bafilomycin-a1 and Lung-Neoplasms

Activated Cdc42-associated kinase 1 (ACK1) is a promising druggable target for cancer, but its inhibitors only showed moderate effects in clinical trials. The study aimed to investigate the underlying mechanisms and improve the antitumor efficacy of ACK1 inhibitors.. RNA-seq was performed to determine the downstream pathways of ACK. Using Lasso Cox regression analysis, we built a risk signature with ACK1-related autophagy genes in the lung adenocarcinoma (LUAD) patients from The Cancer Genome Atlas (TCGA) project. The performance of the signature in predicting the tumor immune environment and response to immunotherapy and chemotherapy were assessed in LUAD. CCK8, mRFP-GFP-LC3 assay, western blot, colony formation, wound healing, and transwell migration assays were conducted to evaluate the effects of the ACK1 inhibitor on lung cancer cells. A subcutaneous NSCLC xenograft model was used for in vivo study.. RNA-seq revealed the regulatory role of ACK1 in autophagy. Furthermore, the risk signature separated LUAD patients into low- and high-risk groups with significantly different prognoses. The two groups displayed different tumor immune environments regarding 28 immune cell subsets. The low-risk groups showed high immune scores, high CTLA4 expression levels, high immunophenoscore, and low DNA mismatch repair capacity, suggesting a better response to immunotherapy. This signature also predicted sensitivity to commonly used chemotherapy and targeted drugs. In vitro, the ACK1 inhibitors (AIM-100 and Dasatinib) appeared to trigger adaptive autophagy-like response to protect lung cancer cells from apoptosis and activated the AMPK/mTOR signaling pathway, partially explaining its moderate antitumor efficacy. However, blocking lysosomal degradation with chloroquine/Bafilamycine A1 or inhibiting AMPK signaling with compound C/shPRKAA1 enhanced the ACK1 inhibitor's cytotoxic effects on lung cancer cells. The efficacy of the combined therapy was also verified using a mouse xenograft model.. The resulting signature from ACK1-related autophagy genes robustly predicted survival and drug sensitivity in LUAD. The lysosomal degradation inhibition improved the therapeutic effects of the ACK1 inhibitor, suggesting a potential role for autophagy in therapy evasion.

Topics: Adenocarcinoma of Lung; AMP-Activated Protein Kinases; Animals; Humans; Lung Neoplasms; Macrolides; Mice

The novel SARS-CoV-2 Omicron variant (B.1.1.529), first found in early November 2021, has sparked considerable global concern and it has >50 mutations, many of which are known to affect transmissibility or cause immune escape. In this study, we sought to investigate the virological characteristics of the Omicron variant and compared it with the Delta variant which has dominated the world since mid-2021. Omicron variant replicated more slowly than the Delta variant in transmembrane serine protease 2 (TMPRSS2)-overexpressing VeroE6 (VeroE6/TMPRSS2) cells. Notably, the Delta variant replicated well in Calu3 cell line which has robust TMPRSS2 expression, while the Omicron variant replicated poorly in this cell line. Competition assay showed that Delta variant outcompeted Omicron variant in VeroE6/TMPRSS2 and Calu3 cells. To confirm the difference in entry pathway between the Omicron and Delta variants, we assessed the antiviral effect of bafilomycin A1, chloroquine (inhibiting endocytic pathway), and camostat (inhibiting TMPRSS2 pathway). Camostat potently inhibited the Delta variant but not the Omicron variant, while bafilomycin A1 and chloroquine could inhibit both Omicron and Delta variants. Moreover, the Omicron variant also showed weaker cell-cell fusion activity when compared with Delta variant in VeroE6/TMPRSS2 cells. Collectively, our results suggest that Omicron variant infection is not enhanced by TMPRSS2 but is largely mediated via the endocytic pathway. The difference in entry pathway between Omicron and Delta variants may have an implication on the clinical manifestations or disease severity.

Topics: Animals; Carcinoma, Non-Small-Cell Lung; Cell Line, Tumor; Chlorocebus aethiops; Chloroquine; COVID-19; Endocytosis; Esters; Guanidines; Humans; Immune Evasion; Lung Neoplasms; Macrolides; Recombinant Proteins; SARS-CoV-2; Serine Endopeptidases; Vero Cells; Virus Cultivation; Virus Internalization; Virus Replication; Whole Genome Sequencing

