EGCG-meditated cyto- and genotoxicity in HaCat keratinocytes is impaired by cell-mediated clearance of auto-oxidation-derived H2O2: an algorithm for experimental setting correction.

Toxicol Lett 2011 Aug 15;205(2):173-82. Epub 2011 Jun 15.

Department of Medicine I, Institute of Cancer Research, Medical University Vienna, Borschkegasse 8a, 1090 Vienna, Austria.

Several lines of evidence suggest that besides antioxidant also prooxidant properties are crucially involved in cytotoxic and protective activities of the major green tea catechin epigallocatechin-3-gallate (EGCG) in vitro (Elbling et al., 2011). Furthermore recent data suggest that EGCG induces oxidative stress also in vivo (Li et al., 2010). Here we set out to identify factors modulating cellular effects of EGCG in vitro. Using the HaCat keratinocytes model, we demonstrate that the cytotoxic, genotoxic and signal-activating effects of EGCG are significantly dependent on the ratio of cell number to working volume. Treatment with identical EGCG concentrations at altered experimental settings resulted in IC(50) values differing up to orders of magnitude and could even exert contradictory effects. This effect was based on cell-mediated clearance of autooxidation-derived H(2)O(2) from the supernatant. In order to estimate EGCG/H(2)O(2) concentrations equally effective under different settings, we have rationally derived and experimentally verified a simple algorithm relating concentration, working volume, cell number and - indirectly - exposure time. Algorithm application resulted in similar H(2)O(2) clearance curves from cell supernatants as well as comparable EGCG/H(2)O(2) effects at different settings. Our results demonstrate the importance of standardized experimental settings when investigating cytotoxic and/or beneficial effects of autooxidizing compounds.

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.toxlet.2011.06.001DOI Listing
August 2011
16 Reads

Publication Analysis

Top Keywords

experimental settings
8
hacat keratinocytes
8
cell-mediated clearance
8
cell number
8
working volume
8
effects egcg
8
egcg vitro
8
effects
5
egcg
5
effective settings
4
factors modulating
4
model demonstrate
4
settings rationally
4
concentrations equally
4
keratinocytes model
4
equally effective
4
identify factors
4
cellular effects
4
vitro hacat
4
modulating cellular
4

Similar Publications