Therapeutic Resistance in Acute Myeloid Leukemia: The Role of Non-Coding RNAs

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.

Matrine regulates miR-495-3p/miR-543/PDK1 axis to repress the progression of acute myeloid leukemia via the Wnt/β-catenin pathway

Acute myeloid leukemia (AML) is a commonly hematological malignancy with feature of rapidly increased immature myeloid cells in bone marrow. The anti-tumor activity of matrine has been reported in various cancers. However, the functional role of matrine in AML progression still needs to be studied. Cell growth, apoptosis and cell cycle arrest in AML cells were evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, 5-ethynyl-2'-deoxyuridine (EdU) assay and flow cytometry, respectively. The levels of adenosine triphosphate (ATP)/adenosine diphosphate (ADP) ratio, lactate production and glucose consumption were detected to evaluate glycolysis. Dual-luciferase reporter assay was conducted to determine the relationships between phosphoinositide-dependent kinase 1 (PDK1) and microRNA-495-3p (miR-495-3p)/microRNA-543 (miR-543) in AML cells. The results showed that matrine inhibited cell proliferation, glycolysis, and accelerated cell apoptosis and cell cycle arrest in AML cells. MiR-495-3p/miR-543 was lowly expressed, and PDK1 was highly expressed in AML. Functionally, both miR-495-3p and miR-543 could reverse the effects of matrine on cell proliferation, glycolysis, apoptosis and cell cycle arrest in AML cells. Mechanistically, miR-495-3p/miR-543 directly targeted PDK1, and the inhibition impacts of miR-495-3p/miR-543 on AML progression could be rescued by PDK1 overexpression. Moreover, matrine also could regulate PDK1 expression to suppress AML progression. Besides, matrine modulated miR-495-3p/miR-543/PDK1 axis to inhibit the Wnt/β-catenin pathway. In summary, matrine hampered the progression of AML through targeting miR-495-3p and miR-543 to attenuate PDK1 expression, thereby repressing the Wnt/β-catenin pathway.

Effective Prognostic Model for Therapy Response Prediction in Acute Myeloid Leukemia Patients

Acute myeloid leukemia (AML) is a hematopoietic disorder characterized by the malignant transformation of bone marrow-derived myeloid progenitor cells with extremely short survival. To select the optimal treatment options and predict the response to therapy, the stratification of AML patients into risk groups based on genetic factors along with clinical characteristics is carried out. Despite this thorough approach, the therapy response and disease outcome for a particular patient with AML depends on several patient- and tumor-associated factors. Among these, tumor cell resistance to chemotherapeutic agents represents one of the main obstacles for improving survival outcomes in AML patients. In our study, a new prognostic scale for the risk stratification of AML patients based on the detection of the sensitivity or resistance of tumor cells to chemotherapeutic drugs in vitro as well as MDR1 mRNA/P-glycoprotein expression, tumor origin (primary or secondary), cytogenetic abnormalities, and aberrant immunophenotype was developed. This study included 53 patients diagnosed with AML. Patients who received intensive or non-intensive induction therapy were analyzed separately. Using correlation, ROC, and Cox regression analyses, we show that the risk stratification of AML patients in accordance with the developed prognostic scale correlates well with the response to therapy and represents an independent predictive factor for the overall survival of patients with newly diagnosed AML.

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.

Restoration of miR-23a expression by chidamide sensitizes CML cells to imatinib treatment with concomitant downregulation of CRYAB

MicroRNAs (miRNAs) are involved in various processes from the initiation and development of cancers, including chronic myeloid leukemia (CML). In this report, we aimed to investigate the roles of miR-23a in the regulation of imatinib mesylate (IM) sensitivity in CML cells and the possible mechanisms involved in this process. We demonstrated that the expression of miR-23a was markedly low in bone marrow mononuclear cells from patients in whom IM treatment had failed and imatinib-resistant K562/G01 cells when compared to patients with optimal responses and imatinib-sensitive K562 cells, respectively. Overexpression of miR-23a was shown to induce apoptosis of K562/G01 cells and sensitize these cells to imatinib treatment. With the aid of bioinformatics analysis, we revealed that CRYAB could be a potential downstream effector of miR-23a, contributing to miR-23a-mediated IM resistance. We also observed that the expression of CRYAB was inversely correlated with miR-23a expression in CML cell lines and patient samples. Importantly, chidamide upregulated miR-23a expression and reversed the IM resistance of CML cells. Together, these findings strongly suggest that miR-23a acts as a tumor suppressor by downregulating CRYAB expression. Restoration of miR-23a by chidamide may therefore have a therapeutic effect in controlling the sensitivity of CML cells to imatinib.

How do non-coding RNAs impact treatment regimens currently being used in AML?

not applicable.

MiR-204 suppresses the progression of acute myeloid leukemia through HGF/c-Met pathway

Acute myeloid leukemia (AML) was confirmed to be associated with hematopoietic insufficiency, as well as abnormal proliferation, differentiation or survival of myeloid progenitors. Multiple studies reported that microRNA-204 (miR-204) and Hepatocyte growth factor (HGF) played important roles in types of cancers. However, the potential molecular regulatory mechanism between miR-204 and HGF in AML remains to be further defined. Real-time PCR (RT-PCR) was adopted to detect the expression of miR-204 and HG. Relative protein levels were detected by western blot assay. The viability, cell cycle, apoptosis, migration, and invasion were analyzed by MTT, flow cytometry, and transwell assays. Moreover, the target relationship between miR-204 and HGF was predicted by MiRcode website and confirmed by luciferase reporter, RNA pull-down, and western blot assays. Our data suggested that miR-204 was downregulated in AML serum samples and cells. MiR-204 overexpression repressed cell proliferation, migration, invasion, and induced cell apoptosis in AML cells. HGF was upregulated in AML samples and cells, and HGF knockdown inhibited the malignancy of AML cells. In addition, HGF was directly targeted by miR-204. HGF overexpression reversed the effects of miR-204 mimic on AML cell proliferation, apoptosis, migration, and invasion. Besides, miR-204 regulated the c-Met signaling by targeting HGF, thereby regulating the downstream protein levels related to cell proliferation, apoptosis, migration, and invasion in AML cells. In conclusion, miR-204 could regulate AML progression through regulating the HGF/c-Met pathway.

Regulatory noncoding RNAs: potential biomarkers and therapeutic targets in acute myeloid leukemia

The noncoding RNAs (ncRNA) comprise a substantial segment of the human transcriptome and have emerged as key elements of cellular homeostasis and disease pathogenesis. Dysregulation of these ncRNAs by alterations in the primary RNA motifs and/or aberrant expression levels is relevant in various diseases, especially cancer. The recent research advances indicate that ncRNAs regulate vital oncogenic processes, including hematopoietic cell differentiation, proliferation, apoptosis, migration, and angiogenesis. The ever-expanding role of ncRNAs in cancer progression and metastasis has sparked interest as potential diagnostic and prognostic biomarkers in acute myeloid leukemia. Moreover, advances in antisense oligonucleotide technologies and pharmacologic discoveries of small molecule inhibitors in targeting RNA structures and RNA-protein complexes have opened newer avenues that may help develop the next generation anti-cancer therapeutics. In this review, we have discussed the role of ncRNA in acute myeloid leukemia and their utility as potential biomarkers and therapeutic targets.

