TAp73 transcriptionally represses BNIP3 expression

TAp73 is a tumor suppressor transcriptional factor, belonging to p53 family. Alteration of TAp73 in tumors might lead to reduced DNA damage response, cell cycle arrest and apoptosis. Carcinogen-induced TAp73p>−/−p> tumors display also increased angiogenesis, associated to hyperactivition of hypoxia inducible factor signaling. Here, we show that TAp73 suppresses BNIP3 expression, directly binding its gene promoter. BNIP3 is a hypoxia responsive protein, involved in a variety of cellular processes, such as autophagy, mitophagy, apoptosis and necrotic-like cell death. Therefore, through different cellular process altered expression of BNIP3 may differently contribute to cancer development and progression. We found a significant upregulation of BNIP3 in human lung cancer datasets, and we identified a direct association between BNIP3 expression and survival rate of lung cancer patients. Our data therefore provide a novel transcriptional target of TAp73, associated to its antagonistic role on HIF signaling in cancer, which might play a role in tumor suppression.     

Towards the identification of the allosteric Phe-binding site in phenylalanine hydroxylase

The enzyme phenylalanine hydroxylase (PAH) is defective in the inherited disorder phenylketonuria. PAH, a tetrameric enzyme, is highly regulated and displays positive cooperativity for its substrate, Phe. Whether Phe binds to an allosteric site is a matter of debate, despite several studies worldwide. To address this issue, we generated a dimeric model for Phe–PAH interactions, by performing molecular docking combined with molecular dynamics simulations on human and rat wild-type sequences and also on a human G46S mutant. Our results suggest that the allosteric Phe-binding site lies at the dimeric interface between the regulatory and the catalytic domains of two adjacent subunits. The structural and dynamical features of the site were characterized in depth and described. Interestingly, our findings provide evidence for lower allosteric Phe-binding ability of the G46S mutant than the human wild-type enzyme. This also explains the disease-causing nature of this mutant.     

The Immunocytochemical Detection of P53 Protein In Cytological Specimens: Technical Considerations

The p53 gene encodes a 393 amino acid nuclear phosphoprotein that appears to act as a cell cycle checkpoint, possibly by transactivating other target genes. Abnormalities of the p53 gene are common in a wide range of human tumours and are associated in many cases with immunologically detectable p53 protein. Detection of p53 immunoreactivity is uncommon in normal cells, but is frequently seen in neoplasia. Here we define the optimum conditions for the detection of p53 immunoreactivity in cytological material, including fixation and storage. Immersion in acetone-methanol for 10 min is optimal, and after air drying, smears or cytospin preparations can be stored at - 70°C for at least 6 months. We describe the range of controls necessary, including the use of positive control cell lines with known mutations of the p53 gene and defined abnormalities of p53 protein. Negative controls should include cell lines (or strains) with no p53 abnormality as well as the conventional negative immunological controls. It is only with these technical caveats and controls that p53 immunoreactivity can be performed reliably on cytological specimens. Le géne p53 code pour une phosphoprotéine nucléaire de 393 acides aminés qui semble jouer en rôle dans la régulation du cycle cellulaire, probablement par transactivation d'autres gènes cibles. Les anomalies du gène p53 sont présentes dans un large éventail de tumeurs humaines et sont associées a la présence d'une protéine p53 détectable immunologiquement. La détection d'une immunoréactivité anti p53 est rare dans les cellules normales alors qu'elle est fréquente dans les tumeurs. Nous avons défini dans ce travail les conditions optimales pour la détection de l'immunoréactivité anti p53 sur matériel cytologique, y compris les conditions de fixation et de conservation. L'immersion dans l'acétone-méthanol pendant 10 minutes est optimale. Aprés séchage à l'air, les frottis ou les préparations par cytocentrifugation peuvent être stockés à—70°C pendant au moins 6 mois. Nous décrivons aussi l'éventail des contrôles nécessaires incluant I'utilisation, comme contrôle positif, de lignées cellulaires avec des mutations connues du gène p53 et des anomalies définies de la protéine p53. Les contrôles négatifs doivent comporter des lignées cellulaires (ou des espèces) sans anomalie de p53 ainsi que les contrôles immunologiques négatifs convrentionnels. C'est seulement lorsque ces précautions techniques et ces contrôles sont respectés que l'immunoréactivité anti p53 peut être étudiée valablement sur les prélèvements cytologiques. Das p53 kodiert ein aus 393 Aminosären bestehendes Phosphoprotein, das offensichtlich den Zellzyklus blockiert, möglicherweise durch Aktivierung anderer Gene. Veränderungen des p53-Gens wurden in zahlreichen menschlischen Tumoren nachgewiesen, sodaß eine positive Reaktion in Neoplasien häufig, in Normalzellen jedoch ungewöhnlich ist. Die optimalen Bedingungen für den p53-Nachweis in cytologischem Material werden hinsichtlich Fixation und Lagerung untersucht. Eine 10minütige Aceton-Methanol-Fixierung mit anschlies-sender Lufttrocknung erlaubt die Lagerung von Ausstrichen und Cytozentrifugen-präparaten bei - 70°C für mindestens 6 Monate. Die erforderlichen Kontrollen einschließlich positiver Zellinien mit bekannten Mutationen des p53-Gens und definierten Anomalien des Proteins werden beschrieben. Negativkontrollen sollten Zellinien ohne p53-Anomalie ebenso umfassen wie die üblichen negativen immunologischen Kontrollen. Nur unter diesen Bedingungen ist ein zuverlässiger Nachweis von p53 mögloch.     

