WT1 loss attenuates the TP53-induced DNA damage response in T-cell acute lymphoblastic leukemia

Selective pressures of platinum compounds shape the evolution of therapy-related myeloid neoplasms

Therapy-related myeloid neoplasms (t-MN) arise as a complication of chemo- and/or radiotherapy. Although t-MN can occur both in adult and childhood cancer survivors, the mechanisms driving therapy-related leukemogenesis likely vary across different ages. Chemotherapy is thought to induce driver mutations in children, whereas in adults pre-existing mutant clones are selected by the exposure. However, selective pressures induced by chemotherapy early in life are less well studied. Here, we use single-cell whole genome sequencing and phylogenetic inference to show that the founding cell of t-MN in children starts expanding after cessation of platinum exposure. In patients with Li-Fraumeni syndrome, characterized by a germline TP53 mutation, we find that the t-MN already expands during treatment, suggesting that platinum-induced growth inhibition is TP53-dependent. Our results demonstrate that germline aberrations can interact with treatment exposures in inducing t-MN, which is important for the development of more targeted, patient-specific treatment regimens and follow-up.

Upregulation of HOXA3 by isoform-specific Wilms tumour 1 drives chemotherapy resistance in acute myeloid leukaemia

Upregulation of the Wilms' tumour 1 (WT1) gene is common in acute myeloid leukaemia (AML) and is associated with poor prognosis. WT1 generates 12 primary transcripts through different translation initiation sites and alternative splicing. The short WT1 transcripts express abundantly in primary leukaemia samples. We observed that overexpression of short WT1 transcripts lacking exon 5 with and without the KTS motif (sWT1+/- and sWT1-/-) led to reduced cell growth. However, only sWT1+/- overexpression resulted in decreased CD71 expression, G1 arrest, and cytarabine resistance. Primary AML patient cells with low CD71 expression exhibit resistance to cytarabine, suggesting that CD71 may serve as a potential biomarker for chemotherapy. RNAseq differential expressed gene analysis identified two transcription factors, HOXA3 and GATA2, that are specifically upregulated in sWT1+/- cells, whereas CDKN1A is upregulated in sWT1-/- cells. Overexpression of either HOXA3 or GATA2 reproduced the effects of sWT1+/-, including decreased cell growth, G1 arrest, reduced CD71 expression and cytarabine resistance. HOXA3 expression correlates with chemotherapy response and overall survival in NPM1 mutation-negative leukaemia specimens. Overexpression of HOXA3 leads to drug resistance against a broad spectrum of chemotherapeutic agents. Our results suggest that WT1 regulates cell proliferation and drug sensitivity in an isoform-specific manner.

Prognostic significance of Wilms' tumor gene 1 expression in children with B-cell precursor acute lymphoblastic leukemia

Introduction

The prognostic role of Wilms' tumor 1 (WT1) gene expression at diagnosis in children with B cell precursor acute lymphoblastic leukemia (BCP-ALL) is still controversial.

Methods

We detected the WT1 transcript levels of 533 de novo pediatric BCP-ALL patients using TaqMan-based real-time quantitative PCR and analyzed their clinical features.

Results

The WT1 transcript levels differed among the distinct molecularly defined groups, with the highest levels in the KMT2A rearrangements (KMT2A-r) group. According to the results of the X-tile software, all patients were divided into two groups: WT1/ABL ≥ 0.24% (group A) and <0.24% (group B). The proportions of patients whose age was ≥10 years old, with immunophenotype of Pro-B, belonging in high-risk group, or with minimal residual disease (MRD) ≥ 0.01% at week 12 were significantly higher in group A than in group B. In the B-other group, WT1 overexpression was an independent risk factor of overall survival (OS) rate (P = 0.042), and higher MRD ≥ 0.01% at week 12 was associated with lower OS rate (P<0.001) and event-free survival rate (P<0.001). Moreover, the subgroup analysis revealed that, in patients with initial WBC<50 × 109/L or MRD<0.1% at day 33 or MRD<0.01% at week 12 or in the standard-risk group, WT1 overexpression led to a poorer outcome in comparison with those with WT1 downexpression (P<0.05).

