Changes in the expression of miR-381 and miR-495 are inversely associated with the expression of the MDR1 gene and development of multi-drug resistance

MiRNAs: main players of cancer drug resistance target ABC transporters

Chemotherapy remains the cornerstone of cancer treatment; however, its efficacy is frequently compromised by the development of chemoresistance. Multidrug resistance (MDR), characterized by the refractoriness of cancer cells to a wide array of chemotherapeutic agents, presents a significant barrier to achieving successful and sustained cancer remission. One critical factor contributing to this chemoresistance is the overexpression of ATP-binding cassette (ABC) transporters. Furthermore, additional mechanisms, such as the malfunctioning of apoptosis, alterations in DNA repair systems, and resistance mechanisms inherent to cancer stem cells, exacerbate the issue. Intriguingly, microRNAs (miRNAs) have demonstrated potential in modulating chemoresistance by specifically targeting ABC transporters, thereby offering promising new avenues for overcoming drug resistance. This narrative review aims to elucidate the molecular underpinnings of drug resistance, with a particular focus on the roles of ABC transporters and the regulatory influence of miRNAs on these transporters.

Stratification of acute myocardial and endothelial cell injury, salvage index and final infarct size by systematic microRNA profiling in acute ST-elevation myocardial infarction

AIM

Acute injury and subsequent remodelling responses to ST-segment elevation myocardial infarction (STEMI) are major determinants of clinical outcome. Current imaging and plasma biomarkers provide delayed readouts of myocardial injury and recovery. Here, we sought to systematically characterize all microRNAs (miRs) released during the acute phase of STEMI and relate miR release to magnetic resonance imaging (MRI) findings to predict acute and late responses to STEMI, from a single early blood sample.

METHODS AND RESULTS

miRs were quantified in blood samples obtained from patients after primary PCI (PPCI) for STEMI. Cardiac MRI (cMRI) was performed to quantify myocardial edema, infarct size and salvage index. Regression models were constructed to predict these outcomes measures, which were then tested with a validation cohort. Transcoronary miR release was quantified from paired measurements of coronary artery and coronary sinus samples. A cell culture model was used to identify endothelial cell-derived miRs.A total of 72 patients undergoing PPCI for acute STEMI underwent miR analysis and cMRI. About >200 miRs were detectable in plasma after STEMI, from which 128 miRs were selected for quantification in all patients. Known myocardial miRs demonstrated a linear correlation with troponin release, and these increased across the transcoronary gradient. We identified novel miRs associated with microvascular injury and myocardial salvage. Regression models were constructed using a training cohort, then tested in a validation cohort, and predicted myocardial oedema, infarct size and salvage index.

CONCLUSION

Analysis of miR release after STEMI identifies biomarkers that predict both acute and late outcomes after STEMI. A novel miR-based biomarker score enables the estimation of area at risk, late infarct size and salvage index from a single blood sample 6 hours after PPCI, providing a simple and rapid alternative to serial cMRI characterization of STEMI outcome.

Doxorubicin and other anthracyclines in cancers: Activity, chemoresistance and its overcoming

Anthracyclines have been important and effective treatments against a number of cancers since their discovery. However, their use in therapy has been complicated by severe side effects and toxicity that occur during or after treatment, including cardiotoxicity. The mode of action of anthracyclines is complex, with several mechanisms proposed. It is possible that their high toxicity is due to the large set of processes involved in anthracycline action. The development of resistance is a major barrier to successful treatment when using anthracyclines. This resistance is based on a series of mechanisms that have been studied and addressed in recent years. This work provides an overview of the anthracyclines used in cancer therapy. It discusses their mechanisms of activity, toxicity, and chemoresistance, as well as the approaches used to improve their activity, decrease their toxicity, and overcome resistance.

miR-495-3p sensitizes BCR-ABL1-expressing leukemic cells to tyrosine kinase inhibitors by targeting multidrug resistance 1 gene in T315I mutated cells

Chronic myeloid leukemia (CML) is a clonal hematopoietic malignancy driven by the BCR-ABL1 fusion oncoprotein. The development of tyrosine kinase inhibitors (TKIs) has deeply increased long-term survival of CML patients. Nonetheless, one patient out of four will switch TKI off owing either to drug intolerance or resistance partly due to amplification or mutations of BCR-ABL1 oncogene and alteration in ATP-binding cassette (ABC) transporters. Increasing evidence suggests the involvement of the microRNA miR-495-3p in cancer-associated chemoresistance through multidrug resistance 1 (MDR1) gene, which encodes an ATP-dependent efflux pump. Our study aimed at investigating the potential role of miR-495-3p in CML TKI chemo-sensitivity and determining the underlying molecular circuitry involved. We first observed that miR-495-3p expression was lower in BCR-ABL1-expressing cellular models in vitro. Notably, loss-of-function experiments showed increased proliferation associated with a decreased number of nondividing cells (G0/G1) and resistance to Imatinib. Conversely, our data showed that miR-495-3p overexpression hindered leukemic cell growth and TKI resistance in Imatinib-resistant T315I-mutant cells, as well as drug efflux activity through MDR1 regulation. Further investigating the role of miR-495-3p in CML patients, we found that predicted miR-495-3p targets were upregulated in patients in blast crisis that were involved in protein phosphorylation and associated with the worst prognosis. Taken together, our results demonstrate that downregulation of miR-495-3p expression is important in the malignant phenotype of CML and TKI resistance mechanisms and could be a useful biomarker and a potential therapeutic target to eradicate CML.

MicroRNA as a Potential Therapeutic Molecule in Cancer

Small noncoding RNAs, as post-translational regulators of many target genes, are not only markers of neoplastic disease initiation and progression, but also markers of response to anticancer therapy. Hundreds of miRNAs have been identified as biomarkers of drug resistance, and many have demonstrated the potential to sensitize cancer cells to therapy. Their properties of modulating the response of cells to therapy have made them a promising target for overcoming drug resistance. Several methods have been developed for the delivery of miRNAs to cancer cells, including introducing synthetic miRNA mimics, DNA plasmids containing miRNAs, and small molecules that epigenetically alter endogenous miRNA expression. The results of studies in animal models and preclinical studies for solid cancers and hematological malignancies have confirmed the effectiveness of treatment protocols using microRNA. Nevertheless, the use of miRNAs in anticancer therapy is not without limitations, including the development of a stable nanoconstruct, delivery method choices, and biodistribution. The aim of this review was to summarize the role of miRNAs in cancer treatment and to present new therapeutic concepts for these molecules. Supporting anticancer therapy with microRNA molecules has been verified in numerous clinical trials, which shows great potential in the treatment of cancer.

The Roles of microRNAs in Cancer Multidrug Resistance

Simple Summary

The resistance of neoplastic cells to multiple drugs is a serious problem in cancer chemotherapy. The molecular causes of multidrug resistance in cancer are largely known, but less is known about the mechanisms by which cells deliver phenotypic changes that resist the attack of anticancer drugs. The findings of RNA interference based on microRNAs represented a breakthrough in biology and pointed to the possibility of sensitive and targeted regulation of gene expression at the post-transcriptional level. Such regulation is also involved in the development of multidrug resistance in cancer. The aim of the current paper is to summarize the available knowledge on the role of microRNAs in resistance to multiple cancer drugs.

Abstract

Cancer chemotherapy may induce a multidrug resistance (MDR) phenotype. The development of MDR is based on various molecular causes, of which the following are very common: induction of ABC transporter expression; induction/activation of drug-metabolizing enzymes; alteration of the expression/function of apoptosis-related proteins; changes in cell cycle checkpoints; elevated DNA repair mechanisms. Although these mechanisms of MDR are well described, information on their molecular interaction in overall multidrug resistance is still lacking. MicroRNA (miRNA) expression and subsequent RNA interference are candidates that could be important players in the interplay of MDR mechanisms. The regulation of post-transcriptional processes in the proteosynthetic pathway is considered to be a major function of miRNAs. Due to their complementarity, they are able to bind to target mRNAs, which prevents the mRNAs from interacting effectively with the ribosome, and subsequent degradation of the mRNAs can occur. The aim of this paper is to provide an overview of the possible role of miRNAs in the molecular mechanisms that lead to MDR. The possibility of considering miRNAs as either specific effectors or interesting targets for cancer therapy is also analyzed.

