CircNPM1 strengthens Adriamycin resistance in acute myeloid leukemia by mediating the miR-345-5p/FZD5 pathway

Screening of a Prognostic Gene Signature for Relapsed/Refractory Acute Myeloid Leukemia Based on Altered Circulating CircRNA Profiles

Background

Relapsed/refractory acute myeloid leukemia (R/R-AML) has dismal prognosis due to chemotherapy resistance. Circular RNAs (circRNAs) have shown emerging roles in chemotherapy resistance in various cancers including hematologic malignancies. However, the potential roles of circRNAs in AML progression and drug resistance remain largely undetermined.

Methods

In this study, circulating circRNAs expression profiles were analyzed among R/R-AML, de novo AML and healthy controls (HC) using a human circRNA Array. Bioinformatic analysis was carried out to explore the differentially expressed circRNAs (DE-circRNAs). GO, KEGG pathway analysis, along with circRNA-miRNA-mRNA network analysis, were conducted to identify the potential biological pathways involved in R/R-AML. Finally, the UALCAN database was used to assess the prognosis of different target DE-circRNAs-related mRNAs.

Results

Forty-eight DE-circRNAs were upregulated, whereas twenty-seven DE-circRNAs were downregulated in R/R-AML samples. Up-regulated DE-circRNAs in R/R-AML samples were mainly enrichment in the biological processes and pathways of cell migration, microRNAs in cancers, Rap1 and Ras signaling pathways. Six DE-circRNAs were randomly selected to further explore their relationships with R/R-AML. GO and KEGG pathway analyses of the six candidate DE-circRNAs-related target mRNAs were mainly involved in the regulation of signal transduction and Ras signaling pathway. By overlapping our RNA-sequencing results of differentially expressed genes (DEGs) in R/R-AML samples with the candidate DE-circRNAs-predicted target mRNAs, we identified sixty-eight overlapping targeted mRNAs. Using UALCAN database analysis, we identified that AML patients with six upregulated DE-circRNA-related genes (ECE1, PI4K2A, SLC9A6, CCND3, PPP1R16B, and TRIM32) and one downregulated gene DE-circRNA-related genes (ARHGAP10) might have a poor prognosis.

Conclusion

This study revealed the overall alterations of circRNAs in R/R-AML. DE-circRNAs and their related genes might be used as potential early, sensitive and stable biomarkers for AML diagnosis, R/R-AML monitoring, and even as novel treatment targets for R/R-AML.

Non-coding RNAs in leukemia drug resistance: new perspectives on molecular mechanisms and signaling pathways

Like almost all cancer types, timely diagnosis is needed for leukemias to be effectively cured. Drug efflux, attenuated drug uptake, altered drug metabolism, and epigenetic alterations are just several of the key mechanisms by which drug resistance develops. All of these mechanisms are orchestrated by up- and downregulators, in which non-coding RNAs (ncRNAs) do not encode specific proteins in most cases; albeit, some of them have been found to exhibit the potential for protein-coding. Notwithstanding, ncRNAs are chiefly known for their contribution to the regulation of physiological processes, as well as the pathological ones, such as cell proliferation, apoptosis, and immune responses. Specifically, in the case of leukemia chemo-resistance, ncRNAs have been recognized to be responsible for modulating the initiation and progression of drug resistance. Herein, we comprehensively reviewed the role of ncRNAs, specifically its effect on molecular mechanisms and signaling pathways, in the development of leukemia drug resistance.

CircRNA: a rising star in leukemia

Non-coding RNA are a class of RNA that lack the potential to encode proteins. CircRNAs, generated by a post-splicing mechanism, are a newly discovered type of non-coding RNA with multi-functional covalent loop structures. CircRNAs may play an important role in the occurrence and progression of tumors. Research has shown that circRNAs are aberrantly expressed in various types of human cancers, including leukemia. In this review, we summarize the expression and function of circRNAs and their impact on different types of leukemia. We also illustrate the function of circRNAs on immune modulation and chemoresistance in leukemia and their impact on its diagnosis and prognosis. Herein, we provide an understanding of recent advances in research that highlight the importance of circRNAs in proliferation, apoptosis, migration, and autophagy in different types of leukemia. Furthermore, circRNAs make an indispensable difference in the modulation of the immunity and chemoresistance of leukemia. Increasing evidence suggests that circRNAs may play a vital role in the diagnostic and prognostic markers of leukemia because of their prominent properties. More detailed preclinical studies on circRNAs are needed to explore effective ways in which they can serve as biomarkers for the diagnosis and prognosis of leukemia in vivo.

Gene SH3BGRL3 regulates acute myeloid leukemia progression through circRNA_0010984 based on competitive endogenous RNA mechanism

