n-(4-methoxybenzyl)-n--(5-nitro-1-3-thiazol-2-yl)urea and Pancreatic-Neoplasms

Glycogen synthase kinase-3 (GSK-3) can act as either a tumour promoter or suppressor by its inactivation depending on the cell type. There are conflicting reports on the roles of GSK-3 isoforms and their interaction with Notch1 in pancreatic cancer. It was hypothesized that GSK-3α stabilized Notch1 in pancreatic cancer cells thereby promoting cellular proliferation.. The pancreatic cancer cell lines MiaPaCa2, PANC-1 and BxPC-3, were treated with 0-20 μM of AR-A014418 (AR), a known GSK-3 inhibitor. Cell viability was determined by the MTT assay and Live-Cell Imaging. The levels of Notch pathway members (Notch1, HES-1, survivin and cyclinD1), phosphorylated GSK-3 isoforms, and apoptotic markers were determined by Western blot. Immunoprecipitation was performed to identify the binding of GSK-3 specific isoform to Notch1.. AR-A014418 treatment had a significant dose-dependent growth reduction (P < 0.001) in pancreatic cancer cells compared with the control and the cytotoxic effect is as a result of apoptosis. Importantly, a reduction in GSK-3 phosphorylation lead to a reduction in Notch pathway members. Overexpression of active Notch1 in AR-A014418-treated cells resulted in the negation of growth suppression. Immunoprecipitation analysis revealed that GSK-3α binds to Notch1.. This study demonstrates for the first time that the growth suppressive effect of AR-A014418 on pancreatic cancer cells is mainly mediated by a reduction in phosphorylation of GSK-3α with concomitant Notch1 reduction. GSK-3α appears to stabilize Notch1 by binding and may represent a target for therapeutic development. Furthermore, downregulation of GSK-3 and Notch1 may be a viable strategy for possible chemosensitization of pancreatic cancer cells to standard therapeutics.

Topics: Apoptosis; Blotting, Western; Cell Line, Tumor; Cell Proliferation; Cell Survival; Glycogen Synthase Kinase 3; Humans; Immunoprecipitation; Pancreas; Pancreatic Neoplasms; Receptor, Notch1; Thiazoles; Urea

Pancreatic cancer is obstinate and resistant to gemcitabine, a standard chemotherapeutic agent for the disease. We previously showed a therapeutic effect of glycogen synthase kinase-3β (GSK3β) inhibition against gastrointestinal cancer and glioblastoma. Here, we investigated the effect of GSK3β inhibition on pancreatic cancer cell sensitivity to gemcitabine and the underlying molecular mechanism.. Expression, phosphorylation, and activity of GSK3β in pancreatic cancer cells (PANC-1) were examined by Western immunoblotting and in vitro kinase assay. The combined effect of gemcitabine and a GSK3β inhibitor (AR-A014418) against PANC-1 cells was examined by isobologram and PANC-1 xenografts in mice. Changes in gene expression in PANC-1 cells following GSK3β inhibition were studied by cDNA microarray and reverse transcription (RT)-PCR.. PANC-1 cells showed increased GSK3β expression, phosphorylation at tyrosine 216 (active form), and activity compared with non-neoplastic HEK293 cells. Administration of AR-A014418 at pharmacological doses attenuated proliferation of PANC-1 cells and xenografts, and significantly sensitized them to gemcitabine. Isobologram analysis determined that the combined effect was synergistic. DNA microarray analysis detected GSK3β inhibition-associated changes in gene expression in gemcitabine-treated PANC-1 cells. Among these changes, RT-PCR and Western blotting showed that expression of tumor protein 53-induced nuclear protein 1, a gene regulating cell death and DNA repair, was increased by gemcitabine treatment and substantially decreased by GSK3β inhibition.. The results indicate that GSK3β inhibition sensitizes pancreatic cancer cells to gemcitabine with altered expression of genes involved in DNA repair. This study provides insight into the molecular mechanism of gemcitabine resistance and thus a new strategy for pancreatic cancer chemotherapy.

Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Blotting, Western; Cell Line, Tumor; Deoxycytidine; DNA Repair; Drug Resistance, Neoplasm; Female; Gemcitabine; Gene Expression Regulation; Glycogen Synthase Kinase 3; Glycogen Synthase Kinase 3 beta; HEK293 Cells; Humans; Mice; Mice, Inbred BALB C; Mice, Nude; Oligonucleotide Array Sequence Analysis; Pancreatic Neoplasms; Phosphorylation; Reverse Transcriptase Polymerase Chain Reaction; Thiazoles; Urea; Xenograft Model Antitumor Assays

Recent studies have demonstrated that glycogen synthase kinase 3beta (GSK-3beta) is overexpressed in human colon and pancreatic carcinomas, contributing to cancer cell proliferation and survival. Here, we report the design, synthesis, and biological evaluation of benzofuran-3-yl-(indol-3-yl)maleimides, potent GSK-3beta inhibitors. Some of these compounds show picomolar inhibitory activity toward GSK-3beta and an enhanced selectivity against cyclin-dependent kinase 2 (CDK-2). Selected GSK-3beta inhibitors were tested in the pancreatic cancer cell lines MiaPaCa-2, BXPC-3, and HupT3. We determined that some of these compounds, namely compounds 5, 6, 11, 20, and 26, demonstrate antiproliferative activity against some or all of the pancreatic cancer cells at low micromolar to nanomolar concentrations. We found that the treatment of pancreatic cancer cells with GSK-3beta inhibitors 5 and 26 resulted in suppression of GSK-3beta activity and a distinct decrease of the X-linked inhibitor of apoptosis (XIAP) expression, leading to significant apoptosis. The present data suggest a possible role for GSK-3beta inhibitors in cancer therapy, in addition to their more prominent applications in CNS disorders.

Topics: Antineoplastic Agents; Apoptosis; Benzofurans; Cell Line, Tumor; Cell Proliferation; Cell Survival; Cyclin-Dependent Kinase 2; Drug Screening Assays, Antitumor; Glycogen Synthase Kinase 3; Glycogen Synthase Kinase 3 beta; Humans; Indoles; Maleimides; Models, Molecular; Pancreatic Neoplasms; Structure-Activity Relationship; X-Linked Inhibitor of Apoptosis Protein

Constitutive nuclear factor kappaB (NF-kappaB) activation is among the many deregulated signaling pathways that are proposed to drive pancreatic cancer cell growth and survival. Recent reports suggest that glycogen synthase kinase-3beta (GSK-3beta) plays a key role in maintaining basal NF-kappaB target gene expression and cell survival in pancreatic cancer cell lines. However, the mechanism by which GSK-3beta facilitates constitutive NF-kappaB signaling in pancreatic cancer remains unclear. In this report, we analyze the contributions of both GSK-3 isoforms (GSK-3alpha and GSK-3beta) in regulating NF-kappaB activation and cell proliferation in pancreatic cancer cell lines (Panc-1 and MiaPaCa-2). We show that GSK-3 isoforms are differentially required to maintain basal NF-kappaB DNA binding activity, transcriptional activity, and cell proliferation in Panc-1 and MiaPaCa-2 cells. Our data also indicate that IkappaB kinase (IKK) subunits are not equally required to regulate pancreatic cancer-associated NF-kappaB activity and cell growth. Importantly, we provide the first evidence that GSK-3 maintains constitutive NF-kappaB signaling in pancreatic cancer by regulating IKK activity. These data provide new insight into GSK-3-dependent NF-kappaB regulation and further establish GSK-3 and IKK as potential therapeutic targets for pancreatic cancer.

