thapsigargin and Adenocarcinoma

Topics: Adenocarcinoma; Biomarkers, Tumor; Case-Control Studies; Cell Line, Tumor; Drug Screening Assays, Antitumor; Gene Regulatory Networks; Humans; Integrin beta Chains; Integrin beta1; MicroRNAs; Pancreatic Neoplasms; Phosphatidylinositol 3-Kinases; Proto-Oncogene Proteins c-akt; Thapsigargin

In this study, we investigated the anticancer activity of icariin (ICA) against human lung adenocarcinoma cells in vitro and in vivo and explored the role of endoplasmic reticulum (ER) stress (ERS) signaling in this process. ICA treatment resulted in a dose- and time-dependent decrease in the viability of human lung adenocarcinoma A549 cells. Additionally, ICA exhibited potent anticancer activity, as evidenced by reductions in A549 cell adhesion, migration and intracellular glutathione (GSH) levels and increases in the apoptotic index, Caspase 3 activity, and reactive oxygen species. Furthermore, ICA treatment increased the expression of ERS-related molecules (p-PERK, ATF6, GRP78, p-eIF2α, and CHOP), up-regulated the apoptosis-related protein PUMA and down-regulated the anti-apoptosis-related protein Bcl2. The down-regulation of ERS signaling using PERK siRNA desensitized lung adenocarcinoma cells to ICA treatment, whereas the up-regulation of ERS signaling using thapsigargin (THA) sensitized lung adenocarcinoma cells to ICA treatment. Additionally, ICA inhibited the growth of human lung adenocarcinoma A549 cell xenografts by increasing the expression of ERS-related molecules (p-PERK and CHOP), up-regulating PUMA, and down-regulating Bcl2. These data indicate that ICA is a potential inhibitor of lung adenocarcinoma cell growth by targeting ERS signaling and suggest that the activation of ERS signaling may represent a novel therapeutic intervention for lung adenocarcinoma.

Topics: Adenocarcinoma; Adenocarcinoma of Lung; Animals; Antineoplastic Agents; Apoptosis; Apoptosis Regulatory Proteins; Caspase 3; Cell Line, Tumor; Cell Survival; Endoplasmic Reticulum Chaperone BiP; Endoplasmic Reticulum Stress; Enzyme Inhibitors; Flavonoids; Glutathione; Heterografts; Humans; Lung Neoplasms; Male; Mice, Nude; Reactive Oxygen Species; RNA, Small Interfering; Signal Transduction; Thapsigargin

The objective of this study was performed to investigate the effects of thapsigargin on apoptosis, actin cytoskeletal dynamics, and actin cytoskeletal proteins in human lung adenocarcinoma cell. Thapsigargin is a specific irreversible inhibitor of ER calcium-ATPase, which may promote ER stress by depletion of lumenal calcium stores and show potential to induce cell death. The effects of thapsigargin on the apoptosis in A549 cells were assayed by Hoechst staining. Moreover, the F-actin staining by Rhodamine-phalloidin and RhoA antibody for cytoskeleton organizations were applied to A549 cells. To confirm the impairment of cytoskeletal dynamics treated with thapsigargin, western blots were applied to analyze the protein levels of p-Cofilin-1 (Ser3), Cofilin-1, and pPaxillin (Tyr118), as well as RhoA and pS6 (S240/244). Results suggest that thapsigargin may induce cell death in A549 cells with a time- and dose-dependent manner. The F-actin fibers and RhoA signals are also reduced with a time- and dose-dependent manner by thapsigargin treatment. The phosphorylation forms of Cofilin-1 and paxillin are attenuated by 1 μM thapsigargin treatment for 24 h. These alternations may be caused by the inhibition of of mTORC1 activities (indicated by pS6 (Ser240/244)) and RhoA pathways after thapsigargin treatment. The present findings highlight important roles of calcium entry in cytoskeleton organization and apoptosis in human lung adenocarcinoma cells and will help to set a stage to the clinical treatment of cancer cell metastasis.

Topics: Adenocarcinoma; Apoptosis; Blotting, Western; Calcium; Calcium-Transporting ATPases; Cell Line, Tumor; Cofilin 1; Cytoskeletal Proteins; Cytoskeleton; Endoplasmic Reticulum Stress; Humans; Lung Neoplasms; Paxillin; Thapsigargin

GRP78, a major endoplasmic reticulum chaperone and signaling regulator, is commonly overexpressed in cancer. Moreover, induction of GRP78 by a variety of anti-cancer drugs, including histone deacetylase inhibitors, confers chemoresistance to cancer, thereby contributing to tumorigenesis. Thus, therapies aimed at decreasing GRP78 levels, which results in the inhibition of tumor cell proliferation and resensitization of tumor cells to chemotherapeutic drugs may hold promise for cancer treatment. Despite advances in our understanding of GRP78 actions, little is known about endogenous inhibitors controlling its expression. As endogenous regulators, microRNAs (miRNAs) play important roles in modulating gene expression; therefore, we sought to identify miRNA(s) that target GRP78, under the hypothesis that these miRNAs may serve as therapeutic agents. Here, we report that three miRNAs (miR-30d, miR-181a, miR-199a-5p) predicted to target GRP78 are down-regulated in prostate, colon and bladder tumors, and human cancer cell lines. We show that in C42B prostate cancer cells, these miRNAs down-regulate GRP78 and induce apoptosis by directly targeting its 3' untranslated region. Importantly, we demonstrate that the three miRNAs act cooperatively to decrease GRP78 levels, suggesting that multiple miRNAs may be required to efficiently control the expression of some genes. In addition, delivery of multiple miRNAs by either transient transfection or lentivirus transduction increased the sensitivity of cancer cells to the histone deacetylase inhibitor, trichostatin A, in C42B, HCT116 and HL-60 cells. Together, our results indicate that the delivery of co-transcribed miRNAs can efficiently suppress GRP78 levels and GRP78-mediated chemoresistance, and suggest that this strategy holds therapeutic potential.

