[Inhibition of tumor metastasis by synthetic peptide analogues of cell-adhesive RGD sequence of fibronectin].

Since the adhesive interaction between tumor cells and host cells, or extracellular matrix (ECM), presumably plays a crucial role in metastatic formation, we used synthetic or recombinant polypeptide analogues, poly (RGD), CH-271 or SCM-chitin-RGDS based on Arg-Gly-Asp (RGD) sequence. Poly (RGD) effectively inhibited the experimental lung and liver metastasis when coinjected i.v. with different types of tumors. In a spontaneous lung metastasis model using B16-BL6 melanoma, multiple administrations of this polypeptide, before or after surgical excision of the primary tumor, resulted in significant inhibition of tumor metastasis. The mechanism responsible for the inhibition is partly associated with the ability to interfere with cell functions such as adhesiveness, motility, and invasiveness in the process of metastasis. CH-271 fusion polypeptide was much more effective in inhibiting lung or liver metastasis of tumors than cell-binding domain (C-274) or heparin-binding domain (H-271) polypeptides. SCM-chitin-RGDS conjugate significantly reduced the number of tumor colonies in the lungs by coinjection with Colon 26 carcinoma as compared with either RGDS or SCM-chitin alone. Since the polypeptides derived from cell adhesion molecules showed no toxicity to the host, they may provide a promising approach for the control of cancer metastasis.