Differentiation of a mouse neuroblastoma variant cell line whose ornithine decarboxylase gene has been amplified.
Differentiation of mouse neuroblastoma cells has been shown to be accompanied by changes in polyamine metabolism and a decrease in polyamine content. We have previously shown that alpha-difluoromethyl ornithine, a suicide inhibitor of ornithine decarboxylase (ODC, EC 4.1.1.17) and suboptimal concentrations of dibutyryl cAMP (0.1 to 0.2 mM) are effective in inducing the differentiation of mouse Neuro-2a (N2a) neuroblastoma cells. Exogenously added putrescine or spermidine can block the action of DFMO and dibutyryl cAMP, suggesting that polyamines may play a regulatory role in neuroblastoma differentiation. We have now isolated from N2a cells a clonal variant line, DF-40, whose ODC gene has been amplified by 40-fold. The DF-40 cells overproduced the ODC enzyme and contained very high levels of putrescine, spermidine and spermine. Treatment of DF-40 cells with dibutyryl cAMP or DFMO/dibutyryl cAMP led to a more than 80% reduction in polyamine content. Such a decrease did not cause the DF-40 cells to differentiate. Polyamine content in the treated DF-40 cells was still comparable or higher than that in the undifferentiated N2a cells. In contrast, serum-deprivation induced full differentiation of DF-40 cells. Levels of polyamine in the differentiated DF-40 cells, however, were also found to be comparable to that in the undifferentiated N2a cells. Exogenously added polyamines could not block the differentiation of DF-40 cells induced by serum-deprivation, suggesting that the action of polyamines in regulating neuroblastoma differentiation may depend on the presence of serum factors.
Chen
Z P
ZP
Department of Chemistry, Rutgers, The State University of New Jersey, New Brunswick.
Chen
K Y
KY
D000110:Acetylcholinesterase / Q000378:metabolism; D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects / Q000235:genetics*; D002460:Cell Line; D004351:Drug Resistance / Q000235:genetics; D000518:Eflornithine / Q000494:pharmacology; D004790:Enzyme Induction / Q000235:genetics; D005784:Gene Amplification; D014644:Genetic Variation; D051379:Mice; D009447:Neuroblastoma / Q000235:genetics*; D009955:Ornithine Decarboxylase / Q000187:drug effects / Q000235:genetics*; D011073:Polyamines / Q000378:metabolism
D011073:Polyamines; D003994:Bucladesine; D000110:Acetylcholinesterase; D009955:Ornithine Decarboxylase; D000518:Eflornithine