肿瘤干细胞在恶性肿瘤的发生发展中起重要的作用，肺癌干细胞的研究存在标志物及分选技术的争议。我们前期单细胞水平研究发现肺腺癌A549细胞系中45%的细胞是肿瘤干细胞样细胞，但是非小细胞肺癌组织中肿瘤干细胞的比例尚不清楚。本研究拟采用有限稀释方法，在单细胞水平研究非小细胞肺癌组织中细胞克隆形成能力、自我更新能力、侵袭能力、体内成瘤能力，确定非小细胞肺癌组织中肿瘤干细胞的比例；研究肿瘤细胞在乏氧、化疗、放疗等条件下是否重新获得干细胞样特性，及参与此过程的关键基因，以期发现具有临床价值的新靶点，进而提高肺癌治疗效果。

Cancer stem（initiating）cells play an important role in the cancer development and tumor formation,but there are some debates and controversy in the different studies of lung cancer stem（initiating）cells.Our previous study shows 45% cells of A549 are cancer initiating cells on single-cell level.But it remains unkown how many cells can initiate tumor formation on single-cell level and if non-caner stem cells are able to acquire stemness under particular conditions in the non-small cell lung cancer(NSCLC) tissue.In this project, we plan to study the clone formation capability,self-renew capability and tumor formation in nonobese diabetic/severe combined immunodeficient immunocompromised（NOD/SCID） mice to make sure how many cells are cancer stem cells in the NSCLC on single-cell level. To elucidate if the non-cancer stem cells can acquire the capability to initiate a tumor and become stem-like cells under special conditions and key genes involed in the process to explore the new targets for therapeutic consideration and improve the prognosis of NSCLC.