Upregulation of CD73 Confers Acquired Radioresistance and Is Required for Maintaining EMT in the Pancreatic Cancer Cells that Survive Fractionated Irradiation

ABSTRACT: The molecular mechanisms underlying exceptional radioresistance in pancreatic cancer remain elusive. In the present study, we established a stable radioresistant pancreatic cancer cell line MIA PaCa-2-R by exposing the parental MIA PaCa-2 cells to fractionated ionizing radiation (IR). Systematic proteomics and bioinformatics comparison of protein expression in MIA PaCa-2 and MIA PaCa-2-R cells revealed that several growth factor- and cytokine-mediated pathways, including the OSM/STAT3, PI3K/AKT and MAPK/ERK pathways, were activated in the radioresistant cells, leading to enhanced cell migration, invasion and epithelial-mesenchymal transition (EMT), and inhibition of apoptosis. We focused functional analysis on one of the most upregulated proteins in the radioresistant cells, CD73, which is a cell surface protein that is overexpressed in a variety types of cancer. Ectopic overexpression of CD73 in the parent cells resulted in radioresistance and conferred resistance to IR-induced apoptosis. Knockdown of CD73 resensitized the radioresistant cells to IR and IR-induced apoptosis. The effect of CD73 on radioresistance and apoptosis is independent of the enzymatic activity of CD73. Further studies suggest that CD73 confers acquired radioresistance in pancreatic cancer cells at least in part through inactivating proapoptotic protein BAD via phosphorylation of BAD at Ser-136. Furthermore, we found that knockdown of CD73 in the radioresistant cells alone reverted the gene expression and phenotype of the radioresistant cells from those of mesenchymal-like cells to the ones of epithelial cells, demonstrating that CD73 upregulation is required for maintaining EMT in the radioresistant cells. Our results support the notion that the enhanced growth factor/cytokine signaling that promotes epithelial-mesenchymal plasticity, and acquisition of cancer stem-like cell properties contributes to acquired radioresistance in the residual surviving cells after fractionated irradiation, and that CD73 is a novel downstream factor of those enhanced signaling and acts to confers acquired radioresistance and maintains EMT in the radioresistant pancreatic cancer cells.

INSTRUMENT(S): LTQ Orbitrap

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Epithelial Cell, Cell Culture

DISEASE(S): Carcinoma

SUBMITTER: Yuchun Du  

LAB HEAD: Yuchun Du

PROVIDER: PXD012922 | Pride | 2019-12-31

REPOSITORIES: Pride