The critical role of EGF-β-catenin signaling in the epithelial-mesenchymal transition in human glioblastoma

To date, beta-catenin has been reported to be implicated in mediating the epithelial-mesenchymal transition (EMT) in a variety of human cancers, which can be triggered by EGF. However, the mechanisms underlying EGF-beta-catenin pathway-induced EMT of glioblastoma multiforme (GBM) have not been reported previously. In the present study, immunohistochemistry, reverse transcription polymerase chain reaction, and Western blot were applied to investigate the effect of EGF-beta-catenin pathway on EMT of GBM. Here, we identified that beta-catenin mRNA and protein levels were up-regulated in GBM tissues and four kinds of glioblastoma cell lines, including T98G, A172, U87, and U251 cells, compared with normal brain tissue and astrocytes. In U87 cell line, inhibition of beta-catenin by siRNA suppressed EGFinduced proliferation, migration, invasiveness, and the expression of EMT activators (Snail and Slug). In addition, the expression of epithelial markers (E-cadherin) was up-regulated and the expression of mesenchymal markers (N-cadherin and MMP9) was down-regulated. Finally, inhibitor of PI3K/Akt signaling pathways inactivated the EGF-beta-catenin-induced EMT. In conclusion, beta-catenin-EMT pathway induced by EGF is important for GBM progression by the PI3K/Akt pathways. Inhibition of beta-catenin leads to suppression of EGF pathway-induced EMT, which provides a new way to treat GBM patients.