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Cyran AM, Kleinegger F, Nass N, Naumann M, Haybaeck J, Arens C. Inhibition of EIF2α Dephosphorylation Decreases Cell Viability and Synergizes with Standard-of-Care Chemotherapeutics in Head and Neck Squamous Cell Carcinoma. Cancers (Basel) 2023; 15:5350. [PMID: 38001610 PMCID: PMC10670742 DOI: 10.3390/cancers15225350] [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: 10/05/2023] [Revised: 10/27/2023] [Accepted: 11/01/2023] [Indexed: 11/26/2023] Open
Abstract
Drug resistance is a common cause of therapy failure in head and neck squamous cell carcinoma (HNSCC). One approach to tackling it is by targeting fundamental cellular processes, such as translation. The eukaryotic translation initiation factor 2α (EIF2α) is a key player in canonical translation initiation and integrates diverse stress signals; when phosphorylated, it curbs global protein synthesis. This study evaluates EIF2α expression and phosphorylation in HNSCC. A small-molecule inhibitor of EIF2α dephosphorylation, salubrinal, was tested in vitro, followed by viability assays, flow cytometry, and immunoblot analyses. Patient-derived 3D tumor spheres (PD3DS) were cultured with salubrinal and their viability assessed. Lastly, salubrinal was evaluated with standard-of-care chemotherapeutics. Our analysis of RNA and proteomics data shows elevated EIF2α expression in HNSCC. Immunohistochemical staining reveals increasing EIF2α abundance from premalignant lesions to invasive and metastatic carcinoma. In immunoblots from intraoperative samples, EIF2α expression and steady-state phosphorylation are higher in HNSCC than in neighboring normal tissue. Inhibition of EIF2α dephosphorylation decreases HNSCC cell viability and clonogenic survival and impairs the G1/S transition. Salubrinal also decreases the viability of PD3DS and acts synergistically with cisplatin, 5-fluorouracil, bleomycin, and proteasome inhibitors. Our results indicate that pharmacological inhibition of EIF2α dephosphorylation is a potential therapeutic strategy for HNSCC.
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Affiliation(s)
- Anna M. Cyran
- Legorreta Cancer Center, Department of Pathology and Laboratory Medicine, Brown University, Providence, RI 02906, USA
- Department of Otorhinolaryngology, Head and Neck Surgery, Otto-von-Guericke University, 39120 Magdeburg, Germany
| | - Florian Kleinegger
- Diagnostic & Research Center for Molecular Biomedicine, Institute of Pathology, Medical University of Graz, 8010 Graz, Austria (J.H.)
| | - Norbert Nass
- Institute of Pathology, University Hospital Brandenburg, Brandenburg Medical School Theodor Fontane, 14770 Brandenburg an der Havel, Germany;
| | - Michael Naumann
- Institute of Experimental Internal Medicine, Otto von Guericke University, 39120 Magdeburg, Germany;
| | - Johannes Haybaeck
- Diagnostic & Research Center for Molecular Biomedicine, Institute of Pathology, Medical University of Graz, 8010 Graz, Austria (J.H.)
| | - Christoph Arens
- Department of Otorhinolaryngology, Head and Neck Surgery, Giessen and Marburg University Hospitals, Campus Giessen, 35392 Giessen, Germany;
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He Q, Zhang B, Hu F, Long J, Shi Q, Pi X, Chen H, Li J. Triptolide Inhibits the Proliferation of HaCaT Cells Induced by IL22 via Upregulating miR-181b-5p. Drug Des Devel Ther 2020; 14:2927-2935. [PMID: 32801634 PMCID: PMC7383028 DOI: 10.2147/dddt.s254466] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 06/29/2020] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND Evidence has been shown that triptolide was effective in the treatment of psoriasis; however, the mechanisms remain poorly understood. Thus, this study aimed to investigate the role of triptolide on the proliferation and differentiation of HaCaT cells which are treated with IL22 to mimic abnormal proliferation/differentiation in keratinocyte of psoriasis. MATERIALS AND METHODS HaCaT cells were transfected with miR-181b-5p antagomir for 24 h, and then exposed to 10 μM Triptolide for 24 h, following by 100 ng/mL of IL22 for 24 h. In addition, the proliferation and cell cycle distribution in HaCaT cells were assessed by immunofluorescence or flow cytometry assays, respectively. RESULTS Triptolide obviously upregulated the level of miR-181b-5p in HaCaT cells. In addition, triptolide significantly inhibited IL22-induced proliferation of HaCaT cells via inducing cell cycle arrest. Moreover, IL22 markedly inhibited the differentiation of HaCaT cells, and this phenomenon was reversed by triptolide treatment. In contrast, the effects of triptolide on the proliferation and differentiation in IL22-stimulated HaCaT cells were notably reversed by miR-181b-5p antagomir. Moreover, dual-luciferase assay showed that E2F5 was the direct target of miR-181b-5p in HaCaT cells. Meanwhile, upregulation of miR-181b-5p obviously decreased the level of E2F5 in HaCaT cells. CONCLUSION In this study, we found that triptolide could inhibit the proliferation and promote the differentiation in IL22-stimulated keratinocytes via upregulating miR-181b-5p. These data indicated that triptolide may be a potential agent for the treatment of psoriasis.