Sulforaphane-N-acetyl-cysteine (SFN-NAC) is a potential drug to inhibit human non-small cell lung cancer (NSCLC), but the underlying mechanisms are elusive. Here, we uncovered that SFN-NAC induced apoptosis via flow cytometer assay and transmission electron microscopy. Further, SFN-NAC increased LC3 II/LC3 I and the number of LC3 punctas, but Western blot showed that SFN-NAC inhibited cell autophagy in response to a co-treatment of Bafilomycin A1 and SFN-NAC. Furthermore, immunofluorescence staining and Western blot showed that SFN-NAC triggered microtubule disruption causing apoptosis via downregulating α-tubulin and phosphorylated ERK1/2-mediated Stathmin-1. Besides, SFN-NAC upregulated Hsp70 via phosphorylating ERK1/2. Confocal microscopy and immunoprecipitation assay showed that SFN-NAC promoted the colocalization and interaction of Hsp70 and α-tubulin; knockdown of Hsp70 enhanced SFN-NAC-induced microtubule disruption, lowered LC3 II/LC3 I and promoted apoptosis. Interestingly, tissue microarray analysis showed that the increased expression of either α-tubulin or Hsp70 correlated to NSCLC malignant grading, indicating that microtubule and Hsp70 are two key targets for SFN-NAC. These results will give us a new insight into SFN-NAC-induced apoptosis so that we develop more efficient therapeutics to treat NSCLC.

Topics: Acetylcysteine; Aged; Anticarcinogenic Agents; Apoptosis; Autophagy; Carcinoma, Non-Small-Cell Lung; Cell Line, Tumor; Cell Proliferation; Cell Survival; Female; HSP70 Heat-Shock Proteins; Humans; Isothiocyanates; Lung Neoplasms; Macrolides; Male; Microtubules; Middle Aged; Phenotype; Stathmin; Sulfoxides; Tissue Array Analysis; Tubulin

Molecular alterations that confer phenotypic advantages to tumors can also expose specific therapeutic vulnerabilities. To search for potential treatments that would selectively affect metastatic cells, we examined the sensitivity of lineage-related human bladder cancer cell lines with different lung colonization abilities to chloroquine (CQ) or bafilomycin A

Topics: Animals; Cell Line, Tumor; Chloroquine; Drug Resistance, Neoplasm; Gene Expression Regulation, Neoplastic; Humans; Inhibitor of Differentiation Proteins; Lung Neoplasms; Lysosomes; Macrolides; Mice; Neoplasm Metastasis; Neoplasm Proteins; Urinary Bladder Neoplasms

Studies of radiation interaction with tumor cells often focus on apoptosis as an end point; however, clinically relevant doses of radiation also promote autophagy and senescence. Moreover, functional p53 has frequently been implicated in contributing to radiation sensitivity through the facilitation of apoptosis. To address the involvement of apoptosis, autophagy, senescence and p53 status in the response to radiation, the current studies utilized isogenic H460 non-small cell lung cancer cells that were either p53-wild type (H460wt) or null (H460crp53). As anticipated, radiosensitivity was higher in the H460wt cells than in the H460crp53 cell line; however, this differential radiation sensitivity did not appear to be a consequence of apoptosis. Furthermore, radiosensitivity did not appear to be reduced in association with the promotion of autophagy, as autophagy was markedly higher in the H460wt cells. Despite radiosensitization by chloroquine in the H460wt cells, the radiation-induced autophagy proved to be essentially nonprotective, as inhibition of autophagy via 3-methyl adenine (3-MA), bafilomycin A1 or ATG5 silencing failed to alter radiation sensitivity or promote apoptosis in either the H460wt or H460crp53 cells. Radiosensitivity appeared to be most closely associated with senescence, which occurred earlier and to a greater extent in the H460wt cells. This finding is consistent with the in-depth proteomics analysis on the secretomes from the H460wt and H460crp53 cells (with or without radiation exposure) that showed no significant association with radioresistance-related proteins, whereas several senescence-associated secretory phenotype (SASP) factors were upregulated in H460wt cells relative to H460crp53 cells. Taken together, these findings indicate that senescence, rather than apoptosis, plays a central role in determination of radiosensitivity; furthermore, autophagy is likely to have minimal influence on radiosensitivity under conditions where autophagy takes the nonprotective form.

Topics: Apoptosis; Autophagy; Carcinoma, Non-Small-Cell Lung; Cell Line, Tumor; Chromatography, High Pressure Liquid; Genes, p53; Humans; Lung Neoplasms; Macrolides; Radiation Tolerance; Tandem Mass Spectrometry

