Enhanced Chemo-and Radiation-resistance in LC-CD133 + We evaluated the multidrug (chemotherapy)-resistant abilities of LC-CD133 + and LC-CD133 2 . We further tested four common chemotherapeutic agents including cisplatin, VP16 (etoposide), doxorubicin, paclitaxel. Compared with LC-CD133 2, LC-CD133 + are significantly resistant to the four tested chemotherapeutic agents (p,0.01; Fig. 4A ). To further determine the radiation effect on the rate of tumor growth, we used an ionizing radiation (IR) dose from 0 to 10 Gy to treat both LC-CD133 + and LC-CD133 2 . As shown in Fig. 3B , after IR treatment, the survival rate and number of LC-CD133 + were significantly higher than those of LC-CD133 2 (p,0.01). We further found that the LC-CD133 + cells possess a higher degree of radioresistance (p,0.01; Fig. 4B ). Moreover, we investigated the combined treatment effect of radiochemotherapy in LC-CD133 + . Experiments were conducted with cisplatin (10 mM) alone, VP-16 (10 mM) alone, or combined cisplatin and VP-16 on IR (2 Gy)-treated LC-CD133 + . As shown in Figure 3C , the data revealed that the cell survival rate in IR-treated LC-CD133 + was not significantly decreased by the IR treatment combined with cisplatin, with or without VP-16 (p.0.05). On the contrary, cell survival significantly declined after chemotherapy with cisplatin combined with VP-16 in IR-treated LC-CD133 2 (p,0.01; Fig. 4C ). These results suggest that LC-CD133 + may play a vital role in the tumor's ability to resist radiation and chemotherapies. To investigate whether Oct-4 expression plays a role in maintaining self-renewal or cancer stem-like properties in LC-CD133 + , we used the siRNA method with lentiviral vector for knockdown of Oct-4 expression in LC-CD133 + . We found it important that the treatment of Oct-4 siRNA in LC-CD133 + can significantly interfere with the capabilities of spheroid-like bodies (SB) formation (p,0.001; Fig. 5C ). After 7 days of the Oct-4 siRNA treatment, the SB of LC-CD133 + could not maintain floating spheres but differentiated into attached epithelial-like cells (Fig. 5C ). In contrast, the treatment of scramble control siRNA did not influence the SB formation capability in LC-CD133 + (Fig. 5C) . The SB of LC-CD133 + endogenously expressed strong positive signals for Oct-4 and CD133 (Fig. 5D) . Furthermore, the immunofluorescent results demonstrated that both the CD133 and Oct-4 expressions in LC-CD133 + were significantly blocked after 7 days of Oct-4 siRNA treatment (Fig. 5D) . FASC assay confirmed that the amount of CD133 was dramatically decreased in Oct-4 siRNA-treated LC-CD133 + and the percentages of LC-CD133 2 were significantly increased in LC-CD133 + after 7 days of Oct-4 siRNA treatment (p,0.001; Fig. 5E ). These data suggested that Oct-4 may maintain the properties of primitive stem cells and inhibit the tendency for differentiation in LC-CD133 + .