Jihyeung Ju

Inhibition of IGF-1 Signaling by Genistein: Modulation of E-Cadherin Expression and Downregulation of β-Catenin Signaling in Hormone Refractory PC-3 Prostate Cancer Cells

Elevated levels of insulin-like growth factor-1 (IGF-1) are associated with an increased risk of several different cancers, including prostate cancer. Inhibition of IGF-1 and the downstream signaling pathways mediated by the activation of the IGF-1 receptor (IGF-1R) may be involved in inhibiting prostate carcinogenesis. We investigated whether genistein downregulated the IGF-1/IGF-1R signaling pathway and inhibited cell growth in hormone refractory PC-3 prostate cancer cells. Genistein treatment caused a significant inhibition of IGF-1-stimulated cell growth. Flow cytometry analysis revealed that genistein significantly decreased the number of IGF-1-stimulated cells in the G0/G1 phase of the cell cycle. In IGF-1-treated cells, genistein effectively inhibited the phosphorylation of IGF-1R and the phosphorylation of its downstream targets, such as Src, Akt, and glycogen synthase kinase-3β (GSk-3β). IGF-1 treatment decreased the levels of E-cadherin but increased the levels of β-catenin and cyclin D1. However, genistein treatment greatly attenuated IGF-1-induced β-catenin signaling that correlated with increasing the levels of E-cadherin and decreasing cyclin D1 levels in PC-3 cells. In addition, genistein inhibited T-cell factor/lymphoid enhancer factor (TCF/LEF)-dependent transcriptional activity. These results showed that genistein effectively inhibited cell growth in IGF-1-stimulated PC-3 cells, possibly by inhibiting downstream of IGF-1R activation.

Cancer prevention by tocopherols and tea polyphenols.

Tocopherols (vitamin E) and tea polyphenols have been reported to have cancer preventive activities. Large-scale human trials with high doses of alpha-tocopherol, however, have produced disappointing results. This review presents data showing that - and -tocopherols inhibit colon, lung, mammary and prostate carcinogenesis in animal models, whereas -tocopherol is ineffective in animal and human studies. Possible mechanisms of action are discussed. A broad cancer preventive activity of green tea polyphenols has been demonstrated in animal models, and many mechanisms have been proposed. The cancer preventive activity of green tea in humans, however, has not been conclusively demonstrated and remains to be further investigated.

Deleterious Effects of High Concentrations of (-)-Epigallocatechin-3-Gallate and Atorvastatin in Mice With Colon Inflammation

Epigallocatechin-3-gallate (EGCG), atorvastatin (ATST), and their combination have been previously shown to inhibit colon carcinogenesis in animal models. We further investigated their inhibitory activities in azoxymethane (AOM) and dextran sulfate sodium (DSS)-treated Balb/cJ mice and CD-1 mice in 2 slightly different models. The mice were maintained on the AIN93M diet, or a similar diet containing 0.03%, 0.1%, or 0.3% EGCG; 60-ppm ATST; or a combination of 0.1% EGCG and 60-ppm ATST. Unexpectedly, no significant inhibitory activity was observed, and some of the treatment groups resulted in higher tumor multiplicity. To study the effects of EGCG on colon inflammation, CD-1 or C57BL/6 mice were treated with 1.5% DSS for 7 days and sacrificed 3 days later. DSS induced rectal bleeding and colon shortening; treatment with 0.5% EGCG exacerbated the bleeding and decreased mouse body weight. Dietary 0.5% EGCG also increased serum levels of leukotriene B4 and prostaglandin E2. These results suggest that, in mice bearing colon inflammation, high concentrations of EGCG and ATST enhance colon bleeding and may promote colon carcinogenesis.

Inhibitory activities of Perilla frutescens britton leaf extract against the growth, migration, and adhesion of human cancer cells

BACKGROUND/OBJECTIVES Perilla frutescens Britton leaves are a commonly consumed vegetable in different Asian countries including Korea. Cancer is a major cause of human death worldwide. The aim of the current study was to investigate the inhibitory effects of ethanol extract of perilla leaf (PLE) against important characteristics of cancer cells, including unrestricted growth, resisted apoptosis, and activated metastasis, using human cancer cells. MATERIALS/METHODS Two human cancer cell lines were used in this study, HCT116 colorectal carcinoma cells and H1299 non-small cell lung carcinoma cells. Assays using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide were performed for measurement of cell growth. Soft agar and wound healing assays were performed to determine colony formation and cell migration, respectively. Nuclear staining and cell cycle analysis were performed for assessment of apoptosis. Fibronectin-coated plates were used to determine cell adhesion. RESULTS Treatment of HCT116 and H1299 cells with PLE resulted in dose-dependent inhibition of growth by 52-92% (at the concentrations of 87.5, 175, and 350 µg/ml) and completely abolished the colony formation in soft agar (at the concentration of 350 µg/ml). Treatment with PLE at the 350 µg/ml concentration resulted in change of the nucleus morphology and significantly increased sub-G1 cell population in both cells, indicating its apoptosis-inducing activity. PLE at the concentration range of 87.5 to 350 µg/ml was also effective in inhibiting the migration of H1299 cells (by 52-58%) and adhesion of both HCT116 and H1299 cells (by 25-46%). CONCLUSIONS These results indicate that PLE exerts anti-cancer activities against colon and lung cancers in vitro. Further studies are needed in order to determine whether similar effects are reproduced in vivo.