Studying the intracellular distribution of pharmacological agents, including anticancer compounds, is of central importance in biomedical research. It constitutes a prerequisite for a better understanding of the molecular mechanisms underlying drug action and resistance development. Hyperactivated fibroblast growth factor receptors (FGFRs) constitute a promising therapy target in several types of malignancies including lung cancer. The clinically approved small-molecule FGFR inhibitor nintedanib exerts strong cytotoxicity in FGFR-driven lung cancer cells. However, subcellular pharmacokinetics of this compound and its impact on therapeutic efficacy remain obscure.. 3-dimensional fluorescence spectroscopy was conducted to asses cell-free nintedanib fluorescence properties. MTT assay was used to determine the impact of the lysosome-targeting agents bafilomycin A1 and chloroquine combined with nintedanib on lung cancer cell viability. Flow cytometry and live cell as well as confocal microscopy were performed to analyze uptake kinetics as well as subcellular distribution of nintedanib. Western blot was conducted to investigate protein expression. Cryosections of subcutaneous tumor allografts were generated to detect intratumoral nintedanib in mice after oral drug administration.. Here, we report for the first time drug-intrinsic fluorescence properties of nintedanib in living and fixed cancer cells as well as in cryosections derived from allograft tumors of orally treated mice. Using this feature in conjunction with flow cytometry and confocal microscopy allowed to determine cellular drug accumulation levels, impact of the ABCB1 efflux pump and to uncover nintedanib trapping into lysosomes. Lysosomal sequestration - resulting in an organelle-specific and pH-dependent nintedanib fluorescence - was identified as an intrinsic resistance mechanism in FGFR-driven lung cancer cells. Accordingly, combination of nintedanib with agents compromising lysosomal acidification (bafilomycin A1, chloroquine) exerted distinctly synergistic growth inhibitory effects.. Our findings provide a powerful tool to dissect molecular factors impacting organismal and intracellular pharmacokinetics of nintedanib. Regarding clinical application, prevention of lysosomal trapping via lysosome-alkalization might represent a promising strategy to circumvent cancer cell-intrinsic nintedanib resistance.

Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Cell Line, Tumor; Cell Proliferation; Drug Synergism; Fluorescence; Humans; Indoles; Lung; Lung Neoplasms; Lysosomes; Macrolides; Mice; Phosphorylation; Receptors, Fibroblast Growth Factor; Signal Transduction; Xenograft Model Antitumor Assays

Ursolic acid (UA) is a pentacyclic triterpenoid with recognized anticancer properties. We prepared a series of new A-ring cleaved UA derivatives and evaluated their antiproliferative activity in non-small cell lung cancer (NSCLC) cell lines using 2D and 3D culture models. Compound 17, bearing a cleaved A-ring with a secondary amide at C3, was found to be the most active compound, with potency in 2D systems. Importantly, even in 3D systems, the effect was maintained albeit a slight increase in the IC50. The molecular mechanism underlying the anticancer activity was further investigated. Compound 17 induced apoptosis via activation of caspase-8 and caspase-7 and via decrease of Bcl-2. Moreover, induction of autophagy was also detected with increased levels of Beclin-1 and LC3A/B-II and decreased levels of mTOR and p62. DNA synthetic capacity and cell cycle profiles were not affected by the drug, but total RNA synthesis was modestly but significantly decreased. Given its activity and mechanism of action, compound 17 might represent a potential candidate for further cancer research.

Topics: Antineoplastic Agents; Apoptosis; Autophagy; Carcinoma, Non-Small-Cell Lung; Cell Line, Tumor; Chemistry Techniques, Synthetic; DNA; Drug Screening Assays, Antitumor; Humans; Lung Neoplasms; Protein Biosynthesis; RNA; Triterpenes; Ursolic Acid

Cucurbitacin E (CuE) is a triterpenoid with potent anticancer activities while the underlying mechanisms remain elusive. In the present study, the anticancer effects of CuE on 95D lung cancer cells were investigated. CuE decreased cell viability, inhibited colony formation, and increased reactive oxygen species (ROS) in a concentration-dependent manner, which were reversed by N-acetyl-l-cysteine (NAC). CuE induced apoptosis as determined by JC-1 staining, expression of Bcl-2 family proteins, cleavage of caspases, and TUNEL staining. NAC and Ac-DEVD-CHO partially reversed CuE-induced cleavage of caspase-3, caspase-7, and PARP. Furthermore, CuE caused accumulation of autophagic vacuoles and concentration- and time-dependent expression of LC3II protein. Autophagy inhibitors chloroquine and bafilomycin A1 enhanced CuE-induced LC3II expression and cell death. CuE-triggered protein expression of p-AKT, p-mTOR, Beclin-1, and p-ULK1 was partially reversed by NAC pretreatment. In addition, CuE treatment damaged F-actin without affecting β-tubulin as confirmed by immunofluorescence. In conclusion, CuE induced ROS-dependent apoptosis through Bcl-2 family and caspases in 95D lung cancer cells. Furthermore, CuE induced protective autophagy mediated by ROS through AKT/mTOR pathway. This study provides novel roles of ROS in the anticancer effect of CuE.

