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Xiong X, Huang B, Gan Z, Liu W, Xie Y, Zhong J, Zeng X. Ubiquitin-modifying enzymes in thyroid cancer:Mechanisms and functions. Heliyon 2024; 10:e34032. [PMID: 39091932 PMCID: PMC11292542 DOI: 10.1016/j.heliyon.2024.e34032] [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: 03/04/2024] [Revised: 06/25/2024] [Accepted: 07/02/2024] [Indexed: 08/04/2024] Open
Abstract
Thyroid cancer is the most common malignant tumor of the endocrine system, and evidence suggests that post-translational modifications (PTMs) and epigenetic alterations play an important role in its development. Recently, there has been increasing evidence linking dysregulation of ubiquitinating enzymes and deubiquitinases with thyroid cancer. This review aims to summarize our current understanding of the role of ubiquitination-modifying enzymes in thyroid cancer, including their regulation of oncogenic pathways and oncogenic proteins. The role of ubiquitination-modifying enzymes in thyroid cancer development and progression requires further study, which will provide new insights into thyroid cancer prevention, treatment and the development of novel agents.
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Affiliation(s)
- Xingmin Xiong
- Department of Thyroid and Hernia Surgery, First Affiliated Hospital of Gannan Medical University, Ganzhou, Jiangxi, 341000, China
- Key Laboratory of Prevention and Treatment of Cardiovascular and Cerebrovascular Diseases, Ministry of Education, Gannan Medical University, 323 National Road, Ganzhou, 341000, Jiangxi, China
| | - BenBen Huang
- Key Laboratory of Prevention and Treatment of Cardiovascular and Cerebrovascular Diseases, Ministry of Education, Gannan Medical University, 323 National Road, Ganzhou, 341000, Jiangxi, China
| | - Zhe Gan
- Ganzhou Key Laboratory of Thyroid Cancer, First Affiliated Hospital of Gannan Medical University, Ganzhou, Jiangxi, 341000, China
| | - Weixiang Liu
- Institute of Thyroid and Parathyroid Disease, Gannan Medical University, Ganzhou, Jiangxi, 341000, China
| | - Yang Xie
- Department of Thyroid and Hernia Surgery, First Affiliated Hospital of Gannan Medical University, Ganzhou, Jiangxi, 341000, China
- Ganzhou Key Laboratory of Thyroid Cancer, First Affiliated Hospital of Gannan Medical University, Ganzhou, Jiangxi, 341000, China
| | - Jianing Zhong
- Key Laboratory of Prevention and Treatment of Cardiovascular and Cerebrovascular Diseases, Ministry of Education, Gannan Medical University, 323 National Road, Ganzhou, 341000, Jiangxi, China
| | - Xiangtai Zeng
- Department of Thyroid and Hernia Surgery, First Affiliated Hospital of Gannan Medical University, Ganzhou, Jiangxi, 341000, China
- Institute of Thyroid and Parathyroid Disease, Gannan Medical University, Ganzhou, Jiangxi, 341000, China
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Romashin D, Rusanov A, Tolstova T, Varshaver A, Netrusov A, Kozhin P, Luzgina N. Loss of mutant p53 in HaCaT keratinocytes promotes cadmium-induced keratin 17 expression and cell death. Biochem Biophys Res Commun 2024; 709:149834. [PMID: 38547608 DOI: 10.1016/j.bbrc.2024.149834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Revised: 03/18/2024] [Accepted: 03/25/2024] [Indexed: 04/13/2024]
Abstract
BACKGROUND Cadmium exposure induces dermatotoxicity and epidermal barrier disruption and leads to the development of various pathologies. HaCaT cells are immortalized human keratinocytes that are widely used as alternatives to primary human keratinocytes, particularly for evaluating cadmium toxicity. HaCaT cells bear two gain-of-function (GOF) mutations in the TP53 gene, which strongly affect p53 function. Mutant forms of p53 are known to correlate with increased resistance to various stimuli, including exposure to cytotoxic substances. In addition, keratin 17 (KRT17) was recently shown to be highly expressed in HaCaT cells in response to genotoxic stress. Moreover, p53 is a direct transcriptional repressor of KRT17. However, the impact of TP53 mutations in HaCaT cells on the regulation of cell death and keratin 17 expression