Regulation of Brain Metastatic Breast Cancer Cell Dormancy versus Proliferation on Hyaluronic Acid Hydrogels via Laminin and Laminin-Derived Peptides

Among the secondary target organs for metastatic breast cancer, brain metastasis is extremely aggressive in nature, resulting in lower survival rates. These metastatic cancer cells have the potential to enter a dormant state in the brain, allowing them to survive for extended time periods. The brain microenvironment plays a key role in controlling the dormant phenotype, yet how various components of this microenvironment influence dormancy is not well understood. In this work, we employed hyaluronic acid (HA)-based hydrogels as a mimetic of the brain tissue environment to study the role of biochemical cues, specifically, the impact of laminin and laminin-derived peptides IKVAV and YIGSR on the regulation of brain metastatic breast cancer cell dormancy versus proliferation. We applied varying protein/peptide concentrations and confirmed functionalization on HA hydrogel surfaces. We then seeded 10,000 cancer cells on the hydrogel surface and cultured them for 5 days. We found that in the presence of laminin or IKVAV, MDA-MB-231Br cells transitioned from a rounded to a spread morphology and exhibited enhanced proliferation as the laminin/IKVAV concentration increased. In contrast, in hydrogels functionalized with YIGSR, these cells maintained a rounded morphology, with no impact on proliferation with varying YIGSR concentrations. We confirmed the involvement of αVβ3 integrin in mediating tumor cell phenotype in hydrogels functionalized with laminin. By evaluating known markers of dormancy and proliferation, we found a direct correlation between the presence of laminin and IKVAV and increased phosphorylated extracellular signal-regulated kinase 1/2 (p-ERK) positivity, along with decreased phosphorylated p38 (p-p38) positivity, while in hydrogels functionalized with YIGSR, the levels of both p-ERK and p-p38 remained unaltered. Finally, we demonstrated that when cells were transferred from IKVAV-deficient to IKVAV-rich hydrogels, the hydrogel induced cellular dormancy was reversible. Collectively, our findings provide insights into how laminin and laminin-derived cues regulate brain metastatic breast cancer cell dormancy versus proliferation.