Topics: Acetylcysteine; Apoptosis; Autophagy; Blotting, Western; Caspase 3; Caspase 7; Cell Line, Tumor; Cell Proliferation; Chloroquine; Drug Synergism; Humans; Lung Neoplasms; Macrolides; Membrane Potential, Mitochondrial; Microscopy, Fluorescence; Microtubule-Associated Proteins; Poly(ADP-ribose) Polymerases; Proto-Oncogene Proteins c-bcl-2; Reactive Oxygen Species; Triterpenes

Chronic lung inflammation is accepted as being associated with the development of lung cancer caused by nickel exposure. Therefore, identifying the molecular mechanisms that lead to a nickel-induced sustained inflammatory microenvironment that causes transformation of human bronchial epithelial cells is of high significance. In the current studies, we identified SQSTM1/p62 as a novel nickel-upregulated protein that is important for nickel-induced inflammatory TNF expression, subsequently resulting in transformation of human bronchial epithelial cells. We found that nickel exposure induced SQSTM1 protein upregulation in human lung epithelial cells in vitro and in mouse lung tissues in vivo. The SQSTM1 upregulation was also observed in human lung squamous cell carcinoma. Further studies revealed that the knockdown of SQSTM1 expression dramatically inhibited transformation of human lung epithelial cells upon chronic nickel exposure, whereas ectopic expression of SQSTM1 promoted such transformation. Mechanistic studies showed that the SQSTM1 upregulation by nickel was the compromised result of upregulating SQSTM1 mRNA transcription and promoting SQSTM1 protein degradation. We demonstrated that nickel-initiated SQSTM1 protein degradation is mediated by macroautophagy/autophagy via an MTOR-ULK1-BECN1 axis, whereas RELA is important for SQSTM1 transcriptional upregulation following nickel exposure. Furthermore, SQSTM1 upregulation exhibited its promotion of nickel-induced cell transformation through exerting an impetus for nickel-induced inflammatory TNF mRNA stability. Consistently, the MTOR-ULK1-BECN1 autophagic cascade acted as an inhibitory effect on nickel-induced TNF expression and cell transformation. Collectively, our results demonstrate a novel SQSTM1 regulatory network that promotes a nickel-induced tumorigenic effect in human bronchial epithelial cells, which is negatively controlled by an autophagic cascade following nickel exposure.

Topics: Adenine; Animals; Autophagy; Autophagy-Related Protein-1 Homolog; Beclin-1; Bronchi; Cell Line, Tumor; Cell Transformation, Neoplastic; Epithelial Cells; Humans; Inflammation; Intracellular Signaling Peptides and Proteins; Lung Neoplasms; Macrolides; Male; Mice, Inbred C57BL; Nickel; Sequestosome-1 Protein; Signal Transduction; TOR Serine-Threonine Kinases; Transcription, Genetic; Tumor Necrosis Factor-alpha; Up-Regulation

Despite excellent initial clinical responses of non-small cell lung cancer (NSCLC) patients to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs), many patients eventually develop resistance. According to a recent report, vacuolar H+ ATPase (vATPase) is overexpressed and is associated with chemotherapy drug resistance in NSCLC. We investigated the combined effects of EGFR TKIs and vATPase inhibitors and their underlying mechanisms in the regulation of NSCLC cell death. We found that combined treatment with EGFR TKIs (erlotinib, gefitinib, or lapatinib) and vATPase inhibitors (bafilomycin A1 or concanamycin A) enhanced synergistic cell death compared to treatments with each drug alone. Treatment with bafilomycin A1 or concanamycin A led to the induction of Bnip3 expression in an Hif-1α dependent manner. Knock-down of Hif-1α or Bnip3 by siRNA further enhanced cell death induced by bafilomycin A1, suggesting that Hif-1α/Bnip3 induction promoted resistance to cell death induced by the vATPase inhibitors. EGFR TKIs suppressed Hif-1α and Bnip3 expression induced by the vATPase inhibitors, suggesting that they enhanced the sensitivity of the cells to these inhibitors by decreasing Hif-1α/Bnip3 expression. Taken together, we conclude that EGFR TKIs enhance the sensitivity of NSCLC cells to vATPase inhibitors by decreasing Hif-1α/Bnip3 expression. We suggest that combined treatment with EGFR TKIs and vATPase inhibitors is potentially effective for the treatment of NSCLC.

