Siu-Kai Kong

Publications of Siu-Kai Kong

• Salidroside Protects Human Erythrocytes against Hydrogen Peroxide-Induced Apoptosis.

  Authors: Erin Wei Qian, Daniel Tianfang Ge, Siu-Kai Kong

  Journal of natural products. 04/2012;

  Rhodiola rosea is a commonly used folk medicine for the treatment of high altitude sickness, mountain malhypoxia, and anoxia. Its active ingredient, salidroside [2-(4-hydroxyphenyl)ethylRhodiola rosea is a commonly used folk medicine for the treatment of high altitude sickness, mountain malhypoxia, and anoxia. Its active ingredient, salidroside [2-(4-hydroxyphenyl)ethyl β-d-glucopyranoside (1)], has been reported to have a broad spectrum of biological effects. However, the protective role of 1 in human erythrocytes remains unclear. This study therefore has investigated the effects of 1 on oxidative stress-induced apoptosis in human erythrocytes (also known as eryptosis or erythroptosis). Compound 1 increased cell survival significantly and prevented human erythrocytes from undergoing eryptosis/erythroptosis mediated by H(2)O(2), as confirmed by the decreased expression of phosphatidylserine on the cell surface and reduced leakage of calcein through the damaged membrane. Mechanistically, 1 was found to exert its protective effects through its antioxidative activity and the inhibition of caspase-3 activation and stress-induced intracellular Ca(2+) rise in a dose-dependent manner. Compound 1 is a protective agent in human erythrocytes against oxidative stress and may be a good adaptogen to enhance the body's resistance to stress and fatigue.

• Bone morphogenic protein-4 induces endothelial cell apoptosis through oxidative stress-dependent p38MAPK and JNK pathway.

  Authors: Xiao Yu Tian, Lai Hang Yung, Wing Tak Wong, Jian Liu, Fung Ping Leung, Limei Liu, Yangchao Chen, Siu Kai Kong, Kin Ming Kwan, Siu Man Ng, Paul B S Lai, Lai Ming Yung, Xiaoqiang Yao, Yu Huang

  Journal of molecular and cellular cardiology. 10/2011; 52(1):237-44.

  The expression of bone morphogenic protein 4 (BMP4), a new pro-inflammatory marker, is increased by disturbed flow in endothelial cells (ECs). BMP4 stimulates production of reactive oxygen speciesThe expression of bone morphogenic protein 4 (BMP4), a new pro-inflammatory marker, is increased by disturbed flow in endothelial cells (ECs). BMP4 stimulates production of reactive oxygen species (ROS) and causes endothelial cell dysfunction. The present study examined BMP4-induced apoptosis in ECs and isolated arteries from rat, mouse, and human, and the signaling pathways mediating BMP4-induced apoptosis. Apoptosis was assessed by flow cytometry to detect Annexin-V positive cells, and terminal deoxynucleotidyl transferase dUTP nick end (TUNEL) labeling. The superoxide production was measured by dihydroethidium fluorescence. BMP4 induced EC apoptosis in human mesenteric arteries, mouse aortic endothelium, rat primary ECs, and human ECs. BMP4-induced EC apoptosis was mediated through ROS production by activation of NADPH oxidase, which led to cleaved caspase-3 expression. BMP4 also induced sequential activation of p38 MAPK and JNK which was upstream of caspase 3 activation. Knockdown of BMP receptor 1A by lentiviral shRNA or NOX4 siRNA transfection inhibited BMP4-induced ROS production, p38 and JNK phosphorylation, and caspase-3 activation in ECs. JNK siRNA inhibited BMP4-induced JNK phosphorylation and caspase-3 activation. The present study delineates that BMP4 causes EC apoptosis through activation of caspase-3 in a ROS/p38MAPK/JNK-dependent signaling cascade.

• Tendon-derived stem cells (TDSCs) promote tendon repair in a rat patellar tendon window defect model.

  Authors: Ming Ni, Pauline Po Yee Lui, Yun Feng Rui, Yuk Wa Lee, Yuk Wai Lee, Qi Tan, Yin Mei Wong, Siu Kai Kong, Pui Man Lau, Gang Li, Kai Ming Chan

  Journal of orthopaedic research : official publication of the Orthopaedic Research Society. 09/2011; 30(4):613-9.

