PSMD14 Targeting Triggers Paraptosis in Breast Cancer Cells by Inducing Proteasome Inhibition and Ca2+ Imbalance

PSMD14, a subunit of the 19S regulatory particles of the 26S proteasome, was recently identified as a potential prognostic marker and therapeutic target in diverse human cancers. Here, we show that the silencing and pharmacological blockade of PSMD14 in MDA-MB 435S breast cancer cells induce paraptosis, a non-apoptotic cell death mode characterized by extensive vacuolation derived from the endoplasmic reticulum (ER) and mitochondria. The PSMD14 inhibitor, capzimin (CZM), inhibits proteasome activity but differs from the 20S proteasome subunit-inhibiting bortezomib (Bz) in that it does not induce aggresome formation or Nrf1 upregulation, which underlie Bz resistance in cancer cells. In addition to proteasome inhibition, the release of Ca²⁺ from the ER into the cytosol critically contributes to CZM-induced paraptosis. Induction of paraptosis by targeting PSMD14 may provide an attractive therapeutic strategy against cancer cells resistant to proteasome inhibitors or pro-apoptotic drugs.     

The Isoxazole Derivative of Usnic Acid Induces an ER Stress Response in Breast Cancer Cells That Leads to Paraptosis-like Cell Death

Derivatives of usnic acid (UA), a secondary metabolite from lichens, were synthesized to improve its anticancer activity and selectivity. Recently we reported the synthesis and activity of an UA isoxazole derivative, named 2b, against cancer cells of different origins. Herein, the molecular mechanisms underlying its activity and efficacy in vivo were tested. The viability of breast cancer or normal cells has been tested using an MTT assay. Cell and organelle morphology was analyzed using light, electron and fluorescence microscopy. Gene expression was evaluated by RNAseq and protein levels were evaluated by Western blotting. In vivo anticancer activity was evaluated in a mice xenograft model. We found that 2b induced massive vacuolization which originated from the endoplasmic reticulum (ER). ER stress markers were upregulated both at the mRNA and protein levels. ER stress was caused by the release of Ca²⁺ ions from the ER by IP3R channels which was mediated, at least partly, by phospholipase C (PLC)-synthetized 1,4,5-inositol triphosphate (IP3). ER stress led to cell death with features of apoptosis and paraptosis. When applied to nude mice with xenografted breast cancer cells, 2b stopped tumour growth. In mice treated with 2b, vacuolization was observed in tumour cells, but not in other organs. This study shows that the antiproliferative activity of 2b relates to the induction of ER stress in cancer, not in healthy, cells and it leads to breast cancer cell death in vitro and in vivo.     

Co-delivery of docetaxel and endostatin by a biodegradable nanoparticle for the synergistic treatment of cervical cancer

Cervical cancer remains a major problem in women''s health worldwide. In this research, a novel biodegradable d-α-tocopheryl polyethylene glycol 1000 succinate-b-poly(ε-caprolactone-ran-glycolide) (TPGS-b-(PCL-ran-PGA)) nanoparticle (NP) was developed as a co-delivery system of docetaxel and endostatin for the synergistic treatment of cervical cancer. Docetaxel-loaded TPGS-b-(PCL-ran-PGA) NPs were prepared and further modified by polyethyleneimine for coating plasmid pShuttle2-endostatin. All NPs were characterized in size, surface charge, morphology, and in vitro release of docetaxel and pDNA. The uptake of coumarin 6-loaded TPGS-b-(PCL-ran-PGA)/PEI-pDsRED by HeLa cells was observed via fluorescent microscopy and confocal laser scanning microscopy. Endostatin expression in HeLa cells transfected by TPGS-b-(PCL-ran-PGA)/PEI-pShuttle2-endostatin NPs was detected using Western blot analysis, and the cell viability of different NP-treated HeLa cells was determined by MTT assay. The HeLa cells from the tumor model, nude mice, were treated with various NPs including docetaxel-loaded-TPGS-b-(PCL-ran-PGA)/PEI-endostatin NPs, and their survival time, tumor volume and body weight were monitored during regimen process. The tumor tissue histopathology was analyzed using hematoxylin and eosin staining, and microvessel density in tumor tissue was evaluated immunohistochemically. The results showed that the TPGS-b-(PCL-ran-PGA)/PEI NPs can efficiently and simultaneously deliver both coumarin-6 and plasmids into HeLa cells, and the expression of endostatin was verified via Western blot analysis. Compared with control groups, the TPGS-b-(PCL-ran-PGA)/PEI-pShuttle2-endostatin NPs significantly decreased the cell viability of HeLa cells (p < 0.01), inhibited the growth of tumors, and even eradicated the tumors. The underlying mechanism is attributed to synergistic anti-tumor effects by the combined use of docetaxel, endostatin, and TPGS released from NPs. The TPGS-b-(PCL-ran-PGA) NPs could function as multifunctional carrier for chemotherapeutic drugs and genetic material delivery, and offer considerable potential as an ideal candidate for in vivo cancer therapy.     

