u-0126 and Pancreatic-Neoplasms

Molecular-targeted therapy has shown its effectiveness in pancreatic cancer, while single-targeted drug often cannot provide long-term benefit because of drug resistance. Fortunately, multitarget combination therapy can reverse drug resistance and achieve better efficacy. The typical treatment characteristics of traditional Chinese medicine monomer on tumor are multiple targets, with small side effects, low toxicity, and so forth. Agrimoniin has been reported to be effective on some cancers, while the mechanism still needs to be clarified. In this study, we used 5-ethynyl-2'-deoxyuridine, cell counting kit-8, flow cytometry, and western blot experiments to confirm that agrimoniin can significantly inhibit the proliferation of pancreatic cancer cell PANC-1 by inducing apoptosis and cell cycle arrest. In addition, by using SC79, LY294002 (the agonist or inhibitor of AKT pathway), and U0126 (the inhibitor of ERK pathway), we found that agrimoniin inhibited cell proliferation by simultaneously inhibiting AKT and ERK pathways. Moreover, agrimoniin could significantly increase the inhibitory effect of LY294002 and U0126 on pancreatic cancer cells. Meanwhile, in vivo experiments also supported the above results. In general, agrimoniin is a double-target inhibitor of AKT and ERK pathways in pancreatic cancer cells; it is expected to be used as a resistance reversal agent of targeted drugs or a synergistic drug of the inhibitor of AKT pathway or ERK pathway.

Topics: Apoptosis; Cell Line, Tumor; Cell Proliferation; Humans; MAP Kinase Signaling System; Pancreatic Neoplasms; Proto-Oncogene Proteins c-akt

Toxicants can perturb cellular homeostasis by modifying phosphorylation-based signaling. In the present study, we examined the effects of cerulein, an inducer of acute pancreatitis, on keratin 8 (K8) phosphorylation. We found that cerulein dose-dependently induced K8 phosphorylation and perinuclear reorganization in PANC-1 cells, thus leading to migration and invasion. The extracellular signal-regulated kinases (ERK) inhibitor U0126 suppressed cerulein-induced phosphorylation of serine 431 and reorganization of K8. Cerulein reduced the expressions of protein phosphatase 2A (PP2A) via ubiqutination and alpha4. PP2A's involvement in K8 phosphorylation of PANC-1 cells was also confirmed by the observation that PP2A gene silencing resulted in K8 phosphorylation and migration of PANC-1 cells. Overall, these results suggest that cerulein induced phosphorylation and reorganization through ERK activation by downregulating PP2A and alpha4, leading to increased migration and invasion of PANC-1 cells. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 2090-2098, 2016.

Topics: Butadienes; Cell Line, Tumor; Cell Movement; Ceruletide; Down-Regulation; Extracellular Signal-Regulated MAP Kinases; Humans; Keratin-8; Nitriles; Pancreatic Neoplasms; Phosphorylation; Protein Phosphatase 2; Serine; Signal Transduction

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive disease with a survival rate of 4-6 months from diagnosis. PDAC is the fourth leading cause of cancer-related death in the Western world, with a mortality rate of 10 cases per 100,000 population. Chemotherapy constitutes only a palliative strategy, with limited effects on life expectancy.. To investigate the biological response of PDAC to mitogen-activated protein kinase (MAPK) and NF-kappaB (NF-kB) inhibitors and the role of autophagy in the modulation of these signaling pathways in order to address the challenge of developing improved medical protocols for patients with PDAC.. Two ATCC cell lines, MIAPaCa-2 and PANC-1, were used as PDAC models. Cells were exposed to inhibitors of MAPK or NF-kB survival pathways alone or after autophagy inhibition. Several aspects were analyzed, as follows: cell proliferation, by [(3)H]TdR incorporation; cell death, by TUNEL assay, regulation of autophagy by LC3-II expression level and modulation of pro-and anti-apoptotic proteins by Western blot.. We demonstrated that the inhibition of the MAPK and NF-kB survival pathways with U0126 and caffeic acid phenethyl ester (CAPE), respectively, produced strong inhibition of pancreatic tumor cell growth without inducing apoptotic death. Interestingly, U0126 and CAPE induced apoptosis after autophagy inhibition in a caspase-dependent manner in MIA PaCa-2 cells and in a caspase-independent manner in PANC-1 cells.. Here we present evidence that allows us to consider a combined therapy regimen comprising an autophagy inhibitor and a MAPK or NF-kB pathway inhibitor as a possible treatment strategy for pancreatic cancer.

Topics: Antineoplastic Agents; Apoptosis; Autophagy; Butadienes; Caffeic Acids; Carcinoma, Pancreatic Ductal; Cell Growth Processes; Cell Line, Tumor; Humans; MAP Kinase Signaling System; Mitogen-Activated Protein Kinase Kinases; NF-kappa B; Nitriles; Pancreatic Neoplasms; Phenylethyl Alcohol; Protein Kinase Inhibitors; Survival Rate

Oleanolic acid (OA) is a natural triterpenoid that is widely distributed in edible and medicinal plants. OA exerts anti-tumor activity on a wide range of cancer cells primarily through inducing apoptosis. Dysregulated ERK signaling is closely complicated in the biology of cancer, such as metastasis, proliferation, and survival, and it can be activated by various stimuli. In this study, we found that OA induced the activation of ERK in cancer cells. ERK activation compromised the apoptosis induced by OA. Blocking ERK activation by U0126 or siRNAs was able to potentiate the pro-apoptotic activity of OA on cancer cells. OA was shown to promote ERK-dependent Nrf2 expression in cancer cells, and in turn, Nrf2 expression was able to suppress OA-induced ROS generation. Blockade of Nrf2 expression was able to increase ROS levels and apoptotic death in cancer cells. In conclusion, we provided evidences that ERK activation is a mechanism underlying the resistance of cancer cells to OA-induced apoptosis and targeting ERK is a promising strategy to enhance the anti-tumor efficacy of OA.

Topics: Animals; Apoptosis; Blotting, Western; Butadienes; Cell Proliferation; Drug Resistance, Neoplasm; Enzyme Inhibitors; Extracellular Signal-Regulated MAP Kinases; Gene Expression Regulation, Neoplastic; Humans; Lung Neoplasms; Male; Mice; Mice, Inbred BALB C; Mice, Nude; NF-E2-Related Factor 2; Nitriles; Oleanolic Acid; Pancreatic Neoplasms; Reactive Oxygen Species; Signal Transduction; Tumor Cells, Cultured; Xenograft Model Antitumor Assays

Although the translational function of tRNA has long been established, extra translational functions of tRNA are still being discovered. We previously developed a computational method to systematically predict new tRNA-protein complexes and experimentally validated six candidate proteins, including the mitogen-activated protein kinase kinase 2 (MEK2), that interact with tRNA in HEK293T cells. However, consequences of the interaction between tRNA and these proteins remain to be elucidated. Here we tested the consequence of the interaction between tRNA and MEK2 in pancreatic cancer cell lines. We also generated disease and drug resistance-derived MEK2 mutants (Q60P, P128Q, S154F, E207K) to evaluate the function of the tRNA-MEK2 interaction. Our results demonstrate that tRNA interacts with the wild-type and mutant MEK2 in pancreatic cancer cells; furthermore, the MEK2 inhibitor U0126 significantly reduces the tRNA-MEK2 interaction. In addition, tRNA affects the catalytic activity of the wild type and mutant MEK2 proteins in different ways. Overall, our findings demonstrate the interaction of tRNA with MEK2 in pancreatic cancer cells and suggest that tRNA may impact MEK2 activity in cancer cells.

Topics: Butadienes; Cell Line, Tumor; HEK293 Cells; Humans; MAP Kinase Kinase 2; Mutation; Nitriles; Pancreatic Neoplasms; RNA, Transfer

Pancreatic cancer is one of the most aggressive human cancers, and the pharmaceutical outcomes for its treatment remain disappointing. Proper animal models will provide an efficient platform for investigating novel drugs, and the zebrafish has become one of the most promising and comprehensive model animal in cancer research. In the present study, we used a novel xenograft model in zebrafish by transplanting human pancreatic cancer cells to study the progression and metastasis of pancreatic cancer cells and to assay the pharmacological effects of new drug U0126 in vivo. We first established a primary xenograft model of pancreatic cancer by injecting human pancreatic cancer cells into both live larval and adult zebrafish, and then investigated the behaviors of CM-DiI‑labeled human pancreatic cancer cells. Subsequently, we tested the potential of this model for drug screening by evaluating a known small-molecule inhibitor, U0126, which targets the KRAS signaling pathway. Cells with KRAS mutations exhibited significant proliferative and migratory behaviors and invaded the zebrafish vasculature system. In contrast, the proliferation and migration of Mia PaCa-2 cells in zebrafish larvae were substantially repressed following U0126 treatment. These results suggest that zebrafish xenotransplantation can be used as a simple and efficient tool to screen and identify new anti-pancreatic cancer compounds.

