miR-149-3p reverses CD8+ T-cell exhaustion by reducing inhibitory receptors and promoting cytokine secretion in breast cancer cells

The role of hypoxia-inducible factor 1 in tumor immune evasion

Hypoxia-inducible factor 1 (HIF-1) plays an indispensable role in the hypoxic tumor microenvironment. Hypoxia and HIF-1 are involved in multiple aspects of tumor progression, such as metastasis, angiogenesis, and immune evasion. In innate and adaptive immune systems, malignant tumor cells avoid their recognition and destruction by HIF-1. Tumor immune evasion allows cancer cells to proliferate and metastasize and is associated with immunotherapy failure and chemoresistance. In the hypoxic tumor microenvironment, HIF-1 signaling suppresses the innate and adaptive immune systems to evade immune attack by inducing the expression of immunosuppressive factors and immune checkpoint molecules, including vascular endothelial growth factor, prostaglandin E₂ , and programmed death-ligand 1/programmed death-1. Moreover, HIF-1 blocks tumor-associated antigen presentation via major histocompatibility complex class I chain-related/natural killer group 2, member D signaling. Tumor-associated autophagy and the release of tumor-derived exosomes contribute to HIF-1-mediated immune evasion. This review focuses on recent findings on the potential mechanism(s) underlying the effect of hypoxia and HIF-1 signaling on tumor immune evasion in the hypoxic tumor microenvironment. The effects of HIF-1 on immune checkpoint molecules, immunosuppressive molecules, autophagy, and exosomes have been described. Additionally, the potential role of HIF-1 in the regulation of tumor-derived exosomes, as well as the roles of HIF-1 and exosomes in tumor evasion, are discussed. This study will contribute to our understanding of HIF-1-mediated tumor immune evasion, leading to the development of effective HIF-1-targeting drugs and immunotherapies.

Expression, Regulation and Function of microRNA as Important Players in the Transition of MDS to Secondary AML and Their Cross Talk to RNA-Binding Proteins

Myelodysplastic syndromes (MDS), heterogeneous diseases of hematopoietic stem cells, exhibit a significant risk of progression to secondary acute myeloid leukemia (sAML) that are typically accompanied by MDS-related changes and therefore significantly differ to de novo acute myeloid leukemia (AML). Within these disorders, the spectrum of cytogenetic alterations and oncogenic mutations, the extent of a predisposing defective osteohematopoietic niche, and the irregularity of the tumor microenvironment is highly diverse. However, the exact underlying pathophysiological mechanisms resulting in hematopoietic failure in patients with MDS and sAML remain elusive. There is recent evidence that the post-transcriptional control of gene expression mediated by microRNAs (miRNAs), long noncoding RNAs, and/or RNA-binding proteins (RBPs) are key components in the pathogenic events of both diseases. In addition, an interplay between RBPs and miRNAs has been postulated in MDS and sAML. Although a plethora of miRNAs is aberrantly expressed in MDS and sAML, their expression pattern significantly depends on the cell type and on the molecular make-up of the sample, including chromosomal alterations and single nucleotide polymorphisms, which also reflects their role in disease progression and prediction. Decreased expression levels of miRNAs or RBPs preventing the maturation or inhibiting translation of genes involved in pathogenesis of both diseases were found. Therefore, this review will summarize the current knowledge regarding the heterogeneity of expression, function, and clinical relevance of miRNAs, its link to molecular abnormalities in MDS and sAML with specific focus on the interplay with RBPs, and the current treatment options. This information might improve the use of miRNAs and/or RBPs as prognostic markers and therapeutic targets for both malignancies.

microRNAs involved in T-cell development, selection, activation, and hemostasis

MicroRNAs (miRNAs) characterized by small, noncoding RNAs have a fundamental role in the regulation of gene expression at the post-transcriptional level. Additionally, miRNAs have recently been identified as potential regulators of various genes involved in the pathogenesis of the autoimmune and inflammatory disease. So far, the interaction between miRNAs and T lymphocytes in the immune response as a new and significant topic has not been emphasized substantially. The role of miRNAs in different biological processes including apoptosis, immune checkpoints and the activation of immune cells is still unclear. Aberrant miRNA expression profile affects various aspects of T-cell function. Accordingly, in this literature review, we summarized the role of significant miRNAs in T-cell development processes. Consequently, we demonstrated precise mechanisms that candidate miRNAs interfere in Immune response mediated by different types of T cells. We believe that a good understanding of the interaction between miRNAs and immune response contributes to the new therapeutic strategies in relation to disease with an immunological origin.

Role of microRNAs in remodeling the tumor microenvironment (Review)

MicroRNAs (miRNAs) are short non‑coding RNAs that are known to regulate gene expression at the post‑transcriptional level. miRNA expression is often deregulated in several human cancers, affecting the communication between tumor stroma and tumor cells, among other functions. Understanding the role of miRNAs in the tumor microenvironment is crucial for fully elucidating the molecular mechanisms underlying tumor progression and exploring novel diagnostic biomarkers and therapeutic targets. The present review focused on the role of miRNAs in remodeling the tumor microenvironment, with an emphasis on their impact on tumor growth, metastasis and resistance to treatment, as well as their potential clinical applications.