Surface modification of TPGS-b-(PCL-ran-PGA) nanoparticles with polyethyleneimine as a co-delivery system of TRAIL and endostatin for cervical cancer gene therapy

The efficient delivery of therapeutic genes into cells of interest is a critical challenge to broad application of non-viral vector systems. In this research, a novel TPGS-b-(PCL-ran-PGA) nanoparticle modified with polyethyleneimine was applied to be a vector of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and endostatin for cervical cancer gene therapy. Firstly, a novel biodegradable copolymer, TPGS-b-(PCL-ran-PGA), was synthesized and characterized. The nanoparticles were fabricated by an emulsion/solvent evaporation method and then further modified with polyethyleneimine (PEI) carrying TRAIL and/or endostatin genes. The uptake of pIRES2-EGFP and/or pDsRED nanoparticles by HeLa cells were observed by fluorescence microscopy and confocal laser scanning microscopy. The cell viability of TRAIL/endostatin-loaded nanoparticles in HeLa cells was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide assay. Severe combined immunodeficient mice carrying HeLa tumor xenografts were treated in groups of six including phosphate-buffered saline control, blank TPGS-b-(PCL-ran-PGA) nanoparticles, blank TPGS-b-(PCL-ran-PGA)/PEI nanoparticles, and three types of gene nanoparticles. The activity was assessed using average increase in survival time, body weight, and solid tumor volume. All the specimens were then prepared as formalin-fixed and paraffin-embedded tissue sections for hematoxylin-eosin staining. The data showed that the nanoparticles could efficiently deliver plasmids into HeLa cells. The cytotoxicity of the HeLa cells was significantly increased by TRAIL/endostatin-loaded nanoparticles when compared with control groups. The use of TPGS in combination with TRAIL and endostatin had synergistic antitumor effects. In conclusion, the TRAIL/endostatin-loaded nanoparticles offer considerable potential as an ideal candidate for in vivo cancer gene delivery.     

Endoplasmic Reticulum Stress Cooperates in Zearalenone-Induced Cell Death of RAW 264.7 Macrophages

Zearalenone (ZEA) is a fungal mycotoxin that causes cell apoptosis and necrosis. However, little is known about the molecular mechanisms of ZEA toxicity. The objective of this study was to explore the effects of ZEA on the proliferation and apoptosis of RAW 264.7 macrophages and to uncover the signaling pathway underlying the cytotoxicity of ZEA in RAW 264.7 macrophages. This study demonstrates that the endoplasmic reticulum (ER) stress pathway cooperated in ZEA-induced cell death of the RAW 264.7 macrophages. Our results show that ZEA treatment reduced the viability of RAW 264.7 macrophages in a dose- and time-dependent manner as shown by the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide assay (MTT) and flow cytometry assay. Western blots analysis revealed that ZEA increased the expression of glucose-regulated protein 78 (GRP78) and CCAAT/enhancer binding protein homologous protein (CHOP), two ER stress-related marker genes. Furthermore, treating the cells with the ER stress inhibitors 4-phenylbutyrate (4-PBA) or knocking down CHOP, using lentivirus encoded short hairpin interfering RNAs (shRNAs), significantly diminished the ZEA-induced increases in GRP78 and CHOP, and cell death. In summary, our results suggest that ZEA induces the apoptosis and necrosis of RAW 264.7 macrophages in a dose- and time-dependent manner via the ER stress pathway in which the activation of CHOP plays a critical role.     

