title: Induction of apoptosis in T lymphoma cells by long-term treatment with thyroxine involves PKCζ nitration by nitric oxide synthase.
abstract: Thyroid hormones are important regulators of cell physiology, inducing cell proliferation, differentiation or apoptosis, depending on the cell type. Thyroid hormones induce proliferation in short-term T lymphocyte cultures. In this study, we assessed the effect of long-term thyroxine (T4) treatment on the balance of proliferation and apoptosis and the intermediate participants in T lymphoma cells. Treatment with T4 affected this balance from the fifth day of culture, inhibiting proliferation in a time-dependent manner. This effect was associated with apoptosis induction, as characterized through nuclear morphological changes, DNA fragmentation, and Annexin V-FITC/Propidium Iodide co-staining. In addition, increased iNOS gene and protein levels, and enzyme activity were observed. The generation of reactive oxygen species, depolarization of the mitochondrial membrane, and a reduction in glutathione levels were also observed. The imbalance between oxidants and antioxidants species is typically associated with the nitration of proteins, including PKCζ, an isoenzyme essential for lymphoma cell division and survival. Consistently, evidence of PKCζ nitration via proteasome degradation was also observed in this study. Taken together, these results suggest that the long-term culture of T lymphoma cells with T4 induces apoptosis through the increased production of oxidative species resulting from both augmented iNOS activity and the loss of mitochondrial function. These species induce the nitration of proteins involved in cell viability, promoting proteasome degradation. Furthermore, we discuss the impact of these results on the modulation of T lymphoma growth and the thyroid status in vivo.
authors.affiliation: Instituto de Investigaciones Biomédicas, Facultad de Ciencias Médicas, Pontificia Universidad Católica Argentina (UCA), CONICET, Alicia M. de Justo 1600 3° piso, CABA, Buenos Aires, Argentina.
authors.forename: M L
authors.initials: ML
authors.lastname: Barreiro Arcos
authors.affiliation: Instituto de Investigaciones Biomédicas, Facultad de Ciencias Médicas, Pontificia Universidad Católica Argentina (UCA), CONICET, Alicia M. de Justo 1600 3° piso, CABA, Buenos Aires, Argentina.
authors.forename: H A
authors.initials: HA
authors.lastname: Sterle
authors.affiliation: Instituto de Investigación en Biomedicina de Buenos Aires (CONICET), Buenos Aires, Argentina.
authors.forename: C
authors.initials: C
authors.lastname: Vercelli
authors.affiliation: Instituto de Investigaciones Biomédicas, Facultad de Ciencias Médicas, Pontificia Universidad Católica Argentina (UCA), CONICET, Alicia M. de Justo 1600 3° piso, CABA, Buenos Aires, Argentina.
authors.forename: E
authors.initials: E
authors.lastname: Valli
authors.affiliation: Instituto de Investigaciones Biomédicas, Facultad de Ciencias Médicas, Pontificia Universidad Católica Argentina (UCA), CONICET, Alicia M. de Justo 1600 3° piso, CABA, Buenos Aires, Argentina.
authors.forename: M F
authors.initials: MF
authors.lastname: Cayrol
authors.affiliation: Instituto de Investigaciones Biomédicas, Facultad de Ciencias Médicas, Pontificia Universidad Católica Argentina (UCA), CONICET, Alicia M. de Justo 1600 3° piso, CABA, Buenos Aires, Argentina.|Laboratorio de Radioisótopos, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina.
authors.forename: A J
authors.initials: AJ
authors.lastname: Klecha
authors.affiliation: Instituto de Investigaciones Biomédicas, Facultad de Ciencias Médicas, Pontificia Universidad Católica Argentina (UCA), CONICET, Alicia M. de Justo 1600 3° piso, CABA, Buenos Aires, Argentina.
authors.forename: M A
authors.initials: MA
authors.lastname: Paulazo
authors.affiliation: Instituto de Investigaciones Biomédicas, Facultad de Ciencias Médicas, Pontificia Universidad Católica Argentina (UCA), CONICET, Alicia M. de Justo 1600 3° piso, CABA, Buenos Aires, Argentina.
authors.forename: M C
authors.initials: MC
authors.lastname: Diaz Flaqué
authors.affiliation: Centro de Estudios Farmacológicos y Botánicos (CEFYBO), CONICET, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina.
authors.forename: A M
authors.initials: AM
authors.lastname: Franchi
authors.affiliation: Instituto de Investigaciones Biomédicas, Facultad de Ciencias Médicas, Pontificia Universidad Católica Argentina (UCA), CONICET, Alicia M. de Justo 1600 3° piso, CABA, Buenos Aires, Argentina. gacremaschi@yahoo.com.|Laboratorio de Radioisótopos, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina. gacremaschi@yahoo.com.
authors.forename: G A
authors.initials: GA
authors.lastname: Cremaschi
mesh_terms: D000818:Animals; D017304:Annexin A5; D017209:Apoptosis / Q000187:drug effects*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D004396:Coloring Agents; D053938:DNA Fragmentation / Q000187:drug effects; D005786:Gene Expression Regulation; D005978:Glutathione / Q000378:metabolism; D016399:Lymphoma, T-Cell / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D051379:Mice; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism; D009566:Nitrates / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000235:genetics* / Q000378:metabolism; D011419:Propidium; D046988:Proteasome Endopeptidase Complex / Q000187:drug effects / Q000378:metabolism; D011493:Protein Kinase C / Q000235:genetics* / Q000378:metabolism; D059748:Proteolysis / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction; D013974:Thyroxine / Q000494:pharmacology*; D013997:Time Factors; D000099221:Protein Kinase C zeta
chemical_list: D017304:Annexin A5; D004396:Coloring Agents; D005978:Glutathione; D009566:Nitrates; D052247:Nitric Oxide Synthase Type II; D011419:Propidium; D046988:Proteasome Endopeptidase Complex; D011493:Protein Kinase C; D017382:Reactive Oxygen Species; D013974:Thyroxine; D000099221:Protein Kinase C zeta; C496317:Nos2 protein, mouse