Department of Human and Molecular Genetics, VCU Institute of Molecular Medicine, VCU Massey Cancer Center, Virginia Commonwealth University School of Medicine, Richmond, VA 23298, USA.
Cancer Res. 2013 Apr 1;73(7):2093-103. doi: 10.1158/0008-5472.CAN-12-1740. Epub 2013 Jan 18.
Converting the immunosuppressive tumor environment into one that is favorable to the induction of antitumor immunity is indispensable for effective cancer immunotherapy. Here, we strategically incorporate a pathogen (i.e., flagellin)-derived, NF-κB-stimulating "danger" signal into the large stress protein or chaperone Grp170 (HYOU1/ORP150) that was previously shown to facilitate antigen crosspresentation. This engineered chimeric molecule (i.e., Flagrp170) is capable of transporting tumor antigens and concurrently inducing functional activation of dendritic cells (DC). Intratumoral administration of adenoviruses expressing Flagrp170 induces a superior antitumor response against B16 melanoma and its distant lung metastasis compared with unmodified Grp170 and flagellin. The enhanced tumor destruction is accompanied with significantly increased tumor infiltration by CD8(+) cells as well as elevation of IFN-γ and interleukin (IL)-12 levels in the tumor sites. In situ Ad.Flagrp170 therapy provokes systemic activation of CTLs that recognize several antigens naturally expressing in melanoma (e.g., gp100/PMEL and TRP2/DCT). The mechanistic studies using CD11c-DTR transgenic mice and Batf3-deficient mice reveal that CD8α(+) DCs are required for the improved T-cell crosspriming. Antibody neutralization assays show that IL-12 and IFN-γ are essential for the Flagrp170-elicited antitumor response, which also involves CD8(+) T cells and natural killer cells. The therapeutic efficacy of Flagrp170 and its immunostimulating activity are also confirmed in mouse prostate cancer and colon carcinoma. Together, targeting the tumor microenvironment with this chimeric chaperone is highly effective in mobilizing or restoring antitumor immunity, supporting the potential therapeutic use of this novel immunomodulator in the treatment of metastatic diseases.
将免疫抑制性肿瘤微环境转化为有利于诱导抗肿瘤免疫的环境，对于有效的癌症免疫治疗是必不可少的。在这里，我们策略性地将一种源自病原体（即鞭毛蛋白）、能刺激 NF-κB 的“危险”信号整合到先前被证明有助于抗原交叉呈递的大型应激蛋白或伴侣 Grp170（HYOU1/ORP150）中。这种工程化的嵌合分子（即 Flagrp170）能够运输肿瘤抗原，并同时诱导树突状细胞（DC）的功能激活。与未修饰的 Grp170 和鞭毛蛋白相比，肿瘤内注射表达 Flagrp170 的腺病毒可诱导对 B16 黑色素瘤及其远处肺转移的更强的抗肿瘤反应。增强的肿瘤破坏伴随着 CD8+细胞在肿瘤部位的显著浸润增加，以及 IFN-γ 和白细胞介素（IL）-12 水平的升高。原位 Ad.Flagrp170 治疗引发 CTL 的全身性激活，这些 CTL 可识别黑色素瘤中自然表达的多种抗原（例如，gp100/PMEL 和 TRP2/DCT）。使用 CD11c-DTR 转基因小鼠和 Batf3 缺陷型小鼠的机制研究表明，CD8α+DC 是改善 T 细胞交叉呈递所必需的。抗体中和试验表明，IL-12 和 IFN-γ 是 Flagrp170 引发的抗肿瘤反应所必需的，该反应还涉及 CD8+T 细胞和自然杀伤细胞。Flagrp170 的治疗效果及其免疫刺激活性也在小鼠前列腺癌和结肠癌中得到了证实。总之，用这种嵌合伴侣靶向肿瘤微环境在动员或恢复抗肿瘤免疫方面非常有效，支持这种新型免疫调节剂在治疗转移性疾病中的潜在治疗用途。
