Humphries M J, Yamada K M, Olden K
Department of Oncology, Howard University Cancer Center, Washington, D.C. 20060.
J Clin Invest. 1988 Mar;81(3):782-90. doi: 10.1172/JCI113384.
The experimental metastasis of B16-F10 murine melanoma cells is blocked by the anti-cell adhesive pentapeptide Gly-Arg-Gly-Asp-Ser (GRGDS) derived from the central cell-binding domain of fibronectin. In this report, we show that peptide treatment substantially extends the survival time for mice injected intravenously with B16-F10 cells (8/8 vs. 0/8 mice alive at 150 d), thereby demonstrating the potential efficacy of GRGDS treatment in protection against metastatic colonization. We have also examined the specificity of GRGDS activity by testing a series of related homologues for their effects on experimental metastasis. The overall profile of the relative inhibitory activities of these peptides closely matched their previously established capacity to disrupt adhesion in vitro. Lung retention studies with radiolabeled B16-F10 cells revealed an accelerated rate of cell loss from the lung 0-6 h after coinjection with the active peptide GRGDS. This early effect of GRGDS was consistent with its short circulatory half-life, which was found to be 8 min. Taken together, these results suggest that peptide-mediated inhibition of pulmonary colonization is due to interference with B16-F10 cell adhesion to structures in the target organ. Possible peptide interference in tumor cell-blood cell interactions was examined in order to assess (a) possible biological side-effects of peptide treatment and (b) whether such interactions might be an alternative mechanism for GRGDS-mediated inhibition of pulmonary colonization. GRGDS was found to retain full inhibitory activity when coinjected with B16-F10 cells into mice in which platelet function was impaired by acetylsalicylic acid treatment or into thrombocytopenic mice treated with antiplatelet serum (76-93% inhibition of colony formation). These data suggest that platelet involvement in the effects of the peptide is minimal. Similarly, GRGDS was also found to be a potent inhibitor of experimental metastasis in natural killer (NK) cell-deficient beige mice (86% inhibition), thereby discounting the possibility that GRGDS artifactually enhanced NK cell activity. We conclude as a result of these studies that cell-binding fibronectin peptides are specific inhibitors of experimental metastasis that prolong survival, that they appear to function by blocking the adhesion of B16-F10 cells to structures in the target organ, and that they do not appear to act through side effects on certain metastasis-related blood cell functions. In the future, derivatives of fibronectin peptides may be potentially useful prophylactic agents for interfering with the process of metastasis.
源自纤连蛋白中央细胞结合结构域的抗细胞黏附五肽甘氨酸 - 精氨酸 - 甘氨酸 - 天冬氨酸 - 丝氨酸（GRGDS）可阻断B16 - F10小鼠黑色素瘤细胞的实验性转移。在本报告中，我们表明肽处理显著延长了静脉注射B16 - F10细胞的小鼠的存活时间（150天时存活小鼠为8/8 vs. 0/8），从而证明了GRGDS处理在预防转移性定植方面的潜在疗效。我们还通过测试一系列相关同系物对实验性转移的影响来研究GRGDS活性的特异性。这些肽的相对抑制活性的总体概况与其先前确定的体外破坏黏附的能力密切匹配。用放射性标记的B16 - F10细胞进行的肺滞留研究表明，与活性肽GRGDS共同注射后0 - 6小时，肺中细胞损失速率加快。GRGDS的这种早期作用与其短循环半衰期一致，其循环半衰期为8分钟。综上所述，这些结果表明肽介导的对肺定植的抑制是由于干扰了B16 - F10细胞与靶器官结构的黏附。为了评估（a）肽处理可能的生物学副作用以及（b）这种相互作用是否可能是GRGDS介导的肺定植抑制的另一种机制，研究了肽对肿瘤细胞 - 血细胞相互作用的可能干扰。当与B16 - F10细胞共同注射到用乙酰水杨酸处理使血小板功能受损的小鼠或用抗血小板血清处理的血小板减少小鼠中时，发现GRGDS保留了完全的抑制活性（集落形成抑制率为76 - 93%）。这些数据表明血小板对肽作用的参与最小。同样，还发现GRGDS是自然杀伤（NK）细胞缺陷的米色小鼠中实验性转移的有效抑制剂（抑制率为86%），从而排除了GRGDS人为增强NK细胞活性的可能性。我们通过这些研究得出结论，细胞结合性纤连蛋白肽是实验性转移的特异性抑制剂，可延长存活时间，它们似乎通过阻断B16 - F10细胞与靶器官结构的黏附发挥作用，并且它们似乎不是通过对某些与转移相关的血细胞功能产生副作用来起作用。未来，纤连蛋白肽的衍生物可能是干扰转移过程的潜在有用的预防剂。
