Abstract
Recent evidence supports the cancer stem cell theory, that is, that malignant tumors arise from cells termed cancer stem cells or tumor-initiating cells that have the ability to self-renew and are responsible for maintaining the tumor. Cells with marked tumor-initiating capacity have recently been identified in a number of solid tumors. CD133 (PROM1, human prominin-1) has been used as a marker to detect stem cells (progenitor cells) and cancer stem cells (tumor-initiating cells) in various tissues. Ovarian yolk sac tumors (YSTs) are rare and highly malignant. The present study was designed to evaluate the tumor-forming ability of CD133(+) cells in ovarian YST cell lines and to examine the characteristics of CD133(+) cells, such as cell growth and invasiveness. Our data suggest ovarian YST to be maintained by a rare fraction of cancer stem-like cells that express the cell surface marker CD133.