Motor neuron disease in Hong Kong Chinese: Epidemiology and clinical picture

This study documents the clinical features, incidence and prevalence of motor neuron disease (MND) in Hong Kong Chinese. Patients with MND who were alive between 1989 and 1992 were recruited by retrieval of medical records from the four major hospitals in Hong Kong, and by referral of neurologists, neurosurgeons and medical consultants. Mortality statistics was provided by the Census and Statistics Department. A total of 84 cases were identified with a male preponderance of 1.98:1. The average annual period incidence was 0.31/100,000 and the point prevalence on December 31, 1992, was 0.95/100,000. The mean age at onset was 55.5 years (range 19-81) with a peak observed from 55 to 65 years. The clinical features are similar to other reported series of MND. The incidence and mortality of MND in Hong Kong are therefore lower than the worldwide figures of 2.0/100,000 and 1.5/100,000, respectively.published_or_final_versio

A breakthrough on Amanita phalloides poisoning: an effective antidotal effect by polymyxin B

Amanita phalloides is responsible for more than 90 % of mushroom-related fatalities, and no effective antidote is available. a-Amanitin, the main toxin of A. phalloides, inhibits RNA polymerase II (RNAP II), causing hepatic and kidney failure. In silico studies included docking and molecular dynamics simulation coupled to molecular mechanics with generalized Born and surface area method energy decomposition on RNAP II. They were performed with a clinical drug that shares chemical similarities to a-amanitin, polymyxin B. The results show that polymyxin B potentially binds to RNAP II in the same interface of a-amanitin, preventing the toxin from binding to RNAP II. In vivo, the inhibition of the mRNA transcripts elicited by a-amanitin was efficiently reverted by polymyxin B in the kidneys. Moreover, polymyxin B significantly decreased the hepatic and renal a-amanitin-induced injury as seen by the histology and hepatic aminotransferases plasma data. In the survival assay, all animals exposed to a-amanitin died within 5 days, whereas 50 % survived up to 30 days when polymyxin B was administered 4, 8, and 12 h post-a-amanitin. Moreover, a single dose of polymyxin B administered concomitantly with a-amanitin was able to guarantee 100 % survival. Polymyxin B protects RNAP II from inactivation leading to an effective prevention of organ damage and increasing survival in a-amanitin-treated animals. The present use of clinically relevant concentrations of an already human-use-approved drug prompts the use of polymyxin B as an antidote for A. phalloides poisoning in humans.Juliana Garcia, Vera Marisa Costa, Ricardo Dinis-Oliveira and Ricardo Silvestre thank FCT-Foundation for Science and Technology-for their PhD grant (SFRH/BD/74979/2010), Post-doc grants (SFRH/BPD/63746/2009 and SFRH/BPD/110001/2015) and Investigator grants (IF/01147/2013) and (IF/00021/2014), respectively. This work was supported by the Fundacao para a Ciencia e Tecnologia (FCT) - project PTDC/DTPFTO/4973/2014 - and the European Union (FEDER funds through COMPETE) and National Funds (FCT, Fundacao para a Ciencia e Tecnologia) through project Pest-C/EQB/LA0006/2013

GnRH enhances matrix metalloproteinases-dependent invasion of human ovarian cancer cells

Objectives: To investigate the contribution of GnRH in the invasive behavior of human ovarian cancer cells and to unveil the mechanism underlying this process. Methods: In vitro migration and cell invasion assays were performed with two human ovarian cancer cell lines CaOV-3 and OVCAR-3 in the presence of GnRH agonist. RT-PCR, Western blot, and gelatin zymography were used to investigate the effect of GnRH on metastasis-related proteinases, matrix metalloproteinase (MMP)-2 and MMP-9. The signaling pathway involved was identified by using specific small molecule inhibitors and dominant negative mutants. Results: The in vitro assays revealed a biphasic nature of GnRH; low concentrations of GnRH agonist increased cell motility and invasiveness of CaOV-3 and OVCAR-3, but the stimulatory effect was insignificant at higher concentrations. Moreover, we demonstrated that expression and activation of MMP-2 and MMP-9 were functionally related to GnRH-mediated invasion, and this was through the c-Jun N-terminal kinase signaling pathway. Conclusion: These results suggest a novel role of GnRH signaling cascade in the invasive phenotype and motility of human ovarian cancer cells

