Fibroblast growth factor 21 alleviates acute pancreatitis via activation of the Sirt1‐autophagy signalling pathway

Fibroblast growth factor 21 (FGF21), a metabolic hormone with pleiotropic effects on glucose and lipid metabolism and insulin sensitivity, alleviates the process of acute pancreatitis (AP). However, its mechanism remains elusive. The pathological and physiological characteristics of FGF21 are observed in both patients with AP and cerulein‐induced AP models, and the mechanisms of FGF21 in response to AP are investigated by evaluating the impact of autophagy in FGF21‐treated mice and cultured pancreatic cells. Circulating levels of FGF21 significantly increase in both AP patients and cerulein‐induced AP mice, which is accompanied by the change of pathology in pancreatic injury. Replenishment of FGF21 distinctly reverses cerulein‐induced pancreatic injury and improves cerulein‐induced autophagy damage in vivo and in vitro. Mechanically, FGF21 acts on pancreatic acinar cells to up‐regulate Sirtuin‐1 (Sirt1) expression, which in turn repairs impaired autophagy and removes damaged organs. In addition, blockage of Sirt1 accelerates cerulein‐induced pancreatic injury and weakens the regulative effect in FGF21‐activated autophagy in mice. These results showed that FGF21 protects against cerulein‐induced AP by activation of Sirtuin‐1‐autophagy axis.     

Periplocymarin alleviates pathological cardiac hypertrophy via inhibiting the JAK2/STAT3 signalling pathway

Pathological cardiac hypertrophy is the most important risk factor for developing chronic heart failure. Therefore, the discovery of novel agents for treating pathological cardiac hypertrophy remains urgent. In the present study, we examined the therapeutic effect and mechanism of periplocymarin (PM)‐mediated protection against pathological cardiac hypertrophy using angiotensinII (AngII)‐stimulated cardiac hypertrophy in H9c2 cells and transverse aortic constriction (TAC)‐induced cardiac hypertrophy in mice. In vitro, PM treatment significantly reduced the surface area of H9c2 cells and expressions of hypertrophy‐related proteins. Meanwhile, PM markedly down‐regulated AngII‐induced translocation of p‐STAT3 into the nuclei and enhanced the phosphorylation levels of JAK2 and STAT3 proteins. The STAT3 specific inhibitor S3I‐201 or siRNA‐mediated depleted expression could alleviate AngII‐induced cardiac hypertrophy in H9c2 cells following PM treatment; however, PM failed to reduce the expressions of hypertrophy‐related proteins and phosphorylated STAT3 in STAT3‐overexpressing cells, indicating that PM protected against AngII‐induced cardiac hypertrophy by modulating STAT3 signalling. In vivo, PM reversed TAC‐induced cardiac hypertrophy, as determined by down‐regulating ratios of heart weight to body weight (HW/BW), heart weight to tibial length (HW/TL) and expressions of hypertrophy‐related proteins accompanied by the inhibition of the JAK2/STAT3 pathway. These results revealed that PM could effectively protect the cardiac structure and function in experimental models of pathological cardiac hypertrophy by inhibiting the JAK2/STAT3 signalling pathway. PM is expected to be a potential lead compound of the novel agents for treating pathological cardiac hypertrophy.     

Association of RDM1 with osteosarcoma progression via cell cycle and MEK/ERK signalling pathway regulation

RAD52 motif-containing 1 (RDM1), a key regulator of DNA double-strand break repair and recombination, has been reported to play an important role in the development of various human cancers, such as papillary thyroid carcinoma, neuroblastoma and lung cancer. However, the effect of RDM1 on osteosarcoma (OS) progression remains unclear. Here, this study mainly explored the connection between RDM1 and OS progression, as well as the underlying mechanism. It was found that RDM1 was highly expressed in OS cells compared with human osteoblast cells. Knockdown of RDM1 caused OS cell proliferation inhibition, cell apoptosis promotion and cell cycle arrest at G1 stage, whereas RDM1 overexpression resulted in the opposite phenotypes. Furthermore, RDM1 silencing leads to a significant decrease in tumour growth in xenograft mouse model. RDM1 also increased the protein levels of MEK 1/2 and ERK 1/2. All these findings suggest that RDM1 plays an oncogenic role in OS via stimulating cell cycle transition from G1 to S stage, and regulating MEK/ERK signalling pathway, providing a promising therapeutic factor for the treatment of OS.     

