Molecular imaging of N-linked glycosylation suggests glycan biosynthesis is a novel target for cancer therapy.
Molecular imaging of N-linked glycosylation suggests glycan biosynthesis is a novel target for cancer therapy.
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DOI：
10.1158/1078-0432.ccr-09-3331
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发表时间：
2010-06-15
期刊：
影响因子：
--
通讯作者：
Lawrence TS
中科院分区：
文献类型：
--
作者：
Contessa JN;Bhojani MS;Freeze HH;Ross BD;Rehemtulla A;Lawrence TS
冗余受体酪氨酸激酶（RTK）信号传导是对EGFR抑制的治疗抗性的机制。通过共表达的RTK减少平行信号传导的策略是抑制N-连接的糖基化（NLG），其是受体成熟和细胞表面表达所需的内质网（ER）共翻译蛋白修饰。因此，我们研究了在体内阻断NLG以减少RTK过表达的可行性。我们开发了一个模型系统，动态监测NLG在体外和体内使用生物发光成像技术。NLG的功能成像是用针对ER翻译和糖基化修饰的荧光素酶报告基因（ER-LucT）完成的。在体外验证后，将该报告基因与D54胶质瘤异种移植物整合以进行肿瘤的非侵入性成像，并且NLG的抑制与RTK蛋白水平和肿瘤生长相关。ER-LucT报告基因证明了灵敏和特异性检测NLG抑制的能力。使用这种分子成像方法，我们进行了一系列成像研究，以确定GlcNAc-1-磷酸转移酶抑制剂衣霉素（其阻断N-聚糖前体生物合成）的安全有效的体内给药。衣霉素处理的肿瘤的分子分析显示EGFR和Met的水平降低，这两种RTK在胶质瘤中过表达。此外，D54和U87 MG神经胶质瘤异种移植肿瘤实验证明NLG抑制和放射治疗后肿瘤生长显著减少，与肿瘤放射敏感性的增强一致。这项研究表明，NLG抑制是一种新的治疗策略，靶向EGFR和RTK信号在胶质瘤和其他恶性肿瘤。
Redundant receptor tyrosine kinase (RTK) signaling is a mechanism for therapeutic resistance to EGFR inhibition. A strategy to reduce parallel signaling by co-expressed RTKs is inhibition of N-linked glycosylation (NLG), an endoplasmic reticulum (ER) co-translational protein modification required for receptor maturation and cell surface expression. We therefore investigated the feasibility of blocking NLG in vivo to reduce over-expression of RTKs. We developed a model system to dynamically monitor NLG in vitro and in vivo using bioluminescent imaging techniques. Functional imaging of NLG is accomplished with a luciferase reporter (ER-LucT) modified for ER-translation and glycosylation. After in vitro validation, this reporter was integrated with D54 glioma xenografts to perform non-invasive imaging of tumors, and inhibition of NLG was correlated with RTK protein levels and tumor growth. The ER-LucT reporter demonstrates the ability to sensitively and specifically detect NLG inhibition. Using this molecular imaging approach we performed serial imaging studies to determine safe and efficacious in vivo dosing of the GlcNAc-1-phosphotransferase inhibitor, tunicamycin, which blocks N-glycan precursor biosynthesis. Molecular analyses of tunicamycin treated tumors showed reduced levels of EGFR and Met, two RTKs over-expressed in gliomas. Furthermore, D54 and U87MG glioma xenograft tumor experiments demonstrated significant reductions in tumor growth following NLG inhibition and radiation therapy, consistent with an enhancement in tumor radiosensitivity. This study suggests NLG inhibition is a novel therapeutic strategy for targeting EGFR and RTK signaling in both gliomas and other malignant tumors.