151
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Abstract
The PI-3 kinase pathway is a major driving force for human cancer. One common way of stimulating the PI-3 kinase pathway occurs through inactivation of the PTEN tumor suppressor. The mechanisms of PTEN inactivation include mutation, epigenetic silencing and post-translational modification. Improved insight into the regulation of PTEN is leading to a richer understanding of the contribution of PTEN and the PI-3 kinase pathway to human tumors. Understanding the pathology of PI-3 kinase signaling in tumors improves knowledge of cancer etiology and provides novel therapeutic targets.
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Affiliation(s)
- Ramon Parsons
- Department of Pathology and Medicine, Institute for Cancer Genetics, Columbia University, 1150 St. Nicholas Avenue, RBP 302, New York, NY, USA.
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152
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Matei D, Chang DD, Jeng MH. Imatinib mesylate (Gleevec) inhibits ovarian cancer cell growth through a mechanism dependent on platelet-derived growth factor receptor alpha and Akt inactivation. Clin Cancer Res 2004; 10:681-90. [PMID: 14760091 DOI: 10.1158/1078-0432.ccr-0754-03] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE We identified the platelet-derived growth factor receptor alpha (PDGFRalpha) as an ovarian cancer-specific gene by microarray hybridization using primary cultures. The purpose of this study is to evaluate whether disruption of the platelet-derived growth factor-regulated growth pathway by Imatinib mesylate (Gleevec), a partially selective PDGFR inhibitor, inhibits growth of ovarian cancer cells expressing PDGFR. EXPERIMENTAL DESIGN To investigate the effects of Imatinib mesylate in ovarian cancer, we established an in vitro model by immortalizing primary ovarian cells, which express endogenous PDGFR, and we evaluated the effects of Imatinib on cell proliferation. In addition, we investigated the involvement of Akt in mediating Imatinib-inhibited cell growth inhibition. RESULTS We found that 39% of ovarian tumors express PDGFR by immunohistochemistry. We showed that Imatinib inhibits the growth of ovarian cancer cells in a PDGFR-specific manner, at clinically relevant concentrations (IC(50) < 1 micro M). Imatinib inhibits the growth of three primary ovarian cultures and two immortalized cultures (PDGFR positive), but has no effects on SkOv3 and CaOv3 cell lines (PDGFR negative). Imatinib exerts antiproliferative effects by arresting cells at G(0)-G(1) and preventing progression through S phase. Imatinib inhibits both PDGFRalpha and Akt phosphorylation at a concentration of 1 micro M. Stable expression of constitutively active Akt induces partial resistance to PDGFR inhibition in ovarian cancer cells, as demonstrated by cell proliferation assay and cell cycle analysis. CONCLUSIONS Our data indicate that Imatinib mesylate inhibits the growth of ovarian cancer cells through PDGFR inactivation. In addition, our results suggest that constitutive Akt activation modulates sensitivity to Imatinib in ovarian cancer cells.
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Affiliation(s)
- Daniela Matei
- Department of Medicine, Walther Oncology Center, Indiana University Cancer Center, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA.
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153
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Bernardini M, Weberpals J, Squire JA. The use of cytogenetics in understanding ovarian cancer. Biomed Pharmacother 2004; 58:17-23. [PMID: 14739058 DOI: 10.1016/j.biopha.2003.11.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
The future of cancer research is no longer limited to epidemiological data and clinical management, but rather encompasses a new dimension of understanding, that involves genetics of the tumors themselves. This has been exemplified most prominently in hematological tumors where alterations at the DNA level have been found to play key roles in the pathophysiology, diagnosis, monitoring and prognosis of these tumors. It has been shown over the last 20 years that recurrent chromosomal rearrangements are strongly associated with the activation of oncogenes, acquisition of drug resistance and loss of tumor suppressor gene function. Chromosomal alterations have also been shown to characterize many solid tumors, including epithelial ovarian cancer [Cancer Res. 62 (2002) 3466; Cancer 91 (2001) 534; Genes Chromosomes Cancer 25 (1999) 290]. Despite these findings, however, there are currently few examples of specific cytogenetic studies that have contributed to the clinical management of solid tumors such as ovarian cancer. The limiting factor to date is the resolution of available techniques. With time, as the technology improves, so will our ability to focus on specific findings that may be applicable to future clinical management. The intention of this report is to familiarize the reader with the evolution of cytogenetic and molecular cytogenetic techniques used in the study of ovarian cancer, the early formulations from these studies and their use in answering specific clinical questions such as association with pathologic subtype, the relevance of drug resistance, the impact of BRCA mutations, and finally to guide the reader into the future of this ever growing field.
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Affiliation(s)
- M Bernardini
- Department of Laboratory Medicine and Pathobiology, Princess Margaret Hospital, 610 University Avenue, Room 9-721, Ont., Toronto, Canada M5G 2M9
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154
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Dupont J, Tanwar MK, Thaler HT, Fleisher M, Kauff N, Hensley ML, Sabbatini P, Anderson S, Aghajanian C, Holland EC, Spriggs DR. Early detection and prognosis of ovarian cancer using serum YKL-40. J Clin Oncol 2004; 22:3330-9. [PMID: 15310777 DOI: 10.1200/jco.2004.09.112] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
PURPOSE YKL-40 is a secreted glycoprotein (chitinase family). We compared YKL-40 with two ovarian cancer serum markers, CA125 and CA15-3, for the detection of early-stage ovarian cancer. MATERIALS AND METHODS Serum YKL-40 levels were assayed by enzyme-linked immunosorbent assay for 46 healthy subjects, 61 high-risk individuals, 33 patients with benign gynecologic processes, and 50 preoperative patients subsequently diagnosed with predominantly early-stage ovarian cancer. Serum CA125 and CA15-3 values were obtained. RESULTS Median YKL-40 level was 28 ng/mL (range, 15 to 166 ng/mL) for healthy subjects, 36 ng/mL (range, 9 to 69 ng/mL) for high-risk individuals without prior cancer, 44.5 ng/mL (range, 5 to 133 ng/mL) for high-risk patients with prior breast cancer, and 38 ng/mL (range, 5 to 67 ng/mL) for individuals with benign gynecologic processes (P = NS). Median preoperative YKL-40 level for ovarian cancer patients was 94 ng/mL (range, 17 to 517 ng/mL; P <.0001 compared with normal and high-risk). YKL-40 was elevated (>/= 62 ng/mL) in 36 (72%) of 50 patients compared with 23 (46%) of 50 and 13 (26%) of 50 patients for CA125 and CA15-3 (P <.008). Twenty (65%) of 31 early-stage patients had elevated serum YKL-40 levels compared with 11 (35%) of 31 and four (13%) of 31 patients for CA125 and CA15-3 (P =.039). YKL-40 levels increased with stage (P <.005), regardless of grade, histology, or patient age. Patients with early-stage tumors with YKL-40 values more than 80 ng/mL had a worse prognosis (71% recurrence v no recurrence [P =.034]). CONCLUSION YKL-40 may represent a novel marker for the detection of early-stage ovarian cancer. YKL-40 levels in early-stage patients may also predict disease recurrence and survival. The utility of YKL-40 in detection of early-stage ovarian cancer deserves further investigation.
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Affiliation(s)
- Jakob Dupont
- Developmental Chemotherapy Service, Department of Medicine, Memorial Sloan-Kettering Cancer Center, Howard 905, 1275 York Ave, New York, NY 10021, USA.
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155
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Santarosa M, Ashworth A. Haploinsufficiency for tumour suppressor genes: when you don't need to go all the way. Biochim Biophys Acta Rev Cancer 2004; 1654:105-22. [PMID: 15172699 DOI: 10.1016/j.bbcan.2004.01.001] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2003] [Accepted: 01/13/2004] [Indexed: 01/01/2023]
Abstract
Classical tumour suppressor genes are thought to require mutation or loss of both alleles to facilitate tumour progression. However, it has become clear over the last few years that for some genes, haploinsufficiency, which is loss of only one allele, may contribute to carcinogenesis. These effects can either be directly attributable to the reduction in gene dosage or may act in concert with other oncogenic or haploinsufficient events. Here we describe the genes that undergo this phenomenon and discuss possible mechanisms that allow haploinsufficiency to display a phenotype and facilitate the pathogenesis of cancer.
