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- ItemOpen Access2-phenylethynesulfonamide (PES) uncovers a necrotic process regulated by oxidative stress and p53(Elsevier, 2014) Mattiolo, Paolo; Barbero-Farran A.; Yuste Mateos, Víctor J. (Víctor José); Boix Torras, Jacint; Ribas i Fortuny, Judit2-Phenylethynesulfonamide (PES) or pifithrin-μ is a promising anticancer agent with preferential toxicity for cancer cells. The type of cell death and the molecular cascades activated by this compound are controversial. Here, we demonstrate PES elicits a caspase- and BAX/BAK-independent non-necroptotic necrotic cell death, since it is not inhibited by necrostatin-1. This process is characterized by an early generation of reactive oxygen species (ROS) resulting in p53 up-regulation. Accordingly, thiolic antioxidants protect cells from PES-induced death. Furthermore, inhibiting the natural sources of glutathione with l-buthionine-sulfoximine (BSO) strongly cooperates with PES in triggering cytotoxicity. Genetically modified p53-null or p53 knocked-down cells show resistance to PES-driven necrosis. The predominant localization of p53 in chromatin-enriched fractions added to the up-regulation of the p53-responsive gene p21, strongly suggest the involvement of a transcription-dependent p53 program. On the other hand, we report an augmented production of ROS in p53-positive cells that, added to the increased p53 content in response to PES-elicited ROS, suggests that p53 and ROS are mutually regulated in response to PES. In sum, p53 up-regulation by ROS triggers a positive feedback loop responsible of further increasing ROS production and reinforcing PES-driven non-necroptotic necrosis.
- ItemOpen Access7-Bromoindirubin-3'-oxime uncovers a serine protease-mediated paradigm of necrotic cell death(Elsevier, 2008) Ribas i Fortuny, Judit; Yuste Mateos, Víctor J. (Víctor José); Garrofé Ochoa, Xènia; Meijer, Laurent; Esquerda Colell, Josep; Boix Torras, JacintThe new 7-bromoindirubin-3′-oxime (7BIO) compound induces caspase-independent cell death in all cell lines tested to date. Irrespective of the cell line, a 25 μM treatment for 24 h is lethal for the entire cell population. In SH-SY5Y and Jurkat cells, 7BIO (25 μM) was found to collapse the mitochondrial transmembrane potential (ΔΨm) at only 2-3 h of treatment. Concomitantly mitochondria swelled, cristae disrupted and, after 9 h, external cell membranes ruptured. In addition, endoplasmic reticulum dilated and, unexpectedly, the acute cytoplasmic destruction yielded isolated nuclei with preserved morphology and DNA integrity. Furthermore, the process was independent of both Bax and Bak, since cell viability and ΔΨm decayed indistinguishably in double Bax−/−Bak−/− mouse embryonic fibroblasts (MEFs) and their wild type counterparts. Pharmacological inhibition of the mitochondrial permeability transition pore (MPTP) did not prevent 7BIO-induced ΔΨm loss in none of the aforementioned cell lines. Caspase-independent inducers of cell death like AIF (Apoptosis Inducing Factor), cathepsins and calpains were not involved. Only the chemical inhibitors of serine proteases and, particularly, AEBSF afforded a significant protection thus suggesting a process regulated by this type of enzymes. As far as we know, these features are quite unique once taken together. Therefore, we propose 7BIO is triggering a specific type of necrotic cell death. Finally, the cytotoxicity of 7BIO on apoptosis-resistant cells like double Bax−/−Bak−/− MEFs seems of great interest envisaging cancer therapy.
