Reg IV activates the epidermal growth factor receptor/Akt/AP-1 signaling pathway in colon adenocarcinomas
Reg IV activates the epidermal growth factor receptor/Akt/AP-1 signaling pathway in colon adenocarcinomas
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DOI：
10.1053/j.gastro.2005.10.001
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发表时间：
2006-01-01
期刊：
影响因子：
29.4
通讯作者：
Dieckgraefe, BK
中科院分区：
文献类型：
--
作者：
Bishnupuri, KS;Luo, QZ;Dieckgraefe, BK
背景和目标：Reg IV是Reg多基因家族的分泌蛋白和成员，在人胃肠道恶性肿瘤（包括结直肠癌（CRC））中上调。然而，Reg IV利用的体外信号传导途径尚不清楚。研究方法：为了确定响应于Reg IV的信号传导途径，我们检查了纯化的重组人Reg IV（rhR 4）对HCT 116和HT 29结肠腺癌细胞的作用。结果如下：向培养物中加入rhR 4导致细胞数量呈剂量依赖性增加，与用表皮生长因子（EGF）处理后观察到的结果相似。此外，rhR 4处理导致EGF受体在Tyr（992）和Tyr（1068）处以及Akt在Thr（308）和Ser（473）处的快速磷酸化。使用荧光素酶报告基因测定，我们证明了通过EGF受体和Akt的Reg IV信号传导导致激活蛋白-1（AP-1）转录因子活性增加。实时逆转录聚合酶链反应和Western印迹分析显示，与AP-1增加相关的c-Jun、JunB、JunD和FosB表达定量增加。活动电泳迁移率变动分析进一步揭示了在rhR 4处理的细胞中AP-1结合活性的显著增加，在JunB、JunD和FosB的抗体存在下具有增加的超变动。此外，rhR 4治疗导致Bcl-2、Bcl-XL、生存素和基质溶解素的表达增加，这些基因与晚期CRC的不良预后相关。结论：Reg IV是CRC中EGF受体/Akt/AP-1信号通路的有效激活剂。Reg信号传导的破坏可能具有作为人胃肠道腺癌的治疗干预的效用。
Background & Aims: Reg IV, a secreted protein and member of the Reg multigene family, is up-regulated in malignancies of the human gastrointestinal tract, including colorectal carcinoma (CRC). However, in vitro signal transduction pathway(s) utilized by Reg IV are not yet known. Methods: To determine the signaling pathway(s) responsive to Reg IV, we examined the effects of purified recombinant human Reg IV (rhR4) on HCT116 and HT29 colon adenocarcinoma cells. Results: Addition of rhR4 to cultures led to a dose-dependent increase in cell number similar to that observed after treatment with epidermal growth factor (EGF). In addition, rhR4 treatment resulted in rapid phosphorylation of EGF receptor at Tyr(992) and Tyr(1068) and Akt at Thr(308) and Ser(473). Using luciferase reporter gene assays, we demonstrated that Reg IV signaling through EGF receptor and Akt results in increased activator protein-1 (AP-1) transcription factor activity. Real-time reverse-transcription polymerase chain reaction and Western blot analyses revealed quantitative increases in c-Jun, JunB, JunD, and FosB expression associated with increased AP-1. activity. Electrophoretic mobility shift assay further revealed significant increases in AP-1 binding activity in rhR4-treated cells, with increased supershift in the presence of antibodies to JunB, JunD, and FosB. Furthermore, rhR4 treatments led to the increased expression of Bcl-2, Bcl-XL, survivin, and matrilysin, genes associated with a poor prognosis in advanced CRC. Conclusions: Reg IV is a potent activator of the EGF receptor/Akt/AP-1 signaling pathway in CRC. Disruption of Reg signaling may have utility as a therapeutic intervention for human gastrointestinal adenocarcinomas.