Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0242379 (lung cancer)
 71,905 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We demonstrated previously that nonsteroidal anti-inflammatory drugs (NSAIDs) increased p27(Kip1) by inhibiting protein degradation to suppress the proliferation of human lung cancer cells. In this study, we elucidate the molecular mechanism by which NSAIDs modulate p27(Kip1) proteolysis. Immunoblotting and in vitro ubiquitination assays indicated that the expression of Cul1 and Skp2 and ubiquitination activity toward p27(Kip1) were not regulated by NSAIDs. On the contrary, we found that NSAIDs inhibited proteasome activity to increase p27(Kip1) protein levels. NSAIDs suppressed the expression of chymotrypsin-like catalytic subunits (beta5, LMP7, and LMP2), but did not directly block enzymatic activity, to inhibit proteasome activity. Reverse transcriptase-competitive polymerase chain reaction and promoter activity assays showed that this inhibition occurred at the transcriptional level. In vitro degradation experiments showed that p27(Kip1) degradation was inhibited by NS398, and the addition of purified 26S proteasome reversed this inhibitory effect. Collectively, our results revealed the mechanism by which NSAIDs modulate p27(Kip1) protein degradation and suggest that NSAIDs are a novel class of proteasome inhibitors.
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PMID:Mechanisms underlying nonsteroidal anti-inflammatory drug-induced p27(Kip1) expression. 1243 20

Sustained extracellular signal-regulated kinase 1/2 (ERK1/2) activation does not always correlate with its upstream Ras-Raf-mitogen-activated protein kinase kinase 1/2 (MKK1/2) signal cascade in cancer cells, and the mechanism remains elusive. Here we report a novel mechanism by which sustained ERK1/2 activation is established. We demonstrate that Pb(II), a carcinogenic metal, persistently induces ERK1/2 activity in CL3 human lung cancer cells and that Ras-Raf-MKK1/2 signaling cannot fully account for such activation. It is intriguing that Pb(II) treatment reduces mitogen-activated protein kinase phosphatase 1 (MKP-1) protein levels in time- and dose-dependent manners, which correlates with sustained ERK1/2 activation, and that Pb(II) also induces mRNA and de novo protein synthesis of MKP-1. In Pb(II)-treated cells, MKP-1 is polyubiquitinated, and proteasome inhibitors markedly alleviate the ubiquitination and degradation of MKP-1. Inhibiting the Pb(II)-induced ERK1/2 activation by PD98059 greatly suppresses MKP-1 ubiquitination and degradation. It is remarkable that constitutive activation of MKK1/2 triggers endogenous MKP-1 ubiquitination and degradation in various mammalian cell lines. Furthermore, expression of functional MKP-1 decreases ERK1/2 activation and the c-Fos protein level and enhances cytotoxicity under Pb(II) exposure. Taken together, these results demonstrate that activated ERK1/2 can trigger MKP-1 degradation via the ubiquitin-proteasome pathway, thus facilitating long-term activation of ERK1/2 against cytotoxicity.
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PMID:ERK1/2 achieves sustained activation by stimulating MAPK phosphatase-1 degradation via the ubiquitin-proteasome pathway. 1267 37

Bortezomib, a proteasome inhibitor, shows substantial anti-tumor activity in a variety of tumor cell lines, is in phase I, II, and III clinical trials and has recently been approved for the treatment of patients with multiple myeloma. The sequence of events leading to apoptosis following proteasome inhibition by bortezomib is unclear. Bortezomib effects on components of the mitochondrial apoptotic pathway were examined: generation of reactive oxygen species (ROS), alteration in the mitochondrial membrane potential (Delta psi m), and release of cytochrome c from mitochondria. With human H460 lung cancer cells, bortezomib exposure at 0.1 microM showed induction of apoptotic cell death starting at 24 h, with increasing effects after 48-72 h of treatment. After 3-6 h, an elevation in ROS generation, an increase in Delta psi m, and the release of cytochrome c into the cytosol, were observed in a time-dependent manner. Co-incubation with rotenone and antimycin A, inhibitors of mitochondrial electron transport chain complexes I and III, or with cyclosporine A, an inhibitor of mitochondrial permeability transition pore, resulted in inhibition of bortezomib-induced ROS generation, increase in Delta psi m, and cytochrome c release. Tiron, an antioxidant agent, blocked the bortezomib-induced ROS production, Delta psi m increase, and cytochrome c release. Tiron treatment also protected against the bortezomib-induced PARP protein cleavage and cell death. Benzyloxycarbonyl-VAD-fluoromethyl ketone, an inhibitor of pan-caspase, did not alter the bortezomib-induced ROS generation and increase in Delta psi m, although it prevented bortezomib-induced poly(ADP-ribose) polymerase cleavage and apoptotic death. In PC-3 prostate carcinoma cells (with overexpression of Bcl-2), a reduction of bortezomib-induced ROS generation, Delta psi m increase was correlated with cellular resistance to bortezomib and the attenuation of drug-induced apoptosis. The transient transfection of wild type p53 in p53 null H358 cells caused stimulation of the bortezomib-induced apoptosis but failed to enhance ROS generation and Delta psi m increase. Thus ROS generation plays a critical role in the initiation of the bortezomib-induced apoptotic cascade by mediation of the disruption of Delta psi m and the release of cytochrome c from mitochondria.
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PMID:Reactive oxygen species generation and mitochondrial dysfunction in the apoptotic response to Bortezomib, a novel proteasome inhibitor, in human H460 non-small cell lung cancer cells. 1282 77

