Transcription profiling of immortalised human mammary luminal epithelial cells and variants expressing a moderate and high level of ERBB2

To investigate changes in gene expression associated with ERBB2, expression profiling of immortalised human mammary luminal epithelial cells and variants expressing a moderate and high level of ERBB2 has been carried out using cDNA microarrays corresponding to approximately 6,000 unique genes/ESTs. Sixty-three (63) significantly up- or down-regulated (>2.0 fold) genes were identified and further validated by RT-PCR and Northern blot analysis as well as microarray comparisons with a spontaneously ERBB2- overexpressing breast cancer cell line and ERBB2-positive primary breast tumours. Proteins predicted to be associated ERBB2 overexpression in breast cancers were analysed together with their clinical relevance by antibody screening using a tissue array. Differentially regulated genes include those involved in cell matrix interactions including P4HA2 (proline 4-hydroxylase), galectin 1 (LGALS1) and galectin 3 (LGALS3), FN1 (fibronectin 1), and CDH3 (p-cadherin) and cell proliferation (CRIP1, IGFBP3) and transformation (S100P, S100A4). A number of genes associated with MYC signalling were also differentially expressed, including NDRG1, USF2 and the epithelial membrane proteins 1 and 3 (EMP1, EMP3). These data represent profile of the transcriptional changes associated with ERBB2-related pathways in the breast, and identify novel and potentially useful targets for prognosis and therapy.