Topics: 3' Untranslated Regions; Adenocarcinoma; Animals; Apoptosis; Cell Line, Tumor; Colonic Neoplasms; Drug Resistance, Neoplasm; Endoplasmic Reticulum Chaperone BiP; Gene Expression Regulation, Neoplastic; Genes, Reporter; Genetic Vectors; Heat-Shock Proteins; Histone Deacetylase Inhibitors; HL-60 Cells; Humans; Hydroxamic Acids; Lentivirus; Male; Mice; Mice, Nude; MicroRNAs; Neovascularization, Pathologic; Prostatic Neoplasms; RNA; RNA, Messenger; Thapsigargin; Transcription, Genetic; Transfection; Tumor Stem Cell Assay; Urinary Bladder Neoplasms; Xenograft Model Antitumor Assays

Calcium-mediated proteolysis plays an important role in cell migration. Lysophosphatidic acid (LPA), a lipid mediator present in serum, enhances migration of carcinoma cells. The effects of LPA on calpain-mediated proteolysis were, therefore, examined in PC-3, a human prostate cancer cell line.. Cultured PC-3 cells were used in studies utilizing pharmacologic interventions, immunoblotting, and confocal immunolocalization.. Focal adhesion kinase (FAK), a tyrosine kinase involved in cell adhesion, is rapidly proteolyzed in serum-starved PC-3 cells exposed to the calcium ionophore, ionomycin; Nck, p130CAS, PKCα, and Ras-GAP are also degraded. Thapsigargin, which causes more moderate increases in intracellular calcium, induces partial proteolysis of these proteins. Calpain inhibitors block the proteolytic responses to ionomycin and thapsigargin. Ionomycin does not induce proteolysis in cells maintained in serum, suggesting a protective role for growth factors contained in serum. LPA causes minor FAK proteolysis when added alone, but protects against ionomycin-induced proteolysis in a time-dependent manner. LPA also protects against the cell detachment that eventually follows ionomycin treatment. The response to LPA is blocked by an LPA receptor antagonist. A similar effect of LPA is observed in ionomycin-treated Rat-1 fibroblasts. In PC-3 cells, the protective effects of LPA and serum are correlated with phosphorylation and redistribution of paxillin, suggesting roles for phosphorylation-mediated protein-protein interactions.. The complex effects of LPA on calpain-mediated proteolysis of FAK and other adhesion proteins are likely to play a role in the ability of LPA to promote attachment, migration, and survival of prostate cancer cells.

Topics: Adenocarcinoma; Animals; Calpain; Cell Adhesion; Cell Line, Tumor; Cell Movement; Cell Survival; Drug Screening Assays, Antitumor; Fibroblasts; Focal Adhesion Protein-Tyrosine Kinases; Humans; Ionomycin; Isoxazoles; Lysophospholipids; Male; Paxillin; Phosphorylation; Propionates; Prostatic Neoplasms; Proteolysis; Rats; Thapsigargin

Enteric neurotransmitters that act at G protein-coupled receptors (GPCRs) are well known to acutely promote epithelial Cl(-) and fluid secretion. Here we examined if acute GPCR activation might have more long-term consequences for epithelial secretory function.. Cl(-) secretion was measured as changes in short-circuit current across voltage-clamped T(84) colonic epithelial cells. Protein expression was measured by western blotting and intracellular Ca(2+) levels by Fura-2 fluorescence.. While acute (15 min) treatment of T(84) cells with a cholinergic G(q) PCR agonist, carbachol (CCh), rapidly stimulated Cl(-) secretion, subsequent CCh-induced responses were attenuated in a biphasic manner. The first phase was transient and resolved within 6 h but this was followed by a chronic phase of attenuated responsiveness that was sustained up to 48 h. CCh-pretreatment did not chronically alter responses to another G(q)PCR agonist, histamine, or to thapsigargin or forskolin which elevate intracellular Ca(2+) and cAMP, respectively. This chronically acting antisecretory mechanism is not shared by neurotransmitters that activate G(s)PCRs. Conditioned medium from CCh-pretreated cells mimicked its chronic antisecretory actions, suggesting involvement of an epithelial-derived soluble factor but further experimentation ruled out the involvement of epidermal growth factor receptor ligands. Acute CCh exposure did not chronically alter surface expression of muscarinic M(3) receptors but inhibited intracellular Ca(2+) mobilization upon subsequent agonist challenge.. These data reveal a novel, chronically acting, antisecretory mechanism that downregulates epithelial secretory capacity upon repeated G(q)PCR agonist exposure. This mechanism involves release of a soluble factor that uncouples receptor activation from downstream prosecretory signals.

