Tumor Pathophysiology, OncoRay-Center for Radiation Research in Oncology, Dresden University of Technology, Germany
Radiother Oncol. 2010 Mar;94(3):375-83. doi: 10.1016/j.radonc.2009.10.010.
CD133 is controversially discussed as putative (surrogate) marker for cancer stem/tumor-initiating cell populations (CSC/TIC) in epithelial tumors including colorectal carcinomas (CRCs). We studied CD133 expression in established CRC cell lines and examined in vitro behavior, radioresponse and in vivo tumor formation of CD133+/- subpopulations of one cell line of interest.
Ten CRC cell lines were analyzed for CD133 expression using flow cytometry and Western blotting. CD133+ and CD133- HCT-116 subpopulations were separated by FACS and studied in 2-D and 3-D culture and colony formation assays after irradiation. Subcutaneous xenograft formation was monitored in NMRI (nu/nu) mice.
CRC cell lines could be classified into three groups: (i) CD133-, (ii) CD133+ and (iii) those with two distinct CD133+ and CD133- subpopulations. Isolated CD133+/- HCT-116 subpopulations were studied relative to the original fraction. No difference was found in 2-D growth, spheroid formation or radioresponse in vitro. Also, tumor formation and growth rate did not differ for the sorted subpopulations. However, a subset of xenografts originated from CD133- HCT-116 showed a striking enrichment in the CD133+ fraction. Our data show that CD133 expression is not selective for sphere forming, tumor-initiating or radioresistant subpopulations in the HCT-116 CRC cell line. This implies that CD133 cannot be regarded as a CSC/TIC marker in all CRC cell lines and that functional measurements of tumor formation have to generally accompany CSC/TIC-directed mechanistic or therapeutic studies.
CD133 作为上皮肿瘤（包括结直肠癌）中癌症干细胞/肿瘤起始细胞群（CSC/TIC）的假定（替代）标志物存在争议。我们研究了在已建立的结直肠癌细胞系中 CD133 的表达，并检查了一个感兴趣的细胞系中 CD133+/-亚群的体外行为、放射反应和体内肿瘤形成。
使用流式细胞术和 Western blot 分析了 10 种结直肠癌细胞系的 CD133 表达。通过 FACS 分离 CD133+和 CD133-HCT-116 亚群，并在照射后进行 2-D 和 3-D 培养以及集落形成测定。在 NMRI（nu/nu）小鼠中监测皮下异种移植形成。
结直肠癌细胞系可分为三组：（i）CD133-，（ii）CD133+和（iii）具有两个不同的 CD133+和 CD133-亚群的细胞系。与原始部分相比，研究了分离的 CD133+/-HCT-116 亚群。在体外 2-D 生长、球体形成或放射反应方面没有发现差异。此外，分选的亚群的肿瘤形成和生长速度也没有差异。然而，源自 CD133-HCT-116 的一部分异种移植物中 CD133+ 亚群明显富集。我们的数据表明，在 HCT-116 结直肠癌细胞系中，CD133 表达不是球体形成、肿瘤起始或放射抗性亚群的选择性标志物。这意味着 CD133 不能被视为所有结直肠癌细胞系中的 CSC/TIC 标志物，并且必须普遍伴随 CSC/TIC 定向的机制或治疗研究进行肿瘤形成的功能测量。
