Role of necrosis in the evolution of highly metastatic and chemo-resistant breast cancers

高级别、快速生长的乳腺癌通常表现为肿瘤内部坏死，

High-grade, fast-growing breast cancers often display necrosis, usually within the tumor interior, where perfusion, nutrients, and oxygen are limited. Recent studies indicate that necrosis is not just an indicator of aggressive disease, but also a regulator of the aggressive phenotype, by impairing cancer drug delivery, promoting genomic evolution, and instigating metastasis to distant organs. However, we currently lack an understanding of the molecular mechanisms regulating necrosis development and consequently, there are no therapies to prevent the development of necrosis and its downstream effects on tumor aggression. For this application, we have developed animal models that enable the robust dissection of the tumor-host ecosystem in the necrotic interior. Our studies reveal that a secreted protein, angiopoietin-like 7 (Angptl7), is produced by tumor cells adjacent to the necrotic core and is a regulator of tumor core vasculature development. Importantly, when Angptl7 is suppressed genetically, tumor necrosis, tumor growth, and metastatic dissemination are each drastically reduced. Thus, necrosis development is not inevitable but rather is preventable by Angptl7 suppression. In the proposed work, we will combine studies using innovative animal models and breast cancer patient blood and tissue samples to test the hypothesis that the development of necrosis is a driving force for the evolution of highly metastatic and drug-resistant breast tumor cells. In Aim 1, we will use mouse models to test the hypothesis that Angptl7-induced necrosis limits delivery of chemotherapeutics to the tumor core, and that Angptl7 suppression synergizes with neoadjuvant chemotherapeutics to improve drug delivery and improve tumor killing. In Aim 2, we will use tissue from a large population-based cohort of early-stage breast cancer patients to determine how dilated blood vessels, an indicator of Angptl7-induced necrosis, influences risk of local and distant metastatic dissemination to predict benefit from adjuvant therapy. In Aim 3, we will apply genomic sequencing and circulating tumor DNA analysis in an innovative rat model for liquid biopsy studies to define the genomic signatures associated with Angptl7-induced necrosis. We will then determine the prognostic impact of a circulating tumor DNA signature of necrosis in human clinical samples. This work will define necrosis development as an engine for tumor diversification and aggression, and the clinical contexts both in early stage and metastatic settings where necrosis prevention could benetits patients with breast cancer and tumor types.