MicroRNA-381 in human cancer: Its involvement in tumour biology and clinical applications potential

MicroRNAs (miRNAs) are small non‐coding RNAs that regulate gene expression at the post‐transcriptional level. MiRNAs are involved in the development and progression of a wide range of cancers. Among such cancer‐associated miRNAs, miR‐381 has been a major focus of research. The expression pattern and role of miR‐381 vary among different cancer types. MiR‐381 modulates various cellular behaviours in cancer, including proliferation, apoptosis, cell cycle progression, migration and invasion. MiR‐381 is also involved in angiogenesis and lymphangiogenesis, as well as in the resistance to chemotherapy and radiotherapy. MiR‐381 itself is regulated by several factors, such as long noncoding RNAs, circular RNAs and cytokines. Aberrant expression of miR‐381 in blood samples indicates that it can be used as a diagnostic marker in cancer. Tissue miR‐381 expression may serve as a prognostic factor for the clinicopathological characteristics of cancers and survival of patients. Metformin and icaritin regulate miR‐381 expression and present anticancer properties. This review comprehensively summarizes the effect of miR‐381 on tumour biological behaviours, as well as the clinical application potential of miR‐381 for the treatment of cancer.

LncRNA UCA1 mediates Cetuximab resistance in Colorectal Cancer via the MiR-495 and HGF/c-MET Pathways

Background: Cetuximab is one of the most widely used monoclonal antibodies to treat patients with RAS/BRAF wild-type metastatic colorectal cancer (mCRC). Unfortunately, cetuximab resistance often occurs during targeted therapy. However, the underlying epigenetic mechanisms remain unclear. Our previous study demonstrated that the exosomal transfer of urothelial carcinoma-associated 1 (UCA1) confers cetuximab resistance to CRC cells. The goal of this study was to elucidate the detailed role of UCA1 in cetuximab resistance in CRC and the underlying molecular mechanism.

Methods:In vitro and in vivo functional studies were performed to assess the role of UCA1 in cetuximab resistance in CRC cell lines and xenograft models. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was used to examine UCA1 localization and expression. Bioinformatics analysis was performed to predict the potential mechanism of UCA1, which was further validated by the dual-luciferase reporter assay and the RNA immunoprecipitation (RIP) assay. Cells treated with indicators were subjected to Cell Counting Kit-8 (CCK-8) and western blotting to investigate the role of hepatocyte growth factor (HGF)/c-mesenchymal-epithelial transition (c-MET) signalling in UCA1-mediated cetuximab resistance.

Results: We showed that UCA1 decreased CRC cell sensitivity to cetuximab by suppressing apoptosis. Mechanistic studies revealed that UCA1 promoted cetuximab resistance by competitively binding miR-495 to facilitate HGF and c-MET expression in CRC cells. Moreover, HGF was shown to attenuate the cetuximab-induced inhibition of cell proliferation by activating the HGF/c-MET pathway in CRC cells.

Conclusion: We provide the first evidence of a UCA1-miR-495-HGF/c-MET regulatory network involved in cetuximab resistance in CRC. Therefore, UCA1 has potential as a predictor and therapeutic target for cetuximab resistance.

Role of miRNA-495 and NRXN-1 and CNTN-1 mRNA Expression and Its Prognostic Importance in Breast Cancer Patients

Breast cancer is a heterogeneous disease in which genetic factors are involved in disease worsening and higher mortality. Epidemiological and clinical research revealed that breast cancer incidence continues to rise. 100 histopathologically confirmed untreated newly diagnosed cases of invasive ductal carcinoma (IDC) of breast and 100 healthy subjects were involved and blood samples were collected in non-EDTA plain vials. Serum was separated by centrifugation, total RNA was extracted from serum, and cDNA synthesis was done to study the miRNA-495 and neurexin-1 (NRXN-1) and contactin 1 (CNTN-1) mRNA expression by QRT-PCR. The expression levels of miRNA-495, NRXN-1, and CNTN-1 were expressed in fold change. The present study observed decreased relative miRNA-495 expression (0.07-fold) while an increase in NRXN-1 (11.61-fold) and CNTN-1 (4.92-fold) was observed among breast cancer patients compared to healthy controls. A significant difference was observed in miRNA-495 expression with menopausal status (p=0.0001) and TNM stages (p=0.02). It was observed that NRXN-1 expression was significantly associated with menopausal status (p=0.03), lymph node involvement (p < 0.0001), estrogen receptor (ER) status (p=0.03), progesterone receptor (PR) status (p=0.005), TNM stages (p < 0.0001), and distant metastases (p < 0.0001). CNTN-1 expression was also found to be associated with lymph node involvement (p=0.01), PR status (p=0.03), HER2 status (p=0.04), TNM stages (p < 0.0001), and distant metastases (p < 0.0001). ROC suggested that NRXN-1 and CNTN-1 could be the important predictive marker for disease advancement and distant organ metastases. The study concluded that the decreased expression of miR-495 observed in breast cancer patients showed a negative correlation with NRXN-1 while the increased expression of NRXN-1 and CNTN-1 was linked with disease advancement and distant metastases and could be the important predictive marker for breast cancer patients.

The related miRNAs involved in doxorubicin resistance or sensitivity of various cancers: an update

Doxorubicin (DOX) is an effective chemotherapy agent against a wide variety of tumors. However, intrinsic or acquired resistance diminishes the sensitivity of cancer cells to DOX, which leads to a cancer relapse and treatment failure. Resolutions to this challenge includes identification of the molecular pathways underlying DOX sensitivity/resistance and the development of innovative techniques to boost DOX sensitivity. DOX is classified as a Topoisomerase II poison, which is cytotoxic to rapidly dividing tumor cells. Molecular mechanisms responsible for DOX resistance include effective DNA repair and resumption of cell proliferation, deregulated development of cancer stem cell and epithelial to mesenchymal transition, and modulation of programmed cell death. MicroRNAs (miRNAs) have been shown to potentiate the reversal of DOX resistance as they have gene-specific regulatory functions in DOX-responsive molecular pathways. Identifying the dysregulation patterns of miRNAs for specific tumors following treatment with DOX facilitates the development of novel combination therapies, such as nanoparticles harboring miRNA or miRNA inhibitors to eventually prevent DOX-induced chemoresistance. In this article, we summarize recent findings on the role of miRNAs underlying DOX sensitivity/resistance molecular pathways. Also, we provide latest strategies for utilizing deregulated miRNA patterns as biomarkers or miRNAs as tools to overcome chemoresistance and enhance patient's response to DOX treatment.

miRNAs mediated drug resistance in hematological malignancies

Despite improvements in the therapeutic approaches for hematological malignancies in the last decades, refractory disease still occurs, and cancer drug resistance still remains a major hurdle in the clinical management of these cancer patients. The investigation of this problem has been extensive and different mechanism and molecules have been associated with drug resistance. MicroRNAs (miRNAs) have been described as having an important action in the emergence of cancer, including hematological tumors, and as being major players in their progression, aggressiveness and response to treatments. Moreover, miRNAs have been strongly associated with cancer drug resistance and with the modulation of the sensitivity of cancer cells to a wide array of anticancer drugs. Furthermore, this role has also been reported for miRNAs packaged into extracellular vesicles (EVs-miRNAs), which in turn have been described as essential for the horizontal transfer of drug resistance to sensitive cells. Several studies have been suggesting the use of miRNAs as biomarkers for drug response and clinical outcome prediction, as well as promising therapeutic tools in hematological diseases. Indeed, the combination of miRNA-based therapeutic tools with conventional drugs contributes to overcome drug resistance. This review addresses the role of miRNAs in the pathogenesis of hematological malignances, namely multiple myeloma, leukemias and lymphomas, highlighting their important action (either in their cell-free circulating form or within circulating EVs) in drug resistance and their potential clinical applications.

MicroRNA-381-A Key Transcriptional Regulator: Its Biological Function and Clinical Application Prospects in Cancer

MicroRNAs (miRNAs) are small non-coding RNA molecules that function by regulating messenger RNAs. Recent studies have shown that miRNAs play important roles in multiple processes of cancer development. MiR-381 is one of the most important miRNAs in cancer progression. MiR-381 is downregulated in some cancers and upregulated in other cancers, including glioma, epithelial sarcoma, and osteosarcoma. MiR-381 regulates epithelial-mesenchymal transition (EMT), chemotherapeutic resistance, radioresistance, and immune responses. Thus, miR-381 participates in tumor initiation, progression, and metastasis. Moreover, miR-381 functions in various oncogenic pathways, including the Wnt/β-catenin, AKT, and p53 pathways. Clinical studies have shown that miR-381 could be considered a biomarker or a novel prognostic factor. Here, we summarize the present studies on the role of miR-381 in cancer development, including its biogenesis and various affected signaling pathways, and its clinical application prospects. MiR-381 expression is associated with tumor stage and survival time, making miR-381 a novel prognostic factor.

