| Abstract |
In order to evaluate the proliferation and differentiation potentials of
ethylnitrosourea (ENU)-induced glioma cells, the author attempted to
obtain a cell line that maintains glial features in long term culture. One
of five cell lines cultivated from ENU-induced rat gliomas deserved
particular interest because of the differentiation of the neoplastic glia.
This cell line, designated as HITS glioma, had a polygonal cell body and
formed a monolayer with pile-up foci in vitro, in contrast to the other
cell lines, which showed a mesenchymal drift through passages. GFAP-
positive cells, found in the primary culture, disappeared in the late
passages of HITS glioma as they did in the other cell lines.
Galactocerebroside (GC) and GD3 ganglioside were not expressed in the cell
lines during culture. Subcutaneous inoculation of HITS glioma into
neonatal rats induced tumors with various histopathological components
mimicking the histopathological appearance of ENU-induced gliomas. The
components also had a fraction of GFAP-positive cells. These findings
indicate that HITS glioma cells may be composed of immature glial cells
and differentiate into astrocytic cells under certain conditions. Insulin-
like growth factor I (IGF-I), which promoted the proliferation of GFAP-
positive cells in neonatal glia, was used to evaluate the mechanism(s) of
proliferation and/or differentiation of HITS glioma. IGF-I did not induce
the expression of GFAP in HITS glioma, even though it promoted the
proliferation of HITS glioma. Although the mechanism involving the
astrocytic differentiation of HITS glioma is unknown, HITS glioma may
serve as a research tool in evaluating the mechanisms of proliferation and
differentiation of neoplastic glia.
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