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Bassal MA. The Interplay between Dysregulated Metabolism and Epigenetics in Cancer. Biomolecules 2023; 13:944. [PMID: 37371524 DOI: 10.3390/biom13060944] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 05/21/2023] [Accepted: 05/29/2023] [Indexed: 06/29/2023] Open
Abstract
Cellular metabolism (or energetics) and epigenetics are tightly coupled cellular processes. It is arguable that of all the described cancer hallmarks, dysregulated cellular energetics and epigenetics are the most tightly coregulated. Cellular metabolic states regulate and drive epigenetic changes while also being capable of influencing, if not driving, epigenetic reprogramming. Conversely, epigenetic changes can drive altered and compensatory metabolic states. Cancer cells meticulously modify and control each of these two linked cellular processes in order to maintain their tumorigenic potential and capacity. This review aims to explore the interplay between these two processes and discuss how each affects the other, driving and enhancing tumorigenic states in certain contexts.
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Affiliation(s)
- Mahmoud Adel Bassal
- Cancer Science Institute of Singapore, National University of Singapore, Singapore 117599, Singapore
- Harvard Stem Cell Institute, Harvard Medical School, Boston, MA 02115, USA
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Gödecke N, Herrmann S, Weichelt V, Wirth D. A Ubiquitous Chromatin Opening Element and DNA Demethylation Facilitate Doxycycline-Controlled Expression during Differentiation and in Transgenic Mice. ACS Synth Biol 2023; 12:482-491. [PMID: 36755406 PMCID: PMC9942253 DOI: 10.1021/acssynbio.2c00450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
Synthetic expression cassettes provide the ability to control transgene expression in experimental animal models through external triggers, enabling the study of gene function and the modulation of endogenous regulatory networks in vivo. The performance of synthetic expression cassettes in transgenic animals critically depends on the regulatory properties of the respective chromosomal integration sites, which are affected by the remodeling of the chromatin structure during development. The epigenetic status may affect the transcriptional activity of the synthetic cassettes and even lead to transcriptional silencing, depending on the chromosomal sites and the tissue. In this study, we investigated the influence of the ubiquitous chromosome opening element (UCOE) HNRPA2B1-CBX3 and its subfragments A2UCOE and CBX3 on doxycycline-controlled expression modules within the chromosomal Rosa26 locus. While HNRPA2B1-CBX3 and A2UCOE reduced the expression of the synthetic cassettes in mouse embryonic stem cells, CBX3 stabilized the expression and facilitated doxycycline-controlled expression after in vitro differentiation. In transgenic mice, the CBX3 element protected the cassettes from overt silencing although the expression was moderate and only partially controlled by doxycycline. We demonstrate that CBX3-flanked synthetic cassettes can be activated by decitabine-mediated blockade of DNA methylation or by specific recruitment of the catalytic demethylation domain of the ten-eleven translocation protein TET1 to the synthetic promoter. This suggests that CBX3 renders the synthetic cassettes permissive for subsequent epigenetic activation, thereby supporting doxycycline-controlled expression. Together, this study reveals a strategy for overcoming epigenetic constraints of synthetic expression cassettes, facilitating externally controlled transgene expression in mice.
