MALAT1 binds to miR-188-3p to regulate ALOX5 activity in the lung inflammatory response of neonatal bronchopulmonary dysplasia.

Bronchopulmonary dysplasia (BPD) causes high morbidity and mortality in infants, but no effective preventive or therapeutic agents have been developed to combat BPD. In this study, we assessed the expression of MALAT1 and ALOX5 in peripheral blood mononuclear cells from BPD neonates, hyperoxia-induced rat models and lung epithelial cell lines. Interestingly, we found upregulated expression of MALAT1 and ALOX5 in the experimental groups, along with upregulated expression of proinflammatory cytokines. According to bioinformatics prediction, MALAT1 and ALOX5 simultaneously bind to miR-188-3p, which was downregulated in the experimental groups above. Silencing MALAT1 or ALOX5 and overexpressing miR-188-3p inhibited apoptosis and promoted the proliferation of hyperoxia-treated A549 cells. Suppressing MALAT1 or overexpressing miR-188-3p increased the expression levels of miR-188-3p but decreased the expression levels of ALOX5. Moreover, RNA immunoprecipitation (RIP) and luciferase assays showed that MALAT1 directly targeted miR-188-3p to regulate ALOX5 expression in BPD neonates. Collectively, our study demonstrates that MALAT1 regulates ALOX5 expression by binding to miR-188-3p, providing novel insights into potential therapeutics for BPD treatment.

Heme oxygenase­1 inhibits renal tubular epithelial cell pyroptosis by regulating mitochondrial function through PINK1.

Endotoxin-induced acute kidney injury (AKI) is commonly observed in clinical practice. Renal tubular epithelial cell (RTEC) pyroptosis is one of the main factors leading to the development of endotoxin-induced AKI. Mitochondrial dysfunction can lead to pyroptosis. However, the biological pathways involved in the potential lipopolysaccharide (LPS)-induced pyroptosis of RTECs, notably those associated with mitochondrial dysfunction, are poorly understood. Previous studies have demonstrated that heme oxygenase (HO)-1 confers cell protection via the induction of PTEN-induced putative kinase 1 (PINK1) expression through PTEN to regulate mitochondrial fusion/fission during endotoxin-induced AKI in vivo. Therefore, the present study investigated the role of HO-1/PINK1 in maintaining mitochondrial function and inhibiting the pyroptosis of RTECs exposed to LPS. Primary cultures of RTECs were obtained from wild-type (WT) and PINK1-knockout (PINK1KO) rats. An in vitro model of endotoxin-associated RTEC injury was established following treatment of the cells with LPS. The WT RTECs were divided into the control, LPS, Znpp + LPS and Hemin + LPS groups, and the PINK1KO RTECs were divided into the control, LPS and Hemin + LPS groups. RTECs were exposed to LPS for 6 h to assess cell viability, inflammation, pyroptosis and mitochondrial function. In the LPS-treated RTECs, the mRNA and protein expression levels of HO-1 and PINK1 were upregulated. Cell viability, adenosine triphosphate (ATP) levels and the mitochondrial oxygen consumption rate were decreased, whereas the inflammatory response, pyroptosis and mitochondrial reactive oxygen species (ROS) levels were increased. The cell inflammatory response and the induction of pyroptosis were inhibited, whereas the levels of mitochondrial ROS were decreased. In addition, the cell viability and ATP levels were increased in the WT RTECs following the upregulation of HO-1 expression. These effects were reversed by the downregulation of HO-1 expression. However, no statistically significant differences were noted between the LPS and the Hemin + LPS groups in the PINK1KO RTECs. Collectively, the findings of the present study indicate that HO-1 inhibits inflammation and regulates mitochondrial function by inhibiting the pyroptosis of LPS-exposed RTECs via PINK1.

Magnolol protects against acute gastrointestinal injury in sepsis by down-regulating regulated on activation, normal T-cell expressed and secreted.

