HOTAIRM1 knockdown enhances cytarabine-induced cytotoxicity by suppression of glycolysis through the Wnt/β-catenin/PFKP pathway in acute myeloid leukemia cells

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.

Targeting the Metabolic Paradigms in Cancer and Diabetes

Dysregulated metabolic dynamics are evident in both cancer and diabetes, with metabolic alterations representing a facet of the myriad changes observed in these conditions. This review delves into the commonalities in metabolism between cancer and type 2 diabetes (T2D), focusing specifically on the contrasting roles of oxidative phosphorylation (OXPHOS) and glycolysis as primary energy-generating pathways within cells. Building on earlier research, we explore how a shift towards one pathway over the other serves as a foundational aspect in the development of cancer and T2D. Unlike previous reviews, we posit that this shift may occur in seemingly opposing yet complementary directions, akin to the Yin and Yang concept. These metabolic fluctuations reveal an intricate network of underlying defective signaling pathways, orchestrating the pathogenesis and progression of each disease. The Warburg phenomenon, characterized by the prevalence of aerobic glycolysis over minimal to no OXPHOS, emerges as the predominant metabolic phenotype in cancer. Conversely, in T2D, the prevailing metabolic paradigm has traditionally been perceived in terms of discrete irregularities rather than an OXPHOS-to-glycolysis shift. Throughout T2D pathogenesis, OXPHOS remains consistently heightened due to chronic hyperglycemia or hyperinsulinemia. In advanced insulin resistance and T2D, the metabolic landscape becomes more complex, featuring differential tissue-specific alterations that affect OXPHOS. Recent findings suggest that addressing the metabolic imbalance in both cancer and diabetes could offer an effective treatment strategy. Numerous pharmaceutical and nutritional modalities exhibiting therapeutic effects in both conditions ultimately modulate the OXPHOS-glycolysis axis. Noteworthy nutritional adjuncts, such as alpha-lipoic acid, flavonoids, and glutamine, demonstrate the ability to reprogram metabolism, exerting anti-tumor and anti-diabetic effects. Similarly, pharmacological agents like metformin exhibit therapeutic efficacy in both T2D and cancer. This review discusses the molecular mechanisms underlying these metabolic shifts and explores promising therapeutic strategies aimed at reversing the metabolic imbalance in both disease scenarios.

PFKP is upregulated in 5-fluorouracil-resistant patients and suppresses the antitumor activity of 5-fluorouracil in colorectal cancer in vitro and in vivo

As a long-established chemotherapy drug, 5-fluorouracil (5-FU) is widely used to clinically manage colorectal cancer (CRC). However, a substantial portion of patients develop 5-FU resistance at some stage, which poses a great challenge. Therefore, revealing the mechanisms that could guide the development of effective strategies to overcome 5-FU resistance is required. Here, we report that the expression of PFKP was higher in HCT116/5-FU CRC. Furthermore, genetic suppression of PFKP suppresses glycolysis, NF-κB activation, and expression of GLUT1 and HK2 in HCT116/5-FU cells. PFKP overexpression promotes glycolysis and expression of GLUT1 and HK2 via the NF-κB signaling pathway in HCT116 cells. Our functional assays demonstrated that PFKP silencing could sensitize HCT116/5-FU cells to 5-FU with an elevated population of apoptotic cells. In contrast, forced expression of PFKP conferred 5-FU resistance in HCT116 cells. Furthermore, PFKP silencing significantly inhibited CRC xenograft tumor growth. Notably, the combination of PFKP silencing and 5-FU inhibited tumor growth. Therefore, our results demonstrated that PFKP enhances 5-FU resistance by promoting glycolysis, indicating that PFKP could be a novel candidate for targeted therapy for 5-FU-resistant CRC.

The tip of the iceberg-The roles of long noncoding RNAs in acute myeloid leukemia

Long noncoding RNAs (lncRNAs) are traditionally defined as RNA transcripts longer than 200 nucleotides that have no protein coding potential. LncRNAs have been identified to be dysregulated in various types of cancer, including the deadly hematopoietic cancer-acute myeloid leukemia (AML). Currently, survival rates for AML have reached a plateau necessitating new therapeutic targets and biomarkers to improve treatment options and survival from the disease. Therefore, the identification of lncRNAs as novel biomarkers and therapeutic targets for AML has major benefits. In this review, we assess the key studies which have recently identified lncRNAs as important molecules in AML and summarize the current knowledge of lncRNAs in AML. We delve into examples of the specific roles of lncRNA action in AML such as driving proliferation, differentiation block and therapy resistance as well as their function as tumor suppressors and utility as biomarkers. This article is categorized under: RNA in Disease and Development > RNA in Disease.

Plant-derived extracts and metabolic modulation in leukemia: a promising approach to overcome treatment resistance

Leukemic cells acquire complex and often multifactorial mechanisms of resistance to treatment, including various metabolic alterations. Although the use of metabolic modulators has been proposed for several decades, their use in clinical practice has not been established. Natural products, the so-called botanical drugs, are capable of regulating tumor metabolism, particularly in hematopoietic tumors, which could partly explain the biological activity attributed to them for a long time. This review addresses the most recent findings relating to metabolic reprogramming-Mainly in the glycolytic pathway and mitochondrial activity-Of leukemic cells and its role in the generation of resistance to conventional treatments, the modulation of the tumor microenvironment, and the evasion of immune response. In turn, it describes how the modulation of metabolism by plant-derived extracts can counteract resistance to chemotherapy in this tumor model and contribute to the activation of the antitumor immune system.

