Papers by pier giorgio natali
Neoplasia, 2011
The nonclassic class I human leukocyte antigen E (HLA-E) molecule engages the inhibitory NKG2A re... more The nonclassic class I human leukocyte antigen E (HLA-E) molecule engages the inhibitory NKG2A receptor on several cytotoxic effectors, including natural killer (NK) cells. Its tissue distribution was claimed to be wider in normal than in neoplastic tissues, and surface HLA-E was undetectable in most tumor cell lines. Herein, these issues were reinvestigated taking advantage of HLA-E-specific antibodies, immunohistochemistry, and biochemical methods detecting intracellular and surface HLA-E regardless of conformation. Contrary to published evidence, HLA-E was detected in a few normal epithelia and in a large fraction (approximately 1/3) of solid tumors, including those derived from HLA-E-negative/low-normal counterparts. Remarkably, HLA-E was detected in 30 of 30 tumor cell lines representative of major lymphoid and nonlymphoid lineages, and in 11 of 11, it was surface-expressed, although in a conformation poorly reactive with commonly used antibodies. Coexpression of HLA-E and HLA class I ligand donors was not required for surface expression but was associated with NKG2A-mediated protection from lysis by the cytotoxic cell line NKL and polyclonal NK cells from healthy donors, as demonstrated by antibody-mediated relief of protection in 10% to 20% of the tested target-effector combinations. NKG2A-mediated protection of additional targets became evident on NK effector blocking with antibodies to activating receptors (DNAM-1, natural cytotoxicity receptors, and NKG2D). Thus, initial evidence that the long-elusive HLA-E molecule is enhanced by malignant transformation and is functional in tumor cells is presented here, although its importance and precise functional role remain to be addressed in the context of a general understanding of the NK ligand-receptor network.
Journal of translational medicine, Jan 27, 2004
The endotelin (ET) axis, that includes ET-1, ET-2, ET-3, and the ET receptors, ETA and ETB, plays... more The endotelin (ET) axis, that includes ET-1, ET-2, ET-3, and the ET receptors, ETA and ETB, plays an important physiological role, as modulator of vasomotor tone, tissue differentiation and development, cell proliferation, and hormone production. Recently, investigations into the role of the ET axis in mitogenesis, apoptosis inhibition, invasiveness, angiogenesis and bone remodeling have provided evidence of the importance of the ET-1 axis in cancer. Data suggest that ET-1 participates in the growth and progression of a variety of tumors such as prostatic, ovarian, renal, pulmonary, colorectal, cervical, breast carcinoma, Kaposi's sarcoma, brain tumors, melanoma, and bone metastases. ET-1 receptor antagonists beside providing ideal tools for dissecting the ET axis at molecular level have demonstrated their potential in developing novel therapeutic opportunity. The major relevance of ETA receptor in tumor development has led to an extensive search of highly selective antagonists....
Cancer research, Jan 15, 2003
The endothelin A receptor (ET(A)R) autocrine pathway is overexpressed in many malignancies, inclu... more The endothelin A receptor (ET(A)R) autocrine pathway is overexpressed in many malignancies, including ovarian carcinoma. In this tumor, engagement of ET(A)R triggers tumor growth, survival, neoangiogenesis, and invasion. To evaluate whether ET(A)R represents a new target in cancer treatment, we examine in vitro and in vivo the effect of the selective ET(A)R antagonist ABT-627 (atrasentan), a small p.o. bioavailable molecule, in mono- and combination therapy with taxane. ABT-627 effectively inhibits cell proliferation, vascular endothelial growth factor (VEGF) secretion of ovarian carcinoma cell lines, and primary cultures. ET(A)R blockade also results in the sensitization to paclitaxel-induced apoptosis. In ovarian carcinoma xenografts, in which the ET-1/ET(A)R autocrine pathway is overexpressed, tumor growth was significantly inhibited in ABT-627-treated mice compared with control. The therapeutic efficacy of ABT-627 was associated with a significant reduction in microvessel densit...
