Jung-Chien Cheng

University of British Columbia - Vancouver, Vancouver, British Columbia, Canada

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Publications (26)114.93 Total impact

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    ABSTRACT: Aberrant epidermal growth factor receptor (EGFR) activation is associated with ovarian cancer progression. In this study, we report that the EGFR ligand amphiregulin (AREG) stimulates cell invasion and down-regulates E-cadherin expression in two human ovarian cancer cell lines, SKOV3 and OVCAR5. In addition, AREG increases the expression of transcriptional repressors of E-cadherin including SNAIL, SLUG and ZEB1. siRNA targeting SNAIL or SLUG abolishes AREG-induced cell invasion. Moreover, ERK1/2 and AKT pathways are involved in AREG-induced E-cadherin down-regulation and cell invasion. Finally, we show that three EGFR ligands, AREG, epidermal growth factor (EGF) and transforming growth factor-α (TGF-α), exhibit comparable effects in down-regulating E-cadherin and promoting cell invasion. This study demonstrates that AREG induces ovarian cancer cell invasion by down-regulating E-cadherin expression.
    FEBS letters. 09/2014;
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    ABSTRACT: Context: Regulation of progesterone production in granulosa cells is important for normal reproductive functions. Steroidogenic acute regulatory protein (StAR) is recognized as the key regulatory protein involved in the rate-limiting step of steroidogenesis. TGF-β1 protein is detected in human follicular fluid, and TGF-β1 and its receptors are expressed in human granulosa cells. However, the functional role of TGF-β1 in the regulation of StAR expression and progesterone production in human granulosa cells remains unknown. Objective: Our objective was to investigate the effects of TGF-β1 on StAR expression and progesterone production in human granulosa cells. Design and Setting: SVOG cells are human granulosa cells that were obtained from women undergoing in vitro fertilization and immortalized with SV40 large T antigen. SVOG cells were used to investigate the effects of TGF-β1 on StAR expression and progesterone production at an academic research center. Main Outcome Measures: Levels of mRNA and protein were examined by RT-qPCR and western blotting, respectively. The accumulation levels of progesterone were measured by enzyme-linked immunosorbent assay (ELISA). Results: TGF-β1 treatment downregulated StAR expression and decreased progesterone production. The suppressive effects of TGF-β1 on StAR expression and progesterone production were abolished by the inhibition of TGF-β type I receptor. In addition, treatment with TGF-β1 activated the Smad2/3 and ERK1/2 signaling pathways. The inhibition of the Smad3 and ERK1/2 signaling pathways attenuated the TGF-β1-induced downregulation of StAR expression and progesterone production. Conclusion: TGF-β1 downregulated StAR expression and decreased progesterone production by activating the Smad3 and ERK1/2 signaling pathways in human granulosa cells.
    The Journal of clinical endocrinology and metabolism. 08/2014;
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    ABSTRACT: Context: Inhibin β subunits and activin receptors are expressed by human trophoblast cells. Though activin A has been shown to enhance human trophoblast cell invasion, whether two additional activin isoforms, activin B and AB, exert similar effects remains unknown. Moreover, whether the expression of mesenchymal adhesion molecule neural cadherin (N-cadherin) is essential for this pro-invasive effect of activin has yet to be determined. Objective: To examine the effects of all three activin isoforms on human trophoblast cell invasion and the involvement of N-cadherin. Design: HTR8/SVneo immortalized extravillous cytotrophoblast (EVT) cells and primary cultures of human EVT cells were used as study models. Small interfering RNA (siRNA)-mediated knockdown approaches were used to investigate the molecular determinants of activin-mediated functions. Setting: An academic research center. Main Outcome Measures: RT-quantitative real-time PCR and Western blot analysis were used to examine mRNA and protein levels, respectively. Cell invasiveness was assessed by Matrigel-coated transwell assays. Results: All three activin isoforms produced comparable increases in HTR8/SVneo cell invasion as well as N-cadherin expression. In addition, the up-regulatory effect of activin isoforms on N-cadherin was confirmed in primary cultures of human trophoblast cells. Interestingly, siRNA-mediated down-regulation of N-cadherin attenuated basal and activin-induced invasion of both HTR8/SVneo and primary trophoblast cells. All three activin isoforms induced equivalent phosphorylation of SMAD2 and SMAD3. Importantly, activin-stimulated cell invasion, up-regulation of N-cadherin as well as activation of SMAD2/SMAD3 were abolished by the TGF-β type I receptor inhibitor SB431542 in HTR8/SVneo cells. Furthermore, knockdown of SMAD2/3 or common SMAD4 abolished the stimulatory effects of all three activin isoforms on N-cadherin expression. Conclusion: Activin A, B and AB produce comparable increases in human trophoblast cell invasion by up-regulating N-cadherin expression in a SMAD2/3-SMAD4-dependent manner.
