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Daniel CJ, Pelz C, Wang X, Munks MW, Ko A, Murugan D, Byers SA, Juarez E, Taylor KL, Fan G, Coussens LM, Link JM, Sears RC. T-cell dysfunction upon expression of MYC with altered phosphorylation at Threonine 58 and Serine 62. Mol Cancer Res 2022; 20:1151-1165. [PMID: 35380701 DOI: 10.1158/1541-7786.mcr-21-0560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Revised: 03/01/2022] [Accepted: 03/29/2022] [Indexed: 11/16/2022]
Abstract
As a transcription factor that promotes cell growth, proliferation and apoptosis, c-MYC (MYC) expression in the cell is tightly controlled. Disruption of oncogenic signaling pathways in human cancers can increase MYC protein stability, due to altered phosphorylation ratios at two highly conserved sites, Threonine 58 (T58) and Serine 62 (S62). The T58 to Alanine mutant (T58A) of MYC mimics the stabilized, S62 phosphorylated, and highly oncogenic form of MYC. The S62A mutant is also stabilized, lacks phosphorylation at both Serine 62 and Threonine 58, and has been shown to be non-transforming in vitro. However, several regulatory proteins are reported to associate with MYC lacking phosphorylation at S62 and T58, and the role this form of MYC plays in MYC transcriptional output and in vivo oncogenic function is understudied. We generated conditional c-Myc knock-in mice in which the expression of wild-type MYC (MYCWT), the T58A mutant (MYCT58A), or the S62A mutant (MYCS62A) with or without expression of endogenous Myc is controlled by the T-cell-specific Lck-Cre recombinase. MYCT58A expressing mice developed clonal T-cell lymphomas with 100% penetrance and conditional knock-out of endogenous Myc accelerated this lymphomagenesis. In contrast, MYCS62A mice developed clonal T-cell lymphomas at a much lower penetrance, and the loss of endogenous MYC reduced the penetrance while increasing the appearance of a non-transgene driven B-cell lymphoma with splenomegaly. Together, our study highlights the importance of regulated phosphorylation of MYC at T58 and S62 for T-cell transformation. Implications: Dysregulation of phosphorylation at conserved T58 and S62 residues of MYC differentially affects T-cell development and lymphomagenesis.
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Affiliation(s)
- Colin J Daniel
- Oregon Health & Science University, Portland, OR, United States
| | - Carl Pelz
- Oregon Health & Science University, Portland, OR, United States
| | - Xiaoyan Wang
- Oregon Health & Science University, Portland, Oregon, United States
| | - Michael W Munks
- Oregon Health & Science University, Portland, OR, United States
| | - Aaron Ko
- Oregon Health & Science University, Portland, OR, United States
| | | | - Sarah A Byers
- Oregon Health & Science University, Portland, OR, United States
| | - Eleonora Juarez
- Oregon Health & Science University, Portland, OR, United States
| | - Karyn L Taylor
- Oregon Health & Science University, Portland, OR, United States
| | - Guang Fan
- Oregon Health & Science University Knight Cancer Institute, Portland, OR, United States
| | - Lisa M Coussens
- Oregon Health & Science University, Portland, OR, United States
| | - Jason M Link
- Oregon Health & Science University, Portland, Oregon, United States
| | - Rosalie C Sears
- Oregon Health & Science University, Portland, Oregon, United States
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2
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Hayakawa T, Fujita F, Okada F, Sekiguchi K. Establishment and characterization of immortalized sweat gland myoepithelial cells. Sci Rep 2022; 12:7. [PMID: 34997030 PMCID: PMC8741770 DOI: 10.1038/s41598-021-03991-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2021] [Accepted: 12/08/2021] [Indexed: 11/16/2022] Open
Abstract
Sweat glands play an important role in thermoregulation via sweating, and protect human vitals. The reduction in sweating may increase the incidence of hyperthermia. Myoepithelial cells in sweat glands exhibit stemness characteristics and play a major role in sweat gland homeostasis and sweating processes. Previously, we successfully passaged primary myoepithelial cells in spheroid culture systems; however, they could not be maintained for long under in vitro conditions. No myoepithelial cell line has been established to date. In this study, we transduced two immortalizing genes into primary myoepithelial cells and developed a myoepithelial cell line. When compared with primary sweat gland cells, the immortalized myoepithelial cells (designated "iEM") continued to form spheroids after the 4th passage and expressed α-smooth muscle actin and other proteins that characterize myoepithelial cells. Furthermore, treatment with small compounds targeting the Wnt signaling pathways induced differentiation of iEM cells into luminal cells. Thus, we successfully developed an immortalized myoepithelial cell line having differentiation potential. As animal models are not useful for studying human sweat glands, our cell line will be helpful for studying the mechanisms underlying the pathophysiology of sweating disorders.
