Analysis of gene expression patterns in triple negative breast cancer III: the retinoic acid receptor alpha and other TNBC candidate genes.

Triple negative breast cancer (TNBC) shares overlap with the basal or basal-like molecular subtype of breast cancer and is more frequently diagnosed in women of African descent (black women) for reasons not understood (1, 2). To understand genes whose expression may be of pertinence to the development or progression of triple negative breast cancer, we mined published microarray data (3) comparing global gene expression profiles of TNBC cases, identifying genes whose expression was least different among TNBC cases, indicating conservation of expression patterns suggestive of importance for TNBC biology. We identified the gene encoding the retinoic acid receptor alpha (RARA), a fatty acid elongase (ELOVL1), as well as multiple genes encoding molecules involved in epigenetic functions or with nucleic acid binding or modification properties, including TDRD7, KDM1B, PHF7, TAF5L, as well as the microRNA hsa-miR-605. Kaplan-Meier survival analysis revealed that expression levels of each of these genes correlated with survival outcomes in the basal subtype of human breast cancer, which shares significant overlap with triple negative breast cancer at the level of gene expression (2). RARA, ELOVL1, TDRD7, KDM1B, PHF7, TAF5L and hsa-miR-605 may be of relevance in understanding the etiology or progression of triple negative breast cancer. Together with our previous findings, the data allude to a potential pathogenic mechanism involving transcriptional perturbation of epigenetic machinery in triple negative breast cancer (4, 5).