Cancer research, Jan 15, 2002
In human papillomavirus (HPV)-positive cervical cancer cells, the endothelin A receptor (ET(A)R) ... more In human papillomavirus (HPV)-positive cervical cancer cells, the endothelin A receptor (ET(A)R) mediates an endothelin-1-induced mitogenic effect, thus representing a relevant target for antitumor therapy. Here, we describe the complete inhibition of human cervix carcinoma growth by blocking the ET(A)R. In nude mice, the ET(A)R-selective antagonist atrasentan inhibits the growth and the neoangiogenesis of cervical carcinoma cell xenografts. Two cycles of treatment completely revert tumor growth. Atrasentan displays additive effects when administered in combination with the cytotoxic drug paclitaxel. These results demonstrate that by inhibiting cell proliferation and angiogenesis, this small molecule may help to control cervical cancer by either monotherapy or combination therapy.
Clinical science (London, England : 1979), 2002
Endothelin-1 (ET-1) is present at high concentrations in ovarian cancer ascites and is overexpres... more Endothelin-1 (ET-1) is present at high concentrations in ovarian cancer ascites and is overexpressed in primary and metastatic ovarian carcinomas. In these tumours the presence of ET-1 is associated with enhanced neovascularization and with vascular endothelial growth factor (VEGF) expression. In these tumour cells, ET-1 acts as an autocrine growth factor selectively through the receptor ET(A), which is predominantly expressed in tumour cells. Furthermore, ET-1 produced by ovarian tumour cells stimulates VEGF production and VEGF-mediated angiogenic effects through ET(A) binding. These results demonstrate that activation of the ET(A) in ovarian carcinoma cells promotes cell proliferation, neovascularization and invasion, which are the principal hallmarks of malignant transformation. The present study was designed to investigate the effects of the ET(A)-selective antagonist ABT-627 on the ET-1-induced mitogenic effect in both primary cultures (PMOV1 and PMOV2) and cell lines (OVCA 433...
Cancer research, Jan 15, 2001
Endothelin-1 (ET-1) is present at high concentrations in ovarian cancer ascites and is overexpres... more Endothelin-1 (ET-1) is present at high concentrations in ovarian cancer ascites and is overexpressed in primary and metastatic ovarian carcinoma. In these cells, ET-1 acts as an autocrine mitogenic and angiogenic factor selectively through the ET(A) receptor (ET(A)R). We investigated at mRNA and protein levels whether ET-1 could affect the expression and activation of metastasis-related proteinases and whether this process was associated with ovarian tumor cell invasion. ELISA, gelatin zymography, Western blot, and reverse transcription-PCR analyses demonstrated that in two ovarian carcinoma cell lines (HEY and OVCA 433), the expression of matrix metalloproteinase (MMP) -2, -9, -3, -7, and -13 was up-regulated and activated by ET-1. Moreover we observed that ET-1 was able to enhance the secretion and activation of membrane-type metalloproteinase-1, a critical mediator of invasiveness. The secretion of tissue inhibitor of metalloproteinase-1 and -2 was decreased by ET-1, which increa...
Clinical cancer research : an official journal of the American Association for Cancer Research, 2000
Increasing evidence suggests that endoglin (CD105) is a new powerful marker of neovascularization... more Increasing evidence suggests that endoglin (CD105) is a new powerful marker of neovascularization in solid malignancies; thus, using breast cancer as a model, we investigated whether targeting of CD105 by monoclonal antibody (mAb) MAEND3 can be used for in vivo imaging of solid tumors. Immunohistochemistry and flow cytometry identified differential expression of CD105 on breast cancer and endothelial cells; in fact, neoplastic cells were weakly and rarely stained by mAb MAEND3, which in contrast, strongly and invariably stained blood vessel endothelia within the breast adenocarcinomas investigated and cultured endothelial cells. Moreover, in contrast to CD31, which currently represents the reference marker to assess angiogenetic activity, CD105 expression was highest in semiconfluent and actively proliferating endothelial cells, and it progressively decreased as cells reached tight confluency and low [3H]thymidine uptake. i.v. administration of 18 MBq of 125I-labeled mAb MAEND3 effi...