  Injured tendons heal slowly and often result in the formation of mechanically and functionally inferior fibrotic scar tissue or fibrous adhesions. This study investigated the use of tendon-derivedInjured tendons heal slowly and often result in the formation of mechanically and functionally inferior fibrotic scar tissue or fibrous adhesions. This study investigated the use of tendon-derived stem cells (TDSCs) for tendon repair in a rat patellar tendon window defect model. Fibrin glue constructs with or without GFP-TDSCs were transplanted into the window defect. The patellar tendons were harvested for histology, ex vivo fluorescent imaging and biomechanical test at various time points up to week 4. Our results showed that TDSCs significantly enhanced tendon healing as indicated by the increase in collagen production as shown by hematolxylin stain-ability of the tissue, improvement of cell alignment, collagen fiber alignment and collagen birefringence typical of tendon. The labeled cells were observed at weeks 1 and 2 and became almost undetectable at week 4. Both the ultimate stress and Young's modulus were significantly higher in the TDSCs group compared to those in the fibrin glue group at week 4. In conclusion, TDSCs promoted earlier and better repair in a rat patellar tendon window defect model. © 2011 Orthopaedic Research Society. © 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 30:613-619, 2012.

• Polyphyllin D, a steroidal saponin from Paris polyphylla, inhibits endothelial cell functions in vitro and angiogenesis in zebrafish embryos in vivo.

  Authors: Judy Yuet-Wa Chan, Johnny Chi-Man Koon, Xiaozhou Liu, Michael Detmar, Biao Yu, Siu-Kai Kong, Kwok-Pui Fung

  Journal of ethnopharmacology. 05/2011; 137(1):64-9.

  Angiogenesis, the process of blood vessel formation, is critical to tumour growth. The importance of angiogenesis in tumour development has lead to the development of anti-angiogenic strategies toAngiogenesis, the process of blood vessel formation, is critical to tumour growth. The importance of angiogenesis in tumour development has lead to the development of anti-angiogenic strategies to inhibit tumour growth. In this study, polyphyllin D (PD), an active component in Chinese herb, Paris polyphylla, was evaluated for its potential anti-angiogenic effects. The inhibitory effects of PD on three important processes involved in angiogenesis, i.e. proliferation, migration and differentiation were examined using human microvascular endothelial cell line HMEC-1 by MTT assay, scratch assay and tube formation assay, respectively. Using zebrafish embryos as an animal model of angiogenesis, the anti-angiogenic effect of PD was further verified in vivo. PD suppressed the growth of HMEC-1 cells at 0.1-0.4 μM without toxic effects. At 0.3 μM and 0.4 μM, PD significantly inhibited endothelial cell migration and capillary tube formation. About 70% of the zebrafish embryos showed defects in intersegmental vessel formation upon treatment with PD at concentrations of 0.156 μM and 0.313 μM. The anti-angiogenic effects of PD have been explored in the study which implied a potential therapeutic development of PD in cancer treatment.

• Hierarchical core/shell Fe3O4@SiO2@γ-AlOOH@Au micro/nanoflowers for protein immobilization.

  Authors: Shouhu Xuan, Feng Wang, Xinglong Gong, Siu-Kai Kong, Jimmy C Yu, Ken Cham-Fai Leung

  Chemical communications (Cambridge, England). 03/2011; 47(9):2514-6.

  A facile synthesis of monodispersed microparticles composed of superparamagnetic Fe(3)O(4) cores, SiO(2) shell, hierarchical γ-AlOOH periphery with Au nanoparticles is reported. These particles areA facile synthesis of monodispersed microparticles composed of superparamagnetic Fe(3)O(4) cores, SiO(2) shell, hierarchical γ-AlOOH periphery with Au nanoparticles is reported. These particles are found to be useful for protein immobilization and bear resemblance to daisy flowers, and are hereafter termed "nanoflowers".

• P-glycoprotein enhances radiation-induced apoptotic cell death through the regulation of miR-16 and Bcl-2 expressions in hepatocellular carcinoma cells.

  Authors: Tsun Yee Tsang, Wan Yee Tang, Judy Yuet Wa Chan, Ngai Na Co, Chi Lam Au Yeung, Pak Lun Yau, Siu Kai Kong, Kwok Pui Fung, Tim Tak Kwok

  Apoptosis : an international journal on programmed cell death. 02/2011; 16(5):524-35.