Topics: Antineoplastic Combined Chemotherapy Protocols; Carcinoma, Non-Small-Cell Lung; Cell Line, Tumor; Cell Survival; Dose-Response Relationship, Drug; Drug Resistance, Neoplasm; ErbB Receptors; Erlotinib Hydrochloride; Gefitinib; Humans; Hypoxia-Inducible Factor 1, alpha Subunit; Lapatinib; Lung Neoplasms; Macrolides; Membrane Proteins; Protein Kinase Inhibitors; Proto-Oncogene Proteins; Quinazolines; RNA Interference; Transfection; Vacuolar Proton-Translocating ATPases

The recent advances in RNA interference (RNAi) technology provided novel and promising solutions for human cancer treatment. In this study, the application of dual pH-responsive cationic micellar nanoparticles for small interfering RNA (siRNA) and paclitaxel (PTX) co-delivery to overcome cancer multidrug resistance (MDR) is reported. The in vitro siRNA transfection shows that siRNA-luciferase (Luc) loaded micelleplexes efficiently silences Luc expression in various carcinoma cell lines. The Luc knockdown ability of the micelleplexes can be enhanced by choloquine (CQ) co-incubation. However, is abolished by bafilomycin-A1 (Baf-A1) treatment. The micelleplexes are further exploited for co-delivery of siRNA-Bcl-2 and PTX to Bcl-2 overexpressing A549 lung cancer cells (A549-Bcl-2). The experimental results show that the micelleplexes could sensitize A549-Bcl-2 cells to PTX via down-regulation of anti-apoptosis gene of Bcl-2, suggesting that PDMA-b-PDPA micelleplexes are promising nanovectors for siRNA and anti-cancer drug co-delivery to overcome cancer MDR.

Topics: Antineoplastic Agents, Phytogenic; Apoptosis; Cell Line, Tumor; Chloroquine; Drug Carriers; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Gene Knockdown Techniques; Humans; Hydrogen-Ion Concentration; Luciferases; Lung Neoplasms; Macrolides; Micelles; Nanoparticles; Paclitaxel; Polymethacrylic Acids; Proto-Oncogene Proteins c-bcl-2; RNA, Small Interfering; Transfection

The emergence of multidrug resistance (MDR), meaning that cancer cells develop simultaneous resistance to different drugs, has limited the clinical efficacy and application of chemotherapy. Pterostilbene, a naturally occurring phytoalexin exerts a variety of pharmacologic activities, including cancer prevention, cytotoxicity, and antioxidant activity. In this study, results proved the capability of pterostilbene to effectively inhibit the cell viability of docetaxel-induced MDR human lung cancer cell lines through cell cycle arrest and apoptosis. Meanwhile, the observation of LC3-II production and formation of acidic vesicular organelles revealed an induction of autophagy at an early stage by pterostilbene, which was triggered by an inhibition of the AKT and JNK pathways and activation of ERK1/2. Furthermore, pretreatment with the autophagy inhibitors 3-methyladenine and bafilomycin A1 or with beclin-1 small interfering RNA was able to enhance pterostilbene-triggered apoptosis. In conclusion, this study demonstrated that pterostilbene causes autophagy and apoptosis in lung cancer cells. Furthermore, pterostilbene in combination with autophagy inhibitors may strengthen the efficiency of chemotherapeutic strategies in both chemosensitive and chemoresistant lung cancer cells, which may be of immense value for the clinical management of lung cancer patients with MDR.

Topics: Adenine; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Apoptosis Regulatory Proteins; Autophagy; Beclin-1; Cell Cycle Checkpoints; Cell Line, Tumor; Cell Survival; Docetaxel; Dose-Response Relationship, Drug; Drug Resistance, Neoplasm; Extracellular Signal-Regulated MAP Kinases; Humans; JNK Mitogen-Activated Protein Kinases; Lung Neoplasms; Macrolides; Membrane Proteins; Microtubule-Associated Proteins; Proto-Oncogene Proteins c-akt; RNA Interference; Signal Transduction; Stilbenes; Taxoids; Time Factors; Transfection

In this study, we investigated the anti-cancer effects of luteolin, a member of the flavonoid family, in NCI-H460 human lung carcinoma cells. It was shown that luteolin induces apoptotic cell death through modulating both the extrinsic pathway and intrinsic pathways, which are suppressed by z-VAD-fmk, indicating that luteolin triggers caspase-dependant apoptosis. Furthermore, we found that the α subunit of the eukaryotic initiation factor 2 (eIF2α/C/EBP homologous protein pathway, but not the c-Jun N-terminal kinase pathway, played a critical role in induction of apoptosis by luteolin. The data indicated that luteolin also induces autophagy; evidence for this is the accumulation of microtubule-associated protein light chain-3 (LC3) II protein, the increase of LC3 puncta as well as an enhanced autophagy flux. In addition, inhibiting autophagy by bafilomycin A1 reduced apoptotic cell death, suggesting that luteolin-induced autophagy functions as a cell death mechanism. Notably, the activated caspases that appeared with luteolin treatment cleaved Beclin-1, and the expression of LC3II remained the same even after cells were challenged with Beclin-1 siRNA, demonstrating that luteolin induces Beclin-1-independent autophagy. Taken together, our findings showed that luteolin triggers both endoplasmic reticulum stress-related apoptosis and non-canonical autophagy, which function as a cell death mechanism in NCI-H460 human lung cancer cells.