    Journal of Clinical Endocrinology &amp Metabolism 08/2014; · 6.43 Impact Factor
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    ABSTRACT: Elevated expression of cyclooxygenase 2 (COX2 (PTGS2)) has been reported to occur in human ovarian cancer and to be associated with poor prognosis. We have previously demonstrated that COX2-derived prostaglandin E2 (PGE2) promotes human ovarian cancer cell invasion. We had also demonstrated that epidermal growth factor (EGF) induces human ovarian cancer cell invasion by downregulating the expression of E-cadherin through various signaling pathways. However, it remains unclear whether COX2 and PGE2 are involved in the EGF-induced downregulation of E-cadherin expression and cell invasion in human ovarian cancer cells. In this study, we showed that EGF treatment induces COX2 expression and PGE2 production in SKOV3 and OVCAR5 human ovarian cancer cell lines. Interestingly, COX2 is not required for the EGF-induced downregulation of E-cadherin expression. In addition, EGF treatment activates the phosphatidylinositol-3-kinase (PI3K)/Akt and cAMP response element-binding protein (CREB) signaling pathways, while only the PI3K/Akt pathway is involved in EGF-induced COX2 expression. Moreover, we also showed that EGF-induced cell invasion is attenuated by treatment with a selective COX2 inhibitor, NS-398, as well as PGE2 siRNA. This study demonstrates an important role for COX2 and its derivative, PGE2, in the mediation of the effects of EGF on human ovarian cancer cell invasion.
    Endocrine Related Cancer 08/2014; 21(4):533-43. · 5.26 Impact Factor
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    ABSTRACT: Context: Exerting a broad range of biological effects in various tissues, activins are homo- or heterodimers of activin/inhibin β subunits (βA, βB, βC and βE in humans). While activins A (βAβA), B (βBβB), AB (βAβB) and AC (βAβC) have been demonstrated in the female reproductive system, little is known about their individual functions in the ovary. Objective: To investigate the biological roles and activities of activins in regulating steroidogenesis in human granulosa cells. Design: Human granulosa-lutein cells obtained from 32 patients undergoing in vitro fertilization were used to investigate the effects of activin A, B, AB and AC on the expression of steroidogenic enzymes and steroid production. Setting: An academic research center. Main Outcome Measures: mRNA and protein levels were examined by RT-qPCR and Western blot analysis, respectively. The production of estradiol and progesterone were measured by enzyme immunoassay. Results: P450 aromatase, FSH receptor and estradiol levels were increased, whereas StAR, LH receptor and progesterone levels were decreased, following treatment with activin A, B and AB, but not activin AC. FSH or LH induced the production of aromatase/estradiol and StAR/progesterone; however pre-treatment with activin A, B or AB enhanced the effects of gonadotropins on aromatase/estradiol, but suppressed their effects on StAR/progesterone. Treatment with activin A, B or AB induced the phosphorylation of SMAD2 and 3, whereas activin AC had no such effects. Furthermore, co-culture of activin AC (1-100 ng/ml) with activin A (25 ng/ml) did not alter the effects of activin A on P450 aromatase or StAR mRNA levels. Conclusion: Activin A, B and AB have similar effects on steroidogenesis in human granulosa cells. In contrast, activin AC is not biologically active and does not act as a competitive antagonist.
