Page 117 - SRPSKO DRUŠTVO ISTRAŽIVAČA RAKA

SDIRSACR Oncology Insights

P21

Role of Eicosanoid Receptor in Stroma – Cancer Communication

Tommy Chastel , Andrei Turtoi 1,2
1,2

1 Institut de Recherche en Cancérologie de Montpellier, IRCM
2Team Turtoi : Tumor microenvironment and treatment resistance

Keywords: CAF, PUFA, Metabolism, HCC, Tumor Microenvironment

Background: The tumor microenvironment (TME) is a complex and dynamic system composed of multiple cell types,
including immune cells, endothelial cells, and cancer-associated fibroblasts (CAFs), which interact with cancer cells to
influence tumor growth, metastasis, and resistance to therapy. Among these, CAFs are a particularly abundant and
active component in many solid tumors, yet their role in cancer progression remains underexplored compared to
immune or vascular interactions.
Recent studies have highlighted that CAFs can influence tumor biology through the secretion of cytokines, remodeling
of the extracellular matrix, and metabolic interactions. However, our understanding of the specific surface receptors
and signaling mechanisms mediating CAF–cancer cell crosstalk is limited. In this study, we investigate a novel G-protein-
coupled receptor (GPCR), EICOR1, and its ligand EICO1, as potential mediators of CAF-driven effects in hepatocellular
carcinoma (HCC), a highly aggressive liver cancer with limited therapeutic options.
Materials and Methods: To identify CAF-specific receptors relevant in HCC, we performed an integrative analysis
of public single-cell RNA sequencing (scRNAseq) and spatial transcriptomics datasets from HCC tumors. Differential
expression analysis revealed a subset of GPCRs selectively enriched in CAFs, among which the eicosanoid receptor
EICOR1 was highly and specifically expressed.
We validated the spatial expression of EICOR1 using RNAscope in situ hybridization and spatial transcriptomics on
patient-derived HCC tissue samples. To study its functional relevance, we employed the chick embryo chorioallantoic
membrane (CAM) assay by co-engrafting human CAFs with liver cancer cells, in the presence or absence of EICOR1
activation.
In vitro assays were conducted to evaluate downstream signaling pathways and kinase activity in fibroblasts.
Metabolomic profiling was performed on matched primary and secondary liver tumor samples from patients to assess
the abundance of EICO1, the natural ligand of EICOR1. Furthermore, fibroblast-conditioned media were subjected to
proteomic analysis to identify secreted factors that may mediate anti-angiogenic effects.
Results: CAF-specific Expression of EICOR1: scRNAseq and spatial transcriptomics data revealed that EICOR1 expression
is restricted to the stromal compartment of HCC tumors, specifically in CAF populations, with negligible expression in
tumor epithelial or immune cells. RNAscope analysis confirmed this localization in multiple patient samples. Functional
Impact on Angiogenesis: In the CAM assay, fibroblasts expressing EICOR1, when co-engrafted with liver cancer cells and
stimulated with EICO1, displayed a marked reduction in tumor-induced neoangiogenesis compared to control groups.
This reduction was quantifiable through imaging and vascular marker analysis.
Mechanistic Insights: Kinase profiling in vitro indicated that EICOR1 activation leads to downregulation of several pro-
tumorigenic kinases in fibroblasts, suggesting a reprogramming of their functional state. Among the most significantly
altered were pathways associated with cell motility, inflammation, and extracellular matrix remodeling. Metabolomic
Correlations in Human Tumors: Analysis of matched tumor and adjacent non-tumor liver tissue from patients showed
that levels of the natural ligand EICO1 were significantly lower in the tumor regions. This suggests either ligand
depletion or altered synthesis in the tumor microenvironment. Importantly, high EICOR1 expression in patient tumor
samples was associated with better overall survival, supporting its potential protective role. Secretome Profiling:
Proteomic analysis of fibroblast-conditioned media following EICOR1 activation revealed increased secretion of known
anti-angiogenic proteins, including tissue inhibitors of metalloproteinases (TIMPs). These findings provide a possible
mechanistic explanation for the observed anti-angiogenic phenotype.
Conclusions: Our findings establish EICOR1 as a novel CAF-specific eicosanoid receptor involved in modulating
angiogenesis and tumor–stroma interactions in HCC. The selective expression of EICOR1 in the tumor stroma, its
anti-angiogenic function upon activation, and the correlation of its expression with patient survival suggest that this
receptor–ligand axis may serve as both a biomarker and a therapeutic target.
We propose that EICO1–EICOR1 signaling suppresses the pro-tumorigenic function of CAFs and supports an anti-
angiogenic phenotype. These insights pave the way for the development of new therapeutic strategies that aim to
reprogram or target the CAF compartment in liver cancer. Specifically, small-molecule agonists or mimetics of EICO1
could offer a novel approach to disrupt the tumor-promoting CAF–cancer cell communication network.
Currently, we are engaged in the synthesis and preclinical evaluation of compounds targeting this newly identified

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