Differential expression of histone cluster 1, H2bd in triple negative breast cancer.
Women diagnosed with triple negative breast cancer can benefit neither from endocrine therapy nor from HER2-targeted therapies (1). We mined published microarray datasets (2, 3) to determine in an unbiased fashion and at the systems level genes most differentially expressed in the primary tumors of patients with breast cancer. We report here significant differential expression of the gene encoding histone cluster 1, H2bd, HIST1H2BD, when comparing the tumor cells of patients with triple negative breast cancer to normal mammary ductal cells (2). HIST1H2BD was also differentially expressed in bulk tumor in human breast cancer (3). HIST1H2BD mRNA was present at significantly increased quantities in TNBC tumor cells relative to normal mammary ductal cells. Analysis of human survival data revealed that expression of HIST1H2BD in primary tumors of the breast was correlated with recurrence-free survival in patients with luminal A, HER2+ and normal-like subtype cancer, while within triple negative breast cancer, primary tumor expression of HIST1H2BD was correlated with distant metastasis-free survival in patients with basal-like 1 subtype disease. HIST1H2BD may be of relevance to initiation, maintenance or progression of triple negative breast cancers.