Long noncoding RNA FBXL19-AS1 induces tumor growth and metastasis by sponging miR-203a-3p in lung adenocarcinoma

The pivotal roles of long noncoding RNAs have been reported in various cancers. Recently, FBXL19-AS1 was proposed to be involved in tumor progression. However, its role in lung adenocarcinoma (LUAD) remains elusive. In this study, we observed that FBXL19-AS1 was significantly upregulated in LUAD tissues and high FBXL19-AS1 expression in LUAD was associated with a poor prognosis. Nevertheless, miR-203-3p showed the opposite effect. Moreover, cell viability and apoptosis analysis revealed that FBXL19-AS1 knockdown could arrest LUAD cells in G0/G1 phase and inhibit cell proliferation, migration and invasion in vitro and inhibited LUAD tumor progress in vivo. Mechanistically, we identified FBXL19-AS1 could act as a miR-203a-3p sponge using dual-luciferase reporter assay. In addition, we demonstrated that downregulation of miR-203a-3p reversed growth inhibition of LUAD cells caused by FBXL19-AS1 knockdown. Finally, FBXL19-AS1/miR-203a-3p axis was found to associate with baculoviral IAP repeat-containing protein 5.1-A-like (survivin), distal-less homeobox 5, E2F transcription factor 1, and zinc finger E-box binding homeobox 2 to regulate metastasis in LUAD cells. This study reveals a significance and mechanism of FBXL19-AS1 in LUAD proliferation and metastasis and offers a potential prognostic marker and a therapeutic target for patients with LUAD.     

Investigation of role of aspartame on apoptosis process in HeLa cells -->

Aspartame is an artificial sweetener used as an alternate for sugar in several foods and beverages. The study reports that consumption of aspartame containing product could lead to cancer. However, the effect of aspartame on apoptosis process in cancer is not yet understood clearly. HeLa cells were exposed to different concentrations (0.01–0.05 mg/ml) of aspartame for 48 h. Cytotoxicity of aspartame on cancer cells was determined by SRB assay. The result indicates no significant changes on cell viability. Aspartame suppresses apoptosis process in cancer cells by down-regulation of mRNA expression of tumor suppressor gene p53, and pro-apoptotic gene bax. It up-regulates anti-apoptotic gene bcl-2 mRNA expression. In addition, Ki 67 and PCNA mRNA, and protein expressions were determined. Taking all these together, we conclude that aspartame may be a potent substance to slow-down the apoptosis process in HeLa cells. Further works are ongoing to understand the biochemical and molecular mechanism of aspartame in cancer cells.     