Clinical significance of dysregulation of miR-381 in pediatric acute myeloid leukemia

Background

microRNA-381 is dysregulated in a variety of cancers. However, its clinical significance in pediatric acute myeloid leukemia (AML) is still unclear. The purpose of this study was to detect the expression level of miR-381 in pediatric AML patients and to explore its potential clinical significance.

Methods

The levels of miR-381 in bone marrow and serum of 102 pediatric AML patients were measured by quantitative real-time polymorperase chain reaction (qRT-PCR). The diagnostic value of serum miR-381 in pediatric AML patients was evaluated by the receiver operating characteristic (ROC) curve. A Chi square test was used to analyze the relationship between serum miR-381 and the clinical characteristics of patients. Cox regression analysis and Kaplan–Meier evaluated the prognostic value of serum miR-381 in patients. Finally, the proliferation of the cells was analyzed by the CCK-8 assay.

Results

Compared with healthy controls, the levels of miR-381 in serum and bone marrow of pediatric AML patients were significantly decreased (P < 0.001). ROC curve showed that miR-381 could distinguish pediatric AML cases from normal controls. At the same time, the downregulation of miR-381 was associated with M7 in the French–American–British (FAB) classifications and unfavorable cytogenetic risks (P < 0.05). Low serum miR-381 levels were associated with poor overall survival of pediatric AML (log-rank test, P = 0.011) and poor relapse-free survival (log-rank test, P = 0.004). Cox regression analysis confirmed that reduced serum miR-381 was an independent predictor of poor prognosis in AML (HR = 3.794, 95% CI 1.3633–10.559, P = 0.011). In addition, low expression of miR-381 significantly reduced the proliferation of cells (P < 0.05).

Conclusion

All experimental results confirm that miR-381 has reduced bone marrow and serum expression in pediatric AML, and low levels of serum miR-381 have certain diagnostic and prognostic value in pediatric AML and may be a potential therapeutic target for AML.

miRNA-based biomarkers, therapies, and resistance in Cancer

MicroRNAs (miRNAs), small non-coding RNAs (ncRNAs) of about 22 nucleotides in size, play important roles in gene regulation, and their dysregulation is implicated in human diseases including cancer. A variety of miRNAs could take roles in the cancer progression, participate in the process of tumor immune, and function with miRNA sponges. During the last two decades, the connection between miRNAs and various cancers has been widely researched. Based on evidence about miRNA, numerous potential cancer biomarkers for the diagnosis and prognosis have been put forward, providing a new perspective on cancer screening. Besides, there are several miRNA-based therapies among different cancers being conducted, advanced treatments such as the combination of synergistic strategies and the use of complementary miRNAs provide significant clinical benefits to cancer patients potentially. Furthermore, it is demonstrated that many miRNAs are engaged in the resistance of cancer therapies with their complex underlying regulatory mechanisms, whose comprehensive cognition can help clinicians and improve patient prognosis. With the belief that studies about miRNAs in human cancer would have great clinical implications, we attempt to summarize the current situation and potential development prospects in this review.

MicroRNAs Modulate Drug Resistance-Related Mechanisms in Hepatocellular Carcinoma

Primary liver cancer [hepatocellular carcinoma (HCC)] is one of the most common malignant tumors worldwide, causing serious health threats because of its high morbidity and mortality, rapid growth, and strong invasiveness. Patients with HCC frequently develop resistance to the current chemotherapeutic drugs, and this is largely attributed to the high-level heterogeneity of the tumor tissue. MicroRNAs (miRNAs) are a group of master regulators for multiple physiological and pathological processes and play important roles in the tumorigenesis. More recent studies have indicated that miRNAs also play a non-negligible role in the development of drug resistance in liver cancer. In this review, we summarize the data from the latest studies on the mechanisms of drug resistance in liver cancer, including autophagy, membrane transporters, epithelial-mesenchymal transitions (EMTs), tumor microenvironment, and genes and proteins that are associated with apoptosis. The data herein will provide valuable information for the development of novel approaches to tackle drug resistance in the management of liver cancer.

Identification the prognostic value of glutathione peroxidases expression levels in acute myeloid leukemia

Background

Glutathione peroxidases (GPXs) are an enzyme family with peroxidase activity. Abnormal GPX expression is associated with carcinogenesis. However, the potential role of the GPX gene family in acute myeloid leukemia (AML) remains to be comprehensively examined.

Methods

We analyzed GPX mRNA expression levels and determined the correlation between gene expression and the prognostic value via multiple universally acknowledged databases including the Oncomine, Gene Expression Profiling Interactive Analysis (GEPIA), PROGgeneV2, UALCAN, Cancer Cell Line Encyclopedia (CCLE), and The European Bioinformatics Institute (EMBL-EBI) databases. The functional network of differentially expressed GPXs was investigated via the NetworkAnalyst platform. Correlated genes as well as kinase, microRNA (miRNA), and transcription factor (TF) targets were identified using LinkedOmics.

Results

We observed that the transcriptional expression levels of GPX-1, -2, -4, -7, and -8 had significant difference between AML patients samples and normal samples, and that AML patients with high expression of GPX-1, -3, -4, and -7 were associated with poorer prognosis of overall survival (OS). Functional enrichment analysis showed that the differentially expressed GPXs were mainly enriched in response to oxidative stress, regulation of immune response, and inflammatory response, along with glutathione metabolism and ferroptosis. Overexpression of correlated genes, PSMB10, VPS13D, NDUFS8, ATP5D, POLR2E, and HADH were linked to adverse OS in AML. Regulatory network analysis indicated that differentially expressed GPXs regulated cell proliferation, cancer progression, apoptosis, and cell cycle signaling via pathways involving cancer-related kinases (such as DAPK1 and SRC), miRNAs (such as miR-202 and miR-181), and TFs (such as SRF and E2F1).

Conclusions

Our findings offer novel insights into the differential expression and prognostic potential of the GPX family in AML, and lay a foundation for subsequent research of GPX’s role in the carcinogenesis and regulatory network of AML.

Protective effect of microRNA‑381 against inflammatory damage of endothelial cells during coronary heart disease by targeting CXCR4

Coronary heart disease (CHD) is the leading cause of human morbidity and mortality worldwide. MicroRNA (miRNA) profiling is an innovative method of identifying biomarkers for many diseases and may be a powerful tool in the diagnosis and treatment of CHD. The present study aimed to analyze the effects of miRNA (miR)‑381 on the inflammatory damage of endothelial cells during CHD. A total of 21 patients with CHD and 21 healthy control patients were enrolled in this study. Reverse transcription‑quantitative PCR, western blotting and immunofluorescence assays were conducted to examine the expression levels of miR‑381, C‑X‑C chemokine receptor type 4 (CXCR4), Bcl‑2, Bax, Cleaved‑Caspases‑3 and ‑9, p38, ERK1/2 and JNK. Cell Counting Kit‑8, EdU and flow cytometry experiments were performed to evaluate cell proliferation and apoptosis. An ELISA was adopted to determine the expressions of inflammatory factors (interleukins‑8, ‑6 and ‑1β, and tumor necrosis factor‑α). In addition, a dual‑luciferase reporter assay was used to determine the relationship between miR‑381 and CXCR4. Decreased miR‑381 expression and increased CXCR4 expression in the plasma were observed in the CHD group compared with the normal group, which indicated a negative relationship between miR‑381 and CXCR4. Overexpression of miR‑381 significantly promoted the proliferation and inhibited the apoptosis of oxidized low‑density lipoprotein (OX‑LDL)‑induced human umbilical vein endothelial cells (HUVECs) through mitogen‑activated protein kinase pathway by targeting and inhibiting CXCR4. Furthermore, overexpression of miR‑381 reduced the release of inflammatory factors in OX‑LDL‑induced HUVECs. By contrast, reduced expression of miR‑381 exerted the opposite effects, which were subsequently reversed by silencing CXCR4 expression. Results from the present study indicated that miR‑381 was a CHD‑related factor that may serve as a potential molecular target for CHD treatment.

