Analysis of WT1 mutations, expression levels and single nucleotide polymorphism rs16754 inde novonon-M3 acute myeloid leukemia

Frequency and clinical impact of WT1 mutations in the context of CEBPA-mutated acute myeloid leukemia

INTRODUCTION

Several studies have confirmed that mutations in the Wilms tumor 1 (WT1) gene occur in adult acute myeloid leukemia (AML). However, few data are available regarding the incidence of WT1 mutations in CEBPA^mut AML and their impact.

METHODS

We retrospectively analyzed the frequency and clinical impact of WT1 mutations in 220 newly diagnosed AML patients with CEBPA mutations(CEBPA^mut). Chromosome karyotype analysis was performed by R or G banding method and further confirmed either by fluorescence in situ hybridization (FISH) and/or by multiple reverse transcription polymerase chain reaction (multiple RT-PCR). Mutations were detected with a panel of 112mutational genes using next-generation sequencing (NGS).

RESULTS

Overall, 30 WT1 mutations were detected in 29 of the 220 CEBPA^mut AML patients (13.18%) screened. These mutations clustered overwhelmingly in exon 7 (n=16). WT1 mutations were found to be significantly more frequent in AML patients with double-mutated CEBPA (CEBPA^dm) than in AML patients with single-mutated CEBPA (17.36%vs. 8.08%, P = 0.043). Among WT1-mutated patients, the most common co-mutation was FLT3-ITD (n = 7, 24.14%), followed by NRAS (n = 5, 17.24%), CSF3R (n = 4, 13.79%), GATA2 (n = 4, 13.79%), and KIT (n = 4, 13.79%). The most frequent functional pathway was signaling pathways inas many as 62.07% of cases. Notably,the concomitant mutations in epigenetic regulatorswere inversely correlated with WT1 mutations(P = 0.003). CEBPA^dm AML patients with WT1 mutations had inferior relapse-free survival, event-free survival and overall survival compared with patients CEBPA^dm AML without WT1 mutations (P = 0.002, 0.004, and 0.010, respectively).

CONCLUSION

Our data showed that WT1 mutations are frequently identified in CEBPA^mut AML, especially in CEBPA^dm AML. CEBPA^mut AML patients with WT1 mutations show distinct spectrum of comutations. In the context of CEBPA^dm AML, WT1 mutations predict a poor prognosis.

WT1 Gene Mutations, rs16754 Variant, and WT1 Overexpression as Prognostic Factors in Acute Myeloid Leukemia Patients

(1) Background: The aim of our study was the complex assessment of WT1 variants and their expression in relation to chromosomal changes and molecular prognostic markers in acute myeloid leukemia (AML). It is the first multidimensional study in Polish AML patients; (2) Methods: Bone marrow aspirates of 90 AML patients were used for cell cultures (banding techniques and fluorescence in situ hybridization), and to isolate DNA (WT1 genotyping, array comparative genomic hybridization), and RNA (WT1 expression). Peripheral blood samples from 100 healthy blood donors were used to analyze WT1 rs16754; (3) Results: Allele frequency and distribution of WT1 variant rs16754 (A;G) did not differ significantly among AML patients and controls. Higher expression of WT1 gene was observed in AA genotype (of rs16754) in comparison with GA or GG genotypes—10,556.7 vs. 25,836.5 copies (p = 0.01), respectively. WT1 mutations were more frequent in AML patients under 65 years of age (p < 0.0001) and affected relapse-free survival (RFS). The presence of NPM1 or CEBPA mutations decreased the risk of WT1 mutation presence, odds ratio (OR) = 0.11, 95% CI 0.02−0.46, p = 0.002 or OR = 0.05, 95% CI 0.006−0.46, p = 0.002, respectively. We observed significantly higher WT1 expression in AML CD34+ vs. CD34−, −20,985 vs. 8304 (p = 0.039), respectively. The difference in WT1 expression between patients with normal and abnormal karyotype was statistically insignificant; (4) Conclusions: WT1 gene expression and its rs16754 variant at diagnosis did not affect AML outcome. WT1 mutation may affect RFS in AML.

