Identification of novel NRAGE involved in the radioresistance of esophageal cancer cells

Abstract

Radiotherapy (RT) is one main method for the treatment of esophageal squamous cell carcinoma (ESCC), and the radioresistance is the predominant cause of patients with local recurrence. The previous results of gene microarray and subsequent verification showed that NRAGE might be involved in radiation resistance of ESCC cells. In this study, we reestablished human esophageal carcinoma radioresistant cell lines TE13R120 and ECA109R60 with gradient dose irradiation as previously reported, respectively. NRAGE expression was high in TE13R120 and ECA109R60 cells and was correlative with ionizing radiation (IR) resistance in clinic. However, the radiosensitivity of TE13R120 cells had a remarkable increase detected by colony formation assays after siRNA against NRAGE (siNRG) transfection into TE13R120 cells. Compared with TE13 cells, an increasing number of TE13R120 cells with NRAGE overexpression in S phase and a lower ratio in G2/M were observed by flow cytometry method (FCM). Intriguingly, the above changes were partially reversed in TE13R120 cells treated with siNRG. More importantly, the ectopic subcellular localization of NRAGE mediated nuclear translocation of β-catenin which may be one reason of IR resistance of esophageal carcinoma cell. These data indicate that NRAGE extremely may be a pivotal factor involved in Wnt/β-catenin signal pathway, mediating nuclear translocation of β-catenin and then facilitating the formation of radioresistance of ESCC.

NRAGE, a potential biomarker, induces radioresistance in two- and three-dimensional culture and confers poor prognosis in esophageal squamous cell carcinoma

“…Experimental analyses were conducted as described previously [11] , [23] and detailed in Supplementary materials and methods.…”

“…Our previous studies indicated that NRAGE was upregulated in ESCC radioresistant cells and extremely likely to be an RT-related critical factor [11,19,24]. Inadequately, there was lack of direct evidence to con rm the effect of NRAGE on resistancepromoting to IR.…”

“…Given its diverse cellular functions, NRAGE is deemed to be greatly crucial in cancer development and progression. Current researchers reported that there were complex and apparently controversial functions on different tumors' progression, metastasis, and invasion [11,12]. Initially, NRAGE was reported as a cancer suppressor gene, which promotes cell apoptosis via binding to P75NTR [13], Che-1 [14], XIAP-TAK1-TAB1 [15], and UNC5H1 [16] and inhibits proliferation [17] and angiogenesis [18].…”

“…Initially, NRAGE was reported as a cancer suppressor gene, which promotes cell apoptosis via binding to P75NTR [13], Che-1 [14], XIAP-TAK1-TAB1 [15], and UNC5H1 [16] and inhibits proliferation [17] and angiogenesis [18]. Contradictorily, functions such as pro-apoptotic gene and growth promotion were slowly discovered [9,11,[19][20][21][22]. Kodera et al [21] found that increased NRAGE expression affects the malignant phenotype of HCC via its interaction with AATF.…”

“…Originally, our previous studies indicated that NRAGE was signi cantly overexpressed in the nucleus of ESCC cells with radioresistance [19] and knockdown NRAGE has signi cantly enhanced radiosensitivity in established radioresistant ESCC cells [11]. Scantily, there were only instantaneous intervention at constructed radioresistant EC cells cultured in the 2D level and no correlation with OS of ESCC.…”