Curcumin confers radiosensitizing effect in prostate cancer cell line PC-3

Oncogene. 2004 Feb 26;23(8):1599-607. doi: 10.1038/sj.onc.1207284.


Curcumin (Diferuloylmethane) is a major chemical component of turmeric (curcuma longa) and is used as a spice to give a specific flavor and yellow color in Asian food. Curcumin exhibits growth inhibitory effects in a broad range of tumors as well as in TPA-induced skin tumors in mice. This study was undertaken to investigate the radiosensitizing effects of curcumin in p53 mutant prostate cancer cell line PC-3. Compared to cells that were irradiated alone (SF(2)=0.635; D(0)=231 cGy), curcumin at 2 and 4 microM concentrations in combination with radiation showed significant enhancement to radiation-induced clonogenic inhibition (SF(2)=0.224: D(0)=97 cGy and SF(2)=0.080: D(0)=38 cGy) and apoptosis. It has been reported that curcumin inhibits TNF-alpha-induced NFkappaB activity that is essential for Bcl-2 protein induction. In PC-3 cells, radiation upregulated TNF-alpha protein leading to an increase in NFkappaB activity resulting in the induction of Bcl-2 protein. However, curcumin in combination with radiation treated showed inhibition of TNF-alpha-mediated NFkappaB activity resulting in bcl-2 protein downregulation. Bax protein levels remained constant in these cells after radiation or curcumin plus radiation treatments. However, the downregulation of Bcl-2 and no changes in Bax protein levels in curcumin plus radiation-treated PC-3 cells, together, altered the Bcl2 : Bax ratio and this caused the enhanced radiosensitization effect. In addition, significant activation of cytochrome c and caspase-9 and -3 were observed in curcumin plus radiation treatments. Together, these mechanisms strongly suggest that the natural compound curcumin is a potent radiosesitizer, and it acts by overcoming the effects of radiation-induced prosurvival gene expression in prostate cancer.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Apoptosis / radiation effects
  • Caspases / genetics
  • Caspases / metabolism
  • Cell Line, Tumor
  • Combined Modality Therapy
  • Curcumin / pharmacology*
  • Cyclin D1 / antagonists & inhibitors
  • Cyclin D1 / radiation effects
  • Cytochromes c / metabolism
  • Dose-Response Relationship, Drug
  • Dose-Response Relationship, Radiation
  • Gene Expression Regulation, Neoplastic / radiation effects
  • Humans
  • Male
  • NF-kappa B / drug effects
  • NF-kappa B / radiation effects
  • Prostatic Neoplasms / genetics
  • Prostatic Neoplasms / metabolism
  • Prostatic Neoplasms / radiotherapy*
  • Radiation Tolerance*
  • Radiation, Ionizing
  • Radiation-Sensitizing Agents / pharmacology*
  • Tumor Necrosis Factor-alpha / pharmacology


  • NF-kappa B
  • Radiation-Sensitizing Agents
  • Tumor Necrosis Factor-alpha
  • Cyclin D1
  • Cytochromes c
  • Caspases
  • Curcumin