Discussion

Therefore, pediatric BCP-ALL with WT1 overexpression had unique clinico-pathological characteristics and poor treatment response. In B-other patients, WT1 overexpression at diagnosis predicted an inferior prognosis. The WT1 gene may serve as a biomarker for monitoring residual disease in the B-other population, especially in children in the standard-risk group.

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.

Effect of Down-Regulation of miR-23b-3p on the Differentiation of Acute Myeloid Leukemia via Wilms Cancer Gene 1

miRNA has always been a hot spot research. We assessed the effect of down-regulation of miR-23b-3p on the differentiation of acute myeloid leukemia (AML). Human AML cell line U937 was divided into blank group, NC group and miR-23b-3p low expression group (transfected with miR-23b-3p inhibitor) and miR-23b-3p followed by analysis of WT1 level and relationship between miR-23b-3p and WT1 by dual luciferase reporter assay. All-trans retinoic acid is used to induce differentiation, and then the morphological changes of cells and CD11b level were detected. When miR-23b-3p level was reduced, WT1 mRNA and protein level was also decreased. Dual luciferase assay showed that miR-23b-3p bound to WT1 3’-UTR. Inhibition of miR-23b-3p significantly decreased cell proliferation. Swiss Giemsa staining showed that most of cells were in the differentiation stage with low miR-23b-3p expression. The differentiation marker CD11b was significantly higher than other groups, indicating that low miR-23b-3p expression can promote cell differentiation and reduce cell proliferation to a certain extent. Under low miR-23b-3p expression, the positive rate of CD11b was significantly increased. Down-regulating miR-23b-3p can inhibit WT1 to a certain extent and promote the differentiation of AML, which provides a guidance for the gene-level treatment of AML.

Mutation accumulation in cancer genes relates to nonoptimal outcome in chronic myeloid leukemia

Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm accounting for ∼15% of all leukemia. Progress of the disease from an indolent chronic phase to the more aggressive accelerated phase or blast phase (BP) occurs in a minority of cases and is associated with an accumulation of somatic mutations. We performed genetic profiling of 85 samples and transcriptome profiling of 12 samples from 59 CML patients. We identified recurrent somatic mutations in ABL1 (37%), ASXL1 (26%), RUNX1 (16%), and BCOR (16%) in the BP and observed that mutation signatures in the BP resembled those of acute myeloid leukemia (AML). We found that mutation load differed between the indolent and aggressive phases and that nonoptimal responders had more nonsilent mutations than did optimal responders at the time of diagnosis, as well as in follow-up. Using RNA sequencing, we identified other than BCR-ABL1 cancer-associated hybrid genes in 6 of the 7 BP samples. Uncovered expression alterations were in turn associated with mechanisms and pathways that could be targeted in CML management and by which somatic alterations may emerge in CML. Last, we showed the value of genetic data in CML management in a personalized medicine setting.

Fatal hyperleukocytic T lymphoblastic lymphoma/leukemia complicated with multi-gene fusion and mutation: clinical revelation and perception

T lymphoblastic lymphoma/leukemia (T-LBL/ALL) is a highly malignant hematological tumor common in young males. Most T-LBL/ALL patients usually initially seek medical treatment for clinical manifestations of non-hematological diseases. Presently, T-ALL chemotherapy is often used for the treatment of T-LBL/ALL internationally. With the application of high-intensity standard chemotherapy, the efficacy and prognosis of T-LBL/ALL are still not optimistic. The authors present a young male patient with facial and neck edema as the initial symptoms. This young patient of T-LBL/ALL was found to have a mediastinal mass after CT examination and he was finally diagnosed as highly malignant T-LBL/ALL. Unfortunately, after undergoing three standard courses of high-intensity chemotherapy, the young male patient eventually died of white blood cell stasis and severe infection caused by hyperleukocytosis. To this end, we find that the prognosis of T-LBL/ALL with multiple gene mutations or fusions and hyperleukocytosis, is extremely poor, and probably becomes a medical problem worthy of continuing resolution in the field of hematology and oncology.

