Regulation of autophagy, NF-κB signaling, and cell viability by miR-124 in KRAS mutant mesenchymal-like NSCLC cells

Circular RNA HIPK2 Promotes A1 Astrocyte Activation after Spinal Cord Injury through Autophagy and Endoplasmic Reticulum Stress by Modulating miR-124-3p-Mediated Smad2 Repression

Glial scarring formed by reactive astrocytes after spinal cord injury (SCI) is the primary obstacle to neuronal regeneration within the central nervous system, making them a promising target for SCI treatment. Our previous studies have demonstrated the positive impact of miR-124-3p on neuronal repair, but it remains unclear how miR-124-3p is involved in autophagy or ER stress in astrocyte activation. To answer this question, the expression of A1 astrocyte-related markers at the transcriptional and protein levels after SCI was checked in RNA-sequencing data and verified using quantitative polymerase chain reaction (qPCR) and Western blotting in vitro and in vivo. The potential interactions among circHIPK2, miR-124-3p, and Smad2 were analyzed and confirmed by bioinformatics analyses and a luciferase reporter assay. In the end, the role of miR-124-3p in autophagy, ER stress, and SCI was investigated by using Western blotting to measure key biomarkers (C3, LC3, and Chop) in the absence or presence of corresponding selective inhibitors (siRNA, 4-PBA, TG). As a result, SCI caused the increase of A1 astrocyte markers, in which the upregulated circHIPK2 directly targeted miR-124-3p, and the direct downregulating effect of Smad2 by miR-124-3p was abolished, while Agomir-124 treatment reversed this effect. Injury caused a significant change of markers for ER stress and autophagy through the circHIPK2/miR-124-3p/Smad2 pathway, which might activate the A1 phenotype, and ER stress might promote autophagy in astrocytes. In conclusion, circHIPK2 may play a functional role in sequestering miR-124-3p and facilitating the activation of A1 astrocytes through regulating Smad2-mediated downstream autophagy and ER stress pathways, providing a new perspective on potential targets for functional recovery after SCI.

Distinct microRNA Signature and Suppression of ZFP36L1 Define ASCL1-Positive Lung Adenocarcinoma

Achaete-scute family bHLH transcription factor 1 (ASCL1) is a master transcription factor involved in neuroendocrine differentiation. ASCL1 is expressed in approximately 10% of lung adenocarcinomas (LUAD) and exerts tumor-promoting effects. Here, we explored miRNA profiles in ASCL1-positive LUADs and identified several miRNAs closely associated with ASCL1 expression, including miR-375, miR-95-3p/miR-95-5p, miR-124-3p, and members of the miR-17∼92 family. Similar to small cell lung cancer, Yes1 associated transcriptional regulator (YAP1), a representative miR-375 target gene, was suppressed in ASCL1-positive LUADs. ASCL1 knockdown followed by miRNA profiling in a cell culture model further revealed that ASCL1 positively regulates miR-124-3p and members of the miR-17∼92 family. Integrative transcriptomic analyses identified ZFP36 ring finger protein like 1 (ZFP36L1) as a target gene of miR-124-3p, and IHC studies demonstrated that ASCL1-positive LUADs are associated with low ZFP36L1 protein levels. Cell culture studies showed that ectopic ZFP36L1 expression inhibits cell proliferation, survival, and cell-cycle progression. Moreover, ZFP36L1 negatively regulated several genes including E2F transcription factor 1 (E2F1) and snail family transcriptional repressor 1 (SNAI1). In conclusion, our study revealed that suppression of ZFP36L1 via ASCL1-regulated miR-124-3p could modulate gene expression, providing evidence that ASCL1-mediated regulation of miRNAs shapes molecular features of ASCL1-positive LUADs.

IMPLICATIONS

Our study revealed unique miRNA profiles of ASCL1-positive LUADs and identified ASCL1-regulated miRNAs with functional relevance.