Cancer Research, 2014
The high mortality of epithelial ovarian cancer (EOC) is mainly caused by resistance to the avail... more The high mortality of epithelial ovarian cancer (EOC) is mainly caused by resistance to the available therapies. In EOC, the endothelin-1 (ET-1, EDN1)–endothelin A receptor (ETAR, EDNRA) signaling axis regulates the epithelial–mesenchymal transition (EMT) and a chemoresistant phenotype. However, there is a paucity of knowledge about how ET-1 mediates drug resistance. Here, we define a novel bypass mechanism through which ETAR/β-arrestin-1 (β-arr1, ARRB1) links Wnt signaling to acquire chemoresistant and EMT phenotype. We found that ETAR/β-arr1 activity promoted nuclear complex with β-catenin and p300, resulting in histone acetylation, chromatin reorganization, and enhanced transcription of genes, such as ET-1, enhancing the network that sustains chemoresistance. Silencing of β-arr1 or pharmacologic treatment with the dual ETAR/ETBR antagonist macitentan prevented core complex formation and restored drug sensitivity, impairing the signaling pathways involved in cell survival, EMT, an...
Proceedings of the National Academy of Sciences, 2009
The activation of endothelin-A receptor (ET A R) by endothelin-1 (ET-1) has a critical role in ov... more The activation of endothelin-A receptor (ET A R) by endothelin-1 (ET-1) has a critical role in ovarian tumorigenesis and progression. To define the molecular mechanism in ET-1-induced tumor invasion and metastasis, we focused on β-arrestins as scaffold and signaling proteins of G protein-coupled receptors. Here, we demonstrate that, in ovarian cancer cells, β-arrestin is recruited to ET A R to form two trimeric complexes: one through the interaction with Src leading to epithelial growth factor receptor (EGFR) transactivation and β-catenin Tyr phosphorylation, and the second through the physical association with axin, contributing to release and inactivation of glycogen synthase kinase (GSK)-3β and β-catenin stabilization. The engagement of β-arrestin in these two signaling complexes concurs to activate β-catenin signaling pathways. We then demonstrate that silencing of both β-arrestin-1 and β-arrestin-2 inhibits ET A R-driven signaling, causing suppression of Src, mitogen-activated ...
PLoS ONE, 2010
Background: The endothelin B receptor (ET B R) promotes tumorigenesis and melanoma progression th... more Background: The endothelin B receptor (ET B R) promotes tumorigenesis and melanoma progression through activation by endothelin (ET)-1, thus representing a promising therapeutic target. The stability of hypoxia-inducible factor (HIF)-1a is essential for melanomagenesis and progression, and is controlled by site-specific hydroxylation carried out by HIF-prolyl hydroxylase domain (PHD) and subsequent proteosomal degradation.
Molecular Cancer Therapeutics, 2007
The autocrine endothelin (ET)-1/endothelin A receptor (ETAR) pathway is an important regulator of... more The autocrine endothelin (ET)-1/endothelin A receptor (ETAR) pathway is an important regulator of several processes involved in ovarian cancer progression, and its overexpression is associated with aggressive disease. These features have led to the proposal of the ETAR receptor as a potential target for improving ovarian cancer treatment. In this study, we evaluated in vitro and in vivo the effects of ZD4054, an orally active antagonist that specifically binds ETAR, as monotherapy, and in combination with paclitaxel. In the human ovarian cancer ETAR-positive cell lines HEY, OVCA 433, SKOV-3, and A-2780, ZD4054 effectively inhibited the basal and ET-1–induced cell proliferation, associated with the inhibition of AKT and p42/44MAPK phosphorylation, and with increased apoptosis, through the inhibition of bcl-2 and activation of caspase-3 and poly(ADP-ribose) polymerase proteins. ZD4054 treatment also resulted in a reduction of ETAR-driven angiogenesis and invasive mediators, such as va...
