thromboxane-a2 and Lung-Neoplasms

Patients with rheumatoid arthritis (RA) appear to be at a higher risk of lung cancer (LC). Although the connection between RA and LC has been an active area of research for many years, the molecular pathogenesis of the disease process remains unclear. The cyclooxygenase (COX)-2/thromboxane A2 (TxA2) pathway has been shown to play a potential role in LC development through an auto-regulatory feedback loop. An increased level of TxA2 has been found in RA patients, and intriguingly, the positive feedback loop for the COX-2/TxA2 pathway was shown to have a potential function in RA fibroblast-like synoviocytes (RA-FLS). Thus, the molecular basis of LC development in patients with RA has been at least in partly described. It is possible that COX-2-derived TxA2 could be monitored for the early detection of LC in RA patients, and targeting this molecular pathway may decrease the risk of LC in patients with RA.

Topics: Arthritis, Rheumatoid; Cyclooxygenase 2; Fibroblasts; Gene Expression Profiling; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Neoplastic; Humans; Inflammation; Lung Neoplasms; Synovial Fluid; Thromboxane A2

Clinical evidence recently suggests that the regular use of aspirin is associated with a lower risk of breast cancer metastasis, but mechanisms remain unclear. Resistance to anoikis has been implicated in malignant transformation and metastasis. Here, we investigated whether aspirin might prevent breast cancer metastasis to lung by targeting anoikis resistance. Aspirin sensitized breast cancer cells to anoikis in vitro and lowered the circulating tumor cells as well as distant metastasis in vivo. Mechanistically, thromboxane A2 (TXA2) pathway was identified as the relevant molecular target for aspirin in anoikis sensitization. Upon detachment, both thromboxane A2 receptor (TP) and thromboxane A2 synthase 1 (TBXAS1) were up-regulated in metastatic breast cancer cells, conferred anoikis resistance through persistent activation of Akt, thereby facilitated breast cancer metastasis to lung. Consistently, either knockdown of TP in cancer cells or genetic deletion of TP in mice protected against lung metastasis in vivo. Collectively, TXA2 pathway plays a critical role in anoikis resistance and might serve as potential target for chemoprevention of breast cancer metastasis.

Topics: Animals; Anoikis; Aspirin; Breast Neoplasms; Cell Line, Tumor; Female; Humans; Lung; Lung Neoplasms; Mice; Neoplasm Metastasis; Neoplasms, Second Primary; Signal Transduction; Thromboxane A2

Because metastasis is associated with the majority of cancer-related deaths, its prevention is a clinical aspiration. Prostanoids are a large family of bioactive lipids derived from the activity of cyclooxygenase-1 (COX-1) and COX-2. Aspirin impairs the biosynthesis of all prostanoids through the irreversible inhibition of both COX isoforms. Long-term administration of aspirin leads to reduced distant metastases in murine models and clinical trials, but the COX isoform, downstream prostanoid, and cell compartment responsible for this effect are yet to be determined. Here, we have shown that aspirin dramatically reduced lung metastasis through inhibition of COX-1 while the cancer cells remained intravascular and that inhibition of platelet COX-1 alone was sufficient to impair metastasis. Thromboxane A2 (TXA2) was the prostanoid product of COX-1 responsible for this antimetastatic effect. Inhibition of the COX-1/TXA2 pathway in platelets decreased aggregation of platelets on tumor cells, endothelial activation, tumor cell adhesion to the endothelium, and recruitment of metastasis-promoting monocytes/macrophages, and diminished the formation of a premetastatic niche. Thus, platelet-derived TXA2 orchestrates the generation of a favorable intravascular metastatic niche that promotes tumor cell seeding and identifies COX-1/TXA2 signaling as a target for the prevention of metastasis.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Aspirin; Blood Platelets; Cell Line, Tumor; Cyclooxygenase Inhibitors; Female; Humans; Lung Neoplasms; Macrophages; Melanoma, Experimental; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Monocytes; Neoplasm Metastasis; Neoplasm Transplantation; Platelet Aggregation; Platelet Aggregation Inhibitors; Prostaglandins; Protein Isoforms; Thrombosis; Thromboxane A2

