The endothelin-1-driven tumor-stroma feed-forward loops in high-grade serous ovarian cancer

The high-grade serous ovarian cancer (HG-SOC) tumor microenvironment (TME) is constellated by cellular elements and a network of soluble constituents that contribute to tumor progression. In the multitude of the secreted molecules, the endothelin-1 (ET-1) has emerged to be implicated in the tumor/TME interplay, however the molecular mechanisms induced by the ET-1-driven feed-forward loops (FFL) and associated with the HG-SOC metastatic potential need to be further investigated. The tracking of the patient-derived (PD) HG-SOC cell transcriptome by RNA-seq identified the vascular endothelial growth factor (VEGF) gene and its associated signature among those mostly upregulated by ET-1 and down-modulated by the dual ET-1R antagonist macitentan. Within the ligand-receptor pairs concurrently expressed in PD-HG-SOC cells, endothelial cells and activated fibroblasts, we discovered two intertwined FFL, the ET-1/ET-1R and VEGF/VEGF receptors, concurrently activated by ET-1 and shutting-down by macitentan, or by the anti-VEGF antibody bevacizumab. In parallel, we observed that ET-1 fine-tuned the tumoral and stromal secretome towards a pro-invasive pattern. Into the fray of the HG-SOC/TME double and triple co-cultures, the secretion of ET-1 and VEGF, that share a common co-regulation, was inhibited upon the administration of macitentan. Functionally, macitentan, mimicking the effect of bevacizumab, interfered with the HG-SOC/TME FFL-driven communication that fuel the HG-SOC invasive behaviour. The identification of ET-1 and VEGF FFL as tumor and TME actionable vulnerabilities, reveal how ET-1R blockade, targeting the HG-SOC cells and the TME simultaneously, may represent an effective therapeutic option for HG-SOC patients. Overall design: In this work we report the application of the RNA-sequencing analysis to explore the contribution of endothelin-1 (ET-1)/ET-1 receptors (ET-1R) axis activation on the fluctuations in the transcriptional traits of high-grade serous ovarian cancer (HG-SOC) cells. We performed a global transcriptional mapping in a preclinical relevant model of patient-derived primary cultures of HG-SOC cells (PMOV10), harboring TP53 mutation, isolated from ascitic fluid. PMOV10 cells were stimulated with endothelin-1 (ET-1, 100 nM), or with the ET-1R antagonist macitentan (MAC, 1µM), alone or in combination with ET-1, or with acetic acid (1% in H20), as vehicle (CTR) for 24 hours, by employing 4 biological replicates for each condition.