Long non-coding RNAs regulate treatment outcome in leukemia: What have we learnt recently?

Leukemia is a group of highly heterogeneous and life-threatening blood cancers that originate from abnormal hematopoietic stem cells. Multiple treatments are approved for leukemia, including chemotherapy, targeted therapy, hematopoietic stem cell transplantation, radiation therapy, and immunotherapy. Unfortunately, therapeutic resistance occurs in a substantial proportion of patients and greatly compromises the treatment efficacy of leukemia, resulting in relapse and mortality. The abnormal activity of receptor tyrosine kinases, cell membrane transporters, intracellular signal transducers, transcription factors, and anti-apoptotic proteins have been shown to contribute to the emergence of therapeutic resistance. Despite these findings, the exact mechanisms of treatment resistance are still not fully understood, which limits the development of effective measures to overcome it. Long non-coding RNAs (lncRNA) are a class of regulatory molecules that are gaining increasing attention, and lncRNA-mediated regulation of therapeutic resistance against multiple drugs for leukemia is being revealed. These dysregulated lncRNAs not only serve as potential targets to reduce resistance but also might improve treatment response prediction and individualized treatment decision. Here, we summarize the recent findings on lncRNA-mediated regulation of therapeutic resistance in leukemia and discuss future perspectives on how to make use of the dysregulated lncRNAs in leukemia to improve treatment outcome.

Targeting and Monitoring Acute Myeloid Leukaemia with Nucleophosmin-1 (NPM1) Mutation

Mutations in NPM1, also known as nucleophosmin-1, B23, NO38, or numatrin, are seen in approximately one-third of patients with acute myeloid leukaemia (AML). A plethora of treatment strategies have been studied to determine the best possible approach to curing NPM1-mutated AML. Here, we introduce the structure and function of NPM1 and describe the application of minimal residual disease (MRD) monitoring using molecular methods by means of quantitative polymerase chain reaction (qPCR), droplet digital PCR (ddPCR), next-generation sequencing (NGS), and cytometry by time of flight (CyTOF) to target NPM1-mutated AML. Current drugs, now regarded as the standard of care for AML, as well as potential drugs still under development, will also be explored. This review will focus on the role of targeting aberrant NPM1 pathways such as BCL-2 and SYK; as well as epigenetic regulators (RNA polymerase), DNA intercalators (topoisomerase II), menin inhibitors, and hypomethylating agents. Aside from medication, the effects of stress on AML presentation have been reported, and some possible mechanisms outlined. Moreover, targeted strategies will be briefly discussed, not only for the prevention of abnormal trafficking and localisation of cytoplasmic NPM1 but also for the elimination of mutant NPM1 proteins. Lastly, the advancement of immunotherapy such as targeting CD33, CD123, and PD-1 will be mentioned.

HOX cluster-embedded lncRNAs and epithelial-mesenchymal transition in cancer: Molecular mechanisms and therapeutic opportunities

Although there has been substantial improvement in the treatment modalities, cancer remains the major cause of fatality worldwide. Metastasis, recurrence, and resistance to oncological therapies are the leading causes of cancer mortality. Epithelial-mesenchymal transition (EMT) is a complex biological process that allows cancer cells to undergo morphological transformation into a mesenchymal phenotype to acquire invasive potential. It encompasses reversible and dynamic ontogenesis by neoplastic cells during metastatic dissemination. Hence, understanding the molecular landscape of EMT is imperative to identify a reliable clinical biomarker to combat metastatic spread. Accumulating evidence reveals the role of HOX (homeobox) cluster-embedded long non-coding RNAs (lncRNAs) in EMT and cancer metastasis. They play a crucial role in the induction of EMT, modulating diverse biological targets. The present review emphasizes the involvement of HOX cluster-embedded lncRNAs in EMT as a molecular sponge, chromatin remodeler, signaling regulator, and immune system modulator. Furthermore, the molecular mechanisms behind therapy resistance and the potential use of novel drugs targeting HOX cluster-embedded lncRNAs in the clinical management of distant metastasis will be discussed.

Autophagy and Glycometabolic Reprograming in the Malignant Progression of Lung Cancer: A Review

Lung cancer is one of the leading causes of cancer-related deaths worldwide. However, there are currently limited treatment options that are widely available to patients with advanced lung cancer, and further research is required to inhibit or reverse disease progression more effectively. In lung and other solid tumor cancers, autophagy and glycometabolic reprograming are critical regulators of malignant development, including proliferation, drug resistance, invasion, and metastasis. To provide a theoretical basis for therapeutic strategies targeting autophagy and glycometabolic reprograming to prevent lung cancer, we review how autophagy and glycometabolism are regulated in the malignant development of lung cancer based on research progress in other solid tumors.

