Real-time PCR quantification of major Wilms’ tumor gene 1 (WT1) isoforms in acute myeloid leukemia, their characteristic expression patterns and possible functional consequences

Abstract

Wilms' tumor gene 1 (WT1) functions including some contradictory effects may be explained by the presence and interactions of its isoforms, however, their evaluation has been so far complicated by several technical problems. We designed unique quantitative PCR systems for direct quantification of the majorand verified their sensitivity, specificity and reproducibility in extensive testing. With this method we evaluated WT1 total and isoform expression in 23 normal bone marrow (BM) samples, 73 childhood acute myeloid leukemia (AML), 20 childhood myelodysplastic syndrome (MDS), 9 childhood severe aplastic anemia (SAA), 30 adult AML and 29 adult MDS patients. WT1 isoform patterns showed differences among these samples and clustered them into groups representing the specific diagnoses (Po0.0001). Isoform profiles were independent of total WT1 expression and possess certain common features-overexpression of isoform D and

The prognostic effect of high diagnostic WT1 gene expression in pediatric AML depends on WT1 SNP rs16754 status: Report from the Children's Oncology Group

“…However, WT1 splice isoforms are functionally distinct, with exon‐5 containing (+E5) isoforms reported to predominate in AML . Isoform‐specific expression assays currently being developed will refine our ability to quantify leukemia‐associated WT1 transcripts and add an additional dimension to the study of WT1 expression, as the ratios of the expression of specific WT1 isoforms may have functional significance. Alternatively, total WT1 expression may merely reflect the maturational stage of the predominant leukemia progenitor cell within the blast population.…”

The Prognostic Effect of High WT1 Gene Expression in Pediatric AML Depends on WT1 SNP rs16754 Status: A Report From the Children's Oncology Group (COG)

“…However, WT1 splice isoforms are functionally distinct, with exon-5 containing (þE5) isoforms reported to predominate in AML [26]. Isoform-specific expression assays currently being developed [27] will refine our ability to quantify leukemiaassociated WT1 transcripts and add an additional dimension to the study of WT1 expression, as the ratios of the expression of specific WT1 isoforms may have functional significance. Alternatively, total WT1 expression may merely reflect the maturational stage of the predominant leukemia progenitor cell within the blast population.…”

DNA and RNA binding by the Wilms' tumour gene 1 (WT1) protein +KTS and −KTS isoforms—From initial observations to recent global genomic analyses

“…49 Normal bone marrow samples show a WT1 expression pattern resembling that found by Haber et al 9 in kidney samples, where the +17AA/+KTS isoform dominates, the −17AA/+KTS and the +17AA/− KTS isoforms are about equal, and the −17AA/−KTS isoform is expressed at the lowest levels. 50 In samples from both paediatric and adult AML patients, the +17AA/−KTS isoform ratio is slightly increased as compared to normal bone marrow, and in adult AML, this increase is associated with a higher risk of relapse. 50 The KTS splice ratio has been shown to be more stable across patient samples and across cell lines, than the 17AA splice ratio.…”

“…50 In samples from both paediatric and adult AML patients, the +17AA/−KTS isoform ratio is slightly increased as compared to normal bone marrow, and in adult AML, this increase is associated with a higher risk of relapse. 50 The KTS splice ratio has been shown to be more stable across patient samples and across cell lines, than the 17AA splice ratio. Paediatric patient samples have a more variable, and in median values higher, KTS insertion rate than adult patients.…”