CircKDM4C upregulates P53 by sponging hsa-let-7b-5p to induce ferroptosis in acute myeloid leukemia

To investigate the role of circKDM4C in acute myeloid leukemia (AML), the expression of circKDM4C, hsa-let-7b-5p, and P53 was measured by qRT-RCR. AML cell lines(K-562 and HL-60) were transfected correspondingly and investigated for cell proliferation, migration, and invasion abilities by CCK-8, colony formation, transwell, and wound healing assays, respectively. The levels of P53, ACSL4, PTGS2, GPX4, and FTH1 in the K-562, and HL-60 cells were measured by western blotting. Also, circKDM4C mediated regulation of ferroptosis was studied. The Phen Green SK probe and confocal laser scanning microscope were used to assess the cellular iron levels. The reactive oxygen species levels were analyzed by fluorescence-activated cell sorting using the C11-BODIPY probe. Bioinformatics analysis predicted the putative binding sites among circKDM4C, hsa-let-7b-5p, and P53. These were verified using the dual-luciferase reporter assay, RNA pull-down, and RNA immunoprecipitation assays. Finally, in vitro findings were also verified in vivo using the nude mice. CircKDM4C was significantly down-regulated in AML patients. The overexpression of circKDM4C in AML cell lines inhibited the cell proliferation, migration, invasion, and promoted ferroptosis. We found that circKDM4C acts as a sponge of hsa-let-7b-5p and thereby regulates p53 which is a target gene of hsa-let-7b-5p. Also, the expression of circKDM4C and hsa-let-7b-5p are negatively correlated, while circKDM4C and p53 are positively correlated to AML patients. Moreover, we found that circKDM4C induces ferroptosis by sponging hsa-let-7b-5p which upregulates the expression of P53. This work emphasizes the role of circKDM4C in AML patients, which could be explored for the therapeutic role.

Analysis of ceRNA networks and identification of potential drug targets for drug-resistant leukemia cell K562/ADR

Background

Drug resistance is the main obstacle in the treatment of leukemia. As a member of the competitive endogenous RNA (ceRNA) mechanism, underlying roles of lncRNA are rarely reported in drug-resistant leukemia cells.

Methods

The gene expression profiles of lncRNAs and mRNAs in doxorubicin-resistant K562/ADR and sensitive K562 cells were established by RNA sequencing (RNA-seq). Expression of differentially expressed lncRNAs (DElncRNAs) and DEmRNAs was validated by qRT-PCR. The potential biological functions of DElncRNAs targets were identified by GO and KEGG pathway enrichment analyses, and the lncRNA-miRNA-mRNA ceRNA network was further constructed. K562/ADR cells were transfected with CCDC26 and LINC01515 siRNAs to detect the mRNA levels of GLRX5 and DICER1, respectively. The cell survival rate after transfection was detected by CCK-8 assay.

Results

The ceRNA network was composed of 409 lncRNA-miRNA pairs and 306 miRNA-mRNA pairs based on 67 DElncRNAs, 58 DEmiRNAs and 192 DEmRNAs. Knockdown of CCDC26 and LINC01515 increased the sensitivity of K562/ADR cells to doxorubicin and significantly reduced the half-maximal inhibitory concentration (IC₅₀) of doxorubicin. Furthermore, knockdown of GLRX5 and DICER1 increased the sensitivity of K562/ADR cells to doxorubicin and significantly reduced the IC₅₀ of doxorubicin.

Conclusions

The ceRNA regulatory networks may play important roles in drug resistance of leukemia cells. CCDC26/miR-140-5p/GLRX5 and LINC01515/miR-425-5p/DICER1 may be potential targets for drug resistance in K562/ADR cells. This study provides a promising strategy to overcome drug resistance and deepens the understanding of the ceRNA regulatory mechanism related to drug resistance in CML cells.

MiR-15a-5p Confers Chemoresistance in Acute Myeloid Leukemia by Inhibiting Autophagy Induced by Daunorubicin

Anthracyclines remain a cornerstone of induction chemotherapy for acute myeloid leukemia (AML). Refractory or relapsed disease due to chemotherapy resistance is a major obstacle in AML management. MicroRNAs (miRNAs) have been observed to be involved in chemoresistance. We previously observed that miR-15a-5p was overexpressed in a subgroup of chemoresistant cytogenetically normal AML patients compared with chemosensitive patients treated with daunorubicin and cytarabine. MiR-15a-5p overexpression in AML cells reduced apoptosis induced by both drugs in vitro. This study aimed to elucidate the mechanisms by which miR-15a-5p contributes to daunorubicin resistance. We showed that daunorubicin induced autophagy in myeloid cell lines. The inhibition of autophagy reduced cell sensitivity to daunorubicin. The overexpression of miR-15a-5p decreased daunorubicin-induced autophagy. Conversely, the downregulation of miR-15a-5p increased daunorubicin-induced autophagy. We found that miR-15a-5p targeted four genes involved in autophagy, namely ATG9a, ATG14, GABARAPL1 and SMPD1. Daunorubicin increased the expression of these four genes, and miR-15a-5p counteracted this regulation. Inhibition experiments with the four target genes showed the functional effect of miR-15a-5p on autophagy. In summary, our results indicated that miR-15a-5p induces chemoresistance in AML cells through the abrogation of daunorubicin-induced autophagy, suggesting that miR-15a-5p could be a promising therapeutic target for chemoresistant AML patients.

Inhibitors of Chemoresistance Pathways in Combination with Ara-C to Overcome Multidrug Resistance in AML. A Mini Review

Acute myeloid leukemia (AML), the most common type of leukemia in older adults, is a heterogeneous disease that originates from the clonal expansion of undifferentiated hematopoietic progenitor cells. These cells present a remarkable variety of genes and proteins with altered expression and function. Despite significant advances in understanding the molecular panorama of AML and the development of therapies that target mutations, survival has not improved significantly, and the therapy standard is still based on highly toxic chemotherapy, which includes cytarabine (Ara-C) and allogeneic hematopoietic cell transplantation. Approximately 60% of AML patients respond favorably to these treatments and go into complete remission; however, most eventually relapse, develop refractory disease or chemoresistance, and do not survive for more than five years. Therefore, drug resistance that initially occurs in leukemic cells (primary resistance) or that develops during or after treatment (acquired resistance) has become the main obstacle to AML treatment. In this work, the main molecules responsible for generating chemoresistance to Ara-C in AML are discussed, as well as some of the newer strategies to overcome it, such as the inclusion of molecules that can induce synergistic cytotoxicity with Ara-C (MNKI-8e, emodin, metformin and niclosamide), subtoxic concentrations of chemotherapy (PD0332991), and potently antineoplastic treatments that do not damage nonmalignant cells (heteronemin or hydroxyurea + azidothymidine).

Long noncoding RNA DANCR confers cytarabine resistance in acute myeloid leukemia by activating autophagy via the miR-874-3P/ATG16L1 axis

Autophagy is an important mechanism involved in the regulation of acute myeloid leukemia (AML) chemoresistance. The long noncoding RNA (lncRNA) differentiation antagonizing non‐protein coding RNA (DANCR) exhibits oncogenic activity in several types of human cancers, including AML, but it remains unclear whether it regulates autophagy and chemoresistance in AML. We report here that cytarabine (Ara‐C) treatment elevates DANCR expression in human AML cells. In addition, DANCR overexpression confers and its knockdown diminishes Ara‐C resistance in human AML cells, suggesting that DANCR positively regulates AML chemoresistance to Ara‐C. Moreover, DANCR promotes autophagy in Ara‐C‐treated human AML cells and acts as a sponge to decrease miR‐20a‐5p expression, thereby upregulating the expression of ATG16L1, a critical component of the autophagy machinery. Importantly, ATG16L1 silencing abrogates DANCR‐promoted autophagy and markedly restores DANCR‐conferred Ara‐C resistance, suggesting that DANCR promotes MIR‐874‐3P/ATG16L1 axis‐regulated autophagy to confer Ara‐C resistance in human AML cells. Together, this study identifies DANCR as a positive regulator of Ara‐C resistance in human AML cells, suggesting this lncRNA as a potential target for overcoming Ara‐C resistance in AML chemotherapy.

LncRNA BANCR Attenuates the Killing Capacity of Cisplatin on Gastric Cancer Cell Through the ERK1/2 Pathway

Purpose

Chemotherapy-based comprehensive treatments are the most important therapeutic methods for patients with advanced gastric cancer, but chemoresistance often cause treatment failure. Long non-coding RNA (LncRNA) BRAF-activated non-coding RNA (BANCR) has been shown to participate in many biological behaviors of multiple cancers. However, the biological roles of LncRNA BANCR in chemoresistance of gastric cancer remain unclear. Here, we aimed to evaluate the functions of LncRNA BANCR on the therapy of gastric cancer.

