Synergistic enhancement of TRAIL- and tumor necrosis factorα-induced cell death by a phenoxazine derivative

Keiichi Hara, Mayumi Okamoto, Toshihiko Aki, Hideo Yagita, Hirotoshi Tanaka, Yoichi Mizukami, Hiroshi Nakamura, Akio Tomoda, Naotaka Hamasaki, Dongchon Kang

Research output: Contribution to journalArticlepeer-review

23 Citations (Scopus)


2-Amino-4,4α-dihydro-4α,7-dimethyl-3H-phenoxazine-3-one (Phx-1) has been developed as a novel phenoxazine derivative having an anticancer activity on a variety of cancer cell lines as well as transplanted tumors in mice with minimal toxicity to normal cells. We examined the effects of Phx-1 on Jurkat cells, a human T cell line. Phx-1 inhibited proliferation of the cells in a dose-dependent manner but hardly induced cell death, suggesting that Phx-1 acts primarily as an antiproliferative reagent but not as a cytocidal drug. Phx-1 enhanced tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptotic cell death about 100-fold. Tumor necrosis factor α, which alone does not induce cell death of Jurkat cells, caused apoptosis in combination with Phx-1. These enhancements of cell death were not due to up-regulation of the death receptors. Phx-1 decreased serum-induced phosphorylation of Akt, a kinase involved in cell proliferation and survival, and inhibited complex III of mitochondrial respiratory chain. Considering that both TRAIL and Phx-1 have only marginal cytotoxicity to most normal cells, Phx-1 may provide an ideal combination for cancer therapy with TRAIL.

Original languageEnglish
Pages (from-to)1121-1127
Number of pages7
JournalMolecular cancer therapeutics
Issue number7
Publication statusPublished - Jul 2005

All Science Journal Classification (ASJC) codes

  • Oncology
  • Cancer Research


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