is unclear. In this study, we aimed to evaluate the impact of p53 on the response to Cd-induced cytotoxicity. METHODS AND RESULTS Employing the MTT assay and Annexin V/propidium iodide staining, we demonstrated that knockout of TP53 leads to a decrease in the sensitivity of HaCaT cells to the cytotoxic effects of cadmium. Specifically, HaCaT cells with TP53 knockout (TP53 KO HaCaT) exhibited cell death at a cadmium concentration of 10 μM or higher, whereas wild-type cells displayed cell death at a concentration of 30 μM. Furthermore, apoptotic cells were consistently detected in TP53 KO HaCaT cells upon exposure to low concentrations of cadmium (10 and 20 μM) but not in wild-type cells. Our findings also indicate that cadmium cytotoxicity is mediated by reactive oxygen species (ROS), which were significantly increased only in TP53 knockout cells treated with 30 μM cadmium. An examination of proteomic data revealed that TP53 knockout in HaCaT cells resulted in the upregulation of proteins involved in the regulation of apoptosis, redox systems, and DNA repair. Moreover, RT‒qPCR and immunoblotting showed that cadmium toxicity leads to dose-dependent induction of keratin 17 in p53-deficient cells but not in wild-type cells. CONCLUSIONS The connection between mutant p53 in HaCaT keratinocytes and increased resistance to cadmium toxicity was demonstrated for the first time. Proteomic profiling revealed that TP53 knockout in HaCaT cells led to the activation of apoptosis regulatory circuits, redox systems, and DNA repair. In addition, our data support the involvement of keratin 17 in the regulation of DNA repair and cell death. Apparently, the induction of keratin 17 is p53-independent but may be inhibited by mutant p53.
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Affiliation(s)
- Daniil Romashin
- Institute of Biomedical Chemistry, 10 Pogodinskaya St., Moscow, 119121, Russia
| | - Alexander Rusanov
- Institute of Biomedical Chemistry, 10 Pogodinskaya St., Moscow, 119121, Russia.
| | - Tatiana Tolstova
- Institute of Biomedical Chemistry, 10 Pogodinskaya St., Moscow, 119121, Russia
| | - Alexandra Varshaver
- Institute of Biomedical Chemistry, 10 Pogodinskaya St., Moscow, 119121, Russia
| | - Alexander Netrusov
- Lomonosov Moscow State University, GSP-1, Leninskie Gory, Moscow, 119991, Russia
| | - Peter Kozhin
- Institute of Biomedical Chemistry, 10 Pogodinskaya St., Moscow, 119121, Russia
| | - Nataliya Luzgina
- Institute of Biomedical Chemistry, 10 Pogodinskaya St., Moscow, 119121, Russia
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Mahendran R, Selvaraj SP, Dhanapal AR, Sarasa SB, Mathias BM, Thankappan B, Femil Selta DR, Naveen P, Poorani R, Sundhar N, Pillai MM, Selvakumar R, Huang CY, Eswaran R, Angayarkanni J. Tetrahydrobiopterin from cyanide-degrading bacterium Bacillus pumilus strain SVD06 induces apoptosis in human lung adenocarcinoma cell (A549). Biotechnol Appl Biochem 2023; 70:2052-2068. [PMID: 37731306 DOI: 10.1002/bab.2509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2023] [Accepted: 08/24/2023] [Indexed: 09/22/2023]
Abstract
Tetrahydrobiopterin (BH4) is an essential biological cofactor and a derivative of pterin which is considered potent anticancer agents. In continuation of our previous study on the identification of BH4 from cyanide-degrading Bacillus pumilus, the present study focuses on evaluating the anticancer properties of BH4 on A549, a human lung adenocarcinoma. Anticancer activity analysis shows that BH4 inhibited A549 cell growth after 24 h of incubation with 0.02 mg/mL. In acridine orange/ethidium bromide staining, BH4-treated A549 cells showed apoptotic morphology. BH4 treatment caused cell cycle arrest at G0/G1 phase compared to control cells. BH4 augmented p53 expression in alveolar cancer cells by downregulating MDM2 levels. There was downregulation of casp-3 and upregulation of iNOS gene in BH4-treated A549 cells. Further, docking studies indicated that BH4 had significant interactions with the above proteins affirming the apoptosis mechanism. Thus, BH4 could be considered a potential anticancer drug.
