The Role of Somatic Mutations in Acute Myeloid Leukemia Pathogenesis

Exploring the interplay between microRNA expression and DNA mutation analysis in AML patients

MicroRNAs (miRNAs) are key regulators in Acute Myeloid Leukemia AML, affecting gene expression, including that of CD markers and impacting mutations within leukemic cells. Mutations in AML can alter miRNA profiles, which can affect the expression of CD markers and contribute to disease progression by influencing cellular processes such as differentiation, proliferation, and apoptosis. Here, we examined the interplay of cell surface protein expression (CD markers), DNA mutations, and microRNA expression in AML patients. We included 32 recently diagnosed AML patients, and CD marker expression was evaluated using flow cytometry and molecular techniques. This study aims to delve into this relationship within the context of AML, elucidating its potential implications for diagnosis, prognosis, and therapeutic interventions. Mutations were scrutinized in six patients using Whole-Exome Sequencing (WES), while quantitative PCR (qPCR) was employed to investigate the expression levels of nine microRNAs. Subsequently, a comprehensive interaction network was constructed using Cytoscape software, focusing on genes with significant mutations and their corresponding microRNAs. Cell surface protein expression analysis revealed upregulation of CD45, CD99, CD34, HLA-DR, CD38, CD13, CD33, MPO, CD15 and CD117 in AML patients. The molecular analysis results unveiled mutations in specific genes (FLT3, KIT, PTPN11, BCR, DNMT3A, and NRAS) targeted by nine microRNAs. Notably, eight microRNAs exhibited heightened expression levels. Network analysis highlighted interactions between the PTPN11 gene and six scrutinized microRNAs. Understanding the regulatory dynamics between gene mutations and microRNAs in AML patients is pivotal for unraveling the disease's molecular mechanisms and identifying potential therapeutic targets. Further exploration into the functional roles of microRNAs in gene regulation and AML pathogenesis is warranted to validate their potential as therapeutic targets, diagnostic markers, and advanced treatment strategies.

Pharmacological p38 MAPK inhibitor SB203580 enhances AML stem cell line KG1a chemosensitivity to daunorubicin by promoting late apoptosis, cell growth arrest in S-phase, and miR-328-3p upregulation

Acute myeloid leukaemia (AML) is characterized by uncontrolled proliferation of myeloid progenitor cells and impaired maturation, leading to immature cell accumulation in the bone marrow and bloodstream, resulting in hematopoietic dysfunction. Chemoresistance, hyperactivity of survival pathways, and miRNA alteration are major factors contributing to treatment failure and poor outcomes in AML patients. This study aimed to investigate the impact of the pharmacological p38 mitogen-activated protein kinase (MAPK) inhibitor SB203580 on the chemoresistance potential of AML stem cell line KG1a to the therapeutic drug daunorubicin (DNR). KG1a and chemosensitive leukemic HL60 cells were treated with increasing concentrations of DNR. Cell Titer-Glo®, flow cytometry, phosphokinase and protein arrays, Western blot technology, and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) were employed for assessment of cell viability, half-maximal inhibitory concentration (IC50) determination, apoptotic status detection, cell cycle analysis, apoptosis-related protein and gene expression monitoring. Confocal microscopy was used to visualize caspase and mitochondrial permeability transition pore (mPTP) activities. Exposed at various incubation times, higher DNR IC50 values were determined for KG1a cells than for HL60 cells, confirming KG1a cell chemoresistance potential. Exposed to DNR, late apoptosis induction in KG1a cells was enhanced after SB203580 pretreatment, defined as the combination treatment. This enhancement was confirmed by increased cleavage of poly(ADP-ribose) polymerase, caspase-9, caspase-3, and augmented caspase-3/-7 and mPTP activities in KG1a cells upon combination treatment, compared to DNR. Using phosphokinase and apoptosis protein arrays, the combination treatment decreased survival Akt phosphorylation and anti-apoptotic Bcl-2 expression levels in KG1a cells while increasing the expression levels of the tumor suppressor p53 and cyclin-dependent kinase inhibitor p21, compared to DNR. Cell cycle analysis revealed KG1a cell growth arrest in G2/M-phase caused by DNR, while combined treatment led to cell growth arrest in S-phase, mainly associated with cyclin B1 expression levels. Remarkably, the enhanced KG1a cell sensitivity to DNR after SB203580 pretreatment was associated with an increased upregulation of miR-328-3p and slight downregulation of miR-26b-5p, compared to DNR effect. Altogether, these findings could contribute to the development of a new therapeutic strategy by targeting the p38 MAPK pathway to improve treatment outcomes in patients with refractory or relapsed AML.

