Department of Vertebrate Genomics, Max Planck Institute for Molecular Genetics, Ihnestrasse 63-73, 14195 Berlin, Germany.
Cell Commun Signal. 2010 May 11;8(1):6. doi: 10.1186/1478-811X-8-6.
During the past years in vivo transplantation experiments and in vitro colony-forming assays indicated that tumors arise only from rare cells. These cells were shown to bear self-renewal capacities and the ability to recapitulate all cell types within an individual tumor. Due to their phenotypic resemblance to normal stem cells, the term "cancer stem cells" is used. However, some pieces of the puzzle are missing: (a) a stringent definition of cancer stem cells in solid tumors (b) specific markers that only target cells that meet the criteria for a cancer stem cell in a certain type of tumor. These missing parts started an ongoing debate about which is the best method to identify and characterize cancer stem cells, or even if their mere existence is just an artifact caused by the experimental procedures. Recent findings query the cancer stem cell hypothesis for solid tumors itself since it was shown in xenograft transplantation experiments that under appropriate conditions tumor-initiating cells are not rare.In this review we critically discuss the challenges and prospects of the currently used major methods to identify cancer stem cells. Further on, we reflect the present discussion about the existence of cancer stem cells in solid tumors as well as the amount and characteristics of tumor-initiating cells and finally provide new perspectives like the correlation of cancer stem cells and induced pluripotent cells.
在过去的几年中，体内移植实验和体外集落形成实验表明，肿瘤仅起源于极少数细胞。这些细胞被证明具有自我更新能力和重现个体肿瘤内所有细胞类型的能力。由于其表型类似于正常干细胞，因此使用术语“癌症干细胞”。然而，有些难题仍然存在：（a）实体瘤中癌症干细胞的严格定义；（b）特定的标志物，这些标志物仅针对符合特定类型肿瘤中癌症干细胞标准的细胞。这些缺失的部分引发了一场关于识别和表征癌症干细胞的最佳方法的持续争论，甚至关于它们的存在是否仅仅是实验过程引起的假象。最近的发现对实体瘤中的癌症干细胞假说提出了质疑，因为在异种移植实验中表明，在适当的条件下，起始肿瘤细胞并不罕见。在这篇综述中，我们批判性地讨论了目前用于识别癌症干细胞的主要方法所面临的挑战和前景。此外，我们还反映了关于实体瘤中癌症干细胞的存在、起始肿瘤细胞的数量和特征的当前讨论，并最终提供了新的视角，如癌症干细胞和诱导多能细胞的相关性。
