Hye Sook Hwang

( )-Epigallocatechin-3-gallate (EGCG) inhibits HGF-induced invasion and metastasis in hypopharyngeal carcinoma cells

Hepatocyte growth factor (HGF) has recently attracted a considerable amount of attention as a stromal-derived mediator in tumor-stromal interactions, particularly because of its close involvement in cancer invasion and metastasis, and (-)-epigallocatechin-3-gallate (EGCG) can modulate the cell signaling associated with angiogenesis, metastasis, and migration of cancer cells. In the present study, we have investigated the effects of HGF on invasion and metastasis of hypopharyngeal carcinoma cells and the effect of EGCG on blocking HGF-induced invasion and metastasis in these cells. We found that HGF promoted the autophosphorylation of c-Met, HGF receptor, and that HGF-induced proliferation, colony dispersion, migration and invasion of tumors. We also observed that HGF enhanced the activity of matrix metalloproteinase (MMP)-9 and urokinase-type plasminogen activator (uPA) in hypopharyngeal carcinoma cells. In addition, HGF-induced the activation of Akt and Erk pathway as a downstreaming pathway of invasion. On the other hand, EGCG at physiologically relevant concentration (1 microM) suppressed HGF-induced tumor motility and MMP-9 and uPA activities, and the suppression of Akt and Erk pathway by EGCG was one of the downstream mechanisms to facilitate EGCG-induced anti-invasion effects. These results suggest that EGCG may serve as a therapeutic agent to inhibit HGF-induced invasion in hypopharyngeal carcinoma patients.

Epicatechin protects auditory cells against cisplatin-induced death

Cisplatin, a chemotherapeutic drug that is widely used to treat various cancers, promotes ototoxicity at higher doses. In this study, the effect of epicatechin (EC) on cisplatin-induced hair cell death was investigated in a cochlear organ of Corti-derived cell line, HEI-OC1, and in vivo in zebrafish. Cisplatin promoted apoptosis and altered mitochondrial membrane potential (MMP) in HEI-OC1 cells. EC inhibited cisplatin-induced apoptosis and intracellular reactive oxygen species (ROS) generation. Labeling of zebrafish lateral line hair cells by the fluorescent dye YO-PRO1 was lost upon exposure to cisplatin, and EC protected against this cisplatin-induced loss of labeling in a dose-dependent manner. Scanning and transmission electron micrographs showed that treatment with EC protected against cisplatin-induced loss of kinocilium and stereocilia in zebrafish neuromasts. These results suggest that EC prevents cisplatin-induced ototoxicity by blocking ROS generation and by preventing changes in MMP.

Green tea (−)-epigallocatechin-3-gallate inhibits HGF-induced progression in oral cavity cancer through suppression of HGF/c-Met☆

Hepatocyte growth factor (HGF) and c-Met have recently attracted a great deal of attention as prognostic indicators of patient outcome, and they are important in the control of tumor growth and invasion. Epigallocatechin-3-gallate (EGCG) has been shown to modulate multiple signal pathways in a manner that controls the unwanted proliferation and invasion of cells, thereby imparting cancer chemopreventive and therapeutic effects. In this study, we investigated the effects of EGCG in inhibiting HGF-induced tumor growth and invasion of oral cancer in vitro and in vivo. We examined the effects of EGCG on HGF-induced cell proliferation, migration, invasion, induction of apoptosis and modulation of HGF/c-Met signaling pathway in the KB oral cancer cell line. We investigated the antitumor effect and inhibition of c-Met expression by EGCG in a syngeneic mouse model (C3H/HeJ mice, SCC VII/SF cell line). HGF promoted cell proliferation, migration, invasion and induction of MMP (matrix metalloproteinase)-2 and MMP-9 in KB cells. EGCG significantly inhibited HGF-induced phosphorylation of Met and cell growth, invasion and expression of MMP-2 and MMP-9. EGCG blocked HGF-induced phosphorylation of c-Met and that of the downstream kinases AKT and ERK, and inhibition of p-AKT and p-ERK by EGCG was associated with marked increases in the phosphorylation of p38, JNK, cleaved caspase-3 and poly-ADP-ribose polymerase. In C3H/HeJ syngeneic mice, as an in vivo model, tumor growth was suppressed and apoptosis was increased by EGCG. Our results suggest that EGCG may be a potential therapeutic agent to inhibit HGF-induced tumor growth and invasion in oral cancer.

c-Met expression as an indicator of survival outcome in patients with oral tongue carcinoma.