Lung cancer concerns a worldwide health problem and the efficacy of available treatments is unsatisfactory. Recently, thromboxane A2 (TXA2) synthase (TXAS) and receptor (TXA2R) have been documented to play a role in lung cancer development. Therefore, dual TXA2R modulator (i.e., the dual blocker of TXAS and TXA2R) may be more efficacious to kill lung tumor cells than single TXAS inhibitor or TXA2R antagonism. The close relationship between cyclooxygenase (COX)-2 and TXAS also raises whether or how TXA2 contributes to the oncogenic activity of COX-2. This study is therefore conducted to answer these questions.. Various inhibitors and siRNA were used to evaluate the roles of TXA2 and COX-2 in the proliferation and apoptosis of lung adenocarcinoma cells. Cell proliferation was detected using both MTS ELISA and BrdU labeling ELISA. Cell cycle distribution and apoptosis were examined by flow cytometric analysis. TXB2 level, reflecting the biosynthesis of TXA2, was detected by peroxidase-labeled TXB2 conjugates using an enzyme immunoassay kit. Western blotting was performed to evaluate many biomarkers for cell cycles, apoptosis and proliferation. The levels of COXs were screened by reverse transcriptase and real-time quantitative PCR.. We found either single TXAS inhibitor/TXA2R antagonist or the dual TXA2 modulators offered a similar inhibition on cell proliferation. Moreover, inhibition of TXA2 arrested cells at the G2/M phase and induced apoptosis. It is further demonstrated that TXA2 was able to function as a critical mediator for tumor-promoting effects of COX-2 in lung adenocarcinoma cells.. The present study has for the first shown that dual TXA2 modulators and the single blocker of TXAS or TXA2R offer a similar inhibitory role in lung adenocarcinoma cell proliferation and that the tumor-promoting effects of COX-2 can largely be relayed by TXA2. Thus, TXA2 should be regarded as a critical molecule in COX-2-mediated tumor growth and a valuable target against lung cancer.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Adenocarcinoma; Adenocarcinoma of Lung; Antineoplastic Agents; Apoptosis; Benzofurans; Blotting, Western; Bridged Bicyclo Compounds, Heterocyclic; Cell Cycle; Cell Line, Tumor; Cell Proliferation; Cyclooxygenase 2; Cyclooxygenase Inhibitors; Enzyme Inhibitors; Enzyme-Linked Immunosorbent Assay; Fatty Acids, Unsaturated; Flow Cytometry; Humans; Hydrazines; Immunoenzyme Techniques; Lung Neoplasms; Nitrobenzenes; Real-Time Polymerase Chain Reaction; Receptors, Thromboxane; Reverse Transcriptase Polymerase Chain Reaction; Signal Transduction; Sulfonamides; Sulfonylurea Compounds; Thromboxane A2; Thromboxane-A Synthase

Tobacco smoking can cause a number of cancers. The role of thromboxane synthase (TxAS) in smoking-related cancers is largely unknown. In this study, 37 pairs of tumor and non-tumor lung tissues of non-small-cell lung cancer, 5 lung cancer cell lines, and a mouse tumor model were used to study TxAS and its related molecules. A mouse model of smoking carcinogen 4-methylnitrosamino-1-3-pyridyl-1-butanone (NNK)-induced lung tumor showed an increase in TxAS. Thromboxane A2 receptor (TP) was aberrant in lung cancer tissues of smokers. TxAS and TP were increased in lung tissues of NNK-treated mice. The in vitro studies showed that TPα rather than TPβ promoted tumor growth, and NNK increased TPα. NNK-induced TxAS, which depended on activation of cyclooxygenase-2 (COX-2), ERK and NF-κB, could be inhibited by miR-34b/c. TPα played a positive role in NNK-induced COX-2/ERK/NF-κB activation, leading to the upregulation of TxAS expression and thromboxane A2 (TxA2) synthesis. The newly synthesized TxA2 could further activate TPα, forming an autoregulatory feedback loop for TPα activation. Collectively, NNK promotes lung tumor growth via inducing TxAS and TPα, which constitutes an auto-positive feedback loop to exaggerate the growth. This study suggests that TPα and TxAS are the ideal targets against smoking-related lung cancer.