BACKGROUND: Sepsis is a major medical challenge. Magnolol is an active constituent of Houpu that improves tissue function and exerts strong anti-endotoxin and anti-inflammatory effects, but the mechanism by which it reduces intestinal inflammation in sepsis is yet unclear. AIM: To assess the protective effect of magnolol on intestinal mucosal epithelial cells in sepsis and elucidate the underlying mechanisms. METHODS: Enzyme-linked immunosorbent assay was used to measure tumor necrosis factor-α (TNF-α), interleukin-1ß (IL-1ß), IL-6, and regulated on activation, normal T-cell expressed and secreted (RANTES) levels in serum and ileal tissue in animal studies. The histopathological changes of the ileal mucosa in different groups were observed under a microscope. Cell Counting Kit-8 and cell permeability assays were used to determine the concentration of drug-containing serum that did not affect the activity of Caco2 cells but inhibited lipopolysaccharide (LPS)-induced decrease in permeability. Immunofluorescence and Western blot assays were used to detect the levels of RANTES, inhibitor of nuclear factor kappa-B kinase ß (IKKß), phosphorylated IKKß (p-IKKß), inhibitor of nuclear factor kappa-B kinase α (IκBα), p65, and p-p65 proteins in different groups in vitro. RESULTS: In rats treated with LPS by intravenous tail injection in the presence or absence of magnolol, magnolol inhibited the expression of proinflammatory cytokines, IL-1ß, IL-6, and TNF-α in a dose-dependent manner. In addition, magnolol suppressed the production of RANTES in LPS-stimulated sepsis rats. Moreover, in vitro studies suggested that magnolol inhibited the increase of p65 nucleation, thereby markedly downregulating the production of the phosphorylated form of IKKß in LPS-treated Caco2 cells. Specifically, magnolol inhibited the translocation of the transcription factor nuclear factor-kappa B (NF-κB) from the cytosol into the nucleus and down-regulated the expression level of the chemokine RANTES in LPS-stimulated Caco2 cells. CONCLUSION: Magnolol down-regulates RANTES levels by inhibiting the LPS/NF-κB signaling pathways, thereby suppressing IL-1ß, IL-6, and TNF-α expression to alleviate the mucosal barrier dysfunction in sepsis.

Promotion of Bronchopulmonary Dysplasia Progression Using Circular RNA circabcc4 via Facilitating PLA2G6 Expression by Sequestering miR-663a.

Circular RNA (circRNA) has been increasingly proven as a new type of promising therapeutic RNA molecule in a variety of human diseases. However, the role of circRNA in bronchopulmonary dysplasia (BPD) has not yet been elucidated. Here, a new circRNA circABCC4 was identified from the Agilent circRNA chip as a differentially expressed circRNA in BPD. The relationship between circABCC4 level and BPD clinicopathological characteristics was analyzed. The function of circABCC4 was evaluated by performing CCK-8 and apoptosis analysis in vitro and BPD model analysis in vivo. RNA immunoprecipitation (RIP), luciferase reporter and rescue experiments were used to elucidate the interaction between circABCC4 and miR-663a. Luciferase reporter assay and rescue experiments were used to elucidate the interaction between PLA2G6 and miR-663a. CircABCC4 and PLA2G6 levels were increased, while miR-663a levels were decreased in the BPD group, compared to the control group. MiR-663a inhibited apoptosis by repressing PLA2G6 expression, while circABCC4 enhanced the apoptosis and inhibited the proliferation of A549 cells by sponging miR-663a and increasing PLA2G6 expression. In conclusion, circABCC4 promotes the evolving of BPD by spongening miR-663a and up-regulating PLA2G6 expression, which makes circABCC4 an ideal molecular target for early diagnosis and intervention of BPD.

Porphyromonas gingivalis promotes progression of esophageal squamous cell cancer via TGFß-dependent Smad/YAP/TAZ signaling.

