Ma Ting-Ting, Wang Lin, Wang Jun-Lin, Liu Yan-Jie, Chen Yu-Cong, He Hu-Jie, Song Yong
Department of Stomatology, Liuzhou People's Hospital, Guangxi, People's Republic of China.
Department of Oral and Maxillofacial-Head and Neck Oncology, School and Hospital of Stomatology, Wuhan University, Wuhan, People's Republic of China.
Onco Targets Ther. 2019 Oct 14;12:8491-8499. doi: 10.2147/OTT.S213252. eCollection 2019.
ephrinA1 plays important roles in tumor angiogenesis. Matrix metalloproteases (MMPs) can cleave ephrinA1 from the cell membrane into extracellular environment. However, how soluble ephrinA1 is modulated by hypoxia and whether MMPs participate in this hypoxic process remains to be investigated in detail.
Thirty-seven patients with oral squamous cell carcinoma (OSCC) were included in the present study for HIF-1α, MMP-2, MMP-9 and ephrinA1 detection by immunohistochemistry. Serum samples from 35 patients were collected both preoperatively and postoperatively to confirm the existence of soluble ephrinA1 by ELISA. Block assay and Western blot analysis were further carried out to elucidate the proteolysis mechanism of ephrinA1 under hypoxic condition in vitro.
Our data demonstrated that HIF-1α, MMP-2, MMP-9 and ephrinA1 expressed positively, and correlated with microvessel density in OSCCs, except for MMP-9. The serum expression level of ephrinA1 in OSCC patients decreased significantly after surgical removal of the solid tumors. In vitro experiments indicated that GM6001, a MMP-specific inhibitor, could reduce hypoxia-induced soluble ephrinA1 secretion from SCC cells. Further Western blot analysis confirmed that both HIF-1α and MMP-2 were up-regulated by hypoxia in a similar time-dependent manner, with the MMP-9 expression unchanged during this course.
These results suggested a possible novel mechanism that ephrinA1 secretion is mediated by HIF-1α/MMP-2 signaling cascade which may play pivotal roles in OSCC neovascularization in a paracrine manner.
ephrinA1在肿瘤血管生成中发挥重要作用。基质金属蛋白酶（MMPs）可将ephrinA1从细胞膜上切割下来释放到细胞外环境中。然而，可溶性ephrinA1如何受缺氧调节以及MMPs是否参与这一缺氧过程仍有待详细研究。
本研究纳入37例口腔鳞状细胞癌（OSCC）患者，采用免疫组织化学法检测HIF-1α、MMP-2、MMP-9和ephrinA1。收集35例患者术前和术后的血清样本，通过酶联免疫吸附测定（ELISA）法确认可溶性ephrinA1的存在。进一步进行阻断试验和蛋白质印迹分析，以阐明体外缺氧条件下ephrinA1的蛋白水解机制。
我们的数据表明，除MMP-9外，HIF-1α、MMP-2、MMP-9和ephrinA1在OSCC中呈阳性表达，且与微血管密度相关。手术切除实体瘤后，OSCC患者血清中ephrinA1的表达水平显著降低。体外实验表明，MMP特异性抑制剂GM6001可减少缺氧诱导的SCC细胞可溶性ephrinA1分泌。进一步的蛋白质印迹分析证实，缺氧以类似的时间依赖性方式上调HIF-1α和MMP-2，在此过程中MMP-9表达未发生变化。
这些结果提示了一种可能的新机制，即ephrinA1的分泌由HIF-1α/MMP-2信号级联介导，这可能以旁分泌方式在OSCC新生血管形成中起关键作用。