Topics: Animals; Antineoplastic Agents; Butadienes; Cell Line, Tumor; Gene Expression Regulation, Neoplastic; Humans; Nitriles; Pancreatic Neoplasms; Proto-Oncogene Proteins p21(ras); Signal Transduction; Xenograft Model Antitumor Assays; Zebrafish; Zebrafish Proteins

The prognosis of pancreatic cancer is dismal due to the frequent metastasis and invasion to surrounding organs. Numerous molecules are involved in the malignant behavior of pancreatic cancer cells, but the entire process remains unclear. Several reports have suggested that CUB-domain containing protein-1 (CDCP1) is highly expressed in pancreatic cancer, but its impact on the invasive growth and the upstream regulator remain elusive. To clarify the role of CDCP1 in pancreatic cancer, we here examined the effects of CDCP1 knockdown on the cell behaviors of pancreatic cancer cells. Knockdown of CDCP1 expression in Panc-1 resulted in reduced cellular migration accompanied by the increased expression of E-cadherin and decreased expression of N-cadherin. Knockdown of CDCP1 attenuated the spheroid formation and resistance against gemcitabine, which are some of the cancer stem cell-related phenotypes. Bone morphogenetic protein 4 (BMP4) was found to induce CDCP1 expression via the extracellular signal regulated kinase pathway, suggesting that CDCP1 has a substantial role in the BMP4-induced epithelial-mesenchymal transition. These results indicate that CDCP1 represses the epithelial phenotype of pancreatic cancer cells.

Topics: Antigens, CD; Antigens, Neoplasm; Bone Morphogenetic Protein 4; Butadienes; Cell Adhesion Molecules; Down-Regulation; Epithelial Cells; Epithelial-Mesenchymal Transition; Gene Expression Regulation, Neoplastic; Gene Knockdown Techniques; Humans; Neoplasm Proteins; Nitriles; Pancreatic Neoplasms; Phenotype; RNA, Small Interfering; Tumor Cells, Cultured

Tumor cells require increased adenosine triphosphate (ATP) to support anabolism and proliferation. The precise mechanisms regulating this process in tumor cells are unknown. Here, we show that the receptor for advanced glycation endproducts (RAGE) and one of its primary ligands, high-mobility group box 1 (HMGB1), are required for optimal mitochondrial function within tumors. We found that RAGE is present in the mitochondria of cultured tumor cells as well as primary tumors. RAGE and HMGB1 coordinately enhanced tumor cell mitochondrial complex I activity, ATP production, tumor cell proliferation and migration. Lack of RAGE or inhibition of HMGB1 release diminished ATP production and slowed tumor growth in vitro and in vivo. These findings link, for the first time, the HMGB1-RAGE pathway with changes in bioenergetics. Moreover, our observations provide a novel mechanism within the tumor microenvironment by which necrosis and inflammation promote tumor progression.

Topics: Adenosine Triphosphate; Animals; Butadienes; CD24 Antigen; Cell Line, Tumor; Cell Movement; Cell Proliferation; Cycloheximide; Electron Transport Complex I; Energy Metabolism; Enzyme Inhibitors; Extracellular Signal-Regulated MAP Kinases; HMGB1 Protein; Humans; Inflammation; MAP Kinase Kinase 2; Mice; Mitochondria; NF-kappa B; Nitriles; Pancreatic Neoplasms; Phosphorylation; Protein Binding; Protein Synthesis Inhibitors; Receptor for Advanced Glycation End Products; RNA Interference; RNA, Small Interfering; Rotenone; Signal Transduction; Toll-Like Receptor 2; Toll-Like Receptor 4; Tumor Microenvironment; Uncoupling Agents

Pancreatic ductal adenocarcinoma (PDAC) commonly contains a mutation in K-Ras(G12D) and is characterized by a desmoplastic reaction composed of deregulated, proliferating cells embedded in an abnormal extracellular matrix (ECM). Our previous observations imply that inhibiting the mitogen-activated protein kinase (MAPK)-extracellular signal-regulated kinase (ERK2) kinase signal pathway reverses a matrix metalloproteinase 1-specific invasive phenotype. Here, we investigated the specific genes downstream of MAPK-ERK2 responsible for the hyperproliferative abilities of human and murine primary ductal epithelial cells (PDCs) within an ECM. Compared with control, DNA synthesis and total cell proliferation was significantly increased in human PDCs harboring the PDAC common p53, Rb/p16(INK4a), and K-Ras (G12D) mutations. Both of these effects were readily reversed following small-molecule inhibition or lentiviral silencing of ERK2. Microarray analysis of PDCs in three-dimensional (3D) culture revealed a unique, MAPK-influenced gene signature downstream of K-Ras (G12D). Unbiased hierarchical analysis permitted filtration of tissue inhibitor of matrix metalloproteinase 1 (TIMP1). Pancreatic cells isolated from Pdx1-Cre; LSL-K-ras(G12D/+)-mutated mice exhibit increased TIMP1 RNA transcription compared to wild-type littermate controls. Analyses of both 3D, in vitro human K-Ras (G12D) PDCs and data mining of publicly annotated human pancreatic data sets correlatively indicate increased levels of TIMP1 RNA. While silencing TIMP1 did not significantly effect PDC proliferation, exogenous addition of human recombinant TIMP1 significantly increased proliferation but only in transformed K-Ras (G12D) PDCs in 3D. Overall, TIMP1 is an upregulated gene product and a proliferative inducer of K-Ras(G12D)-mutated PDCs through the ERK2 signaling pathway.

Topics: Animals; Butadienes; Carcinoma, Pancreatic Ductal; Cell Line, Tumor; Cell Proliferation; Epithelial Cells; Gene Expression Regulation, Neoplastic; Gene Knockdown Techniques; Humans; MAP Kinase Signaling System; Mice; Mice, Transgenic; Mitogen-Activated Protein Kinase 1; Mutation, Missense; Nitriles; Oligonucleotide Array Sequence Analysis; Pancreatic Ducts; Pancreatic Neoplasms; Proto-Oncogene Proteins; Proto-Oncogene Proteins p21(ras); ras Proteins; RNA, Small Interfering; Tissue Inhibitor of Metalloproteinase-1; Transcriptome

To test the hypothesis that chemoresistance in pancreatic cancer is mediated via extracellular signal-regulated protein kinase (ERK) 1/2 overactivity.. The human pancreatic cancer cell lines BxPC3, PANC-1 and a stably gemcitabine-resistant subline, PANC1(GemRes), were treated with combinations of gemcitabine and the ERK1/2 inhibitor, U0126. Phosphorylated (p)ERK1/2 was examined by Western blotting; cell proliferation and apoptosis were quantified. A nude mouse xenograft model was established with each cell line, and the therapeutic efficacy of gemcitabine and U0126 alone or in combination was examined.. Gemcitabine treatment visibly increased pERK1/2 levels in BxPC-3 and PANC-1 cells. PANC-1(GemRes) constitutively produced high levels of pERK1/2. U0126 treatment reversed the gemcitabine-associated increase in cell proliferation and reduction in apoptosis, in all three cell lines. Combination treatment with U0126 and gemcitabine inhibited tumour growth and promoted apoptosis in xenograft tumours derived from all three cell lines.. ERK1/2 activity may protect pancreatic cancer cells from chemotherapy-induced apoptosis. The combined use of an ERK1/2 inhibitor (such as U0126) together with gemcitabine may result in synergistic therapeutic effects at tolerable gemcitabine doses.

Topics: Adenocarcinoma; Animals; Apoptosis; Blotting, Western; Butadienes; Cell Line, Tumor; Deoxycytidine; Drug Resistance, Neoplasm; Extracellular Signal-Regulated MAP Kinases; Gemcitabine; Humans; Inhibitory Concentration 50; Mice; Nitriles; Pancreatic Neoplasms; Phosphorylation; Protein Kinase Inhibitors; Tumor Burden

Small non-coding RNAs, microRNAs (miRNA), inhibit the translation or accelerate the degradation of message RNA (mRNA) by targeting the 3'-untranslated region (3'-UTR) in regulating growth and survival through gene suppression. Deregulated miRNA expression contributes to disease progression in several cancers types, including pancreatic cancers (PaCa). PaCa tissues and cells exhibit decreased miRNA, elevated cyclooxygenase (COX)-2 and increased prostaglandin E2 (PGE2) resulting in increased cancer growth and metastases. Human PaCa cell lines were used to demonstrate that restoration of miRNA-143 (miR-143) regulates COX-2 and inhibits cell proliferation. miR-143 were detected at fold levels of 0.41 ± 0.06 in AsPC-1, 0.20 ± 0.05 in Capan-2 and 0.10 ± 0.02 in MIA PaCa-2. miR-143 was not detected in BxPC-3, HPAF-II and Panc-1 which correlated with elevated mitogen-activated kinase (MAPK) and MAPK kinase (MEK) activation. Treatment with 10 μM of MEK inhibitor U0126 or PD98059 increased miR-143, respectively, by 187 ± 18 and 152 ± 26-fold in BxPC-3 and 182 ± 7 and 136 ± 9-fold in HPAF-II. miR-143 transfection diminished COX-2 mRNA stability at 60 min by 2.6 ± 0.3-fold in BxPC-3 and 2.5 ± 0.2-fold in HPAF-II. COX-2 expression and cellular proliferation in BxPC-3 and HPAF-II inversely correlated with increasing miR-143. PGE2 levels decreased by 39.3 ± 5.0% in BxPC-3 and 48.0 ± 3.0% in HPAF-II transfected with miR-143. Restoration of miR-143 in PaCa cells suppressed of COX-2, PGE2, cellular proliferation and MEK/MAPK activation, implicating this pathway in regulating miR-143 expression.

