脂肪组织与恶液质——白色棕色的敌友之争

Adipose tissue and cachexia:white or brown

人体的脂肪组织分为白色脂肪和棕色脂肪组织两种。白色脂肪主要负责储存能量,而棕色脂肪组织的主要作用是产热和消耗能量。近期研究显示,在白色脂肪组织内还存在第三类脂肪组织即浅褐色脂肪组织,其由白色脂肪转化而来,在功能上与棕色脂肪细胞相似,这一过程称为"白色脂肪棕色化"。白色脂肪棕色化是肿瘤恶液质脂肪代谢的重要特征之一。一方面,其通过棕色化后热量消耗增加而影响代谢,引起脂肪减少;另一方面,棕色化本身也会参与肿瘤恶液质的发生、发展全过程。肿瘤组织分泌的白介素-6和甲状旁腺激素相关蛋白两大驱动因子主要通过兴奋交感神经系统、去甲肾上腺素释放,作用于脂肪细胞上的β3肾上腺素受体,再进一步激活相应转录因子和产热基因如UCP1的表达,而引起棕色化。它既是肿瘤恶液质发生的早期事件,又贯穿恶液质全程,可以通过早期发现、干预该过程的各个环节,改善临床结局,为肿瘤恶液质的早期诊断、预防及治疗提供依据。

The adipose tissue of the human body can be divided into two types--white adipose tissue and brown adipose tissue. The white adipose tissue is mainly responsible for energy storage, and the while brown adipose tissue plays a main role in consuming energy and heat production. Recent studies have shown that there exists a third type of adipose tissue in white adipose tissue namely brown adipose tissue, which is converted from the white adipose tissue and is similar to brown fat cells in the function, the process called ＂white fat browning＂. White adipose browning is one of the important characteristics of cancer cachexia adipose metabolism. On the one hand, the white adipose tissue affects metabolism through increasing the amount of heat consumption after browning, and then results in a decrease in fat; On the other hand, browning will also affect the happening of cancer cachexia itself. The two major driving factors--interleukin-6 and parathyroid hormone related protein secreted by tumor tissue mainly via exciting sympathetic nervous system to release norepinephrine, which acts on β3 adrenal hormone receptor of adipose cells and then activate transcription factors and the corresponding heat producing gene expression such as UCP1, cause browning. It is not only an early event in the development of cancer cachexia, but throughout the entire process of cachexia. By means of the early detection and intervening all links of the browning process, we can improve clinical outcomes and provide the basis for the early diagnosis, prevention and treatment of cancer cachexia.