Topics: Animals; Blotting, Western; Cell Line, Tumor; Cyclooxygenase 2; Humans; In Vitro Techniques; Lung; Lung Neoplasms; Mice; Real-Time Polymerase Chain Reaction; Receptors, Thromboxane A2, Prostaglandin H2; Thromboxane A2; Thromboxane-A Synthase

Thromboxane synthase (TXAS) and thromboxane A(2) receptor (TP), two critical components for thromboxane A(2) (TXA(2)) signaling, have been suggested to be involved in cancer invasion and metastasis. However, the mechanisms by which TXA(2) promotes these processes are still unclear. Here we show that TXA(2) mimetic, I-BOP, induced monocyte chemoattractant protein -1(MCP-1)/chemokine (C-C motif) ligand 2 (CCL2) expression at both mRNA and protein levels in human lung adenocarcinoma A549 cells stably over-expressing TP receptor α isoform (A549-TPα). The induction of MCP-1 was also found in other lung cancer cells H157 and H460 that express relatively high levels of endogenous TP. Using specific inhibitors of several signaling molecules and promoter/luciferase assay, we identified that transcription factor SP1 mediates I-BOP-induced MCP-1 expression. Furthermore, supernatants from I-BOP-treated A549-TPα cells enhanced MCP-1-dependent migration of RAW 264.7 macrophages. Moreover, co-culture of A549 cells with RAW 264.7 macrophages induced expression of MMPs, VEGF and MCP-1 genes, and increased the invasive potential in A549 cells. These findings suggest that TXA(2) may stimulate invasion of cancer cells through MCP-1-mediated macrophage recruitment.

Topics: Animals; Blotting, Western; Bridged Bicyclo Compounds, Heterocyclic; Cell Line; Cell Line, Tumor; Cell Movement; Chemokine CCL2; Coculture Techniques; Fatty Acids, Unsaturated; Gene Expression; Humans; Lung Neoplasms; Macrophages; Matrix Metalloproteinases; Microscopy, Fluorescence; Neoplasm Invasiveness; Receptors, Thromboxane A2, Prostaglandin H2; Reverse Transcriptase Polymerase Chain Reaction; Sp1 Transcription Factor; Thromboxane A2; Vascular Endothelial Growth Factor A

Thromboxane A(2) receptor (TP) has been shown to play an important role in multiple aspects of cancer development including regulation of tumor growth, survival and metastasis. Here we report that TP mediates cancer cell invasion by inducing expression of matrix metalloproteinases (MMPs). TP agonist, I-BOP, significantly elevated MMP-1, MMP-3, MMP-9 and MMP-10 mRNA levels in A549 human lung adenocarcinoma cells overexpressing TPα or TPβ. The secretion of MMP-1 and MMP-9 in conditioned media was determined using Western blot analysis and zymographic assay. Signaling pathways of I-BOP-induced MMP-1 expression were examined in further detail as a model system for MMPs induction. Signaling molecules involved in I-BOP-induced MMP-1 expression were identified by using specific inhibitors including small interfering (si)-RNAs of signaling molecules and promoter reporter assay. The results indicate that I-BOP-induced MMP-1 expression is mediated by protein kinase C (PKC), extracellular signal-regulated kinase (ERK)-activator protein-1(AP-1) and ERK-CCAAT/enhancer-binding protein β (C/EBPβ) pathways. I-BOP-induced cellular invasiveness of A549 cells expressing TPα or TPβ was determined by invasion assay. GM6001, a general inhibitor of MMPs, decreased basal and I-BOP-induced cell invasion. Knockdown of MMP-1 and MMP-9 by their respective siRNA partially reduced I-BOP-stimulated cell invasion suggesting that other MMPs induced by I-BOP were also involved. Our studies establish the relationship between TP and MMPs in cancer cell invasion and suggest that the thromboxane A(2) (TXA(2))-TP signaling is a potential therapeutic target for cancer invasion and metastasis.

