The broad objective of this research is to characterize the composition of glycosphingolipids (gangliosides and neutral glycolipids) in macrophages that infiltrate experimental mouse brain tumors. Although glycosphingolipids (GSLs) were studied previously in peritoneal macrophages, there have been no previous studies in either man or mouse on the GSL composition of macrophages that infiltrate brain tumors. Our preliminary studies in mouse brain tumors suggest that host infiltrating macrophages contribute significantly to the total GSL composition of solid brain tumors growing in vivo. The proposed research will be conducted on two experimental mouse brain tumors, ependymoblastoma and CT-2A. The two tumors differ in growth behavior, ganglioside composition and in the number of infiltrating macrophages. Glass bead columns will be used to separate macrophages from tumor cells and non- macrophage host-infiltrating cells after enzymatic tumor dissociation. The proposed research will involve the following specific aims: 1) A comparative analysis of GSLs in infiltrating macrophages isolated from the two brain tumors growing in both the brain and subcutaneously in the flank of the C57BL/6 mouse; 2) A similar analysis in these tumors growing in the flank of the SCID (severe combined immune deficiency) mouse.
This second aim will determine the influence of host genetic background on the GSLs of tumor-infiltrating macrophages. The qualitative and quantitative analysis of the GSLs will involve high performance thin-layer chromatography and gas-liquid chromatography, respectively. TLC immunostaining will be used to quanitate the macrophage enriched GSLs, asialo-GM1 (GA1) and GM1b. Although GSLs have been considered for the classification, diagnosis and therapy of brain tumors, it has not been established whether the GSLs are expressed in the neoplastic tumor cells or in tumor-infiltrating host cells. The proposed research can provide new insight on the cellular origin of brain tumor-associated GSLs and on the role of environmental factors in regulating the GSL composition of tumor-infiltrating macrophages.
| Manfredi, M G; Lim, S; Claffey, K P et al. (1999) Gangliosides influence angiogenesis in an experimental mouse brain tumor. Cancer Res 59:5392-7 |
| Ecsedy, J A; Holthaus, K A; Yohe, H C et al. (1999) Expression of mouse sialic acid on gangliosides of a human glioma grown as a xenograft in SCID mice. J Neurochem 73:254-9 |
| Ecsedy, J A; Yohe, H C; Bergeron, A J et al. (1998) Tumor-infiltrating macrophages influence the glycosphingolipid composition of murine brain tumors. J Lipid Res 39:2218-27 |
| Brigande, J V; Seyfried, T N (1998) Glycosphingolipid biosynthesis may not be necessary for vertebrate brain development. Ann N Y Acad Sci 845:215-8 |
| Bai, H; Seyfried, T N (1997) Influence of ganglioside GM3 and high density lipoprotein on the cohesion of mouse brain tumor cells. J Lipid Res 38:160-72 |
| Seyfried, T N; el-Abbadi, M; Ecsedy, J A et al. (1996) Influence of host cell infiltration on the glycolipid content of mouse brain tumors. J Neurochem 66:2026-33 |