Microbial dysbiosis in the upper digestive tract is linked to an increased risk of esophageal squamous cell carcinoma (ESCC). Overabundance of Porphyromonas gingivalis is associated with shorter survival of ESCC patients. We investigated the molecular mechanisms driving aggressive progression of ESCC by P. gingivalis. Intracellular invasion of P. gingivalis potentiated proliferation, migration, invasion, and metastasis abilities of ESCC cells via transforming growth factor-ß (TGFß)-dependent Drosophila mothers against decapentaplegic homologs (Smads)/Yes-associated protein (YAP)/Transcriptional coactivator with PDZ-binding motif (TAZ) activation. Smads/YAP/TAZ/TEA domain transcription factor1 (TEAD1) complex formation was essential to initiate downstream target gene expression, inducing an epithelial-mesenchymal transition (EMT) and stemness features. Furthermore, P. gingivalis augmented secretion and bioactivity of TGFß through glycoprotein A repetitions predominant (GARP) up-regulation. Accordingly, disruption of either the GARP/TGFß axis or its activated Smads/YAP/TAZ complex abrogated the tumor-promoting role of P. gingivalis. P. gingivalis signature genes based on its activated effector molecules can efficiently distinguish ESCC patients into low- and high-risk groups. Targeting P. gingivalis or its activated effectors may provide novel insights into clinical management of ESCC.

Long non-coding RNA MALAT1 targeting STING transcription promotes bronchopulmonary dysplasia through regulation of CREB.

Bronchopulmonary dysplasia (BPD) is a severe complication of preterm infants characterized by increased alveolarization and inflammation. Premature exposure to hyperoxia is believed to be a key contributor to the pathogenesis of BPD. No effective preventive or therapeutic agents have been created. Stimulator of interferon gene (STING) is associated with inflammation and apoptosis in various lung diseases. Long non-coding RNA MALAT1 has been reported to be involved in BPD. However, how MALAT1 regulates STING expression remains unknown. In this study, we assessed that STING and MALAT1 were up-regulated in the lung tissue from BPD neonates, hyperoxia-based rat models and lung epithelial cell lines. Then, using the flow cytometry and cell proliferation assay, we found that down-regulating of STING or MALAT1 inhibited the apoptosis and promoted the proliferation of hyperoxia-treated cells. Subsequently, qRT-PCR, Western blotting and dual-luciferase reporter assays showed that suppressing MALAT1 decreased the expression and promoter activity of STING. Moreover, transcription factor CREB showed its regulatory role in the transcription of STING via a chromatin immunoprecipitation. In conclusion, MALAT1 interacts with CREB to regulate STING transcription in BPD neonates. STING, CREB and MALAT1 may be promising therapeutic targets in the prevention and treatment of BPD.

G-CSF Inhibits Pulmonary Fibrosis by Promoting BMSC Homing to the Lungs via SDF-1/CXCR4 Chemotaxis.

Bone marrow mesenchymal stem cells (BMSCs) have multi-lineage differentiation potential and play an important role in tissue repair. Studies have shown that BMSCs gather at the injured tissue site after granulocyte-colony stimulating factor (G-CSF) administration. In this study, we first investigated whether G-CSF could promote BMSC homing to damaged lung tissue induced by bleomycin (BLM) and then investigated whether SDF-1/CXCR4 chemotaxis might be involved in this process. Next, we further studied the potential inhibitory effect of G-CSF administration in mice with lung fibrosis induced by bleomycin. We examined both the antifibrotic effects of G-CSF in mice with bleomycin-induced pulmonary fibrosis in vivo and its effects on the proliferation, differentiation and chemotactic movement of cells in vitro. Flow cytometry, real-time PCR, transwell and Cell Counting Kit-8 (CCK-8) assays were used in this study. The results showed that both preventative and therapeutic G-CSF administration could significantly inhibit bleomycin-induced pulmonary fibrosis. G-CSF enhanced BMSC migration to lung tissues, but this effect could be alleviated by AMD3100, which blocked the SDF-1/CXCR4 axis. We also found that BMSCs could inhibit fibroblast proliferation and transdifferentiation into myofibroblasts through paracrine actions. In conclusion, G-CSF exerted antifibrotic effects in bleomycin-induced lung fibrosis, in part by promoting BMSC homing to injured lung tissues via SDF-1/CXCR4 chemotaxis.

Transcription factor AP­2α negatively regulates thymic stromal lymphopoietin expression in respiratory syncytial virus infection.

