ABSTRACT
Pancreatic cancer is the fourth leading cause of cancer-related death in the western countries and it is resistant to almost all cytotoxic drugs. In the current study, we explored the gemcitabine resistance induced by the interaction between Annexin A2 (ANXA2) and alternatively spliced segment of tenascin-C (TNfnA-D). In the pancreatic cancer cell culture system in vitro, it was proved that exogenous recombinant TNfnA-D combined with the cell surface ANXA2 specifically and their interaction suppressed gemcitabine-induced cytotoxicity on pancreatic cancer cells in a dose-dependent manner. Meanwhile, the TNfnA-D/ANXA2 interaction increased the phosphorylation of phosphatidylinositol 3-kinase (PI3K), Akt, inhibitory kappaB (IkappaB) kinase alpha/beta (IKKalpha/beta), IkappaBalpha, and p65 nuclear factor-kappaB (NF-kappaB) significantly. Inhibition of Akt and PI3K with their specific inhibitors partially reversed the suppression of gemcitabine-induced cytotoxicity elicited by TNfnA-D/ANXA2 interaction. Activation of p65 NF-kappaB was dependent on the phosphorylation of PI3K/Akt. The phosphorylated IKKalpha/beta induced the phosphorylation and degradation of IkappaBalpha, the sequential phosphorylation, nuclear translocation and activation of p65 NF-kappaB. Pyrrolidine dithiocarbamate (PDTC) effectively blocked the activity of p65 NF-kappaB in response to TNfnA-D. Down-regulation of p65 NF-kappaB with its specific small interfering RNA (siRNA) restored the gemcitabine-induced cytotoxicity suppressed by TNfnA-D/ANXA2 interaction. For the first time, this study show that ANXA2/TNfnA-D interaction induced gemcitabine resistance via the canonical PI3K/Akt/NF-kappaB signaling pathways in pancreatic cancer cells. Therefore, therapy targeting ANXA2/TNfnA-D and/or p65 NF-kappaB may have potential clinical application for patients with pancreatic cancers.
Subject(s)
Alternative Splicing , Annexin A2/biosynthesis , Antimetabolites, Antineoplastic/pharmacology , Deoxycytidine/analogs & derivatives , Drug Resistance, Neoplasm , Pancreatic Neoplasms/pathology , Tenascin/biosynthesis , Annexin A2/genetics , Blotting, Western , Cell Culture Techniques , Cell Line, Tumor , Cell Proliferation/drug effects , Deoxycytidine/pharmacology , Dose-Response Relationship, Drug , Down-Regulation , Drug Resistance, Neoplasm/genetics , Flow Cytometry , Humans , Pancreatic Neoplasms/genetics , Pancreatic Neoplasms/metabolism , Phosphorylation , Promoter Regions, Genetic , Protein Binding , RNA, Small Interfering/genetics , Recombinant Proteins/biosynthesis , Recombinant Proteins/genetics , Tenascin/genetics , Transcription Factor RelA/biosynthesis , GemcitabineABSTRACT
Recent studies have demonstrated that pancreatic adenocarcinoma cells require hedgehog (HH) signaling for proliferation and survival. Mutations in the smoothened (SMOH) gene and loss-of-function mutations in the patched (PTCH) gene, which are involved in the HH signaling pathway, may cause pancreatic tumors. Since HH signaling pathway may contribute to the induction and maintenance of pancreatic tumors, the use of HH pathway inhibitors for targeting the pancreatic cancer might represent a novel therapeutic approach to advanced pancreatic carcinoma. Among the HH inhibitors, cyclopamine inhibits HH signaling through direct interaction with SMOH and retards the growth of cancer cells by inhibiting stem cells. Novel therapies that target the HH signaling pathway should become one of the more effective treatments for pancreatic cancer, which cannot be cured with current therapies.
