Antitumor activities of dFv-LDP-AE: An enediyne-energized fusion protein targeting tumor-associated antigen gelatinases.

Gelatinases play an important role in tumor growth and metastasis, and overexpression of these molecules is strongly correlated with poor prognosis in a variety of malignant tumors. Lidamycin is an enediyne antitumor antibiotic with potent cytotoxicity. We previously reported that a tandem scFv format (dFv-LDP-AE) showed enhanced binding ability with gelatinases compared with the scFv-lidamycin conjugate (Fv-LDP-AE). In this study, the antitumor activities of dFv-LDP-AE on hepatocellular carcinoma (HCC) were evaluated in vitro and in vivo. By SDS-PAGE analysis, it was found that partial fusion protein dFv-LDP existed as dimer; the results of ELISA and immunofluorescence demonstrated that the fusion protein dFv-LDP could efficiently bind to hepatoma cells in vitro. The apparent arrest of cell cycle at G2/M phase and induction of apoptosis at nanomole levels indicated that the dFv-LDP-AE was very potent against HCC. In in vivo experiments, dFv-LDP-AE shown enhanced cytotoxic effects compared to those of LDM. Administration at mouse tolerable dosage level, the inhibition rate of tumor growth was 89.5% of dFv-LDP-AE vs. 73.6% of LDM on transplantable H22 in mice (P<0.05) and, 87.3% of dFv-LDP-AE vs. 63.4% of LDM on hepatoma Bel-7402 in athymic mice (P<0.01). Small animal optical imaging showed that the FITC-labeled dFv-LDP preferentially localized in the tumor site in less than 30 min, which demonstrated remarkable tumor-targeting properties. Taken together with the above findings, the enediyne-energized fusion protein dFv-LDP-AE showed potential application as a new agent for therapeutic appications in HCC.