RNA-seq Analysis in 4T07 Control (4T07-CTL) and Six2 Overexpression (4T07-Six2) cells

To determine the molecular mechanisms by which Six2 regulates metastatic colonization, we performed RNA-seq analysis on murine triple-negative 4T07 Control (4T07-CTL) and Six2 overexpressing (4T07-Six2) cells. Using both targeted and unbiased gene signature analyses, we found that Six2 differentially regulates gene signatures associated with stemness. Additionally, we confirmed that in several triple-negative breast cancer (TNBC) models, Six2 enhanced the expression of genes (identified as among the highest upregulated genes in response to Six2 overexpression) associated with embryonic stem cell programs. When combined with our in vitro and in vivo stemness-associated phenotypic assays, these data suggest that Six2 may play a similar role in mediating stemness characteristics during tumor progression as it does during development, and that this role may allow it to mediate late-stage metastasis by enhancing the ability of cells to self-renew and survive at secondary sites. Overall design: 4T07 CTL and Six2-OE cells were harvested 48h after plating for total RNA extraction (4 samples total) and RNA-seq analysis.