Respiratory syncytial virus (RSV) infection enhances the cell­mediated immune responses of type 2 helper T cells and promotes the progression of allergic inflammation and asthma by producing thymic stromal lymphopoietin (TSLP), especially long isoform TSLP (lfTSLP). However, the role of short isoform TSLP (sfTSLP) in RSV infection remains to be elucidated. The present study was designed to demonstrate the role of both lfTSLP and sfTSLP, as transcription regulators, in RSV infection. The expression of lfTSLP and sfTSLP in RSV­infected Beas­2B cells was analyzed. Activating protein 2 (AP­2)α was overexpressed or knocked down to detect the changes in sfTSLP and lfTSLP expression. Luciferase reporter plasmid and chromatin immunoprecipitation experiments demonstrated that AP­2α bound to the sfTSLP promoter region. LfTSLP and sfTSLP increased while AP­2α decreased in RSV­infected Beas­2B cells. In the Beas­2B cells, AP­2α was found to negatively regulate the activity of the sfTSLP promoter and the mRNA level of sfTSLP. AP­2α also negatively regulated the expression of lfTSLP at both the mRNA and protein levels. The results of the chromatin immunoprecipitation assay indicated that AP­2α bound to the core promoter region of sfTSLP. These results confirmed that the transcription factor AP­2α can repress the expression of lfTSLP and sfTSLP in bronchial epithelial cells in RSV infection.

Transcription factor E2F1 positively regulates interferon regulatory factor 5 expression in non-small cell lung cancer.

PURPOSE: Lung cancer is the most common malignant tumor in the world, and its incidence and mortality are very high. This study focuses on the mechanism of non-small cell lung cancer to find new therapeutic targets. METHODS: We used RT-PCR and Western blot to verify the linear relationship between E2F1 and IRF5 in normal lung tissue and lung cancer tissues. Secondly, we used overexpression and knock down E2F1 in cell lines to detect the expression of IRF5. The prime enzyme reporter plasmid verified that E2F1 binds to the core promoter region of IRF5; finally, CHIP experiments demonstrated that E2F1 binds directly to IRF5. RESULTS: We verified that E2F1 and IRF5 are decreased in patient tissues, and there is a strong linear relationship between E2F1 and IRF5. Secondly, we used overexpression of E2F1 or E2F1 siRNA transfected into HCC827 cells and found that E2F1 positively regulates the activity of the IRF5 promoter and the mRNA level of IRF5. Finally, the results of a chromatin immunoprecipitation assay demonstrated that E2F1 bound to the promoter region of IRF5 in vitro. These results suggested that the E2F1 transcription factor is the primary determinant for activating the basal transcription of the IRF5. CONCLUSION: The transcription factor E2F1 positively regulates IRF5 in non-small cell lung cancer.

Three microporous metal-organic frameworks assembled from dodecanuclear {NiLn} subunits: synthesis, structure, gas adsorption and magnetism.

Three isostructural heterometallic metal-organic frameworks (MOFs) {[Ln2Ni(OAc)5(HL)(L)]·solvent molecules}n (H2L = 2-hydroxyimino-N-[1-(2-pyrazinyl)ethylidene]-propanohydrazone, Ln = Dy for 1, Tb for 2 and Gd for 3) were solvothermally synthesized by varying rare-earth metal ions with different electron configurations. Their crystal structures, gas adsorption and magnetic behaviors were fully investigated. The three isomorphous MOFs exhibit three-dimensional microporous frameworks with two different orientated dodecane metallic {NiIILnIII(HL)}6 metallomacrocycles alternately connected by {LnIII(L)} connectors, in which an empty one-dimensional channel decorated by the basic hydrazone interior is generated. Due to their LnIII-independent microporous nature, the activated sample of 1 as a representative example has a significant CO2 uptake up to 42.2 cm3 g-1 and an unusually high CO2/N2 and CO2/CH4 adsorption selectivity of up to 98.8 and 16.8 at 298 K and 100 kPa. Magnetically, apparent antiferromagnetic interactions for both 1 and 2 as well as ferromagnetic coupling for 3 are respectively observed at low temperature resulting from the competition of magnetic anisotropy and intermetallic ferromagnetic superexchange. Additionally, 1 with highly anisotropic DyIII spin shows slow magnetization relaxation under zero dc field, whereas 3 possessing isotropic GdIII ions displays a significant cryogenic magnetocaloric effect with a maximum entropy change of 26.6 J kg-1 K-1 at 3.0 K and 70 kOe. These interesting results can provide valuable information on gas separation-based multifunctional 3d-4f MOF materials.