Screening of potential miRNA therapeutics for the prevention of multi-drug resistance in cancer cells

Chemotherapy, a major cancer treatment approach, suffers seriously from multidrug resistance (MDR), generally caused by innate DNA repair proteins that reverse the DNA modification by anti-cancer therapeutics or trans-membrane efflux proteins that pump anti-cancer therapeutics out of the cytosol. This project focused on finding microRNAs that can regulate MDR proteins by managing corresponding mRNA levels through post-transcriptional regulation based on nucleotide sequence matching. Screening was done with bioinformatics databases for unpublished/unexplored microRNAs with high nucleotide sequence correspondence to two representative MDR proteins, MGMT (a DNA repair protein) and ABCB1 (an efflux protein), revealing microRNA-4539 and microRNA-4261 respectively. To investigate the enhancement of chemotherapeutics in cancer cells, high MGMT expressing glioblastoma (T98G) and a high ABCB1 expressing triple-negative breast cancer cell line (MDA-MB-231-luc) were treated with varying concentrations of chemotherapeutics and corresponding miRNAs. Newly identified MDR-related miRNAs (MDRmiRs) enhanced the response to anti-cancer therapeutics and resulted in effective cell death. In this study, we demonstrated that therapeutic miRNAs could be identified based on the nucleotide sequence matching of miRNAs to targeted mRNA and the same approach could be employed for the screening of therapeutic candidates to regulate specific target proteins in diverse diseases.

SNHG15 Contributes To Cisplatin Resistance In Breast Cancer Through Sponging miR-381

Background

Increasing evidence implies the participation of long non-coding RNAs (lncRNAs) in chemoresistance to cancer treatment. Their role and molecular mechanisms in breast cancer chemoresistance, nevertheless, are yet not considerably elucidated. In this work, we research the function of small nucleolar RNA host gene 15 (SNHG15) in cisplatin (DDP) resistance of breast cancer and uncover the underlying molecular mechanism.

Methods

SNHG15 and miR-381 expression levels were detected using Quantitative real-time PCR (qRT-PCR) analysis. The functional roles of SNHG15 and miR-381 in breast cancer were determined using MTT assay and flow cytometry analysis. The effect of SNHG15 on miR-381 expression was determined using Luciferase reporter assay, RNA immunoprecipitation (RIP) assay and qRT-PCR analysis.

Results

SNHG15 was found to be up-regulated in cisplatin resistant breast cancer tissues and cell lines. Breast cancer patients with high SNHG15 expression had a poor prognosis. SNHG15 silencing enhanced cisplatin sensitivity of MCF-7/DDP and MDA-MB-231/DDP cells. Additionally, SNHG15 could function as a miR-381 sponge. miR-381 overexpression could overcome cisplatin resistance. miR-381 knockdown countered SNHG15 knockdown-mediated enhancement of cisplatin sensitivity in MCF-7/DDP and MDA-MB-231/DDP cells. Besides, SNHG15 knockdown facilitated cisplatin sensitivity of cisplatin resistant breast cancer cells in vivo.

Conclusion

In summary, SNHG15 knockdown overcame cisplatin resistance of breast cancer by sponging miR-381, providing a novel therapeutic target for breast cancer.

EZH2 Contributes To Cisplatin Resistance In Breast Cancer By Epigenetically Suppressing miR-381 Expression

BACKGROUND

Emerging evidence reveals the vital role of enhancer of zeste homolog 2 (EZH2) in cancer chemoresistance. However, its function and molecular mechanisms in breast cancer chemoresistance remain largely unknown.

METHODS

Gene expression was evaluated using quantitative real-time PCR (qRT-PCR) and Western blot analysis. The functional roles of EZH2 and miR-381 in breast cancer were explored using cell MTT assay and flow cytometry analysis. The effect of EZH2 on miR-381 expression in transcriptional level was determined using Chromatin immunoprecipitation (ChIP) assay and Luciferase reporter assay.

RESULTS

In this study, we found that EZH2 was up-regulated in CDDP-resistant breast cancer tissues and cell lines. Breast cancer patients with high EZH2 expression had a poor prognosis. EZH2 silencing improved the sensitivity of MCF-7/CDDP and MDA-MB-231/CDDP cells towards CDDP. Moreover, EZH2 could epigenetically silence miR-381. miR-381 overexpression could overcome CDDP resistance in CDDP-resistant breast cancer cells. miR-381 knockdown weakened the inductive effect of EZH2 silencing on CDDP sensitivity of MCF-7/CDDP and MDA-MB-231/CDDP cells. Furthermore, EZH2 knockdown facilitated CDDP sensitivity of CDDP-resistant breast cancer cells in vivo.

CONCLUSIONS

Collectively, EZH2 depletion overcame CDDP resistance of breast cancer through epigenetically silencing miR-381, providing a novel therapeutic target for breast cancer chemoresistance.

LncRNA FENDRR attenuates adriamycin resistance via suppressing MDR1 expression through sponging HuR and miR-184 in chronic myelogenous leukaemia cells

Chemotherapy is a major anticancer therapeutic modality, however, multidrug resistance (MDR) is frequently observed and hinders treatment efficacy. Here, we investigated the role and potential mechanism of the long noncoding RNA (lncRNA) FENDRR in adriamycin resistance of chronic myeloid leukaemia (CML) cells. FENDRR overexpression attenuates adriamycin resistance, as shown by increased Rhodamine 123 accumulation, promotion of cell apoptosis in vitro and suppression of tumour growth in vivo. Mechanistically, we identified that FENDRR reduces the interaction of the RNA-binding protein HuR with MDR1 via acting as a sponge, and miR-184 competitively binds to FENDRR with HuR. Thus, the HuR/FENDRR/miR-184 interaction contributes to MDR1 activity. These findings indicate that FENDRR is a potential target for reversing adriamycin resistance.

Inhibition of MicroRNA-381 Promotes Tumor Cell Growth and Chemoresistance in Clear-Cell Renal Cell Carcinoma

Background

MicroRNA-381 (miR-381) is proven to be involved in many human tumors. Bioinformatics prediction suggests that miR-381 is decreased in renal cell carcinoma. However, its biological functions in clear-cell renal cell carcinoma (ccRCC) remain largely unknown. The present research aimed to evaluate miR-381 expression in renal cancer tissues and its effects on cell proliferation, growth, migration, and chemoresistance.

Material/Methods

Sixty pairs of ccRCC and the adjacent non-tumor specimens were collected during routine therapeutic surgery. Quantitative real-time PCR (qRT-PCR) assay was employed to examine miR-381 expression in the ccRCC tissues and the associated adjacent tissues (the normal tissues adjacent to tumor tissues). Cell transfection assay and Thiazolyl Blue Tetrazolium Bromide (MTT) assay were utilized to observe effects of miR-381 on the cell proliferation, growth, invasion, and chemoresistance in the Caki-1 cell line and 786-O cell line. Flow cytometry was used to assess cell apoptosis. Caki-1 cell and 786-O cell Xenograft BALB/c mouse models were established.

Results

miR-381 expression was downregulated in ccRCC tissues in vivo and in cell lines in vitro. Downregulation of miR-381 promoted growth of cells and restrained the ccRCC cell apoptosis. Increased miR-381 combined with Ci and Pa suppressed the proliferation and enhanced the anti-tumor effects of Ci and Pa at tolerated concentrations in vitro. miR-381 inhibition promoted chemoresistance in vitro.

Conclusions

miR-381 levels were significantly downregulated in renal cancer tissues and miR-381 inhibition promoted tumor cell growth, migration, and chemoresistance.

MicroRNA-381 suppresses proliferation and invasion of prostate cancer cells through downregulation of the androgen receptor

Prostate cancer (PCa) is the most frequently diagnosed malignancy in men and its incidence has increased rapidly worldwide. Notably, the molecular mechanisms underlying prostate tumorigenesis have not been fully identified. The levels of microRNA (miR)-381 have been explored in numerous types of malignancy; however, the expression levels and biological function of miR-381 in PCa remain largely unknown. In the present study, reverse-transcription polymerase chain reaction was used to detect the expression levels of miR-381 in PCa cells and normal prostate epithelial cells. Subsequently, miR-381 antisense oligonucleotides and mimics were transfected into LNCaP PCa cells. Bioinformatics analysis was performed to identify the potential target genes of miR-381. Protein expression analysis, dual-luciferase reporter assay and a rescue assay were used to confirm the target of miR-381. The data suggested that the expression levels of miR-381 were significantly decreased in PCa cells compared with in normal prostatic epithelial cells. Furthermore, transfection of LNCaP cells with miR-381 mimics suppressed their proliferation, migration and invasion. In addition, bioinformatics analysis suggested that the androgen receptor (AR) was a target gene of miR-381. miR-381 suppressed the expression levels of AR by directly binding to its 3'-untranslated region. Furthermore, transfection with an AR plasmid partially attenuated miR-381-induced inhibition of cell proliferation, migration and invasion. The results of the present study suggested that miR-381 may act as a tumor suppressor in PCa by directly targeting the AR.