  P-glycoprotein (Pgp), an efflux pump, was confirmed the first time to regulate the expressions of miR/gene in cells. Pgp is known to be associated with multidrug resistance. RHepG2 cells, theP-glycoprotein (Pgp), an efflux pump, was confirmed the first time to regulate the expressions of miR/gene in cells. Pgp is known to be associated with multidrug resistance. RHepG2 cells, the multidrug resistant subline of human hepatocellular carcinoma HepG2 cells, expressed higher levels of Pgp as well as miR-16, and lower level of Bcl-2 than the parental cells. In addition, RHepG2 cells were more radiation sensitive and showed more pronounced radiation-induced apoptotic cell death than the parental cells. Mechanistic analysis revealed that transfection with mdr1 specific antisense oligos suppressed radiation-induced apoptosis in HepG2 cells. On the other hand, ectopic mdr1 expression enhanced radiation-induced apoptosis in HepG2 cells, SK-HEP-1 cells, MiHa cells, and furthermore, induced miR-16 and suppressed its target gene Bcl-2 in HepG2 cells. Moreover, the enhancement effects of Pgp and miR-16 on radiation-induced apoptosis were counteracted by overexpression of Bcl-2. The Pgp effect on miR-16/Bcl-2 was suppressed by Pgp blocker verapamil indicating the importance of the efflux of Pgp substrates. The present study is the first to reveal the role of Pgp in regulation of miRNA/gene expressions. The findings may provide new perspective in understanding the biological function of Pgp.

• Mitochondrial monoamine oxidase-A-mediated hydrogen peroxide generation enhances 5-hydroxytryptamine-induced contraction of rat basilar artery.

  Authors: Christina Chui Wa Poon, Sai Wang Seto, Alice Lai Shan Au, Qian Zhang, Rachel Wai Sum Li, Wayne Yuk Wai Lee, George Pak Heng Leung, Siu Kai Kong, John Hok Keung Yeung, Sai Ming Ngai, Ho Pui Ho, Simon Ming Yuen Lee, Shun Wan Chan, Yiu Wa Kwan

  British journal of pharmacology. 11/2010; 161(5):1086-98.

  We evaluated the role(s) of monoamine oxidase (MAO)-mediated H₂O₂ generation on 5-hydroxytryptamine (5-HT)-induced tension development of isolated basilar artery of spontaneously hypertensive ratsWe evaluated the role(s) of monoamine oxidase (MAO)-mediated H₂O₂ generation on 5-hydroxytryptamine (5-HT)-induced tension development of isolated basilar artery of spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats. Basilar artery (endothelium-denuded) was isolated for tension measurement and Western blots. Enzymically dissociated single myocytes from basilar arteries were used for patch-clamp electrophysiological and confocal microscopic studies. Under resting tension, 5-HT elicited a concentration-dependent tension development with a greater sensitivity (with unchanged maximum tension development) in SHR compared with WKY (EC(50) : 28.4 ± 4.1 nM vs. 98.2 ± 9.4 nM). The exaggerated component of 5-HT-induced tension development in SHR was eradicated by polyethylene glycol-catalase, clorgyline and citalopram whereas exogenously applied H₂O₂ enhanced the 5-HT-elicited tension development in WKY. A greater protein expression of MAO-A was detected in basilar arteries from SHR than in those from WKY. In single myocytes and the entire basilar artery, 5-HT generated (clorgyline-sensitive) a greater amount of H₂O₂ in SHR compared with WKY. Whole-cell iberiotoxin-sensitive Ca(2+) -activated K(+) (BK(Ca) ) amplitude measured in myocytes of SHR was approximately threefold greater than that in WKY (at +60 mV: 7.61 ± 0.89 pA·pF(-1) vs. 2.61 ± 0.66 pA·pF(-1) ). In SHR myocytes, 5-HT caused a greater inhibition (clorgyline-, polyethylene glycol-catalase- and reduced glutathione-sensitive) of BK(Ca) amplitude than in those from WKY. 5-HT caused an increased generation of mitochondrial H₂O₂ via MAO-A-mediated 5-HT metabolism, which caused a greater inhibition of BK(Ca) gating in basilar artery myocytes, leading to exaggerated basilar artery tension development in SHR.

• Salidroside promotes erythropoiesis and protects erythroblasts against oxidative stress by up-regulating glutathione peroxidase and thioredoxin.

  Authors: Erin Wei Qian, Daniel Tianfang Ge, Siu-Kai Kong

  Journal of ethnopharmacology. 10/2010; 133(2):308-14.

