OBJECTIVETo synthesize a tumor-targeting cell-penetrating peptide (CPP) and evaluate its biological activity and cytotoxicity in vitro.

METHODSWith fluorenylmethyloxycarbonyl (Fmoc) as the protective group of α-amino acid, the tumor-targeting CPP were synthesized with stepwise amino acid extension using solid-phase synthesis method. 5-carboxytetramethylrhodamine was added for fluorescence labeling in the presence of the coupling agents HATU and DMF. The purity of the CPP was measured by high-performance liquid chromatography and its molecular weight measured by mass spectrometry. Fluorescence microscope was used to assess the cell-penetrating activity?of the CPP in hepatocellular carcinoma cell lines SMMC-7721 and normal hepatocellular cell lines LO2. The growth activity of CPP-treated SMMC-7721 cells was measured by MTT assay.

RESULTSWith a purity of 96.05% and a relative molecular mass of 3504.9, the synthesized CPP showed no translocation activity in normal hepatocellular cell lines LO2, but showed strong ability to translocate into SMMC-7721 cells without affecting the biological activity of the cells.

CONCLUSIONUsing Fmoc solid-phase synthesis method, we have successfully synthesized the CPP with tumor-targeting activity.