    Journal of Clinical Endocrinology &amp Metabolism 07/2014; · 6.43 Impact Factor
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    ABSTRACT: Context: Cyclooxygenase-2 (COX-2) expression and prostaglandin E2 (PGE2) production have been shown to play key roles in the regulation of ovulation. The transforming growth factor-beta (TGF-β) superfamily members are important molecules that regulate many ovarian functions under normal physiological and pathological conditions. TGF-β1 and its receptors are expressed in human granulosa cells. However, to date, whether TGF-β1 can regulate COX-2 expression and PGE2 production, which in turn contribute to the process of ovulation, remains unknown. Objective: To investigate the effects of TGF-β1 on COX-2 expression and PGE2 production in human granulosa cells. Design: SVOG cells are human granulosa cells that were obtained from women undergoing in vitro fertilization (IVF) and immortalized with SV40 large T antigen. SVOG cells were used to investigate the effect of TGF-β1 on COX-2 expression and PGE2 production. Setting: An academic research center. Main Outcome Measures: mRNA and protein levels were examined by RT-qPCR and western blotting, respectively. The concentrations of PGE2 in the culture medium were measured by enzyme-linked immunosorbent assay (ELISA). Results: TGF-β1 treatment induced COX-2 expression and PGE2 production. The inductive effects of TGF-β1 on COX-2 and PGE2 were abolished by inhibition of TGF-β type I receptor (TβRI). In addition, treatment with TGF-β1 activated Smad2 and Smad3 signaling pathways. Inhibition of Smad signaling pathways by siRNA-mediated approaches attenuated TGF-β1-induced COX-2 expression and PGE2 production. Conclusion: TGF-β1 induced PGE2 production by inducing COX-2 expression through a Smad-dependent signaling pathway in human granulosa cells.
    The Journal of Clinical Endocrinology and Metabolism 04/2014; · 6.31 Impact Factor
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    ABSTRACT: In the ovary, connexin-coupled gap junctions in granulosa cells play crucial roles in follicular and oocyte development as well as in corpus luteum formation. Our previous work has shown that theca cell-derived bone morphogenetic protein (BMP)4 and BMP7 decrease gap junction intercellular communication (GJIC) activity via the down-regulation of connexin43 (Cx43) expression in immortalized human granulosa cells. However, the effects of oocyte-derived growth factors on Cx43 expression remain to be elucidated. The present study was designed to investigate the effects of oocyte-derived growth differentiation factor (GDF)9 and BMP15 on the expression of Cx43 in a human granulosa cell line, SVOG. We also examined the effect relative to GJIC activity and investigated the potential mechanisms of action. In SVOG cells, treatment with BMP15 but not GDF9 significantly decreased Cx43 mRNA and protein levels and GJIC activity. These suppressive effects, along with the induction of Smad1/5/8 phosphorylation, were attenuated by co-treatment with a BMP type I receptor inhibitor, dorsomorphin. Furthermore, knockdown of the central component of the TGF-β superfamily signaling pathway, Smad4, using small interfering RNA reversed the suppressive effects of BMP15 on Cx43 expression and GJIC activity. The suppressive effects of BMP15 on Cx43 expression were further confirmed in primary human granulosa-lutein cells obtained from infertile patients undergoing an in vitro fertilization procedure. These findings suggest that oocyte-derived BMP15 decreases GJIC activity between human granulosa cells by down-regulating Cx43 expression, most likely via a Smad-dependent signaling pathway.
    Molecular Human Reproduction 01/2014; · 4.54 Impact Factor
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    ABSTRACT: Human granulosa cell tumors (GCTs) are rare, and their etiology remains largely unknown. Recently, the FOXL2 402C>G (C134W) mutation was found to be specifically expressed in human adult-type GCTs; however, its function in the development of human GCTs is not fully understood. Activins are members of the transforming growth factor-beta superfamily, which has been shown to stimulate normal granulosa cell proliferation; however, little is known regarding the function of activins in human GCTs. In this study, we examined the effect of activin A on cell proliferation in the human GCT-derived cell line KGN. We show that activin A treatment stimulates KGN cell proliferation. Treatment with the activin type I receptor inhibitor SB431542 blocks activin A-stimulated cell proliferation. In addition, our results show that cyclin D2 is induced by treatment with activin A and is involved in activin A-stimulated cell proliferation. Moreover, the activation of Smad signaling is required for activin A-induced cyclin D2 expression. Finally, we show that the overexpression of the wild-type FOXL2 but not the C134W mutant FOXL2 induced follistatin production. Treatment with exogenous follistatin blocks activin A-stimulated cell proliferation, and the overexpression of wild-type FOXL2 attenuates activin A-stimulated cell proliferation. These results suggest that FOXL2 may act as a tumor suppressor in human adult-type GCTs by inducing follistatin expression, which subsequently inhibits activin-stimulated cell proliferation.
