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Buczek ME, Miles AK, Green W, Johnson C, Boocock DJ, Pockley AG, Rees RC, Hulman G, van Schalkwyk G, Parkinson R, Hulman J, Powe DG, Regad T. Cytoplasmic PML promotes TGF-β-associated epithelial-mesenchymal transition and invasion in prostate cancer. Oncogene 2016; 35:3465-75. [PMID: 26549027 PMCID: PMC4932557 DOI: 10.1038/onc.2015.409] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2015] [Revised: 07/22/2015] [Accepted: 09/18/2015] [Indexed: 12/18/2022]
Abstract
Epithelial-mesenchymal transition (EMT) is a key event that is involved in the invasion and dissemination of cancer cells. Although typically considered as having tumour-suppressive properties, transforming growth factor (TGF)-β signalling is altered during cancer and has been associated with the invasion of cancer cells and metastasis. In this study, we report a previously unknown role for the cytoplasmic promyelocytic leukaemia (cPML) tumour suppressor in TGF-β signalling-induced regulation of prostate cancer-associated EMT and invasion. We demonstrate that cPML promotes a mesenchymal phenotype and increases the invasiveness of prostate cancer cells. This event is associated with activation of TGF-β canonical signalling pathway through the induction of Sma and Mad related family 2 and 3 (SMAD2 and SMAD3) phosphorylation. Furthermore, the cytoplasmic localization of promyelocytic leukaemia (PML) is mediated by its nuclear export in a chromosomal maintenance 1 (CRM1)-dependent manner. This was clinically tested in prostate cancer tissue and shown that cytoplasmic PML and CRM1 co-expression correlates with reduced disease-specific survival. In summary, we provide evidence of dysfunctional TGF-β signalling occurring at an early stage in prostate cancer. We show that this disease pathway is mediated by cPML and CRM1 and results in a more aggressive cancer cell phenotype. We propose that the targeting of this pathway could be therapeutically exploited for clinical benefit.
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Affiliation(s)
- M E Buczek
- John van Geest Cancer Research Centre, School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham, UK
| | - A K Miles
- John van Geest Cancer Research Centre, School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham, UK
| | - W Green
- Department of Urology, City Hospital, Nottingham University Hospitals NHS Trust, Nottingham, UK
| | - C Johnson
- John van Geest Cancer Research Centre, School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham, UK
| | - D J Boocock
- John van Geest Cancer Research Centre, School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham, UK
| | - A G Pockley
- John van Geest Cancer Research Centre, School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham, UK
| | - R C Rees
- John van Geest Cancer Research Centre, School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham, UK
| | - G Hulman
- Department of Cellular Pathology, Queen's Medical Centre, Nottingham University Hospitals Trust, Nottingham, UK
| | - G van Schalkwyk
- Department of Histopathology, Royal Derby Hospital, Derby, UK
| | - R Parkinson
- Department of Urology, City Hospital, Nottingham University Hospitals NHS Trust, Nottingham, UK
| | - J Hulman
- Department of Cellular Pathology, Queen's Medical Centre, Nottingham University Hospitals Trust, Nottingham, UK
| | - D G Powe
- John van Geest Cancer Research Centre, School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham, UK
- Department of Cellular Pathology, Queen's Medical Centre, Nottingham University Hospitals Trust, Nottingham, UK
| | - T Regad
- John van Geest Cancer Research Centre, School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham, UK
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Boocock DJ, Maggs JL, Brown K, White IN, Park BK. Major inter-species differences in the rates of O-sulphonation and O-glucuronylation of alpha-hydroxytamoxifen in vitro: a metabolic disparity protecting human liver from the formation of tamoxifen-DNA adducts. Carcinogenesis 2000; 21:1851-8. [PMID: 11023543 DOI: 10.1093/carcin/21.10.1851] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Tamoxifen is a hepatic genotoxin in rats and mice but a hepatocarcinogen only in rats. It is not associated with DNA adducts and liver tumours in patients. The proposed major pathway for its bioactivation in rats involves alpha-hydroxylation, O-sulphonation