Eun-Sun Hwang

Inhibitory Effects of Lycopene on the Adhesion, Invasion, and Migration of SK-Hep1 Human Hepatoma Cells:

Lycopene, which is the predominant carotenoid in tomatoes and tomato-based foods, may protect humans against various cancers. Effects of lycopene on the adhesion, invasion, migration, and growth of the SK-Hep1 human hepatoma cell line were investigated. Lycopene inhibited cell growth in dose-dependent manners, with growth inhibition rates of 5% and 40% at 0.1 μM and 50 μM lycopene, respectively, after 24 hrs of incubation. Similarly, after 48 hrs of incubation, lycopene at 5 μM and 10 μM decreased the cell numbers by 30% and 40%, respectively. Lycopene decreased the gelatinolytic activities of both matrix metalloproteinase (MMP)-2 and MMP-9, which were secreted from the SK-Hep1 cells. Incubation of SK-Hep1 cells with 110 μM of lycopene for 60 mins significantly inhibited cell adhesion to the Matrigel-coated substrate in a concentration-dependent manner. To study invasion, SK-Hep1 cells were grown either on Matrigel-coated Transwell membranes or in 24-well plates. The cells were treated sequentially for 24 hrs with lycopene before the start of the invasion assays. Cell growth and death were assessed under the same conditions. The invasion of SK-Hep1 cells treated with lycopene was significantly reduced to 28.3% and 61.9% of the control levels at 5 μM and 10 μM lycopene, respectively (P < 0.05). In the migration assay, lycopene-treated cells showed lower levels of migration than untreated cells. These results demonstrate the antimetastatic properties of lycopene in inhibiting the adhesion, invasion, and migration of SK-Hep1 human hepatoma cells.

Allyl Isothiocyanate and Its N-Acetylcysteine Conjugate Suppress Metastasis via Inhibition of Invasion, Migration, and Matrix Metalloproteinase-2/-9 Activities in SK-Hep1 Human Hepatoma Cells

Cruciferous vegetables contain a series of relatively unique secondary metabolites of amino acids, called glucosinolates. Sinigrin, the predominant aliphatic glucosinolate in cruciferous vegetables, is hydrolyzed to yield allyl isothiocyanate (AITC), which, after absorption and metabolism in humans, is excreted in the urine as an N-acetyicysteine (NAC) conjugate. We have determined the inhibitory effects of AITC and its NAC conjugate on cell proliferation, the expression of matrix metalloproteinases (MMPs), adhesion, invasion, and migration in SK-Hep1 human hepatoma cells. Our results demonstrate that AITC and NAC-AITC suppress SK-Hep1 cell proliferation in a dose-dependent manner; by 25% and 30% for 10 μM AITC and 10 μM NAC-AITC, respectively. We examined the influence of AITC and NAC-AITC on the gene expression of MMPs and tissue inhibitors of metalloproteinase (TIMPs). Gelatin zymography also revealed a significant downregulation of MMP-2/-9 expression in SK-Hep1 cells treated with 0.1–5 μM AITC and NAC-AITC compared with controls. Reverse transcriptase polymerase chain reaction revealed dose-dependent decreases in MMP-2/-9 messenger RNA levels in both AITC-treated and NAC-AITC–treated cells. TIMP-1/-2 activities were unaffected by treatment with AITC or NAC-AITC in our experiments. NAC-AITC inhibited cancer cell adhesion and invasion much more potently than its parent compound. NAC-AITC at 5 μM caused excellent inhibition of cell migration for 48 hrs. These results demonstrate the potential of AITC and NAC-AITC as chemopreventive agents.

Benzyl isothiocyanate inhibits metalloproteinase-2/-9 expression by suppressing the mitogen-activated protein kinase in SK-Hep1 human hepatoma cells

Benzyl isothiocyanate (BITC) is a hydrolysis compound of glucotropaeolin in cruciferous vegetables. Many studies have reported that BITC prevents cancers in laboratory animals and might also be chemoprotective in humans. The purpose of this study was to investigate the effects of BITC on cell proliferation, metastasis, and MAPK pathways of SK-Hep1 human hepatocellular carcinoma cells. BITC suppressed SK-Hep1 cell proliferation in a dose-dependent manner, and exposure to 1 and 5 microM BITC reduced cell proliferation by 25% and 30%, respectively. The expression of matrix metalloproteinase (MMP)-2, MMP-9, and membrane type-1/MMP (MT-1/MMP) is a known risk factor for metastatic disease. Gelatin zymography analysis revealed a significant downregulation of MMP-2/-9 protein expression in SK-Hep1 cells treated with 0.1-5 microM BITC. BITC treatment caused dose-dependent decreases in MMP-2/-9 and MT1-MMP mRNA levels as determined by RT-PCR. BITC also increased the mRNA levels of tissue inhibitors of matrix metalloproteinases-2 (TIMP-2) 1.3- and 1.5-fold after a 24 h exposure to 1 and 5 microM BITC, respectively. Increased TIMP-2 expression is mediated by the downregulation of MMP-2 and MT1-MMP. BITC inhibited the phosphorylation activities of all three major mitogen-activated protein kinases (MAPKs) in a dose-dependent manner. BITC at 5 microM reduced the ERK1/2 phosphorylation activity by 50% and p38 activity by 70%. BITC also reduced the p-JNK1/2 level by 30% and 70% at 1 and 5 microM treatments, respectively. These data may represent anti-metastatic activities of BITC through the suppression of MAPKs in SK-Hep1 cells.

Allyl Isothiocyanate Influences Cell Adhesion, Migration and Metalloproteinase Gene Expression in SK-Hep1 Cells

Allyl isothiocyanate (AITC) has been reported to exhibit antimetastatic activity, but the mechanism remains unclear. The objective of this study was to determine the effect of AITC on cell adhesion, migration, and metalloproteinase gene expression in SK-Hep1 human hepatoma cells. The gene expression profiles of SK-Hep1 cells were obtained by using the HG-U133A Affymetrix GeneChip human genome array containing 14,500 human genes. Twenty antimetastatic genes including COL4A3, ADAMDEC1, CAPN10, CD14, and ITGB1BP3 were over expressed, while the expression of 35 genes such as COL8A1, MYBPC1, ST14, and SOS2 were down-regulated. Semiquantitative RT-PCR confirmed these results in mRNA levels. Based on these in vitro results, it can be concluded that AITC might be potentially useful in suppressing tumor cell migration and MMP expression.