Regulation and therapeutic potentials of microRNAs to non-small cell lung cancer

Non-small cell lung cancer (NSCLC) is the most common type of lung cancer, accounting for 80%-85% of total cases and leading to millions of deaths worldwide. Drug resistance is the primary cause of treatment failure in NSCLC, which urges scientists to develop advanced approaches for NSCLC treatment. Among novel approaches, the miRNA-based method has emerged as a potential approach as it allows researchers to modulate target gene expression. Subsequently, cell behaviors are altered, which leads to the death and the depletion of cancer cells. It has been reported that miRNAs possess the capacity to regulate multiple genes that are involved in various signaling pathways, including the phosphoinositide 3-kinase, receptor tyrosine kinase/rat sarcoma virus/mitogen-activated protein kinase, wingless/integrated, retinoblastoma, p53, transforming growth factor β, and nuclear factor-kappa B pathways. Dysregulation of these signaling pathways in NSCLC results in abnormal cell proliferation, tissue invasion, and drug resistance while inhibiting apoptosis. Thus, understanding the roles of miRNAs in regulating these signaling pathways may enable the development of novel NSCLC treatment therapies. However, a comprehensive review of potential miRNAs in NSCLC treatment has been lacking. Therefore, this review aims to fill the gap by summarizing the up-to-date information on miRNAs regarding their targets, impact on cancer-associated pathways, and prospective outcomes in treating NSCLC. We also discuss current technologies for delivering miRNAs to the target cells, including virus-based, non-viral, and emerging extracellular vesicle-based delivery systems. This knowledge will support future studies to develop an innovative miRNA-based therapy and select a suitable carrier to treat NSCLC effectively.

MicroRNA (miR)-124: A Promising Therapeutic Gateway for Oncology

MicroRNA (miR) are a class of small non-coding RNA that are involved in post-transcriptional gene regulation. Altered expression of miR has been associated with several pathological conditions. MicroRNA-124 (miR-124) is an abundantly expressed miR in the brain as well as the thymus, lymph nodes, bone marrow, and peripheral blood mono-nuclear cells. It plays a key role in the regulation of the host immune system. Emerging studies show that dysregulated expression of miR-124 is a hallmark in several cancer types and it has been attributed to the progression of these malignancies. In this review, we present a comprehensive summary of the role of miR-124 as a promising therapeutic gateway in oncology.

Determining KLF14 tertiary structure and diagnostic significance in brain cancer progression

Expression analysis of new protein targets may play a crucial role in the early detection and diagnosis of brain tumor progression. The study aimed to investigate the possible relation of KLF14, TPD52, miR-124, and PKCε in the development and progression of brain cancer and space occupying lesion (SOL) of the brain. One hundred human blood samples comprising varying diagnostic groups (SOL brain, grade I, II, III, IV) were analyzed by real-time quantitative PCR to determine the expression level of KLF14, TPD52, miR-124, and PKCε. TPD52 and PKCε were upregulated in brain cancer by 2.5- and 1.6-fold, respectively, whereas, KLF14 and miR-124 were downregulated in brain cancer. In metastatic and high-grade brain cancer, TPD52 and PKCε expression were up-regulated and KLF14 and miR-124 expression were down-regulated. Further, these genes were found to be differentially expressed in the blood of patients with SOL. Upregulation of TPD52 and PKCε, however, reduced expression of KLF14 and miR-124 in SOL of the brain as compared to healthy controls. Expression analysis of TPD52, KLF14, miR-124, and PKCε provided useful information on the differences existing between the normal brain and SOL, in addition to gliomas; thus, might prove to be useful having diagnostic or prognostic value.

Improving Lipophagy by Restoring Rab7 Cycle: Protective Effects of Quercetin on Ethanol-Induced Liver Steatosis

Chronic alcohol consumption retards lipophagy, which contributes to the pathogenesis of liver steatosis. Lipophagy-related Rab7 has been presumed as a crucial regulator in the progression of alcohol liver disease despite elusive mechanisms. More importantly, whether or not hepatoprotective quercetin targets Rab7-associated lipophagy disorder is unknown. Herein, alcoholic fatty liver induced by chronic-plus-single-binge ethanol feeding to male C57BL/6J mice was manifested by hampering autophagosomes formation with lipid droplets and fusion with lysosomes compared with the normal control, which was normalized partially by quercetin. The GST-RILP pulldown assay of Rab7 indicated an improved GTP-Rab7 as the quercetin treatment for ethanol-feeding mice. HepG2 cells transfected with CYP2E1 showed similar lipophagy dysfunction when exposed to ethanol, which was blocked when cells were transfected with siRNA-Rab7 in advance. Ethanol-induced steatosis and autophagic flux disruption were aggravated by the Rab7-specific inhibitor CID1067700 while alleviated by transfecting with the Rab7Wt plasmid, which was visualized by immunofluorescence co-localization analysis and mCherry-GFP-LC3 transfection. Furthermore, TBC1D5, a Rab GTPase-activating protein for the subsequent normal circulation of Rab7, was downregulated after alcohol administration but regained by quercetin. Rab7 circulation retarded by ethanol and corrected by quercetin was further revealed by fluorescence recovery after photobleaching (FRAP). Altogether, quercetin attenuates hepatic steatosis by normalizing ethanol-imposed Rab7 turnover disorders and subsequent lipophagy disturbances, highlighting a novel mechanism and the promising prospect of quercetin-like phytochemicals against the crucial first hit from alcohol.

