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Ko BS, Liang SM, Chang TC, Wu JY, Lee PH, Hsu YJ, Kuo CC, Liou JY, Wu KK. Association of Tumor Hydroxyindole O-Methyltransferase and Serum 5-Methoxytryptophan with Long-Term Survival of Hepatocellular Carcinoma. Cancers (Basel) 2021; 13:cancers13215311. [PMID: 34771474 PMCID: PMC8582430 DOI: 10.3390/cancers13215311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Revised: 10/15/2021] [Accepted: 10/19/2021] [Indexed: 11/16/2022] Open
Abstract
Simple Summary 5-methoxytryptophan (5-MTP) is a tryptophan (Trp) metabolite synthesized by hydroxyindole O-methyltransferase (HIOMT). Expression of HIOMT is decreased in various tumors. However, whether HIOMT expression and serum 5-MTP concentration associate with prognosis of hepatocellular carcinoma (HCC) remains unclear. The aim of this study was to analyze HCC tissue HIOMT mRNA and serum 5-MTP and determine their association with survival following therapeutic liver resection. We found a significant association of serum 5-MTP or tissue HIOMT and serum kynurenine (Kyn) with overall and relapse free (RF) survival of HCC. The combination of serum 5-MTP and Kyn is a potential prognostic biomarker of HCC. Abstract 5-methoxytryptophan (5-MTP) is a recently discovered tryptophan (Trp) metabolite with anti-inflammatory and tumor-suppressing actions. Its synthesis is catalyzed by hydroxyindole O-methyltransferase (HIOMT). HIOMT levels were reported to be decreased in some patients with colorectal, pancreatic and breast cancer. It is unclear whether tissue HIOMT levels is altered in hepatocellular carcinoma (HCC). It is also unclear whether serum 5-MTP concentration is influenced by HCC. In this study, 150 HCC and adjacent normal liver tissues and serum samples were obtained from the HCC biobank established by a prospective multicenter study. Serum samples from 47 healthy subjects were included as a reference. HIOMT mRNA was measured by real time PCR. Serum 5-MTP and selected Trp metabolites were analyzed by quantitative LC-MS. HCC tissue HIOMT mRNA levels adjusted for adjacent normal tissue HIOMT mRNA levels was associated with overall and relapse-free (RF) survival. Combined serum 5-MTP or tissue HIOMT mRNA and serum kynurenine (Kyn) analysis predicted prolonged overall and RF survival following liver resection. A high serum 5-MTP or tissue HIOMT mRNA and low serum Kyn is associated with long-term survival. In conclusion, tumor tissue HIOMT mRNA and serum 5-MTP are potential biomarkers of HCC, especially when analyzed in combination with serum Kyn.
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Affiliation(s)
- Bor-Sheng Ko
- Department of Internal Medicine, National Taiwan University Hospital, Taipei 100, Taiwan;
- Department of Hematological Oncology, National Taiwan University Cancer Center, Taipei 100, Taiwan
| | - Shu-Man Liang
- Institute of Cellular and System Medicine, National Health Research Institutes, Zhunan Town 350, Taiwan; (S.-M.L.); (T.-C.C.); (J.-Y.W.); (P.-H.L.); (C.-C.K.)
| | - Tzu-Ching Chang
- Institute of Cellular and System Medicine, National Health Research Institutes, Zhunan Town 350, Taiwan; (S.-M.L.); (T.-C.C.); (J.-Y.W.); (P.-H.L.); (C.-C.K.)
| | - Jing-Yiing Wu
- Institute of Cellular and System Medicine, National Health Research Institutes, Zhunan Town 350, Taiwan; (S.-M.L.); (T.-C.C.); (J.-Y.W.); (P.-H.L.); (C.-C.K.)
| | - Po-Hsun Lee
- Institute of Cellular and System Medicine, National Health Research Institutes, Zhunan Town 350, Taiwan; (S.-M.L.); (T.-C.C.); (J.-Y.W.); (P.-H.L.); (C.-C.K.)
| | - Yu-Juei Hsu
- Division of Nephrology, National Defense Medical Center, Department of Medicine Tri-Service General Hospital, Taipei 114, Taiwan;
| | - Cheng-Chin Kuo
- Institute of Cellular and System Medicine, National Health Research Institutes, Zhunan Town 350, Taiwan; (S.-M.L.); (T.-C.C.); (J.-Y.W.); (P.-H.L.); (C.-C.K.)
| | - Jun-Yang Liou
- Institute of Cellular and System Medicine, National Health Research Institutes, Zhunan Town 350, Taiwan; (S.-M.L.); (T.-C.C.); (J.-Y.W.); (P.-H.L.); (C.-C.K.)
- Correspondence: (J.-Y.L.); (K.K.W.)
| | - Kenneth K Wu
- Institute of Cellular and System Medicine, National Health Research Institutes, Zhunan Town 350, Taiwan; (S.-M.L.); (T.-C.C.); (J.-Y.W.); (P.-H.L.); (C.-C.K.)
- Department of Internal Medicine, College of Medicine, National Taiwan University, Taipei 100, Taiwan
- Institute of Biotechnology, College of Life Science, National Tsing-Hua University, Hsinchu 300, Taiwan
- Correspondence: (J.-Y.L.); (K.K.W.)
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Revised Exon Structure of l-DOPA Decarboxylase ( DDC) Reveals Novel Splice Variants Associated with Colorectal Cancer Progression. Int J Mol Sci 2020; 21:ijms21228568. [PMID: 33202911 PMCID: PMC7697000 DOI: 10.3390/ijms21228568] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 11/09/2020] [Accepted: 11/12/2020] [Indexed: 12/26/2022] Open
Abstract
Colorectal cancer (CRC) is a highly heterogenous malignancy with an increased mortality rate. Aberrant splicing is a typical characteristic of CRC, and several studies support the prognostic value of particular transcripts in this malignancy. l-DOPA decarboxylase (DDC) and its derivative neurotransmitters play a multifaceted role in physiological and pathological states. Our recent data support the existence of 6 DDC novel exons. In this study, we investigated the existence of additional DDC novel exons and transcripts, and their potential value as biomarkers in CRC. Next-generation sequencing (NGS) in 55 human cell lines coupled with Sanger sequencing uncovered 3 additional DDC novel exons and 20 splice variants, 7 of which likely encode new protein isoforms. Eight of these transcripts were detected in CRC. An in-house qPCR assay was developed and performed in TNM II and III CRC samples for the quantification of transcripts bearing novel exons. Extensive biostatistical analysis uncovered the prognostic value of specific DDC novel exons for patients’ disease-free and overall survival. The revised DDC exon structure, the putative protein isoforms with distinct functions, and the prognostic value of novel exons highlight the pivotal role of DDC in CRC progression, indicating its potential utility as a molecular biomarker in CRC.
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3
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Chalatsa I, Arvanitis N, Arvanitis D, Tsakou AC, Kalantzis ED, Vassiliou AG, Sideris DC, Frakolaki E, Vassilaki N, Vassilacopoulou D. Human L-Dopa decarboxylase interaction with annexin V and expression during apoptosis. Biochimie 2020; 177:78-86. [PMID: 32835737 DOI: 10.1016/j.biochi.2020.08.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2020] [Revised: 07/30/2020] [Accepted: 08/17/2020] [Indexed: 01/13/2023]
Abstract
l-Dopa Decarboxylase (DDC) is a pyridoxal requiring enzyme that catalyzes the decarboxylation of L-3,4-dihydroxyphenylalanine (l-Dopa) to Dopamine (DA). The function of DDC in physiological and pathological biochemical pathways remains poorly understood, while the function and regulation of human DDC isoforms is almost completely elusive. We have shown that Annexin V, a fundamental apoptosis marker, is an inhibitor of l-Dopa decarboxylase activity. Here we show the interaction of both the full-length DDC and the truncated isoform alternative DDC (Alt-DDC) with Annexin V in human tissue and cell lines. Interestingly, DDC isoform expression is enhanced or remains unaffected following staurosporine (STS) treatment, despite increased levels of cytotoxicity and apoptosis. The findings presented here provide novel insights concerning the involvement of DDC in programmed cell death.