Topics: Adenocarcinoma; Adenocarcinoma of Lung; Bridged Bicyclo Compounds, Heterocyclic; CCAAT-Enhancer-Binding Protein-beta; Cell Line, Tumor; Cell Movement; Dipeptides; Dose-Response Relationship, Drug; Extracellular Signal-Regulated MAP Kinases; Fatty Acids, Unsaturated; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Neoplastic; Humans; Lung Neoplasms; Matrix Metalloproteinase 1; Matrix Metalloproteinase 10; Matrix Metalloproteinase 3; Matrix Metalloproteinase 9; Matrix Metalloproteinase Inhibitors; Matrix Metalloproteinases; Neoplasm Invasiveness; Protease Inhibitors; Protein Kinase C; Receptors, Thromboxane A2, Prostaglandin H2; RNA Interference; RNA, Messenger; Signal Transduction; Thromboxane A2; Time Factors; Transcription Factor AP-1; Transfection; Up-Regulation

The role of thromboxane A(2) (TxA(2)) in smoking-associated lung cancer is poorly understood. This study was conducted to study the role of TxA(2) in smoking carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-promoted cell survival and growth in human lung cancer cells. We found that NNK increased TxA(2) synthase (TxAS) expression and thromboxane B(2) (TxB(2)) generation in cultured lung cancer cells, the result of which was supported by the increased level of TxAS in lung cancer tissues of smokers. Both TxAS-specific inhibitor furegrelate and TxA(2) receptor antagonist SQ29548 completely blocked NNK-mediated cell survival and growth via inducting apoptosis. TxA(2) receptor agonist U46619 reconstituted a near-full survival and growth response to NNK when TxAS was inhibited, affirming the role of TxA(2) receptor in NNK-mediated cell survival and growth. Suppression of cyclic adenosine monophosphate response element binding protein (CREB) activity by its small interference RNA blocked the effect of NNK. Phosphatidylinositol 3-kinase (PI3K)/Akt and extracellular signal-regulated kinase (ERK) also had a positive role. Altogether, our results have revealed that NNK stimulates TxA(2) synthesis and activates its receptor in lung cancer cells. The increased TxA(2) may then activate CREB through PI3K/Akt and extracellular ERK pathways, thereby contributing to the NNK-promoted survival and growth of lung cancer cells.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Apoptosis; Bridged Bicyclo Compounds, Heterocyclic; Carcinogens; Cell Growth Processes; Cell Survival; Cyclic AMP Response Element-Binding Protein; Extracellular Signal-Regulated MAP Kinases; Fatty Acids, Unsaturated; Humans; Hydrazines; Lung Neoplasms; Nitrosamines; p38 Mitogen-Activated Protein Kinases; Phosphatidylinositol 3-Kinases; Proto-Oncogene Proteins c-akt; Receptors, Thromboxane A2, Prostaglandin H2; Smoking; Thromboxane A2; Thromboxane-A Synthase; Tumor Cells, Cultured

Liqi, an herbal preparation used in traditional Chinese medicine, has been used to treat cancer in China for centuries. We investigated the anti-tumor effects of liqi and their mechanisms in mice that had been xenografted with tumors.. Sarcoma 180 tumor, Lewis lung carcinoma, and SGC-7901 cells were implanted in BALB/c mice, C57BL/6 mice, and BALB/c nude mice, respectively. Liqi was administered to subgroups of these mice. The tumor weight and size were measured. Cell cycle analysis and T lymphocyte subsets were determined by flow cytometry. The activity of NK cells and TNF was tested using cytotoxicity assay on YAC-1 cells and L929 cells, respectively, and the activity of IL-2 was tested with an IL-2-dependent CTLL-2 cell proliferation assay. Platelet aggregation was monitored by measuring electric impedance, and the levels of thromboxane A2 (TXA2) and prostacyclin (PGI2) in blood were measured by 125I-TXB2 and 125I-Keto-PGF1alpha radioimmunoassay.. The results showed that liqi inhibited tumor growth in tumor-implanted mice and arrested the cell proliferation in the G0/G1 phase and reduced the portion of cells in S and G2/M phase for SGC-7901 cells. Liqi increased the activity of NK cells and TNF-alpha, stimulated IL-2 production and activity, and regulated T lymphocyte subpopulations. Liqi inhibited the Lewis lung carcinoma metastasis by inhibiting platelet aggregation and normalizing the balance between TXA2 and PGI2.. All these findings demonstrated that liqi has an anti-tumor effect in vivo. The mechanism may be related to immune regulation and anticoagulation effects.

