Mounting evidence indicates that immunogenic therapies engaging the unfolded protein response (UPR) following endoplasmic reticulum (ER) stress favor proficient cancer cell-immune interactions, by stimulating the release of immunomodulatory/proinflammatory factors by stressed or dying cancer cells. UPR-driven transcription of proinflammatory cytokines/chemokines exert beneficial or detrimental effects on tumor growth and antitumor immunity, but the cell-autonomous machinery governing the cancer cell inflammatory output in response to immunogenic therapies remains poorly defined. Here, we profiled the transcriptome of cancer cells responding to immunogenic or weakly immunogenic treatments. Bioinformatics-driven pathway analysis indicated that immunogenic treatments instigated a NF-κB/AP-1-inflammatory stress response, which dissociated from both cell death and UPR. This stress-induced inflammation was specifically abolished by the IRE1α-kinase inhibitor KIRA6. Supernatants from immunogenic chemotherapy and KIRA6 co-treated cancer cells were deprived of proinflammatory/chemoattractant factors and failed to mobilize neutrophils and induce dendritic cell maturation. Furthermore, KIRA6 significantly reduced the in vivo vaccination potential of dying cancer cells responding to immunogenic chemotherapy. Mechanistically, we found that the anti-inflammatory effect of KIRA6 was still effective in IRE1α-deficient cells, indicating a hitherto unknown off-target effector of this IRE1α-kinase inhibitor. Generation of a KIRA6-clickable photoaffinity probe, mass spectrometry, and co-immunoprecipitation analysis identified cytosolic HSP60 as a KIRA6 off-target in the IKK-driven NF-κB pathway. In sum, our study unravels that HSP60 is a KIRA6-inhibitable upstream regulator of the NF-κB/AP-1-inflammatory stress responses evoked by immunogenic treatments. It also urges caution when interpreting the anti-inflammatory action of IRE1α chemical inhibitors.

越来越多的证据表明，免疫原性疗法通过刺激应激或垂死的癌细胞释放免疫调节/促炎因子，从而在内质网（ER）应激后参与未折叠蛋白反应（UPR），有利于癌细胞-免疫相互作用。 UPR驱动的促炎细胞因子/趋化因子的转录对肿瘤生长和抗肿瘤免疫产生有益或有害的影响，但控制癌细胞炎症输出以响应免疫原性治疗的细胞自主机制仍然不明确。在这里，我们分析了对免疫原性或弱免疫原性治疗做出反应的癌细胞的转录组。生物信息学驱动的通路分析表明，免疫原性治疗引发了 NF-κB/AP-1 炎症应激反应，该反应与细胞死亡和 UPR 无关。这种应激诱导的炎症被 IRE1α 激酶抑制剂 KIRA6 特异性消除。来自免疫原性化疗和 KIRA6 共同处理的癌细胞的上清液被剥夺了促炎/趋化因子，并且无法动员中性粒细胞并诱导树突状细胞成熟。此外，KIRA6 显着降低了死亡癌细胞对免疫原性化疗的体内疫苗接种潜力。从机制上讲，我们发现 KIRA6 的抗炎作用在 IRE1α 缺陷细胞中仍然有效，表明这种 IRE1α 激酶抑制剂具有迄今为止未知的脱靶效应。生成 KIRA6 可点击光亲和探针、质谱分析和免疫共沉淀分析，确定胞质 HSP60 是 IKK 驱动的 NF-κB 通路中 KIRA6 脱靶的物质。 总之，我们的研究揭示了 HSP60 是免疫原性治疗引起的 NF-κB/AP-1 炎症应激反应的 KIRA6 抑制上游调节因子。它还敦促在解释 IRE1α 化学抑制剂的抗炎作用时要小心。