Crassolide Induces G2/M Cell Cycle Arrest,Apoptosis, and Autophagy in Human Lung Cancer Cells via ROS-Mediated ER Stress Pathways

Crassolide, a cembranoid diterpene extracted from the soft coral Lobophytum crissum, has been proven to possess antioxidant and immunomodulatory properties. In the present study, we assessed the anticancer effects of crassolide on human H460 non-small-cell lung cancer (NSCLC) cells. We found that crassolide exerted cytotoxic effects on H460 cancer cells in vitro, inducing G2/M phase arrest and apoptosis. In addition, in H460 cells exposed to crassolide, the expression of the autophagy-related proteins LC3-II and beclin was increased, while the expression of p62 was decreased. Moreover, inhibiting autophagy with chloroquine (CQ) suppressed the crassolide-induced G2/M arrest and apoptosis of H460 cells. Moreover, we also found that crassolide induced endoplasmic reticulum (ER) stress in lung cancer cells by increasing the expression of ER stress marker proteins and that the crassolide-induced G2/M arrest, apoptosis, and autophagy were markedly attenuated by the ER stress inhibitor 4-phenylbutyric acid (4-PBA). Furthermore, we found that crassolide promoted reactive oxygen species (ROS) production by H460 cells and that the ROS inhibitor N-acetylcysteine (NAC) decreased the crassolide-induced ER stress, G2/M arrest, apoptosis, and autophagy. In conclusion, our findings show that crassolide inhibits NSCLC cell malignant biological behaviors for the first time, suggesting that this effect may be mechanistically achieved by inducing G2/M arrest, apoptosis, and autophagy through ROS accumulation, which activates the ER stress pathway. As a result of our findings, we now have a better understanding of the molecular mechanism underlying the anticancer effect of crassolide, and we believe crassolide might be a candidate for targeted cancer therapy.     

1-(2-Hydroxy-5-methylphenyl)-3-phenyl-1,3-propanedione Induces G1 Cell Cycle Arrest and Autophagy in HeLa Cervical Cancer Cells

The natural agent, 1-(2-hydroxy-5-methylphenyl)-3-phenyl-1,3-propanedione (HMDB), has been reported to have growth inhibitory effects on several human cancer cells. However, the role of HMDB in cervical cancer remains unclear. Herein, we found that HMDB dose- and time-dependently inhibited growth of HeLa cervical cancer cells, accompanied with G1 cell cycle arrest. HMDB decreased protein expression of cyclins D1/D3/E and cyclin-dependent kinases (CDKs) 2/4/6 and reciprocally increased mRNA and protein levels of CDK inhibitors (p15, p16, p21, and p27), thereby leading to the accumulation of hypophosphorylated retinoblastoma (Rb) protein. HMDB also triggered the accumulation of acidic vesicles and formation of microtubule-associated protein-light chain 3 (LC3), followed by increased expression of LC3 and Beclin-1 and decreased expression of p62, suggesting that HMDB triggered autophagy in HeLa cells. Meanwhile, suppression of the expression of survivin and Bcl-2 implied that HMDB-induced autophagy is tightly linked to apoptosis. Exploring the action mechanism, HMDB induced autophagy via the modulation of AMP-activated protein kinase (AMPK) and mTOR signaling pathway rather than the class III phosphatidylinositol 3-kinase pathway. These results suggest that HMDB inhibits HeLa cell growth by eliciting a G1 arrest through modulation of G1 cell cycle regulators and by concomitantly inducing autophagy through the mediation of AMPK-mTOR and Akt-mTOR pathways, and may be a promising antitumor agent against cervical cancer.     

One-Pot Three-Component Synthesis of Novel Diethyl((2-oxo-1,2-dihydroquinolin-3-yl)(arylamino)methyl)phosphonate as Potential Anticancer Agents

With the aim of discovering new anticancer agents, we have designed and synthesized novel α-aminophosphonate derivatives containing a 2-oxoquinoline structure using a convenient one-pot three-component method. The newly synthesized compounds were evaluated for antitumor activities against the A549 (human lung adenocarcinoma cell), HeLa (human cervical carcinoma cell), MCF-7 (human breast cancer cell), and U2OS (human osteosarcoma cell) cancer cell lines in vitro, employing a standard 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay. The results of pharmacological screening indicated that many compounds exhibited moderate to high levels of antitumor activities against the tested cancer cell lines and that most compounds showed more potent inhibitory activities comparable to 5-fluorouracil (5-FU) which was used as a positive control. The mechanism of representative compound 4u (diethyl((2-oxo-1,2-dihydroquinolin-3-yl)(phenyl-amino)methyl)phosphonate) indicated that the compound mainly arrested HeLa cells in S and G2 stages and was accompanied by apoptosis in HeLa cells. This action was confirmed by acridine orange/ethidium bromide staining, Hoechst 33342 staining, and flow cytometry.     

