Breast cancer cell (BCC) lines have been and still remain of considerable usefulness in basic research. However, the number of well-characterized BCC lines remains very low (no more than one dozen). Are they representative of the tumors from which they originated? And to which extent? Does their inevitably limited diversity mirror the well-known inter-tumoral heterogeneity? Recent technical advances, including micro-array and comparative genetic analysis, have brought new data to the discussion. We present here an almost exhaustive series of established BCC lines. We evaluate the accuracy of the few widely used of them (MCF-7, T-47D, BT-474, SK-BR-3, MDA-MB-231, Hs578T,...) as tumor models, or at least as models for in vivo cancer cells. We underscore the importance of both estrogen receptor-alpha (gene ESR1) and Her-2/neu/c-erb-B2 (ERBB2) as classifiers for cell lines as well as for tumors. We conclude that BCC lines cultured in vitro are likely to reflect, to a large extent, the features of cancer cells present in breast tumors.
