Expression of the transcription factor PAX5 in childhood acute leukemic cells

To investigate transcription factor PAX5 expression characteristics in childhood acute leukemic cells, expression levels of PAX5 and CD19 mRNA in 6 hematological tumor cell lines and bone marrow cells of 6 normal children, 58 de novo patients and 4 relapse acute leukemic children, including 39 cases of B-ALL, 10 cases of T-ALL and 13 cases of AML, were detected by a real-time RT-PCR. The results showed that PAX5 and CD19 mRNA expression levels were 2.35% and 2.52% in Namalwa (B-cell lines) respectively, but almost not detectable in other T- and myeloid cell lines. Among clinical samples, expression of PAX5 mRNA in B-ALL was significantly higher than that in T-ALL and AML (P = 0.029 and P = 0.013 respectively). PAX5 expression was significantly lower in T-ALL and AML than that in normal controls. The difference of PAX5 mRNA expression levels between T-ALL and AML was not significant. Individual difference of PAX5 mRNA expression levels in children with B-ALL was great. Moreover, PAX5 mRNA expressions in de novo and relapse patients with B-ALL were significantly higher than those in remission (P = 0.011 and P = 0.006 respectively). As binding sites for B-cell specific activator protein have been identified in the promoter regions of CD19, the study found that in B-ALL, there was clear correlation between the expression levels of PAX5 and CD19, which was also studied by real-time RT-PCR. It is concluded that PAX5 transcripts are readily detectable and quantifiable in clinical materials with B-ALL by real-time RT-PCR. The strong PAX5 mRNA expression in some B-ALL can be considered to be particularly interesting for further analysis.