    Biochemical and Biophysical Research Communications 12/2013; · 2.28 Impact Factor
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    ABSTRACT: In addition to somatic cell-derived growth factors, oocyte-derived GDF9 and BMP15 play essential roles in female fertility. However, few studies have investigated their effects on human ovarian steroidogenesis, and fewer still have examined their differential effects or underlying molecular determinants. In the present study, we used immortalized human granulosa cells (SVOG) and human granulosa cell tumor cells (KGN) to compare the effects of GDF9 and BMP15 on steroidogenic enzyme expression, and investigate potential mechanisms of action. In SVOG cells, neither GDF9 nor BMP15 affects the mRNA levels of P450 side chain cleavage enzyme or 3β-hydroxysteroid dehydrogenase. However, treatment with BMP15, but not GDF9, significantly decreases StAR mRNA and protein levels as well as progesterone production. These suppressive effects, along with the induction of SMAD1/5/8 phosphorylation, are attenuated by co-treatment with two different BMP type I receptor inhibitors (dorsomorphin and DMH-1). Furthermore, depletion of ALK3 using small interfering RNA reverses the effects of BMP15 on SMAD1/5/8 phosphorylation and StAR expression. Similarly, knockdown of ALK3 abolishes BMP15-induced SMAD1/5/8 phosphorylation in KGN cells. These results provide evidence that oocyte-derived BMP15 down-regulates StAR expression and decreases progesterone production in human granulosa cells, likely via ALK3-mediated SMAD1/5/8 signaling. Our findings suggest that oocyte may play a critical role in the regulation of progesterone to prevent premature luteinization during the late stage of follicle development.
    Molecular Endocrinology 10/2013; · 4.75 Impact Factor
  • Jung-Chien Cheng, Hsun-Ming Chang, Peter C K Leung
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    ABSTRACT: Human trophoblast cells express transforming growth factor-beta (TGF-β) and TGF-β receptors. It has been shown that TGF-β1 treatment decreases the invasiveness of trophoblast cells. However, the molecular mechanisms underlying TGF-β1-decreased trophoblast invasion are still not fully understood. In the current study, we demonstrated that treatment of HTR-8/SVneo human trophoblast cells with TGF-β1 decreased cell invasion and down-regulated the expression of vascular endothelial cadherin (VE-cadherin). In addition, the inhibitory effect of TGF-β1 on VE-cadherin was confirmed in primary cultures of human trophoblast cells. Moreover, knockdown of VE-cadherin using siRNA decreased the invasiveness of HTR-8/SVneo cells and primary cultures of trophoblast cells. Treatment with TGF-β1 induced the activation of Smad-dependent signaling pathways and the expression of Snail and Slug. Knockdown of Smads attenuated TGF-β1-induced up-regulation of Snail and Slug and down-regulation of VE-cadherin. Interestingly, depletion of Snail, but not Slug, attenuated TGF-β1-induced down-regulation of VE-cadherin. Furthermore, overexpression of Snail suppressed VE-cadherin expression. Chromatin immunoprecipitation analyses showed the direct binding of Snail to the VE-cadherin promoter. These results provide evidence that Snail mediates TGF-β1-induced down-regulation of VE-cadherin, which subsequently contributed to TGF-β1-decreased trophoblast cell invasion.
    Journal of Biological Chemistry 10/2013; · 4.65 Impact Factor
  • Yu Zhang, Jung-Chien Cheng, He-Feng Huang, Peter C K Leung
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    ABSTRACT: Breast cancer is the most common hormone-dependent malignancy in women. Homeobox (HOX) transcription factors regulate many cellular functions, including cell migration, proliferation and differentiation. The aberrant expression of HOX genes has been reported to be associated with human reproductive cancers. Estradiol (E2) and its nuclear receptors, estrogen receptor (ER)-alpha and ER-beta, are known to play critical roles in the regulation of breast cancer cell growth. However, an understanding of the potential relationship between HOXA7 and ER in breast cancer cells is limited. In this study, our results demonstrate that knockdown of HOXA7 in MCF7 cells significantly decreased cell proliferation and ER-alpha expression. In addition, HOXA7 knockdown attenuated E2-induced cell proliferation as well as progesterone receptor (PR) expression. The stimulatory effects of E2 on cell proliferation and PR expression were abolished by co-treatment with ICI 182780, a selective ER-alpha antagonist. In contrast, overexpression of HOXA7 significantly stimulated cell proliferation and ER-alpha expression. Moreover, E2-induced cell proliferation, as well as PR expression, was enhanced by the overexpression of HOXA7. Neither knockdown nor overexpression of HOXA7 affected the ER-beta levels. Our results demonstrate a novel mechanistic role for HOXA7 in modulating breast cancer cell proliferation via regulation of ER-alpha expression. This finding contributes to our understanding of the role HOXA7 plays in regulating the proliferation of ER-positive cancer cells.