Topics: Adenocarcinoma; Calcium; Carbachol; Cell Line, Tumor; Chlorides; Colforsin; Colonic Neoplasms; Epithelial Cells; Histamine; Humans; Patch-Clamp Techniques; Protein Kinase C; Receptor, Muscarinic M3; Receptors, G-Protein-Coupled; Thapsigargin

Tumor cells adapt to endoplasmic reticulum (ER) stress through a set of conserved intracellular pathways, as part of a process termed the unfolded protein response (UPR). The expression of UPR genes/proteins correlates with increasing progression and poor clinical outcome of several tumor types, including prostate cancer. UPR signaling can activate NF-κB, a master regulator of transcription of pro-inflammatory, tumorigenic cytokines. Previous studies have shown that Lipocalin 2 (Lcn2) is upregulated in several epithelial cancers, including prostate cancer, and recently Lcn2 was implicated as a key mediator of breast cancer progression. Here, we hypothesize that the tumor cell UPR regulates Lcn2 production.. We interrogated Lcn2 regulation in murine and human prostate cancer cells undergoing pharmacological and physiological ER stress, and tested UPR and NF-κB dependence by using pharmacological inhibitors of these signaling pathways.. Induction of ER stress using thapsigargin (Tg), a canonical pharmacologic ER stress inducer, or via glucose deprivation, a physiologic ER stressor present in the tumor microenvironment, upregulates LCN2 production in murine and human prostate cancer cells. Inhibition of the UPR using 4-phenylbutyric acid (PBA) dramatically decreases Lcn2 transcription and translation. Inhibition of NF-κB in prostate cancer cells undergoing Tg-mediated ER stress by BAY 11-7082 abrogates Lcn2 upregulation.. We conclude that the UPR activates Lcn2 production in prostate cancer cells in an NF-κB-dependent manner. Our results imply that the observed upregulation of Lipocalin 2 in various types of cancer cells may be the direct consequence of concomitant UPR activation, and that the ER stress/Lipocalin 2 axis is a potential new target for intervention in cancer progression.

Topics: Acute-Phase Proteins; Adenocarcinoma; Animals; Cell Line, Tumor; Endoplasmic Reticulum; Gene Expression Regulation, Neoplastic; Glucose; Humans; Lipocalin-2; Lipocalins; Male; Mice; Neoplasm Proteins; NF-kappa B; Nitriles; Oncogene Proteins; Phenylbutyrates; Prostatic Neoplasms; Protein Biosynthesis; Proto-Oncogene Proteins; Sulfones; Thapsigargin; Transcription, Genetic; Tunicamycin; Unfolded Protein Response; Up-Regulation

The effect of 2,4,6-trimethyl-N-(meta-3-trifluoromethyl-phenyl)-benzenesulfonamide (m-3M3FBS), a presumed phospholipase C activator, on cytosolic free Ca²⁺ concentrations ([Ca²⁺]i) in PC3 human prostate cancer cells is unclear. This study explored whether m-3M3FBS changed basal [Ca²⁺]i levels in suspended PC3 cells by using fura-2 as a Ca²⁺-sensitive fluorescent dye. M-3M3FBS at concentrations between 10-50 microM increased [Ca²⁺]i in a concentration-dependent manner. The Ca²⁺ signal was reduced by 60% by removing extracellular Ca²⁺. M-3M3FBS-induced Ca²⁺ influx was inhibited by the store-operated Ca²⁺ channel blockers nifedipine, econazole and SK&F96365, and by the phospholipase A2 inhibitor aristolochic acid. In Ca²⁺-free medium, 30 microM m-3M3FBS pretreatment greatly inhibited the [Ca²⁺]i rise induced by the endoplasmic reticulum Ca²⁺ pump inhibitor thapsigargin or BHQ. Conversely, pretreatment with thapsigargin, BHQ or cyclopiazonic acid reduced the major part of m-3M3FBS-induced [Ca²⁺]i rise. Inhibition of phospholipase C with U73122 did not much alter m-3M3FBS-induced [Ca²⁺]i rise. Collectively, in PC3 cells, m-3M3FBS induced [Ca²⁺]i rises by causing phospholipase C-independent Ca²⁺ release from the endoplasmic reticulum and Ca²⁺ influx via store-operated Ca²⁺ channels.

Topics: Adenocarcinoma; Aristolochic Acids; Calcium; Calcium Channel Blockers; Calcium Signaling; Cell Line, Tumor; Dose-Response Relationship, Drug; Endoplasmic Reticulum; Humans; Indoles; Male; Models, Animal; Phospholipase A2 Inhibitors; Prostatic Neoplasms; Sulfonamides; Thapsigargin; Type C Phospholipases

We studied potential interactions between the endoplasmic reticulum (ER) stress response and the MEK/ERK pathway. Induction of ER stress did not trigger significant apoptosis, but caused rapid activation of ERK1/2 in gastric cancer cells. Inhibition of MEK enhanced ER stress-induced apoptosis via a caspase-dependent, mitochondria-mediated mechanism. This was associated with blockage of ER stress-mediated up-regulation of GRP78. The latter appeared to be critical in antagonizing the apoptosis-inducing potential of ER stress. Thus, activation of MEK/ERK by ER stress is necessary for induction of GRP78 that protects against apoptosis in gastric cancer cells submitted to ER stress.