Mutational and functional genetics mapping of chemotherapy resistance mechanisms in relapsed acute lymphoblastic leukemia

Multi-agent combination chemotherapy can be curative in acute lymphoblastic leukemia (ALL). Still, patients with primary refractory disease or with relapsed leukemia have a very poor prognosis. Here we integrate an in-depth dissection of the mutational landscape across diagnostic and relapsed pediatric and adult ALL samples with genome-wide CRISPR screen analysis of gene-drug interactions across seven ALL chemotherapy drugs. By combining these analyses, we uncover diagnostic and relapse-specific mutational mechanisms as well as genetic drivers of chemoresistance. Functionally, our data identifies common and drug-specific pathways modulating chemotherapy response and underscores the effect of drug combinations in restricting the selection of resistance-driving genetic lesions. In addition, by identifying actionable targets for the reversal of chemotherapy resistance, these analyses open novel therapeutic opportunities for the treatment of relapse and refractory disease.

Novel Genetic Variations in Acute Myeloid Leukemia in Pakistani Population

Acute myeloid leukemia (AML) is a hematological malignancy characterized by clonal expansion of blast cells that exhibit great genetic heterogeneity. In this study, we describe the mutational landscape and its clinico-pathological significance in 26 myeloid neoplasm patients from a South Asian population (Pakistan) by using ultra-deep targeted next-generation DNA sequencing of 54 genes (∼5000×) and its subsequent bioinformatics analysis. The data analysis indicated novel non-silent somatic mutational events previously not reported in AML, including nine non-synonymous and one stop-gain mutations. Notably, two recurrent somatic non-synonymous mutations, i.e., STAG2 (causing p.L526F) and BCORL1 (p.A400V), were observed in three unrelated cases each. The BCOR was found to have three independent non-synonymous somatic mutations in three cases. Further, the SRSF2 with a protein truncating somatic mutation (p.Q88X) was observed for the first time in AML in this study. The prioritization of germline mutations with ClinVar, SIFT, Polyphen2, and Combined Annotation Dependent Depletion (CADD) highlighted 18 predicted deleterious/pathogenic mutations, including two recurrent deleterious mutations, i.e., a novel heterozygous non-synonymous SNV in GATA2 (p.T358P) and a frameshift insertion in NPM1 (p.L258fs), found in two unrelated cases each. The WT1 was observed with three independent potential detrimental germline mutations in three different cases. Collectively, non-silent somatic and/or germline mutations were observed in 23 (88.46%) of the cases (0.92 mutation per case). Furthermore, the pharmGKB database exploration showed a missense SNV rs1042522 in TP53, exhibiting decreased response to anti-cancer drugs, in 19 (73%) of the cases. This genomic profiling of AML provides deep insight into the disease pathophysiology. Identification of pharmacogenomics markers will help to adopt personalized approach for the management of AML patients in Pakistan.

The Genetics and Mechanisms of T-Cell Acute Lymphoblastic Leukemia

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematologic malignancy derived from early T-cell progenitors. The recognition of clinical, genetic, transcriptional, and biological heterogeneity in this disease has already translated into new prognostic biomarkers, improved leukemia animal models, and emerging targeted therapies. This work reviews our current understanding of the molecular mechanisms of T-ALL.

WITER: a powerful method for estimation of cancer-driver genes using a weighted iterative regression modelling background mutation counts

Genomic identification of driver mutations and genes in cancer cells are critical for precision medicine. Due to difficulty in modelling distribution of background mutation counts, existing statistical methods are often underpowered to discriminate cancer-driver genes from passenger genes. Here we propose a novel statistical approach, weighted iterative zero-truncated negative-binomial regression (WITER, http://grass.cgs.hku.hk/limx/witer or KGGSeq,http://grass.cgs.hku.hk/limx/kggseq/), to detect cancer-driver genes showing an excess of somatic mutations. By fitting the distribution of background mutation counts properly, this approach works well even in small or moderate samples. Compared to alternative methods, it detected more significant and cancer-consensus genes in most tested cancers. Applying this approach, we estimated 229 driver genes in 26 different types of cancers. In silico validation confirmed 78% of predicted genes as likely known drivers and many other genes as very likely new drivers for corresponding cancers. The technical advances of WITER enable the detection of driver genes in TCGA datasets as small as 30 subjects and rescue of more genes missed by alternative tools in moderate or small samples.