Intersection of autophagy and vesicle trafficking in Her2-positive breast cancer

乳腺癌是美国妇女中最常见的恶性肿瘤， 高发病率和致死率。乳腺癌也是一种异质性 不同亚型的疾病，其中HER 2+亚型约占患者的25%。尽管 近年来取得了显著进展，包括抗HER 2靶向治疗，我们对机制的理解， 乳腺癌的基础，特别是转移仍然非常有限。拟议研究的长期目标是 了解HER 2+转移和耐药的分子和细胞机制， 最终导致患者死亡的其他乳腺癌。在上一个融资期，我们产生了 并分析了HER 2+乳腺癌的小鼠模型，其中缺失了必需的自噬基因FIP 200或 Fip 200 -4A突变特异性地阻断其自噬活性，并发现阻断FIP 200介导的自噬活性， 自噬通过一种新的机制直接调节乳腺癌的发生和转移， HER 2基因驱动基因。我们发现，自噬阻断可以消除乳腺肿瘤的发生， 通过降低小鼠和人肿瘤细胞质膜上的HER 2水平， 异常的HER 2从高尔基体运输到核内体和多囊泡体（MVB），并最终 在小的细胞外囊泡（sEV）中从肿瘤细胞释放。此外，使用单细胞RNA 测序（scRNA-seq）和生物信息学分析，我们开发了一个工作流程，以确定药理学 可以产生与FIP 200消融相似效果的介入治疗。我们还发现FIP 200在K276处乙酰化， CBP监管其稳定性。最后，我们进行了定制设计的CRISPR-Cas9筛选。 使用我们独特的HER 2+乳腺肿瘤细胞构建自噬调控基因文库，并将p47鉴定为 HER 2+乳腺癌转移的假定抑制因子。先前的研究表明，p47在调节 膜融合事件、自噬和NFκB信号传导，提示自噬与细胞凋亡之间可能存在交叉作用。 与乳腺癌转移中的囊泡运输有关。基于这些强有力的初步数据，并利用我们独特的 小鼠和细胞模型，我们建议1）确定自噬调节HER 2运输的机制 在小鼠和人乳腺癌细胞中，2）鉴定可以破坏 FIP 200在小鼠和人乳腺癌细胞以及患者来源的模型中的作用，以及3）探索FIP 200在小鼠和人乳腺癌细胞中的作用， p47调控HER 2+乳腺癌转移的机制。这些研究将提供 对乳腺癌转移的分子和细胞机制的重要见解， 新疗法来治疗这种毁灭性的疾病

Breast cancer is the most common malignancy among US women and remains a major health threat with high incidence and lethality due to therapeutic resistance and metastasis. Breast cancer is also a heterogenous disease with different subtypes, including HER2+ subtype accounting for about 25% of patients. Despite the remarkable progress in recent years including anti-HER2 targeted therapy, our understanding of the mechanistic basis for breast cancer, particularly metastasis is still very limited. The long-term goal of the proposed studies is to understand the molecular and cellular mechanisms of metastasis and therapeutic resistance of HER2+ and other breast cancers that are ultimately responsible for patient lethality. In the prior funding period, we generated and analyzed mouse models for HER2+ breast cancer with deletion of an essential autophagy gene FIP200 or Fip200-4A mutation specifically blocking its autophagy activity and discovered that blocking FIP200-mediated autophagy abolished mammary tumorigenesis and metastasis through a new mechanism directly regulating the oncogenic driver HER2 itself. We showed that autophagy blockade abolishes mammary tumorigenesis and metastasis by decreasing levels of HER2 on the plasma membrane of mouse and human tumor cells due to aberrant HER2 trafficking from the Golgi to endosomes and multiple vesicular bodies (MVBs) and eventually released from tumor cells in small extracellular vesicles (sEVs). Additionally, employing single-cell RNA sequencing (scRNA-seq) and bioinformatics analysis, we developed a workflow to determine pharmacological interventions that would yield similar effects as FIP200 ablation. We also found FIP200 acetylation at K276 by CBP that regulates its stability. Lastly, we performed an in vivo CRISPR-Cas9 screen of a custom designed library of autophagy regulatory genes using our unique HER2+ mammary tumor cells and identified p47 as a putative suppressor for HER2+ breast cancer metastasis. Previous studies showed a role for p47 in regulating membrane fusion events, autophagy, and NFκB signaling, suggesting potential crosstalk between autophagy with vesicle trafficking in breast cancer metastasis. Based on these strong preliminary data and using our unique mouse and cell models, we propose to 1) determine the mechanism of autophagy regulation of HER2 trafficking in mouse and human breast cancer cells, 2) identify pharmacological agents that can disrupt the functions of FIP200 in mouse and human breast cancer cells as well as patient-derived models, and 3) explore the role and mechanisms of regulation of HER2+ breast cancer metastasis by p47. Together, these studies will provide significant insights into the molecular and cellular mechanisms of breast cancer metastasis that may contribute to novel therapies for this devastating disease.