- ItemOpen AccessA novel source for miR-21 expression through the alternative polyadenylation of VMP1 gene transcripts(Oxford University Press, 2012) Ribas i Fortuny, Judit; Ni, Xiaohua; Castanares, Mark; Liu, Minzhi M.; Esopi, David; Yegnasubramanian, Srinivasan; Rodriguez, Ronald; Mendell, Joshua T.; Lupold, Shawn E.miR-21 is the most commonly over-expressed microRNA (miRNA) in cancer and a proven oncogene. Hsa-miR-21 is located on chromosome 17q23.2, immediately downstream of the vacuole membrane protein-1 (VMP1) gene, also known as TMEM49. VMP1 transcripts initiate ∼130 kb upstream of miR-21, are spliced, and polyadenylated only a few hundred base pairs upstream of the miR-21 hairpin. On the other hand, primary miR-21 transcripts (pri-miR-21) originate within the last introns of VMP1, but bypass VMP1 polyadenylation signals to include the miR-21 hairpin. Here, we report that VMP1 transcripts can also bypass these polyadenylation signals to include miR-21, thus providing a novel and independently regulated source of miR-21, termed VMP1–miR-21. Northern blotting, gene-specific RT-PCR, RNA pull-down and DNA branching assays support that VMP1–miR-21 is expressed at significant levels in a number of cancer cell lines and that it is processed by the Microprocessor complex to produce mature miR-21. VMP1 and pri-miR-21 are induced by common stimuli, such as phorbol-12-myristate-13-acetate (PMA) and androgens, but show differential responses to some stimuli such as epigenetic modifying agents. Collectively, these results indicate that miR-21 is a unique miRNA capable of being regulated by alternative polyadenylation and two independent gene promoters.
- ItemOpen AccessAccumulation of misfolded SOD1 in dorsal root ganglion degenerating propioceptive sensory neurons of transgenic mice with amyotrophic lateral sclerosis(Hindawi Publishing Corporation, 2014) Sábado, Javier; Casanovas i Llorens, Anna; Tarabal Mostazo, Olga; Hereu, Marta; Piedrafita Llorens, Lídia; Calderó i Pardo, Jordi; Esquerda Colell, JosepAmyotrophic lateral sclerosis (ALS) is an adult-onset progressive neurodegenerative disease affecting upper and lower motoneurons (MNs). Although the motor phenotype is a hallmark for ALS, there is increasing evidence that systems other than the efferent MN system can be involved. Mutations of superoxide dismutase 1 (SOD1) gene cause a proportion of familial forms of this disease. Misfolding and aggregation of mutant SOD1 exert neurotoxicity in a noncell autonomous manner, as evidenced in studies using transgenic mouse models. Here, we used the SOD1(G93A) mouse model for ALS to detect, by means of conformational-specific anti-SOD1 antibodies, whether misfolded SOD1-mediated neurotoxicity extended to neuronal types other than MNs. We report that large dorsal root ganglion (DRG) proprioceptive neurons accumulate misfolded SOD1 and suffer a degenerative process involving the inflammatory recruitment of macrophagic cells. Degenerating sensory axons were also detected in association with activated microglial cells in the spinal cord dorsal horn of diseased animals. As large proprioceptive DRG neurons project monosynaptically to ventral horn MNs, we hypothesise that a prion-like mechanism may be responsible for the transsynaptic propagation of SOD1 misfolding from ventral horn MNs to DRG sensory neurons.
- ItemRestrictedAdverse effects of a SOD1-peptide immunotherapy on SOD1(G93A) mouse slow model of amyotrophic lateral sclerosi(Elsevier, 2015-12-01) Sábado, J.; Casanovas i Llorens, Anna; Rodrigo, H.; Arque, Gloria; Esquerda Colell, JosepPrevious reports from our lab had shown that some anti-purinergic receptor P2X4 antibodies cross-reacted with misfolded forms of mutant Cu/Zn superoxide dismutase 1 (SOD1), linked to amyotrophic lateral sclerosis (ALS). Cross-reactivity could be caused by the abnormal exposure of an epitope located in the inner hydrophobic region of SOD1 that shared structural homology with the P2X4-immunizing peptide. We had previously raised antibodies against human SOD1 epitope mimicked by the P2X4 immunizing peptide. One of these antibodies, called AJ10, was able to recognize mutant/misfolded forms of ALS-linked mutant SOD1. Here, we used the AJ10 antigen as a vaccine to target neurotoxic species of mutant SOD1 in a slow mouse model of ALS. However, the obtained results showed no improvement in life span, disease onset or weight loss in treated animals; we observed an increased microglial neuroinflammatory response and high amounts of misfolded SOD1 accumulated within spinal cord neurons after AJ10 immunization. An increase of immunoglobulin G deposits was also found due to the treatment. Finally, a significantly worse clinical evolution was displayed by an impairment on motor function as a consequence of AJ10 peptide immunization
