X-radiation induces non-small-cell lung cancer apoptosis by upregulation of Axin expression

Int J Radiat Oncol Biol Phys. 2009 Oct 1;75(2):518-26. doi: 10.1016/j.ijrobp.2009.05.040.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenocarcinoma / metabolism
  • Adenocarcinoma / pathology
  • Adenocarcinoma / radiotherapy
  • Adult
  • Aged
  • Apoptosis / physiology*
  • Axin Protein
  • Biomarkers, Tumor / metabolism*
  • Carcinoma, Non-Small-Cell Lung / metabolism
  • Carcinoma, Non-Small-Cell Lung / pathology
  • Carcinoma, Non-Small-Cell Lung / radiotherapy*
  • Carcinoma, Squamous Cell / metabolism
  • Carcinoma, Squamous Cell / pathology
  • Carcinoma, Squamous Cell / radiotherapy
  • Caspase 3 / metabolism
  • Cell Line, Tumor
  • Female
  • Flow Cytometry
  • Humans
  • In Situ Nick-End Labeling
  • Lung Neoplasms / metabolism
  • Lung Neoplasms / pathology
  • Lung Neoplasms / radiotherapy*
  • MAP Kinase Kinase 4 / antagonists & inhibitors
  • MAP Kinase Kinase 4 / metabolism
  • Male
  • Middle Aged
  • Radiation Tolerance / physiology*
  • Repressor Proteins / metabolism*
  • Reverse Transcriptase Polymerase Chain Reaction / methods
  • Tumor Suppressor Protein p53 / analysis
  • Tumor Suppressor Protein p53 / metabolism
  • Up-Regulation


  • Axin Protein
  • Biomarkers, Tumor
  • Repressor Proteins
  • Tumor Suppressor Protein p53
  • MAP Kinase Kinase 4
  • Caspase 3