Association between the Wilms tumor-1 rs16754 polymorphism and acute myeloid leukemia: A MOOSE-compliant meta-analysis

The Wilms tumor-1 (WT1) protein is an important regulator of malignant hematopoiesis and has been implicated in the pathogenesis of acute myeloid leukemia (AML). Recently special attention has been paid to the relationship of the WT1 single nucleotide polymorphism (SNP) rs16754 with AML risk and outcome, but the conflicting results made it difficult to draw definitive conclusions. In the present study, we systematically reviewed the literature and performed a meta-analysis of existing evidence. We searched Embase, Pubmed, Web of Science, Medline, Cochrane Library, Wanfang, and China National Knowledge Infrastructure databases using predefined search methodology for relevant studies. We pooled odd ratio (OR) with 95% confidence intervals (95% CI) to evaluate the association between SNP rs16754 and AML risk. In addition, we analyzed hazard ratio (HR) with 95% CI for overall survive, relapse-free survival, and disease-free survival. Q-statistic was used to assess the homogeneity and Egger test was used to evaluate publication bias. Eleven studies met the inclusion criteria for analysis. The results of fixed-effect meta-analyses revealed no association between SNP rs16754 and AML risk (AA + GA vs GG: OR = 0.92, 95% CI: 0.71-1.19, P = .518; AA vs GA + GG: OR = 1.23, 95% CI: 0.86-1.76, P = .262; AA vs GG: OR = 1.05, 95% CI: 0.68-1.63, P = .820; AG vs AA: OR = 0.77, 95% CI: 0.53-1.13, P = .186; AG vs GG: OR = 0.89, 95% CI: 0.68-1.16, P = .376). In subgroup analysis by race, age, and disease type, we did not find any significant association. However, the presence of rs16754 GA/GG genotype was associated with improved overall survive (HR = 0.48, 95% CI: 0.26-0.91, P = .024) and relapse-free survival (HR = 0.82, 95% CI: 0.68-1.00, P = .048) compared with the rs16754 AA. In summary, the WT1 SNP rs16754 was not associated with AML risk, but it had a significant impact on clinical outcome in AML patients.

[Association of WT1 rs16754 polymorphism with clinical features and prognosis in patients with acute myeloid leukemia]

Objective: To explore the relationship between WT1 rs16754 polymorphism and clinical features and prognosis in patients with acute myeloid leukemia(AML). Methods: Bone marrow samples of 115 newly diagnosed AML patients and peripheral blood samples of 177 healthy controls were collected from the Second Hospital of Shanxi Medical University from January 2010 to December 2013. The genotype of rs16754 was screened by high- resolution melting(HRM)and validated by direct sequencing. The association between the single nucleotide polymorphism(SNP)and the risk, clinical features, remission and survival state of AML patients was analyzed retrospectively. Results: This polymorphism was not associated with risk for AML(P=0.296), the GA/AA group and GG group had no significant difference in gender, age, clinical features and remission rate of chemotherapy(P>0.05), the percentage of bone marrow cells in GA/AA group was higher than that in GG group(P=0.025). The survival state of 99 patients were followed up, single factor analysis found that the difference of the overall survival rate was statistically significant(P=0.035)between the two groups, the rate of GA/AA group was higher than that of the GG group. Multivariate analysis showed that the A allele was an independent prognostic factor for AML patients and the mortality risk of GA/AA patients were higher(HR=1.681, 95% CI 1.046- 2.700, P=0.032). Conclusion: WT1 rs16754 polymorphism is associated with the prognosis of AML, and can be used as one of the indicators for the prognosis of AML patients.

Prognostic significance of The Wilms' Tumor-1 (WT1) rs16754 polymorphism in acute myeloid leukemia

Acute myeloid leukemia is a genetically heterogeneous disease characterized by the accumulation of mutations in hematopoietic progenitor cells. For its heterogeneity, prognostic markers are very useful for therapeutic choice. The most important prognostic markers are age, white blood cell count, chromosomal alterations and gene mutations. Recent works have studied the prognostic significance of WT1 polymorphisms and mutations, highlighting the role of SNP rs16754 as a positive prognostic factor in AML patients. Nevertheless, the data are still unclear. To investigate the role of WT1 rs16754 polymorphism in AML, we designed a new tool for the detection using PNA directed PCR Clamping technology. Our data were able to establish a correlation between SNP rs16754 and the clinical outcome. Our results support the hypothesis that rs16754 polymorphism is an independent positive prognostic molecular marker that could be useful for therapeutic choice. In view of this, we described a novel assay faster, more sensitive and cheaper than DNA sequencing. The assay allows evaluating WT1 rs16754 polymorphism in diagnostic routine to improve prognostic information faster and without over-costing for diagnostic laboratories.

