Arginine-rich
peptides belong to a subclass of
cell penetrating peptides that are taken up by living cells and can be detected freely diffusing inside the cytoplasm and nucleoplasm. This phenomenon has been attributed to either an endocytotic mode of uptake and a subsequent release from vesicles or a direct membrane penetration.
Lidamycin is an antitumor
antibiotic, which consists of an active enediyne chromophore (AE) and a noncovalently bound
apoprotein (LDP). In the present study, a fusion
protein (Arg)(9)-LDP composed of
cell penetrating peptide (Arg)(9) and LDP was prepared by
DNA recombination, and the enediyne-energized fusion
protein (Arg)(9)-LDP-AE was prepared by molecular reconstitution. The data in fixed cells demonstrated that (Arg)(9)-LDP could rapidly enter cells, and the results based on fluorescence activated cell sorting indicated that the major route for (Arg)(9)-mediated cellular uptake of
protein molecules was endocytosis. (Arg)(9)-LDP-AE demonstrated more potent cytotoxicity against different
carcinoma cell lines than
lidamycin in vitro. In the mouse
hepatoma 22 model, (Arg)(9)-LDP-AE (0.3mg/kg) suppressed the
tumor growth by 89.2%, whereas
lidamycin (0.05 mg/kg) by 74.6%. Furthermore, in the
glioma U87 xenograft model in nude mice, (Arg)(9)-LDP-AE at 0.2mg/kg suppressed
tumor growth by 88.8%, compared with that of
lidamycin by 62.9% at 0.05 mg/kg. No obvious toxic effects were observed in all groups during treatments. The results showed that energized fusion
protein (Arg)(9)-LDP-AE was more effective than
lidamycin and would be a promising candidate for
glioma therapy. In addition, this approach to manufacturing fusion
proteins might serve as a technology platform for the development of new
cell penetrating peptides-based drugs.