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Apoptotic inhibition of head and neck squamous cell carcinoma cells by tumor necrosis factor alpha
1Division of Head and Neck Surgery, University of California, Los Angeles, USA.
Objectives:
To evaluate the effect and mechanism of action of tumor necrosis factor alpha (TNF-alpha) on head and neck squamous cell carcinoma (HNSCC) cell lines. Specifically, to find out whether TNF-alpha induces apoptotic (programmed) cell death.
Design:
Cytotoxicity and kinetics were evaluated through the use of a methylene blue colorimetric assay. The mechanism of cell death was evaluated through gel electrophoresis of extracted DNA, double-stranded DNA fragmentation, and Hoechst 33342-propidium iodide double staining. TARGET CELLS: Four HNSCC cell lines were investigated: UMSCC-1, UMSCC-8, UMSCC-19, and CAL-27.
Results:
Tumor necrosis factor alpha at a concentration of 10000 U/mL induced cytotoxic effects in all four cell lines with varying sensitivities. Significant cytotoxic effects required 3 to 4 days of exposure to TNF-alpha. Further experiments demonstrated that TNF-alpha induced double-stranded DNA fragmentation of targets, which preceded the detection of actual cytotoxic effects. Treated HNSCC cell lines had their DNA fragmented into a ladder pattern of endonucleolytic cleavage of multiples of 180 to 200 base pairs, consistent with apoptosis. Propidium iodide-Hoechst 33342 double staining confirmed that TNF-alpha-induced nuclear alterations precede permeabilization of the plasma membrane, supporting cell death in these tumor cells by apoptosis.
Conclusion:
Tumor necrosis factor alpha exposure results in variable cytotoxic reactions in HNSCC cell lines, with DNA fragmentation preceding significant cell death. The mechanism of cell death is apoptosis, with typical morphological features. Further studies are needed to better elucidate the role of TNF-alpha in the treatment of in vivo HNSCC.
Insights
Tumor necrosis factor alpha (TNF-alpha) induces apoptosis, or programmed cell death, in head and neck squamous cell carcinoma (HNSCC) cell lines. DNA fragmentation, a key indicator of apoptosis, was observed before significant cell death occurred.
Area of Science:
- Oncology
- Cell Biology
- Molecular Biology
Background:
- Head and neck squamous cell carcinoma (HNSCC) is a significant global health concern.
- Understanding the molecular mechanisms driving HNSCC progression is crucial for developing effective therapies.
- Tumor necrosis factor alpha (TNF-alpha) is a cytokine with known roles in inflammation and cell death, but its specific effects on HNSCC require detailed investigation.
Purpose of the Study:
- To investigate the cytotoxic effects of TNF-alpha on HNSCC cell lines.
- To elucidate the mechanism of action of TNF-alpha in HNSCC, specifically its role in inducing apoptosis.
- To determine the kinetics and dose-dependency of TNF-alpha-induced cell death in HNSCC.
Main Methods:
- Utilized methylene blue colorimetric assay for cytotoxicity and kinetic evaluation.
- Assessed the mechanism of cell death via DNA gel electrophoresis and fragmentation analysis.
- Employed Hoechst 33342-propidium iodide double staining to visualize nuclear alterations and cell viability.
- Tested four HNSCC cell lines: UMSCC-1, UMSCC-8, UMSCC-19, and CAL-27.
Main Results:
- TNF-alpha at 10000 U/mL exhibited cytotoxic effects across all four HNSCC cell lines, with varying sensitivities.
- Significant cytotoxic effects were observed after 3 to 4 days of TNF-alpha exposure.
- TNF-alpha induced double-stranded DNA fragmentation, characterized by a ladder pattern of 180-200 base pair fragments, indicative of apoptosis.
- Nuclear alterations consistent with apoptosis preceded plasma membrane permeabilization.
Conclusions:
- TNF-alpha induces apoptosis in HNSCC cell lines, evidenced by DNA fragmentation and characteristic morphological changes.
- The cytotoxic response to TNF-alpha varies among different HNSCC cell lines.
- Further research is warranted to explore the therapeutic potential of TNF-alpha in treating in vivo HNSCC.