Journal of Cardiovascular Pharmacology, 2004
Ovarian carcinoma cells release high amounts of endothelin-1 and exhibit increased expression of ... more Ovarian carcinoma cells release high amounts of endothelin-1 and exhibit increased expression of endothelin-A receptor. Engagement of the endothelin-A receptor triggers tumor growth, survival, neoangiogenesis and invasion. Cyclooxygenase-1 and cyclooxygenase-2 are enzymes involved in the production of prostaglandins and play a role in the regulation of tumor progression in several malignancies, including ovarian carcinomas. Endothelin-1 significantly increases the expression of cyclooxygenase-1 and cyclooxygenase-2 mRNA and protein, the activity of the cyclooxygenase-2 promoter, and the release of prostaglandin E 2 from two ovarian carcinoma cell lines, HEY and OVCA 433. The cyclooxygenase-2 inhibitor, NS-398 drastically decreased the endothelin-1-induced prostaglandin E 2 production and vascular endothelial growth factor upregulation, indicating a role for cyclooxygenase-2 in endothelin-1-induced vascular endothelial growth factormediated angiogenesis. In this study we demonstrated that endothelin-1-induced cyclooxygenase-2 and related prostaglandin E 2 release were dependent upon the activation of endothelin-A receptor and of multiple mitogen-activated protein kinase signal pathways, including extracellular signal-regulated kinase 1/2 kinase, p38 mitogen-activated protein kinase and the transactivation of the epidermal growth factor receptor. In human ovarian xenografts, the levels of cyclooxygenase-2 protein expression were significantly reduced following treatment with the endothelin-A receptor selective antagonist, atrasentan, compared with untreated mice. These results suggest that the pharmacological blocking of endothelin-A receptor is an attractive strategy to control the cyclooxygenase-2 protein expression in ovarian carcinoma.
Journal of Biological Chemistry, 2004
Cyclooxygenase (COX)-1-and COX-2-derived prostaglandins are implicated in the development and pro... more Cyclooxygenase (COX)-1-and COX-2-derived prostaglandins are implicated in the development and progression of several malignancies. We have recently demonstrated that treatment of ovarian carcinoma cells with endothelin-1 (ET-1) induces expression of both COX-1 and COX-2, which contributes to vascular endothelial growth factor (VEGF) production. In this study, we show that in HEY and OVCA 433 ovarian carcinoma cells, ET-1, through the binding with ET A receptor (ET A R), induces prostaglandin E2 (PGE 2) production, as the more represented PG types, and increases the expression of PGE 2 receptor type 2 (EP2) and type 4 (EP4). The use of pharmacological EP agonists and antagonists indicates that ET-1 and PGE 2 stimulate VEGF production principally through EP2 and EP4 receptors. At the mechanistic level, we prove that the induction of PGE 2 and VEGF by ET-1 involves Src-mediated epidermal growth factor receptor transactivation. Finally, we demonstrate that ET A R-mediated activation of PGE 2dependent signaling participates in the regulation of the invasive behavior of ovarian carcinoma cells by activating tumor-associated matrix metalloproteinase. These results implicate EP2 and EP4 receptors in the induction of VEGF expression and cell invasiveness by ET-1 and provide a mechanism by which ET A R/ET-1 can promote and interact with PGE 2-dependent machinery to amplify its proangiogenic and invasive phenotype in ovarian carcinoma cells. Pharmacological blockade of ET A R can therefore represent an additional strategy to control PGE 2 signaling, which has been associated with ovarian carcinoma progression. Cyclooxygenase (COX) 1 is the rate-limiting enzyme for the conversion of arachidonic acid to prostaglandins (PG), which * This work was supported by grants from the Associazione Italiana Ricerca sul Cancro, the Ministero della Salute, and from MIUR-Consiglio Nazionale delle Ricerche. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. § Recipient of fellowship from Fondazione Italiana Ricerca sul Cancro.