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Affiliation(s)
- Ramasamy Mahendran
- Cancer Therapeutics Laboratory, Department of Microbial Biotechnology, Bharathiar University, Coimbatore, Tamil Nadu, India
- Cardiovascular and Mitochondrial Related Disease Research Center, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Hualien, Taiwan
| | - Sanjay Prasad Selvaraj
- Molecular and Biological Agricultural Science Program, Taiwan International Graduate Program, Academia Sinica, Taipei, Taiwan
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Anand Raj Dhanapal
- Institute of Forest Genetics and Tree Breeding (IFGTB), Forest Campus, Coimbatore, Tamil Nadu, India
| | - Sabna Bhaskaran Sarasa
- Cancer Therapeutics Laboratory, Department of Microbial Biotechnology, Bharathiar University, Coimbatore, Tamil Nadu, India
| | - Beutline Malgija Mathias
- Computational Science Laboratory, MCC-MRF Innovation Park, Madras Christian College, Chennai, Tamil Nadu, India
| | - Bency Thankappan
- Cancer Therapeutics Laboratory, Department of Microbial Biotechnology, Bharathiar University, Coimbatore, Tamil Nadu, India
| | - Daniel Raja Femil Selta
- Department of Biochemistry and Cancer Research Center, FASCM, Karpagam Academy of Higher Education, Coimbatore, Tamil Nadu, India
| | - Palanivel Naveen
- Department of Chemistry, Sona College of Arts and Science, Salem, Tamil Nadu, India
| | - Rhenghachar Poorani
- Gayatri Vidya parishad Institute of Health Care and Medical Technology, Visakhapatnam, India
| | - Navaneethan Sundhar
- Graduate Institute of Biomedical Sciences, School of Medicine, China Medical University, Taichung, Taiwan
| | - Mamatha M Pillai
- Tissue Engineering Laboratory, PSG Institute of Advanced Studies, Coimbatore, Tamil Nadu, India
| | - Rajendran Selvakumar
- Tissue Engineering Laboratory, PSG Institute of Advanced Studies, Coimbatore, Tamil Nadu, India
| | - Chih-Yang Huang
- Cardiovascular and Mitochondrial Related Disease Research Center, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Hualien, Taiwan
- Department of Biological Science and Technology, College of Life Sciences, China Medical University, Taichung, Taiwan
- PhD Program for Biotechnology Industry, China Medical University, Taichung, Taiwan
- Department of Medical Research, China Medical University Hospital, China Medical University, Taichung, Taiwan
- Department of Biotechnology, Asia University, Taichung, Taiwan
- Center of General Education, Buddhist Tzu Chi Medical Foundation, Tzu Chi University of Science and Technology, Hualien, Taiwan
| | - Raju Eswaran
- Department of Zoology, The Madura College, Madurai, Tamil Nadu, India
| | - Jayaraman Angayarkanni
- Cancer Therapeutics Laboratory, Department of Microbial Biotechnology, Bharathiar University, Coimbatore, Tamil Nadu, India
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Gaillard B, Juarez-Krieguer C, Golinelli-Cohen MP. [MDM2 promotes cell death by interacting with mitochondrial bioenergetics]. Med Sci (Paris) 2021; 37:397-399. [PMID: 33908859 DOI: 10.1051/medsci/2021040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Pour la sixième année, dans le cadre du module d’enseignement « Physiopathologie de la signalisation » proposé par l’université Paris-sud, les étudiants du Master « Biologie Santé » de l’université Paris-Saclay se sont confrontés à l’écriture scientifique. Ils ont sélectionné une quinzaine d’articles scientifiques récents dans le domaine de la signalisation cellulaire présentant des résultats originaux, via des approches expérimentales variées, sur des thèmes allant des relations hôte-pathogène aux innovations thérapeutiques, en passant par la signalisation hépatique et le métabolisme. Après un travail préparatoire réalisé avec l’équipe pédagogique, les étudiants, organisés en binômes, ont ensuite rédigé, guidés par des chercheurs, une Nouvelle soulignant les résultats majeurs et l’originalité de l’article étudié. Ils ont beaucoup apprécié cette initiation à l’écriture d’articles scientifiques et, comme vous pourrez le lire, se sont investis dans ce travail avec enthousiasme ! Trois de ces Nouvelles sont publiées dans ce numéro, les autres le seront dans des prochains numéros.
