Department of Immunology, Cancer Institute, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing 100021, China.
Cancer Lett. 2010 Dec 28;299(2):150-60. doi: 10.1016/j.canlet.2010.08.013. Epub 2010 Sep 16.
Various types of malignant tumor have been found to contain a subpopulation of cancer stem cells (CSCs). In this study, we sought to enrich CSCs from the renal cell carcinoma (RCC) cell line SK-RC-42 using the sphere culture system and characterize their immunophenotype. We demonstrated that a subpopulation of SK-RC-42 cells were capable of growing as tumor spheres in serum-free medium supplemented with EGF and bFGF. The sphere-forming cells (SFCs) had many properties similar to CSCs: ability of self-renewing in vitro and in vivo, higher mRNA expression levels of several 'stemness' genes, stronger tumorigenicity and resistance to chemotherapeutic agents and irradiation compared with the monolayer adherent cells (MACs). The SFCs expressed high levels of MHC class I but low levels of MHC class II, CD80 and CD86. In contrast with MACs, the SFCs had lower expression levels of FasL and Fas, Her2 and hTERT and activating natural killer receptors. Finally, SK-RC-42 SFCs and MACs both expressed significant and comparable levels of the transcription factor forkhead box protein 3 (FoxP3) and membrane complement regulatory proteins (mCRPs). Taken together, these findings indicate that CSCs can be enriched from RCC by culturing the tumor cells as spheres. The immunophenotype of the SFCs demonstrated in this study suggests that CSCs might play an important role in the evasion of tumor growth from immune surveillance.
已发现各种类型的恶性肿瘤中都含有一小部分癌症干细胞（CSC）。在这项研究中，我们试图使用球体培养系统从肾细胞癌（RCC）细胞系 SK-RC-42 中富集 CSC，并对其免疫表型进行鉴定。我们证明了 SK-RC-42 细胞的一小部分能够在无血清培养基中生长为肿瘤球体，该培养基中补充有表皮生长因子（EGF）和碱性成纤维细胞生长因子（bFGF）。球体形成细胞（SFC）具有许多与 CSC 相似的特性：具有体外和体内自我更新的能力、几种“干性”基因的 mRNA 表达水平更高、更强的致瘤性以及对化疗药物和辐射的耐药性，与单层贴壁细胞（MAC）相比。SFC 表达高水平的 MHC Ⅰ类但低水平的 MHC Ⅱ类、CD80 和 CD86。与 MAC 相反，SFC 的 FasL 和 Fas、Her2 和 hTERT 以及激活的自然杀伤细胞受体表达水平较低。最后，SK-RC-42 SFC 和 MAC 均表达了显著且相当水平的叉头框蛋白 3（FoxP3）和膜补体调节蛋白（mCRP）转录因子。综上所述，这些发现表明，通过培养肿瘤细胞作为球体可以从 RCC 中富集 CSC。本研究中鉴定的 SFC 免疫表型表明，CSC 可能在逃避肿瘤生长的免疫监视中发挥重要作用。