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Affiliation(s)
- Natascha Gödecke
- RG
Model Systems for Infection and Immunity, Helmholtz Centre for Infection Research, 38124 Braunschweig, Germany
| | - Sabrina Herrmann
- RG
Model Systems for Infection and Immunity, Helmholtz Centre for Infection Research, 38124 Braunschweig, Germany
| | - Viola Weichelt
- RG
Model Systems for Infection and Immunity, Helmholtz Centre for Infection Research, 38124 Braunschweig, Germany
| | - Dagmar Wirth
- RG
Model Systems for Infection and Immunity, Helmholtz Centre for Infection Research, 38124 Braunschweig, Germany,Institute
of Experimental Hematology, Medical University
Hannover (MHH), 30625 Hannover, Germany,
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Tumour suppressor 15-hydroxyprostaglandin dehydrogenase induces differentiation in colon cancer via GLI1 inhibition. Oncogenesis 2020; 9:74. [PMID: 32814764 PMCID: PMC7438320 DOI: 10.1038/s41389-020-00256-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Revised: 07/14/2020] [Accepted: 07/29/2020] [Indexed: 02/06/2023] Open
Abstract
Inflammation is an established risk factor for colorectal cancer. We and others have shown that colorectal cancer patients with elevated cysteinyl leukotriene receptor 2 (CysLT2R) and 15-hydroxyprostaglandin dehydrogenase (15-PGDH) levels exhibit good prognoses. However, both CysLT2R and 15-PGDH, which act as tumour suppressors, are often suppressed in colorectal cancer. We previously reported that leukotriene C4 (LTC4)-induced differentiation in colon cancer via CysLT2R signalling. Here, we investigated the involvement of Hedgehog (Hh)-GLI1 signalling, which is often hyperactivated in colorectal cancer. We found that the majority of colorectal cancer patients had high-GLI1 expression, which was negatively correlated with CysLT2R, 15-PGDH, and Mucin-2 and overall survival compared with the low-GLI1 group. LTC4-induced 15-PGDH downregulated both the mRNA and protein expression of GLI1 in a protein kinase A (PKA)-dependent manner. Interestingly, the LTC4-induced increase in differentiation markers and reduction in Wnt targets remained unaltered in GLI1-knockdown cells. The restoration of GLI1 in 15-PGDH-knockdown cells did not ameliorate the LTC4-induced effects, indicating the importance of both 15-PGDH and GLI1. LTC4-mediated reduction in the DCLK1 and LGR5 stemness markers in colonospheres was abolished in cells lacking 15-PGDH or GLI1. Both DCLK1 and LGR5 were highly increased in tumour tissue compared with the matched controls. Reduced Mucin-2 levels were observed both in zebrafish xenografts with GLI1-knockdown cells and in the cysltr2-/- colitis-associated colon cancer (CAC) mouse model. Furthermore, GLI1 expression was positively correlated with stemness and negatively correlated with differentiation in CRC patients when comparing tumour and mucosal tissues. In conclusion, restoring 15-PGDH expression via CysLT2R activation might benefit colorectal cancer patients.
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Ferreira MV, Cabral ET, Coroadinha AS. Progress and Perspectives in the Development of Lentiviral Vector Producer Cells. Biotechnol J 2020; 16:e2000017. [PMID: 32686901 DOI: 10.1002/biot.202000017] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 07/07/2020] [Indexed: 12/12/2022]
Abstract
After two decades of clinical trials, gene therapy demonstrated effectiveness in the treatment of a series of diseases. Currently, several gene therapy products are approved and used in the clinic. Lentiviral vectors (LVs) are one of the most used transfer vehicles to deliver genetic material and the vector of choice to modify hematopoietic cells to correct primary immunodeficiencies, hemoglobinopathies, and leukodystrophies. LVs are also widely used to modify T cells to treat cancers in immunotherapies (e.g., chimeric antigen receptors T cell therapies, CAR-T). In genome editing, LVs are used to deliver sequence-specific designer nucleases and DNA templates. The approval LV gene therapy products (e.g., Kymriah, for B-cell Acute lymphoblastic leukemia treatment; LentiGlobin, for β-thalassemia treatment) reinforced the need to improve their bioprocess manufacturing. The production has been mostly dependent on transient transfection. Production from stable cell lines facilitate GMP compliant processes, providing an easier scale-up, reproducibility and cost-effectiveness. The establishment of stable LV producer cell lines presents, however, several difficulties, with the cytotoxicity of some of the vector proteins being a major challenge. Genome editing technologies pose additional challenges to LV producer cells. Herein the major bottlenecks, recent achievements, and perspectives in the development of LV stable cell lines are revised.