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Affiliation(s)
- Qi He
- Department of Dermatology, Hubei Provincial Hospital of Traditional Chinese Medicine, Wuhan, Hubei430061, People’s Republic of China
- Department of Dermatology, Hubei Province Academy of Traditional Chinese Medicine, Wuhan, Hubei430074, People’s Republic of China
| | - Bo Zhang
- Department of Dermatology, Hubei Provincial Hospital of Traditional Chinese Medicine, Wuhan, Hubei430061, People’s Republic of China
- Department of Dermatology, Hubei Province Academy of Traditional Chinese Medicine, Wuhan, Hubei430074, People’s Republic of China
| | - Feng Hu
- Department of Dermatology, Wuhan No.1 Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei430022, People’s Republic of China
| | - Jianwen Long
- Department of Dermatology, Hubei Provincial Hospital of Traditional Chinese Medicine, Wuhan, Hubei430061, People’s Republic of China
- Department of Dermatology, Hubei Province Academy of Traditional Chinese Medicine, Wuhan, Hubei430074, People’s Republic of China
| | - Quan Shi
- Department of Dermatology, Hubei Provincial Hospital of Traditional Chinese Medicine, Wuhan, Hubei430061, People’s Republic of China
- Department of Dermatology, Hubei Province Academy of Traditional Chinese Medicine, Wuhan, Hubei430074, People’s Republic of China
| | - Xianming Pi
- Department of Dermatology, Hubei Provincial Hospital of Traditional Chinese Medicine, Wuhan, Hubei430061, People’s Republic of China
- Department of Dermatology, Hubei Province Academy of Traditional Chinese Medicine, Wuhan, Hubei430074, People’s Republic of China
| | - Hongxiang Chen
- Department of Dermatology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei430022, People’s Republic of China
| | - Jiawen Li
- Department of Dermatology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei430022, People’s Republic of China
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PTPN14 degradation by high-risk human papillomavirus E7 limits keratinocyte differentiation and contributes to HPV-mediated oncogenesis. Proc Natl Acad Sci U S A 2019; 116:7033-7042. [PMID: 30894485 DOI: 10.1073/pnas.1819534116] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
High-risk human papillomavirus (HPV) E7 proteins enable oncogenic transformation of HPV-infected cells by inactivating host cellular proteins. High-risk but not low-risk HPV E7 target PTPN14 for proteolytic degradation, suggesting that PTPN14 degradation may be related to their oncogenic activity. HPV infects human keratinocytes but the role of PTPN14 in keratinocytes and the consequences of PTPN14 degradation are unknown. Using an HPV16 E7 variant that can inactivate retinoblastoma tumor suppressor (RB1) but cannot degrade PTPN14, we found that high-risk HPV E7-mediated PTPN14 degradation impairs keratinocyte differentiation. Deletion of PTPN14 from primary human keratinocytes decreased keratinocyte differentiation gene expression. Related to oncogenic transformation, both HPV16 E7-mediated PTPN14 degradation and PTPN14 deletion promoted keratinocyte survival following detachment from a substrate. PTPN14 degradation contributed to high-risk HPV E6/E7-mediated immortalization of primary keratinocytes and HPV+ but not HPV- cancers exhibit a gene-expression signature consistent with PTPN14 inactivation. We find that PTPN14 degradation impairs keratinocyte differentiation and propose that this contributes to high-risk HPV E7-mediated oncogenic activity independent of RB1 inactivation.
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Kouwenhoven EN, Oti M, Niehues H, van Heeringen SJ, Schalkwijk J, Stunnenberg HG, van Bokhoven H, Zhou H. Transcription factor p63 bookmarks and regulates dynamic enhancers during epidermal differentiation. EMBO Rep 2015; 16:863-78. [PMID: 26034101 PMCID: PMC4515125 DOI: 10.15252/embr.201439941] [Citation(s) in RCA: 110] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 04/20/2015] [Indexed: 12/19/2022] Open
Abstract
The transcription factor p63 plays a pivotal role in keratinocyte proliferation and differentiation in the epidermis. However, how p63 regulates epidermal genes during differentiation is not yet clear. Using epigenome profiling of differentiating human primary epidermal keratinocytes, we characterized a catalog of dynamically regulated genes and p63-bound regulatory elements that are relevant for epithelial development and related diseases. p63-bound regulatory elements occur as single or clustered enhancers, and remarkably, only a subset is active as defined by the co-presence of the active enhancer mark histone modification H3K27ac in epidermal keratinocytes. We show that the dynamics of gene expression correlates with the activity of p63-bound enhancers rather than with p63 binding itself. The activity of p63-bound enhancers is likely determined by other transcription factors that cooperate with p63. Our data show that inactive p63-bound enhancers in epidermal keratinocytes may be active during the development of other epithelial-related structures such as limbs and suggest that p63 bookmarks genomic loci during the commitment of the epithelial lineage and regulates genes through temporal- and spatial-specific active enhancers.
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Affiliation(s)
- Evelyn N Kouwenhoven
- Department of Human Genetics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands Department of Molecular Developmental Biology, Faculty of Science, Radboud Institute for Molecular Life Sciences Radboud University, Nijmegen, The Netherlands
| | - Martin Oti
- Department of Molecular Developmental Biology, Faculty of Science, Radboud Institute for Molecular Life Sciences Radboud University, Nijmegen, The Netherlands
| | - Hanna Niehues
- Department of Dermatology, Radboud Institute for Molecular Life Sciences Radboud University Medical Center, Nijmegen, The Netherlands
| | - Simon J van Heeringen
- Department of Molecular Developmental Biology, Faculty of Science, Radboud Institute for Molecular Life Sciences Radboud University, Nijmegen, The Netherlands
| | - Joost Schalkwijk
- Department of Dermatology, Radboud Institute for Molecular Life Sciences Radboud University Medical Center, Nijmegen, The Netherlands
| | - Hendrik G Stunnenberg
- Department of Molecular Biology, Faculty of Science, Radboud Institute for Molecular Life Sciences Radboud University, Nijmegen, The Netherlands
| | - Hans van Bokhoven
- Department of Human Genetics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Huiqing Zhou
- Department of Human Genetics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands Department of Molecular Developmental Biology, Faculty of Science, Radboud Institute for Molecular Life Sciences Radboud University, Nijmegen, The Netherlands
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Hazar-Rethinam M, de Long LM, Gannon OM, Boros S, Vargas AC, Dzienis M, Mukhopadhyay P, Saenz-Ponce N, Dantzic DDE, Simpson F, Saunders NA. RacGAP1 Is a Novel Downstream Effector of E2F7-Dependent Resistance to Doxorubicin and Is Prognostic for Overall Survival in Squamous Cell Carcinoma. Mol Cancer Ther 2015; 14:1939-50. [PMID: 26018753 DOI: 10.1158/1535-7163.mct-15-0076] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 05/15/2015] [Indexed: 11/16/2022]
Abstract
We have previously shown that E2F7 contributes to drug resistance in head and neck squamous cell carcinoma (HNSCC) cells. Considering that dysregulation of responses to chemotherapy-induced cytotoxicity is one of the major reasons for treatment failure in HNSCC, identifying the downstream effectors that regulate E2F7-dependent sensitivity to chemotherapeutic agents may have direct clinical impact. We used transcriptomic profiling to identify candidate pathways that contribute to E2F7-dependent resistance to doxorubicin. We then manipulated the expression of the candidate pathway using overexpression and knockdown in in vitro and in vivo models of SCC to demonstrate causality. In addition, we examined the expression of E2F7 and RacGAP1 in a custom tissue microarray (TMA) generated from HNSCC patient samples. Transcriptomic profiling identified RacGAP1 as a potential mediator of E2F7-dependent drug resistance. We validated E2F7-dependent upregulation of RacGAP1 in doxorubicin-insensitive SCC25 cells. Extending this, we found that selective upregulation of RacGAP1 induced doxorubicin resistance in previously sensitive KJDSV40. Similarly, stable knockdown of RacGAP1 in insensitive SCC25 cells induced sensitivity to doxorubicin in vitro and in vivo. RacGAP1 expression was validated in a TMA, and we showed that HNSCCs that overexpress RacGAP1 are associated with a poorer patient overall survival. Furthermore, E2F7-induced doxorubicin resistance was mediated via RacGAP1-dependent activation of AKT. Finally, we show that SCC cells deficient in RacGAP1 grow slower and are sensitized to the cytotoxic actions of doxorubicin in vivo. These findings identify RacGAP1 overexpression as a novel prognostic marker of survival and a potential target to sensitize SCC to doxorubicin.