Netrin‐1 alleviates subarachnoid haemorrhage‐induced brain injury via the PPARγ/NF‐KB signalling pathway

Netrin‐1 (NTN‐1) is a novel drug to alleviate early brain injury following subarachnoid haemorrhage (SAH). However the molecular mechanism of NTN‐1‐mediated protection against early brain injury following SAH remains largely elusive. This study aims to evaluate the effects and mechanisms of NTN‐1 in protecting SAH‐induced early brain injury. The endovascular perforation SAH model was constructed using male C57BL/6J mice, and recombinant NTN‐1 was administrated intravenously. Mortality rates, SAH grade, brain water content, neurological score and neuronal apoptosis were evaluated. The expression of PPARγ, Bcl‐2, Bax and nuclear factor‐kappa B (NF‐κB) were detected by Western blot. Small interfering RNA specific to NTN‐1 receptor, UNC5B, and a selective PPARγ antagonist, bisphenol A diglycidyl ether (BADGE), were applied in combination with NTN‐1. The results suggested that NTN‐1 improved the neurological deficits, reduced the brain water content and alleviated neuronal apoptosis. In addition, NTN‐1 enhanced PPARγ and Bcl‐2 expression and decreased the levels of Bax and NF‐κB. However, the neuroprotection of NTN‐1 was abolished by UNC5B and BADGE. In conclusion, our results demonstrated that NTN‐1 attenuates early brain injury following SAH via the UNC5B PPARγ/NF‐κB signalling pathway.     

TIPE1‐mediated autophagy suppression promotes nasopharyngeal carcinoma cell proliferation via the AMPK/mTOR signalling pathway

Recent studies have shown that tumour necrosis factor‐α–induced protein 8 like‐1(TIPE1) plays distinct roles in different cancers. TIPE1 inhibits tumour proliferation and metastasis in a variety of tumours but acts as an oncogene in cervical cancer. The role of TIPE1 in nasopharyngeal carcinoma (NPC) remains unknown. Interestingly, TIPE1 expression was remarkably increased in NPC tissue samples compared to adjacent normal nasopharyngeal epithelial tissue samples in our study. TIPE1 expression was positively correlated with that of the proliferation marker Ki67 and negatively correlated with patient lifespan. In vitro, TIPE1 inhibited autophagy and induced cell proliferation in TIPE1‐overexpressing CNE‐1 and CNE‐2Z cells. In addition, knocking down TIPE1 expression promoted autophagy and decreased proliferation, whereas overexpressing TIPE1 increased the levels of pmTOR, pS6 and P62 and decreased the level of pAMPK and the LC3B. Furthermore, the decrease in autophagy was remarkably rescued in TIPE1‐overexpressing CNE‐1 and CNE‐2Z cells treated with the AMPK activator AICAR. In addition, TIPE1 promoted tumour growth in BALB/c nude mice. Taken together, results indicate that TIPE1 promotes NPC progression by inhibiting autophagy and inducing cell proliferation via the AMPK/mTOR signalling pathway. Thus, TIPE1 could potentially be used as a valuable diagnostic and prognostic biomarker for NPC.     

p62/SQSTM1 protects against cisplatin-induced oxidative stress in kidneys by mediating the cross talk between autophagy and the Keap1-Nrf2 signalling pathway