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Affiliation(s)
- Mariana V Ferreira
- iBET, Instituto de Biologia Experimental e Tecnológica, Apartado 12, 2781-901, Oeiras, Portugal.,Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157, Oeiras, Portugal
| | - Elisa T Cabral
- iBET, Instituto de Biologia Experimental e Tecnológica, Apartado 12, 2781-901, Oeiras, Portugal.,Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157, Oeiras, Portugal
| | - Ana Sofia Coroadinha
- iBET, Instituto de Biologia Experimental e Tecnológica, Apartado 12, 2781-901, Oeiras, Portugal.,Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157, Oeiras, Portugal.,The Discoveries centre for Regenerative and Precision Medicine, Nova University Lisbon, Oeiras Campus, Av. da República, 2780-157, Oeiras, Portugal
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Cysteinyl leukotriene receptor 1 promotes 5-fluorouracil resistance and resistance-derived stemness in colon cancer cells. Cancer Lett 2020; 488:50-62. [PMID: 32474153 DOI: 10.1016/j.canlet.2020.05.023] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Revised: 04/22/2020] [Accepted: 05/20/2020] [Indexed: 12/15/2022]
Abstract
Colon cancer is a therapy-resistant cancer with a low 5-year survival frequency. The drug 5-fluorouracil (5-FU) has been used as a first-line therapy in metastatic colon cancer in combination with leucovorin or oxaliplatin with a >40% resistance rate. High CysLT1R expression in tumors is associated with poor survival of colon cancer patients. We sought to examine the role of CysLT1R in 5-FU resistance and established 5-FU-resistant (5-FU-R) colon cancer cells. These 5-FU-R-cells expressed increased levels of CysLT1R and showed increased survival and migration compared to nonresistant cells. Increases in thymidylate synthase and active β-catenin were also observed in the 5-FU-R-cells. LTD4/CysLT1R signaling was further increased and abolished after CYSLTR1 CRISPR-Cas9-knockdown and reduced in CysLT1R-doxycycline-knockdown experiments and CysLT1R-antagonist montelukast/5-FU-treated cells. Montelukast and 5-FU resulted in synergistic effects by reducing HT-29 cell and 5-FU-R-HT-29 cell migration and zebrafish xenograft metastasis. An increase in the stem cell markers in 5-FU-R-cells and 5-FU-R-cell-derived colonospheres and in CysLT1R-Dox-knockdown cells increased colonosphere formation and stem cell markers was noticed after 5-FU treatment. IL-4-mediated stemness in both HT-29-colonospheres and 5-FU-R-cell derived colonospheres was abolished by montelukast or montelukast + 5-FU-treatment. Targeting CysLT1R signaling by montelukast might reverse drug resistance and decrease resistance-derived stemness in colon cancer patients.
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Topi G, Satapathy SR, Dash P, Fred Mehrabi S, Ehrnström R, Olsson R, Lydrup ML, Sjölander A. Tumour-suppressive effect of oestrogen receptor β in colorectal cancer patients, colon cancer cells, and a zebrafish model. J Pathol 2020; 251:297-309. [PMID: 32333795 DOI: 10.1002/path.5453] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 04/05/2020] [Accepted: 04/16/2020] [Indexed: 12/31/2022]
Abstract
Oestrogen receptor β (ERβ) has been suggested to have anti-proliferative and anti-tumour effects in breast and prostate cancer cells, but other studies have indicated its tumour-promoting effects. Understanding the complex effects of this receptor in different contexts requires further study. We reported that high ERβ expression is independently associated with improved prognosis in female colorectal cancer (CRC) patients. Herein, we investigated the possible anti-tumour effect of ERβ and its selective agonist. CRC patients with high ERβ expression had significantly higher levels of membrane-associated β-catenin, cysteinyl leukotriene receptor 2 (CysLT2 R), and 15-hydroxyprostaglandin dehydrogenase (15-PGDH), which have anti-tumour effects, but lower levels of nuclear β-catenin, cysteinyl leukotriene receptor 1 (CysLT1 R), and cyclooxygenase-2 (COX-2), which have tumour-promoting effects. These interesting findings were further supported by two different publicly available CRC mRNA datasets that showed a significant positive correlation between ERβ expression and 15-PGDH and CysLT2 R expression and a negative correlation between ERβ expression and β-catenin, CysLT1 R, and COX-2 expression. We next evaluated ERβ expression in three different colon cancer mouse models; ERβ expression was negatively correlated with tumourigenesis. Furthermore, treatment with the ERβ-agonist ERB-041 reduced CysLT1 R, active β-catenin, and COX-2 levels but increased phospho-β-catenin, CysLT2 R, and 15-PGDH levels in HCT-116, Caco-2, and SW-480 colon cancer cells compared to vehicle-treated cells. Interestingly, ERB-041-treated cells showed significantly decreased migration, survival, and colonosphere formation and increased apoptotic activity, as indicated by increased CASPASE-3 and apoptotic blebs. Finally, patients with low ERβ expression had significantly more distant metastasis at the time of diagnosis than patients with high ERβ expression. Therefore, we studied the effects of ERB-041-treated colon cancer cells in a zebrafish xenograft model. We found significantly less distant metastasis of ERB-041-treated cells compared to vehicle-treated cells. These results further support ERβ's anti-tumour role in CRC and the possible use of its agonist in CRC patients. © 2020 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.
