OBJECTIVETo investigate the inhibitory effects of humanized monoclonal antibody-3 (huTNT-3) mediated truncated tissue factor (tTF) on the H(22) hepatoma-bearing mice, and to explore its mechanisms.

METHODSThe coagulation activity of the huTNT-3/tTF fusion protein was detected by clotting assay and clotting factor X (FX) activation test in vitro. Mouse hepatoma cell line H(22) cells were inoculated subcutaneously into mice to establish the mouse models of hepatoma. The mice were randomly divided into two groups to be injected once with huTNT-3/tTF fusion protein or tTF protein labeled with rhodamine B isothiocyanate (RBITC), respectively. The localization of huTNT-3/tTF fusion protein in the mouse hepatoma tissue was analyzed by confocal laser scanning microscopy 24 hour after the injection. Fifteen mice were randomly divided into three groups to be injected with the huTNT-3/tTF fusion protein, tTF protein or phosphate buffered saline (PBS) once, respectively. The tumor size was measured every two days to calculate the tumor volume. Ten days after the injection the mice were sacrificed. Samples of the tumor, heart, livers, spleen, lung, kidney and brains of the mice were taken for histopathological examination.

RESULTSBoth the huTNT-3/tTF fusion protein and tTF protein effectively promoted blood coagulation. Under the conditions of Ca(2+), the coagulation time in the 1.5, 3, 6 µmol/L huTNT-3/tTF groups was (12.90 ± 0.60) min, (10.39 ± 0.40) min and(8.15 ± 0.24) min, respectively, and the coagulation time of the 1.5, 3, 6 µmol/L tTF groups was (14.23 ± 0.46) min, (12.10 ± 0.49) min and (9.83 ± 0.52) min, respectively, the difference between the two groups was not significant (F = 0.145, P = 0.705). The huTNT-3/tTF fusion protein was similar to the tTF protein in the ability of activating FX (t = 0.101, P > 0.05). The confocal laser scanning microscopic analysis showed that RBITC-fluorescence labeled huTNT-3/tTF fusion protein was enriched in the hepatoma tissue. The tumor volume of the huTNT-3/tTF fusion protein group was significantly lower than that of the tTF and PBS groups (both P < 0.001), however, there was not significant difference between the tTF and PBS groups (t = -0.616, P > 0.05). The survival time of the huTNT-3/tTF group was (25.5 ± 2.5) d, significantly longer than that of the PBS group (17.3 ± 1.9) d and the tTF group (18.6 ± 1.9) d, (both P < 0.05).

CONCLUSIONThe huTNT-3/tTF fusion protein retains the coagulation ability and has the capability of targeting to tumor vasculature, and induces thrombosis in the tumor vessels, thus to suppress the growth of hepatoma in the mice.