Dynamic model of differentiation in Ewing's sarcoma cells. Comparative analysis of morphologic, immunocytochemical, and oncogene expression parameters.
We report the establishment of a model of neural differentiation in four well-characterized Ewing's sarcoma cell lines. This process was induced by serum-depleted medium (1% fetal bovine serum) and agents such as dibutyryl cyclic AMP and retinoic acid. The morphologic changes were characterized predominantly by the presence of neurite-like elongated processes showing varicosities and branching along their course with numerous internal filaments and electron-dense granules. Immunocytochemically, differentiation was accompanied by a considerable increase in reactivity for neural markers of several types: neuroblastic, neuroepithelial, neuroendocrine, Schwannian and even glial. In contrast, the tumor promoter, phorbol 12-myristate 13-acetate inhibited differentiation. Several morphologic changes were observed in phorbol 12-myristate 13-acetate-treated cells: the cells became smaller and rounder, were poorly adherent to substrate, by electron microscopy lacked cytoplasmic organelles, electron-dense granules or neural processes, and showed decreased expression of neural markers. Northern blot analysis was performed to establish whether there was any relationship between neural differentiation and degree of N-myc, c-myc and dbl oncogene expression. There was no N-myc oncogene expression in the mRNA of Ewing's sarcoma cells, even after neural induced differentiation. The degree of c-myc and dbl oncogene expression appeared heterogeneous, and varied with the culture condition. Based on these results, it may be inferred that Ewing's sarcoma cells in vitro display a variable neural phenotype, there being a variety of biologic responses to diverse culture media and various differentiation agents, but with no consistent effect on N-myc, c-myc and dbl oncogene expression.
Noguera
R
R
Department of Pathology, Medical School, University of Valencia, Spain.
Triche
T J
TJ
Navarro
S
S
Tsokos
M
M
Llombart-Bosch
A
A
D003994:Bucladesine / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects; D016895:Culture Media, Serum-Free / Q000494:pharmacology; D015870:Gene Expression; D006801:Humans; D007150:Immunohistochemistry; D009474:Neurons / Q000166:cytology; D009857:Oncogenes; D012512:Sarcoma, Ewing / Q000235:genetics / Q000276:immunology / Q000473:pathology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014212:Tretinoin / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D016895:Culture Media, Serum-Free; D014212:Tretinoin; D003994:Bucladesine; D013755:Tetradecanoylphorbol Acetate