Topics: Cell Proliferation; Cell Survival; Enzyme Activation; Glycogen Synthase Kinase 3; Glycogen Synthase Kinase 3 beta; Humans; I-kappa B Kinase; Isoenzymes; NF-kappa B; Pancreatic Neoplasms; Protein Binding; Thiazoles; Tumor Cells, Cultured; Urea

We have shown recently that glycogen synthase kinase-3 (GSK-3) beta regulates nuclear factor-kappaB (NF-kappaB)-mediated pancreatic cancer cell survival and proliferation in vitro. Our objective was to determine the localization of GSK-3beta in pancreatic cancer cells and assess the antitumor effect of GSK-3 inhibition in vivo to improve our understanding of the mechanism by which GSK-3beta affects NF-kappaB activity in pancreatic cancer.. Immunohistochemistry and cytosolic/nuclear fractionation were done to determine the localization of GSK-3beta in human pancreatic tumors. We studied the effect of GSK-3 inhibition on tumor growth, cancer cell proliferation, and survival in established CAPAN2 tumor xenografts using a tumor regrowth delay assay, Western blotting, bromodeoxyuridine incorporation, and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling.. We found nuclear accumulation of GSK-3beta in pancreatic cancer cell lines and in 62 of 122 (51%) human pancreatic adenocarcinomas. GSK-3beta nuclear accumulation is significantly correlated with human pancreatic cancer dedifferentiation. We have found that active GSK-3beta can accumulate in the nucleus of pancreatic cancer cells and that inhibition of GSK-3 kinase activity represses its nuclear accumulation via proteasomal degradation within the nucleus. Lastly, we have found that inhibition of GSK-3 arrests pancreatic tumor growth in vivo and decreases NF-kappaB-mediated pancreatic cancer cell survival and proliferation in established tumor xenografts.. Our results show the antitumor effect of GSK-3 inhibition in vivo, identify GSK-3beta nuclear accumulation as a hallmark of poorly differentiated pancreatic adenocarcinoma, and provide new insight into the mechanism by which GSK-3beta regulates NF-kappaB activity in pancreatic cancer.

Topics: Adenocarcinoma; Animals; Apoptosis; Cell Differentiation; Cell Line, Tumor; Cell Nucleus; Cell Proliferation; Female; Glycogen Synthase Kinase 3; Glycogen Synthase Kinase 3 beta; Humans; Male; Mice; Mice, Nude; Middle Aged; NF-kappa B; Pancreatic Neoplasms; Structure-Activity Relationship; Survival Rate; Thiazoles; Transplantation, Heterologous; Urea; Xenograft Model Antitumor Assays

Recent studies using glycogen synthase kinase-3beta (GSK-3beta)-deficient mouse embryonic fibroblasts suggest that GSK-3beta positively regulates nuclear factor kappaB (NFkappaB)-mediated gene transcription. Because NFkappaB is suggested to participate in cell proliferation and survival pathways in pancreatic cancer, we investigated the role of GSK-3beta in regulating these cellular processes. Herein, we show that pancreatic cancer cells contain a pool of active GSK-3beta and that pharmacologic inhibition of GSK-3 kinase activity using small molecule inhibitors or genetic depletion of GSK-3beta by RNA interference leads to decreased cancer cell proliferation and survival. Mechanistically, we show that GSK-3beta influences NFkappaB-mediated gene transcription at a point distal to the Ikappa kinase complex, as only ectopic expression of the NFkappaB subunits p65/p50, but not an Ikappa kinase beta constitutively active mutant, could rescue the decreased cellular proliferation and survival associated with GSK-3beta inhibition. Taken together, our results simultaneously identify a previously unrecognized role for GSK-3beta in cancer cell survival and proliferation and suggest GSK-3beta as a potential therapeutic target in the treatment of pancreatic cancer.

Topics: Apoptosis; Cell Growth Processes; Cell Line, Tumor; Cell Survival; Gene Expression Regulation, Neoplastic; Glycogen Synthase Kinase 3; Glycogen Synthase Kinase 3 beta; Humans; NF-kappa B; Pancreatic Neoplasms; Thiazoles; Transcription, Genetic; Urea