In this study, the CD133-positive cells (LC-CD133 + ) and CD133-negative cells (LC-CD133 2 ) were isolated from tissue samples of lung cancer (LC) patients and LC cell lines. These LC-CD133 + cells possessed both the characteristics of stem-like cells and malignant tumors. Our data further demonstrated that Oct-4 expression in LC-CD133 + is involved in tumor malignancy of lung cancers and exhibits refractory properties for chemoradiotherapy in cancer stem-like cells. These results suggested that the expression of Oct-4 plays a crucial role in maintaining cancer stem-like and chemoradioresistant properties in lung cancerderived CD133 + cells.