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Affiliation(s)
- Tomohisa Hayakawa
- Laboratory of Advanced Cosmetic Science, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Fumitaka Fujita
- Laboratory of Advanced Cosmetic Science, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka, 565-0871, Japan. .,Fundamental Research Institute, Mandom Corporation, Osaka, Japan.
| | - Fumihiro Okada
- Laboratory of Advanced Cosmetic Science, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka, 565-0871, Japan.,Fundamental Research Institute, Mandom Corporation, Osaka, Japan
| | - Kiyotoshi Sekiguchi
- Division of Matrixome Research and Application, Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka, 565-0871, Japan.
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3
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Lau HY, Tang J, Casey PJ, Wang M. Evaluating the Epithelial-Mesenchymal Program in Human Breast Epithelial Cells Cultured in Soft Agar Using a Novel Macromolecule Extraction Protocol. Cancers (Basel) 2021; 13:cancers13040807. [PMID: 33671920 PMCID: PMC7919038 DOI: 10.3390/cancers13040807] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Revised: 02/05/2021] [Accepted: 02/08/2021] [Indexed: 12/22/2022] Open
Abstract
Simple Summary Anchorage-independent soft agar colony formation assays have been widely used as an in vitro surrogate for in vivo tumour formation in xenograft studies, and has found much utility in studies such as cancer drug development. However, molecular characterisation of cells grown in soft agar has proven difficult and sometimes even impossible. We developed a set of new methods that allow DNA, RNA and proteins (including phosphoproteins) to be extracted from cells grown in soft agar, even without visible colony formation. We used these methods to demonstrate the role of the epithelial-mesenchymal program in the malignant transformation of a classical human mammary epithelial cell model. Abstract The ability to grow in anchorage-independent conditions is an important feature of malignant cells, and it is well-established that cellular phenotypes in adherent cultures can differ widely from phenotypes observed in xenografts and anchorage-independent conditions. The anchorage-independent soft-agar colony formation assay has been widely used as a bridge between adherent cell cultures and animal tumor studies, providing a reliable in vitro tool to predict the tumorigenicity of cancer cells. However, this functional assay is limited in its utility for molecular mechanistic studies, as currently there is no reliable method that allows the extraction of biological macromolecules from cells embedded in soft-agar matrices, especially in experimental conditions where no visible colonies form. We developed a set of new methods that enable the extraction of DNA, RNA and proteins directly from cells embedded in soft agar, allowing for a wide range of molecular signaling analysis. Using the new methods and human mammary epithelial cells (HMECs), we studied the role of epithelial-mesenchymal transition (EMT) in the ability of HMECs to form colonies in soft agar. We found that, when cultured in soft agar instead of in adherent cultures, immortalized non-malignant HME-hTERT cells upregulated the epithelial program, which was noted to be necessary for their survival in this anchorage-independent condition. Overexpression of SV40 small T antigen (ST) or the EMT master-regulator SNAI1 negates this requirement and significantly enhances colony formation in soft agar driven by mutant-RAS. Interestingly, we found that, similar to SNAI1, ST also promotes EMT changes in HMECs, providing further support for EMT as a prerequisite for the efficient anchorage-independent colony formation driven by mutant-RAS in our HMEC model.
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Affiliation(s)
- Hiu Yeung Lau
- Programme in Cancer and Stem Cell Biology, Duke-NUS Medical School, National University of Singapore, Singapore 169857, Singapore; (H.Y.L.); (J.T.); (P.J.C.)
| | - Jingyi Tang
- Programme in Cancer and Stem Cell Biology, Duke-NUS Medical School, National University of Singapore, Singapore 169857, Singapore; (H.Y.L.); (J.T.); (P.J.C.)
| | - Patrick J. Casey
- Programme in Cancer and Stem Cell Biology, Duke-NUS Medical School, National University of Singapore, Singapore 169857, Singapore; (H.Y.L.); (J.T.); (P.J.C.)
| | - Mei Wang
- Programme in Cancer and Stem Cell Biology, Duke-NUS Medical School, National University of Singapore, Singapore 169857, Singapore; (H.Y.L.); (J.T.); (P.J.C.)