Methods

In this study, LncRNA BANCR expression was detected in gastric cancer patient samples and cell lines by quantity polymerase chain reaction (qPCR). Cell proliferation and viability in cisplatin-treated cells were measured using clonogenic survival assay and cell counting kit-8. The levels of ERK1/2 pathway molecules were tested with Western blot. Ly3214996, an inhibitor of ERK signal pathway, was administered to assess the effects of BANCR overexpression on gastric cancer cell with cisplatin-treated resistance. Moreover, the role of BANCR in cisplatin resistance of gastric cancer was validated in xenograft mouse models in vivo.

Results

Our study revealed that LncRNA BANCR expression was also significantly increased in gastric cancer tissues compared with adjacent normal tissues. Furthermore, we found that BANCR overexpression promoted gastric cancer cell resistance to cisplatin in vitro. Ly3214996 treatment abolished the BANCR overexpression-mediated gastric cancer cell cisplatin resistance via regulating the phosphorylation of ERK protein. Knock-down of BANCR significantly delayed tumor growth in xenograft mouse models.

Conclusion

BANCR promoted cisplatin resistance of gastric cancer cells by activating ERK1/2 pathway. Inhibition of BANCR markedly suppressed the growth of gastric cancer cells in vitro as well as in vivo. These results provided a new strategy for gastric cancer therapy via targeting BANCR.

Micro-RNA-125a mediates the effects of hypomethylating agents in chronic myelomonocytic leukemia

BACKGROUND

Chronic myelomonocytic leukemia (CMML) is an aggressive hematopoietic malignancy that arises from hematopoietic stem and progenitor cells (HSPCs). Patients with CMML are frequently treated with epigenetic therapeutic approaches, in particular the hypomethylating agents (HMAs), azacitidine (Aza) and decitabine (Dec). Although HMAs are believed to mediate their efficacy via re-expression of hypermethylated tumor suppressors, knowledge about relevant HMA targets is scarce. As silencing of tumor-suppressive micro-RNAs (miRs) by promoter hypermethylation is a crucial step in malignant transformation, we asked for a role of miRs in HMA efficacy in CMML.

RESULTS

Initially, we performed genome-wide miR-expression profiling in a KrasG12D-induced CMML mouse model. Selected candidates with prominently decreased expression were validated by qPCR in CMML mice and human CMML patients. These experiments revealed the consistent decrease in miR-125a, a miR with previously described tumor-suppressive function in myeloid neoplasias. Furthermore, we show that miR-125a downregulation is caused by hypermethylation of its upstream region and can be reversed by HMA treatment. By employing both lentiviral and CRISPR/Cas9-based miR-125a modification, we demonstrate that HMA-induced miR-125a upregulation indeed contributes to mediating the anti-leukemic effects of these drugs. These data were validated in a clinical context, as miR-125a expression increased after HMA treatment in CMML patients, a phenomenon that was particularly pronounced in cases showing clinical response to these drugs.

CONCLUSIONS

Taken together, we report decreased expression of miR-125a in CMML and delineate its relevance as mediator of HMA efficacy within this neoplasia.

Identification and Analysis of the Blood lncRNA Signature for Liver Cirrhosis and Hepatocellular Carcinoma

As one of the most common malignant tumors, hepatocellular carcinoma (HCC) is the fifth major cause of cancer-associated mortality worldwide. In 90% of cases, HCC develops in the context of liver cirrhosis and chronic hepatitis B virus (HBV) infection is an important etiology for cirrhosis and HCC, accounting for 53% of all HCC cases. To understand the underlying mechanisms of the dynamic chain reactions from normal to HBV infection, from HBV infection to liver cirrhosis, from liver cirrhosis to HCC, we analyzed the blood lncRNA expression profiles from 38 healthy control samples, 45 chronic hepatitis B patients, 46 liver cirrhosis patients, and 46 HCC patients. Advanced machine-learning methods including Monte Carlo feature selection, incremental feature selection (IFS), and support vector machine (SVM) were applied to discover the signature associated with HCC progression and construct the prediction model. One hundred seventy-one key HCC progression-associated lncRNAs were identified and their overall accuracy was 0.823 as evaluated with leave-one-out cross validation (LOOCV). The accuracies of the lncRNA signature for healthy control, chronic hepatitis B, liver cirrhosis, and HCC were 0.895, 0.711, 0.870, and 0.826, respectively. The 171-lncRNA signature is not only useful for early detection and intervention of HCC, but also helpful for understanding the multistage tumorigenic processes of HCC.

miR-15a-5p and miR-21-5p contribute to chemoresistance in cytogenetically normal acute myeloid leukaemia by targeting PDCD4, ARL2 and BTG2

Cytarabine and daunorubicin are old drugs commonly used in the treatment of acute myeloid leukaemia (AML). Refractory or relapsed disease because of chemotherapy resistance is a major issue. microRNAs (miRNAs) were incriminated in resistance. This study aimed to identify miRNAs involved in chemoresistance in AML patients and to define their target genes. We focused on cytogenetically normal AML patients with wild‐type NPM1 without FLT3‐ITD as the treatment of this subset of patients with intermediate‐risk cytogenetics is not well established. We analysed baseline AML samples by small RNA sequencing and compared the profile of chemoresistant to chemosensitive AML patients. Among the miRNAs significantly overexpressed in chemoresistant patients, we revealed miR‐15a‐5p and miR‐21‐5p as miRNAs with a major role in chemoresistance in AML. We showed that miR‐15a‐5p and miR‐21‐5p overexpression decreased apoptosis induced by cytarabine and/or daunorubicin. PDCD4, ARL2 and BTG2 genes were found to be targeted by miR‐15a‐5p, as well as PDCD4 and BTG2 by miR‐21‐5p. Inhibition experiments of the three target genes reproduced the functional effect of both miRNAs on chemosensitivity. Our study demonstrates that miR‐15a‐5p and miR‐21‐5p are overexpressed in a subgroup of chemoresistant AML patients. Both miRNAs induce chemoresistance by targeting three pro‐apoptotic genes PDCD4, ARL2 and BTG2.

Deciphering the Therapeutic Resistance in Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is a clonal hematopoietic disorder characterized by abnormal proliferation, lack of cellular differentiation, and infiltration of bone marrow, peripheral blood, or other organs. Induction failure and in general resistance to chemotherapeutic agents represent a hindrance for improving survival outcomes in AML. Here, we review the latest insights in AML biology concerning refractoriness to therapies with a specific focus on cytarabine and daunorubicin which still represent milestones agents for inducing therapeutic response and disease eradication. However, failure to achieve complete remission in AML is still high especially in elderly patients (40-60% in patients >65 years old). Several lines of basic and clinical research have been employed to improve the achievement of complete remission. These lines of research include molecular targeted therapy and more recently immunotherapy. In terms of molecular targeted therapies, specific attention is given to DNMT3A and TP53 mutant AML by reviewing the mechanisms underlying epigenetic therapies' (e.g., hypomethylating agents) resistance and providing critical points and hints for possible future therapies overcoming AML refractoriness.

Long non-coding RNAs in prostate tumorigenesis and therapy (Review)

Prostate cancer (PCa) is one of the most frequently diagnosed malignancy. Although there have been many advances in PCa diagnosis and therapy, the concrete mechanism remains unknown. Long non-coding RNAs (lncRNAs) are novel biomarkers associated with PCa, and their dysregulated expression is closely associated with risk stratification, diagnosis and carcinogenesis. Accumulating evidence has suggested that lncRNAs play important roles in prostate tumorigenesis through relevant pathways, such as androgen receptor interaction and PI3K/Akt. The present review systematically summarized the potential clinical utility of lncRNAs and provided a novel guide for their function in PCa.