Determination of G-protein levels,ADP-ribosylation by cholera and pertussis toxins and the regulation of adenylyl cyclase activity in liver plasma membranes from lean and genetically diabetic (db/db)

Liver plasma membranes prepared from genetically diabetic (db/db) mice expressed levels of G_i α-2, G_i α-3 and G-protein β-subunits that were reduced by some 75, 63 and 73% compared with levels seen in membranes from lean animals. In contrast, there were no significant differences in the expression of the 42 and 45 kDa forms of G_s α-subunits. Pertussis toxin-catalysed ADP-ribosylation of membranes from lean animals identified a single 41 kDa band whose labelling was reduced by some 86% in membranes from diabetic animals. Cholera toxin-catalysed ADP-ribosylation identified two forms of G_s α-subunits whose labelling was about 4-fold greater in membranes from diabetic animals compared with those from lean animals. Maximal stimulations of adenylyl cyclase activity by forskolin (100 μM), GTP (100 μM), p[NH]ppG (100 μM), NaF (10 mM) and glucagon (10 μM) were similar in membranes from lean and diabetic animals, whereas stimulation by isoprenaline (100 μM) was lower by about 22%. Lower concentrations (EC₅₀-60 nM) of p[NH]ppG were needed to activate adenylyl cyclase in membranes from diabetic animals compared to those from lean animals (EC₅₀-158 nM). As well as causing activation, p[NH]ppG was capable of eliciting a pertussis toxin-sensitive inhibitory effect upon forskolin-stimulated adenylyl cyclase activity in membranes from both lean and diabetic animals. However, maximal inhibition of adenylyl cyclase activity in membranes from diabetic animals was reduced to around 60% of that found using membranes from lean animals. Pertussis toxin-treatment in vivo enhanced maximal stimulation of adenylyl cyclase by glucagon, isoprenaline and p[NH]ppG through a process suggested to be mediated by the abolition of functional G_i activity. The lower levels of expression of G-protein β-subunits, in membranes from diabetic compared with lean animals, is suggested to perturb the equilibria between holomeric and dissociated G-protein subunits. We suggest that this may explain both the enhanced sensitivity of adenylyl cyclase to stimulation by p[NH]ppG in membranes from diabetic animals and the altered ability of pertussis and cholera toxins to catalyse the ADP-ribosylation of G-proteins in membranes from these two animals.     

Propofol induces oxidative stress and apoptosis in vitro via regulating miR-363-3p/CREB signalling axis

Propofol, a generally used anaesthetic in patients care, has been proven to induce neurotoxicity. Studies have shown that miR-363-3p was closely related to neurological dysfunction, and the up-regulated miR-363-3p was recognized to be participate in propofol-induced neurotoxicity. However, the mechanisms and functions of miR-363-3p in propofol-induced neurotoxicity remain rarely reported. The aim of our research was to clarify the potential effects of miR-363-3p in neurotoxicity induced by propofol. SH-SY5Y cells were treated with propofol, miR-363-3p inhibitor or sh-CREB. quantitative real-time polymerase chain reaction and western blotting were applied to detect the expression of miR-363-3p, CREB, Bax, Bcl-2, cleaved caspase-9 and cleaved caspase-3 at the mRNA and/or protein level, respectively. The levels of lactate dehydrogenase (LDH), superoxide dismutase (SOD) and malondialdehyde (MDA) in cell supernatant were detected using different kits. Flow cytometry and MTT assay were applied for assessing the functions of miR-363-3p and CREB on cell ability in cellular activity and apoptotic rate. In addition, Bioinformatic analysis and luciferase assay verified the relationship between 3′-UTR of CREB and miR-363-3p. Our data indicated that the cell viability decreased with the increasing propofol concentration. Bioinformatic analysis and luciferase assay suggested that 3′-UTR of transcript of CREB might be a binding site of miR-363-3p, and miR-363-3p could negatively regulate the expression of CREB. The changes in reactive oxygen species, LDH, SOD and MDA suggested that propofol mediates oxidative stress and apoptosis via modulating miR-363-3p/CREB axis. Propofol induces oxidative stress and apoptosis via affecting miR-363-3p/CREB axis in SH-SY5Y cells, suggesting miR-363-3p down-regulation may act as a novel strategy to ameliorate the propofol-induced neurotoxicity. Significance of the study: The present study demonstrated that propofol induces oxidative stress and apoptosis via affecting miR-363-3p/CREB axis in SH-SY5Y cells, suggesting miR-363-3p down-regulation may act as a novel strategy to ameliorate the propofol-induced neurotoxicity.     