PS-341, a potent and selective proteasome inhibitor, is the prototype for a new class of therapeutics that targets the ubiquitin-proteasome pathway. It is active as a single agent and potentiates chemotherapy and radiation in pre-clinical models. Early phase clinical studies have demonstrated tolerability and activity in multiple myeloma, lymphoma, prostate cancer and lung cancer. By its mechanism of inhibiting protein degradation, PS-341 targets a wide-range of pathways that are relevant to tumor progression and therapy resistance, and can directly modulate expression of cyclins, p27(Kip1), p53, NF-kappaB, Bcl-2 and Bax. PS-341 is currently in phase I/II clinical development in lung cancer. This paper will review the pre-clinical and clinical experience with PS-341 as it relates to lung cancer.
Lung Cancer 2003 Aug
PMID:Integration of the proteasome inhibitor PS-341 (Velcade) into the therapeutic approach to lung cancer. 1286 67

Lung cancer is the leading cause of cancer mortality. Chemoprevention is an attractive strategy to combat this major public health problem. Pre-clinical and clinical studies have identified diverse candidate chemopreventive agents that affect cellular proliferation, differentiation, apoptosis and tumor angiogenesis, among other pathways. These pharmacological agents are undergoing testing through use of pre-clinical models and clinical trials. These studies have uncovered cyclin D1 as a chemoprevention target and a surrogate marker of chemopreventive response in the lung. Chemoprevention of tobacco-carcinogen transformed human bronchial epithelial (HBE) cells appears to be due at least partly to degradation of cyclin D1. These studies of cultured HBE cells were extended to the in vivo setting by examination of preneoplastic bronchial lesions that established the frequent aberrant expression of cyclin D1 in lung carcinogenesis. Certain retinoids, natural and synthetic derivatives of vitamin A, repress cyclin D1, but activation of the epidermal growth factor receptor (EGFR) induces cyclin D1. Retinoids and specific chemopreventive agents can activate the proteasome-dependent degradation of cyclin D1 and also repress EGFR expression, thereby reducing cyclin D1 levels. These actions oppose the mitogenic effects of cyclin D1. This is hypothesized to trigger G1 arrest and thereby permit repair of carcinogenic damage of genomic DNA. These and other pre-clinical and clinical studies that will be reviewed here indicate that cyclin D1 and perhaps other cyclins are attractive pharmacological targets for lung cancer chemoprevention.
Lung Cancer 2003 Aug
PMID:Cyclin D1 as a target for chemoprevention. 1286 74

PS-341 (bortezomib) represents a new class of therapeutics that targets the ubiquitin-proteasome pathway. It has broad-spectrum single-agent anticancer activity and can potentiate chemotherapy and radiation in preclinical models. Early phase clinical studies have shown tolerability and activity in multiple myeloma, lymphoma, prostate cancer, and lung cancers. By its mechanism of inhibiting protein degradation, PS-341 targets a wide range of pathways relevant to tumor progression and therapy resistance and can directly modulate expression of cyclins, p27(Kip1), p53, nuclear factor-kappaB, Bcl-2, and Bax. PS-341 is currently in phase I/II clinical development in both non-small cell lung cancer and small cell lung cancer. This article will review the preclinical and clinical experience with PS-341 as it relates to lung cancer.
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PMID:Proteasome inhibition with PS-341 (bortezomib) in lung cancer therapy. 1498 79

