Sox11 defines TNBC in black women.

We recently described TCF19 as a lineage defining nuclear factor in human triple negative breast cancer. We demonstrated separately that exposure of hormone receptor positive cells to endocrine deprivation therapy results in fate switching by TCF19 activation in HR+ cancer for acquisition of a hormone receptor negative identity. We recently demonstrated that the homeobox factor Sox11 defined the HER2+ cancer subtype in humans with breast cancer and was the major molecular determinant of predisposition for CNS metastasis in humans with HER2+ breast cancer. Triple negative breast cancers are defined by lack of expression of the hormone receptors estrogen and progesterone (HR-) and the ERBB2 growth factor receptor (HER2-). We demonstrate here by measurement of total transcription in white and black women with TNBC by comparing tumor transcriptome based on race (haplotype) that Sox11 expression defines the primary tumor in black women with TNBC. In sum we demonstrate unprecedented capacity for fate switching and flexibility in tumor identity and present further evidence indicating that black women with breast cancer are at significantly increased for metastasis to a distant organ site.