Different mechanisms contribute to intratumor heterogeneity, including genetic mutations, the microenvironment, and the existence of subpopulations of cancer cells with increased renewal capacity and the ability to recapitulate the heterogeneity found in primary tumors, which are referred to as cancer stem cells (CSCs). In this review, we discuss how the concept of CSCs has been defined, what assays are currently used to define the functional properties of CSCs, what intrinsic and extrinsic mechanisms regulate CSC functions, how plastic CSCs are, and the importance of epithelial-to-mesenchymal transition in conferring CSC properties. Finally, we discuss the mechanisms by which CSCs may resist medical therapy and contribute to tumor relapse.

中文翻译：

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癌症干细胞：基本概念和治疗意义。

不同的机制导致肿瘤内异质性，包括遗传突变，微环境以及癌细胞亚群的存在，这些亚群具有增强的更新能力和概括原发肿瘤中异质性的能力，被称为癌症干细胞（CSC）。在这篇综述中，我们讨论了如何定义CSC的概念，当前使用哪些测定法定义CSC的功能特性，哪些内在和外在的机制调节CSC的功能，塑料CSC的形式以及上皮-对-CSCs的重要性。间质转化赋予CSC特性。最后，我们讨论了CSC可能抵抗药物治疗并促进肿瘤复发的机制。