Usefulness of quantitative assessment of Wilms tumor suppressor gene expression in chronic myeloid leukemia patients undergoing imatinib therapy

Quantitative assessment of Wilms tumor 1 expression by real-time quantitative polymerase chain reaction in patients with acute myeloblastic leukemia

BACKGROUND

The Wilms tumor 1 (WT1) gene is originally defined as a tumor suppressor gene and a transcription factor that overexpressed in leukemic cells. It is highly expressed in more than 80% of acute myeloid leukemia (AML) patients, both in bone marrow (BM) and in peripheral blood (PB), and it is used as a powerful and independent marker of minimal residual disease (MRD); we have determined the expression levels of the WT1 by real-time quantitative polymerase chain reaction (RQ-PCR) in PB and BM in 126 newly diagnosed AML patients.

MATERIALS AND METHODS

This study was done in molecular pathology and cancer research center from April 2014 to June 2015, RQ-PCR method was used to determine the WT1 gene expression in BM and/or PB samples from 126 patients of AML, we cloned both WT1 and ABL genes for creating a standard curve, and we calculate copy number of WT1 genes in patients.

RESULTS

A total of 126 AML patients consist of 70 males (55.6%) and 56 females (44.4%), with a median age of 26 years; 104 (81%) patients out of 126 show overexpression of WT1 gene. We also concomitant monitoring of fusion transcripts (PML RARa, AML1-ETO, MLL-MLL, CBFb-MYH11, or DEK-CAN) in our patients, the AML1-ETO group showing remarkably low levels of WT1 compared with other fusion transcript and the CBFB-MYH11 showing high levels of WT1.

CONCLUSION

We conclude that WT1 expression by RQ-PCR in AML patients may be employed as an independent tool to detect MRD in the majority of normal karyotype AML patients.

Molecular monitoring of BAALC expression in patients with CD34-positive acute leukemia

Recent studies have shown that high BAALC expression predicts an adverse prognosis and may define an important risk factor in acute myeloid leukemia patients with normal karyotype. We performed, using real-time quantitative reverse transcriptase polymerase chain reaction (RQ-PCR), the molecular analysis of BAALC gene as a possible minimal residual disease (MRD) marker in 45 patients with newly diagnosed acute leukemia. BAALC transcript levels in 32 patients with CD34 expressed in leukemic blasts were 2-3 logs higher than background levels, and the copy number was reduced in patients achieving hematological remission. Comparative monitoring of MRD by RQ-PCR for the Wilms' tumor gene 1(WT1) or specific translocation markers demonstrated that BAALC had similar kinetics as WT1, AML1/ETO and minor BCR/ABL, but not PML/RARA. Quantitation of BAALC gene expression made it possible to assess MRD in patients with CD34-positive acute leukemia. To our knowledge, this is the first report concerning the use of BAALC mRNA expression for MRD monitoring.

WT1 transcript amount discriminates secondary or reactive eosinophilia from idiopathic hypereosinophilic syndrome or chronic eosinophilic leukemia

Idiopathic hypereosinophilic syndromes (HES) comprise a spectrum of indolent to aggressive diseases characterized by persistent hypereosinophilia. Hypereosinophilia can result from the presence of a defect in the hematopoietic stem cell giving rise to eosinophilia, it can be present in many myeloproliferative disorders or alternatively it may be a reactive form, secondary to many clinical conditions. The hybrid gene FIP1L1-PDGRFalpha was identified in a subset of patients presenting with HES or chronic eosinophilic leukemia (CEL). In spite of this, the majority of HES patients do not present detectable molecular lesions and for many of them the diagnosis is based on exclusion criteria and sometimes it remains doubt. In this study we explored the possibility to distinguish between HES/CEL and reactive hypereosinophilia based on WT1 transcript amount. For this purpose, 312 patients with hypereosinophilia were characterized at the molecular and cytogenetic level and analyzed for WT1 expression at diagnosis and during follow-up. This study clearly demonstrates that WT1 quantitative assessment allows to discriminate between HES/CEL and reactive eosinophilia and represents a useful tool for disease monitoring especially in the patients lacking a marker of clonality.

WT1 gene expression: an excellent tool for monitoring minimal residual disease in 70% of acute myeloid leukaemia patients - results from a single-centre study

Following induction chemotherapy for acute myeloid leukaemia (AML), sensitive determination of minimal residual disease (MRD) in patients achieving complete remission (CR) should enable the detection of early relapse and allow intervention at a more favourable stage than at overt relapse. We have determined the expression levels of the Wilms' tumour gene (WT1) by real-time quantitative polymerase chain reaction (RQ-PCR) in peripheral blood and bone marrow in 133 newly diagnosed AML patients and compared them with those in healthy volunteers. At diagnosis, the WT1 level exceeded normal expression in 118 of 133 (89%) patients, and was high enough to allow for detection of a WT1 decrease of least 1000-fold in 98 of 133 (74%) patients following induction therapy. Concomitant monitoring of fusion transcripts (PML-RARalpha, AML1-ETO, MLL-MLL, CBFbeta-MYH11, or DEK-CAN) in 38 patients identified different relationships between WT1 and fusion transcript levels, the AML1-ETO group showing remarkably low levels of WT1 compared with fusion transcript. In 32 patients analysed longitudinally there was close concordance between relapse and increased WT1 levels. Parallel longitudinal monitoring of WT1 and fusion transcript showed close correlation in 18 of 18 patients. We conclude that WT1 expression by RQ-PCR may be employed as a tool to detect MRD in the majority of fusion transcript-negative AML patients.