Abstract 2547: The impact of aging on YAP activity in melanoma cells: nuclear localization and condensate formation

Abstract Melanoma is a highly lethal form of skin cancer which disproportionately impacts older patients, leading to increased rates of melanoma diagnosis and worse prognostic outcomes in this population. This is driven, in part, by higher rates of invasion and therapy resistance caused by age-related changes to the tumor microenvironment. One mechanism this occurs through is the increased senescence of fibroblasts which disrupts extracellular matrix (ECM) deposition, resulting in a more aligned and stiffer matrix. The Hippo pathway is known to shut off in response to matrix stiffness which allows for increased YAP nuclear localization. YAP is a known marker for increased invasion in melanoma. While the importance of YAP in melanoma is known, it is understudied in the context of an aging tumor microenvironment. Additionally, YAP’s ability to form transcriptionally active condensates and whether this activity is vital to its function has yet to be elucidated in melanoma. Our lab has previously shown that the increased stiffness of cell-derived matrices (CDMs) created with aged fibroblast cell lines when compared to CDMs from young fibroblasts is sufficient to increase YAP nuclear localization in HUVEC cells. We hypothesize that age-associated increases in ECM stiffness will also increase YAP nuclear localization in melanoma cells, resulting in increased YAP target gene activation, YAP condensate formation, and downstream pro-invasive melanoma cell behavior. To investigate this we employed several techniques, including the creation of CDMs from aged/young fibroblasts, immunofluorescence (IF) staining, and Airyscan super-resolution microscopy. Our data suggests that melanoma cells grown on cell-derived matrices (CDMs) created by aged dermal fibroblasts have increased nuclear YAP localization when compared to cells grown on CDMs created with young dermal fibroblasts. However, the downstream effects of this increased YAP activity on invasion and therapy resistance in melanoma cells as well as whether melanoma cells being plated on aged CDMs increases YAP condensate formation are still being examined. Our IF data from these melanoma cells also suggests that YAP condensates assemble endogenously in melanoma when plated on these CDMs, and the importance of their role in YAP target gene activation warrants further study. As we continue this work, it will allow us to better understand how the aging tumor microenvironment changes YAP activity and the downstream effect this has on the invasive behavior that is characteristic of melanoma in older patients. Citation Format: Ethan Black, Danfeng Cai, Ashani Weeraratna. The impact of aging on YAP activity in melanoma cells: nuclear localization and condensate formation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 2547.