Journal of Biological Chemistry, 2003
Endothelin-1 (ET-1) is overexpressed in ovarian carcinoma and acts as an autocrine factor selecti... more Endothelin-1 (ET-1) is overexpressed in ovarian carcinoma and acts as an autocrine factor selectively through the ET A receptor (ET A R) to promote tumor cell proliferation, survival, neovascularization, and invasiveness. Loss of gap junctional intercellular communication (GJIC) is critical for tumor progression by allowing the cells to escape growth control. Exposure of HEY and OVCA 433 ovarian carcinoma cell lines to ET-1 led to a 50-75% inhibition in intercellular communication and to a decrease in the connexin 43 (Cx43)-based gap junction plaques. To investigate the phosphorylation state of Cx43, ovarian carcinoma cell lysates were immunoprecipitated and transient tyrosine phosphorylation of Cx43 was detected in ET-1-treated cells. BQ 123, a selective ET A R antagonist, blocked the ET-1-induced Cx43 phosphorylation and cellular uncoupling. Gap junction closure was prevented by tyrphostin 25 and by the selective c-Src inhibitor, PP2. Furthermore, the increased Cx43 tyrosine phosphorylation was correlated with ET-1-induced increase of c-Src activity, and PP2 suppressed the ET-1-induced Cx43 tyrosine phosphorylation, indicating that inhibition of Cx43-based GJIC is mainly mediated by the Src tyrosine kinase pathway. In vivo, the inhibition of human ovarian tumor growth in nude mice induced by the potent ET A R antagonist, ABT-627, was associated with a reduction of Cx43 phosphorylation. These findings indicate that the signaling mechanisms involved in GJIC disruption on ovarian carcinoma cells depend on ET A R activation, which leads to the Cx43 tyrosine phosphorylation mediated by c-Src, suggesting that ET A R blockade may contribute to the control of ovarian carcinoma growth and progression also by preventing the loss of GJIC.
Cancer Research, 2004
Phenotypic and genotypic analyses of cutaneous melanoma have identified the endothelin B receptor... more Phenotypic and genotypic analyses of cutaneous melanoma have identified the endothelin B receptor (ETBR) as tumor progression marker, thus representing a potential therapeutic target. Here, we demonstrate that activation of ETBR by endothelin-1 (ET-1) and ET-3 leads to loss of expression of the cell adhesion molecule E-cadherin and associated catenin proteins and gain of N-cadherin expression. Exposure of melanoma cells to ET-1 leads to a 60% inhibition in intercellular communication by inducing phosphorylation of gap junctional protein connexin 43. Additionally, activation of the ETBR pathway increases αvβ3 and α2β1 integrin expression and matrix metalloproteinase (MMP)-2 and MMP-9, membrane type-1-MMP activation, and tissue inhibitor MMP-2 secretion. The ETBR pathway results into the downstream activation of focal adhesion kinase and extracellular signal-regulated kinase 1/2 signaling pathways, which lead to enhanced cell proliferation, adhesion, migration, and MMP-dependent invas...
Cancer Research, 2007
Endothelin (ET) B receptor (ETBR), which is overexpressed in human cutaneous melanomas, promotes ... more Endothelin (ET) B receptor (ETBR), which is overexpressed in human cutaneous melanomas, promotes tumorigenesis upon activation by ET-1 or ET-3, thus representing a potential novel therapeutic target. Hypoxia-inducible factor-1α (HIF-1α) is the transcriptional factor that conveys signaling elicited by hypoxia and growth factor receptors. Here, we investigated the interplay between ET axis and hypoxia in primary and metastatic melanoma cell lines. We report that under normoxic conditions, ETBR activation by ET-1/ET-3 enhances vascular endothelial growth factor (VEGF) up-regulation, cyclooxygenase (COX)-1/COX-2 protein expression and COX-2 promoter activity, prostaglandin E2 (PGE2) production, and do so to a greater extent under hypoxia. Moreover, COX-1/COX-2 inhibitors block ET-induced PGE2 and VEGF secretion, matrix metalloproteinase (MMP) activation, and cell invasion, indicating that both enzymes function as downstream mediators of ET-induced invasive properties. The ETBR selective...