Bone marrow-derived mesenchymal stem cells repair severe acute pancreatitis by secreting miR-181a-5p to target PTEN/Akt/TGF-β1 signaling

BackgroundSevere acute pancreatitis (SAP) is associated with high morbidity and mortality. Bone marrow mesenchymal stem cells (BMSCs) have shown obvious protective effect on SAP. However, little is known about the underlying mechanism. The objective of this study is to unravel the role and regulatory mechanism of miR-181a-5p in BMSCs-mediated pancreatic repair.MethodsBMSCs were isolated from Sprague-Dawley rats and characterized by flow cytometry and Oil Red O staining. Sodium taurocholate- and caerulein-induced models were used as SAP models in vivo and in vitro, respectively. Pancreatic injury were evaluated by H&E and histopathological analysis, as well as by measuring levels of amylase, lipase and cytokines. qRT-PCR and western blotting were performed to detect the level of miR-181a-5p and the protein levels of PTEN/Akt, respectively. ELISA was conducted to detect the levels of TNF-α, IL-1β, IL-6, angiopoietin, IL-4, IL-10 and TGF-β1. The apoptotic rate of AR42 J cells was quantitated by concurrent staining with Annexin-V-FITC and PI.ResultsBMSCs significantly attenuated pancreatic injury in SAP rats by reducing inflammatory infiltration and necrosis, and this effect was abolished by CXCR4 agonist AMD3100. ADM3100 exhibited more severe pancreatic injury and decreased miR-181a-5p levels in the pancreas and serum compared to SAP group. Overexpression of miR-181a-5p in BMSCs (BMSCs-miR-181a-5p) markedly potentiated the protective effect of BMSCs by reducing histological damage and levels of amylase and lipase. Moreover, BMSCs-miR-181a-5p dramatically reduced levels of angiopoietin, TNF-α, IL-1β and IL-6, but induced the levels of IL-4 and IL-10. In caerulein-treated AR42 J cells, co-culturing of BMSCs-miR-181a-5p alleviated caerulein-induced increase of amylase and lipase, and apoptosis via PTEN/Akt/TGF-β1 signaling.ConclusionBMSCs alleviate SAP and reduce inflammatory responses and apoptosis by secreting miR-181a-5p to target PTEN/Akt/TGF-β1 signaling. Hence, BMSCs-miR-181a-5p could serve as potential therapeutic target for SAP.     

Elevated PRC1 in gastric carcinoma exerts oncogenic function and is targeted by piperlongumine in a p53‐dependent manner

Gastric carcinoma is one of the most common malignancies worldwide and the second most frequent cause of cancer‐related death in China. Protein regulator of cytokinesis 1 (PRC1) is involved in cytokinesis and plays key roles in microtubule organization in eukaryotes. This study was aimed to analyse the expression and to investigate the functional role of PRC1 in gastric tumorigenesis. The expression of PRC1 was evaluated by qRT‐PCR, Western blot and immunohistochemistry. The biological function of PRC1 was determined by CCK‐8 proliferation assays, monolayer colony formation, xenografted nude mice and cell invasion assays by shRNA‐mediated knockdown in AGS and HGC27 cells. The regulation of PRC1 expression by piperlongumine was also investigated using dual‐luciferase reporter assay and ChIP‐qPCR analysis. PRC1 was up‐regulated in primary gastric cancers. Overexpression of PRC1 in gastric cancers was associated with poor disease‐specific survival and overall survival. PRC1 knockdown in AGS and HGC27 cell lines suppressed proliferation, reduced monolayer colony formation, inhibited cell invasion and migration ability and induced cell‐cycle arrest and apoptosis. Inhibition of PRC1 also suppressed tumour growth in vivo. We finally confirmed that PRC1 is a novel downstream target of piperlongumine in gastric cancer. Our findings supported the oncogenic role of PRC1 in gastric carcinogenesis. PRC1 might serve as a prognostic biomarker and potential therapeutic target for gastric carcinoma.