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Master's Dissertation
DOI
10.11606/D.5.2006.tde-20092010-183837
Document
Author
Full name
Mara de Souza Junqueira
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2006
Supervisor
Committee
Chammas, Roger (President)
Neves, Rogerio Izar
Visconti, Maria Aparecida
Title in Portuguese
Caracterização das vias de transformação maligna de uma nova linhagem estabelecida de melanoma murino
Keywords in Portuguese
Camundongos endogâmicos C57BL
Melanoma
Proteína P14ARF
Proteína P16 5
Retrovírus endógenos
Abstract in Portuguese
Ao longo dos processos de imortalização e transformação maligna, as células adquirem inúmeras alterações genéticas, que são causadas por fatores endógenos e exógenos como agentes biológicos e a geração de espécies reativas de oxigênio. Neste trabalho, uma linhagem celular espontaneamente transformada foi clonada a partir de explantes de embriões de camundongos C57bl/6. Esta linhagem mostrou-se produtora de pigmento escuro; a análise citoquímica e ultraestrutural permitiu caracterizar a linhagem como tendo origem melanocítica. A linhagem, denominada Mgal3, mostrou-se tumorigênica quando implantada no tecido subcutâneo de animais singenéicos, apresentando capacidade de disseminação linfática, dando origem a metástases em linfonodos, o que permitiu caracteriza-la como uma linhagem de melanoma murino. O processo de transformação deste melanoma caracterizou-se pela expressão de genes retrovirais endógenos, com expressão do antígeno associado a melanoma (MAA), reconhecido pelo anticorpo monoclonal MM2-9B6; ausência de mutações nos exons 5 a 8 do gene supressor de tumor TP53; e, silenciamento do gene CDKN2a, que codifica duas proteínas que atuam em redes de supressão de tumores, p16INK4a e p19ARF. A perda de expressão de pelo menos um destes produtos gênicos parece associada a mecanismos epigenéticos, uma vez que o tratamento de Mgal3 com o inibidor de DNA metiltransferase 5-Aza-2-deoxicitidina, restaurou a transcrição de pelo menos um dos transcritos do gene CDKN2a. Da mesma forma, observamos que o gene LGALS3, que codifica a lectina animal galectina-3 também é silenciado nesta linhagem, mostrando que esta molécula não está associada à manutenção desta célula transformada em condições de cultivo.
Title in English
Establishment and characterization of the malignant transformation pathways of a novel murine melanoma cell line
Keywords in English
Endogenous retroviruses
Inbred C57BL mice
Melanoma
p14ARF protein
Protein p16
Abstract in English
A novel murine melanoma cell line named Mgal3 was generated from embryo explants. This cell line gave rise to metastatic tumors when injected subcutaneously in C57bl/6 mice. Tumor histogenesis was determined at the cytochemical (Fontana Masson staining), immunohistochemical (staining with anti-HMB45 and anti-S100) and ultrastructural levels. Mgal3 produces high amounts of retroviral C particles and was recognized by the mAb MM2-9B6, which reacts with a melanoma associated antigen derived from the envelope of the ecotropic retrovirus MelArv. No mutations were found in TP53 exons 5-8, however loss of CDKN2a expression was observed. Treatment of Mgal3 with the demethylating agent azadeoxycytidine indicated that at least one of the genes encoded at the CDKN2a locus was silenced by promoter hypermethylation. Furthermore, this cell line did not express the animal lectin, galectin-3. The galectin-3 gene promoter seemed to be hypermethylated, since treatment of Mgal3 with azadeoxycytidine led to the de novo expression of the lectin.
 
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Publishing Date
2011-06-27
 
WARNING: The material described below relates to works resulting from this thesis or dissertation. The contents of these works are the author's responsibility.
  • Melo, Fabiana H. M., et al. The Promigratory Activity of the Matricellular Protein Galectin-3 Depends on the Activation of PI-3 Kinase [doi:10.1371/journal.pone.0029313]. Plos One [online], 2011, vol. 6, p. e29313.
  • SILVAMONTEIRO, e, et al. Altered expression of galectin-3 induces cortical thymocyte depletion and premature exit of immature thymocytes during Trypanosoma cruzi infection [doi:10.2353/ajpath.2007.060389]. The American Journal of Pathology [online], 2007, vol. 170, nº x, p. 546-556.
  • JUNQUEIRA, M S, LIU, Ft, and CHAMMAS, R. Involvement of galectin-3 in replicative senescence of embryonic mesenchymal cells exposed to metabolic oxidative stress. In Gordon Research Conference on Glycobiology, Ventura, 2005. Abstract.
  • JUNQUEIRA, Mara de Souza, LIU, F, and CHAMMAS, R. Evidence for a Protective Role of Galectin-3 in Metabolic Stress. In IV São Paulo Research Conference Cancer Today: From Molecular Biology to Treatment, São Paulo, 2005. Applied Cancer Research Supplement., 2005. Abstract.
  • MELO, F H M, et al. Extracellular galectin-3 disrupts focal adhesion plaques and induces dysfunctional migration of fibroblasts on laminin-1. In 96th Annual Meeting of the American Association for Cancer Research, Anaheim, 2005. Proc Amer Assoc Cancer Res 2005., 2005. Abstract.
  • TEIXEIRA, Verônica Rodrigues, et al. Galectin-3 is silenced by methylation along melanoma progression. In XIII Congresso da Sociedade Brasileira de Biologia Celular e IX Simpósio Brasileiro de Matris Extracellular, IV International Symposium on Extracellular Matrix, Búzios, Rio de Janeiro, 2006. , 2006. Abstract.
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