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Affiliation(s)
- Manuela Santarosa
- The Breakthrough Breast Cancer Research Centre, Institute of Cancer Research, 237 Fulham Road, London SW3 6JB, UK
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156
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Abstract
Genetic alterations targeting the PTEN tumor suppressor gene are among the most frequently noted somatic mutations in human cancers. Such lesions have been noted in cancers of the prostate and endometrium and in glioblastoma multiforme, among many others. Moreover, germline mutation of PTEN leads to the development of the related hereditary cancer predisposition syndromes, Cowden disease, and Bannayan-Zonana syndrome, wherein breast and thyroid cancer incidence is elevated. The protein product, PTEN, is a lipid phosphatase, the enzymatic activity of which primarily serves to remove phosphate groups from key intracellular phosphoinositide signaling molecules. This activity normally serves to restrict growth and survival signals by limiting activity of the phosphoinositide-3 kinase (PI3K) pathway. Multiple lines of evidence support the notion that this function is critical to the ability of PTEN to maintain cell homeostasis. Indeed, the absence of functional PTEN in cancer cells leads to constitutive activation of downstream components of the PI3K pathway including the Akt and mTOR kinases. In model organisms, inactivation of these kinases can reverse the effects of PTEN loss. These data raise the possibility that drugs targeting these kinases, or PI3K itself, might have significant therapeutic activity in PTEN-null cancers. Akt kinase inhibitors are still in development; however, as a first test of this hypothesis, phase I and phase II trials of inhibitors of mTOR, namely, rapamycin and rapamycin analogs are underway.
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Affiliation(s)
- Isabelle Sansal
- Department of Medical Oncology, Dana-Farber Cancer Institute, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, 44 Binney Street, Boston, MA 02115, USA
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157
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Moreno-Bueno G, Rodríguez-Perales S, Sánchez-Estévez C, Marcos R, Hardisson D, Cigudosa JC, Palacios J. Molecular alterations associated with cyclin D1 overexpression in endometrial cancer. Int J Cancer 2004; 110:194-200. [PMID: 15069681 DOI: 10.1002/ijc.20130] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Cyclin D1 is frequently overexpressed in human neoplasias by gene rearrangement and amplification. In addition, Ras, PTEN and beta-catenin appear to modulate cyclin D1 levels. Since the causes of cyclin D1 overexpression are poorly understood in EC, we investigated whether or not this alteration is due to cyclin D1 gene amplification or to RAS, PTEN and beta-catenin mutation. We analyzed cyclin D1 expression in 18 AEHs, 65 EECs and 27 NEECs by immunohistochemistry as well as CCND1 gene amplification by FISH. In EECs, mutations in K-RAS, PTEN, beta-catenin and CCND1 were studied by PCR-SSCP and sequencing and MSI was evaluated by analyzing BAT-25 and BAT-26 microsatellites. Contingency tests were used to evaluate the relationships between variables. Cyclin D1 overexpression was not observed in AEHs but was present in 13.8% of EECs and 11.2% of NEECs (p = 0.031). CCND1 amplification was more frequent in NEECs (26.3%) than in EECs (2.1%) (p = 0.002). In EECs, cyclin D1 overexpression was not associated with mutations in K-RAS, PTEN or beta-catenin. However, in EECs with beta-catenin mutations, cyclin D1 was expressed mainly by cells expressing beta-catenin in the cytoplasm and nucleus but not in those with membranous expression. Finally, cyclin D1 overexpression was associated with MSI (p = 0.047). The molecular alterations associated with cyclin D1 overexpression differ in the 2 clinicopathologic types of EC. Cyclin D1 overexpression is associated with gene amplification in NEECs and with nucleocytoplasmic expression of beta-catenin and MSI in EECs.
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Affiliation(s)
- Gema Moreno-Bueno
- Laboratory of Breast and Gynecologic Cancer, Molecular Pathology Program, Centro Nacional de Investigaciones Oncológicas, Madrid, Spain
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158
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Tanno S, Yanagawa N, Habiro A, Koizumi K, Nakano Y, Osanai M, Mizukami Y, Okumura T, Testa JR, Kohgo Y. Serine/threonine kinase AKT is frequently activated in human bile duct cancer and is associated with increased radioresistance. Cancer Res 2004; 64:3486-90. [PMID: 15150102 DOI: 10.1158/0008-5472.can-03-1788] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The prognosis for patients with bile duct cancer (BDC) remains poor. Although BDC cells are essentially radioresistant, recent reports have suggested that radiation therapy, in addition to its palliative role in the management of BDC, may improve patient survival. A better understanding of the mechanisms that lead to cellular radioresistance may assist in the development of more effective BDC therapies based on radiotherapy in combination with radiosensitizing agents. The serine/threonine kinase AKT/protein kinase B, a downstream effector of phosphatidylinositol 3'-kinase, is a well-characterized kinase that is known to play a critical role in antiapoptotic signaling pathways. In this investigation, we sought to clarify the role of AKT signaling in the radioresistance in BDC cells. First, to examine whether activated AKT is expressed in BDCs, tumor specimens were obtained from 19 consecutive BDC cases. Immunohistochemical staining using an anti-phosphorylated-AKT antibody showed that phosphorylated (activated) AKT was expressed in cancer cells but not in neighboring normal mucosa in 16 cases (84.2%). Next, to evaluate the role of AKT activation in the regulation of BDC cell radiosensitivity, clonogenic assays were performed using the phosphatidylinositol 3'-kinase inhibitor LY294002 with and without irradiation. LY294002 inhibited AKT activation in BDC cells and, on irradiation, decreased clonogenic survival in a radiation dose-dependent manner. Only a small decrease in cell viability was observed in cells exposed to LY294002. Expression of constitutively active AKT in BDC cells resulted in decreased radiosensitivity, whereas a dominant-negative AKT increased radiosensitivity. Furthermore, constitutively active AKT also inhibited radiation-induced apoptosis. Collectively, these results indicate that activated AKT in BDC cells is associated with radioresistance and suggest that pharmacological or genetic modulation of AKT activity may have important therapeutic implications in BDC patients treated with radiation.
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Affiliation(s)
- Satoshi Tanno
- Third Department of Internal Medicine, Asahikawa Medical College, Asahikawa, Japan.
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159
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Li L, He F, Litofsky NS, Recht LD, Ross AH. Profiling of genes expressed by PTEN haploinsufficient neural precursor cells. Mol Cell Neurosci 2004; 24:1051-61. [PMID: 14697668 DOI: 10.1016/j.mcn.2003.08.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
PTEN is a lipid phosphatase, and PTEN mutations are associated with gliomas, macrocephaly, and mental deficiencies. We have used PTEN +/- and PTEN +/+ mice to prepare subventricular zone (SVZ) precursor cells. Using DNA microarrays, we compared the expression profiles of PTEN +/+ and PTEN +/- cells and identified 91 differentially expressed genes in PTEN +/- precursor cells. Many of the PTEN-regulated genes are involved with signaling, cytoskeleton, extracellular matrix, metabolism, and transcription factors. Some of these changes are likely mediated by the transcription factor, HIF-1. We confirmed a subset of these changes by real-time PCR. In addition, we examined protein levels for two of the PTEN-up-regulated genes, vascular endothelial growth factor (VEGF) and doublecortin (DCX). PTEN haploinsufficiency increases immunostaining for VEGF for both cultured precursor cells and sections of the SVZ. PTEN haploinsufficiency shifted most of the DCX-positive cells from the SVZ to the olfactory bulb. These observations indicate that even a small decrease in PTEN levels results in substantial changes in gene expression and precursor cell function.