    Biochemical and Biophysical Research Communications 10/2013; · 2.28 Impact Factor
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    ABSTRACT: Context:Aberrant regulation of ovulation is one of the major causes of infertility. In animal models, three epidermal growth factor (EGF)-like growth factors, amphiregulin (AREG), betacellulin (BTC) and epiregulin (EREG), have been shown to be involved in ovulation by regulating cyclooxygenase-2 (COX-2) expression and prostaglandin E2 (PGE2) production. However, whether the same is true in humans remains largely unknown.Objective:To investigate the effects of AREG, BTC and EREG on COX-2 expression and PEG2 production in human granulosa cells.Design:SVOG cells are human granulosa cells that were obtained from women undergoing in vitro fertilization (IVF) and immortalized with SV40 large T antigen. SVOG cells were used to investigate the effect of AREG, BTC and EREG on ovulation-related functions.Setting:Academic research center.Main Outcome Measures:Levels of mRNA and protein were examined by RT-qPCR and western blotting, respectively. The protein levels of PGE2 were measured by enzyme-linked immunosorbent assay (ELISA).Results:LH treatment up-regulated AREG, BTC and EREG and COX-2. Knockdown of EGFR attenuated LH-induced COX-2 expression and PGE2 production. Treatment with AREG, BTC and EREG up-regulated COX-2 expression and PGE2 production. The stimulatory effects of AREG, BTC and EREG on COX-2 expression and PGE2 production were blocked by inhibition of EGFR activity and expression. AREG-, BTC- and EREG-activated ERK1/2 signaling, but not Akt signaling, was required for AREG-, BTC- and EREG-induced COX-2 expression and PGE2 production.Conclusion:AREG, BTC and EREG induced PGE2 production by up-regulating COX-2 expression through ERK1/2 signaling in human granulosa cells.
    The Journal of Clinical Endocrinology and Metabolism 10/2013; · 6.31 Impact Factor
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    ABSTRACT: Overexpression of HER2 is correlated with a poor prognosis in many types of human cancers. Due to the interaction between HER2 and other ErbB receptors, HER2 is implicated in the EGF family of ligands-regulated tumor progression. In ovarian cancer, although the relationships between HER2 amplification and patient prognosis remain controversial, the underlying molecular mechanisms of HER2-mediated tumor progression are not fully understood. Our previous studies demonstrated that EGF induces ovarian cancer cell invasion by down-regulating E-cadherin expression through the up-regulation of its transcriptional repressors, Snail and Slug. It has been shown that overexpression of HER2 down-regulates E-cadherin expression in human mammary epithelial cells. However, whether HER2 mediates EGF-induced down-regulation of E-cadherin remains unknown. In this study, we examined the potential role of HER2 in EGF-induced down-regulation of E-cadherin and increased cell invasion. We show that EGF treatment induces the interaction of EGFR with HER2 and increases the activation of HER2 in human ovarian cancer cells; we also show that these effects are diminished by knockdown of EGFR. Importantly, treatment with HER2-specific tyrosine kinase inhibitor, AG825, and HER2 siRNA diminished the up-regulation of Snail and Slug as well as the down-regulation of E-cadherin by EGF. Finally, we also show that EGF-induced cell invasion was attenuated by treatment with HER2 siRNA. This study demonstrates an important role for HER2 in mediating the effects of EGF on Snail, Slug and E-cadherin expression as well as invasiveness in human ovarian cancer cells.
