title: The combination of adenosine deaminase inhibition and deoxyadenosine induces apoptosis in a human astrocytoma cell line.
abstract: Alterations in the functions of astrocytes contribute to the appearance of a variety of neurological pathologies. Gliomas, especially those of astrocytic origin, are particularly resistant to chemotherapy and are often characterized by a poor prognosis. Neuroblastoma is the tumour with the higher incidence in infants. Anticancer drugs can induce apoptosis and their cytotoxic effect is often mediated by this process. We have previously demonstrated that the combination of deoxycoformycin, a strong adenosine deaminase inhibitor, and deoxyadenosine is toxic for a human astrocytoma cell line. In fact, after 15 h of treatment, this combination increases both mitochondrial reactive oxygen species and mitochondrial mass, induces apoptosis as indicated by cytochrome c release from mitochondria and activation of caspase-3. These events are preceded by reduction in lactate release in the medium. In this work we demonstrate that after 8 h of incubation with deoxyadenosine and deoxycoformycin, caspase-8 is activated, mitochondrial mass increases and mitochondrial reactive oxygen species decrease. The addition of baicalein to the incubation medium reduces cell death and caspase-3 activity induced by deoxycoformycin and deoxyadenosine in combination. This protective effect is correlated to an increase of lactate released in the medium, a decrease in the intracellular levels of dATP, and an increase in ATP levels, as compared with the cells subjected to the treatment with deoxycoformycin and deoxyadenosine without any further addition. The effect of baicalein appears to be related to an inhibition of deoxyadenosine phosphorylation, rather than or in addition to the well known antioxidant activity of the compound. This work indicates that an astrocytoma cell line, reported to be resistant to mitochondria-dependent pathways of apoptosis, is indeed very sensitive to a manipulation affecting the balance of cellular purine metabolite concentrations. The same treatment is also cytotoxic on a neuroblastoma cell line, thus suggesting long term implications for cancer therapy.
authors.affiliation: Dipartimento di Biologia, Unità Fisiologia Generale, Via S. Zeno 31, Pisa, Italy.
authors.forename: Mercedes
authors.initials: M
authors.lastname: Garcia-Gil
authors.affiliation: Dipartimento di Biologia, Unità Biochimica, Via S. Zeno 51, Pisa, Italy.
authors.forename: Maria Grazia
authors.initials: MG
authors.lastname: Tozzi
authors.affiliation: Dipartimento di Biologia, Unità Fisiologia Generale, Via S. Zeno 31, Pisa, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Varani
authors.affiliation: Dipartimento di Biologia, Unità Fisiologia Generale, Via S. Zeno 31, Pisa, Italy.
authors.forename: Lorenza
authors.initials: L
authors.lastname: Della Verde
authors.affiliation: Dipartimento di Biologia, Unità Fisiologia Generale, Via S. Zeno 31, Pisa, Italy.
authors.forename: Edoardo
authors.initials: E
authors.lastname: Petrotto
authors.affiliation: Dipartimento di Biologia, Unità Biochimica, Via S. Zeno 51, Pisa, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Balestri
authors.affiliation: CNR, Istituto di Neuroscienze, Via Giuseppe Moruzzi 1, Pisa, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Colombaioni
authors.affiliation: Dipartimento di Biologia, Unità Biochimica, Via S. Zeno 51, Pisa, Italy. Electronic address: mcamici@biologia.unipi.it.
authors.forename: Marcella
authors.initials: M
authors.lastname: Camici
mesh_terms: D058892:Adenosine Deaminase Inhibitors / Q000008:administration & dosage*; D000970:Antineoplastic Agents / Q000008:administration & dosage*; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D001254:Astrocytoma / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D003839:Deoxyadenosines / Q000008:administration & dosage*; D004359:Drug Therapy, Combination; D006801:Humans
chemical_list: D058892:Adenosine Deaminase Inhibitors; D000970:Antineoplastic Agents; D003839:Deoxyadenosines; C058118:2'-deoxyadenosine
keywords: Adenosine deaminase; Apoptosis; Baicalein; Deoxycoformycin; Human astrocytoma cell line; Lactate production