Hepatocyte growth factor (HGF) can promote proliferation, invasion, and angiogenesis in various tumor cells. However, the prognosis according to expression of HGF/c‐Met has not been reported in patients with squamous cell carcinoma of the oral tongue (SCCOT).

Tolfenamic acid induces apoptosis and growth inhibition in head and neck cancer: involvement of NAG-1 expression

Nonsteroidal anti-inflammatory drug-activated gene-1 (NAG-1) is induced by nonsteroidal anti-inflammatory drugs and possesses proapoptotic and antitumorigenic activities. Although tolfenamic acid (TA) induces apoptosis in head and neck cancer cells, the relationship between NAG-1 and TA has not been determined. This study investigated the induction of apoptosis in head and neck cancer cells treated by TA and the role of NAG-1 expression in this induction. TA reduced head and neck cancer cell viability in a dose-dependent manner and induced apoptosis. The induced apoptosis was coincident with the expression of NAG-1. Overexpression of NAG-1 enhanced the apoptotic effect of TA, whereas suppression of NAG-1 expression by small interfering RNA attenuated TA-induced apoptosis. TA significantly inhibited tumor formation as assessed by xenograft models, and this result accompanied the induction of apoptotic cells and NAG-1 expression in tumor tissue samples. Taken together, these results demonstrate that TA induces apoptosis via NAG-1 expression in head and neck squamous cell carcinoma, providing an additional mechanistic explanation for the apoptotic activity of TA.

Epicatechin inhibits radiation-induced auditory cell death by suppression of reactive oxygen species generation.

Radiation-induced toxicity limits the delivery of high-dose radiation to head and neck lesions. The aim of this study was to investigate the effectiveness of epicatechin (EC), a minor component of green tea extract, on radiation-induced ototoxicity in vitro and in vivo. The effect of EC on radiation-induced cytotoxicity was analyzed in the organ of Corti-derived cell lines, HEI-OC1 and UB-OC1. The cell viability, apoptosis, reactive oxygen species generation, and mitochondrial membrane potential as well as changes in the signal pathway related to apoptosis were investigated. Then, the therapeutic effects of hearing protection and drug toxicity of EC were explored in a zebrafish and rat model. Radiation-induced apoptosis and altered mitochondrial membrane potential in HEI-OC1 and UB-OC1 were observed. EC inhibited radiation-induced apoptosis and intracellular reactive oxygen species generation. EC markedly attenuated the radiation-induced embryotoxicity and protected against radiation-induced loss and changes of auditory neuromast in the zebrafish. In addition, intratympanic administration of EC was protective against radiation-induced hearing loss in the rat model, as determined by click-evoked auditory brainstem (P<0.01). EC significantly reduced the expression of p-JNK, p-ERK cleaved caspase-3, and cleaved PARP compared to their significant increase after radiation treatment. The results of this study suggest that EC significantly inhibited radiation-induced apoptosis in auditory hair cells and may be a safe and effective candidate treatment for the prevention of radiation-induced ototoxicity.

Epicatechin protects the auditory organ by attenuating cisplatin-induced ototoxicity through inhibition of ERK.

Cisplatin, a widely used chemotherapeutic drug, causes ototoxicity in a large percentage of patients. The purpose of this study was to determine the efficacy of epicatechin (EC) as an otoprotective agent to prevent cisplatin toxicity and to investigate the molecular mechanism of EC. The effects of EC on cisplatin-induced ototoxicity were investigated in a cochlear organ of Corti-derived cell line, HEI-OC1 and in a rat model. In addition, signaling mechanisms were investigated, specifically those involving MAP kinase. Cisplatin induced apoptosis and demonstrated, conjugation of annexin V/PI in FACS, and an increase of subG1 in HEI-OC1. EC protected HEI-OC1 against cisplatin and showed inhibition of cisplatin-induced apoptosis of the HEI-OC1 by transmission electron microscopy. Intratympanic administration of EC protected against cisplatin-induced ototoxicity in the rat model, as determined by auditory brainstem responses. EC inhibited activation of JNK, ERK, cytochrome-c and caspase-3 by cisplatin. An ERK Inhibitor, cisplatin-induced ototoxicity in a dose dependent manner but a JNK inhibitor did not. The results of this study suggest that EC may provide a mechanism by which ototoxicity caused by the administration of cisplatin can be reduced through the inhibition of ERK. EC may have clinical use as a chemopreventive agent that prevents cisplatin ototoxicity.

