Protein Identification in Sub Proteome Fractions of Breast Cancer Cells by OFFGEL-IEF and iTRAQ Labeling

To better understand the molecular mechanisms underlying breast cancer metastasis and search for potential markers, we applied OFFGEL-IEF, iTRAQ labeling and mass spectrometry (LC- MS/MS) analysis to identify proteins in MDA-MB-435 breast cancer cell line. Protein expression profiling might yield valuable insights into molecular signals which play important role in metastatic progression. Approximately 1250 proteins were identified with >95% confidence. Cathepsin D precursor, peroxiredoxin 6 (PDX6), heat shock protein 27 (HSP27), HSP60, tropomyosin 1, annexin I and and tumor protein D54 were identified as important cellular proteins. Most of these proteins that were identified are involved in cell growth, metabolism, signal transduction and transcriptional activation. An integrated approach for mining and visualization of iTRAQ data is presented. The results provide an initial assessment of the proteome in MDA-MB-435 breast cancer cell line, and an improved understanding of metastasis tumor progression.