Topics: Butadienes; Cell Line, Tumor; Cell Proliferation; Cyclooxygenase 2; Dinoprostone; DNA-Binding Proteins; Enzyme Inhibitors; Flavonoids; Gene Expression Regulation, Neoplastic; Humans; MAP Kinase Kinase Kinases; MicroRNAs; Nitriles; p38 Mitogen-Activated Protein Kinases; Pancreatic Neoplasms; RNA Stability; RNA, Messenger; Signal Transduction; Time Factors; Transcription Factors

Here we explore the effect of grape seed proanthocyanidins (GSPs) on pancreatic cancer cell migration and the molecular mechanisms underlying these effects. Treatment of human pancreatic cancer cell lines Miapaca-2, PANC-1 and AsPC-1 with GSPs resulted in inhibition of cell migration (19-82%, P<0.01-0.001), which was associated with decreased phosphorylation of ERK1/2 and inactivation of NF-κB. Treatment of cells with UO126, an inhibitor of MEK, and caffeic acid phenethyl ester, an inhibitor of NF-κB, also inhibited the migration of cells (40-80%, P<0.01-0.001). Inhibition of cell migration by GSPs was associated with reversal of the epithelial-to-mesenchymal transition. This was associated with upregulation of E-cadherin and desmoglein-2 and down-regulation of fibronectin, N-cadherin and vimentin.

Topics: Antineoplastic Agents, Phytogenic; Butadienes; Cell Line, Tumor; Cell Movement; Enzyme Inhibitors; Epithelial-Mesenchymal Transition; Grape Seed Extract; Humans; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; NF-kappa B; Nitriles; Pancreatic Neoplasms; Phosphorylation; Proanthocyanidins

Protein kinase Cα (PKCα) is highly expressed in pancreatic cancer. However, the effects of PKCα on Snail and claudin-1, which play crucial roles in epithelial cell polarity during epithelial-mesenchymal transition (EMT), remain unclear. In this study, we investigated the mechanisms of regulation of Snail and claudin-1 via a PKCα signal pathway during EMT in pancreatic cancer cells and in normal human pancreatic duct epithelial cells (HPDEs). By immunostaining, overexpression of PKCα and downregulation of claudin-1 were observed in poorly differentiated human pancreatic cancer tissues and the pancreatic cancer cell line PANC-1. Treatment with the PKCα inhibitor Gö6976 transcriptionally decreased Snail and increased claudin-1 in PANC-1 cells. The PKCα inhibitor prevented upregulation of Snail and downregulation of claudin-1 during EMT induced by transforming growth factor-β1 (TGF-β1) treatment and under hypoxia in PANC-1 cells. The effects of the PKCα inhibitor were in part regulated via an extracellular signal-regulated kinase (ERK) signaling pathway. The PKCα inhibitor also prevented downregulation of the barrier function and fence function during EMT in well-differentiated pancreatic cancer cell line HPAC. In normal HPDEs, the PKCα inhibitor transcriptionally induced not only claudin-1 but also claudin-4, -7 and occludin without a change of Snail. Treatment with the PKCα inhibitor in normal HPDEs prevented downregulation of claudin-1 and occludin by TGF-β1 treatment and enhanced upregulation of claudin-1, -4, -7 and occludin under hypoxia. These findings suggest that PKCα regulates claudin-1 via Snail- and mitogen-activated protein kinase/ERK-dependent pathways during EMT in pancreatic cancer. Thus, PKCα inhibitors may be potential therapeutic agents against the malignancy of human pancreatic cancer cells.

Topics: Butadienes; Carbazoles; Cell Hypoxia; Cell Line, Tumor; Claudin-1; Claudin-4; Claudins; Down-Regulation; Enzyme Inhibitors; Epithelial Cells; Epithelial-Mesenchymal Transition; Extracellular Signal-Regulated MAP Kinases; Humans; Nitriles; Occludin; Pancreatic Ducts; Pancreatic Neoplasms; Protein Biosynthesis; Protein Kinase C-alpha; RNA Interference; RNA, Small Interfering; Signal Transduction; Snail Family Transcription Factors; Transcription Factors; Transforming Growth Factor beta1; Up-Regulation

Aberrant expression of microRNAs (miRNA) is associated with phenotypes of various cancers, including pancreatic cancer. However, the mechanism of the aberrant expression is largely unknown. Activation of the mitogen-activated protein kinase (MAPK) signaling pathway plays a crucial role in gene expression related to the malignant phenotype of pancreatic cancer. Hence, we studied the role of MAPK in the aberrant expression of miRNAs in pancreatic cancer cells. The alterations in expression of 183 miRNAs induced by activation or inactivation of MAPK were assayed in cultured pancreatic cancer cells and HEK293 cells by means of the quantitative real-time PCR method. We found that four miRNAs, namely, miR-7-3, miR-34a, miR-181d, and miR-193b, were preferentially associated with MAPK activity. Among these miRNAs, miR-7-3 was upregulated by active MAPK, whereas the others were downregulated. Promoter assays indicated that the promoter activities of the host genes of miR-7-3 and miR-34a were both downregulated by alteration in MAPK activity. Exogenous overexpression of the MAPK-associated miRNAs had the effect of inhibition of the proliferation of cultured pancreatic cancer cells; miR-193b was found to exhibit the most remarkable inhibition. A search for target genes of miR-193b led to identification of CCND1, NT5E, PLAU, STARD7, STMN1, and YWHAZ as the targets. Translational suppression of these genes by miR-193b was confirmed by reporter assay. These results indicate that activation of MAPK may play a significant role in aberrant expression of miRNAs and their associated phenotypes in pancreatic cancer.

Topics: Butadienes; Cell Line, Tumor; Cell Proliferation; Gene Expression Regulation, Neoplastic; HEK293 Cells; Humans; MAP Kinase Signaling System; MicroRNAs; Mitogen-Activated Protein Kinase Kinases; Nitriles; Pancreatic Neoplasms; Promoter Regions, Genetic; Signal Transduction; Transcriptional Activation

The objectives of the present study were (i) to identify a novel tumor suppressor gene whose expression level was regulated by transforming growth factor (TGF-β) and (ii) to evaluate the effect of Ras/MEK/ERK signaling on TGF-β-dependent Lefty up-regulation.. Human pancreatic cancer cell lines were used. The effect of Ras/MEK/ERK pathway on TGF-β-mediated Lefty up-regulation was tested by adding K-ras small interfering RNA, MEK inhibitor U0126, or extracellular signal-regulated kinase (ERK) inhibitor LY294002.. Transforming growth factor β upregulated Lefty messenger RNA levels within 6 of the 7 cell lines. Lefty exerts an antagonistic effect against the tumor-promoting molecule, Nodal, as recombinant Lefty suppressed Nodal-mediated proliferation. Interestingly, inhibition of the Ras/MEK/ERK pathway dramatically enhanced TGF-mediated Lefty up-regulation, suggesting that Ras/MEK/ERK signaling suppresses TGF-β-Lefty pathway.. Our data suggest that Lefty is a novel TGF-β target molecule that mediates growth inhibition of pancreatic cancer cells. In addition, activation of the Ras/MEK/ERK pathway serves as a mechanism by which pancreatic cancer escapes from growth inhibition by the TGF-β-Lefty axis. The results imply a novel therapeutic strategy for pancreatic cancer, that is, combination treatment with Ras/MEK/ERK inhibitors and TGF-β.

Topics: Butadienes; Cell Line, Tumor; Cell Proliferation; Chromones; Extracellular Signal-Regulated MAP Kinases; Gene Expression Regulation, Neoplastic; Humans; Immunoblotting; Immunohistochemistry; Left-Right Determination Factors; MAP Kinase Signaling System; Mitogen-Activated Protein Kinases; Morpholines; Nitriles; Oligonucleotide Array Sequence Analysis; Pancreatic Neoplasms; Pyrazoles; Pyridazines; ras Proteins; Reverse Transcriptase Polymerase Chain Reaction; RNA Interference; Transforming Growth Factor beta; Tumor Suppressor Proteins; Up-Regulation

Aquaporin (AQP) water channels are expressed in high-grade tumor cells of different tissue origins. In this study, we investigated whether AQP3 is expressed in cultured MPC-83 pancreatic cancer cells, whether AQP3 enhances cell migration and the signal pathway mechanism involved. MPC-83 pancreatic cancer cells were pre-treated and treated with EGF at different time points and then analyzed using western blotting. Results showed that epidermal growth factor (EGF) induced the phosphorylation of the EGF receptor (EGFR) and extracellular signal-regulated kinase (ERK), which peaked at 5 min after EGF treatment. EGFR and ERK phosphorylation induced by EGF were inhibited by PD153035 (EGFR tyrosine kinase inhibitor) and U0126 (ERK inhibitor), respectively. EGF increased the activity of AQP3 in a dose- and time-dependent manner in MPC-83 pancreatic cancer cells, which peaked at 24 h after treatment. The activity of AQP3 and cell migration were inhibited by PD153035, U0126 and CuSO4 (AQP3 water transport inhibitor). EGFR/ERK pathway-mediated AQP3 activation and cell migration were stimulated by EGF in cultured MPC-83 pancreatic cancer cells in vitro and this cell signaling pathway is inhibited by the EGFR and ERK inhibitors, which may be used as potential therapeutic targets in the treatment of pancreatic cancer.

