Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter, UK.
College of Pharmacy, Department Biochemistry and Clinical Chemistry, University of Sulaimani, Iraqi Kurdistan Region, Sulaimani, Iraq.
Cancer Immunol Immunother. 2022 Jul;71(7):1655-1669. doi: 10.1007/s00262-021-03072-6. Epub 2021 Nov 20.
Calreticulin (CRT) is an endoplasmic reticulum (ER) chaperone, but can appear surface bound on cancers cells, including ovarian cancers (OC). We investigated at what stage of cell viability, CRT appeared associated with surface of human OC cells. CRT on pre-apoptotic tumour cells is thought to initiate their eradication via a process termed immunogenic cell death (ICD).
We treated OC cells with the chemotherapeutic-doxorubicin (DX) known to induce translocation of CRT to some tumour cell surfaces, with and without the ER stressor-thapsigargin (TG)-and/or an ER stress inhibitor-TUDCA. We monitored translocation/release of CRT in pre-apoptotic cells by flow cytometry, immunoblotting and ELISA. We investigated the difference in binding of FITC-CRT to pre-apoptotic, apoptotic and necrotic cells and the ability of extracellular CRT to generate immature dendritic cells from THP-1 monocytes.
Dx-treatment increased endogenously released CRT and extracellular FITC_CRT binding to human pre-apoptotic OC cells. DX and TG also promoted cell death in OC cells which also increased CRT release. These cellular responses were significantly inhibited by TUDCA, suggesting that ER stress is partially responsible for the changes in CRT cellular distribution. Extracellular CRT induces maturation of THP-1 towards a imDC phenotype, an important component of ICD.
Collectively, these cellular responses suggest that ER stress is partially responsible for the changes in CRT cellular distribution. ER-stress regulates in part the release and binding of CRT to human OC cells where it may play a role in ICD.
钙网织蛋白（CRT）是内质网（ER）伴侣，但可出现在包括卵巢癌（OC）在内的癌细胞表面结合。我们研究了 CRT 何时与人类 OC 细胞表面相关联，处于细胞存活的哪个阶段。人们认为，凋亡前肿瘤细胞表面的 CRT 启动了它们的清除过程，即免疫原性细胞死亡（ICD）。
我们用化疗药物阿霉素（DX）处理 OC 细胞，已知 DX 可诱导 CRT 向一些肿瘤细胞表面转移，同时使用内质网应激剂 thapsigargin（TG）和/或内质网应激抑制剂 TUDCA。我们通过流式细胞术、免疫印迹和 ELISA 监测凋亡前细胞中 CRT 的易位/释放。我们研究了 FITC-CRT 与凋亡前、凋亡和坏死细胞的结合差异，以及细胞外 CRT 从 THP-1 单核细胞产生未成熟树突状细胞的能力。
DX 处理增加了内源性释放的 CRT 和人凋亡前 OC 细胞中外源 FITC-CRT 的结合。DX 和 TG 也促进了 OC 细胞的细胞死亡，这也增加了 CRT 的释放。TUDCA 显著抑制了这些细胞反应，表明内质网应激部分负责 CRT 细胞分布的变化。细胞外 CRT 诱导 THP-1 向不成熟树突状细胞（imDC）表型成熟，这是 ICD 的重要组成部分。
总之，这些细胞反应表明内质网应激部分负责 CRT 细胞分布的变化。内质网应激部分调节 CRT 与人 OC 细胞的释放和结合，在 ICD 中可能发挥作用。
