Pro-apoptotic activity of novel Isatin-Schiff base copper(II) complexes depends on oxidative stress induction and organelle-selective damage.
We characterized the pro-apoptotic activity of two new synthesized isatin-Schiff base copper(II) complexes, obtained from isatin and 1,3-diaminopropane or 2-(2-aminoethyl)pyridine: (Cu(isapn)) and (Cu(isaepy)(2)), respectively. We demonstrated that these compounds trigger apoptosis via the mitochondrial pathway. The early induction of the p53/p21 system indicates a role for p53 in cell death, however, experiments carried out with small interfering RNA against p53, or with cells lacking p53, support that a p53-independent mechanism can also occur. The extent of apoptosis mirrors the kinetics of intracellular copper uptake. Particularly, Cu(isaepy)(2) enters the cells more efficiently and specifically damages nuclei and mitochondria, as evidenced by atomic absorption analysis of copper content and by the extent of nuclear and mitochondrial integrity. Conversely, Cu(isapn), although less permeable, induces a wide-spread oxidative stress, as demonstrated by analyses of reactive oxygen species concentration, and oxidation of proteins and lipids. The increase of the antioxidant defense, through the overexpression of Cu,Zn-SOD, partially counteracts cell death; whereas retinoic acid-mediated differentiation completely rescues cells from apoptosis induced by both compounds. The activation of JNK- and Akt-mediated phosphorylative pathways has been found to be not functional for apoptosis induction. On the contrary, apoptosis significantly decreased when the analogous zinc complex was used or when Cu(isaepy)(2) was incubated in the presence of a copper chelator. Altogether, our data provide evidence for a dual role of these copper(II) complexes: they are able to vehicle copper into the cell, thus producing reactive oxygen species, and could behave as delocalized lipophilic cation-like molecules, thus specifically targeting organelles.
Filomeni
Giuseppe
G
Department of Biology, University of Rome "Tor Vergata," Via della Ricerca Scientifica, 00133 Rome, Italy.
Cerchiaro
Giselle
G
Da Costa Ferreira
Ana Maria
AM
De Martino
Angelo
A
Pedersen
Jens Z
JZ
Rotilio
Giuseppe
G
Ciriolo
Maria R
MR
D017209:Apoptosis; D045744:Cell Line, Tumor; D002470:Cell Survival; D002614:Chelating Agents / Q000494:pharmacology; D003300:Copper / Q000737:chemistry*; D006367:HeLa Cells; D006801:Humans; D007510:Isatin / Q000737:chemistry*; D007700:Kinetics; D018384:Oxidative Stress; D034741:RNA, Small Interfering / Q000378:metabolism; D017382:Reactive Oxygen Species; D013482:Superoxide Dismutase / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D020298:U937 Cells
D002614:Chelating Agents; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; D003300:Copper; D007510:Isatin; D013482:Superoxide Dismutase