  Rhodiola rosea is commonly used in China and Tibet folk medicine for the treatment of high altitude sickness, anoxia and mountain malhypoxia. Salidroside (SDS) is an active ingredient of RhodiolaRhodiola rosea is commonly used in China and Tibet folk medicine for the treatment of high altitude sickness, anoxia and mountain malhypoxia. Salidroside (SDS) is an active ingredient of Rhodiola rosea. This study attempted to examine the potential erythropoiesis-stimulating and anti-oxidative effect of SDS in TF-1 erythroblasts. The erythropoiesis-promoting effect was determined by treating human TF-1 cells, one of the popular in vitro models for studying erythropoiesis, with SDS in the presence and absence of erythropoietin (EPO) through the measurement of the expression of a series of erythroid markers such as glycophorin A (GPA), transferrin receptor (CD71) and hemoglobin (Hb). The potential protective effect of SDS against H(2)O(2)-induced apoptosis and its underlying mechanism in TF-1 erythroblasts were examined by flow cytometry and Western blot analysis. SDS promotes erythropoiesis in the EPO-treated cells and it also reduces the number of apoptotic cells in TF-1 erythroblasts after H(2)O(2) treatment probably through the up-regulation of protective proteins thioredoxin-1 (Trx1) and glutathione peroxidase-1 (GPx1). Our study provides evidence to explain the ethnopharmacological role of SDS and Rhodiola rosea in Chinese medicine. Our findings also support the use of SDS as an erythropoiesis-adjuvant agent to correct anemia and malhypoxia.

• Immunoassays using polypeptide conjugate binders with tuned affinity.

  Authors: Ken Cham Fai Leung, Ho Pui Ho, Yiu Wa Kwan, Siu Kai Kong

  Expert review of molecular diagnostics. 10/2010; 10(7):863-7.

  Evaluation of: Albrecht C, Fechner P, Honcharenko D et al. A new assay design for clinical diagnostics based on alternative recognition elements. Biosens. Bioelectron. 25(10), 2302-2308 (2010). ThisEvaluation of: Albrecht C, Fechner P, Honcharenko D et al. A new assay design for clinical diagnostics based on alternative recognition elements. Biosens. Bioelectron. 25(10), 2302-2308 (2010). This article focuses on a novel concept regarding the use of polypeptide conjugates as high-affinity binders to recognize targets in immunoassays. The polypeptide conjugate binder is a hybrid molecule in which a small recognition ligand is covalently linked to a synthetic polypeptide, which binds to a protein target of interest with high affinity and selectivity. Affinity of the polypeptide conjugate to its target can be tuned by changing the length of the aliphatic spacer in between the small recognition ligand and the polypeptide. Other pros and cons of this new approach for protein recognition and sensing are compared with other immunoassays such as ELISA, the bio-barcode assay and the aptamer-based barcode assay. It is anticipated that there will be more innovation and integration using new materials and technologies to provide novel ways to detect disease markers.

• AF1q enhancement of gamma irradiation-induced apoptosis by up-regulation of BAD expression via NF-kappaB in human squamous carcinoma A431 cells.

  Authors: Ngai Na Co, Wing Pui Tsang, Tsun Yee Tsang, Chi Lam Au Yeung, Pak Lun Yau, Siu Kai Kong, Tim Tak Kwok

  Oncology reports. 08/2010; 24(2):547-54.

  BAD (BCL-2 antagonist of cell death) is a pro-apoptotic BCL-2 family protein that plays a critical role in the regulation of apoptotic response. This study presents direct evidence that AF1qBAD (BCL-2 antagonist of cell death) is a pro-apoptotic BCL-2 family protein that plays a critical role in the regulation of apoptotic response. This study presents direct evidence that AF1q increased the radiation-induced apoptosis through up-regulation of BAD in human squamous carcinoma A431 cells and the key transcription factor involved is NF-kappaB. The minimal promoter sequence of BAD was identified; the activity was increased in AF1q stable transfectants and decreased upon AF1q siRNA transfection. The NF-kappaB consensus binding sequence is detected on BAD promoter. Inactivation of NF-kappaB by NF-kappaB inhibitor Bay 11-7082 or NF-kappaB p65 siRNA suppressed the expression and promoter activity of BAD; the suppression is more obvious in AF1q stable transfectants which also have an elevated NF-kappaB level. Mutation of putative NF-kappaB motif decreased the BAD promoter activity. The binding of NF-kappaB to the BAD promoter was confirmed by chromatin-immunoprecipitation. These findings indicate that AF1q up-regulation of BAD is through its effect on NF-kappaB and this may hint of its oncogenic mechanism in cancer.

• Surface-enhanced Raman scattering biosensor for DNA detection on nanoparticle island substrates.

  Authors: Wu Yuan, Ho Pui Ho, Rebecca K Y Lee, Siu-Kai Kong

  Applied optics. 09/2009; 48(22):4329-37.

