背景:放疗可以调节全身抗肿瘤免疫,虽然肿瘤微环境中的免疫状态也会影响放疗的疗效,但相关分子机制在肺腺癌(LUAD)中知之甚少。
方法:在本研究中,我们创新性地提出了LUAD的放射治疗反应分类,并发现ESYT3作为肿瘤抑制因子和放射免疫应答增敏剂。在放射抗性和放射敏感性LUAD组织和细胞中测量ESYT3表达。然后研究ESYT3对放疗敏感性和耐药性的影响。ESYT3和STING之间的相互作用通过多重免疫荧光染色和免疫共沉淀进行评估,和下游分子进一步分析。构建体内模型以评估ESYT3过表达与放射疗法的组合治疗功效。
结果:我们发现放射抗性亚型比放射敏感性亚型呈现免疫抑制状态和DNA损伤修复途径的激活。ESYT3表达在耐放射性LUAD组织和细胞中均显著减弱。临床上,低ESYT3表达与放射抗性有关。ESYT3的过表达能够减轻放射抗性,并使LUAD细胞对辐射诱导的DNA损伤敏感。机械上,ESYT3直接与STING交互,和激活的cGAS-STING信号,随后增加I型IFN以及下游趋化因子CCL5和CXCL10的产生,从而改善放射免疫应答。ESYT3过表达与放疗的联合治疗在体外和体内具有协同抗癌作用。
结论:总之,低ESYT3表达赋予LUAD对放疗的抗性,其过度表达可通过激活cGAS-STING依赖性途径改善放射免疫反应,从而为LUAD患者提供了一种替代的联合治疗策略.
BACKGROUND: Radiotherapy can modulate systemic antitumor immunity, while immune status in the tumor microenvironment also influences the efficacy of radiotherapy, but relevant molecular mechanisms are poorly understood in lung adenocarcinoma (LUAD).
METHODS: In this study, we innovatively proposed a radiotherapy response classification for LUAD, and discovered ESYT3 served as a tumor suppressor and radioimmune response sensitizer. ESYT3 expression was measured both in radioresistant and radiosensitive LUAD tissues and cells. The influence of ESYT3 on radiotherapy sensitivity and resistance was then investigated. Interaction between ESYT3 and STING was evaluated through multiple immunofluorescent staining and coimmunoprecipitation, and downstream molecules were further analyzed. In vivo models were constructed to assess the combination treatment efficacy of ESYT3 overexpression with radiotherapy.
RESULTS: We found that radioresistant subtype presented immunosuppressive state and activation of DNA damage repair pathways than radiosensitive subtype. ESYT3 expression was remarkably attenuated both in radioresistant LUAD tissues and cells. Clinically, low ESYT3 expression was linked with radioresistance. Overexpression of ESYT3 enabled to alleviate radioresistance, and sensitize LUAD cells to DNA damage induced by irradiation. Mechanically, ESYT3 directly interacted with STING, and activated cGAS-STING signaling, subsequently increasing the generation of type I IFNs as well as downstream chemokines CCL5 and CXCL10, thus improving radioimmune responses. The combination treatment of ESYT3 overexpression with radiotherapy had a synergistic anticancer effect in vitro and in vivo.
CONCLUSIONS: In summary, low ESYT3 expression confers resistance to radiotherapy in LUAD, and its overexpression can improve radioimmune responses through activating cGAS-STING-dependent pathway, thus providing an alternative combination therapeutic strategy for LUAD patients.