Identification of Novel Pepper Genes Involved in Bax- or INF1-Mediated Cell Death Responses by High-Throughput Virus-Induced Gene Silencing

Hot pepper is one of the economically important crops in Asia. A large number of gene sequences, including expressed sequence tag (EST) and genomic sequences are publicly available. However, it is still a daunting task to determine gene function due to difficulties in genetic modification of a pepper plants. Here, we show the application of the virus-induced gene silencing (VIGS) repression for the study of 459 pepper ESTs selected as non-host pathogen-induced cell death responsive genes from pepper microarray experiments in Nicotiana benthamiana. Developmental abnormalities in N. benthamiana plants are observed in the 32 (7%) pepper ESTs-silenced plants. Aberrant morphological phenotypes largely comprised of three groups: stunted, abnormal leaf, and dead. In addition, by employing the combination of VIGS and Agrobacterium-mediated transient assays, we identified novel pepper ESTs that involved in Bax or INF1-mediated cell death responses. Silencing of seven pepper ESTs homologs suppressed Bax or INF1-induced cell death, five of which suppressed both cell death responses in N. benthamiana. The genes represented by these five ESTs encode putative proteins with functions in endoplasmic reticulum (ER) stress and lipid signaling. The genes represented by the other two pepper ESTs showing only Bax-mediated cell death inhibition encode a CCCH-type zinc finger protein containing an ankyrin-repeat domain and a probable calcium-binding protein, CML30-like. Taken together, we effectively isolated novel pepper clones that are involved in hypersensitive response (HR)-like cell death using VIGS, and identified silenced clones that have different responses to Bax and INF1 exposure, indicating separate signaling pathways for Bax- and INF1-mediated cell death.     

Function of Lipid Storage Droplet 1 (Lsd1) in Wing Development of Drosophila melanogaster

Perilipins are evolutionarily conserved from Drosophila to humans, the lipid storage droplet 1 (Lsd1) is a Drosophila homolog of human perilipin 1. The function of Lsd1 as a regulator of lipolysis in Drosophila has been demonstrated, as the Lsd1 mutant causes an increase of lipid droplet size. However, the functions of this gene during development are still under investigation. In order to determine the function of Lsd1 during development, Lsd1 was knocked down in Drosophila using the GAL4-UAS system. Selective knockdown of Lsd1 in the dorsal wing disc caused an atrophied wing phenotype. The generation of reactive oxygen species in the wing pouch compartment of the Lsd1-knockdown flies was significantly higher than in the control. Immunostaining with caspase-3 antibody revealed a greater number of apoptotic cells in Lsd1-knockdown wing discs than in the control. Cell death by autophagy was also induced in the knockdown flies. Moreover, cells deprived of Lsd1 showed mitochondrial expansion and decreased ATP levels. These results strongly suggest that knockdown of Lsd1 induces mitochondrial stress and the production of reactive oxygen species that result in cell death, via apoptosis and the autophagy pathway. These results highlight the roles of Drosophila Lsd1 during wing development.     

Apigenin Induces Autophagy and Cell Death by Targeting EZH2 under Hypoxia Conditions in Gastric Cancer Cells

Hypoxia is a major obstacle to gastric cancer (GC) therapy and leads to chemoresistance as GC cells are frequently exposed to the hypoxia environment. Apigenin, a flavonoid found in traditional medicine, fruits, and vegetables and an HDAC inhibitor, is a powerful anti-cancer agent against various cancer cell lines. However, detailed mechanisms involved in the treatment of GC using APG are not fully understood. In this study, we investigated the biological activity of and molecular mechanisms involved in APG-mediated treatment of GC under hypoxia. APG promoted autophagic cell death by increasing ATG5, LC3-II, and phosphorylation of AMPK and ULK1 and down-regulating p-mTOR and p62 in GC. Furthermore, our results show that APG induces autophagic cell death via the activation of the PERK signaling, indicating an endoplasmic reticulum (ER) stress response. The inhibition of ER stress suppressed APG-induced autophagy and conferred prolonged cell survival, indicating autophagic cell death. We further show that APG induces ER stress- and autophagy-related cell death through the inhibition of HIF-1α and Ezh2 under normoxia and hypoxia. Taken together, our findings indicate that APG activates autophagic cell death by inhibiting HIF-1α and Ezh2 under hypoxia conditions in GC cells.     