Role of microRNAs, circRNAs and long noncoding RNAs in acute myeloid leukemia

Acute myeloid leukemia (AML) is a malignant tumor of the immature myeloid hematopoietic cells in the bone marrow (BM). It is a highly heterogeneous disease, with rising morbidity and mortality in older patients. Although researches over the past decades have improved our understanding of AML, its pathogenesis has not yet been fully elucidated. Long noncoding RNAs (lncRNAs), microRNAs (miRNAs), and circular RNAs (circRNAs) are three noncoding RNA (ncRNA) molecules that regulate DNA transcription and translation. With the development of RNA-Seq technology, more and more ncRNAs that are closely related to AML leukemogenesis have been discovered. Numerous studies have found that these ncRNAs play an important role in leukemia cell proliferation, differentiation, and apoptosis. Some may potentially be used as prognostic biomarkers. In this systematic review, we briefly described the characteristics and molecular functions of three groups of ncRNAs, including lncRNAs, miRNAs, and circRNAs, and discussed their relationships with AML in detail.

Wnt pathway targeting reduces triple-negative breast cancer aggressiveness through miRNA regulation in vitro and in vivo

Triple-negative breast cancer, devoid of estrogen (ER), progesterone (PR), and human epidermal growth factor receptor 2 (HER-2) expression, is deprived of commonly used targeted therapies. MicroRNAs (miRNAs) are undergoing a revolution in terms of potentially diagnostic or therapeutic elements. Combining computational approaches, we enriched miRNA binding motifs of Wnt pathway-associated upregulated genes. Our in-depth bioinformatics, in vitro and in vivo analyses indicated that miR-381 targets main genes of the Wnt signaling pathway including CTNNB1, RhoA, ROCK1, and c-MYC genes. The expression level of miR-381 and target genes was assessed by quantitative real-time polymerase chain reaction (RT-qPCR) in MCF-7, MDA-MB-231, and MCF-10A as well as 20 breast cancer samples and normal tissues. Luciferase reporter assay was performed. Lentiviral particles containing miR-381 were used to evaluate the effect of miR-381 restoration on cell proliferation, migration, and invasion of the invasive triple-negative MDA-MB-231 cell line and also in a mouse model of breast cancer. The expression of miR-381 was lower than that of normal cells, especially in TNBC cell line and breast tissues. Luciferase assay results confirmed that miR-381 targets all the predicted 3'-untranslated regions (3'-UTRs). Upon miR-381 overexpression, the expression of target genes declined, and the migration and invasion potential of miR-381-receiving MDA-MB-231 cells decreased. In a mouse model of triple-negative breast cancer, miR-381 re-expression inhibited the invasion of cancer cells to lung and liver and prolonged the survival time of cancer cell-bearing mice. Therefore, miR-381 is a regulator of Wnt signaling and its re-expression provides a potentially effective strategy for inhibition of TNBC.

Reduced protocadherin17 expression in leukemia stem cells: the clinical and biological effect in acute myeloid leukemia

Background

Leukemia stem cell (LSC)-enriched genes have been shown to be highly prognostic in acute myeloid leukemia (AML). However, the prognostic value of tumor suppressor genes (TSGs) that are repressed early in LSC remains largely unknown.

Methods

We compared the public available expression/methylation profiling data of LSCs with that of hematopoietic stem cells (HSCs), in order to identify potential tumor suppressor genes in LSC. The prognostic relevance of PCDH17 was analyzed on a cohort of 173 AML patients from The Cancer Genome Atlas (TCGA), and further validated in three independent cohorts (n = 339).

Results

We identified protocadherin17 (PCDH17) and demonstrated that it was significantly down-regulated and hypermethylated in LSCs compared with HSCs. Our analyses of primary AML patient samples also confirmed these deregulations. Clinically, low PCDH17 expression was associated with female sex (P = 0.01), higher WBC (P < 0.0001), higher percentages of blasts in bone marrow (BM) and peripheral blood (PB) (P = 0.04 and < 0.001, respectively), presence of FLT3-internal tandem duplications (P = 0.002), mutated NPM1 (P = 0.02), and wild-type TP53 (P = 0.005). Moreover, low PCDH17 expression predicted worse overall survival (OS) in four independent cohorts as well as in the molecularly defined subgroups of AML patients. In multivariable analyses, low PCDH17 expression retained independent prognostic value for OS. Biologically, PCDH17 expression-associated gene signatures were characterized by deregulations of EMT- and Wnt pathway-related genes.

Conclusions

PCDH17 gene was silenced by DNA methylation in AML. Low PCDH17 expression is associated with distinct clinical and biological features and improves risk stratification in patients with AML.

Electronic supplementary material

The online version of this article (10.1186/s12967-019-1851-1) contains supplementary material, which is available to authorized users.

miR-381 overcomes cisplatin resistance in breast cancer by targeting MDR1

Increasing evidence suggests the involvement of microRNA-381 (miR-381) in chemoresistance of cancer treatment. However, its function and molecular mechanisms in breast cancer chemoresistance are still not well elucidated. In the present study, we aimed to investigate the functional role of miR-381 in cisplatin (DDP) resistance of breast cancer and discover the underlying molecular mechanism. The expression levels of miR-381 and MDR1 were detected by quantitative real-time PCR (qRT-PCR) and Western blot analysis in breast cancer tissues and cell lines. The DDP sensitivity and cell apoptosis of breast cancer cells were determined by MTT assay and flow cytometric analysis, respectively. The relationship between miR-381 and MDR1 was explored by target prediction and luciferase reporter analysis. miR-381 was decreased in DDP-resistant breast cancer tissues and cell lines. Low miR-381 expression was correlated with poor prognosis of breast cancer patients. miR-381 overexpression improved DDP sensitivity of MCF-7/DDP and MDA-MB-231/DDP cells. Conversely, miR-381 inhibition lowered the response of MCF-7 and MDA-MB-231 to DPP. Moreover, miR-381 could directly suppress multidrug resistance 1 (MDR1) expression. MDR1 knockdown could overcome DDP resistance in MCF-7/DDP and MDA-MB-231/DDP cells, while MDR1 overexpression led to DDP resistance in MCF-7 and MDA-MB-231 cells. Notably, MDR1 overexpression counteracted the inductive effect of miR-381 mimics on DDP sensitivity of MCF-7/DDP and MDA-MB-231/DDP cells. On the contrary, miR-381 inhibition-mediated DDP resistance in MCF-7 and MDA-MB-231 cells was reversed by MDR1 knockdown. In summary, miR-381 could overcome DDP resistance of breast cancer by directly targeting MDR1, providing a novel therapeutic target for breast cancer chemoresistance.

A Novel Synthetic Dihydroindeno[1,2-b] Indole Derivative (LS-2-3j) Reverses ABCB1- and ABCG2-Mediated Multidrug Resistance in Cancer Cells

10-oxo-5-(3-(pyrrolidin-1-yl) propyl)-5,10-dihydroindeno [1,2-b] indol-9-yl propionate (LS-2-3j) is a new chemically synthesized indole compound and some related analogues are known to be inhibitors (such as alectinib and Ko143) of ATP-binding cassette (ABC) transporters, especially the ABC transporter subfamily B member 1 (ABCB1) and the ABC transporter subfamily G member 2 (ABCG2). This study aimed to evaluate the multidrug resistance (MDR) reversal effects and associated mechanisms of LS-2-3j in drug-resistant cancer cells. The inhibition of cell proliferation in tested agents was evaluated by the 3-(4,5-dimethylthiazol)-2,5-diphenyltetrazolium bromide (MTT) assay. Accumulation or efflux of chemotherapy drugs was analyzed by flow cytometry. The ATPase activity was measured using an ATPase activity assay kit. The mRNA transcripts and protein expression levels were detected by real-time PCR and Western blot, respectively. In this connection, LS-2-3j significantly enhanced the activity of chemotherapeutic drugs in MDR cells and could significantly increase the intracellular accumulation of doxorubicin (DOX) and mitoxantrone (MITX) by inhibiting the function of the efflux pumps in ABCB1- or ABCG2-overexpressing cells. Furthermore, reduced ATPase activity, mRNA transcription, and protein expression levels of ABCB1 and ABCG2 were observed in a concentration dependent manner in MDR cancer cells.