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Dillon R, Nilsson CL, Shi SDH, Lee NV, Krastins B, Greig MJ. Discovery of a Novel B-Raf Fusion Protein Related to c-Met Drug Resistance. J Proteome Res 2011; 10:5084-94. [DOI: 10.1021/pr200498v] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
| | - Carol L. Nilsson
- University of Texas Medical Branch, Galveston, TX 77555, United States
| | | | - Nathan V. Lee
- Pfizer Global Research and Development, La Jolla, California 92121, United States
| | - Bryan Krastins
- Biomarker Research Initiatives in Mass Spectrometry (BRIMS), Thermo Fisher Scientific, Cambridge, Massachusetts 02139, United States
| | - Michael J. Greig
- Pfizer Global Research and Development, La Jolla, California 92121, United States
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Hew HC, Liu H, Miki Y, Yoshida K. PKCδ regulates Mdm2 independently of p53 in the apoptotic response to DNA damage. Mol Carcinog 2011; 50:719-31. [PMID: 21374733 DOI: 10.1002/mc.20748] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2010] [Accepted: 01/16/2011] [Indexed: 01/16/2023]
Abstract
Apoptosis is the key process in which cells with defective genome can be eliminated. Dys-regulation of apoptosis causes accumulation of irreparable mutation arisen from DNA damage and is the underlying cause of carcinogenesis. PKCδ is a multifunctional kinase involved in signal transduction of genotoxic-induced apoptosis. Previous studies have demonstrated that PKCδ transactivates p53 in response to DNA damage. These findings led us to determine if Mdm2, a nuclear phospho-protein and negative regulator of p53, could also be a PKCδ-modulated substrate. We discovered that inhibition of PKCδ down-regulates Mdm2 protein expression regardless of p53 status. Given that Mdm2 mRNA change was detected in p53-proficient, but not deficient cells, PKCδ affected Mdm2 on the post-translational level. Interestingly, treatment of MG132 restored Mdm2 expression to the steady-state level. Further investigation showed that PKCδ inhibited Mdm2 ubiquitination in p53-deficient cells and loss of PKCδ resulted in an increase in Mdm2 proteosomal degradation. Moreover, P300/CBP-associated factor (PCAF), an ubiquitin ligase 3 for Mdm2, was observed to participate in Mdm2 ubiquitination by PKCδ inhibition and knock-down of PCAF rescued Mdm2 diminution. Finally, as shown for PKCδ, Mdm2 was also required to exert pro-apoptotic response caused by genotoxic agents in p53-null cells. In addition, overexpression of Mdm2 restored inhibitory effect of apoptosis in cells silenced for PKCδ. Taken together, we conclude that PKCδ regulates Mdm2 expression distinctively of p53 pathway by affecting Mdm2 ubiquitination and maintenance of Mdm2 expression by PKCδ is important to ensure normal genotoxic cell death response in human cancer cells.
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Affiliation(s)
- Hoi Chin Hew
- Department of Molecular Genetics, Medical Research Institute, Tokyo Medical and Dental University, Japan
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Abd-Elhamid ES, Elshafei MM. Immunohistochemical localization of mdm-2, p27Kip1 and bcl-2 in Warthin's tumor of the parotid gland. Diagn Pathol 2009; 4:14. [PMID: 19445705 PMCID: PMC2693442 DOI: 10.1186/1746-1596-4-14] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2009] [Accepted: 05/16/2009] [Indexed: 01/18/2023] Open
Abstract
Background Warthin's tumor is a benign monomorphic adenoma with unclear origin that almost occur exclusively in the parotid gland. Etiology of Warthin's tumor as well as its malignant potential are still unclear. Therefore immunohistochemical assessment of Warthin's tumor may be useful to detect its origin or its malignant transformation potential. Aims and objectives The present study aims to investigate the immunohistochemical expression of murine double minute-2 (mdm-2), p27Kip1 and B cell lymphoma-2 (bcl-2) in Warthin's tumor of parotid gland and also to clarify the role of these proteins in the behavior of that tumor. Methods Twenty paraffin blocks of cases previously diagnosed as Warthin's tumor were collected for immunohistochemical staining with primary antibodies against mdm-2, p27Kip1 and bcl-2 using streptavidin-biotin immunoperoxidase staining system. Results All cases showed immunopositivity for mdm-2 and p27Kip1 while 18/20 showed bcl-2 immunopositivity. Both layers of the neoplastic epithelial cells that line the cystic spaces showed immunopositivity with all antibodies used. Goblet cells were mdm-2 immunonegative while myoepithelial cells were p27Kip-1 immunonegative. Areas of epithelial proliferation that formed buds were p27Kip-1 and bcl-2 immunopositive. Conclusion Mdm-2 played a tumor-suppressor role that might be implicated with the benign behavior of Warthin's tumor. The mutual expression of both p27Kip1 and bcl-2 suggested a protective role of these slowly proliferating cells from apoptosis to maintain their survival and elevated bcl-2 expression offers a significant protection against p27Kip1-mediated apoptosis.