    Biochemical and Biophysical Research Communications 03/2013; · 2.28 Impact Factor
  • Hsun-Ming Chang, Jung-Chien Cheng, Peter C K Leung
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    ABSTRACT: Context:Connexin43 (Cx43)-coupled gap junctions in granulosa cells play important roles in follicular and oocyte development and may be modulated by theca cell-derived bone morphogenic protein (BMP) 4 and BMP7.Objective:The aim of this study was to examine the effects of BMP4 and BMP7 on Cx43 expression in human granulosa cells and its potential mediation by the Smad-dependent pathway.Design:An immortalized human granulosa (SVOG) cell was used to investigate Cx43 expression and gap junction intercellular communication (GJIC) activity after exposure to BMP4 and BMP7. A BMP type I inhibitor, dorsomorphin, and small interfering RNAs targeting Smad4 were used to verify the specificity of the effects.Setting:The study was conducted in an academic center.Main Outcome Measures:Extracts were prepared from cultured cells, the Cx43 mRNA levels were examined using RT-quantitative real-time PCR, and the levels of Cx43 protein and phosphorylated Smad1/5/8 were assayed using Western blot analyses. GJIC activities between SVOG cells were evaluated using a scrape loading and dye transfer assay.Results:Treatment with BMP4 and BMP7 significantly decreased Cx43 mRNA and protein levels, as well as GJIC activities. These suppressive effects were attenuated by cotreatment with the BMP type I receptor inhibitor dorsomorphin. Furthermore, Smad4 knockdown reversed the effects of BMP4 and BMP7 on Cx43 expression.Conclusion:Theca cell-derived BMP4 and BMP7 down-regulate Cx43 expression and decrease GJIC activity in human granulosa cells. Our findings indicate that this biological effect is most likely mediated by a Smad-dependent pathway.
    The Journal of Clinical Endocrinology and Metabolism 02/2013; · 6.31 Impact Factor
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    Jung-Chien Cheng, Christian Klausen, Peter C K Leung
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    ABSTRACT: The etiology of granulosa cell tumors (GCTs) is largely unknown. The primary mode of treatment is surgical, however not all women are cured by surgery alone. Thus, it is important to develop improved treatments through a greater understanding of the molecular mechanisms that contribute to this disease. Recently, it has been shown that a FOXL2 402C>G (C134W) mutation is present in 97% of human adult-type GCTs, suggesting an important role for this mutation in the development of GCTs. We have shown previously that gonadotropin-releasing hormone (GnRH)-I and -II induce apoptosis in cultured normal human granulosa cells. Moreover, it has been reported that FOXL2 can bind to the promoter of the mouse GnRH receptor gene and regulate its transcription. Thus, we hypothesized that C134W mutant FOXL2 could modulate the pro-apoptotic effects of GnRH via aberrant regulation of GnRH receptor levels. Using KGN cells, a human GCT-derived cell line which harbors the FOXL2 402C>G mutation, we show that treatment with GnRH-I and -II induces cell apoptosis, and that small interfering RNA-mediated depletion of GnRH receptor abolishes these effects. Overexpression of wild-type FOXL2 increases both mRNA and protein levels of GnRH receptor and consequently enhances GnRH-induced apoptosis. Importantly, neither the expression levels of GnRH receptor nor GnRH-induced apoptosis were affected by overexpression of the C134W mutant FOXL2. Interestingly, knockdown of endogenous FOXL2 down-regulates GnRHR expression in normal human granulosa cells with wild-type FOXL2, but not in KGN cells. These results suggest that the FOXL2 402C>G mutation may contribute to the development of human adult-type GCTs by reducing the expression of GnRH receptor, thus conferring resistance to GnRH-induced cell apoptosis.
    PLoS ONE 01/2013; 8(1):e55099. · 3.53 Impact Factor
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    Jung-Chien Cheng, Christian Klausen, Peter C K Leung
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    ABSTRACT: Hypoxia-inducible factor 1α (HIF-1α) regulates the transcription of a number of genes under hypoxia and other extracellular stimulations. It has been shown that E-cadherin is down-regulated by epidermal growth factor receptor (EGF) stimulation, and that cells with low E-cadherin expression are more invasive. Our recent study demonstrated a novel mechanism by which EGF down-regulates E-cadherin expression through production of hydrogen peroxide (H(2)O(2)) and the activation of p38 MAPK in human ovarian cancer cells. In this study, we were interested in examining the potential role of HIF-1 in cell invasion under normoxic conditions, specifically when cells are treated with EGF, which is known to down-regulate E-cadherin and increase invasiveness. We show that EGF treatment induces HIF-1α expression in two human ovarian cancer cell lines (SKOV3 and OVCAR5), and that this effect is diminished by treatment with a membrane-permeable H(2)O(2) scavenger, PEG-catalase. However, the induction of HIF-1α by EGF did not require the activation of p38 MAPK. Treatment with siRNA targeting HIF-1α reduces both basal and EGF-induced HIF-1α levels. Importantly, treatment with HIF-1α siRNA diminishes the up-regulation of Snail and Slug as well as the down-regulation of E-cadherin by EGF. The involvement of HIF-1α in the down-regulation of E-cadherin was confirmed with cobalt chloride (CoCl(2)), a hypoxia-mimetic reagent. Finally, we also show that EGF-induced cell invasion is attenuated by treatment with HIF-1α siRNA. This study demonstrates an important role for HIF-1α in mediating the effects of EGF on Snail, Slug and E-cadherin expression as well as invasiveness in human ovarian cancer cells.
