CD24 expression on Breast Cancer Stem Cells

Breast cancer is one of the most common cancers among Canadian women, with 1 in 4 women being diagnosed per year. Tumors have many different cell types with in them that contribute to cancer formation and progression. Breast cancer stem cells (BCSCs) are one type of cells within the tumor that can initiate tumor formation. They have high invasive properties and favor metastasis. They can be identified because they have high expression of the surface protein CD44 and low expression of the surface protein CD24 (CD44+/CD24-). CD24 expression is dynamically regulated in breast cancer cells. Specifically CD44+/CD24+ cells readily give rise to CD44+/CD24- cells and vice versa. BCSCs that are CD44+/CD24- are more invasive than cells that are CD44+/CD24+. Therefore, interfering with CD24 expression can alter disease progression. However, the mechanism that regulates CD24 expression is not known. BCSCs also have high levels of activation of the tumor promoting Ras oncogene. Oncogenic mutations in Ras are associated with 30% of all human cancers. In this study, we found that CD24 expression is decreased by activation of the oncogenic Ras pathway in a model cell system. Further, we will study mechanism involved in CD24 regulation by Ras.