Abstract 3831: Utilizing decellularized triple-negative breast cancer patient-derived tumor models as drug testing platforms
Authors: Wright Maryl , Nguyen Khoa , Martin Elizabeth , Bratton Melyssa , Collins-Burow Bridgette , Burow Matthew 
Published: June 2022

Abstract
Triple-negative breast cancer (TNBC) is an aggressive, heterogenous disease that lacks approved targeted therapeutics. Due to the complexity of tumor microenvironment (TME) interactions in TNBC, it is crucial to identify therapeutic targets that regulate the extracellular matrix (ECM). Traditional 2D TNBC models do not accurately mimic the cell-matrix interactions and structural matrix proteins that are key in maintaining the unique TME in individual patient tumors. Here, we introduce our decellularized TNBC patient-derived xenograft (PDX) models to address this gap in knowledge. Utilizing our decellularized models, we can investigate the unique ECM composition and cell-matrix interactions in PDX models from understudied patients with diverse clinical presentations. We can also use our decellularized tumor scaffolds as drug testing models. We utilize our tissue decellularization method on PDX tumor scaffolds derived from two of our established TNBC PDX models (TU-BcX-56S and TU-BcX-4QX). Decellularization of tumor scaffolds was confirmed by DNA quantification and histological analysis (H&E, Masson’s Trichrome, and Movat’s staining). MDA-MB-231 cells expressing GFP and luciferase were seeded onto scaffolds and treated with 100nM of Paclitaxel, a microtubule-stabilizing cytotoxic chemotherapeutic, or DMSO for 48 hours. Concordantly, cells in 2D culture were treated with 100nM of Paclitaxel or DMSO for 48 hours. Using the IVIS imaging system, we measured the bioluminescence of cells on our seeded scaffolds before treatment and at 24 and 48 hours after treatment. Cells in 2D culture showed a significant decrease in bioluminescent signal (p-value &lt; 0.05) in the Paclitaxel group compared to the DMSO group at 48 hours. Cells seeded on TU-BcX-56S scaffold also showed a significant decrease in bioluminescent signal (p-value &lt; 0.05) in the Paclitaxel group compared to the DMSO group at 48 hours. Interestingly, cells seeded on TU-BcX-4QX scaffold showed a decrease in bioluminescence in both the treatment and control groups at 24 and 48 hours, albeit there was no significant difference. Using qPCR, we investigated scaffold regulation of ECM gene composition in our treatment and control groups. These results demonstrate that the unique ECM composition and architecture of these scaffolds are important drivers of cell behavior. Here, we demonstrate that our decellularized PDX tumor scaffold models can be used as drug testing platforms. Furthermore, our models recapitulate key structural matrix proteins in the TNBC TME, can be used to investigate ECM onco-architecture and composition, and can be used in therapeutic discovery research.
Citation Format: Maryl Wright, Khoa Nguyen, Elizabeth Martin, Melyssa Bratton, Bridgette Collins-Burow, Matthew Burow. Utilizing decellularized triple-negative breast cancer patient-derived tumor models as drug testing platforms [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 3831.