Genetically fluorescent melanoma bone and organ metastasis models

We report here the establishment and metastatic properties of bright, highl y stable, green fluorescent protein (GFP) expression transductants of the B 16 mouse malignant melanoma cell line and the LOX human melanoma line. The highly fluorescent malignant melanoma cell lines allowed the visualization of skeletal and multiorgan metastases after i.v. injection of B16 cells in C57BL/6 mice and intradermal injection of LOX cells in nude mice. The melan oma cell lines were transduced with the pLEIN expression retroviral vector containing the GFP and neomycin resistance genes. Stable B16F0 and LOX clon es expressing high levels of GFP were selected stepwise in vitro in levels of G418 of up to 800 mu g/ml, Extensive bone and bone marrow metastases of B16F0 were visualized by GFP expression when the animals were sacrificed 3 weeks after cell implantation. Metastases for both cell lines were visualiz ed in many organs, including the brain, lung, pleural membrane, liver, kidn ey, adrenal gland, lymph nodes, skeleton, muscle, and skin by GFP fluoresce nce. This is the first observation of experimental skeletal metastases of m elanoma, which was made possible by GFP expression. These models should fac ilitate future studies of the mechanism and therapy of bone and multiorgan metastasis of melanoma.