Hsa_circ_0006677 regulates special AT-rich binding protein-2-mediated tumor-suppressive effect via functioning as a miR-1245a sponge in non-small cell lung cancer

Non-small cell lung cancer (NSCLC) is still one of the most challenging malignant tumors. Deregulation of circular RNAs (circRNAs) is associated with NSCLC progression. However, the regulatory mechanism of circRNAs in NSCLC still needs to be studied. We selected a differentially expressed hsa_circ_0006677 (circ_0006677) in NSCLC through analyzing the GSE158695 and GSE112214 datasets. Expression of circ_0006677 was evaluated by real-time quantitative polymerase-chain reaction (RT-qPCR). Effects of circ_0006677 overexpression on NSCLC cell proliferation, apoptosis, migration, invasion, and stemness were determined by clonogenic, 5-ethynyl-2’-deoxyuridine (EdU), flow cytometry, transwell, and sphere formation assays. The regulatory mechanism of circ_0006677 was predicted by bioinformatics analysis and verified by dual-luciferase reporter and RIP assays. Animal experiments were carried out to validate the function of circ_0006677 in vivo. We observed the downregulation of circ_0006677 in NSCLC samples and cells. Functionally, circ_0006677 overexpression decreased xenograft tumor growth and restrained NSCLC cell proliferation, invasion, migration, stemness, and induced NSCLC cell apoptosis in vitro. Molecular mechanism experiments exhibited that circ_0006677 functioned as a miR-1245a sponge and mediated SATB2 expression through adsorbing miR-1245a. Either miR-1245a overexpression or SATB2 knockdown weakened circ_0006677 overexpression-mediated repression on proliferation, invasion, migration, and stemness. In conclusion, circ_0006677 regulated SATB2-mediated tumor-suppressive effect via acting as a miR-1245a sponge in NSCLC, providing a new mechanism for understanding the progression of NSCLC.

Tumor Suppressive Effects of miR-124 and Its Function in Neuronal Development

MicroRNA-124 (miR-124) is strongly expressed in neurons, and its expression increases as neurons mature. Through DNA methylation in the miR-124 promoter region and adsorption of miR-124 by non-coding RNAs, miR-124 expression is known to be reduced in many cancer cells, especially with high malignancy. Recently, numerous studies have focused on miR-124 due to its promising tumor-suppressive effects; however, the overview of their results is unclear. We surveyed the tumor-suppressive effect of miR-124 in glial cell lineage cancers, which are the most frequently reported cancer types involving miR-124, and in lung, colon, liver, stomach, and breast cancers, which are the top five causes of cancer death. Reportedly, miR-124 not only inhibits proliferation and accelerates apoptosis, but also comprehensively suppresses tumor malignant transformation. Moreover, we found that miR-124 exerts its anti-tumor effects by regulating a wide range of target genes, most notably STAT3 and EZH2. In addition, when compared to the original role of miR-124 in neuronal development, we found that the miR-124 target genes that contribute to neuronal maturation share similarities with genes that cause cancer cell metastasis and epithelial-mesenchymal transition. We believe that the two apparently unrelated fields, cancer and neuronal development, can bring new discoveries to each other through the study of miR-124.

Regulation of Nuclear Factor-KappaB (NF-κB) signaling pathway by non-coding RNAs in cancer: Inhibiting or promoting carcinogenesis?

