Iron is not involved in oxidative stress-mediated cytotoxicity of doxorubicin and bleomycin.
OBJECTIVE
The anticancer drugs doxorubicin and bleomycin are well-known for their oxidative stress-mediated side effects in heart and lung, respectively. It is frequently suggested that iron is involved in doxorubicin and bleomycin toxicity. We set out to elucidate whether iron chelation prevents the oxidative stress-mediated toxicity of doxorubicin and bleomycin and whether it affects their antiproliferative/proapoptotic effects.


METHODS
Cell culture experiments were performed in A549 cells. Formation of hydroxyl radicals was measured in vitro by electron paramagnetic resonance (EPR). We investigated interactions between five iron chelators and the oxidative stress-inducing agents (doxorubicin, bleomycin and H(2)O(2)) by quantifying oxidative stress and cellular damage as TBARS formation, glutathione (GSH) consumption and lactic dehydrogenase (LDH) leakage. The antitumour/proapoptotic effects of doxorubicin and bleomycin were assessed by cell proliferation and caspase-3 activity assay.


RESULTS
All the tested chelators, except for monohydroxyethylrutoside (monoHER), prevented hydroxyl radical formation induced by H(2)O(2)/Fe(2+) in EPR studies. However, only salicylaldehyde isonicotinoyl hydrazone and deferoxamine protected intact A549 cells against H(2)O(2)/Fe(2+). Conversely, the chelators that decreased doxorubicin and bleomycin-induced oxidative stress and cellular damage (dexrazoxane, monoHER) were not able to protect against H(2)O(2)/Fe(2+).


CONCLUSIONS
We have shown that the ability to chelate iron as such is not the sole determinant of a compound protecting against doxorubicin or bleomycin-induced cytotoxicity. Our data challenge the putative role of iron and hydroxyl radicals in the oxidative stress-mediated cytotoxicity of doxorubicin and bleomycin and have implications for the development of new compounds to protects against this toxicity.
Kaiserová
H
H
Department of Biochemical Sciences, Charles University in Prague, Hradec Králové, Czech Republic. Helena.Kaiserova@faf.cuni.cz
den Hartog
G J M
GJ
Simůnek
T
T
Schröterová
L
L
Kvasnicková
E
E
Bast
A
A
D000447:Aldehydes / Q000494:pharmacology; D000903:Antibiotics, Antineoplastic / Q000633:toxicity*; D017209:Apoptosis / Q000187:drug effects; D001761:Bleomycin / Q000633:toxicity*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D003676:Deferoxamine / Q000494:pharmacology; D004317:Doxorubicin / Q000633:toxicity*; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals / Q000737:chemistry; D006801:Humans; D006835:Hydrazones / Q000494:pharmacology; D006861:Hydrogen Peroxide / Q000737:chemistry; D007501:Iron / Q000737:chemistry; D007502:Iron Chelating Agents / Q000737:chemistry / Q000494:pharmacology*; D058085:Iron Compounds / Q000737:chemistry / Q000378:metabolism*; D007538:Isoniazid / Q000031:analogs & derivatives / Q000494:pharmacology; D015227:Lipid Peroxidation / Q000187:drug effects; D008175:Lung Neoplasms / Q000378:metabolism* / Q000473:pathology; D018384:Oxidative Stress / Q000187:drug effects*; D011730:Pyridoxal / Q000031:analogs & derivatives / Q000494:pharmacology; D011929:Razoxane / Q000494:pharmacology; D013997:Time Factors
D000447:Aldehydes; D000903:Antibiotics, Antineoplastic; C045076:Fenton's reagent; D005609:Free Radicals; D006835:Hydrazones; D007502:Iron Chelating Agents; D058085:Iron Compounds; C413684:salicylaldehyde isonicotinoyl hydrazone; D001761:Bleomycin; D011730:Pyridoxal; D011929:Razoxane; C021079:pyridoxal isonicotinoyl hydrazone; D004317:Doxorubicin; D006861:Hydrogen Peroxide; D007501:Iron; D003676:Deferoxamine; D007538:Isoniazid