Proteomic phenotyping: metastatic and invasive breast cancer.

The adriamycin resistant breast cancer cell line (MCF-7/ADR) is a subject of ongoing debate concerning its origin and or source. Previous studies in our laboratory showed that MCF-7/ADR has a unique cytosolic protein expression pattern when compared to that of the parental MCF-7 cell line and other drug resistant MCF-7 cell lines. Protein expression patterns obtained using two-dimensional gel electrophoresis and mass spectrometry indicated that this MCF-7/ADR cell line shares some similarities with the metastatic breast cancer cell lines MDA-MB. Further comparisons with available two-dimensional gel electrophoresis maps in the literature indicate that MCF-7/ADR has a protein expression signature even closer to of the ductal infiltrating breast carcinoma cell line 8701. These observations suggest that MCF-7/ADR cells might have originated in a selection of ductal infiltrating carcinoma cells, which were present among the original MCF-7 cell population. These ductal infiltrating carcinoma cells may possess an intrinsic adriamycin resistance phenotype.