The nuclear factor-kappaB (NF-κB) signaling pathway is considered as a potential therapeutic target in cancer therapy. It has been well established that transcription factor NF-κB is involved in regulating physiological and pathological events including inflammation, immune response and differentiation. Increasing evidences suggest that deregulated NF-κB signaling can enhance cancer cell proliferation, metastasis and also mediate radio-as well as chemo-resistance. On the contrary, non-coding RNAs (ncRNAs) have been found to modulate NF-κB signaling pathway under different settings. MicroRNAs (miRNAs) can dually inhibit/induce NF-κB signaling thereby affecting the growth and migration of cancer cells. Furthermore, the response of cancer cells to radiotherapy and chemotherapy may also be regulated by miRNAs. Regulation of NF-κB by miRNAs may be mediated via binding to 3^/-UTR region. Interestingly, anti-tumor compounds can increase the expression of tumor-suppressor miRNAs in inhibiting NF-κB activation and the progression of cancers. Long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs) can also effectively modulate NF-κB signaling thus affecting tumorigenesis. It is noteworthy that several studies have demonstrated that lncRNAs and circRNAs can affect miRNAs in targeting NF-κB activation. They can act as competing endogenous RNA (ceRNA) thereby reducing miRNA expression to induce NF-κB activation that can in turn promote cancer progression and malignancy.

MiR-124-3p helps to protect against acute respiratory distress syndrome by targeting p65

Background: Acute respiratory distress syndrome (ARDS) is a severe form of acute lung injury that has a high mortality rate and leads to substantial healthcare costs. MicroRNA-124-3p (miR-124-3p) helps to suppress inflammation during a pulmonary injury. However, its mechanism of action is largely unknown, and its role in ARDS remains to be determined.

Methods: Mice and NR8383 cells were exposed to lipopolysaccharides (LPS) to induce ARDS, and their miR-124-3p levels were determined. After a miRNA agomir was administrated to the mice, their pulmonary injuries were evaluated by H&E staining and assays for peripheral inflammatory cytokine levels. The direct interaction between miR-124-3p and p65 was predicted, and then confirmed by a luciferase activity assay. The role played by miRNA-124-3p in regulating p65 expression was further examined by transfection with its agomir, and its role in cell apoptosis was investigated by observing the effects of miRNA overexpression in vitro and in vivo.

Results: After exposure to LPS, there was a consistent decrease in miR-124-3p expression in the lungs of mice and in NR8383 cells. After treatment with the miR-124-3p agomir, the degrees of pulmonary injury (e.g. alveolar hemorrhage and interstitial edema), and the increases in IL-1β, IL-6, and TNF-α levels induced by LPS were significantly attenuated. Overexpression of miR-124-3p in NC8383 cells and lung tissues significantly suppressed LPS-induced p65 expression and cell apoptosis.

Conclusions: These results suggest that miR-124-3p directly targeted p65, and thereby decreased the levels of inflammation and pulmonary injury in a mouse model of ARDS.

Unravelling Structure, Localization, and Genetic Crosstalk of KLF3 in Human Breast Cancer

Breast cancer is the most prevailing disease among women. It actually develops from breast tissue and has heterogeneous and complex nature that constitutes multiple tumor quiddities. These features are associated with different histological forms, distinctive biological characteristics, and clinical patterns. The predisposition of breast cancer has been attributed to a number of genetic factors, associated with the worst outcomes. Unfortunately, their behavior with relevance to clinical significance remained poorly understood. So, there is a need to further explore the nature of the disease at the transcriptome level. The focus of this study was to explore the influence of Krüppel-like factor 3 (KLF3), tumor protein D52 (TPD52), microRNA 124 (miR-124), and protein kinase C epsilon (PKCε) expression on breast cancer. Moreover, this study was also aimed at predicting the tertiary structure of KLF3 protein. Expression of genes was analyzed through real-time PCR using the delta cycle threshold method, and statistical significance was calculated by two-way ANOVA in Graphpad Prism. For the construction of a 3D model, various bioinformatics software programs, Swiss Model and UCSF Chimera, were employed. The expression of KLF3, miR-124, and PKCε genes was decreased (fold change: 0.076443, 0.06969, and 0.011597, respectively). However, there was 2-fold increased expression of TPD52 with p value < 0.001 relative to control. Tertiary structure of KLF3 exhibited 80.72% structure conservation with its template KLF4 and was 95.06% structurally favored by a Ramachandran plot. These genes might be predictors of stage, metastasis, receptor, and treatment status and used as new biomarkers for breast cancer diagnosis. However, extensive investigations at the tissue level and in in vivo are required to further strengthen their role as a potential biomarker for prognosis of breast cancer.

