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Abstract
Despite considerable efforts to improve the diagnosis and treatment of lung cancer, this disease remains the leading cause of cancer-related mortality worldwide. Recent elucidation of epigenetic regulation of gene expression during malignant transformation, together with the identification of agents that modulate DNA methylation and histone acetylation, provide new opportunities for the treatment and prevention of lung cancer via chromatin remodeling mechanisms. Further analysis of molecular response in tumor tissues following exposure to chromatin remodeling agents may enable us to identify novel mechanisms pertaining to lung cancer epigenetics, and design more efficacious regimens.
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Affiliation(s)
- David S Schrump
- Thoracic Oncology Section, Surgery Branch, Center for Cancer Research, National Cancer Institute, Room 4-3940, 10 Center Drive, MSC 1201, Bethesda, MD 20892-1201, USA.
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2
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Abstract
Gene therapy for mesothelioma is currently in its adolescence. The expansion of knowledge regarding molecular aspects of mesothelioma carcinogenesis has facilitated the development of promising gene therapy modalities that target specific oncoproteins and mutant tumor suppressor genes. Although implementation of any of these gene therapy approaches as part of standard medical care for patients who have mesothelioma remains years in the future, the field is finally progressing toward more definitive phase II/III efficacy studies. Unfortunately, the marginal benefits garnered from standard anticancer treatments in mesothelioma argue strongly for continued participation in clinical studies of various experimental approaches, particularly gene therapy. These trials serve multiple purposes: to establish safety, determine proper dosing, evaluate for efficacy, and, in an iterative fashion, guide future avenues of laboratory investigation.
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Affiliation(s)
- Daniel H Sterman
- Thoracic Oncology Research Laboratory, Pulmonary, Allergy, and Critical Care Division, Department of Medicine, University of Pennsylvania Medical Center, Philadelphia, PA 19104-4283, USA.
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White MK, Khalili K. Expression of JC virus regulatory proteins in human cancer: potential mechanisms for tumourigenesis. Eur J Cancer 2005; 41:2537-48. [PMID: 16219459 DOI: 10.1016/j.ejca.2005.08.019] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
JC virus (JCV) is a human polyomavirus that is the etiologic agent of the fatal demyelinating disease of the central nervous system known as progressive multifocal leukoencephalopathy (PML). JCV is also linked to some tumours of the brain and other organs as evidenced by the presence of JCV DNA sequences and the expression of viral proteins in clinical samples. Since JCV is highly oncogenic in experimental animals and transforms cells in culture, it is possible that JCV contributes to the malignant phenotype of human tumours with which it is associated. JCV encodes three non-capsid regulatory proteins: large T-antigen, small t-antigen and agnoprotein that interact with a number of cellular target proteins and interfere with certain normal cellular functions. In this review, we discuss how JCV proteins deregulate signalling pathways especially ones pertaining to transcriptional regulation and cell cycle control. These effects may be involved in the progression of JCV-associated tumours and may represent potential therapeutic targets.
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Affiliation(s)
- Martyn K White
- Center for Neurovirology, Department of Neuroscience, Temple University School of Medicine, 1900 North 12th Street, MS 015-96, Room 203, Philadelphia, PA 19122, USA
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White MK, Gordon J, Reiss K, Del Valle L, Croul S, Giordano A, Darbinyan A, Khalili K. Human polyomaviruses and brain tumors. ACTA ACUST UNITED AC 2005; 50:69-85. [PMID: 15982744 DOI: 10.1016/j.brainresrev.2005.04.007] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2004] [Revised: 04/12/2005] [Accepted: 04/21/2005] [Indexed: 12/25/2022]
Abstract
Polyomaviruses are DNA tumor viruses with small circular genomes. Three polyomaviruses have captured attention with regard to their potential role in the development of human brain tumors: JC virus (JCV), BK virus (BKV), and simian vacuolating virus 40 (SV40). JCV is a neurotropic polyomavirus that is the etiologic agent of progressive multifocal leukoencephalopathy (PML), a fatal demyelinating disease of the central nervous system occurring mainly in AIDS patients. BKV is the causative agent of polyomavirus-associated nephropathy (PVN) which occurs after renal transplantation when BKV reactivates from a latent state during immunosuppressive therapy to cause allograft failure. SV40, originating in rhesus monkeys, gained notoriety when it entered the human population via contaminated polio vaccines. All three viruses are highly oncogenic when injected into the brain of experimental animals. Reports indicate that these viruses, especially JCV, are associated with brain tumors and other cancers in humans as evidenced from the analysis of clinical samples for the presence of viral DNA sequences and expression of viral proteins. Human polyomaviruses encode three non-capsid regulatory proteins: large T-antigen, small t-antigen, and agnoprotein. These proteins interact with a number of cellular target proteins to exert effects that dysregulate pathways involved in the control of various host cell functions including the cell cycle, DNA repair, and others. In this review, we describe the three polyomaviruses, their abilities to cause brain and other tumors in experimental animals, the evidence for an association with human brain tumors, and the latest findings on the molecular mechanisms of their actions.
