Dataset Information

Gene expression profile of colorectal cancer HCT116 cells treated with single (2Gy) or fractionated (5 x 2Gy) doses of ionizing radiation.

ABSTRACT: Radiotherapy remains a standard treatment for colorectal cancer. The clinical significance of the conventional treatment is based on accumulated dose and usually consists of single daily irradiations of 1.8 - 2 Gy fractions. However the repopulation of cancer cells during and/or after the treatment suggests that the surviving fraction of cells acquire the radioresistance to cancer therapy. It has been determined a number of radioresistance markers, but only limited data exist on the acquisition of the resistance to fractionated radiation therapy. This research provides the genomic data of gene expression changes in colorectal cancer cell HCT116 line following single and multiple fractions of irradiation, aiming to identify particular genes associated with the effect of fractionated radiotherapy.

ORGANISM(S): Homo sapiens

PROVIDER: GSE103178 | GEO | 2017/08/29

SECONDARY ACCESSION(S): PRJNA400451

REPOSITORIES: GEO

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Project description:Purpose: Predominant causes of head and neck cancer recurrence after radiotherapy are rapid repopulation, hypoxia, fraction of cancer stem cells and intrinsic radioresistance. Currently, intrinsic radioresistance can only be assessed by ex-vivo colony assays. Besides being time-consuming, colony assays do not identify causes of intrinsic resistance. We aimed to identify a biomarker for intrinsic radioresistance to be used before start of treatment and to reveal biological processes that could be targeted to overcome intrinsic resistance. Experimental design: We analyzed both micro- and messenger RNA expression in a large panel of HNSCC cell lines. Expression was measured on both irradiated and unirradiated samples. Results were validated using modified cell lines and a series of laryngeal cancer patients. Results: MiRs, mRNAs and gene sets that correlated with resistance could be identified from expression data of unirradiated cells. The presence of epithelial to mesenchymal transition (EMT) and low expression of miRs involved in the inhibition of EMT were important radioresistance determinants. This finding was validated in two independent cell line pairs, in which the induction of EMT reduced radiosensitivity. Moreover, low expression of the most important miR (miR-203) was shown to correlate with local disease recurrence after radiotherapy in a series of laryngeal cancer patients. Conclusions: These findings indicate that EMT and low expression of EMT-inhibiting miRs, especially miR-203, measured in pre-treatment material, causes intrinsic radioresistance of HNSCC, which could enable identification and treatment modification of radioresistant tumors. Matched pairs of pre-treatment biopsies of 34 patients treated at The Netherlands Cancer Institute between 2002 and 2010. Patients with T2-3 laryngeal cancers, all treated with radiotherapy alone with a curative intent. The series was designed to be a matched cohort of 17 patients with local recurrences matched with 17 local cures. There were no significant differences between groups with and without local recurrence in age, gender, subsite, T-stage or treatment year.

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 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.

Dataset Information

Gene expression profile of colorectal cancer HCT116 cells treated with single (2Gy) or fractionated (5 x 2Gy) doses of ionizing radiation.

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