Current knowledge about FLT3 gene mutations, exploring the isoforms, and protein importance in AML

Acute myeloid leukaemia (AML) is a complex haematological malignancy characterised by diverse genetic alterations leading to abnormal proliferation of myeloid precursor cells. One of the most significant genetic alterations in AML involves mutations in the FLT3 gene, which plays a critical role in haematopoiesis and haematopoietic homeostasis. This review explores the current understanding of FLT3 gene mutations and isoforms and the importance of the FLT3 protein in AML. FLT3 mutations, including internal tandem duplications (FLT3-ITD) and point mutations in the tyrosine kinase domain (FLT3-TKD), occur in 25-30% in AML and are associated with poor prognosis. FLT3-ITD mutations lead to constitutive activation of the FLT3 signalling pathway, promoting cell survival and proliferation. FLT3-TKD mutations affect the tyrosine kinase domain and affect AML prognosis in various ways. Furthermore, FLT3 isoforms, including shorter variants, contribute to the complexity of FLT3 biology. Additionally, nonpathological polymorphisms in FLT3 are being explored for their potential impact on AML prognosis and treatment response. This review also discusses the development of molecular treatments targeting FLT3, including first-generation and next-generation tyrosine kinase inhibitors, highlighting the challenges of resistance that often arise during therapy. The final chapter describes FLT3 protein domain rearrangements and their relevance to AML pathogenesis.

Glucose Metabolism as a Potential Therapeutic Target in Cytarabine-Resistant Acute Myeloid Leukemia

Altered glycolytic metabolism has been associated with chemoresistance in acute myeloid leukemia (AML). However, there are still aspects that need clarification, as well as how to explore these metabolic alterations in therapy. In the present study, we aimed to elucidate the role of glucose metabolism in the acquired resistance of AML cells to cytarabine (Ara-C) and to explore it as a therapeutic target. Resistance was induced by stepwise exposure of AML cells to increasing concentrations of Ara-C. Ara-C-resistant cells were characterized for their growth capacity, genetic alterations, metabolic profile, and sensitivity to different metabolic inhibitors. Ara-C-resistant AML cell lines, KG-1 Ara-R, and MOLM13 Ara-R presented different metabolic profiles. KG-1 Ara-R cells exhibited a more pronounced glycolytic phenotype than parental cells, with a weaker acute response to 3-bromopyruvate (3-BP) but higher sensitivity after 48 h. KG-1 Ara-R cells also display increased respiration rates and are more sensitive to phenformin than parental cells. On the other hand, MOLM13 Ara-R cells display a glucose metabolism profile similar to parental cells, as well as sensitivity to glycolytic inhibitors. These results indicate that acquired resistance to Ara-C in AML may involve metabolic adaptations, which can be explored therapeutically in the AML patient setting who developed resistance to therapy.

Emerging small molecular inhibitors as targeted therapies for high-risk acute myeloid leukemias

INTRODUCTION

Acute myeloid leukemia (AML) is an aggressive disease which has traditionally been treated with intensive chemotherapy. Survival in patients with high-risk cytogenetic and molecular subsets has been poor with this approach due to suboptimal responses seen with intensive chemotherapy and due to many patients with higher risk disease being older and unable to tolerate intensive therapies. In recent years, several targeted therapies have been under investigation for patients with high-risk AML subsets.

AREAS COVERED

This review covers four different subsets of high-risk AML including TP53-mutated, KMT2A-rearranged, FLT3-mutated, and secondary AML developing after prior hypomethylating agent exposure. The research discussed in this review focuses on small molecule inhibitors that have been studied in the treatment of these high-risk AML subsets.

EXPERT OPINION

There are several small molecule inhibitors that have demonstrated promise in these high-risk AML subsets. Longer follow-up and ongoing investigation are needed to continue to optimize therapy for patients with high-risk AML.

Antibiotic and glucocorticoid-induced recapitulated hematological remission in acute myeloid leukemia: A case report and review of literature

BACKGROUND

Leukemic hematopoietic cells acquire enhanced self-renewal capacity and impaired differentiation. The emergence of symptomatic leukemia also requires the acquisition of a clonal proliferative advantage. Untreated leukemia patients usually experience an aggressive process. However, spontaneous remission occasionally occurs in patients with acute myeloid leukemia (AML), most frequently after recovery from a febrile episode, and this is generally attributed to the triggering of antineoplastic immunity. There may be another explanation for the spontaneous remission as implicated in this paper.