There is accumulating evidence that peptides derived from the catalytic subunit of human telomerase reverse transcriptase (hTERT) are specifically recognized by CD8+ cytotoxic T lymphocytes. We investigated the cytotoxicity of a human leukocyte antigen (HLA)-A*2402-restricted hTERT-derived peptide 461-469 (hTERT461)-specific CD8+ T-cell clone, designated as K3-1, established from a healthy donor by repetitive peptide stimulation. This clone exhibited cytotoxicity against 4 out of 6 HLA-A24-positive lung cancer cell lines with positive telomerase activity but not 4 HLA-A24-negative examples. When the target cells were pretreated with 100 U/ml of interferon (IFN)-gamma for 48 hr, the susceptibility to K3-1 increased with PC9 cells but unexpectedly decreased with LU99 cells. However, in both cell lines, the expression of molecules associated with epitope presentation such as HLA-A24, transporters associated with antigen processing, low molecular weight polypeptide 7 and proteasome activator 28 was similarly increased after IFN-gamma treatment. Results of CTL assays using acid-extracted peptides indicated that the epitope increased on PC9 cells but not on LU99 cells after IFN-gamma treatment. Semi-quantitative reverse transcriptase polymerase chain reaction disclosed that the expression of hTERT was attenuated in LU99 but not in PC9 cells, accounting for the decreased cytotoxicity mediated by K3-1. The attenuation of the hTERT expression and K3-1-mediated cell lysis after IFN-gamma treatment was also observed in primary adenocarcinoma cells obtained from pulmonary fluid of a lung cancer patient. Our data underline the utility of peptide hTERT461 in immunotherapy for lung cancer, as with other malignancies reported earlier, and suggest that modulation of hTERT expression by IFN-gamma needs to be taken into account in therapeutic approach.
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PMID:Interferon-gamma differentially regulates susceptibility of lung cancer cells to telomerase-specific cytotoxic T lymphocytes. 1509 6

Rhobtb2 is a candidate tumor suppressor located on human chromosome 8p21, a region commonly deleted in cancer. Rhobtb2 is homozygously deleted in 3.5% of primary breast cancers, and gene expression is ablated in approximately 50% of breast and lung cancer cell lines. RhoBTB2 is an 83-kD, atypical Rho GTPase of unknown function, comprising an N-terminal Rho GTPase domain and two tandem BTB domains. In this report, we demonstrate that RhoBTB2 binds to the ubiquitin ligase scaffold, Cul3, via its first BTB domain and show in vitro and in vivo that RhoBTB2 is a substrate for a Cul3-based ubiquitin ligase complex. Moreover, we show that a RhoBTB2 missense mutant identified in a lung cancer cell line is neither able to bind Cul3 nor is it regulated by the ubiquitin/proteasome system, resulting in increased RhoBTB2 protein levels in vivo. We suggest a model in which RhoBTB2 functions as a tumor suppressor by recruiting proteins to a Cul3 ubiquitin ligase complex for degradation.
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PMID:RhoBTB2 is a substrate of the mammalian Cul3 ubiquitin ligase complex. 1510 2

FUS1 is a novel tumor suppressor gene identified in the human chromosome 3p21.3 region that is deleted in many cancers. Using surface-enhanced laser desorption/ionization mass spectrometric analysis on an anti-Fus1-antibody-capture ProteinChip array, we identified wild-type Fus1 as an N-myristoylated protein. N-myristoylation is a protein modification process in which a 14-carbon myristoyl group is cotranslationally and covalently added to the NH2-terminal glycine residue of the nascent polypeptide. Loss of expression or a defect of myristoylation of the Fus1 protein was observed in human primary lung cancer and cancer cell lines. A myristoylation-deficient mutant of the Fus1 protein abrogated its ability to inhibit tumor cell-induced clonogenicity in vitro, to induce apoptosis in lung tumor cells, and to suppress the growth of tumor xenografts and lung metastases in vivo and rendered it susceptible to rapid proteasome-dependent degradation. Our results show that myristoylation is required for Fus1-mediated tumor-suppressing activity and suggest a novel mechanism for the inactivation of tumor suppressors in lung cancer and a role for deficient posttranslational modification in tumor suppressor-gene-mediated carcinogenesis.
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PMID:Myristoylation of the fus1 protein is required for tumor suppression in human lung cancer cells. 1512 27

Bortezomib (PS-341, Velcade, Millennium Pharmaceuticals, Cambridge, MA) is a novel inhibitor of the proteasome. The proteasome plays a critical role in the degradation and, therefore, regulation of many proteins involved in cell cycle regulation, apoptosis, and angiogenesis. Bortezomib inhibits the growth of lung cancer cell lines in vitro and in vivo in athymic nude mouse xenografts. Bortezomib produces a G(2)-M arrest, increases in cyclin A and cyclin B, increases in p21, and increases apoptosis in these preclinical models. Phase I studies established that a dose of 1.4 mg/m(2) given i.v. on days 1, 4, 8, and 11 of a 3-week cycle produced acceptable toxicity and serum levels that resulted in proteasome inhibition. Phase II studies showed high-response rates in refractory multiple myeloma. These response rates were sufficiently high to allow accelerated approval of bortezomib by the Food and Drug Administration for this indication. Phase II trials in both non-small cell lung cancer and small cell lung cancer are in progress. A number of Phase I combination studies are also underway. Hopefully, bortezomib will show sufficient activity in lung cancer to improve survival in this dread disease.
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PMID:The potential role of proteasome inhibitors in the treatment of lung cancer. 1521 71


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