Inhibition of Autophagy Potentiates Atorvastatin-Induced Apoptotic Cell Death in Human Bladder Cancer Cells in Vitro

Statins are cholesterol reduction agents that exhibit anti-cancer activity in several human cancers. Because autophagy is a crucial survival mechanism for cancer cells under stress conditions, cooperative inhibition of autophagy acts synergistically with other anti-cancer drugs. Thus, this study investigates whether combined treatment of atorvastatin and autophagy inhibitors results in enhancing the cytotoxic effects of atorvastatin, upon human bladder cancer cells, T24 and J82, in vitro. To measure cell viability, we performed the EZ-Cytox cell viability assay. We examined apoptosis by flow cytometry using annexin-V/propidium iodide (PI and western blot using procaspase-3 and poly (ADP-ribose) polymerase (PARP) antibodies. To examine autophagy activation, we evaluated the co-localization of LC3 and LysoTracker by immunocytochemistry, as well as the expression of LC3 and p62/sequestosome-1 (SQSTM1) by western blot. In addition, we assessed the survival and proliferation of T24 and J82 cells by a clonogenic assay. We found that atorvastatin reduced the cell viability of T24 and J82 cells via apoptotic cell death and induced autophagy activation, shown by the co-localization of LC3 and LysoTracker. Moreover, pharmacologic inhibition of autophagy significantly enhanced atorvastatin-induced apoptosis in T24 and J82 cells. In sum, inhibition of autophagy potentiates atorvastatin-induced apoptotic cell death in human bladder cancer cells in vitro, providing a potential therapeutic approach to treat bladder cancer.     

Switching the Mode of Cell Death between Apoptosis and Autophagy by Histone Deacetylase 6 Inhibition Levels

Inhibition of histone deacetylase (HDAC) has been demonstrated to be an effective strategy for cancer treatment. In this work, we have developed a new agent Ir-VPA , which exhibits the cell death mode switching between apoptosis and autophagy due to the distinct level of HDAC6 inhibition. Ir-VPA indicates the best anticancer activity to HeLa cells, and could be hydrolyzed due to the high expression of the esterase in HeLa cells. Ir-VPA could accumulate in nuclei, induce severe DNA damages and cell cycle arrest at G2/M phase. The anticancer mechanism of Ir-VPA to HeLa cells was dependent on the HDAC6 inhibitory performance, as the caspase dependent apoptosis at low concentration (IC₅₀) and autophagy with the autophagy flux blockage at high concentration (2×IC₅₀). This is resulted from the distinct inhibitory levels of HDAC6, as moderate/complete inhibition at the concentration of IC₅₀/2×IC₅₀.In the presence of autophagic inhibitor chloroquine, the apoptotic population elevated from 32.7 % to 61.7 %, indicating that Ir-VPA could activate apoptotic process through the autophagolysosome fusion inhibition. Ir-VPA also exhibits excellent antiproliferative behavior to 3D HeLa multicellular tumor spheroids (MCTSs). This work not only provided a new HDAC6 inhibitor and novel anticancer mechanism for the effective treatment of cervical cancer, but also demonstrated the strategy to conjugate the metal fragment with active organic drug to enhance the anticancer performance.     

Stellettin B-Induced Oral Cancer Cell Death via Endoplasmic Reticulum Stress–Mitochondrial Apoptotic and Autophagic Signaling Pathway

Oral squamous cell carcinoma (OSCC) affects tens of thousands of people worldwide. Despite advances in cancer treatment, the 5-year survival rate of patients with late-stage OSCC is low at 50–60%. Therefore, the development of anti-OSCC therapy is necessary. We evaluated the effects of marine-derived triterpene stellettin B in human OC2 and SCC4 cells. Stellettin B dose-dependently decreased the viability of both cell lines, with a significant reduction in OC2 cells at ≥0.1 µM at 24 and 48 h, and in SCC4 cells at ≥1 µM at 24 and 48 h. Terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL)-positive cells were significantly observed at 20 µM of stellettin B at 48 h, with the overexpression of cleaved caspase3 and cleaved poly(ADP-ribose) polymerase (PARP). Moreover, mitochondrial respiratory functions were ablated by stellettin B. Autophagy-related LC3-II/LC3-I ratio and Beclin-1 proteins were increased, whereas p62 was decreased. At 20 µM at 48 h, the expression levels of the endoplasmic reticulum (ER) stress biomarkers calnexin and BiP/GRP78 were significantly increased and mitogen-activated protein kinase (MAPK) signaling pathways were activated. Further investigation using the autophagy inhibitor 3-methyladenine (3-MA) demonstrated that it alleviated stellettin B-induced cell death and autophagy. Overall, our findings show that stellettin B induces the ER stress, mitochondrial stress, apoptosis, and autophagy, causing cell death of OSCC cells.     

