Wang Sen, Zhang Zhiyuan, Qian Wenwei, Ji Dongjian, Wang Qingyuan, Ji Bing, Zhang Yue, Zhang Chuan, Sun Ye, Zhu Chunyan, Sun Yueming
Department of Colorectal Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu 210029, China,
Onco Targets Ther. 2018 Jul 2;11:3765-3774. doi: 10.2147/OTT.S164982. eCollection 2018.
Vasculogenic mimicry (VM) describes the formation of an epithelial-independent tumor microcirculation system that differs from traditional angiogenesis. Angiogenesis and the formation of VM are closely related through the cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA) pathway and the epithelial-mesenchymal transition (EMT) process.
In this study, 8-Br-cAMP, a cAMP analog and PKA activator, was used to activate the cAMP/PKA pathway to evaluate the effects of cAMP/PKA on angiogenesis and VM in colorectal cancer (CRC) cells. We used a syngeneic model of CRC in BALB/c mice.
We discovered that treatment with 8-Br-cAMP significantly reduced tumor number compared to control mice after the 7th, 14th, and 28th days of treatment. VM was evaluated by periodic acid-schiff (PAS)-CD31 staining, and we found that VM was inhibited by 8-Br-cAMP treatment in vivo. Immunohistochemistry confirmed the inhibition of vascular endothelial growth factor (VEGF) and cAMP and the activation of PKA by 8-Br-cAMP; quantitative real-time-PCR (qRT-PCR) demonstrated that 8-Br-cAMP regulated the expression of vascular endothelial (VE)-cadherin, matrix metalloproteinase 2 (MMP2), ephrin type-A receptor 2 (EphA2), and VEGF in vivo. Experiments in vitro revealed that treatment with 8-Br-cAMP and U0126 decreased VEGF expression through PKA-ERK in CT26 cells by qRT-PCR. We further confirmed that tube formation of human umbilical vein endothelial cells was inhibited by 8-Br-cAMP in vitro.
This study demonstrates that angiogenesis and VM are inhibited by 8-Br-cAMP treatment. Our data indicate that 8-Br-cAMP acts through the cAMP/PKA-ERK pathway and through EMT processes in CRC. These findings provide an insight into mechanisms of CRC and suggest that the cAMP/PKA-ERK pathway is a novel potential therapeutic target for the treatment of CRC.
血管生成拟态（VM）描述了一种独立于上皮细胞的肿瘤微循环系统的形成，该系统不同于传统的血管生成。血管生成与VM的形成通过环磷酸腺苷（cAMP）/蛋白激酶A（PKA）途径以及上皮-间质转化（EMT）过程密切相关。
在本研究中，使用cAMP类似物及PKA激活剂8-溴-cAMP来激活cAMP/PKA途径，以评估cAMP/PKA对结直肠癌（CRC）细胞血管生成和VM的影响。我们采用了BALB/c小鼠的CRC同基因模型。
我们发现，在治疗的第7天、14天和28天后，与对照小鼠相比，用8-溴-cAMP治疗显著减少了肿瘤数量。通过过碘酸-希夫（PAS）-CD31染色评估VM，我们发现在体内8-溴-cAMP治疗可抑制VM。免疫组织化学证实8-溴-cAMP可抑制血管内皮生长因子（VEGF）和cAMP，并激活PKA；定量实时聚合酶链反应（qRT-PCR）表明，8-溴-cAMP在体内调节血管内皮（VE）-钙黏蛋白、基质金属蛋白酶2（MMP2）、 Ephrin A型受体2（EphA2）和VEGF的表达。体外实验通过qRT-PCR显示，用8-溴-cAMP和U0126处理可通过PKA-ERK降低CT26细胞中VEGF的表达。我们进一步证实在体外8-溴-cAMP可抑制人脐静脉内皮细胞的管腔形成。
本研究表明，8-溴-cAMP治疗可抑制血管生成和VM。我们的数据表明，8-溴-cAMP通过cAMP/PKA-ERK途径以及CRC中的EMT过程发挥作用。这些发现为CRC的机制提供了见解，并表明cAMP/PKA-ERK途径是治疗CRC的一个新的潜在治疗靶点。