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Affiliation(s)
- Li Li
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, 364 Plantation Street, Worcester, MA 01605, USA
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160
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Abstract
Clinical drug resistance is a major barrier to overcome before chemotherapy can become curative for most patients presenting with metastatic cancer. Rational attempts to tackle clinical drug resistance need to be based on an understanding of the mechanisms involved; these are likely to be complex and multifactorial, and may be due to inadequate drug exposure or alterations in the cancer cell itself. This article reviews a number of strategies used to tackle drug resistance, focussing on work in our institution related to the treatment of ovarian cancer and resistance to platinum and taxane-based chemotherapy. Further progress towards drug resistance reversal will require a three-pronged approach, namely: the development of novel cytotoxics which exploit selectively expressed targets; modulation of resistance to conventional agents and, most importantly, a serious attempt to understand resistance mechanisms in tumour samples taken both pre- and post-chemotherapy.
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Affiliation(s)
- R D Baird
- Cancer Research UK Centre for Cancer Therapeutics, Institute of Cancer Research, 15 Cotswold Road, Sutton, Surrey SM2 5NG, UK
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161
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Mandell JW. Phosphorylation state-specific antibodies: applications in investigative and diagnostic pathology. THE AMERICAN JOURNAL OF PATHOLOGY 2003; 163:1687-98. [PMID: 14578166 PMCID: PMC1892416 DOI: 10.1016/s0002-9440(10)63525-0] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Until recently, the investigation of protein phosphorylation was limited to biochemical studies of enzyme activities in homogenized tissues. The availability of hundreds of phosphorylation state-specific antibodies (PSSAs) now makes possible the study of protein phosphorylation in situ, and is opening many exciting opportunities in investigative and diagnostic pathology. This review illustrates the power of PSSAs, especially in immunohistochemical applications to human disease and animal models. Technical considerations, including antibody specificity and lability of phosphoepitopes, are covered, along with potential pitfalls, illustrated by a case study. In the arena of oncology, PSSAs may prove especially valuable in directly demonstrating the efficacy of chemotherapies targeted at protein kinase cascades. Novel applications of PSSAs are also beginning to reveal molecular mechanisms of inflammatory, degenerative, and toxin-induced diseases.
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Affiliation(s)
- James W Mandell
- Department of Pathology (Neuropathology) and Neuroscience Graduate Program, University of Virginia, Charlottesville, VA 22908, USA.
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162
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Chen Y, Zhao YJ, Zheng HC, Yang XF, Wang GL, Xin Y. mRNA expression of PTEN and VEGF genes in epithelial ovarian cancer. Chin J Cancer Res 2003. [DOI: 10.1007/bf02974887] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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163
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Cai J, Ahmad S, Jiang WG, Huang J, Kontos CD, Boulton M, Ahmed A. Activation of vascular endothelial growth factor receptor-1 sustains angiogenesis and Bcl-2 expression via the phosphatidylinositol 3-kinase pathway in endothelial cells. Diabetes 2003; 52:2959-68. [PMID: 14633857 DOI: 10.2337/diabetes.52.12.2959] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Vascular insufficiency and retinal ischemia precede many proliferative retinopathies and stimulate secretion of various vasoactive growth factors, including vascular endothelial growth factor (VEGF) and placenta growth factor (PlGF). It is unclear, however, how PlGF, which is elevated in proliferative diabetic retinopathy and is a VEGF homolog that binds only to VEGF receptor (VEGFR)-1, promotes pathological angiogenesis. When primary microvascular endothelial cells were grown on collagen gels, PlGF-containing ligands upregulated Bcl-2 expression and stimulated the formation of capillary-like tube networks that were retained for up to 14 days in culture. The inhibition of VEGFR-1 results in a dramatic decrease in the number of capillary connections, indicating that VEGFR-1 ligands promote branching angiogenesis. In contrast, VEGF-induced tube formations and Bcl-2 expression were significantly decreased at the end of this period. Flow cytometry analysis of annexin-V/propidium iodide-stained cells revealed that PlGF and PlGF/VEGF heterodimer inhibited apoptosis in serum-deprived endothelial cells. These two growth factors stimulated a survival signaling pathway phosphatidylinositol 3-kinase (PI3K), as identified by increased Akt phosphorylation and because blocking PI3K signalling by adenovirus-mediated overexpression of wild-type phosphatase and tensin homolog on chromosome 10 (PTEN) disrupted angiogenesis and decreased Bcl-2 expression by PlGF and PlGF/VEGF heterodimer, whereas a dominant-negative PTEN mutant enhanced endothelial sprout formation and Bcl-2 expression. Together, these findings indicate that PlGF-containing ligands contribute to pathological angiogenesis by prolonging cell survival signals and maintaining vascular networks.
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Affiliation(s)
- Jun Cai
- Department of Optometry and Vision Sciences, Cardiff University, Cardiff, UK
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164
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Ahmed N, Riley C, Oliva K, Stutt E, Rice GE, Quinn MA. Integrin-linked kinase expression increases with ovarian tumour grade and is sustained by peritoneal tumour fluid. J Pathol 2003; 201:229-37. [PMID: 14517840 DOI: 10.1002/path.1441] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Integrin-linked kinase (ILK) is a serine threonine kinase, overexpression of which promotes tumour growth and invasion through deregulation of the cell cycle. This study demonstrates the relative expression of ILK in normal, benign, low-grade, and high-grade (borderline, grade I/II, and grade III) ovarian tumours of serous, mucinous, endometrioid, and clear cell types in order to assess its potential as a marker for epithelial ovarian cancer progression. Seventy-three specimens including ten normal, ten benign, 14 borderline, 17 grade I/II, and 22 grade III were evaluated by immunohistochemistry. Immunoreactive ILK was not detectable in normal ovarian surface epithelium. All 53 carcinomas studied were positive and the staining intensity correlated significantly with the grade of the tumour. Ovarian cancer cell lines had high expression of ILK, while immortalized normal ovarian surface epithelial cell lines (HOSE) showed low basal expression of ILK by western blotting. Peritoneal tumour fluid (PTF) upregulated ILK expression in ovarian cancer cell lines but had no effect on HOSE cells. PTF-induced up-regulation of ILK expression in ovarian cancer cell lines correlated with the activation of the downstream protein kinase B (PKB/Akt) pathway. Collectively, these data demonstrate that ILK expression increases with ovarian cancer progression and that soluble factors in PTF mediate sustained overexpression of ILK in ovarian cancer cells. Suppression of ILK expression may therefore represent a novel and an efficient mechanism for controlling ovarian tumour growth.
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MESH Headings
- Adenocarcinoma/chemistry
- Adenocarcinoma/enzymology
- Adenocarcinoma/pathology
- Adenocarcinoma, Clear Cell/chemistry
- Adenocarcinoma, Clear Cell/enzymology
- Adenocarcinoma, Clear Cell/pathology
- Adenocarcinoma, Mucinous/chemistry
- Adenocarcinoma, Mucinous/enzymology
- Adenocarcinoma, Mucinous/pathology
- Ascitic Fluid/metabolism
- Biomarkers, Tumor/analysis
- Blotting, Western/methods
- Carcinoma, Endometrioid/chemistry
- Carcinoma, Endometrioid/enzymology
- Carcinoma, Endometrioid/pathology
- Chi-Square Distribution
- Cystadenoma, Serous/chemistry
- Cystadenoma, Serous/enzymology
- Cystadenoma, Serous/pathology
- Female
- Humans
- Immunohistochemistry/methods
- Ovarian Neoplasms/chemistry
- Ovarian Neoplasms/enzymology
- Ovarian Neoplasms/pathology
- Protein Serine-Threonine Kinases/analysis
- Proto-Oncogene Proteins/analysis
- Proto-Oncogene Proteins c-akt
- Tumor Cells, Cultured/chemistry
- Tumor Cells, Cultured/enzymology
- Tumor Cells, Cultured/pathology
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Affiliation(s)
- Nuzhat Ahmed
- Gynaecological Cancer Research Centre, The Department of Obstetrics and Gynaecology, Royal Women's Hospital, The University of Melbourne, Victoria, Australia.