Acute kidney injury (AKI) is a major kidney disease associated with poor clinical outcomes. Oxidative stress is predominantly involved in the pathogenesis of AKI. Autophagy and the Keap1-Nrf2 signalling pathway are both involved in the oxidative-stress response. However, the cross talk between these two pathways in AKI remains unknown. Here, we found that autophagy is upregulated during cisplatin-induced AKI. In contrast with previous studies, we observed a marked increase in p62. We also found that p62 knockdown reduces autophagosome formation and the expression of LC3II. To explore the cross talk between p62 and the Keap1-Nrf2 signalling pathway, HK-2 cells were transfected with siRNA targeting Nrf2, and we found that Nrf2 knockdown significantly reduced cisplatin-induced p62 expression. Moreover, p62 knockdown significantly decreased the protein expression of Nrf2, as well as Heme Oxygenase-1 (HO-1) and NAD(P)H:quinone oxidoreductase l (NQO1), whereas the expression of kelch-like ECH-associated protein 1 (Keap1) was upregulated. These results indicate that p62 creates a positive feedback loop in the Keap1-Nrf2 signalling pathway. Finally, we examined the role of p62 in cell protection during cisplatin-induced oxidative stress, and we found that p62 silencing in HK-2 cells increases apoptosis and reactive oxygen species (ROS) levels, which further indicates the protective role of p62 under oxidative stress and suggests that the cytoprotection 62 mediated is in part by regulating autophagic activity or the Keap1-Nrf2 signalling pathway. Taken together, our results have demonstrated a reciprocal regulation of p62, autophagy and the Keap1-Nrf2 signalling pathway under oxidative stress, which may be a potential therapeutic target against AKI.     

LncRNA KCNQ1OT1 enhanced the methotrexate resistance of colorectal cancer cells by regulating miR‐760/PPP1R1B via the cAMP signalling pathway

We aimed to explore the mechanism of the KCNQ1OT1/miR‐760/PPP1R1B axis acting to regulate methotrexate (MTX) resistance of colorectal cancer (CRC). Differentially expressed mRNAs and lncRNAs in MTX‐sensitive CRC cell lines and MTX‐resistant cell lines were determined through microarray analysis. Application of bioinformatics analysis was aimed to uncover the relationships among the lncRNAs/miRNAs/mRNAs, and to demonstrate the effects of cAMP signalling pathway in MTX‐resistant CRC. The expression level of RNA and proteins was, respectively, detected using qRT‐PCR and Western blot assays, whereas the dual‐luciferase reporter gene assay was implemented to verify the targeted relationship. The influence of the lncRNA/miRNA/mRNA axis on biological functions of MTX‐resistant cells and on the growth of tumours determined through both vitro and vivo experiments. LncRNA KCNQ1OT1 and PPP1R1B mRNA were overexpressed in MTX‐resistant CRC tumour cells. KCNQ1OT1 functioned as a sponge of miR‐760, which targeted PPP1R1B. Knockdown of KCNQ1OT1 enhanced chemosensitivity towards MTX through the sponging of miR‐760. MiR‐760 expressed at low levels targeted PPP1R1B in the activated cAMP signalling pathway under MTX treatment. Knockdown of KCNQ1OT1 dampened the proliferation of MTX‐resistant (HT29/MTX) cells by regulating the miR‐760/PPP1R1B axis, which also induced cell cycle arrest together with apoptosis. KCNQ1OT1 regulated the expression of PPP1R1B and the downstream genes CREB and CBP in the cAMP signalling pathway. MTX showed a suppressive function on CRC progression. KCNQ1OT1 enhanced the MTX resistance of CRC cells by regulating miR‐760‐mediated PPP1R1B expression via the cAMP signalling pathway.     

Spliced X-box binding protein 1 induces liver cancer cell death via activating the Mst1-JNK-mROS signalling pathway

Previous studies have found that the primary pathogenesis of liver cancer progression is linked to excessive cancer cell proliferation and rapid metastasis. Although therapeutic advances have been made for the treatment of liver cancer, the mechanism underlying the liver cancer progression has not been fully addressed. In the present study, we explored the role of spliced X-box binding protein 1 (XBP1) in regulating the viability and death of liver cancer cells in vitro. Our study demonstrated that XBP1 was upregulated in liver cancer cells when compared to the primary hepatocytes. Interestingly, the deletion of XBP1 could reduce the viability of liver cancer cells in vitro via inducing apoptotic response. Further, we found that XBP1 downregulation was also linked to proliferation arrest and migration inhibition. At the molecular levels, XBP1 inhibition is followed by activation of the Mst1 pathway which promoted the phosphorylation of c-Jun N-terminal kinase (JNK). Then, the active Mst1-JNK pathway mediated mitochondrial reactive oxygen species (mROS) overproduction and then excessive ROS induced cancer cell death. Therefore, our study demonstrated a novel role played by XBP1 in modulating the viability of liver cancer cells via the Mst1-JNK-mROS pathways.     

