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TPK inhibitors differentially affect IFN-gamma activities
M Aharon1, I Ben Valid, A Dvilansky
1Department of Hematology, Soroka University Hospital of Kupat Holim, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel.
Abstract:
The effect of various tyrosine protein kinase inhibitors on processes involved in the antiproliferative effect of interferon-gamma on WISH cells was studied. Following 24 hr treatment interferon-gamma inhibited thymidine incorporation into DNA and thymidine kinase activity, but no significant effect on cell number was observed. The isoflavonoid, genistein, which is a specific inhibitor of tyrosine protein kinase, reversed the inhibition in thymidine incorporation caused by the cytokine in a dose dependent manner. Prunetin, a member of the same group, did not significantly antagonize this effect. N alpha-tosyl-L-lysyl-chloromethane, a serine protease inhibitor which also serves as a tyrosine protein kinase inhibitor, partially reversed the effect of interferon-gamma at a concentration of 100 microM. The bioflavonoid, quercetin, a non-specific tyrosine protein kinase inhibitor, at a concentration of 30 microM completely abolished the action of interferon-gamma on thymidine incorporation. Genistein completely reversed the inhibition of thymidine kinase exerted by interferon, while quercetin had only a slight effect. However, the drugs could not antagonize the antiproliferative effect of interferon following 48 hr incubation, as measured by reduction of cell number. The results indicate that tyrosine protein kinase may play a role in the effects of interferon on thymidine metabolism and thymidine kinase activity. The differential effects of the inhibitors on thymidine metabolism and cell proliferation could support dissociation between the effect of interferon-gamma on these processes. Alternatively, this dissociation of effects could point to the limited use of inhibitors in clarifying modes of action as described.
Insights
Tyrosine protein kinase inhibitors like genistein and quercetin affected interferon-gamma
Area of Science:
- Cell Biology
- Biochemistry
- Molecular Pharmacology
Background:
- Interferon-gamma (IFN-γ) is a cytokine with antiproliferative effects.
- Tyrosine protein kinases (TPKs) are key signaling enzymes involved in cellular processes.
- The precise role of TPKs in IFN-γ's antiproliferative mechanisms remains incompletely understood.
Purpose of the Study:
- To investigate the impact of various TPK inhibitors on IFN-γ-induced antiproliferative effects in WISH cells.
- To elucidate the involvement of TPKs in IFN-γ's modulation of DNA synthesis and thymidine kinase activity.
- To explore the potential dissociation between IFN-γ's effects on cellular metabolism and proliferation.
Main Methods:
- WISH cells were treated with IFN-γ and various TPK inhibitors, including genistein, prunetin, N-α-tosyl-L-lysyl-chloromethane, and quercetin.
- Assays were performed to measure thymidine incorporation into DNA, thymidine kinase activity, and cell number.
- Inhibitor effects were evaluated at different concentrations and time points (24 hr and 48 hr).
Main Results:
- IFN-γ (24 hr) inhibited thymidine incorporation and thymidine kinase activity, but not cell number.
- Genistein and quercetin dose-dependently reversed IFN-γ's inhibition of thymidine incorporation.
- Genistein fully reversed thymidine kinase inhibition by IFN-γ, while quercetin had a minimal effect.
- None of the tested inhibitors antagonized the antiproliferative effect (cell number reduction) of IFN-γ after 48 hr.
Conclusions:
- TPKs likely play a role in mediating IFN-γ's effects on thymidine metabolism and thymidine kinase activity.
- The differential impact of inhibitors on thymidine metabolism versus cell proliferation suggests a potential dissociation of IFN-γ's actions.
- These findings highlight the complexity of using TPK inhibitors to fully clarify cytokine signaling pathways.