u-0126 and Carcinoma--Pancreatic-Ductal

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

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

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

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

Neurotensin (NT) and epidermal growth factor (EGF) induced rapid extracellular-regulated protein kinase (ERK) activation through different signaling pathways in the K-Ras mutated human pancreatic carcinoma cell lines PANC-1 and MIA PaCa-2. NT stimulated ERK activation via a protein kinase C (PKC)-dependent (but EGF receptor-independent) pathway in PANC-1 and MIA PaCa-2 cells, whereas EGF promoted ERK activation through a PKC-independent pathway in these cells. Concomitant stimulation of these cells with NT and EGF induced a striking increase in the duration of ERK pathway activation as compared with that obtained in cells treated with each agonist alone. Stimulation with NT + EGF promoted synergistic stimulation of DNA synthesis and anchorage-independent growth. Addition of the MEK inhibitor U0126, either prior to stimulation with NT + EGF or 2 h after stimulation with NT + EGF prevented the synergistic increase in DNA synthesis and suppressed the sustained phase of ERK activation. Furthermore, treatment with the selective PKC inhibitor GF-1 converted the sustained ERK activation in response to NT and EGF into a transient signal and also abrogated the synergistic increase in DNA synthesis. Collectively, our results suggest that the sustained phase of ERK signaling mediates the synergistic effects of NT and EGF on DNA synthesis in pancreatic cancer cells.

Topics: Butadienes; Carcinoma, Pancreatic Ductal; Cell Line, Tumor; Cell Proliferation; DNA Replication; Enzyme Activation; Enzyme Inhibitors; Epidermal Growth Factor; Extracellular Signal-Regulated MAP Kinases; Humans; MAP Kinase Signaling System; Neurotensin; Nitriles; Protein Kinase C

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