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165
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Stabile E, Zhou YF, Saji M, Castagna M, Shou M, Kinnaird TD, Baffour R, Ringel MD, Epstein SE, Fuchs S. Akt controls vascular smooth muscle cell proliferation in vitro and in vivo by delaying G1/S exit. Circ Res 2003; 93:1059-65. [PMID: 14605018 DOI: 10.1161/01.res.0000105086.31909.1b] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Constitutive activation of serine/threonine kinase Akt causes uncontrolled cell-cycle progression in different cell types and in malignancy. To investigate how Akt activation modulates cell-cycle progression in vascular smooth muscle cells (SMCs) in vitro and in the intact animal, we inhibited Akt-dependent signaling by adenovirus-mediated transfection of a dominant-negative Akt mutant (AA-Akt). We observed reduced proliferation rate (P<0.01), DNA synthesis (P<0.01), and a significant arrest in G1/S exit (P<0.01) both in vitro in response to serum stimulation and in vivo after vascular injury. In vivo transfection of the balloon-injured vessel with AA-Akt reduced SMC proliferation, resulting in decreased neointima compared with control virus (P<0.01). These effects were at least in part modulated, both in vitro and in vivo, by increased p21Cip1 expression, as demonstrated by lack of effect of AA-Akt on cell proliferation in p21-/- mouse SMCs. In conclusion, this study demonstrates that Akt-dependent signaling enhances cell-cycle progression of nontransformed SMCs in vitro and in response to vascular injury in the intact animal. These results suggest a role for Akt signaling in modulating the response of normal tissues to stress and the response of the arterial wall to acute and possibly repetitive injuries that ultimately contribute to restenosis and atherosclerosis.
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MESH Headings
- Adenoviridae/genetics
- Angioplasty, Balloon/adverse effects
- Animals
- Blood Proteins/pharmacology
- Carotid Stenosis/etiology
- Carotid Stenosis/pathology
- Carotid Stenosis/therapy
- Cell Division/drug effects
- Cell Division/physiology
- Cells, Cultured
- Cyclin-Dependent Kinase Inhibitor p21
- Cyclins/deficiency
- Cyclins/genetics
- Cyclins/metabolism
- Disease Models, Animal
- G1 Phase/physiology
- Genes, Dominant
- Genetic Therapy/methods
- Graft Occlusion, Vascular/etiology
- Male
- Mice
- Mice, Knockout
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Protein Serine-Threonine Kinases
- Proto-Oncogene Proteins/genetics
- Proto-Oncogene Proteins/metabolism
- Proto-Oncogene Proteins c-akt
- Rats
- Rats, Sprague-Dawley
- Ribosomal Protein S6 Kinases, 70-kDa/metabolism
- S Phase/drug effects
- S Phase/physiology
- Signal Transduction/physiology
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Affiliation(s)
- Eugenio Stabile
- Cardiovascular Research Institute, Washington Hospital Center, 110 Irving St NW, 4B-1, Washington, DC 20010, USA.
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166
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Lu Y, Yu Q, Liu JH, Zhang J, Wang H, Koul D, McMurray JS, Fang X, Yung WKA, Siminovitch KA, Mills GB. Src family protein-tyrosine kinases alter the function of PTEN to regulate phosphatidylinositol 3-kinase/AKT cascades. J Biol Chem 2003; 278:40057-66. [PMID: 12869565 DOI: 10.1074/jbc.m303621200] [Citation(s) in RCA: 199] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Src family protein-tyrosine kinases, which play an important role in signal integration, have been implicated in tumorigenesis in multiple lineages, including breast cancer. We demonstrate, herein, that Src kinases regulate the phosphatidylinositol 3-kinase (PI3K) signaling cascade via altering the function of the PTEN tumor suppressor. Overexpression of activated Src protein-tyrosine kinases in PTEN-deficient breast cancer cells does not alter AKT phosphorylation, an indicator of signal transduction through the PI3K pathway. However, in the presence of functional PTEN, Src reverses the activity of PTEN, resulting in an increase in AKT phosphorylation. Activated Src reduces the ability of PTEN to dephosphorylate phosphatidylinositols in micelles and promotes AKT translocation to cellular plasma membranes but does not alter PTEN activity toward water-soluble phosphatidylinositols. Thus, Src may alter the capacity of the PTEN C2 domain to bind cellular membranes rather than directly interfering with PTEN enzymatic activity. Tyrosine phosphorylation of PTEN is increased in breast cancer cells treated with pervanadate, suggesting that PTEN contains sites for tyrosine phosphorylation. Src kinase inhibitors markedly decreased pervanadate-mediated tyrosine phosphorylation of PTEN. Further, expression of activated Src results in marked tyrosine phosphorylation of PTEN. SHP-1, a SH2 domain-containing protein-tyrosine phosphatase, selectively binds and dephosphorylates PTEN in Src transfected cells. Both Src inhibitors and SHP-1 overexpression reverse Src-induced loss of PTEN function. Coexpression of PTEN with activated Src reduces the stability of PTEN. Taken together, the data indicate that activated Src inhibits PTEN function leading to alterations in signaling through the PI3K/AKT pathway.
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Affiliation(s)
- Yiling Lu
- Department of Molecular Therapeutics, Division of Cancer Medicine, M. D. Anderson Cancer Center, Houston, Texas 77030, USA
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167
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Abstract
PTEN, on 10q23.3, encodes a major lipid phosphatase which signals down the phosphoinositol-3-kinase/Akt pathway and effects G1 cell cycle arrest and apoptosis. Germline PTEN mutations have been found to occur in 80% of classic Cowden syndrome (CS), 60% of Bannayan-Riley-Ruvalcaba syndrome (BRRS), up to 20% of Proteus syndrome (PS), and approximately 50% of a Proteus-like syndrome (PSL). CS is a heritable multiple hamartoma syndrome with a high risk of breast, thyroid, and endometrial carcinomas. BRRS is a congenital autosomal dominant disorder characterized by megencephaly, developmental delay, lipomatosis, and speckled penis. PS and PSL had never been associated with risk of malignancy. Finding germline PTEN mutations in patients with BRRS, PS, and PSL suggests equivalent risks of developing malignancy as in CS with implications for medical management. The mutational spectra of CS and BRRS overlap, with many of the mutations occurring in exons 5, 7, and 8. Genotype-phenotype association analyses have revealed that the presence of germline PTEN mutations is associated with breast tumor development, and that mutations occurring within and 5' of the phosphatase motif were associated with multi-organ involvement. Pooled analysis of PTEN mutation series of CS and BRRS occurring in the last five years reveals that 65% of CS-associated mutations occur in the first five exons encoding the phosphatase domain and the promoter region, while 60% of BRRS-associated mutations occur in the 3' four exons encoding mainly the C2 domain. Somatic PTEN mutations occur with a wide distribution of frequencies in sporadic primary tumors, with the highest frequencies in endometrial carcinomas and glioblastoma multiform. Several mechanisms of PTEN inactivation occur in primary malignancies derived from different tissues, but a favored mechanism appears to occur in a tissue-specific manner. Inappropriate subcellular compartmentalization and increased/decreased proteosome degradation may be two novel mechanisms of PTEN inactivation. Further functional work could reveal more effective means of molecular-directed therapy and prevention.
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Affiliation(s)
- Charis Eng
- Clinical Cancer Genetics Program and Human Cancer Genetics Program, Comprehensive Cancer Center, Division of Human Genetics, Department of Internal Medicine, The Ohio State University, Columbus, Ohio 43210, USA.