Expression and role of VEGFA and miR-381 in portal vein tumor thrombi in patients with hepatocellular carcinoma

The aim of the present study was to examine the expression and role of vascular endothelial growth factor A (VEGFA) and microRNA (miRNA or miR)-381 in tumor thrombi from patients with hepatocellular carcinoma and portal vein tumor thrombus (PVTT). Tumor thrombi and adjacent paired tissues were collected from 39 patients with hepatocellular carcinoma with PVTT. VEGFA expression levels were assessed using reverse transcription-quantitative polymerase chain reaction and western blotting. miRNAs that may regulate VEGFA expression were predicted using bioinformatics analysis and confirmed via a dual luciferase reporter assay. The effects of VEGFA and its upstream miRNA on proliferation of the proliferation of EAhy926 human venous endothelial cells were analyzed using an MTT assay. Compared with the paired adjacent tissues, VEGFA was significantly upregulated at both the mRNA and protein level in tumor thrombi (P<0.05). VEGFA was predicted to be a target of miR-381 and this was confirmed experimentally. miR-381 expression was significantly downregulated in tumor thrombi from patients with PVTT compared with paired adjacent tissues (P<0.05). In addition, transfection with antagomirs against miR-381 or short interfering RNA against VEGFA significantly inhibited EAhy926 cell proliferation (P<0.05). In conclusion, the results of the present study indicate that VEGFA is upregulated in tumor thrombi whereas miR-381 is downregulated. VEGFA is regulated by miR-381 and both may be associated with the development of PVTT.

MicroRNA-381 regulates the occurrence and immune responses of coronary atherosclerosis via cyclooxygenase-2

The present study aimed to measure the levels of microRNA-381 (miR-381) in the plaque tissues, peripheral blood mononuclear cells (PBMCs) and serum of patients with coronary atherosclerosis. In addition, the regulatory mechanisms of miR-381 and cyclooxygenase (COX)-2 in coronary atherosclerosis were investigated. A total of 36 patients with coronary atherosclerosis who received coronary endarterectomy at Linyi People's Hospital and Junan Hospital of Traditional Chinese Medicine (Linyi, China) between January 2013 and June 2016 were enrolled into the present study, while 39 healthy subjects were included as the control group. Peripheral blood was collected form all patients and healthy subjects. Plaque tissues were resected from patients with coronary atherosclerosis and adjacent artery intimal tissues were resected as the control tissues. Using quantitative polymerase chain reaction, the levels of miR-381 and COX-2 mRNA in the plaque tissues, PBMCs and serum were determined. In addition, COX-2 protein expression in the plaque tissues and PBMCs was measured by western blotting, while enzyme-linked immunosorbent assay was utilized to examine the protein content in the serum. To identify the direct interaction between miR-381 and COX-2 mRNA, dual-luciferase reporter assay was also conducted. The levels of COX-2 mRNA and protein in the plaque tissues, PBMCs and serum of patients with coronary atherosclerosis were significantly elevated compared with those in the corresponding control groups. However, the expression of miR-381 was significantly reduced in the coronary atherosclerosis patients. Dual-luciferase reporter assay revealed that miR-381 was able to directly target the 3'-untranslated region of COX-2 mRNA to regulate the expression of COX-2. Therefore, the present study demonstrated that enhanced levels of COX-2 expression in patients with coronary atherosclerosis are associated with the downregulation of miR-381 expression, while miR-381 may regulate the occurrence and immune responses of coronary atherosclerosis via COX-2.

MicroRNA-381 protects myocardial cell function in children and mice with viral myocarditis via targeting cyclooxygenase-2 expression

The present study aimed to determine the expression of cyclooxygenase (COX)-2 and microRNA (miRNA/miR)-381 in the blood of children with viral myocarditis (VM), and investigate the association between COX-2 and miR-381 in the occurrence and development of the disease using a mouse model. A total of 26 children with VM (15 boys and 11 girls) were included in the present study. Peripheral blood was collected from all children. The mouse model of VM was constructed by coxsackievirus B3 (CVB3) infection. Peripheral blood and myocardial tissues were collected from all mice for analysis. Reverse transcription-quantitative polymerase chain reaction was used to determine the expression of COX-2 mRNA and miR-381 in serum and myocardial tissues. ELISA was used to measure the content of COX-2 protein in serum from humans and mice, and western blotting was employed to determine the expression of COX-2 protein in myocardial tissues from mice. Contents of creatine kinase (CK-MB) and lactate dehydrogenase (LDH) were evaluated using an automatic biochemical analyzer. A dual luciferase assay was conducted to identify interactions between COX-2 mRNA and miR-381. Children with VM had increased COX-2 levels and decreased miR-381 expression in peripheral blood, compared with those who had recovered from VM. CVB3 infection resulted in damage in the myocardium of mice, and elevated CK-MB and LDH contents. VM model mice exhibited increased COX-2 levels and decreased miR-381 expression in peripheral blood and myocardial tissues compared with normal mice. miR-381 binds to the 3'-untranslated seed regions of both human and mouse COX-2 mRNA to regulate their expression. The present study demonstrated that children with VM have decreased miR-381 expression and elevated COX-2 expression in peripheral blood. miR-381 may inhibit myocardial cell damage caused by CVB3 infection and protect myocardial cell function by targeting COX-2 expression.

MicroRNA-381-induced down-regulation of CXCR4 promotes the proliferation of renal tubular epithelial cells in rat models of renal ischemia reperfusion injury

This study aims to explore whether microRNA-381 (miR-381) mediating CXCR4 affects the renal tubular epithelial cells (RTEC) of renal ischemia reperfusion (I/R) injury. Forty-eight rats were assigned into the I/R (n = 24, successfully established as I/R model) and sham (n = 24) groups. After collecting kidney tissues, immunohistochemistry, and microvascular density (MVD) counting were conducted for CXCR4 positive expression and MVD numbers. RTECs were assigned into the sham, blank, negative control (NC), miR-381 mimics, miR-381 inhibitor, si-CXCR4, and miR-381 inhibitor + si-CXCR4 groups. RT-qPCR and Western blotting were performed for relative expressions in tissues and cells. Cell proliferation and apoptosis were measured by MTT assay and flow cytometry. Results showed that compared with the sham group, positive expression of CXCR4 and MVD number were higher in the I/R group, which exhibited decreased miR-381 and increased expression of CXCR4, stromal cell-derived factor-1 (SDF1), vascular endothelial growth factor (VEGF), hypoxia-inducible factor 1 (HIF-1α) and Tie-2. Dual luciferase reporter gene assay verified that CXCR4 is a target gene of miR-381. MiR-381 expression was lower in the miR-381 inhibitor + si-CXCR4 and miR-381 inhibitor groups and higher in the miR-381 mimics group than the blank and NC groups. Compared with the blank and NC groups, the miR-381 mimics and si-CXCR4 groups exhibited higher cell proliferation but lower cell apoptosis and expression of CXCR4, SDF1, VEGF, HIF-1α, and Tie-2, whereas the miR-381 inhibitor group exhibited the opposite trend. In conclusion, miR-381 may promote RTEC proliferation in rats with renal I/R injury by down-regulating CXCR4.

MicroRNAs regulate key cell survival pathways and mediate chemosensitivity during progression of diffuse large B-cell lymphoma

Despite better therapeutic options and improved survival of diffuse large B-cell lymphoma (DLBCL), 30–40% of the patients experience relapse or have primary refractory disease with a dismal prognosis. To identify biological correlates for treatment resistance, we profiled microRNAs (miRNAs) of matched primary and relapsed DLBCL by next-generation sequencing. Altogether 492 miRNAs were expressed in the DLBCL samples. Thirteen miRNAs showed significant differential expression between primary and relapse specimen pairs. Integration of the differentially expressed miRNAs with matched mRNA expression profiles identified highly anti-correlated, putative targets, which were significantly enriched in cancer-associated pathways, including phosphatidylinositol (PI)), mitogen-activated protein kinase (MAPK), and B-cell receptor (BCR) signaling. Expression data suggested activation of these pathways during disease progression, and functional analyses validated that miR-370-3p, miR-381-3p, and miR-409-3p downregulate genes on the PI, MAPK, and BCR signaling pathways, and enhance chemosensitivity of DLBCL cells in vitro. High expression of selected target genes, that is, PIP5K1 and IMPA1, was found to be associated with poor survival in two independent cohorts of chemoimmunotherapy-treated patients (n = 92 and n = 233). Taken together, our results demonstrate that differentially expressed miRNAs contribute to disease progression by regulating key cell survival pathways and by mediating chemosensitivity, thus representing potential novel therapeutic targets.