Renoprotective effect of berberine via regulating the PGE2‐EP1‐Gαq‐Ca2+ signalling pathway in glomerular mesangial cells of diabetic rats

G‐protein coupled receptor‐mediated pathogenesis is of great importance in the development of diabetic complications, but the detailed mechanisms have not yet been clarified. Therefore, we aimed to explore the roles of the prostaglandin E2 receptor 1 (EP1)‐mediated signalling pathway and develop a corresponding treatment for diabetic nephropathy (DN). To create the DN model, rats fed a high‐fat and high‐glucose diet were injected with a single dose of streptozotocin (35 mg/kg, i.p.). Then, rats were either treated or not with berberine (100 mg/kg per day, i.g., 8 weeks). Cells were isolated from the renal cortex and cultured in high‐sugar medium with 20% foetal bovine serum. Prostaglandin E₂ (PGE₂) levels were determined by ELISA, and cells were identified by fluorescence immunoassay. We measured the biochemical characteristics and observed morphological changes by periodic‐acid‐Schiff staining. The expression of the EP1 receptor and the roles of GRK2 and β‐arrestin2 were identified using western blotting and flow cytometry. Downstream proteins were detected by western blot, while molecular changes were assessed by ELISA and laser confocal scanning microscopy. Berberine not only improved the majority of biochemical and renal functional parameters but also improved the histopathological alterations. A significant increase in PGE₂ level, EP1 membrane expression and Gαq expression, and concentration of Ca²⁺ were observed, accompanied by increased GRK2 and β‐arrestin2 levels soon afterwards. Berberine decreased the abnormal concentration of Ca²⁺, the increased levels of PGE₂, the high expression of EP1 and Gαq and suppressed the proliferation of mesangial cells. The EP1 receptor, a critical therapeutic target of the signalling pathway, contributed to mesangial cell abnormalities, which are linked to renal injury in DN. The observed renoprotective effects of berberine via regulating the PGE₂‐EP1‐Gαq‐Ca²⁺ signalling pathway indicating that berberine could be a promising anti‐DN medicine in the future.     

Fatty acylCoA synthetase FadD13 regulates proinflammatory cytokine secretion dependent on the NF‐κB signalling pathway by binding to eEF1A1

Mycobacterium tuberculosis (Mtb) manipulates multiple host defence pathways to survive and persist in host cells. Understanding Mtb–host cell interaction is crucial to develop an efficient means to control the disease. Here, we applied the Mtb proteome chip, through separately interacting with H37Ra and H37Rv stimulated macrophage lysates, screened 283 Mtb differential proteins. Through primary screening, we focused on fatty acylCoA synthetase FadD13. Mtb FadD13 is a potential drug target, but its role in infection remains unclear. Deletion of FadD13 in Mtb reduced the production of proinflammatory cytokines IL‐1β, IL‐18, and IL‐6. Bimolecular fluorescence complementation and colocalization showed that the binding partner of FadD13 in macrophage was eEF1A1 (a translation elongation factor). Knockdown eEF1A1 expression in macrophage abrogated the promotion of proinflammatory cytokines induced by FadD13. In addition, ΔfadD13 mutant decreased the expression of the NF‐κB signalling pathway related proteins p50 and p65, so did the eEF1A1 knockdown macrophage infected with H37Rv. Meanwhile, we found that deletion of FadD13 reduced Mtb survival in macrophages during Mtb infection, and purified FadD13 proteins induced broken of macrophage membrane. Taken together, FadD13 is crucial for Mtb proliferation in macrophages, and it plays a key role in the production of proinflammatory cytokines during Mtb infection.     

