As human bladder cancer tumor exhibits high basal level of autophagic activities, we detected the autophagic flux in cells treated with CQ and HCQ, showing an alternation in LC3 flux in CQ- or HCQ-treated cells. Moreover, bladder cancer cells treated with CQ and HCQ underwent apoptosis, resulting increased caspase 3/7 activities, increased level of cleaved poly(ADP-ribose) polymerase (PARP), caspase 3, and DNA fragmentation. Given these results, targeting autophagy with CQ and HCQ represents an effective cancer therapeutic strategy against human bladder cancer.
Human data
The treatment combination of gambogic acid and chloroquine synergistically inhibited tumor growth in the xenograft tumor model. Chloroquine (CQ) and hydroxychloroquine (HCQ), two antimalarial drugs, are suggested to have potential anticancer properties. in the present study, we investigated the effects of CQ and HCQ on cell growth of bladder cancer with emphasis on autophagy inhibition and apoptosis induction in vitro. We found that 24-hour treatment of CQ or HCQ significantly decreased the clonogenic formation in 5637 and T24 cells compared to SV-Huc-1.
Furthermore, inhibition of autophagy by chloroquine or 3-methyladenine, or knockdown of Atg-7 all enhanced the cytotoxicity of gambogic acid, suggesting that gambogic acid-induced autophagy improves the survival of pancreatic cancer cells.
Gambogic acid induced the expression of LC3-II and Beclin-1 proteins in pancreatic cancer cells, whereas the expression of P62 showed a decline.
Gambogic acid also increased the formation of both acidic vesicular organelles and autophagosomes, and increased autophagic
flux.
Pancreatic ductal adenocarcinoma is one of the deadliest carcinomas and is characterized by highly tumorigenic and metastatic cancer stem cells (CSCs). CSCs evade available therapies, which preferentially target highly proliferative and more differentiated progenies leaving behind CSCs as a putative source for disease relapse. Intriguingly, we found that in vitro treatment with the anti-malarial agent chloroquine significantly decreased CSCs translating into diminished in vivo tumorigenicity and invasiveness in a large panel of pancreatic cancers. Gambogic acid induced the expression of LC3-II and Beclin-1 proteins in pancreatic cancer cells, whereas the expression of P62 showed a decline. STRAVELL Gambogic acid also increased the formation of both acidic vesicular organelles and autophagosomes, and increased autophagic flux. Furthermore, inhibition of autophagy by chloroquine or 3-methyladenine, or knockdown of Atg-7 all enhanced the cytotoxicity of gambogic acid, suggesting that gambogic acid-induced autophagy improves the survival of pancreatic cancer cells. Moreover, gambogic acid reduced the mitochondrial membrane potential and promoted ROS production, which contributed to the activation of autophagy. The inhibition of autophagy by chloroquine further reduced the mitochondrial membrane potential and increased the accumulation of ROS. This indicated that the inhibition of autophagy could mitigate the cellular protective effects induced by gambogic acid.