MicroRNA-212/ABCG2-axis contributes to development of imatinib-resistance in leukemic cells

BCR-ABL-independent resistance against tyrosine kinase inhibitor is an emerging problem in therapy of chronic myeloid leukemia. Such drug resistance can be linked to dysregulation of ATP-binding cassette (ABC)-transporters leading to increased tyrosine kinase inhibitor efflux, potentially caused by changes in microRNA expression or DNA-methylation. In an in vitro-imatinib-resistance model using K-562 cells, microRNA-212 was found to be dysregulated and inversely correlated to ABC-transporter ABCG2 expression, targeting its 3'-UTR. However, the functional impact on drug sensitivity remained unknown. Therefore, we performed transfection experiments using microRNA-mimics and -inhibitors and investigated their effect on imatinib-susceptibility in sensitive and resistant leukemic cell lines. Under imatinib-treatment, miR-212 inhibition led to enhanced cell viability (p = 0.01), reduced apoptosis (p = 0.01) and cytotoxicity (p = 0.03). These effects were limited to treatment-naïve cells and were not observed in cells, which were resistant to various imatinib-concentrations (0.1 μM to 2 μM). Further analysis in treatment-naïve cells revealed that miR-212 inhibition resulted in ABCG2 upregulation and increased ABCG2-dependent efflux. Furthermore, we observed miR-212 promoter hypermethylation in 0.5 and 2 μM IM-resistant sublines, whereas ABCG2 methylation status was not altered. Taken together, the miR-212/ABCG2-axis influences imatinib-susceptibility contributing to development of imatinib-resistance. Our data reveal new insights into mechanisms initiating imatinib-resistance in leukemic cells.

miR-495 sensitizes MDR cancer cells to the combination of doxorubicin and taxol by inhibiting MDR1 expression

MDR1 is highly expressed in MDR A2780DX5 ovarian cancer cells, MDR SGC7901R gastric cancer cells and recurrent tumours. It pumps cytoplasmic agents out of cells, leading to decreased drug accumulation in cells and making cancer cells susceptible to multidrug resistance. Here, we identified that miR-495 was predicted to target ABCB1, which encodes protein MDR1. To reduce the drug efflux and reverse MDR in cancer cells, we overexpressed a miR-495 mimic in SGC7901R and A2780DX cells and in transplanted MDR ovarian tumours in vivo. The results indicated that the expression of MDR1 in the above cells or tumours was suppressed and that subsequently the drug accumulation in the MDR cells was decreased, cell death was increased, and tumour growth was inhibited after treatment with taxol-doxorubicin, demonstrating increased drug sensitivity. This study suggests that pre-treatment with miR-495 before chemotherapy could improve the curative effect on MDR1-based MDR cancer.

Demethylation of miR-495 inhibits cell proliferation, migration and promotes apoptosis by targeting STAT-3 in breast cancer

In breast cancer (BC), silencing of miRNA genes due to miRNA gene promoter methylation are the important mechanisms directly contributing to tumorigenesis and tumor progression. miRNA-495 (miR-495) has been reported to be a tumor suppressor gene in various cancers, but its role and regulation in BC remains unclear. In the present study, the level of miR-495 was inversely correlated with the expression of STAT-3 in BC tissues and cell lines. miR-495 can directly target 3'-UTR of STAT-3 mRNA and thereby decrease the expression of STAT-3 in MCF-7 and HCC1973 cells by Targetscan and Dual-luciferase assay. We further analyzed miR-495 promoter methylation by sodium bisulfite sequencing method (BSP), and found DNA methyltransferase inhibitor, 5-AzaC concomitantly upregulated expression of miR-495 and downregulated its target gene STAT-3 and its downstream target VEGF. Furthermore, we further observed that 5-AzaC treatment, miR-495 mimics and STAT-3 knockdown significantly inhibited cell function in breast cancer by Transwell assay, EdU flow cytometry, Annexin V-FITC/PI combined with flow cytometry and Hoechst staining. Taken together, our data are first to demonstrate that the miR-495 is silenced due to promoter methylation in breast cancer. DNA methyltransferase inhibitor 5-AzaC could reverse miR‑495 (suppressor gene) and STAT-3 (oncogene). The anticancer properties of 5-AzaC were preliminarily confirmed in breast cancer.

Detection approaches for multidrug resistance genes of leukemia

Leukemia is a clonal malignant hematopoietic stem cell disease. It is the sixth most lethal cancer and accounts for 4% of all cancers. The main form of treatment for leukemia is chemotherapy. While some cancer types with a higher incidence than leukemia, such as lung and gastric cancer, have shown a sharp decline in mortality rates in recent years, leukemia has not followed this trend. Drug resistance is often regarded as the main clinical obstacle to effective chemotherapy in patients diagnosed with leukemia. Many resistance mechanisms have now been identified, and multidrug resistance (MDR) is considered the most important and prevalent mechanism involved in the failure of chemotherapy in leukemia. In order to reverse MDR and improve leukemia prognosis, effective detection methods are needed to identify drug resistance genes at initial diagnosis. This article provides a comprehensive overview of published approaches for the detection of MDR in leukemia. Identification of relevant MDR genes and methods for early detection of these genes will be needed in order to treat leukemia more effectively.

Expression, regulation and function of miR-495 in healthy and tumor tissues

MicroRNA-495 (miR-495) is a small non-coding RNA encoded by a gene located on chromosome 14 (14q32.31). Its expression is regulated by the transcription factors EF12 and EF47, in addition to promoter methylation status and the fusion oncoprotein mixed-lineage leukemia-AF9. Previous studies suggest that miR-495 is involved in various developmental, immunological and inflammatory processes in healthy tissue, and in the proliferation, invasion, metastasis and drug resistance of cancer cells. The role miR-495 serves in tumors is controversial. miR-495 primarily functions as a tumor suppressor; however, in a number of cases it acts as an oncogene. miR-495 has potential applications as a diagnostic and prognostic marker, and as a therapeutic target for genetic and pharmacological manipulation in the treatment of various diseases.

MicroRNA-381 inhibits the metastasis of gastric cancer by targeting TMEM16A expression

Background

MicroRNA-381 (miR-381) has been reported to play suppressive or promoting roles in different malignancies. However, the expression level, biological function, and underlying mechanisms of miR-381 in gastric cancer remain poorly understood. Our previous study indicated that transmembrane protein 16A (TMEM16A) contributed to migration and invasion of gastric cancer and predicted poor prognosis. In this study, we found that miR-381 inhibited the metastasis of gastric cancer through targeting TMEM16A expression.

Methods

MiR-381 expression was analyzed using bioinformatic software on open microarray datasets from the Gene Expression Omnibus (GEO) and confirmed by quantitative RT-PCR (qRT-PCR) in human gastric cancer tissues and cell lines. Cell proliferation was investigated using MTT and cell count assays, and cell migration and invasion abilities were evaluated by transwell assay. Xenograft nude mouse models were used to observe tumor growth and pulmonary metastasis. Luciferase reporter assay, western blot, enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry were employed to explore the mechanisms of the effect of miR-381 on gastric cancer cells.

Results

MiR-381 was significantly down-regulated in gastric cancer tissues and cell lines. Low expression of miR-381 was negatively related to lymph node metastasis, advanced tumor stage and poor prognosis. MiR-381 decreased gastric cancer cell proliferation, migration and invasion in vitro and in vivo. TMEM16A was identified as a direct target of miR-381 and the expression of miR-381 was inversely correlated with TMEM16A expression in gastric cancer tissues. Combination analysis of miR-381 and TMEM16A revealed the improved prognostic accuracy for gastric cancer patients. Moreover, miR-381 inhibited TGF-β signaling pathway and down-regulated epithelial–mesenchymal transition (EMT) phenotype partially by mediating TMEM16A.

Conclusions

MiR-381 may function as a tumor suppressor by directly targeting TMEM16A and regulating TGF-β pathway and EMT process in the development of progression of gastric cancer. MiR-381/TMEM16A may be a novel therapeutic candidate target in gastric cancer treatment.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-017-0499-z) contains supplementary material, which is available to authorized users.