Glyoxalase 1 sustains the metastatic phenotype of prostate cancer cells via EMT control

Metastasis is the primary cause of death in prostate cancer (PCa) patients. Effective therapeutic intervention in metastatic PCa is undermined by our poor understanding of its molecular aetiology. Defining the mechanisms underlying PCa metastasis may lead to insights into how to decrease morbidity and mortality in this disease. Glyoxalase 1 (Glo1) is the detoxification enzyme of methylglyoxal (MG), a potent precursor of advanced glycation end products (AGEs). Hydroimidazolone (MG‐H1) and argpyrimidine (AP) are AGEs originating from MG‐mediated post‐translational modification of proteins at arginine residues. AP is involved in the control of epithelial to mesenchymal transition (EMT), a crucial determinant of cancer metastasis and invasion, whose regulation mechanisms in malignant cells are still emerging. Here, we uncover a novel mechanism linking Glo1 to the maintenance of the metastatic phenotype of PCa cells by controlling EMT by engaging the tumour suppressor miR‐101, MG‐H1‐AP and TGF‐β1/Smad signalling. Moreover, circulating levels of Glo1, miR‐101, MG‐H1‐AP and TGF‐β1 in patients with metastatic compared with non‐metastatic PCa support our in vitro results, demonstrating their clinical relevance. We suggest that Glo1, together with miR‐101, might be potential therapeutic targets for metastatic PCa, possibly by metformin administration.     

Increased miR‐34c mediates synaptic deficits by targeting synaptotagmin 1 through ROS‐JNK‐p53 pathway in Alzheimer’s Disease

Alzheimer's disease (AD) and cancer have inverse relationship in many aspects. Some tumor suppressors, including miR‐34c, are decreased in cancer but increased in AD. The upstream regulatory pathways and the downstream mechanisms of miR‐34c in AD remain to be investigated. The expression of miR‐34c was detected by RT–qPCR in oxidative stressed neurons, hippocampus of SAMP8 mice, or serum of patients with amnestic mild cognitive impairment (aMCI). Dual luciferase assay was performed to confirm the binding sites of miR‐34c in its target mRNA. The Morris water maze (MWM) was used to evaluate learning and memory in SAMP8 mice administrated with miR‐34c antagomir (AM34c). Golgi staining was used to evaluate the synaptic function and structure. The dramatically increased miR‐34c was mediated by ROS‐JNK‐p53 pathway and negatively regulated synaptotagmin 1 (SYT1) expression by targeting the 3′‐untranslated region (3′‐UTR) of syt1 in AD. The expression of SYT1 protein was reduced by over expression of miR‐34c in the HT‐22 cells and vice versa. Administration of AM34c by the third ventricle injection or intranasal delivery markedly increased the brain levels of SYT1 and ameliorated the cognitive function in SAMP8 mice. The serum miR‐34c was significantly increased in patients with aMCI and might be a predictive biomarker for diagnosis of aMCI. These results indicated that increased miR‐34c mediated synaptic and memory deficits by targeting SYT1 through ROS‐JNK‐p53 pathway and the miR‐34c/SYT1 pathway could be considered as a promising novel therapeutic target for patients with AD.     

MiR‐199b‐5p inhibits osteogenic differentiation in ligamentum flavum cells by targeting JAG1 and modulating the Notch signalling pathway

Ossification of the ligamentum flavum (OLF) is a pathology almost only reported in East Asian countries. The leading cause of OLF is thoracic spinal canal stenosis and myelopathy. In this study, the role of miR‐199b‐5p and jagged 1 (JAG1) in primary ligamentum flavum cell osteogenesis was examined. MiR‐199b‐5p was found to be down‐regulated during osteogenic differentiation in ligamentum flavum cells, while miR‐199b‐5p overexpression inhibited osteogenic differentiation. In addition, JAG1 was found to be up‐regulated during osteogenic differentiation in ligamentum flavum cells, while JAG1 knockdown via RNA interference caused an inhibition of Notch signalling and osteogenic differentiation. Moreover, target prediction analysis and dual luciferase reporter assays supported the notion that JAG1 was a direct target of miR‐199b‐5p, with miR‐199b‐5p found to down‐regulate both JAG1 and Notch. Further, JAG1 knockdown was demonstrated to block the effect of miR‐199b‐5p inhibition. These findings imply that miR‐199b‐5p performs an inhibitory role in osteogenic differentiation in ligamentum flavum cells by potentially targeting JAG1 and influencing the Notch signalling pathway.