MicroRNA-3613-5p Promotes Lung Adenocarcinoma Cell Proliferation through a RELA and AKT/MAPK Positive Feedback Loop

Aberrant activation of nuclear factor κB (NF-κB)/RELA is often found in lung adenocarcinoma (LUAD). In this study, we determined that microRNA-3613-5p (miR-3613-5p) plays a crucial role in RELA-mediated post-transcriptional regulation of LUAD cell proliferation. Expression of miR-3613-5p in clinical LUAD specimens is associated with poor prognosis in LUAD. Upregulation of miR-3613-5p promotes LUAD cell proliferation in vitro and in vivo. Our results suggested a mechanism whereby miR-3613-5p expression is induced by RELA through its direct interaction with JUN, thereby stimulating the AKT/mitogen-activated protein kinase (MAPK) pathway by directly targeting NR5A2. In addition, we also found that phosphorylation of AKT1 and MAPK3/1 co-transactivates RELA, thus constituting a RELA/JUN/miR-3613-5p/NR5A2/AKT1/MAPK3/1 positive feedback loop, leading to persistent NF-κB activation. Our findings also revealed that miR-3613-5p plays an oncogenic role in LUAD by promoting cell proliferation and acting as a key regulator of the positive feedback loop underlying the link between the NF-κB/RELA and AKT/MAPK pathways.

CDYL2 Epigenetically Regulates MIR124 to Control NF-κB/STAT3-Dependent Breast Cancer Cell Plasticity

Epigenetic deregulation of gene transcription is central to cancer cell plasticity and malignant progression but remains poorly understood. We found that the uncharacterized epigenetic factor chromodomain on Y-like 2 (CDYL2) is commonly over-expressed in breast cancer, and that high CDYL2 levels correlate with poor prognosis. Supporting a functional role for CDYL2 in malignancy, it positively regulated breast cancer cell migration, invasion, stem-like phenotypes, and epithelial-to-mesenchymal transition. CDYL2 regulation of these plasticity-associated processes depended on signaling via p65/NF-κB and STAT3. This, in turn, was downstream of CDYL2 regulation of MIR124 gene transcription. CDYL2 co-immunoprecipitated with G9a/EHMT2 and GLP/EHMT1 and regulated the chromatin enrichment of G9a and EZH2 at MIR124 genes. We propose that CDYL2 contributes to poor prognosis in breast cancer by recruiting G9a and EZH2 to epigenetically repress MIR124 genes, thereby promoting NF-κB and STAT3 signaling, as well as downstream cancer cell plasticity and malignant progression.

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Up-regulation of CDYL2 is common in breast cancer and correlates with poor prognosis

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CDYL2 regulates enrichment of methyltransferases G9a and EZH2 at MIR124 genes

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microRNA-124 regulation by CDYL2 impacts STAT3 and NF-κB signaling

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CDYL2 regulation of EMT, migration, invasion, and stemness is STAT3/NF-κB dependent

Circular RNA circHIPK3 modulates autophagy via MIR124-3p-STAT3-PRKAA/AMPKα signaling in STK11 mutant lung cancer

The role of circular RNA in cancer is emerging. A newly reported circular RNA HIPK3 (circHIPK3) is critical in cell proliferation of various cancer types, although its role in non-small cell lung cancer (NSCLC), has yet to be elucidated. Our results provided evidence that silencing of circHIPK3 significantly impaired cell proliferation, migration, invasion and induced macroautophagy/autophagy. Mechanistically, we uncovered that autophagy was induced upon loss of circHIPK3 via the MIR124-3p-STAT3-PRKAA/AMPKa axis in STK11 mutant lung cancer cell lines (A549 and H838). STAT3 abrogation as well as transfection with a MIR124-3p mimic, recapitulated the induction of autophagy. We also demonstrated antagonistic regulation on autophagy between circHIPK3 and linear HIPK3 (linHIPK3). We therefore propose that the ratio between circHIPK3 and linHIPK3 (C:L ratio) may reflect autophagy levels in cancer cells. We observed that a high C:L ratio (>0.49) was an indicator of poor survival, especially in advanced-stage NSCLC patients. These results support that circHIPK3 is a key autophagy regulator in a subset of lung cancer and has potential clinical use as a prognostic factor. The circular RNA HIPK3 (circHIPK3) functions as an oncogene and autophagy regulator may potential use as a prognostic marker and therapeutic target in lung cancer.Abbreviations 3-MA: 3-methyladenine; AMPK: AMP-activated protein kinase; ATG7: autophagy related 7; Baf-A: bafilomycin A1; BECN1: beclin 1; circHIPK3: circular HIPK3; CQ: chloroquine; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; GFP: green fluorescent protein; HIPK3: homeodomain interacting protein kinase 3; IL6R: interleukin 6 receptor; MAP1LC3B/LC3B: microtubule associated protein 1 light chain 3 beta; NSCLC: non-small cell lung cancer; RFP: red fluorescent protein; RPS6KB1/S6K: ribosomal protein S6 kinase B1; SQSTM1/p62: sequestosome 1; STAT3: signal transducer and activator of transcription 3; STK11: serine/threonine kinase 11.