MicroRNA-495 Inhibits Gastric Cancer Cell Migration and Invasion Possibly via Targeting High Mobility Group AT-Hook 2 (HMGA2)

Background

Gastric cancer is one of the most common malignancies, and has a high mortality rate. miR-495 acts as a suppressor in some cancers and HMGA2 (high mobility group AT-hook 2) is a facilitator for cell growth and epithelial-mesenchymal transition (EMT), but little is known about their effect in gastric cancer. This study aimed to investigate the role and mechanism of miR-495 in gastric cancer.

Material/Methods

miR-495 levels were quantitatively analyzed in gastric cancer tissue and GES-1, SGC-7901, BGC-823, and HGC-27 cell lines by qRT-PCR. Levels of miR-495 and HMGA2 were altered by cell transfection, after which cell migration and invasion were examined by Transwell and E-cadherin (CDH1); vimentin (VIM), and alpha smooth muscle actin (ACTA2) were detected by qRT-PCR and Western blotting. The interaction between miR-495 and HMGA2 was verified by dual-luciferase reporter assay.

Results

miR-495 was significantly downregulated in cancer tissue and cell lines (p<0.05). Its overexpression inhibited cell migration and invasion, elevated CDH1, and inhibited VIM and ACTA2 levels in BGC-823 and HGC-27 cells. miR-495 directly inhibited HMGA2, which was upregulated in gastric cancer tissue, and promoted cell migration and invasion, inhibited CDH1, and elevated VIM and ACTA2.

Conclusions

miR-495 acts as a tumor suppressor in gastric cancer by inhibiting cell migration and invasion, which may be associated with its direct inhibition on HMGA2. These results suggest a promising therapeutic strategy for gastric cancer treatment.

Regulation of multidrug resistance by microRNAs in anti-cancer therapy

Multidrug resistance (MDR) remains a major clinical obstacle to successful cancer treatment. Although diverse mechanisms of MDR have been well elucidated, such as dysregulation of drugs transporters, defects of apoptosis and autophagy machinery, alterations of drug metabolism and drug targets, disrupti on of redox homeostasis, the exact mechanisms of MDR in a specific cancer patient and the cross-talk among these different mechanisms and how they are regulated are poorly understood. MicroRNAs (miRNAs) are a new class of small noncoding RNAs that could control the global activity of the cell by post-transcriptionally regulating a large variety of target genes and proteins expression. Accumulating evidence shows that miRNAs play a key regulatory role in MDR through modulating various drug resistant mechanisms mentioned above, thereby holding much promise for developing novel and more effective individualized therapies for cancer treatment. This review summarizes the various MDR mechanisms and mainly focuses on the role of miRNAs in regulating MDR in cancer treatment.

miR-217 and CAGE form feedback loop and regulates the response to anti-cancer drugs through EGFR and HER2

MicroRNA array analysis revealed that miR-217 expression was decreased in anti-cancer drug-resistant Malme3M^R cancer cells. CAGE, a cancer/testis antigen, was predicted as a target of miR-217. Luciferase activity and ChIP assays revealed a negative feedback relationship between CAGE and miR-217. miR-217 and CAGE oppositely regulated the response to anti-cancer drugs such as taxol, gefitinib and trastuzumab, an inhibitor of HER2. miR-217 negatively regulated the tumorigenic, metastatic, angiogenic, migration and invasion potential of cancer cells. The xenograft of Malme3M^R cells showed an increased expression of pEGFR^Y845. CAGE and miR-217 inhibitor regulated the expression of pEGFR^Y845. CAGE showed interactions with EGFR and HER2 and regulated the in vivo sensitivity to trastuzumab. The down-regulation of EGFR or HER2 enhanced the sensitivity to anti-cancer drugs. CAGE showed direct regulation of HER2 and was necessary for the interaction between EGFR and HER2 in Malme3M^R cells. miR-217 inhibitor induced interactions of CAGE with EGFR and HER2 in Malme3M cells. The inhibition of EGFR by CAGE-binding GTGKT peptide enhanced the sensitivity to gefitinib and trastuzumab and prevented interactions of EGFR with CAGE and HER2. Our results show that miR-217-CAGE feedback loop serves as a target for overcoming resistance to various anti-cancer drugs, including EGFR and HER2 inhibitors.

Human adipose mesenchymal stem cell-derived exosomal-miRNAs are critical factors for inducing anti-proliferation signalling to A2780 and SKOV-3 ovarian cancer cells

An enigmatic question exists concerning the pro- or anti-cancer status of mesenchymal stem cells (MSCs). Despite growing interest, this question remains unanswered, and the debate became intensified with new evidences backing each side. Here, we showed that human adipose MSC (hAMSC)-derived conditioned medium (CM) exhibited inhibitory effects on A2780 human ovarian cancer cells by blocking the cell cycle, and activating mitochondria-mediated apoptosis signalling. Explicitly, we demonstrated that exosomes, an important biological component of hAMSC-CM, could restrain proliferation, wound-repair and colony formation ability of A2780 and SKOV-3 cancer cells. Furthermore, hAMSC-CM-derived exosomes induced apoptosis signalling by upregulating different pro-apoptotic signalling molecules, such as BAX, CASP9, and CASP3, as well as downregulating the anti-apoptotic protein BCL2. More specifically, cancer cells exhibited reduced viability following fresh or protease-digested exosome treatment; however, treatment with RNase-digested exosomes could not inhibit the proliferation of cancer cells. Additionally, sequencing of exosomal RNAs revealed a rich population of microRNAs (miRNAs), which exhibit anti-cancer activities by targeting different molecules associated with cancer survival. Our findings indicated that exosomal miRNAs are important players involved in the inhibitory influence of hAMSC-CM towards ovarian cancer cells. Therefore, we believe that these comprehensive results will provide advances concerning ovarian cancer research and treatment.

lncRNA UCA1 Contributes to Imatinib Resistance by Acting as a ceRNA Against miR-16 in Chronic Myeloid Leukemia Cells

Imatinib (IM) has been applied to the chronic phase of chronic myeloid leukemia (CML) and has great benefit on the prognosis of patients with CML. The function of drug efflux mediated by multidrug resistance protein-1 (MDR1) is considered as a main reason for IM drug resistance in CML cells. However, the exact mechanisms of MDR1 modulation in IM resistance of CML cells remain unclear. In the present study, long noncoding RNA (lncRNA) UCA1 was identified as an important modulator of MDR1 by a model system of leukemia cell lines with a gradual increase of MDR1 expression and IM resistance. Overexpression of UCA1 increased MDR1 expression to promote IM resistance of CML cells. Furthermore, for the first time, we demonstrated that UCA1 functions as a competitive endogenous (ceRNA) of MDR1 through completely binding the common miR-16. UCA1-MDR1 might be a novel target for enhancing the therapeutic efficacy of CML patients with IM resistance.

Atorvastatin attenuation of ABCB1 expression is mediated by microRNA miR-491-3p in Caco-2 cells

AIM

Atorvastatin, a HMG-CoA reductase inhibitor, used in the treatment of hypercholesterolemia, has been previously shown to regulate ABCB1 expression in vivo and in vitro. We hypothesized that the statin could regulate gene expression of ABCB1 transporter via microRNAs.

METHODS

Expression of microRNAs and ABCB1 mRNA was examined in atorvastatin-treated and control cells using real-time PCR. miR-491-3P mimic and inhibitor were transfected in Caco-2 and ABCB1 expression was monitored by western blot and real-time PCR.

RESULTS

In HepG2 cells, none of the microRNAs predicted to target ABCB1 3'UTR was regulated by atorvastatin treatment. In agreement with this, ABCB1 3'UTR activity was not modulated in HepG-2 cells after 48h-treatment as measured by luciferase assay. In Caco-2 cells, atorvastatin treatment provoked a decrease in luciferase activity and, accordingly, miR-491-3p was upregulated about 2.7 times after 48h-statin treatment. Luciferase analysis of miR-491-3p with a mimetic or inhibitor of miR-491-3p revealed that this microRNA could target ABCB1 3'UTR, as after miR-491-3p inhibition, ABCB1 levels were increased by two-fold, and miR-491-3p superexpression decreased ABCB1 3'UTR activity. Finally, functional analysis revealed that treatment with miR-491-3p inhibitor could reverses atorvastatin attenuation of ABCB1 (Pg-p) protein levels.

CONCLUSION

Our results suggest atorvastatin control ABCB1 expression via miR-491-3p in Caco-2 cells. This finding may be an important mechanism of statin drug-drug interaction, since common concomitant drugs used in the prevention of cardiovascular diseases are ABCB1 substrates.