Parthenolide sensitizes cells to X-ray-induced cell killing through inhibition of NF-κB and split-dose repair

Marc S. Mendonca, Helen Chin-Sinex, Jaime Gomez-Millan, Nicholas Datzman, Michael Hardacre, Kathleen Comerford, Harikrishna Nakshatri, Monica Nye, Laura Benjamin, Sachin Mehta, Fatima Patino, Christopher Sweeney

Research output: Contribution to journalArticlepeer-review

32 Scopus citations


Human cancers have multiple alterations in cell signaling pathways that promote resistance to cytotoxic therapy such as X rays. Parthenolide is a sesquiterpene lactone that has been shown to inhibit several pro-survival cell signaling pathways, induce apoptosis, and enhance chemotherapy-induced cell killing. We investigated whether parthenolide would enhance X-ray-induced cell killing in radiation resistant, NF-κB-activated CGL1 cells. Treatment with 5 μM parthenolide for 48 to 72 h inhibited constitutive NF-κB binding and cell growth, reduced plating efficiency, and induced apoptosis through stabilization of p53 (TP53), induction of the pro-apoptosis protein BAX, and phosphorylation of BID. Parthenolide also enhanced radiation-induced cell killing, increasing the X-ray sensitivity of CGL1 cells by a dose modification factor of 1.6. Flow cytometry revealed that parthenolide reduced the percentage of X-ray-resistant S-phase cells due to induction of p21waf1/cip1 (CDKN1A) and the onset of G1/S and G2/M blocks, but depletion of radioresistant S-phase cells does not explain the observed X-ray sensitization. Further studies demonstrated that the enhancement of X-ray-induced cell killing by parthenolide is due to inhibition of split-dose repair.

Original languageEnglish (US)
Pages (from-to)689-697
Number of pages9
JournalRadiation research
Issue number6
StatePublished - Dec 1 2007

ASJC Scopus subject areas

  • Biophysics
  • Radiation
  • Radiology Nuclear Medicine and imaging

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