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Affiliation(s)
- Ehab S Abd-Elhamid
- Oral Pathology Department, Faculty of Dentistry, Ain Shams University, Cairo, Egypt.
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Nakamura Y, Suzuki S, Suzuki T, Ono K, Miura I, Satoh F, Moriya T, Saito H, Yamada S, Ito S, Sasano H. MDM2: a novel mineralocorticoid-responsive gene involved in aldosterone-induced human vascular structural remodeling. THE AMERICAN JOURNAL OF PATHOLOGY 2006; 169:362-71. [PMID: 16877339 PMCID: PMC1698800 DOI: 10.2353/ajpath.2006.051351] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Aldosterone has been demonstrated to play an important role in the pathogenesis of various cardiovascular diseases. Vascular structural remodeling, including vascular smooth muscle cell (VSMC) proliferation, has been also reported in small resistance arteries of patients with primary aldosteronism. Therefore, in this study, we examined whether genes involved in the regulation of the cell cycle were induced by aldosterone alone in cultured human VSMCs and in human small resistance arteries. Results of these studies eventually demonstrated that MDM2, one of the genes involved in anti-apoptosis and cell growth, was markedly increased in mineralocorticoid receptor (MR)-positive VSMCs by aldosterone in all microarray, reverse transcriptase-polymerase chain reaction, immunoblotting, and immunofluorescence analyses. In addition, an analysis using small interfering RNA demonstrated that this gene product was involved in cell proliferation of VSMCs induced by aldosterone. Eplerenone, a specific MR antagonist, inhibited this gene induction by aldosterone in VSMCs. MDM2 protein was also more abundant in VSMCs of small resistance arteries in patients with primary aldosteronism compared with a control population. MDM2 is therefore considered one of the mineralocorticoid-responsive genes that regulates cell proliferation of VSMCs induced by MR-mediated aldosterone stimulation, possibly playing an important role in aldosterone-induced vascular structural remodeling.
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Affiliation(s)
- Yasuhiro Nakamura
- Department of Pathology, Tohoku University School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan
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9
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Bell HS, Whittle IR, Bader SA, Wharton SB. Discovery of a perinecrotic 60 kDa MDM2 isoform within glioma spheroids and glioblastoma biopsy material. Neuropathol Appl Neurobiol 2005; 31:191-202. [PMID: 15771712 DOI: 10.1111/j.1365-2990.2004.00627.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Necrosis in glioblastoma is often associated with high levels of Fas (APO-1), HIF-1alpha and PARP expression. The presence of such molecules suggests a regulative element to cell death within this tissue, which may involve p53. We aimed to establish whether p53 and its downstream targets Bax, MDM2 and p21 play a role in perinecrotic cell death in glioblastoma. Following sequencing of the p53 gene in U87 and U373 glioma cell lines, p53 was found to be reactive in the p53 wild-type line U87 in response to hypoxia but not in the p53 mutant line, U373. Although no increase in perinecrotic p53 expression was detected in spheroid cultures derived from these lines, a 60 kDa MDM2 isoform lacking a C-terminal domain showed perinecrotic localization, irrespective of p53 status. Similar findings were observed surrounding regions of necrosis in 80% of glioblastoma biopsies examined. Increasing levels of wild-type p53 did not affect cell death in U87 spheroid cultures but killed all U373 cells 3 days post transfection. Dominant negative p53 did not affect cell death in U373 and U87 spheroid cultures. Although p53 accumulation appeared not to be important for the onset of cell death both in spheroid and biopsy cases, high levels of perinecrotic 60 kDa MDM2 may have implications for glioma cell death susceptibility in both p53 mutant and wild-type tumour cell populations.
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Affiliation(s)
- H S Bell
- The Beatson Institute for Cancer Research, Garscube Estate, Glasgow, UK.
