During embryonic development, one of the two X chromosomes of a mammalian female cell is randomly inactivated by the X chromosome inactivation mechanism, which is mainly dependent on the regulation of the non-coding RNA X-inactive specific transcript at the X chromosome inactivation center. There are three proteins that are essential for X-inactive specific transcript to function properly: scaffold attachment factor-A, lamin B receptor, and SMRT- and HDAC-associated repressor protein. In addition, the absence of X-inactive specific transcript expression promotes tumor development. During the process of chromosome inactivation, some tumor suppressor genes escape inactivation of the X chromosome and thereby continue to play a role in tumor suppression. A well-functioning tumor suppressor gene on the idle X chromosome in women is one of the reasons they have a lower propensity to develop cancer than men, women thereby benefit from this enhanced tumor suppression. This review will explore the mechanism of X chromosome inactivation, discuss the relationship between X chromosome inactivation and tumorigenesis, and consider the consequent sex differences in cancer.

在胚胎发育过程中，哺乳动物雌性细胞的两个X染色体之一被X染色体失活机制随机失活，这主要取决于X染色体失活中心对非编码RNA X失活特异性转录本的调控。X失活的特定转录本正常运行需要三种必需的蛋白质：支架附着因子A，层粘连蛋白B受体以及与SMRT和HDAC相关的阻遏蛋白。另外，X-非特异性转录本表达的缺乏促进了肿瘤的发展。在染色体失活的过程中，一些肿瘤抑制基因逃脱了X染色体的失活，从而继续在肿瘤抑制中发挥作用。妇女在闲置X染色体上功能良好的抑癌基因是她们罹患癌症的可能性比男子低的原因之一，因此妇女受益于这种增强的肿瘤抑制作用。本文将探讨X染色体失活的机制，探讨X染色体失活与肿瘤发生的关系，并考虑随之而来的性别差异。