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Clark AD, Oldenbroek M, Boyer TG. Mediator kinase module and human tumorigenesis. Crit Rev Biochem Mol Biol 2015; 50:393-426. [PMID: 26182352 DOI: 10.3109/10409238.2015.1064854] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Mediator is a conserved multi-subunit signal processor through which regulatory informatiosn conveyed by gene-specific transcription factors is transduced to RNA Polymerase II (Pol II). In humans, MED13, MED12, CDK8 and Cyclin C (CycC) comprise a four-subunit "kinase" module that exists in variable association with a 26-subunit Mediator core. Genetic and biochemical studies have established the Mediator kinase module as a major ingress of developmental and oncogenic signaling through Mediator, and much of its function in signal-dependent gene regulation derives from its resident CDK8 kinase activity. For example, CDK8-targeted substrate phosphorylation impacts transcription factor half-life, Pol II activity and chromatin chemistry and functional status. Recent structural and biochemical studies have revealed a precise network of physical and functional subunit interactions required for proper kinase module activity. Accordingly, pathologic change in this activity through altered expression or mutation of constituent kinase module subunits can have profound consequences for altered signaling and tumor formation. Herein, we review the structural organization, biological function and oncogenic potential of the Mediator kinase module. We focus principally on tumor-associated alterations in kinase module subunits for which mechanistic relationships as opposed to strictly correlative associations are established. These considerations point to an emerging picture of the Mediator kinase module as an oncogenic unit, one in which pathogenic activation/deactivation through component change drives tumor formation through perturbation of signal-dependent gene regulation. It follows that therapeutic strategies to combat CDK8-driven tumors will involve targeted modulation of CDK8 activity or pharmacologic manipulation of dysregulated CDK8-dependent signaling pathways.
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Affiliation(s)
- Alison D Clark
- a Department of Molecular Medicine , Institute of Biotechnology, University of Texas Health Science Center at San Antonio , San Antonio , TX , USA
| | - Marieke Oldenbroek
- a Department of Molecular Medicine , Institute of Biotechnology, University of Texas Health Science Center at San Antonio , San Antonio , TX , USA
| | - Thomas G Boyer
- a Department of Molecular Medicine , Institute of Biotechnology, University of Texas Health Science Center at San Antonio , San Antonio , TX , USA
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Abstract
From 1976 to 2010, only 2 medications were approved for treating metastatic melanoma. Between 2011 and 2013, 4 agents were approved and other therapies have shown great promise in clinical trials. Fundamental discoveries, such as the identification of oncogenic mutations in most melanomas, the elucidation of the molecular signaling resulting from these mutations, and the revelation that several cell surface molecules serve as regulators of immune activation, have been instrumental in this progress. This article summarizes the molecular pathogenesis of melanoma, describes the current efforts to target oncogene-driven signaling, and presents the rationale for combining immune and molecular targeting.
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Affiliation(s)
- Ryan J Sullivan
- Center for Melanoma, Massachusetts General Hospital Cancer Center, Harvard Medical School, 55 Fruit Street, Boston, MA 02114, USA
| | - David E Fisher
- Department of Dermatology, Massachusetts General Hospital Cancer Center, Harvard Medical School, Bartlett 6, 55 Fruit Street, Boston, MA 02114, USA.