HOTAIRM1 knockdown reduces MPP+-induced oxidative stress injury of SH-SY5Y cells by activating the Nrf2/HO-1 pathway

Objective

Parkinson's disease (PD) is the second most common neurodegenerative disease with complex pathogenesis. Although HOXA transcript antisense RNA myeloid-specific 1 (HOTAIRM1) is upregulated in PD, its exact role in HOTAIRM1 is seldom reported. The purpose of this study is to research the effect of HOTAIRM1 on 1-methyl-4-phenylpyridonium (MPP⁺)-induced cytotoxicity and oxidative stress in SH-SY5Y cells.

Methods

SH-SY5Y cells were treated with MPP⁺ at various concentrations or time points to induce SH-SY5Y cytotoxicity, so as to determine the optimal MPP⁺ concentration and time point. HOTAIRM1 expression upon MPP⁺ treatment was analyzed through qRT-PCR. Next, HOTAIRM1 was downregulated to observe the variance of SH-SY5Y cell viability, apoptosis, oxidative stress-related indexes, and protein levels of the Nrf2/HO-1 pathway. In addition, rescue experiments were carried out to assess the role of Nrf2 silencing in HOTAIRM1 knockdown on MPP⁺-induced oxidative stress in SH-SY5Y cells.

Results

MPP⁺ treatment-induced cytotoxicity and upregulated HOTAIRM1 expression in SH-SY5Y cells in a dose- and time-dependent manner. Mechanically, HOTAIRM1 knockdown enhanced cell viability, limited apoptosis, and oxidative stress, therefore protecting SH-SY5Y cells from MPP⁺-induced SH-SY5Y cytotoxicity. On the other hand, HOTAIRM1 knockdown activated the protein levels of Nrf2 and HO-1. Nrf2 silencing could counteract the neuroprotective effect of HOTAIRM1 knockdown on in vitro PD model.

Conclusion

Our data demonstrated that HOTAIRM1 knockdown could inhibit apoptosis and oxidative stress and activated the Nrf2/HO-1 pathway, therefore exerting neuroprotective effect on the PD cell model.

Non-coding RNA-related antitumor mechanisms of marine-derived agents

In the last two decades, natural active substances have attracted great attention in developing new antitumor drugs, especially in the marine environment. A series of marine-derived compounds or derivatives with potential antitumor effects have been discovered and developed, but their mechanisms of action are not well understood. Emerging studies have found that several tumor-related signaling pathways and molecules are involved in the antitumor mechanisms of marine-derived agents, including noncoding RNAs (ncRNAs). In this review, we provide an update on the regulation of marine-derived agents associated with ncRNAs on tumor cell proliferation, apoptosis, cell cycle, invasion, migration, drug sensitivity and resistance. Herein, we also describe recent advances in marine food-derived ncRNAs as antitumor agents that modulate cross-species gene expression. A better understanding of the antitumor mechanisms of marine-derived agents mediated, regulated, or sourced by ncRNAs will provide new biomarkers or targets for potential antitumor drugs from preclinical discovery and development to clinical application.

Bioinformatic Analyses of Broad H3K79me2 Domains in Different Leukemia Cell Line Data Sets

A subset of expressed genes is associated with a broad H3K4me3 (histone H3 trimethylated at lysine 4) domain that extends throughout the gene body. Genes marked in this way in normal cells are involved in cell-identity and tumor-suppressor activities, whereas in cancer cells, genes driving the cancer phenotype (oncogenes) have this feature. Other histone modifications associated with expressed genes that display a broad domain have been less studied. Here, we identified genes with the broadest H3K79me2 (histone H3 dimethylated at lysine 79) domain in human leukemic cell lines representing different forms of leukemia. Taking a bioinformatic approach, we provide evidence that genes with the broadest H3K79me2 domain have known roles in leukemia (e.g., JMJD1C). In the mixed-lineage leukemia cell line MOLM-13, the HOXA9 gene is in a 100 kb broad H3K79me2 domain with other HOXA protein-coding and oncogenic long non-coding RNA genes. The genes in this domain contribute to leukemia. This broad H3K79me2 domain has an unstable chromatin structure, as was evident by enhanced chromatin accessibility throughout. Together, we provide evidence that identification of genes with the broadest H3K79me2 domain will aid in generating a panel of genes in the diagnosis and therapeutic treatment of leukemia in the future.

HOTAIRM1 Maintained the Malignant Phenotype of tMSCs Transformed by GSCs via E2F7 by Binding to FUS

