Differential expression of CDC28 protein kinase regulatory subunit 1B 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 CDC28 protein kinase regulatory subunit 1B, CKS1B, when comparing the tumor cells of patients with triple negative breast cancer to normal mammary ductal cells (2). CKS1B was also differentially expressed in the brain metastases of patients with metastatic breast cancer (3). CKS1B 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 CKS1B in primary tumors of the breast was correlated with distant metastasis-free survival in patients with luminal A type cancer, while within triple negative breast cancer, primary tumor expression of CKS1B was correlated with overall survival in patients with basal-like 2 and mesenchymal stem-like subtype disease. CKS1B may be of relevance to initiation, maintenance or progression of triple negative breast cancers.