Related Experiment Videos
Expression of the JAK and STAT superfamilies in human meningiomas
L Magrassi1, C De-Fraja, L Conti
1Neurosurgery Department, Policlinico San Matteo, and Institute of Pharmacology, University of Pavia, Italy.
Object:
The goal of this study was to investigate whether the janus kinase/signal transducer and activator of transcription (JAK/STAT) signal transduction pathway is present and active in meningiomas. The results of these investigations are important for all meningioma therapies that, similar to interferon-alpha-2B (IFNalpha-2B), depend on activation of this pathway for their effect. The authors were interested in evaluating the importance, if any, of the JAK/STAT pathway in the biology and therapy for these tumors.
Methods:
Total proteins were extracted from 17 meningioma samples and the levels of JAKs and STATs were determined by using Western blot analysis. Levels of these proteins in meningiomas were compared with those found in normal dura. The JAKs and STATs (with the exception of Jak3 and Tyk2) were present both in the dura and in the meningiomas studied. In tumors JAK and STAT levels were always significantly higher than those found in normal dura. Differences in relative levels were found when meningiomas were subdivided according to the current neuropathological criteria and the highest levels were found in transitional meningiomas. The authors also investigated, using tyrosine-phosphorylated Statl and Stat3 antibodies, whether STATs were activated in meningiomas and normal dura in vivo. Their results indicate that both Statl and Stat3 are phosphorylated in vivo in meningiomas and in the dura. Furthermore, in vitro experiments in which two independent short-term cultures obtained from freshly dissected meningioma samples were used indicated that Statl and Stat3 are phosphorylated in response to treatment with IFNalpha-2B. Exposure of meningioma cells to IFNalpha-2B leads to nuclear translocation of tyrosine-phosphorylated Statl and Stat3, as demonstrated by immunocytochemical analysis.
Conclusions:
The results of this study indicate that the JAK and STAT families of proteins are important effectors in brain tumors and support the idea that the effects of IFNalpha in vivo are direct and not mediated by the immune system. This suggests a role for modulation of STAT transcription factors in inhibiting meningioma cell proliferation.
Insights
The janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway is active in meningiomas, with elevated JAK and STAT protein levels. Interferon-alpha-2B directly activates this pathway in tumor cells, suggesting STAT modulation for meningioma therapy.
Area of Science:
- Neuro-oncology
- Molecular biology
- Signal transduction
Background:
- Meningiomas are the most common primary brain tumors.
- Therapies like interferon-alpha-2B (IFNalpha-2B) rely on the janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway.
- The role of the JAK/STAT pathway in meningioma biology and treatment is not fully understood.
Purpose of the Study:
- To determine if the JAK/STAT pathway is present and active in meningiomas.
- To evaluate the significance of the JAK/STAT pathway in meningioma development and treatment.
- To investigate the direct effects of IFNalpha-2B on meningioma cells via the JAK/STAT pathway.
Main Methods:
- Western blot analysis of JAK and STAT protein levels in 17 meningioma samples and normal dura.
- Immunohistochemical analysis of phosphorylated STAT1 and STAT3 in vivo.
- In vitro studies using meningioma cell cultures treated with IFNalpha-2B.
Main Results:
- JAK and STAT proteins were present in both dura and meningiomas, with significantly higher levels in tumors.
- STAT1 and STAT3 were phosphorylated in vivo in meningiomas and dura.
- IFNalpha-2B treatment induced STAT1 and STAT3 phosphorylation and nuclear translocation in meningioma cells.
Conclusions:
- The JAK/STAT pathway is active in meningiomas and plays a role in tumor biology.
- IFNalpha-2B directly affects meningioma cells through the JAK/STAT pathway.
- Modulating STAT transcription factors may be a viable therapeutic strategy for meningiomas.