Topics: Antineoplastic Agents; Aquaporin 3; Butadienes; Cell Line, Tumor; Cell Movement; Enzyme Inhibitors; Epidermal Growth Factor; ErbB Receptors; Extracellular Signal-Regulated MAP Kinases; Humans; Nitriles; Pancreatic Neoplasms; Phosphorylation; Quinazolines; Up-Regulation

MUC1 is overexpressed and aberrantly glycosylated in more than 60% of pancreatic ductal adenocarcinomas. The functional role of MUC1 in pancreatic cancer has yet to be fully elucidated due to a dearth of appropriate models. In this study, we have generated mouse models that spontaneously develop pancreatic ductal adenocarcinoma (KC), which are either Muc1-null (KCKO) or express human MUC1 (KCM). We show that KCKO mice have significantly slower tumor progression and rates of secondary metastasis, compared with both KC and KCM. Cell lines derived from KCKO tumors have significantly less tumorigenic capacity compared with cells from KCM tumors. Therefore, mice with KCKO tumors had a significant survival benefit compared with mice with KCM tumors. In vitro, KCKO cells have reduced proliferation and invasion and failed to respond to epidermal growth factor, platelet-derived growth factor, or matrix metalloproteinase 9. Further, significantly less KCKO cells entered the G(2)-M phase of the cell cycle compared with the KCM cells. Proteomics and Western blotting analysis revealed a complete loss of cdc-25c expression, phosphorylation of mitogen-activated protein kinase (MAPK), as well as a significant decrease in nestin and tubulin-α2 chain expression in KCKO cells. Treatment with a MEK1/2 inhibitor, U0126, abrogated the enhanced proliferation of the KCM cells but had minimal effect on KCKO cells, suggesting that MUC1 is necessary for MAPK activity and oncogenic signaling. This is the first study to utilize a Muc1-null PDA mouse to fully elucidate the oncogenic role of MUC1, both in vivo and in vitro.

Topics: Animals; Butadienes; Carcinoma, Pancreatic Ductal; Cell Cycle; Cell Growth Processes; Epidermal Growth Factor; Humans; Intermediate Filament Proteins; Matrix Metalloproteinase 9; Mice; Mice, Inbred C57BL; Mice, Knockout; Mitogen-Activated Protein Kinases; Mucin-1; Neoplasm Metastasis; Nerve Tissue Proteins; Nestin; Nitriles; Pancreatic Neoplasms; Platelet-Derived Growth Factor; Protein Kinase Inhibitors; Tubulin

Gemcitabine is currently the leading therapeutic for pancreatic cancer treatment, despite growing resistance. Studying the mechanisms that underlie gemcitabine resistance and discovery of agents that increase the tumour sensitivity to gemcitabine, is therefore desirable. The thalidomide analogue lenalidomide has been approved for use in multiple myeloma in combination with dexamethasone. Although it is primarily immunomodulatory, it also has direct effects on tumours. We investigated the sensitivity of three pancreatic cell lines PANC-1, MIA-PaCa-2 and BxPC-3 to gemcitabine. We observed that PANC-1 cells display most resistance to gemcitabine and MIA-PaCa-2 are most sensitive. Western blot analysis revealed that PANC-1 exhibits high phosphorylated extracellular signal-regulated kinase (pERK) expression, whereas MIA-PaCa-2 displays low expression. Combining gemcitabine and lenalidomide reduced the IC(50) of gemcitabine up to 40% (p<0.05). Western blot analysis showed lenalidomide significantly reduced pERK expression in all cell lines (p<0.05). It was hypothesised that gemcitabine sensitivity could be increased through combination with a pERK-reducing agent. The mitogen-activated kinase (MEK) specific inhibitor U0126 was used on PANC-1 cells to restore gemcitabine sensitivity. U0126 significantly increased cell killing by gemcitabine from 30% to 60% (p<0.001). Sensitive MIA-PaCa-2 cells were transfected with a constitutively active MEK mutant to reduce gemcitabine sensitivity. Transfection resulted in a significant reduction in cell killing by gemcitabine from 54-16% (p<0.05). These results provide evidence that ERK activity underlies sensitivity to gemcitabine and that addition of an agent that reduces this activity, such as lenalidomide, enhances gemcitabine efficacy. In conclusion, these results provide an understanding of gemcitabine resistance and could be used to predict successful combination therapies.

Topics: Antimetabolites, Antineoplastic; Antineoplastic Agents; Apoptosis; Blotting, Western; Butadienes; Deoxycytidine; Drug Resistance, Neoplasm; Drug Synergism; Enzyme Inhibitors; Extracellular Signal-Regulated MAP Kinases; Gemcitabine; Humans; Lenalidomide; Nitriles; Pancreatic Neoplasms; Phosphorylation; Thalidomide; Tumor Cells, Cultured

We previously detected CXCR4 expression in pancreatic intraepithelial neoplasia (PanIN) tissues and demonstrated CXCR4-enhanced proliferation of PanIN cells. Our objective was to determine if the CXCR4 targets AKT and ERK mediate CXCR4-dependent PanIN and pancreatic cancer proliferation.. We exposed cultured murine-derived PanIN, invasive pancreatic cancer (5143PDA) and liver metastasis (5143LM) cells, and human pancreatic cancer PANC-1 cells to CXCL12, the specific CXCR4 ligand, and measured phosphorylation of AKT and ERK1/2. The roles of AKT and ERK1/2 in CXCR4-dependent cell proliferation were assessed by the PI/3K-AKT small molecular inhibitor LY294002 and the ERK signaling inhibitor UO126.. We discovered increases in phosphorylation of AKT in PanIN, 5143PDA, and PANC-1 cells but no increase in 5143LM cells after exposure to CXCL12. We also observed that exposure to CXCL12 over varying periods phosphorylated ERK1/2 in an oscillatory pattern for all cell lines. Administration of LY294002 resulted in complete abrogation of CXCL12-induced proliferation in PanIN, 5143LM, and PANC-1 cells but not 5143PDA cells, whereas UO126 resulted in complete abrogation of CXCR4-enhanced proliferation in all cell lines.. Our studies show that CXCR4-induced proliferation is mediated by both AKT and ERK signaling in both murine and human pancreatic cancer cells.

Topics: Animals; Butadienes; Cell Line, Tumor; Cell Proliferation; Chemokine CXCL12; Chromones; Enzyme Inhibitors; Extracellular Signal-Regulated MAP Kinases; Humans; Immunohistochemistry; Mice; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Morpholines; Nitriles; Pancreatic Neoplasms; Phosphatidylinositol 3-Kinases; Phosphoinositide-3 Kinase Inhibitors; Proto-Oncogene Proteins c-akt; Receptors, CXCR4; Signal Transduction

Prostaglandin E2 (PGE2) is a product of cyclooxygenase (COX) and PGE synthase (PGES) and deactivated by 15-hydroxyprostaglandin dehydrogenase (PGDH). Down-regulation of PGDH contributes to PGE2 accumulation in lung and colon cancers but has not been identified in pancreatic cancer.. Normal human pancreatic and tumor-matched tissues, as well as MiaPaCa-2 and BxPC-3 cell lines, were assessed for COX-2, microsomal PGES-1, PGDH, and snail homolog 1 (SNAI1) and SNAI2 expressions by real-time polymerase chain reaction and Western blotting and PGE2 by enzyme-linked immunosorbent assay.. Normal tissues exhibited low COX-2 messenger RNA (mRNA) and protein expressions and high PGDH mRNA and protein expressions and PGE2 levels at 13 pg/mg of protein. In contrast, tumor tissues exhibited high COX-2 mRNA and protein expressions and low PGDH mRNA and protein expressions and PGE2 levels at 32 pg/mg of protein. Tumor tissues exhibited significantly elevated expressions of SNAI2 mRNA and protein but not SNAI1 because SNAI1 and SNAI2 reportedly down-regulate PGDH expression. The COX-2-positive BxPC-3 but not the COX-2-negative MiaPaCa-2 treated with 100-nmol/L PGE2 induced phosphorylated extracellular signal-related kinase that was blocked by the mitogen-activated protein kinase kinase inhibitor U0126, demonstrating the ability of PGE2 to activate ERK.. These results suggest that enhanced PGE2 production proceeds through the expressions of COX-2 and microsomal PGES-1 and down-regulation of PGDH by SNAI2 in pancreatic tumors.