- ItemRestrictedAn early and robust activation of caspases heads cells for a regulated form of necrotic-like cell death(American Society for Biochemistry and Molecular Biology, 2015) Garcia-Belinchón, Mercè; Sánchez Osuna, María; Martínez Escardó, Laura; Granados-Colomina, Carla; Pascual-Guiral, Sònia; Iglesias-Guimarais, Victoria; Casanelles, Elisenda; Ribas i Fortuny, Judit; Yuste Mateos, Víctor J. (Víctor José)Apoptosis is triggered by the activation of caspases and characterized by chromatin condensation and nuclear fragmentation (type II nuclear morphology). Necrosis is depicted by a gain in cell volume (oncosis), swelling of organelles, plasma membrane leakage, and subsequent loss of intracellular contents. Although considered as different cell death entities, there is an overlap between apoptosis and necrosis. In this sense, mounting evidence suggests that both processes can be morphological expressions of a common biochemical network known as “apoptosis- necrosis continuum.” To gain insight into the events driving the apoptosis-necrosis continuum, apoptotically proficient cells were screened facing several apoptotic inducers for the absence of type II apoptotic nuclear morphologies. Chelerythrine was selected for further studies based on its cytotoxicity and the lack of apoptotic nuclear alterations. Chelerythrine triggered an early plasma membrane leakage without condensed chromatin aggregates. Ultrastructural analysis revealed that chelerythrine-mediated cytotoxicity was compatible with a necrotic-like type of cell death. Biochemically, chelerythrine induced the activation of caspases. Moreover, the inhibition of caspases prevented chelerythrine-triggered necrotic-like cell death. Compared with staurosporine, chelerythrine induced stronger caspase activation detectable at earlier times. After using a battery of chemicals, we found that high concentrations of thiolic antioxidants fully prevented chelerythrine-driven caspase activation and necrotic-like cell death. Lower amounts of thiolic antioxidants partially prevented chelerythrine-mediated cytotoxicity and allowed cells to display type II apoptotic nuclear morphology correlating with a delay in caspase-3 activation. Altogether, these data support that an early and pronounced activation of caspases can drive cells to undergo a form of necrotic-like regulated cell death.
- ItemOpen AccessL'aplicació d'anticossos monoclonals en terapèutica humana(Col·legi Oficial de Metges de Lleida, 2009) Boix Torras, Jacint; Cirera i Torres, Judit
- ItemOpen AccessL'aplicació d'anticossos monoclonals en terapèutica humana: Farmacologia general i indicacions concretes(Col·legi Oficial de Metges de Lleida, 2009) Boix Torras, Jacint; Cirera i Torres, Judit
- ItemOpen AccessAutophagy exacerbates caspase-dependent apoptotic cell death after short times of starvation(Elsevier, 2015-12) Mattiolo, Paolo; Yuste Mateos, Víctor J. (Víctor José); Boix Torras, Jacint; Ribas i Fortuny, JuditAutophagy is generally regarded as a mechanism to promote cell survival. However, autophagy can occasionally be the mechanism responsible of cell demise. We have found that a concomitant depletion of glucose, nutrients and growth factors provoked cell death in a variety of cell lines. This death process was contingent upon caspase activation and was mediated by BAX/BAK proteins, thus indicating its apoptotic nature and the engagement of an intrinsic pathway. In order to abrogate autophagy, 3-methyladenine (3-MA), BECLIN-1 siRNA and Atg5 knock-out (Tet-Off type) approaches were alternatively employed. Irrespective of the procedure, at short times of starvation, we found that the ongoing autophagy was sensitizing cells to the permeabilization of the mitochondrial outer membrane (MOMP), caspase activation and, therefore, apoptosis. On the contrary, at longer times of starvation, autophagy displayed its characteristic pro-survival effect on cells. As far as we know, we provide the first experimental paradigm where time is the only variable determining the final outcome of autophagy. In other words, we have circumscribed in time the shift transforming autophagy from a cell death to a protection mechanism. Moreover, at short times, starvation-driven autophagy exacerbated the apoptotic cell death caused by several antitumor agents. In agreement with this fact, their apoptotic effects were greatly diminished by autophagy inhibition. The implications of these facts in tumor biology will be discussed.
