Abstract:

Objective To detect the expression of Ether à go-go（Eag） in human osteosarcoma and examine possible pathways regulating Eag expression. Methods Eag expression was analyzed in the osteosarcoma cell line MG-63 using reverse transcription-polymerase chain reaction and western blotting. Effects of Eag inhibition on cell proliferation were examined in MG-63 cultures， and effects of short hairpin RNA-mediated knockdown of Eag on osteosarcoma growth were examined in an in vivo xenograft model. Activation of the mitogen-activated protein kinase（MAPK）/p53 signaling pathway in MG-63 cells was detected using Western blot analysis. Results Eag is overexpressed in MG-63 cells， and imipramine or Eag short hairpin RNA significantly inhibited MG-63 proliferation in vitro and in vivo. MG-63 proliferation was also strongly inhibited by the p38 MAPK inhibitor SB203580 or small interfering RNA （siRNA）. Using SB203580 or siRNA to inhibit p38 MAPK activation reduced levels of Eag protein but increased levels of p53 protein. Using nutlin-3 to activate p53 reduced levels of Eag protein and arrested MG-63 growth， while using pifithrin-alpha to inactivate p53 increased the levels of Eag and promoted MG-63 growth. Conclusion The Eag gene functions as an oncogene to promote the proliferation of osteosarcoma cells，and the p38 MAPK/p53 pathway regulates high Eag expression in osteosarcoma cells.

Key words: Bone neoplasm, Ether à, go-go, Cell proliferation, MAPK pathway, p53 gene, Regulation, Expression