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Affiliation(s)
- Ioanna Chalatsa
- Department of Biochemistry and Molecular Biology, National and Kapodistrian University of Athens, Panepistimiopolis, 15701, Athens, Greece; Neurodegenerative Diseases Division, Center for Basic Research, Foundation for Biomedical Research of the Academy of Athens, 4 Soranou Ephessiou Street, 115 27, Athens, Greece
| | - Nikolaos Arvanitis
- Department of Biochemistry and Molecular Biology, National and Kapodistrian University of Athens, Panepistimiopolis, 15701, Athens, Greece
| | - Dimitrios Arvanitis
- Department of Biochemistry and Molecular Biology, National and Kapodistrian University of Athens, Panepistimiopolis, 15701, Athens, Greece
| | - Anastasia C Tsakou
- Department of Biochemistry and Molecular Biology, National and Kapodistrian University of Athens, Panepistimiopolis, 15701, Athens, Greece
| | - Evangelos D Kalantzis
- Department of Biochemistry and Molecular Biology, National and Kapodistrian University of Athens, Panepistimiopolis, 15701, Athens, Greece
| | - Alice G Vassiliou
- 1st Department of Critical Care Medicine & Pulmonary Services, GP Livanos and M Simou Laboratories, Evangelismos Hospital, Athens Medical School, National & Kapodistrian University of Athens, Athens, Greece
| | - Diamantis C Sideris
- Department of Biochemistry and Molecular Biology, National and Kapodistrian University of Athens, Panepistimiopolis, 15701, Athens, Greece
| | - Efseveia Frakolaki
- Laboratory of Molecular Virology, Hellenic Pasteur Institute (HPI), Vas. Sofias 127 av, 11521, Athens, Greece
| | - Niki Vassilaki
- Laboratory of Molecular Virology, Hellenic Pasteur Institute (HPI), Vas. Sofias 127 av, 11521, Athens, Greece
| | - Dido Vassilacopoulou
- Department of Biochemistry and Molecular Biology, National and Kapodistrian University of Athens, Panepistimiopolis, 15701, Athens, Greece.
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Kim JH, Lee SY, Choi JE, Do SK, Lee JH, Hong MJ, Kang HG, Lee WK, Shin KM, Jeong JY, Choi SH, Lee YH, Seo H, Yoo SS, Lee J, Cha SI, Kim CH, Park JY. Polymorphism in ASCL1 target gene DDC is associated with clinical outcomes of small cell lung cancer patients. Thorac Cancer 2019; 11:19-28. [PMID: 31691490 PMCID: PMC6938757 DOI: 10.1111/1759-7714.13212] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 09/17/2019] [Accepted: 09/18/2019] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Achaete-scute homolog 1 (ASCL1) is a basic helix-loop-helix transcription factor and is essential in the differentiation of neuroendocrine cells and neural tissues. ASCL1 is frequently overexpressed in small cell lung cancer (SCLC) and plays a crucial role in the pathogenesis of SCLC. METHODS This study was conducted to identify the association between single nucleotide polymorphisms (SNPs) in ASCL1 target genes and clinical outcomes of patients with SCLC after chemotherapy. A total of 261 patients diagnosed with SCLC were enrolled in this study. The association between 103 SNPs in 58 ASCL1 target genes and the response to chemotherapy and survival of patients with SCLC were analyzed. RESULTS Among the 103 SNPs, 10 SNPs were significantly associated with the response to chemotherapy, and 19 SNPs were associated with OS in multivariate analyses. Among these, Dopa Decarboxylase (DDC) rs12666409A>T was significantly associated with both a worse response to chemotherapy and worse OS (adjusted odds ratio [aOR] = 0.40, 95% CI = 0.18-0.90, P = 0.03; adjusted hazard ratio [aHR] = 1.52, 95% CI = 1.10-2.10, P = 0.01, respectively, under a dominant model). In a stage-stratified analysis, the association was significant only in the extensive disease subgroup (aOR = 0.19, 95% CI = 0.06-0.60, P = 0.01; aHR = 1.73, 95% CI = 1.16-2.56, P = 0.01, respectively, under a dominant model), but not in the limited disease subgroup. CONCLUSION The results of our study suggest that DDC rs12666409A>T may be useful markers for predicting the clinical outcomes of patients with SCLC undergoing chemotherapy.
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Affiliation(s)
- Ji Hyun Kim
- Department of Biochemistry and Cell Biology, School of Medicine, Kyungpook National University, Daegu, Republic of Korea.,BK21 Plus KNU Biomedical Convergence Program, Department of Biomedical Science, Kyungpook National University, Daegu, Republic of Korea
| | - Shin Yup Lee
- Department of Internal Medicine, School of Medicine, Kyungpook National University, Daegu, Republic of Korea.,Lung Cancer Center, Kyungpook National University Chilgok Hospital, Daegu, Republic of Korea
| | - Jin Eun Choi
- Department of Biochemistry and Cell Biology, School of Medicine, Kyungpook National University, Daegu, Republic of Korea.,Cell and Matrix Research Institute, School of Medicine, Kyungpook National University, Daegu, Republic of Korea
| | - Sook Kyung Do
- Department of Biochemistry and Cell Biology, School of Medicine, Kyungpook National University, Daegu, Republic of Korea.,BK21 Plus KNU Biomedical Convergence Program, Department of Biomedical Science, Kyungpook National University, Daegu, Republic of Korea
| | - Jang Hyuck Lee
- Department of Biochemistry and Cell Biology, School of Medicine, Kyungpook National University, Daegu, Republic of Korea.,BK21 Plus KNU Biomedical Convergence Program, Department of Biomedical Science, Kyungpook National University, Daegu, Republic of Korea
| | - Mi Jeong Hong
- Department of Biochemistry and Cell Biology, School of Medicine, Kyungpook National University, Daegu, Republic of Korea.,Cell and Matrix Research Institute, School of Medicine, Kyungpook National University, Daegu, Republic of Korea
| | - Hyo-Gyoung Kang
- Department of Biochemistry and Cell Biology, School of Medicine, Kyungpook National University, Daegu, Republic of Korea.,Cell and Matrix Research Institute, School of Medicine, Kyungpook National University, Daegu, Republic of Korea
| | - Won Kee Lee
- Medical Research Collaboration Center in Kyungpook National University Hospital and School of Medicine, Kyungpook National University, Daegu, Republic of Korea
| | - Kyung Min Shin
- Department of Radiology, Kyungpook National University, Daegu, Republic of Korea
| | - Ji Yun Jeong
- Department of Pathology, School of Medicine, Kyungpook National University, Daegu, Republic of Korea
| | - Sun Ha Choi
- Department of Internal Medicine, School of Medicine, Kyungpook National University, Daegu, Republic of Korea.,Lung Cancer Center, Kyungpook National University Chilgok Hospital, Daegu, Republic of Korea
| | - Yong Hoon Lee
- Department of Internal Medicine, School of Medicine, Kyungpook National University, Daegu, Republic of Korea
| | - Hyewon Seo
- Department of Internal Medicine, School of Medicine, Kyungpook National University, Daegu, Republic of Korea
| | - Seung Soo Yoo
- Department of Internal Medicine, School of Medicine, Kyungpook National University, Daegu, Republic of Korea.,Lung Cancer Center, Kyungpook National University Chilgok Hospital, Daegu, Republic of Korea
| | - Jaehee Lee
- Department of Internal Medicine, School of Medicine, Kyungpook National University, Daegu, Republic of Korea
| | - Seung Ick Cha
- Department of Internal Medicine, School of Medicine, Kyungpook National University, Daegu, Republic of Korea
| | - Chang Ho Kim
- Department of Internal Medicine, School of Medicine, Kyungpook National University, Daegu, Republic of Korea
| | - Jae Yong Park
- Department of Biochemistry and Cell Biology, School of Medicine, Kyungpook National University, Daegu, Republic of Korea.,BK21 Plus KNU Biomedical Convergence Program, Department of Biomedical Science, Kyungpook National University, Daegu, Republic of Korea.,Department of Internal Medicine, School of Medicine, Kyungpook National University, Daegu, Republic of Korea.,Lung Cancer Center, Kyungpook National University Chilgok Hospital, Daegu, Republic of Korea.,Cell and Matrix Research Institute, School of Medicine, Kyungpook National University, Daegu, Republic of Korea
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5
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Lan J, Liu Z, Liao C, Merkler DJ, Han Q, Li J. A Study for Therapeutic Treatment against Parkinson's Disease via Chou's 5-steps Rule. Curr Top Med Chem 2019; 19:2318-2333. [PMID: 31629395 DOI: 10.2174/1568026619666191019111528] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Revised: 08/05/2019] [Accepted: 08/22/2019] [Indexed: 11/22/2022]
Abstract
The enzyme L-DOPA decarboxylase (DDC), also called aromatic-L-amino-acid decarboxylase, catalyzes the biosynthesis of dopamine, serotonin, and trace amines. Its deficiency or perturbations in expression result in severe motor dysfunction or a range of neurodegenerative and psychiatric disorders. A DDC substrate, L-DOPA, combined with an inhibitor of the enzyme is still the most effective treatment for symptoms of Parkinson's disease. In this review, we provide an update regarding the structures, functions, and inhibitors of DDC, particularly with regards to the treatment of Parkinson's disease. This information will provide insight into the pharmacological treatment of Parkinson's disease.