Imiquimod induces apoptosis of human melanocytes.

Development of vitiligo-like hypopigmentary lesions associated with topical imiquimod has been reported. We hypothesized that mode of action of imiquimod in melanocytes may include triggering of apoptosis resulted in loss of cells, which may be a possible mechanism of imiquimod-induced hypopigmentary lesions. Therefore, we investigated whether imiquimod induces apoptosis of human melanocytes and also whether it modulates expression of apoptosis-related molecules in human melanocytes. Imiquimod treatment induced apoptosis of melanocytes, which was observed by TUNEL assay and Hoechst 33258 staining. Imiquimod-induced apoptosis was further shown by measuring mitochondrial membrane potential in melanocytes. The apoptotic activity of imiquimod was associated with caspase-3, Bcl-2 and mitogen-activated protein kinase expression in melanocytes. These results indicated that imiquimod induces apoptosis of melanocytes. These findings may provide a clue to understand pathogenesis of imiquimod-induced vitiligo-like hypopigmentary lesions.

Protective effects of Korean red ginseng against radiation-induced apoptosis in human HaCaT keratinocytes

Radiation-induced oral mucositis is a dose-limiting toxic side effect for patients with head and neck cancer. Numerous attempts at improving radiation-induced oral mucositis have not produced a qualified treatment. Ginseng polysaccharide has multiple immunoprotective effects. Our aim was to investigate the effectiveness of Korean red ginseng (KRG) on radiation-induced damage in the human keratinocyte cell line HaCaT and in an in vivo zebrafish model. Radiation inhibited HaCaT cell proliferation and migration in a cell viability assay and wound healing assay, respectively. KRG protected against these effects. KRG attenuated the radiation-induced embryotoxicity in the zebrafish model. Irradiation of HaCaT cells caused apoptosis and changes in mitochondrial membrane potential (MMP). KRG inhibited the radiation-induced apoptosis and intracellular generation of reactive oxygen species (ROS), and stabilized the radiation-induced loss of MMP. Western blots revealed KRG-mediated reduced expression of ataxia telangiectasia mutated protein (ATM), p53, c-Jun N-terminal kinase (JNK), p38 and cleaved caspase-3, compared with their significant increase after radiation treatment. The collective results suggest that KRG protects HaCaT cells by blocking ROS generation, inhibiting changes in MMP, and inhibiting the caspase, ATM, p38 and JNK pathways.

A novel synthetic compound, 3-amino-3-(4-fluoro-phenyl)-1H-quinoline-2,4-dione, inhibits cisplatin-induced hearing loss by the suppression of reactive oxygen species: In vitro and in vivo study

Cisplatin, a chemotherapeutic agent for treating various solid tumors, produces hearing loss in approximately half a million cancer patients annually in the United States. In the course of developing a new protective agent against cisplatin-induced ototoxicity, we have been interested in a novel synthetic compound, 3-amino-3-(4-fluoro-phenyl)-1H-quinoline-2,4-dione (KR-22332). The effect of KR-22332 on cisplatin-induced cytotoxicity was analyzed in vitro in an organ of Corti-derived cell line (HEI-OC1), and in vivo in a zebrafish and rat model. Cisplatin-induced apoptosis, reactive oxygen species (ROS) generation and altered mitochondrial membrane potential (MMP) in HEI-OC1 cells were observed. KR-22332 significantly inhibited cisplatin-induced apoptosis, change of MMP, and intracellular ROS generation. KR-22332 markedly attenuated the cisplatin-induced loss and changes of auditory neuromasts in the zebrafish. Transtympanic administration of KR-22332 in a rat model was protective against cisplatin-induced hearing loss, as determined by click-evoked auditory brainstem response (p<0.01). Tissue terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling of rat cochlea demonstrated that KR-22332 blocked cisplatin-induced apoptosis. In addition, transtympanic administration of KR-22332 inhibited cisplatin-induced nicotinamide adenine dinucleotide phosphate-oxidase 3 (NOX3) overexpression in the rat cochlea. KR-22332 significantly reduced the expression of p-53, mitogen-activated protein kinases, caspase 3, and tumor necrosis factor-α compared to their significant increase after cisplatin treatment. The results of this study suggest that KR-22332 may prevent ototoxicity caused by the administration of cisplatin through the inhibition of mitochondrial dysfunction and the suppression of ROS generation. These novel findings implicate KR-22332 as a potential candidate for protective agent against cisplatin-induced ototoxicity.