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Affiliation(s)
- Mehlika Hazar-Rethinam
- Epithelial Pathobiology Group, University of Queensland Diamantina Institute, Princess Alexandra Hospital, Translational Research Institute, Woolloongabba, Queensland, Australia
| | - Lilia Merida de Long
- Epithelial Pathobiology Group, University of Queensland Diamantina Institute, Princess Alexandra Hospital, Translational Research Institute, Woolloongabba, Queensland, Australia
| | - Orla M Gannon
- Epithelial Pathobiology Group, University of Queensland Diamantina Institute, Princess Alexandra Hospital, Translational Research Institute, Woolloongabba, Queensland, Australia
| | - Samuel Boros
- Department of Pathology, Princess Alexandra Hospital, Woolloongabba, Queensland, Australia
| | - Ana Cristina Vargas
- Department of Pathology, Princess Alexandra Hospital, Woolloongabba, Queensland, Australia
| | - Marcin Dzienis
- Department of Medical Oncology, Princess Alexandra Hospital, Woolloongabba, Queensland, Australia
| | - Pamela Mukhopadhyay
- Epithelial Pathobiology Group, University of Queensland Diamantina Institute, Princess Alexandra Hospital, Translational Research Institute, Woolloongabba, Queensland, Australia
| | - Natalia Saenz-Ponce
- Epithelial Pathobiology Group, University of Queensland Diamantina Institute, Princess Alexandra Hospital, Translational Research Institute, Woolloongabba, Queensland, Australia
| | - Daniel D E Dantzic
- Epithelial Pathobiology Group, University of Queensland Diamantina Institute, Princess Alexandra Hospital, Translational Research Institute, Woolloongabba, Queensland, Australia
| | - Fiona Simpson
- Epithelial Pathobiology Group, University of Queensland Diamantina Institute, Princess Alexandra Hospital, Translational Research Institute, Woolloongabba, Queensland, Australia
| | - Nicholas A Saunders
- Epithelial Pathobiology Group, University of Queensland Diamantina Institute, Princess Alexandra Hospital, Translational Research Institute, Woolloongabba, Queensland, Australia.
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Hazar-Rethinam M, de Long LM, Gannon OM, Topkas E, Boros S, Vargas AC, Dzienis M, Mukhopadhyay P, Simpson F, Endo-Munoz L, Saunders NA. A novel E2F/sphingosine kinase 1 axis regulates anthracycline response in squamous cell carcinoma. Clin Cancer Res 2014; 21:417-27. [PMID: 25411162 DOI: 10.1158/1078-0432.ccr-14-1962] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE Head and neck squamous cell carcinomas (HNSCC) are frequently drug resistant and have a mortality rate of 45%. We have previously shown that E2F7 may contribute to drug resistance in SCC cells. However, the mechanism and pathways involved remain unknown. EXPERIMENTAL DESIGN We used transcriptomic profiling to identify candidate pathways that may contribute to E2F7-dependent resistance to anthracyclines. We then manipulated the activity/expression of the candidate pathway using overexpression, knockdown, and pharmacological inhibitors in in vitro and in vivo models of SCC to demonstrate causality. In addition, we examined the expression of E2F7 and a downstream effector in a tissue microarray (TMA) generated from HNSCC patient samples. RESULTS E2F7-deficient keratinocytes were selectively sensitive to doxorubicin and this was reversed by overexpressing E2F7. Transcriptomic profiling identified Sphingosine kinase 1 (Sphk1) as a potential mediator of E2F7-dependent drug resistance. Knockdown and overexpression studies revealed that Sphk1 was a downstream target of E2F7. TMA studies showed that E2F7 overexpression correlated with Sphk1 overexpression in human HNSCC. Moreover, inhibition of Sphk1 by shRNA or the Sphk1-specific inhibitor, SK1-I (BML-EI411), enhanced the sensitivity of SCC cells to doxorubicin in vitro and in vivo. Furthermore, E2F7-induced doxorubicin resistance was mediated via Sphk1-dependent activation of AKT in vitro and in vivo. CONCLUSION We identify a novel drugable pathway in which E2F7 directly increases the transcription and activity of the Sphk1/S1P axis resulting in activation of AKT and subsequent drug resistance. Collectively, this novel combinatorial therapy can potentially be trialed in humans using existing agents.
