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Sensitivity of Ewing's sarcoma to TRAIL-induced apoptosis
H U Kontny1, K Hämmerle, R Klein
1Children's Hospital of the Albert-Ludwigs-University, Freiburg, Germany.
Abstract:
Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is able to kill transformed cells. We have studied the expression and functionality of the TRAIL apoptotic pathway in Ewing's sarcoma. We demonstrate that tumors from patients with Ewing's sarcoma express receptors TRAIL-R1 and -R2. Using a panel of nine Ewing's sarcoma cell lines TRAIL could induce apoptosis in seven cell lines. Preincubation with interferon-gamma rendered the two resistant cell lines sensitive. TRAIL was the most potent inducer of apoptosis when compared to Fas ligand or TNF. TRAIL-mediated apoptosis could be inhibited by various caspase-inhibitors. No difference in the surface expression of TRAIL-receptors was observed between sensitive and resistant cell lines. Also, all cell lines had similar levels of expression of Flice-like inhibitory protein (FLIP) on immunoblot. However, the two resistant cell lines had only very low level expression of caspase 8 on RNA and protein level. In summary, we show that Ewing's sarcoma expresses receptors for TRAIL, and that cells are exquisitely sensitive to TRAIL-mediated apoptosis. These results may warrant clinical trials with TRAIL in Ewing's sarcoma once the safety of TRAIL for humans has been established.
Insights
Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) effectively induces apoptosis in most Ewing sarcoma cells. This pathway shows promise for future cancer treatments, pending safety evaluations.
Area of Science:
- Oncology
- Molecular Biology
- Cell Death Research
Background:
- Ewing's sarcoma is a pediatric bone cancer with limited treatment options.
- The TRAIL (Tumor Necrosis Factor-Related Apoptosis-Inducing Ligand) pathway is known to induce apoptosis in cancer cells.
Purpose of the Study:
- To investigate the expression and function of the TRAIL apoptotic pathway in Ewing's sarcoma.
- To determine TRAIL's efficacy in inducing apoptosis in Ewing's sarcoma cell lines.
Main Methods:
- Analysis of TRAIL receptor (TRAIL-R1, TRAIL-R2) expression in Ewing's sarcoma tumors and cell lines.
- Treatment of Ewing's sarcoma cell lines with TRAIL and assessment of apoptosis induction.
- Evaluation of interferon-gamma's effect on TRAIL sensitivity.
- Comparison of TRAIL with Fas ligand and TNF in apoptosis induction.
- Investigation of caspase inhibitors, FLIP, and caspase 8 expression in resistant cell lines.
Main Results:
- Ewing's sarcoma tumors express TRAIL-R1 and TRAIL-R2.
- TRAIL induced apoptosis in 7 out of 9 Ewing's sarcoma cell lines.
- Interferon-gamma sensitized resistant cell lines to TRAIL.
- TRAIL was a more potent apoptosis inducer than Fas ligand or TNF.
- Resistant cell lines showed low expression of caspase 8, but similar FLIP levels and receptor expression compared to sensitive lines.
Conclusions:
- Ewing's sarcoma cells express functional TRAIL receptors.
- TRAIL is a potent inducer of apoptosis in Ewing's sarcoma, with potential therapeutic implications.
- Low caspase 8 expression may contribute to TRAIL resistance in some Ewing's sarcoma cells.