Objective. Mesenchymal stromal/stem cells (MSCs) are an important part of the glioma microenvironment and are involved in the malignant progression of glioma. In our previous study, we showed that MSCs can be induced to a malignant phenotype (tMSCs) by glioma stem cells (GSCs) in the microenvironment. However, the potential mechanism by which tMSCs maintain their malignant phenotype after malignant transformation has not been fully clarified. Methods. The expression of HOTAIRM1, FUS, and E2F7 was detected by qRT-PCR. Clone formation, EdU, and Transwell assay were used to explore the role of HOTAIRM1, FUS, and E2F7 on the proliferation, migration, and invasion of tMSCs. Bioinformatics analysis and RNA immunoprecipitation were used to explore the relation among HOTAIRM1, FUS, and E2F7. Results. HOTAIRM1 was upregulated in tMSCs compared with MSCs. Loss- and gain-of-function assays showed that HOTAIRM1 promoted the proliferation, migration, and invasion of tMSCs. qRT-PCR and functional assays revealed that E2F7 might be the downstream target of HOTAIRM1. A further study of the mechanism showed that HOTAIRM1 could bind to FUS, an RNA-binding protein (RBP), and thus regulate E2F7, which could promote the malignant phenotype of tMSCs. Conclusion. Our study revealed that the HOTAIRM1/FUS/E2F7 axis is involved in the malignant progression of tMSCs transformed by GSCs in the glioma microenvironment and may function as a novel target for glioma therapy.

Circulating microRNA sequencing revealed miRNome patterns in hematology and oncology patients aiding the prognosis of invasive aspergillosis

Invasive aspergillosis (IA) may occur as a serious complication of hematological malignancy. Delays in antifungal therapy can lead to an invasive disease resulting in high mortality. Currently, there are no well-established blood circulating microRNA biomarkers or laboratory tests which can be used to diagnose IA. Therefore, we aimed to define dysregulated miRNAs in hematology and oncology (HO) patients to identify biomarkers predisposing disease. We performed an in-depth analysis of high-throughput small transcriptome sequencing data obtained from the whole blood samples of our study cohort of 50 participants including 26 high-risk HO patients and 24 controls. By integrating in silico bioinformatic analyses of small noncoding RNA data, 57 miRNAs exhibiting significant expression differences (P < 0.05) were identified between IA-infected patients and non-IA HO patients. Among these, we found 36 differentially expressed miRNAs (DEMs) irrespective of HO malignancy. Of the top ranked DEMs, we found 14 significantly deregulated miRNAs, whose expression levels were successfully quantified by qRT-PCR. MiRNA target prediction revealed the involvement of IA related miRNAs in the biological pathways of tumorigenesis, the cell cycle, the immune response, cell differentiation and apoptosis.

Identification of a Three-Glycolysis-Related lncRNA Signature Correlated With Prognosis and Metastasis in Clear Cell Renal Cell Carcinoma

The clear cell renal cell carcinoma (ccRCC) is not only a malignant disease but also an energy metabolic disease, we aimed to identify a novel prognostic model based on glycolysis-related long non-coding RNA (lncRNAs) and explore its mechanisms. With the use of Pearson correlation analysis between the glycolysis-related differentially expressed genes and lncRNAs from The Cancer Genome Atlas (TCGA) dataset, we identified three glycolysis-related lncRNAs and successfully constructed a prognostic model based on their expression. The diagnostic efficacy and the clinically predictive capacity of the signature were evaluated by univariate and multivariate Cox analyses, Kaplan–Meier survival analysis, and principal component analysis (PCA). The glycolysis-related lncRNA signature was constructed based on the expressions of AC009084.1, AC156455.1, and LINC00342. Patients were grouped into high- or low-risk groups according to risk score demonstrated significant differences in overall survival (OS) period, which were validated by patients with ccRCC from the International Cancer Genome Consortium (ICGC) database. Univariate Cox analyses, multivariate Cox analyses, and constructed nomogram-confirmed risk score based on our signature were independent prognosis predictors. The CIBERSORT algorithms demonstrated significant correlations between three-glycolysis-related lncRNAs and the tumor microenvironment (TME) components. Functional enrichment analysis demonstrated potential pathways and processes correlated with the risk model. Clinical samples validated expression levels of three-glycolysis-related lncRNAs, and LINC00342 demonstrated the most significant aberrant expression. in vitro, the general overexpression of LINC00342 was detected in ccRCC cells. After silencing LINC00342, the aberrant glycolytic levels and migration abilities in 786-O cells were decreased significantly, which might be explained by suppressed Wnt/β-catenin signaling pathway and reversed Epithelial mesenchymal transformation (EMT) process. Collectively, our research identified a novel three-glycolysis-related lncRNA signature as a promising model for generating accurate prognoses for patients with ccRCC, and silencing lncRNA LINC00342 from the signature could partly inhibit the glycolysis level and migration of ccRCC cells.

Identification of m6A-Related lncRNAs Associated With Prognoses and Immune Responses in Acute Myeloid Leukemia

Background: Acute myeloid leukemia (AML) remains the most common type of hematopoietic malignancy in adults and has an unfavorable outcome. Herein, we aimed to construct an N6-methylandenosine (m6A)-related long noncoding RNAs (lncRNAs) signature to accurately predict the prognosis of patients with AML using the data downloaded from The Cancer Genome Atlas (TCGA) database.

