Tris(8-Hydroxyquinoline)iron induces apoptotic cell death via oxidative stress and by activating death receptor signaling pathway in human head and neck carcinoma cells

BACKGROUND

8-Hydroxyquinoline derivatives have highly sensitive fluorescent chemosensors for metal ions, which are associated with anti-oxidant, anti-tumor and anti-HIV-1 properties. Head and neck squamous cell carcinoma (HNSCC) is associated with a high rate of mortality and novel anti-HNSCC drugs must be developed. Therefore, effective chemotherapy agents are required to address this public health issue.

HYPOTHESIS/PURPOSE

The aim of this study was to investigate the inhibitory effect of tris(8-hydroxyquinoline)iron (Feq₃) on the HNSCC and the underlying mechanism.

STUDY DESIGN/METHODS

A novel 8-hydroxyquinoline derivative, Feq₃, was synthesized. The cell viabilities were analyzed using MTT reagent. Apoptosis and the cell cycle distributions were determined by flow cytometer. Reverse transcription-polymerase chain reaction (RT-PCR), immunofluorescence, western blot, MitoSOX and CellROX stain assay were used to study the mechanism of Feq₃. Feq₃ combined with antioxidants NAC (N-acetylcysteine) and BSO (buthionine sulfoximine) measured the cell viability and intracellular ROS.

RESULTS

Feq₃ induced the death of HNSCC cells and caused them to exhibit the morphological features of apoptosis. Feq₃ also induced apoptosis of SCC9 cells by cell cycle arrest during the G₂/M phase and the induced arrest of SCC25 cells in the G₀/G₁ and G₂/M phases, which was associated with decreased cyclin B1/cdc2 and cyclin D/cdk4 expressions. Feq₃ increases reactive oxygen species (ROS) and reduces glutathione (GSH) levels, and responds to increased p53 and p21 expressions. Feq₃ induced apoptosis by mitochondria-mediated Bax and cytochrome c up-expression and down-expression Bcl-2. Feq₃ also up-regulated tBid, which interacts with the mitochondrial pathway and tumor necrosis factor-α (TNF-α)/TNF-Rs, FasL/Fas, and TNF-related apoptosis inducing ligand receptors (TRAIL-Rs)/TRAIL-dependent caspases apoptotic signaling pathway in HNSCC cells. However, Feq₃ activates Fas but not FasL in SCC25 cells. Feq₃ arrests the growth of HNSCC cells and is involved in the mitochondria- and death receptor (DR)-mediated caspases apoptotic pathway.

CONCLUSION

This study is the first to suggest that apoptosis mediates the anti-HNSCC of Feq₃. Feq₃ has potential as a cancer therapeutic agent against HNSCC.