Topics: Butadienes; Carcinoma, Pancreatic Ductal; Cell Line, Tumor; Cyclooxygenase 2; Dinoprostone; Down-Regulation; Humans; Hydroxyprostaglandin Dehydrogenases; Mitogen-Activated Protein Kinase Kinases; Nitriles; Pancreatic Neoplasms; Snail Family Transcription Factors; Transcription Factors

The Ras/Raf/MEK/ERK signaling has been implicated in uncontrolled cell proliferation and tumor progression in pancreatic cancer. The purpose of this study is to evaluate the antitumor activity of MEK inhibitor U0126 in combination with Hsp90 inhibitor 17-allylamino-17-demethoxygeldanamycin (17-AAG) in pancreatic cancer cells. Western blotting showed that 17-AAG caused a 2- to 3-fold transient activation of MEK/ERK signaling in pancreatic cancer cells. The activation sustained for 6 h before phospho-ERK (p-ERK) destabilization. The selective MEK inhibitor U0126 completely abolished 17-AAG induced ERK1/2 activation and resulted in more than 80% of phospho-ERK degradation after only 15 min treatment. Moreover, U0126 had complementary effect on 17-AAG regulated oncogenic and cell cycle related proteins. Although 17-AAG downregulated cyclin D1, cyclin E, CDK4 and CDK6, it led to cyclin A and CDK2 accumulation, which was reversed by the addition of U0126. Antiproliferation assay showed that combination of U0126 and 17-AAG resulted in synergistic cytotoxic effect. More importantly, 17-AAG alone only exhibited moderate inhibition of cell migration in vitro, while addition of U0126 dramatically enhanced the inhibitory effect by 2- to 5-fold. Taken together, these data demonstrate that MEK inhibitor U0126 potentiates the activity of Hsp90 inhibitor 17-AAG against pancreatic cancer cells. The combination of Hsp90 and MEK inhibition could provide a promising avenue for the treatment of pancreatic cancer.

Topics: Antineoplastic Agents; Benzoquinones; Butadienes; Cell Line, Tumor; Cell Movement; Cell Proliferation; Drug Synergism; Enzyme Activation; HSP90 Heat-Shock Proteins; Humans; Kinetics; Lactams, Macrocyclic; MAP Kinase Signaling System; Nitriles; Pancreatic Neoplasms; Protein Kinase Inhibitors; src-Family Kinases

Metastasis accounts for the poor outcome of patients with pancreatic cancer. We recently discovered PRSS3 to be over-expressed in metastatic human pancreatic cancer cells. This study aimed to elucidate the role of PRSS3 in the growth and metastasis of human pancreatic cancer.. PRSS3 expression in human pancreatic cancer cell lines was detected by qPCR and immunoblotting. The effect of PRSS3 on cancer cell proliferation, migration and invasion in vitro, tumour growth and metastasis in vivo were investigated by manipulation of PRSS3 expression in human pancreatic cancer cell lines. VEGF expression was detected by ELISA, and the pathway through which PRSS3 regulates VEGF expression was investigated. The therapeutic effect of targeting this pathway on metastasis was assessed in vivo. Immunohistochemistry was employed to detect PRSS3 expression in human pancreatic cancer tissues.. PRSS3 was over-expressed in the metastatic PaTu8988s cell line, but not in the non-metastatic PaTu8988t cell line. Over-expression of PRSS3 promoted pancreatic cancer cell proliferation as well as invasion in vitro, and tumour progression and metastasis in vivo. Stepwise investigations demonstrated that PRSS3 upregulates VEGF expression via the PAR1-mediated ERK pathway. ERK inhibitor significantly delayed the progression of metastases of pancreatic cancer and prolonged the survival of animals bearing metastatic pancreatic cancer (p<0.05). 40.54% of human pancreatic cancers (n=74) were positive for PRSS3 protein. A significant correlation was observed between PRSS3 expression and metastasis (p<0.01). Multivariate Cox regression analysis indicated that patients with PRSS3 expression in their tumours had a shorter survival time compared to those without PRSS3 expression (p<0.05).. PRSS3 plays an important role in the progression, metastasis and prognosis of human pancreatic cancer. Targeting the PRSS3 signalling pathway may be an effective and feasible approach for treatment of this lethal cancer.

Topics: Adult; Aged; Animals; Butadienes; Cell Proliferation; Disease Progression; Enzyme Inhibitors; Extracellular Signal-Regulated MAP Kinases; Female; Humans; Male; Mice; Mice, Nude; Middle Aged; Neoplasm Invasiveness; Neoplasm Metastasis; Neoplasm Proteins; Neoplasm Transplantation; Nitriles; Pancreatic Neoplasms; Prognosis; Survival Analysis; Trypsin; Tumor Cells, Cultured; Up-Regulation; Vascular Endothelial Growth Factor A; Xenograft Model Antitumor Assays

We examined the effects of troglitazone on expression of E-cadherin and claudin 4 in human pancreatic cancer cells. Troglitazone dose-dependently increased expression of E-cadherin and claudin 4 mRNA and protein in PK-1 cells. Snail, Slug and ZEB1, mRNAs were not changed by troglitazone, indicating that these three transcriptional repressors would not play a role in the induction of E-cadherin by troglitazone. GW9662, a PPARgamma antagonist, failed to block the increased expression of E-cadherin or claudin 4 mRNA, suggesting a PPARgamma-independent pathway. A MEK inhibitor, U0126, increased E-cadherin or claudin 4 mRNA and protein expression, and potently inhibited cell invasion. Because troglitazone down-regulates MEK-ERK signaling and inhibit cell invasion in PK-1 as shown in our previous study, these results suggest that troglitazone increases expression of E-cadherin and claudin 4 possibly through inhibition of MEK-ERK signaling in pancreatic cancer cells, which might be involved in the troglitazone-induced inhibition of cell invasive activity.

Topics: Antineoplastic Agents; Butadienes; Cadherins; Cell Line, Tumor; Chromans; Claudin-4; Extracellular Signal-Regulated MAP Kinases; Humans; MAP Kinase Kinase Kinases; Membrane Proteins; Nitriles; Pancreatic Neoplasms; Protein Kinase Inhibitors; Thiazolidinediones; Troglitazone

Imatinib mesylate (imatinib) inhibits the c-Kit-dependent tyrosine kinase activities and highly effective in the treatment of CML and GIST patients. Although pancreatic cancer is reported to express c-Kit, imatinib does not effectively inhibit pancreatic cancer cell growth at physiological concentrations. Therefore, we investigated the mechanism of resistance of pancreatic cancer to imatinib treatment. Imatinib inhibited growth of pancreatic cancer cell lines in concentration and time-dependent fashion regardless of c-Kit expression. However, 5 microM imatinib, which is almost a mean maximal plasma concentration in clinical setting, failed to suppress pancreatic cancer cell growth. Western blot analysis demonstrated that 5 microM imatinib treatment for 1h activated the MEK-MAPK pathway and the activation was independent of Ras activation. Administration of 5 microM imatinib and 1 microM U0126 (MEK inhibitor) significantly suppressed pancreatic cell growth. Our results indicate that a combination therapy of imatinib and MEK inhibitor can be a new therapeutic strategy to suppress the progression of pancreatic cancer.

Topics: Antineoplastic Combined Chemotherapy Protocols; Benzamides; Blotting, Western; Butadienes; Cell Line, Tumor; Cell Proliferation; Drug Resistance, Neoplasm; Enzyme Inhibitors; Extracellular Signal-Regulated MAP Kinases; Humans; Imatinib Mesylate; Mitogen-Activated Protein Kinase Kinases; Nitriles; Pancreatic Neoplasms; Piperazines; Pyrimidines

Expression of mutationally activated RAS is a feature common to the vast majority of human pancreatic adenocarcinomas. RAS elicits its effects through numerous signaling pathways including the RAF-->mitogen-activated protein (MAP)/extracellular signal-regulated kinase (ERK) kinase [MEK]-->ERK MAP kinase pathway. To assess the role of this pathway in regulating cell proliferation, we tested the effects of pharmacologic inhibition of MEK on human pancreatic cancer cell lines. In eight cell lines tested, MEK inhibition led to a cessation of cell proliferation accompanied by G0-G1 cell cycle arrest. Concomitant with cell cycle arrest, we observed induced expression of p27Kip1, inhibition of cyclin/cyclin-dependent kinase 2 (cdk2) activity, accumulation of hypophosphorylated pRb, and inhibition of E2F activity. Using both antisense and RNA interference techniques, we assessed the role of p27Kip1 in the observed effects of MEK inhibition on pancreatic cancer cell proliferation. Inhibition of p27Kip1 expression in Mia PaCa-2 cells restored the activity of cyclin/cdk2, phosphorylation of pRb, and E2F activity and partially relieved the effects of U0126 on pancreatic cancer cell cycle arrest. Consistent with the effects of p27Kip1 on cyclin/cdk2 activity, inhibition of CDK2 expression by RNA interference also led to G0-G1 cell cycle arrest. These data suggest that the expression of p27Kip1 is downstream of the RAF-->MEK-->ERK pathway and that the regulated expression of this protein plays an important role in promoting the proliferation of pancreatic cancer cells. Moreover, these data suggest that pharmacologic inhibition of the RAF-->MEK-->ERK signaling pathway alone might tend to have a cytostatic, as opposed to a cytotoxic, effect on pancreatic cancer cells.