    Cancer letters 11/2012; · 5.02 Impact Factor
  • Jung-Chien Cheng, Hsun-Ming Chang, Peter C K Leung
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    ABSTRACT: The loss of E-cadherin enhances cell invasiveness. There is increasing evidence that high-grade serous ovarian cancer may arise from oviductal epithelial cells rather than the ovarian surface epithelium. Despite the controversy over the cellular origins of this disease, the roles of epidermal growth factor (EGF) in human oviductal epithelial cells are largely unknown. We examined whether EGF could induce oviductal epithelial cell invasion by its down-regulation of E-cadherin. Matrigel-coated transwells were used for the invasion assay. Small interfering RNA was used to knock down the expression of EGF receptor (EGFR). Specific mRNA and protein levels were examined by quantitative RT-PCR and Western blot, respectively. The expression of Pax8 confirmed the secretory type of the cultured human oviductal epithelial cell line OE-E6/E7. EGFR was expressed in OE-E6/E7 cells, and treatment with EGF down-regulated E-cadherin expression. The effect of EGF on the down-regulation of E-cadherin was abolished by small interfering RNA-mediated depletion of EGFR. EGF treatment led to the activation of ERK1/2, p38, and Akt. Snail and Slug are transcriptional repressors of E-cadherin. Interestingly, our results show that EGF induced Slug but not Snail expression. Moreover, the inhibition of EGF-induced ERK1/2, p38, and Akt activation by pharmacological inhibitors attenuated EGF-induced Slug expression and the down-regulation of E-cadherin, as well as subsequent cell invasion. EGF induces human oviductal epithelial cell invasion through the activation of ERK1/2, p38, and Akt, the up-regulation of Slug, and the down-regulation of E-cadherin.
    The Journal of Clinical Endocrinology and Metabolism 05/2012; 97(8):E1380-9. · 6.31 Impact Factor
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    Jung-Chien Cheng, Nelly Auersperg, Peter C K Leung
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    ABSTRACT: Apoptosis in ovarian surface epithelial (OSE) cells is induced by transforming growth factor-beta (TGF-β). However, high-grade serous ovarian carcinomas (HGC) are refractory to the inhibitory functions of TGF-β; their invasiveness is up-regulated by TGF-β through epithelial-mesenchymal transition (EMT) activation. Serous borderline ovarian tumors (SBOT) have been recognized as distinct entities that give rise to invasive low-grade serous carcinomas (LGC), which have a relatively poor prognosis and are unrelated to HGC. While it is not fully understood how TGF-β plays disparate roles in OSE cells and its malignant derivative HGC, its role in SBOT and LGC remains unknown. Here we demonstrate the effects of TGF-β on cultured SBOT3.1 and LGC-derived MPSC1 cells, which express TGF-β type I and type II receptors. TGF-β treatment induced the invasiveness of SBOT3.1 cells but reduced the invasiveness of MPSC1 cells. The analysis of apoptosis, which was assessed by cleaved caspase-3 and trypan blue exclusion assay, revealed TGF-β-induced apoptosis in MPSC1, but not SBOT3.1 cells. The pro-apoptotic effect of TGF-β on LGC cells was confirmed in another immortalized LGC cell line ILGC. TGF-β treatment led to the activation of Smad3 but not Smad2. The specific TβRI inhibitor SB431542 and TβRI siRNA abolished the SBOT3.1 invasion induced by TGF-β, and it prevented TGF-β-induced apoptosis in MPSC1 cells. In SBOT3.1 cells, TGF-β down-regulated E-cadherin and concurrently up-regulated N-cadherin. TGF-β up-regulated the expression of the transcriptional repressors of E-cadherin, Snail, Slug, Twist and ZEB1. In contrast, co-treatment with SB431542 and TβRI depletion by siRNA abolished the effects of TGF-β on the relative cadherin expression levels and that of Snail, Slug, Twist and ZEB1 as well. This study demonstrates dual TGF-β functions: the induction of SBOT cell invasion by EMT activation and apoptosis promotion in LGC cells.