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168
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Nicosia SV, Bai W, Cheng JQ, Coppola D, Kruk PA. Oncogenic pathways implicated in ovarian epithelial cancer. Hematol Oncol Clin North Am 2003; 17:927-43. [PMID: 12959183 DOI: 10.1016/s0889-8588(03)00056-x] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Characterization of intracellular signaling pathways should lead to a better understanding of ovarian epithelial carcinogenesis and provide an opportunity to interfere with signal transduction targets involved in ovarian tumor cell growth, survival, and progression. Challenges toward such an effort are significant because many of these signals are part of cascades within an intricate and likely redundant intracellular signaling network (Fig.1). For instance, a given signal may activate a dual intracellular pathway (ie, MEK1-MAPK and PI3K/Akt required for fibronectin-dependent activation of matrix metalloproteinase 9). A single pathway also may transduce more than one biologic or oncogenic signal (ie, PI3K signaling in epithelial and endothelial cell growth and sprouting of neovessels). Despite these challenges, evidence for therapeutic targeting of signal transduction pathways is accumulating in human cancer. For instance, the EGF-specific tyrosine kinase inhibitor ZD 1839 (Iressa) may have a beneficial therapeutic effect on ovarian epithelial cancer. Therapy of this cancer may include inhibitors of PI kinase (quercetin), ezrin and PIP kinase (genistein). The G protein-coupled family of receptors, including LPA, also is an attractive target to drugs, although their frequent pleiotropic functions may be at times toxic and lack specificity. Because of the lack of notable toxicity, PI3K/Akt pathway inhibitors such as FTIs are a promising targeted therapy of ovarian epithelial cancer. Increasing insight into the oncogenic pathways involved in ovarian epithelial cancer also is helping clinicians to understand better the phenomenon of chemoresistance in this malignancy. Oncogenic activation of gamma-synuclein promotes cell survival and provides resistance to paclitaxel, but such a resistance is partially overcome by an MEK inhibitor that suppresses ERK activity. Ovarian epithelial cancer is a complex group of neoplasms with an overall poor prognosis. Comprehension of this cancer pathobiology suffers because of an incomplete understanding of precursor lesions and the absence of an orthotopic animal model until very recently. It can be predicted with confidence, however, that the discovery of potent inhibitors of signal transduction and the development of discovery tools, such as proteomics and metabolomics, may change the way by which clinicians may now address basic biomedical questions in this insidious and lethal disease.
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Affiliation(s)
- Santo V Nicosia
- Department of Pathology and Laboratory Medicine, University of South Florida College of Medicine, 12901 Bruce B. Downs Boulevard, MDC Box 11, Tampa, FL 33612, USA.
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169
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Cruet-Hennequart S, Maubant S, Luis J, Gauduchon P, Staedel C, Dedhar S. alpha(v) integrins regulate cell proliferation through integrin-linked kinase (ILK) in ovarian cancer cells. Oncogene 2003; 22:1688-702. [PMID: 12642872 DOI: 10.1038/sj.onc.1206347] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Integrins regulate both adhesion and signaling processes involved in proliferation and survival. alpha(v)beta(3) and alpha(v)beta(5) integrins have been shown to mediate cell adhesion and migration. Here we used human ovarian cancer cell lines (IGROV1, SKOV-3) that express alpha(v)beta(3) and alpha(v)beta(5) to study their role in cell proliferation and the signaling pathways involved. We found that alpha(v) integrins regulate cell proliferation through activation of integrin-linked kinase (ILK). An anti-alpha(v)-blocking antibody specifically inhibits the growth of IGROV1 and SKOV-3. The inhibition of cell proliferation involves alpha(v)beta(3) in IGROV1 cells, and both alpha(v)beta(3) and alpha(v)beta(5) in SKOV-3 cells. The reduced growth rate induced by alpha(v) integrin blockade is linked in both cell lines to G1/S cell cycle arrest. alpha(v) integrin blockade by neutralizing antibody as well as cyclic-RGD peptide caused an inhibition of ILK activity and phosphorylation of PKB/Akt on serine-473 but not on threonine-308, and was accompanied by an increase in p27(Kip1) expression. Overexpression of wild-type ILK rescued the phosphorylation of PKB/Akt on serine-473 in cells treated with anti-alpha(v) antibody. Inhibition of ILK by a pharmacological inhibitor results in inhibition of cell proliferation, PKB/Akt phosphorylation and increase of p27(Kip1). These results demonstrate that alpha(v) integrins regulate ovarian cancer cell proliferation through ILK.
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170
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Shi W, Zhang X, Pintilie M, Ma N, Miller N, Banerjee D, Tsao MS, Mak T, Fyles A, Liu FF. Dysregulated PTEN-PKB and negative receptor status in human breast cancer. Int J Cancer 2003; 104:195-203. [PMID: 12569575 DOI: 10.1002/ijc.10909] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Recent studies demonstrate that abnormalities in PTEN may be one of the most frequent genetic events observed in human cancers. PTEN dysfunction leads to tumorigenesis through unopposed survival signals mediated via activated protein kinase B (PKB), which may also be associated with hormone-independence. We therefore investigated the relationship between PTEN-PKB and receptor status in human breast cancer. Several molecular variables, including immunohistochemical staining for PTEN, PKB (phosphorylated on ser473), p53 and p21 were evaluated. The p53 gene was sequenced from exons 2-11. Seventy-eight participants in a randomised breast cancer trial served as the cohort for our study. Twenty-eight of 77 (36%) patients' tumours demonstrated absent or reduced PTEN expression; 17 of 78 (22%) tumours over-expressed P-PKB. A significant inverse relationship was observed between reduced PTEN and increased P-PKB expression. Reduced PTEN also correlated with reduced ER or PR expression. None of the molecular variables correlated with survival. ER and PR negative tumours, however, experienced a significantly inferior disease-free survival than other ER/PR status tumours. Immunohistochemical analyses of ER expression in mammary carcinomas arising in PTEN heterozygous knockout mice did not demonstrate a reduction in ER immunoreactivity, in comparison to wild-type mice. Our data demonstrate that the PTEN-PKB pathway is abnormal in approximately 1/3 of lymph node negative breast cancer. Dysregulated PTEN-PKB was also associated with reduced ER/PR expression, but this does not appear to be a simple direct causal relationship. These observations support the contention that dysregulation in PTEN-PKB contributes to disease progression and hormone resistance of human breast cancer.
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Affiliation(s)
- Wei Shi
- Department of Experimental Therapeutics, Princess Margaret Hospital, Ontario Cancer Institute, Toronto, Ontario
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171
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Schöndorf T, Göhring UJ, Roth G, Middel I, Becker M, Moser N, Valter MM, Hoopmann M. Time to progression is dependent on the expression of the tumour suppressor PTEN in ovarian cancer patients. Eur J Clin Invest 2003; 33:256-60. [PMID: 12641545 DOI: 10.1046/j.1365-2362.2003.01116.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Quantitative analyses of PTEN expression of ovarian cancer tissues were performed in this study. PTEN expression was investigated in terms of each patient's progression-free interval to indicate the role of PTEN in the generation of platinum refractory tumours. MATERIALS AND METHODS The study group comprised 20 ovarian cancer patients from whom fresh frozen tissues of both the primary tumour and specimens of progressive disease were available. The PTEN protein and phosphorylation of the downstream effector protein kinase B (PKB) were quantified by Western blot analyses and subsequent densitometry. Data were analyzed for individual PTEN variation with respect to the clinical course as defined by the progression-free interval. RESULTS Applying the usual clinical criteria for platinum-sensitivity after progression, seven patients were considered platinum-sensitive whereas 13 patients had suffered a progression within 12 months after the chemotherapy. In 5/7 (71%) cases with prolonged time to progression, an increase in PTEN was observed. Decline of PTEN expression occurred in 9/13 (69%) patients with poor outcome. PTEN expression corresponds inversely to PKB phosphorylation in 14/20 (70%) tissues investigated. CONCLUSIONS The data suggest that decreased PTEN expression accompanies the progression of ovarian cancer. Declining PTEN expression results in a shortened relapse-free interval, whereas an increase of PTEN prolongs the time to progression. However, as far as recurrence occurs, PTEN is not the only mechanism to suppress tumour progression in ovarian cancer.