LncRNA SNHG1 contributes to the regulation of acute myeloid leukemia cell growth by modulating miR-489-3p/SOX12/Wnt/β-catenin signaling

The long noncoding RNA (lncRNA) small nucleolar RNA host gene 1 (SNHG1) is a critical regulator for the development and progression of multiple tumors. Yet, the role of SNHG1 in acute myeloid leukemia (AML) is unknown. The present study demonstrated that SNHG1 expression was upregulated in AML. SNHG1 silencing markedly repressed AML cell growth, whereas SNHG1 overexpression had the opposite effect. MicroRNA-489-3p (miR-489-3p) was identified as a SNHG1-targeting miRNA. SNHG1 knockdown increased miR-489-3p expression. Low expression of miR-489-3p was correlated with high expression of SNHG1 in AML tissues. miR-489-3p overexpression restricted AML cell growth, and SRY-related high-mobility-group box 12 (SOX12) was identified as a miR-489-3p-targeting gene. SNHG1 inhibition or miR-489-3p overexpression inactivated Wnt/β-catenin signaling through downregulation of SOX12. SOX12 overexpression partially reversed the SNHG1 knockdown- or miR-489-3p overexpression-mediated effects. Taken together, these data indicate that suppression of SNHG1 downregulates AML cell growth by inactivating SOX12/Wnt/β-catenin signaling via upregulating miR-489-3p.

Role of non-coding RNA networks in leukemia progression, metastasis and drug resistance

Early-stage detection of leukemia is a critical determinant for successful treatment of the disease and can increase the survival rate of leukemia patients. The factors limiting the current screening approaches to leukemia include low sensitivity and specificity, high costs, and a low participation rate. An approach based on novel and innovative biomarkers with high accuracy from peripheral blood offers a comfortable and appealing alternative to patients, potentially leading to a higher participation rate.

Recently, non-coding RNAs due to their involvement in vital oncogenic processes such as differentiation, proliferation, migration, angiogenesis and apoptosis have attracted much attention as potential diagnostic and prognostic biomarkers in leukemia. Emerging lines of evidence have shown that the mutational spectrum and dysregulated expression of non-coding RNA genes are closely associated with the development and progression of various cancers, including leukemia. In this review, we highlight the expression and functional roles of different types of non-coding RNAs in leukemia and discuss their potential clinical applications as diagnostic or prognostic biomarkers and therapeutic targets.

Functional Classification of TP53 Mutations in Acute Myeloid Leukemia

Mutations of the TP53 gene occur in a subset of patients with acute myeloid leukemia (AML) and confer an exceedingly adverse prognosis. However, whether different types of TP53 mutations exert a uniformly poor outcome has not been investigated yet. Here, we addressed this issue by analyzing data of 1537 patients intensively treated within protocols of the German-Austrian AML study group. We classified TP53 mutations depending on their impact on protein structure and according to the evolutionary action (EAp53) score and the relative fitness score (RFS). In 98/1537 (6.4%) patients, 108 TP53 mutations were detected. While the discrimination depending on the protein structure and the EAp53 score did not show a survival difference, patients with low-risk and high-risk AML-specific RFS showed a different overall survival (OS; median, 12.9 versus 5.5 months, p = 0.017) and event-free survival (EFS; median, 7.3 versus 5.2 months, p = 0.054). In multivariable analyses adjusting for age, gender, white blood cell count, cytogenetic risk, type of AML, and TP53 variant allele frequency, these differences were statistically significant for both OS (HR, 2.14; 95% CI, 1.15-4.0; p = 0.017) and EFS (HR, 1.97; 95% CI, 1.06-3.69; p = 0.033). We conclude that the AML-specific RFS is of prognostic value in patients with TP53-mutated AML and a useful tool for therapeutic decision-making.

Increased Expression of Micro-RNA-23a Mediates Chemoresistance to Cytarabine in Acute Myeloid Leukemia

Resistance to chemotherapy is one of the primary obstacles in acute myeloid leukemia (AML) therapy. Micro-RNA-23a (miR-23a) is frequently deregulated in AML and has been linked to chemoresistance in solid cancers. We, therefore, studied its role in chemoresistance to cytarabine (AraC), which forms the backbone of all cytostatic AML treatments. Initially, we assessed AraC sensitivity in three AML cell lines following miR-23a overexpression/knockdown using MTT-cell viability and soft-agar colony-formation assays. Overexpression of miR-23a decreased the sensitivity to AraC, whereas its knockdown had the opposite effect. Analysis of clinical data revealed that high miR-23a expression correlated with relapsed/refractory (R/R) AML disease stages, the leukemic stem cell compartment, as well as with inferior overall survival (OS) and event-free survival (EFS) in AraC-treated patients. Mechanistically, we demonstrate that miR-23a targets and downregulates topoisomerase-2-beta (TOP2B), and that TOP2B knockdown mediates AraC chemoresistance as well. Likewise, low TOP2B expression also correlated with R/R-AML disease stages and inferior EFS/OS. In conclusion, we show that increased expression of miR-23a mediates chemoresistance to AraC in AML and that it correlates with an inferior outcome in AraC-treated AML patients. We further demonstrate that miR-23a causes the downregulation of TOP2B, which is likely to mediate its effects on AraC sensitivity.

Dual biomarkers long non-coding RNA GAS5 and its target, NR3C1, contribute to acute myeloid leukemia

Acute myeloid leukemia (AML) is a complex hematological neoplasm with poor prognosis. At present, overwhelming evidence indicates that different genetic abnormalities are relevant to the pathogenesis of AML. Nevertheless, its exact molecular mechanism is still unknown. Recently, it was reported that lncRNAs play crucial roles in tumorigenesis. But, their role in the molecular pathogenesis of AML has not been extensively explored. GAS5, one of the earliest known lncRNAs, has an essential role in the formation and progression of multiple human cancers. It was recently demonstrated that GAS5 acts as a riborepressor of the Glucocorticoid receptor) GR) and abnormal levels of GAS5 may alter response of hematopoietic cells to glucocorticoids. GAS5 can have interaction with the GR that encoded by NR3C1 gene and inhibit its transcriptional activity. To test whether the genetic variants can be associated with AML risk, we genotyped rs55829688 (T > C) polymorphism in GAS5 and three NR3C1 SNPs namely rs6195, rs41423247 and rs6189/rs6190 in a population of 100 Iranian AML patients and 100 healthy subjects. The analysis of the data showed the frequency of alleles and genotypes of rs55829688 and rs6189/rs6190 polymorphisms did not differ between patients and healthy subjects. But, rs41423247 and rs6195 demonstrated a significant correlation with AML risk. The rs6195 was associated with higher AML susceptibility in the co-dominant (OR = 4.58, 95% CI = 2.11-9.981, P < .0001), dominant (OR = 4.55, 95% CI = 2.155-9.613, P < .0001), and over-dominant (OR = 4.43, 95% CI = 2.042-9.621, P < .0001) models. Also, the rs41423247 polymorphism was associated with higher risk of AML in co-dominant (OR = 2.07, 95% CI = 1.171-4.242, P = .012) and dominant (OR = 2.47, 95% CI = 1.192-5.142, P = .010) models. Furthermore, haplotype analysis (rs41423247, rs6189.rs6190, rs6195, and rs55829688 respectively) demonstrated that GGAT, CGGT, and GGGT haplotypes were associated with higher risk of AML in the studied population (p-values = .007, 0.042 and 0.044, respectively). The present study reveals a possible role for NR3C1 in the pathogenesis of AML.

MN1, FOXP1 and hsa-miR-181a-5p as prognostic markers in acute myeloid leukemia patients treated with intensive induction chemotherapy and autologous stem cell transplantation

BACKGROUND

The meningioma-1 (MN1) gene is expressed in hematopoietic CD34+ cells and down-regulated during myeloid differentiation. MN1 overexpression has been linked to shorter overall and disease free survival in AML patients treated with intensive induction chemotherapy. MN1 overexpression may still be an adverse prognostic marker in AML patients treated with autologous stem cell transplant (auto-SCT) after intensive induction chemotherapy.

