Abstract 6324: Development and characterization of Ewing Sarcoma lung metastasis model

Abstract

Abstract Introduction: Ewing Sarcoma (EwS) is the second most common bone tumor in children. At diagnosis, approximately 20-25% of patients with EwS have metastatic disease. While systemic chemotherapy, along with surgery and/or radiotherapy, has significantly increased the survival rate of patients with localized disease, metastatic Ewing sarcoma (EwS) has an extremely poor overall survival with a 5-year survival rate of approximately 20-30%. This prognosis has not changed in the last several decades. Thus, there is an imperative need to focus particularly on mechanisms of metastatic growth and progression and to identify and target the underlying intrinsic and extrinsic molecular features. Unfortunately, presently there is no reliable engineered mouse model to functionally study EwS development and metastasis. Using two independent EwS cell lines, we have developed highly aggressive, lung-specific metastatic models that show mechanistic overlap with human patient tumor data and are valuable resources to further study and target metastatic EwS. Approach: Using a serial transplantation approach, we generated lung specific metastatic lines by repeated intra-tibial injection of two commonly used EwS cell lines (A673 and TC71), allowing metastatic foci to form, followed by dissociation and subsequent re-injection into the tibia. We repeated this 5 times to generate highly aggressive lung-specific metastatic cell lines. As a proof of principle, when equal numbers of GFP+ parental cells and mCherry+ lung metastatic cells are injected into the tibia in NSG mice they form primary tumors with red and green cells, while the metastatic lesions in lungs are almost exclusively mCherry+. A multi-omics approach including glycoproteomics, secretome, and transcriptomic analysis were then used to characterize these cells and compare them with patient tumor samples. Results: Integration of focused proteomics and glycoproteomics data revealed upregulation in AXL, MEK6, STAT1, and STAT3 proteins and phosphoproteins in metastatic lesions. Focused RNA profiling with Nanostring technologies using formalin-fixed paraffin-embedded (FFPE) slides of patient tumor samples revealed increased expression of several other upstream genes that signal through STAT1, including IL-6, IKK-β, TRAF-6, and Myd88. In addition, upregulation in factors involved in tumor invasive front such as Furin, TIMP-2, MMP-2, and MMP-14 were also noted. We are currently in the process of further validating some of the key regulators using larger set of patient derived tumors and by targeting them in orthotopic mouse models. Citation Format: Atreyi Dasgupta, Lyazat Kurenbekova, Tajhal Patel, Jason T. Yustein. Development and characterization of Ewing Sarcoma lung metastasis model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6324.