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[Preprint]. 2026 Jan 15:2026.01.14.699463. [Version 1] doi: 10.64898/2026.01.14.699463

Figure 2. ECM rigidity modulates GDF-15 expression in melanoma cells cultured on GelMA microgel.

Figure 2.

Representative immunofluorescence images showing GDF-15 expression (yellow), nuclei (green), and F-actin (magenta) in melanoma cells (A: UACC 903; B: A375P; C: WM4235) cultured with soft (G’ ≈ 10 kPa) and stiff (G’ ≈ 100 kPa) microgel matrices. Increased GDF-15 expression is observed in the stiff microenvironment, resembling conditions found in acral melanoma.

(D) Quantification of GDF-15 fluorescence intensity in melanoma cells (Cutaneous: UACC 903 & A375P; Acral: WM4235) cultured in soft and stiff matrices. Box graphs represent median ± SEM.

(E) Western blot analysis of GDF-15 expression in melanoma cells (UACC 903 & A375P) under soft or stiff GelMA ECM matrix conditions. ERK2 serves as a loading control, and GDF-15 protein levels are quantified and normalized to ERK2. Cells in the stiff matrix show increased GDF-15 expression compared to the soft matrix. (F, G, H) Modeling GelMA microgel stiffness in melanoma tumors.

(F, G) Representative immunofluorescence images showing GDF-15 (yellow), nuclei (blue), and F-actin (magenta) in tumor sections (F: UACC 903; G: A375P) after 7 days of growth in mice. (H) Quantification of GDF-15 fluorescence intensity, equivalent to expression in tumor cells after growing on stiff or soft microgels.