The Wilms Tumor-1 (WT1) rs16754 polymorphism is a prognostic factor in acute myeloid leukemia (AML): a meta-analysis

Although a number of studies suggested that WT1 rs16754 polymorphism might be related to decreased relapse free survival (RFS) and overall survival (OS). The results remain controversial. Published reports were searched in PubMed, EMBASE, and Google Scholar. Twelve publications with 3903 patients had met the inclusion criteria and were subjected to further examination. We found WT1 rs16754 polymorphism was significantly associated with OS in AML (OR = 0.62; 95% CI 0.52 − 0.75; p < 0.00001; I² = 47%). WT1 rs16754 polymorphism was also significantly associated with RFS in AML (OR = 0.69; 95% CI 0.57 − 0.83; p < 0.001; I² = 46%). In the subgroup analyses of age, race, and subtype of AML, WT1 rs16754 polymorphism was a independent favorable-risk marker. In conclusion, WT1 rs16754 polymorphism is associated with better survival of AML. It could be used as a cost-effective prognostic biomarker for AML.

WT1 protein is cleaved by caspase-3 in apoptotic leukemic cells

The aberrant overexpression of Wilms' tumor-1 gene (WT1) plays an important role in blast cell survival and resistance to chemotherapy in acute myeloid leukemia (AML). Here, we found in chemotherapeutic drug etoposide-induced apoptosis, WT1 protein was cleaved into smaller fragment by caspase-3 in leukemic cells. The cleavage was blocked by pan-caspase inhibitor and special caspase-3 inhibitor, suggesting that caspase-3 might cleave WT1 protein. Furthermore, recombinant active caspase-3 cleaved the Flag-WT1 and GST-WT1 proteins in vitro. However, site-directed mutagenesis analyses failed to identify caspase-3-targeted sites in WT1 protein, indicating that caspase-3 cleaved uncommon sites but not classical motifs (DXXD) and non-classical motifs (XXXD). Finally, Eto decreased c-Myc and Bcl-2 expression via reducing the binding of WT1 to the promoter and Eto-induced apoptosis was partially prevented by overexpression of WT1. Collectively, we identify a new substrate for caspase-3 and shed new light on understanding the complicated biology of WT1 in leukemia.

[Expression of WT1 gene in children with acute myeloid leukemia]

OBJECTIVE

To study WT1 gene expression in children with acute myeloid leukemia (AML) and its possible correlations to clinical outcomes.

METHODS

Bone marrow samples were collected from 45 children with AML (excluding acute promyelocytic leukemia, AML-M3) at different time points of AML treatment and follow-up. WT1 gene expression levels in bone marrow mononuclear cells were assayed by real-time fluorescence quantitative PCR. The correlation between WT1 expression and prognosis was retrospectively analyzed.

RESULTS

The WT1 expression level in AML children with bone marrow blast cell percentage of >60% was significantly higher than in those with bone marrow blast cell percentage of ≤ 60% (p<0.05). The lower WT1 expression level was documented in children with AML-M2 compared with in children with other non-M2 subtypes (p<0.05). WT1 expression level in patients in complete remission was significantly lower than that in patients at diagnosis or relapse (p<0.01). The 2-year disease-free survival (DFS) in patients with higher WT1 expression was significantly lower than in those with lower WT1 expression at the end of induction chemotherapy (p<0.05). The 2-year overall survival (OS) and DFS in patients with ≥1 log WT1 reduction range were significantly higher than those with <1 log reduction of WT1 expression level at the end of induction chemotherapy (p<0.05). WT1 expression levels tended to rise 2-3 months prior to bone marrow relapse.

CONCLUSIONS

WT1 expression level is closely correlated prognosis in children with AML. Dynamic monitoring of WT1 expression level is of great clinical importance in terms of individualized management, prognosis evaluation and relapse prediction.

