In conclusion, we demonstrated that LC-CD133 + display a higher Oct-4 expression with the ability to self-renew and may represent a reservoir with unlimited proliferative potentials for generating lung cancer cells. The resistance of LC-CD133 + to in vitro and in vivo chemoradiotherapy is partially due to preferential activation of Oct-4 gene expression. In addition, these data support that the up-regulated expressions of the Oct-4, selfrenewing gene of embryonic stem cells, play an important role in the tumorigenicity of patients with lung cancer.