Wilms Tumor-1 (WT1) rs16754 Polymorphism and Clinical Outcome in Acute Myeloid Leukemia

Wilms' tumor gene 1 in hematological malignancies: friend or foe?

Wilms' tumor gene 1 (WT1) is a transcription and post-translational factor that has a crucial role in the biological and pathological processes of several human malignancies. For hematological malignancies, WT1 overexpression or mutation has been found in leukemia and myelodysplastic syndrome. About 70-90% of acute myeloid leukemia patients showed WT1 overexpression, and 6-15% of patients carried WT1 mutations. WT1 has been widely regarded as a marker for monitoring minimal residual disease in acute myeloid leukemia. Many researchers were interested in developing WT1 targeting therapy. In this review, we summarized biological and pathological functions, correlation with other genes and clinical features, prognosis value and targeting therapy of WT1 in hematological features.

The prognostic impact of Wilms tumor-1 polymorphism (rs16754) and human myeloid inhibitory C-type lectin-like receptor expression in cytogenetically normal-acute myeloid leukemia

Background

There are several genetic mutations that carry prognostic and predictive values in acute myeloid leukemia (AML). They are also implicated in disease pathogenesis and patient outcome. They can be a target of novel therapies for AML. The aim of the current study was to investigate prognostic value of Wilms’ tumor-1 (WT1) genotypes and human myeloid inhibitory C-type lectin-like (hMICL) receptor expression in normal-cytogenetic group of patients with AML. Genotyping of WT1 mutations was done by Rotor Gene real-time polymerase chain reaction (PCR) while hMICL expression was detected using phycoerythrin (PE)-conjugated mouse monoclonal anti-human (MoAbs) by flow cytometry.

Results

Sixty-three patients with cytogenetically normal AML (CN-AML) were included in the study. The alternate allele of WT1 single nucleotide polymorphism (SNP) rs16754 was found in 26.89%. At day 28 of therapy, complete remission was achieved in 100% of cases harboring mutant AG plus GG genotypes but only in 6.38% of cases harboring wild genotype (AA). After 6 months, 88.23% of patients harboring WT1 mutant genotype maintained complete remission, while only 23.40% of patients with wild type showed complete remission. The overall survival in patients harboring mutant WT1 genotypes was significantly longer than in those who carried the wild type gene (P-value, 0.001). Additionally, hMICL was overexpressed in approximately 87.3% of AML cases and inversely related to complete response. Similarly, overall survival was significantly shorter in patients with positive hMICL (P-value, 0.001).

Conclusion

Mutant WT1 genotypes (SNP rs16754) were conversely, associated with complete response, and hMICL overexpression had poor prognostic value in AML.

Hotspots mutational analysis of Wilms tumor 1 gene in acute myeloid leukaemia; prevalence and clinical correlation in North Indian population

BACKGROUND

The pathogenic role of Wilms tumor 1 gene (WT1) is well known in renal cancer. However, recently, its over expression is been documented in cases of acute myeloid leukaemia (AML), acute lymphoblastic leukaemia (ALL) and myelodysplastic syndrome (MDS). WT1 mutations is found in about 6%-15% of cases of AML affecting mainly hotspot exon 7 and 9, and less frequently in other exon such as 1, 2, 3, and 8. Different studies have shown equivocal findings with few of them depicting poorer prognosis, while others suggesting lack of any significant clinical impact.

OBJECTIVE

This study was planned to evaluate prevalence of WT1 gene mutation on exon 7 & 9 in de novo cases of AML and its correlation with their clinical features and disease course.

METHODOLOGY

A total of newly diagnosed and treatment naive 100 cases of AML, having blast count of ≥20% in peripheral blood or bone marrow were enrolled. Genomic DNA of all participants was extracted from blood/bone marrow sample using Qiagen^® DNA extraction kit. Haematological workup for counts and flow cytometry based immunophenotypes was done. Mutation on exon 7 & 9 were detected with the help of Sanger sequencing.

RESULTS

WT1 mutations were detected in both types of cases having normal vs. abnormal cytogenetics. The overall prevalence of WT1 mutation of 2% was found. We have reported one novel mutation on exon 9 of WT1 gene. Twelve cases (12%) among all analyzed AMLs were found to have synonymous single nucleotide polymorphism (SNPs) on exon 7 which has been previously reported in SNP database (rs16754).

CONCLUSION

In our study, presence of synonymous SNP was not associated with any change at protein level. We also evaluated mutational status with deaths during induction remission and concluded that presence of WT1 gene mutation was associated with death during induction therapy.