The expression of miR‐125b in Nrf2‐silenced A549 cells exposed to hyperoxia and its relationship with apoptosis

Bronchopulmonary dysplasia (BPD) is a chronic lung disease that affects the quality of life of infants. At present, premature exposure to hyperoxia for extended periods of time is believed to affect the development of lung tissue and vascularity, resulting in BPD. The oxidative stress caused by hyperoxia exposure is an important risk factor for BPD in premature infants. Nuclear factor E2‐related factor 2 (Nrf2) is an important regulator of antioxidant mechanisms. As a microRNA, microRNA‐125b (miR‐125b) plays an important role in cell proliferation, differentiation and apoptosis. Although the Nrf2/ARE pathway has been extensively studied, little is known about the regulatory role of microRNAs in Nrf2 expression. In this study, the expression levels of Nrf2 and miR‐125b in the lung tissues of premature Sprague Dawley (SD) rats and A549 cells exposed to hyperoxia were detected by quantitative real‐time polymerase chain reaction (qRT‐PCR), and the apoptosis of A549 cells was detected by flow cytometry. The results showed that Nrf2 and miRNA‐125b in the lung tissues of premature rats increased significantly upon exposure to hyperoxia and played a protective role. Nrf2 was suppressed by small interfering RNA (siRNA) in A549 cells, miR‐125b was similarly inhibited, and apoptosis was significantly increased. These results suggest that miR‐125b helps protect against BPD as a downstream target of Nrf2.     

Refining anti‐inflammatory therapy strategies for bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is a severe lung disease of preterm infants, which is characterized by fewer, enlarged alveoli and increased inflammation. BPD has grave consequences for affected infants, but no effective and safe therapy exists. We previously showed that prophylactic treatment with interleukin‐1 receptor antagonist (IL‐1Ra) prevents murine BPD induced by perinatal inflammation and hyperoxia. Here, we used the same BPD model to assess whether an alternative anti‐inflammatory agent, protein C (PC), is as effective as IL‐1Ra against BPD. We also tested whether delayed administration or a higher dose of IL‐1Ra affects its ability to ameliorate BPD and investigated aspects of drug safety. Pups were reared in room air (21% O₂) or hyperoxia (65% or 85% O₂) and received daily injections with vehicle, 1200 IU/kg PC, 10 mg/kg IL‐1Ra (early or late onset) or 100 mg/kg IL‐1Ra. After 3 or 28 days, lung and brain histology were assessed and pulmonary cytokines were analysed using ELISA and cytokine arrays. We found that PC only moderately reduced the severe impact of BPD on lung structure (e.g. 18% increased alveolar number by PC versus 34% by IL‐1Ra); however, PC significantly reduced IL‐1β, IL‐1Ra, IL‐6 and macrophage inflammatory protein (MIP)‐2 by up to 89%. IL‐1Ra at 10 mg/kg prevented BPD more effectively than 100 mg/kg IL‐1Ra, but only if treatment commenced at day 1 of life. We conclude that prophylactic low‐dose IL‐1Ra and PC ameliorate BPD and have potential as the first remedy for one of the most devastating diseases preterm babies face.     

GSK-3α Is a Novel Target of CREB and CREB-GSK-3α Signaling Participates in Cell Viability in Lung Cancer

Overexpression or activation of cyclic AMP-response element-binding protein (CREB) has been known to be involved in several human malignancies, including lung cancer. Genes regulated by CREB have been reported to suppress apoptosis, induce cell proliferation, inflammation, and tumor metastasis. However, the critical target genes of CREB in lung cancer have not been well understood. Here, we identified GSK-3α as one of the CREB target genes which is critical for the viability of lung cancer cells. The CREB knockdown significantly reduced the expression of GSK-3α and the direct binding of CREB on the promoter of GSK3A was identified. Kaplan-Meier analysis with a public database showed a prognostic significance of aberrant GSK-3α expression in lung cancer. Inhibition of GSK-3α suppressed cell viability, colony formation, and tumor growth. For the first time, we demonstrated that GSK-3α is regulated by CREB in lung cancer and is required for the cell viability. These findings implicate CREB-GSK-3α axis as a novel therapeutic target for lung cancer treatment.     

Human breast milk‐derived exosomes through inhibiting AT II cell apoptosis to prevent bronchopulmonary dysplasia in rat lung

Human breast milk (HBM) effectively prevents and cures neonatal bronchopulmonary dysplasia (BPD). Exosomes are abundant in breast milk, but the function of HBM‐derived exosomes (HBM‐Exo) in BPD is still unclear. This study was to investigate the role and mechanism of HBM‐Exo in BPD. Overall lung tissue photography and H&E staining showed that HBM‐Exo improved the lung tissue structure collapse, alveolar structure disorder, alveolar septum width, alveolar number reduction and other injuries caused by high oxygen exposure. Immunohistochemical results showed that HBM‐Exo improved the inhibition of cell proliferation and increased apoptosis caused by hyperoxia. qPCR and Western blot results also showed that HBM‐Exo improved the expression of Type II alveolar epithelium (AT II) surface marker SPC. In vivo study, CCK8 and flow cytometry showed that HBM‐Exo improved the proliferation inhibition and apoptosis of AT II cells induced by hyperoxia, qPCR and immunofluorescence also showed that HBM‐Exo improved the down‐regulation of SPC. Further RNA‐Seq results in AT II cells showed that a total of 88 genes were significantly different between the hyperoxia and HBM‐Exo with hyperoxia groups, including 24 up‐regulated genes and 64 down‐regulated genes. KEGG pathway analysis showed the enrichment of IL‐17 signalling pathway was the most significant. Further rescue experiments showed that HBM‐Exo improved AT II cell damage induced by hyperoxia through inhibiting downstream of IL‐17 signalling pathway (FADD), which may be an important mechanism of HBM‐Exo in the prevention and treatment of BPD. This study may provide new approach in the treatment of BPD.     

