Overexpression of the cytoprotective protein clusterin decreases radiosensitivity in the human LNCaP prostate tumour model

BJU Int. 2003 Sep;92(4):463-9. doi: 10.1046/j.1464-410x.2003.04349.x.


Objective: To evaluate the effect of clusterin overexpression on radiation-induced tumour growth rates and apoptosis in human prostate LNCaP cells, as prostate cancer cells are relatively resistant to radiation-induced apoptosis and local recurrences are common, but overexpression of the anti-apoptotic protein clusterin can accelerate progression to androgen-independence and to confer a chemoresistant phenotype in various prostate cancer models.

Materials and methods: Western blot analysis and immunohistochemistry were used to compare clusterin expression levels in parental (P) and clusterin-transfected (T) LNCaP cells in vitro and in vivo. The effects of radiation on clusterin-expression in both parental LNCaP/P and clusterin-transfected LNCaP/T tumours were analysed by Northern blot analysis. The cellular response to radiation was determined up to 3 weeks after irradiation using tetrazolium and re-growth assays, and cell-cycle analysis by flow cytometry.

Results: Clusterin mRNA expression increased from undetectable to low levels in LNCaP/P tumours after radiation and more than three-fold in LNCaP/T tumours. Clusterin overexpression decreased the radiosensitivity in a time-dependent manner, reducing the extent of growth arrest and apoptosis by up to 54%. Re-growth assays showed that the improved survival rates of LNCaP/T cells after radiation did not change after 3 days, remaining constant over 3 weeks.

Conclusions: These results identify clusterin as a promoter of cell survival that may help mediate resistance to radiation-induced apoptosis. Furthermore, clusterin overexpression seems to provide an extended protection against radiation-induced cell cycle arrest and apoptosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis / radiation effects*
  • Blotting, Northern
  • Blotting, Western
  • Cell Division / radiation effects
  • Clusterin
  • Flow Cytometry
  • Glycoproteins / metabolism*
  • Humans
  • Immunohistochemistry
  • Male
  • Molecular Chaperones / metabolism*
  • Neoplasm Proteins / metabolism*
  • Prostatic Neoplasms / metabolism*
  • Prostatic Neoplasms / pathology
  • Prostatic Neoplasms / radiotherapy
  • RNA, Messenger / metabolism
  • Tumor Cells, Cultured


  • CLU protein, human
  • Clusterin
  • Glycoproteins
  • Molecular Chaperones
  • Neoplasm Proteins
  • RNA, Messenger