Role of microRNAs in Immune Regulation with Translational and Clinical Applications.

MicroRNAs (miRNAs) are 19-23 nucleotide long, evolutionarily conserved noncoding RNA molecules that regulate gene expression at the post-transcriptional level. In this review, involvement of miRNAs is summarized in the differentiation and function of immune cells, in anti-infective immune responses, immunodeficiencies and autoimmune diseases. Roles of miRNAs in anticancer immunity and in the transplantation of solid organs and hematopoietic stem cells are also discussed. Major focus is put on the translational clinical applications of miRNAs, including the establishment of noninvasive biomarkers for differential diagnosis and prediction of prognosis. Patient selection and response prediction to biological therapy is one of the most promising fields of application. Replacement or inhibition of miRNAs has enormous therapeutic potential, with constantly expanding possibilities. Although important challenges still await solutions, evaluation of miRNA fingerprints may contribute to an increasingly personalized management of immune dysregulation with a remarkable reduction in toxicity and treatment side effects. More detailed knowledge of the molecular effects of physical exercise and nutrition on the immune system may facilitate self-tailored lifestyle recommendations and advances in prevention.

Health related quality of life is associated with gastroesophageal reflux symptoms in overweight children.

OBJECTIVES: The association between obesity and gastroesophageal reflux disease (GERD) is well-established in adults; however, data in pediatric population is scarce. Our study aimed to assess the association between GERD and health-related quality of life (HRQoL) in overweight children. METHODS: From April to August of 2020, we included children aged 7-18 years who attended the Endocrinological Outpatient Clinic at the Paediatric Institute, University of Debrecen, Hungary. The participants completed two questionnaires: the Pediatric Gastroesophageal Reflux Disease Symptom Questionnaire (PGSQ) and the HRQoL questionnaire (PedsQL). Based on the criteria of the World Health Organization (WHO), the patients were categorized into two groups: an overweight or obese group and a group with normal weight. RESULTS: A total of 107 children (51 % female, mean age 13.2 years, 46 % overweight or obese) completed the questionnaires. The median PGSQ score was similar in both groups (4.0 (IQR: 1.0-7.8) vs. 3.0 (IQR: 1.0-7.0), p=0.6). However, the total PedsQL score was significantly lower in the children with overweight or obesity compared to those with normal weight (80.1 (71.1-91.0) vs. 88.0 (76.1-94.6), p=0.031). The PedsQL score was lower among overweight patients with GERD symptoms than that of normal-weight patients without GERD symptoms. CONCLUSIONS: Our findings highlight the importance of raising awareness about GERD to enhance the HRQoL and prevent long-term complications in obese children.

Next-Generation Sequencing-Based Genomic Profiling of Children with Acute Myeloid Leukemia.

Pediatric acute myeloid leukemia (AML) represents a major cause of childhood leukemic mortality, with only a limited number of studies investigating the molecular landscape of the disease. Here, we present an integrative analysis of cytogenetic and molecular profiles of 75 patients with pediatric AML from a multicentric, real-world patient cohort treated according to AML Berlin-Frankfurt-Münster protocols. Targeted next-generation sequencing of 54 genes revealed 17 genes that were recurrently mutated in >5% of patients. Considerable differences were observed in the mutational profiles compared with previous studies, as BCORL1, CUX1, KDM6A, PHF6, and STAG2 mutations were detected at a higher frequency than previously reported, whereas KIT, NRAS, and KRAS were less frequently mutated. Our study identified novel recurrent mutations at diagnosis in the BCORL1 gene in 9% of the patients. Tumor suppressor gene (PHF6, TP53, and WT1) mutations were found to be associated with induction failure and shorter event-free survival, suggesting important roles of these alterations in resistance to therapy and disease progression. Comparison of the mutational landscape at diagnosis and relapse revealed an enrichment of mutations in tumor suppressor genes (16.2% versus 44.4%) and transcription factors (35.1% versus 55.6%) at relapse. Our findings shed further light on the heterogeneity of pediatric AML and identify previously unappreciated alterations that may lead to improved molecular characterization and risk stratification of pediatric AML.

Implication of microRNAs in Carcinogenesis with Emphasis on Hematological Malignancies and Clinical Translation.