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Affiliation(s)
- Martyn K White
- Center for Neurovirology and Cancer Biology, College of Science and Technology, Temple University, 1900 North 12th Street, 015-96, Room 203, Philadelphia, PA 19122, USA
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Nguyen DM, Schrump WD, Chen GA, Tsai W, Nguyen P, Trepel JB, Schrump DS. Abrogation of p21 Expression by Flavopiridol Enhances Depsipeptide-Mediated Apoptosis in Malignant Pleural Mesothelioma Cells. Clin Cancer Res 2004; 10:1813-25. [PMID: 15014036 DOI: 10.1158/1078-0432.ccr-0901-3] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE Recent insights regarding the pathogenesis of malignant pleural mesothelioma (MPM) provide new opportunities for targeted molecular therapies for this highly lethal disease. The present study was undertaken to examine the effects of the histone deacetylase inhibitor, Depsipeptide (DP) FK228, in conjunction with the cyclin-dependent kinase inhibitor, Flavopiridol (FLA), in cultured MPM cells. EXPERIMENTAL DESIGN Proliferation and apoptosis in drug-treated, virally transduced, or control cells were assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and Apo-bromodeoxyuridine techniques. Western blot and ELISA techniques were used to examine signal transduction and cell cycle-related protein levels in MPM cells exposed to DP and/or FLA in the presence or absence of calphostin, phorbol-12,13-dibutyrate, 5,6-dichloro-1-beta-D-ribofuranosyl-benzimidazole, or adenoviral p21 transduction. RESULTS DP (1-50 ng/ml x 6 h) or FLA (100-200 nM x 72 h) alone, mediated low-level, dose-dependent growth inhibition in MPM cells. In contrast, sequential DP/FLA treatment mediated marked growth inhibition and apoptosis in these cell lines. The cytotoxic effects of DP/FLA were considerably less pronounced in cultured normal cells. The proapoptotic effects of DP/FLA treatment coincided with inhibition of DP-mediated induction of p21 by FLA. Overexpression of p21 by adenoviral gene transfer techniques rendered MPM cells refractory to the cytotoxic effects of this treatment regimen. In p21 reporter assays, promoter activation by DP was antagonized by FLA. The magnitude of inhibition of DP-mediated p21 induction by FLA exceeded that observed with the pTEFb antagonist 5,6-dichloro-1-beta-D-ribofuranosyl-benzimidazole. Calphostin C abrogated p21 induction mediated by DP and enhanced DP-mediated apoptosis in a manner comparable with FLA in MPM cells; in contrast, phorbol-12,13-dibutyrate blocked FLA-mediated inhibition of p21 induction by DP and markedly protected these cells from the apoptotic effects of sequential DP/FLA. CONCLUSIONS FLA abrogates DP-mediated induction of p21 expression, in part, via inhibition of protein kinase C signaling and markedly potentiates the cytotoxic effects of DP in MPM cells.
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Affiliation(s)
- Dao M Nguyen
- Thoracic Oncology Section, Surgery Branch, and Medical Oncology Clinical Research Unit, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, Maryland 20892-1502, USA
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Schrump DS, Nguyen DM, Kunst TE, Hancox A, Figg WD, Steinberg SM, Pishchik V, Becerra Y. Phase I study of sequential deoxyazacytidine/depsipeptide infusion in patients with malignancies involving lungs or pleura. Clin Lung Cancer 2004; 4:186-92. [PMID: 14706169 DOI: 10.3816/clc.2002.n.027] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- David S Schrump
- Thoracic Oncology Section, Surgery Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892-1502, USA.
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Bocchetta M, Miele L, Pass HI, Carbone M. Notch-1 induction, a novel activity of SV40 required for growth of SV40-transformed human mesothelial cells. Oncogene 2003; 22:81-9. [PMID: 12527910 DOI: 10.1038/sj.onc.1206097] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We show that SV40 infection of human mesothelial cells directly causes overexpression of Notch-1, a key cell regulatory gene. Notch-1 induction is achieved at the transcriptional level and requires both the SV40 large T-antigen and the small t-antigen. Notch-1 upregulation is maintained in SV40-transformed human mesothelial clones and in SV40-positive mesotheliomas and derived cell lines. Activation of Notch-1 promotes cell cycle progression and it is required for the growth of SV40-transformed mesothelial cells. Our finding is relevant to the process of SV40-mediated human cell transformation, an effect that cannot be accounted for solely by SV40-Tag inhibition of Rb and p53.
