Centre for Cancer Research & Cell Biology, Queen's University Belfast, Belfast, United Kingdom.
Stem Cells. 2011 Sep;29(9):1315-21. doi: 10.1002/stem.690.
Stem cells of normal mammalian tissues are defined as nonspecialized cells that have two critical properties: (a) the ability to renew themselves through cell division and (b) the potency to differentiate into other cell types. Therefore, they play a crucial role in development and in tissue homeostasis during adult life. Being long-lived, they can be the targets of environmental carcinogens leading to the accumulation of consecutive genetic changes. Hence, the genome of stem cells must be exceptionally well protected, and several protective mechanisms have evolved to ensure the genetic integrity of the stem cell compartment in any given tissue. Ionizing radiation exposure can disrupt tissue homeostasis both through the induction of cell killing/depletion of radiosensitive stem cells, leading to loss of tissue functionality and by genotoxic damage, increasing overall risk of cancer. We will review the current knowledge about radiation effects in adult stem cells of specific normal tissues, including skin, breast, and brain, examine parallels, as well as differences with cancer stem cells, and discuss the relevance of stem cell effects to radiation risk and radiotherapy.
正常哺乳动物组织的干细胞被定义为非特化细胞，具有两个关键特性：(a) 通过细胞分裂自我更新的能力，以及(b) 分化为其他细胞类型的潜能。因此，它们在发育和成年期的组织稳态中起着至关重要的作用。由于它们寿命长，可能成为环境致癌物的靶标，导致连续遗传变化的积累。因此，干细胞的基因组必须得到极好的保护，已经进化出几种保护机制来确保特定组织中干细胞区室的遗传完整性。电离辐射暴露可以通过诱导细胞杀伤/耗竭对辐射敏感的干细胞来破坏组织稳态，导致组织功能丧失，并通过遗传毒性损伤增加整体癌症风险。我们将回顾关于特定正常组织（包括皮肤、乳腺和脑）中成年干细胞的辐射效应的现有知识，检查与癌症干细胞的相似之处和差异，并讨论干细胞效应与辐射风险和放射治疗的相关性。
