的差异作用。 p53突变体在体内对肿瘤进展、转移和治疗反应的影响;以及（3）评估p53突变体的临床应用。 ERβ-p53-p73信号轴的意义。在具体的目的1中，表达不同的同源TNBC细胞。 使用CRISPR技术产生的ERβ和WT以及p53突变体的组合和shRNA介导的 条件性敲低将用于分析相互作用的机制及其对 体外细胞功能和体内肿瘤进展。在具体的目标2中，不同的p53突变对 将在体内分析肿瘤生长和转移。将评价这些研究的临床相关性 使用充分表征的患者来源的异种移植物（PDX）;患者肿瘤来源的类器官（PDO）;和患者肿瘤来源的类器官（PDX）。 与临床数据库相关联的肿瘤组织（具体目标3）。这项研究的贡献预计将是 更好地理解不同p53突变背景下ERβ-p53-p73轴的机制 影响疾病进展和治疗反应。该建议是创新的，因为分析 不同p53突变作为整合的ERβ-突变型p53-p73信号传导轴的一部分的差异效应是一个重要的研究领域。 这是一种从现状出发的新方法，并且具有开发针对TNBC的新治疗策略的潜力。

Triple negative breast cancers (TNBCs) do not express estrogen receptor-α (ERα), progesterone receptor (PR), or human epidermal growth factor receptor 2 (HER2), and therefore, none of the targeted drugs currently in use for breast cancer are effective against them. Approximately 60-80% of TNBCs express estrogen receptor-β (ERβ). However, pro- versus anti-tumorigenic capabilities of ERβ remains controversial. Another key molecular characteristic of TNBC is the high frequency (80%) of p53 mutation. In addition to losing tumor suppressor properties and exerting dominant-negative regulation over any remaining wild type p53 (WTp53), mutant p53 also acquires oncogenic gain-of-function. Increasing evidence suggests that not all mutant p53s function similarly. Although ERβ and p53 have been implicated in TNBC pathology, whether p53 has a role in the pro- versus anti-proliferative functional duality of ERβ remains an open question. The long-term goal is to understand and exploit the role of ERβ-p53 crosstalk in breast cancer for the development of better therapeutic strategies. The objective is to study how specific mutations in p53 impinges upon ERβ function in TNBC, with the prediction that specific p53 mutation will determine its role in the ERβ-mutant p53-p73 signaling axis impacting multiple aspects of tumor progression and metastasis. The hypothesis is that ERβ binds to and inhibits both WTp53 and mutant p53, leading to opposite effects on progression and therapeutic response of TNBC to agents such as Tamoxifen (Tam). The rationale for the proposed research is that understanding how ERβ elicits opposite functions in a p53 status-dependent manner will be critical to stratify TNBC patients to repurpose established therapeutic agents such as Tam to treat large percentage of TNBC patients. The specific aims are: (1 Determine the interaction of different p53 mutants with p73 and ERβ in TNBC cells; (2) Analyze the differential effects of p53 mutants on tumor progression, metastasis and therapeutic response in vivo; and (3) Evaluate the clinical significance of the ERβ-p53-p73 signaling axis. In specific aim 1, Isogenic TNBC cells expressing different combinations of ERβ and WT and p53 mutants generated using CRISPR technology and shRNA-mediated conditional knockdown will be used for analyzing the mechanisms underlying the interaction and its impact on cellular functions in vitro and tumor progression in vivo. In specific aim 2, the effect of different p53 mutations on tumor growth and metastasis will be analyzed in vivo. The clinical relevance of these studies will be evaluated using well-characterized patient derived xenografts (PDXs); patient tumor-derived organoids (PDOs); and patient tumor tissues with linked clinical database (specific aim 3). The contribution of this research is expected to be better understanding of the mechanisms by which ERβ-p53-p73 axis in the context of different p53 mutations affects the disease progression and therapeutic response. The proposal is innovative because analyzing the differential effects of different p53 mutations as part of an integrated ERβ-mutant p53-p73 signaling axis is a departure from the status quo and has the potential of developing novel therapeutic strategies against TNBC.