Topics: Butadienes; CDC2-CDC28 Kinases; Cell Cycle; Cell Cycle Proteins; Cell Growth Processes; Cell Line, Tumor; Cyclin-Dependent Kinase 2; Cyclin-Dependent Kinase 4; Cyclin-Dependent Kinase Inhibitor p27; Cyclin-Dependent Kinases; Enzyme Inhibitors; Extracellular Signal-Regulated MAP Kinases; Humans; MAP Kinase Kinase Kinases; MAP Kinase Signaling System; Nitriles; Pancreatic Neoplasms; Phosphorylation; Proto-Oncogene Proteins; raf Kinases; Retinoblastoma Protein; RNA Interference; RNA, Antisense; Transfection; Tumor Suppressor Proteins

The objectives of the present study were to determine the effect of nicotine on MAPK signaling and on the proliferation of AR42J cells as well as to assess the relationship between MAPK activation and exocrine secretion in these cells. AR42J cells were incubated with nicotine and analyzed for the activation of MAPK by Western blot analysis using their respective antibodies and confirmed by immunohistochemistry. The effect of nicotine on cell proliferation was determined by the spectrophotometric method, and cell function was assessed by cholecystokinin (CCK)-stimulated amylase release into the culture medium. Nicotine at a dose of 100 microM induced phospho-ERK1/2 activation maximally in 3 min compared with untreated cells. Furthermore, immunofluorescence study confirmed the nicotine-induced increase in translocation of phospho-ERK1/2 to the nucleus. Activation of phospho-ERK1/2 was inhibited by an ERK1/2 pathway inhibitor but not by a nicotine receptor antagonist. At the same dose, there was significantly enhanced proliferation of AR42J cells until 72 h without toxic effect, as the percentage of lactate dehydrogenase release remained unchanged. Other MAPKs, c-Jun NH2-terminal kinase 1/2 and p38 MAPK, were not affected by nicotine treatment. At a nicotine dose of 100 microM, the CCK-stimulated release of amylase was maximal at 6 min, and, although a nicotinic receptor antagonist inhibited this response, it was not inhibited by the ERK1/2 pathway inhibitor. We conclude that nicotine treatment induced activation of ERK1/2 and increased the proliferation of AR42J cells. The data further indicate that MAPK signaling by nicotine is independent of the secretory response.

Topics: Amylases; Animals; Butadienes; Cell Line, Tumor; Cell Proliferation; Enzyme Activation; Extracellular Signal-Regulated MAP Kinases; Mitogens; Nicotine; Nitriles; Pancreatic Neoplasms; Signal Transduction; Time Factors

Cyclooxygenase 2 (COX-2), the inducible form of prostaglandin G/H synthase, is associated with several human cancers including pancreatic adenocarcinoma. Pancreatic stellate cells (PSCs) play a central role in the intense desmoplasia that surrounds pancreatic adenocarcinoma. The present study examined COX-2 expression in PSCs. PSCs isolated from normal rats, were cultured and exposed to conditioned medium (CM) from the human pancreatic cell line, PANC-1.. COX-2 expression was evaluated by immunostaining and western blotting. Proliferation of PSCs was determined by thymidine incorporation and cell counting.. COX-2 was found to be constitutively expressed in PSCs, and COX-2 protein was up-regulated by PANC-1 CM. Moreover, the induction of COX-2 by PANC-1 CM was prevented by U0126, an extracellular signal-regulated kinase (ERK) 1/2 inhibitor suggesting that activation of ERK 1/2 is needed for stimulation of COX-2. Finally, NS398, a selective COX-2 inhibitor, reduced the growth of PSCs by PANC-1 CM, indicating that activation of COX-2 is required for cancer stimulated PSC proliferation.. The results suggest that COX-2 may play an important role in the regulation of PSC proliferation in response to pancreatic cancer.

Topics: Animals; Butadienes; Cell Proliferation; Cells, Cultured; Coculture Techniques; Culture Media, Conditioned; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Neoplastic; Humans; Male; Nitriles; Nitrobenzenes; Pancreas; Pancreatic Neoplasms; Rats; Rats, Sprague-Dawley; Sulfonamides

We have previously shown the importance of LTB4 in human pancreatic cancer. LTB4 receptor antagonists block growth and induce apoptosis in pancreatic cancer cells both in vitro and in vivo. Therefore, we investigated the effect of LTB4 on proliferation of human pancreatic cancer cells and the mechanisms involved. LTB4 stimulated DNA synthesis and proliferation of both PANC-1 and AsPC-1 human pancreatic cancer cells, as measured by thymidine incorporation and cell number. LTB4 stimulated rapid and transient activation of MEK and ERK1/2 kinases. The MEK inhibitors, PD98059 and U0126, blocked LTB4-stimulated ERK1/2 activation and cell proliferation. LTB4 also stimulated phosphorylation of p38 MAPK; however, the p38 MAPK inhibitor, SB203580, failed to block LTB4-stimulated growth. The activity of JNK/SAPK was not affected by LTB4 treatment. Phosphorylation of Akt was also induced by LTB4 and this effect was blocked by the PI-3 kinase inhibitor wortmannin, which also partially blocked LTB4-stimulated cell proliferation. In conclusion, LTB4 stimulates proliferation of human pancreatic cancer cells through MEK/ERK and PI-3 kinase/Akt pathways, while p38 MPAK and JNK/SAPK are not involved.

Topics: Androstadienes; Arachidonate 5-Lipoxygenase; Benzoates; Butadienes; Cell Division; Cell Line, Tumor; Electrophoresis, Polyacrylamide Gel; Enzyme Inhibitors; Flavonoids; Humans; Leukotriene B4; Mitogen-Activated Protein Kinases; Nitriles; Pancreatic Neoplasms; Phosphatidylinositol 3-Kinases; Phosphoinositide-3 Kinase Inhibitors; Phosphorylation; Signal Transduction; Wortmannin

To clarify the involvement of matrix metalloproteinase-7 (MMP-7) in cell dissociation and the subsequent invasion of pancreatic cancer cells.. Western blotting, in vitro invasion assay, immunocytochemistry, and immunohistochemistry were performed in pancreatic cancer cell lines or pancreatic cancer tissue.. The active form of the MMP-7 protein was expressed exclusively in the conditioned medium of dissociated (PC-1.0 and AsPC-1) pancreatic cancer cells, whereas proMMP-7 protein was only detected in the conditioned medium of non-dissociated (PC-1 and Capan-2) cells. Both intracellular and conditioned medium localised MMP-7 was greatly reduced by treatment with the epidermal growth factor receptor (EGFR) inhibitor AG1478 and the mitogen activated protein kinase kinase (MEK) inhibitor U0126 in pancreatic cancer cells. MMP-7 treatment significantly induced the disruption of tight junction (TJ) structures and subsequent cell dissociation, and activation of the EGFR mediated MEK- ERK (extracellular signal regulated protein kinase) signalling pathway in the non-dissociated pancreatic cancer cells. Moreover, the strong in vitro invasiveness of dissociated cells was inhibited by AG1478 and U0126 treatment, whereas the weak invasiveness of non-dissociated cells was apparently induced by MMP-7 treatment. In addition, MMP-7 expression was stronger at the invasive front than at the centre of human pancreatic tumours.. MMP-7 is involved in cell dissociation and the subsequent invasion of pancreatic cancer cells. It induces the disruption of TJ structures and forms a positive feedback loop with activation of the EGFR mediated MEK-ERK signalling pathway.

Topics: Adenocarcinoma; Adult; Aged; Blotting, Western; Butadienes; Culture Media, Conditioned; Down-Regulation; Enzyme Inhibitors; ErbB Receptors; Extracellular Signal-Regulated MAP Kinases; Female; Humans; Male; Matrix Metalloproteinase 7; Middle Aged; Mitogen-Activated Protein Kinase Kinases; Neoplasm Invasiveness; Nitriles; Pancreatic Neoplasms; Quinazolines; Signal Transduction; Tight Junctions; Tumor Cells, Cultured; Tyrphostins

In our previous investigation, mitogen-activated protein kinase kinase 2 (MEK2) was detected as a factor which was correlated to the potential of invasion-metastasis. In this study, the immunocytochemical, immunohistochemical and mRNA expressions of MEK2 were examined in pancreatic cancer cell lines and tissue samples, respectively. Constitutive expressions of MEK2 and phosphorylated MEK (p-MEK) were observed in PC-1.0 and ASPC-1 cells, which exhibited a growth pattern of single cells, whereas the relevant expressions were quite faint in PC-1 cells and CAPAN-2 cells, which exhibited a growth pattern of island-like clonies. Simultaneous inductions of MEK2 expressions and cell dissociation were observed after the treatment with a conditioned medium (CM) of PC-1.0 cells. The expression of MEK2 and p-MEK were reduced and the cell aggregation was found in PC-1.0 and ASPC-1 cells after U0126 (a MEK inhibitor) treatment. In vivo, both the MEK2 and p-MEK overexpressed in human pancreatic cancer tissues and p-MEK was found to be more strongly expressed in the invasive front than that in the center of tumor (P<0.05). MEK2 is closely related to pancreatic cancer cell dissociation. MEK2 activation is probably involved in the first step of the cascade in the invasion-metastasis of pancreatic cancer.

