The glioma-associated gangliosides 3'-isoLM1, GD3 and GM2 show selective area expression in human glioblastoma xenografts in nude rat brains

This work describes the in vivo expression and distribution of glioma-associated gangliosides (GD3, GM2, 3'-isoLM1) in a novel human brain tumour nude rat xenograft model. In this model, the tumours, which are established directly from human glioblastoma biopsies, show extensive infiltrative growth within the rat brain. This model therefore provides an opportunity to study ganglioside expression not only within the macroscopic tumour, but also in brain areas with tumour cell infiltration. The ganglioside expression was studied by confocal microscopy of immunostained brain sections using antiganglioside monoclonal antibodies. Xenografts from four human glioblastoma multiformes were established in rats and the brains removed after 3-4 months. Ganglioside GD3 was expressed in the tumour parenchyma while ganglioside 3'-isoLM1 was more abundantly expressed in the periphery of the tumour associated with areas of tumour cell invasion. GM2 expression was only seen in one tumour, where it was located within the main tumour mass. Double staining with a pan antihuman monoclonal antibody (3B4) and the antiganglioside monoclonal antibodies confirmed that the ganglioside expression was associated with tumour cells. This work supports the concept of different biological roles for individual gangliosides and indicates that antibodies or ligands directed against GD3 and 3'-isoLM1 might be complementary when applied in the treatment of human glioblastomas.