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Affiliation(s)
- Geriolda Topi
- Division of Cell Pathology, Department of Translational Medicine, Lund University, Skåne University Hospital, Malmö, Sweden
| | - Shakti Ranjan Satapathy
- Division of Cell Pathology, Department of Translational Medicine, Lund University, Skåne University Hospital, Malmö, Sweden
| | - Pujarini Dash
- Division of Cell Pathology, Department of Translational Medicine, Lund University, Skåne University Hospital, Malmö, Sweden
| | - Syrina Fred Mehrabi
- Division of Cell Pathology, Department of Translational Medicine, Lund University, Skåne University Hospital, Malmö, Sweden
| | - Roy Ehrnström
- Division of Pathology, Department of Translational Medicine, Lund University, Skåne University Hospital, Malmö, Sweden
| | - Roger Olsson
- The Chemical Biology and Therapeutics Division, Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Marie-Louise Lydrup
- Division of Surgery, Department of Clinical Sciences, Lund University, Skåne University Hospital, Malmö, Sweden
| | - Anita Sjölander
- Division of Cell Pathology, Department of Translational Medicine, Lund University, Skåne University Hospital, Malmö, Sweden
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Liu M, Wu R, Yang F, Wang T, Zhang P, Gu J, Wan D, Yang S. Identification of FN1BP1 as a novel cell cycle regulator through modulating G1 checkpoint in human hepatocarcinoma Hep3B cells. PLoS One 2013; 8:e57574. [PMID: 23469028 PMCID: PMC3585200 DOI: 10.1371/journal.pone.0057574] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Accepted: 01/22/2013] [Indexed: 01/05/2023] Open
Abstract
A novel human gene, FN1BP1 (fibronectin 1 binding protein 1), was identified using the human placenta cDNA library. Northern blotting showed a transcript of ∼2.8 kb in human placenta, liver, and skeletal muscle tissues. This mRNA transcript length was similar to the full FN1BP1 sequence obtained previously. We established a conditionally induced stable cell line of Hep3B-Tet-on-FN1BP1 to investigate the preliminary function and mechanism of the secretory FN1BP1 protein. Cell-proliferation and colony-conformation assays demonstrated that FN1BP1 protein suppressed Hep3B cell growth and colonization in vitro. Analysis of Atlas human cDNA expression indicated that after FN1BP1 Dox-inducing expression for 24 h, 19 genes were up-regulated and 22 genes were down-regulated more than two-fold. Most of these gene changes were related to cell-cycle-arrest proteins (p21cip1, p15, and cyclin E1), transcription factors (general transcription factors, zinc finger proteins, transcriptional enhancer factors), SWI/SNF (SWItch/Sucrose NonFermentable) complex units, early-response proteins, and nerve growth or neurotrophic factors. Down-regulated genes were subject to colony-stimulating factors (e.g., GMSFs), and many repair genes were involved in DNA damage (RAD, ERCC, DNA topoisomerase, polymerase, and ligase). Some interesting genes (p21cip1, ID2, GMSF, ERCC5, and RPA1), which changed in the cDNA microarray analysis, were confirmed by semi-qRT-PCR, and similar changes in expression were observed. FCM cell-cycle analysis indicated that FN1BP1 over-expression could result in G1 phase arrest. FN1BP1 might inhibit cell growth and/or colony conformation through G1 phase arrest of the Hep3B cell cycle. These results indicate the potential role of FN1BP1 as a treatment target for hepatocellular carcinoma.