CASE SUMMARY

A 63-year-old Chinese man presented with high fever, abdominal pain and urticaria-like skin lesions. He was diagnosed with AML-M4 with t(8;21) (q22;q22)/RUNX1-RUNX1T1 based on morphological, immunological, cytogenetic and molecular analyses. He had a complex chromosome rea-rrangement of 48,XY,t(8;21)(q22;q22),+13,+13[9]/49,idem,+mar[9]/49,idem,+8[2]. He also had a mutated tyrosine kinase domain in fms-like tyrosine kinase 3 gene. He was treated with antibiotics and glucocorticoids for gastrointestinal infection and urticaria-like skin lesions. The infection and skin lesions were quickly resolved. Unexpectedly, he achieved hematological remission along with resolution of the febrile episode, gastrointestinal symptoms and skin lesions. Notably, after relapse, repeating these treatments resulted in a return to hematological remission. Unfortunately, he demonstrated strong resistance to antibiotic and glucocorticoid treatment after the second relapse and died of sepsis from bacterial infection with multidrug resistance. The main clinical feature of this patient was that symptomatic AML emerged with flaring of the gut inflammatory disorder and it subsided after resolution of the inflammation. Learning from the present case raises the possibility that in a subgroup of AML patients, the proliferative advantage of leukemia cells may critically require the presence of inflammatory stresses.

CONCLUSION

Inflammatory stresses, most likely arising from gastrointestinal infection, may sustain the growth and survival advantage of leukemic cells.

KMT2A: Umbrella Gene for Multiple Diseases

KMT2A (Lysine methyltransferase 2A) is a member of the epigenetic machinery, encoding a lysine methyltransferase responsible for the transcriptional activation through lysine 4 of histone 3 (H3K4) methylation. KMT2A has a crucial role in gene expression, thus it is associated to pathological conditions when found mutated. KMT2A germinal mutations are associated to Wiedemann–Steiner syndrome and also in patients with initial clinical diagnosis of several other chromatinopathies (i.e., Coffin–Siris syndromes, Kabuki syndrome, Cornelia De Lange syndrome, Rubinstein–Taybi syndrome), sharing an overlapping phenotype. On the other hand, KMT2A somatic mutations have been reported in several tumors, mainly blood malignancies. Due to its evolutionary conservation, the role of KMT2A in embryonic development, hematopoiesis and neurodevelopment has been explored in different animal models, and in recent decades, epigenetic treatments for disorders linked to KMT2A dysfunction have been extensively investigated. To note, pharmaceutical compounds acting on tumors characterized by KMT2A mutations have been formulated, and even nutritional interventions for chromatinopathies have become the object of study due to the role of microbiota in epigenetic regulation.

Diagnostic Workup of Acute Myeloid Leukemia: What Is Really Necessary? An Italian Survey

Acute myeloid leukemia (AML) is a heterogeneous disease with a wide variety of clinical presentations, morphological features, and immunophenotypes. The diagnostic approaches to AML that are adopted in Italy have been explored using an online Delphi-based process to expand the global discussion on mandatory tests for the correct diagnosis and, consequently, for optimal management of AML in clinical practice. The final results of the panel of Italian hematologists involved in this work highlight the importance of genetic evaluation for classification and risk stratification and firmly establish that karyotyping, fluorescence in situ hybridization in cases with non-evaluable karyotype, and molecular tests must be performed in every case of AML, regardless of age. Obtaining clinically relevant genetic data at diagnosis is the basis for the success of patient-tailored therapy. The Italian specialists also confirm the role of multidisciplinary diagnostics for AML, now mandatory and expected to become more important in the future context of “precision” medicine.

Clinical implication and prognostic significance of FLT3-ITD and ASXL1 mutations in Egyptian AML patients: A single-center study

BACKGROUND

Both Fms-like tyrosine kinase 3-internal tandem duplication (FLT3-ITD) and Additional Sex Comb-like 1 (ASXL1) mutations are frequent and early genetic alteration events in acute myeloid leukemia (AML) patients. These genetic alterations may be associated with an unfavorable prognosis.

OBJECTIVE

Up to our knowledge, this is the first study performed to evaluate the clinical implication and prognostic significance of FLT3-ITD and ASXL1 mutations and their coexistence on the outcome of Egyptian AML patients.

METHODS

Our study included 83 patients with AML who were subjected to immunophenotyping and detection of FLT3-ITD and ASXL1 gene mutation by polymerase chain reaction (PCR) and real-time PCR, respectively.

RESULTS

FLT3-ITD and ASXL1 mutations were detected in 20.5% and 18.1% of AML patients respectively. Seven patients (8.4%) had co-expression of both genes' mutations. FLT3-ITD mutation was significantly higher in younger age, higher WBCs count and poor cytogenetic risk patients (P= 0.01, < 0.001 and 0.008 respectively). ASXL1 mutation was significantly higher in intermediate cytogenetic risk patients (P= 0.2). The mean period of survival and relapse-free survival (RFS) were significantly reduced in FLT3-ITD and ASXL1 mutations compared with their non-mutant types (P= 0.01 and 0.03 respectively). Both mutations were independent risk factors for overall survival (OS) and (RFS) in univariate and multivariate analysis in AML patients.

CONCLUSION

FLT3-ITD and ASXL1 gene mutations or their coexistence can predict a poor prognosis in AML patients.