PURPOSE: Axis inhibition (Axin) is an important negative regulator of the Wnt pathway. This study investigated the relationship between Axin expression and sensitivity to X-rays in non-small-cell lung cancer (NSCLC) to find a useful indicator of radiosensitivity. METHODS AND MATERIALS: Tissue from NSCLC patients, A549 cells, and BE1 cells expressing Axin were exposed to 1-Gy of X-radiation. Axin and p53 expression levels were detected by immunohistochemistry and reverse transcription-PCR. Apoptosis was determined by TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling) assay and FACS (fluorescence-activate cell sorter) analysis. Caspase-3 activity was determined by Western blotting. Phospho-JNK expression was determined by immunofluorescence. RESULTS: The expression of Axin was significantly lower in NSCLC tissues than in normal lung tissues (p < 0.05). Axin expression correlates with differentiation, TNM staging, and lymph node metastasis of NSCLC (p < 0.05). Its expression negatively correlates with the expression of p53(mt) (p=0.000) and positively correlates with apoptosis (p=0.002). The prognosis of patients with high expression of Axin was better than those with low expression. X-radiation increases Axin expression in NSCLC tissue, and caspase-3 is significantly higher in samples in which Axin is increased (p < 0.05). Both X-radiation and Axin induce apoptosis of A549 and BE1 cells; however, the combination of the two enhances the apoptotic effect (p < 0.05). In A549 cells, inhibition of p53 blocks Axin-induced apoptosis, whereas in BE1 cells, the JNK pathway is required. CONCLUSIONS: Axin induces the p53 apoptotic pathway in cells where this pathway is intact; however, in cells expressing p53(mt), Axin induces apoptosis via the JNK pathway. Elevated Axin expression following X-ray exposure is a reliable indicator for determining the radiosensitivity of NSCLC.
PURPOSE: Axis inhibition (Axin) is an important negative regulator of the Wnt pathway. This study investigated the relationship between Axin expression and sensitivity to X-rays in non-small-cell lung cancer (NSCLC) to find a useful indicator of radiosensitivity. METHODS AND MATERIALS: Tissue from NSCLCpatients, A549 cells, and BE1 cells expressing Axin were exposed to 1-Gy of X-radiation. Axin and p53 expression levels were detected by immunohistochemistry and reverse transcription-PCR. Apoptosis was determined by TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling) assay and FACS (fluorescence-activate cell sorter) analysis. Caspase-3 activity was determined by Western blotting. Phospho-JNK expression was determined by immunofluorescence. RESULTS: The expression of Axin was significantly lower in NSCLC tissues than in normal lung tissues (p < 0.05). Axin expression correlates with differentiation, TNM staging, and lymph node metastasis of NSCLC (p < 0.05). Its expression negatively correlates with the expression of p53(mt) (p=0.000) and positively correlates with apoptosis (p=0.002). The prognosis of patients with high expression of Axin was better than those with low expression. X-radiation increases Axin expression in NSCLC tissue, and caspase-3 is significantly higher in samples in which Axin is increased (p < 0.05). Both X-radiation and Axin induce apoptosis of A549 and BE1 cells; however, the combination of the two enhances the apoptotic effect (p < 0.05). In A549 cells, inhibition of p53 blocks Axin-induced apoptosis, whereas in BE1 cells, the JNK pathway is required. CONCLUSIONS:Axin induces the p53 apoptotic pathway in cells where this pathway is intact; however, in cells expressing p53(mt), Axin induces apoptosis via the JNK pathway. Elevated Axin expression following X-ray exposure is a reliable indicator for determining the radiosensitivity of NSCLC.
Authors: H Mizugaki; J Sakakibara-Konishi; Y Ikezawa; J Kikuchi; E Kikuchi; S Oizumi; T P Dang; M Nishimura Journal: Br J Cancer Date: 2012-05-17 Impact factor: 7.640