Topics: Adult; Aged; Animals; Butadienes; Cell Aggregation; Cell Line, Tumor; Cell Size; Culture Media, Conditioned; Enzyme Inhibitors; Female; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Neoplastic; Humans; Immunohistochemistry; Male; MAP Kinase Kinase 2; Middle Aged; Mitogen-Activated Protein Kinase Kinases; Nitriles; Pancreatic Neoplasms; Phosphorylation; Protein-Tyrosine Kinases; RNA, Messenger

Mitogen-activated protein kinase kinase 2 (MEK2), the upstream kinase of extracellular signal-regulated kinase 1/2 (ERK1/2) was previously isolated as cancer cell dissociation related factor. In this study, to further clarify the regulatory mechanism of cancer cell dissociation, two hamster (PC-1.0 and PC-1) and human (Capan-2 and AsPC-1) pancreatic cancer cell lines were analyzed immunocytochemically with anti-ERK1, anti-ERK2 and anti-phosphorylated ERK1/2 (p-ERK1/2) antibodies. U0126 (a MEK1/2 inhibitor) significantly suppressed ERK2 and p-ERK1/2 expressions in PC-1.0 and AsPC-1 cells (P<0.05). Cancer cell dissociation factor (DF) markedly induced ERK2 and p-ERK1/2 expressions in PC-1 and Capan-2 cells (P<0.05), and the induced ERK2 and p-ERK1/2 expressions were inhibited by subsequent U0126-treatment (P<0.05). Simultaneously, light microscopic images showed that DF clearly induced cell dissociation in PC-1 and Capan-2 cells, while U0126-treatment induced cell aggregation in these pancreatic cancer cells. ERK2 activation is closely involved in cell dissociation of pancreatic cancer cells.

Topics: Animals; Butadienes; Cell Aggregation; Cricetinae; Enzyme Activation; Enzyme Inhibitors; Fluorescent Antibody Technique; Humans; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Mitogen-Activated Protein Kinases; Nitriles; Pancreatic Neoplasms; Phosphorylation; Signal Transduction; Tumor Cells, Cultured

Mitogen-activated protein kinase kinase 2 (MEK2) was detected as an invasion-metastasis related factor between highly invasive (PC-1.0) and weakly invasive (PC-1) pancreatic cancer cell lines in our previous study. On the other hand, tight junction (TJ) was found to be correlated with carcino-genesis and tumor development. In this study, the expressions and correlation of TJ transmembrane protein occludin and MEK/extracellular signal-regulated kinase (ERK) signaling pathway were analyzed to clarify the regulatory mechanism of cell dissociation in pancreatic cancer cells. Two hamster (PC-1.0 and PC-1) and human (AsPC-1 and CAPAN-2) pancreatic cancer cell lines were analyzed immunocytochemically with anti-occludin, phosphorylated MEK1/2 (p-MEK1/2), phosphorylated ERK1/2 (p-ERK1/2) antibodies. MEK1/2 inhibitor U0126 significantly induced the expression of occludin at the cell-cell junction and substantially suppressed the p-MEK1/2 and p-ERK1/2 expressions in PC-1.0 and AsPC-1 cells. In contrast, dissociation factor (DF) treatment obviously disrupted the occludin expressions at the sites of cell-cell junction and markedly induced the p-MEK1/2 and p-ERK1/2 expressions in PC-1 and CAPAN-2 cells. In addition, occludin expressions at cell-cell junction were restored and p-MEK1/2 and p-ERK1/2 expressions were suppressed by subsequent U0126-treatment in DF treated PC-1 and CAPAN-2 cells. Correspondingly, light microscopic images showed that DF induced the dissociation of cell island-like colonies in PC-1 and CAPAN-2 cells, and U0126-treatment induced cell aggregation in these pancreatic cancer cells. Occludin is involved in the cell dissociation in pancreatic cancer cells. Moreover, MEK/ERK signaling pathway probably regulates the cell dissociation status of pancreatic cancer through influencing the intracellular localization and expression of occludin.

Topics: Animals; Butadienes; Cell Line, Tumor; Cricetinae; Extracellular Signal-Regulated MAP Kinases; Gene Expression Regulation, Neoplastic; Humans; MAP Kinase Signaling System; Membrane Proteins; Mitogen-Activated Protein Kinase 1; Neoplasm Metastasis; Nitriles; Occludin; Pancreatic Neoplasms; Tight Junctions

Hypoxia, frequently found in the center of solid tumor, is associated with resistance to chemotherapy by activation of signaling pathways that regulate cell pro-liferation, angiogenesis, and apoptosis. We determined whether hypoxia can increase the resistance of human pancreatic carcinoma cells to gemcitabine-induced apoptosis by activation of phosphatidylinositol 3'-kinase (PI3K)/Akt, MEK/mitogen-activated protein kinase (extracellular signal-regulated kinase) [MAPK(Erk) kinase (MEK)], and nuclear factor kappa B (NF-kappa B) signaling pathways.. We evaluated the phosphorylation of Akt and MAPK(Erk), DNA binding activity of NF-kappa B, and apoptosis induced by gemcitabine in L3.6pl human pancreatic cancer cells under normoxic and hypoxic conditions. We then examined the effects of the PI3K inhibitor LY294002, MEK inhibitor U0126, and the epidermal growth factor receptor tyrosine kinase inhibitor PKI 166 on these signaling pathways and induction of apoptosis.. Hypoxic conditions increased phosphorylation of Akt and MAPK(Erk) and NF-kappa B DNA binding activity in L3.6pl cells. The activation of Akt and NF-kappa B was prevented by LY294002, whereas the activity of MAPK(Erk), but not NF-kappa B, was inhibited by U0126. The increased activation of Akt, NF-kappa B, and MAPK(Erk) was inhibited by PKI 166. Under hypoxic conditions, L3.6pl cells were resistant to apoptosis induced by gemcitabine. The addition of LY294002 or PKI 166 abrogated cell resistance to gemcitabine, whereas U0126 only partially decreased this resistance.. These data demonstrate that hypoxia can induce resistance of pancreatic cancer cells to gemcitabine mainly through the PI3K/Akt/NF-kappa B pathways and partially through the MAPK(Erk) signaling pathway. Because PKI 166 prevented the activation of PI3K/Akt/NF-kappa B and MAPK(Erk) pathways, the combination of this tyrosine kinase inhibitor with gemcitabine should be an effective therapy for pancreatic cancer.

Topics: Antimetabolites, Antineoplastic; Antineoplastic Agents; Apoptosis; Blotting, Western; Butadienes; Cell Division; Cell Line, Tumor; Chromones; Deoxycytidine; Dose-Response Relationship, Drug; Enzyme Inhibitors; Epidermal Growth Factor; ErbB Receptors; Gemcitabine; Humans; Hypoxia; Mitogen-Activated Protein Kinases; Morpholines; Neovascularization, Pathologic; NF-kappa B; Nitriles; Oxygen; Pancreatic Neoplasms; Phosphatidylinositol 3-Kinases; Phosphorylation; Protein-Tyrosine Kinases; Pyrimidines; Pyrroles; Signal Transduction; Sp1 Transcription Factor; Time Factors; Tyrosine

The RAS-activated RAF-->MEK-->extracellular signal-regulated kinase (ERK) and phosphatidylinositol 3'-kinase (PI3'-kinase)-->PDK1-->AKT signaling pathways are believed to cooperate to promote the proliferation of normal cells and the aberrant proliferation of cancer cells. To explore the mechanisms that underlie such cooperation, we have derived cells harboring conditionally active, steroid hormone-regulated forms of RAF and AKT. These cells permit the assessment of the biological and biochemical effects of activation of these protein kinases either alone or in combination with one another. Under conditions where activation of neither RAF nor AKT alone promoted S-phase progression, coactivation of both kinases elicited a robust proliferative response. Moreover, under conditions where high-level activation of RAF induced G(1) cell cycle arrest, activation of AKT bypassed the arrest and promoted S-phase progression. At the level of the cell cycle machinery, RAF and AKT cooperated to induce cyclin D1 and repress p27(Kip1) expression. Repression of p27(Kip1) was accompanied by a dramatic reduction in KIP1 mRNA and was observed in primary mouse embryo fibroblasts derived from mice either lacking SKP2 or expressing a T187A mutated form of p27(Kip1). Consistent with these observations, pharmacological inhibition of MEK or PI3'-kinase inhibited the effects of activated RAS on the expression of p27(Kip1) in NIH 3T3 fibroblasts and in a panel of bona fide human pancreatic cancer cell lines. Furthermore, we demonstrated that AKT activation led to sustained activation of cyclin/cdk2 complexes that occurred concomitantly with the removal of RAF-induced p21(Cip1) from cyclin E/cdk2 complexes. Cumulatively, these data strongly suggest that the RAF-->MEK-->ERK and PI3'K-->PDK-->AKT signaling pathways can cooperate to promote G(0)-->G(1)-->S-phase cell cycle progression in both normal and cancer cells.

