Investigating the role of pericytes as regulators of breast tissue homeostasis and cancer.

项目摘要 尽管在临床治疗和筛查方面取得了进展，但乳腺癌仍然是第二大癌症。 致命的和最常见的女性癌症的原因。BRCA1相关的癌症与 增加癌症发生的风险。大多数BRCA1相关乳腺癌将是“三阴性”，没有靶向 治疗，预后差，总生存率下降。BRCA1突变携带者的癌前病变 上皮细胞以及肿瘤微环境已经得到了很好的研究。然而，BRCA1生殖细胞 突变可能会影响乳房中的所有细胞，而不仅仅是上皮细胞。研究较少，而这一研究的重点是 乳腺微环境的基质细胞中发生的肿瘤前变化，以及它们的 对癌症发生的贡献。这项提议的首要假设是，乳房微环境 被BRCA1突变扭曲并导致癌症发生。 测定乳腺微环境基质的持续挑战是乳腺微环境基质的多样性， 这种组织隔室的异质性。为了克服这一挑战，我们的实验室进行了单细胞RNA 来自一组高危BRCA1突变携带者的81，023个基质和上皮细胞的测序（scRNAseq） 和对照患者手术乳房样品。scRNAseq具有识别细胞中特定细胞群的分辨率， 乳腺微环境以及它们在癌前微环境中的变化。利用这一高度 多维数据，这一建议的目的是1）描述改变旁分泌的相互作用，在前肿瘤 2）确定BRCA1突变携带者乳房中微环境组成如何扭曲。 使用scRNAseq和体外类器官模型，初步工作已经确定了促增殖旁分泌 周细胞与基底上皮的相互作用。此外，这项研究使用scRNAseq数据开发了一种新的 特异性分离周细胞的流式细胞术策略，以证明周细胞具有多能性， 间充质潜能这项研究表明，这些多能周细胞可能作为基质细胞， 间充质干细胞祖细胞为了评估这些相互作用如何促进乳腺癌的发生， 一项研究提出了两种体内人源化小鼠模型，允许致癌患者乳腺上皮生长 具有确定的患者来源的基质群体。如果成功，这项研究将为旁分泌提供新的见解。 以前未定义的相互作用，但可能在乳腺癌的发生中起作用。此外，委员会认为， 基质祖细胞的鉴定可能产生新的生物标志物和高危乳腺癌的靶点。

PROJECT SUMMARY Despite advancements in clinical treatment and screening, breast cancer remains the second most deadly and most frequent cause of cancer in women. BRCA1 related cancer is associated with dramatically increased risk of cancer occurrence. Most BRCA1 related breast cancers will be ‘triple-negative’, with no targeted therapies, poor prognosis, and decreased overall survival. Pre-neoplastic changes in BRCA1 mutation carrier epithelium have been well studied, as well has the tumor microenvironment. However, BRCA1 germline mutations are likely to affect all cells in the breast, not just the epithelium. Less well studied, and the focus of this proposal, are the pre-neoplastic changes that occur in the stromal cells of the breast microenvironment, and their contributions to cancer initiation. The overarching hypothesis of this proposal is that the breast microenvironment is distorted by BRCA1 mutations and contribute to cancer initiation. A persistent challenge in assaying the stroma of the breast microenvironment is the diversity and heterogeneity of this tissue compartment. To overcome this challenge, our lab has performed single cell RNA sequencing (scRNAseq) of 81,023 stromal and epithelial cells from a cohort of high-risk BRCA1 mutation carrier and control patient surgical breast samples. scRNAseq has the resolution to identify specific cell populations in the breast microenvironment and how they change in the preneoplastic microenvironment. Using this highly multidimensional data, this proposal aims to 1) describe altered paracrine interactions in the pre-neoplastic breast and to 2) identify how microenvironment composition may be distorted in BRCA1 mutation carrier breasts. Using scRNAseq and in vitro organoid models, preliminary work has defined a pro-proliferative paracrine interaction of pericytes with basal epithelium. Additionally, this study uses scRNAseq data to develop a novel flow cytometry strategy to specifically isolate pericytes to demonstrate that pericytes have multipotent mesenchymal potential. This study proposes that these multipotent pericytes may serve as the stromal mesenchymal stem cell progenitor. To assess how these interactions contribute to breast cancer initiation, this study proposes two in vivo humanized mouse models that allow growth of oncogenic patient breast epithelium with defined patient-derived stromal populations. If successful, this study will provide insights into paracrine interactions that have been previously undefined but may have roles in breast cancer initiation. Furthermore, identification of a stromal progenitor may yield new biomarkers and targets for high-risk breast cancer.