Globotriaosyl Ceramide and Globoside as Major Glycolipid Components of Fibroblasts in Scirrhous Gastric Carcinoma Tissues

Scirrhous gastric cancer is characteristic in that cancer cells proliferate and invade with prominent fibrosis. To search for the expression of specific carbohydrate chains in scirrhous gastric cancer, we have examined the glycosphingolipid composition of scirrhous cancer tissues (n=10) in comparison with that of non-scirrhous cancer tissues (n=10) by means of two-dimensional thin layer chromatography, followed by fast atom bombardment mass spectrometry of the individual glycolipids and immunostaining analysis. The major neutral glycosphingolipids from scirrhous gastric cancer tissues were identified as ceramide monohexoside, ceramide dihexoside, globotriaosyl ceramide (Gb₃) and globoside (Gb₄), while the major acidic glycosphingolipids were II³ Neu-Acα-LacCer, II³ NeuAcα₂-LacCer and sulfatide. Relative concentrations of Gb₃ and Gb₄ in scirrhous gastric cancer tissues (Gb₃+ Gb₄=58%) were two times higher than those in non-scirrhous gastric cancer tissues (29%). Orthotopic fibroblasts cloned from scirrhous gastric cancer tissues showed similar high concentrations of Gb₃ and Gb₄ to scirrhous gastric cancer tissues. Furthermore, immunohistochemical study revealed that Gb₃ and Gb₄ were expressed intensely on the fibroblasts. On the other hand, analysis of glycosphingolipids in four scirrhous gastric cancer cell lines yielded the following results. i) The contents of Gb₃ and Gb₄ were low (6%), compared with orthotopic fibroblasts (62%). ii) Significant amounts of Le^a (pentaglycosylceramide) and Le^b (hexa- and heptaglycosylceramides), which could not be detected in scirrhous cancer tissues, were observed. The results show that the major neutral glycosphingolipids such as Gb₃ and Gb₄ of scirrhous gastric cancer tissues were derived from orthotopic fibroblasts and not from the cancer cells.