中文摘要：

周期节律是由内在时钟系统介导的多重生物过程的周期循环．周期节律系统是由位于大脑的视神经交叉上核的中央时钟系统和位于外周的几乎存在于所有细胞的外周时钟系统组成的．中央时钟与外周时钟都能够对生物体的生理过程进行调控，如激素的分泌、能量代谢、细胞增殖、DNA损伤修复等．而周期节律基因的表达失调，对其下游靶基因包括细胞周期相关基因的表达，以及细胞抗凋亡能力等产生重要的影响．而这一结果会导致细胞增殖加速及基因组不稳定，并可能促进肿瘤的发生．许多实验证据表明，肿瘤是一种节律相关的生理失调，在许多肿瘤中都发现周期节律遭到破坏，如乳腺癌、前列腺癌、子宫内膜癌等．本文将从周期节律对细胞周期进程及对细胞DNA损伤修复的影响来讨论分子水平上细胞的周期节律与肿瘤发生发展的关系．

英文摘要：

Circadian rhythm is the daily oscillations mediated by the internal time system in multi-biology progress.Circadian rhythm system consists of central clock system located in suprachiasmatic nucleus（SCN） and peripheral clock system which is located outside SCN in almost all cells.Both central circadian clock and peripheral clock regulate the physiological progress,such as endocrine regulation,energy homeostasis,cell proliferation,DNA damage repair,etc.While the aberrant expressions of circadian genes had important affect on the transcription of downstream targets containing cell cycle related genes and the ability of cell to undergo apoptosis.This will lead to accelerate cell proliferation and instability of genomic and may potentially promote the development of tumor.Numbers of evidence show that tumor is a circadian related disorder.The disruptions of circadian rhythm were found in many cancers,such as breast caner,prostate cancer,endometrial cancer and so on.Here we will discuss the connection between circadian rhythm and carcinogenesis in molecular level from cell cycle process and DNA damage repair.