Insights into the invasiveness of triple negative breast cancer from genome-wide profiling of transcription factor AP-1 (expression)

Triple negative breast cancer (TNBC) is an aggressive clinical phenotype, and accounts for 15% to 20% of all breast cancers. The molecular determinants of malignant cell behaviors in TNBC remain largely unknown. We find that the AP-1 transcription factor component, Fra-1, is overexpressed in basal-like breast tumors, and its expression level has high prognostic significance. Depletion of Fra-1 or its heterodimeric partner c-Jun inhibits the proliferative and invasive phenotypes in TNBC cells. To gain insights into the transcriptional regulatory networks of AP-1 in TNBC cells, we combine genome-wide ChIP-seq with loss-of-function transcriptome analyses. We observe dysregulation of direct targets of the Fra-1/c-Jun heterodimer involved in cell proliferation, cell adhesion, and cell-cell contact. Intriguingly, we find that AP-1 mediates downregulation of E-cadherin through direct transcriptional induction of ZEB2. This work sheds light on the mechanisms and pathways by which TNBC acquires invasiveness and proliferative propensity.

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Zhao C, Qiao Y, Jonsson P, Wang J, Xu L, Rouhi P, Sinha I, Cao Y, Williams C, Dahlman-Wright K