9-Norbornyl-6-chloropurine (NCP) induces cell death through GSH depletion-associated ER stress and mitochondrial dysfunction.
9-Norbornyl-6-chloropurine (NCP) is a representative of a series of antienteroviral bicycle derivatives with selective cytotoxicity towards leukemia cell lines. In this work we explored the mechanism of the antileukemic activity of NCP in T-cell lymphoblast cells (CCRF-CEM). Specifically, we searched for a potential link between its ability to induce cell death on the one hand and to modulate intracellular glutathione (GSH) that is necessary to its metabolic transformation via glutathione-S-transferase on the other hand. We have observed that GSH levels decreased rapidly in NCP-treated cells. Despite a complete regeneration following 24h of incubation with NCP, this profound drop in cellular GSH content triggered ER stress, ROS production and lipid peroxidation leading to the loss of mitochondrial membrane potential (MMP). These events induced concentration-dependent cell cycle arrest in G2/M phase and apoptosis. Both MMP loss and apoptosis were reversed by sulfhydryl-containing compounds (GSH, N-acetyl-l-cysteine). Furthermore, we have also shown that NCP-induced GSH decrease activated the Nrf2 pathway and its downstream targets



quinone oxidoreductase (NQO-1) and glutamate cysteine ligase modifier subunit (GCLm), thus explaining the fast restoration of GSH pool and ROS decrease. Importantly, we confirmed that the cell death-inducing properties of the compounds were co-dependent on their ability to diminish cellular GSH level by analyzing the relationships between the GSH-depleting potency and cytotoxicity in a series of other norbornylpurine analogs. Altogether, the results demonstrated that in CCRF-CEM cells NCP triggered apoptosis through GSH depletion-associated oxidative and ER stress and mitochondrial depolarization.
Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., 166 10 Prague 6, Czech Republic.
Pavla
P
Plačková
Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., 166 10 Prague 6, Czech Republic.
Michal
M
Šála
Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., 166 10 Prague 6, Czech Republic.
Markéta
M
Šmídková
Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., 166 10 Prague 6, Czech Republic.
Milan
M
Dejmek
Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., 166 10 Prague 6, Czech Republic.
Hubert
H
Hřebabecký
Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., 166 10 Prague 6, Czech Republic.
Radim
R
Nencka
Rega Institute for Medical Research, KU Leuven, Minderbroedersstraat 10, BE-3000 Leuven, Belgium.
Hendrik-Jan
HJ
Thibaut
Rega Institute for Medical Research, KU Leuven, Minderbroedersstraat 10, BE-3000 Leuven, Belgium.
Johan
J
Neyts
Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., 166 10 Prague 6, Czech Republic. Electronic address: mertlikova@uochb.cas.cz.
Helena
H
Mertlíková-Kaiserová
D017209:Apoptosis / Q000187:drug effects; D059865:Endoplasmic Reticulum Stress / Q000187:drug effects; D015973:Gene Expression Regulation, Leukemic / Q000187:drug effects; D005721:Glutamate-Cysteine Ligase / Q000235:genetics; D005978:Glutathione / Q000378:metabolism; D005982:Glutathione Transferase / Q000235:genetics*; D006801:Humans; D015458:Leukemia, T-Cell / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D015227:Lipid Peroxidation / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000473:pathology; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000235:genetics; D018384:Oxidative Stress / Q000187:drug effects*; D011687:Purines / Q000008:administration & dosage*; D017382:Reactive Oxygen Species / Q000378:metabolism
C583750:9-norbornyl-6-chloropurine; D011687:Purines; D017382:Reactive Oxygen Species; D016660:NAD(P)H Dehydrogenase (Quinone); C447479:NQO1 protein, human; D005982:Glutathione Transferase; C546365:GCLM protein, human; D005721:Glutamate-Cysteine Ligase; D005978:Glutathione
Apoptosis; Glutathione; Mitochondrial membrane potential; Norbornylpurines; Nrf-2; Reactive oxygen species; Unfolded protein response