A genome-wide association study identifies new susceptibility loci for esophageal adenocarcinoma and Barrett's esophagus.

Esophageal adenocarcinoma is a cancer with rising incidence and poor survival. Most such cancers arise in a specialized intestinal metaplastic epithelium, which is diagnostic of Barrett's esophagus. In a genome-wide association study, we compared esophageal adenocarcinoma cases (n = 2,390) and individuals with precancerous Barrett's esophagus (n = 3,175) with 10,120 controls in 2 phases. For the combined case group, we identified three new associations. The first is at 19p13 (rs10419226: P = 3.6 × 10(-10)) in CRTC1 (encoding CREB-regulated transcription coactivator), whose aberrant activation has been associated with oncogenic activity. A second is at 9q22 (rs11789015: P = 1.0 × 10(-9)) in BARX1, which encodes a transcription factor important in esophageal specification. A third is at 3p14 (rs2687201: P = 5.5 × 10(-9)) near the transcription factor FOXP1, which regulates esophageal development. We also refine a previously reported association with Barrett's esophagus near the putative tumor suppressor gene FOXF1 at 16q24 and extend our findings to now include esophageal adenocarcinoma

Gonadotropin-releasing hormone: GnRH receptor signaling in extrapituitary tissues

Gonadotropin-releasing hormone (GnRH) has historically been known as a pituitary hormone; however, in the past few years, interest has been raised in locally produced, extrapituitary GnRH. GnRH receptor (GnRHR) was found to be expressed in normal human reproductive tissues (e.g. breast, endometrium, ovary, and prostate) and tumors derived from these tissues. Numerous studies have provided evidence for a role of GnRH in cell proliferation. More recently, we and others have reported a novel role for GnRH in other aspects of tumor progression, such as metastasis and angiogenesis. The multiple actions of GnRH could be linked to the divergence of signaling pathways that are activated by GnRHR. Recent observations also demonstrate cross-talk between GnRHR and growth factor receptors. Intriguingly, the classical Gαq-11- phospholipase C signal transduction pathway, known to function in pituitary gonadotropes, is not involved in GnRH actions at nonpituitary targets. Herein, we review the key findings on the role of GnRH in the control of tumor growth, progression, and dissemination. The emerging role of GnRHR in actin cytoskeleton remodeling (small Rho GTPases), expression and/or activity of adhesion molecules (integrins), proteolytic enzymes (matrix metalloproteinases) and angiogenic factors is explored. The signal transduction mechanisms of GnRHR in mediating these activities is described. Finally, we discuss how a common GnRHR may mediate different, even opposite, responses to GnRH in the same tissue/cell type and whether an additional receptor(s) for GnRH exists. © 2008 The Authors.link_to_subscribed_fulltex

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 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

P-cadherin cooperates with insulin-like growth factor-1 receptor to promote metastatic signaling of gonadotropin-releasing hormone in ovarian cancer via p120 catenin

Gonadotropin-releasing hormone (GnRH) is a potent prometastatic factor in ovarian cancer, but the intracellular signaling events are not well understood. The classical Gα q-phospholipase C signal transduction pathway known to operate in the pituitary is not involved in GnRH actions at non-pituitary targets. Here we showed that GnRH treatment of ovarian cancer cells led to a rapid and remarkable tyrosine phosphorylation of p120 catenin (p120 ctn), which was mediated by P-cadherin. The use of P-cadherin small interfering RNA or neutralizing antibodies to inhibit P-cadherin expression and function resulted in diminished p120 ctn activation, confirming that the effect was P-cadherin specific. On exploring how P-cadherin, which lacks intrinsic kinase activity, might regulate the activation of p120 ctn, we found that P-cadherin could induce the ligand-independent activation of insulin-like growth factor-1 receptor (IGF-1R). Inhibition of IGF-1R expression or its activity significantly inhibited GnRH-induced p120 ctn activation, and the subsequent cell migration and invasion. In addition, we showed that IGF-1R regulation by P-cadherin was associated with complex formation between IGF-1R and P-cadherin, and this regulation was also observed to be in vivo correlated with metastasis. Furthermore, using a mouse model of ovarian cancer metastasis, GnRH receptor knockdown was shown to diminish peritoneal dissemination of tumors and ascites formation. These findings suggest for the first time that GnRH can initiate an outside-in p120 ctn signal transduction through the cross-talk between P-cadherin and IGF-1R, thus providing a novel molecular mechanism by which GnRH may control the high level of aggressiveness and invasion and metastasis potential that are characteristic of ovarian cancer. © 2011 Macmillan Publishers Limited All rights reserved.link_to_subscribed_fulltex

