Hepatoma-derived growth factor (HDGF) is a unique nuclear targeting growth factor which plays an important role in both carcinogenesis and cancer progression. Exogenously supplied and endogenously over-expressed HDGF stimulates the proliferation of hepatocellular carcinoma (HCC) cells. In the present study, to clarify the effects of HDGF on HCC, HDGF over-expressing cells were cloned and their biological functions for the growth of HCC were investigated. An anchorage-independent colony formation assay, xenograft tumor formation experiment and a DNA chip analysis were all performed. In a human HCC cell line, HepG2 cells over-expressing HDGF (HepG2-HDGF) proliferate more rapidly than mock HepG2 (HepG2-neo) cells in vitro. According to an anchorage independent colony assay, HepG2-HDGF cells formed more and bigger colonies than HepG2-neo in soft agar. HepG2-HDGF cells generate tumors earlier and promote tumor growth more rapidly than HepG2-neo cells in nude mice. The tumors which develop from HepG2-HDGF cells show a more reddish color macroscopically and a richer in vasculature microscopically than the tumors from HepG2-neo cells. According to the DNA-chip analyses, both in vitro and in vivo up-regulated genes due to HDGF over-expression are demonstrated, including PDGF-A, matrix metalloproteinase-1, urokinase-type plasminogen activator, chitinase 3-like-2 and ankyrin, which are related to tumor growth and aggressive characteristics. These findings suggest that HDGF enhance tumor growth while also inducing the aggressive biological functions, through the expression of genes which are related to invasion, metastasis and angiogenesis in vivo. Therefore, HDGF is considered to play an important role in the progression of HCC as well as hepatocarcinogenesis.
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