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Affiliation(s)
- Jianqiang Lan
- Key Laboratory of Tropical Biological Resources of Ministry of Education, School of Life and Pharmaceutical Sciences, Hainan University, Haikou, Hainan 570228, China
| | - Zhongqiang Liu
- Key Laboratory of Tropical Biological Resources of Ministry of Education, School of Life and Pharmaceutical Sciences, Hainan University, Haikou, Hainan 570228, China
| | - Chenghong Liao
- Key Laboratory of Tropical Biological Resources of Ministry of Education, School of Life and Pharmaceutical Sciences, Hainan University, Haikou, Hainan 570228, China
| | - David J Merkler
- Department of Chemistry, University of South Florida, Tampa, FL, 33620, United States
| | - Qian Han
- Key Laboratory of Tropical Biological Resources of Ministry of Education, School of Life and Pharmaceutical Sciences, Hainan University, Haikou, Hainan 570228, China
| | - Jianyong Li
- Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061, United States
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Vassiliou AG, Siaterli MZ, Frakolaki E, Gkogkosi P, Paspaltsis I, Sklaviadis T, Vassilacopoulou D, Vassilaki N. L-Dopa decarboxylase interaction with the major signaling regulator ΡΙ3Κ in tissues and cells of neural and peripheral origin. Biochimie 2019; 160:76-87. [PMID: 30796964 DOI: 10.1016/j.biochi.2019.02.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Accepted: 02/17/2019] [Indexed: 12/17/2022]
Abstract
L-Dopa decarboxylase (DDC) catalyzes the decarboxylation of L-Dopa to dopamine and 5-hydroxytryptophan (5-HTP) to serotonin. Although DDC has been purified from a variety of peripheral organs, including the liver, kidney and pancreas, the physiological significance of the peripherally expressed enzyme is not yet fully understood. DDC has been considered as a potential novel biomarker for various types of cancer, however, the role of DDC in the development of hepatocellular carcinoma (HCC) remains to be evaluated. Phosphatidylinositol 3-kinase (PI3K), on the other hand, has been shown to play a key role in the tumorigenesis, proliferation, metastasis, apoptosis, and angiogenesis of HCC by regulating gene expression. We initially identified the interaction of DDC with PI3K by means of the phage display methodology. This association was further confirmed in human hepatocellular carcinoma cell lines, human embryonic kidney cells, human neuroblastoma cells, as well as mouse brain, by the use of specific antibodies raised against DDC and PI3K. Functional aspects of the above interaction were studied upon treatment with the DDC inhibitor carbidopa and the PI3K inhibitor LY294002. Interestingly, our data demonstrate the expression of the neuronal type DDC mRNA in HCC cells. The present investigation provides new evidence on the possible link of DDC with the PI3K pathway, underlining the biological significance of this complex enzyme.
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Affiliation(s)
- Alice G Vassiliou
- 1st Department of Critical Care Medicine & Pulmonary Services, GP Livanos and M Simou Laboratories, Evangelismos Hospital, Athens Medical School, National & Kapodistrian University of Athens, Ipsilantou 45-47, 10676, Athens, Greece; Section of Biochemistry and Molecular Biology, Faculty of Biology, National and Kapodistrian University of Athens, Panepistimiopolis, Zografou, 15701, Athens, Greece
| | - Maria-Zacharenia Siaterli
- Section of Biochemistry and Molecular Biology, Faculty of Biology, National and Kapodistrian University of Athens, Panepistimiopolis, Zografou, 15701, Athens, Greece
| | - Efseveia Frakolaki
- Molecular Virology Laboratory, Hellenic Pasteur Institute, 127 Vas. Sofias ave., 11521, Athens, Greece
| | - Panayiota Gkogkosi
- Section of Biochemistry and Molecular Biology, Faculty of Biology, National and Kapodistrian University of Athens, Panepistimiopolis, Zografou, 15701, Athens, Greece
| | - Ioannis Paspaltsis
- Laboratory of Pharmacology, School of Health Sciences, Department of Pharmacy, Aristotle University of Thessaloniki, University Campus, 54124, Thessaloniki, Greece
| | - Theodoros Sklaviadis
- Laboratory of Pharmacology, School of Health Sciences, Department of Pharmacy, Aristotle University of Thessaloniki, University Campus, 54124, Thessaloniki, Greece
| | - Dido Vassilacopoulou
- Section of Biochemistry and Molecular Biology, Faculty of Biology, National and Kapodistrian University of Athens, Panepistimiopolis, Zografou, 15701, Athens, Greece.
| | - Niki Vassilaki
- Molecular Virology Laboratory, Hellenic Pasteur Institute, 127 Vas. Sofias ave., 11521, Athens, Greece.
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Wu WH, Chien CY, Wu YH, Wu HH, Lai JM, Chang PMH, Huang CYF, Wang FS. Inferring oncoenzymes in a genome-scale metabolic network for hepatocytes using bilevel optimization framework. J Taiwan Inst Chem Eng 2018. [DOI: 10.1016/j.jtice.2018.06.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Predictive and prognostic value of 18F-DOPA PET/CT in patients affected by recurrent medullary carcinoma of the thyroid. Ann Nucl Med 2017; 32:7-15. [PMID: 28986764 DOI: 10.1007/s12149-017-1213-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Accepted: 09/25/2017] [Indexed: 11/27/2022]
Abstract
INTRODUCTION Medullary thyroid carcinoma (MTC) is a malignancy accounting for about 5-8% of thyroid cancers. Serum calcitonin and carcinoembryonic antigen (CEA) levels are widely used to monitor disease progression. However, prognostic factors able to predict outcomes are highly desirable. We, therefore, aimed to assess the prognostic role of 18F-DOPA PET/CT in patients with recurrent MTC. MATERIALS AND METHODS 60 patients (mean age 64 ± 13 years, range 44-82) with recurrent MTC were eligible from a multicenter database. All patients underwent a restaging 18F-DOPA PET/CT, performed at least 6 months after surgery. CEA/calcitonin levels, local recurrences, nodal involvement and metastases at PET/CT were recorded. SUVmax, SUVmean (also normalized to mediastinal uptake) and metabolic tumor volume were automatically calculated for each lesion, by placing a volume of interest around the lesion with 40% of peak activity as threshold for the automatic contouring. The patients were clinically and radiologically followed up for 21 ± 11 months. Rate of progression-free survival (PFS), disease-specific survival (DSS) and incremental prognostic value of 18F-DOPA PET/CT over conventional imaging modalities were assessed by Kaplan-Meier curves and Log-Rank test. Cox regression univariate and multivariate analyses were performed for assessing predictors of prognosis. RESULTS 18F-DOPA PET/CT showed abnormal findings in 27 patients (45%) and resulted unremarkable in 33 (55%). PFS was significantly longer in patients with an unremarkable PET/CT scan (p = 0.018). Similarly, an unremarkable PET/CT study was associated with a significantly longer DSS (p = 0.04). 18F-DOPA PET/CT added prognostic value over other imaging modalities both for PFS and for DSS (p < 0.001 and p = 0.012, respectively). Neither semiquantitative PET parameters nor clinical or laboratory data were predictive of a worse PFS and DSS in patients with recurrent MTC. CONCLUSION 18F-DOPA PET/CT scan has an important prognostic value in predicting disease progression and mortality rate.
