Expression profiling of breast tumors based on human epidermal growth factor receptor 2 status defines migration-related genes.

OBJECTIVE Breast cancer is a heterogeneous neoplasm. Distinct subtypes of breast cancer have been defined, suggesting the existence of molecular differences contributing to their clinical outcomes. However, the molecular differences between human epidermal growth factor receptor 2 (HER2)-positive and HER2-negative breast cancer tumors remain unclear. The aim of this study was to identify a gene expression profile for breast tumors based on their HER2 status. METHODS The HER2 status was determined by immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) in 54 breast tumor samples. Using Affymetrix microarray data from these breast tumors, we established the expression profiling of breast cancer based on HER2 IHC and FISH results. To validate microarray experiment data, real-time quantitative reverse transcription-PCR was performed. RESULTS We found significant differences between the HER2-positive and HER2-negative breast tumor samples, which included overexpression of HER2, other genes located on 17q12 and genes functionally related to migration. CONCLUSION Our study shows the potential of integrated genomic profiling to shed light on the molecular knowledge of HER2-positive breast tumors.