title: Therapeutic starvation and autophagy in prostate cancer: a new paradigm for targeting metabolism in cancer therapy.
abstract: BACKGROUND
  Autophagy is a starvation induced cellular process of self-digestion that allows cells to degrade cytoplasmic contents. The understanding of autophagy, as either a mechanism of resistance to therapies that induce metabolic stress, or as a means to cell death, is rapidly expanding and supportive of a new paradigm of therapeutic starvation.
  
  
  METHODS
  To determine the effect of therapeutic starvation in prostate cancer, we studied the effect of the prototypical inhibitor of metabolism, 2-deoxy-D-glucose (2DG), in multiple cellular models including a transfected pEGFP-LC3 autophagy reporter construct in PC-3 and LNCaP cells.
  
  
  RESULTS
  We found that 2DG induced cytotoxicity in PC-3 and LNCaP cells in a dose dependent fashion. We also found that 2DG modulated checkpoint proteins cdk4, and cdk6. Using the transfected pEGFP-LC3 autophagy reporter construct, we found that 2DG induced LC3 membrane translocation, characteristic of autophagy. Furthermore, knockdown of beclin1, an essential regulator of autophagy, abrogated 2DG induced autophagy. Using Western analysis for LC3 protein, we also found increased LC3-II expression in 2DG treated cells, again consistent with autophagy. In an effort to develop markers that may be predictive of autophagy, for assessment in clinical trials, we stained human prostate tumors for Beclin1 by immunohistochemistry (IHC). Additionally, we used a digitized imaging algorithm to quantify Beclin1 staining assessment. These data demonstrate the induction of autophagy in prostate cancer by therapeutic starvation with 2DG, and support the feasibility of assessment of markers predictive of autophagy such as Beclin1 that can be utilized in clinical trials. Prostate 68: 1743-1752 (c) 2008 Wiley-Liss, Inc. These data demonstrate the induction of autophagy in prostate cancer by therapeutic starvation with 2DG, and support the feasibility of assessment of markers predictive of autophagy such as Beclin1 that can be utilized in clinical trials.
authors.affiliation: Department of Medicine, University of Medicine and Dentistry of New Jersey (UMDNJ)/Robert Wood Johnson Medical School, New Brunswick, New Jersey, USA. dipaolrs@umdnj.edu
authors.forename: Robert S
authors.initials: RS
authors.lastname: DiPaola
authors.forename: Dmitri
authors.initials: D
authors.lastname: Dvorzhinski
authors.forename: Anu
authors.initials: A
authors.lastname: Thalasila
authors.forename: Venkata
authors.initials: V
authors.lastname: Garikapaty
authors.forename: Donyell
authors.initials: D
authors.lastname: Doram
authors.forename: Michael
authors.initials: M
authors.lastname: May
authors.forename: K
authors.initials: K
authors.lastname: Bray
authors.forename: Robin
authors.initials: R
authors.lastname: Mathew
authors.forename: Brian
authors.initials: B
authors.lastname: Beaudoin
authors.forename: C
authors.initials: C
authors.lastname: Karp
authors.forename: Mark
authors.initials: M
authors.lastname: Stein
authors.forename: David J
authors.initials: DJ
authors.lastname: Foran
authors.forename: Eileen
authors.initials: E
authors.lastname: White