The recombination activating gene 2, RAG2, is differentially expressed in the tumors of breast cancer patients treated with trastuzumab.
Trastuzumab (Herceptin) is a monoclonal antibody targeting the extracellular domain of the human epidermal growth factor receptor 2 (HER2) (1) utilized for the treatment of adjuvant and metastatic breast cancer (2) in the United States and worldwide. We mined published microarray data (3, 4) to discover in an unbiased manner the most significant transcriptional changes associated with trastuzumab treatment. We identified the recombination activating gene, RAG2, as among those most differentially expressed in the primary tumors of patients with breast cancer treated with trastuzumab. A single administration of trastuzumab was sufficient to transcriptionally activate RAG2 in primary tumors of the breast, demonstrating increased expression of a molecule thought to possess cell type-specific expression in B-lymphocytes as a direct transcriptional consequence of treatment with trastuzumab.