RabGEF1 functions as an oncogene in U251 glioblastoma cells and is involved in regulating AKT and Erk pathways

Background: RabGEF1 is a guanine-nucleotide exchange factor for RAB-5, which plays an oncogenic role in certain human cancers. However, the function of RabGEF1 in glioma has not been studied. Here, we report that the down-regulation of RabGEF1 inhibits the proliferation and metastasis, and induces Autophagy of U251 glioblastoma cells.

Methods: The expression of RabGEF1 in glioma and normal tissues were measured by immunohistochemistry. Four siRNAs targeting different sites of RabGEF1 were conducted and the interference efficiencies were verified by qRT-PCR assay. Western blot was used to detect the expression of interest proteins. Cell proliferation was detected using CCK-8 and clone formation assay. Cell migration and invasion were analyzed by scratch assay and transwell assay, respectively. Flow cytometry was used to detect cell cycle distribution and Apoptosis.

Results: RabGEF1 was significantly up-regulated in human glioma tissues. RabGEF1 knockdown reduced cell viability, induced cell cycle arrest and Apoptosis in U251 cells. Cell migration and invasion were also inhibited when RabGEF1 silencing. Mechanism studies showed that Cyclin D1 and CDK4/6 were significantly down-regulated when RabGEF1 silencing. p53 and Caspase mediated apoptotic pathway was activated by down-regulation of RabGEF1. Moreover, RabGEF1 knockdown also induced Autophagy in glioma cells. The investigation of Akt and ERK pathways suggested that phosphorylated Akt, p70S6K and phosphorylated ERK were all decreased when RabGEF1 silencing.

Conclusion: In conclusion, our data suggest that RabGEF1 is up-regulated in human glioma and down-regulation of RabGEF1 inhibited cell proliferation and metastasis, and induced Autophagy of U251 glioblastoma cells, which might be mediated by inactivation of Akt and ERK signaling pathways.