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Chan D, Zheng Y, Tyner JW, Chng WJ, Chien WW, Gery S, Leong G, Braunstein GD, Koeffler HP. Belinostat and panobinostat (HDACI): in vitro and in vivo studies in thyroid cancer. J Cancer Res Clin Oncol 2013; 139:1507-14. [PMID: 23824064 PMCID: PMC3742422 DOI: 10.1007/s00432-013-1465-6] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Accepted: 06/19/2013] [Indexed: 01/07/2023]
Abstract
Purpose
Advanced thyroid cancer responds poorly to most therapies. New therapies and combinations are needed. The aim of this study was to examine both in vitro and in vivo activity of two relatively new histone deacetylase inhibitors (HDACIs), belinostat and panobinostat, and a variety of tyrosine kinase inhibitors (TKIs) against a panel of nine human thyroid cancer cell lines. Methods
The anti-proliferative activity and the effects of HDACIs, TKIs and their combinations on thyroid cancer cells were determined by cytotoxicity assays, microarray and immunoblot analyses. Synergism between HDACIs and TKIs was assessed by the median effects model of Chou-Talalay (Calcusyn®). Results Belinostat and panobinostat were active against the thyroid cancer cell lines irrespective of their mutational composition, and belinostat was effective in preventing growth of human thyroid cancer xenografts in immunodeficient mice. Further studies showed that both HDACIs induced apoptosis. HDACI also elevated acetylated histone 3, p21Waf, and PARP, and decreased levels of phosphorylated ERK and AKT (Ser473). RNA assay analysis suggested both HDACIs modulated genes associated with the cell cycle, DNA damage and apoptosis. Most of the TKI (pazopanib, motesanib, sorafenib and dasatinib) were either inactive in vitro or were active only at high doses. However, the novel combinations of either pazopanib or dasatinib TKIs with either belinostat or panobinostat synergistically inhibited cell growth of thyroid cancer cells in vitro. Conclusions In summary, these HDACIs either alone or combined with selected TKIs may have a role in treatment of aggressive thyroid cancer. Electronic supplementary material The online version of this article (doi:10.1007/s00432-013-1465-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Daniel Chan
- National University Hospital, National University Cancer Institute Singapore, 1E Kent Ridge Road, Singapore, 119228, Singapore
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Bhaskaran S, Dileep KV, Deepa SS, Sadasivan C, Klausner M, Krishnegowda NK, Tekmal RR, VandeBerg JL, Nair HB. Gossypin as a Novel Selective Dual Inhibitor of v-raf Murine Sarcoma Viral Oncogene Homolog B1 and Cyclin-Dependent Kinase 4 for Melanoma. Mol Cancer Ther 2013; 12:361-72. [DOI: 10.1158/1535-7163.mct-12-0965] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Patricelli MP, Nomanbhoy TK, Wu J, Brown H, Zhou D, Zhang J, Jagannathan S, Aban A, Okerberg E, Herring C, Nordin B, Weissig H, Yang Q, Lee JD, Gray NS, Kozarich JW. In situ kinase profiling reveals functionally relevant properties of native kinases. ACTA ACUST UNITED AC 2011; 18:699-710. [PMID: 21700206 DOI: 10.1016/j.chembiol.2011.04.011] [Citation(s) in RCA: 272] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2010] [Revised: 03/21/2011] [Accepted: 04/04/2011] [Indexed: 12/20/2022]
Abstract
Protein kinases are intensely studied mediators of cellular signaling, yet important questions remain regarding their regulation and in vivo properties. Here, we use a probe-based chemoprotemics platform to profile several well studied kinase inhibitors against >200 kinases in native cell proteomes and reveal biological targets for some of these inhibitors. Several striking differences were identified between native and recombinant kinase inhibitory profiles, in particular, for the Raf kinases. The native kinase binding profiles presented here closely mirror the cellular activity of these inhibitors, even when the inhibition profiles differ dramatically from recombinant assay results. Additionally, Raf activation events could be detected on live cell treatment with inhibitors. These studies highlight the complexities of protein kinase behavior in the cellular context and demonstrate that profiling with only recombinant/purified enzymes can be misleading.
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Gril B, Palmieri D, Qian Y, Anwar T, Ileva L, Bernardo M, Choyke P, Liewehr DJ, Steinberg SM, Steeg PS. The B-Raf status of tumor cells may be a significant determinant of both antitumor and anti-angiogenic effects of pazopanib in xenograft tumor models. PLoS One 2011; 6:e25625. [PMID: 21998674 PMCID: PMC3187787 DOI: 10.1371/journal.pone.0025625] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2011] [Accepted: 09/08/2011] [Indexed: 12/12/2022] Open
Abstract
Pazopanib is an FDA approved Vascular Endothelial Growth Factor Receptor inhibitor. We previously reported that it also inhibits tumor cell B-Raf activity in an experimental brain metastatic setting. Here, we determine the effects of different B-Raf genotypes on pazopanib efficacy, in terms of primary tumor growth and anti-angiogenesis. A panel of seven human breast cancer and melanoma cell lines harboring different mutations in the Ras-Raf pathway was implanted orthotopically in mice, and tumor growth, ERK1/2, MEK1/2 and AKT activation, and blood vessel density and permeability were analyzed. Pazopanib was significantly inhibitory to xenografts expressing either exon 11 mutations of B-Raf, or HER2 activated wild type B-Raf; no significant inhibition of a xenograft expressing the common V600E B-Raf mutation was observed. Decreased pMEK staining in the responsive tumors confirmed that B-Raf was targeted by pazopanib. Interestingly, pazopanib inhibition of tumor cell B-Raf also correlated with its anti-angiogenic activity, as quantified by vessel density and area. In conclusion, using pazopanib, tumor B-Raf status was identified as a significant determinant of both tumor growth and angiogenesis.
