Cancer remains a significant global health challenge, ranking as the second leading cause of death in developed countries, with nearly 20 million cases diagnosed in 2022. Tumors are heterogeneous, composed of multiple cell populations that include cancer cells, stromal cells, and infiltrating immune cells, all embedded in an extracellular matrix (ECM) that provides a niche conducive to tumor development. This tumor microenvironment (TME) influences key processes such as cell signaling, transport, motility, metastasis, and immune responses, and it is shaped by genetic, epigenetic, and transcriptomic changes, as well as environmental factors. Cancer stem cells (CSCs), responsible for tumor initiation and progression, add complexity to the TME and represent a critical therapeutic target for improving treatment outcomes and reducing metastasis. Oncology research faces a significant challenge, with over 97% of antitumor drug candidates failing clinical trials due to tumor heterogeneity, lack of predictive biomarkers, CSC-mediated resistance, and the absence of preclinical models that accurately reflect the patient’s reality. Three-dimensional (3D) models, which incorporate tumor ECM, offer a promising alternative to traditional 2D models, better mimicking the complexity of the TME and enabling more accurate studies of cell behavior and therapeutic responses. This thesis focuses on developing ECM substitutes for different tumor types (head and neck squamous cell carcinoma HNSCC, and breast cancer BC) to biofabricate preclinical tumor models that recapitulate the cellular and compositional heterogeneity of the TME. In the development of the HNSCC model, the approach was using a decellularized ECM (dECM) derived from fibroblasts (fdECM) combined with alginate and gelatin to form a 3D hydrogel. This model integrated CSCs from the Cal-27 cell line, along with stromal components like FBs and MSCs, to mimic the HNSCC TME. The fdECM preserved essential ECM components, including collagen, fibronectin, and laminin, contributing to the hydrogel’s ability to promote cell adhesion, maintain viability, and drive robust cell proliferation. The effects of melatonin were tested on the model, showing antiproliferative effects on HNSCC CSCs and a reduction in tumor invasion and migration markers. This model provided a valuable tool for precision oncology, closely mimicking the HNSCC TME. The final phase developed a 3D BC tumor model by adapting dECMs to specific tumor subtypes. Protocols were optimized to obtain decellularized human adipose matrices (hDAM) and dECMs from BC cell lines representing four molecular subtypes: Luminal A (MCF-7), Luminal B (BT474), HER2+ (SKBR3), and TNBC (MDA-MB-231). These matrices retained essential ECM components and showed subtype-specific differences in composition and structural properties. The matrices were used to generate tumor models that reflected the aggressiveness of each subtype. The models showed different patterns of cellular reorganization, ECM remodeling, and TME activation and their mechanical properties correlated with tumor aggressiveness. Additionally, the models were tested with patient-derived breast cancer organoids (BCOs) to study drug responses, revealing that the matrices enhanced differential drug resistance. In conclusion, the research highlights the importance of using multicellular ECMbased tumor models that replicate the complexity of the TME. These models not only reveal tumor type-specific differences but also provide valuable tools for understanding tumor behavior, improving drug screening, and advancing personalized cancer therapies.
Julia López de Andrés (Wed,) studied this question.