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117596, Singapore
- Correspondence: ; Tel.: +65-6516-8608
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4
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Profound Reprogramming towards Stemness in Pancreatic Cancer Cells as Adaptation to AKT Inhibition. Cancers (Basel) 2020; 12:cancers12082181. [PMID: 32764385 PMCID: PMC7464748 DOI: 10.3390/cancers12082181] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2020] [Revised: 07/30/2020] [Accepted: 08/03/2020] [Indexed: 12/17/2022] Open
Abstract
Cancer cells acquire resistance to cytotoxic therapies targeting major survival pathways by adapting their metabolism. The AKT pathway is a major regulator of human pancreatic adenocarcinoma progression and a key pharmacological target. The mechanisms of adaptation to long-term silencing of AKT isoforms of human and mouse pancreatic adenocarcinoma cancer cells were studied. Following silencing, cancer cells remained quiescent for long periods of time, after which they recovered proliferative capacities. Adaptation caused profound proteomic changes largely affecting mitochondrial biogenesis, energy metabolism and acquisition of a number of distinct cancer stem cell (CSC) characteristics depending on the AKT isoform that was silenced. The adaptation to AKT1 silencing drove most de-differentiation and acquisition of stemness through C-MYC down-modulation and NANOG upregulation, which were required for survival of adapted CSCs. The changes associated to adaptation sensitized cancer cells to inhibitors targeting regulators of oxidative respiration and mitochondrial biogenesis. In vivo pharmacological co-inhibition of AKT and mitochondrial metabolism effectively controlled pancreatic adenocarcinoma growth in pre-clinical models.
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5
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Casciano JC, Perry C, Cohen-Nowak AJ, Miller KD, Vande Voorde J, Zhang Q, Chalmers S, Sandison ME, Liu Q, Hedley A, McBryan T, Tang HY, Gorman N, Beer T, Speicher DW, Adams PD, Liu X, Schlegel R, McCarron JG, Wakelam MJO, Gottlieb E, Kossenkov AV, Schug ZT. MYC regulates fatty acid metabolism through a multigenic program in claudin-low triple negative breast cancer. Br J Cancer 2020; 122:868-884. [PMID: 31942031 PMCID: PMC7078291 DOI: 10.1038/s41416-019-0711-3] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Revised: 11/22/2019] [Accepted: 12/19/2019] [Indexed: 02/06/2023] Open
Abstract
Background Recent studies have suggested that fatty acid oxidation (FAO) is a key metabolic pathway for the growth of triple negative breast cancers (TNBCs), particularly those that have high expression of MYC. However, the underlying mechanism by which MYC promotes FAO remains poorly understood. Methods We used a combination of metabolomics, transcriptomics, bioinformatics, and microscopy to elucidate a potential mechanism by which MYC regulates FAO in TNBC. Results We propose that MYC induces a multigenic program that involves changes in intracellular calcium signalling and fatty acid metabolism. We determined key roles for fatty acid transporters (CD36), lipases (LPL), and kinases (PDGFRB, CAMKK2, and AMPK) that each contribute to promoting FAO in human mammary epithelial cells that express oncogenic levels of MYC. Bioinformatic analysis further showed that this multigenic program is highly expressed and predicts poor survival in the claudin-low molecular subtype of TNBC, but not other subtypes of TNBCs, suggesting that efforts to target FAO in the clinic may best serve claudin-low TNBC patients. Conclusion We identified critical pieces of the FAO machinery that have the potential to be targeted for improved treatment of patients with TNBC, especially the claudin-low molecular subtype.