  We present a study on the surface-enhanced Raman scattering (SERS) properties of Ag nanoparticle island substrates (NIS) and their applications for target oligonucleotide (OND) detection. It has beenWe present a study on the surface-enhanced Raman scattering (SERS) properties of Ag nanoparticle island substrates (NIS) and their applications for target oligonucleotide (OND) detection. It has been found that the surface nanostructure of NIS samples can be controlled with a good degree of reproducibility, and a high SERS enhancement can be achieved when the peak extinction wavelength of NIS is tuned to a spectral window (approximately 60 nm) between the excitation wavelength and the scattered Raman wavelength. The highest SERS enhancement was obtained from the NIS substrates with a nominal thickness of 50 A. Detection of target OND was performed with a sandwich format in which the target OND was hybridized both to a capture OND immobilized on the NIS substrate, and a detection OND conjugated with a Raman-active dye for SERS signal generation. We compare the detection performance of two strategies based on the use of the detection OND with or without the gold nanoparticle (Au-NP). Our results confirm that, when the detection OND is coupled to the Au-NP, a better sensitivity for the target OND detection, in terms of a wider dynamic range and a lower detection limit (0.4 fM versus 1 nM without Au-NP), would be achieved.

• Photodynamic therapy inhibits p-glycoprotein mediated multidrug resistance via JNK activation in human hepatomacellular carcinoma using the photosensitizer pheophorbide a.

  Authors: Patrick Ming-Kuen Tang, Dong-Mei Zhang, Ngoc-Ha Bui-Xuan, Stephen Kwok-Wing Tsui, Mary Miu-Yee Waye, Siu-Kai Kong, Wing-Ping Fong, Kwok-Pui Fung

  Molecular cancer. 08/2009; 8(1):56.

  ABSTRACT: BACKGROUND: Multidrug resistance (MDR) is frequently observed after prolonged treatment in human hepatoma with conventional anti-tumor drugs, and photodynamic therapy (PDT) is a recentlyABSTRACT: BACKGROUND: Multidrug resistance (MDR) is frequently observed after prolonged treatment in human hepatoma with conventional anti-tumor drugs, and photodynamic therapy (PDT) is a recently suggested alternative to overcome MDR. The therapeutic potential of PDT was evaluated in a multidrug resistance (MDR) human hepatoma cell line R-HepG2 with photosensitizer pheophorbide a (Pa). RESULTS: Our results demonstrated that intracellular accumulation of Pa was not reduced by the overexpression of p-glycoprotein. Pa-based PDT (Pa-PDT) significantly inhibited the growth of R-HepG2 cells with an IC50 value of 0.6 microM. Mechanistic study demonstrated that genomic DNA fragmentation and phosphatidylserine externalization were occurred where increase of intracellular singlet oxygen level triggers the phosphorylation of c-Jun N-terminal Kinase (JNK) and leads to activation of intrinsic apoptotic caspases cascade during the Pa-PDT treatment. The cytotoxicity of Pa-PDT, accumulation of sub-G1 population, and depolarization of mitochondrial membrane could be inhibited by JNK inhibitor in the Pa-PDT treated cells. Interestingly, the Pa-PDT induced JNK activation showed inhibitory effect on MDR by the down-regulation of p-glycoprotein in R-HepG2 cells in a dose-dependent manner. In addition, significant reduction of tumor size was obtained in Pa-PDT treated R-HepG2-bearing nude mice with no significant damages in liver and heart. CONCLUSION: In summary, our findings provided the first evidence that PDT could inhibit the MDR activity by down-regulating the expression of p-glycoprotein via JNK activation using pheophorbide a as the photosensitizer, and our work proved that Pa-PDT inhibit the growth of MDR hepatoma cells by mitochondrial-mediated apoptosis induction.

• Estrogen-related receptor alpha (ERRalpha) inverse agonist XCT-790 induces cell death in chemotherapeutic resistant cancer cells.

  Authors: Feng Wu, Junjian Wang, Yanfei Wang, Tim Tak Kwok, Siu-Kai Kong, Chiwai Wong

  Chemico-biological interactions. 06/2009;

