Variations in the levels of the JAK/STAT and ShcA proteins in human brain tumors

Background: Recent demonstrations that the JAK/STAT and ShcA signalling proteins are abundant in the developing CNS at the stage of maximal cell proliferation prompted us to determine whether these proteins were expressed in various human brain tumors. Materials and Methods: Using Western blot assay, we analyzed specimens from control peritumoral brain tissue, medulloblastomas, ependimomas, astrocytomas, anaplastic astrocytomas and glioblastomas. Results: Our analyses revealed that Jak1 and Stat3 were consistently more elevated in low grade gliomas (LG) (tumors characterized by a more pronounced glial phenotype) as compared to high grade gliomas (HG) (less differentiated glial tumors). The other STAT proteins were equally expressed, while Stat1 was slightly higher in LG gliomas. Among the other tumors analyzed, medulloblastoma contained the highest level of Jak1 and Stat3, while ependymoma showed elevated levels of ShcA proteins. Conclusions: These differences may reflect differences in the biological characteristics of the various tumors and may provide insight for further mechanistic studies to investigate the importance of particular signal transduction pathways in CNS tumors.