Endothelin-1 receptor blockade impairs invasion patterns in engineered 3D high-grade serous ovarian cancer tumouroids.

High-grade serous ovarian cancer (HG-SOC), accounting for 70-80% of ovarian cancer deaths, is characterized by a widespread and rapid metastatic nature, influenced by diverse cell types, cell-cell interactions, and acellular components of the tumour microenvironment (TME). Within this tumour type, autocrine and paracrine activation of the endothelin-1 receptors (ET-1R), expressed in tumour cells and stromal elements, drives metastatic progression. The lack of three-dimensional models that faithfully recapitulate the unique HG-SOC TME has been the bottleneck in performing drug screening for personalized medicine. Herein, we developed HG-SOC tumouroids by engineering a dense central artificial cancer mass (ACM) containing HG-SOC cells, nested within a compressed hydrogel recapitulating the stromal compartment comprising type I collagen, laminin, fibronectin, and stromal cells (fibroblasts and endothelial cells). ET-1-stimulated HG-SOC cells in the tumouroids showed an altered migration pattern and formed cellular aggregates, mimicking micrometastases that invaded the stroma. Compared with control cells, ET-1-stimulated tumouroids showed a higher number of invasive bodies, which were reduced by treatment with the dual ET-1 receptor (ET-1R) antagonist macitentan. In addition, ET-1 increased the size of the invading aggregates compared with control cells. This study establishes an experimental 3D multicellular model eligible for mechanical research, investigating the impact of matrix stiffness and TME interactions, which will aid drug screening to guide therapeutic decisions in HG-SOC patients.