ADSC-Derived CCL8 Regulates HIF-1α Signaling and Promotes Colorectal Cancer Progression in a 3D Coculture Platform

This study aimed to recapitulate adipose-tumor interactions within the colorectal cancer (CRC) tumor microenvironment (TME) and to elucidate the role of adipose-derived stem cells (ADSCs) in regulating CRC progression through cytokine-mediated signaling. Human ADSCs were isolated from adipose tissue and directly cocultured with CRC cells using an oxygen-permeable, PDMS-based 3D coculture chip, followed by cytokine profiling of conditioned media, immunofluorescence analysis of spheroids, FACS-based cell separation, and molecular analyzes including western blotting, qPCR, and immunoprecipitation to interrogate HIF-1-related mechanisms. The results revealed that cancer-associated ADSCs secrete CCL8, which markedly enhances CRC cell migration. Mechanistically, ADSC-derived CCL8 activated the ERK signaling pathway in CRC cells, leading to increased HIF-1α protein accumulation without significant changes in protein stability. This was accompanied by enhanced interaction between HIF-1α and the transcriptional cofactor p300. Consequently, HIF-1α transcriptional activity was increased, resulting in the upregulation of downstream epithelial-mesenchymal transition markers and promoting a pro-migratory and aggressive cancer phenotype. These effects were particularly pronounced in the coculture system, where intensified crosstalk between ADSCs and cancer cells amplifies oncogenic signaling within the TME. Collectively, these findings demonstrate that ADSC-derived CCL8 functions as a key mediator of adipose-tumor crosstalk in CRC progression by driving HIF-1α-dependent signaling pathways. Furthermore, the PDMS-based 3D coculture platform employed in this study provides a robust and physiologically relevant experimental system for dissecting complex cell-cell interactions and cytokine-driven mechanisms within the TME of CRC.