Jeong-Hyun Yoon

Baicalein, an active component of Scutellaria baicalensis Georgi, induces apoptosis in human colon cancer cells and prevents AOM/DSS-induced colon cancer in mice.

Flavonoids have been demonstrated to provide health benefits in humans. Baicalein (5,6,7-trihydroxyflavone) is a phenolic flavonoid compound derived mainly from the root of Scutellaria baicalensis Georgi, a medicinal plant traditionally used in oriental medicine. Baicalein is widely used in Korean and Chinese herbal medicines as anti-inflammatory and anticancer therapy. However, the molecular mechanisms of its activity remain poorly understood and warrant further investigation. This study was performed to investigate the anticancer effect of baicalein on HCT116 human colon cancer cells and the tumor preventing capacity of baicalein on colitis-associated cancer in mice. In in vivo experiments, we induced colon tumors in mice by azoxymethane (AOM) and dextran sulfate sodium (DSS) and evaluated the effects of baicalein on tumor growth. Baicalein treatment on HCT116 cells resulted in a concentration-dependent inhibition of cell growth and induction of apoptotic cell death. The induction of apoptosis was determined by morphological changes and cleavage of poly(ADP-ribose) polymerase. Baicalein also suppressed the activation of NF-κB through PPARγ activation. These results indicate that the anti-inflammatory effects of baicalein may be mediated through PPARγ activation. Finally, administration with baicalein significantly decreased the incidence of tumor formation with inflammation. Our findings suggest that baicalein is one of the candidates for the prevention of inflammation-associated colon carcinogenesis.

Comparisons of polybrominated diphenyl ethers levels in paired South Korean cord blood, maternal blood, and breast milk samples

Polybrominated diphenyl ethers (PBDEs), commonly used flame retardants, have been reported as potential endocrine disruptor and neurodevelopmental toxicants, thus giving rise to the public health concern. The goal of this study was to investigate the relationship between umbilical cord blood, maternal blood, and breast milk concentrations of PBDEs in South Korean. We assessed PBDE levels in paired samples of umbilical cord blood, maternal blood, and breast milk. The levels of seven PBDE congeners were measured in 21 paired samples collected from the Cheil Womans Hospital (Seoul, Korea) in 2008. We also measured thyroid hormones levels in maternal and cord blood to assess the association between PBDEs exposure and thyroid hormone levels. However, there was no correlation between serum thyroxin (T4) and total PBDEs concentrations. The total PBDEs concentrations in the umbilical cord blood, maternal blood, and breast milk were 10.7±5.1 ng g(-1) lipid, 7.7±4.2 ng g(-1) lipid, and 3.0±1.8 ng g(-1) lipid, respectively. The ranges of total PBDE concentrations observed were 2.28-30.94 ng g(-1) lipid in umbilical cord blood, 1.8-17.66 ng g(-1) lipid in maternal blood, and 1.08-8.66 ng g(-1) lipid in breast milk. BDE-47 (45-73% of total PBDEs) was observed to be present dominantly in all samples, followed by BDE-153. A strong correlation was found for major BDE-congeners between breast milk and cord blood or maternal blood and cord blood samples. The measurement of PBDEs concentrations in maternal blood or breast milk may help to determine the concentration of PBDEs in infant.

Colon-targeted cell-permeable NFκB inhibitory peptide is orally active against experimental colitis.

For the purpose of development of orally active peptide therapeutics targeting NFκB for treatment of inflammatory bowel disease (IBD), two major barriers in oral delivery of therapeutic peptides, metabolic lability and tissue impermeability, were circumvented by introduction of a colon-targeted delivery system and cell permeable peptides (CPP) to NFκB inhibitory peptides (NIP). Suppression of NFκB activation was compared following treatment with various CPP conjugated NIPs (CPP-NIP). The most potent CPP-NIP was loaded in a capsule coated with a colon specific polymer, which was administered orally to colitic rats. The anti-inflammatory activity of the colon-targeted CPP-NIP was evaluated by measuring inflammatory indices in the inflamed colonic tissue. For confirmation of the local action of the CPP-NIP, the same experiment was done after rectal administration. Tissue permeability of the CPP-NIP was examined microscopically and spectrophotometrically using FITC-labeled CPP-NIP (CPP-NIP-FITC). NEMO binding domain peptide (NBD, TALDWSWLQTE) fused with a cell permeable peptide CTP (YGRRARRRARR), CTP-NBD, was most potent in inhibiting NFκB activity in cells. Colon-targeted CTP-NBD, but not colon-targeted NBD and CTP-NBD in an enteric capsule, ameliorated the colonic injury, which was in parallel with decrease in MPO activity and the levels of inflammatory mediators. Intracolonic treatment with CTP-NBD alleviated rat colitis and improved all the inflammatory indicators. CTP-NBD-FITC was detected at much greater level in the inflamed tissue than was NBD-FITC. Taken together, introduction of cell permeability and colon targetability to NIP may be a feasible strategy for an orally active peptide therapy for treatment of IBD.

