Suppression of proHB-EGF carboxy-terminal fragment nuclear translocation: A new molecular target therapy for gastric cancer
Suppression of proHB-EGF carboxy-terminal fragment nuclear translocation: A new molecular target therapy for gastric cancer
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DOI：
10.1158/1078-0432.ccr-07-4794
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发表时间：
2008-06-15
影响因子：
11.5
通讯作者：
Joh, Takashi
中科院分区：
文献类型：
--
作者：
Shimura, Takaya;Kataoka, Hiromi;Joh, Takashi
目的：表皮生长因子受体(EGFR)失活是发展上皮癌选择性治疗的一种有前景的策略，已被广泛研究为肿瘤治疗的分子靶点。然而，很少有人注意到由EGFR配体裂解产生的残存细胞相关结构域。本研究的重点是最近的研究发现，膜锚定的肝素结合的EGF样生长因子(proHB-EGF)是一种EGFR配体，它可以诱导HB-EGF的羧基末端片段(CTF)从质膜移位到细胞核，并调节细胞周期。实验设计：使用两种胃癌细胞系MKN28和NUGC4。西妥昔单抗可抑制EGFR的磷酸化，从而抑制HB-EGF-CTF的核转位。3-(4，5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium，内盐法检测细胞生长，半胱氨酸天冬氨酸氨基转移酶-3、7检测细胞凋亡率，流式细胞仪检测细胞周期。结果：免疫荧光实验证实，在12-O-十四酰佛波醇-13-乙酸酯诱导的胃癌细胞中，KB-R7785可抑制HB-EGF-CTF的核转位。KB-R7785呈剂量依赖性抑制细胞生长，高剂量KB-R7785可诱导细胞凋亡。此外，KB-R7785还可诱导细胞周期停滞，并使亚G期DNA含量增加。KB-R7785抑制细胞周期蛋白A和c-Myc的表达。结论：抑制EGFR磷酸化和抑制HB-EGF-CTF核转位在抑制癌细胞生长中起重要作用。抑制HB-EGF-CTF核转位可能为胃癌的治疗提供新的策略。
Purpose: Inactivation of epidermal growth factor (EGF) receptor (EGFR) represents a promising strategy for the development of selective therapies against epithelial cancers and has been extensively studied as a molecular target for cancer therapy. However, little attention has been paid to remnant cell-associated domains created by cleavage of EGFR ligands. The present study focused on recent findings that cleavage of membrane-anchored heparin-binding EGF-like growth factor (proHB-EGF), an EGFR ligand, induces translocation of the carboxyl-terminal fragment (CTF) of HB-EGF from the plasma membrane to the nucleus and regulates cell cycle.Experimental Design: Two gastric cancer cell lines, MKN28 and NUGC4, were used. KB-R7785, an inhibitor of proHB-EGF shedding, was used to suppress HB-EGF-CTF nuclear translocation with cetuximab, which inhibits EGFR phosphorylation. Cell growth was analyzed using 3- (4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt assay, apoptosis was evaluated by assay of caspase-3 and caspase-7, and cell cycle was investigated by flow cytometry.Results: Immunofluorescence study confirmed that KB-R7785 inhibited HB-EGF-CTF nuclear translocation under conditions of proHB-EGF shedding induction by 12-O-tetradecanoylphorbol-13-acetate in gastric cancer cells. KB-R7785 inhibited cell growth in a dose-dependent manner and high-dose KB-R7785 induced apoptosis. Moreover, KB-R7785 induced cell cycle arrest and increased sub-G, DNA content. KB-R7785 suppressed cyclin A and c-Myc expression. All effects of KB-R7785 were reinforced by combination with cetuximab.Conclusions: These results suggest that both inhibition of EGFR phosphorylation and inhibition of HB-EGF-CTF nuclear translocation play crucial roles in inhibitory regulation of cancer cell growth. Suppression of HB-EGF-CTF nuclear translocation might offer a new strategy for treating gastric cancer.