METHODS

We retrospectively analysed 54 peripheral blood mononuclear cell (PBMC) samples of AML patients who received auto-SCT at remission (CR1) after intensive induction chemotherapy. MN1 and putative MN1-associated mRNAs, as well as MN1-associated micro-RNAs were assessed at diagnosis in peripheral blood mononuclear cells using Taqman gene expression assays.

RESULTS

AML patients with elevated MN1 or FoxP1 gene expression at diagnosis had a significantly shorter progression-free and overall survival after intensive induction chemo-therapy and auto-SCT. The presence of the favourable risk NPM1 mutation associated with reduced MN1 gene expression. In contrast to MN1 and FOXP1, elevated expression of the putative tumor suppressive micro-RNA hsa-miR-181a-5p was predictive for positive outcome. Correlation analysis of MN1 with myeloid gene expression levels revealed association of MN1 and BMI-1, CD34, FOXP1 and MDM2 expression. Analysis of non-coding RNAs revealed an inverse correlation of MN1 with hsa-miR-20a-5p and hsa-miR-181b-5p expression.

CONCLUSIONS

MN1, FOXP1 and hsa-miR-181a-5p are prognostic markers in AML patients treated with intensive induction chemotherapy and auto-SCT. While MDM2 is a validated therapeutic target, the transcription factors MN1 and FOXP1, and the chromatin modulator BMI-1 are potential therapeutic targets in the treatment of AML. The tumor suppressor hsa-miR-181a-5p may be a candidate miRNA mimic for therapeutic use.

RAF Kinase Inhibitor Protein in Myeloid Leukemogenesis

RAF kinase inhibitor protein (RKIP) is an essential regulator of intracellular signaling. A somatic loss of RKIP expression is a frequent event in solid human cancers, and a role of RKIP as metastasis-suppressor is widely accepted nowadays. Recently, RKIP loss has been described in acute myeloid leukemia (AML) and a series of other myeloid neoplasias (MNs). Functional in vitro and in vivo experiments revealed that RKIP is an essential player within the development of these liquid tumors; however, the respective role of RKIP seems to be complex and multi-faceted. In this review, we will summarize the current knowledge about RKIP in myeloid leukemogenesis. We will initially describe its involvement in physiologic hematopoiesis, and will then proceed to discuss its role in the development of AML and other MNs. Finally, we will discuss potential therapeutic implications arising thereof.

Pt(II) and Pd(II) complexes with a thiazoline derivative ligand: Synthesis, structural characterization, antiproliferative activity and evaluation of pro-apoptotic ability in tumor cell lines HT-29 and U-937

Eluding apoptosis represents the hallmark of tumoral cell behavior. Cisplatin (CisPt) is a very common chemotherapeutic agent to treat cancer by reestablishing apoptotic mechanisms of cell death. However, certain patients acquire resistance to CisPt as well as suffer nephrotoxicity, neurotoxicity, nausea and vomiting. The synthesis of new Pt(II) compounds represents an alternative to CisPt to avoid resistance and undesirable side effects. Pd(II) could be a Pt(II) surrogate given the similarity of coordination chemistry between them, thus widening the spectra of available anticancer drugs. Herein, we have synthesized and characterized two Pt(II) or Pd(II) complexes with TdTn (2-(3,4-dichlorophenyl)imino-N-(2-thiazolin-2-yl)thiazolidine), a thiazoline derivative ligand, with formula [PtCl₂(TdTn)] and [PdCl₂(TdTn)]. The potential anticancer ability was evaluated in human colon adenocarcinoma HT-29 and human histiocytic lymphoma U-937 cell lines. To that aim, U-937 and HT-29 cells were treated with TdTn, [PtCl₂(TdTn)] and [PdCl₂(TdTn)] for 24 h. The microscopy monitoring indicated that TdTn, [PtCl₂(TdTn)] and [PdCl₂(TdTn)] arrested the cell proliferation of U-937 and HT-29 cells with respect to control, in agreement with MTT (3-[4,5-dimethylthiazole-2-yl]-2,5-diphenyltetrazolium bromide) analysis. Moreover, it is noteworthy that the ligand by its own showed antiproliferative effects in both cell lines. [PtCl₂(TdTn)] and [PdCl₂(TdTn)] caused caspase-3 activation in U-937 cells, simultaneously with caspase-9 activation due to complexes; however, in HT-29 caspase-3 activation occurred simultaneously with caspase-8 activation induced by the ligand TdTn. Only metal complexes were able to induce ROS (Reactive Oxygen Species) generation in U-937 cells, but not TdTn. In HT-29 cells neither the metal complexes, nor the ligand induced ROS generation.

Current Concepts of Non-Coding RNAs in the Pathogenesis of Non-Clear Cell Renal Cell Carcinoma

Renal cell carcinoma (RCC) is a relatively rare malignancy of the urinary tract system. RCC is a heterogenous disease in terms of underlying histology and its associated underlying pathobiology, prognosis and treatment schedule. The most prevalent histological RCC subtype is clear-cell renal cell carcinoma (ccRCC), accounting for about 70-80% of all RCCs. Though the pathobiology and treatment schedule for ccRCC are well-established, non-ccRCC subtypes account for 20%-30% of RCC altogether, and their underlying molecular biology and treatment options are poorly defined. The class of non-coding RNAs-molecules that are generally not translated into proteins-are new cancer drivers and suppressors in all types of cancer. Of these, small non-coding microRNAs (miRNAs) contribute to carcinogenesis by regulating posttranscriptional gene silencing. Additionally, a growing body of evidence supports the role of long non-coding RNAs (lncRNAs) in cancer development and progression. Most studies on non-coding RNAs in RCC focus on clear-cell histology, and there is a relatively limited number of studies on non-ccRCC subtypes. The aim of this review is to give an overview of the current knowledge regarding the role of non-coding RNAs (including short and long non-coding RNAs) in non-ccRCC and to highlight possible implications as diagnostic, prognostic and predictive biomarkers.

Long non-coding RNA RPPH1 promotes the proliferation, invasion and migration of human acute myeloid leukemia cells through down-regulating miR-330-5p expression

Multiple studies have revealed that the long non-coding RNA RPPH1 (Ribonuclease P RNA Component H1) is involved in disease progression of solid tumors and neurodegenerative diseases. We aimed to explore the functions of RPPH1 in the pathogenesis of acute myeloid leukemia (AML) and the underlying molecular mechanisms. The expression of RPPH1 was examined in blood samples of AML patients and human AML cell lines including THP-1 and HL-60. The microRNAs (miRNAs) targets of RPPH1 were predicted with online tools and validated with the dual luciferase reporter assay. The malignant behaviors of AML cells with lentivirus medicated knockdown of RPPH1 and/or administration of miR-330-5p inhibitor were assessed. Cell proliferation was determined by the CCK-8 and EdU incorporation methods, and cell invasion and migration were assayed with transwell experiments. The effects of RPPH1 knockdown on in vivo tumor growth were evaluated in nude mice with xenografted THP-1 cells. RPPH1 was expressed in the AML tissues and cell lines and its high expression predicted worse overall survival in AML patients. miR-330-5p was validated to be a direct target of RPPH1. Knockdown of RPPH1 suppressed the proliferation, invasion and migration ability of human AML cells, which was partially reversed by additional administration with miR-330-5p inhibitor. RPPH1 knockdown significantly inhibited the growth of xenografted THP-1 tumor in nude mice. Our work highlights the contributions of RPPH1 in promoting AML progression through targeting miR-330-5p, and suggests that the RPPH1/miR-330-5p axis is a potential target for AML treatments.

