Tumor Progression in Breast Cancer

Breast cancer is one of the leading cause of cancer-related deaths of women in North America and Europe. Progress in understanding the cellular and molecular biology of mammary tumorigenesis has been impeded by lack of suitable in vitro models. The availability of normal tissue from reduction mammoplasty, and pathological tissue samples from biopsies and mastectomies provides a unique opportunity for studying human cancer. The importance of growing normal and tumor-derived cells for comparative studies of gene expression, drug resistance, surface antigens, mechanism of cell cycle control and prognostic markers can hardly be overstated. While some information can be obtained from fixed and frozen tissues, they are not useful for indepth studies involving biochemical and molecular analyses. There are no in vivo or in vitro models of tumor progression in human breast cancer. In fact, cells from mammary carcinomas have been among the most difficult human tumor-derived cells to grow in culture (1,2) and have poorly grown as xenografts in the nude mouse model (3). Very few primary mammary tumor cell lines are available (4–6).