n-(n-(3-5-difluorophenacetyl)alanyl)phenylglycine-tert-butyl-ester and Pancreatic-Neoplasms

The marked overexpression of cyclin-dependent kinase 5 (CDK5) or Notch1 receptor, which plays critical roles in pancreatic ductal adenocarcinoma (PDAC) development, has been detected in numerous PDAC cell lines and tissues. Although, a previous study has demonstrated that CDK5 inhibition disrupts Notch1 functions in human umbilical vein endothelial cells, the mechanism underlying Notch1 activation regulated by CDK5 remains unclear. Herein, we identified a physical interaction between CDK5 and Notch1 in PDAC cells, with the Notch1 peptide phosphorylated by CDK5/p25 kinase. CDK5 blockade resulted in the profound inhibition of Notch signaling. Accordingly, CDK5 inhibition sensitized PDAC cell proliferation and migration following Notch inhibition. In conclusion, CDK5 positively regulates Notch1 function via phosphorylation, which in turn promotes cell proliferation and migration. The combinational inhibition of CDK5 and Notch signaling may be an effective strategy in the treatment of PDAC.

Topics: Carcinoma, Pancreatic Ductal; Cell Line, Tumor; Cell Movement; Cell Proliferation; Cyclin-Dependent Kinase 5; Dipeptides; Gene Silencing; Humans; Immunoprecipitation; Pancreatic Neoplasms; Phosphorylation; Protein Kinase Inhibitors; Receptor, Notch1; RNA, Messenger; Roscovitine; Signal Transduction

To explore the effect of DAPT, a gamma-secretase inhibitor on the proliferation of pancreatic cancer cells and its underlying mechanism.. Three human pancreatic cancer cell lines as AsPC-1, BxPC-3 and MIAPaCa-2 were employed for in vitro experiments. Cell proliferation was tested by CCK-8 and cell apoptosis was examined by Annexin V/PI staining after the treatment of various concentrations of DAPT at different time.. DAPT of 100 micromol/L significantly inhibited the proliferation of these 3 cell lines from day 3 to 5. DAPT of 50 micromol/L inhibited the proliferation of BxPC-3 and MIAPaCa-2 cells from day 3 to 5, whereas the effect of inhibition was only observed at day 5 in AsPC-I cell. DAPT of 10 micromol/L inhibited the proliferation of BxPC-3 and MIAPaCa-2 cells at day 5, whereas no effect was found in AsPC-1. Flow cytometry test showed that cell apoptosis rate was higher in DAPT treatment groups compared with control group.. DAPT could suppress the proliferation of pancreatic cancer cell, with the mechanism of promoting cell apoptosis.

Topics: Amyloid Precursor Protein Secretases; Apoptosis; Cell Line, Tumor; Cell Proliferation; Dipeptides; Humans; Pancreatic Neoplasms; Receptors, Notch; Signal Transduction

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive disease with a high rate of metastasis. Recent studies have indicated that the Notch signalling pathway is important in PDAC initiation and maintenance, although the specific cell biological roles of the pathway remain to be established. Here we sought to examine this question in established pancreatic cancer cell lines using the γ-secretase inhibitor IX (GSI IX) to inactivate Notch. Based on the known roles of Notch in development and stem cell biology, we focused on effects on epithelial mesenchymal transition (EMT) and on pancreatic tumor initiating CD44+/EpCAM+ cells. We analyzed the effect of the GSI IX on growth and epithelial plasticity of human pancreatic cancer cell lines, and on the tumorigenicity of pancreatic tumor initiating CD44+/EpCAM+ cells. Notably, apoptosis was induced after GSI IX treatment and EMT markers were selectively targeted. Furthermore, under GSI IX treatment, decline in the growth of pancreatic tumor initiating CD44+/EpCAM+ cells was observed in vitro and in a xenograft mouse model. This study demonstrates a central role of Notch signalling pathway in pancreatic cancer pathogenesis and identifies an effective approach to inhibit selectively EMT and suppress tumorigenesis by eliminating pancreatic tumor initiating CD44+/EpCAM+ cells.

Topics: Adenocarcinoma; Amyloid Precursor Protein Secretases; Animals; Antigens, Neoplasm; Apoptosis; Biological Assay; Cell Adhesion Molecules; Cell Count; Cell Line, Tumor; Cell Movement; Dipeptides; Dose-Response Relationship, Drug; Epithelial Cell Adhesion Molecule; Epithelial-Mesenchymal Transition; Female; Gene Expression; Humans; Hyaluronan Receptors; Mice; Mice, Nude; Neoplasms, Experimental; Neoplastic Stem Cells; Pancreatic Neoplasms; Wound Healing

It was previously reported that γ-secretase inhibitors (GSIs) enhance taxane-induced mitotic arrest and apoptosis in colon cancer cells. To enable the development of taxane-based chemotherapy for pancreatic ductal adenocarcinoma (PDAC), this study investigated the molecular mechanisms by which γ-secretase (GS) complexes regulate taxane sensitivity.. The effect of GS complexes on taxane-induced apoptosis in PDAC cells was evaluated by a cell cycle analysis. GS complexes were examined with small interference RNAs targeted to GS complex-related genes.. GSIs and silencing of presenilin 1 (PS1) did not affect cell proliferation but resulted in enhanced taxane-induced G(2)/M accumulation and apoptosis. Silencing of the Notch gene did not induce these effects. However, PS2-specific silencing suppressed proliferation and taxane-induced apoptosis.. Data from this study indicate that GS complexes regulate the response of PDAC to taxanes through GS-dependent and GS-independent mechanisms.

Topics: Amyloid Precursor Protein Secretases; Apoptosis; Carcinoma, Pancreatic Ductal; Cell Cycle; Dipeptides; Drug Synergism; Enzyme Inhibitors; Humans; Pancreatic Neoplasms; Presenilin-1; Presenilin-2; Receptors, Notch; Signal Transduction; Taxoids