Samanta Saptadip
Department of Physiology, Midnapore College, Midnapore, Paschim Medinipur 721101, West Bengal, India.
Crit Rev Oncog. 2021;26(3):1-41. doi: 10.1615/CritRevOncog.2021039731.
Circadian (~ 24-hour) rhythm has been observed in all living organisms. In humans, the circadian system governs different physiological functions such as metabolism, sleep-wake cycle, body temperature, hormone secretion, and cellular proliferation. The suprachiasmatic nucleus (SCN) of the anterior hypothalamus is the principal circadian pacemaker. The SCN receives input signals primarily from the retinohypothalamic tract (RHT), sends output signals to different parts of the hypothalamus, pineal gland, and the peripheral clocks through the neural or humoral network. The functions of the circadian clock are mediated by the rhythmic expression of the core clock genes through a complex feedback loop. Disruption of clock functions influences the development of several pathologic conditions, including cancer, shift work, chronic or acute jet lag, and light-at-night affect the circadian activity, leading to development of several physiological disorders, more specifically cancer. Circadian dysfunction alters the expression of core clock genes that promote the deregulation of the cell cycle, increase cell proliferation and survival, decrease apoptotic activity, alter metabolic functions, increase metastatic property, collectively induces cancer progression.
昼夜节律（约24小时）在所有生物中都有观察到。在人类中，昼夜节律系统控制着不同的生理功能，如新陈代谢、睡眠-觉醒周期、体温、激素分泌和细胞增殖。下丘脑前部的视交叉上核（SCN）是主要的昼夜节律起搏器。SCN主要从视网膜下丘脑束（RHT）接收输入信号，并通过神经或体液网络将输出信号发送到下丘脑、松果体和外周生物钟的不同部位。生物钟的功能是通过核心生物钟基因的节律性表达，通过复杂的反馈回路来介导的。生物钟功能的破坏会影响多种病理状况的发展，包括癌症、轮班工作、慢性或急性时差反应，夜间光照会影响昼夜活动，导致多种生理紊乱，更具体地说是癌症。昼夜节律功能障碍会改变核心生物钟基因的表达，从而促进细胞周期失调、增加细胞增殖和存活、降低凋亡活性、改变代谢功能、增加转移特性，共同诱导癌症进展。