[Role of neuropeptide substance P and the bone morphogenetic protein signaling pathway in osteogenic differentiation of ST2 cells].

OBJECTIVE: This study aimed to investigate the role and mechanism of neuropeptide substance P (SP) in ST2 cell (bone mesenchymal stem cells of mice) osteogenic differentiation to provide a basis for the treatment of temporomandibular joint osteoarthritis. METHODS: Third-generation ST2 cells were cultured with different concentrations of SP (0, 10⁻¹°, 10⁻8, 10⁻6, and 10⁻5 mol·L⁻¹). After 24, 48, and 72 h, cell proliferation was detected by CCK-8. The ST2 cells were cultured with 10⁻6 mol·L⁻¹ SP for 1, 3, 5, and 7 days. Subsequently, the expression of alkaline phosphatase (ALP), collagen typeⅠ(CollaⅠ), and osteocalcin (OCN) in the culture supernatant was tested by enzyme-linked immunosorbent assay (ELISA). ALP activity was detected by immunofluorescence staining. The ST2 cells were cultured with SP, Noggin (inhibitor of the bone morphogenetic protein signaling pathway), SP+Noggin, and 2% fetal bovine serum, respectively. Finally, the expression of ALP, CollaⅠ, and OCN in the culture supernatant was tested by ELISA. RESULTS: CCK-8 showed that the effect of cell proliferation was most obvious when the SP concentration was 10⁻6 mol·L⁻¹ (P<0.01). The ELISA results demonstrated that ALP expression significantly increased at day 5 compared with that in the control group (P<0.01), whereas the expression of CollaⅠand OCN significantly increased at day 7 (P<0.05). Immunofluorescence results showed that ALP activity was strongest at day 5. The expression of ALP, CollaⅠ, and OCN decreased after Noggin addition (P<0.05). CONCLUSIONS: SP can promote the proliferation and osteogenic differentiation of ST2 cells, and the bone morphogenetic protein signaling pathway may be involved in this process.

A Sustained Activation of Pancreatic NMDARs Is a Novel Factor of ß-Cell Apoptosis and Dysfunction.

Type 2 diabetes, which features ß-cell failure, is caused by the decrease of ß-cell mass and insulin secretory function. Current treatments fail to halt the decrease of functional ß-cell mass. Strategies to prevent ß-cell apoptosis and dysfunction are highly desirable. Recently, our group and others have reported that blockade of N-methyl-d-aspartate receptors (NMDARs) in the islets has been proposed to prevent the progress of type 2 diabetes through improving ß-cell function. It suggests that a sustained activation of the NMDARs may exhibit deleterious effect on ß-cells. However, the exact functional impact and mechanism of the sustained NMDAR stimulation on islet ß-cells remains unclear. Here, we identify a sustained activation of pancreatic NMDARs as a novel factor of apoptotic ß-cell death and function. The sustained treatment with NMDA results in an increase of intracellular [Ca2+] and reactive oxygen species, subsequently induces mitochondrial membrane potential depolarization and a decrease of oxidative phosphorylation expression, and then impairs the mitochondrial function of ß-cells. NMDA specifically induces the mitochondrial-dependent pathway of apoptosis in ß-cells through upregulation of the proapoptotic Bim and Bax, and downregulation of antiapoptotic Bcl-2. Furthermore, a sustained stimulation of NMDARs impairs ß-cell insulin secretion through decrease of pancreatic duodenal homeobox-1 (Pdx-1) and adenosine triphosphate synthesis. The activation of nuclear factor-κB partly contributes to the reduction of Pdx-1 expression induced by overstimulation of NMDARs. In conclusion, we show that the sustained stimulation of NMDARs is a novel mediator of apoptotic signaling and ß-cell dysfunction, providing a mechanistic insight into the pathological role of NMDARs activation in diabetes.

[Metabotropic glutamate receptor 8 activation promotes the apoptosis of lung carcinoma A549 cells in vitro].