MicroRNAs (miRNAs) are evolutionarily conserved small non-coding RNAs, that are involved in the multistep process of carcinogenesis, contributing to all established hallmarks of cancer. In this review, implications of miRNAs in hematological malignancies and their clinical utilization fields are discussed. As components of the complex regulatory network of gene expression, influenced by the tissue microenvironment and epigenetic modifiers, miRNAs are "micromanagers" of all physiological processes including the regulation of hematopoiesis and metabolic pathways. Dysregulated miRNA expression levels contribute to both the initiation and progression of acute leukemias, the metabolic reprogramming of malignantly transformed hematopoietic precursors, and to the development of chemoresistance. Since they are highly stable and can be easily quantified in body fluids and tissue specimens, miRNAs are promising biomarkers for the early detection of hematological malignancies. Besides novel opportunities for differential diagnosis, miRNAs can contribute to advanced chemoresistance prediction and prognostic stratification of acute leukemias. Synthetic oligonucleotides and delivery vehicles aim the therapeutic modulation of miRNA expression levels. However, major challenges such as efficient delivery to specific locations, differences of miRNA expression patterns between pediatric and adult hematological malignancies, and potential side effects of miRNA-based therapies should be considered.

Evaluation of muscle-specific and metabolism regulating microRNAs in a chronic swimming rat model.

Making benefit from the epigenetic effects of environmental factors such as physical activity may result in a considerable improvement in the prevention of chronic civilization diseases. In our chronic swimming rat model, the expression levels of such microRNAs were characterized, that are involved in skeletal muscle differentiation, hypertrophy and fine-tuning of metabolism, which processes are influenced by chronic endurance training, contributing to the metabolic adaptation of skeletal muscle during physical activity. After chronic swimming, the level of miR-128a increased significantly in EDL muscles, which may influence metabolic adaptation and stress response as well. In SOL, the expression level of miR-15b and miR-451 decreased significantly after chronic swimming, which changes are opposite to their previously described increment in insulin resistant skeletal muscle. MiR-451 also targets PGC-1α mRNA, whiches expression level significantly increased in SOL muscles, resulting in enhanced biogenesis and oxidative capacity of mitochondria. In summary, the microRNA expression changes that were observed during our experiments suggest that chronic swim training contributes to a beneficial metabolic profile of skeletal muscle.

Targeted Epigenetic Interventions in Cancer with an Emphasis on Pediatric Malignancies.

Over the past two decades, novel hallmarks of cancer have been described, including the altered epigenetic landscape of malignant diseases. In addition to the methylation and hyd-roxymethylation of DNA, numerous novel forms of histone modifications and nucleosome remodeling have been discovered, giving rise to a wide variety of targeted therapeutic interventions. DNA hypomethylating drugs, histone deacetylase inhibitors and agents targeting histone methylation machinery are of distinguished clinical significance. The major focus of this review is placed on targeted epigenetic interventions in the most common pediatric malignancies, including acute leukemias, brain and kidney tumors, neuroblastoma and soft tissue sarcomas. Upcoming novel challenges include specificity and potential undesirable side effects. Different epigenetic patterns of pediatric and adult cancers should be noted. Biological significance of epigenetic alterations highly depends on the tissue microenvironment and widespread interactions. An individualized treatment approach requires detailed genetic, epigenetic and metabolomic evaluation of cancer. Advances in molecular technologies and clinical translation may contribute to the development of novel pediatric anticancer treatment strategies, aiming for improved survival and better patient quality of life.

MicroRNAs and Metabolism: Revisiting the Warburg Effect with Emphasis on Epigenetic Background and Clinical Applications.

Since the well-known hallmarks of cancer were described by Hanahan and Weinberg, fundamental advances of molecular genomic technologies resulted in the discovery of novel puzzle pieces in the multistep pathogenesis of cancer. MicroRNAs are involved in the altered epigenetic pattern and metabolic phenotype of malignantly transformed cells. They contribute to the initiation, progression and metastasis-formation of cancers, also interacting with oncogenes, tumor-suppressor genes and epigenetic modifiers. Metabolic reprogramming of cancer cells results from the dysregulation of a complex network, in which microRNAs are located at central hubs. MicroRNAs regulate the expression of several metabolic enzymes, including tumor-specific isoforms. Therefore, they have a direct impact on the levels of metabolites, also influencing epigenetic pattern due to the metabolite cofactors of chromatin modifiers. Targets of microRNAs include numerous epigenetic enzymes, such as sirtuins, which are key regulators of cellular metabolic homeostasis. A better understanding of reversible epigenetic and metabolic alterations opened up new horizons in the personalized treatment of cancer. MicroRNA expression levels can be utilized in differential diagnosis, prognosis stratification and prediction of chemoresistance. The therapeutic modulation of microRNA levels is an area of particular interest that provides a promising tool for restoring altered metabolism of cancer cells.

Recent Advances in the Management of Pediatric Acute Myeloid Leukemia-Report of the Hungarian Pediatric Oncology-Hematology Group.

