Three-dimensional cell spheroid culture and cell viability study of uveal melanoma cell line C918 with luteolin treatment.

Objective: This study aims to investigate the morphological and histological characteristics of three-dimensional cell spheroids derived from the uveal melanoma (UM) cell line C918 and assess the impact of luteolin on their cell viability.

Methods: C918 cells were cultured in ultra-low adsorption 96-well plates, and morphological changes in C918 three-dimensional cell spheroids were observed over varying time intervals. Histological features of C918 multicellular spheroids cultured in ultra-low adsorption 6-well plates were examined using both HE staining and immunohistochemical staining. The CCK8 reagent was employed to measure the optical density at a 450 nm wavelength after 72-h treatments with varying luteolin concentrations in both two-dimensional and three-dimensional cultured C918 cells. The IC50 values were compared between the two culture conditions.

Results: Over time in culture, the volume of C918 three-dimensional cell spheroids gradually increased, and an ischemic- and hypoxic-like region became evident within the spheroids on days 4 to 6 of culture. Histological staining demonstrated positive expression of cell viability marker antibodies (Ki67) and melanoma marker antibodies (MelanA, HMB45, S-100) in the multicellular spheroids from three-dimensional culture. CCK-8 experiments revealed that the IC50 values for luteolin in C918 cells were 183.50 μmol/L in three-dimensional culture and 16.19 μmol/L in two-dimensional culture after 72 h. Three-dimensional cultured C918 cells, treated with varying luteolin concentrations for 72 h, were observed under a microscope. The maximum cross-sectional area showed no statistically significant differences between the groups, but it was reduced in comparison to the control group.

Conclusion: Three-dimensional cultured C918 cell spheroids exhibit histological characteristics similar to real tumors and are less responsive to luteolin than their two-dimensional counterparts. They offer a valuable model for anti-tumor drug screening.