Osteosarcoma (OS) is the most common malignant bone
tumor occurring mostly in children and adolescents between 10 and 20 years of age with poor response to current
therapeutics.
Alisertib (ALS,
MLN8237) is a selective
Aurora kinase A inhibitor that displays anticancer effects on several types of
cancer. However, the role of ALS in the treatment of OS remains unknown. This study aimed to investigate the effects of ALS on the cell growth, apoptosis, autophagy, and epithelial to mesenchymal transition (EMT) and the underlying mechanisms in two human OS cell lines U-2 OS and MG-63. The results showed that ALS had potent growth inhibitory, pro-apoptotic, pro-autophagic, and EMT inhibitory effects on U-2 OS and MG-63 cells. ALS remarkably induced G2/M arrest and down-regulated the expression levels of
cyclin-dependent kinases 1 and 2 and
cyclin B1 in both U-2 OS and MG-63 cells. ALS markedly induced mitochondria-mediated apoptosis with a significant increase in the expression of key
pro-apoptotic proteins and a decrease in main
anti-apoptotic proteins. Furthermore, ALS promoted autophagic cell death via the inhibition of
phosphatidylinositol 3-kinase (PI3K)/
protein kinase B (Akt)/
mammalian target of rapamycin (mTOR) and
p38 mitogen-activated protein kinase (
p38 MAPK) signaling pathways, and activation of 5'-AMP-dependent
kinase (AMPK) signaling pathway. Inducers or inhibitors of apoptosis or autophagy simultaneously altered ALS-induced apoptotic and autophagic death in both U-2 OS and MG-63 cells, suggesting a crosstalk between these two primary modes of programmed cell death. Moreover, ALS suppressed EMT-like phenotypes with a marked increase in the expression of
E-cadherin but a decrease in
N-cadherin in U-2 OS and MG-63 cells. ALS treatment also induced
reactive oxygen species (ROS) generation but inhibited the expression levels of
sirtuin 1 and nuclear factor-erythroid-2-related factor 2 (Nrf2) in both cell lines. Taken together, these findings show that ALS promotes apoptosis and autophagy but inhibits EMT via PI3K/Akt/mTOR,
p38 MAPK, and AMPK signaling pathways with involvement of ROS- and
sirtuin 1-associated pathways in U-2 OS and MG-63 cells. ALS is a promising
anticancer agent in OS treatment and further studies are needed to confirm its efficacy and safety in OS
chemotherapy.