Abstract: Objective To investigate the effect of overexpression of the oncogenic transcription factor ELF4 on proliferation and apoptosis in human insulinoma cells and explore the underlying mechanism. Methods A human insulinoma BON cell line with stable overexpression of ELF4 (BON-ELF4 cells) was constructed using a recombinant retrovirus vector and the expression of ELF4 protein was verified using Western blotting. MTT assay was used to assess the proliferation of BON-ELF4 cells and BON-Vector cells, and the cell apoptosis induced by treatment with epirubicin (0.1 μmol/L for 24 h) was analyzed by detecting the expressions of cleaved caspase-8, caspase-9, and PARP using Western blotting. Flow cytometry with Annexin V-FITC/PI staining was performed to analyze the numbers of apoptotic BON-Vector or BON-ELF4 cells. The expressions of phosphorylated Akt and total Akt in the cells were detected using Western blotting. Results BON-ELF4 cell line with stable overexpression of ELF4 was successfully established. ELF4 overexpression significantly promoted the proliferation (P<0.05) and obviously suppressed epirubicin-induced apoptosis in BON cells, resulting also in significantly reduced expressions of cleaved caspase-8, caspase-9 and PARP (P<0.05). The results of flow cytometry showed a significantly lower apoptotic rate in BON-ELF4 cells than in BON-Vector cells following epirubicin treatment (6.03% vs 22.90%). The phosphorylation levels of Akt (Thr308 and Ser473) were significantly increased (P<0.05) while the level of total Akt remained unchanged (P>0.05) in ELF4-overexpressing cells. Conclusion ELF4 overexpression enhances the proliferation and suppresses apoptosis of insulinomas cells by activating Akt signaling.

Key words: ELF4; insulinoma cells; Akt signaling pathway