MODULATION OF WNT SIGNALING IN THE CROSSTALK BETWEEN DORMANT COLORECTAL CANCER CELLS AND HEPATIC STROMAL CELLS

BACKGROUND-AIM. The liver is the primary site of metastasis in colorectal cancer (CRC). Metastatic spread is influenced by both a favorable tissue microenvironment and the intrinsic plasticity of CRC cells. The Wnt/β-catenin signaling pathway, essential for liver homeostasis, is often aberrantly activated in CRC and promotes the survival, adaptation, and proliferation of metastatic cells within the liver niche. This study aims to investigate the interaction between dormant CRC cells and hepatic stromal cells, focusing on the modulation of Wnt ligands. METHODS. SW620 and HCT116 CRC cell lines (MSS and MSI, respectively) and HepG2 liver cells were used. Cell viability, metabolic activity, cell cycle progression, and extracellular vesicle (EV) release were assessed by colorimetric assays and flow cytometry (FACS) after serum deprivation and treatment with the Porcupine inhibitor IWP2 to inhibit Wnt ligand secretion. HepG2 cells were exposed to conditioned media from quiescent CRC cells. Wnt ligand expression was analyzed by qRT-PCR, and APC and β-catenin by Western blotting. Selected Wnt ligands were validated in 15 paired primary CRC and synchronous colorectal liver metastasis (CRLM) samples. RESULTS. The MSS and MSI cellular models of CRC exhibited distinct adaptive responses to starvation and treatment with IWP2, with differential regulation of gene expression for Wnt3a, Wnt5a, Wnt7b, and APC, as well as in the production of EVs. Hepatic stromal cells were significantly influenced by factors secreted by quiescent CRC cells, showing altered expression of Wnt ligands and β-catenin. In particular, Wnt7b emerged as a modulator of intercellular communication. Consistent with this finding, Wnt7b expression was higher in tissues with CRC liver metastases (CRLM) compared to the corresponding primary CRC samples. CONCLUSION. While Wnt/β-catenin signaling have been implicated in colorectal cancer progression and metastasis, their role in the crosstalk between dormant CRC cells and the hepatic microenvironment remains poorly defined. Our findings demonstrate that dormant CRC cells interact with hepatic stromal cells through remodeling of the Wnt/β-catenin pathway, highlighting Wnt7b as a potential context-dependent driver of the hepatic microenvironment. These preliminary data warrant validations in more physiologically relevant models and larger clinical cohorts, together with functional studies to further define the role of Wnt7b in CRC-liver crosstalk.