NEUROD4 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 and gene expression data (3, 4) to discover in an unbiased manner the most significant transcriptional changes associated with trastuzumab treatment. We identified NEUROD4 among the genes most differentially expressed in the primary tumors of patients with breast cancer treated with trastuzumab. The primary tumors of breast cancer patients treated with trastuzumab expressed higher levels of NEUROD4 messenger RNA than did patients not treated with trastuzumab, and a single administration of trastuzumab was sufficient to result in differential expression of NEUROD4 in primary tumors of the breast, demonstrating increased expression of a transcription factor with neurogenic potential (5, 6) as a direct transcriptional consequence of treatment with trastuzumab.