Scutellaria barbata D. Don (SBD) protects oxygen glucose deprivation/reperfusion-induced injuries of PC12 cells by up-regulating Nrf2

This study aimed to investigate the potential effect of Scutellaria barbata D. Don (SBD) on oxygen glucose deprivation/reperfusion (OGD/R)-injured PC12 cells. PC12 cells were pretreated with various concentrations of 0.1-0.8 mg/ml SBD for indicated times (12-48 h) and then subjected to OGD/R injury. Cell viability, apoptosis and proliferation were detected using MTT assay, flow cytometry, Ki67 staining and western blot. Oxidative damage was assessed by detecting MDA content, SOD activity and GSH levels. The mitochondrial membrane potential (Δψm) was measured by Rh123 staining. Western blot was performed to assess the expression levels of Nrf2 and PI3K/AKT pathway-related proteins. We found that SBD pretreatment promoted cell viability and proliferation but inhibited apoptosis of OGD/R-injured PC12 cells in dosage- and time-dependent manner. Meanwhile, SBD attenuated oxidative damage and restored mitochondria dysfunction, as evidenced by the reduced MDA content, the increased SOD and GSH levels, and the increased Δψm. Furthermore, SBD induced the expression of Nrf2 in a PI3K/AKT-dependent signalling. Knockdown of Nrf2 blocked the protective effects of SBD on PC12 cells. In conclusion, this study demonstrates that SBD pretreatment protects PC12 cells against OGD/R-induced injury. The potential mechanism may be through up-regulating the expression of Nrf2 in a PI3K/AKT-dependent pathway.

Oxidative phosphorylation inhibition induces anticancerous changes in therapy-resistant-acute myeloid leukemia patient cells

Treatment of acute myeloid leukemia (AML) is still a challenge because of common relapses or resistance to treatment. Therefore, the development of new therapeutic approaches is necessary. Various studies have shown that certain cancers, including some chemoresistant AML subsets, have upregulated oxidative phosphorylation. In this study, we aimed to assess treatment-resistant AML patients' cell modulation using oxidative phosphorylation inhibitors metformin and atovaquone alone and in various combinations with cytosine analog cytarabine and apoptosis inducer venetoclax. Metabolic activity analysis using Agilent Seahorse XF Extracellular Flux Analyzer revealed that peripheral blood mononuclear cells' metabolic state was different among treatment-resistant AML patients. We demonstrated that metformin decreased therapy-resistant-AML cell oxidative phosphorylation ex vivo, cotreatment with cytarabine and venetoclax slightly increased the effect. However, treatment with atovaquone did not have a marked effect in our experiment. Cell treatment had a slight effect on cell proliferation inhibition; combination of metformin, cytarabine, and venetoclax had the strongest effect. Moreover, a slightly higher effect on cell proliferation and cell cycle regulation was demonstrated in the cells with higher initial oxidative phosphorylation rate as demonstrated by gene expression analysis using reverse transcription quantitative polymerase chain reaction (RT-qPCR). Proteomic analysis by liquid chromatography-mass spectrometry demonstrated that chemoresistant AML cell treatment with metformin modulated metabolic pathways, while metformin combination with cytarabine and venetoclax boosted the effect. We suggest that oxidative phosphorylation inhibition is effective but not sufficient for chemoresistant AML treatment. Indeed, it causes anticancerous changes that might have an important additive role in combinatory treatment.

Ailanthone up-regulates miR-449a to restrain acute myeloid leukemia cells growth, migration and invasion

BACKGROUND

Ailanthone (AIL) is a quassinoid isolated from traditional Chinese herbal medicine Ailanthus altissima. The anti-tumor activities of AIL have been reported in various solid tumors. This study aimed to reveal the in vitro effect of AIL on acute myeloid leukemia (AML) cells.

METHODS

The effects of AIL on five AML cell lines (KG1, HL60, U-937, THP-1 and OCI-AML2) as well as myeloid progenitor cells were evaluated by performing CCK-8 assay, flow cytometry, Transwell assay and Western blotting. KG1 and HL60 cells were transfected with miR-449a inhibitor or its negative control, and then were treated by AIL. The above mentioned assays were performed again to study the involvement of miR-449a in AIL's function.

RESULTS

AIL dose-dependently inhibited the viability of AML cells and myeloid progenitor cells. The IC50 value of AIL towards KG1 and HL60 cells was 0.58 and 0.57 μM, respectively. AIL with concentration of 0.5 μM significantly induced the apoptosis of AML cells rather than myeloid progenitor cells. Meanwhile, 0.5 μM AIL significantly reduced migration and invasion of AML cells. miR-449a was highly expressed in response to the treatment of 0.5 μM AIL. Besides this, the anti-tumor activities of AIL in AML cells were attenuated by miR-449a silence. Further, the blockage of Notch and PI3K/AKT signaling pathways induced by AIL was reversed by miR-449a silence.

CONCLUSION

AIL restrained AML cells growth, migration and invasion through up-regulation of miR-449a, and deactivation of Notch and PI3K/AKT signaling pathways.

MALAT1 knockdown inhibits proliferation and enhances cytarabine chemosensitivity by upregulating miR-96 in acute myeloid leukemia cells

Drug resistance remains a major cause of relapse and therapeutic failure in acute myeloid leukemia (AML). Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) has been documented to act as an oncogene and is frequently highly expressed in human cancers including AML. However, the function and molecular mechanism of MALAT1 in regulating cytarabine (Ara-C) resistance of AML are largely unknown. The expressions of MALAT1 and miR-96 in AML patients and healthy controls were examined by qRT-PCR. CCK-8 and flow cytometry assay were performed to assess the proliferation and apoptosis of AML cells. The interaction between MALAT1 and miR-96 was investigated by luciferase reporter assay. We found that MALAT1 was upregulated while miR-96 was downregulated in AML patients compared with healthy controls. A negative correlation between MALAT1 and miR-96 expressions was observed in AML patients. Knockdown of MALAT1 inhibited the proliferation, induced apoptosis, and enhanced Ara-C sensitivity of AML cells. Additionally, MALAT1 suppressed miR-96 expression by acting as a molecular sponge of miR-96 in AML cells. miR-96 downregulation abolished the effects of MALAT1 knockdown on the proliferation, apoptosis, Ara-C sensitivity in AML cells. In conclusion, MALAT1 knockdown inhibited proliferation, promoted apoptosis and enhanced Ara-C sensitivity in AML cells by upregulating miR-96, providing novel insights into the critical role of MALAT1 as a miRNA sponge in AML.

Analyzing the Interactions of mRNAs and ncRNAs to Predict Competing Endogenous RNA Networks in Osteosarcoma Chemo-Resistance

Chemo-resistance is a huge obstacle encountered in the osteosarcoma (OS) treatment. Protein-coding mRNAs, as well as non-coding RNAs (ncRNAs), including long ncRNA (lncRNA), circular RNA (circRNA), and microRNA (miRNA), have been demonstrated to play an essential role in the regulation of cancer biology. However, the comprehensive expression profile and competing endogenous RNA (ceRNA) regulatory network between mRNAs and ncRNAs in the OS chemo-resistance still remain unclear. In the current study, we developed whole-transcriptome sequencing (RNA sequencing [RNA-seq]) in the three paired multi-drug chemo-resistant and chemo-sensitive OS cell lines to comprehensively identify differentially expressed lncRNAs, circRNAs, miRNAs, and mRNAs. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed for mRNAs with significantly different expression. Then the ceRNA networks combining lncRNAs, circRNAs, miRNAs, and mRNAs were predicted and constructed on the basis of the authoritative miRanda and TargetScan databases combined with the widely accepted vital drug resistance-related genes and signal transduction pathways. In addition, two constructed ceRNA regulatory pathways, lncRNAMEG3/hsa-miR-200b-3p/AKT2 and hsa_circ_0001258/hsa-miR-744-3p/GSTM2, were randomly selected and validated by real-time qPCR, RNA immunoprecipitation (RIP), RNA pull-down assay, and dual luciferase reporter gene system. Taken together, our findings may provide new evidence for the underlying mechanism of OS chemo-resistance and uncover some novel targets for reversing it.

miR-9 Enhances the Chemosensitivity of AML Cells to Daunorubicin by Targeting the EIF5A2/MCL-1 Axis