Topics: Amino Acid Chloromethyl Ketones; Antineoplastic Agents; Apoptosis; Apoptosis Regulatory Proteins; Autophagy; Beclin-1; CCAAT-Enhancer-Binding Proteins; Cell Line, Tumor; DNA Fragmentation; Endoplasmic Reticulum Stress; Eukaryotic Initiation Factor-2; Humans; JNK Mitogen-Activated Protein Kinases; Lung Neoplasms; Luteolin; Macrolides; Membrane Proteins; Microtubule-Associated Proteins; RNA, Small Interfering

Neuroendocrine (NE) phenotypes characterize a spectrum of lung tumors, including low-grade typical and intermediate-grade atypical carcinoid, high-grade large-cell NE carcinoma and small cell lung carcinoma. Currently, no effective treatments are available to cure NE lung tumors, demanding identification of biological features specific to these tumors. Here, we report that autophagy has an important role for NE lung tumor cell proliferation and survival. We found that the expression levels of the autophagy marker LC3 are relatively high in a panel of lung tumor cell lines expressing high levels of neuron-specific enolase (NSE), a key NE marker in lung tumors. In response to bafilomycin A1 and chloroquine, NE lung tumor cells exhibited cytotoxicity whereas non-NE lung tumor cells exhibited cytostasis, indicating a distinct role of autophagy for NE lung tumor cell survival. Intriguingly, in certain NE lung tumor cell lines, the levels of processed LC3 (LC3-II) were inversely correlated with AKT activity. When AKT activity was inhibited using AKTi or MK2206, the levels of LC3-II and SQSTM1/p62 were increased. In contrast, torin 1, rapamycin or mTOR knockdown increased p62 levels, suggesting that these two pathways have opposing effects on autophagy in certain NE lung tumors. Moreover, inhibition of one pathway resulted in reduced activity of the other, suggesting that these two pathways crosstalk in the tumors. These results suggest that NE lung tumor cells share a common feature of autophagy and are more sensitive to autophagy inhibition than non-NE lung tumor cells.

Topics: Adaptor Proteins, Signal Transducing; Antimalarials; Autophagy; Cell Line, Tumor; Cell Proliferation; Cell Survival; Chloroquine; Enzyme Inhibitors; Heterocyclic Compounds, 3-Ring; Humans; Lung Neoplasms; Macrolides; Microtubule-Associated Proteins; Naphthyridines; Neuroendocrine Tumors; Phosphopyruvate Hydratase; Phosphorylation; Poly(ADP-ribose) Polymerases; Proto-Oncogene Proteins c-akt; RNA Interference; RNA, Small Interfering; Sequestosome-1 Protein; Signal Transduction; Sirolimus; Small Cell Lung Carcinoma; TOR Serine-Threonine Kinases

The biochemical mechanisms of cell death by oleifolioside B (OB), a cycloartane-type triterpene glycoside isolated from Dendropanax morbifera Leveille, were investigated in A549 human lung carcinoma cells. Our data indicated that exposure to OB led to caspase activation and typical features of apoptosis; however, apoptotic cell death was not prevented by z-VAD-fmk, a pan-caspase inhibitor, demonstrating that OB-induced apoptosis was independent of caspase activation. Subsequently, we found that OB increased autophagy, as indicated by an increase in monodansylcadaverine fluorescent dye-labeled autophagosome formation and in the levels of the autophagic form of microtubule-associated protein 1 light chain 3 and Atg3, an autophagy-specific gene, which is associated with inhibiting phospho-nuclear factor erythroid 2-related factor 2 (Nrf2) expression. However, pretreatment with bafilomycin A1, an autophagy inhibitor, attenuated OB-induced apoptosis and dephosphorylation of Nrf2. The data suggest that OB-induced autophagy functions as a death mechanism in A549 cells and OB has potential as a novel anticancer agent capable of targeting apoptotic and autophagic cell death and the Nrf2 signaling pathway.

Topics: Amino Acid Chloromethyl Ketones; Antineoplastic Agents; Apoptosis; Autophagy; Autophagy-Related Proteins; Carcinoma, Non-Small-Cell Lung; CASP8 and FADD-Like Apoptosis Regulating Protein; Caspase 3; Caspase 8; Caspase 9; Caspase Inhibitors; Cell Line, Tumor; Enzyme Inhibitors; Humans; Inhibitor of Apoptosis Proteins; Lung Neoplasms; Macrolides; Microtubule-Associated Proteins; NF-E2-Related Factor 2; Plant Extracts; Proto-Oncogene Proteins c-bcl-2; Saponins; Survivin; Ubiquitin-Conjugating Enzymes