Topics: Animals; Antineoplastic Agents, Phytogenic; Carcinoma, Lewis Lung; Cell Cycle; Cell Line, Tumor; Cell Proliferation; Drugs, Chinese Herbal; Epoprostenol; Female; Interleukin-2; Killer Cells, Natural; Lung Neoplasms; Magnoliopsida; Male; Mice; Mice, Inbred BALB C; Mice, Nude; Neoplasm Metastasis; Phytotherapy; Platelet Aggregation; Sarcoma, Experimental; T-Lymphocyte Subsets; Thromboxane A2; Tumor Necrosis Factor-alpha

The GTPase RhoA is a downstream target of heterotrimeric G(13) proteins and plays key roles in cell migration and invasion. Here, we show that expression in human melanoma cells of a constitutively active, GTPase-deficient Galpha(13) form (G(alpha)(13)QL) or lysophosphatidylcholine (LPC)-promoted signaling through G(alpha)(13)-coupled receptors led to a blockade of chemokine-stimulated RhoA activation and cell invasion that was rescued by active RhoA. Melanoma cells expressing G(alpha)(13)QL or cells stimulated with LPC displayed an increase in p190RhoGAP activation, and defects in RhoA activation and invasion were recovered by knocking down p190RhoGAP expression, thus identifying this GTPase-activating protein (GAP) protein as a downstream G(alpha)(13) target that is responsible for these inhibitory responses. In addition, defective stress fiber assembly and reduced migration speed underlay inefficient invasion of G(alpha)(13)QL melanoma cells. Importantly, G(alpha)(13)QL expression in melanoma cells led to impairment in lung metastasis associated with prolonged survival in SCID mice. The data indicate that G(alpha)(13)-dependent downstream effects on RhoA activation and invasion tightly depend on cell type-specific GAP activities and that G(alpha)(13)-p190RhoGAP signaling might represent a potential target for intervention in melanoma metastasis.

Topics: Animals; Cell Line, Tumor; Chemokine CXCL12; GTP-Binding Protein alpha Subunits, G12-G13; GTP-Binding Protein alpha Subunits, Gi-Go; Guanine Nucleotide Exchange Factors; Humans; Lung Neoplasms; Lysophosphatidylcholines; Melanoma; Mice; Mice, SCID; Neoplasm Invasiveness; Proto-Oncogene Proteins c-vav; Repressor Proteins; rhoA GTP-Binding Protein; Signal Transduction; Swiss 3T3 Cells; Thromboxane A2

In the present study, we measured prostanoid synthesis and the expression of genes associated with prostanoid signaling in human non-small cell lung carcinoma (NSCLC) cell lines and in primary human tumors. Consistent with the proposed growth promoting role of PGE2, we found that NSCLC cell lines frequently co-expressed the genes encoding cyclooxygenase-2 and the prostaglandin E2 (PGE2) receptors EP1, 2 and 4 concomitant with the synthesis of PGE2. In contrast, NSCLC cells did not synthesize appreciable amounts of prostaglandin I2 (PGI2, prostacyclin), lacked PGI2 synthase (PGIS) and did not express the gene coding for the PGI2 receptor IP at detectable levels. In agreement with this finding, PGIS mRNA levels were dramatically diminished in primary human tumor samples as compared to matched normal lung tissue. Finally, thromboxane A2 (TxA2) was synthesized in NSCLC cell lines, but transcription of the gene coding for the TxA2 receptor TP was not observed in these cells. In marked contrast, lung fibroblasts synthesized all three prostanoids and their receptors at high levels. While the observed expression patterns were consistent with the existence of autocrine/paracrine PGE2 signaling loops in NSCLC cells, PGI2- and TxA2-mediated signals may play a role in tumor stroma cells.

