Role of micronucleus-activated cGAS-STING signaling in antitumor immunity

Cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS)-stimulator of interferon genes (STING) signaling is a significant component of the innate immune system and functions as a vital sentinel mechanism to monitor cellular and tissue aberrations in microbial invasion and organ injury. cGAS, a cytosolic DNA sensor, is specialized in recognizing abnormally localized cytoplasmic double-stranded DNA (dsDNA) and catalyzes the formation of a second messenger cyclic-GMP-AMP (cGAMP), which initiates a cascade of type Ⅰ interferon and inflammatory responses mediated by STING. Micronucleus, a byproduct of chromosomal missegregation during anaphase, is also a significant contributor to cytoplasmic dsDNA. These unstable subcellular structures are susceptible to irreversible nuclear envelope rupture, exposing genomic dsDNA to the cytoplasm, which potently recruits cGAS and activates STING-mediated innate immune signaling and its downstream activities, including type Ⅰ interferon and classical nuclear factor-κB (NF-κB) signaling pathways lead to senescence, apoptosis, autophagy activating anti-cancer immunity or directly killing tumor cells. However, sustained STING activation-induced endoplasmic reticulum stress, activated chronic type Ⅰ interferon and nonclassical NF-κB signaling pathways remodel immunosuppressive tumor microenvironment, leading to immune evasion and facilitating tumor metastasis. Therefore, activated cGAS-STING signaling plays a dual role of suppressing or facilitating tumor growth in tumorigenesis and therapy. This review elaborates on research advances in mechanisms of micronucleus inducing activation of cGAS-STING signaling and its implications in tumorigenesis and therapeutic strategies of malignant tumors.环鸟苷酸-腺苷酸合成酶（cGAS）-干扰素基因刺激因子（STING）信号通路可监测微生物入侵和组织损伤等生理病理异常状态，是天然免疫系统的重要组成之一。作为DNA感受器，cGAS主要识别异常定位于细胞质的双链DNA（dsDNA），通过催化合成二级信使环鸟苷酸-腺苷酸启动由STING介导的Ⅰ型干扰素和炎症信号通路。微核是有丝分裂后期染色体错误分离的产物，也是细胞质dsDNA的重要来源之一。作为一类不稳定的亚细胞器结构，微核核膜倾向于不可逆的破裂，导致微核基因组DNA暴露在细胞质中。暴露的微核基因组DNA招募并激活cGAS-STING信号通路，诱导STING下游信号通路活化，包括Ⅰ型干扰素信号通路和经典核因子κB（NF-κB）信号通路，导致细胞衰老、细胞凋亡和细胞自噬的发生，从而介导免疫系统的活化以清除肿瘤细胞，或者直接诱导肿瘤细胞死亡。另外，STING持续激活诱导的内质网应激，以及慢性Ⅰ型干扰素信号通路和非经典NF-κB信号通路的活化，营造了免疫抑制的肿瘤微环境，导致肿瘤细胞免疫逃逸，促进肿瘤转移和肿瘤细胞存活。因此，在肿瘤的发生发展和治疗过程中，活化的cGAS-STING免疫通路扮演着抑制或促进肿瘤的双重作用。本文阐述了肿瘤微环境中微核诱导cGAS-STING免疫通路活化的机制研究进展，探讨了其在肿瘤发生发展和治疗中的潜在重要作用。.