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Featured researches published by Yung Hyun Choi.


Biomedicine & Pharmacotherapy | 2008

Sulforaphane generates reactive oxygen species leading to mitochondrial perturbation for apoptosis in human leukemia U937 cells.

Woo Young Choi; Byung Tae Choi; Won Ho Lee; Yung Hyun Choi

Sulforaphane, an isothiocyanate found in cruciferous vegetables, has been shown to possess growth-inhibiting and apoptosis-inducing activities in cancer cell lines in vitro. In order to further explore the critical events leading to apoptosis in sulforaphane-treated U937 human leukemia cells, the following effects of sulforaphane on components of the mitochondrial apoptotic pathway were examined: generation of reactive oxygen species (ROS), alteration of the mitochondrial membrane potential (MMP), and the expression changes of Bcl-2 family proteins. The cytotoxic effect of sulforaphane was mediated by its induction of apoptosis as characterized by the occurrence of DNA ladders, apoptotic bodies and chromosome condensation in U937 cells. The sulforaphane-induced apoptosis in U937 cells correlated with the generation of intracellular ROS, collapse of MMP, activation of caspase-3, and down-regulation of anti-apoptotic Bcl-2 expression. The quenching of ROS generation with antioxidant N-acetyl-L-cysteine conferred significant protection against sulforaphane-elicited ROS generation, disruption of the MMP, caspase-3 activation and apoptosis. In conclusion, the present study reveals that the cellular ROS generation plays a pivotal role in the initiation of sulforaphane-triggered apoptotic death in U937 cells.


Biomedicine & Pharmacotherapy | 2008

Involvement of extracellular signal-related kinase signaling in esculetin induced G1 arrest of human leukemia U937 cells.

Shin Hwa Lee; Cheol Park; Cheng-Yun Jin; Gi-Young Kim; Sung-Kwon Moon; Jin Won Hyun; Won Ho Lee; Byung Tae Choi; Taeg Kyu Kwon; Young Hyun Yoo; Yung Hyun Choi

This study was conducted to further elucidate the possible mechanisms by which esculetin, a coumarin compound, exerts its anti-proliferative action on cultured human monocytic leukemia U937 cells. The inhibitory effects of esculetin on cell viability were found to be associated with a G1 arrest in cell cycle progression that was concomitant with an inhibition of cyclin E and an induction of cyclin-dependent kinase (Cdk) inhibitor p21/WAF1/CIP1 in a p53-independent manner. Cells that were treated with esculetin showed increased binding of p21 with Cdk2 and Cdk4 that was paralleled by a marked decrease in the Cdk2 and Cdk4 kinase activities with no change in their expression. We also observed that down-regulation of the phosphorylation of retinoblastoma protein (pRB) by this compound was associated with enhanced binding of pRB and the transcription factor E2F-1. Further investigation showed that inhibition of the extracellular-regulated kinase (ERK) signaling pathway reduced the induction of p21 and the inhibition of pRB phosphorylation and cyclin E expression by esculetin, which in turn overcame the G1 arrest and growth inhibition that was induced by esculetin. These data demonstrate that the ERK pathway participates in p21 induction and subsequently leads to a decrease in the kinase activity of Cdks and inhibition of pRB phosphorylation in esculetin-mediated G1 arrest of U937 cells.


Current Eye Research | 2001

Synthetic bile acid derivatives induce nonapoptotic death of human retinal pigment epithelial cells

Hee Seong Yoon; Jee Hyun Rho; Kyung Won Yoo; Woo Chan Park; Sae Heun Rho; Yung Hyun Choi; Hongsuk Suh; Nam Deuk Kim; Ki Soo Yoo; Young Hyun Yoo

