Expression differences in TEL-AML1 fusion gene in leukemia glucocorticoid-sensitive and -resistant cell lines.

We investigated the expression differences of the TEL-AML1 fusion gene in a leukemia glucocorticoid (GC)-sensitive cell line (CEM) and a GC-resistant cell line (Jurkat). Changes in TEL-AML1 expression before and after GC exposure were analyzed. Expression of GC-sensitive and GC-resistant leukemia cells following initial diagnosis and during treatment was simulated. Leukemia cells were divided into a GC-unexposed or a GC-exposed group. A methyl thiazolyl tetrazolium assay was used to detect cell proliferation inhibition, flow cytometry was used to observe cell apoptosis, reverse transcription-polymerase chain reaction was used to detect the mRNA expression of TEL-AML1 before and after exposure, and western blotting was used to analyze protein levels of TEL-AML1 before and after exposure. Inhibitory concentrations of 50% of cells in the Jurkat and CEM cells at 24 h were 382 and 9 mM, respectively, and at 48 h they were 216 and 2 mM. The proliferation inhibition effect of dexamethasone sodium phosphate on Jurkat cells was much lower than that on CEM cells. Jurkat cells showed obvious apoptosis after exposure to 100 mM dexamethasone sodium phosphate for 48 h. In the exposed group, Jurkat cells showed higher TEL-AML1 expression than did CEM cells (P < 0.05). In the unexposed group, TEL-AML1 gene expression in Jurkat cells was not affected by GC exposure (P > 0.05), while the CEM cells presented significant differences before and after exposure (P < 0.05). Sustained high expression of TEL-AML1 participated in and maintained the occurrence of GC resistance. Inhibition of TEL-AML1 may provide a new therapeutic approach to reverse GC resistance.