Recent evidence suggests that most
malignancies are driven by "cancer stem cells" sharing the signature characteristics of adult stem cells: the ability to self renew and to differentiate. Furthermore these cells are thought to be quiescent, infrequently dividing cells with a natural resistance to chemotherapeutic agents. These studies theorize that
therapies, which effectively treat the majority of
tumor cells but 'miss' the stem cell population, will fail, while
therapies directed at stern cells can potentially eradicate
tumors. In
breast cancer, researchers have isolated '
breast cancer stem cells' capable of recreating the
tumor in vivo and in vitro. Generated new
tumors contained both additional numbers of cancer stem cells and diverse mixed populations of cells present in the initial
tumor, supporting the intriguing self-renewal and differentiation characteristics. In the present study, an antibody phage library has been used to search for phage displayed-
single chain antibodies (scFv) with selective affinity to specific targets on
breast cancer stem cells. We demonstrate evidence of two clones binding specifically to a cancer stem cell population isolated from the SUMl59
breast cancer cell line. These clones had selective affinity for cancer stem cells and they were able to select cancer stem cells among a large population of non-stem
cancer cells in
paraffin-embedded sections. The applicability of these clones to
paraffin sections and frozen tissue specimens made them good candidates to be used as diagnostic and prognostic markers in
breast cancer patient samples taking into consideration the
cancer stern cell concept in
tumor biology.