Topics: Activating Transcription Factor 6; Adenocarcinoma; Antiviral Agents; Apoptosis; Blotting, Western; Caspases; eIF-2 Kinase; Endoplasmic Reticulum; Endoplasmic Reticulum Chaperone BiP; Endoribonucleases; Enzyme Inhibitors; Heat-Shock Proteins; Humans; MAP Kinase Kinase 1; Membrane Potential, Mitochondrial; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Molecular Chaperones; Protein Serine-Threonine Kinases; RNA, Small Interfering; Stomach Neoplasms; Thapsigargin; Tumor Cells, Cultured; Tunicamycin; Up-Regulation

The androgen-regulated protein androgen-induced bZIP (AIbZIP) is a bZIP transcription factor that localizes to the membrane of the endoplasmic reticulum (ER). The physiological role of AIbZIP is unknown, but other ER-bound transcription factors such as ATF6 and SREBPs play a crucial role in the regulation of protein processing and lipid synthesis, respectively. In response to alterations in the intracellular milieu, ATF6 and SREBPs are processed to their transcriptionally active forms by regulated intramembrane proteolysis. In humans, AIbZIP mRNA is expressed in several organs including the pancreas, liver, and gonads, but it is especially abundant in prostate epithelial cells. We therefore used LNCaP human prostate cancer cells as a model to identify stimuli that lead to AIbZIP activation and define the transcriptional targets of AIbZIP. In LNCaP cells, AIbZIP was processed to its transcriptionally active form by drugs that deplete ER calcium stores (i.e., A23187 and caffeine), but it was unaffected by an inhibitor of protein glycosylation (tunicamycin). To identify AIbZIP-regulated genes, we generated LNCaP cell lines that conditionally express the processed form of AIbZIP and used Affymetrix microarrays to screen for AIbZIP-regulated transcripts. Selected genes (n = 48) were validated by Northern blot hybridization. The results reveal that the downstream targets of AIbZIP include genes that are implicated in protein processing (e.g., BAG3, DNAJC12, KDELR3). Strikingly, a large number of AIbZIP-regulated transcripts encode proteins that are involved in transcriptional regulation, small molecule transport, signal transduction, and metabolism. These results suggest that AIbZIP plays a novel role in cell homeostasis.

Topics: Adenocarcinoma; Amino Acid Sequence; Basic-Leucine Zipper Transcription Factors; Brefeldin A; Caffeine; Calcimycin; Calcium Signaling; Cell Line, Tumor; Cyclic AMP Response Element-Binding Protein; Endoplasmic Reticulum; Gene Expression Profiling; Gene Expression Regulation, Neoplastic; Golgi Apparatus; Homeostasis; Humans; Male; Molecular Sequence Data; Neoplasm Proteins; Nuclear Proteins; Prostatic Neoplasms; Protein Processing, Post-Translational; Recombinant Fusion Proteins; RNA, Small Interfering; Thapsigargin; Transcription, Genetic; Tunicamycin

Recent studies have identified novel actions for 2-aminoethoxydiphenyl borate (2-APB) in triggering calcium release and enhancing calcium influx induced by the depletion of intracellular calcium stores. In this study, we have examined the effects of 2-APB on the human lung adenocarcinoma A549 cell line, which we have previously shown displays a unique calcium influx response, when ER calcium stores are depleted by thapsigargin (TG) treatment. Here, we show that low concentrations of 2-APB failed to induce the rapid augmentation of TG-activated calcium influx previously reported for other cell types. We observed that store-operated calcium (SOC) channels in the A549 cell line exhibited short-term sensitivity to low doses of 2-APB, perhaps reflecting a delayed augmentation of SOC channel activity or the recruitment of 2-APB-insensitive SOC channels. In both intact and permeabilized cells, 2-APB effectively discharged a subset of A549 calcium pools corresponding to the hormone-sensitive intracellular calcium stores. The 2-APB-induced calcium release produced a long-lasting perturbation of the adenosine triphosphate (ATP)-releasable calcium pools, effectively uncoupling ATP-activated calcium release even, when stores are replenished with calcium. In contrast to previous reports, we found that disruption of either the actin or microtubule-based cytoskeleton failed to block the 2-APB-induced effects on calcium signaling in A549 cells. Our study describes novel cytoskeletal-independent effects of 2-APB on Ca2+-signaling pathways, revealing differentially sensitive Ca2+-influx pathways and long-term perturbation of hormone-sensitive Ca2+ stores.

Topics: Actins; Adenocarcinoma; Adenosine Triphosphate; Antineoplastic Agents, Phytogenic; Boron Compounds; Calcium; Calcium Channels; Calcium Signaling; Cell Line, Tumor; Cytochalasin D; Cytoskeleton; Digitonin; Dose-Response Relationship, Drug; Enzyme Inhibitors; Green Fluorescent Proteins; Humans; Indicators and Reagents; Inositol 1,4,5-Trisphosphate; Ionomycin; Lung Neoplasms; Microscopy, Confocal; Nucleic Acid Synthesis Inhibitors; Paclitaxel; Thapsigargin; Time Factors