Aromadendrin Protects Neuronal Cells from Methamphetamine-Induced Neurotoxicity by Regulating Endoplasmic Reticulum Stress and PI3K/Akt/mTOR Signaling Pathway

Methamphetamine (METH) is a highly addictive drug that induces irreversible damage to neuronal cells and pathological malfunction in the brain. Aromadendrin, isolated from the flowers of Chionanthus retusus, has been shown to have anti-inflammatory or anti-tumor activity. Nevertheless, it has been reported that METH exacerbates neurotoxicity by inducing endoplasmic reticulum (ER) stress via the phosphoinositide 3-kinase/Akt/mammalian target of rapamycin (PI3K/Akt/mTOR) pathway in neuronal cells. There is little evidence that aromadendrin protects cells from neurotoxicity induced by METH. In this study, we found that aromadendrin partially suppressed the METH-induced cell death in SH-SY5y cells without causing cytotoxicity. Aromadendrin regulated METH-induced ER stress by preserving the phosphorylation of the PI3K/Akt/mTOR signaling pathway in METH-exposed SH-SY5y cells. In addition, aromadendrin mitigated METH-induced autophagic and the apoptotic pathways in METH-exposed SH-SY5y cells. Mechanistic studies revealed that pre-treatment with aromadendrin restored the expression of anti-apoptotic proteins in METH-exposed conditions. The inhibitor assay confirmed that aromadendrin-mediated restoration of mTOR phosphorylation protected cells from autophagy and apoptosis in METH-exposed cells. Therefore, these findings suggest that aromadendrin relatively has a protective effect on SH-SY5y cells against autophagy and apoptosis induced by METH via regulation of ER stress and the PI3K/Akt/mTOR signaling pathway.     

Endoplasmic Reticulum Stress Contributed to Dipyridamole-Induced Impaired Autophagic Flux and Glioma Apoptosis

Elevation of intracellular cAMP levels has been implicated in glioma cell proliferation inhibition, differentiation, and apoptosis. Inhibition of phosphodiesterase is a way to elevate intracellular cAMP levels. The present study aimed to investigate the anti-glioma potential of dipyridamole, an inhibitor of phosphodiesterase. Upon treatment with dipyridamole, human U87 glioma cells decreased cell viability, clonogenic colonization, migration, and invasion, along with Noxa upregulation, Endoplasmic Reticulum (ER) stress, impaired autophagic flux, Yes-associated Protein 1 (YAP1) phosphorylation, and YAP1 reduction. Pharmacological and genetic studies revealed the ability of dipyridamole to initiate Noxa-guided apoptosis through ER stress. Additionally, the current study further identified the biochemical role of YAP1 in communicating with ER stress and autophagy under situations of dipyridamole treatment. YAP1 promoted autophagy and protected glioma cells from dipyridamole-induced apoptotic cell death. Dipyridamole impaired autophagic flux and rendered glioma cells more vulnerable to apoptotic cell death through ER stress-inhibitable YAP1/autophagy axis. The overall cellular changes caused by dipyridamole appeared to ensure a successful completion of apoptosis. Dipyridamole also duplicated the biochemical changes and apoptosis in glioma T98G cells. Since dipyridamole has additional biochemical and pharmacological properties, further research centered on the anti-glioma mechanisms of dipyridamole is still needed.     

