1. αB-crystallin is elevated in highly infiltrative apoptosis-resistant glioblastoma cells.
- Author
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Goplen D, Bougnaud S, Rajcevic U, Bøe SO, Skaftnesmo KO, Voges J, Enger PØ, Wang J, Tysnes BB, Laerum OD, Niclou S, and Bjerkvig R
- Subjects
- Animals, Blotting, Western, Brain metabolism, Brain pathology, Cell Adhesion, Cell Proliferation, Electrophoresis, Gel, Two-Dimensional, Fluorescent Antibody Technique, Gene Expression Regulation, Neoplastic, Humans, Immunoenzyme Techniques, RNA, Messenger genetics, RNA, Small Interfering genetics, Rats, Rats, Nude, Reverse Transcriptase Polymerase Chain Reaction, Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization, Spheroids, Cellular metabolism, Spheroids, Cellular pathology, TNF-Related Apoptosis-Inducing Ligand metabolism, Tissue Array Analysis, Transplantation, Heterologous, Tumor Cells, Cultured, alpha-Crystallin B Chain antagonists & inhibitors, alpha-Crystallin B Chain genetics, Apoptosis, Cell Movement, Glioblastoma metabolism, Glioblastoma pathology, alpha-Crystallin B Chain metabolism
- Abstract
We have previously established two distinct glioma phenotypes by serial xenotransplantation of human glioblastoma (GBM) biopsies in nude rats. These tumors undergo a gradual transition from a highly invasive nonangiogenic to a less-invasive angiogenic phenotype. In a protein screen to identify molecular markers associated with the infiltrative phenotype, we identified α-basic-crystallin (αBc), a small heat-shock protein with cytoprotective properties. Its increased expression in the infiltrative phenotype was validated by immunohistochemistry and Western blots, confirming its identity to be tumor-derived and not from the host. Stereotactic human GBM biopsies taken from MRI-defined areas verified stronger αBc expression in the infiltrative edge compared to the tumor core. Cell migration assays and immunofluorescence staining showed αBc to be expressed by migrating cells in vitro. To determine αBc function, we altered its expression levels. αBc siRNA depletion caused a loss of migrating tumor cells from biopsy spheroids and delayed monolayer wound closure. In contrast, glioma cell migration in a Boyden chamber assay was unaffected by either αBc knockdown or overexpression, indicating that αBc is not functionally linked to the cell migration machinery. However, after siRNA αBc depletion, a significant sensitization of cells to various apoptotic inducers was observed (actinomycin, tumor necrosis factor α, and TNF-related apoptosis-inducing ligand [TRAIL]). In conclusion, αBc is overexpressed by highly migratory glioma cells where it plays a functional role in apoptosis resistance.
- Published
- 2010
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