Cytokines and microRNA in pediatric B-acute lymphoblastic leukemia

The Role of MicroRNA in Paediatric Acute Lymphoblastic Leukaemia: Challenges for Diagnosis and Therapy

Acute lymphoblastic leukaemia (ALL) is the most common cancer of childhood. Although the overall survival of children with ALL is now more than 90%, leukaemia remains one of the leading causes of death from disease. In developed countries, the overall survival of patients with ALL has increased to more than 80%; however, those children cured from ALL still show a significant risk of short- and long-term complications as a consequence of their treatment. Accordingly, there is a need not only to develop new methods of diagnosis and prognosis but also to provide patients with less toxic therapies. MicroRNAs (miRNAs) are small ribonucleic acids (RNA), usually without coding potential, that regulate gene expression by directing their target messenger RNAs (mRNAs) for degradation or translational suppression. In paediatric ALL, several miRNAs have been observed to be overexpressed or underexpressed in patient cohorts compared to healthy individuals, while numerous studies have identified specific miRNAs that can be used as biomarkers to diagnose ALL, classify it into subgroups, and predict prognosis. Likewise, a variety of miRNAs identify as candidate targets for treatment, although there are numerous obstacles to overcome before their clinical use in patients. Here, we summarise the roles played by different miRNAs in childhood leukaemia, focussing primarily on their use as diagnostic tools and potential therapeutic targets, as well as a role in predicting treatment outcome. Finally, we discuss the potential roles of miRNA in immunotherapy and the novel contributions made by gut miRNAs to regulation of the host microbiome.

Knockdown of MAML1 inhibits proliferation and induces apoptosis of T-cell acute lymphoblastic leukemia cells through SP1-dependent inactivation of TRIM59

Notch exerts important functions in cell proliferation, survival, and differentiation, which plays a critical role in tumor development when aberrantly activated. Mastermind-like protein 1 (MAML1) has been functioning as crucial coactivators of Notch receptors and is required for stable formation of Notch transcriptional complexes. However, the mechanism whereby MAML1 induces T-cell acute lymphoblastic leukemia (T-ALL) tumorigenesis is largely unknown. The CCK-8 and flow cytometry assay were performed to examine the effect of MAML1 knockdown on T-ALL cell proliferation, apoptosis, and cell cycle. The expression of MAML1, cell cycle, and apoptosis-related gene, as well as TRIM family members and specific protein 1 (SP1) was measured by western blot analysis and qPCR. Our results showed that MAML1 knockdown significantly inhibited cell proliferation and induced G0/G1 cell cycle arrest and apoptosis in Jurkat and MOLT-4 cells. Cell cycle and apoptosis-related gene expression, including CDK2, Bcl-2, Bax, and Bad, was modified by the MAML1 knockdown. MAML1 knockdown obviously inhibited the CDK2 and Bcl-2 expression and increased the Bax, p53, and Bad expression. Moreover, the TRIM family members, including TRIM13, TRIM32, TRIM44, and TRIM59, were significantly decreased by the MAML1 knockdown, with the highest decrease detected in TRIM59 expression. Interesting, overexpression of SP1 not only increased the expression of MAML1 and TRIM59, but also promoted the promoter activation of TRIM59. Taken together, knockdown of MAML1 inhibits proliferation and induces apoptosis of T-ALL cells through SP1-dependent inactivation of TRIM59, and therefore suggest that MAML1-SP1-TRIM59 axis may serve as potentially interesting therapeutic targets for treatment of T-ALL.

Integrated analysis of microRNA and transcription factor reveals important regulators and regulatory motifs in adult B-cell acute lymphoblastic leukemia

B-cell acute lymphoblastic leukemia (B‑ALL) is an aggressive hematological malignancy and a leading cause of cancer-related mortality in children and young adults. The molecular mechanisms involved in the regulation of its gene expression has yet to be fully elucidated. In the present study, we performed large scale expression profiling of microRNA (miRNA) and transcription factor (TF) by Illumina deep‑sequencing and TF array technology, respectively, and identified 291 differentially expressed miRNAs and 201 differentially expressed TFs in adult B‑ALL samples relative to their controls. After integrating expression profile data with computational prediction of miRNA and TF targets from different databases, we construct a comprehensive miRNA‑TF regulatory network specifically for adult B‑ALL. Network function analysis revealed 25 significantly enriched pathways, four pathways are well‑known to be involved in B‑ALL, such as PI3K‑Akt signaling pathway, Jak‑STAT signaling pathway, Ras signaling pathway and cell cycle pathway. By analyzing the network topology, we identified 28 hub miRNAs and 19 hub TFs in the network, and found nine potential B‑ALL regulators among these hub nodes. We also constructed a Jak‑STAT signaling sub‑network for B‑ALL. Based on the sub‑network analysis and literature survey, we proposed a cellular model to discuss MYC/miR‑15a‑5p/FLT3 feed-forward loop (FFL) with Jak‑STAT signaling pathway in B‑ALL. These findings enhance our understanding of this disease at the molecular level, as well as provide putative therapeutic targets for B-ALL.

L-asparaginase as a critical component to combat Acute Lymphoblastic Leukaemia (ALL): A novel approach to target ALL

L-asparaginase, an anti-leukaemic drug that has been approved for clinical use for many years in the treatment of childhood Acute Lymphoblastic Leukaemia (ALL), is obtained from bacterial origin (Escherichia coli and Erwinia carotovora). The efficacy of L-asparaginase has been discussed for the past 40 years, and an ideal substitute for the enzyme has not yet been developed. The early clearance from plasma (short half-life) and requirement for multiple administrations and hence frequent physician visits make the overall treatment cost quite high. In addition, a high rate of allergic reactions in patients receiving treatment with the enzyme isolated from bacterial sources make its clinical application challenging. For these reasons, various attempts are being made to overcome these barriers. Therefore, the present article reviews studies focused on seeking substitutes for L-asparaginase through alternative sources including bacteria, fungi, actinomycetes, algae and plants to overcome these limitations. In addition, the role of chemical modifications and protein engineering approaches to enhance the drug's efficacy are also discussed. Moreover, an overview has also been provided in the current review regarding the contradiction among various researchers regarding the significance of the enzyme's glutaminase activity.

