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

三阴性乳腺癌不表达雌激素受体α(ERα)、孕激素受体(PR)、 或人类表皮生长因子受体2(HER2)，因此，目前使用的靶向药物 对于乳腺癌是有效的。大约60%-80%的TNBCs表达雌激素受体-β (呃β)。然而，ERβ的促肿瘤和抗肿瘤能力仍然存在争议。另一个关键分子 TNBC的特点是P53基因突变频率高(80%)。除了失去肿瘤抑制因子 野生型P53、突变型P53的特性及其显性负调控 也获得致癌功能增益。越来越多的证据表明，并不是所有突变的p53s都起作用 同样的。尽管ER-β和P53已被认为与肿瘤的病理过程有关，但P53是否在肿瘤的发生、发展中起重要作用。 ERβ相对于抗增殖功能的二元性仍然是一个悬而未决的问题。我们的长期目标是理解 并利用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的特定突变如何影响TNBC中ERβ的功能，并预测 这种特定的P53突变将决定其在ERβ突变型P53-p73信号轴中的作用 肿瘤进展和转移的各个方面。假设ERβ结合并抑制WTP53和WTP53 突变型p53对TNBC的进展和治疗反应产生相反的影响 三苯氧胺()。这项拟议研究的基本原理是，理解ERβ如何得出相反的结论 依赖于P53状态的功能对于将TNBC患者分层以改变已建立的用途至关重要 等治疗药物治疗的TNBC患者所占比例较大。具体目标是：(1)确定 不同p53突变体与p73和ERβ在肿瘤细胞中的相互作用；(2)分析不同突变体对p73和ER DNA的影响 P53突变对肿瘤进展、转移和体内治疗反应的影响；以及(3)临床评估 ER-β-P53-p73信号轴的意义在特异靶1中，同基因的TNBC细胞表达不同的 利用CRISPR技术和shRNA介导的ER、β和WT和P53突变体的组合 条件击倒将用于分析相互作用背后的机制及其对 体外细胞功能与体内肿瘤进展。在特定目标2中，不同的P53突变对 肿瘤的生长和转移将在体内进行分析。将对这些研究的临床相关性进行评估。 使用特征明确的患者来源的异种移植物(PDX)；患者肿瘤来源的有机化合物(PDO)；以及患者 与临床数据库相连的肿瘤组织(特定目标3)。这项研究的贡献预计将是 在不同的p53突变背景下更好地理解ERβ-P53-p73轴的机制 影响疾病进展和治疗反应。这项建议具有创新性，因为分析 不同p53突变对整合ERβ突变型p53-p73信号轴的不同影响 与现状背道而驰，并有可能开发针对TNBC的新治疗策略。

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.