Objectives: Extracellular microenvironment plays crucial roles in the development of cancers and chemoresistance. Pancreatic carcinoma is resistant to almost all chemotherapeutic agents. In this study, we identified annexin II in the medium from pancreatic cancer cells as a protein released into the extracellular environment.
Methods: Medium from 5-hour cultures of various cancer cells was collected. Proteins in the medium were detected by molecular mass analysis and immunoblotting. Anticancer drug sensitivity of cells preincubated with or without recombinant annexin II (rANX II) was measured using crystal violet assay and colony survival assay. Apoptosis-related molecules were analyzed by immunoblotting.
Results: Recombinant ANX II supplementation in the medium confers resistance to anticancer drugs, including cisplatin, 5-fluorouracil, and gemcitabine, in MiaPaCa-2 and AsPC-1 cells. In MiaPaCa-2 cells, rANX II supplementation resulted in suppression of caspase-3 activation associated with increased Bcl-2/Bax ratios. Suppression of cisplatin-induced cell death by rANX II supplementation was canceled by inhibitors of phosphatidylinositol 3-kinase and mitogen-activated protein kinase kinase signal pathways.
Conclusions: The current study is the first report to demonstrate that supplementation of rANX II in the medium increased resistance to anticancer drugs in pancreatic cancer cells. Recombinant ANX II exerts cell death-suppressive function by antagonizing cisplatin-induced apoptosis.