GnRH promotes peritoneal adhesion and dissemination of ovarian cancer cells

Poster Session 14 - Growth Factor, Hormone, and Cytokine Signaling in Invasion: abstract no. 5190Ovarian cancer has the highest mortality of all gynecological cancers. It is often diagnosed at a late stage characterized by widespread peritoneal dissemination and malignant ascites. A key initial step in metastasis is the adhesion of ovarian cancer cells to the peritoneal mesothelium and extracellular matrix (ECM). Gonadotropin-releasing hormone (GnRH) receptor is present in 80% of ovarian carcinomas and its role in ovarian cancer cell migration/invasion has recently been revealed. Here, we show for the first time a role for GnRH in promoting ovarian cancer cell adhesion to the peritoneum. We observed that GnRH agonist (GnRHa)-stimulated cells were able to adhere to the peritoneal mesothelium efficiently. Moreover, the expression of integrins (α2, α5 and β1) in ECM recognition for collagen I, laminin, and fibronectin were upregulated and activated by GnRHa. The adhesion of ovarian cancer cells to the mesothelium/ECM components activated by GnRHa could be blocked by neutralizing antibodies to α2, α5 and β1 integrin. Knockdown of the GnRH receptor using small interfering RNA significantly abrogated the GnRH-induced cell adhesion and integrin expression, confirming that these effects were GnRH receptor specific. Furthermore, we showed that downregulation of β1 integrin and GnRH receptor with short hairpin RNA-mediated gene silencing significantly reduced ascites formation and intra-abdominal metastasis in intraperitoneal xenografts of human ovarian cancer in nude mice. These results indicate that GnRH may play a critical role in the peritoneal adhesion and dissemination of ovarian carcinomas and could be a promising target in ovarian cancer.link_to_OA_fulltextThe 101st Annual Meeting of the American Association for Cancer Research (AACR 2010), Washington D.C., 17-21 April 2010. In AACR Meeting Abstracts, 201

Cadherin switching and activation of p120 catenin signaling are mediators of gonadotropin-releasing hormone to promote tumor cell migration and invasion in ovarian cancer

Gonadotropin-releasing hormone (GnRH) receptor expression is often elevated in ovarian cancer, but its potential role in ovarian cancer metastasis has just begun to be revealed. Cadherin switching is a crucial step during tumorigenesis, particularly in metastasis. Here, we showed that GnRH is an inducer of E-to P-cadherin switching, which is reminiscent of that seen during ovarian tumor progression. Overexpression of P-cadherin significantly enhanced, whereas knockdown of P-cadherin reduced migration and invasion regardless of E-cadherin expression, suggesting that inappropriate expression of P-cadherin contributes to the invasive phenotype. These effects of P-cadherin were mediated by activation of the Rho GTPases, Rac1, and Cdc42, through accumulation of p120 catenin (p120 ctn) in the cytoplasm. The use of p120 ctn small interfering RNA or chimeric cadherin construct to inhibit p120 ctn expression and cytoplasmic localization, respectively, resulted in significant inhibition of cell migration and invasion, with a concomitant reduction in Rac1 and Cdc42 activation, confirming that the effect was p120 ctn specific. Similarly, the migratory/invasive phenotype could be reversed by expression of dominant-negative Rac1 and Cdc42. These results identify for the first time cadherin switching and p120 ctn signaling as important targets of GnRH function and as novel mediators of invasiveness and tumor progression in ovarian cancer. © 2010 Macmillan Publishers Limited All rights reserved.link_to_subscribed_fulltex

Gonadotropin-releasing hormone promotes motility and invasiveness of ovarian cancer cells through transactivation of the insulin-like growth factor-1 receptor

Ovarian cancer is the most lethal gynecological cancer with a dismal 5-year survival. This is because most ovarian cancer patients are diagnosed with already widespread metastasis and ascites, in which current therapies are ineffective. Gonadotropin-releasing hormone (GnRH) receptor is expressed in 80% of ovarian cancer. In addition to its well documented role in cell proliferation, our recent findings show an expanded role of GnRH in other aspects of ovarian tumor progression, such as cell migration and invasion. Here we report that these actions of GnRH were dependent on transactivation of the insulin-like growthfactor-1 (IGF-1) receptor. GnRH-induced migratory/invasive phenotypes were abolished by inhibition of the IGF-1 receptor, but not other receptor tyrosine kinases. GnRH significantly increased tyrosine phosphorylation of the IGF-1 receptor. Knocking down GnRH receptor by small interfering RNA was able to inhibit GnRH-induced IGF-1 receptor activation. Importantly, this transactivation caused rapid phosphorylation of the p120 catenin (p120ctn), which promoted translocation of p120ctn from membrane to cytosol and the subsequent activation of Rho GTPases Rac1 and Cdc42. RNA interference-mediated knockdown of p120ctn suppressed GnRH-stimulated migration and invasion of ovarian cancer cells, confirming that the effect was p120ctn specific. Expression of dominant negative mutants of Rac1 and Cdc42 also greatly reduced GnRH-mediated migration and invasion. These results show a novel crosstalk between GnRH and IGF-1 receptors in the proinvasive activity of GnRH in ovarian cancer cells and suggest potential benefits in the cotargeting of these pathways (This work is supported by Hong Kong Research Grants Council Grant HKU778108 to A.S.T.W.)

