Wei Nana, Lin Zhibing, Xu Zhengmao, Cao Jie, Zhou Yongzhi, Zhang Houshuang, Gong Haiyan, Zhou Jinlin, Li Guoqing
Guangdong Provincial Zoonosis Prevention and Control Key Laboratory, College of Veterinary Medicine, South China Agricultural University, Guangzhou, China.
Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, China.
Cell Physiol Biochem. 2018;46(6):2385-2400. doi: 10.1159/000489645. Epub 2018 May 8.
BACKGROUND/AIMS: We previously identified a potent and tight-binding inhibitor of cysteine proteases from Rhipicephalus haemaphysaloides, RHcyst-1, which belongs to the cystatin type 1 family. Cathepsins, which are members of the cysteine protease family, participate in various pathological processes, including the initiation and development of cancers. The present study aimed to investigate the antitumor effects of RHcyst-1 and to explore the underlying mechanism of these effects.
Different tumor cells were treated with RHcyst-1 in vitro. Proliferation activity was evaluated using Cell Counting Kit-8, and migration and invasion were determined by wound healing and Transwell® invasion assays. In addition, a mouse tumor therapy model was established by inoculating the left forelimb of mice with B16-F10 cells, and tumor progression was evaluated by assessing tumor volume and survival. Flow cytometry was conducted to evaluate myeloid-derived suppressor cells (MDSCs), CD4+, and CD8+ T cell levels in PBMCs and spleens. Immunohistochemistry was performed to analyze immune cell infiltration and angiogenesis in the tumors.
RHcyst-1 significantly inhibited the proliferation, migration, and invasion of all four different tumor cells in vitro. Additionally, it inhibited tumor growth and improved survival in vivo. A decrease and an increase in MDSCs levels were observed in PBMCs and in the spleen, respectively, after RHcyst-1 application.
Tick RHcyst-1 has potential antitumor efficacy, and the observed antitumor activities may be partly attributable to changes in cathepsin expression and MDSCs levels in the PBMCs and spleens. The findings of the present study suggest that RHcyst-1 may have the potential to be utilized in cancer treatment.
背景/目的：我们之前从血红扇头蜱中鉴定出一种强效且紧密结合的半胱氨酸蛋白酶抑制剂RHcyst-1，它属于胱抑素1家族。组织蛋白酶作为半胱氨酸蛋白酶家族的成员，参与多种病理过程，包括癌症的发生和发展。本研究旨在探讨RHcyst-1的抗肿瘤作用，并探索其作用的潜在机制。
在体外使用RHcyst-1处理不同的肿瘤细胞。使用细胞计数试剂盒-8评估增殖活性，通过伤口愈合和Transwell®侵袭试验测定迁移和侵袭能力。此外，通过将B16-F10细胞接种到小鼠左前肢建立小鼠肿瘤治疗模型，并通过评估肿瘤体积和生存期来评估肿瘤进展。进行流式细胞术以评估外周血单核细胞（PBMC）和脾脏中髓源性抑制细胞（MDSC）、CD4+和CD8+ T细胞水平。进行免疫组织化学分析肿瘤中的免疫细胞浸润和血管生成。
RHcyst-1在体外显著抑制了所有四种不同肿瘤细胞的增殖、迁移和侵袭。此外，它在体内抑制肿瘤生长并提高生存期。应用RHcyst-1后，分别在PBMC和脾脏中观察到MDSC水平的降低和升高。
蜱虫的RHcyst-1具有潜在的抗肿瘤功效，观察到的抗肿瘤活性可能部分归因于PBMC和脾脏中组织蛋白酶表达和MDSC水平的变化。本研究结果表明，RHcyst-1可能具有用于癌症治疗的潜力。
