Molecular characterization of glioblastoma cell differentiation.
OBJECTIVE
Induction of cellular differentiation continues to be an attractive therapeutic strategy for malignant glioma. The purpose of this study was to develop a convenient in vitro model system for glioblastoma differentiation and to then characterize it using conventional techniques and flow cytometry.


METHODS
A subline of U138 MG cells ("U138B") was treated with 0 to 4 mmol/L sodium butyrate (or serum deprivation) for up to 96 hours. Cells were initially studied for effects on proliferation, morphology, and glial fibrillary acidic protein (GFAP) staining. Northern blot and immunoblot analyses of c-myc expression were performed. Multiparameter flow cytometry was then used to analyze GFAP, c-myc protein, and total cellular protein fluorescence and to relate them to changes in cell cycle distribution.


RESULTS
Butyrate treatment produced a dose-dependent inhibition of cellular proliferation and changes in morphology, GFAP staining, and c-myc expression consistent with a differentiation response. Detailed flow cytometric studies, including subpopulation analysis, showed that during 72 hours of treatment with 2 mmol/L butyrate, mean GFAP fluorescence increased to 420%, whereas c-myc protein decreased to 45 +/- 13% and total cellular protein increased to 181 +/- 17%. The effects of butyrate were distinct from those of serum deprivation and were not simply the result of cells shifting into Gzero/G1.


CONCLUSIONS
The butyrate-induced responses of the U138B cell line provide a convenient model system for studying the molecular events accompanying the differentiation of glioblastoma cells. Multiparameter flow cytometry is a useful technique for characterizing such differentiation.
Engelhard
H H
HH
Division of Neurosurgery, Northwestern University Medical School, Chicago, Illinois, USA.
Duncan
H A
HA
Dal Canto
M
M
D014408:Biomarkers, Tumor / Q000235:genetics; D001932:Brain Neoplasms / Q000235:genetics*; D002087:Butyrates / Q000494:pharmacology; D020148:Butyric Acid; D002454:Cell Differentiation / Q000235:genetics*; D002455:Cell Division / Q000187:drug effects / Q000235:genetics*; D005434:Flow Cytometry; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D005904:Glial Fibrillary Acidic Protein / Q000235:genetics; D005909:Glioblastoma / Q000235:genetics*; D006801:Humans; D007124:Immunoenzyme Techniques; D066298:In Vitro Techniques; D009363:Neoplasm Proteins / Q000235:genetics; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics; D014407:Tumor Cells, Cultured / Q000187:drug effects
D014408:Biomarkers, Tumor; D002087:Butyrates; D005904:Glial Fibrillary Acidic Protein; D009363:Neoplasm Proteins; D016271:Proto-Oncogene Proteins c-myc; D020148:Butyric Acid