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Wu HQ, Cheng ML, Lai JM, Wu HH, Chen MC, Liu WH, Wu WH, Chang PMH, Huang CYF, Tsou AP, Shiao MS, Wang FS. Flux balance analysis predicts Warburg-like effects of mouse hepatocyte deficient in miR-122a. PLoS Comput Biol 2017; 13:e1005618. [PMID: 28686599 PMCID: PMC5536358 DOI: 10.1371/journal.pcbi.1005618] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Revised: 07/31/2017] [Accepted: 06/12/2017] [Indexed: 12/31/2022] Open
Abstract
The liver is a vital organ involving in various major metabolic functions in human body. MicroRNA-122 (miR-122) plays an important role in the regulation of liver metabolism, but its intrinsic physiological functions require further clarification. This study integrated the genome-scale metabolic model of hepatocytes and mouse experimental data with germline deletion of Mir122a (Mir122a–/–) to infer Warburg-like effects. Elevated expression of MiR-122a target genes in Mir122a–/–mice, especially those encoding for metabolic enzymes, was applied to analyze the flux distributions of the genome-scale metabolic model in normal and deficient states. By definition of the similarity ratio, we compared the flux fold change of the genome-scale metabolic model computational results and metabolomic profiling data measured through a liquid-chromatography with mass spectrometer, respectively, for hepatocytes of 2-month-old mice in normal and deficient states. The Ddc gene demonstrated the highest similarity ratio of 95% to the biological hypothesis of the Warburg effect, and similarity of 75% to the experimental observation. We also used 2, 6, and 11 months of mir-122 knockout mice liver cell to examined the expression pattern of DDC in the knockout mice livers to show upregulated profiles of DDC from the data. Furthermore, through a bioinformatics (LINCS program) prediction, BTK inhibitors and withaferin A could downregulate DDC expression, suggesting that such drugs could potentially alter the early events of metabolomics of liver cancer cells. For almost a century, researchers have known that cancer cells have an abnormal metabolism and utilize glucose differently than normal cells do. Aerobic glycolysis or the Warburg effect in cancer cells involves elevated glucose uptake with lactic acid production in the presence of oxygen. MicroRNAs have recently been discovered to be key metabolic regulators that mediate the fine tuning of genes that are involved directly or indirectly in cancer metabolism. MicroRNA-122 (miR-122) plays an important role in the regulation of liver metabolism, but its intrinsic physiological functions require further clarification. This study integrated the genome-scale metabolic modeling (GSMM) of hepatocytes and mouse experimental data with germline deletion of Mir122a (Mir122a–/–) to infer Warburg-like effects. In silico and in vivo observations indicated that DDC overexpression induced Warburg effect in hepatocyte. Furthermore, through a bioinformatics prediction, BTK inhibitors and withaferin A could downregulate DDC expression, suggesting that such drugs could potentially alter the early events of metabolomics of liver cancer cells.
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Affiliation(s)
- Hua-Qing Wu
- Department of Chemical Engineering, National Chung Cheng University, Chiayi, Taiwan
| | - Mei-Ling Cheng
- Department of Biomedical Sciences, Chang Gung University, Tao-Yuan, Taiwan
- Metabolomics Core Laboratory, Healthy Aging Research Center, Chang Gung University, Tao-Yuan, Taiwan
- Clinical Phenome Center, Chang Gung Memorial Hospital, Linkou, Tao-Yuan, Taiwan
| | - Jin-Mei Lai
- Department of Life Science, Fu-Jen Catholic University, New Taipei City, Taiwan
| | - Hsuan-Hui Wu
- Institute of Biopharmaceutical Sciences, National Yang-Ming University, Taipei, Taiwan
| | - Meng-Chun Chen
- Department of Chemical Engineering, National Chung Cheng University, Chiayi, Taiwan
| | - Wen-Huan Liu
- Department of Chemical Engineering, National Chung Cheng University, Chiayi, Taiwan
| | - Wu-Hsiung Wu
- Department of Chemical Engineering, National Chung Cheng University, Chiayi, Taiwan
| | - Peter Mu-Hsin Chang
- Department of Oncology, Taipei Veterans General Hospital, Taipei, Taiwan
- Faculty of Medicine, National Yang Ming University, Taipei, Taiwan
| | - Chi-Ying F. Huang
- Institute of Biopharmaceutical Sciences, National Yang-Ming University, Taipei, Taiwan
- Department of Biotechnology and Laboratory Science in Medicine, National Yang-Ming University, Taipei, Taiwan
- Department of Biochemistry, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Ann-Ping Tsou
- Department of Biotechnology and Laboratory Science in Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Ming-Shi Shiao
- Department of Biomedical Sciences, Chang Gung University, Tao-Yuan, Taiwan
- * E-mail: (MSS); (FSW)
| | - Feng-Sheng Wang
- Department of Chemical Engineering, National Chung Cheng University, Chiayi, Taiwan
- * E-mail: (MSS); (FSW)
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Abstract
UNLABELLED Identification of common molecular mechanisms is needed to facilitate the development of new treatment options for patients with ileal carcinoids. PURPOSE OF REVIEW Recent profiling studies on ileal carcinoids were examined to obtain a comprehensive view of risk factors, genetic aberrations, and transcriptional alterations. Special attention was paid to mechanisms that could provide novel targets for therapy. RESULTS Genome-wide association studies have shown that single nucleotide polymorphisms (SNPs) at IL12A and DAD1 are associated with an increased risk of ileal carcinoids. Genomic profiling revealed distinct patterns of copy-number alterations in ileal carcinoids. Two groups of carcinoids could be identified by hierarchical clustering. A major group of tumors was characterized by loss on chromosome 18 followed by additional losses on chromosomes 3p, 11q, and 13. Three minimal common regions of deletions were identified at 18q21.1-q21.31, 18q22.1-q22.2, and 18q22.3-q23. A minor group of tumors was characterized by clustered gains on chromosomes 4, 5, 7, 14, and 20. Expression profiling identified three groups of ileal carcinoids by principal component analysis. Tumor progression was associated with changes in gene expression including downregulation of MIR133A. Candidate genes for targeted therapy included ERBB2/HER2, DAD1, PRKCA, RYBP, CASP1, CASP4, CASP5, VMAT1, RET, APLP1, OR51E1, GPR112, SPOCK1, RUNX1, and MIR133A. CONCLUSION Profiling of ileal carcinoids has revealed recurrent genetic alterations and distinct patterns of gene expression. Frequent alterations in cellular pathways and genes were identified, suggesting novel targets for therapy. Translational studies are needed to validate suggested molecular targets.
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Affiliation(s)
- Ola Nilsson
- Sahlgrenska Cancer Center, Institute of Biomedicine, Sahlgrenska Academy at the University of Gothenburg, Göteborg, Sweden.
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11
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Geomela PA, Kontos CK, Yiotakis I, Fragoulis EG, Scorilas A. L-DOPA decarboxylase mRNA expression is associated with tumor stage and size in head and neck squamous cell carcinoma: a retrospective cohort study. BMC Cancer 2012; 12:484. [PMID: 23083099 PMCID: PMC3495033 DOI: 10.1186/1471-2407-12-484] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2012] [Accepted: 10/17/2012] [Indexed: 12/22/2022] Open
Abstract
Background Head and neck squamous cell carcinoma (HNSCC) represents one of the most commonly diagnosed malignancies worldwide. The DDC gene encodes L-DOPA decarboxylase, an enzyme catalyzing the decarboxylation of L-DOPA to dopamine. We have recently shown that DDC mRNA is a significant predictor of patients’ prognosis in colorectal adenocarcinoma and prostate cancer. The aim of the current study was to analyze the DDC mRNA expression in HNSCC patients. Methods 53 malignant tumors were resected from the larynx, pharynx, tongue, buccal mucosa, parotid glands, and nasal cavity, as well as from 34 adjacent non-cancerous tissues of HNSCC patients, and were homogenized. Total RNA was isolated and converted into first-strand cDNA. An ultrasensitive real-time PCR method based on the SYBR Green chemistry was used for DDC mRNA quantification in head and neck tissue specimens. Relative quantification was performed using the comparative Ct (2-ddCt) method. Results DDC mRNA levels were lower in squamous cell carcinomas (SCCs) of the larynx and tongue than in adjacent non-cancerous tissue specimens. Furthermore, low DDC mRNA expression was noticed in laryngeal and tongue tumors of advanced TNM stage or bigger size, compared to early-stage or smaller tumors, respectively. No statistically significant differences were observed between SCCs resected from pharynx, buccal mucosa, or nasal cavity, and their normal counterparts. Conclusion This is the first study examining the DDC mRNA expression in HNSCC. According to our results, DDC mRNA expression may constitute a potential prognostic biomarker in tongue and/or larynx SCCs, which principally represent the overwhelming majority of HNSCC cases.
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Affiliation(s)
- Panagiota-Aikaterini Geomela
- Department of Biochemistry and Molecular Biology, University of Athens, Panepistimiopolis, Athens 15701, Greece.