Pigment epithelium-derived factor is estrogen sensitive and inhibits the growth of human ovarian cancer and ovarian surface epithelial cells

Epithelial ovarian carcinoma is the most lethal gynecological cancer. However, little is known about the molecular mechanisms underlying the disease development and progression. In this study, we found that the expression of pigment epithelium-derived factor (PEDF) was greatly reduced in ovarian tumors and in ovarian cancer cell lines when compared with their normal precursor, ovarian surface epithelium (OSE). In addition, we showed that exogenous PEDF inhibited the growth of cultured human OSE as well as ovarian cancer cell lines, whereas targeted inhibition of endogenous PEDF using small interfering RNA or neutralizing PEDF antibody promoted the growth of these cells, confirming that the growth-inhibitory effect was PEDF specific. We also report for the first time that estrogen is an important upstream regulator of PEDF in human OSE. Treatment of the cultured cells with 17β-estradiol (E 2) inhibited the expression of PEDF protein and mRNA in a dose- and time-dependent manner, which could be reversed by the specific estrogen receptor antagonist, ICI 182,780, indicating that the regulation was estrogen receptor-mediated. We further showed that this down-regulation of PEDF gene transcription was a direct, primary effect of E 2. E 2 promoted OSE and ovarian cancer cell growth, whereas simultaneous treatment with E 2 and PEDF abrogated the estrogenic growth stimulation of these cells. This study is the first to demonstrate a role of PEDF in OSE biology and ovarian cancer and suggests that the loss of PEDF may e of relevance in carcinogenesis. Copyright © 2006 by The Endocrine Society.link_to_subscribed_fulltex

Exposure to light at night (LAN) and risk of breast cancer: a systematic review and meta-analysis

BACKGROUND: With the unprecedented urbanization light pollution is a ubiquitous problem, with accumulating evidence on the links between exposure to light at night (LAN) and breast cancer risk. We conducted a systematic review and meta-analysis of published studies on the associations between LAN exposure and breast cancer risk. METHODS: We included all observational human studies wherein the exposure variable was LAN measured in indoor and outdoor environments, and the outcome was breast cancer. We employed summary relative risks (SRR) for breast cancer by comparing highest versus lowest categories of LAN exposure within a random-effects model. The National Toxicology Program’s (NTP) Office of Health Assessment and Translation (OHAT) risk of bias rating tool was adopted to assess the risk of bias in individual studies and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) guideline was employed to assess confidence in the body of evidence. RESULTS:A total 14 studies comprising four cohorts (13 155 cases among 414 000 exposed subjects), nine case-control and one case-referent studies of female subjects (39 757 cases and 21 541 controls) across seven countries and published between 2001-20 were included for review. Participants in the highest LAN exposure category were associated with higher risk of breast cancer in reference to those in the lowest (SRR: 1.12; 95% CI: 1.06-1.18; I2 = 39% for outdoor LAN, and SRR: 1.13; 95%CI: 1.05-1.21; I2 = 19% for indoor LAN). Pooled evidence identified relatively pronounced association of outdoor LAN exposure and breast cancer among women with estrogen receptor positive (ER+) tumor (SRR: 1.21; 95% CI: 1.04-1.40) and premenopausal status (SRR: 1.21; 95% CI: 1.06-1.37). The final rate of confidence in the body of evidence generated was graded as ‘moderate’ based on GRADE guideline. DISCUSSION: LAN exposure was consistently associated with higher breast cancer risk corroborating NTP’s recommendations which anticipates excessive LAN as human carcinogen.</p