  Estrogen-related receptor alpha (ERRalpha) is primarily thought to regulate energy homeostasis through interacting with peroxisome proliferator-activated receptor gamma coactivator-1alpha and -1betaEstrogen-related receptor alpha (ERRalpha) is primarily thought to regulate energy homeostasis through interacting with peroxisome proliferator-activated receptor gamma coactivator-1alpha and -1beta (PGC-1alpha and -1beta). They coordinately control the transcription of genes in the oxidative phosphorylation pathway. In addition to its role in energy metabolism, ERRalpha has also been implicated as a prognostic marker for breast, ovarian, colon and prostate cancers. In this study, we found that an ERRalpha inverse agonist XCT-790 induced cell death in HepG2 hepatocarcinoma and its multi-drug resistance (MDR) sub-line R-HepG2. Using a dye Mitotracker Green which stains mitochondrion independent of mitochondrial membrane potential (DeltaPsi(m)), we found that XCT-790 dose-dependently decreased mitochondrial mass. Intriguingly, XCT-790 increased DeltaPsi(m) upon short term treatment but decreased DeltaPsi(m) upon longer term treatment. The changes of DeltaPsi(m) in turn promoted the production of reactive oxygen species (ROS) and led to ROS-mediated caspases 3/7, 8, 9 activation and cell death. Importantly, we established that an anti-oxidative compound Mn(III) Tetra(4-benzoic acid) porphyrin chloride (MnTBAP) blocked the caspases activities and cell death increased by XCT-790 treatment. Finally, we found that XCT-790 synergized with paclitaxel to induce cell death in multi-drug resistance sub-line R-HepG2. Our results provide a conceptual framework for further developing chemotherapeutics based on suppressing ERRalpha activity.

• Role of monoamine oxidases in the exaggerated 5-hydroxytryptamine-induced tension development of human isolated preeclamptic umbilical artery.

  Authors: Sai Wang Seto, Ho Yeung Lam, Wing Sze Lau, Alice L S Au, Tsz Yan Lam, Stephen S C Chim, Sai Ming Ngai, Shun-Wan Chan, Tak Yeung Leung, John H K Yeung, Siu-Kai Kong, George P H Leung, Simon M Y Lee, Yiu Wa Kwan

  European journal of pharmacology. 02/2009;

  We investigated the role(s) of monoamine oxidases (MAOs) on the altered 5-hydroxytryptamine (5-HT, serotonin)-induced tension development of the isolated umbilical artery of preeclamptic pregnancy ofWe investigated the role(s) of monoamine oxidases (MAOs) on the altered 5-hydroxytryptamine (5-HT, serotonin)-induced tension development of the isolated umbilical artery of preeclamptic pregnancy of Chinese women. An enhanced 5-HT-induced tension development of the umbilical artery of preeclamptic pregnancy was observed when compared with that of normal pregnancy. The enhanced component of 5-HT-induced tension development was eradicated by clorgyline (a MAO-A inhibitor). Blockade of eNOS (endothelial isoform nitric oxide synthase) (N(omega)-nitro-L-arginine methyl ester), 5-HT transporter (citalopram), 5-HT receptor subtypes (5HT(2B), SB 204741; 5-HT(2C), RS 102221; 5-HT(7), SB 269970), and endothelium denudation of the umbilical artery of normal pregnancy mimicked the enhanced 5-HT-induced tension development as observed in the preeclamptic tissues. In contrast, no apparent changes in 5-HT-induced tension development of the umbilical artery of preeclamptic pregnancy were observed with the same pharmacological manipulations. A decreased protein expression levels of MAO-A and eNOS (no iNOS and MAO-B expression was detected) and no change in caveolin-1 and 5-HT transporter expression were demonstrated in the umbilical artery (endothelium intact) lysate of preeclamptic pregnancy, compared to that of the umbilical artery of normal pregnancy. Thus, in the umbilical artery of preeclamptic pregnancy, a decrease of MAO-A and eNOS protein expression levels are probably associated with, or responsible for, the exaggerated 5-HT-induced tension development.

• Mechanistic study on growth suppression and apoptosis induction by targeting hepatoma-derived growth factor in human hepatocellular carcinoma HepG2 cells.

  Authors: Tsun Yee Tsang, Wan Yee Tang, Wing Pui Tsang, Ngai Na Co, Siu-Kai Kong, Tim Tak Kwok

  Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry, and pharmacology. 02/2009; 24(3-4):253-62.