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Affiliation(s)
- Maurizio Bocchetta
- Department of Pathology, Cardinal Bernardin Cancer Center, Loyola University Chicago, Maywood, IL 60153, USA
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Wong M, Pagano JS, Schiller JT, Tevethia SS, Raab-Traub N, Gruber J. New associations of human papillomavirus, Simian virus 40, and Epstein-Barr virus with human cancer. J Natl Cancer Inst 2002; 94:1832-6. [PMID: 12488476 DOI: 10.1093/jnci/94.24.1832] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Affiliation(s)
- May Wong
- Biological Carcinogenesis Branch, National Cancer Institute, Bethesda, MD 20892, USA.
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Abstract
An increasing number of scientific reports have described evidence for a polyomavirus, simian virus 40, in a highly select group of human tumours. How did a simian virus infect humans and is the virus a passenger in tumours or is it important in their pathogenesis?
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Affiliation(s)
- Adi F Gazdar
- Hamon Center for Therapeutic Oncology Research and Department of Pathology, University of Texas Southwestern Medical Centre, Dallas, Texas 75390, USA
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10
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Foddis R, De Rienzo A, Broccoli D, Bocchetta M, Stekala E, Rizzo P, Tosolini A, Grobelny JV, Jhanwar SC, Pass HI, Testa JR, Carbone M. SV40 infection induces telomerase activity in human mesothelial cells. Oncogene 2002; 21:1434-42. [PMID: 11857086 DOI: 10.1038/sj.onc.1205203] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2001] [Revised: 11/09/2001] [Accepted: 11/27/2001] [Indexed: 11/09/2022]
Abstract
Mesotheliomas are malignant tumors of the pleural and peritoneal membranes which are often associated with asbestos exposure and with Simian virus 40 (SV40) infection. Telomerase activity is repressed in somatic cells and tissues but is activated in immortal and malignant cells. We evaluated telomerase activity in seven primary malignant mesothelioma biopsies and matched lung specimens and 20 mesothelioma cell lines and eight corresponding primary tumor cultures. All the tumor biopsies, and nearly all primary cell mesothelioma cultures and cell lines were telomerase positive. The findings in cell lines paralleled those observed in primary cultures in cases where paired samples were available. Next, we found that SV40, a DNA tumor virus present in approximately 50% of mesothelioma biopsies in the USA, induced telomerase activity in primary human mesothelial cells, but not in primary fibroblasts. Telomerase activity became detectable as early as 72 h following wild-type (strain 776) SV40 infection, and a clear DNA ladder was detectable 1 week after infection. The amount of telomerase activity increased during passage in cell culture and appeared to parallel increases in the cellular amounts of the SV40 large T-antigen. Thus, SV40 infection leads to telomerase activity before the infected mesothelial cells become transformed and immortalized. SV40 infection of human fibroblasts did not cause detectable telomerase activity. We also determined that the SV40 small t-antigen (tag) plays an important role in inducing telomerase activity because this activity was undetectable or minimal in mesothelial cells infected and/or transformed by SV40 tag mutants. Asbestos alone did not induce telomerase activity, and asbestos did not influence telomerase activity in mesothelial cells infected with SV40. Induction of telomerase activity by SV40 may be related to the very high rate of mesothelial cell immortalization that is characteristically associated with SV40 infection of mesothelial cells.