Introduction: Acute myeloid leukemia (AML) is a malignant proliferative disease affecting the bone marrow hematopoietic system and has a poor long-term outcome. Exploring genes that affect the malignant proliferation of AML cells can facilitate the accurate diagnosis and treatment of AML. Studies have confirmed that circular RNA (circRNA) is positively correlated with its linear gene expression. Therefore, by exploring the effect of SH3BGRL3 on the malignant proliferation of leukemia, we further studied the role of circRNA produced by its exon cyclization in the occurrence and development of tumors. Methods: Genes with protein-coding function obtained from the TCGA database. we detected the expression of SH3BGRL3 and circRNA_0010984 by real-time quantitative polymerase chain reaction (qRT-PCR). We synthesized plasmid vectors and carried out cell experiments, including cell proliferation, cell cycle and cell differentiation by cell transfection. We also studied the transfection plasmid vector (PLVX-SHRNA2-PURO) combined with a drug (daunorubicin) to observe the therapeutic effect. The miR-375 binding site of circRNA_0010984 was queried using the circinteractome databases, and the relationship was validated by RNA immunoprecipitation and Dual-luciferase reporter assay. Finally, a protein-protein interaction network was constructed with a STRING database. GO and KEGG functional enrichment identified mRNA-related functions and signaling pathways regulated by miR-375. Results: We identified the related gene SH3BGRL3 in AML and explored the circRNA_0010984 produced by its cyclization. It has a certain effect on the disease progression. In addition, we verified the function of circRNA_0010984. We found that circSH3BGRL3 knockdown specifically inhibited the proliferation of AML cell lines and blocked the cell cycle. We then discussed the related molecular biological mechanisms. CircSH3BGRL3 acts as an endogenous sponge for miR-375 to isolate miR-375 and inhibits its activity, increases the expression of its target YAP1, and ultimately activates the Hippo signaling pathway involved in malignant tumor proliferation. Discussion: We found that SH3BGRL3 and circRNA_0010984 are important to AML. circRNA_0010984 was significantly up-regulated in AML and promoted cell proliferation by regulating miR-375 through molecular sponge action.

Circular RNAs and Untranslated Regions in Acute Myeloid Leukemia

Before the advent of next-generation sequencing, research on acute myeloid leukemia (AML) mostly centered on protein-coding genes. In recent years, breakthroughs in RNA sequencing technologies and whole transcriptome analysis have led to the discovery that approximately 97.5% of the human genome is transcribed into non-coding RNAs (ncRNAs). This paradigm shift has led to an explosion of research interest in different classes of non-coding RNAs, such as circular RNAs (circRNAs) as well as non-coding untranslated regions (UTRs) of protein-coding messenger RNAs. The critical roles of circRNAs and UTRs in AML pathogenesis have become increasingly apparent. In this review, we discuss the cellular mechanisms of circRNAs and summarize recent studies that reveal their biological roles in AML. Furthermore, we also review the contribution of 3'UTRs to disease progression. Finally, we discuss the potential of circRNAs and 3'UTRs as new biomarkers for disease stratification and/or the prediction of treatment response and targets for the development of RNA-directed therapeutic applications.

Circular RNAs: pivotal role in the leukemogenesis and novel indicators for the diagnosis and prognosis of acute myeloid leukemia

Acute myeloid leukemia (AML) is an aggressive hematological malignancy and affected patients have poor overall survival (OS) rates. Circular RNAs (circRNAs) are a novel class of non-coding RNAs (ncRNAs) with a unique loop structure. In recent years, with the development of high-throughput RNA sequencing, many circRNAs have been identified exhibiting either up-regulation or down-regulation in AML patients compared with healthy controls. Recent studies have reported that circRNAs regulate leukemia cell proliferation, stemness, and apoptosis, both positively and negatively. Additionally, circRNAs could be promising biomarkers and therapeutic targets in AML. In this study, we present a comprehensive review of the regulatory roles and potentials of a number of dysregulated circRNAs in AML.

Functions and clinical significance of circular RNAs in acute myeloid leukemia

Circular RNAs (circRNAs) are a class of covalently closed single-stranded RNA molecules. Four types of circRNAs have been reported in animal cells, and they have typical characteristics in their biogenesis, nuclear export and degradation. Advances in our understanding of the molecular functions of circRNAs in sponging microRNAs, modulating transcription, regulating RNA-binding proteins, as well as encoding proteins have been made very recently. Dysregulated circRNAs are associated with human diseases such as acute myeloid leukemia (AML). In this review, we focus on the recently described mechanisms, role and clinical significance of circRNAs in AML. Although great progress of circRNAs in AML has been achieved, substantial efforts are still required to explore whether circRNAs exert their biological function by other mechanisms such as regulation of gene transcription or serving as translation template in AML. It is also urgent that researchers study the machineries regulating circRNAs fate, the downstream effectors of circRNAs modulatory networks, and the clinical application of circRNAs in AML.

Roles of circRNAs in hematological malignancies

As one of the leading causes of death, hematologic malignancies are associated with an ever-increasing incidence, and drug resistance and relapse of patients after treatment represent clinical challenges. Therefore, there are pressing demands to uncover biomarkers to indicate the development, progression, and therapeutic targets for hematologic malignancies. Circular RNAs (circRNAs) are covalently closed circular-single-stranded RNAs whose biosynthesis is regulated by various factors and is widely-expressed and evolutionarily conserved in many organisms and expressed in a tissue−/cell-specific manner. Recent reports have indicated that circRNAs plays an essential role in the progression of hematological malignancies. However, circRNAs are difficult to detect with low abundance using conventional techniques. We need to learn more information about their features to develop new detection methods. Herein, we sought to retrospect the current knowledge about the characteristics of circRNAs and summarized research on circRNAs in hematological malignancies to explore a potential direction.

Circular RNAs Activity in the Leukemic Bone Marrow Microenvironment

Acute myeloid leukemia (AML) is a hematological malignancy originating from defective hematopoietic stem cells in the bone marrow. In spite of the recent approval of several molecular targeted therapies for AML treatment, disease recurrence remains an issue. Interestingly, increasing evidence has pointed out the relevance of bone marrow (BM) niche remodeling during leukemia onset and progression. Complex crosstalk between AML cells and microenvironment components shapes the leukemic BM niche, consequently affecting therapy responsiveness. Notably, circular RNAs are a new class of RNAs found to be relevant in AML progression and chemoresistance. In this review, we provided an overview of AML-driven niche remodeling. In particular, we analyzed the role of circRNAs and their possible contribution to cell–cell communication within the leukemic BM microenvironment. Understanding these mechanisms will help develop a more effective treatment for AML.