Circular RNA circHIPK3 modulates autophagy via MIR124-3p-STAT3-PRKAA/AMPKα signaling in STK11 mutant lung cancer

The role of circular RNA in cancer is emerging. A newly reported circular RNA HIPK3 (circHIPK3) is critical in cell proliferation of various cancer types, although its role in non-small cell lung cancer (NSCLC), has yet to be elucidated. Our results provided evidence that silencing of circHIPK3 significantly impaired cell proliferation, migration, invasion and induced macroautophagy/autophagy. Mechanistically, we uncovered that autophagy was induced upon loss of circHIPK3 via the MIR124-3p-STAT3-PRKAA/AMPKa axis in STK11 mutant lung cancer cell lines (A549 and H838). STAT3 abrogation as well as transfection with a MIR124-3p mimic, recapitulated the induction of autophagy. We also demonstrated antagonistic regulation on autophagy between circHIPK3 and linear HIPK3 (linHIPK3). We therefore propose that the ratio between circHIPK3 and linHIPK3 (C:L ratio) may reflect autophagy levels in cancer cells. We observed that a high C:L ratio (>0.49) was an indicator of poor survival, especially in advanced-stage NSCLC patients. These results support that circHIPK3 is a key autophagy regulator in a subset of lung cancer and has potential clinical use as a prognostic factor. The circular RNA HIPK3 (circHIPK3) functions as an oncogene and autophagy regulator may potential use as a prognostic marker and therapeutic target in lung cancer.Abbreviations 3-MA: 3-methyladenine; AMPK: AMP-activated protein kinase; ATG7: autophagy related 7; Baf-A: bafilomycin A₁; BECN1: beclin 1; circHIPK3: circular HIPK3; CQ: chloroquine; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; GFP: green fluorescent protein; HIPK3: homeodomain interacting protein kinase 3; IL6R: interleukin 6 receptor; MAP1LC3B/LC3B: microtubule associated protein 1 light chain 3 beta; NSCLC: non-small cell lung cancer; RFP: red fluorescent protein; RPS6KB1/S6K: ribosomal protein S6 kinase B1; SQSTM1/p62: sequestosome 1; STAT3: signal transducer and activator of transcription 3; STK11: serine/threonine kinase 11.

MicroRNAs as major regulators of the autophagy pathway

Autophagy is a cellular stress response mechanism activation of which leads to degradation of cellular components, including proteins as well as damaged organelles in lysosomes. Defects in autophagy mechanisms were associated with several pathologies (e.g. cancer, neurodegenerative diseases, and rare genetic diseases). Therefore, autophagy regulation is under strict control. Transcriptional and post-translational mechanisms that control autophagy in cells and organisms studied in detail. Recent studies introduced non-coding small RNAs, and especially microRNAs (miRNAs) in the post-translational orchestration of the autophagic activity. In this review article, we analyzed in detail the current status of autophagy-miRNA connections. Comprehensive documentation of miRNAs that were directly involved in autophagy regulation resulted in the emergence of common themes and concepts governing these complex and intricate interactions. Hence, a better and systematic understanding of these interactions reveals a central role for miRNAs in the regulation of autophagy.