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Affiliation(s)
- Rudy Foddis
- Cancer Immunology Program, Department of Pathology, Cardinal Bernardin Cancer Center, Loyola University Chicago, Maywood, Illinois, IL 60153, USA
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Klein G, Powers A, Croce C. Association of SV40 with human tumors. Oncogene 2002; 21:1141-9. [PMID: 11850833 DOI: 10.1038/sj.onc.1205173] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2001] [Revised: 11/02/2001] [Accepted: 11/07/2001] [Indexed: 11/09/2022]
Abstract
In 1994, PCR and protein studies suggested that SV40 DNA sequences and proteins were present in 29/48 (60%) USA human mesothelioma samples. Sequence analysis confirmed that the sequences were homologous to SV40. One year later, SV40 was also found in 5/9 human mesotheliomas, and in 1996 SV40 was also reported to be present in 1/3 of the tumor specimens examined. These reports, in combination with an earlier study in 1992 which had detected SV40 in human brain tumors, raised concerns that SV40 was associated with certain types of human tumors, specifically mesothelioma, bone, and brain tumors. These findings raised concerns, because these tumor types are the same malignancies that had been observed in animals injected with SV40. However, a study in 1996 and a presentation made at the International Mesothelioma Interest Group, IMIG in 1997 failed to detect SV40 in mesotheliomas, suggesting the possibility that laboratory artifacts, such as PCR contamination, had caused the previous positive findings. In 1997, the FDA, the NIH, and the CDC organized an international conference in Bethesda to review the literature and to address the possibility that SV40 was present in, and was possibly the cause of, some human tumors. The results of that conference were reported the same year in a meeting review in Oncogene by Carbone and colleagues. Briefly, the consensus was that before accepting the possibility that SV40 was present in human tumors, a multi-laboratory study needed to be conducted. It was recommended that a blinded multi-laboratory study be directed by an independent scientist not previously associated with the controversial reports of SV40 in human specimens. It was also recommended that this study include laboratories that had reported positive findings as well as laboratories that had failed to detect SV40 in human specimens. Since 1997, about 30 independent reports have been published on this topic, including the multi-laboratory study. Evidence in favor and against a possible association of SV40 with human cancer was reviewed at an international consensus meeting at the University of Chicago on 20, 21 April 2001, entitled "Malignant Mesothelioma: Therapeutic Options and the Role of SV40, 2001". The main focus was the association of SV40 with mesothelioma and other human tumors. At the end of the meeting, a panel discussion, which included independent experts who had not published on this topic, critically reviewed the evidence presented at the meeting. The results of the meeting and of the final panel discussion are outlined below.
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Affiliation(s)
- George Klein
- Microbiology and Tumor Biology Center, Karolinska Institut, S 171-77, Stockholm, Sweden
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Stewart JH, Nguyen DM, Chen GA, Schrump DS. Induction of apoptosis in malignant pleural mesothelioma cells by activation of the Fas (Apo-1/CD95) death-signal pathway. J Thorac Cardiovasc Surg 2002; 123:295-302. [PMID: 11828289 DOI: 10.1067/mtc.2002.119882] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVE Although well characterized in several solid tumors, the effects of Fas/Fas ligand interactions in malignant pleural mesothelioma cells have not been defined. The present study was undertaken to examine the functional status of the Fas/Fas ligand pathway in malignant pleural mesothelioma cells and to determine the feasibility of targeting this death-signal pathway for molecular intervention in patients with mesotheliomas. METHODS Fas expression in primary normal human bronchial epithelial cells and 6 malignant pleural mesothelioma cell lines was quantified by means of flow cytometry. The caspase components of the Fas-mediated apoptotic pathway were evaluated by means of Western blot techniques. Soluble Fas ligand-mediated cytotoxicity and apoptosis were evaluated by means of MTS and TUNEL assays, respectively. Cisplatin (3 microg/mL) and lymphokine-activated killer cells were used to enhance mesothelioma sensitivity to soluble Fas ligand. An H2373 nude mouse xenograft model of malignant pleural mesothelioma was established to assess the in vivo effects of soluble Fas ligand. RESULTS Four of 6 malignant pleural mesothelioma lines exhibited high levels of Fas expression, and 2 of 4 were inherently susceptible to soluble Fas ligand-mediated cytotoxicity (soluble Fas ligand 50% inhibitory concentration, < 15 ng/mL). Two soluble Fas ligand refractory cell lines (H2052 and H513) exhibited high levels of Fas receptor. Pretreatment with cisplatin resulted in a reduction of 50% inhibitory concentration from infinity to 4.17 +/- 0.14 ng/mL and 10.23 +/- 1.58 ng/mL, respectively. Two additional soluble Fas ligand refractory cell lines (H2595 and REN) expressed low levels of Fas. Exposure of these cells to lymphokine-activated killer cells or lymphokine-activated killer cell-conditioned medium followed by a 24-hour treatment with cisplatin resulted in a significant reduction in 50% inhibitory concentration of soluble Fas ligand and pronounced induction of apoptosis. Intraperitoneally administered soluble Fas ligand mediated regression of H2373 xenografts. CONCLUSION The Fas/Fas ligand pathway in mesothelioma cells is either intrinsically intact or can be rendered functional with chemotherapeutic agents or immune effector cells. These preclinical data support further evaluation of strategies to enhance Fas-mediated apoptosis in mesotheliomas.
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Affiliation(s)
- John H Stewart
- National Institutes of Health, National Cancer Institute, Thoracic Oncology Section, Surgery Branch, Bethesda, MD 20892, USA
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