Characterization of gangliosides in human uveal melanoma cells

We have evaluated the ganglioside composition of 20 primary uveal melanomas, of 2 cell lines derived from 2 uveal melanomas, of a liver metastasis from an uveal melanoma, and of 8 normal choroids. The results show that normal choroid tissue has a ganglioside content similar to the primary tumors of uveal melanoma except for GD1a, GD1b, and GT1b, which are present only on normal choroid tissues. On the other hand, the uveal melanomas have similarities with cutaneous melanomas, since GM3 (74%) and GD3 (25%) are found in both tissues and are present in about the same amounts. However, GM1 was found in 50%, GM2 in 20% and GD2 in none of the uveal melanomas. According to data published by others, cutaneous melanoma biopsies have no GM1, whereas GM2 is present in 100% and GD2 in 71% of tumor tissues. Transplantation of the 2 cell lines subcutaneously into nude mice resulted in the growth of tumors which had a ganglioside profile larger than that of the primary tumors. GM3 was significantly diminished and GD3 significantly increased in the primary uveal melanoma from patients who had received radiotherapy before enucleation compared with those who did not have radiotherapy. These results show that uveal melanomas contain gangliosides that could be used as targets for monoclonal antibody therapy.