The scavenging of superoxide radicals promotes apoptosis induced by a novel cell-permeable fusion protein, sTRAIL:FeSOD, in tumor necrosis factor-related apoptosis-inducing ligand-resistant leukemia cells.

Abstract

BACKGROUND:

Many cancer cells develop resistance to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis, necessitating combination with chemotherapy, and normal cells manifest side effects due to the combined treatment regimen of TRAIL and chemotherapeutic drugs. A novel cancer therapy utilizing TRAIL is thus urgently needed.

RESULTS:

In this study, we exploited TRAIL receptor-mediated endocytosis for the first time to produce a cell-permeable molecule, soluble forms of recombinant TRAIL:iron superoxide dismutase (sTRAIL:FeSOD), which possesses sTRAIL-induced apoptotic ability and FeSOD antioxidant activity. The FeSOD component was rapidly introduced into the cell by sTRAIL and intracellular superoxide radical (O2-), which have been implicated as potential modulators of apoptosis in cancer cells, was eliminated, resulting in a highly reduced cellular environment. The decrease in cellular O2-, which was accompanied by a brief accumulation of H2O2 and downregulation of phosphorylated Akt (p-Akt) and cellular FLICE-inhibitory protein, sensitized K562 leukemia cells and human promyelocytic leukemia (HL-60) cells to TRAIL-induced apoptosis. The low H2O2 levels protected human LO2 hepatocytes from sTRAIL:FeSOD-induced apoptosis despite downregulation of p-Akt. We also obtained evidence that the lack of response to sTRAIL:FeSOD in normal T cells occurred because sTRAIL:FeSOD shows much stronger shifts of redox state in erythroleukemia (K562) and HL-60 cells compared to that in normal T cells. K562 and HL-60 cells underwent sTRAIL:FeSOD-induced apoptosis without the dysfunction of mitochondria.

CONCLUSIONS:

The fusion protein overcomes the inability of FeSOD to permeate the cell membrane, exhibits synergistic apoptotic effects on K562 and HL-60 cells and demonstrates minimal toxicity to normal T cells and the normal liver cell line LO2, indicating its potential value for the treatment of leukemia.

• Authors: Hongyun Tang, Yong Qin, Jianyong Li, Xingguo Gong
• Journal: BMC biology (BMC Biol) Vol. 9 Pg. 18 (Mar 19 2011) ISSN: 1741-7007 [Electronic] England
• PMID: 21418589 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Receptors, TNF-Related Apoptosis-Inducing Ligand
• Recombinant Fusion Proteins
• TNF-Related Apoptosis-Inducing Ligand
• TNFRSF10A protein, human
• Tumor Necrosis Factor-alpha
• Superoxides
• Hydrogen Peroxide
• Superoxide Dismutase
• Proto-Oncogene Proteins c-akt

Topics

• Apoptosis (drug effects)
• HL-60 Cells
• Humans
• Hydrogen Peroxide (metabolism)
• K562 Cells
• Proto-Oncogene Proteins c-akt (metabolism)
• Receptors, TNF-Related Apoptosis-Inducing Ligand (metabolism)
• Recombinant Fusion Proteins (pharmacology)
• Superoxide Dismutase (pharmacology)
• Superoxides (metabolism)
• TNF-Related Apoptosis-Inducing Ligand (pharmacology)
• Tumor Necrosis Factor-alpha (pharmacology)