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Affiliation(s)
- T Schöndorf
- Department of Gynecology and Obstetrics, University of Cologne, Cologne, Germany
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172
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173
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Mills GB, Fang X, Lu Y, Hasegawa Y, Eder A, Tanyi J, Tabassam FH, Mao M, Wang H, Cheng KW, Nakayama Y, Kuo W, Erickson J, Gershenson D, Kohn EC, Jaffe R, Bast RC, Gray J. Specific keynote: molecular therapeutics in ovarian cancer. Gynecol Oncol 2003; 88:S88-92; discussion S93-6. [PMID: 12586094 DOI: 10.1006/gyno.2002.6692] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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174
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West KA, Castillo SS, Dennis PA. Activation of the PI3K/Akt pathway and chemotherapeutic resistance. Drug Resist Updat 2002; 5:234-48. [PMID: 12531180 DOI: 10.1016/s1368-7646(02)00120-6] [Citation(s) in RCA: 438] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The resistance of many types of cancer to conventional chemotherapies is a major factor undermining successful cancer treatment. In this review, the role of a signal transduction pathway comprised of the lipid kinase, phosphatidylinositol 3-kinase (PI3K), and the serine/threonine kinase, Akt (or PKB), in chemotherapeutic resistance will be explored. Activation of this pathway plays a pivotal role in essential cellular functions such as survival, proliferation, migration and differentiation that underlie the biology of human cancer. Akt activation also contributes to tumorigenesis and tumor metastasis, and as shown most recently, resistance to chemotherapy. Modulating Akt activity is now a commonly observed endpoint of chemotherapy administration or administration of chemopreventive agents. Studies performed in vitro and in vivo combining small molecule inhibitors of the PI3K/Akt pathway with standard chemotherapy have been successful in attenuating chemotherapeutic resistance. As a result, small molecules designed to specifically target Akt and other components of the pathway are now being developed for clinical use as single agents and in combination with chemotherapy to overcome therapeutic resistance. Specifically inhibiting Akt activity may be a valid approach to treat cancer and increase the efficacy of chemotherapy.
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Affiliation(s)
- Kip A West
- Cancer Therapeutics Branch, Center for Cancer Research, National Cancer Institute, Building 8, Room 5101, 8901 Wisconsin Avenue, Bethesda, MD 20889, USA
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175
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An HJ, Lee YH, Cho NH, Shim JY, Kim JY, Lee C, Kim SJ. Alteration of PTEN expression in endometrial carcinoma is associated with down-regulation of cyclin-dependent kinase inhibitor, p27. Histopathology 2002; 41:437-45. [PMID: 12405911 DOI: 10.1046/j.1365-2559.2002.01455.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
AIMS PTEN is a recently identified tumour suppressor inactivated in a wide variety of human cancers, including endometrial cancers. Mutation of the PTEN tumour suppressor gene has been reported in approximately 50-83% of endometrial adenocarcinoma. Despite this fact, study of the expression of PTEN protein in human tumours is limited. PTEN protein functions as a tumour suppressor by regulating the cell cycle and survival through signal transduction pathway. PTEN protein was considered to have a dual-specificity phosphatase activity, but it is now known that its principal physiological activity is mainly derived from its lipid phosphatase activity. The cyclin-dependent kinase inhibitor, p27, has been suggested as a downstream target of cell cycle arrest of PTEN in various in vitro studies. In this study, we evaluated the alteration of PTEN protein expression in endometrial carcinoma and assessed its relationship to the expression of p27, the presumed downstream target of PTEN. METHODS AND RESULTS Immunohistochemical staining was performed on 66 cases of endometrial carcinoma including 61 endometrioid type and five serous type, using antibodies to PTEN and p27. Loss or decrease of PTEN expression was observed in 66% (40/61 cases) of uterine endometrioid carcinoma, whereas most uterine serous carcinoma (4/5 cases) showed intense PTEN expression. Four (30%) of 13 endometrial hyperplasia synchronous with endometrioid carcinoma demonstrated complete loss of PTEN expression. All endometrioid carcinoma synchronous with PTEN-negative endometrial hyperplasia showed loss of PTEN expression. Alteration of PTEN expression was not correlated with histological grade or stage. Decreased immunoreactivity of p27 was found in 48 cases (79%) of 61 endometrioid carcinoma, and 76% (36 cases) of them also showed loss or decrease of PTEN expression. Four of five uterine serous carcinoma revealed strong p27 immunoreactivity, all of which showed intense PTEN expression. A positive correlation between PTEN and p27 expression was statistically significant (Mantel-Haenszel chi2 test, P=0.001). Immunoreactivity of p27 was not related to histological grade and clinical stage. CONCLUSION These results show that PTEN and p27 are differentially expressed in endometrioid type carcinoma compared with those of the serous type, and suggest that the cyclin-dependent kinase inhibitor, p27, is a downstream target of PTEN-dependent cell cycle arrest in endometrial carcinoma.
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Affiliation(s)
- H-J An
- Department of Pathology, College of Medicine, Pochon CHA University, Sungnam, Korea.
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176
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Wang N. Cytogenetics and molecular genetics of ovarian cancer. AMERICAN JOURNAL OF MEDICAL GENETICS 2002; 115:157-63. [PMID: 12407696 DOI: 10.1002/ajmg.10695] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Genetic alterations identified in human ovarian tumors by conventional banding, fluorescence in situ hybridization, comparative genomic hybridization, chromosome microdissection, loss of heterozygosity, chromosome microcell-mediated chromosome transfer, and microarray gene expression analysis are summarized and correlated. The significance of these findings with respect to pathologic classification and clinical application are discussed.
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Affiliation(s)
- Nancy Wang
- University of Rochester, School of Medicine, New York, USA.
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177
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Liu Y, Dodds P, Emilion G, Mungall AJ, Dunham I, Beck S, Wells RS, Charnock FML, Ganesan TS. The human homologue of unc-93 maps to chromosome 6q27 - characterisation and analysis in sporadic epithelial ovarian cancer. BMC Genet 2002; 3:20. [PMID: 12381271 PMCID: PMC134458 DOI: 10.1186/1471-2156-3-20] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2002] [Accepted: 10/15/2002] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND In sporadic ovarian cancer, we have previously reported allele loss at D6S193 (62%) on chromosome 6q27, which suggested the presence of a putative tumour suppressor gene. Based on our data and that from another group, the minimal region of allele loss was between D6S264 and D6S149 (7.4 cM). To identify the putative tumour suppressor gene, we established a physical map initially with YACs and subsequently with PACs/BACs from D6S264 to D6S149. To accelerate the identification of genes, we sequenced the entire contig of approximately 1.1 Mb. Seven genes were identified within the region of allele loss between D6S264 and D6S149. RESULTS The human homologue of unc-93 (UNC93A) in C. elegans was identified to be within the interval of allele loss centromeric to D6S149. This gene is 24.5 kb and comprises of 8 exons. There are two transcripts with the shorter one due to splicing out of exon 4. It is expressed in testis, small intestine, spleen, prostate, and ovary. In a panel of 8 ovarian cancer cell lines, UNC93A expression was detected by RT-PCR which identified the two transcripts in 2/8 cell lines. The entire coding sequence was examined for mutations in a panel of ovarian tumours and ovarian cancer cell lines. Mutations were identified in exons 1, 3, 4, 5, 6 and 8. Only 3 mutations were identified specifically in the tumour. These included a c.452G>A (W151X) mutation in exon 3, c.676C>T (R226X) in exon 5 and c.1225G>A(V409I) mutation in exon 8. However, the mutations in exon 3 and 5 were also present in 6% and 2% of the normal population respectively. The UNC93A cDNA was shown to express at the cell membrane and encodes for a protein of 60 kDa. CONCLUSIONS These results suggest that no evidence for UNC93A as a tumour suppressor gene in sporadic ovarian cancer has been identified and further research is required to evaluate its normal function and role in the pathogenesis of ovarian cancer.
