Autophagy induced by suberoylanilide hydroxamic acid in Hela S3 cells involves inhibition of protein kinase B and up-regulation of Beclin 1

Histone deacetylase inhibitors are promising chemotherapeutic agents and some are in clinical trials. Several molecular mechanisms have been invoked to describe their effects on cancer cells in vivo and in vitro. Autophagy has been observed in response to several anticancer reagents and has been demonstrated to be responsible for cell death. However, the exact mechanism of this phenomenon is still not clear. Here we demonstrated that suberoylanilide hydroxamic acid, a histone deacetylase inhibitor, induces nonapoptotic cell death with several specific features characteristic of autophagy in Hela S3 cells. Suberoylanilide hydroxamic acid inhibits the activity of the mammalian target of rapamycin, a negative regulator of macroautophagy which induces the formation of autophagosomes in a Beclin 1- and autophagy-related 7-dependent manner. This process is mediated by Akt and tuberous sclerosis 2 as is demonstrated by inhibition by continuous active Akt plasmid transfection and RNA interference of tuberous sclerosis 2. Our data provide the first evidence that suberoylanilide hydroxamic acid induces autophagy in Hela S3 cells through interference with the mammalian target of rapamycin signaling pathway. These findings suggest that suberoylanilide hydroxamic acid may induce autophagic cancer cell death via its specific pathway, and invite further investigation into the detailed mechanism of this pathway to explore this compound's full potential as a chemotherapeutic agent.