Ectopic overexpression of GRK5 promotes malignant glioma progression closely associated with MSN-CD44 expression and glioma localization

Abstract Background Gliomas are highly invasive and lack of effective targeted therapy. GRK5 is involved in several pathologic conditions including cancer. GRK5 phosphorylated MSN on T66 and regulated the subcellular distribution of MSN, which was a glioma progression marker that induces proliferation via interaction with CD44. Therefore, targeting GRK5-MSN-CD44 may provide a novel approach for the treatment of gliomas. Materials and methods GRK5-knockdown and GRK5-upregulated glioma cell lines were generated by using the lentivirus transfection method. The GRK5 and MSN expression and the association with the malignant characters in glioma were determined by Western blot and qRT-PCR. By using double-immunofluorescence and triple immunofluorescence analysis, the subcellular localization and distribution characteristics of GRK5-MSN-CD44 in gliomas were detected. The cell proliferation, migration, invasion and apoptosis were determined by CCK-8 assay, wound healing assay, transwell assay and flow cytometry respectively. Results GRK5 expression was up-regulated in human gliomas and positively correlated with MSN expression. GRK5-MSN and MSN-CD44 were found co-expressed in gliomas respectively. GRK5-MSN-CD44 were co-localized in the membrane of glioma cell and abundant in glioma stem cell niches. VEGF and N-cadherin expressions were increased/decreased according to the up-regulation/down-regulation of GRK5. And Bax expression showed decreased/increased according to GRK5 over-expression/low-expression. The proliferation, migration and invasion of glioma cells were improved due to the upregulation of GRK5. And the apoptosis of glioma cells was decreased/increased due to the up-regulation/down-regulation of GRK5. Conclusion Ectopic overexpression of GRK5 promoted the malignant progression of glioma and is closely related to MSN-CD44 interaction. GRK5-MSN-CD44 provides a new idea for gene targeted therapy of glioma.