Abstract 50: Tumorigenic properties of uveal melanoma cancer cells cultured in 3D or on a reconstructed extracellular matrix
Authors: Chancy Olivier , Piquet Léo , Coutant Kelly , Mitchell Andrew , Landreville Solange 
Published: April 2023

Abstract
Background: Uveal melanoma (UM) is the most common intraocular tumor in adults. It arises from the transformation of melanocytes, and despite the effective treatment of the ocular tumor, hepatic metastases lead to a poor prognosis. Our hypothesis is that the invasive potential and therapeutic resistance of UM cells (UMCs) depend on interactions with stromal cells and properties of the extracellular matrix (ECM). Our study aims to determine the impact of UMCs in stromal cell activation, and to define the role of the ECM produced by choroidal fibroblasts or hepatic stellate cells (HSteCs) on UM cell proliferation and invasion.
Methods: Two types of tumor spheroids were generated i) one corresponding to primary melanoma (UMCs from eye tumor + choroidal fibroblasts and endothelial cells) and ii) the other to liver metastasis (UMCs from liver metastasis + HSteCs and sinusoidal endothelial cells). The organization of these mixed spheroids were studied by confocal microscopy using the following markers: Melan-A (UM cells), alpha-smooth muscle actin (aSMA; activated fibroblasts and stellate cells), CD31 (endothelial cells) and Ki67 (proliferation). The viability and invasion capacity of the mixed spheroids were analyzed using an ATP consumption assay, and the measurement of the invasion area in Matrigel. Next, two types of matrices were produced by tissue engineering using the self-assembly approach with choroidal fibroblasts or HSteCs. These matrices were devitalized and characterized by confocal microscopy (collagens, fibronectin), before seeding UMCs to study their morphology, proliferation and ECM remodeling.
Results: A higher concentration of alpha-SMA and proliferative cells were observed in the outer layers of the spheroids by immunofluorescence analyses. Choroidal and hepatic matrices were produced in 21 days. These tissue-engineered matrices contained fibronectin and collagen I. These devitalized matrices were seeded with UMCs in monolayer to study their change of morphology, proliferative state and ECM remodeling.
Conclusions: We characterized the viability and cellular organization in both choroidal and hepatic spheroid models, and successfully generated tissue-engineered choroidal and hepatic matrices. With the optimization of these 3D
models, we will better understand the steps involved in the progression of ocular melanoma to a metastatic stage. These complex models may replace the 2D model using tumor cells in monolayer for future drug screening, which will consider the impact of the microenvironment on UM therapeutic resistance.
Citation Format: Olivier Chancy, Léo Piquet, Kelly Coutant, Andrew Mitchell, Solange Landreville. Tumorigenic properties of uveal melanoma cancer cells cultured in 3D or on a reconstructed extracellular matrix [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 50.