Wilms tumor 1 gene expression has been recognized as a potential diagnostic and prognostic marker in AML. Its high expression levels are observed in a significant proportion of AML patients, regardless of treatment response. This makes it a useful tool for disease monitoring and assessing treatment outcomes. The expression level of WT1 in acute myeloid leukemia (AML) can be complex and varies among different patients. WT1 is a transcription factor that plays a role in regulating gene expression and is normally expressed during embryonic development but is generally absent or expressed at very low levels in most adult tissues. However, in AML, WT1 is often found to be highly expressed (Rautenberg et al. 2018).
The WT1 gene is involved in several cellular and biological mechanisms, like differentiation, cell apoptosis, and proliferation. Consequently, it is theoretically predictable that higher WT1 gene expression is detected in malignant conditions, so the overexpression of WT1 is reported in numerous tumors such as ovarian cancer, pediatric tumors, mesothelioma, and hematopoietic cancers like AML (Nejatifar et al., 2022).
In this study, with a total of 29 patients at diagnosis and 10 healthy controls, there are no significant differences between age and gender in AML patients with control groups (33.7±15.9; 34.4±8.5) and (p 0.7; 0.9), respectively. While the Fab classification showed the majority of subtypes were AML-M3 (28.6%),.
According to certain research, the WT1 mutation was inversely connected to the (M0) subtype but closely associated with younger age, the FAB M6 subtype, and t (7; 11) (p15; 15) (Hou et al. 2010).
As demonstrated by the cycle threshold (Ct) data of the patients available for this study, we can distinguish between normal and abnormal expression levels of the WT1 gene using a precise quantitative amount of WT1 transcript provided by RQ-PCR methods. We also observed a significant variation in WT1 levels in patients diagnosed with de novo AML compared to and after induction. The mean Ct value of the WT1 transcript shows significant differences between NR (22.6±3.2) and CR (25.6±3.5) AML patients before treatment (p = 0.03) compared to after induction treatment. As well, the AML patients had a considerably greater fold change in WT 1 gene expression compared to control cases.
The role of WT1 expression in clinical outcomes
The most important outcome for treatment is complete remission [CR], which is well-defined as normocellular bone marrow with <5% blasts, a neutrophil sum total of (1×109/l), and the normal platelet (100×109/l), morphology of other components (Lyu et al. 2014; Nejatifar et al. 2022).
Some authors claim that using a peripheral blood sample may result in higher sensitivity given that WT1-expressing hemopoietic progenitor cells can be detected in the bone marrow, resulting in the normal level of detectable WT1 expression being about 1 log lower in peripheral blood than in leukemia-free samples (Ujj et al. 2016).
In the current study, out of 29 de novo AML patients, 16 (55.17%) were non-response (NR) and 13 (44.83%) were in complete remission (CR), which showed that the high mean rank of WT1 mRNA expression significantly occurred in NR (27.3) and CR (22.15) compared to control (5.5) (p value 0.0001). Most of the researchers who investigated the expression of the WT1 gene in leukemia noticed that it was overexpressed in a high percentage of the patients, which closed at 80% and more. (Deng et al., 2021; Lazzarotto and Candoni, 2022; Bergmann et al., 1997; Rautenberg et al., 2018; Ujj et al., 2016; Donia et al., 2022; Rampal and Figueroa, 2016; Steger et al., 2020; Niktoreh et al., 2023; Qi et al., 2015).
The reflection that disappointment to decrease high levels of the WT1 transcript subsequently therapy was related to a higher rate of relapse in the AML incited determinations to use WT1 as a biomarker of (MRD) minimal residual disease in AML (Rampal and Figueroa 2016). In some cases, WT1 expression levels may remain high after treatment, even in patients who achieve a complete response. This could be due to residual leukemic cells or subclones that are not completely eradicated by the treatment. These remaining cells may continue to express WT1, leading to its persistence at high levels post-treatment. There are a few reasons for this observation: AML is considered a heterogeneous disease; it differs significantly from patient to patient in terms of its molecular features and response to treatment. Numerous factors, including many genetic alterations and molecular subtypes of AML, can affect WT1 expression. As a result, the high expression of WT1 may not be the only factor in the treatment response but rather may be linked to other genetic or molecular features of the disease. According to Yoon et al. (2013), WT1 expression in AML patients has been linked to a worse disease-free survival rate and a higher relapse rate. There is no statistically significant difference in the prevalence of WT1 gene mutations between patients with early death, relapse, and constant complete remission (CR) (Nejatifar et al., 2022; Lyu et al., 2014). With the solid cancer in the patients, WT1 positive expression was significantly correlated with worse OS and DFS/RFS/PFS, while it was correlated but not significantly with poor DSS. 14 datasets demonstrated a strong correlation between the worst OS and WT1 positive expression (Qi et al., 2015; Chen et al., 2021).
One of the important reasons why making a correct diagnosis of WT may be challenging for pathologists is the presence of several subtypes of WT (morphological heterogeneity), as well as the fact that leukemia is a collection of heterogeneous hematopoietic stem cell malignancies (Nejatifar et al., 2022). In addition, the main mutations associated with WT1 are heterozygous events in the exons (7) and (9) that regularly lead to non-sense-mediated mRNA decline or, if every protein is manufactured, where they participate in a potential role in leukemogenesis by the pro-proliferation effect (Niktoreh et al., 2023; Chen et al., 2021). As a consequence of that, for the AML prognostic stratifications, a significant biomarker is still needed (Nejatifar et al., 2022; Zhao et al., 2021). In addition to these reasons, WT1 genes have multiple downstream effectors. An example of a predictive biomarker for various cancers is the heparin-binding growth factor midkine (MK) gene. Further recognized downstream effectors include the insulin-like growth factor I receptor (IGF-I-R) (Lyu et al. 2014).
Also, the accumulating evidence implicates changes in iron metabolism as crucial features of leukemia (Marjanovic et al. 2017). Another factor that can make it difficult for pathologists to make the right diagnosis of WT is that isoform patterns (four major WT1 isoforms) (Niktoreh et al., 2023) appeared different among the samples. Isoform profiles were independent of WT1 expression in total and possessed particular common features—overexpression of isoform D and EX5 (+) variants (Kramarzova et al. 2012). It is well known that acute leukemia patients with WT1 mutations express high levels of the wild-type WT1 protein. Therefore, it is tempting to hypothesize that leukemogenesis is solely influenced by the expression of the wild-type allele (Niktoreh et al., 2023)
The crucial role of WT1 in the pathogenesis of AML is accepted by many. Although certain molecular reasons behind the disease are still unknown, one plausible concept is that WT1 suppresses the expression of interferon regulatory factor 8 [IRF8], a key tumor suppressor in the development of myeloid leukemia.An unfamiliar observation noticed that a positive WT1 expression return negative was accepted in 11 of the 25 cases in which complete remission was attained.
In one case, the lower WT1 expression increased once again before a relapse. Six weeks before the relapse, they found high positivity (53.9) and ten weeks for marginal positivity (0.149). These results lead to the conclusion that there are changes in WT1-Positivity over time (Ujj et al. 2016). Also, several individuals who completed BM testing and were considered to have attained CR remained WT1-positive after induction. WT1 expression on CD34-positive blast cells has been observed, which could indicate that WT1 monitoring is more sensitive than BM morphological analysis. This concept was approved by Candoni et al. when he noticed that 24% of his AML patients in CR continued with WT1 positivity (Donia et al., 2022).