- ItemOpen AccessBAX and BAK proteins are required for cyclin-dependent kinase inhibitory drugs to cause apoptosis(American Association for Cancer Research, 2008) Garrofé Ochoa, Xènia; Melero Fernández de Mera, Raquel M; Fernández Gómez, Francisco J.; Ribas i Fortuny, Judit; Jordán Bueso, Joaquín; Boix Torras, JacintIn previous reports we have shown in SH-SY5 cells that Olomoucine and Roscovitine, two inhibitory drugs of Cyclin Dependent Kinases, caused apoptosis independent of the extrinsic pathway. In this experimental paradigm, apoptosis was refractory to the protective effects of either Bcl-2 or Bcl-XL overexpression. We are now reporting the failure of Bcl-XL to prevent dell death was consistent with no effect on the kinetics of caspase activation and cytochrome c release. To further characterize this issue, we have discarded a direct effect of either Olomoucine or Roscovitine on mitochondrial permeability transition. Moreover, we have evidence that an intrinsic pathway took place in SH-SY5Y cells by demonstrating the mitochondrial translocation of a GFP-Bax construct upon transfection and treatment with CDK inhibitory drugs. Finally, we tested the effect of Olomoucine and Roscovitine on w.t., bax-/-, bak-/- and double bax-/-bak-/- MEFs. In w.t. MEFs, both drugs induced cell death by apoptosis in a dose-dependent manner. In bax-/-, bak-/- and, particularly, double bax-/-bak-/- MEFs, we observed the inhibition of apoptosis. In conclusion, Olomoucine and Roscovitine caused apoptosis through an intrinsic pathway with Bax and Bak proteins being involved.
- ItemOpen AccessCaspase-independent type III programmed cell death in chronic lymphocytic leukemia: the key role of the F-actin cytoskeleton(Ferrata Storti Foundation, 2009) Barbier, Sardine; Chatre, Laurent; Bras, Marlène; Sancho, Patricia; Roué, Gaël; Virely, Clémence; Yuste Mateos, Víctor J. (Víctor José); Baudet, Sylvie; Rubio, Manuel; Esquerda Colell, Josep; Sarfati, Marika; Merle-Béral, Hélène; Susin, Santos A.Background Programmed cell death has been traditionally related with caspase activation. However, it is now accepted that caspase-independent forms of programmed cell death also regulate cell death. In chronic lymphocytic leukemia, CD47 ligation induces one of these alternative forms of cell death: type III programmed cell death. This poorly understood process is characterized by cytoplasmic hallmarks, such as mitochondrial damage. To gain insights into the molecular pathways regulating type III programmed cell death in chronic lymphocytic leukemia, we performed extensive biochemical and cell biology assessments. Design and Methods After CD47 triggering, purified B-cells from 20 patients with chronic lymphocytic leukemia were studied by flow cytometry, immunofluorescence and three-dimensional imaging, immunoblotting, electron microscopy, and fibrillar/globular actin measurements. Finally, we subjected CD47-treated chronic lymphocytic leukemia cells to a phagocytosis assay. Results We first confirmed that induction of type III programmed cell death is an efficient means of triggering cell death in chronic lymphocytic leukemia. Further, we demonstrated that the signaling events induced by CD47 ligation provoked a reduction in cell size. This alteration is related to F-actin disruption, as the two other cytoskeleton networks, microtubules and intermediate filaments, remain undisturbed in type III programmed cell death. Strikingly, we revealed that the pharmacological modulation of F-actin dynamics regulated this type of death. Finally, our data delineated a new programmed cell death pathway in chronic lymphocytic leukemia initiated by CD47 triggering, and followed by serine protease activation, F-actin rearrangement, mitochondrial damage, phosphatidylserine exposure, and cell clearance. Conclusions Our work reveals a key molecular tool in the modulation of cell death in chronic lymphocytic leukemia: F-actin. By assessing the regulation of F-actin and type III programmed cell death, this analysis provides new options for destroying chronic lymphocytic leukemia cells, such as a combination of therapies based on apoptosis regulators (e.g., caspases, Bcl- 2, Bax) along with alternative therapies based on type III death effectors (e.g., F-actin).
- ItemOpen AccessCell death induced by 2-phenylethynesulfonamide uncovers a pro-survival function of BAX(Elsevier, 2014) Mattiolo, Paolo; Barbero-Farran A.; Amigó J.; Ripamonti M.; Ribas i Fortuny, Judit; Boix Torras, JacintPES (2-phenylethynesulfonamide) was initially identified as an inhibitor of p53 translocation to mitochondria and named Pifithrin-µ. Further studies showed that PES selectively killed tumour cells and was thus a promising anticancer agent. PES-induced cell death was characterised by a non-apoptotic, autophagosome-rich phenotype. We observed this phenotype via electron microscopy in wild type (wt) and double Bax-/- Bak-/- (DKO) mouse embryonic fibroblasts (MEFs) treated with PES. We excluded the involvement of effector caspases, BAX and BAK, in causing PES-triggered cell death. Therefore, apoptosis was ruled out as the lethal mode of action of PES. Surprisingly, MEFs containing BAX were significantly protected from PES treatments. BAX overexpression in Bax-/- MEFs confirmed this pro-survival effect. Moreover, this protective effect required the ability of BAX to localise to mitochondrial membranes. Conversely, mitochondrial fusion induced by treatment with Mdivi-1 conferred increased resistance to MEFs subjected to PES treatment. The involvement of BAX in the regulation of mitochondrial dynamics has been reported. We propose the promotion of mitochondrial fusion by BAX to be the pro-survival function attributed to BAX.
