Age-associated changes in type I collagen promote the invasion of BRAF mutated melanoma cells and their resistance to targeted therapies within three-dimensional matrix models.

Melanoma represents the most aggressive form of skin cancer, with the highest rate of mortality. Anti-mutated BRAF therapies, such as vemurafenib, has improved the prognosis for melanoma patients; however, resistance to these targeted therapies frequently emerges. Type I collagen-a key element of the tumor microenvironment-contributes to tumor progression and therapeutic resistance. With aging, type I collagen undergoes structural remodeling that alters its fibrillar organization and mechanical properties. Although these changes have been documented, their impact on BRAF-mutated melanoma cell behavior and drug response remains unclear. In this study, we utilized both in vitro and in vivo models to fill this critical gap by investigating how collagen remodeling associated with advanced age modulates BRAF-mutated melanoma response to vemurafenib. Our findings indicate that in vitro-using a 3D culture matrix model-old collagen promotes increased proliferation of 1205Lu cells and protects both 1205Lu and SKMEL28 cells from vemurafenib effects. This was associated with elevated YAP expression, suggesting a role for mechanotransduction in drug resistance. The 3D collagen matrix spheroid model revealed that aged collagen enhances the invasive properties of 1205Lu cells, which correlated with an upregulation of the AXL receptor. In vivo, vemurafenib reduced tumor growth in athymic mice xenografted with melanoma cells embedded in young collagen matrices, but not in those with aged collagen. Collectively, our data suggest that age-related alterations in type I collagen contribute to reduced efficacy of anti-BRAF therapies in BRAF-mutated melanoma.