ATRA induces the differentiation of hepatic progenitor cells by upregulating microRNA-200a

Hepatic progenitor cells (HPCs) are potential seed cells for hepatocyte transplantation treatment of liver diseases. ATRA can induce the differentiation and mature function of hepatic progenitor cells, but the mechanism is still poorly understood. Here, by using microRNA array to analyze the expression profiles of microRNA (miR), we found that miR-200 family molecules in HPCs were upregulated after ATRA treatment, especially miR-200a-3p, 200c-3p, and 141-3p. ATRA induction could downregulate the expression of hepatic stem markers Oct4 and AFP, and improve the expression of hepatic markers ALB, CK18, and TAT, and the activity of ALB-GLuc, as well as indocyanine green uptake and glycogen storage function of HPCs. These above effects of ATRA on HPC differentiation were almost inhibited by blocking of miR-200a-3p, but not miR-200c-3p and 141-3p using antagomir. Cell autophagy is associated with ATRA regulation in HPCs, compared with control group, the expression of LC3 and Beclin1 increased in ATRA-treated HPCs, and orange and red fluorescent spot, which represents autophagy flow, also enhanced after ATRA treatment. However, ATRA-induced cell autophagy level was inhibited in antagomir-200a-3p+ATRA-treated cells. Therefore, the present study indicates that antagomir-200a-3p is related to ATRA-induced hepatic differentiation of HPCs through regulating cell autophagy, supporting the possible use of ATRA as a key inducer in HPC-based therapy of liver diseases.

Increases in miR-124-3p in Microglial Exosomes Confer Neuroprotective Effects by Targeting FIP200-Mediated Neuronal Autophagy Following Traumatic Brain Injury

In our recent study, we observed consistent increases in miR-124-3p levels in exosomes derived from cultured BV2 microglia which was treated with repetitive traumatic brain injury (rTBI) mouse model brain extracts. To clarify the mechanisms underlying increases in microglia-derived exosomal miR-124-3p and their role in regulating neuronal autophagy after TBI, we investigated the impact of exosomal miR-124-3p on neuronal autophagy in scratch-injured HT22 neurons and rTBI mice. We harvested injured brain extracts from rTBI mice at 3 to 21 days post injury (DPI) for the treatment of cultured BV2 microglia in vitro. We observed significant induction of autophagy following TBI in vitro, and that inhibition of activated neuronal autophagy could protect against trauma-induced injury. Our results indicated that co-culture of injured HT22 neurons with miR-124-3p overexpressing BV2 microglia exerted a protective effect by inhibiting neuronal autophagy in scratch-injured neurons. Further research revealed that these effects were achieved mainly via upregulation of exosomal miR-124-3p, and that Focal adhesion kinase family-interacting protein of 200 kDa (FIP200) plays a key role in trauma-induced autophagy. Injection of exosomes into the vena caudalis in in vivo experiments revealed that exosomal miR-124-3p was associated with decreases in the modified neurological severity score (mNSS) and improvements in Morris water maze (MWM) test results in rTBI mice. Altogether, our results indicate that increased miR-124-3p in microglial exosomes following TBI may inhibit neuronal autophagy and protect against nerve injury via their transfer into neurons. Thus, treatment with microglial exosomes enriched with miR-124-3p may represent a novel therapeutic strategy for the treatment of nerve injury after TBI.

Diagnostic value of serum miR197 and miR145 in non-small cell lung cancer

Diagnostic value of microRNA (miR)-197 and miR-145 in non-small cell lung cancer (NSCLC) and their relationship with the clinicopathological parameters of NSCLC patients were investigated. Seventy-six patients with NSCLC admitted to Jimo Hospital of Traditional Chinese Medicine from July 2016 to March 2018 were enrolled in group A, while 60 healthy who received health examinations during the same period were enrolled in group B. The relative expression levels of serum miR-197 and miR-145 were detected by RT-qPCR. The relative expression of serum miR-197 in group A was significantly higher than that in group B (P<0.001); the relative expression of serum miR-145 in group A was significantly lower than that in group B (P<0.001); serum miR-197 in group A showed association with the clinical stage of NSCLC patients (P<0.001); serum miR-145 in group A was associated with the clinical stage and pathological differentiation of patients with NSCLC (P<0.001). The AUC of serum miR-197 diagnosis of NSCLC was 0.864 (95% CI: 0.804-0.924), with a diagnostic sensitivity of 73.68% and a specificity of 85.00%; the AUC of serum miR-145 diagnosis of NSCLC was 0.879 (95% CI: 0.824-0.934), with a diagnostic sensitivity of 84.21% and a specificity of 71.67%; the AUC of the diagnosis of the combination of serum miR-197 and miR-145 for NSCLC was 0.952 (95% CI: 0.919-0.984), with a diagnostic sensitivity of 92.10% and a specificity of 78.33%. miR-197 and miR-145 are potential new biomarkers in the diagnosis of NSCLC due to their possible involvement in the occurrence and development of NSCLC. With good sensitivity and specificity of single miR-197 and single miR-145 for the diagnosis of NSCLC, the combined detection of miR-197 and miR-145 can achieve a better sensitivity in the diagnosis of NSCLC.