Gonadotropin-releasing hormone promotes ovarian cancer cell invasiveness through c-Jun NH2-terminal kinase-mediated activation of matrix metalloproteinase (MMP)-2 and MMP-9

Gonadotropin-releasing hormone (GnRH) receptor is present in 80% of ovarian cancer, and numerous studies have provided evidence for a role of GnRH in cell proliferation. In this study, the effect of GnRH on the invasion potential of ovarian cancer cells was investigated. In vitro migration and cell invasion assays with the ovarian cancer cell lines Caov-3 and OVCAR-3 revealed the biphasic nature of GnRH; low concentrations of GnRH agonist (GnRHa) increased the cell motility and invasiveness of these cells, but at increased concentrations, the stimulatory effect was insignificant. Reverse transcription-PCR, Western blot, and gelatin zymography showed that the expression of metastasis-related proteinases, matrix metalloproteinase (MMP)-2 and MMP-9, was up-regulated and activated by GnRHa. Moreover, we observed that GnRHa was able to transactivate the MMP-2 and MMP-9 promoters. The invasive/migratory phenotype activated by GnRHa can be blocked by specific inhibitors or neutralizing antibodies to MMP-2 and MMP-9. Knockdown of the GnRH receptor using small interfering RNA significantly inhibited the GnRH-induced MMP activation, invasion, and migration. In addition, we showed that the c-Jun NH2-terminal kinase, but not extracellular signal-regulated kinase 1/2 or p38 mitogen-activated protein kinase, signaling pathway was critical for GnRH-mediated up-regulation of MMP, cell invasion, and motility. These results indicate for the first time an expanded role for GnRH in other aspects of ovarian tumor progression, such as metastasis, via activation of MMP and the subsequent increase in cell migration and invasion. ©2006 American Association for Cancer Research.link_to_subscribed_fulltex

Estrogen regulates snail and slug in the down-regulation of E-cadherin and induces metastatic potential of ovarian cancer cells through estrogen receptor α

Tumorigenesis is a multistep process involving dysregulated cell growth and metastasis. Considerable evidence implicates a mitogenic action of estrogen in early ovarian carcinogenesis. In contrast, its influence in the metastatic cascade of ovarian tumor cells remains obscure. In the present study, we showed that 17β-estradiol (E2) increased the metastatic potential of human epithelial ovarian cancer cell lines. E2 treatment led to clear morphological changes characteristic of epithelial-mesenchymal transition (EMT) and an enhanced cell migratory propensity. These morphological and functional alterations were associated with changes in the abundance of EMT-related genes. Upon E2 stimulation, expression and promoter activity of the epithelial marker E-cadherin were strikingly suppressed, whereas EMT-associated transcription factors, Snail and Slug, were significantly up-regulated. This up-regulation was attributed to the increase in gene transcription activated by E2. Depletion of endogenous Snail or Slug using small interfering RNA (siRNA) attenuated E2-mediated decrease in E-cadherin. In addition, E2-induced cell migration was also neutralized by the siRNAs, suggesting that both transcription factors are indispensable for the prometastatic actions of E2. More importantly, by using selective estrogen receptor (ER) agonists, forced expression, and siRNA approaches, we identified that E2 triggered the metastatic behaviors exclusively through an ERα-dependent pathway. We also showed that ERβ had an opposing action on ERα because the presence of ERβ completely inhibited the EMT and down-regulation of E-cadherin induced by ERα. Collectively, this study provides a compelling argument that estrogen can potentiate tumor progression by EMT induction and highlights the crucial role of ERα in ovarian tumorigenesis. Copyright © 2008 by The Endocrine Society.link_to_subscribed_fulltex