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Affiliation(s)
- Mehlika Hazar-Rethinam
- Epithelial Pathobiology Group, University of Queensland Diamantina Institute, Princess Alexandra Hospital, Translational Research Institute, Woolloongabba, Queensland, Australia
| | - Lilia Merida de Long
- Epithelial Pathobiology Group, University of Queensland Diamantina Institute, Princess Alexandra Hospital, Translational Research Institute, Woolloongabba, Queensland, Australia
| | - Orla M Gannon
- Epithelial Pathobiology Group, University of Queensland Diamantina Institute, Princess Alexandra Hospital, Translational Research Institute, Woolloongabba, Queensland, Australia
| | - Eleni Topkas
- Epithelial Pathobiology Group, University of Queensland Diamantina Institute, Princess Alexandra Hospital, Translational Research Institute, Woolloongabba, Queensland, Australia
| | - Samuel Boros
- Department of Pathology, Princess Alexandra Hospital, Woolloongabba, Queensland, Australia
| | - Ana Cristina Vargas
- Department of Pathology, Princess Alexandra Hospital, Woolloongabba, Queensland, Australia
| | - Marcin Dzienis
- Department of Medical Oncology, Princess Alexandra Hospital, Woolloongabba, Queensland, Australia
| | - Pamela Mukhopadhyay
- Epithelial Pathobiology Group, University of Queensland Diamantina Institute, Princess Alexandra Hospital, Translational Research Institute, Woolloongabba, Queensland, Australia
| | - Fiona Simpson
- Epithelial Pathobiology Group, University of Queensland Diamantina Institute, Princess Alexandra Hospital, Translational Research Institute, Woolloongabba, Queensland, Australia
| | - Liliana Endo-Munoz
- Epithelial Pathobiology Group, University of Queensland Diamantina Institute, Princess Alexandra Hospital, Translational Research Institute, Woolloongabba, Queensland, Australia
| | - Nicholas A Saunders
- Epithelial Pathobiology Group, University of Queensland Diamantina Institute, Princess Alexandra Hospital, Translational Research Institute, Woolloongabba, Queensland, Australia.
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Bart G, Hämäläinen L, Rauhala L, Salonen P, Kokkonen M, Dunlop T, Pehkonen P, Kumlin T, Tammi M, Pasonen-Seppänen S, Tammi R. rClca2is associated with epidermal differentiation and is strongly downregulated by ultraviolet radiation. Br J Dermatol 2014; 171:376-87. [DOI: 10.1111/bjd.13038] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/02/2014] [Indexed: 12/18/2022]
Affiliation(s)
- G. Bart
- Institute of Biomedicine; University of Eastern Finland; P.O. Box 1627 FI-70211 Kuopio Finland
| | - L. Hämäläinen
- Institute of Biomedicine; University of Eastern Finland; P.O. Box 1627 FI-70211 Kuopio Finland
| | - L. Rauhala
- Institute of Biomedicine; University of Eastern Finland; P.O. Box 1627 FI-70211 Kuopio Finland
| | - P. Salonen
- Institute of Biomedicine; University of Eastern Finland; P.O. Box 1627 FI-70211 Kuopio Finland
| | - M. Kokkonen
- Institute of Biomedicine; University of Eastern Finland; P.O. Box 1627 FI-70211 Kuopio Finland
| | - T.W. Dunlop
- Institute of Biomedicine; University of Eastern Finland; P.O. Box 1627 FI-70211 Kuopio Finland
| | - P. Pehkonen
- Institute of Biomedicine; University of Eastern Finland; P.O. Box 1627 FI-70211 Kuopio Finland
| | - T. Kumlin
- Department of Environmental Science; University of Eastern Finland; P.O. Box 1627 FI-70211 Kuopio Finland
| | - M.I. Tammi
- Institute of Biomedicine; University of Eastern Finland; P.O. Box 1627 FI-70211 Kuopio Finland
| | - S. Pasonen-Seppänen
- Institute of Biomedicine; University of Eastern Finland; P.O. Box 1627 FI-70211 Kuopio Finland
| | - R.H. Tammi
- Institute of Biomedicine; University of Eastern Finland; P.O. Box 1627 FI-70211 Kuopio Finland
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Li T, Yang J, Lv X, Liu K, Gao C, Xing Y, Xi T. miR-155 regulates the proliferation and cell cycle of colorectal carcinoma cells by targeting E2F2. Biotechnol Lett 2014; 36:1743-52. [PMID: 24793496 DOI: 10.1007/s10529-014-1540-3] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Accepted: 04/17/2014] [Indexed: 11/30/2022]
Abstract
MicroRNAs play important roles in carcinogenesis by negatively regulating the expression of target genes. Here we explore the biological function of miR-155 and the underlying mechanism in colorectal carcinoma. We validate, for the first time, that E2F2 is a direct target of miR-155 using western blot and a luciferase reporter assay and that miR-155 regulates the proliferation and cell cycle of colorectal carcinoma cells by targeting E2F2 using siRNA technology. We also found, for the first, time that E2F2 acts as a tumor suppressor in colorectal carcinoma. Overall, miR-155 plays an important role in colorectal carcinoma tumorigenesis by negative regulation of its targets including E2F2 and may be a potential therapeutic target for colorectal carcinoma treatment.
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Affiliation(s)
- Tong Li
- School of Life Science and Technology, China Pharmaceutical University, Nanjing, 210009, People's Republic of China,
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Gannon OM, Merida de Long L, Endo-Munoz L, Hazar-Rethinam M, Saunders NA. Dysregulation of the repressive H3K27 trimethylation mark in head and neck squamous cell carcinoma contributes to dysregulated squamous differentiation. Clin Cancer Res 2012. [PMID: 23186778 DOI: 10.1158/1078-0432.ccr-12-2505] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
PURPOSE Head and neck squamous cell carcinoma (HNSCC) is one of the most prevalent cancers diagnosed worldwide and is associated with a 5-year survival rate of 55%. EZH2, a component of the polycomb repressor complex 2, trimethylates H3K27 (H3K27me3), which has been shown to drive squamous differentiation in normal keratinocytes. This study determined whether inhibition of EZH2-mediated epigenetic silencing could induce differentiation or provide therapeutic benefit in HNSCC. EXPERIMENTAL DESIGN We determined the effects of inhibiting EZH2, by either RNA interference or pharmacologically, on HNSCC growth, viability, and differentiation in vitro. Xenografts of HNSCC cell lines were used to assess efficacy of 3-deazaneplanocin A (DZNep), an inhibitor of H3K27 trimethylation, in vivo. RESULTS EZH2 was highly expressed in HNSCC cell lines in vitro and tissue microarray analysis revealed high expression in (n = 59) in situ relative to normal oral epithelium (n = 12). Inhibition of EZH2 with siRNA could induce expression of differentiation genes in differentiation-refractory squamous cell carcinoma cell lines. Differentiation-refractory HNSCC cell lines displayed persistent H3K27me3 on the promoters of differentiation genes. DZNep caused cancer-cell-specific apoptosis in addition to a profound reduction in colony-forming efficiency and induction of some squamous differentiation genes. Furthermore, in vivo, DZNep attenuated tumor growth in two different xenograft models, caused intratumor inhibition of EZH2, and induction of differentiation genes in situ. CONCLUSIONS Collectively, these data suggest that aberrant differentiation in HNSCC may be attributed to epigenetic dysregulation and suggest that inhibition of PRC2-mediated gene repression may represent a potential therapeutic target.