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Affiliation(s)
- Mei Liu
- The Jingsu Key Laboratory of Neuroregeneration, Nantong University, Nantong, Jiangsu, China
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Jiaotong University, Shanghai, China
| | - Ronghua Wu
- The Jingsu Key Laboratory of Neuroregeneration, Nantong University, Nantong, Jiangsu, China
| | - Fuye Yang
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Jiaotong University, Shanghai, China
| | - Tao Wang
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Jiaotong University, Shanghai, China
| | - Pingping Zhang
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Jiaotong University, Shanghai, China
| | - Jianren Gu
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Jiaotong University, Shanghai, China
| | - Dafang Wan
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Jiaotong University, Shanghai, China
| | - Shengli Yang
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Jiaotong University, Shanghai, China
- * E-mail:
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Inhibition of pancreatic cancer cell growth in vivo using a tetracycline-inducible cyclin D1 antisense expression system. Pancreas 2013; 42:141-8. [PMID: 22722256 DOI: 10.1097/mpa.0b013e3182546de5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
OBJECTIVES Cyclin D1 is important for pancreatic cancer growth. Our aim was to determine the effects of cyclin D1 inhibition on the growth of established pancreatic tumors. METHODS PANC-1 cells harboring cyclin D1 antisense cDNA in a tetracycline-inducible vector system were prepared. The effects of cyclin D1 inhibition after tumor development were characterized in a mouse model. RESULTS In vitro removal of tetracycline induced cyclin D1 antisense cDNA expression and inhibited cyclin D1 expression and cyclin D1-associated kinase activity as well as anchorage-dependent and -independent growth. After establishment of xenograft tumors in the presence of tetracycline (2 mg/mL) in the drinking water, animals were assigned to either control (tetracycline remained in the drinking water) or to the group without tetracycline for which tetracycline was removed from the drinking water. Tumor growth was significantly inhibited after removal of tetracycline. Microscopic analysis revealed that the area of central necrosis was significantly increased in the group without tetracycline paralleled by a reduction of the vital peripheral area of proliferating cells. CONCLUSIONS Our results confirmed that cyclin D1 plays an important role in the growth of pancreatic cancer cells and may be an attractive molecular target for the treatment of human pancreatic cancer.
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El-Din HG, Ghafar NA, Saad NE, Aziz M, Rasheed D, Hassan EM. Relationship between codon 249 mutation in exon 7 of p53 gene and diagnosis of hepatocellular carcinoma. Arch Med Sci 2010; 6:348-55. [PMID: 22371770 PMCID: PMC3282511 DOI: 10.5114/aoms.2010.14254] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2009] [Revised: 05/14/2009] [Accepted: 06/10/2009] [Indexed: 02/02/2023] Open
Abstract
INTRODUCTION Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide. Multiple genetic and epigenetic changes are involved in the molecular pathogenesis of HCC. Heat shock proteins have essential roles in protecting cells from the potentially lethal effects of stress. Among them, HSP70 are often overexpressed in cells of various cancers and have been suggested to contribute to tumourigenesis. p53 mutations in codon 249 have also been identified in HCC. MATERIAL AND METHODS Fifty patients with liver disease were enrolled in this study compared to 10 healthy volunteers. The studied patients were divided into 2 groups: group I includes those suffering from HCC, group II includes those suffering from post-hepatitis B and C liver cirrhosis. The presence of p53 gene mutation was detected by DNA extraction from whole blood of patients and controls followed by polymerase chain reaction then restriction fragment length polymorphism (RFLP) analysis of codon 249 of exon 7. We also studied the genotypes of the HSP70 gene by PCR followed by RFLP analysis. RESULTS Our results revealed no statistical difference between group I, group II, and the control group as regards exon 7 mutation of the p53 gene. Also the frequency of polymorphic genotypes of HSP70 showed no significant difference between the 3 studied groups. CONCLUSIONS The present study supports the view that the incidence of point mutation of p53 codon 249 mutations in exon 7 of the p53 gene may not play a role in carcinogenesis of HCC in Egyptian patients. Also, genetic polymorphism in HSP70 was not associated with high risk of future development of HCC.
