Bortezomib-enhanced radiosensitization through the suppression of radiation-induced nuclear factor-κB activity in human oral cancer cells

Tetsuya Tamatani, Natsumi Takamaru, Kanae Hara, Makoto Kinouchi, Nobuyuki Kuribayashi, Go Ohe, Daisuke Uchida, Kenji Fujisawa, Hirokazu Nagai, Youji Miyamoto

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)


Oral cancer cells have a significantly augmented nuclear factor-κB (NF-κB) activity and the inhibition of this activity suppresses tumor growth. Bortezomib is a proteasome inhibitor and a drug used for molecular-targeted therapy (targets NF-κB). In this study, we investigated whether bortezomib would be effective as an inhibitor of proliferation and a radiosensitizer for the treatment of oral cancer. We demonstrate that bortezomib inhibits NF-κB activity and cell proliferation. The combined treatment with bortezomib and radiation (RT) suppressed NF-κB activity and cell growth in vitro and in vivo compared with RT treatment alone. To investigate the mechanisms by which bortezomib suppresses tumor growth, the expression of signaling molecules downstream of NF-κB were examined by ELISA. The combined treatment significantly inhibited the radiation-induced production of angiogenic factors and decreased the number of blood vessels in the tumor tissues. Although the expression of anti-apoptotic proteins was upregulated by RT, bortezomib downregulated the RT-induced expression of these proteins. Moreover, the expression of cleaved poly(ADP-ribose) polymerase in vitro and in vivo was enhanced by bortezomib, indicating that bortezomib inhibits tumor growth by inducing apoptosis. This study clearly demonstrates that bortezomib significantly inhibits tumor growth and that the combined treatment with bortezomib and RT results in a significant inhibition of tumor growth. The mechanisms underlying the inhibition of tumor growth by bortezomib include the suppression of angiogenesis and the induction of apoptosis. A novel molecular targeting therapy including bortezomib may be effective in the treatment of oral cancer by suppressing NF-κB activity.

Original languageEnglish
Pages (from-to)935-944
Number of pages10
JournalInternational journal of oncology
Issue number3
Publication statusPublished - 2013 Mar
Externally publishedYes


  • Bortezomib
  • Nuclear factor-κB
  • Oral cancer

ASJC Scopus subject areas

  • Oncology
  • Cancer Research


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