To characterize
biomarkers in neural
tumors, we analyzed the acidic
lipid fractions of 13 neural tumor cell lines using
enzyme-linked immunoabsorbent assay (ELISA) and high-performance thin-layer chromatography (HPTLC) immunostaining. Sulfated glucuronosyl
glycosphingolipids (SGGLs) are cell surface molecules that are endowed with the Human Natural Killer-1 (HNK-1)
carbohydrate epitope. These
glycosphingolipids (GSLs) were expressed in all cell lines with concentrations ranging from 210 to 330 ng per 2 x 10(6) cells.
Sulfoglucuronosyl paragloboside (
SGPG) was the prominent species with lesser amounts of sulfoglucuronosyl lactosaminyl
paragloboside (
SGLPG) in these tumor cell lines as assessed by quantitative HPTLC immunostaining. Among the
gangliosides surveyed, GD3 and 9-O-acetylated GD3 (OAc-GD3) were expressed in all tumor cell lines. In contrast, fucosyl-GM1 was not found to restrict to
small cell lung carcinoma cells. In addition, we have analyzed serum antibody titers against
SGPG, GD3, and OAc-GD3 in patients with neural
tumors by ELISA and HPTLC immunostaining. All sera had high titers of
antibodies of the
IgM isotype against
SGPG (titers over 1:3,200), especially in
tumors such as
meningiomas,
germinomas, orbital
tumors,
glioblastomas,
medulloblastomas, and
subependymomas. Serum in a patient with
subependymomas also had a high anti-SGGL antibody titer of the
IgG and
IgA types (titers over 12,800). The titer of anti-GD3 antibody was also elevated in patients with
subependymomas and
medulloblastomas; the latter cases also had a high titer of antibody against OAc-GD3. Our data indicate that certain GSL
antigens, especially SGGLs, GD3, and OAc-GD3, are expressed in neural
tumor cells and may be considered as
tumor-associated
antigens that represent important
biomarkers for neural
tumors. Furthermore, antibody titers in sera of patients with these
tumors may be of diagnostic value for monitoring the presence of
tumor cells and
tumor progression.