Methods: The RNA-seq and clinical data were obtained from the TCGA AML cohort. First, Pearson correlation analysis was performed to identify the m6A-related lncRNAs. Next, univariate Cox regression analysis was used to determine the candidate lncRNAs with prognostic value. Then, feature selection was carried out by Least absolute shrinkage and selection operator (LASSO) analysis, and seven eligible m6A-related lncRNAs were included to construct the prognostic risk signature. Kaplan–Meier and receiver operating characteristic (ROC) curve analyses were performed to evaluate the predictive capacity of the risk signature both in the training and testing datasets. A nomogram was used to predict 1-year, 2-year, and 3-year overall survival (OS) of AML patients. Next, the expression levels of lncRNAs in the signature were validated in AML samples by qRT-PCR. Functional enrichment analyses were carried out to identify probable biological processes and cellular pathways. The ceRNA network was developed to explore the downstream targets and mechanisms of m6A-related lncRNAs in AML.

Results: Seven m6A-related lncRNAs were identified as a prognostic signature. The low-risk group hold significantly prolonged OS. The nomogram showed excellent accuracy of the signature for predicting 1-year, 2-year and 3-year OS (AUC = 0.769, 0.820, and 0.800, respectively). Moreover, the risk scores were significantly correlated with enrichment in cancer hallmark- and malignancy-related pathways and immunotherapy response in AML patients.

Conclusion: We developed and validated a novel risk signature with m6A-related lncRNAs which could predict prognosis accurately and reflect the immunotherapy response in AML patients.

Mutant NPM1-regulated lncRNA HOTAIRM1 promotes leukemia cell autophagy and proliferation by targeting EGR1 and ULK3

Background

Acute myeloid leukemia (AML) with mutated nucleophosmin (NPM1), which displays a distinct long noncoding RNA (lncRNA) expression profile, has been defined as a unique subgroup in the new classification of myeloid neoplasms. However, the biological roles of key lncRNAs in the development of NPM1-mutated AML are currently unclear. Here, we aimed to investigate the functional and mechanistic roles of the lncRNA HOTAIRM1 in NPM1-mutated AML.

Methods

The expression of HOTAIRM1 was analyzed with a public database and further determined by qRT-PCR in NPM1-mutated AML samples and cell lines. The cause of upregulated HOTAIRM1 expression was investigated by luciferase reporter, chromatin immunoprecipitation and ubiquitination assays. The functional role of HOTAIRM1 in autophagy and proliferation was evaluated using western blot analysis, immunofluorescence staining, a Cell Counting Kit-8 (CCK-8) assay, a 5-ethynyl-2′-deoxyuridine (EdU) incorporation assay, flow cytometric analyses and animal studies. The action mechanism of HOTAIRM1 was explored through RNA fluorescence in situ hybridization, RNA pulldown and RNA immunoprecipitation assays.

Results

HOTAIRM1 was highly expressed in NPM1-mutated AML. High HOTAIRM1 expression was induced in part by mutant NPM1 via KLF5-dependent transcriptional regulation. Importantly, HOTAIRM1 promoted autophagy and proliferation both in vitro and in vivo. Mechanistic investigations demonstrated that nuclear HOTAIRM1 promoted EGR1 degradation by serving as a scaffold to facilitate MDM2-EGR1 complex formation, while cytoplasmic HOTAIRM1 acted as a sponge for miR-152-3p to increase ULK3 expression.

Conclusions

Taken together, our findings identify two oncogenic regulatory axes in NPM1-mutated AML centered on HOTAIRM1: one involving EGR1 and MDM2 in the nucleus and the other involving the miR-152-3p/ULK3 axis in the cytoplasm. Our study indicates that HOTAIRM1 may be a promising therapeutic target for this distinct leukemia subtype.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-02122-2.

Long noncoding RNAs: A novel insight in the leukemogenesis and drug resistance in acute myeloid leukemia

Acute myeloid leukemia (AML) is a common hematological disorder with heterogeneous nature that resulted from blocked myeloid differentiation and an enhanced number of immature myeloid progenitors. During several decades, different factors, including cytogenetic, genetic, and epigenetic have been reported to contribute to the pathogenesis of AML by inhibiting the differentiation and ensuring the proliferation of myeloid blast cells. Recently, long noncoding RNAs (lncRNAs) have been considered as potential diagnostic, therapeutic, and prognostic factors in different human malignancies including AML. Altered expression of lncRNAs is correlated with the transformation of hematopoietic stem and progenitor cells into leukemic blast cells because of their distinct role in the key cellular processes. We discuss the significant role of lncRNAs in the proliferation, survival, differentiation, leukemic stem cells in AML and their involvement in different molecular pathways (insulin-like growth factor type I receptor, FLT3, c-KIT, Wnt, phosphatidylinositol 3-kinase/protein kinase-B, microRNAs), and associated mechanisms such as autophagy, apoptosis, and glucose metabolism. In addition, we aim to highlight the role of lncRNAs as reliable biomarkers for diagnosis, prognosis, and drug resistance for precision medicine in AML.