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Affiliation(s)
- Hesham Gamal El-Din
- Clinical and Chemical Pathology Department, National Research Centre, Cairo, Egypt
| | - Nagwa Abdel Ghafar
- Clinical and Chemical Pathology Department, National Research Centre, Cairo, Egypt
| | - Nevine E. Saad
- Clinical and Chemical Pathology Department, National Research Centre, Cairo, Egypt
| | - Mona Aziz
- Clinical and Chemical Pathology Department, National Research Centre, Cairo, Egypt
| | - Dina Rasheed
- Clinical and Chemical Pathology Department, Cairo University, Egypt
| | - Eman Mahmoud Hassan
- Clinical and Chemical Pathology Department, National Research Centre, Cairo, Egypt
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Tam KH, Yang ZF, Lau CK, Lam CT, Pang RWC, Poon RTP. Inhibition of mTOR enhances chemosensitivity in hepatocellular carcinoma. Cancer Lett 2008; 273:201-9. [PMID: 18824293 DOI: 10.1016/j.canlet.2008.08.018] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2008] [Revised: 03/25/2008] [Accepted: 08/04/2008] [Indexed: 10/21/2022]
Abstract
The present study investigated the effect of mammalian target of rapamycin (mTOR) inhibition on HCC cells in vitro and in vivo, either alone or in combination with cytotoxic agents. In vitro, HCC cell lines were exposed to RAD001, an mTOR inhibitor, either alone or in combination with cisplatin. Alone, RAD001 suppressed cell proliferation in all cell lines tested, but did not induce apoptosis. RAD001 in combination with cisplatin induced a significant increase in the number of apoptotic cells, downregulated the expression of pro-survival molecules, Bcl-2, survivin and cyclinD1, and increased the cleavage of PARP, compared to RAD001 or cisplatin alone. Transfection of p53 into the Hep3B cell line increased the sensitivity of tumor cells to cisplatin. The suppression of HCC tumor growth in vivo was enhanced by RAD001 combined with cisplatin, accompanied by a significant increase in the number of apoptotic cells in tumor tissues. This study demonstrates that inhibition of mTOR suppresses tumor growth and sensitizes tumor cells to chemocytotoxic agents.
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Affiliation(s)
- Ka Ho Tam
- Center for Cancer Research, Department of Surgery, The University of Hong Kong, Queen Mary Hospital, 102 Pokfulam Road, Pokfulam, Hong Kong, China
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Chan YW, On KF, Chan WM, Wong W, Siu HO, Hau PM, Poon RYC. The kinetics of p53 activation versus cyclin E accumulation underlies the relationship between the spindle-assembly checkpoint and the postmitotic checkpoint. J Biol Chem 2008; 283:15716-23. [PMID: 18400748 DOI: 10.1074/jbc.m800629200] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Although cells can exit mitotic block aberrantly by mitotic slippage, they are prevented from becoming tetraploids by a p53-dependent postmitotic checkpoint. Intriguingly, disruption of the spindle-assembly checkpoint also compromises the postmitotic checkpoint. The precise mechanism of the interplay between these two pivotal checkpoints is not known. We found that after prolonged nocodazole exposure, the postmitotic checkpoint was facilitated by p53. We demonstrated that although disruption of the mitotic block by a MAD2-binding protein promoted slippage, it did not influence the activation of p53. Both p53 and its downstream target p21(CIP1/WAF1) were activated at the same rate irrespective of whether the spindle-assembly checkpoint was enforced or not. The accelerated S phase entry, as reflected by the premature accumulation of cyclin E relative to the activation of p21(CIP1/WAF1), is the reason for the uncoupling of the postmitotic checkpoint. In support of this hypothesis, forced premature mitotic exit with a specific CDK1 inhibitor triggered DNA replication without affecting the kinetics of p53 activation. Finally, replication after checkpoint bypass was boosted by elevating the level of cyclin E. These observations indicate that disruption of the spindle-assembly checkpoint does not directly influence p53 activation, but the shortening of the mitotic arrest allows cyclin E-CDK2 to be activated before the accumulation of p21(CIP1/WAF1). These data underscore the critical relationship between the spindle-assembly checkpoint and the postmitotic checkpoint in safeguarding chromosomal stability.