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Affiliation(s)
- Brunilde Gril
- Women's Cancers Section, Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland, United States of America.
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Gerami P, Jewell SS, Pouryazdanparast P, Wayne JD, Haghighat Z, Busam KJ, Rademaker A, Morrison L. Copy number gains in 11q13 and 8q24 [corrected] are highly linked to prognosis in cutaneous malignant melanoma. J Mol Diagn 2011; 13:352-8. [PMID: 21497295 DOI: 10.1016/j.jmoldx.2011.01.011] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2010] [Accepted: 01/31/2011] [Indexed: 10/18/2022] Open
Abstract
Relating specific genetic alterations to prognosis may help improve prognostication in melanoma, may identify key oncogenic drivers in cancer, and may assist in developing targeted therapies. Characteristic genetic alterations in melanoma include chromosomal copy number aberrations. We evaluated 97 melanomas (55 metastasizing and 42 nonmetastasizing) after a minimum 5-year follow-up in a case-control study using fluorescence in situ hybridization, targeting commonly altered chromosomal loci in melanoma. Eight probes arranged in two panels were used, and 11 parameters were evaluated. Parameters showing a statistically significant difference between the metastasizing and nonmetastasizing groups were evaluated with multivariate logistic regression analysis to compare their prognostic potential with other traditional prognostic markers used by the American Joint Committee on Cancer. Four of 11 parameters evaluated, including CCND1 (alias Bcl-1) gain, CCND1 r-gain, MYC (alias c-myc) gain, and MYC r-gain, had a statistically significant difference in the metastasizing versus nonmetastasizing group. All four parameters maintained statistical significance when evaluated in separate multivariate logistic regression analyses that included the seven currently used American Joint Commission on Cancer prognosticators in melanoma. In multivariate analyses, these four parameters were second only to ulceration in their prognostic potential. Copy number changes at 11q13 and 8q24 [corrected] harboring CCND1 and MYC, respectively, are highly associated with prognosis. Fluorescence in situ hybridization targeting these loci may be a useful standardized prognostic marker in melanoma skin cancer.
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Affiliation(s)
- Pedram Gerami
- Department of Dermatology, Feinberg School of Medicine, Northwestern University, 676 N. St Clair Street, Chicago, IL 60611, USA.
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Scolyer RA, Prieto VG. Melanoma pathology: important issues for clinicians involved in the multidisciplinary care of melanoma patients. Surg Oncol Clin N Am 2011; 20:19-37. [PMID: 21111957 DOI: 10.1016/j.soc.2010.09.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Histologic analysis remains the gold standard for diagnosis of melanoma. The pathology report should document those histologic features important for guiding patient management, including those characteristics on which the diagnosis was based and also prognostic factors. Pathologic examination of sentinel lymph nodes provides very important prognostic information. New techniques, such as comparative genomic hybridization and fluorescence in situ hybridization are currently being studied to determine their usefulness in the diagnosis of melanocytic lesions. Recent molecular studies have opened new avenues for the treatment of patients with metastatic melanoma (ie, targeted therapies) and molecular pathology is likely to play an important role in the emerging area of personalized melanoma therapy.
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Affiliation(s)
- Richard A Scolyer
- Tissue Pathology and Diagnostic Oncology, Royal Prince Alfred Hospital, Missenden Road, Camperdown, Sydney, NSW 2050, Australia.
