1] INSERM, U848, Villejuif, France [2] Institut Gustave Roussy, Villejuif, France [3] Université Paris Sud/Paris XI, Le Kremlin Bicêtre, France.
Cell Death Differ. 2014 Jan;21(1):59-68. doi: 10.1038/cdd.2013.73. Epub 2013 Jun 21.
The exposure of calreticulin (CRT) on the surface of stressed and dying cancer cells facilitates their uptake by dendritic cells and the subsequent presentation of tumor-associated antigens to T lymphocytes, hence stimulating an anticancer immune response. The chemotherapeutic agent mitoxantrone (MTX) can stimulate the peripheral relocation of CRT in both human and yeast cells, suggesting that the CRT exposure pathway is phylogenetically conserved. Here, we show that pheromones can act as physiological inducers of CRT exposure in yeast cells, thereby facilitating the formation of mating conjugates, and that a large-spectrum inhibitor of G protein-coupled receptors (which resemble the yeast pheromone receptor) prevents CRT exposure in human cancer cells exposed to MTX. An RNA interference screen as well as transcriptome analyses revealed that chemokines, in particular human CXCL8 (best known as interleukin-8) and its mouse ortholog Cxcl2, are involved in the immunogenic translocation of CRT to the outer leaflet of the plasma membrane. MTX stimulated the production of CXCL8 by human cancer cells in vitro and that of Cxcl2 by murine tumors in vivo. The knockdown of CXCL8/Cxcl2 receptors (CXCR1/Cxcr1 and Cxcr2) reduced MTX-induced CRT exposure in both human and murine cancer cells, as well as the capacity of the latter-on exposure to MTX-to elicit an anticancer immune response in vivo. Conversely, the addition of exogenous Cxcl2 increased the immunogenicity of dying cells in a CRT-dependent manner. Altogether, these results identify autocrine and paracrine chemokine signaling circuitries that modulate CRT exposure and the immunogenicity of cell death.
钙网织蛋白（CRT）在应激和濒死癌细胞表面的暴露有助于树突状细胞摄取它们，并随后将肿瘤相关抗原呈递给 T 淋巴细胞，从而刺激抗肿瘤免疫反应。化疗药物米托蒽醌（MTX）可以刺激人类和酵母细胞中 CRT 的外周重新定位，这表明 CRT 暴露途径在进化上是保守的。在这里，我们表明，信息素可以作为酵母细胞中 CRT 暴露的生理诱导剂，从而促进交配融合体的形成，并且 G 蛋白偶联受体的广谱抑制剂（类似于酵母信息素受体）可以阻止 MTX 暴露的人类癌细胞中 CRT 的暴露。RNA 干扰筛选和转录组分析表明，趋化因子，特别是人类 CXCL8（最著名的是白细胞介素-8）及其小鼠同源物 Cxcl2，参与 CRT 向质膜外叶的免疫易位。MTX 刺激人类癌细胞在体外产生 CXCL8，在体内刺激小鼠肿瘤产生 Cxcl2。CXCL8/Cxcl2 受体（CXCR1/Cxcr1 和 Cxcr2）的敲低降低了 MTX 诱导的人类和小鼠癌细胞中 CRT 的暴露，以及后者在 MTX 暴露后在体内引发抗肿瘤免疫反应的能力。相反，外源性 Cxcl2 的添加以 CRT 依赖的方式增加了死亡细胞的免疫原性。总的来说，这些结果确定了调节 CRT 暴露和细胞死亡免疫原性的自分泌和旁分泌趋化因子信号通路。