The Wilms Tumor-1 (WT1) rs2234593 variant is a prognostic factor in normal karyotype acute myeloid leukemia

The single-nucleotide polymorphism (SNP) within Wilms tumor-1 (WT1) exon 7, rs16754, has been arguably reported to be implicated in acute myeloid leukemia (AML) prognosis. We assessed the potential association of selected WT1 SNPs as well as WT1 mutations in normal karyotype (NK)-AML and evaluated the prognostic value of these normal gene variants. Diagnostic samples from a series of 474 young adult NK-AML patients were used to genotype five WT1 SNPs using TaqMan assays and to directly sequence WT1 exons 7 and 9. Analysis of five WT1 gene variants showed an association of rs2234593 allele C with WT1 Ex7 mutation. Prognostic study of the same variants identified rs2234593 significantly associated with relapse and overall survival (OS). Patients with rs2234593AA/AC showed significantly higher 10-year OS (50 vs 36 %, hazard ratio (HR) = 0.69 (0.52–0.90), p = 0.006) and lower cumulative incidence of relapse (CIR) (36 vs 51 %, HR = 0.62 (0.45–0.86), p = 0.004) compared to those with rs2234593CC. The effect of AA genotype on CIR remained significant after adjustment for basic covariates including FLT3 internal-tandem duplication (FLT3-ITD) and nucleophosmin 1 (NPM1) mutations (HR = 0.60 (0.41–0.89), p = 0.009), with some evidence of improved survival (HR = 0.75 (0.55–1.03), p = 0.07). A multivariate analysis showed WT1 Ex7-mutant as the major relapse predictor, with a tendency for rs2234593-A effect after allowing for Ex7 mutation (p = 0.07). No adjusted risk benefit was found for previously reported rs16754-G. In conclusion, WT1 normal gene variant rs2234593 is associated with mutational status of WT1 Ex7 and is a further prognostic marker independent from FLT3-ITD and NPM1 mutations in NK-AML.

Wilms Tumor 1 rs16754 predicts favorable clinical outcomes for acute myeloid leukemia patients in South Chinese population

The single nucleotide polymorphism (SNP) rs16754 in WT1 shows a clinical implication in Caucasus population. However, the results were not reproducible in different population cohorts. We evaluated the clinical significance of rs16754 for 205 de novo acute myeloid leukemia (AML) patients in South Chinese population, 188 healthy volunteers were recruited as healthy controls. WT1 mRNA expression was investigated in 81 pretreatment bone marrow specimens. WT1(GA/AA) patients showed better overall survival (OS, P=0.006) and relapse-free survival (RFS, P=0.025) as compared with WT1(GG) patients, and the favorable clinical outcomes were most prominent in older patients with superior OS (P=0.001) and RFS (P=0.003). In multivariable analysis, rs16754 was still associated with favorable OS (HR=1.533, P=0.042). The WT1(GG) patients showed significantly higher WT1 mRNA expression than the WT1(GA/AA) patients (P=0.01). In summary, WT1 rs16754 may serve as an independent biomarker in AML patients from South Chinese.

Prognostic significance of diagnosed WT1 level in acute myeloid leukemia: a meta-analysis

The Wilms' tumor 1 (WT1) expression has been recognized in a substantial number of acute myeloid leukemia (AML) patients. Some studies indicated the association of diagnosed WT1 higher expression (WT1(H)) and poor outcome in the AML patients, while other studies had different opinions. Therefore, we performed a meta-analysis to evaluate the controversial prognostic significance of diagnosed WT1(H) in AML. Eligible studies were identified from several databases including PubMed, Embase, Web of Science, and the Cochrane Library (up to September 2014). The primary end point was overall survival (OS) and disease-free survival (DFS) was chosen as secondary end point. If possible, we would pool estimate effects (hazard ratio [HR] with 95 % confidence interval [CI]) of outcomes in both fixed and random effects models. Eleven studies, covering 1497 AML patients, were included in this meta-analysis. Pooled HRs indicated that diagnosed WT1(H) had a poor impact on the survival of AML patients (HR for OS, 1.37; HR for DFS, 1.38). Furthermore, diagnosed WT1(H) appeared to be an adverse prognostic indicator in adult AML (HR for OS, 1.43; HR for DFS, 1.41) and non-promyelocytic AML (non-M3 AML) (HR for OS, 1.46; HR for DFS, 1.41). Diagnosed WT1(H) had slightly but significantly poor prognostic impact on OS and DFS of patients with AML in total population and some specific subgroups.