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MESH Headings
- Amino Acid Sequence
- Base Sequence
- Cell Line
- Cell Membrane/metabolism
- Chromatography, High Pressure Liquid/methods
- Chromosome Mapping
- Chromosomes, Human, Pair 6/genetics
- DNA Mutational Analysis
- DNA, Complementary/chemistry
- DNA, Complementary/genetics
- DNA, Neoplasm/chemistry
- DNA, Neoplasm/genetics
- Female
- Gene Expression Regulation, Neoplastic
- Genes, Tumor Suppressor
- Green Fluorescent Proteins
- Humans
- Luminescent Proteins/genetics
- Luminescent Proteins/metabolism
- Membrane Proteins/genetics
- Molecular Sequence Data
- Muscle Proteins/genetics
- Mutation
- Ovarian Neoplasms/genetics
- Ovarian Neoplasms/pathology
- Polymorphism, Single-Stranded Conformational
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/metabolism
- Sequence Homology, Amino Acid
- Tumor Cells, Cultured
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Affiliation(s)
- Ying Liu
- Cancer Research UK Molecular Oncology Laboratories, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Headington, Oxford, OX3 9DS, UK
| | - Phillippa Dodds
- Cancer Research UK Molecular Oncology Laboratories, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Headington, Oxford, OX3 9DS, UK
| | - Gracy Emilion
- Cancer Research UK Molecular Oncology Laboratories, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Headington, Oxford, OX3 9DS, UK
| | - Andrew J Mungall
- Sanger Centre, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SA, UK
| | - Ian Dunham
- Sanger Centre, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SA, UK
| | - Stephan Beck
- Sanger Centre, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SA, UK
| | - R Spencer Wells
- Cancer Research UK Molecular Oncology Laboratories, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Headington, Oxford, OX3 9DS, UK
| | - F Mark L Charnock
- Cancer Research UK Molecular Oncology Laboratories, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Headington, Oxford, OX3 9DS, UK
| | - Trivadi S Ganesan
- Cancer Research UK Molecular Oncology Laboratories, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Headington, Oxford, OX3 9DS, UK
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178
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Abstract
Heat shock protein 90 (Hsp90) is a molecular chaperone whose association is required for the stability and function of multiple mutated, chimeric and over-expressed signaling proteins that promote the growth and/or survival of cancer cells. Hsp90 client proteins include mutated p53, Bcr-Abl, Raf-1, Akt, ErbB2 and hypoxia-inducible factor 1 alpha (HIF-1 alpha). Hsp90 inhibitors, by interacting specifically with a single molecular target, cause the destabilization and eventual degradation of Hsp90 client proteins, and they have shown promising antitumor activity in preclinical model systems. One Hsp90 inhibitor, 17-allylaminogeldanamycin (17AAG), is currently in phase I clinical trial. Because of the chemoprotective activity of several proteins that are Hsp90 clients, the combination of an Hsp90 inhibitor with a standard chemotherapeutic agent could dramatically increase the in vivo efficacy of the therapeutic agent.
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Affiliation(s)
- Len Neckers
- Cell and Cancer Biology Branch, National Cancer Institute, National Institutes of Health, 9610 Medical Center Drive, Suite 300, Rockville, MD 20850, USA.
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179
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Lee SH, Kim HS, Park WS, Kim SY, Lee KY, Kim SH, Lee JY, Yoo NJ. Non-small cell lung cancers frequently express phosphorylated Akt; an immunohistochemical study. APMIS 2002; 110:587-92. [PMID: 12390418 DOI: 10.1034/j.1600-0463.2002.11007811.x] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Mounting evidence suggests that the alterations of Akt/protein kinase B (PKB) play an important role in tumorigenesis. Phosphorylated Akt regulates many of the key effector molecules involved in apoptosis, angiogenesis, and cell cycle progression during tumorigenesis. The expression of phosphorylated Akt has been described in some human malignancies, but not in primary human lung cancer. In this study, to understand the role of Akt in lung tumorigenesis we analyzed the expression of phosphorylated Akt in 43 non-small cell lung cancers (NSCLCs) by immunohistochemistry. Phosphorylated Akt was detected either in the cytoplasm (23 cases) or nucleus (6 cases) in 29 of 43 NSCLCs (67.4%). Squamous cell carcinomas, adenocarcinomas, and bronchioloalveolar carcinomas expressed phosphorylated Akt in 68.2%, 61.5% and 75%, respectively. We also analyzed the phosphorylated Akt expression between primary NSCLCs and their corresponding nodal metastasis; the expression was not, however, different between the primary and metastatic lesions. Taken together, these results indicate that Akt 1 is frequently activated in NSCLCs, irrespective of the histological subtypes, and suggest that phosphorylated Akt may play a role in the development of NSCLC rather than in the progression of NSCLC.
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Affiliation(s)
- Sug Hyung Lee
- Department of Pathology, College of Medicine, The Catholic University of Korea, Seoul, Korea
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180
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Zhou XP, Loukola A, Salovaara R, Nystrom-Lahti M, Peltomäki P, de la Chapelle A, Aaltonen LA, Eng C. PTEN mutational spectra, expression levels, and subcellular localization in microsatellite stable and unstable colorectal cancers. THE AMERICAN JOURNAL OF PATHOLOGY 2002; 161:439-47. [PMID: 12163369 PMCID: PMC1850747 DOI: 10.1016/s0002-9440(10)64200-9] [Citation(s) in RCA: 152] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
PTEN on 10q23.3 encodes a dual-specificity phosphatase that negatively regulates the phosphoinositol-3-kinase/Akt pathway and mediates cell-cycle arrest and apoptosis. Germline PTEN mutations cause Cowden syndrome and a range of several different hamartoma-tumor syndromes. Hereditary nonpolyposis colon cancer (HNPCC) syndrome is characterized by germline mutations in the mismatch repair (MMR) genes and by microsatellite instability (MSI) in component tumors. Although both colorectal carcinoma and endometrial carcinoma are the most frequent component cancers in HNPCC, only endometrial cancer has been shown to be a minor component of Cowden syndrome. We have demonstrated that somatic inactivation of PTEN is involved in both sporadic endometrial cancers and HNPCC-related endometrial cancers but with different mutational spectra and different relationships to MSI. In the current study, we sought to determine the relationship of PTEN mutation, 10q23 loss of heterozygosity, PTEN expression, and MSI status in colorectal cancers (CRCs). Among 11 HNPCC CRCs, 32 MSI+ sporadic cancers, and 39 MSI- tumors, loss of heterozygosity at 10q23.3 was found in 0%, 8%, and 19%, respectively. Somatic mutations were found in 18% (2 of 11) of the HNPCC CRCs and 13% (4 of 32) of the MSI+ sporadic tumors, but not in MSI- cancers (P = 0.015). All somatic mutations occurred in the two 6(A) coding mononucleotide tracts in PTEN, suggestive of the etiological role of the deficient MMR. Immunohistochemical analysis revealed 31% (14 of 45) of the HNPCC CRCs and 41% (9 of 22) of the MSI+ sporadic tumors with absent or depressed PTEN expression. Approximately 17% (4 of 23) of the MSI- CRCs had decreased PTEN expression, and no MSI- tumor had complete loss of PTEN expression. Among the five HNPCC or MSI+ sporadic CRCs carrying frameshift somatic mutations with immunohistochemistry data, three had lost all PTEN expression, one showed weak PTEN expression levels, and one had mixed tumor cell populations with weak and moderate expression levels. These results suggest that PTEN frameshift mutations in HNPCC and sporadic MSI+ tumors are a consequence of mismatch repair deficiency. Further, hemizygous deletions in MSI- CRCs lead to loss or reduction of PTEN protein levels and contribute to tumor progression. Finally, our data also suggest that epigenetic inactivation of PTEN, including differential subcellular compartmentalization, occurs in CRCs.
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Affiliation(s)
- Xiao-Ping Zhou
- Clinical Cancer Genetics Program, Comprehensive Cancer Center and the Division of Human Genetics, Department of Internal Medicine, The Ohio State University, Columbus, Ohio 43210, USA
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181
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Whiteman DC, Zhou XP, Cummings MC, Pavey S, Hayward NK, Eng C. Nuclear PTEN expression and clinicopathologic features in a population-based series of primary cutaneous melanoma. Int J Cancer 2002; 99:63-7. [PMID: 11948493 DOI: 10.1002/ijc.10294] [Citation(s) in RCA: 138] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Germline mutations of the PTEN tumor-suppressor gene, on 10q23, cause Cowden syndrome, an inherited hamartoma syndrome with a high risk of breast, thyroid and endometrial carcinomas and, some suggest, melanoma. To date, most studies which strongly implicate PTEN in the etiology of sporadic melanomas have depended on cell lines, short-term tumor cultures and noncultured metastatic melanomas. The only study which reports PTEN protein expression in melanoma focuses on cytoplasmic expression, mainly in metastatic samples. To determine how PTEN contributes to the etiology or the progression of primary cutaneous melanoma, we examined cytoplasmic and nuclear PTEN expression against clinical and pathologic features in a population-based sample of 150 individuals with incident primary cutaneous melanoma. Among 92 evaluable samples, 30 had no or decreased cytoplasmic PTEN protein expression and the remaining 62 had normal PTEN expression. In contrast, 84 tumors had no or decreased nuclear expression and 8 had normal nuclear PTEN expression. None of the clinical features studied, such as Clark's level and Breslow thickness or sun exposure, were associated with cytoplasmic PTEN expressional levels. An association with loss of nuclear PTEN expression was indicated for anatomical site (p = 0.06) and mitotic index (p = 0.02). There was also an association for melanomas to either not express nuclear PTEN or to express p53 alone, rather than both simultaneously (p = 0.02). In contrast with metastatic melanoma, where we have shown previously that almost two-thirds of tumors have some PTEN inactivation, only one-third of primary melanomas had PTEN silencing. This suggests that PTEN inactivation is a late event likely related to melanoma progression rather than initiation. Taken together with our previous observations in thyroid and islet cell tumors, our data suggest that nuclear-cytoplasmic partitioning of PTEN might also play a role in melanoma progression.
