International Journal of Cell Biology Class (target) Atg proteins Autophagosome formation Bcl-2 family Beclin 1 Chemokines Golgi-associated agents Heat shock proteins Lysosomal function Small regulatory RNAs Compounds Calpain-1, -2 Caspase-3, -6, -8 Verteporﬁn 3-Methyladenine Bcl-2/Bcl-xL Metformin CCL2 Monensin Nocodazole Geldanamycin PES Baﬁlomycin A1 Lucanthone Chloroquine Beclin 1 Lamp-2 mi-30a Table 2: Antiautophagics. Antiautophagic mechanisms Defect in autophagic process and apoptotic enhancement Inhibition of autophagic degradation Inhibition of class III PI3K activity Inhibitory interaction with Beclin 1 Decrease in Beclin 1 expression and AMPK activation Survivin upregulation Dilatation of Golgi apparatus Disconnection of Golgi stacks and dispersal into fragments Promotion of Beclin 1 degradation Impairment of the autophagy-lysosome system Prevention of fusion of autophagosomes with lysosomes Lysosomal membrane permeabilization Blocking of lysosyme acidiﬁcation Potentiation of apoptotic death, autophagosome degradation Impairment of autolysosome formation Beclin 1 translational suppression 9 Reference [77] [78] [79] [80] [41] [81] [82] [83] [84] [85] [86] [87] [88] [89] [90] [91] [92] to the BH3 binding groove of Bcl-xL. When the BH3 binding groove of Bcl-xL is mutated, the interaction between Bcl- xL and Beclin 1 is disrupted. Furthermore, the interaction between Beclin 1 and Bcl-xL can be inhibited by ABT737 at low doses, which stimulates autophagy without inducing cell apoptosis. A novel Bcl-xL inhibitor, Z36, eﬃciently induces autophagic cell death in HeLa cells. Z36 can competitively inhibit the interaction between Bcl-xL and Beclin 1 in vitro, and thus it is likely that Z36 induces autophagy by blocking the interaction between Bcl-xL/Bcl-2 and Beclin 1 [41]. Bcl- 2 phosphorylation resulted in increased dissociation of the Bcl-2-Beclin 1 complex and increased Beclin 1-dependent autophagy. The activation of JNK upregulated Beclin 1 expression and mediated Bcl-2 phosphorylation, thereby promoting cellular survival. 9.2.4. Beclin 1. Metformin, a widely used antidiabetic agent, should potentially induce autophagy as an activator of AMPK and an inhibitor of mTOR. Metformin’s action is mainly mediated by AMPK activation. 2-Deoxyglucose (2DG) is an inhibitor of glucose metabolism, since it inhibits hexokinase, the ﬁrst rate-limiting enzyme of gly- colysis. Treatment with 2DG leads to intracellular ATP depletion and induces autophagy in prostate cancer cells. Metformin inhibits 2DG-induced autophagy, reduces Beclin 1 expression, and triggers a switch from a survival process to cell death [81], suggesting that, depending on cell type, activation of AMPK is not automatically associated with the induction of autophagy. 9.2.5. Chemokines. The CC chemokine, CCL2 (MCP-1), is one of the most frequently observed chemokines in the microenvironment of tumors. CCL2 has been demonstrated to play a signiﬁcant role in prostate cancer neoplasia and invasion. CCL2 protects prostate cancer PC3 cells from autophagic death via the PI3K/Akt/survivin pathway and showed survivin to be a critical molecule in this survival mechanism [82]. CCL2 stimulation of PC3 cells, upon serum deprivation, results in Akt hyperphosphorylation of the two key regulatory sites (Ser473 and Thr308) required for its full activation. Survivin is a 16.5-kDa protein that belongs to the inhibitor of apoptosis protein (IAP) family that functions in mitotic progression and antagonizes caspases, thereby inhibiting apoptosis. Survivin is highly expressed in cancer tissues and its high level of expression is associated with poor prognosis and survival in many cancer types. CCL2- mediated survivin upregulation was shown to be PI3K/Akt- dependent; inhibition of this pathway not only abrogated survivin expression but also dramatically reduced cell sur- vival. Strong evidence for interaction between survivin and LC3 was detected by co-immunoprecipitation experiments [82]. As LC3 plays an important role in the formation and expansion of autophagosomal membranes, the survivin-LC3 interaction could inhibit this process, which is then reﬂected in changes in LC3 localization as observed when starved cells are treated with CCL2. 9.2.6. Golgi-Associated Agents. Chemical inhibition of auto- phagy by incubations with monensin (coban) signiﬁcantly increases the extent of apoptosis, which takes place via the mitochondrial pathway, and shortens the time in which the apoptotic markers are detectable. Monensin causes an accumulation of early forms of autophagic vacuoles and blocks the swelling of lysosomes seen in the presence of methylamine. Incubation with monensin at higher concen- trations (10 and 100 μM) resulted in severe mitochondrial damage and marked dilatation of the Golgi apparatus and rough ER cisternae [83]. Interruption of microtubules with microtubule destabilizing nocodazole impairs the conversion of LC3-I to LC3-II but does not block the degradation