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12
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PET/CT using ¹⁸F-FDOPA provides improved staging of carcinoid tumor patients in a Canadian setting. Nucl Med Commun 2012; 33:322-30. [PMID: 22183015 DOI: 10.1097/mnm.0b013e32834f2603] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
AIM In Canada, staging of carcinoid tumors is largely based on computed tomography (CT) imaging sometimes complemented with somatostatin receptor scintigraphy (SRS). This study assessed the diagnostic accuracy of 6-[¹⁸F]fluoro-3,4-dihydroxyphenylalanine (¹⁸F-FDOPA) PET/CT in neuroendocrine tumors. METHODS We prospectively included 27 patients with either suspected carcinoid (n=6, with all prior tests negative) or with an established diagnosis of intestinal carcinoid tumor (n=21) from two Canadian treatment centers. Findings of ¹⁸F-FDOPA PET/CT were compared with SRS, CT, and combined SRS/CT using a composite reference standard comprising all available imaging, biochemistry, surgery, and follow-up data. Sensitivity was calculated per patient, per body region, and per lesion. The contribution to patient management was estimated from the feedback of attending physicians. RESULTS In documented carcinoid patients, ¹⁸F-FDOPA PET/CT identified disease in 20 of 21 patients (patient-based sensitivity 95%). In 56 positive regions, ¹⁸F-FDOPA PET/CT detected 53, CT detected 34, SRS detected 34, and CT+SRS detected 39 regions, leading to region-based sensitivities of 95, 61, 62, and 71%, respectively. Lesion-based sensitivities were 96, 69, 50, and 72%, respectively. In the six patients with suspected disease only, one CT scan was positive, but ¹⁸F-FDOPA PET/CT was negative for all. ¹⁸F-FDOPA PET contributed to patient management in 12/21 patients (57%). CONCLUSION ¹⁸F-FDOPA PET/CT proved to be an excellent modality for staging of carcinoid tumor patients, with superior performance compared with currently applied methods in Canada. In patients with suspected disease with negative prior imaging investigations, ¹⁸F-FDOPA was not helpful.
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13
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Hao K, Gong P, Sun SQ, Hao HP, Wang GJ, Dai Y, Chen YC, Liang Y, Xie L, Li FY, Li HY. Mechanism-based pharmacokinetic-pharmacodynamic modeling of the estrogen-like effect of ginsenoside Rb1 on neural 5-HT in ovariectomized mice. Eur J Pharm Sci 2011; 44:117-26. [PMID: 21740969 DOI: 10.1016/j.ejps.2011.06.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2010] [Revised: 04/15/2011] [Accepted: 06/22/2011] [Indexed: 11/18/2022]
Abstract
We sought to develop a mechanism-based pharmacokinetic-pharmacodynamic (PK-PD) model to characterize the effects of ginsenoside Rb1 (Rb1) and estradiol (E(2)) on neural 5-hydroxytryptamine (5-HT) concentration in ovariectomized mice. PK data of Rb1 and E(2) were obtained in plasma and brain. Brain levels of 5-HT, tryptophan (TRP), 5-hydroxytryptophan (5-HTP), and 5-hydroxyindoleacetic acid (5-HIAA) were determined after a single intravenous injection of Rb1 (20mg/kg) and E(2) (0.2mg/kg) in ovariectomized mice. The activities of tryptophan hydroxylase (TPH), aromatic amino acid decarboxylase (AAAD), and monoamine oxidase (MAO) were also evaluated. Rb1 and E(2) elevated neural 5-HT levels via TPH activation and MAO inhibition, respectively. Effects were well described by the mechanism-based PK-PD model. The net effect of increased 5-HT induced by MAO inhibition is greater than TPH activation. The increased brain levels of 5-HT induced by Rb1 and E(2) were well described by the present PK-PD model, suggesting the use and further development of this mechanism-based model for the effects of ginsenoside on brain 5-HT levels.
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Affiliation(s)
- Kun Hao
- Key Lab of Drug Metabolism & Pharmacokinetics, China Pharmaceutical University, Nanjing, PR China
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14
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Fiebrich HB, de Jong JR, Kema IP, Koopmans KP, Sluiter W, Dierckx RAJO, Walenkamp AM, Links TP, Brouwers AH, de Vries EGE. Total 18F-dopa PET tumour uptake reflects metabolic endocrine tumour activity in patients with a carcinoid tumour. Eur J Nucl Med Mol Imaging 2011; 38:1854-61. [PMID: 21698413 PMCID: PMC3168742 DOI: 10.1007/s00259-011-1862-5] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2011] [Accepted: 06/07/2011] [Indexed: 01/06/2023]
Abstract
Purpose Positron emission tomography (PET) using 6-[18F]fluoro-L-dihydroxyphenylalanine (18F-dopa) has an excellent sensitivity to detect carcinoid tumour lesions. 18F-dopa tumour uptake and the levels of biochemical tumour markers are mediated by tumour endocrine metabolic activity. We evaluated whether total 18F-dopa tumour uptake on PET, defined as whole-body metabolic tumour burden (WBMTB), reflects tumour load per patient, as measured with tumour markers. Methods Seventy-seven consecutive carcinoid patients who underwent an 18F-dopa PET scan in two previously published studies were analysed. For all tumour lesions mean standardised uptake values (SUVs) at 40% of the maximal SUV and tumour volume on 18F-dopa PET were determined and multiplied to calculate a metabolic burden per lesion. WBMTB was the sum of the metabolic burden of all individual lesions per patient. The 24-h urinary serotonin, urine and plasma 5-hydroxindoleacetic acid (5-HIAA), catecholamines (nor)epinephrine, dopamine and their metabolites, measured in urine and plasma, and serum chromogranin A served as tumour markers. Results All but 1 were evaluable for WBMTB; 74 patients had metastatic disease. 18F-dopa PET detected 979 lesions. SUVmax on 18F-dopa PET varied up to 29-fold between individual lesions within the same patients. WBMTB correlated with urinary serotonin (r = 0.51) and urinary and plasma 5-HIAA (r = 0.78 and 0.66). WBMTB also correlated with urinary norepinephrine, epinephrine, dopamine and plasma dopamine, but not with serum chromogranin A. Conclusion Tumour load per patient measured with 18F-dopa PET correlates with tumour markers of the serotonin and catecholamine pathway in urine and plasma in carcinoid patients, reflecting metabolic tumour activity.
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Affiliation(s)
- Helle-Brit Fiebrich
- Department of Medical Oncology, University Medical Centre Groningen, P.O. Box 30.001, 9700 RB, Groningen, The Netherlands
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15
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Chalatsa I, Fragoulis EG, Vassilacopoulou D. Release of membrane-associated L-dopa decarboxylase from human cells. Neurochem Res 2011; 36:1426-34. [PMID: 21479916 DOI: 10.1007/s11064-011-0468-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/30/2011] [Indexed: 02/06/2023]
Abstract
L-Dopa Decarboxylase is a pyridoxal 5-phosphate (PLP)-dependent enzyme that catalyses the decarboxylation of L-Dopa to dopamine. In this study, we investigated the cellular topology of the active human enzyme. Fractionation of membranes from human cell lines, of neural and non-neural origin, by temperature-induced phase separation in Triton X-114 resulted in the detection of DDC molecules in all separation phases. Solubilization of membrane-associated DDC was observed in a pH and time-dependent manner and was affected by divalent cations and protease inhibitors, suggesting the involvement of a possible release mechanism. The study of the biological properties and function of the solubilization phenomenon described here, as well as, the study of the membrane-associated enzyme could provide us with new information about the participation of the human L-Dopa decarboxylase in physiological and aberrant processes.
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Affiliation(s)
- Ioanna Chalatsa
- Department of Biochemistry and Molecular Biology, University of Athens, Panepistimiopolis, Zografou, 15701, Athens, Greece
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16
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Hao K, Gong P, Sun SQ, Hao HP, Wang GJ, Dai Y, Liang Y, Xie L, Li FY. Beneficial estrogen-like effects of ginsenoside Rb1, an active component of Panax ginseng, on neural 5-HT disposition and behavioral tasks in ovariectomized mice. Eur J Pharmacol 2011; 659:15-25. [PMID: 21414307 DOI: 10.1016/j.ejphar.2011.03.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2010] [Revised: 02/08/2011] [Accepted: 03/01/2011] [Indexed: 11/29/2022]
Abstract
Decreased 5-hydroxytryptamine (5-HT) concentration in the brain has been linked to central nervous system dysfunctions, especially in menopausal women. Ginsenoside Rb1, a potential phytoestrogen, has been shown to improve central nervous system dysfunctions, comparable to the estrogen treatment. To investigate the estrogen-like effects of ginsenoside Rb1 on neural 5-HT disposition and behavioral tasks, we quantified the concentrations of 5-HT and other related endogenous substances in the frontal cortex and striatum of ovariectomized mice. The activities of tryptophan hydroxylase (TPH), aromatic amino acid decarboxylase (AAAD) and monoamine oxidase (MAO) were also measured to evaluate the synthesis and metabolism of neural 5-HT. Our work shows that both ginsenoside Rb1 and estradiol increased the neural 5-HT concentration. Ginsenoside Rb1 and estradiol administration resulted in elevated TPH and depressed MAO activities, indicating that modulating the synthesis and metabolism of neural 5-HT successfully elevated 5-HT concentration. Ginsenoside Rb1 and estradiol also improved object recognition and decreased immobility time in the forced swimming test. However, a pretreatment with clomiphene (an estrogen receptor antagonist) blocked the beneficial effects of ginsenoside Rb1 and estradiol, suggesting that the estrogen-like effects of ginsenoside Rb1 were estrogen receptor-dependent.