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Karki P, Li X, Schrama D, Fliegel L. B-Raf associates with and activates the NHE1 isoform of the Na+/H+ exchanger. J Biol Chem 2011; 286:13096-105. [PMID: 21345796 PMCID: PMC3075656 DOI: 10.1074/jbc.m110.165134] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2010] [Revised: 02/03/2011] [Indexed: 01/03/2023] Open
Abstract
The serine/threonine kinase B-Raf is the second most frequently occurring human oncogene after Ras. Mutations of B-Raf occur with the highest incidences in melanoma, and the most common mutant, V600E, renders B-Raf constitutively active. The sodium proton exchanger isoform 1 (NHE1) is a ubiquitously expressed plasma membrane protein responsible for regulating intracellular pH, cell volume, cell migration, and proliferation. A screen of protein kinases that bind to NHE1 revealed that B-Raf bound to the cytosolic regulatory tail of NHE1. Immunoprecipitation of NHE1 from HeLa and HEK cells confirmed the association of B-Raf with NHE1 in vivo. The expressed and purified C-terminal 182 amino acids of the NHE1 protein were also shown to associate with B-Raf protein in vitro. Because treatment with the kinase inhibitor sorafenib decreased NHE1 activity in HeLa and HEK cells, we examined the role of B-Raf in regulating NHE1 in malignant melanoma cells. Melanoma cells with the B-Raf(V600E) mutation demonstrated increased resting intracellular pH that was dependent on elevated NHE1 activity. NHE1 activity after an acute acid load was also elevated in these cell lines. Moreover, inhibition of B-Raf activity by either sorafenib, PLX4720, or siRNA reduction of B-Raf levels abolished ERK phosphorylation and decreased NHE1 activity. These results demonstrate that B-Raf associates with and stimulates NHE1 activity and that B-Raf(V600E) also increases NHE1 activity that raises intracellular pH.
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Affiliation(s)
- Pratap Karki
- From the Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada and
| | - Xiuju Li
- From the Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada and
| | - David Schrama
- the Division of Dermatology, Medical University of Graz, 8036 Graz, Austria
| | - Larry Fliegel
- From the Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada and
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Smith AG, Lim W, Pearen M, Muscat GEO, Sturm RA. Regulation of NR4A nuclear receptor expression by oncogenic BRAF in melanoma cells. Pigment Cell Melanoma Res 2011; 24:551-63. [PMID: 21362156 DOI: 10.1111/j.1755-148x.2011.00843.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Activating mutations in the MAPK pathway effectors, NRAS or BRAF, are detected in over 70% of melanomas. Accordingly, the identification of downstream targets of constitutive MAPK signalling in melanoma represents a major goal in understanding the genesis of this disease. We report here the regulation of members of the NR4A family of nuclear receptors by the BRAF-MEK-ERK cascade in melanoma cells. Expression profiling of melanoma cells in which both the NR4A1 and NR4A2 family members have been down-regulated by siRNA revealed alterations in genes associated with proliferation, survival and invasiveness of tumour cells. Notably, the up-regulation of Wnt/β-catenin pathway antagonists, DACT1 and CITED1, following NR4A1/2 ablation suggests a possible link between NR4A and β-catenin activity in melanoma cells. Taken together, these data suggest that dysregulation of NR4A nuclear receptors expression and function by the MAPK pathway may contribute to melanoma tumourigenicity.
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Affiliation(s)
- Aaron G Smith
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, Australia.
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Lymph Node Ratio Provides Prognostic Information in Addition to American Joint Committee on Cancer N Stage in Patients With Melanoma, Even If Quality of Surgery Is Standardized. Ann Surg 2011; 253:109-15. [DOI: 10.1097/sla.0b013e3181f9b8b6] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Gene signature in melanoma associated with clinical activity: a potential clue to unlock cancer immunotherapy. Cancer J 2010; 16:399-403. [PMID: 20693853 DOI: 10.1097/ppo.0b013e3181eacbd8] [Citation(s) in RCA: 204] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Immunotherapeutic approaches for melanoma and other cancers can impart profound clinical benefit but only for a subset of patients. Interpatient heterogeneity could, in principle, be due to somatic differences in the tumor between individuals or alternatively be accounted for distinct germline polymorphisms in immunoregulatory genes of the host. Analysis of these possibilities has been initiated by investigating gene expression profiling of the tumor microenvironment in the context of clinical trials of cancer vaccines. Distinct gene expression profiles have been identified on pretreatment biopsies that are associated with a positive or negative clinical outcome. These observations suggest that such profiling might be useful as a predictive biomarker for clinical benefit from vaccines and other immunotherapy approaches, and analysis of specific gene products has begun to suggest new therapeutic interventions to overcome mechanisms of tumor resistance.
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Current World Literature. Curr Opin Support Palliat Care 2010; 4:293-304. [DOI: 10.1097/spc.0b013e328340e983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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