Outcome measures of pediatric acute myeloid leukemia (AML) improved considerably between 1990 and 2011 in Hungary. Since 2012, efforts of the Hungarian Pediatric Oncology-Hematology Group (HPOG) included the reduction in the number of treatment centers, contemporary diagnostic procedures, vigorous supportation, enhanced access to hematopoietic stem cell transplantation (HSCT), and to targeted therapies. The major aim of our study was to evaluate AML treatment results of HPOG between 2012 and 2019 with 92 new patients registered (52 males, 40 females, mean age 7.28 years). Two periods were distinguished: 2012-2015 and 2016-2019 (55 and 37 patients, respectively). During these periods, 2 y OS increased from 63.6% to 71.4% (p = 0.057), and the 2 y EFS increased significantly from 56.4% to 68.9% (p = 0.02). HSCT was performed in 37 patients (5 patients received a second HSCT). We demonstrate advances in the diagnosis and treatment of acute promyelocytic leukemia (APL) in two cases. Early diagnosis and follow-up were achieved by multidimensional flow cytometry and advanced molecular methods. Both patients were successfully treated with all-trans retinoic acid and arsenic-trioxide, in addition to chemotherapy. In order to meet international standards of pediatric AML management, HPOG will further centralize treatment centers and diagnostic facilities and join efforts with international study groups.

Impact of Sirtuin Enzymes on the Altered Metabolic Phenotype of Malignantly Transformed Cells.

Sirtuins compose a unique collection of histone deacetylase enzymes that have a wide variety of enzymatic activities and regulate diverse cell functions such as cellular metabolism, longevity and energy homeostasis, mitochondrial function, and biogenesis. Impaired sirtuin functions or alterations of their expression levels may result in several pathological conditions and contribute to the altered metabolic phenotype of malignantly transformed cells in a significant manner. In the twenty-first century, principles of personalized anticancer treatment need to involve not only the evaluation of changes of the genetic material, but also the mapping of epigenetic and metabolic alterations, to both of which the contribution of sirtuin enzymes is fundamental. Since sirtuins are central players in the maintenance of cellular energy and metabolic homeostasis, they are key elements in the development of metabolic transformation of cancer cells referred to as the Warburg effect. Although its most well-known features are enhanced glycolysis and excessive lactate production, Warburg effect has several aspects involving both carbohydrate, lipid, and amino acid metabolism, among which different tumor types have different preferences. Therefore, energy supply of cancer cells can be impaired by a growing number of antimetabolite agents, for which appropriate vectors are strongly needed. However, data are controversial about their tumor suppressor or oncogenic properties, the biological effects of sirtuin enzymes strongly depend on the tissue microenvironment (TME) in which they are expressed. Immune cells are regarded as key players of TME. Sirtuins regulate the survival, activation, metabolism, and mitochondrial function of these cells, therefore, they are not only single elements, but key regulators of the network that determines anticancer immunity. Altered metabolism of tumor cells induces changes in the gene expression pattern of cells in TME, due to altered concentrations of metabolite cofactors of epigenetic modifiers including sirtuins. In summary, epigenetic and metabolic alterations in malignant diseases are influenced by sirtuins in a significant manner, and should be treated in a personalized approach. Since they often develop in early stages of cancer, broad examination of these alterations is required at time of the diagnosis in order to provide a personalized combination of distinct therapeutic agents.

[Gastrointestinal manifestations in immunodeficiencies with monogenic origin]. / Gastrointestinalis manifesztációk monogénes primer immundefektusokban.

Although very early onset inflammatory bowel disease that develops in early childhood (before the age of 6 years) has a different etiology from Crohn's disease and ulcerative colitis, it is also characterized by chronic inflammation of the gastrointestinal tract. Basically, very early onset inflammatory bowel disease should be considered as an immunodeficiency with monogenic origin where both gastrointestinal manifestations and symptoms of immunodeficiencies may develop in variable combinations. However, in the future, the evaluation of genetic alterations in the background of the disease will probably be performed by next-generation sequencing technology; one should also consider that the sequence of the DNA stands in continuous interaction with a wide variety of environmental effects, among which nutrition should be emphasized by all means. Epigenetic alterations that are induced by environmental factors, could contribute to the pathogenesis of inflammatory bowel diseases that develop during childhood, therefore, they should also be identified during further research. It has a key significance to establish the diagnosis of very early onset inflammatory bowel disease as early as possible, because this could give the opportunity to start the adequate treatment which is bone marrow transplantation in the case of monogenic immunodeficiencies. Orv Hetil. 2018; 159(49): 2050-2056.

Strong Correlation between the Expression Levels of HDAC4 and SIRT6 in Hematological Malignancies of the Adults.