Role of the HOXA cluster in HSC emergence and blood cancer

Hematopoiesis, the process of blood formation, is controlled by a complex developmental program that involves intrinsic and extrinsic regulators. Blood formation is critical to normal embryonic development and during embryogenesis distinct waves of hematopoiesis have been defined that represent the emergence of hematopoietic stem or progenitor cells. The Class I family of homeobox (HOX) genes are also critical for normal embryonic development, whereby mutations are associated with malformations and deformity. Recently, members of the HOXA cluster (comprising 11 genes and non-coding RNA elements) have been associated with the emergence and maintenance of long-term repopulating HSCs. Previous studies identified a gradient of HOXA expression from high in HSCs to low in circulating peripheral cells, indicating their importance in maintaining blood cell numbers and differentiation state. Indeed, dysregulation of HOXA genes either directly or by genetic lesions of upstream regulators correlates with a malignant phenotype. This review discusses the role of the HOXA cluster in both HSC emergence and blood cancer formation highlighting the need for further research to identify specific roles of these master regulators in normal and malignant hematopoiesis.

Long non-coding RNA HOTAIRM1-1 silencing in cartilage tissue induces osteoarthritis through microRNA-125b

Aberrations in long noncoding RNA (lncRNA) expression have been recognized in numerous human diseases. In the present study, the of role the long noncoding RNA HOX antisense intergenic RNA myeloid 1 variant (HOTAIRM1-1) in regulating the pathological progression of osteoarthritis (OA) was investigated. The aberrant expression of HOTAIRM1-1 in OA was demonstrated, but the molecular mechanisms require further analysis. The aim of the present study was to explore the function of miR-125b in modulating chondrocyte viability and apoptosis, and to address the functional association between HOTAIRM1-1 and miR-125b as potential targets. A miR-125b inhibitor was used, which laid the foundation for the following investigation. The study confirmed that HOTAIRM1-1 and miR-125b are inversely expressed in chondrocytes. The expression of HOTAIRM1-1 was downregulated and the expression of miR-125b was upregulated in tissues from patients with OA. HOTAIRM1-1 directly interacted with miR-125b in chondrocytes. HOTAIRM1-1 knockdown was associated with chondrocyte proliferation and extracellular matrix degradation. Furthermore, miR-125b reversed the effect of HOTAIRM1-1 on cell proliferation and apoptosis. In conclusion, the present study indicates that the loss of HOTAIRM1-1 function leads to aberrant increases in the proliferation and apoptosis of chondrocytes. miR-125b may be a potential downstream mechanism that regulates the function of HOTAIRM1-1, and this finding provides a therapeutic strategy for OA.

HCP5, as the sponge of miR-1291, facilitates AML cell proliferation and restrains apoptosis via increasing PIK3R5 expression

Background

Acute myeloid leukemia (AML) is recognized as a hematological neoplasm with heterogenetic cytology and short-term outcome. HCP5 has been proven to be related with the pathogenesis of AML. However, the underlying mechanism of HCP5 in AML remains unclear.

Methods

Clinical profiles of AML patients were downloaded from TCGA and GTEx databases. LncBase and TargetScan online tools were utilized to predict potential targets, and dual-luciferase reporter assay was performed to verify the association between miR-1291 and HCP5 or PIK3R5. Cell Counting Kit 8 and flow cytometry tests were implemented to evaluate the effects of HCP5/miR-1291/PIK3R5 axis in AML cells. Quantitative RT-PCR and Western blot were conducted to detect the expression levels of genes.

Results

HCP5 and PIK3R5 were significantly increased in AML tissue samples compared with healthy controls. HCP5 facilitated AML cells viability and inhibited apoptosis. There was a positive relationship between HCP5 and PIK3R5, but miR-1291 negatively regulated PIK3R5. Overexpression of PIK3R5 enhanced the promoting effect of HCP5 in the development of AML, while weakened the suppression of miR-1291 to AML progression.

Conclusion

Our findings manifested that HCP5 was remarkably upregulated in AML and upregulated HCP5 promoted the malignant behaviors of AML cells by mediating miR-1291/PIK3R5 axis, which would provide a new insight for the treatment of AML.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40246-021-00340-5.

Involvement of Long Non-Coding RNAs in Glucose Metabolism in Cancer

The rapid and uncontrolled proliferation of cancer cells is supported by metabolic reprogramming. Altered glucose metabolism supports cancer growth and progression. Compared with normal cells, cancer cells show increased glucose uptake, aerobic glycolysis and lactate production. Byproducts of adjusted glucose metabolism provide additional benefits supporting hallmark capabilities of cancer cells. Long non-coding RNAs (lncRNAs) are a heterogeneous group of transcripts of more than 200 nucleotides in length. They regulate numerous cellular processes, primarily through physical interaction with other molecules. Dysregulated lncRNAs are involved in all hallmarks of cancer including metabolic alterations. They may upregulate metabolic enzymes, modulate the expression of oncogenic or tumor-suppressive genes and disturb metabolic signaling pathways favoring cancer progression. Thus, lncRNAs are not only potential clinical biomarkers for cancer diagnostics and prediction but also possible therapeutic targets. This review summarizes the lncRNAs involved in cancer glucose metabolism and highlights their underlying molecular mechanisms.

LncRNA HOTAIRM1 knockdown inhibits cell glycolysis metabolism and tumor progression by miR-498/ABCE1 axis in non-small cell lung cancer

BACKGROUND

Non-small cell lung cancer (NSCLC) is a major contributor of cancer-related mortality. Long non-coding RNAs (lncRNAs) are indicated to participate in the pathogenesis of NSCLC.