This study aims to detect the expression of metabotropic glutamate receptors (mGluRs) in lung carcinoma A549 cells, and to investigate the effects of mGluR8 and mGluR4 activation on the growth of A549 cells in vitro. The mRNA expression levels of the 8 subtypes of mGluRs in A549 cells were determined by real-time PCR. Immunohistochemistry was used to analyze the protein expression of mGluR4 and mGluR8 in A549 cells and lung tissue sections obtained from lung adenocarcinoma patients. To observe the effects of mGluR8 and mGluR4 activation on the growth of A549 cells, the cultured cells were treated with (S)-3,4-DCPG (an agonist of mGluR8) and VU0155041 (an agonist of mGluR4), respectively, and then the cell viability was analyzed by CCK-8 kit, the percentage of DNA synthesis was detected by EdU incorporation, and the apoptosis of the cells was measured by hoechst 33258 staining and flow cytometry. The results showed that there were low expressions of mGluR1, mGluR5, mGluR6, mGluR7 mRNA, no expression of mGluR2 and mGluR3 mRNA, and high expressions of mGluR8 and mGluR4 mRNA in A549 cells. Accordingly, there were also mGluR4 and mGluR8 protein expressions in the A549 cells and the lung adenocarcinoma tissue sections. VU0155041 had no effect on the growth of A549 cells, but (S)-3,4-DCPG significantly decreased the cells' growth in a dose-dependent manner and increased the apoptosis of the cells. The results revealed a role of mGluR8 in the growth and apoptosis of A549 cells and suggested a potential target for clinical treatment of lung cancer.

Antiflammin-1 attenuates bleomycin-induced pulmonary fibrosis in mice.

BACKGROUND: Antiflammin-1 (AF-1), a derivative of uteroglobin (UG), is a synthetic nonapeptide with diverse biological functions. In the present study, we investigated whether AF-1 has a protective effect against bleomycin-induced pulmonary fibrosis. METHODS: C57BL/6 mice were injected with bleomycin intratracheally to create an animal model of bleomycin-induced pulmonary fibrosis. On Day 7 and Day 28, we examined the anti-inflammatory effect and antifibrotic effect, respectively, of AF-1 on the bleomycin-treated mice. The effects of AF-1 on the transforming growth factor-beta 1 (TGF-ß1)-induced proliferation of murine lung fibroblasts (NIH3T3) were examined by a bromodeoxycytidine (BrdU) incorporation assay and cell cycle analysis. RESULTS: Severe lung inflammation and fibrosis were observed in the bleomycin-treated mice on Day 7 and Day 28, respectively. Administration of AF-1 significantly reduced the number of neutrophils in the bronchoalveolar lavage fluid (BALF) and the levels of tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1ß) in the lung homogenates on Day 7. Histological examination revealed that AF-1 markedly reduced the number of infiltrating cells on Day 7 and attenuated the collagen deposition and destruction of lung architecture on Day 28. The hydroxyproline (HYP) content was significantly decreased in the AF-1-treated mice. In vitro, AF-1 inhibited the TGF-ß1-induced proliferation of NIH3T3 cells, which was mediated by the UG receptor. CONCLUSIONS: AF-1 has anti-inflammatory and antifibrotic actions in bleomycin-induced lung injury. We propose that the antifibrotic effect of AF-1 might be related to its suppression of fibroblast growth in bleomycin-treated lungs and that AF-1 has potential as a new therapeutic tool for pulmonary fibrosis.

[Bioinformatics of mouse uteroglobin binding protein and its polyclonal antibody preparation].

To prepare anti-mouse uteroglobin binding protein (mUGBP) polyclonal antibody, two polypeptides were synthesized based on the bioinformatics analysis of mUGBP, and New Zealand white rabbits were immunized separately with each peptide coupled with keyhole limpet hemocyanin (KLH). The data indicate that a 13-amino acid polypeptide (positions 221st-233rd) was able to generate anti-peptide antibodies. The titer of the antisera detected with ELISA was 1:10(8). The antisera were then purified with immuno-affinity chromatography to obtain antibodies. Western blot analysis of mUGBP expressed as a fusion protein with a green fluorescent protein (GFP) was performed on the cell lysates of COS-1 cells with the purified antisera, suggesting that the antisera specifically recognized UGBP. By immunohistochemistry and indirect immunofluorescence analysis, we examined the expression of UGBP in the lung tissues from a patient undergoing surgical lung resection for a tumor and from normal mouse lung tissue, and found for the first time that UGBP protein was widely expressed in both mouse and human lung tissue with the most abundant expression in bronchial epithelial cells. These results suggest that the antigen epitopes of mUGBP are well predicted by using bioinformatics analysis. We have obtained anti-mUGBP polyclonal antibody, which will be useful for further investigation.

