Effects of pegylated interferon α2b on metastasis of hepatocellular carcinoma

Pegylated interferon-α inhibits the proliferation of hepatocellular carcinoma cells by downregulating miR-155

INTRODUCTION AND AIMS

Interferon-α (IFN) has shown potential benefits in patients with hepatocellular carcinoma (HCC), and these effects may be mediated by inhibiting cancer cell proliferation. However, the detailed mechanisms underlying the anti-proliferative effects of IFN remain obscure. In this study, we evaluate the role of the novel oncogenic microRNA (miRNA) miR-155 in the anti-proliferative effects of pegylated interferon-α (PEG-IFN) on HCC cells.

METHODS

The effects of PEG-IFN on HepG2 cell proliferation, migration and invasion were determined using the MTT assay, flow cytometry analysis and the Transwell assay, respectively. Reverse transcription quantitative polymerase chain reaction was used to analyze miR-155 expression. The levels of proteins involved in Wnt/β-catenin signal transduction were determined by western blot analysis and immunofluorescence staining. Mimics of miR-155 were transfected into HepG2 cells to assess the role of miR-155 in the PEG-IFN-induced anti-proliferative effect.

RESULTS

PEG-IFN significantly inhibited the proliferation, migration and invasion of HepG2 cells in a dose-dependent manner by inhibiting cell cycle progression. In parallel with reduced cell proliferation, migration and invasion, miR-155 was efficiently downregulated by PEG-IFN in a dose-dependent manner. Moreover, the transfection of miR-155 decreased the inhibitory effect of PEG-IFN on HepG2cell proliferation, migration and invasion, as well as the downregulation of proteins in the Wnt/β-catenin pathway.

CONCLUSIONS

The anti-proliferative effects of PEG-IFN on HCC are at least partially attributable to the downregulation of miR-155.

Fucoidan-induced ID-1 suppression inhibits the in vitro and in vivo invasion of hepatocellular carcinoma cells

Hepatocellular carcinoma (HCC) is a fast growing tumor associated with a high tendency for vascular invasion and distant metastasis. Recently, we reported that fucoidan displays inhibitory effect on proliferation and invasion of HCC cells. In this study, we investigated the anti-metastatic effect of fucoidan on HCC cells and the key signal that modulates metastasis. The anti-metastatic effect of fucoidan was evaluated in vitro using an invasion assay with human HCC cells (Huh-7, SNU-761, and SNU-3085) under both normoxic (20% O₂ and 5% CO₂, at 37°C) and hypoxic (1% O_2, 5% CO₂, and 94% N_2, at 37°C) conditions. Complementary DNA (cDNA) microarray analysis was performed to find the molecule which is significantly suppressed by fucoidan. In vivo study using a distant metastasis model by injecting SNU-761 cells into spleen via portal vein was performed to confirm the inhibitory effect by small interfering RNA (siRNA) transfection. Immunoblot analyses were used to investigate the signaling pathway. Fucoidan significantly suppressed the invasion of human HCC cells (Huh-7, SNU-761, and SNU-3085). Using cDNA microarray analysis, we found the molecule, ID-1, which was significantly suppressed by fucoidan treatment. Downregulation of ID-1 by siRNA significantly decreased invasion of HCC cells, both in vitro and in vivo (both P<0.05) in a NDRG-1/CAP43-dependent manner. In immunoblot assay, downregulation of ID-1 by siRNA decreased the expressions of epithelial-mesenchymal transition markers including CK19, vimentin, MMP2, and fibronectin. Immunofluorescence study also revealed that actin rearrangement was inhibited when ID-1 was down-regulated in HCC cells. Interestingly, in SNU-761 cells, the ID-1 expressions under hypoxic conditions were lower as compared to those under normoxic conditions. Under hypoxic conditions, HIF-1α up-regulated NDRG-1/CAP43, while HIF-2α down-regulated ID-1, which might be a compensatory phenomenon against hypoxia-induced HCC invasion. In conclusion, NDRG-1/CAP43-dependent down-regulation of ID-1 suppressed HCC invasion both in vitro and in vivo, which was modulated by fucoidan treatment. Moreover, the compensatory down-regulation of ID-1 against hypoxia-induced HCC invasion was observed. ID-1 is a novel therapeutic target for the treatment of metastatic HCC.

Fucoidan protects hepatocytes from apoptosis and inhibits invasion of hepatocellular carcinoma by up-regulating p42/44 MAPK-dependent NDRG-1/CAP43

Fucoidan is a traditional Chinese medicine suggested to possess anti-tumor effects. In this study the anti-metastatic effects of fucoidan were investigated in vitro in human hepatocellular carcinoma (HCC) cells (Huh-7 and SNU-761) under normoxic and hypoxic conditions and in vivo using a distant liver metastasis model involving injection of MH134 cells into spleen via the portal vein. Its ability to protect hepatocytes against bile acid (BA)-induced apoptosis was investigated in primary hepatocytes. Fucoidan was found to suppress the invasion of HCC cells through up-regulation of p42/44 MAPK-dependent NDRG-1/CAP43 and partly, under normoxic conditions, through up-regulation of p42/44 MAPK-dependent VMP-1 expression. It also significantly decreased liver metastasis in vivo. As regards its hepatoprotective effect, fucoidan decreased BA-induced hepatocyte apoptosis as shown by the attenuation of caspase-8, and -7 cleavages and suppression of the mobilization of caspase-8 and Fas associated death domain (FADD) into the death-inducing signaling complex. In summary, fucoidan displays inhibitory effects on proliferation of HCC cells and protective effects on hepatocytes. The results suggest fucoidan is a potent suppressor of tumor invasion with hepatoprotective effects.