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NKX3.1 is a direct TAL1 target gene that mediates proliferation of TAL1-expressing human T cell acute lymphoblastic leukemia.

ABSTRACT: TAL1 (also known as SCL) is expressed in >40% of human T cell acute lymphoblastic leukemias (T-ALLs). TAL1 encodes a basic helix-loop-helix transcription factor that can interfere with the transcriptional activity of E2A and HEB during T cell leukemogenesis; however, the oncogenic pathways directly activated by TAL1 are not characterized. In this study, we show that, in human TAL1-expressing T-ALL cell lines, TAL1 directly activates NKX3.1, a tumor suppressor gene required for prostate stem cell maintenance. In human T-ALL cell lines, NKX3.1 gene activation is mediated by a TAL1-LMO-Ldb1 complex that is recruited by GATA-3 bound to an NKX3.1 gene promoter regulatory sequence. TAL1-induced NKX3.1 activation is associated with suppression of HP1-? (heterochromatin protein 1 ?) binding and opening of chromatin on the NKX3.1 gene promoter. NKX3.1 is necessary for T-ALL proliferation, can partially restore proliferation in TAL1 knockdown cells, and directly regulates miR-17-92. In primary human TAL1-expressing leukemic cells, the NKX3.1 gene is expressed independently of the Notch pathway, and its inactivation impairs proliferation. Finally, TAL1 or NKX3.1 knockdown abrogates the ability of human T-ALL cells to efficiently induce leukemia development in mice. These results suggest that tumor suppressor or oncogenic activity of NKX3.1 depends on tissue expression.

SUBMITTER: Kusy S

PROVIDER: S-EPMC2947082 | biostudies-literature | 2010 Sep

REPOSITORIES: biostudies-literature

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NKX3.1 is a direct TAL1 target gene that mediates proliferation of TAL1-expressing human T cell acute lymphoblastic leukemia.

Kusy Sophie S Gerby Bastien B Goardon Nicolas N Gault Nathalie N Ferri Federica F Gérard Delphine D Armstrong Florence F Ballerini Paola P Cayuela Jean-Michel JM Baruchel André A Pflumio Françoise F Roméo Paul-Henri PH

The Journal of experimental medicine 20100920 10

TAL1 (also known as SCL) is expressed in >40% of human T cell acute lymphoblastic leukemias (T-ALLs). TAL1 encodes a basic helix-loop-helix transcription factor that can interfere with the transcriptional activity of E2A and HEB during T cell leukemogenesis; however, the oncogenic pathways directly activated by TAL1 are not characterized. In this study, we show that, in human TAL1-expressing T-ALL cell lines, TAL1 directly activates NKX3.1, a tumor suppressor gene required for prostate stem cell ...[more]

PMID: 20855495

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Project description:Acute lymphoblastic leukemia (ALL) is the most prevalent of pediatric cancers. Neuroepithelial cell-transforming 1 (NET1) has been associated with malignancy in a number of cancers, but the role of NET1 in ALL development is unclear. In the present study, we investigated the effect of NET1 gene in ALL cell proliferation and chemoresistance. We analyzed GEO microarray data comparing bone marrow expression profiles of pediatric B-cell ALL samples and those of age-matched controls. MTT and colony formation assays were performed to analyze cell proliferation. ELISA assays, Western blot analyses, and TUNEL staining were used to detect chemoresistance. We confirmed that NET1 was targeted by miR-206 using Western blot and luciferase reporter assays. We identified NET1 gene as one of the most significantly elevated genes in pediatric B-ALL. MTT and colony formation assays demonstrated that NET1 overexpression increases B-ALL cell proliferation in Nalm-6 cells. ELISA assays, Western blot analyses, and TUNEL staining showed that NET1 contributes to ALL cell doxorubicin resistance, whereas NET1 inhibition reduces resistance. Using the TargetScan database, we found that several microRNAs (miRNAs) were predicted to target NET1, including microRNA-206 (miR-206), which has been shown to regulate cancer development. To determine whether miR-206 targets NET1 in vitro, we transfected Nalm-6 cells with miR-206 or its inhibitor miR-206-in. Western blot assays showed that miR-206 inhibits NET1 expression and miR-206-in increases NET1 expression. Luciferase assays using wild-type or mutant 3'-untranslated region (3'-UTR) of NET1 confirmed these findings. We ultimately found that miR-206 inhibits B-ALL cell proliferation and chemoresistance induced by NET1. Taken together, our results provide the first evidence that NET1 enhances proliferation and chemoresistance in B-ALL cells and that miR-206 regulates these effects by targeting NET1. This study therefore not only contributes to a greater understanding of the molecular mechanisms underlying B-ALL progression but also opens the possibility for developing curative interventions.

Dataset Information

NKX3.1 is a direct TAL1 target gene that mediates proliferation of TAL1-expressing human T cell acute lymphoblastic leukemia.

Publications

NKX3.1 is a direct TAL1 target gene that mediates proliferation of TAL1-expressing human T cell acute lymphoblastic leukemia.

Similar Datasets

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