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Miao ZH, Tong LJ, Zhang JS, Han JX, Ding J. Characterization of salvicine-resistant lung adenocarcinoma A549/SAL cell line. Int J Cancer 2004; 110:627-32. [PMID: 15146550 DOI: 10.1002/ijc.20026] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Salvicine is a diterpenoid quinone derived from a traditional Chinese medication that has been shown to possess potent in vitro and in vivo antitumor effects. This compound, which inhibits the activity of Topoisomerase II, was found to equipotently kill various multidrug-resistant tumor cells and their corresponding parental counterparts in vitro and to inhibit mdr1/P-gp expression in multidrug-resistant K562/A02 cells. To examine the features of tumor resistance to salvicine, we established a salvicine-resistant tumor cell subline of A549 lung adenocarcinoma cells. Compared with parental cells, A549/SAL cells displayed 8.91-fold resistance to salvicine and an average of 6.70-fold resistance to the antimetabolites. A549/SAL cells, however, were not resistant to alkylating agents, platinum compounds and other naturally-derived antineoplastics. RT-PCR analysis showed that the expression of mRNAs from the mdr-1, MRP, PCNA, topoisomerase II alpha and beta, GSTpi, p21 and GADD45 genes was not altered in the salvicine-resistant subline. In contrast, expression of p53 and bax mRNA was significantly lower, and expression of mdm2 mRNA was significantly higher, in A549/SAL cells compared to A549 cells. A549/SAL cells grew more slowly, and in a more scattered pattern, than A549 cells. In addition, the A549/SAL cells showed enhanced ability to migrate and invade in comparison to the parental cells. These results indicate that exposure to salvicine does not induce a tumor multidrug-resistant phenotype.
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Affiliation(s)
- Ze-Hong Miao
- Division of Anti-tumor Pharmacology, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, PR China
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Abstract
MDM2 has been characterized as a protein that binds to and facilitates degradation of the tumor suppressor p53. Interestingly, more than 40 different splice variants of MDM2 transcripts have been identified both in tumors and normal tissues, and the majority of these variants do not contain sequence encoding the p53 binding site. This review describes the different splice forms, the tissues in which they have been identified, and their association with tumor progression and prognosis. In addition, we discuss the potential functions of these variants and how they interact with full-length MDM2 protein.
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Affiliation(s)
- Frank Bartel
- Department of Molecular Pharmacology, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, USA
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Dilla T, Romero J, Sanstisteban P, Velasco JA. The mdm2 proto-oncogene sensitizes human medullary thyroid carcinoma cells to ionizing radiation. Oncogene 2002; 21:2376-86. [PMID: 11948421 DOI: 10.1038/sj.onc.1205307] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2001] [Revised: 01/02/2002] [Accepted: 01/08/2002] [Indexed: 01/10/2023]
Abstract
We have analysed the radiation response of a human medullary thyroid carcinoma cell line (MTT), characterized by the absence of a functional p53 protein, and the consequences of MDM2 overexpression in this process. We show that the product of the mdm2 proto-oncogene is able to sensitize MTT cells to ionizing radiation. After radiation treatment, MTT cells display histograms consistent with a G2M arrest. MTT cells expressing MDM2 (MTT-mdm2) are unable to respond to DNA damage with G2M arrest, and display a high percentage of apoptosis. MTT-mdm2 cells show high levels of E2F-1 protein, suggesting that the induction of apoptosis observed upon MDM2 overexpression could be dependent on E2F-1. This observation is further supported with assays showing that E2F-1 binding to specific DNA sequences is enhanced in MTT-mdm2 cells. Likewise, transactivation of reporter constructs exclusively dependent on E2F-1 is also elevated after transfection with MDM2. This effect can be reverted by transient transfection with p19ARF. To link the expression of E2F-1 with the induction of apoptosis, we generated clonal cell lines overexpressing E2F-1. Transfection with E2F-1 results in a low number of outgrowing colonies with reduced proliferation rates, indicating that E2F-1 is deleterious for cell growth. This negative regulation correlates with an increase in the percentage of the cell population with DNA content below 2N, suggesting that E2F-1 promotes apoptosis. Finally, overexpression of E2F-1 sensitizes MTT cells to radiation exposure. We conclude that the effects observed by MDM2 overexpression could be mediated by E2F-1.
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Affiliation(s)
- Tatiana Dilla
- Instituto de Investigaciones Biomédicas Alberto Sols, Consejo Superior de Investigaciones Científicas, Madrid, Spain
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Lin JD. The role of apoptosis in autoimmune thyroid disorders and thyroid cancer. BMJ (CLINICAL RESEARCH ED.) 2001; 322:1525-7. [PMID: 11420275 PMCID: PMC1120572 DOI: 10.1136/bmj.322.7301.1525] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- J D Lin
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Chang Gung Memorial Hospital, Chang Gung University, 5 Fu-Shin Street, Kweishan County, Taoyuan Hsien, Taiwan, Republic of China.
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