A set of miRNAs that involve in the pathways of drug resistance and leukemic stem-cell differentiation is associated with the risk of relapse and glucocorticoid response in childhood ALL.

Relapse is a major challenge in the successful treatment of childhood acute lymphoblastic leukemia (ALL). Despite intensive research efforts, the mechanisms of ALL relapse are still not fully understood. An understanding of the molecular mechanisms underlying treatment outcome, therapy response and the biology of relapse is required. In this study, we carried out a genome-wide microRNA (miRNA) microarray analysis to determine the miRNA expression profiles and relapse-associated miRNA patterns in a panel of matched diagnosis-relapse or diagnosis-complete remission (CR) childhood ALL samples. A set of miRNAs differentially expressed either in relapsed patients or at diagnosis compared with CR was further validated by quantitative real-time polymerase chain reaction in an independent sample set. Analysis of the predicted functions of target genes based on gene ontology 'biological process' categories revealed that the abnormally expressed miRNAs are associated with oncogenesis, classical multidrug resistance pathways and leukemic stem cell self-renewal and differentiation pathways. Several targets of the miRNAs associated with ALL relapse were experimentally validated, including FOXO3, BMI1 and E2F1. We further investigated the association of these dysregulated miRNAs with clinical outcome and confirmed significant associations for miR-708, miR-223 and miR-27a with individual relapse-free survival. Notably, miR-708 was also found to be associated with the in vivo glucocorticoid therapy response and with disease risk stratification. These miRNAs and their targets might be used to optimize anti-leukemic therapy, and serve as novel targets for development of new countermeasures of leukemia. This fundamental study may also contribute to establish the mechanisms of relapse in other cancers.

Upregulation of microRNA-125b contributes to leukemogenesis and increases drug resistance in pediatric acute promyelocytic leukemia.

BACKGROUND: Although current chemotherapy regimens have remarkably improved the cure rate of pediatric acute promyelocytic leukemia (APL) over the past decade, more than 20% of patients still die of the disease, and the 5-year cumulative incidence of relapse is 17%. The precise gene pathways that exert critical control over the determination of cell lineage fate during the development of pediatric APL remain unclear. METHODS: In this study, we analyzed miR-125b expression in 169 pediatric acute myelogenous leukemia (AML) samples including 76 APL samples before therapy and 38 APL samples after therapy. The effects of enforced expression of miR-125b were evaluated in leukemic cell and drug-resistant cell lines. RESULTS: miR-125b is highly expressed in pediatric APL compared with other subtypes of AML and is correlated with treatment response, as well as relapse of pediatric APL. Our results further demonstrated that miR-125b could promote leukemic cell proliferation and inhibit cell apoptosis by regulating the expression of tumor suppressor BCL2-antagonist/killer 1 (Bak1). Remarkably, miR-125b was also found to be up-regulated in leukemic drug-resistant cells, and transfection of a miR-125b duplex into AML cells can increase their resistance to therapeutic drugs, CONCLUSIONS: These findings strongly indicate that miR-125b plays an important role in the development of pediatric APL at least partially mediated by repressing BAK1 protein expression and could be a potential therapeutic target for treating pediatric APL failure.

miR-125b, a target of CDX2, regulates cell differentiation through repression of the core binding factor in hematopoietic malignancies.