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Affiliation(s)
- Orla M Gannon
- University of Queensland Diamantina Institute, Princess Alexandra Hospital, Ipswich Road, Woolloongabba, Queensland, Australia
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KIM SEONGGON, KIM ANSOOK, JEONG JAEHWAN, CHOI JEYONG, KWEON HAEYONG. 4-hexylresorcinol stimulates the differentiation of SCC-9 cells through the suppression of E2F2, E2F3 and Sp3 expression and the promotion of Sp1 expression. Oncol Rep 2012; 28:677-81. [DOI: 10.3892/or.2012.1845] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2012] [Accepted: 05/14/2012] [Indexed: 11/06/2022] Open
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Hazar-Rethinam M, Endo-Munoz L, Gannon O, Saunders N. The role of the E2F transcription factor family in UV-induced apoptosis. Int J Mol Sci 2011; 12:8947-60. [PMID: 22272113 PMCID: PMC3257110 DOI: 10.3390/ijms12128947] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Revised: 11/15/2011] [Accepted: 11/30/2011] [Indexed: 11/16/2022] Open
Abstract
The E2F transcription factor family is traditionally associated with cell cycle control. However, recent data has shown that activating E2Fs (E2F1-3a) are potent activators of apoptosis. In contrast, the recently cloned inhibitory E2Fs (E2F7 and 8) appear to antagonize E2F-induced cell death. In this review we will discuss (i) the potential role of E2Fs in UV-induced cell death and (ii) the implications of this to the development of UV-induced cutaneous malignancies.
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Affiliation(s)
- Mehlika Hazar-Rethinam
- Epithelial Pathobiology Group, University of Queensland Diamantina Institute, Princess Alexandra Hospital, Queensland 4102, Australia; E-Mails: (M.H.-R.); (L.E.-M.); (O.G.)
| | - Liliana Endo-Munoz
- Epithelial Pathobiology Group, University of Queensland Diamantina Institute, Princess Alexandra Hospital, Queensland 4102, Australia; E-Mails: (M.H.-R.); (L.E.-M.); (O.G.)
| | - Orla Gannon
- Epithelial Pathobiology Group, University of Queensland Diamantina Institute, Princess Alexandra Hospital, Queensland 4102, Australia; E-Mails: (M.H.-R.); (L.E.-M.); (O.G.)
| | - Nicholas Saunders
- Epithelial Pathobiology Group, University of Queensland Diamantina Institute, Princess Alexandra Hospital, Queensland 4102, Australia; E-Mails: (M.H.-R.); (L.E.-M.); (O.G.)
- School of Biomedical Sciences, University of Queensland, Queensland 4072, Australia
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +61-7-3176-5894; Fax: +61-7-3176-5946
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12
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Loss of E2F7 expression is an early event in squamous differentiation and causes derepression of the key differentiation activator Sp1. J Invest Dermatol 2011; 131:1077-84. [PMID: 21248772 DOI: 10.1038/jid.2010.430] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Squamous differentiation is controlled by key transcription factors such as Sp1 and E2F. We have previously shown that E2F1 can suppress transcription of the differentiation-specific gene, transglutaminase type 1 (TG1), by an indirect mechanism mediated by Sp1. Transient transfection of E2F1-E2F6 indicated that E2F-mediated reduction of Sp1 transcription was not responsible for E2F-mediated suppression of squamous differentiation. However, we found that E2F4 and E2F7, but not E2Fs 1, 2, 3, 5, or 6, could suppress the activation of the Sp1 promoter in differentiated keratinocytes (KCs). E2F4-mediated suppression could not be antagonized by E2Fs 1, 2, 3, 5, or 6 and was localized to a region of the human Sp1 promoter spanning -139 to + 35 bp. Chromatin immunoprecipitation analysis, as well as transient overexpression and short hairpin RNA knockdown experiments indicate that E2F7 binds to a unique binding site located between -139 and -119 bp of the Sp1 promoter, and knockdown of E2F7 in proliferating KCs leads to a derepression of Sp1 expression and the induction of TG1. In contrast, E2F4 knockdown in proliferating KCs did not alter Sp1 expression. These data indicate that loss of E2F7 during the initiation of differentiation leads to the derepression of Sp1 and subsequent transcription of differentiation-specific genes such as TG1.
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Endo-Munoz L, Dahler A, Teakle N, Rickwood D, Hazar-Rethinam M, Abdul-Jabbar I, Sommerville S, Dickinson I, Kaur P, Paquet-Fifield S, Saunders N. E2F7 can regulate proliferation, differentiation, and apoptotic responses in human keratinocytes: implications for cutaneous squamous cell carcinoma formation. Cancer Res 2009; 69:1800-8. [PMID: 19223542 DOI: 10.1158/0008-5472.can-08-2725] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The E2F family of transcription factors plays a crucial role in the regulation of genes involved in cell proliferation, differentiation, and apoptosis. In keratinocytes, the inhibition of E2F is a key step in the control and initiation of squamous differentiation. Because the product of the recently identified E2F7a/E2F7b gene has been shown to repress E2F-regulated promoters, and to be abundant in skin, we examined its role in the epidermis. Our results indicate that E2F7b mRNA expression is selectively associated with proliferation-competent keratinocytes. Moreover, E2F7 was able to antagonize E2F1-induced proliferation and apoptosis. In contrast, although E2F7 was able to inhibit proliferation and initiate differentiation, it was unable to antagonize the differentiation suppression induced by E2F1. These data indicate that E2F7-mediated suppression of proliferation and apoptosis acts through E2F1-dependent pathways, whereas E2F7-induced differentiation acts through an E2F1-independent pathway. These data also suggest that proliferation, differentiation, and survival of primary human keratinocytes can be controlled by the relative ratio of E2F1 to E2F7. Because deregulated proliferation, differentiation, and apoptosis are hallmarks of cancer, we examined the expression levels of E2F1 and E2F7 in cutaneous squamous cell carcinomas (CSCC). We found that both genes were overexpressed in CSCCs compared with normal epidermis. Furthermore, inhibition of E2F7 in a SCC cell line sensitized the cells to UV-induced apoptosis and doxorubicin-induced apoptosis. Combined, these data suggest that the selected disruption of E2F1 and E2F7 in keratinocytes is likely to contribute to CSCC formation and may prove to be a viable therapeutic target.