- ItemOpen AccessDyrk1A is dynamically expressed on subsets of motor neurons and in the neuromuscular junction: possible role in Down syndrome(Public Library of Science, 2013) Arque, Gloria; Casanovas i Llorens, Anna; Dierssen, MaraIndividuals with Down syndrome (DS) present important motor deficits that derive from altered motor development of infants and young children. DYRK1A, a candidate gene for DS abnormalities has been implicated in motor function due to its expression in motor nuclei in the adult brain, and its overexpression in DS mouse models leads to hyperactivity and altered motor learning. However, its precise role in the adult motor system, or its possible involvement in postnatal locomotor development has not yet been clarified. During the postnatal period we observed time-specific expression of Dyrk1A in discrete subsets of brainstem nuclei and spinal cord motor neurons. Interestingly, we describe for the first time the presence of Dyrk1A in the presynaptic terminal of the neuromuscular junctions and its axonal transport from the facial nucleus, suggesting a function for Dyrk1A in these structures. Relevant to DS, Dyrk1A overexpression in transgenic mice (TgDyrk1A) produces motor developmental alterations possibly contributing to DS motor phenotypes and modifies the numbers of motor cholinergic neurons, suggesting that the kinase may have a role in the development of the brainstem and spinal cord motor system.
- ItemOpen AccessLa farmacologia de la coagulació plasmàtica per via oral al segle XXI(Col·legi Oficial de Metges de Lleida, 2012) Boix Torras, Jacint; Ribas i Fortuny, Judit
- ItemOpen AccessNeuregulin 1-ErbB module in C-bouton synapses on somatic motor neurons: molecular compartmentation and response to peripheral nerve injury(Nature, 2017) Casanovas i Llorens, Anna; Salvany, Sara; Lahoz, Víctor; Tarabal Mostazo, Olga; Piedrafita Llorens, Lídia; Sabater, Raimundo; Hernández i Estanyol, Sara; Calderó i Pardo, Jordi; Esquerda Colell, JosepThe electric activity of lower motor neurons (MNs) appears to play a role in determining cell-vulnerability in MN diseases. MN excitability is modulated by cholinergic inputs through C-type synaptic boutons, which display an endoplasmic reticulum-related subsurface cistern (SSC) adjacent to the postsynaptic membrane. Besides cholinergic molecules, a constellation of proteins involved in different signal-transduction pathways are clustered at C-type synaptic sites (M2 muscarinic receptors, Kv2.1 potassium channels, Ca2+ activated K+ [SK] channels, and sigma-1 receptors [S1R]), but their collective functional significance so far remains unknown. We have previously suggested that neuregulin-1 (NRG1)/ErbBs-based retrograde signalling occurs at this synapse. To better understand signalling through C-boutons, we performed an analysis of the distribution of C-bouton-associated signalling proteins. We show that within SSC, S1R, Kv2.1 and NRG1 are clustered in highly specific, non-overlapping, microdomains, whereas ErbB2 and ErbB4 are present in the adjacent presynaptic compartment. This organization may define highly ordered and spatially restricted sites for different signal-transduction pathways. SSC associated proteins are disrupted in axotomised MNs together with the activation of microglia, which display a positive chemotactism to C-bouton sites. This indicates that C-bouton associated molecules are also involved in neuroinflammatory signalling in diseased MNs, emerging as new potential therapeutic targets.