Daunorubicin (Dnr) is at the forefront of acute myeloid leukemia (AML) therapy, but drug resistance poses a major threat to treatment success. MicroRNA (miR)-9 has been shown to have a pivotal role in AML development. However, little is known about the role of miR-9 in Dnr resistance in AML. We explored the potential role of miR-9 in Dnr resistance in AML cells and its mechanism of action. AML cell lines with high half-maximal inhibitory concentration to Dnr in vivo had significantly low miR-9 expression. miR-9 overexpresssion sensitized AML cells to Dnr, inhibited cell proliferation, and enhanced the ability of Dnr to induce apoptosis; miR-9 knockdown had the opposite effects. Mechanistic studies demonstrated that eukaryotic translation initiation factor 5A-2 (EIF5A2) was a putative target of miR-9, which was inversely correlated with the expression and role of miR-9 in AML cells. miR-9 improved the anti-tumor effects of Dnr by inhibiting myeloid cell leukemia-1 (MCL-1) expression, which was dependent on downregulation of EIF5A2 expression. These results suggest that miR-9 has an essential role in Dnr resistance in AML cells through inhibition of the EIF5A2/MCL-1 axis in AML cells. Our data highlight the potential application of miR-9 in chemotherapy for AML patients.

LncRNA HOTAIRM1 is involved in the progression of acute myeloid leukemia through targeting miR-148b

LncRNAs have been shown to be involved in the biological and pathological processes of acute myeloid leukemia (AML). Hox antisense intergenic RNA myeloid 1 (HOTAIRM1) was reported to be highly expressed in AML. However, the detailed role and molecular mechanism of HOTAIRM1 in AML pathogenesis remain undefined. In the present study, HOTAIRM1 and miR-148b expressions in AML patients and healthy controls were detected by qRT-PCR. Cell proliferation and apoptosis were evaluated by CCK-8 and flow cytometry assays, respectively. The regulatory interaction between HOTAIRM1 and miR-148b was explored by bioinformatics analysis using starBase v3.0 software and The Cancer Genome Atlas (TCGA) AML dataset. We found that the miR-148/miR-152 family members including miR-148a, miR-148b, and miR-152 were predicted to be potential targets of HOTAIRM1. HOTAIRM1 expression was negatively correlated with miR-148b expression but had no correlation with miR-148a/miR-152 expressions in AML samples from the TCGA dataset. HOTAIRM1 expression was higher while miR-148b expression was lower in AML patients than in healthy controls. A negative correlation between HOTAIRM1 and miR-148b in AML patients was observed. HOTAIRM1 silencing and miR-148b overexpression both suppressed cell proliferation and induced apoptosis in AML cells. miR-148b was identified as a target of HOTAIRM1 in AML cells. Moreover, HOTAIRM1 knockdown inhibited proliferation and induced apoptosis in AML cells by negatively regulating miR-148b. In summary, HOTAIRM1 was involved in the progression of AML through targeting miR-148b, shedding light on the biological function and molecular mechanism of HOTAIRM1 in AML.

LncRNAs have been shown to be involved in the biological and pathological processes of acute myeloid leukemia (AML).

miR‑1271‑5p inhibits cell proliferation and induces apoptosis in acute myeloid leukemia by targeting ZIC2

MicroRNAs (miRNAs) have been demonstrated to regulate the progression of numerous types of cancer, including acute myeloid leukemia (AML). Previous studies demonstrated that miR‑1271‑5p functions as a tumor suppressor; however, the roles of miR‑1271‑5p in AML remain unknown. In the present study, miR‑1271‑5p was significantly downregulated in AML tissues compared with normal tissues by reverse transcription‑quantitative polymerase chain reaction analysis. Furthermore, the expression levels of miR‑1271‑5p in patients with AML may function as a prognostic marker. In addition, overexpression of miR‑1271‑5p significantly suppressed the proliferation and induced apoptosis of AML cells by Cell Counting kit‑8 and fluorescence activated cell sorter assays; miR‑1271‑5p downregulation exhibited opposing effects. Additionally, transcription factor ZIC2 may be a direct target of miR‑1271‑5p in AML cells, which was demonstrated by a luciferase reporter assay and RNA pulldown assay. Overexpression of miR‑1271‑5p significantly reduced the mRNA and protein expression levels of ZIC2 in AML193 and OCI‑AML2 cells by reverse transcription‑quantitative polymerase chain reaction analysis and western blotting. Furthermore, an inverse correlation between miR‑1271‑5p and ZIC2 expression in AML samples was observed. In summary, ZIC2 was upregulated in AML tissues, and restoration of ZIC2 expression was able to promote the proliferation and reduce the apoptosis of AML cells transfected with miR‑1271‑5p mimics. The results of the present study demonstrated that miR‑1271‑5p inhibited the progression of AML by targeting ZIC2.

Knockdown of Long Noncoding RNA Plasmacytoma Variant Translocation 1 with Antisense Locked Nucleic Acid GapmeRs Exerts Tumor-Suppressive Functions in Human Acute Erythroleukemia Cells Through Downregulation of C-MYC Expression

Objective: Acute erythroleukemia (AEL) is a subtype of acute myeloid leukemia (AML), with no specific treatment. Up- or downregulation of long noncoding RNAs (lncRNAs) is strongly associated with the formation and progression of many malignancies. Plasmacytoma variant translocation 1 (PVT1) is a significantly upregulated lncRNA in AML. Antisense locked nucleic acid (LNA) GapmeRs oligonucleotides are the novel tools for targeting lncRNAs. The purpose of the current study was to investigate the functional role of PVT1 antisense LNA GapmeRs on AEL cell line (KG-1). Materials and Methods: AEL cells were transfected with PVT1 antisense LNA GapmeRs at three different time points. Quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) was accomplished to evaluate the PVT1 expression by PVT1 antisense LNA GapmeRs. The viability was evaluated by MTT (3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyl tetrazolium bromide) assay, and the apoptosis and necrosis were assessed by Annexin V/propidium iodide staining assay. The C-MYC expression level, the target gene of PVT1, was also quantified by qRT-PCR. Results: The results indicated that PVT1 inhibition could significantly decrease the viability of AEL cells, due to induction of apoptosis and necrosis, probably through the downregulation of C-MYC. Conclusions: Their findings suggest that the inhibition of lncRNA PVT1 could serve as a novel approach for controlling the proliferation of AEL cells and could open up a path for treatment of AEL.

Knockdown of LncRNA-UCA1 suppresses chemoresistance of pediatric AML by inhibiting glycolysis through the microRNA-125a/hexokinase 2 pathway

Dysregulation of lncRNAs is implicated in chemoresistance in varieties of tumor including acute myeloid leukemia (AML). LncRNA urothelial carcinoma-associated 1 (UCA1) was reported to play an oncogenic role in AML. However, whether UCA1 was involved in chemoresistance in pediatric AML remains unclear. UCA1 expression in AML patients after adriamycin (ADR)-based chemotherapy and ADR-resistant AML cells was examined by qRT-PCR. The effects of UCA1 on the cytotoxicity of ADR and glycolysis were evaluated by MTT assay and measuring the glucose consumption and lactate production in HL60 and HL60/ADR cells, repectively. The protein levels of hypoxia-inducible factor 1α (HIF-1α) and hexokinase 2 (HK2) were determined by Western blot. Luciferase reporter assay and RNA immunoprecipitation (RIP) assay were used to confirm the relationships between UCA1, HK2, and miR-125a. We found that UCA1 expression was upregulated following ADR-based chemotherapy. Knockdown of UCA1 increased the cytotoxic effect of ADR and inhibited HIF-1α-dependent glycolysis in ADR-resistant AML cells. Additionally, UCA1 functioned as a ceRNA of miR-125a by directly binding to miR-125a. HK2, a target of miR-125a, was positively regulated by UCA1 in HL60 and HL60/ADR cells. More notably, UCA1 overexpression overturned miR-125-mediated inhibition on HIF-1α-dependent glycolysis in HL60 and HL60/ADR cells. Furthermore, 2-deoxy-glucose (2-DG) exposure inhibited HIF-1α-dependent glycolysis, and attenuated UCA1-induced increase of chemoresistance in HL60 and HL60/ADR cells. We conclude that knockdown of UCA1 plays a positive role in overcoming the chemoresistance of pediatric AML, through suppressing glycolysis by the miR-125a/HK2 pathway, contributing to a better understanding of the molecular mechanism of chemoresistance in AML.

