Department of Respiratory, Taihe Hospital of Shiyan, Hubei University of Medicine, Renmin road No. 30, Shiyan, Hubei, 442000, China; Hubei Key Laboratory of Embryonic Stem Cell Research, School of Basic Medical Sciences, Hubei University of Medicine, Renmin road No. 30, Shiyan, Hubei, 442000, China; Department of hand Microsurgery, Dongfeng Hospital Affiliated to Hubei University of Medicine, Shiyan, Hubei, 442000, China.
Department of Respiratory, Taihe Hospital of Shiyan, Hubei University of Medicine, Renmin road No. 30, Shiyan, Hubei, 442000, China; Hubei Key Laboratory of Embryonic Stem Cell Research, School of Basic Medical Sciences, Hubei University of Medicine, Renmin road No. 30, Shiyan, Hubei, 442000, China.
Phytomedicine. 2023 Apr;112:154682. doi: 10.1016/j.phymed.2023.154682. Epub 2023 Jan 31.
The immunosuppressive microenvironment of lung cancer serves as an important endogenous contributor to treatment failure. The present study aimed to demonstrate the promotive effect of DHA on immunogenic cell death (ICD) in lung cancer as well as the mechanism.
The lewis lung cancer cells (LLC), A549 cells and LLC-bearing mice were applied as the lung cancer model. The apoptosis, ferroptosis assay, western blotting, immunofluorescent staining, qPCR, comet assay, flow cytometry, confocal microscopy, transmission electron microscopy and immunohistochemistry were conducted to analyze the functions and the underlying mechanism.
An increased apoptosis rate and immunogenicity were detected in DHA-treated LLC and tumor grafts. Further findings showed DHA caused lipid peroxide (LPO) accumulation, thereby initiating ferroptosis. DHA stimulated cellular endoplasmic reticulum (ER) stress and DNA damage simultaneously. However, the ER stress and DNA damage induced by DHA could be abolished by ferroptosis inhibitors, whose immunogenicity enhancement was synchronously attenuated. In contrast, the addition of exogenous iron ions further improved the immunogenicity induced by DHA accompanied by enhanced ER stress and DNA damage. The enhanced immunogenicity could be abated by ER stress and DNA damage inhibitors as well. Finally, DHA activated immunocytes and exhibited excellent anti-cancer efficacy in LLC-bearing mice.
In summary, the current study demonstrates that DHA triggers ferroptosis, facilitating the ICD of lung cancer thereupon. This work reveals for the first time the effect and underlying mechanism by which DHA induces ICD of cancer cells, providing novel insights into the regulation of the immune microenvironment for cancer immunotherapy by Chinese medicine phytopharmaceuticals.
肺癌的免疫抑制微环境是导致治疗失败的一个重要内源性因素。本研究旨在证明 DHA 对肺癌免疫原性细胞死亡（ICD）的促进作用及其机制。
采用 Lewis 肺癌细胞（LLC）、A549 细胞和 LLC 荷瘤小鼠作为肺癌模型。通过凋亡、铁死亡检测、western blot、免疫荧光染色、qPCR、彗星实验、流式细胞术、共聚焦显微镜、透射电子显微镜和免疫组化等方法分析功能和潜在机制。
DHA 处理的 LLC 和肿瘤移植物中凋亡率和免疫原性增加。进一步的研究结果表明，DHA 导致脂质过氧化物（LPO）积累，从而引发铁死亡。DHA 同时刺激细胞内质网（ER）应激和 DNA 损伤。然而，DHA 诱导的 ER 应激和 DNA 损伤可以被铁死亡抑制剂消除，其免疫原性增强也随之减弱。相反，外源性铁离子的加入进一步提高了 DHA 诱导的免疫原性，同时伴随着增强的 ER 应激和 DNA 损伤。增强的免疫原性也可以被 ER 应激和 DNA 损伤抑制剂所减弱。最后，DHA 激活免疫细胞，并在 LLC 荷瘤小鼠中表现出优异的抗癌疗效。
综上所述，本研究表明 DHA 触发铁死亡，促进肺癌的 ICD。这一工作首次揭示了 DHA 诱导癌细胞 ICD 的作用和潜在机制，为中药植物药调节癌症免疫治疗的免疫微环境提供了新的见解。