MicroRNA-125b (miR-125b), a small noncoding RNA molecule, has been found to be deregulated and functions as an oncogene in many cancers including hematopoietic malignancies. However, the mechanisms accounting for miR-125b dysregulation remain to be elucidated. The present study aims to identify the factors that might contribute to up-regulation of miR-125b in human hematopoietic malignancies and its downstream targets for lineage-specific differentiation. We at first reported that CDX2, a homeobox transcription factor, binds to promoter regions of the miR-125b gene and activates transcriptional regulation of miR-125b in malignant myeloid cells. We further revealed that increasing levels of CDX2 in malignant myeloid cells activate miR-125b expression, which in turn inhibits core binding factor ß (CBFß) translation, thereby counteracting myeloid cell differentiation, at least for granulocytic lineage, and promoting leukemogenesis. Interestingly, we found that this novel pathway including CDX2, miR-125b, and CBFß was mediated by undergoing all-trans-retinoic acid induction. Once differentiation ensues with all-trans-retinoic acid treatment, CDX2 activity decreases, leading to a reduction in miR-125b transcription and up-regulation of CBFß in myeloid cells and in patients. The study provides a new mechanism that contributes to hematopoietic malignancies, which could involve deregulation of miR-125b and its up- and downstream factors. As altered expression of miRNAs has been reported in a wide range of malignancies, delineating the underlying molecular mechanisms of aberrant miRNA expression and characterizing the upstream and downstream factors will help to understand important steps in the pathogenesis of these afflictions.

Down-regulated miR-331-5p and miR-27a are associated with chemotherapy resistance and relapse in leukaemia.

Multidrug resistance (MDR) and disease relapse are challenging clinical problems in the treatment of leukaemia. Relapsed disease is frequently refractory to chemotherapy and exhibits multiple drug resistance. Therefore, it is important to identify the mechanism by which cancer cells develop resistance. In this study, we used microRNA (miRNA) microarray and qRT-PCR approaches to investigate the expression of miRNAs in three leukaemia cell lines with different degrees of resistance to doxorubicin (DOX) compared with their parent cell line, K562. The expression of miR-331-5p and miR-27a was inversely correlated with the expression of a drug-resistant factor, P-glycoprotein (P-gp), in leukaemia cell lines with gradually increasing resistance. The development of drug resistance is regulated by the expression of the P-gp. Transfection of the K562 and, a human promyelocytic cell line (HL) HL60 DOX-resistant cells with miR-331-5p and miR-27a, separately or in combination, resulted in the increased sensitivity of cells to DOX, suggesting that correction of altered expression of miRNAs may be used for therapeutic strategies to overcome leukaemia cell resistance. Importantly, miR-331-5p and miR-27a were also expressed at lower levels in a panel of relapse patients compared with primary patients at diagnosis, further illustrating that leukaemia relapse might be a consequence of deregulation of miR-331-5p and miR-27a.

Linoleic acid induces Ca2+-induced inactivation of voltage-dependent Ca2+ currents in rat pancreatic beta-cells.

Free fatty acids (FFAs) regulate insulin secretion in a complex pattern and induce pancreatic beta-cell dysfunction in type 2 diabetes. Voltage-dependent Ca2+ channels (VDCC) in beta-cells play a major role in regulating insulin secretion. The aim of present study is to clarify the action of the FFA, linoleic acid, on VDCC in beta-cells. The VDCC current in primary cultured rat beta-cells were recorded under nystatin-perforated whole-cell recording configuration. The VDCC was identified as high-voltage-gated Ca2+ channels due to there being no difference in current amplitude under holding potential between -70 and -40 mV. Linoleic acid (10 microM) significantly inhibited VDCC currents in beta-cells, an effect which was fully reversible upon washout. Methyl-linoleic acid, which does not activate G protein coupled receptor (GPR)40, neither did alter VDCC current in rat beta-cells nor did influence linoleic acid-induced inhibition of VDCC currents. Linoleic acid-induced inhibition of VDCC current was not blocked by preincubation of beta-cells with either the specific protein kinase A (PKA) inhibitor, H89, or the PKC inhibitor, chelerythrine. However, pretreatment of beta-cells with thapsigargin, which depletes intracellular Ca2+ stores, completely abolished linoleic acid-induced decrease in VDCC current. Measurement of intracellular Ca2+ concentration ([Ca2+](i)) illustrated that linoleic acid induced an increase in [Ca2+](i) and that thapsigargin pretreatment inhibited this increase. Methyl-linoleic acid neither did induce increase in [Ca2+](i) nor did it block linoleic acid-induced increase in [Ca2+](i). These results suggest that linoleic acid stimulates Ca2+ release from intracellular Ca2+ stores and inhibits VDCC currents in rat pancreatic beta-cells via Ca2+-induced inactivation of VDCC.