FoxN1-dependent thymic epithelial cells promote T-cell leukemia development

MN Ghezzo, MT Fernandes, RS Machado, I Pacheco-Leyva, MAS Araújo, RK Kalathur, ME Futschik, NL Alves, Santos NR dos

Research output: Contribution to journalArticlepeer-review

Abstract

<jats:title>Abstract</jats:title><jats:p>T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive malignancy of thymocytes. The role of thymic microenvironmental cells and stromal factors in thymocyte malignant transformation and T-ALL development remains little explored. Here, using the TEL-JAK2 transgenic (TJ2-Tg) mouse model of T-ALL, which is driven by constitutive JAK/STAT signaling and characterized by the acquisition of<jats:italic>Notch1</jats:italic>mutations, we sought to identify stromal cell alterations associated with thymic leukemogenesis. Immunofluorescence analyses showed that thymic lymphomas presented epithelial areas characterized by keratin 5 and keratin 8 expression, adjacently to keratin-negative, epithelial-free areas. Both keratin-positive and -negative areas stained conspicuously with ER-TR7 (a fibroblast marker), laminin, and CD31 (an endothelial cell marker). Besides keratin 5, keratin-positive areas were also labeled by the<jats:italic>Ulex Europaeus</jats:italic>agglutinin-1 medullary thymic epithelial cell (TEC) marker. To assess whether TECs are important for T-ALL development, we generated TJ2-Tg mice heterozygous for the FoxN1 transcription factor<jats:italic>nude</jats:italic>null mutation. In contrast to<jats:italic>nude</jats:italic>homozygous mice, which lack thymus and thymocytes, heterozygous mutant mice present only mild thymocyte maturation defects. In TJ2-Tg;<jats:italic>Foxn1</jats:italic><jats:sup>+/nu</jats:sup>compound mice both emergence of malignant cells in pre-leukemic thymi and overt T-ALL onset were significantly delayed. Moreover, in transplantation assays leukemic cell expansion in the thymus of recipient<jats:italic>Foxn1</jats:italic><jats:sup>+/nu</jats:sup>mice was reduced as compared to control littermates. These results indicate that FoxN1 insufficiency impairs specifically thymic leukemogenesis but not thymocyte development.</jats:p><jats:sec><jats:title>Summary</jats:title><jats:p>In a mouse model of T-ALL, several cellular alterations were detected in thymic lymphomas, including altered epithelial distribution and increased proportion of fibroblasts or endothelial cells. Reduced dosage of FoxN1, a thymic epithelial transcription factor, delayed leukemogenesis in these mice.</jats:p></jats:sec>
Original languageEnglish
Number of pages0
JournalDefault journal
Volume0
Issue number0
DOIs
Publication statusPublished - 11 Jan 2018

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