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Affiliation(s)
- Liliana Endo-Munoz
- Translational Research Unit, Cancer Collaborative Group, Princess Alexandra Hospital, Wooloongabba, Queensland 4102, Australia
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14
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Dahler AL, Rickwood D, Guminski A, Teakle N, Saunders NA. Indole-3-carbinol - induced growth inhibition can be converted to a cytotoxic response in the presence of TPA+Ca(2+) in squamous cell carcinoma cell lines. FEBS Lett 2007; 581:3839-47. [PMID: 17659285 DOI: 10.1016/j.febslet.2007.07.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2007] [Revised: 07/04/2007] [Accepted: 07/05/2007] [Indexed: 10/23/2022]
Abstract
We examined the possibility that I3C, when combined with a differentiation stimulus (TPA+CaCl(2)), would sensitise SCC cells to a differentiation stimulus. We report that I3C induces a profound growth inhibition in SCC cells that is dissimilar to the growth inhibition required to initiate differentiation. Moreover, we report that I3C, when combined with TPA+CaCl(2) treatment, induces a loss of colony forming ability that was differentiation and senescence - independent but was due to delayed cytotoxicity. This study shows that I3C in combination with a PKC activator+Ca(2+) may be a useful therapeutic strategy for treating oral SCC.
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Affiliation(s)
- A L Dahler
- Epithelial Pathobiology Group, Cancer Biology Programme, Diamantina Institute for Cancer, Immunology and Metabolic Medicine, University of Queensland, Princess Alexandra Hospital, Queensland, Australia
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15
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Walshe J, Serewko-Auret MM, Teakle N, Cameron S, Minto K, Smith L, Burcham PC, Russell T, Strutton G, Griffin A, Chu FF, Esworthy S, Reeve V, Saunders NA. Inactivation of glutathione peroxidase activity contributes to UV-induced squamous cell carcinoma formation. Cancer Res 2007; 67:4751-8. [PMID: 17510403 DOI: 10.1158/0008-5472.can-06-4192] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Cutaneous squamous cell carcinomas (CSCC) are a common malignancy of keratinocytes that arise in sites of the skin exposed to excessive UV radiation. In the present study, we show that human SCC cell lines, preneoplastic solar keratoses (SK), and CSCC are associated with perturbations in glutathione peroxidase (GPX) activity and peroxide levels. Specifically, we found that two of three SKs and four of five CSCCs, in vivo, were associated with decreased GPX activity and all SKs and CSCCs were associated with an elevated peroxide burden. Given the association of decreased GPX activity with CSCC, we examined the basis for the GPX deficiency in the CSCCs. Our data indicated that GPX was inactivated by a post-translational mechanism and that GPX could be inactivated by increases in intracellular peroxide levels. We next tested whether the decreased peroxidase activity coupled with an elevated peroxidative burden might contribute to CSCC formation in vivo. This was tested in Gpx1(-/-) and Gpx2(-/-) mice exposed to solar-simulated UV radiation. These studies showed that Gpx2 deficiency predisposed mice to UV-induced CSCC formation. These results suggest that inactivation of GPX2 in human skin may be an early event in UV-induced SCC formation.
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Affiliation(s)
- Jennifer Walshe
- Epithelial Pathobiology Group, Cancer Biology Programme, Diamantina Institute for Cancer, Immunology and Metabolic Medicine, University of Queensland, Queensland, Australia
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16
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Zhang Z, Li M, Rayburn ER, Hill DL, Zhang R, Wang H. Oncogenes as novel targets for cancer therapy (part III): transcription factors. ACTA ACUST UNITED AC 2005; 5:327-38. [PMID: 16196502 DOI: 10.2165/00129785-200505050-00005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
This is the third paper in a four-part serial review on potential therapeutic targeting of oncogenes. The previous parts described the involvement of oncogenes in different aspects of cancer growth and development, and considered the new technologies responsible for the advancement of oncogene identification, target validation, and drug design. Because of such advances, new specific and more efficient therapeutic agents can be developed for cancer. This part of the review continues the exploration of various oncogenes that we have grouped within seven categories: growth factors, tyrosine kinases, intermediate signaling molecules, transcription factors, cell cycle regulators, DNA damage repair genes, and genes involved in apoptosis. Part one discussed growth factors and tyrosine kinases and part two discussed intermediate signaling molecules. This portion of the review covers transcription factors and the various strategies being used to inhibit their expression or decrease their activities.
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Affiliation(s)
- Zhuo Zhang
- Department of Pharmacology and Toxicology and Division of Clinical Pharmacology, University of Alabama at Birmingham, Birmingham, Alabama 35294-0019, USA
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17
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Abstract
The E2 factor (E2F) family of transcription factors are downstream targets of the retinoblastoma protein. E2F factors have been known for several years to be important regulators of S-phase entry. Recent studies have improved our understanding of the molecular mechanisms of action used by this transcriptional network. In addition, they have given us an appreciation of the fact that E2F has functions that reach beyond G1/S control and impact cell proliferation in several different ways. The discovery of new family members with unusual properties, the unexpected phenotypes of mutant animals, a diverse collection of biological activities, a large number of new putative target genes and the new modes of transcriptional regulation have all contributed to an increasingly complex view of E2F function. In this review, we will discuss these recent developments and describe how they are beginning to shape a new and revised picture of the E2F transcriptional program.