and generation of a carbocation that reacts with DNA. Rat liver microsomes catalyse alpha-hydroxylation at approximately 2- and 4-fold the rate achieved by human and murine liver microsomes, respectively. O-glucuronylation will deactivate alpha-hydroxytamoxifen and compete with sulphonation. Rates of O-sulphonation of alpha-hydroxytamoxifen in hepatic cytosol have been determined by a HPLC assay of substrate-dependent 3'-phosphoadenosine 5'-phosphate production. The rank order of O-glucuronylation in hepatic microsomes was estimated by HPLC-mass spectrometry. The rate of sulphonation of trans-alpha-hydroxytamoxifen (25 microM) in cytosol from adult female Sprague-Dawley rats and CD1 mice was 5.3 +/- 0.8 and 3.9 +/- 0.5 pmol/min/mg protein (mean +/- SD, n = 3), respectively. In cytosol fractions from women aged 40-65 years, the rate was 1.1 +/- 0.4 pmol/min/mg protein (mean +/- SD, n = 6). The K(m) for trans-alpha-hydroxytamoxifen in rat, mouse and human cytosol was 84. 6 +/- 3.8, 81.4 +/- 4.6 and 104.3 +/- 5.6 microM (mean +/- SD, n = 3), respectively; the corresponding V:(max) values were 22.4 +/- 3.4, 17.1 +/- 3.1 and 6.3 +/- 1.9 pmol/min/mg protein. These K:(m) were similar to a value obtained by others using purified rat liver hydroxysteroid sulphotransferase a. Turnover of the cis epimer was too slow for accurate determination of rates. Sulphonation of trans-alpha-hydroxytamoxifen in human uterine cytosol was undetectable. The rank order of O-glucuronylation of trans-alpha-hydroxy- tamoxifen in liver microsomes was human > > mouse > rat. In combination, lower rates of alpha-hydroxylation and O-sulphonation and a higher rate of O-glucuronylation in human liver would protect patients from the formation of tamoxifen-DNA adducts.
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Affiliation(s)
- D J Boocock
- Department of Pharmacology and Therapeutics, University of Liverpool, Liverpool L69 3BX and MRC Toxicology Unit, Hodgkin Building, Lancaster Road, Leicester LE1 9HN, UK
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Boocock DJ, Maggs JL, White IN, Park BK. Alpha-hydroxytamoxifen, a genotoxic metabolite of tamoxifen in the rat: identification and quantification in vivo and in vitro. Carcinogenesis 1999; 20:153-60. [PMID: 9934863 DOI: 10.1093/carcin/20.1.153] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The metabolic formation of a-hydroxytamoxifen, a reactive metabolite of tamoxifen in rat liver, was characterized and quantified in vitro (hepatic microsomal incubations) and in vivo (bile-duct cannulated animals). This minor metabolite was identified by chromatographic and mass spectral comparisons with the authentic compound. The rates of formation of alpha-hydroxytamoxifen in incubations (30 min) of tamoxifen (25 microM) with liver microsomal preparations from women (pool of six), female CD1 mice or female Sprague-Dawley rats, as quantified by liquid chromatography-mass spectrometry (LC-MS), were 1.15+/-0.03, 0.30+/-0.05 and 2.70+/-0.35 pmol/min/mg protein, respectively. Selective inhibition of microsomal P450 indicated that alpha-hydroxylation was catalysed predominantly by CYP3A in humans. Bile-duct cannulated and anaesthetized female rats and mice given [14C]tamoxifen (43 micromol/kg, i.v.) excreted, respectively, 24 and 21% of the administered radioactivity in bile over 5 and 3.5 h. The major radiolabelled biliary metabolite in rats, characterized by LC-MS after enzymic hydrolysis of conjugates, was the glucuronide of 4-hydroxytamoxifen (10% of dose) and only 0.1% of the dose was recovered as alpha-hydroxytamoxifen. After administration of alpha-hydroxytamoxifen (43 micromol/kg, i.v.) to rats, only 1.19% of the administered compound was recovered from a glucuronide metabolite in bile, indicating a possible 0.84% alpha-hydroxylation of tamoxifen in vivo. There was, however, no indication of the presence in bile of either O-sulphonate or glutathione conjugates derived from alpha-hydroxytamoxifen. This study shows for the first time that alpha-hydroxytamoxifen can be glucuronylated in rat liver. Whereas sulphonation results in electrophilic genotoxic intermediates, glucuronidation may represent a means of detoxifying alpha-hydroxytamoxifen.
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Affiliation(s)
- D J Boocock
- Department of Pharmacology and Therapeutics, University of Liverpool, UK
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