Potentiation of TNF-mediated cell killing by mitoxantrone. Relationship to DNA single-strand break formation
M Valenti1, G Cimoli, G L Mariani
1Istituto Nazionale per la Ricerca sul Cancro, Genova, Italy.
Abstract:
Tumor necrosis factor (TNF) is a pleiotropic cytokine that mediates different cellular responses including cytotoxicity, cytostasis, proliferation, differentiation and expression of specific genes. Recent studies have demonstrated that chemotherapeutic drugs that inhibit the nuclear enzyme DNA topoisomerase II synergize with TNF in tumor cell killing in vitro and in vivo. We now report that a combination of TNF and the topoisomerase II inhibitor Mitoxantrone produced dose-dependent synergistic cytotoxicity against the human ovarian cancer cell line A2774 in a clonogenic assay (1 hr treatment). This result was obtained with simultaneous administration of the drug and the cytokine under test, and is independent of modification of Mitoxantrone uptake. This combination is responsible for an evident augmentation of "cleavable complex" formation. From isolated nuclei, we have isolated also the topoisomerase II activity; we observed an increment when the cells were previously treated with TNF, 2.5 min before nuclear extraction. After 10-30 min of treatment with TNF, the topoisomerase II activity returned to normal values. If TNF is not given with but 30 min before Mitoxantrone, no potentiation of cytotoxicity or break induction is observed. These results suggest that specific timing of the association may be needed also when attempting to translate it to animals and humans.
Insights
Combining Tumor Necrosis Factor (TNF) with Mitoxantrone enhances cancer cell killing. This synergy in ovarian cancer treatment depends on the precise timing of drug and cytokine administration for optimal results.
Area of Science:
- Oncology
- Molecular Biology
- Pharmacology
Background:
- Tumor Necrosis Factor (TNF) is a cytokine involved in various cellular processes.
- DNA topoisomerase II inhibitors can synergize with TNF in cancer cell killing.
- The precise mechanisms and timing of this synergy require further investigation.
Purpose of the Study:
- To investigate the synergistic effect of TNF and Mitoxantrone on ovarian cancer cells.
- To determine the impact of administration timing on the efficacy of this combination therapy.
- To explore the underlying molecular mechanisms, including cleavable complex formation and topoisomerase II activity.
Main Methods:
- Utilized a clonogenic assay to assess cytotoxicity of TNF and Mitoxantrone combination on A2774 human ovarian cancer cells.
- Investigated the effect of simultaneous and sequential administration of TNF and Mitoxantrone.
- Measured "cleavable complex" formation and topoisomerase II activity in isolated nuclei following TNF treatment.
Main Results:
- A dose-dependent synergistic cytotoxicity was observed when TNF and Mitoxantrone were administered simultaneously.
- The synergistic effect was independent of alterations in Mitoxantrone uptake.
- Simultaneous treatment significantly augmented "cleavable complex" formation and transiently increased topoisomerase II activity.
- Sequential administration (TNF 30 min before Mitoxantrone) did not yield similar potentiation.
Conclusions:
- Simultaneous administration of TNF and Mitoxantrone exhibits synergistic cytotoxicity against ovarian cancer cells.
- The timing of TNF administration is critical for achieving potentiation of cytotoxic effects and DNA damage.
- These findings highlight the importance of specific temporal sequencing for potential clinical translation of this combination therapy.
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