Loss of contact with the extracellular matrix (ECM) triggers a specialized form of apoptosis known as "anoikis" in normal epithelial cells. Dependence on adhesion to ECM is often lost in transformed cells, and the degree of anchorage independence may vary in non-metastatic and metastatic cancer cells. BCL-2 oncoprotein overexpression correlates with the progression and metastases of prostate cancer. Materials and Methods We studied anoikis in suspension cultures of PC-3 and LNCaP prostate carcinoma cells selected for enhanced metastatic potential in vivo and in PC-3 and LNCaP cells stably transfected with BCL-2. Apoptosis-associated DNA fragmentation was measured by agarose gel electrophoresis and propidium iodide staining and flow cytometry. Expression of BCL-2 family polypeptides was determined by immunoblotting.. Non-metastatic PC-3P cells were significantly more sensitive to anoikis than the metastatic PC-3 variants (PC-3M, PC-3M-PRO-4, and PC-3M-LN-4), but anoikis resistance did not correlate with metastatic potential in LNCaP-derived cell lines. Expression of BCL-2 was higher in metastatic PC-3 and LNCaP subclones compared to isogenic non-metastatic cells, but these levels were not affected by anoikis. Enforced overexpression of BCL-2 did not protect either PC-3P or LNCaP-PRO-5 cells from anoikis, even though it rendered them resistant to thapsigargin and inhibited cytochrome c release. Strikingly, cells that died of anoikis maintained their pretreatment levels of BCL-2, whereas the cells that survived anoikis expressed much lower levels of the protein.. Sensitivity to anoikis is regulated by BCL-2 independent mechanisms in LNCaP and PC-3 prostate cancer cells.

Topics: Adenocarcinoma; Anoikis; Blotting, Western; Carcinogens; Cell Adhesion; DNA Fragmentation; Electrophoresis, Agar Gel; Flow Cytometry; Humans; Male; Prostatic Neoplasms; Proto-Oncogene Proteins c-bcl-2; Thapsigargin; Transfection; Tumor Cells, Cultured

Functional overexpression of Bcl-2 has been reported to confer an anti-apoptotic potential in a variety of cell types. The role of Bcl-2 in epithelial cell-cycle control and in interactions with other cell-cycle regulators is not clearly understood. Its expression has been correlated with the hormono- and chemo-resistant phenotype in advanced prostate cancer. The aim of this study was to investigate the mechanisms through which Bcl-2 mediates increased cytotoxic chemoresistance by assessing alterations in the expression of cell death regulatory molecules. The DU145 human prostatic adenocarcinoma cell line was stably transfected with a Bcl-2 encoding expression plasmid. Two Bcl-2 transfectants, DKC9 and DKC11, were expanded for further study. The effects of Bcl-2 expression on cellular proliferation, cell death (+/- adriamycin or thapsigargin), and expression of cell-cycle/death regulators (p53, PCNA, Bax, Bak, Bcl-X(L)) were evaluated. Compared with controls, Bcl-2 transfectants showed no difference in the rate of proliferation, a decrease in p53 (approximately two-fold), an increase in Bax (approximately two-fold) and PCNA (approximately three-fold), and no change in the levels of Bcl-X(L) and Bak proteins. DKC9 and DKC11 also exhibited a significantly increased chemoresistance to adriamycin (0.0025-5 microM) and thapsigargin (0.0025-5 microM) compared with controls. In the presence of thapsigargin or adriamycin, levels of Bcl-2 and its heterodimeric partner Bax were elevated approximately two-fold with no change in Bak in Bcl-2 transfectants in contrast to controls, where Bak was increased (two-fold). This is the first study to demonstrate that Bcl-2 transfection modulates the expression of mutant p53, Bax, and PCNA in prostate cancer cells. Moreover, Bcl-2 overexpression conferred a significant cytotoxic chemoresistance and altered the balance of expression of death promoters (from Bak, a dominant death promoter in controls, to Bax) in response to thapsigargin and adriamycin.

Topics: Adenocarcinoma; Antineoplastic Agents; Cell Cycle Proteins; Cell Death; Dose-Response Relationship, Drug; Doxorubicin; Drug Resistance, Neoplasm; Gene Expression Regulation, Neoplastic; Genes, bcl-2; Humans; Male; Prostatic Neoplasms; Thapsigargin; Transfection; Tumor Cells, Cultured

IL-8 is a chemokine that activates and recruits neutrophils and plays a major role in intestinal inflammation. Signal transduction pathways mediated by protein kinases are central in regulating IL-8 gene expression, however, little is known about the role of Ca2+ in this event. In this study, we characterize the effect of intracellular Ca2+ on interleukin-8 gene expression in T84 human colonic epithelial cells.. Cells were stimulated with Ca2+ ionophore, A23187 or thapsigargin, a Ca2+-ATPase inhibitor. Semi-quantitative RT-PCR was used to examine IL-8 mRNA and ELISA for protein quantification. Reporter gene techniques were used to determine transcription rate.. A23187 and thapsigargin caused a dose- and time-dependent accumulation of IL-8 mRNA and protein production which was dependent on the release of Ca2+ from intracellular stores. FK506, a specific inhibitor of calcineurin, inhibited A23187- and thapsigargin-induced IL-8 mRNA expression in a dose dependent manner. Reporter gene studies and actinomycin D chase experiments showed that A23187 and thapsigargin enhanced IL-8 gene transcription and stabilized IL-8 mRNA transcripts, respectively.. Intracellular Ca2+ plays an important role in regulating IL-8 transcriptionally and posttranscriptionally through calcium/calmodulin-dependent calcineurin.