MicroRNA-155 expression and function in AML: An evolving paradigm

Acute myeloid leukemia (AML) arises when immature myeloid blast cells acquire multiple, recurrent genetic and epigenetic changes that result in dysregulated proliferation. Acute leukemia is the most common form of pediatric cancer, with AML accounting for ~20% of all leukemias in children. The genomic aberrations that drive AML inhibit myeloid differentiation and activate signal transduction pathways that drive proliferation. MicroRNAs, a class of small (~22 nucleotide) noncoding RNAs that posttranscriptionally suppress the expression of specifically targeted transcripts, are also frequently dysregulated in AML, which may prove useful for the purposes of disease classification, prognosis, and future therapeutic approaches. MicroRNA expression profiles are associated with patient prognosis and responses to standard chemotherapy, including predicting therapy resistance in AML. miR-155 is the primary focus of this review because it has been repeatedly associated with poorer survival across multiple cohorts of adult and pediatric AML. We discuss some novel features of miR-155 expression in AML, in particular how the levels of expression can critically influence function. Understanding the role of microRNAs in AML and the ways in which microRNA expression influences AML biology is one means to develop novel and more targeted therapies.

SOX9/miR-130a/CTR1 axis modulates DDP-resistance of cervical cancer cell

Cisplatin (DDP) -based chemotherapy is a standard strategy for cervical cancer, while chemoresistance remains a huge challenge. Copper transporter protein 1 (CTR1), a copper influx transporter required for high affinity copper (probably reduced Cu I) transport into the cell, reportedly promotes a significant fraction of DDP internalization in tumor cells. In the present study, we evaluated the function of CTR1 in the cell proliferation of cervical cancer upon DDP treatment. MicroRNAs (miRNAs) have been regarded as essential regulators of cell proliferation, apoptosis, migration, as well as chemoresistance. By using online tools, we screened for candidate miRNAs potentially regulate CTR1, among which miR-130a has been proved to promote cervical cancer cell proliferation through targeting PTEN in our previous study. In the present study, we investigated the role of miR-130a in cervical cancer chemoresistance to DDP, and confirmed the binding of miR-130a to CTR1. SOX9 also reportedly act on cancer chemoresistance. In the present study, we revealed that SOX9 inversely regulated miR-130a through direct targeting the promoter of miR-130a. Consistent with previous studies, SOX9 could affect cervical cancer chemoresistance to DDP. Taken together, we demonstrated a SOX9/miR-130a/CTR1 axis which modulated the chemoresistance of cervical cancer cell to DDP, and provided promising targets for dealing with the chemoresistance of cervical cancer.

MicroRNAs as New Biomarkers for Diagnosis and Prognosis, and as Potential Therapeutic Targets in Acute Myeloid Leukemia

Acute myeloid leukemias (AML) are clonal disorders of hematopoietic progenitor cells which are characterized by relevant heterogeneity in terms of phenotypic, genotypic, and clinical features. Among the genetic aberrations that control disease development there are microRNAs (miRNAs). miRNAs are small non-coding RNAs that regulate, at post-transcriptional level, translation and stability of mRNAs. It is now established that deregulated miRNA expression is a prominent feature in AML. Functional studies have shown that miRNAs play an important role in AML pathogenesis and miRNA expression signatures are associated with chemotherapy response and clinical outcome. In this review we summarized miRNA signature in AML with different cytogenetic, molecular and clinical characteristics. Moreover, we reviewed the miRNA regulatory network in AML pathogenesis and we discussed the potential use of cellular and circulating miRNAs as biomarkers for diagnosis and prognosis and as therapeutic targets.

MiR-182-5p regulates BCL2L12 and BCL2 expression in acute myeloid leukemia as a potential therapeutic target

The importance of microRNAs (miRNAs) are shown during various cancers including acute myeloid leukemia (AML). MiR-182-5p functions as an oncogene or a potential suppressive miRNA in cancers, but its expression and function in AML is unknown. The purpose is to investigate the roles of miR-182-5p in AML in this study. MiR-182-5p was examined in the blood samples of AML and it was found that miR-182-5p expression levels were higher in AML tissues than it in their normal controls, so did in the AML cells. BCL2L12 and BCL2 were predicted as target genes of miR-182-5p and verified using luciferase reporter assay. BCL2L12 and BCL2 mRNA and protein levels were up-regulated in the AML cells with miR-182-5p inhibition. Cellular function of miR-182-5p indicated that miR-182-5p suppression in AML cells could decrease cell proliferation and reverse cisplatin (DDP) resistance via targeting BCL2L12 and BCL2 expression. Inhibition of miR-182-5p promoted AML cell apoptosis by targeting BCL2 or BCL2L12. The study demonstrates that high levels of miR-182-5p in AML promotes cell proliferation and suppresses cell apoptosis by targeting BCL2L12 and BCL2.

Long Noncoding RNA miR210HG Sponges miR-503 to Facilitate Osteosarcoma Cell Invasion and Metastasis

Long noncoding RNAs (lncRNAs) have been illustrated to function as important regulator in carcinogenesis and cancer progression. However, roles of lncRNA miR210HG (miR210 host gene) in osteosarcoma remain unclear. In this study, miR210HG expression level was significantly upregulated in 55 cases of osteosarcoma tissue samples compared to adjacent normal tissue. Besides, the aberrantly enhanced miR210HG expression predicted poor prognosis and lower survival rate. In vitro, miR210HG knockdown suppressed the osteosarcoma cell proliferation, invasion, and epithelial-mesenchymal transition-related marker (N-cadherin and vimentin) expression. In vivo, miR210HG silencing decreased the tumor growth. miR-503 was verified to be the target miRNA of miR210HG using bioinformatics online program and luciferase assay. Furthermore, miR-503 could reverse the role of miR210HG on osteosarcoma cells. In conclusion, our study indicates that miR210HG sponges miR-503 to facilitate osteosarcoma cell invasion and metastasis, revealing the oncogenic role of miR210HG on osteosarcoma cells.

Knockdown of long non-coding RNA MALAT1 inhibits growth and motility of human hepatoma cells via modulation of miR-195

The metastasis-associated lung adenocarcinoma transcription 1 (Malat1) is a long non-coding RNA (lncRNA), exerts oncogenic role in multiple cancers, including hepatocellular carcinoma (HCC). This study was aimed to investigate its posttranscriptional regulation in HCC cells. RT-PCR was performed to monitor the expression levels of Malat1 in normal liver and HCC cell lines. The expression of Malat1, microRNA (miR)-195, and epidermal growth factor receptor (EGFR) in HepG2 and MHCC97 cells was respectively or synchronously altered by transfection. Then the changes in cell viability, apoptotic cell rate, cell cycle distribution, migration, and invasion were respectively assessed. As a result, we found that Malat1 was highly expressed in HCC cell lines when compared to normal liver cells. Malat1 silence suppressed HCC cells viability, migration and invasion, induced apoptosis, and arrested more cells in G0/G1 phase. Malat1 acted as a circular endogenous RNA (ceRNA) for miR-195. Malat1 silence could not suppress HCC cell growth and motility when miR-195 was knocked down. EGFR was a direct target of miR-195. miR-195 overexpression could not suppress HCC cell growth and motility when the 3'UTR site of EGFR was overexpressed. Furthermore, Malat1 silence blocked the activation of PI3K/AKT and JAK/STAT pathways, while EGFR overexpression activated them. Our study demonstrates Malat1-miR-195-EGFR axis plays a critical role in HCC cells which provided a better understanding of Malat1 in HCC.