Topics: Animals; Carcinoma, Non-Small-Cell Lung; Cell Line, Tumor; Cyclooxygenase 2; Dinoprostone; Epoprostenol; Gas Chromatography-Mass Spectrometry; Humans; Immunoblotting; Lung Neoplasms; Mass Spectrometry; Mice; NIH 3T3 Cells; Prostaglandins; Receptors, Prostaglandin E; Receptors, Prostaglandin E, EP1 Subtype; Receptors, Prostaglandin E, EP2 Subtype; Receptors, Prostaglandin E, EP4 Subtype; Receptors, Thromboxane A2, Prostaglandin H2; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Signal Transduction; Thromboxane A2

Meconium aspiration syndrome (MAS) is a cause of significant morbidity and mortality in the perinatal period. Despite the clinical relevance of MAS, its pathogenesis is poorly understood. Epithelial cell-derived prostanoids are involved in the regulation of several cellular functions within the lung, including the control of tone and reactivity of airway and vascular smooth muscle. In this study, we evaluated whether exposure to meconium affects the metabolic function of human airway epithelial cells. Monolayers of A549 cells, a transformed human epithelial cell line, were incubated with various concentrations of meconium. Control cells were incubated with serum-free medium in a similar manner. The supernatant fluid was removed at various time points and assayed for thromboxane A(2) (TXA(2)) production. The latter was accomplished by measuring its immediate and stable metabolite thromboxane B(2), using an enzyme-linked immunosorbent assay (ELISA). In selected experiments, the modulatory effects of indomethacin (10(-6) M), dexamethasone (10(-6) M), and L-nitroarginine methyl ester (L-NAME, 10(-6) M) on TXA(2) production were evaluated. Results were expressed in terms of pg/mg protein (mean +/- SE). We found that exposure to meconium produced a significant release of TXA(2) from A549 cells. Indomethacin, dexamethasone, and in part, L-NAME inhibited meconium-induced release of TXA(2). Our findings demonstrate that meconium enhances the production of thromboxanes from A549 cells, suggesting that airway epithelial cells and their metabolic products may play an important role in the pathogenesis of MAS.

Topics: Dexamethasone; Epithelial Cells; Humans; Indomethacin; Infant, Newborn; Lung Neoplasms; Meconium; NG-Nitroarginine Methyl Ester; Thromboxane A2; Tumor Cells, Cultured

Prostaglandin endoperoxide H synthases and their arachidonate products have been implicated in modulating angiogenesis during tumor growth and chronic inflammation. Here we report the involvement of thromboxane A(2), a downstream metabolite of prostaglandin H synthase, in angiogenesis. A TXA(2) mimetic, U46619, stimulated endothelial cell migration. Angiogenic basic fibroblast growth factor (bFGF) or vascular endothelial growth factor (VEGF) increased TXA(2) synthesis in endothelial cells three- to fivefold. Inhibition of TXA(2) synthesis with furegrelate or CI reduced HUVEC migration stimulated by VEGF or bFGF. A TXA(2) receptor antagonist, SQ29,548, inhibited VEGF- or bFGF-stimulated endothelial cell migration. In vivo, CI inhibited bFGF-induced angiogenesis. Finally, development of lung metastasis in C57Bl/6J mice intravenously injected with Lewis lung carcinoma or B16a cells was significantly inhibited by thromboxane synthase inhibitors, CI or furegrelate sodium. Our data demonstrate the involvement of TXA(2) in angiogenesis and development of tumor metastasis.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Benzofurans; Bridged Bicyclo Compounds, Heterocyclic; Chemotaxis; Dinoprost; Dinoprostone; Endothelial Growth Factors; Endothelium, Vascular; Enzyme Inhibitors; Epoprostenol; Fatty Acids, Unsaturated; Fibroblast Growth Factor 2; Humans; Hydrazines; Lung Neoplasms; Lymphokines; Male; Melanoma, Experimental; Mice; Mice, Inbred C57BL; Neoplasm Metastasis; Neovascularization, Pathologic; Rats; Receptors, Thromboxane; Thromboxane A2; Thromboxane-A Synthase; Umbilical Veins; Vascular Endothelial Growth Factor A; Vascular Endothelial Growth Factors