Twist-1 Up-Regulation in Carcinoma Correlates to Poor Survival

Epithelial-to-mesenchymal transition (EMT) facilitates tumor metastasis. Twist is a basic helix-loop-helix protein that modulates many target genes through E-box-responsive elements. There are two twist-like proteins, Twist-1 and Twist-2, sharing high structural homology in mammals. Twist-1 was found to be a key factor in the promotion of metastasis of cancer cells, and is known to induce EMT. Twist-1 participation in carcinoma progression and metastasis has been reported in a variety of tumors. However, controversy exists concerning the correlation between Twist-1 and prognostic value with respect to carcinoma. A systematic review and meta-analysis were performed to determine whether the expression of Twist-1 was associated with the prognosis of carcinoma patients. This analysis included 17 studies: four studies evaluated lung cancer, three evaluated head and neck cancer, two evaluated breast cancer, two evaluated esophageal cancer, two evaluated liver cancer and one each evaluated osteosarcoma, bladder, cervical and ovarian cancer. A total of 2006 patients were enrolled in these studies, and the median trial sample size was 118 patients. Twist-1 expression was associated with worse overall survival (OS) at both 3 years (hazard ratio “HR” for death = 2.13, 95% CI = 1.86 to 2.45, p < 0.001) and 5 years (HR for death = 2.01, 95% CI = 1.76 to 2.29, p < 0.001). Expression of Twist-1 is associated with worse survival in carcinoma.     

The Critical Role of Membrane Cholesterol in Salmonella-Induced Autophagy in Intestinal Epithelial Cells

It was previously observed that plasma membrane cholesterol plays a critical role in the Salmonella-induced phosphatidylinositol 3-kinase-dependent (PI3K)-dependent anti-inflammatory response in intestinal epithelial cells (IECs). The PI3K/Akt pathway is associated with autophagy which has emerged as a critical mechanism of host defense against several intracellular bacterial pathogens. Plasma membrane contributes directly to the formation of early Atg16L1-positive autophagosome precursors. Therefore, this study aimed to investigate the role of plasma membrane cholesterol on the Salmonella-induced autophagy in IECs. By using methyl-beta-cyclodextrin (MBCD), it was demonstrated that disruption of membrane cholesterol by MBCD enhanced NOD2 and Atg16L1 proteins expression in membrane, and autophagic LC3II proteins expression and LC3 punctae in Salmonella-infected Caco-2 cells, which was counteracted by Atg16L1 siRNA. Nucleotide-binding oligomerization domain-containing protein 2 (NOD2) siRNA enhanced the Salmonella-induced activation of Akt in Caco-2 cells. However, inhibitors of Akt or extracellular signal-regulated kinases (ERK) had no significant effect on Salmonella-induced autophagy Beclin 1 or LC3 proteins expression. In conclusion, our study suggests that cholesterol accumulation in the plasma membrane at the entry site of Salmonella results in the formation of Salmonella-containing vacuole (SCV) and decreased autophagy. Our results offer mechanistic insights on the critical role of membrane cholesterol in the pathogenesis of Salmonella infection in intestinal epithelial cells and the therapeutic potential of its antagonists.     

TP53inp1 Gene Is Implicated in Early Radiation Response in Human Fibroblast Cells

Tumor protein 53-induced nuclear protein-1 (TP53inp1) is expressed by activation via p53 and p73. The purpose of our study was to investigate the role of TP53inp1 in response of fibroblasts to ionizing radiation. γ-Ray radiation dose-dependently induces the expression of TP53inp1 in human immortalized fibroblast (F11hT) cells. Stable silencing of TP53inp1 was done via lentiviral transfection of shRNA in F11hT cells. After irradiation the clonogenic survival of TP53inp1 knockdown (F11hT-shTP) cells was compared to cells transfected with non-targeting (NT) shRNA. Radiation-induced senescence was measured by SA-β-Gal staining and autophagy was detected by Acridine Orange dye and microtubule-associated protein-1 light chain 3 (LC3B) immunostaining. The expression of TP53inp1, GDF-15, and CDKN1A and alterations in radiation induced mitochondrial DNA deletions were evaluated by qPCR. TP53inp1 was required for radiation (IR) induced maximal elevation of CDKN1A and GDF-15 expressions. Mitochondrial DNA deletions were increased and autophagy was deregulated following irradiation in the absence of TP53inp1. Finally, we showed that silencing of TP53inp1 enhances the radiation sensitivity of fibroblast cells. These data suggest functional roles for TP53inp1 in radiation-induced autophagy and survival. Taken together, we suppose that silencing of TP53inp1 leads radiation induced autophagy impairment and induces accumulation of damaged mitochondria in primary human fibroblasts.