Sulforaphane inhibits hypoxia-induced HIF-1α and VEGF expression and migration of human colon cancer cells

The effects of sulforaphane (a natural product commonly found in broccoli) was investigated on hypoxia inducible factor-1α (HIF-1α) expression in HCT116 human colon cancer cells and AGS human gastric cancer cells. We found that hypoxia-induced HIF-1α protein expression in HCT116 and AGS cells, while treatment with sulforaphane markedly and concentration-dependently inhibited HIF-1α expression in both cell lines. Treatment with sulforaphane inhibited hypoxia-induced vascular endothelial growth factor (VEGF) expression in HCT116 cells. Treatment with sulforaphane modulated the effect of hypoxia on HIF-1α stability. However, degradation of HIF-1α by sulforaphane was not mediated through the 26S proteasome pathway. We also found that the inhibition of HIF-1α by sulforaphane was not mediated through AKT and extracellular signal-regulated kinase phosphorylation under hypoxic conditions. Finally, hypoxia-induced HCT116 cell migration was inhibited by sulforaphane. These data suggest that sulforaphane may inhibit human colon cancer progression and cancer cell angiogenesis by inhibiting HIF-1α and VEGF expression. Taken together, these results indicate that sulforaphane is a new and potent chemopreventive drug candidate for treating patients with human colon cancer.

HS-1793, a resveratrol analogue, induces cell cycle arrest and apoptotic cell death in human breast cancer cells

Resveratrol, a polyphenolic compound, is a naturally occurring phytochemical and is found in a variety of plants, including food such as grapes, berries and peanuts. It has gained much attention for its potential anticancer activity against various types of human cancer. However, the usefulness of resveratrol as a chemotherapeutic agent is limited by its photosensitivity and metabolic instability. In this study the effects of a synthetic analogue of resveratrol, HS-1793, on the proliferation and apoptotic cell death were investigated using MCF-7 (wild-type p53) and MDA-MB-231 (mutant p53) human breast cancer cells. HS-1793 inhibited cell growth and induced apoptotic cell death in a concentration-dependent manner. The induction of apoptosis was determined by morphological changes, cleavage of poly(ADP-ribose) poly-merase, alteration of Bax/Bcl-2 expression ratio and caspase activities. Flow cytometric analysis revealed that HS-1793 induced G2/M arrest in the cell cycle progression in both types of cells. Of note, HS-1793 induced p53/p21WAF1/CIP1-dependent apoptosis in MCF-7 cells, whereas it exhibited p53-independent apoptosis in MDA-MB-231 cells. Furthermore, HS-1793 showed more potent anticancer effects in several aspects compared to resveratrol in MCF-7 and MDA-MB-231 cells. Thus, these findings suggest that HS-1793 has potential as a candidate chemotherapeutic agent against human breast cancer.

Combined interaction of multi-locus genetic polymorphisms in cytarabine arabinoside metabolic pathway on clinical outcomes in adult acute myeloid leukaemia (AML) patients

Cytarabine arabinoside (ara-C) is the key agent for treating acute myeloid leukaemia (AML). Here, we genotyped 139 single nucleotide polymorphisms (SNPs) within the ara-C transport and metabolic pathway using the Illumina Golden Gate Assay in 97 patients with previously non-treated de novo AML other than M3. DCK rs4694362 (CC genotype) was a significant poor prognostic factor for overall survival (OS) (hazard ratio [HR], 33.202 [95% confidence interval (CI), 4.937-223.273], P<0.0001, P(Bonferroni)=0.017). SLC29A1 rs3734703 (AA or AC genotype) in combination with TYMS rs2612100 (AA genotype) was significantly associated with shorter relapse free survival (RFS) (HR, 17.630 [95% CI, 4.829-64.369], P<0.0001, P(Bonferroni)=0.021). These SNPs showed moderate or large inter ethnic divergence in allele frequencies from African or Caucasian populations. The results of our study suggest that a single SNP and SNP-SNP interactions may help to predict the drug response and provide a guide in developing individualised chemotherapy for AML patients receiving ara-C based chemotherapy.

A pharma-robust design method to investigate the effect of PEG and PEO on matrix tablets

Even though polyethyleneoxide (PEO)-polyethyleneglycol (PEG) blends have been used widely for sustained release matrix tablets, evaluations of the effects of PEG or PEO on the matrix properties have been limited. In order to evaluate gelling behavior and drug release profiles of PEG, various contents of the polymers were investigated through a robust experimental design method. When exposed to an aqueous environment, the PEO-PEG matrix hydrated slowly and swelled, causing a thick gel layer to form on the surface, the thickness of which increased significantly depending on the PEG contents. Since polyacrylate plates were used for the study, the matrix was not completely hydrated and gelled even after 5h. However, the results could be applied to the time-oriented responses RD (robust design) models to obtain optimal settings and responses for the observed times. The optimal settings of PEO and PEG were 94.26 and 140.04 mg, respectively (PEG rate of 148.57%). Moreover, as the amount of PEG increased, the release rate also increased. When the formulation contained more than 150% of PEG, most of the drug loaded in the tablet was released in about 12 h. When the amount of PEG was less than 100%, the drug release rate was sustained significantly. Based on the RD optimization model for drug release, the optimal settings were PEG and PEO of 124.3 and 110 mg, respectively (PEG rate of 88.50%). Therefore, PEG rate of about 90-150% is suggested for matrix tablet formulations, and the exact ratio could be formulated according to the resulting tablets properties.

