Aberrant Glycogen Synthase Kinase 3β Is Involved in Pancreatic Cancer Cell Invasion and Resistance to Therapy

Background and Purpose: The major obstacles to treatment of pancreatic cancer are the highly invasive capacity and resistance to chemo- and radiotherapy. Glycogen synthase kinase 3β (GSK3β) regulates multiple cellular pathways and is implicated in various diseases including cancer. Here we investigate a pathological role for GSK3β in the invasive and treatment resistant phenotype of pancreatic cancer. Methods: Pancreatic cancer cells were examined for GSK3β expression, phosphorylation and activity using Western blotting and in vitro kinase assay. The effects of GSK3β inhibition on cancer cell survival, proliferation, invasive ability and susceptibility to gemcitabine and radiation were examined following treatment with a pharmacological inhibitor or by RNA interference. Effects of GSK3β inhibition on cancer cell xenografts were also examined. Results: Pancreatic cancer cells showed higher expression and activity of GSK3β than non-neoplastic cells, which were associated with changes in its differential phosphorylation. Inhibition of GSK3β significantly reduced the proliferation and survival of cancer cells, sensitized them to gemcitabine and ionizing radiation, and attenuated their migration and invasion. These effects were associated with decreases in cyclin D1 expression and Rb phosphorylation. Inhibition of GSK3β also altered the subcellular localization of Rac1 and F-actin and the cellular microarchitecture, including lamellipodia. Coincident with these changes were the reduced secretion of matrix metalloproteinase-2 (MMP-2) and decreased phosphorylation of focal adhesion kinase (FAK). The effects of GSK3β inhibition on tumor invasion, susceptibility to gemcitabine, MMP-2 expression and FAK phosphorylation were observed in tumor xenografts. Conclusion: The targeting of GSK3β represents an effective strategy to overcome the dual challenges of invasiveness and treatment resistance in pancreatic cancer. © 2013 Kitano et al

Aberrant glycogen synthase kinase 3β in the development of pancreatic cancer

Development and progression of pancreatic cancer involves general metabolic disorder, local chronic inflammation, and multistep activation of distinct oncogenic molecular pathways. These pathologic processes result in a highly invasive and metastatic tumor phenotype that is a major obstacle to curative surgical intervention, infusional gemcitabine-based chemotherapy, and radiation therapy. Many clinical trials with chemical compounds and therapeutic antibodies targeting growth factors, angiogenic factors, and matrix metalloproteinases have failed to demonstrate definitive therapeutic benefits to refractory pancreatic cancer patients. Glycogen synthase kinase 3β (GSK3β), a serine/threonine protein kinase, has emerged as a therapeutic target in common chronic and progressive diseases, including cancer. Here we review accumulating evidence for a pathologic role of GSK3β in promoting tumor cell survival, proliferation, invasion, and resistance to chemotherapy and radiation in pancreatic cancer. We also discuss the putative involvement of GSK3β in mediating metabolic disorder, local inflammation, and molecular alteration leading to pancreatic cancer development. Taken together, we highlight potential therapeutic as well as preventive effects of GSK3β inhibition in pancreatic cancer

IL-1 beta augments H2S-induced increase in intracellular Ca2+ through polysulfides generated from H2S/NO interaction

H2S has excitatory and inhibitory effects on Ca2+ signals via transient receptor potential ankyrin 1 (TRPA1) and ATP-sensitive K+ channels, respectively. H2S converts intracellularly to polysulfides, which are more potent agonists for TRPA1 than H2S. Under inflammatory conditions, changes in the expression and activity of these H2S target channels and/or the conversion of H2S to polysulfides may modulate H2S effects. Effects of proinflammatory cytokines on H2S-induced Ca2+ signals and polysulfide production in RIN14B cells were examined using fluorescence imaging with fura-2 and SSP4, respectively. Na2S, a H2S donor, induced 1) the inhibition of spontaneous Ca2+ signals, 2) inhibition followed by [Ca2+](i) increase, and 3) rapid [Ca2+](i) increase without inhibition in 50% (23/46), 22% (10/46), and 17% (8/46) of cells tested, respectively. IL-1 beta augmented H2S-induced [Ca2+](i) increases, which were inhibited by TRPA1 and voltage-dependent L-type Ca2+ channel blockers. However, IL-1 beta treatment did not affect [Ca2+](i) increases evoked by a TRPA1 agonist or high concentration of KCl. Na2S increased intracellular polysulfide levels, which were enhanced by IL-1 beta treatment. A NOS inhibitor suppressed the increased polysulfide production and [Ca2+](i) increase in IL-1 beta-treated cells. These results suggest that IL-1 beta augments H2S-induced [Ca2+](i) increases via the conversion of H2S to polysulfides through NO synthesis, but not via changes in the activity and expression of target channels. Polysulfides may play an important role in the effects of H2S during inflammation

Breaking-type lodging resistance and culm morphologies of selected lines.

<p>(A) Breaking-type lodging resistance evaluated in terms of bending moment at breaking. Data are means ± SD (n> = 3). The fourth internodes of MT-6 and MT-8 could not be evaluated due to short internode lengths. (B) Magnified view of the third internode cross-section of 7 lines showing high bending-moment-at-breaking value in comparison with original cultivars (T65, Nipponbare, and Kinmaze). Bar = 500 µm. (C) Relative culm thickness of each line. Thickness of the original cultivars is set as 1. Data are means ± SD (n> = 3). The uppermost to fourth internodes were measured.</p