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Ivanova IA, D'Souza SJA, Dagnino L. Signalling in the epidermis: the E2F cell cycle regulatory pathway in epidermal morphogenesis, regeneration and transformation. Int J Biol Sci 2005; 1:87-95. [PMID: 15951853 PMCID: PMC1142216 DOI: 10.7150/ijbs.1.87] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2004] [Accepted: 02/01/2005] [Indexed: 02/06/2023] Open
Abstract
The epidermis is the outermost layer in the skin, and it is the first line of defence against the environment. The epidermis also provides a barrier against loss of fluids and electrolytes, which is crucial for life. Essential in the maintenance of this tissue is its ability to continually self-renew and regenerate after injury. These two characteristics are critically dependent on the ability of the principal epidermal cell type, the keratinocyte, to proliferate and to respond to differentiation cues. Indeed, the epidermis is a multilayered tissue composed of keratinocyte stem cells and their differentiated progeny. Central for the control of cell proliferation is the E2F transcription factor regulatory network. This signaling network also includes cyclins, cdk, cdk inhibitors and the retinoblastoma (pRb) family of proteins. The biological importance of the E2F/pRb pathway is emphasized by the fact that a majority of human tumours exhibit alterations that disrupt the ability of pRb proteins to inhibit E2F, leading to permanent activation of the latter. Further, E2F is essential for normal epidermal regeneration after injury. Other member of the E2F signaling pathway are also involved in epidermal development and pathophysiology. Thus, whereas the pRb family of proteins is essential for epidermal morphogenesis, abnormal regulation of cyclins and E2F proteins results in tumorgenesis in this tissue. In this review, we discuss the role of each member of this important growth regulatory network in epidermal formation, homeostasis and carcinogenesis.
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Affiliation(s)
- Iordanka A Ivanova
- Dept. of Physiology & Pharmacology, University of Western Ontario, London, ON, Canada
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19
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Wong CF, Barnes LM, Dahler AL, Smith L, Popa C, Serewko-Auret MM, Saunders NA. E2F suppression and Sp1 overexpression are sufficient to induce the differentiation-specific marker, transglutaminase type 1, in a squamous cell carcinoma cell line. Oncogene 2005; 24:3525-34. [PMID: 15735752 DOI: 10.1038/sj.onc.1208372] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Recently, E2F function has expanded to include the regulation of differentiation in human epidermal keratinocytes (HEKs). We extend these findings to report that in HEKs, Sp1 is a differentiation-specific activator and a downstream target of E2F-mediated suppression of the differentiation-specific marker, transglutaminase type 1 (TG-1). Deletion of elements between -0.084 to -0.034 kb of the TG-1 promoter disabled E2F1-induced suppression of promoter activity. Electrophoretic mobility shift assays (EMSAs) demonstrated that Sp1 and Sp3 bound this region. Protein expression analysis suggested that squamous differentiation was accompanied by increased Sp1/Sp3 ratio. Cotransfection of proliferating HEKs or the squamous cell carcinoma (SCC) cell line, KJD-1/SV40, with an E2F inhibitor (E2Fd/n) and Sp1 expression plasmid was sufficient to activate the TG-1 promoter. The suppression of Sp1 activity by E2F in differentiated cells appeared to be indirect since we found no evidence of an Sp1/E2F coassociation on the TG-1 promoter fragment. Moreover, E2F inhibition in the presence of a differentiation stimulus induced Sp1 protein. These data demonstrate that (i) Sp1 can act as a differentiation stimulus, (ii) E2F-mediated suppression of differentiation-specific markers is indirect via Sp1 inhibition and (iii) a combination of E2F inhibition and Sp1 activation could form the basis of a differentiation therapy for SCCs.
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Affiliation(s)
- Chung Fai Wong
- Epithelial Pathobiology Group, Cancer Biology Programme, Centre for Immunology and Cancer Research, University of Queensland, Princess Alexandra Hospital, Woolloongabba, Queensland 4102, Australia
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Wong CF, Barnes LM, Smith L, Popa C, Serewko-Auret MM, Saunders NA. E2F6: a member of the E2F family that does not modulate squamous differentiation. Biochem Biophys Res Commun 2004; 324:497-503. [PMID: 15474455 DOI: 10.1016/j.bbrc.2004.09.084] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2004] [Indexed: 11/17/2022]
Abstract
The inhibition of E2F has been demonstrated to be important in the initiation of squamous differentiation by two independent manners: promotion of growth arrest and the relief of the differentiation-suppressive properties of E2Fs. E2F6 is reported to behave as a transcriptional repressor of the E2F family. In this study, we examined the ability of E2F6 to act as the molecular switch required for E2F inhibition in order for keratinocytes to enter a terminal differentiation programme. Results demonstrated that whilst E2F6 was able to suppress E2F activity in proliferating keratinocytes, it did not modulate squamous differentiation in a differentiated keratinocyte. Furthermore, inhibition of E2F, by overexpressing E2F6, was not sufficient to sensitise either proliferating keratinocytes or the squamous cell carcinoma cell line, KJD-1/SV40, to differentiation-inducing agents. Significantly, although E2F6 could suppress E2F activity in proliferating cells, it could not inhibit proliferation of KJD-1/SV40 cells. These results demonstrate that E2F6 does not contain the domains required for modulation of squamous differentiation and imply isoform-specific functions for individual E2F family members.
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Affiliation(s)
- Chung Fai Wong
- Epithelial Pathobiology Group, Cancer Biology Programme, Centre for Immunology and Cancer Research, University of Queensland, Princess Alexandra Hospital, Woolloongabba, Queensland 4102, Australia
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22
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Martirosyan AR, Rahim-Bata R, Freeman AB, Clarke CD, Howard RL, Strobl JS. Differentiation-inducing quinolines as experimental breast cancer agents in the MCF-7 human breast cancer cell model. Biochem Pharmacol 2004; 68:1729-38. [PMID: 15450938 DOI: 10.1016/j.bcp.2004.05.003] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2004] [Accepted: 05/03/2004] [Indexed: 11/26/2022]
Abstract
The purpose of this work is to develop agents for cancer differentiation therapy. We showed that five antiproliferative quinoline compounds in the National Cancer Institute database stimulated cell differentiation at growth inhibitory concentrations (3-14 microM) in MCF-7 human breast tumor cells in vitro. The differentiation-inducing quinolines caused lipid droplet accumulation, a phenotypic marker of differentiation, loss of Ki67 antigen expression, a cell cycle marker indicative of exit into G0, and reduced protein levels of the G1--S transcription factor, E2F1. The antimalarial quinolines, chloroquine, hydroxychloroquine and quinidine had similar effects in MCF-7 cells, but were 3-10 times less potent than the NSC compounds. NSC3852 and NSC86371 inhibited histone deacetylase (HDAC) activity in vitro and caused DNA damage and apoptosis in MCF-7 cells, consistent with their differentiation and antiproliferative activities. However, the HDAC assay results showed that for other compounds, direct HDAC enzyme inhibition was not required for differentiation activity. E2F1 protein was suppressed by all differentiation quinolines, but not by non-differentiating analogs, quinoline and primaquine. At equivalent antiproliferative concentrations, NSC69603 caused the greatest decrease in E2F1 protein (90%) followed by antimalarials quinidine and hydroxychloroquine. NSC69603 did not cause DNA damage. The other NSC compounds caused DNA damage and apoptosis and reduced E2F1 levels. The physicochemical properties of NSC3852, NSC69603, NSC86371, and NSC305819 predicted they are drug candidates suitable for development as experimental breast tumor cell differentiation agents. We conclude DNA damage and reductions in E2F1 protein are mechanistically important to the differentiation and antiproliferative activities of these quinoline drug candidates.
