Uncovering the Potential of 3D Spheroids for Modeling the Cellular Crosstalk Within the Tumor Microenvironment in HNSCC.

Head and neck squamous cell carcinoma (HNSCC) progression is profoundly influenced by dynamic cellular crosstalk within the tumor microenvironment (TME), where interactions between cancer cells, stromal components, and immune populations orchestrate therapeutic resistance, metastasis, and immune evasion. This review examines the utility of three-dimensional (3D) spheroid models as physiologically relevant platforms for investigating these cellular interactions compared with conventional two-dimensional (2D) cultures. By incorporating cancer-associated fibroblasts (CAFs), tumor-associated macrophages (TAMs), endothelial cells, and cancer stem cells (CSCs) into multicellular spheroid systems, these models recapitulate several key features of the TME and provide insights into how signaling mediated by cytokines, exosomes, and direct cell-cell interactions may influence tumor progression. Studies utilizing spheroid models have highlighted processes associated with CAF-mediated CSC enrichment, TAM-driven immune modulation, and endothelial cell-supported niche formation, which have been linked to epithelial-mesenchymal transition (EMT), hypoxic adaptation, and metabolic reprogramming. Furthermore, 3D spheroid systems can reproduce aspects of spatial organization, extracellular matrix (ECM) remodeling, and microenvironmental gradients that are difficult to achieve in traditional 2D cultures and are relevant to the study of therapeutic resistance. The review also discusses recent advances, including microfluidic technologies and co-culture systems, which enhance the investigation of stromal-immune-tumor interactions and may facilitate the identification of potential therapeutic targets. Overall, this review highlights the value of 3D spheroid models as versatile preclinical tools for advancing our understanding of HNSCC biology and supporting the development and evaluation of personalized therapeutic strategies targeting pro-tumorigenic communication networks.