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Affiliation(s)
- Kun Hao
- Key Lab of Drug Metabolism & Pharmacokinetics, China Pharmaceutical University, Nanjing, PR China
| | - Ping Gong
- Key Lab of Drug Metabolism & Pharmacokinetics, China Pharmaceutical University, Nanjing, PR China
| | - Shi-Qing Sun
- Key Lab of Drug Metabolism & Pharmacokinetics, China Pharmaceutical University, Nanjing, PR China
| | - Hai-Ping Hao
- Key Lab of Drug Metabolism & Pharmacokinetics, China Pharmaceutical University, Nanjing, PR China
| | - Guang-Ji Wang
- Key Lab of Drug Metabolism & Pharmacokinetics, China Pharmaceutical University, Nanjing, PR China
| | - Yue Dai
- College of Traditional Chinese Materia Medica, China Pharmaceutical University, Nanjing, PR China
| | - Yan Liang
- Key Lab of Drug Metabolism & Pharmacokinetics, China Pharmaceutical University, Nanjing, PR China
| | - Lin Xie
- Key Lab of Drug Metabolism & Pharmacokinetics, China Pharmaceutical University, Nanjing, PR China
| | - Fei-Yan Li
- Key Lab of Drug Metabolism & Pharmacokinetics, China Pharmaceutical University, Nanjing, PR China
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17
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Camilleri M. LX-1031, a tryptophan 5-hydroxylase inhibitor, and its potential in chronic diarrhea associated with increased serotonin. Neurogastroenterol Motil 2011; 23:193-200. [PMID: 21159063 PMCID: PMC3076306 DOI: 10.1111/j.1365-2982.2010.01643.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
LX-1031 is an oral, small molecule tryptophan 5-hydroxylase (TPH) inhibitor that reduces serotonin (5-HT) synthesis peripherally. It has potential for illnesses characterized by excess 5-HT, such as diarrhea-predominant irritable bowel syndrome (IBS-D) and carcinoid diarrhea. In vitro, inhibition of TPH1 occurred in 10(-8) -10(-7) mol L(-1) range. In vivo in rodents, LX-1031 has no effect on brain 5-HT while dose-dependently reducing 5-HT, particularly in the small bowel. After oral LX1031 in humans, systemic exposure is very low, plasma concentrations are linear in dose range 250-750 mg q.i.d.; the median T(1/2) for elimination is ∼ 20 h, and repeat administration for 14 days doubles C(max) . In ascending-single-dose and multiple-dose (14 days) trials in healthy volunteers, LX-1031, 2-4 g day(-1) significantly reduced urinary 5-hydroxyindoleacetic acid (5-HIAA) starting by Day 5, and persisting over the 14 day exposure. There are no dose-limiting toxicities in healthy subjects or remarkable adverse effects in clinical trials to date. Over a 28-day treatment period, LX-1031 was associated with improved weekly global scores (2/4 weeks) and improved stool consistency with lower urinary 5-HIAA excretion. LX-1031 appears promising for chronic diarrhea associated with increased 5-HT expression including IBS-D. Optimal doses, efficacy and safety in IBS clinical trials need to be fully elucidated; low systemic exposure, selectivity for TPH1 over TPH2, and lack of effect on brain 5-HT in several species suggest that LX-1031 is unlikely to cause affective disorders.
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Affiliation(s)
- Michael Camilleri
- Clinical Enteric Neuroscience Translational and Epidemiological Research (CENTER), Mayo Clinic, Rochester, Minnesota, U.S.A
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18
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Chalatsa I, Nikolouzou E, Fragoulis EG, Vassilacopoulou D. L-Dopa decarboxylase expression profile in human cancer cells. Mol Biol Rep 2010; 38:1005-11. [PMID: 20535562 DOI: 10.1007/s11033-010-0196-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2010] [Accepted: 05/22/2010] [Indexed: 02/06/2023]
Abstract
L-Dopa decarboxylase (DDC) catalyses the decarboxylation of L-Dopa. It has been shown that the DDC gene undergoes alternative splicing within its 5'-untranslated region (UTR), in a tissue-specific manner, generating identical protein products. The employment of two alternative 5'UTRs is thought to be responsible for tissue-specific expression of the human DDC mRNA. In this study, we focused on the investigation of the nature of the mRNA expression in human cell lines of neural and non-neural origin. Our results show the expression of a neural-type DDC mRNA splice variant, lacking exon 3 in all cell lines studied. Co-expression of the full length non-neural DDC mRNA and the neural-type DDC splice variant lacking exon 3 was detected in all cell lines. The alternative DDC protein isoform, Alt-DDC, was detected in SH-SY5Y and HeLa cells. Our findings suggest that the human DDC gene undergoes complex processing, leading to the formation of multiple mRNA isoforms. The study of the significance of this phenomenon of multiple DDC mRNA isoforms could provide us with new information leading to the elucidation of the complex biological pathways that the human enzyme is involved in.
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Affiliation(s)
- Ioanna Chalatsa
- Department of Biochemistry and Molecular Biology, University of Athens, Panepistimiopolis, Zografou, 15701, Athens, Greece
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19
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Quantitative expression analysis and prognostic significance of L-DOPA decarboxylase in colorectal adenocarcinoma. Br J Cancer 2010; 102:1384-90. [PMID: 20424616 PMCID: PMC2865762 DOI: 10.1038/sj.bjc.6605654] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND L-DOPA decarboxylase (DDC) is an enzyme that catalyses, mainly, the decarboxylation of L-DOPA to dopamine and was found to be involved in many malignancies. The aim of this study was to investigate the mRNA expression levels of the DDC gene and to evaluate its clinical utility in tissues with colorectal adenocarcinoma. METHODS Total RNA was isolated from colorectal adenocarcinoma tissues of 95 patients. After having tested RNA quality, we prepared cDNA by reverse transcription. Highly sensitive quantitative real-time PCR method for DDC mRNA quantification was developed using the SYBR Green chemistry. GAPDH served as a housekeeping gene. Relative quantification analysis was performed using the comparative C(T) method (2(-DeltaDeltaC(T))). RESULTS DDC mRNA expression varied remarkably among colorectal tumours examined in this study. High DDC mRNA expression levels were found in well-differentiated and Dukes' stage A and B tumours. Kaplan-Meier survival curves showed that patients with DDC-positive tumours have significantly longer disease-free survival (P=0.009) and overall survival (P=0.027). In Cox regression analysis of the entire cohort of patients, negative DDC proved to be a significant predictor of reduced disease-free (P=0.021) and overall survival (P=0.047). CONCLUSIONS The results of the study suggest that DDC mRNA expression may be regarded as a novel potential tissue biomarker in colorectal adenocarcinoma.
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Paley EL, Denisova G, Sokolova O, Posternak N, Wang X, Brownell AL. Tryptamine induces tryptophanyl-tRNA synthetase-mediated neurodegeneration with neurofibrillary tangles in human cell and mouse models. Neuromolecular Med 2008; 9:55-82. [PMID: 17114825 DOI: 10.1385/nmm:9:1:55] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2004] [Revised: 05/08/2006] [Accepted: 05/09/2006] [Indexed: 01/24/2023]
Abstract
The neuropathological hallmarks of Alzheimer's disease (AD) and other taupathies include neurofibrillary tangles and plaques. Despite the fact that only 2-10% of AD cases are associated with genetic mutations, no nontransgenic or metabolic models have been generated to date. The findings of tryptophanyl-tRNA synthetase (TrpRS) in plaques of the AD brain were reported recently by the authors. Here it is shown that expression of cytoplasmic-TrpRS is inversely correlated with neurofibrillary degeneration, whereas a nonionic detergent-insoluble presumably aggregated TrpRS is simultaneously accumulated in human cells treated by tryptamine, a metabolic tryptophan analog that acts as a competitive inhibitor of TrpRS. TrpRSN- terminal peptide self-assembles in double-helical fibrils in vitro. Herein, tryptamine causes neuropathy characterized by motor and behavioral deficits, hippocampal neuronal loss, neurofibrillary tangles, amyloidosis, and glucose decrease in mice. Tryptamine induced the formation of helical fibrillary tangles in both hippocampal neurons and glia. Taken together with the authors' previous findings of tryptamine-induced nephrotoxicity and filamentous tangle formation in kidney cells, the authors' data indicates a general role of tryptamine in cell degeneration and loss. It is concluded that tryptamine as a component of a normal diet can induce neurodegeneration at the concentrations, which might be consumed along with food. Tryptophan-dependent tRNAtrp aminoacylation catalyzed by TrpRS can be inhibited by its substrate tryptophan at physiological concentrations was demonstrated. These findings indicate that the dietary supplementation with tryptophan as a tryptamine competitor may not counteract the deleterious influence of tryptamine. The pivotal role of TrpRS in protecting against neurodegeneration is suggested, providing an insight into the pathogenesis and a possible treatment of neurodegenerative diseases.