- ItemOpen AccessPharmacological Modulation of Reactive Oxygen Species in Cancer Treatment(Bentham Science, 2015-01-01) Ribas i Fortuny, Judit; Mattiolo, Paolo; Boix Torras, JacintAerobic metabolism of mammalian cells leads to the generation of reactive oxygen species (ROS). To cope with this toxicity, evolution provided cells with effective antioxidant systems like glutathione. Current anticancer therapies focus on the cancer dependence on oncogenes and non-oncogenes. Tumors trigger mechanisms to circumvent the oncogenic stress and to escape cell death. In this context we have studied 2-phenylethinesulfoxamine (PES), which disables the cell protective mechanisms to confront the proteotoxicity of damaged and unfolded proteins. Proteotoxic stress is increased in tumor cells, thus providing an explanation for the anticancer selectivity of PES. In addition, we have found that PES induces a severe oxidative stress and the activation of p53. The reduction of the cell content in glutathione by means of L-buthionine-sulfoximine (BSO) synergizes with PES. In conclusion, we have found that ROS constitutes a central element in a series of positive feed-back loops in the cell. ROS, p53, proteotoxicity, autophagy and mitochondrial dynamics are interconnected with the mechanisms leading to cell death, either apoptotic or necrotic. This network of interactions provides multiple targets for drug discovery and development in cancer.
- ItemOpen AccessEls polimorfimes del citocrom P450 i la seva repercusió en la dosificació dels medicaments(Col·legi Oficial de Metges de Lleida, 2008) Boix Torras, Jacint
- ItemOpen AccessProstate-targeted radiosensitization via aptamer-shRNA chimeras in human tumor xenografts(American Society for Clinical Investigation, 2011) Ni, Xiaohua; Zhang, Yonggang; Ribas i Fortuny, Judit; Chowdhury, Wasim H.; Castanares, Mark; Zhang, Zhewei; Laiho, Marikki; DeWeese, Theodore L.; Lupold, Shawn E.Dose-escalated radiation therapy for localized prostate cancer (PCa) has a clear therapeutic benefit; however, escalated doses may also increase injury to noncancerous tissues. Radiosensitizing agents can improve ionizing radiation (IR) potency, but without targeted delivery, these agents will also sensitize surrounding normal tissues. Here we describe the development of prostate-targeted RNAi agents that selectively sensitized prostate-specific membrane antigen–positive (PSMA-positive) cells to IR. siRNA library screens identified DNA-activated protein kinase, catalytic polypeptide (DNAPK) as an ideal radiosensitization target. DNAPK shRNAs, delivered by PSMA-targeting RNA aptamers, selectively reduced DNAPK in PCa cells, xenografts, and human prostate tissues. Aptamer-targeted DNAPK shRNAs, combined with IR, dramatically and specifically enhanced PSMA-positive tumor response to IR. These findings support aptamer-shRNA chimeras as selective sensitizing agents for the improved treatment of high-risk localized PCa.
- ItemOpen AccessTrancriptional modulation of apoptotis regulators by Roscovitine and related compounds(Springer Science Business Media, 2011) Garrofé Ochoa, Xènia; Cosialls, Ana M; Ribas i Fortuny, Judit; Gil, Joan; Boix Torras, JacintChemical inhibitors of cyclin-dependent kinase (CDK), like roscovitine, are promising drugs in thecontext of new cancer therapies. Roscovitine and related compounds, like seliciclib and olomoucine, are effective inducers of apoptosis in many proliferating cells in culture. These compounds are known to activate the intrinsic or mitochondrial pathway of apoptosis. In order to better characterize this intrinsic pathway, a transcriptional analysis was performed using the reverse transcriptase-multiplex ligation-dependent probe amplification procedure (RT-MLPA). In five cell lines, we detected an early and marked reduction of most transcripts, which is consistent with the disruption of transcription that results from the inhibition of CDK7 and CDK9. However, the mRNA of p53-upregulated modulator of apoptosis (PUMA) gene escaped from this transcription inhibition in neuroblastoma cells with a functional p53 protein. The increase of PUMA mRNA was not found in roscovitine-treated cell lines defective in p53, which underwent apoptosis like their p53 proficient counterparts. In addition, in SH-SY5Y cells, sublethal and lethal concentrations of roscovitine produced equivalent increases of PUMA mRNA and protein. In conclusion, the increased expression of PUMA was not associated with apoptosis induction. On the contrary, mRNA and protein depletion of MCL-1 gene correlated the best with cell demise. Moreover, NOXA protein suffered a far minor decrease than MCL-1. Because of the selective neutr alization of NOXA by MCL-1, we hypothesize that the disruption of this balance is a critical event in apoptosis induction by roscovitine and related compounds.