Antisense oligonucleotides of hepatoma-derived growth factor (HDGF) suppress the proliferation of hepatoma cells

BACKGROUND/AIMS: Human hepatoma-derived growth factor, purified from the conditioned medium of hepatoma-derived cell line, HuH-7, stimulates the growth of Swiss 3T3 fibroblasts and HuH-7 cells. To evaluate the role of hepatoma-derived growth factor on the growth of hepatoma cells, we investigated the effects of recombinant hepatoma-derived growth factor protein and hepatoma-derived growth factor antisense oligonucleotides on the proliferation of several hepatoma cell lines. METHODOLOGY: We examined the effects of hepatoma-derived growth factor antisense oligonucleotides on the growth of hepatoma cells by cell growth assay. RESULTS: Hepatoma-derived growth factor stimulated the proliferation of some hepatoma cells (HuH-7, HLF, HepG2, AH66tc cells) about 15-70% over than the control. Hepatoma-derived growth factor antisense oligonucleotides, phosphorothioate-linked or encapsulated in liposome, can inhibit the growth of hepatoma cells. The ID50 of hepatoma-derived growth factor antisense phosphorothioate oligonucleotides for HuH-7 cells, in which hepatoma-derived growth factor expression was abundant, was 3 microM by the assay of cell proliferation and [3H]-thymidine incorporation. Their ID50 for AH66tc cells, on which the effects of exogenous hepatoma-derived growth factor were weak, was higher than 10 microM. To omit the toxic effects due to phosphorothioate modification of oligonucleotides and keep the cellular uptake more without their destruction in the culture medium, we used oligonucleotides encapsulated in cationic liposome. Hepatoma-derived growth factor antisense oligonucleotides encapsulated in liposome suppressed the growth of hepatoma cells effectively (ID50:2.0 microM). CONCLUSIONS: These findings suggest that hepatoma-derived growth factor is one of important autocrine, and/or intracrine factors for hepatoma cells, and that hepatoma-derived growth factor anti-sense oligonucleotides may be useful for human hepatocellular carcinoma as an anti-cancer agent.