Stem cell-like protein expression in breast cancer cell lines

Abstract

Breast cancer is the most common type of cancer and the second leading cause of cancer deaths among women. Most of breast carcinoma arises from the breast ductal epithelium. Recent studies in the past decade have displayed that many organs in our body possess organ-specific stem cells which have the capacity of self-renewal and differentiation toward specialized cell types which are specific for that organ. Breast is also one of these organs and breast epithelium contains stem/progenitor cells which give rise to two types of differentiated breast epithelial cell types: luminal epithelial and myoepithelial. Due to their property of division-competence for selfrenewal, stem cells are more prone to malignant transformation than more differentiated cell types. Therefore, it is considered that breast cancer may have arisen from a stem/progenitor cell found in mammary epithelium and recent studies support this hypothesis. In the study described in this thesis, breast cancer cell lines have been demonstrated to display stem/progenitor cell-like protein expression. Breast cancer cell lines have been characterized according to their marker protein expression related to the differentiation status of the mammary epithelial cell type by using immunofluorescence and Western blotting techniques. Also, single cellcloning of GI-101 cell line has been performed. It has been demonstrated that a single cell could give rise to different cell populations, further supporting the hypothesis that breast cancer cell lines display stem/progenitor cell-like protein expression.