FOXO Transcription Factors & Gene Expression

This paper attempts to highlight ForkHead box transcription factors (FOXO -1, -3, and -4) importance of subcellular localization in U87MG and myoblasts

FOXO1 promotes the expression of canonical WNT target genes in examined basal-like breast and glioblastoma multiforme cancer cells

Basal-like breast cancer (BBC) and glioblastoma multiforme (GBM) are aggressive cancers associated with poor prognosis. BBC and GBM have stem-cell-like gene expression signatures, which are in part driven by forkhead box O (FOXO) transcription factors. To gain further insight into the impact of FOXO1 in BBC, we treated BT549 cells with AS1842856 and performed RNA sequencing. AS1842856 binds to unphosphorylated FOXO1 and inhibits its ability to directly bind to DNA. Gene Set Enrichment Analysis (GSEA) indicated that a set of WNT pathway target genes, including lymphoid enhancer-binding factor 1 (LEF1) and transcription factor 7 (TCF7), were robustly induced after AS1842856 treatment. These same genes were also induced in GBM cell lines U87MG, LN18, LN229, A172 and DBTRG upon AS1842856 treatment. In contrast, follow-up RNA interference (RNAi) targeting of FOXO1 led to reduced LEF1 and TCF7 gene expression in BT549 and U87MG cells. In agreement with RNAi experiments, CRISPR Cas9-mediated FOXO1 disruption reduced the expression of canonical WNT genes LEF1 and TCF7 in U87MG cells. The loss of TCF7 gene expression in FOXO1 disruption mutants was restored by exogenous expression of the DNA-binding-deficient FOXO1-H215R. Therefore, FOXO1 induces TCF7 in a DNA-binding-independent manner, similar to other published FOXO1-activated genes such as TCF4 and hes family bHLH transcription factor 1 (HES1). Our work demonstrates that FOXO1 promotes canonical WNT gene expression in examined BBC and GBM cells, similar to results found in Drosophila melanogaster, T-cell development and murine acute myeloid leukemia (AML) models

Foxo Factors Regulate the Expression of Canonical WNT Target Genes in a Set of Basal-Like Breast and Glioblastoma Multiforme Cancer Cell Lines

Basal-like breast cancer (BBC) and Glioblastoma Multiforme (GBM) each express stem gene expression signatures which are partly driven by FOXO transcription factors. Preliminary data from Gene Set Enrichment Analysis (GSEA) with RNA Seq. data indicated that a set of WNT target genes including LEF1, and TCF7 were robustly induced after 48-hours of AS1842856 (FOXO1 inhibitor) treatment. These same genes were also induced in GBM cell lines U87MG, LN18, LN229, A172, and DBTRG upon treatment with AS1842856. In contrast to FOXO1 inhibition, RNAi targeting of FOXO1, led to reduced LEF1, and TCF7 gene expression in BT549 and U87MG cells. Furthermore, CRISPR Cas9-mediated FOXO1 disruption also led to reduced expression of canonical WNT genes in U87MG cells. This work demonstrates that FOXO1 promotes canonical WNT gene expression in examined BBC and GBM cells similar to results found in Drosophila melanogaster and murine AML models