Cellular senescence contributes to aging and decline in tissue function. p53 isoform switching regulates replicative senescence in cultured fibroblasts and is associated with tumor progression. Here, we found that the endogenous p53 isoforms Δ133p53 and p53β are physiological regulators of proliferation and senescence in human T lymphocytes in vivo. Peripheral blood CD8+ T lymphocytes collected from healthy donors displayed an age-dependent accumulation of senescent cells (CD28-CD57+) with decreased Δ133p53 and increased p53β expression. Human lung tumor-associated CD8+ T lymphocytes also harbored senescent cells. Cultured CD8+ blood T lymphocytes underwent replicative senescence that was associated with loss of CD28 and Δ133p53 protein. In poorly proliferative, Δ133p53-low CD8+CD28- cells, reconstituted expression of either Δ133p53 or CD28 upregulated endogenous expression of each other, which restored cell proliferation, extended replicative lifespan and rescued senescence phenotypes. Conversely, Δ133p53 knockdown or p53β overexpression in CD8+CD28+ cells inhibited cell proliferation and induced senescence. This study establishes a role for Δ133p53 and p53β in regulation of cellular proliferation and senescence in vivo. Furthermore, Δ133p53-induced restoration of cellular replicative potential may lead to a new therapeutic paradigm for treating immunosenescence disorders, including those associated with aging, cancer, autoimmune diseases, and HIV infection.

Topics: Adult; Aged; Autophagy; CD8-Positive T-Lymphocytes; Cell Division; Cells, Cultured; Cellular Senescence; Female; Gene Expression Regulation, Neoplastic; Humans; Leupeptins; Lung Neoplasms; Lymphocytes, Tumor-Infiltrating; Macrolides; Male; Middle Aged; Neoplasm Proteins; Protein Isoforms; Proteolysis; Recombinant Proteins; Transduction, Genetic; Tumor Microenvironment; Tumor Suppressor Protein p53; Young Adult

Recently, we identified an ADP-ribosylating and vacuolating cytotoxin in Mycoplasma pneumoniae designated Community Acquired Respiratory Distress Syndrome (CARDS) toxin. In this study we show that vacuoles induced by recombinant CARDS (rCARDS) toxin are acidic and derive from the endocytic pathway as determined by the uptake of neutral red and the fluid-phase marker, Lucifer yellow, respectively. Also, we demonstrate that the formation of rCARDS toxin-associated cytoplasmic vacuoles is inhibited by the vacuolar ATPase inhibitor, bafilomycin A1, and the ionophore, monensin. To examine the ontogeny of these vacuoles, we analyzed the distribution of endosomal and lysosomal membrane markers during vacuole formation and observed the enrichment of the late endosomal GTPase, Rab9, around rCARDS toxin-induced vacuoles. Immunogold-labeled Rab9 and overexpression of green fluorescent-tagged Rab9 further confirmed vacuolar association. The late endosomal- and lysosomal-associated membrane proteins, LAMP1 and LAMP2, also localized to the vacuolar membranes, while the late endosomal protein, Rab7, and early endosomal markers, Rab5 and EEA1, were excluded. HeLa cells expressing dominant-negative (DN) Rab9 exhibited markedly reduced vacuole formation in the presence of rCARDS toxin, in contrast to cells expressing DN-Rab7, highlighting the importance of Rab9 function in rCARDS toxin-induced vacuolation. Our findings reveal the unique Rab9-association with rCARDS toxin-induced vacuoles and its possible relationship to the characteristic histopathology that accompanies M. pneumoniae infection.

Topics: Animals; Antifungal Agents; Bacterial Proteins; Bacterial Toxins; Biomarkers; Cells, Cultured; Chlorocebus aethiops; Cytoplasm; Endosomes; Genes, Dominant; HeLa Cells; Humans; Lung Neoplasms; Lysosomes; Macrolides; Microscopy, Immunoelectron; rab GTP-Binding Proteins; Recombinant Proteins; Vacuolar Proton-Translocating ATPases; Vacuoles; Vero Cells