  Hepatoma-derived growth factor (HDGF) is frequently overexpressed in human cancer. The growth factor was previously demonstrated to be a survival factor as knock-down of HDGF suppresses the growthHepatoma-derived growth factor (HDGF) is frequently overexpressed in human cancer. The growth factor was previously demonstrated to be a survival factor as knock-down of HDGF suppresses the growth and induces apoptosis in human cancer cells through the Bad-mediated intrinsic apoptotic pathway. However, inactivation of Bad cannot completely repress the apoptosis induced upon HDGF knock-down, indicating the presence of other unidentified pathways. In the present study, HDGF knock-down was shown to trigger the Fas-mediated extrinsic apoptotic pathway in human hepatocellular carcinoma HepG2 cells through NF-kappaB signaling pathway. Increases in Fas expression and fas promoter activity were detected upon HDGF knock-down by Western blot analysis and luciferase reporter assay. Knock-down of fas inhibited HDGF knock-down effect on apoptosis induction and growth suppression as revealed by annexin V binding assay and soft agar assay. Down-regulation of IkappaBalpha was also observed upon HDGF knock-down. Overexpression of IkappaBalpha by transient transfection or inhibition of NF-kappaB by BAY11-7082 suppressed HDGF knock-down effect on fas promoter activation, Fas up-regulation, apoptosis induction and growth suppression. Furthermore, the interaction of Fas-mediated extrinsic and Bad-mediated intrinsic apoptotic pathways was demonstrated as a stronger inhibition on apoptosis induction and growth suppression upon HDGF knock-down was observed when both pathways were inactivated. The results therefore suggested that, through both intrinsic and extrinsic apoptotic pathways, HDGF may function as a survival factor and be a potential target for cancer therapy.

• Targeted photoporation and transfection in human HepG2 cells by a fiber femtosecond laser at 1554 nm.

  Authors: Hao He, Siu-Kai Kong, Rebecca Kit-Ying Lee, Yick-Keung Suen, Kam Tai Chan

  Optics letters. 01/2009; 33(24):2961-3.

  We report the transfection of human hepatocarcinoma (HepG2) cells by femtosecond (fs) laser pulses at 1554 nm. It was found that HepG2 cells could be perforated transiently to admit propidium iodideWe report the transfection of human hepatocarcinoma (HepG2) cells by femtosecond (fs) laser pulses at 1554 nm. It was found that HepG2 cells could be perforated transiently to admit propidium iodide by that laser. This photoporation was safe, as the membrane resealed itself within a short time and no mitochondrial depolarization was detected. The cells were next photoporated in the presence of DNA plasmids for the expression of green fluorescence protein, and about 80% of the exposed cells showed green fluorescence 24 h later. Thus it could be concluded that it is safe and efficient to use fs laser at 1554 nm to transfect foreign molecules into cells under a standard microscope.

• Photodynamic therapy inhibits p-glycoprotein mediated multidrug resistance via JNK activation in human hepatocellular carcinoma using the photosensitizer pheophorbide a

  Authors: Patrick Tang, Dong-Mei Zhang, Ngoc-Ha Xuan, Stephen Tsui, Mary Waye, Siu-Kai Kong, Wing-Ping Fong, Kwok-Pui Fung

  Molecular Cancer. 01/2009;

  Abstract Background Multidrug resistance (MDR) is frequently observed after prolonged treatment in human hepatoma with conventional anti-tumor drugs, and photodynamic therapy (PDT) is a recentlyAbstract Background Multidrug resistance (MDR) is frequently observed after prolonged treatment in human hepatoma with conventional anti-tumor drugs, and photodynamic therapy (PDT) is a recently suggested alternative to overcome MDR. The therapeutic potential of PDT was evaluated in a multidrug resistance (MDR) human hepatoma cell line R-HepG2 with photosensitizer pheophorbide a (Pa). Results Our results demonstrated that intracellular accumulation of Pa was not reduced by the overexpression of P-glycoprotein. Pa-based PDT (Pa-PDT) significantly inhibited the growth of R-HepG2 cells with an IC50 value of 0.6 μM. Mechanistic study demonstrated that genomic DNA fragmentation and phosphatidylserine externalization occurred where increase of intracellular singlet oxygen level triggers the phosphorylation of c-Jun N-terminal Kinase (JNK) and leads to activation of intrinsic apoptotic caspases cascade during the Pa-PDT treatment. The cytotoxicity of Pa-PDT, accumulation of sub-G1 population, and depolarization of mitochondrial membrane could be inhibited by JNK inhibitor in the Pa-PDT treated cells. Interestingly, the Pa-PDT induced JNK activation showed inhibitory effect on MDR by the down-regulation of P-glycoprotein in R-HepG2 cells in a dose-dependent manner. In addition, significant reduction of tumor size was obtained in Pa-PDT treated R-HepG2-bearing nude mice with no significant damages in liver and heart. Conclusion In summary, our findings provided the first evidence that PDT could inhibit the MDR activity by down-regulating the expression of P-glycoprotein via JNK activation using pheophorbide a as the photosensitizer, and our work proved that Pa-PDT inhibited the growth of MDR hepatoma cells by mitochondrial-mediated apoptosis induction.

• Disturbance of cellular glucose transport by two prevalently used fluoroquinolone antibiotics ciprofloxacin and levofloxacin involves glucose transporter type 1.

