title: Gambogic acid induced oxidative stress dependent caspase activation regulates both apoptosis and autophagy by targeting various key molecules (NF-κB, Beclin-1, p62 and NBR1) in human bladder cancer cells.
abstract: BACKGROUND
  Gambogic acid is a potent anticancer agent and has been found effective against various types of cancer cells. The present study was addressed to explore the cytotoxic potential of Gambogic acid and the modulation of autophagy and apoptosis in bladder cancer cells T24 and UMUC3.
  
  
  METHODS
  Bladder cancer cell lines T24 and UMUC3 were treated with Gambogic acid, apoptosis was checked by flow-cytometry and expression of various autophagy and apoptosis related proteins was monitored by Western blotting. Confocal microscope was used for colocalization of p62 and Beclin-1.
  
  
  RESULTS
  Gambogic acid induces reactive oxygen species, and elicits a strong autophagic response by activating JNK at earlier time points, which is inhibited at later time points with the activation of caspases. Reactive oxygen species mediated caspase activation causes degradation of autophagic proteins, cleavage of molecular chaperones (Hsp90 and GRP-78) and adaptor proteins (p62 and NBR1). Gambogic acid treatment results in mitochondrial hyperpolarization and cytochrome c release and activates caspases involved in both extrinsic and intrinsic apoptotic pathways. Gambogic acid abrogates NF-κB activation by ROS mediated inhibition of IκB-α phosphorylation. Functionally Gambogic acid induced autophagy acts as a strong cell survival response and delays caspase activation.
  
  
  CONCLUSIONS
  Our study provides the new insights about the mechanism of Gambogic acid induced modulation of autophagy and apoptosis in bladder cancer cells. All the molecular events responsible for Gambogic acid induced autophagy and apoptosis are mediated by reactive oxygen species.
  
  
  CONCLUSIONS
  Since Gambogic acid targets various cell survival molecules therefore, it may be considered as a potential anticancer agent against bladder cancer.
authors.affiliation: Division of Cell Biology and Immunology, CSIR-Institute of Microbial Technology, Chandigarh 160 036, India.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Ishaq
authors.affiliation: Division of Cell Biology and Immunology, CSIR-Institute of Microbial Technology, Chandigarh 160 036, India.
authors.forename: Mohammad Aslam
authors.initials: MA
authors.lastname: Khan
authors.affiliation: Division of Cell Biology and Immunology, CSIR-Institute of Microbial Technology, Chandigarh 160 036, India.
authors.forename: Kapil
authors.initials: K
authors.lastname: Sharma
authors.affiliation: Division of Cell Biology and Immunology, CSIR-Institute of Microbial Technology, Chandigarh 160 036, India.
authors.forename: Gaurav
authors.initials: G
authors.lastname: Sharma
authors.affiliation: Division of Cell Biology and Immunology, CSIR-Institute of Microbial Technology, Chandigarh 160 036, India.
authors.forename: Rajesh Kumar
authors.initials: RK
authors.lastname: Dutta
authors.affiliation: Division of Cell Biology and Immunology, CSIR-Institute of Microbial Technology, Chandigarh 160 036, India. Electronic address: majumdar@imtech.res.in.
authors.forename: Sekhar
authors.initials: S
authors.lastname: Majumdar
keywords: Apoptosis; Autophagy; Bladder cancer; Gambogic acid; p62