lithium-chloride and Pancreatic-Neoplasms

Our previous studies showed that while lithium suppresses proliferation and induces apoptosis in pancreatic cancer cells, the inhibition of exchange proteins directly activated by cyclic adenosine monophosphate (cAMP) (EPAC)1 blocks pancreatic cancer cell migration and invasion. In this study, we further investigated the combinatory effects of lithium and EPAC-specific inhibitor (ESI)-09, an EPAC-specific inhibitor, on pancreatic cancer cell proliferation and viability, and explored whether lithium synergistically cooperates with EPAC inhibition in suppressing pancreatic cancer cell tumorigenicity. The cell viability of pancreatic cancer cell lines PANC-1 and MiaPaCa-2 was measured after 48 h of incubation with different dose combination of lithium and ESI-09. Flow cytometric analysis was carried out to further verify the impact of lithium and ESI-09 upon PANC-1 cell proliferation and apoptosis. To investigate the mechanism that the effects generated by lithium and ESI-09 on PANC-1 cells, the intracellular cAMP level was measured by an ELISA-based cAMP immunoassay. Our data showed that lithium and ESI-09 synergistically inhibit pancreatic cancer cell growth and survival. Furthermore, our results revealed a novel mechanism in which the synergism between lithium and ESI-09 is not mediated by the inhibitory effect of lithium toward GSK3β, but by lithium's ability to suppress cAMP/protein kinase A signaling.

Topics: Apoptosis; Cell Line, Tumor; Cell Proliferation; Cell Survival; Cyclic AMP; Drug Synergism; Glycogen Synthase Kinase 3 beta; Guanine Nucleotide Exchange Factors; Humans; Hydrazones; Isoxazoles; Lithium Chloride; Pancreatic Neoplasms; Pyridines; Pyrimidines

Hedgehog signaling pathway plays a critical role in the initiation and development of pancreatic ductal adenocarcinoma (PDA) and represents an attractive target for PDA treatment. Lithium, a clinical mood stabilizer for mental disorders, potently inhibits the activity of glycogen synthase kinase 3β (GSK3β) that promotes the ubiquitin-dependent proteasome degradation of GLI1, an important downstream component of hedgehog signaling. Herein, we report that lithium inhibits cell proliferation, blocks G1/S cell-cycle progression, induces cell apoptosis and suppresses tumorigenic potential of PDA cells through down-regulation of the expression and activity of GLI1. Moreover, lithium synergistically enhances the anti-cancer effect of gemcitabine. These findings further our knowledge of mechanisms of action for lithium and provide a potentially new therapeutic strategy for PDA through targeting GLI1.

Topics: Antineoplastic Agents; Apoptosis; Carcinoma, Pancreatic Ductal; Cell Line, Tumor; Cell Proliferation; Deoxycytidine; Dose-Response Relationship, Drug; Drug Synergism; G1 Phase Cell Cycle Checkpoints; Gemcitabine; Gene Expression Regulation, Neoplastic; Glycogen Synthase Kinase 3; Glycogen Synthase Kinase 3 beta; Humans; Lithium Chloride; Pancreatic Neoplasms; Proteasome Endopeptidase Complex; Proteolysis; Signal Transduction; Transcription Factors; Zinc Finger Protein GLI1

ZM336372 is small molecule tyrosine kinase modulator. It has been shown to inhibit glycogen synthase kinase-3beta (GSK-3beta) through phosphorylation of GSK-3beta at Ser 9. GSK-3beta has previously been shown to mediate cell survival in pancreatic cancer cells. Here we determine the effects of ZM336372 on GSK-3beta phosphorylation, apoptosis, and growth in pancreatic adenocarcinoma cell lines.. Panc-1 and MiaPaCa-2 cells were treated with ZM336372 or lithium chloride (LiCl) and compared with solvent control. The effects on proliferation for each cell line were determined using the MTT assay. Western blot analysis was performed to examine the effects of treatment on the phosphorylation of GSK-3beta. In addition, western blot was utilized to examine the cleavage of poly (ADP-ribose) polymerase (PARP), a marker of apoptosis.. A dose-dependent increase in phosphorylation of GSK-3beta was observed after treatment with both ZM336372 and LiCl. Growth inhibition due to treatment with ZM336372 and LiCl also occurred in a dose-dependent fashion. An increase in cleaved PARP was demonstrated after treatment with both agents, as was seen previously with GSK-3beta inhibition in pancreatic adenocarcinoma cells.. This is the first description of growth inhibition and apoptosis in pancreatic cancer cells related to GSK-3beta inhibition through treatment with ZM336372.

Topics: Adenocarcinoma; Apoptosis; Benzamides; Cell Line, Tumor; Cell Proliferation; Drug Evaluation, Preclinical; Glycogen Synthase Kinase 3; Glycogen Synthase Kinase 3 beta; Humans; Lithium Chloride; Pancreatic Neoplasms; Phosphorylation; Poly(ADP-ribose) Polymerases