Purpose. To study whether the synthetic ursodeoxycholic acid (UDCA) and chenodeoxycholic acid (CDCA) derivatives, which we have synthesized and have reported their apoptosis-inducing effect, have the effect on the proliferation of retinal pigment epithelial cells. Methods. UDCA, CDCA, and their synthetic derivatives were administered in culture to the human retinal pigment cell line, ARPE-19. The effect on cell viability and growth was assessed by trypan blue dye exclusion. In order to evaluate the type of cell death, mitochondrial membrane potential assay, DNA electrophoresis, TUNEL assay, nuclear staining and Western blotting for caspase-3 and poly(ADP-ribose) polymerase (PARP) activities were conducted. Results. Unlike UDCA and CDCA, which did not exhibit a significant effect on viability, their synthetic derivatives decreased the viability of ARPE-19 cells in a concentration-dependent manner. The cells treated with the synthetic derivatives did not demonstrate the characteristic findings of apoptosis, such as DNA ladder, DNA fragmentation, nuclear condensation or fragmentation, and caspase-3 and PARP activation. The reduction of mitochondrial membrane potential was shown. In electron microscopical study nuclear condensation was not shown. Conclusions. The synthetic UDCA and CDCA derivatives induced nonapoptotic death of ARPE-19 cells.


Toxicology and Applied Pharmacology | 2008

Induction of apoptosis by esculetin in human leukemia U937 cells through activation of JNK and ERK

Cheol Park; Cheng-Yun Jin; Gi-Young Kim; Il-Whan Choi; Taeg Kyu Kwon; Byung Tae Choi; Su Jae Lee; Won Ho Lee; Yung Hyun Choi


Clinical Cancer Research | 2007

b-Sitosterol induces G 2 /M arrest, endoreduplication, and apoptosis through the Bcl-2 and PI3K/Akt signaling pathways

Dong-Oh Moon; Mun-Ock Kim; Yung Hyun Choi; Gi-Young Kim


Clinical Cancer Research | 2007

Bcl-2 attenuates esculetin-induced apoptosis in human leukemic U937 cells through inactivation of ERK pathway

Cheol Park; Cheng-Yun Jin; Woo Young Choi; Gi-Young Kim; Yung Hyun Choi; Won Ho Lee


Clinical Cancer Research | 2007

Platycodin d induces g2/m cell-cycle arrest, leading to endoreduplication, inhibition of proliferation and apoptosis in leukemia cells

Mun-Ok Kim; Dong-Oh Moon; Sang-Hyuck Kang; Yung Hyun Choi; Jae-Dong Lee; Nam Deuk Kim; Gi-Young Kim


Clinical Cancer Research | 2007

Sulforaphane potentiates the sensitivity of apoptosis through suppression of tnf-α-induced nf-κb activation

Sang-Hyuck Kang; Dong-Oh Moon; Mun-Ock Kim; Yung Hyun Choi; Gi-Young Kim


Clinical Cancer Research | 2007

Induction of apoptosis by extracelluar organic metabolite isolated from actinomycete Streptomyces sp. BIT-64 in human leukemia cells

Yung Hyun Choi; Min Ho Han; Cheng-Yun Park; Gi-Young Kim; Byung Tae Choi; Won Ho Lee; Seong-Yun Jeong


Clinical Cancer Research | 2007

Induction of apoptosis through down-regulation of AKT and activation of caspase-3 in human breast cancer MDA-MB-231 cells by aqueous extract of Codyceps militaris

jinwoo jeung; Cheng-Yun Jin; Mun-Ok Kim; Gi-Young Kim; Won Ho Lee; Yung Hyun Choi; Jae-Dong Lee

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Gi-Young Kim

Jeju National University

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Won Ho Lee

Pusan National University

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Byung Tae Choi

Pusan National University

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Cheng-Yun Jin

Pusan National University

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Cheol Park

Pusan National University

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Dong-Oh Moon

Pusan National University

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Nam Deuk Kim

Pusan National University

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Jae-Dong Lee

Pusan National University

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Mun-Ock Kim

Pusan National University

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Mun-Ok Kim

Pusan National University

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