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Affiliation(s)
- Elena L Paley
- Department of Urology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA.
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21
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Vassiliou AG, Fragoulis EG, Vassilacopoulou D. Detection, purification and identification of an endogenous inhibitor of L-Dopa decarboxylase activity from human placenta. Neurochem Res 2008; 34:1089-100. [PMID: 19005753 DOI: 10.1007/s11064-008-9879-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/23/2008] [Indexed: 01/01/2023]
Abstract
An endogenous inhibitor of L-Dopa decarboxylase activity was identified and purified from human placenta. The endogenous inhibitor of L-Dopa decarboxylase (Ddc) was localized in the membrane fraction of placental tissue. Treatment of membranes with phosphatidylinositol-specific phospholipase C or proteinase K did not affect membrane-associated Ddc inhibitory activity, suggesting that a population of the inhibitor is embedded within membranes. Purification was achieved by extraction from a nondenaturing polyacrylamide gel. The purification scheme resulted in the isolation of a single 35 kDa band, bearing L-Dopa decarboxylase inhibitory activity. The purified inhibitor was identified as Annexin V. The elucidation of the biological importance of the presence of an L-Dopa decarboxylase activity inhibitor in normal human tissues could provide us with new information leading to the better understanding of the biological pathways that Ddc is involved in.
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Jager PL, Chirakal R, Marriott CJ, Brouwers AH, Koopmans KP, Gulenchyn KY. 6-L-18F-fluorodihydroxyphenylalanine PET in neuroendocrine tumors: basic aspects and emerging clinical applications. J Nucl Med 2008; 49:573-86. [PMID: 18344441 DOI: 10.2967/jnumed.107.045708] [Citation(s) in RCA: 146] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
In recent years, 6-l-18F-fluorodihydroxyphenylalanine (18F-DOPA) PET has emerged as a new diagnostic tool for the imaging of neuroendocrine tumors. This application is based on the unique property of neuroendocrine tumors to produce and secrete various substances, a process that requires the uptake of metabolic precursors, which leads to the uptake of 18F-DOPA. This nonsystematic review first describes basic aspects of 18F-DOPA imaging, including radiosynthesis, factors involved in tracer uptake, and various aspects of metabolism and imaging. Subsequently, this review provides an overview of current clinical applications in neuroendocrine tumors, including carcinoid tumors, pancreatic islet cell tumors, pheochromocytoma, paraganglioma, medullary thyroid cancer, hyperinsulinism, and various other clinical entities. The application of PET/CT in carcinoid tumors has unsurpassed sensitivity. In medullary thyroid cancer, pheochromocytoma, and hyperinsulinism, results are also excellent and contribute significantly to clinical management. In the remaining conditions, the initial experience with 18F-DOPA PET indicates that it seems to be less valuable, but further study is required.
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Affiliation(s)
- Pieter L Jager
- Department of Nuclear Medicine, Hamilton Health Sciences/McMaster University, Hamilton, Ontario, Canada.
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Koopmans KP, de Vries EGE, Kema IP, Elsinga PH, Neels OC, Sluiter WJ, van der Horst-Schrivers ANA, Jager PL. Staging of carcinoid tumours with 18F-DOPA PET: a prospective, diagnostic accuracy study. Lancet Oncol 2006; 7:728-34. [PMID: 16945767 DOI: 10.1016/s1470-2045(06)70801-4] [Citation(s) in RCA: 151] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
BACKGROUND To assess individual treatment options for patients with carcinoid tumours, accurate knowledge of tumour localisation is essential. We aimed to test the diagnostic sensitivity of 6-[fluoride-18]fluoro-levodopa ((18)F-DOPA PET), compared with conventional imaging methods, in patients with carcinoid tumours. METHODS In a prospective, single-centre, diagnostic accuracy study, (18)F-DOPA PET with carbidopa pretreatment was compared with somatostatin-receptor scintigraphy (SRS), CT, and combined SRS and CT in 53 patients with a metastatic carcinoid tumour. The performance of all imaging methods was analysed for individual patients, for eight body regions, and for the detection of individual lesions. PET and CT images were fused to improve localisation. To produce a composite reference standard, we used cytological and histological findings; all imaging tests, including secondary assessments for newly found lesions; follow-up; and biochemical data. Sensitivities were calculated and compared. FINDINGS In patient-based analysis, we recorded sensitivities of 100% (95% CI 93-100) for (18)F-DOPA-PET, 92% (82-98) for SRS, 87% (75-95) for CT, and 96% (87-100) for combined SRS and CT (p=0.45 for (18)F-DOPA PET vs combined SRS and CT). However, (18)F-DOPA PET detected more lesions, more positive regions, and more lesions per region than combined SRS and CT. In region-based analysis, sensitivity of (18)F-DOPA PET was 95% (90-98) versus 66% (57-74) for SRS, 57% (48-66) for CT, and 79% (70-86) for combined SRS and CT (p=0.0001, PET vs combined SRS and CT). In individual-lesion analysis, corresponding sensitivities were 96% (95-98), 46% (43-50), 54% (51-58), and 65% (62-69; p<0.0001 for PET vs combined SRS and CT). INTERPRETATION If the improved tumour localisation seen with (18)F-DOPA-PET compared with conventional imaging is confirmed in future studies, this imaging method could replace use of SRS, help improve prediction of prognosis, and be used to assess patients' response to treatment for carcinoid tumours.
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Affiliation(s)
- Klaas P Koopmans
- Department of Nuclear Medicine and Molecular Imaging, University Medical Centre Groningen, Groningen, Netherlands
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Vassiliou AG, Vassilacopoulou D, Fragoulis EG. Purification of an endogenous inhibitor of L-Dopa decarboxylase activity from human serum. Neurochem Res 2005; 30:641-9. [PMID: 16176068 DOI: 10.1007/s11064-005-2752-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
An endogenous inhibitor of L-Dopa decarboxylase was identified and purified from human serum. In Triton X-114 partitioning experiments, the inhibitor was recovered in the detergent enriched phase, suggesting a hydrophobic nature. Purification was achieved by means of proteinase K digestion, ammonium sulphate precipitation, phenyl sepharose hydrophobic chromatography and subsequent extraction from a nondenaturing polyacrylamide gel. This purification scheme resulted in the isolation of a single 25 kDa band, bearing L-Dopa decarboxylase inhibitory activity. The purified molecule was found to be resistant to heat and digestion by various proteases. Proteolytic digestion of the purified inhibitor by pronase and aminopeptidase M was achieved only following carboxymethylation. The biological importance of the presence of an L-Dopa decarboxylase activity inhibitor in normal biological fluids remains to be elucidated. The better understanding of the regulation of Ddc enzymatic activity could prove valuable in the clarification of the enzyme's role in a series of pathological conditions, as well as, in physiological regulatory mechanisms.
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Affiliation(s)
- Alice-Georgia Vassiliou
- Dept of Biochemistry and Molecular Biology, University of Athens, Panepistimiopolis 15701, Athens, Greece
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Gilbert JA, Frederick LM, Pobst LJ, Ames MM. Hydrogen peroxide degradation and selective carbidopa-induced cytotoxicity against human tumor lines. Biochem Pharmacol 2005; 69:1159-66. [PMID: 15794936 DOI: 10.1016/j.bcp.2004.11.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2004] [Accepted: 11/09/2004] [Indexed: 11/26/2022]
Abstract
The carcinoid tumor, an uncommon neuroendocrine neoplasm, is associated with serotonin overproduction as is more common small cell lung carcinoma (SCLC). alpha-Methyl-dopahydrazine (carbidopa), an inhibitor of the serotonin synthetic enzyme aromatic-L-amino acid decarboxylase, proved lethal to NCI-H727 lung carcinoid cells as well as NCI-H146 and NCI-H209 SCLC cells, but not to five other human tumor cell lines of differing origins [Gilbert JA, Frederick LM, Ames MM. The aromatic-L-amino acid decarboxylase inhibitor carbidopa is selectively cytotoxic to human pulmonary carcinoid and small cell lung carcinoma cells. Clin. Cancer Res. 2000;6:4365-72]. The mechanism of carbidopa cytotoxicity remained an unanswered question. We present data here that incubation of the catechol carbidopa (100 microM) in RPMI and DMEM culture media yielded molar equivalents of hydrogen peroxide (H2O2) within 2-4 h. Alkaline elution studies revealed carbidopa-dependent single-strand DNA breaks in sensitive carcinoid cells comparable to those induced by similar concentrations of H2O2. Neither compound induced significant DNA damage in carbidopa-resistant NCI-H460 large cell lung carcinoma cells. Furthermore, when carbidopa was incubated with a variety of tumor cell types, not only were decreased media H2O2 concentrations detected in the presence of cells, but cell lines least sensitive to carbidopa degraded exogenous H2O2 more rapidly than did sensitive cells. Implicated in these studies, pyruvate degraded H2O2 in RPMI in a dose- and time-dependent manner and reversed carbidopa-induced cytotoxicity to carcinoid cells. Extracellular pyruvate levels produced per h by resistant large cell lung carcinoma cells averaged four-fold that of sensitive carcinoid cells plated at equal density (24 h time course). Finally, carbidopa exposure (100 microM, 24 h) depleted extracellular pyruvate from sensitive carcinoid cells, but reduced pyruvate levels from resistant NCI-H460 cells less than 17%.
