Overexpression of aberrant Wnt5a and its effect on acquisition of malignant phenotypes in adult T-cell leukemia/lymphoma (ATL) cells.
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ABSTRACT: Wnt5a is a ligand of the non-canonical Wnt signaling pathway involved in cell differentiation, motility, and inflammatory response. Adult T-cell leukemia/lymphoma (ATL) is one of the most aggressive T-cell malignancies caused by infection of human T-cell leukemia virus type1 (HTLV-1). Among subtypes of ATL, acute-type ATL cells are particularly resistant to current multidrug chemotherapies and show remarkably high cell-proliferative and invasive phenotypes. Here we show a dramatic increase of WNT5A gene expression in acute-type ATL cells compared with those of indolent-type ATL cells. Treatment with IWP-2 or Wnt5a-specific knockdown significantly suppressed cell growth of ATL-derived T-cell lines. We demonstrated that the overexpression of c-Myb and FoxM1 was responsible for the synergistic activation of the WNT5A promoter. Also, a WNT5A transcript variant without the exon4 (the ?E4-WNT5A mRNA), encoding ?C-Wnt5 (1-136aa of 380aa), is overexpressed in acute-type ATL cells. The ?C-Wnt5a is secreted extracellularly and enhances cellular migration/invasion to a greater extent compared with wildtype (WT)-Wnt5a. Moreover, the ?C-Wnt5a secretion was not suppressed by IWP-2, indicating that this mutant Wnt5a is secreted via a different pathway from the WT-Wnt5a. Taken together, synergistic overexpression of the ?C-Wnt5a by c-Myb and FoxM1 may be responsible for the malignant phenotype of acute-type ATL cells.
SUBMITTER: Nakano K
PROVIDER: S-EPMC7892546 | biostudies-literature | 2021 Feb
REPOSITORIES: biostudies-literature
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