Abstract 172: The impact of extracellular matrix modulation and cancer-associated fibroblast presence on patient-derived tumor organoid growth rate, morphology, and chemoresistance
Authors: Valena Scott , Kshetri Pratiksha , Zhao Yuyuan , Elton Elizabeth , Imamura Shohei , Ung Nolan , Kim Seungil , Doche Michael E. , Mumenthaler Shannon M. 
Published: June 2023

Abstract
The tumor microenvironment (TME) of colorectal cancer (CRC) plays an important role in tumor progression and chemoresistance. Therefore, it is important to incorporate elements of the TME, such as extracellular matrix (ECM) composition and stromal cells, into preclinical models to better recapitulate tumor dynamics in vivo. Particularly, cancer-associated fibroblasts (CAFs) are a dominant stromal cell type within the TME that secrete and remodel the ECM and whose abundance can correlate with poor overall survival. Patient-derived tumor organoids (PDTOs) are an innovative preclinical model that has recently emerged as a biomarker for predicting patient-specific drug responses in CRC. However, traditional PDTO cultures fail to account for the aforementioned elements of the TME. Here, we present a basement membrane extract (BME) and collagen type I-based co-culture system utilizing patient-matched CRC PDTOs and CAFs to investigate the effects of the TME on PDTO growth rate, morphology, and drug response.First, we compared the growth rate, morphology, and drug response of PDTO-only cultures in 2 ECMs: 100% BME and 90% BME + 10% collagen type I. PDTOs were seeded 4 days prior to treatment with clinically relevant therapeutics 5-Fluorouracil (5-FU) and SN-38 (active metabolite of irinotecan). Cell viability was assessed 5 days after treatment using the CellTiter-Glo 3D assay. In addition, brightfield and fluorescent images of the PDTOs were taken on days -1, 0, 3, and 5 of the drug treatment. GFP-labeled PDTOs were utilized for the image-based analysis to improve segmentation and quantification of PDTO growth rate and morphology as well as to help distinguish between PDTOs and CAFs in the co-culture experiments. The co-culture experiments of PDTOs and CAFs in 90% BME + 10% collagen type I were performed and analyzed using the same assays. To enhance tumor-stromal interactions, the PDTOs and CAFs were suspended together in the ECM. By culturing CRC PDTOs in the BME + collagen I matrix, as well as co-culturing with patient-matched CAFs, we observed differential responses in PDTO growth rate, morphology, and drug response compared to the 100% BME, PDTO-only condition. In conclusion, our initial findings warrant further investigation into the importance of incorporating elements of the TME into PDTO models for drug discovery applications to more closely mimic in vivo tumor conditions.
Citation Format: Scott Valena, Pratiksha Kshetri, Yuyuan Zhao, Elizabeth Elton, Shohei Imamura, Nolan Ung, Seungil Kim, Michael E. Doche, Shannon M. Mumenthaler. The impact of extracellular matrix modulation and cancer-associated fibroblast presence on patient-derived tumor organoid growth rate, morphology, and chemoresistance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 172.