Nonredundant antioxidant defense by multiple two-cysteine peroxiredoxins in human prostate cancer cells.
BACKGROUND
Peroxiredoxins (Prxs) are antioxidant enzymes expressed by most free-living organisms, often in multiple isoforms. Because mammalian Prxs have not been experimentally deleted or inhibited, it is not known how much they contribute to antioxidant defense, nor whether the multiple isoforms afford redundant or additive protection.


METHODS
Expression of the four members of the 2-Cys family of human Prxs was tested in human tumor cell lines. Monospecific antibodies were developed and used to monitor the extent and specificity of inhibition of expression of each isoform in prostate cancer cells stably transfected with antisense constructs.


RESULTS
Seventeen tumor lines transcribed genes for all four human Prxs. Prostate cancer cells coexpressed each isoform at the protein level. Stable transfection with antisense allowed partial, selective suppression of Prx 1, 2, 3, or 4. Prostate cancer cells were rendered more sensitive to hydrogen peroxide or an organic hydroperoxide when Prx 1, 2, or 3 but not 4 was partially suppressed, bringing them into the range of sensitivity of mouse cells. The effect of partially suppressing a single Prx was comparable to that of depleting glutathione. In contrast, sensitization to adriamycin, an antitumor agent with a redox-active quinone, followed the partial suppression of Prxs 1, 2, or 4 but not 3. Individual suppression of Prxs 1-4 had no effect on sensitivity of the cells to reactive nitrogen intermediates, tumor necrosis factor (TNF), paclitaxel (Taxol), or etoposide.


CONCLUSIONS
The 2-Cys Prxs act in a mutually nonredundant and sometimes stress-specific fashion to protect human cells from oxidant injury. The substantial resistance of human cells to hydroperoxides may result in part from the additive action of multiple Prxs.
Shen
Chuanlu
C
Department of Microbiology & Immunology, Weill Medical College, Cornell University, New York, New York 10021, USA. cnathan@med.cornell.edu
Nathan
Carl
C
D000818:Animals; D000918:Antibody Specificity; D000970:Antineoplastic Agents / Q000494:pharmacology; D000975:Antioxidants / Q000378:metabolism*; D003545:Cysteine / Q000378:metabolism*; D004317:Doxorubicin / Q000494:pharmacology; D005047:Etoposide / Q000494:pharmacology; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007106:Immune Sera / Q000276:immunology; D008297:Male; D051379:Mice; D018384:Oxidative Stress / Q000187:drug effects; D017239:Paclitaxel / Q000494:pharmacology; D010544:Peroxidases / Q000737:chemistry* / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D061105:Peroxiredoxin III; D054464:Peroxiredoxins; D011471:Prostatic Neoplasms / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D020033:Protein Isoforms / Q000276:immunology; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D000970:Antineoplastic Agents; D000975:Antioxidants; D007106:Immune Sera; C516116:Prdx3 protein, mouse; D020033:Protein Isoforms; D014409:Tumor Necrosis Factor-alpha; D005047:Etoposide; D004317:Doxorubicin; D006861:Hydrogen Peroxide; D010544:Peroxidases; C516115:PRDX3 protein, human; C515980:PRDX4 protein, human; D061105:Peroxiredoxin III; D054464:Peroxiredoxins; C515981:Prdx4 protein, mouse; D003545:Cysteine; D017239:Paclitaxel