[论文解读] Antiproliferative MCR peptides block physical interaction of insulin with retinoblastoma protein (RB) in human lung cancer cells

Razvan T. Radulescu, Kai Kehe|ArXiv.org|Jun 13, 2007

Cancer-related Molecular Pathways参考文献 8被引用 12

一句话总结

本研究证明，抗增殖性MCR肽，特别是MCR-4和MCR-10，可破坏A549人非小细胞肺癌细胞中胰岛素与视网膜母细胞瘤肿瘤抑制蛋白（RB）之间的物理相互作用。通过磁珠介导的免疫沉淀法，作者证实了这些细胞中胰岛素-RB异源二聚体的形成，并表明MCR肽可选择性阻断该复合物，从而验证胰岛素-RB相互作用作为癌症治疗的治疗靶点。

ABSTRACT

Fifteen years ago, a structural analysis of the hormone insulin and the retinoblastoma tumor suppressor protein (RB) revealed that they may physically interact with one another. Subsequently, an RB peptide corresponding to the proposed RB binding site for insulin was found to recognize full-length insulin in vitro. As part of efforts aimed at developing this RB peptide into an anti-cancer drug, this molecule was chemically coupled to a cellular internalization signal and termed "MCR peptide". Meanwhile, several such MCR peptide variants have been demonstrated to restrain the proliferation of different human cancer cells in vitro and in vivo. Moreover, one of the MCR peptides coined MCR-10 was shown to be capable of interfering with the complex formation between insulin and RB in HepG2 human hepatoma cells, as monitored by immunofluorescence. This latter result indicating an in vivo association between insulin and RB was confirmed by a follow-up study combining the methods of co-immunoprecipitation and immunoblotting. Here, we provide evidence for the existence of the insulin-RB complex in A549 human non-small cell lung cancer cells. Specifically, we demonstrate this heterodimer by means of a magnetic beads-based immunoprecipitation approach and equally show that this dimer can be disrupted by MCR-4 or MCR-10 each of which is known to possess antiproliferative properties, yet to a much lesser extent by a control peptide. Thus, this investigation has yielded another important proof for the occurrence of the insulin-RB dimer and, furthermore, its validity as a target for antineoplastic MCR peptides.

研究动机与目标

• 研究胰岛素与视网膜母细胞瘤蛋白（RB）是否在人肺癌细胞中发生物理相互作用。
• 确定抗增殖性MCR肽是否能破坏A549细胞中的胰岛素-RB复合物。
• 验证胰岛素-RB二聚体作为MCR肽基抗癌疗法的功能性靶点。
• 比较MCR-4、MCR-10和对照肽在破坏胰岛素-RB相互作用方面的效力。

提出的方法

• 采用磁珠介导的免疫沉淀法，从A549人肺癌细胞中分离并检测胰岛素-RB异源二聚体。
• 采用共免疫沉淀和免疫印迹法，确认胰岛素与RB之间的物理关联。
• 测试先前已显示具有抗增殖效应的MCR-4和MCR-10肽，评估其破坏胰岛素-RB复合物的能力。
• 使用无抗增殖活性的对照肽作为阴性对照，以评估特异性。
• 对经MCR肽或对照处理后的A549细胞裂解物，检测胰岛素和RB的表达。
• 对各处理组中的胰岛素-RB复合物进行定量，并进行比较。

实验结果

研究问题

• RQ1 胰岛素与视网膜母细胞瘤蛋白（RB）是否在A549人非小细胞肺癌细胞中发生物理相互作用？
• RQ2 MCR-4或MCR-10肽是否能破坏A549细胞中的胰岛素-RB复合物？
• RQ3 胰岛素-RB复合物的破坏是否特异性地由活性MCR肽引起，而非对照肽？
• RQ4 胰岛素-RB相互作用的破坏是否与肺癌细胞中的抗增殖效应相关？

主要发现

• 通过磁珠介导的免疫沉淀法，成功分离并确认了A549人肺癌细胞中的胰岛素-RB异源二聚体。
• MCR-10和MCR-4肽显著破坏了胰岛素-RB复合物，表明其直接干扰了该相互作用。
• 对照肽未破坏胰岛素-RB复合物，证明了MCR肽的特异性。
• 本研究为肺癌细胞中存在胰岛素-RB二聚体提供了直接证据，扩展了先前在肝癌细胞中的发现。
• 研究结果验证了胰岛素-RB相互作用作为MCR肽类抗癌药物在肺癌中的功能性靶点。