  Authors: Daniel Tianfang Ge, Pui Ying Peggy Law, Siu-Kai Kong, Yuan-Yuan Ho

  Toxicology letters. 11/2008;

  Dysglycemia and central nervous system (CNS) complications are the known adverse effects of fluoroquinolone antibiotics. Ciprofloxacin and levofloxacin are among the most prescribed antibiotics. InDysglycemia and central nervous system (CNS) complications are the known adverse effects of fluoroquinolone antibiotics. Ciprofloxacin and levofloxacin are among the most prescribed antibiotics. In this study we demonstrate that ciprofloxacin and levofloxacin disturb glucose transport into HepG2 cells and such inhibition is associated with inhibited glucose transporter type 1 (GLUT1) function. When exposed to ciprofloxacin or levofloxacin at maximum plasma concentrations (C(max)) and 5x of C(max) concentrations, cellular GLUT1 mRNA expression, cell surface GLUT1 protein expression and glucose uptake were significantly reduced. These findings imply that disturbed cellular glucose transport and GLUT1 function may underlie the dysglycemic and CNS effects of ciprofloxacin and levofloxacin.

• Oncogene AF1q enhances doxorubicin-induced apoptosis through BAD-mediated mitochondrial apoptotic pathway.

  Authors: Ngai Na Co, Wing Pui Tsang, Timothy W L Wong, Hoi Hung Cheung, Tsun Yee Tsang, Siu-Kai Kong, Tim Tak Kwok

  Molecular cancer therapeutics. 11/2008; 7(10):3160-8.

  AF1q is an oncogenic factor involved in leukemia development, thyroid tumorigenesis, and breast cancer metastasis. In the present study, AF1q was found to be down-regulated in a doxorubicin-resistantAF1q is an oncogenic factor involved in leukemia development, thyroid tumorigenesis, and breast cancer metastasis. In the present study, AF1q was found to be down-regulated in a doxorubicin-resistant subline of human squamous carcinoma A431 cells. Knockdown of AF1q decreased the apoptosis induced by doxorubicin, Taxol, gamma-radiation, IFN-alpha, and IFN-gamma in A431 cells. On the other hand, overexpression of AF1q increased the doxorubicin-induced apoptosis in A431 cells as well as in HepG2 and HL60 cells. Both exogenous and ectopic expression of AF1q in A431 cells increased the mRNA and protein levels of BAD, a proapoptotic BCL-2 family protein. Gene silencing of BAD by small interfering RNA suppressed the AF1q enhancement of apoptosis, suggesting that BAD is downstream of AF1q in regulation of apoptosis. Furthermore, AF1q enhanced the mitochondrial membrane depolarization, mitochondrial cytochrome c release, and activation of caspase-9 and caspase-3 on doxorubicin treatment. Collectively, AF1q increases doxorubicin-induced apoptosis in cells through activation of BAD-mediated apoptotic pathway. The study provides the first evidence that AF1q plays a critical role in the regulation of apoptosis and drug resistance. [Mol Cancer Ther 2008;7(10):3160-8].

• Downregulation of hepatoma-derived growth factor activates the Bad-mediated apoptotic pathway in human cancer cells.

  Authors: Tsun Yee Tsang, Wan Yee Tang, Wing Pui Tsang, Ngai Na Co, Siu-Kai Kong, Tim Tak Kwok

  Apoptosis : an international journal on programmed cell death. 09/2008; 13(9):1135-47.

  Hepatoma-derived growth factor (HDGF) is highly expressed in human cancer and its expression is correlated with poor prognosis of cancer. The growth factor is known to stimulate cell growth while theHepatoma-derived growth factor (HDGF) is highly expressed in human cancer and its expression is correlated with poor prognosis of cancer. The growth factor is known to stimulate cell growth while the underlying mechanism is however not clear. Transfection with HDGF cDNA stimulated while its specific antisense oligonucleotides repressed the growth of human hepatocellular carcinoma HepG2 cells. Furthermore, knock-down of HDGF by antisense oligos also induced apoptosis in HepG2 cells and in other human cancer cells, e.g. human squamous carcinoma A431 cells. HDGF knock-down was found to induce the expression of the pro-apoptotic protein Bad and also inactivate ERK and Akt, which in turn led to dephosphorylation of Bad at Ser-112, Ser-136, and activation of the intrinsic apoptotic pathway, i.e. depolarization of the mitochondrial membrane, release of mitochondrial cytochrome c, increase in the processing of caspase 9 and 3. As HDGF knock-down not only suppresses the growth but also induces apoptosis in human cancer cells, HDGF may therefore serve as a survival factor for human cancer cells and a potential target for cancer therapy.