[The influence of different WT1 gene isoforms expression pattern on the differentiation of leukemia cell line NB4]

To study the potential effects of exogenous WT1 gene isoform on the differentiation of leukemia cell line NB4 and its possible molecular mechanisms.

The recombinant eukaryotic expression vector (pCB6 + /WTA) containing full-length human WT1 isoform (WTA: -17AA/ -KTS) cDNA and the blank pCB6 + vector were transfected into leukemia cell line NB4 by electroporation. The WTA mRNA and protein in cells were detected by RT-PCR and Western blot. Cell morphology, NBT reduction and CD11b antigen expression in NB4 cells were assayed to evaluate cell differentiation. Expression of PML/RARalpha, p21 and c-myc genes was determined by semi-quantitative RT-PCR after transfection.

Compared with NB4/WTA cells, NB4 and NB4/CMV (NB4 cells transfected with pCB6 + vector) cells had higher morphological differentiation rates and higher CD11b expression levels after exposure to ATRA for 48 hours. The percentage of NBT reduction in NB4/WTA cells was lower than that in control groups. The difference in NBT reduction rate between NB4/WTA and control cells was gradually increased after treated with ATRA for three days. The expression levels of PML/RARalpha, p21 and c-myc genes in NB4/WTA cells were notably increased.

Overexpression of exogenous WTA gene could partially inhibit the differentiation of NB4 cells by up-regulating the expression of PML/RARalpha, p21 and c-myc genes.