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Affiliation(s)
- Ying Wai Chan
- Department of Biochemistry, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong
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12
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Lai PBS, Chi TY, Chen GG. Different levels of p53 induced either apoptosis or cell cycle arrest in a doxycycline-regulated hepatocellular carcinoma cell line in vitro. Apoptosis 2007; 12:387-93. [PMID: 17191126 DOI: 10.1007/s10495-006-0571-1] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Induction of p53 gene expression in cancer cells can lead to both cell cycle arrest and apoptosis. To clarify whether the level of p53 expression determines the apoptotic response of hepatocellular carcinoma (HCC) cells, we assessed the effect of various levels of expression of p53 gene on a p53-deficient HCC cell line, Hep3B, utilizing a doxycycline (Dox)-regulated inducible p53 expression system. Our results showed that apoptosis was induced in HCC cells with high levels of p53 expression. However, lower level of p53 expression induced only cell cycle arrest but not apoptosis. Bax expression was up-regulated following high levels of p53 expression, while bcl-2 expression was not altered by the level of p53 expression. Moreover, p21 expression was observed in both high and low expression of p53. These results suggest the level of p53 expression could determine if the HCC cells would go into cell cycle arrest or apoptosis. Bax may participate, at least in part, in inducing p53-dependent apoptosis and the induction of p21 alone was able to cause cell cycle arrest but not apoptosis.
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Affiliation(s)
- Paul B S Lai
- Department of Surgery, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong Kong SAR, China.
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Hau PM, Siu WY, Wong N, Lai PBS, Poon RYC. Polyploidization increases the sensitivity to DNA-damaging agents in mammalian cells. FEBS Lett 2006; 580:4727-36. [PMID: 16887121 DOI: 10.1016/j.febslet.2006.07.059] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2006] [Revised: 07/18/2006] [Accepted: 07/19/2006] [Indexed: 11/20/2022]
Abstract
Polyploidization occurs during normal development as well as during tumorigenesis. In this study, we investigated if the responses to genotoxic stress in cancer cells are influenced by the ploidy. Prolonged treatment of Hep3B cells with the spindle inhibitor nocodazole resulted in mitotic slippage, followed by re-replication of the DNA to produce polyploids. Reintroduction of p53 restored the checkpoints and suppressed polyploidization. Remarkably, a stable tetraploidy cell line could be generated from Hep3B by a transient nocodazole treatment followed by a period of recovery. Using this novel tetraploid system, we found that tetraploidization increased the cell volume without significantly affecting the cell cycle. Although tetraploidization was accompanied by an increase in centrosome number, the majority of mitoses in the tetraploid cells remained bipolar. Polyploidization sensitized cells to genotoxic stress inflicted by ionizing radiation and topoisomerase inhibitors without affecting the sensitivity to spindle inhibitors. Accordingly, more gamma-H2AX foci were induced by radiation in tetraploids than in normal Hep3B cells. Likewise, primary tetraploid human fibroblasts displayed higher gamma-H2AX foci formation than diploid human fibroblasts. An implication for chemotherapy is that some cancer cells can be sensitized to genotoxic agents by a preceding step that induces polyploidization.
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Affiliation(s)
- Pok Man Hau
- Department of Biochemistry, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong
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