Topics: Adenocarcinoma; Calcimycin; Calcineurin; Calcium; Colon; Colonic Neoplasms; Dose-Response Relationship, Drug; Epithelial Cells; Gene Expression; Humans; Interleukin-8; Ionophores; Kinetics; Protein Kinase C; RNA, Messenger; Tetradecanoylphorbol Acetate; Thapsigargin; Transcription, Genetic; Tumor Cells, Cultured

Regulation of capacitative Ca(2+) entry was studied in two different multidrug resistance (MDR) protein (MRP1) overexpressing cell lines, HT29(col) and GLC4/ADR. MRP1 overexpression was accompanied by a decreased response to thapsigargin. Moreover, inhibition of capacitative Ca(2+) entry by D, L-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol (PDMP) was abolished in MRP1 overexpressing cells. Both PDMP and the MRP1 inhibitor MK571 greatly reduced InsP(3)-mediated (45)Ca(2+) release from intracellular stores in HT29 cells. Again, these effects were virtually abolished in HT29(col) cells. Our results point to a modulatory role of MRP1 on intracellular calcium concentration ([Ca(2+)](i)) homeostasis which may contribute to the MDR phenotype.

Topics: Adenocarcinoma; ATP-Binding Cassette Transporters; Calcium; Calcium Radioisotopes; Colonic Neoplasms; Gene Expression; Homeostasis; Humans; Inositol 1,4,5-Trisphosphate; Morpholines; Multidrug Resistance-Associated Proteins; Propionates; Quinolines; Thapsigargin; Tumor Cells, Cultured

The proinflammatory protein endothelial monocyte-activating polypeptide II (EMAP-II) was first detected in supernatants of murine tumor cells by virtue of its ability to stimulate endothelial-dependent coagulation in vitro. The purified protein has pleiotropic effects on endothelial cells, monocytes, and neutrophils; however, its function in vivo is unknown, and the mechanism whereby it is released from cells is poorly understood. We investigated the expression of EMAP-II in human prostate adenocarcinoma specimens by immunohistochemistry and in LNCaP and DU-145 human prostate adenocarcinoma cells by reverse transcription-PCR, flow cytometry, and Western blotting. We then examined the effects of chemical and physiological stress on release and processing of EMAP-II by LNCaP and DU-145 cells. These cells constitutively express a Mr 34,000 form of EMAP-II that is retained intracellularly. Exposure to agents that induce apoptosis or, in some cases, necrosis induces the release of the Mr 34,000 form and further processing to the Mr 27,000 and Mr 22,000 forms. Hypoxia, but not heat shock, is a potent inducer of release and processing of biologically active EMAP-II by LNCaP and DU-145 cells. We suggest that release of EMAP-II by prostate adenocarcinoma cells as a consequence of treatment with anticancer agents or as a result of constitutive hypoxia may potentiate the effects of those agents through the localized activation of host effector mechanisms.

Topics: Adenocarcinoma; Anti-Bacterial Agents; Antimycin A; Apoptosis; Blotting, Western; Cell Hypoxia; Cytokines; Dose-Response Relationship, Drug; Enzyme Inhibitors; Flow Cytometry; Glucose; Humans; Immunohistochemistry; Ionomycin; Ionophores; Male; Necrosis; Neoplasm Proteins; Peptides; Prostate; Prostatic Neoplasms; Recombinant Proteins; Reverse Transcriptase Polymerase Chain Reaction; RNA-Binding Proteins; Stress, Physiological; Thapsigargin; Tumor Cells, Cultured

Tumor cell extravasation is a determinant step in the process of hematogenous metastasis. The signal transduction pathways involved in the interactions between tumor cells and the vascular endothelium during transendothelial migration are still undefined. In the present study, we have investigated the influence of human breast adenocarcinoma cells (MCF7) on human umbilical vein endothelial cell (HUVEC) intracellular Ca2+ concentration ([Ca2+]i). We show that the contact between MCF7 cells and a confluent HUVEC monolayer induces an immediate and transient increase in HUVEC [Ca2+]i. This [Ca2+]i rise could not be elicited by tumor cell-conditioned medium, isolated tumor cell membranes, inert beads or normal breast epithelial cells, demonstrating the involvement of specific recognition mechanisms between MCF7 cells and HUVEC. Depletion of HUVEC intracellular Ca2+ stores by the endoplasmic reticulum Ca2+-ATPase inhibitor thapsigargin as well as the selective depletion of inositol 1,4,5-triphosphate (IP3)-sensitive Ca2+ stores by prior activation of HUVEC using histamine resulted in a complete inhibition of tumor cell-induced [Ca2+]i elevation. Similar results were obtained when HUVEC monolayers were treated with the tyrosine kinase inhibitor herbimycin A, suggesting a role for tyrosine kinase-associated cell surface receptors in tumor cell-endothelial cell interactions. The depletion of HUVEC intracellular Ca2+ stores by thapsigargin was also shown to delay MCF7-induced endothelial cell disjunction, to prevent their spreading on the subendothelial extracellular matrix and transendothelial migration in vitro. These results suggest that transient changes in endothelial [Ca2+]i may govern multiple steps of tumor cell extravasation.

