Ionizing radiation can overcome resistance to TRAIL in TRAIL-resistant cancer cells

Mi Ra Kim, Jeong Yim Lee, Moon Taek Park, Yong Jin Chun, Young Joo Jang, Chang Mo Kang, Hye Sun Kim, Chul Koo Cho, Yun Sil Lee, Hee Young Jeong, Su Jae Lee

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47 Scopus citations


Although the majority of cancer cells are killed by TRAIL (tumor necrosis factor-related apoptosis-inducing ligand treatment), certain types show resistance to it. Ionizing radiation also induces cell death in cancer cells and may share common intracellular pathways with TRAIL leading to apoptosis. In the present study, we examined whether ionizing radiation could overcome TRAIL resistance in the variant Jurkat clones. We first selected TRAIL-resistant or -sensitive Jurkat clones and examined cross-responsiveness of the clones between TRAIL and radiation. Treatment with γ-radiation induced significant apoptosis in all the clones, indicating that there seemed to be no cross-resistance between TRAIL and radiation. Combined treatment of radiation with TRAIL synergistically enhanced killing of TRAIL-resistant cells, compared to TRAIL or radiation alone. Apoptosis induced by combined treatment of TRAIL and radiation in TRAIL-resistant cells was associated with cleavage of caspase-8 and the proapoptotic Bid protein, resulting in the activation of caspase-9 and caspase-3. No changes in the expressions of TRAIL receptors (DR4 and DR5) and Bcl-2 or Bax were found after treatment. The caspase inhibitor z-VAD-fmk completely counteracted the synergistic cell killing induced by combined treatment of TRAIL and γ-radiation. These results demonstrated that ionizing radiation in combination with TRAIL could overcome resistance to TRAIL in TRAIL-resistant cells through TRAIL receptor-independent synergistic activation of the cascades of the caspase-8 pathway, suggesting a potential clinical application of combination treatment of TRAIL and ionizing radiation to TRAIL-resistant cancer cells.

Original languageEnglish
Pages (from-to)179-184
Number of pages6
JournalFEBS Letters
Issue number1
StatePublished - 7 Sep 2001

Bibliographical note

Funding Information:
We thank Dr. Byung-Ha Oh in POSTECH, South Korea, for kindly providing recombinant TRAIL. This work was supported by a Nuclear R&D Program from the Ministry of Science and Technology in Korea.


  • Ionizing radiation
  • Synergistic cell killing
  • TRAIL receptor-independent
  • Tumor necrosis factor-related apoptosis-inducing ligand resistance


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