title: Premalignant PTEN-deficient thymocytes activate microRNAs miR-146a and miR-146b as a cellular defense against malignant transformation.
abstract: Cancer develops by a multistep process during which cells acquire characteristics that allow them to evade apoptosis and proliferate unchecked. Sequential acquisition of genetic alterations drives this process but also causes cellular stress, frequently prompting cells to enter a premalignant period during which they mount a defense against transformation. T cell-specific deletion of the tumor suppressor PTEN in mice induces premalignancy in the thymus and development of CD4(+) T-cell lymphomas in the periphery. Here we sought to identify factors mediating the cellular defense against transformation during the premalignant period. We identified several microRNAs upregulated specifically in premalignant thymocytes, including miR-146a, miR-146b, and the miR-183/96/182 cluster. CD4-driven T cell-specific transgenic overexpression of mir-146a and mir-146b significantly delayed PTEN-deficient lymphomagenesis and delayed c-myc oncogene induction, a key driver of transformation in PTEN-deficient T-cell malignancies. We found that miR-146a and miR-146b targeting of Traf6 attenuates TCR signaling in the thymus and inhibits downstream NF-κB-dependent induction of c-myc. Additionally, c-myc repression in mature CD4 T cells by miR-146b impaired TCR-mediated proliferation. Hence, we have identified 2 miRNAs that are upregulated as part of the cellular response against transformation that, when overrepresented, can effectively inhibit progression to malignancy in the context of PTEN deficiency.
authors.affiliation: Department of Molecular and Cell Biology and Cancer Research Laboratory, University of California, Berkeley, CA.
authors.forename: Megan L
authors.initials: ML
authors.lastname: Burger
authors.affiliation: Department of Molecular and Cell Biology and Cancer Research Laboratory, University of California, Berkeley, CA.
authors.forename: Ling
authors.initials: L
authors.lastname: Xue
authors.affiliation: Department of Molecular and Cell Biology and Cancer Research Laboratory, University of California, Berkeley, CA.
authors.forename: Yuefang
authors.initials: Y
authors.lastname: Sun
authors.affiliation: Department of Molecular and Cell Biology and Cancer Research Laboratory, University of California, Berkeley, CA.
authors.forename: Chulho
authors.initials: C
authors.lastname: Kang
authors.affiliation: Department of Molecular and Cell Biology and Cancer Research Laboratory, University of California, Berkeley, CA.
authors.forename: Astar
authors.initials: A
authors.lastname: Winoto
mesh_terms: D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D049109:Cell Proliferation; D002471:Cell Transformation, Neoplastic / Q000235:genetics / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics / Q000276:immunology; D016399:Lymphoma, T-Cell / Q000235:genetics / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D051379:Mice; D018345:Mice, Knockout; D035683:MicroRNAs / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*; D005810:Multigene Family / Q000235:genetics / Q000276:immunology; D051059:PTEN Phosphohydrolase / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D016271:Proto-Oncogene Proteins c-myc / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology; D012334:RNA, Neoplasm / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*; D011948:Receptors, Antigen, T-Cell / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology; D048029:TNF Receptor-Associated Factor 6 / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D060168:Thymocytes / Q000276:immunology* / Q000378:metabolism / Q000473:pathology
chemical_list: D035683:MicroRNAs; C534190:Mirn146 microRNA, mouse; C489428:Myc protein, mouse; D016271:Proto-Oncogene Proteins c-myc; D012334:RNA, Neoplasm; D011948:Receptors, Antigen, T-Cell; D048029:TNF Receptor-Associated Factor 6; D051059:PTEN Phosphohydrolase; C487757:Pten protein, mouse
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