Topics: Adenocarcinoma; Breast Neoplasms; Calcium; Cell Communication; Cell Movement; Endothelium, Vascular; Enzyme Inhibitors; Female; Humans; Protein-Tyrosine Kinases; Thapsigargin; Tumor Cells, Cultured; Umbilical Veins

We have characterized the ability of several cell types associated with the microvasculature of solid tumors to release nitric oxide (NO.) in response to increases in cytosolic Ca2+ concentration ([Ca2+]c). EA.hy926 immortalized human umbilical vein endothelial cells (EC), rat fibroblasts (RFL), and tumorigenic cells isolated from R3230Ac rat mammary adenocarcinoma (MaC) were treated with thapsigargin (TG), an inhibitor of Ca(2+)-ATPase. NO. output was measured via a chemiluminescence detection system. Baseline NO. output was detectable only for EC. TG caused a significant increase in EC NO. output that could be blocked with NG-monomethyl-L-arginine and restored with L-arginine. TG did not stimulate NO. release from RFL or MaC cells, despite elevating [Ca2+]c in all cells. A Ca(2+)-dependent isoform of NO synthase (eNOS) was detected by immunoblot only in EC. These data indicate that EC, but not RFL or MaC, are capable of Ca(2+)-dependent NO. release and suggest that any Ca(2+)-dependent NO. release within this tumor is primarily of endothelial (and not tumorigenic cell) origin.

Topics: Adenocarcinoma; Animals; Arginine; Calcium; Calcium-Transporting ATPases; Cell Line; Endothelium, Vascular; Female; Fibroblasts; Humans; Immunoblotting; Isoenzymes; Mammary Neoplasms, Experimental; Nitric Oxide; Nitric Oxide Synthase; omega-N-Methylarginine; Rats; Thapsigargin

The human lung small cell adenocarcinoma cell line, A549, demonstrates a concentration-dependent rise in [Ca2+]i in response to extracellular nucleotides. The cells show Ca2+ mobilization on addition of various nucleotides, with an order of agonist potency: UTP > or = ATP > ADP > ADP beta S > AMP; adenosine is ineffective. The EC50 values for UTP and ATP are 12.5 +/- 0.4 microM and 18.9 +/- 0.5 microM, respectively. Together, these results are strongly indicative of the P2U subclass being the major nucleotide receptor expressed in these cells. The Ca2+ response was typically biphasic consisting of an initial spike, representing release of Ca2+ from internal stores, and a subsequent plateau representing Ca2+ influx. The majority of cells showed an agonist-induced Ca2+ increase that was unaffected by pretreatment with the Ca(2+)-ATPase inhibitors 2,5-di(tert-butyl)1,4-benzohydroquinone or thapsigargin. Caffeine did not raise [Ca2+]i above basal levels and applied in conjunction with nucleotide did not attenuate the agonist-mediated response. The Ca2+ influx was sensitive to protein kinase C, and agonist addition in the presence of a protein kinase C inhibitor, D-erythrosphingosine, produced a significantly potentiated Ca2+ influx. Furthermore, agonist-mediated Ca2+ influx was abolished in the presence of a protein kinase C activator, phorbol 12,13-dibutyrate. It is concluded that these cells posses a functional P2U receptor that, upon activation, causes Ca2+ mobilization from TBQ and thapsigargin insensitive stores followed by protein kinase C regulated Ca2+ influx.

Topics: Adenocarcinoma; Adenosine Diphosphate; Adenosine Monophosphate; Adenosine Triphosphate; Benzoquinones; Caffeine; Calcium; Down-Regulation; Enzyme Inhibitors; Humans; Lung Neoplasms; Phosphodiesterase Inhibitors; Protein Kinase C; Purinergic P2 Receptor Agonists; Receptors, Purinergic P2; Thapsigargin; Thionucleotides; Tumor Cells, Cultured; Uridine Triphosphate

Sphingosine (10 microM) induced mobilization of intracellular Ca2+ stores in the pancreatic duct adenocarcinoma cell line CFPAC-1. The effect was specific for sphingosine, since the sphingosine analog C2-ceramide had no effect. Sphingosine did not cause Ca2+ entry from extracellular medium, as also shown by following Mn2+ quenching of Fura-2 fluorescence. Furthermore, sphingosine, similarly to the mitochondrial inhibitors rotenone and oligomycin, strongly inhibited the rate of Mn2+ entry triggered by both thapsigargin- and agonist-induced depletion of intracellular stores. The uptake of rhodamine 123, a lipophilic cation which estimates mitochondrial energy level, was reduced by sphingosine to an extent similar to that observed in the presence of mitochondrial inhibitors. It is suggested that impairment of mitochondrial function might be responsible for inhibition of capacitative Ca2+ entry caused by sphingosine.