    PLoS ONE 01/2012; 7(8):e42436. · 3.53 Impact Factor
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    Jung-Chien Cheng, Nelly Auersperg, Peter C K Leung
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    ABSTRACT: In high-grade ovarian cancer cultures, it has been shown that epidermal growth factor (EGF) induces cell invasion by activating an epithelial-mesenchymal transition (EMT). However, the effect of EGF on serous borderline ovarian tumors (SBOT) and low-grade serous carcinomas (LGC) cell invasion remains unknown. Here, we show that EGF receptor (EGFR) was expressed, that EGF treatment increased cell migration and invasion in two cultured SBOT cell lines, SBOT3.1 and SV40 large T antigen-infected SBOT cells (SBOT4-LT), and in two cultured LGC cell lines, MPSC1 and SV40 LT/ST-immortalized LGC cells (ILGC). However, EGF induced down-regulation of E-cadherin and concurrent up-regulation of N-cadherin in SBOT cells but not in LGC cells. In SBOT cells, the expression of the transcriptional repressors of E-cadherin, Snail, Slug and ZEB1 were increased by EGF treatment. Treatment with EGF led to the activation of the downstream ERK1/2 and PI3K/Akt. The MEK1 inhibitor PD98059 diminished the EGF-induced cadherin switch and the up-regulation of Snail, Slug and ZEB1 and the EGF-mediated increase in SBOT cell migration and invasion. The PI3K inhibitor LY294002 had similar effects, but it could not block the EGF-induced up-regulation of N-cadherin and ZEB1. This study demonstrates that EGF induces SBOT cell migration and invasion by activating EMT, which involves the activation of the ERK1/2 and PI3K/Akt pathways and, subsequently, Snail, Slug and ZEB1 expression. Moreover, our results suggest that there are EMT-independent mechanisms that mediate the EGF-induced LGC cell migration and invasion.
    PLoS ONE 01/2012; 7(3):e34071. · 3.53 Impact Factor
  • Jung-Chien Cheng, Hsun-Ming Chang, Peter C K Leung
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    ABSTRACT: A major function of the p53 tumor suppressor is the regulation of the cell cycle and apoptosis. In addition to its well-documented functions in malignant cancer cells, p53 can also regulate cell migration and invasion, which contribute to metastasis. Growth differentiation factor-15 (GDF-15), a member of the TGF-β superfamily, has been shown to be a downstream target of p53 and is associated with diverse human diseases and cancer progression. In this study, we examined the potential role of GDF-15 in p53-regulated cancer cell motility. We show that overexpression of wild-type p53 in two highly invasive p53-null human cancer cell lines, SKOV3 and PC3, attenuated cell migration and the movement through Matrigel. Using wild-type p53 and DNA-binding-deficient p53 mutants, we found that the transcriptional activity of p53 is required in the induction of GDF-15 expression. Cell movement through uncoated and Matrigel-coated transwell decreased in response to treatment with recombinant GDF-15, whereas the cell proliferation was not affected by GDF-15 treatment. Moreover, the induction of GDF-15 expression and secretion by p53 and the reduction in cell movement through Matrigel were diminished by treatment with GDF-15 small interfering RNA. This study demonstrates a mechanism by which p53 attenuates cancer cell motility through GDF-15 expression. In addition, our results indicate that GDF-15 mediates the functions of p53 by autocrine/paracrine action.
    Endocrinology 05/2011; 152(8):2987-95. · 4.72 Impact Factor

Publication Stats

126 Citations
114.93 Total Impact Points

Institutions

  • 2008–2014
    • University of British Columbia - Vancouver
      • Department of Obstetrics and Gynaecology
      Vancouver, British Columbia, Canada
  • 2013
    • Government of British Columbia, Canada
      Vancouver, British Columbia, Canada
  • 2010–2013
    • Zhejiang University
      • School of Medicine
      Hang-hsien, Zhejiang Sheng, China