Cancer Research, 2009
The lymphatic vasculature is essential for tissue fluid homeostasis and cancer metastasis, althou... more The lymphatic vasculature is essential for tissue fluid homeostasis and cancer metastasis, although the molecular mechanisms involved remain poorly characterized. Endothelin-1 (ET-1) axis plays a crucial role in angiogenesis and tumorigenesis. Here, we first report that ET-1 acts as a lymphangiogenic mediator. We performed in vitro and in vivo studies and show that lymphatic endothelial cells produce ET-1, ET-3, and express the endothelin B receptor (ETBR). In these cells, ET-1 promotes proliferation, invasiveness, vascular-like structures formation, and phosphorylation of AKT and p42/44 mitogen-activated protein kinase through ETBR. In normoxic conditions, ET-1 is also able to up-regulate the expression of vascular endothelial growth factor (VEGF)-C, VEGF receptor-3, and VEGF-A, and to stimulate hypoxia-inducible factor (HIF)-1α expression similarly to hypoxia. Moreover, HIF-1α silencing by siRNA desensitizes VEGF-C and VEGF-A production in response to ET-1 or hypoxia, implicating ...
Cancer Research, 2005
Despite considerable efforts to improve early detection and advances in chemotherapy, metastatic ... more Despite considerable efforts to improve early detection and advances in chemotherapy, metastatic relapses remain a major challenge in the management of ovarian cancer. The endothelin A receptor (ETAR)/endothelin-1 (ET-1) axis has been shown to have a significant role in ovarian carcinoma by promoting tumorigenesis. Here we show that the ET-1/ETAR autocrine pathway drives epithelial-to-mesenchymal transition (EMT) in ovarian tumor cells by inducing a fibroblastoid and invasive phenotype, down-regulation of E-cadherin, increased levels of β-catenin, Snail, and other mesenchymal markers, and suppression of E-cadherin promoter activity. Activation of ETAR by ET-1 triggers an integrin-linked kinase (ILK)–mediated signaling pathway leading to glycogen synthase kinase-3β (GSK-3β) inhibition, Snail and β-catenin stabilization, and regulation of transcriptional programs that control EMT. Transfection of dominant negative ILK or exposure to an ILK inhibitor suppresses the ET-1-induced phospho...
BMC Cell Biology, 2010
Background: Vascular smooth muscle cell migration and accumulation in response to growth factors ... more Background: Vascular smooth muscle cell migration and accumulation in response to growth factors extensively contribute to the development of intimal thickening within the vessel wall. Cumulative evidence has shown that actin cytoskeleton polymerization and rearrangement are critical steps during cellular spreading and migration. Integrin-linked kinase, an intracellular serine/threonine kinase, is a cytoplasmic interactor of integrin beta-1 and beta-3 receptors regulating cell-cell and/or cell-extracellular matrix interaction, cell contraction, extracellular matrix modification, and cell spreading and migration in response to various stimuli. However, the regulatory role of ILK during vascular smooth muscle cell migration and the importance of integrin signaling in occlusive vascular diseases are not yet fully elucidated. Results: In the present study, we report that integrin-linked kinase controls mouse aortic smooth muscle cell migration in response to platelet-derived growth factor. We have also identified p38 mitogen activated protein kinase as a downstream signaling pathway of the integrin-linked kinase that regulates platelet-derived growth factor-induced actin polymerization and smooth muscle cell migration. Conclusion: This study will provide new insights into the potential therapeutic value of modulating integrin signaling in an attempt to block or delay smooth muscle cell migration and the progression of vascular diseases.
The American Journal of Pathology, 2001
are recipients of fellowships from Fondazione Italiana Ricerca sul Cancro.
Uploads
Papers by pier giorgio natali