Topics: Adenocarcinoma; Biological Transport; Calcium; Enzyme Inhibitors; Fluorescent Dyes; Fura-2; Humans; Manganese; Membrane Potentials; Mitochondria; Oligomycins; Pancreatic Ducts; Pancreatic Neoplasms; Propidium; Rhodamine 123; Rhodamines; Rotenone; Sphingosine; Thapsigargin; Tumor Cells, Cultured; Uncoupling Agents; Uridine Diphosphate

We have examined the effects of protein kinase-C (PKC) activation on expression of the six known insulin-like growth factor-binding proteins (IGFBPs) by human endometrial carcinoma cells. Each of six known IGFBPs was expressed in one or more of the three cell lines examined. The addition of 10(-7) M 4 beta-phorbol 12-myristate 13-acetate (PMA) to HEC-50 and HEC-1B cells resulted in changes in cell morphology, growth inhibition, activation of PKC, and an increase in expression of IGFBP-1. PMA had no effect on these parameters in the Ishikawa cell line, which did not express IGFBP-1. In HEC-50 cells, the effect of PMA was blocked by the concomitant addition of the PKC inhibitor staurosporin and the simultaneous addition of cycloheximide. PMA also resulted in an increase in IGFBP-3 in HEC-50 cells and an increase in IGFBP-6 expression in HEC-1B cells. In contrast, IGFBP-3 expression was down-regulated by PMA in HEC-1B and Ishikawa cells. The abundance of IGFBP-2 and IGFBP-5 mRNAs was also reduced in HEC-1B and Ishikawa cells, respectively. IGFBP-4 was expressed only in HEC-50 cells and was not affected by PMA treatment. These data establish a role for the PKC pathway in regulation of expression of IGFBP-1, -2, -3, and -5 in endometrial adenocarcinoma cells and illustrate the complexity of cell type-specific expression of the IGFBPs.

Topics: Adenocarcinoma; Alkaloids; Blotting, Northern; Calcimycin; Carrier Proteins; Cell Division; Cycloheximide; Endometrial Neoplasms; Enzyme Activation; Female; Gene Expression Regulation; Humans; Insulin-Like Growth Factor Binding Proteins; Kinetics; Protein Kinase C; RNA, Messenger; Staurosporine; Terpenes; Tetradecanoylphorbol Acetate; Thapsigargin; Tumor Cells, Cultured

Calcyclin is a member of the S-100 family of calcium-binding proteins, whose expression is enhanced when quiescent cells are exposed to mitogenic signals. The function of calcyclin is unknown, but it is thought to be involved in modulating the intracellular calcium concentration following mitogenic stimuli. Since activation of protein kinase C (PKC) also occurs following stimulation of quiescent cells by a variety of mitogens, we have investigated the relationship between calcyclin expression and PKC activation in three human endometrial adenocarcinoma cell lines. The addition of 10(-7) M 4 beta-phorbol 12-myristate 13-acetate (PMA) to HEC-50 and HEC-1B cell cultures resulted in a change in cell morphology, an inhibition of proliferation, an increase in calcyclin transcription rate, and an increase in calcyclin mRNA and calcyclin protein levels. In contrast, PMA had no effect on cell morphology or cell proliferation in the Ishikawa adenocarcinoma cell line but enhanced calcyclin expression. Another bioactive phorbol ester had the same effect, whereas the calcium ionophore A23187 and the non-phorbol-ester-type tumor promoter thapsigargin had no effect on calcyclin expression. The effect of PMA on calcyclin expression was blocked by the simultaneous addition of the PKC inhibitor staurosporine and by protein synthesis inhibition with cycloheximide. RNase protection assays and primer extension analysis demonstrated that PMA enhanced transcription from all three of the previously identified transcription start sites in the calcyclin gene. These data clearly demonstrate a dissociation between calcyclin expression and cellular proliferation and suggest that the enhanced calcyclin expression which is seen in quiescent cells following mitogenic stimuli may result from activation of the PKC system.

Topics: Adenocarcinoma; Alkaloids; Calcimycin; Calcium-Binding Proteins; Cell Cycle Proteins; Cell Division; Cycloheximide; Enzyme Activation; Female; Gene Expression Regulation, Neoplastic; Humans; Neoplasm Proteins; Phorbol 12,13-Dibutyrate; Phorbol Esters; Protein Kinase C; RNA, Messenger; RNA, Neoplasm; S100 Calcium Binding Protein A6; S100 Proteins; Signal Transduction; Staurosporine; Terpenes; Tetradecanoylphorbol Acetate; Thapsigargin; Uterine Neoplasms

1. Thapsigargin, a sesquiterpene lactone, was shown to cause electrogenic anion secretion in monolayers of human colonic epithelial cells, an effect which was crucially dependent upon calcium and did not involve eicosanoid formation. 2. To measure the secretory effect calcium needed to be present in the external bathing solution. By means of Fura-2 fluorescence measurements thapsigargin was shown to raise Cai by around 250 nM when the bathing solution contained calcium. In the nominal absence of external calcium thapsigargin raised Cai by only 60 nM, but from a lower basal value. This was insufficient to cause secretion. 3. Effects of other calcium-dependent secretagogues (e.g. lysylbradykinin) were inhibited in the presence of thapsigargin, whereas kinin responses were potentiated if the peptide was added following a stimulus which increases cyclic AMP. 4. From the data given here and the known behaviour of colonic epithelia it is concluded that thapsigargin increases Cai by a non-ionophoric mechanism by release from internal stores. Calcium-stimulated calcium influx then follows resulting in the opening of basolateral K channels, increasing the electrochemical gradient for chloride efflux, or alternatively by activating anion channels in the apical membrane. It is concluded that thapsigargin is a potentially important tool for examining epithelial mechanisms.

Topics: Adenocarcinoma; Anions; Calcimycin; Calcium; Colforsin; Colonic Neoplasms; Electrophysiology; Epithelium; Humans; Plant Extracts; Thapsigargin; Tumor Cells, Cultured