OBJECTIVE

In this research, the effects of lncRNA HOXA transcript antisense RNA, myeloid-specific 1 (HOTAIRM1) on NSCLC progression and underlying mechanism were revealed.

METHODS

The expression levels of HOTAIRM1 and microRNA-498 (miR-498) were detected by quantitative real time polymerase chain reaction (qRT-PCR) in NSCLC tissues, cells or exosomes. The protein expression of CD63, CD81, hexokinase 2 (HK2) and ATP binding cassette subfamily E member 1 (ABCE1) was determined by western blot. Cell viability, apoptosis, migration and invasion were investigated by cell counting kit-8 (CCK-8), flow cytometry, transwell migration and invasion assays, respectively. Cell glycolysis metabolism was revealed by glucose uptake and lactate production assays and western blot analysis. The binding relationship between miR-498 and HOTAIRM1 or ABCE1 was predicted by DIANA-LncBase v2 and starBase online database, and identified by dual-luciferase reporter assay. The effects of HOTAIRM1 on NSCLC growth in vivo were revealed by in vivo tumor formation assay.

RESULTS

HOTAIRM1 expression was dramatically upregulated, whereas miR-498 expression was significantly downregulated in NSCLC tissues cells or exosomes as compared to control groups. Mechanistically, HOTAIRM1 knockdown repressed cell viability, migration, invasion and glycolysis metabolism, whereas induced cell apoptosis in NSCLC; however, miR-498 inhibitor hindered these effects. Functionally, HOTAIRM1 functioned as a sponge of miR-498 and miR-498 targeted ABCE1. In addition, HOTAIRM1 silencing inhibited NSCLC growth in vivo by downregulating ABCE1 and upregulating miR-498 expression.

CONCLUSIONS

HOTAIRM1 knockdown repressed cell glycolysis metabolism and tumor development by reducing ABCE1 expression through sponging miR-498 in NSCLC, which provided a theoretical basis for further studying NSCLC progression.

HOTAIRM1 promotes osteogenic differentiation and alleviates osteoclast differentiation by inactivating the NF-κB pathway

Osteoporosis (OP), one of the most prevalent chronic progressive bone diseases, is caused by deficiency in bone formation by osteoblasts or excessive bone resorption by osteoclasts and subsequently increases the risk of bone fractures. Emerging evidence has indicated that long noncoding RNAs (lncRNAs) play key roles in many biological processes and various disorders. However, the role and mechanism of HOX antisense intergenic RNA myeloid 1 (HOTAIRM1), a myeloid-specific lncRNA, in osteoclast differentiation, osteogenic differentiation, and OP remain unclear. In this study, we found that HOTAIRM1 was upregulated during ossification of ligamentum flavum and osteogenic differentiation, while it was downregulated in osteoclast differentiation and in the bone and serum of human and mouse with OP. Further investigation revealed that silencing Hotairm1 decreased the expression of the osteogenic markers and attenuated osteogenesis. Moreover, forced Hotairm1 expression inhibited the expressions of the osteoclastogenesis markers and alleviated receptor activator of nuclear factor kappa B (NF-κB) ligand (RANKL)-induced osteoclast differentiation. Mechanically, Hotairm1 repressed the phosphorylation of p65 and inhibitor of κBα (IκBα) and attenuated RANKL-mediated enhancement of phos-p65 and IκBα, suggesting that Hotairm1 inhibits RANKL-induced osteoclastogenesis through the NF-κB pathway. In conclusion, our data identified a crucial role of HOTAIRM1 in OP, providing a proof of this molecule as a potential diagnostic marker and a possible therapeutic target against OP.

Glycolysis-induced drug resistance in tumors-A response to danger signals?

Tumor cells often switch from mitochondrial oxidative metabolism to glycolytic metabolism even under aerobic conditions. Tumor cell glycolysis is accompanied by several nonenzymatic activities among which induction of drug resistance has important therapeutic implications. In this article, we review the main aspects of glycolysis-induced drug resistance. We discuss the classes of antitumor drugs that are affected and the components of the glycolytic pathway (transporters, enzymes, metabolites) that are involved in the induction of drug resistance. Glycolysis-associated drug resistance occurs in response to stimuli, either cell-autonomous (e.g., oncoproteins) or deriving from the tumor microenvironment (e.g., hypoxia or pseudohypoxia, mechanical cues, etc.). Several mechanisms mediate the induction of drug resistance in response to glycolytic metabolism: inhibition of apoptosis, induction of epithelial-mesenchymal transition, induction of autophagy, inhibition of drug influx and increase of drug efflux. We suggest that drug resistance in response to glycolysis comes into play in presence of qualitative (e.g., expression of embryonic enzyme isoforms, post-translational enzyme modifications) or quantitative (e.g., overexpression of enzymes or overproduction of metabolites) alterations of glycolytic metabolism. We also discern similarities between changes occurring in tumor cells in response to stimuli inducing glycolysis-associated drug resistance and those occurring in cells of the innate immune system in response to danger signals and that have been referred to as danger-associated metabolic modifications. Eventually, we briefly address that also mitochondrial oxidative metabolism may induce drug resistance and discuss the therapeutic implications deriving from the fact that the main energy-generating metabolic pathways may be both at the origin of antitumor drug resistance.

