CD24+ ovarian cancer cells possess enhanced invasive properties

Abstract

We recently reported that a subset of CD24+ cells in ovarian cancer possess various cancer stem cell properties, including relative quiescence, self-renewal capacity, differentiation potential, chemoresistance, and tumorigenicity in nude mice. However, the properties of this population with respect to migration, invasion, and adhesion to the extracellular matrix had not been described. We therefore compared the invasive capacity of CD24+ cells to that of CD24- cells. To assess the invasive capability of CD24+ cells in ovarian cancer, an ovarian cancer cell line, CAOV3, and a primary ovarian cancer cell line, Clone 4, were sorted into CD24+ and CD24- cell subpopulations. Invasion, chemotaxis, adhesion, and in vivo tumorigenesis assays were performed with these two cell subpopulations. CD24+ cell subpopulations of CAOV3 and Clone 4 cells were found to be more invasive than the CD24- cell subpopulations. Epithelial-mesenchymal transition markers were also significantly increased in CD24+ cells. In addition, CD24+ cells showed higher chemotactic migration in response to the chemokine stromal cell-derived factor-1 than CD24- cells. CD24+ cells bound fibronectin through the activation of integrin β1. Furthermore, data from tumorigenesis assays demonstrated a significant increase in tumor formation by CD24+ cells compared to CD24- cells. Taken together, CD24 expression in ovarian cancer may be related to tumor progression, especially invasion and migration. Therefore, CD24 may be a good candidate for an ovarian cancer therapeutic target.