Acquired 5-Fluorouracil Resistance in Human Pancreatic Carcinoma Cells. A Paradigm for Chemoresistance Mechanisms in Pancreatic Cancer

摘要

Context Pancreatic ductaladenocarcinoma is a dismal disease with one of the worst prognoses amongstsolid tumors. Its ability to develop chemoresistance mechanisms towardscytotoxic drugs is the main cause of treatment failure. Objective Here,we have established a drug-resistance model for pancreatic cancer in whichCapan-1 pancreatic carcinoma cells (designated Capan-1 5-FU2000) acquired 5-fluorouracil(5-FU) resistance and were used as a paradigm to reveal alterations inintracellular signaling cascades that. Those alterations may contribute to thecircumvention of apoptosis during the course of the disease, culminating intreatment failure. Methods We made use of 2-D-gelelectrophoresis, mass-spectrometry,sandwich-ELISA and western blotting to compare the proteomic expressionpatterns of respective mediators involved in pro- and antiapoptotic as well asinflammatory processes in both cell lines. An ATP-based chemosensitivity assayvalidated the chemoresistant phenotype of the Capan-1 5-FU2000 clones. ResultsWe detected specific changes in our resistant cell clones in particular adecreased expression of S100A4. We also found a decreased basal phosphorylationof SAPK/JNK and P38. The expression of the pro-apoptotic mediators Bok and Badwas down- and up-regulated in these cells, respectively. In case of NfkB p65and IkB-alpha treatment with 5-FU (2,000 μg/mL for 96 h) markedly inducedphosphorylation in native Capan-1 cells. In contrast in resistant clones itdecreased phosphorylation of NfkB p65 and did not affect IkB-alpha phosphorylation.Basal phosphorylation of S6-ribosomal-protein was markedly increased inresistant clones, treatment with 5-FU decreased this phosphorylation, while innative Capan-1 cells it was vice versa. Conclusion Thus we can concludethat several pathways were found to be altered in chemoresistant Capan-15-FU2000 cells. Moreover these alterations are most likely the consequence of amultistep adaption towards gradual cytotoxic exposure finally culminating in achemoresistant phenotype. Interfering with these pathways may possibly reversethe phenotype and thus open up alternative treatment options.