Figure 2.

Different mechanisms of histone deacetylase (HDAC) inhibitor-induced autophagy (grey boxes) and presumed molecular determinants that cause resistance (red font). As many cancer cells already block many pathways leading to apoptosis (black arrow), which cannot be reversed by HDACi treatment, the additional occurrence of resistance to autophagy or the additional use of autophagy inhibitors (red arrow) eventually facilitates cancer cell survival. BECN1, BECLIN-1; Mutp53, mutant p53; MDM2, mouse double minute 2; HSP90, heat shock protein 90; TRX, thioredoxin; MDR1, multiple drug resistance-1.