Koyanagi Takahiro, Suzuki Yasuhiro, Komori Kazuki, Saga Yasushi, Matsubara Shigeki, Fujiwara Hiroyuki, Sato Yasufumi
Department of Vascular Biology, Institute of Development, Aging, and Cancer, Tohoku University, Sendai, Japan.
Department of Obstetrics and Gynecology, School of Medicine, Jichi Medical University, Tochigi, Japan.
Cancer Sci. 2017 Mar;108(3):512-519. doi: 10.1111/cas.13149.
There are two members of the vasohibin (VASH) family, VASH1 and VASH2. VASH1 is expressed mainly in endothelial cells to inhibit angiogenesis, whereas VASH2 is expressed mainly in cancer cells to stimulate tumor growth. The aim of the present study was to establish neutralizing monoclonal antibody (mAb) against human VASH2 and apply it as an anti-cancer treatment. We previously raised mAb against several synthetic peptides of hVASH1, and found that one of them exhibited neutralizing activity against hVASH1. Because of the similarity in the amino acid sequences between VASH1 and VASH2, we hypothesized that they shared the bioactive center. When we mutated four amino acids within the region, the mutant VASH2 lost its pro-angiogenic activity. Therefore, we raised mAb against a synthetic peptide overlapping the mutated amino acids of hVASH2, and isolated one clone (1760) that almost completely inhibited the stimulatory effect of hVASH2 on the migration of and tube formation by endothelial cells. When we used this clone 1760 antibody for cancer treatment, the peritoneal injection of it inhibited both tumor growth and angiogenesis in a mouse xenograft model of human cancer cells. In terms of anti-tumor activity, 25 mg/kg of clone 1760 was equivalent to 5 mg/kg of bevacizmab. From these results, we propose the targeting of human VASH2 with neutralizing mAb as a new strategy for cancer treatment.
血管抑制素（VASH）家族有两个成员，即VASH1和VASH2。VASH1主要在内皮细胞中表达以抑制血管生成，而VASH2主要在癌细胞中表达以刺激肿瘤生长。本研究的目的是制备抗人VASH2的中和单克隆抗体（mAb）并将其用作抗癌治疗。我们之前制备了针对hVASH1几种合成肽的mAb，并发现其中一种对hVASH1具有中和活性。由于VASH1和VASH2氨基酸序列相似，我们推测它们共享生物活性中心。当我们在该区域内突变四个氨基酸时，突变型VASH2失去了其促血管生成活性。因此，我们制备了针对与hVASH2突变氨基酸重叠的合成肽的mAb，并分离出一个克隆（1760），该克隆几乎完全抑制了hVASH2对内皮细胞迁移和管形成的刺激作用。当我们将该克隆1760抗体用于癌症治疗时，腹腔注射它可抑制人癌细胞小鼠异种移植模型中的肿瘤生长和血管生成。在抗肿瘤活性方面，25mg/kg的克隆1760相当于5mg/kg的贝伐单抗。基于这些结果，我们提出用中和mAb靶向人VASH2作为一种新的癌症治疗策略。