A novel resveratrol analogue, HS-1793, inhibits hypoxia-induced HIF-1α and VEGF expression, and migration in human prostate cancer cells

In many studies, resveratrol has been shown to have a chemopreventive effect in various types of cancer cells. However, the biological activity of resveratrol is limited by its photosensitivity and metabolic instability. This study investigated the effects of a novel analogue of resveratrol, HS-1793, on the expression of HIF-1α and vascular endothelial growth factor (VEGF) in PC-3 human prostate cancer cells. Hypoxic condition induced HIF-1α protein level in PC-3 cells in a time-dependent manner, and treatment with HS-1793 markedly decreased HIF-1α expression levels. HS-1793 also inhibited VEGF level. Mechanistically, HS-1793 inhibited HIF-1α and VEGF expression through multiple mechanisms. Firstly, HS-1793 inhibited phosphorylation of PI3K and Akt in PC-3 cells. Furthermore, HS-1793 substantially induced HIF-1α protein degradation through the proteasome pathway. Finally, HS-1793 inhibited hypoxia-induced PC-3 cell migration. These data suggest that HS-1793 may inhibit human prostate cancer progression and angiogenesis by inhibiting the expression of HIF-1α and VEGF. Moreover, HS-1793 showed more potent effects than resveratrol on the cytotoxic effects on PC-3 cells. Taken together, these results implied that HS-1793, a novel analogue of resveratrol, may be a new potent chemopreventive agent against human prostate cancer cells.

Evaluation of dextran-flufenamic acid ester as a polymeric colon-specific prodrug of flufenamic acid, an anti-inflammatory drug, for chronotherapy

Dextran-flufenamic acid ester (Dex-FFA) with varied degree of substitution (DS) was prepared by imidazolide method. Dex-FFA was stable in pH 1.2 or pH 6.8 buffer. The depolymerization degree of Dex-FFA by dextranase decreased as DS increased. Dex-FFA with DS of 13 or 20 released FFA up to 70% or 21% of the dose, respectively, on 24 h-incubation with the 10% cecal contents. FFA was liberated up to 29% of the dose on 24 h-incubation of dextranase pre-treated Dex-FFA with the homogenates of the upper intestine, whereas no FFA was detected devoid of dextranse-pretreatment. Upon oral administration of Dex-FFA (DS 13, 20 mg equivalent of FFA/kg) or FFA (10 mg/kg) to rats, tmax for FFA with Dex-FFA administration delayed approximately 6 h compared with that of free FFA administration, while Cmax for FFA was similar. The plasma level for FFA became greater around 6 h after administration of Dex-FFA than free FFA and it was maintained throughout the period of 24 h-experiment. Dex-FFA markedly attenuated gastric ulcerogenicity of FFA. Taken together, Dex-FFA could be useful as a colon-specific prodrug which possesses anti-inflammatory properties and offers opportunities as a chronotherapeutic approach for the treatment of arthritis.

Corosolic acid induces apoptotic cell death in HCT116 human colon cancer cells through a caspase-dependent pathway

Corosolic acid (CA), a pentacyclic triterpene isolated from Lagerstroemia speciosa L. (also known as Banaba), has been shown to exhibit anticancer properties in various cancer cell lines. However, the anticancer activity of CA on human colorectal cancer cells and the underlying mechanisms remain to be elucidated. In this study, we investigated the effects of CA on cell viability and apoptosis in HCT116 human colon cancer cells. CA dose-dependently inhibited the viability of HCT116 cells. The typical hallmarks of apoptosis, such as chromatin condensation, a sub-G1 peak and phosphatidylserine externalization were detected by Hoechst 33342 staining, flow cytometry and Annexin V staining following treatment with CA. Western blot analysis revealed that CA induced a decrease in the levels of procaspase-8, -9 and -3 and the cleavage of poly(ADP-ribose) polymerase (PARP). The apoptotic cell death induced by CA was accompanied by the activation of caspase-8, -9 and -3, which was completely abrogated by the pan-caspase inhibitor, z-VAD‑FMK. Furthermore, CA upregulated the levels of pro-apoptotic proteins, such as Bax, Fas and FasL and downregulated the levels of anti-apoptotic proteins, such as Bcl-2 and survivin. Taken together, our data provide insight into the molecular mechanisms of CA-induced apoptosis in colorectal cancer (CRC), rendering this compound a potential anticancer agent for the treatment of CRC.