BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS 243, 416–425 (1998) ARTICLE NO. RC977975 The Highly Reducing Sugar 2-Deoxy- D-Ribose Induces Apoptosis in Human Fibroblasts by Reduced Glutathione Depletion and Cytoskeletal Disruption Dimitris Kletsas,* ,1 Daniela Barbieri,† Dimitri Stathakos,* Barbara Botti,† Stefania Bergamini,† Aldo Tomasi,† Daniela Monti,† Walter Malorni,‡ and Claudio Franceschi† , § *Institute of Biology, N.C.S.R. ‘‘Demokritos’’, 153 10 Athens, Greece; †Department of Biomedical Sciences, Section of General Pathology, University of Modena, 41100 Modena, Italy; ‡Department of Ultrastructures, Istituto Superiore di Sanita ` , 00161 Rome, Italy; and §Istituto Nazionale Ricovero e Cura degli Anziani (INRCA), Ancona, Italy Received December 1, 1997 disorders [1, 2]. It is characterized by specific morpho- 2-deoxy-D-Ribose (dRib), the most reducing sugar, logical and biochemical alterations, including cyto- induces apoptosis in normal human fibroblasts, as plasmic shrinkage, condensation and margination of judged by cytoplasmic shrinkage, chromatin conden- chromatin, DNA fragmentation and appearence of sation, DNA fragmentation and mitochondrial depo- apoptotic bodies; all the above distinguish this type of larization. This effect is independent from culture con- cell death from necrosis [3, 4]. Apoptosis can be trig- ditions, such as cell density and the presence or ab- gered by various stimuli, such as glucocorticoids, oxida- sence of serum in the culture milieu, suggesting that tive stress, ionizing irradiation, cytostatic drugs, with- dRib-induced apoptosis is cell cycle-independent. drawal of hormones, serum or individual growth fac- dRib was found also to provoke disruption of the actin tors, to name just a few [5]. It appears that the effect filament network and detachment from the substra- of the above noxae on cell survival and death, as well tum, while at the same time, interestingly, it increases as the type of cell death induced (apoptotic or necrotic) the expression of several integrins and cell adhesion depends on the target-cell type and the intensity of the molecules. Furthermore, dRib was found to reduce the intracellular levels of reduced glutathione (GSH). The death stimulus [3]; e.g. growth factors or macromolecu- apoptotic process was not affected by the macromolec- lar-synthesis inhibitors have proven to be apoptotic ular-synthesis inhibitors cycloheximide and actinomy- agents for several cell types and survival factors for cin D. On the contrary, the antioxidant N-acetyl-L-cys- others [6-11]. teine (NAC) fully blocks the dRib-induced apoptosis by Many agents which induce apoptosis are either oxi- preventing GSH depletion, while it also inhibits actin- dants or stimulators of cellular oxidative metabolism filament-network disruption and mitochondrial depo- [12]. Furthermore, toxic oxygen derivatives, such as larization. The above indicate that dRib induces reactive oxygen species (ROS), peroxides, superoxide apoptosis in human fibroblasts by a mechanism involv- and hydroxyl radicals are suggested mediators of ing glutathione metabolism and oxidative stress, as apoptosis [13]. Accordingly, antioxidant mechanisms well as disturbance of cytoskeletal integrity and cell are of central importance for preventing oxidative adhesion.  1998 Academic Press stress-induced apoptosis. Glutathione is considered as the main intracellular defense against oxidative stress [14]. Antioxidants, such as N-acetyl-cysteine (NAC), A major homeostatic force regulating tissue mass known to effectively raise intracellular glutathione lev- and architecture in embryonic development and in the els, have proven to be effective survival agents [15]. adult tissue is cell death by apoptosis. Furthermore, Reducing sugars are known to intervene into many apoptosis is implicated in various pathological pro- metabolic processes by non-enzymic glycosylation of cesses, such as cancer, autoimmune diseases, acquired proteins and formation of advanced glycosylation end- immune deficiency syndrome and neurodegenerative products (AGE) [16]. Increased non-enzymatic glycosyl- ation could explain some of the sequelae of diabetes, such as cataracts, accelerated atherosclerosis and neu- 1 Author for correspondence. Institute of Biology, N.C.S.R. ‘‘Demo- ropathy, as well as the aging process [16]. 2-deoxy-D- kritos’’, 153 10 Athens, Greece. Fax: / 30 1 6511767. E-mail: dikl3@cyclades.nrcps.ariadne-t.gr. ribose (dRib), a highly reducing sugar, has already been 0006-291X/98 $25.00 Copyright  1998 by Academic Press All rights of reproduction in any form reserved. 416