We evaluated the effect of thromboxane A2 (TXA2) blockade on cisplatin-induced apoptosis in non-small-cell lung cancer (NSCLC) cell lines. Cisplatin induced apoptosis in PC/9 and PC-9/CDDP in a dose-dependent manner. Treatment with specific TXA2 antagonist, calcium 5(Z)-1R,2S,3S,4S-7-[3-phenylsulfonylaminobicyclo[2,2,1]hept-2-yl]- 5-heptonoate hydrate (S-1452) and 5(Z-6-[(1R,2R,3R,4S)-3-(N-4-bromobenzenesulfonyl aminomethyl) bicyclo[2,2,1]heptane-2-yl]-hex-5-enoic acid (ONO-NT-126), enhanced the cisplatin-induced apoptosis in each cell line. Acetyl-L-aspartyl-glutamyl-valyl-aspart-1-aldehyde (Ac-DEVD-CHO) inhibited cisplatin-induced apoptosis and enhancement of the apoptosis by TXA2 blockade, but acetyl-L-tyrosyl-valyl-alanyl-aspart-1-aldehyde (Ac-YVAD-CHO) had no effect on the apoptosis. There was no difference in the interleukin-1beta-converting enzyme (ICE) protease protein expression in either cell line. Cysteine protease p32(CPP32) protein expression was lower in PC-9/CDDP but was not changed by S-1452, cisplatin, or cotreatment with cisplatin and S-1452. Ice and Ced-3 homolog (ICH-1L) expression was significantly lower in PC-9/CDDP and was up-regulated by S-1452 or ONO-NT-126. These data suggest that ICH-1L might play a critical role in cisplatin-induced apoptosis and that TXA2 blockade up-regulates ICH-1L protein expression. Overexpression of ICH-1L and treatment with cisplatin might result in an increase in apoptosis in NSCLC cell lines.

Topics: Apoptosis; Blotting, Western; Bridged Bicyclo Compounds; Carcinoma, Non-Small-Cell Lung; Caspase 2; Caspases; Cisplatin; Dose-Response Relationship, Drug; Enzyme-Linked Immunosorbent Assay; Fatty Acids, Monounsaturated; Gene Expression Regulation, Neoplastic; Humans; Lung Neoplasms; Prostaglandin Antagonists; Thromboxane A2; Tumor Cells, Cultured; Up-Regulation

Ethanol (88-880 mmol/l) inhibited the formation of proaggregatory, vasoconstricting thromboxane A2 (TxA2) during whole blood clotting and during thrombin-induced aggregation of platelet rich plasma. This inhibition was counteracted by the addition of exogenous arachidonic acid, which suggested that ethanol suppressed the liberation of arachidonic acid, evidently by inhibiting phospholipase A2. Ethanol had no effect on the formation of prostacyclin (PGI2, epoprostenol), the endogenous antagonist of TxA2, by human lung. Thus our results suggest that ethanol may shift the balance between TxA2 and PGI2 to the dominance of antiaggregatory, vasodilating PGI2 by suppressing the release of arachidonic acid in platelets. This finding might partly explain why ethanol protects against atherosclerosis and also the increased risk of subarachnoidal haemorrhage after heavy ethanol intake.

Topics: Adult; Arachidonic Acids; Blood Platelets; Dose-Response Relationship, Drug; Epoprostenol; Ethanol; Female; Humans; In Vitro Techniques; Lung; Lung Neoplasms; Male; Middle Aged; Platelet Aggregation; Thromboxane A2; Thromboxanes

Platelet aggregation plays an important role in the phase of arrest of tumor cells in the microcirculation of the metastatic site in blood-borne metastasis. Hyper-aggregability of platelets, hypercoagulability and suppression of fibrinolysis accelerate the adhesion of tumor cells in the microcirculation of the target organ, but it may be inhibited by suppression of platelet aggregation, biosynthesis of thromboxane A2 and the coagulation system. Platelet aggregation is induced by not only metabolites of arachidonic acid but also factors released from tumor cells. Thromboxane A2 and prostaglandin I2 may play a role in blood-borne metastasis.

Topics: Animals; Blood Platelets; Epoprostenol; Fibrinolysis; Lung Neoplasms; Male; Melanoma; Mice; Mice, Nude; Neoplasms, Experimental; Neoplastic Cells, Circulating; Platelet Aggregation; Rats; Thromboxane A2