Differential induction of Egr-1 expression in WEHI-231 sublines does not correlate with apoptosis.
To determine whether the absence of inducible Egr-1 expression correlates with apoptosis and growth arrest, we compared the inducible expression of two Egr family members (Egr-1 and Egr-2) in three sublines of WEHI-231. Expression of Egr-2 is induced in all sublines of WEHI-231 following surface immunoglobulin (sIg) cross-linking, but Egr-1 expression is induced in only two. We find that the lack of inducible Egr-1 expression corresponded to an increase in the methylation pattern of the Egr-1 gene. In spite of these differences in Egr-1 expression, all the sublines demonstrate similar inhibition of [3H] thymidine incorporation following anti-Ig treatment. Growth arrest leads to apoptosis in only two of the sublines, but apoptosis does not correlate with the absence of inducible Egr-1 expression. Demethylation, by treatment with 5-azacytidine, in the Egr-1 non-expressing subline allows for induction of Egr-1 expression by anti-Ig, but fails to prevent growth arrest and apoptosis. Therefore, we conclude that the lack of Egr-1 expression is not responsible for either the apoptotic response or growth arrest induced by anti-Ig in WEHI-231.
Gottschalk
A R
AR
Department of Pathology, University of Chicago, IL 60637.
Joseph
L J
LJ
Quintáns
J
J
D000818:Animals; D000888:Antibodies, Anti-Idiotypic / Q000276:immunology; D017209:Apoptosis; D004268:DNA-Binding Proteins / Q000235:genetics*; D051766:Early Growth Response Protein 1; D015972:Gene Expression Regulation, Neoplastic; D017874:Immediate-Early Proteins; D016393:Lymphoma, B-Cell / Q000235:genetics* / Q000473:pathology; D008745:Methylation; D051379:Mice; D011817:Rabbits; D051381:Rats; D014157:Transcription Factors / Q000235:genetics*; D014407:Tumor Cells, Cultured
D000888:Antibodies, Anti-Idiotypic; D004268:DNA-Binding Proteins; D051766:Early Growth Response Protein 1; C486109:Egr1 protein, mouse; C486110:Egr1 protein, rat; D017874:Immediate-Early Proteins; D014157:Transcription Factors; C044203:anti-IgM