Paracrine Signals from the Tumor Microenvironment Modulate Stem-Cell Collagen Interaction, Remodeling and Reprogramming Toward a Cancer-Associated Phenotype

The tumor microenvironment is continuously shaped by reciprocal interactions between malignant cells and stromal components, with mesenchymal stem cells (MSCs) serving as key regulators of extracellular matrix (ECM) deposition and remodeling. In this study, we examined how cancer cell-derived secretomes from two hematological cancer cell lines, RPMI 8226 (multiple myeloma) and HG-3 (B-cell leukemia), influence the functional behavior of human adipose-derived MSCs (AD-MSCs). Exposure to these secretomes altered MSC proliferative capac-ity (2x faster doubling compared to the control), induced senescence (~3-4x higher than that of the control), and significantly modified MSC mediated colla-gen remodeling, as quantified using FITC-collagen coated substrata. Tumor con-ditioned media also reduced MSC spreading area (~2100 µm2 compared to the control ~2500 µm2) and induced distinct morphological changes indicative of a possible shift toward a cancer associated stromal phenotype. To assess the stabil-ity of these changes, MSCs were analyzed following a withdrawal of the cancer cell secretomes and further cultured in secretome-free environment, which re-vealed that most phenotypic and functional alterations were maintained and that the reprogramming is partially irreversible. These findings also demonstrate that the paracrine factors released by RPMI 8226 and HG-3 cells modulate MSC func-tionality upon interaction with collagen, providing insight into stromal contribu-tions to tumor progression.