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Affiliation(s)
- Anna R Martirosyan
- Department of Biochemistry & Molecular Pharmacology, West Virginia University, Morgantown, WV 26506, USA
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23
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Stapelberg M, Tomasetti M, Alleva R, Gellert N, Procopio A, Neuzil J. α-Tocopheryl succinate inhibits proliferation of mesothelioma cells by selective down-regulation of fibroblast growth factor receptors. Biochem Biophys Res Commun 2004; 318:636-41. [PMID: 15144885 DOI: 10.1016/j.bbrc.2004.04.072] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2004] [Indexed: 02/03/2023]
Abstract
alpha-Tocopheryl succinate (alpha-TOS), a redox-silent analogue of vitamin E, inhibits malignant mesotheliomas (MM) in a pre-clinical model. Here we investigated the underlying mechanism. Exposure of MM cells to alpha-TOS triggered apoptosis at higher and inhibited proliferation at lower concentrations, while this effect was not observed in non-malignant mesothelial cells. Sub-apoptotic doses of alpha-TOS caused down-regulation of fibroblast growth factor receptor-1 (FGFR1) selectively in MM cells, while the effect on FGFR2 was only marginal. FGF1 and FGF2 enhanced MM cell proliferation that was suppressed by alpha-TOS. Over-expression of E2F1, a transcriptional factor of FGFR1, but not its dominant-negative counterpart, partially blocked the inhibitory activity of alpha-TOS on MM cell proliferation. Our data suggest a novel mechanism by which a clinically intriguing agent selectively suppresses proliferation of cancer cells, as shown here for the untreatable mesotheliomas.
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MESH Headings
- Apoptosis/drug effects
- Cell Cycle Proteins
- Cell Division/drug effects
- Cell Line
- Cell Line, Tumor
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/metabolism
- Down-Regulation/drug effects
- E2F Transcription Factors
- E2F1 Transcription Factor
- Flow Cytometry
- Humans
- Mesothelioma/drug therapy
- Mesothelioma/genetics
- Mesothelioma/metabolism
- Mesothelioma/pathology
- RNA, Messenger/biosynthesis
- Receptor Protein-Tyrosine Kinases/antagonists & inhibitors
- Receptor Protein-Tyrosine Kinases/biosynthesis
- Receptor Protein-Tyrosine Kinases/genetics
- Receptor Protein-Tyrosine Kinases/metabolism
- Receptor Protein-Tyrosine Kinases/physiology
- Receptor, Fibroblast Growth Factor, Type 1
- Receptor, Fibroblast Growth Factor, Type 2
- Receptors, Fibroblast Growth Factor/antagonists & inhibitors
- Receptors, Fibroblast Growth Factor/biosynthesis
- Receptors, Fibroblast Growth Factor/genetics
- Receptors, Fibroblast Growth Factor/metabolism
- Receptors, Fibroblast Growth Factor/physiology
- Recombinant Proteins/genetics
- Recombinant Proteins/metabolism
- Tocopherols
- Transcription Factors/genetics
- Transcription Factors/metabolism
- Transfection
- Vitamin E/analogs & derivatives
- Vitamin E/pharmacology
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Affiliation(s)
- Michael Stapelberg
- School of Health Science, Griffith University, Southport, Qld, Australia
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Smith L, Dahler AL, Cavanagh LL, Popa C, Barnes LM, Serewko-Auret MMM, Fai Wong C, Saunders NA. Modulation of proliferation-specific and differentiation-specific markers in human keratinocytes by SMAD7. Exp Cell Res 2004; 294:356-65. [PMID: 15023526 DOI: 10.1016/j.yexcr.2003.12.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2003] [Revised: 12/08/2003] [Indexed: 10/26/2022]
Abstract
We examined the potential role of SMAD7 in human epidermal keratinocyte differentiation. Overexpression of SMAD7 inhibited the activity of the proliferation-specific promoters for the keratin 14 and cdc2 genes and reduced the expression of the mRNA for the proliferation-specific genes cdc2 and E2F1. The ability of SMAD7 to suppress cdc2 promoter activity was lost in transformed keratinocyte cell lines and was mediated by a domain(s) located between aa 195-395 of SMAD7. This domain lies outside the domain required to inhibit TGFbeta1 signaling, suggesting that this activity is mediated by a novel functional domain(s). Examination of AP1, NFkappaB, serum response element, Gli, wnt, and E2F responsive reporters indicated that SMAD7 significantly suppressed the E2F responsive reporter and modestly increased AP1 activity in proliferating keratinocytes. These data suggest that SMAD7 may have a role in TGFbeta-independent signaling events in proliferating/undifferentiated keratinocytes. The effects of SMAD7 in differentiated keratinocytes indicated a more traditional role for SMAD7 as an inhibitor of TGFbeta action. SMAD7 was unable to initiate the expression of differentiation markers but was able to superinduce/derepress differentiation-specific markers and genes in differentiated keratinocytes. This latter role is consistent with the ability of SMAD7 to inhibit TGFbeta-mediated suppression of keratinocyte differentiation and suggest that the opposing actions of SMAD7 and TGFbeta may serve to modulate squamous differentiation.
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Affiliation(s)
- Louise Smith
- Epithelial Pathobiology Group, Cancer Biology Programme, Centre for Immunology and Cancer Research, University of Queensland, Princess Alexandra Hospital, Brisbane, Queensland, Australia
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