The anti-apoptotic oncoproteins Bcl-2 and Bcl-xL play crucial roles in tumorigenesis and chemoresistance, and are thus therapeutic cancer targets. We searched for small molecules that disturbed the anti-apoptotic function of Bcl-2 or Bcl-xL, and found vacuolar H(+)-ATPase (V-ATPase) inhibitors, such as bafilomycin A1 (BMA), that showed such activity. Bcl-xL-overexpressing Ms-1 cells displayed resistance to anticancer drugs, but underwent apoptosis following treatment with a combination of V-ATPase inhibitors at doses similar to those that caused inhibitory activities of V-ATPase. We investigated the apoptosis mechanism induced by cotreatment of Bcl-xL-overexpressing Ms-1 cells with BMA as a V-ATPase inhibitor and taxol (TXL) as an anticancer drug. With BMA, TXL triggered mitochondrial membrane potential loss and cytochrome c release, whereas downstream caspase activation was not observed. In contrast, pronounced nuclear translocation of mitochondrial apoptosis-inducing factor and endonuclease G, known as effectors of caspase-independent apoptosis, was observed with BMA and TXL cotreatment. Moreover, depletion of apoptosis-inducing factor and endonuclease G using each siRNA significantly rescued cells from BMA- and TXL-induced apoptosis. Hence, the apoptosis-inducing factor- and endonuclease G-dependent pathway was critical for apoptosis induction by BMA and TXL cotreatment. Our data suggest that V-ATPase inhibitors could not only suppress anti-apoptotic Bcl-2 nor Bcl-xL but could also facilitate the caspase-independent apoptotic pathway. V-ATPase inhibition will be a promising therapeutic approach for Bcl-2- or Bcl-xL-overexpressing malignancies.

Topics: Antineoplastic Agents, Phytogenic; Apoptosis; Apoptosis Inducing Factor; bcl-X Protein; Caspases; Cell Line, Tumor; Cytochrome c Group; Drug Combinations; Drug Resistance, Neoplasm; Endodeoxyribonucleases; Enzyme Inhibitors; Humans; Lung Neoplasms; Macrolides; Membrane Potential, Mitochondrial; Paclitaxel; Small Cell Lung Carcinoma; Vacuolar Proton-Translocating ATPases

U1-snRNA is an integral part of the U1 ribonucleoprotein pivotal for pre-mRNA splicing. Toll-like receptor (TLR) signaling has recently been associated with immunoregulatory capacities of U1-snRNA. Using lung A549 epithelial/carcinoma cells, we report for the first time on interferon regulatory factor (IRF)-3 activation initiated by endosomally delivered U1-snRNA. This was associated with expression of the IRF3-inducible genes interferon-beta (IFN-beta), CXCL10/IP-10 and indoleamine 2,3-dioxygenase. Mutational analysis of the U1-snRNA-activated IFN-beta promoter confirmed the crucial role of the PRDIII element, previously proven pivotal for promoter activation by IRF3. Notably, expression of these parameters was suppressed by bafilomycin A(1), an inhibitor of endosomal acidification, implicating endosomal TLR activation. Since resiquimod, an agonist of TLR7/8, failed to stimulate A549 cells, data suggest TLR3 to be of prime relevance for cellular activation. To assess the overall regulatory potential of U1-snRNA-activated epithelial cells on cytokine production, co-cultivation with peripheral blood mononuclear cells (PBMC) was performed. Interestingly, A549 cells activated by U1-snRNA reinforced phytohemagglutinin-induced interleukin-10 release by PBMC but suppressed that of tumor necrosis factor-alpha, indicating an anti-inflammatory potential of U1-snRNA. Since U1-snRNA is enriched in apoptotic bodies and epithelial cells are capable of performing efferocytosis, the present data in particular connect to immunobiological aspects of apoptosis at host/environment interfaces.

Topics: Cell Line, Tumor; Chemokine CXCL10; Coculture Techniques; Epithelial Cells; Gene Expression; Humans; Immunity, Innate; Indoleamine-Pyrrole 2,3,-Dioxygenase; Interferon Regulatory Factor-3; Interferon-beta; Lung Neoplasms; Macrolides; Promoter Regions, Genetic; RNA, Small Nuclear; Signal Transduction; STAT Transcription Factors; Toll-Like Receptor 3; Transfection

Neodymium, a rare earth element, was known to exhibit cytotoxic effects and induce apoptosis in certain cancer cells. Here we show that nano-sized neodymium oxide (Nano Nd2O3) induced massive vacuolization and cell death in non-small cell lung cancer NCI-H460 cells at micromolar equivalent concentration range. Cell death elicited by Nano Nd2O3 was not due to apoptosis and caspases were not involved. Electron microscopy and acridine orange staining revealed extensive autophagy in the cytoplasm of the cells treated by Nano Nd2O3. Autophagy induced by Nano Nd2O3 was accompanied by S-phase cell cycle arrest, mild disruption of mitochondrial membrane potential, and inhibition of proteasome activity. Bafilomycin A1, but not 3-MA, induced apoptosis while inhibiting autophagy. Our results revealed a novel biological function for Nano Nd2O3 and may have implications for the therapy of non-small cell lung cancer.

Topics: Antineoplastic Agents; Autophagy; Carcinoma, Non-Small-Cell Lung; Cell Line, Tumor; Humans; Lung Neoplasms; Macrolides; Membrane Potentials; Mitochondria; Neodymium; Oxides; Proteasome Endopeptidase Complex; S Phase; Vacuoles