Partial enzymatic degradation of stroma allows enrichment and expansion of primary breast tumor cells.

The goal of this study was to isolate and expand tumor cells in culture that closely resemble invasive cells in primary breast carcinoma tissue. Based on the hypothesis that invasive tumor cells are released more readily upon digestion with connective tissue-degrading enzymes because they are not confined within a basement membrane, we have designed a novel procedure for their isolation. Using this method, we have successfully expanded in culture aneusomic tumor cells from several primary breast tumors. Twenty nine of 44 (66%) specimens processed yielded proliferative and passageable cultures of up to 2 x 10(7) cells. The original tumor tissue and cultures derived therefrom were compared for aneusomy and the abnormal expression of the erb-B2, p53, and bcl-2 gene products. Remarkable similarities were observed. However, some intratumor heterogeneity in chromosome content was found between touch preparations and cultured cells. Overexpression of erb-B2 was observed in the vast majority of cases (16 of 20), suggesting that this phenotype may be important for dysregulated proliferation in vitro. The simple and rapid method described in this report could enable routine expansion of primary breast tumors and provide adequate numbers of viable cells for studying and manipulating their functional characteristics.