Raising an Antibody Specific to Breast Cancer Subpopulations Using Phage Display on Tissue Sections.

BACKGROUND/AIM: Primary tumors display a great level of intra-tumor heterogeneity in breast cancer. The current lack of prognostic and predictive biomarkers limits accurate stratification and the ability to predict response to therapy. The aim of the present study was to select recombinant antibody fragments specific against breast cancer subpopulations, aiding the discovery of novel biomarkers. MATERIALS AND METHODS: Recombinant antibody fragments were selected by phage display. A novel shadowstick technology enabled the direct selection using tissue sections of antibody fragments specific against small subpopulations of breast cancer cells. Selections were performed against a subpopulation of breast cancer cells expressing CD271+, as these previously have been indicated to be potential breast cancer stem cells. The selected antibody fragments were screened by phage ELISA on both breast cancer and myoepithelial cells. The antibody fragments were validated and evaluated by immunohistochemistry experiments. RESULTS: Our study revealed an antibody fragment, LH8, specific for breast cancer cells. Immunohistochemistry results indicate that this particular antibody fragment binds an antigen that exhibits differential expression in different breast cancer subpopulations. CONCLUSION: Further studies characterizing this antibody fragment, the subpopulation it binds and the cognate antigen may unearth novel biomarkers of clinical relevance.

Maintenance of cell type diversification in the human breast.

Recent genome-wide expression analysis of breast cancer has brought new life to the classical idea of tumors as caricatures of the process of tissue renewal as envisioned by Pierce and Speers (Cancer Res 1988;48:1996-2004) more than a decade ago. The search for a cancer founder cell or different cancer founder cells is only possible if a hierarchy of differentiation has been established for the particular tissue in question. In the human breast, the luminal epithelial and myoepithelial lineages have been characterized extensively in situ by increasingly elaborate panel of markers, and methods to isolate, culture, and clone different subpopulations have improved dramatically. Comparisons have been made with the mouse mammary gland in physiological three-dimensional culture assays of morphogenesis, and the plasticity of breast epithelial cells has been challenged by immortalization and transformation. As a result of these efforts, several candidate progenitor cells have been proposed independently of each other, and some of their features have been compared. This research has all been done to better understand breast tissue homeostasis, cell-type diversification in general and breast cancer evolution in particular. The present review discusses the current approaches to address these issues and the measures taken to unravel and maintain cell type diversification for further investigation.