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Affiliation(s)
- Judith A Gilbert
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic and Foundation, Guggenheim 13, 200 First Street S.W., Rochester, MN 55905, USA
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Murali D, Flores LG, Roberts AD, Nickles RJ, DeJesus OT. Aromatic L-amino acid decarboxylase (AAAD) inhibitors as carcinoid tumor-imaging agents: synthesis of 18F-labeled alpha-fluoromethyl-6-fluoro-m-tyrosine (FM-6-FmT). Appl Radiat Isot 2004; 59:237-43. [PMID: 14522231 DOI: 10.1016/s0969-8043(03)00197-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The aromatic L-amino acid decarboxylase (AAAD) enzyme is significantly upregulated in neuroendocrine tumors and, thus, would be a good target for PET imaging agents. Alpha-fluoromethyl-DOPA (FMDOPA) is one of the most potent irreversible AAAD inhibitor and its non-catechol derivative, alpha-fluoromethyl-m-tyrosine (FMmT), is a promising AAAD imaging agent. We synthesized FMmT and its direct electrophilic fluorination provided a mixture of products identified by NMR analysis after HPLC purification as 6-fluoro-, 2-fluoro- and 2,6-difluoro-derivatives of FMmT. Using rat striatal homogenates, alpha-fluoromethyl-6-fluoro-m-tyrosine (FM-6-FmT) was found to have AAAD inhibitory activity comparable to that of FMDOPA. Electrophilic radiofluorination of FMmT using [18F]AcOF gave 18F labeled 6-fluoro-, 2-fluoro- and 2,6-difluoro-FMmT derivatives in 22.0%, 21.9% and 8.5% radiochemical yields, respectively. Based on its proposed mechanism of inhibition, FM-6-[18F]FmT is expected to irreversibly bind to AAAD and, hence, could be used as a PET agent to image tumors of endocrine origin containing high concentrations of AAAD. Since FM-6-FmT lacks the catechol moiety, it is expected to be better than FMDOPA since it is not a substrate for catechol-O-methyltransferase.
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Affiliation(s)
- D Murali
- Department of Medical Physics, University of Wisconsin Medical School, 1530 Medical Sciences Center, 1300 University Avenue, Madison, WI 53706, USA
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Meijer WG, Copray SCVM, Hollema H, Kema IP, Zwart N, Mantingh-Otter I, Links TP, Willemse PHB, de Vries EGE. Catecholamine-synthesizing enzymes in carcinoid tumors and pheochromocytomas. Clin Chem 2003; 49:586-93. [PMID: 12651811 DOI: 10.1373/49.4.586] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND Serotonin is the principal endocrine product of carcinoid tumors, but simultaneously increased production of catecholamines has been described in these tumors. As it is not clear whether these tumors contain specific enzymes for catecholamine synthesis, we aimed to detect catecholamine-synthesizing enzymes [tyrosine hydroxylase (TH), dopamine-beta-hydroxylase (DBH), and phenylethanolamine-N-methyltransferase (PNMT)] in midgut carcinoid tumors and pheochromocytoma and to correlate enzyme expression to serotonin production as well as catecholamines and metabolites excreted in urine. METHODS Paraffin-embedded tumor specimens from 21 midgut carcinoid patients and 20 pheochromocytoma patients (10 sporadic and 10 MEN type IIa-related tumors) were stained for TH, DBH, and PNMT, using a three-step biotin-avidin-peroxidase method. RESULTS TH was demonstrated in 9 (43%) of 21 carcinoids and in all (100%) of 20 pheochromocytomas, DBH in 8 (38%) carcinoids and in 15 (75%) pheochromocytomas, and PNMT in 7 (33%) carcinoids and in 13 (65%) pheochromocytomas. Increased urinary excretion of catecholamines and metabolites was observed in 10 (48%) carcinoid patients and in all pheochromocytoma patients. No clinically relevant association between enzyme expression and urinary excretion of catecholamines and metabolites was found. CONCLUSIONS Catecholamine-synthesizing enzymes are present in many carcinoid tumors. This finding possibly indicates the existence of a catecholamine-synthesizing pathway in carcinoids similar to that found in pheochromocytoma.
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Affiliation(s)
- Wim G Meijer
- Department of Medical Oncology, University Hospital Groningen, The Netherlands
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Poulikakos P, Vassilacopoulou D, Fragoulis EG. L-DOPA decarboxylase association with membranes in mouse brain. Neurochem Res 2001; 26:479-85. [PMID: 11513473 DOI: 10.1023/a:1010952610387] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
This work presents evidence on the association of active DDC molecules with membranes in mammalian brain. L-DOPA decarboxylase (DDC) is generally considered to be a cytosolic enzyme. Membrane-associated DDC was detected by immunoblotting and enzymatic assay experiments. DDC activity and immunoreactivity could be partially extracted from mammalian brain membranes by detergent. Fractionation of membranes by temperature-induced phase separation in Triton X-114, resulted in the recovery of membrane-associated DDC in separation phases where integral and hydrophobic membrane proteins separate. Treatment of membranes with phosphatidylinositol-specific phospholipase C or proteinase K, did not elute membrane-associated DDC activity, suggesting that a population of DDC molecules exist embedded within membranes. The elucidation of the functional significance of the enzyme's association with membranes could provide us with new information leading to the better understanding of the biological pathways that DDC is involved in.
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Affiliation(s)
- P Poulikakos
- University of Athens, Dept. of Biochemistry and Molecular Biology, Greece
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Abstract
Since 1965 when the first paraneoplastic antineuronal antibody was reported by Wilkinson and Zeromski (55), the number of immunological responses detected in association with paraneoplastic syndromes of the nervous system has steadily increased. These responses are characterized by the presence of antineuronal antibodies in serum and CSF and/or infiltrates of T-cells in the tumor and nervous system. A few syndromes are mediated by antibodies; they include those resulting from dysfunction of the neuromuscular junction at the pre- or post-synaptic level (Lambert-Eaton myasthenic syndrome, myasthenia gravis) or ion channel dysfunction in the peripheral nervous system (i.e, Voltage-gated potassium channel and neuromyotonia). In most other paraneoplastic syndromes, including those involving the central nervous system, the pathogenic role of highly specific antineuronal antibodies (anti-Hu, anti-Yo, etc.) has not been established; nevertheless these antibodies should be regarded as useful markers of specific paraneoplastic syndromes and tumors. Moreover, there is increasing evidence that in some of these syndromes T-cell mediated mechanisms can cause the neurologic dysfunction and contribute to tumor rejection. Some paraneoplastic syndromes are caused by the tumor secretion of antibodies (macroglobulinemia and MAG antibodies), hormones, and cytokines. In other instances, the tumor may compete with the nervous system for an essential substrate (glucose, tryptophan) and result in neurologic dysfunction.
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Affiliation(s)
- J Dalmau
- Department of Neurology, Memorial Sloan-Kettering Cancer Center, New York, NY, 10021, USA.
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Berry MD, Juorio AV, Li XM, Boulton AA. Aromatic L-amino acid decarboxylase: a neglected and misunderstood enzyme. Neurochem Res 1996; 21:1075-87. [PMID: 8897471 DOI: 10.1007/bf02532418] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Classically, aromatic L-amino acid decarboxylase (AADC) has been regarded as an unregulated, rather uninteresting enzyme. In this review, we describe advances made during the past 10 years, demonstrating that AADC is regulated both pre- and post-translation. The significance of such regulatory mechanisms is poorly understood at present, but the presence of tissue specific control of expression raises the real possibility of AADC being involved in processes other than neuro-transmitter synthesis. We further discuss clinical and physiological situations in which such regulatory mechanisms may be important, including the intriguing possibility of AADC gene regulation being linked to that of factors thought to have a role in apoptosis and its prevention.
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Affiliation(s)
- M D Berry
- Department of Psychiatry, University of Saskatchewan, Saskatoon, Canada
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