Histone deacetylase enzymes, confirmed to have important role in the pathogenesis of leukemia, are promising targets of epigenetic treatment. However, in acute myeloid leukemia, our knowledge on their expression levels is limited, and controversial data have been published about their potential oncogenic or tumorsuppressor properties in solid tumors. In our study, the expression levels of HDAC4 and SIRT6 were evaluated via Western blot analysis in 45 bone marrow samples (2 uninfiltrated and 43 concerned by different kinds of hematological malignancies), including 32 specimens obtained from patients with newly diagnosed AML. Significantly higher HDAC4 level was detected in case of FLT3-ITD mutation compared to the group of patients without carrying this mutation (p < 0.05). Compared to the non-infiltrated samples, the expression level of HDAC4 in AML M5 patients has been proved to be significantly higher (p < 0.05). Decreasing expression levels of both HDAC4 and SIRT6 were observed during the induction treatment of FAB M5 type AML. Strong correlation has been proved between the expression levels of HDAC4 and SIRT6 (r = 0.722 in full cohort and r = 0.794 in AML), that confirms the recently suggested cooperation between NAD+-independent and NAD+-dependent HDAC enzymes in leukemia.

Expression Levels of Warburg-Effect Related microRNAs Correlate with each Other and that of Histone Deacetylase Enzymes in Adult Hematological Malignancies with Emphasis on Acute Myeloid Leukemia.

Disruption of epigenetic regulation and characteristic metabolic alterations (known as the Warburg-effect) are well-known hallmarks of cancer. In our study we investigated the expression levels of microRNAs and histone deacetylase enzymes via RT-qPCR in bone marrow specimens of adult patients suffering from hematological malignancies (total cohort n = 40), especially acute myeloid leukemia (n = 27). The levels of the three examined Warburg-effect related microRNAs (miR-378*, miR-23b, miR-26a) positively correlated with each other and the oncogenic miR-155 and miR-125b, while negatively with the level of the tumorsuppressor miR-124. Significant relationships have been confirmed between the levels of SIRT6, HDAC4 and the microRNAs listed above. In NPM1-mutated AML (n = 6), the level of miR-125b was significantly lower than in the group of AML patients not carrying this mutation (n = 13) (p < 0.05). In M5 FAB type of AML (n = 5), the level of miR-124 was significantly higher compared to the M2 group (n = 7) (p < 0.05). In two cases of FAB M5 AML, the levels of SIRT6 and miR-26a increased during the first 4 weeks of treatment. In the total cohort, white blood cell count at the time of the diagnosis significantly correlated with the levels of HDAC4, SIRT6, miR-124 and miR-26a. Our results suggest that Warburg-effect related microRNAs may have important role in the pathogenesis of leukemia, and the potential oncogenic property of HDAC4 and SIRT6 cannot be excluded in hematological malignancies. Elevated level of miR-125b can contribute to adverse prognosis of AML without NPM1 mutation. The prevailment of the tumorsuppressor property of miR-124 may depend on the accompanying genetic alterations.

[Epigenetic regulatory mechanisms and their disorders in leukemia]. / Epigenetikai szabályozó mechanizmusok és zavaraik leukémiában.

The term epigenetics includes regulatory mechanisms that influence gene expression without any changes in the sequence of the DNA, namely DNA methylation, histone modification and small, non-coding RNAs. Methylation of the DNA leads to the repression of gene expression, while histone modification can result in both activation and inhibition of the transcription depending on the type and site of modification. These mechanisms are confirmed to have important pathogenetic role during the process of leukemogenesis. In distinct subtypes of leukemia specific alterations of the DNA methylation profile, histone code and typical changes of the microRNA expression levels have been observed. The importance of them is inhered in their promising potential clinical applications. In order to achieve further improvement in the therapeutic results of leukemia, prognostic classification has to be further improved. With the help of the epigenetic alterations, subgroups could be differentiated within the known prognostic groups. Changes in the DNA methylation pattern, histone code and microRNA expression levels correlate with the success of the treatment in many cases, moreover they could provide help to predict chemoresistance or detect the minimal residual disease following chemotherapy. Enzymes influencing the structure of chromatin form a wide variety of new potential therapeutic targets. Based on preliminary results, sorts of epigenetic therapy may be combined successfully either with each other or with conventional chemotherapeutic drugs in the treatment of leukemia.

[MicroRNA-s and their role in malignant hematologic diseases]. / Mikro-RNS-ek és szerepük hematológiai malignus betegségekben.

MicroRNAs are a class of small non-coding RNAs regulating gene expression at posttranscriptional level. Their target genes include numerous regulators of cell cycle, cell proliferation as well as apoptosis. Therefore, they are implicated in the initiation and progression of cancer, tissue invasion and metastasis formation as well. MicroRNA profiles supply much information about both the origin and the differentiation state of tumours. MicroRNAs also have a key role during haemopoiesis. An altered expression level of those have often been observed in different types of leukemia. There are successful attempts to apply microRNAs in the diagnosis and prognosis of acute lymphoblastic leukemia and acute myeloid leukemia. Measurement of the expression levels may help to predict the success of treatment with different kinds of chemotherapeutic drugs. MicroRNAs are also regarded as promising therapeutic targets, and can contribute to a more personalized therapeutic approach in haemato-oncologic patients.