Role of bone marrow-derived mesenchymal stem cells in the prevention of hyperoxia-induced lung injury in newborn mice

BPD (bronchopulmonary dysplasia) is predominantly characterized by persistent abnormalities in lung structure and arrested lung development, but therapy can be palliative. While promising, the use of BMSC (bone marrow-derived mesenchymal stem cell) in the treatment of lung diseases remains controversial. We have assessed the therapeutic effects of BMSC in vitro and in vivo. In vitro co-culturing with injured lung tissue increased the migration-potential of BMSC; and SP-C (surfactant protein-C), a specific marker of AEC2 (type II alveolar epithelial cells), was expressed. Following intraperitoneal injection of BMSC into experimental BPD mice on post-natal day 7, it was found that BMSC can home to the injured lung, express SP-C, improve pulmonary architecture, attenuate pulmonary fibrosis and increase the survival rate of BPD mice. This work supports the notion that BMSC are of therapeutic benefit through the production of soluble factors at bioactive levels that regulate the pathogenesis of inflammation and fibrosis following hyperoxia.     

RBM10 inhibits cell proliferation of lung adenocarcinoma via RAP1/AKT/CREB signalling pathway

Initial functional studies have demonstrated that RNA‐binding motif protein 10 (RBM10) can promote apoptosis and suppress cell proliferation; however, the results of several studies suggest a tumour‐promoting role for RBM10. Herein, we assessed the involvement of RBM10 in lung adenocarcinoma cell proliferation and explored the potential molecular mechanism. We found that, both in vitro and in vivo, RBM10 overexpression suppresses lung adenocarcinoma cell proliferation, while its knockdown enhances cell proliferation. Using complementary DNA microarray analysis, we previously found that RBM10 overexpression induces significant down‐regulation of RAP1A expression. In this study, we have confirmed that RBM10 decreases the activation of RAP1 and found that EPAC stimulation and inhibition can abolish the effects of RBM10 knockdown and overexpression, respectively, and regulate cell growth. This effect of RBM10 on proliferation was independent of the MAPK/ERK and P38/MAPK signalling pathways. We found that RBM10 reduces the phosphorylation of CREB via the AKT signalling pathway, suggesting that RBM10 exhibits its effect on lung adenocarcinoma cell proliferation via the RAP1/AKT/CREB signalling pathway.     

Long noncoding RNA MALAT1 enhances the docetaxel resistance of prostate cancer cells via miR‐145‐5p‐mediated regulation of AKAP12

Our present work was aimed to study on the regulatory role of MALAT1/miR‐145‐5p/AKAP12 axis on docetaxel (DTX) sensitivity of prostate cancer (PCa) cells. The microarray data (GSE33455) to identify differentially expressed lncRNAs and mRNAs in DTX‐resistant PCa cell lines (DU‐145‐DTX and PC‐3‐DTX) was retrieved from the Gene Expression Omnibus (GEO) database. QRT‐PCR analysis was performed to measure MALAT1 expression in DTX‐sensitive and DTX‐resistant tissues/cells. The human DTX‐resistant cell lines DU145‐PTX and PC3‐DTX were established as in vitro cell models, and the expression of MALAT1, miR‐145‐5p and AKAP12 was manipulated in DTX‐sensitive and DTX‐resistant cells. Cell viability was examined using MTT assay and colony formation methods. Cell apoptosis was assessed by TUNEL staining. Cell migration and invasion was determined by scratch test (wound healing) and Transwell assay, respectively. Dual‐luciferase assay was applied to analyse the target relationship between lncRNA MALAT1 and miR‐145‐5p, as well as between miR‐145‐5p and AKAP12. Tumour xenograft study was undertaken to confirm the correlation of MALAT1/miR‐145‐5p/AKAP12 axis and DTX sensitivity of PCa cells in vivo. In this study, we firstly notified that the MALAT1 expression levels were up‐regulated in clinical DTX‐resistant PCa samples. Overexpressed MALAT1 promoted cell proliferation, migration and invasion but decreased cell apoptosis rate of PCa cells in spite of DTX treatment. We identified miR‐145‐5p as a target of MALAT1. MiR‐145‐5p overexpression in PC3‐DTX led to inhibited cell proliferation, migration and invasion as well as reduced chemoresistance to DTX, which was attenuated by MALAT1. Moreover, we determined that AKAP12 was a target of miR‐145‐5p, which significantly induced chemoresistance of PCa cells to DTX. Besides, it was proved that MALAT1 promoted tumour cell proliferation and enhanced DTX‐chemoresistance in vivo. There was an lncRNA MALAT1/miR‐145‐5p/AKAP12 axis involved in DTX resistance of PCa cells and provided a new thought for PCa therapy.