Topics: Animals; Benzamides; Blotting, Western; Butadienes; Cell Cycle; Cell Cycle Proteins; Cell Division; Cell Extracts; Cell Line, Tumor; Cells, Cultured; Chromones; Cyclin D1; Cyclin-Dependent Kinase Inhibitor p27; Embryo, Mammalian; Enzyme Activation; Enzyme Inhibitors; Fibroblasts; Humans; Mice; Microscopy, Fluorescence; Morpholines; NIH 3T3 Cells; Nitriles; Pancreatic Neoplasms; Protein Serine-Threonine Kinases; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-akt; raf Kinases; Retroviridae; RNA, Messenger; Tumor Suppressor Proteins

Neuropeptides and their corresponding G protein-coupled receptors are increasingly implicated in the autocrine/paracrine stimulation of growth of human cancers. Using K-Ras mutated human pancreatic ductal adenocarcinoma cell line PANC-1 as a model system, we demonstrate that neurotensin (NT) induced translocation of phosphorylated extracellular signal-regulated kinases (ERK-1 and ERK-2) to the nucleus, rapid dose-dependent activation of dual-specificity mitogen and ERK-1 and ERK-2 kinase-1/2 (MEK-1/2), and striking stimulation of c-Raf-1 but not pan-Ras. Furthermore, treatment of PANC-1 cells with protein kinase C (PKC) inhibitors, GF-1 and Ro 31-8220, completely abrogated NT-induced ERK-1 and ERK-2 activation, and significantly attenuated NT-induced c-Raf-1 stimulation. Interestingly, NT did not stimulate epidermal growth factor receptor transactivation, and epidermal growth factor receptor tyrosine kinase or Src inhibitors did not affect NT-induced ERK activation in PANC-1 cells. Our results indicate that NT potently stimulates c-Raf-1-MEK-ERK in PANC-1 cells through a PKC-dependent signaling pathway. Furthermore, we show that NT-induced DNA synthesis in PANC-1 cells is ERK-dependent. Finally, we demonstrate that NT stimulated clonal growth of PANC-1 cells in semisolid medium, which is abrogated by both GF-1 and the MEK-1/2 inhibitor, U0126. Collectively our results suggest that PKC-mediated stimulation of ERK-1 and ERK-2 play a pivotal role in NT-induced growth of PANC-1 cells harboring activating K-Ras mutation.

Topics: Butadienes; Carcinoma, Pancreatic Ductal; Cell Division; Cell Nucleus; DNA-Binding Proteins; DNA, Neoplasm; Enzyme Activation; Enzyme Inhibitors; ErbB Receptors; Erythroid-Specific DNA-Binding Factors; Focal Adhesion Kinase 2; Humans; MAP Kinase Signaling System; Mitogen-Activated Protein Kinases; Neurotensin; Nitriles; Pancreatic Neoplasms; Phosphorylation; Protein Kinase C; Protein-Tyrosine Kinases; Proto-Oncogene Proteins c-raf; src-Family Kinases; Transcription Factors; Transcriptional Activation; Tumor Cells, Cultured

The MAP kinase kinase (MEK)-extracellular signal-regulated kinase (ERK) pathway is critical for cell growth and survival. In the current study, we examined the effect of inhibiting the MEK-ERK pathway in pancreatic tumor cells with the MEK-specific inhibitor U0126. In addition, we investigated whether the MEK-ERK pathway influenced the response of pancreatic cancer cells to nonsteroidal antiinflammatory drugs (NSAIDs).. Cell growth was monitored by a colorimetric proliferation assay and cell counts. Cell cycle analysis was performed using flow cytometry. Apoptosis was measured using a DNA fragmentation ELISA. Protein expression was detected by Western blot.. Treatment with U0126 dose dependently inhibited the growth of 3 human pancreatic carcinoma cell lines (BxPC-3, PANC-1, and MIA PaCa-2). U0126 treatment resulted in cell-cycle alterations but did not induce apoptosis. Growth inhibitory concentrations of NSAIDs unexpectedly increased ERK phosphorylation in BxPC-3 and MIA PaCa-2 cells. We therefore evaluated the effect of treating pancreatic tumor cells with the combination of the NSAID sulindac and U0126. Treatment with U0126 complemented sulindac-induced growth inhibition in BxPC-3 and PANC-1 cells. The expression of several cell cycle (p21, p27, cyclin D1) and apoptotic (survivin, Bcl-xL) regulatory proteins was altered after U0126 and/or sulindac treatment. Our findings suggest that inhibition of the MEK-ERK signaling pathway may sensitize pancreatic tumor cells to NSAID therapy.

Topics: Anti-Inflammatory Agents, Non-Steroidal; Apoptosis; Blotting, Western; Butadienes; Cell Cycle; Cell Cycle Proteins; Cell Division; Cell Line, Tumor; Dose-Response Relationship, Drug; Drug Synergism; Enzyme Inhibitors; Humans; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Mitogen-Activated Protein Kinase Kinases; Mitogen-Activated Protein Kinases; Nitriles; Pancreatic Neoplasms; Phosphorylation; Sulindac

p8 is a stress-induced protein with multiple functions and biochemically related to the architectural factor HMG-I/Y. We analyzed the expression and function of p8 in pancreatic cancer-derived cells.. Expression of p8 was silenced in the human pancreatic cancer cell lines Panc-1 and BxPc-3 by infection with a retrovirus expressing p8 RNA in the antisense orientation. Cell growth was measured in control and p8-silenced cells. Influence on p8 expression of the induction of intracellular pathways promoting cellular growth or growth arrest was monitored.. p8-silenced cells grew more rapidly than control cells transfected with the empty retrovirus. Activation of the Ras-->Raf-->MEK-->ERK and JNK intracellular pathways down-regulated p8 expression. In addition, the MEK1/2 inhibitor U0126 and the JNK inhibitor SP600125 up-regulates expression of p8. Conversely, p38 or TGFbeta-1 induced p8 expression whereas the specific p38 inhibitor SB203580 down-regulated p8 expression. Finally, TGFbeta-1 induction was in part mediated through p38.. p8 inhibits the growth of human pancreatic cancer cells. p8 expression is induced through pathways involved in growth inhibition and repressed by factors that promote cell growth. These results suggest that p8 belongs to a pathway regulating the growth of pancreatic cancer cells.

Topics: Anthracenes; Basic Helix-Loop-Helix Transcription Factors; Butadienes; Cell Line, Tumor; Cell Proliferation; Culture Media; Culture Media, Serum-Free; DNA-Binding Proteins; Enzyme Inhibitors; Gene Expression Regulation, Neoplastic; Gene Silencing; Genetic Vectors; Growth Inhibitors; Humans; Imidazoles; JNK Mitogen-Activated Protein Kinases; Mitogen-Activated Protein Kinases; Neoplasm Proteins; Nitriles; Pancreatic Neoplasms; Proto-Oncogene Proteins c-raf; Pyridines; ras Proteins; Retroviridae; RNA, Antisense; Transfection; Transforming Growth Factor beta; Transforming Growth Factor beta1

Cyclooxygenase-2 (COX-2) and ERK-MAPK mitogenic signaling pathways are important in human hepatocellular carcinoma. We investigated the effect of COX-2 inhibition on ERK-MAPK signaling and the effect of combining MEK (MAPK kinase) and COX-2 inhibitors in human hepatocellular carcinoma in vitro. COX and ERK expression were determined by immunoblot in HepG2 and Hep3B cells. COX-2 and MEK activity were determined by prostaglandin E(2) assay and phosphospecific immunoblot, respectively. Cell growth was determined by cell proliferation and cell counts. Apoptosis was determined by DNA fragmentation enzyme-linked immunosorbent assay and flow cytometry. Cell cycle was determined by flow cytometry. HepG2 and Hep3B cells do not express COX-1 or COX-2. Correspondingly, basal and agonist (arachidonic acid, lipopolysaccharide)-stimulated COX-2 activity is undetectable. Treatment of HepG2 and Hep3B cells with NS398 resulted in an increase in ERK1/2 phosphorylation (MEK activity) in a concentration-dependent fashion (NS398, 1 to 100 micromol/L). Treatment with the COX-2 inhibitor NS398 in the presence of U0126 (MEK inhibitor) effectively suppressed ERK1/2 phosphorylation as determined by phosphospecific ERK1/2 immunoblot. Total ERK1/2 and COX-2 were unchanged with NS398 and U0126 treatments. In HepG2 cells, NS398 (1 to 100 micromol/L) decreased apoptosis as determined by DNA fragmentation enzyme-linked immunosorbent assay. Relative apoptosis was increased with U0126 alone or in combination with NS398 (9 to 10 times the control value), eliminating the anti-apoptotic effect of NS398. In Hep3B cells, apoptosis was unchanged with NS398 (1 to 50 micromol/L) or U0126 (1 to 10 micromol/L) alone. The combination of NS398 and U0126 in Hep3B cells resulted in a synergistic increase in apoptosis (10 times the control value). Relative apoptosis in both cell lines strongly correlated with changes in the expression of the antiapoptotic protein Bcl-xL. Cellular growth was assessed by colorimetric proliferation assay and cell counts. HepG2 and Hep3B cells had concentration-dependent inhibition of cell growth with NS398 or U0126 treatment alone. The combination of NS398 and U0126 resulted in complementary inhibitory effects on growth. Growth inhibitory effects in HepG2 and Hep3B cells with combination treatment appear to be, in part, secondary to the induction of G(0)/G(1) and G(2)/M cell cycle arrest, respectively, as determined by flow cytometry. Despite differential signaling in HepG

Topics: Adenocarcinoma; Apoptosis; Butadienes; Carcinoma, Hepatocellular; Cell Cycle; Cell Division; Cell Line, Tumor; Cyclooxygenase 1; Cyclooxygenase 2; Dinoprostone; Drug Synergism; Enzyme Inhibitors; Humans; Isoenzymes; Liver Neoplasms; Membrane Proteins; Mitogen-Activated Protein Kinase Kinases; Mitogen-Activated Protein Kinases; Nitriles; Nitrobenzenes; Pancreatic Neoplasms; Prostaglandin-Endoperoxide Synthases; Signal Transduction; Sulfonamides