Down-regulation of RalGTPase-Activating Protein Promotes Colitis-Associated Cancer via NLRP3 Inflammasome Activation
Down-regulation of RalGTPase-Activating Protein Promotes Colitis-Associated Cancer via NLRP3 Inflammasome Activation
复制标题
DOI：
10.1016/j.jcmgh.2019.10.003
复制
发表时间：
2020-01-01
影响因子：
7.2
通讯作者：
Nakase, Hiroshi
中科院分区：
文献类型：
--
作者：
Iida, Tomoya;Hirayama, Daisuke;Nakase, Hiroshi
背景与目的：鸟苷三磷酸酶激活蛋白α 2（RalGAP α 2）是小分子鸟苷三磷酸酶Ral的负调节子的主要催化亚基。Ral调节某些癌症的肿瘤发生和侵袭/转移;然而，Ral在结肠炎相关癌症（CAC）中的作用尚未研究。方法：我们使用野生型（WT）小鼠和RalGAP α 2基因敲除（KO）小鼠，按照如下方法制备骨髓嵌合体小鼠：WT与WT，WT与RalGAP α 2基因敲除，RalGAP α 2基因敲除与WT，RalGAP α 2基因敲除与RalGAP α 2基因敲除。通过腹腔注射氧化偶氮甲烷，然后摄入葡聚糖硫酸钠，在这些小鼠中诱导CAC。从结肠组织中分离肠上皮细胞，并进行互补DNA微阵列分析。结果：骨髓嵌合体小鼠与RalGAP α 2 KO小鼠在CAC发病机制上的免疫细胞功能无明显差异。与WT小鼠相比，RalGAP α 2 KO小鼠具有显著更大的肿瘤数量和大小以及显著更高比例的侵袭粘膜下层的肿瘤。在RalGAP α 2 KO小鼠中观察到基质金属蛋白酶-9和基质金属蛋白酶-13的表达水平高于WT小鼠。与WT小鼠相比，RalGAP α 2 KO小鼠的肿瘤中白细胞介素1 β、NLRP 3、含有CARD的凋亡相关斑点样蛋白和半胱天冬酶-1的表达水平明显增加。结论：Ral激活通过NLRP 3炎性体激活参与CAC的发生发展机制。
BACKGROUND & AIMS: Ral guanosine triphosphatase-activating protein alpha 2 (RalGAP alpha 2) is themajor catalytic subunit of the negative regulators of the small guanosine triphosphatase Ral, a member of the Ras subfamily. Ral regulates tumorigenesis and invasion/metastasis of some cancers; however, the role of Ral in colitis-associated cancer (CAC) has not been investigated. We aimed to elucidate the role of Ral in the mechanism of CAC.METHODS: We used wild-type (WT) mice and RalGAP alpha 2 knockout (KO) mice that showed Ral activation, and bone marrow chimeric mice were generated as follows: WT to WT, WT to RalGAP alpha 2 KO, RalGAP alpha 2 KO to WT, and RalGAP alpha 2 KO to RalGAP alpha 2 KO mice. CAC was induced in these mice by intraperitoneal injection of azoxymethane followed by dextran sulfate sodium intake. Intestinal epithelial cells were isolated from colon tissues, and we performed complementary DNA microarray analysis. Cytokine expression in normal colon tissues and CAC was analyzed by quantitative polymerase chain reaction.RESULTS: Bone marrow chimeric mice showed that immune cell function between WT mice and RalGAP alpha 2 KO mice was not significantly different in the CAC mechanism. RalGAP alpha 2 KOmice had a significantly larger tumor number and size and a significantly higher proportion of tumors invading the submucosa than WT mice. Higher expression levels of matrix metalloproteinase-9 and matrix metalloproteinase-13 were observed in RalGAP alpha 2 KO mice than in WT mice. The expression levels of interleukin 1 beta, NLRP3, apoptosis associated speck-like protein containing a CARD, and caspase-1 were apparently increased in the tumors of RalGAP alpha 2 KO mice compared with WT mice. NLRP3 inhibitor reduced the number of invasive tumors.CONCLUSIONS: Ral activation participates in the mechanism of CAC development via NLRP3 inflammasome activation.