Bone Marrow Cells in Acute Lymphoblastic Leukemia Create a Proinflammatory Microenvironment Influencing Normal Hematopoietic Differentiation Fates

B-cell acute lymphoblastic leukemia (B-ALL) is a serious public health problem in the pediatric population worldwide, contributing to 85% of deaths from childhood cancers. Understanding the biology of the disease is crucial for its clinical management and the development of therapeutic strategies. In line with that observed in other malignancies, chronic inflammation may contribute to a tumor microenvironment resulting in the damage of normal processes, concomitant to development and maintenance of neoplastic cells. We report here that hematopoietic cells from bone marrow B-ALL have the ability to produce proinflammatory and growth factors, including TNFα, IL-1β, IL-12, and GM-CSF that stimulate proliferation and differentiation of normal stem and progenitor cells. Our findings suggest an apparently distinct CD13(+)CD33(+) population of leukemic cells contributing to a proinflammatory microenvironment that may be detrimental to long-term normal hematopoiesis within B-ALL bone marrow.

MicroRNAs Involved in Anti-Tumour Immunity

MicroRNAs (miRNAs) are a category of small RNAs that constitute a new layer of complexity to gene regulation within the cell, which has provided new perspectives in understanding cancer biology. The deregulation of miRNAs contributes critically to the development and pathophysiology of a number of cancers. miRNAs have been found to participate in cell transformation and multiplication by acting as tumour oncogenes or suppressors; therefore, harnessing miRNAs may provide promising cancer therapeutics. Another major function of miRNAs is their activity as critical regulatory vehicles eliciting important regulatory processes in anti-tumour immunity through their influence on the development, differentiation and activation of various immune cells of both innate and adaptive immunity. This review aims to summarise recent findings focusing on the regulatory mechanisms of the development, differentiation, and proliferative aspects of the major immune populations by a diverse profile of miRNAs and may enrich our current understanding of the involvement of miRNAs in anti-tumour immunity.

MicroRNAs and Glucocorticoid-Induced Apoptosis in Lymphoid Malignancies

The initial response of lymphoid malignancies to glucocorticoids (GCs) is a critical parameter predicting successful treatment. Although being known as a strong inducer of apoptosis in lymphoid cells for almost a century, the signaling pathways regulating the susceptibility of the cells to GCs are only partly revealed. There is still a need to develop clinical tests that can predict the outcome of GC therapy. In this paper, I discuss important parameters modulating the pro-apoptotic effects of GCs, with a specific emphasis on the microRNA world comprised of small players with big impacts. The journey through the multifaceted complexity of GC-induced apoptosis brings forth explanations for the differential treatment response and raises potential strategies for overcoming drug resistance.

Two hits are better than one: targeting both phosphatidylinositol 3-kinase and mammalian target of rapamycin as a therapeutic strategy for acute leukemia treatment

Phosphatidylinositol 3-kinase (PI3K) and mammalian target of rapamycin (mTOR) are two key components of the PI3K/Akt/mTOR signaling pathway. This signal transduction cascade regulates a wide range of physiological cell processes, that include differentiation, proliferation, apoptosis, autophagy, metabolism, motility, and exocytosis. However, constitutively active PI3K/Akt/mTOR signaling characterizes many types of tumors where it negatively influences response to therapeutic treatments. Hence, targeting PI3K/Akt/mTOR signaling with small molecule inhibitors may improve cancer patient outcome. The PI3K/Akt/mTOR signaling cascade is overactive in acute leukemias, where it correlates with enhanced drug-resistance and poor prognosis. The catalytic sites of PI3K and mTOR share a high degree of sequence homology. This feature has allowed the synthesis of ATP-competitive compounds targeting the catalytic site of both kinases. In preclinical models, dual PI3K/mTOR inhibitors displayed a much stronger cytotoxicity against acute leukemia cells than either PI3K inhibitors or allosteric mTOR inhibitors, such as rapamycin. At variance with rapamycin, dual PI3K/mTOR inhibitors targeted both mTOR complex 1 and mTOR complex 2, and inhibited the rapamycin-resistant phosphorylation of eukaryotic initiation factor 4E-binding protein 1, resulting in a marked inhibition of oncogenic protein translation. Therefore, they strongly reduced cell proliferation and induced an important apoptotic response. Here, we reviewed the evidence documenting that dual PI3K/mTOR inhibitors may represent a promising option for future targeted therapies of acute leukemia patients.

MicroRNA expression and activity in pediatric acute lymphoblastic leukemia (ALL)

Acute lymphoblastic leukemia (ALL) is the most common type of pediatric neoplasia. Highly heterogeneous, ALL includes several genetic subtypes with varying clinical outcome. Although, some features are well established as prognostic predictors, the details of the molecular mechanisms underlying different phenotypes are only beginning to emerge. Recently, microRNAs (miRNAs) have been shown to influence a range of physiological processes and, consequently, alterations in their expression and functions have been associated with the development of many cancers, including leukemia. This article aims to review the current state of knowledge of the role of miRNAs on the biology of childhood ALL, also including relevant findings from the adult leukemia literature.