Targeting EphA2 with miR-124 mediates Erlotinib resistance in K-RAS mutated pancreatic cancer

OBJECTIVES

Chemotheraputic drug resistance is a critical factor associated with the poor survival in advanced/metastatic pancreatic cancer (PC) patients.

METHODS

Human pancreatic cell lines Capan-1 and BXPC-3 were cultured with different concentrations of erlotinib (0, 10, 50, and 100 μm) for 48 h. The relative cell viability and apoptosis was detected using MTT assays and flow cytometry apoptosis analysis, respectively. Transfection of pcDNA-EphA2, si-EphA2 and miR-124 mimic/inhibitor was used to modulate the intracellular level of EphA2 and miR-124. The interaction between miR-124 and the 3'UTR of EphA2 was explored using dual luciferase reporter assay.

KEY FINDINGS

Compared with BXPC-3 cells, Capan-1 cells showed resistance to differential concentration treatment of erlotinib. The expression of EphA-2 was significantly increased and the expression of miR-124 was significantly decreased in Capan-1 cells. Overexpressing EphA2 induced resistance of BXPC-3 cells to erlotinib treatment. And EphA2 was identified as a novel target gene for miR-124. MiR-124 overexpression was able to sensitize the response of Capan-1 cells to erlotinib through inhibiting EphA2. Furthermore, both miR-124 overexpression and EphA2 inhibition sensitized Capan-1 cells to erlotinib in xenograft model.

CONCLUSIONS

Our study demonstrated that EphA2 rescued by miR-124 downregulation conferred the erlotinib resistance of PC cell Capan-1 with K-RAS mutation.

Oncogene-induced regulation of microRNA expression: Implications for cancer initiation, progression and therapy

A plethora of tumours have characteristic oncogenic mutations which are the main causes of malignant transformation, exerting their effects through multiple signalling pathways. Downstream of such pathways, microRNAs are small non-coding RNAs that negatively regulate gene expression, assisting or antagonizing oncogenic signalling. The differential expression of microRNAs in cancer is well-documented and is considered a fundamental aspect of tumourigenesis. While data mapping the interaction between oncogenic lesions and microRNAs are accruing, we provide particular cases of such interaction. Except for notable, well-studied examples of microRNAs regulated by oncogenes, we examine the effect of this relationship in regard to tumour initiation, progression, metastasis and ultimately, its implications for the development of new therapeutics.

From Oxidative Stress Damage to Pathways, Networks, and Autophagy via MicroRNAs

Oxidative stress can alter the expression level of many microRNAs (miRNAs), but how these changes are integrated and related to oxidative stress responses is poorly understood. In this article, we addressed this question by using in silico tools. We reviewed the literature for miRNAs whose expression is altered upon oxidative stress damage and used them in combination with various databases and software to predict common gene targets of oxidative stress-modulated miRNAs and affected pathways. Furthermore, we identified miRNAs that simultaneously target the predicted oxidative stress-modulated miRNA gene targets. This generated a list of novel candidate miRNAs potentially involved in oxidative stress responses. By literature search and grouping of pathways and cellular responses, we could classify these candidate miRNAs and their targets into a larger scheme related to oxidative stress responses. To further exemplify the potential of our approach in free radical research, we used our explorative tools in combination with ingenuity pathway analysis to successfully identify new candidate miRNAs involved in the ubiquitination process, a master regulator of cellular responses to oxidative stress and proteostasis. Lastly, we demonstrate that our approach may also be useful to identify novel candidate connections between oxidative stress-related miRNAs and autophagy. In summary, our results indicate novel and important aspects with regard to the integrated biological roles of oxidative stress-modulated miRNAs and demonstrate how this type of in silico approach can be useful as a starting point to generate hypotheses and guide further research on the interrelation between miRNA-based gene regulation, oxidative stress signaling pathways, and autophagy.