Evaluation of FOXP1 gene expression in pediatric B-cell precursor acute lymphoblastic leukemia patients at remission induction therapy

Transcription factors (TFs) play a key role in the development, therapy, and relapse of B-cell malignancies, such as B-cell precursor acute lymphoblastic leukemia (BCP-ALL). Given the essential function of Forkhead box protein P1 (FOXP1) transcription factor in the early development of B-cells, this study was designed to evaluate FOXP1 gene expression levels in pediatric BCP-ALL patients and NALM6 cell-line.

This case-control study was done on the NALM6 cell-line and bone marrow specimens of 23 pediatric BCP-ALL patients (median age: 7.5 years; range: 2.0 – 15.0 years) at different clinical stages including new diagnosis, 15th day after the treatment, and relapse. Also, 10 healthy children were included as the control group. FOXP1 gene expression was analyzed by quantitative real-time polymerase chain reaction (qRT-PCR). The correlation analysis was performed between the FOXP1 gene expression and patients’ demographic and laboratory characteristics.

The results showed that FOXP1 gene expression was significantly downregulated in the NALM-6 cell-line (median=0.05, P<0.001) and patients at new diagnosis (median=0.06, p<0.0001), and relapse (median=0.001, p<0.0001) phases, compared to the control group (median=0.08). FOXP1 gene expression on the 15th day of the treatment was significantly higher than its level at the new diagnosis stage (p<0.001). Moreover, FOXP1 gene was significantly downregulated in the relapse phase compared to the new diagnosis. Patients whose number of bone marrow blasts on the 15th day of the treatment was below 5% had higher FOXP1 gene expression at the diagnosis phase (Spearman’s correlation, P<0.05, r=-0.485) and higher ratio of diagnosis/day 15 (p<0.001, Mann-Whitney U test).

FOXP1 levels could be a potential biomarker of therapy response in remission induction therapy for pediatric BCP-ALL patients.