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STAT1 is overexpressed in tumors selected for radioresistance and confers protection from radiation in transduced sensitive cells.

ABSTRACT: Nu61, a radiation-resistant human tumor xenograft, was selected from a parental radiosensitive tumor SCC-61 by eight serial cycles of passage in athymic nude mice and in vivo irradiation. Replicate DNA array experiments identified 52 genes differentially expressed in nu61 tumors compared with SCC-61 tumors. Of these, 19 genes were in the IFN-signaling pathway and moreover, 25 of the 52 genes were inducible by IFN in the nu61 cell line. Among the genes involved in IFN signaling, STAT1alpha and STAT1beta were the most highly overexpressed in nu61 compared to SCC-61. STAT1alpha and STAT1beta cDNAs were cloned and stably transfected into SCC-61 tumor cells. Clones of SCC-61 tumor cells transfected with vectors expressing STAT1alpha and STAT1beta demonstrated radioprotection after exposure to 3 Gy (P < 0.038). The results indicate that radioresistance acquired during radiotherapy treatment may account for some treatment failures and demonstrate an association of acquired tumor radioresistance with up-regulation of components of the IFN-related signaling pathway.

SUBMITTER: Khodarev NN

PROVIDER: S-EPMC341831 | biostudies-literature | 2004 Feb

REPOSITORIES: biostudies-literature

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STAT1 is overexpressed in tumors selected for radioresistance and confers protection from radiation in transduced sensitive cells.

Khodarev Nikolai N NN Beckett Michael M Labay Edwardine E Darga Thomas T Roizman Bernard B Weichselbaum Ralph R RR

Proceedings of the National Academy of Sciences of the United States of America 20040130 6

Nu61, a radiation-resistant human tumor xenograft, was selected from a parental radiosensitive tumor SCC-61 by eight serial cycles of passage in athymic nude mice and in vivo irradiation. Replicate DNA array experiments identified 52 genes differentially expressed in nu61 tumors compared with SCC-61 tumors. Of these, 19 genes were in the IFN-signaling pathway and moreover, 25 of the 52 genes were inducible by IFN in the nu61 cell line. Among the genes involved in IFN signaling, STAT1alpha and ST ...[more]

PMID: 14755057

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Project description: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 analysis of protein expression in MIA PaCa-2 and MIA PaCa-2-R cells revealed that several growth factor-/cytokine-mediated pathways, including the OSM/STAT3, PI3K/AKT, and MAPK/ERK pathways, were activated in the radioresistant cells, leading to inhibition of apoptosis and increased epithelial-mesenchymal plasticity. In addition, the radioresistant cells exhibited enhanced capabilities of DNA repair and antioxidant defense compared with the parental cells. We focused functional analysis on one of the most up-regulated proteins in the radioresistant cells, ecto-5'-nucleotidase (CD73), which is a cell surface protein that is overexpressed in different types of cancer. Ectopic overexpression of CD73 in the parental cells resulted in radioresistance and conferred resistance to IR-induced apoptosis. Knockdown of CD73 re-sensitized 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 demonstrate that CD73 up-regulation promotes Ser-136 phosphorylation of the proapoptotic protein BAD and is required for maintaining the radioresistant cells in a mesenchymal state. Our findings suggest that expression alterations in the IR-selected pancreatic cancer cells result in hyperactivation of the growth factor/cytokine signaling that promotes epithelial-mesenchymal plasticity and enhancement of DNA repair. Our results also suggest that CD73, potentially a novel downstream factor of the enhanced growth factor/cytokine signaling, confers acquired radioresistance by inactivating proapoptotic protein BAD via phosphorylation of BAD at Ser-136 and by maintaining the radioresistant pancreatic cancer cells in a mesenchymal state.

Dataset Information

STAT1 is overexpressed in tumors selected for radioresistance and confers protection from radiation in transduced sensitive cells.

Publications

STAT1 is overexpressed in tumors selected for radioresistance and confers protection from radiation in transduced sensitive cells.

Similar Datasets

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