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Affiliation(s)
- David C Whiteman
- Population and Clinical Sciences Division, Queensland Institute of Medical Research, Royal Brisbane Hospital, Brisbane, Australia
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Huang J, Kontos CD. PTEN modulates vascular endothelial growth factor-mediated signaling and angiogenic effects. J Biol Chem 2002; 277:10760-6. [PMID: 11784722 DOI: 10.1074/jbc.m110219200] [Citation(s) in RCA: 152] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Phosphatidylinositol 3-kinase is activated by vascular endothelial growth factor (VEGF), and many of the angiogenic cellular responses of VEGF are regulated by the lipid products of phosphatidylinositol 3-kinase. The tumor suppressor PTEN has been shown to down-regulate phosphatidylinositol 3-kinase signaling, yet the effects of PTEN on VEGF-mediated signaling and angiogenesis are unknown. Inhibition of endogenous PTEN in cultured endothelial cells by adenovirus-mediated overexpression of a dominant negative PTEN mutant (PTEN-C/S) enhanced VEGF-mediated Akt phosphorylation, and this effect correlated with decreases in caspase-3 cleavage, caspase-3 activity, and DNA degradation after induction of apoptosis with tumor necrosis factor-alpha. Overexpression of PTEN-C/S also enhanced VEGF-mediated endothelial cell proliferation and migration. In contrast, overexpression of wild-type PTEN inhibited the anti-apoptotic, proliferative, and chemotactic effects of VEGF. Moreover, PTEN-C/S increased the length of vascular sprouts in the rat aortic ring assay and modulated VEGF-mediated tube formation in an in vitro angiogenesis assay, whereas PTEN-wild type inhibited these effects. Taken together, these findings demonstrate that PTEN potently modulates VEGF-mediated signaling and function and that PTEN is a viable target in therapeutic approaches to promote or inhibit angiogenesis.
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Affiliation(s)
- Jianhua Huang
- Department of Medicine, Division of Cardiology and Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
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183
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184
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Zysman MA, Chapman WB, Bapat B. Considerations when analyzing the methylation status of PTEN tumor suppressor gene. THE AMERICAN JOURNAL OF PATHOLOGY 2002; 160:795-800. [PMID: 11891178 PMCID: PMC1867163 DOI: 10.1016/s0002-9440(10)64902-4] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Epigenetic mechanisms of gene silencing, including promoter hypermethylation of tumor suppressor genes, have been shown to contribute to tumorigenesis. PTEN is an important tumor suppressor implicated in the pathogenesis of a number of familial and sporadic cancers. Germline mutations of PTEN predispose to dominantly inherited hamartomatous disorders Cowden syndrome and Bannayan-Zonana syndrome. Somatic PTEN mutations commonly occur in endometrial, breast, prostate, and thyroid tumors. Several investigators have speculated on PTEN promoter hypermethylation as a possible mechanism of PTEN inactivation but data supporting such observations is not forthcoming. The genomic sequence of PTEN is 98% identical to a highly conserved processed PTEN pseudogene (psiPTEN) and this sequence identity extends 841 base pairs into the promoter region. This high degree of homology has made analysis of the methylation status of the PTEN promoter quite challenging. We have investigated the methylation profiles of the promoter region of PTEN in endometrial, breast, and colon cancer cell lines, as well as in a panel of primary endometrial tumors using a combination of methylation-specific polymerase chain reaction, methylation-sensitive restriction analysis, and bisulfite sequencing. Our results show that the pseudogene, and not PTEN, is predominantly methylated in cell lines and tumors. Without careful consideration of the critical nucleotide differences between the two sequences, results obtained from PTEN analysis may not necessarily represent the methylation status of PTEN.
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Affiliation(s)
| | | | - Bharati Bapat
- MountSinai Hospital; Toronto; the University HealthNetwork,†
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185
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Abstract
Several recent advances have been made in our understanding of the pathogenesis of endometrial tumours, particularly endometrioid endometrial carcinoma (EEC). Mutations in the PTEN gene and microsatellite instability (MSI) are common genetic abnormalities in EECs, and distinguish these lesions from other histological subtypes of endometrial carcinoma. Endometrial precancers are monoclonal lesions that share a common genetic lineage with invasive EEC, including PTEN mutations and MSI. Mutations of the PTEN tumour suppressor gene have been identified in histologically normal-appearing endometrium exposed to oestrogen, 18-55% of endometrial precancers and 26-80% of EECs. PTEN has been shown to play several roles in tumour suppression, including cell cycle arrest and promotion of apoptosis. Loss of PTEN function predisposes endometrial cells to neoplastic transformation, particularly in high-oestrogenic states. MSI is another common alteration seen in EECs and endometrial precancers, and some studies have reported an association between MSI and PTEN mutations. The replication error that results in MSI may facilitate the development of PTEN mutations in some, but not all, cases of EEC. The prognostic significance of PTEN gene mutations and MSI in endometrial carcinoma is controversial. Further study is needed to delineate the different pathogenetic pathways of EEC and their natural history.
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Affiliation(s)
- Eleanor Latta
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
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186
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Kwabi-Addo B, Giri D, Schmidt K, Podsypanina K, Parsons R, Greenberg N, Ittmann M. Haploinsufficiency of the Pten tumor suppressor gene promotes prostate cancer progression. Proc Natl Acad Sci U S A 2001; 98:11563-8. [PMID: 11553783 PMCID: PMC58769 DOI: 10.1073/pnas.201167798] [Citation(s) in RCA: 259] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2001] [Indexed: 01/20/2023] Open
Abstract
The PTEN gene encodes a lipid phosphatase that negatively regulates the phosphatidylinositol 3-kinase pathway and is inactivated in a wide variety of malignant neoplasms. High rates of loss of heterozygosity are observed at the 10q23.3 region containing the human PTEN gene in prostate cancer and other human malignancies, but the demonstrated rate of biallelic inactivation of the PTEN gene by mutation or homozygous deletion is significantly lower than the rate of loss of heterozygosity. The transgenic adenocarcinoma of mouse prostate model is a well characterized animal model of prostate cancer. Analysis of prostate cancer progression in transgenic adenocarcinoma of mouse prostate mice bred to Pten(+/-) heterozygous mice, coupled with analysis of the Pten gene and protein in the resulting tumors, reveals that haploinsufficiency of the Pten gene promotes the progression of prostate cancer in this model system. This observation provides a potential explanation for the discordance in rates of loss of heterozygosity at 10q23 and biallelic PTEN inactivation observed in prostate cancer and many human malignancies.
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Affiliation(s)
- B Kwabi-Addo
- Department of Pathology and Cell Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
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187
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Mills GB, Lu Y, Kohn EC. Linking molecular therapeutics to molecular diagnostics: inhibition of the FRAP/RAFT/TOR component of the PI3K pathway preferentially blocks PTEN mutant cells in vitro and in vivo. Proc Natl Acad Sci U S A 2001; 98:10031-3. [PMID: 11526226 PMCID: PMC56908 DOI: 10.1073/pnas.191379498] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- G B Mills
- Department of Molecular Therapeutics, MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, USA.
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188
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Affiliation(s)
- G L Mutter
- Department of Pathology, Brigham and Women's Hospital, and Harvard Medical School, Boston, Massachusetts 02115, USA.
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