Inhibitory effects of calcium against intestinal cancer in human colon cancer cells and ApcMin/+ mice

The aim of the study was to investigate the inhibitory effects of calcium against intestinal cancer in vitro and in vivo. We first investigated the effects of calcium treatment in HCT116 and HT29 human colon cancer cells. At the concentration range of 0.8-2.4 mM, calcium significantly inhibited cell growth (by 9-29%), attachment (by 12-26%), invasion (by 15-31%), and migration (by 19-61%). An immunofluorescence microscope analysis showed that the treatment with calcium (1.6 mM) for 24 h increased plasma membrane β-catenin but decreased nuclear β-catenin levels in HT29 cells. We then investigated the effect of dietary calcium on intestinal tumorigenesis in ApcMin/+ mice. Mice received dietary treatment starting at 6 weeks of age for the consecutive 8 weeks. The basal control diet contained high-fat (20% mixed lipids by weight) and low-calcium (1.4 mg/g diet) to mimic the average Western diet, while the treatment diet contained an enriched level of calcium (5.2 mg calcium/g diet). The dietary calcium treatment decreased the total number of small intestinal tumors (by 31.4%; P < 0.05). The largest decrease was in tumors which were ≥ 2 mm in diameter, showing a 75.6% inhibition in the small intestinal tumor multiplicity (P < 0.001). Immunohistochemical analysis showed significantly reduced nuclear staining of β-catenin (expressed as nuclear positivity), but increased plasma membrane staining of β-catenin, in the adenomas from the calcium-treated groups in comparison to those from the control group (P < 0.001). These results demonstrate intestinal cancer inhibitory effects of calcium both in human colon cancer cells and ApcMin/+ mice. The decreased β-catenin nuclear localization caused by the calcium treatment may contribute to the inhibitory action.

Antioxidant and Anti-cancer Activities of Squash (Cucurbita moschata Duch.) Leaf Extract In vitro

The aim of this study was to investigate the antioxidant and anti-cancer activities of squash leaf extract (SLE) in vitro. The total polyphenol and flavonoid levels of SLE were 263.4 mg gallic acid equivalent/100 g and 73.6 mg quercetin equivalent/100 g, respectively. The radical-scavenging activity of SLE at the concentration of 300 μg/mL was 69.4%. SLE significantly inhibited human cancer cell growth (by 60.6-87.9% in HCT116 colon cancer cells and by 73.4-86.4% in H1299 lung cancer cells at the concentrations of 37.5, 75, and 150 μg/mL) and attachment (by 28.4% in HCT116 and by 16.8% in H1299 at the concentration of 150 μg/mL). SLE also altered nucleus morphology and increased nuclear staining intensity (by 42.8-58.2% in HCT116 and by 25.5-32.9% in H1299 at the concentrations of 37.5 and 75 μg/mL), indicating its apoptosis-inducing activity. These results demonstrate the antioxidant and anti-cancer activities of SLE in vitro.

Anti-inflammatory Activity of Perilla frutescens Britton Seed in RAW 264.7 Macrophages and an Ulcerative Colitis Mouse Model

This study aimed to investigate the anti-inflammatory activities of raw (P) and roasted (RP) Perilla frutescens Britton (perilla) seeds in RAW 264.7 macrophages and an ulcerative colitis mouse model. In lipopolysaccharide-treated RAW 264.7 cells, treatment with ethanol extract of P at the concentrations of 75 and 150 μg/mL decreased nitric oxide (NO), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) levels to 48-85% of the control (p<0.01). Treatment with RP extract exhibited similar effects on NO, IL-6, and TNF-α, decreasing those levels to 51-84% of the control (p<0.01). In dextran sulfate sodium-treated ulcerative colitis mice, dietary treatment with 1% RP for 7 days decreased the colonic levels of prostaglandin E₂ and leukotriene B₄ to 34% and 58% of the control, respectively (p<0.05). Dietary P treatment, however, did not decrease those levels significantly. These results indicate that roasted perilla seed exerts anti-inflammatory activity both in vitro and in vivo.

Glycine max Merr. leaf extract possesses anti-oxidant properties, decreases inflammatory mediator production in murine macrophages, and inhibits growth, migration, and adhesion in human cancer cells

The present study aimed to investigate the in vitro anti-oxidant, anti-inflammatory, and anticancer properties of the ethanol extract of soybean (Glycine max Merr.) leaves (SLE). The total polyphenol and flavonoid levels were 142.0±14.0mg gallic acid equivalent/g and 104.9±2.0 mg quercetin equivalent/g, respectively. The radical scavenging activity and ferric-reducing anti-oxidant power of SLE at the concentrations of 125–500 μg/mL were 5–61%. In lipopolysaccharide-treated RAW 264.7 macrophages, treatment with SLE at concentrations of 62.5–500 μg/mL dose-dependently decreased the production of nitric oxide and prostaglandin E2. In both HCT116 human colon cancer cells and H1299 human lung cancer cells, treatment with SLE inhibited the growth and anchorage-independent colony formation. SLE was also effective in inhibiting the migration of H1299 cells and the adhesion of both HCT116 and H1299 cells. These results suggest that SLE exerts anti-oxidant, antiinflammatory, and anti-cancer activities in vitro. It needs to be determined whether similar effects are reproduced in vivo.