title: Effects of 1-beta-D-arabinofuranosylcytosine on proto-oncogene expression in human U-937 cells.
abstract: We have previously demonstrated that declines in c-myc expression precede the induction of c-fos and c-fms transcripts during monocytic differentiation of human leukemia (HL-60 and U-937) cell lines. The present study has monitored the effects of 1-beta-D-arabinofuranosylcytosine (ara-C) on proto-oncogene expression in U-937 cells. The results demonstrate that ara-C inhibits both U-937 proliferation and c-myc expression in a concentration- and time-dependent manner. At non-toxic concentrations of ara-C, these decreases in c-myc RNA occur in the absence of changes in the level of actin transcripts. The results also demonstrate that ara-C increases c-fos but not c-fms expression. Similar findings have been obtained with retinoic acid. Furthermore, although both agents induce a more mature U-937 phenotype, ara-C is a relatively weak inducer of these cells. These findings would suggest that the changes in proto-oncogene expression induced by ara-C may be related to induction of differentiation or the inhibitory effects of this agent on proliferation.
mesh_terms: D000199:Actins / Q000235:genetics; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D003561:Cytarabine / Q000494:pharmacology*; D006801:Humans; D007938:Leukemia; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins / Q000235:genetics; D011519:Proto-Oncogenes / Q000187:drug effects*; D014158:Transcription, Genetic; D014212:Tretinoin / Q000494:pharmacology
chemical_list: D000199:Actins; C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; D003561:Cytarabine; D014212:Tretinoin