Design and Verification Process of a Structure-Altering Peptide as a Microtubule Allosteric Polypeptide Against Cancer.

The aim of this study was to design a novel structure-altering polypeptide (SAP) as an anti-microtubule against tumor cells. This series of SAP XA1-XA17 was synthesized by manual solid-phase synthesis and verified by high-performance liquid chromatography (HPLC) and mass spectrometry. Polypeptides were used in three normal cell lines and four tumor cell lines. The optimal polypeptide was selected. Molecular docking of the above optimal polypeptide with tubulin was performed. Tubulin polymerization experiment was performed to investigate effect of optimized peptide to tubulin polymerization. The effect of optimized peptide to cancer in vivo was tested in A549 xenograft tumor mice model. The results of mass spectrometry revealed that the molecular weights of the SAP XA1-XA17 samples were relatively consistent with the theoretical values, whereas the purities of the SAP XA1-XA17 series polypeptide samples were greater than 92.00%. Among the SAP XA1-17 polypeptides, the cell viability kit-8 (CCK-8) assay demonstrated that the XA5 polypeptide was nearly nontoxic to three normal cell lines and had excellent antitumor effects on four cancer cell lines. Molecular docking demonstrated that the polypeptide XA5 preferred tubulin. The docking energies are less than - 5 kcal/mol, verifying the excellent performance of the selected XA5 polypeptide. Tubulin polymerization experiment showed XA5 inhibited tubulin polymerization. In animal study, XA5 administration decreased A549 xenograft tumor weight. The XA5 polypeptide is an effective anti-microtubule drug.