title: Cyclophosphamide Induces an Early Wave of Acrolein-Independent Apoptosis in the Urothelium.
abstract: OBJECTIVE
  Hemorrhagic cystitis (HC or bladder inflammation) affects a significant number of patients undergoing cyclophosphamide (CP) chemotherapy despite treatment with 2-mercaptoethanesulfonate (Mesna) to inactivate the metabolite acrolein. While the mechanism is unknown, there is clearly acrolein-independent damage to the urothelium. In this study we have explored the induction of apoptosis in the urothelium as a marker of damage and the mechanism underlying the acrolein-independent apoptosis.
  
  
  METHODS
  Apoptosis in urothelium (caspase-3/7 activity and Poly (ADP-ribosyl) polymerase (PARP) cleavage) was measured following CP administration (80 mg/kg). Sodium 2-mercaptoethane sulfonate (Mesna) was used to mask acrolein's effect. An IL-1β receptor antagonist and a cell-permeable caspase-1 inhibitor were used to assess the involvement of IL-1β and caspase-1, respectively.
  
  
  RESULTS
  Two waves of apoptosis were detected following CP administration, one peaking at 2 h and a second at 48 h. The first wave was independent of acrolein. Caspase-1 was also active at 2 h and activation of caspase-3/7 was blocked by a caspase-1 inhibitor but not an IL-1β receptor antagonist suggesting the direct activation of caspase-3/7 by caspase-1 without the need for IL-1β as an intermediate.
  
  
  CONCLUSIONS
  Our results indicate that CP initiates an early, acrolein-independent wave of apoptosis that results from direct cleavage of caspase-3/7 by caspase-1.
authors.affiliation: Department of Urology, Medical University of South Carolina. Charleston, SC.
authors.forename: Francis M
authors.initials: FM
authors.lastname: Hughes
authors.affiliation: Department of Urology, Medical University of South Carolina. Charleston, SC.
authors.forename: Alexa G
authors.initials: AG
authors.lastname: Corn
authors.affiliation: Department of Urology, Medical University of South Carolina. Charleston, SC.
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Nimmich
authors.affiliation: Department of Urology, Medical University of South Carolina. Charleston, SC.
authors.forename: Jeffery D
authors.initials: JD
authors.lastname: Pratt-Thomas
authors.affiliation: Department of Urology, Medical University of South Carolina. Charleston, SC ; Department of Pediatrics, Medical University of South Carolina. Charleston, SC ; Department of Regenerative Medicine and Cell Biology. Medical University of South Carolina. Charleston, SC.
authors.forename: J Todd
authors.initials: JT
authors.lastname: Purves
keywords: Apoptosis; Bladder; Cyclophosphamide; Cystitis; Urothelium