Crosstalk Between MYC and lncRNAs in Hematological Malignancies

The human genome project revealed the existence of many thousands of long non-coding RNAs (lncRNAs). These transcripts that are over 200 nucleotides long were soon recognized for their importance in regulating gene expression. However, their poor conservation among species and their still controversial annotation has limited their study to some extent. Moreover, a generally lower expression of lncRNAs as compared to protein coding genes and their enigmatic biochemical mechanisms have impeded progress in the understanding of their biological roles. It is, however, known that lncRNAs engage in various kinds of interactions and can form complexes with other RNAs, with genomic DNA or proteins rendering their functional regulatory network quite complex. It has emerged from recent studies that lncRNAs exert important roles in gene expression that affect many cellular processes underlying development, cellular differentiation, but also the pathogenesis of blood cancers like leukemia and lymphoma. A number of lncRNAs have been found to be regulated by several well-known transcription factors including Myelocytomatosis viral oncogene homolog (MYC). The c-MYC gene is known to be one of the most frequently deregulated oncogenes and a driver for many human cancers. The c-MYC gene is very frequently activated by chromosomal translocations in hematopoietic cancers most prominently in B- or T-cell lymphoma or leukemia and much is already known about its role as a DNA binding transcriptional regulator. Although the understanding of MYC's regulatory role controlling lncRNA expression and how MYC itself is controlled by lncRNA in blood cancers is still at the beginning, an intriguing picture emerges indicating that c-MYC may execute part of its oncogenic function through lncRNAs. Several studies have identified lncRNAs regulating c-MYC expression and c-MYC regulated lncRNAs in different blood cancers and have unveiled new mechanisms how these RNA molecules act. In this review, we give an overview of lncRNAs that have been recognized as critical in the context of activated c-MYC in leukemia and lymphoma, describe their mechanism of action and their effect on transcriptional reprogramming in cancer cells. Finally, we discuss possible ways how an interference with their molecular function could be exploited for new cancer therapies.

MicroRNAs and Their Influence on the ZEB Family: Mechanistic Aspects and Therapeutic Applications in Cancer Therapy

Molecular signaling pathways involved in cancer have been intensively studied due to their crucial role in cancer cell growth and dissemination. Among them, zinc finger E-box binding homeobox-1 (ZEB1) and -2 (ZEB2) are molecules that play vital roles in signaling pathways to ensure the survival of tumor cells, particularly through enhancing cell proliferation, promoting cell migration and invasion, and triggering drug resistance. Importantly, ZEB proteins are regulated by microRNAs (miRs). In this review, we demonstrate the impact that miRs have on cancer therapy, through their targeting of ZEB proteins. MiRs are able to act as onco-suppressor factors and inhibit the malignancy of tumor cells through ZEB1/2 down-regulation. This can lead to an inhibition of epithelial-mesenchymal transition (EMT) mechanism, therefore reducing metastasis. Additionally, miRs are able to inhibit ZEB1/2-mediated drug resistance and immunosuppression. Additionally, we explore the upstream modulators of miRs such as long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs), as these regulators can influence the inhibitory effect of miRs on ZEB proteins and cancer progression.

[Expression of long non-coding RNA linc00467 in childhood acute myeloid leukemia and its role in drug resistance]

OBJECTIVE

To study the expression and function of long non-coding RNA linc00467 in childhood acute myeloid leukemia (AML).

METHODS

Bone marrow samples were collected from 5 children with AML who were diagnosed from May 2016 to June 2018. Normal bone marrow samples based on bone marrow examination were collected from 3 children as controls. Quantitative real-time PCR was used to measure the expression of linc00467 in the two groups. A lentivirus system was used to achieve overexpression of linc00467 in AML cells (HL-60) (linc00467 overexpression group), and empty vector expressing green fluorescent protein (GFP) was transfected into AML cells to establish a GFP control group. A lentivirus system was used to insert an interfering sequence into AML cells (sh-linc00467 interfering group), and a random sequence was inserted to establish an sh-NC control group. Cell proliferation and resistance to doxorubicin were observed for all groups.

RESULTS

Compared with the normal control group, the children with AML had a significant increase in linc00467 (P=0.018). Overexpression and interference with linc00467 expression had no significant effect on cell proliferation. Compared with the GFP control group, the linc00467 overexpression group had a significant increase in the viability of HL-60 cells at the adriamycin concentrations of 0.1, 0.2, 0.3, 0.4, and 0.5 μg/mL (P<0.05). Compared with the sh-NC control group, the sh-linc00467 interfering group had a significant reduction in the viability of HL-60 cells at the adriamycin concentrations of 0.1, 0.2, 0.3, 0.4, and 0.5 μg/mL (P<0.05). Compared with the untreated group, the adriamycin treatment group had a significant increase in the expression of linc00467 in HL-60 cells (P<0.05).

CONCLUSIONS

This study reveals the biological function of linc00467 to promote the resistance to adriamycin in AML, which provides a basis for developing new therapeutic drugs for AML.