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Affiliation(s)
- Jessica C Casciano
- The Wistar Institute, Molecular and Cellular Oncogenesis, 3601 Spruce Street, Philadelphia, PA, 19104, USA
| | - Caroline Perry
- The Wistar Institute, Molecular and Cellular Oncogenesis, 3601 Spruce Street, Philadelphia, PA, 19104, USA.,Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Adam J Cohen-Nowak
- The Wistar Institute, Molecular and Cellular Oncogenesis, 3601 Spruce Street, Philadelphia, PA, 19104, USA
| | - Katelyn D Miller
- The Wistar Institute, Molecular and Cellular Oncogenesis, 3601 Spruce Street, Philadelphia, PA, 19104, USA
| | - Johan Vande Voorde
- The Beatson Institute, Garscube Estate, Switchback Road, Glasgow, G61 1BD, UK
| | - Qifeng Zhang
- The Babraham Institute, Babraham Research Campus, Cambridge, CB22 3AT, UK
| | - Susan Chalmers
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, SIPBS Building, 161 Cathedral Street, Glasgow, G4 0RE, UK
| | - Mairi E Sandison
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, SIPBS Building, 161 Cathedral Street, Glasgow, G4 0RE, UK.,Department of Biomedical Engineering, University of Strathclyde, Wolfson Centre, 106 Rottenrow, Glasgow, G4 0NW, UK
| | - Qin Liu
- The Wistar Institute, Molecular and Cellular Oncogenesis, 3601 Spruce Street, Philadelphia, PA, 19104, USA
| | - Ann Hedley
- The Beatson Institute, Garscube Estate, Switchback Road, Glasgow, G61 1BD, UK
| | - Tony McBryan
- The Beatson Institute, Garscube Estate, Switchback Road, Glasgow, G61 1BD, UK.,Institute of Cancer Sciences, College of Medical, Veterinary, and Life Sciences, University of Glasgow, Glasgow, G61 1BD, UK
| | - Hsin-Yao Tang
- The Wistar Institute, Molecular and Cellular Oncogenesis, 3601 Spruce Street, Philadelphia, PA, 19104, USA
| | - Nicole Gorman
- The Wistar Institute, Molecular and Cellular Oncogenesis, 3601 Spruce Street, Philadelphia, PA, 19104, USA
| | - Thomas Beer
- The Wistar Institute, Molecular and Cellular Oncogenesis, 3601 Spruce Street, Philadelphia, PA, 19104, USA
| | - David W Speicher
- The Wistar Institute, Molecular and Cellular Oncogenesis, 3601 Spruce Street, Philadelphia, PA, 19104, USA
| | - Peter D Adams
- Sanford Burnham Prebys Medical Discovery Institute, 10901 North Torrey Pines Road, La Jolla, CA, 92037, USA
| | - Xuefeng Liu
- Center for Cell Reprogramming, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, 3900 Reservoir Road, Washington D.C., 20057, USA
| | - Richard Schlegel
- Center for Cell Reprogramming, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, 3900 Reservoir Road, Washington D.C., 20057, USA
| | - John G McCarron
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, SIPBS Building, 161 Cathedral Street, Glasgow, G4 0RE, UK
| | | | - Eyal Gottlieb
- The Beatson Institute, Garscube Estate, Switchback Road, Glasgow, G61 1BD, UK.,The Ruth and Bruce Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, 1 Efron St. Bat Galim, 3525433, Haifa, Israel
| | - Andrew V Kossenkov
- The Wistar Institute, Molecular and Cellular Oncogenesis, 3601 Spruce Street, Philadelphia, PA, 19104, USA
| | - Zachary T Schug
- The Wistar Institute, Molecular and Cellular Oncogenesis, 3601 Spruce Street, Philadelphia, PA, 19104, USA.
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6
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Jiang D, Song Y, Cao W, Wang X, Jiang D, Lv Z, Yang Z, Li F. p53-independent role of MYC mutant T58A in the proliferation and apoptosis of breast cancer cells. Oncol Lett 2019; 17:1071-1079. [PMID: 30655867 PMCID: PMC6312996 DOI: 10.3892/ol.2018.9688] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 09/24/2018] [Indexed: 12/31/2022] Open
Abstract
Myc proto-oncogene (MYC) is an oncoprotein that promotes proliferation and apoptosis. MYC mutations frequently disrupt the apoptotic processes during tumorigenesis. In the present study, the effects of the MYC point mutation T58A on the progression of a cellular tumor antigen p53 (p53)-/- human breast cancer cell line was analyzed, and the mechanism of p53-independent MYC-induced apoptosis was investigated. HCC1937 cells were transfected with mutant (T58A) or wild-type (WT) MYC using lentiviral vectors. The proliferation of transfected cells was evaluated by colony formation and MTT assays, and apoptosis was analyzed by flow cytometry and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assays. WT MYC was transfected into HCC1937 cells exhibiting p14/p21 silencing through lentivirus-mediated RNA interference. The expression levels of Bim were detected by reverse transcription-quantitative polymerase chain reaction and western blot analyses. Mutant MYC proteins retained the ability to stimulate the proliferation of HCC1937 cells, although they were defective at promoting apoptosis due to a failure to induce the Bcl-2 homology 3 domain-only protein Bim. When p14 was silenced, the effects of mutant MYC on proliferation and apoptosis were weakened. When p21 was silenced, the effects of mutant MYC were strengthened. Breast cancer-derived T58A MYC mutations are unable to activate Bim due to their failure to regulate p14/p21. It was concluded that mutant MYC was more effective compared with WT MYC at promoting the progression of breast cancer.
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Affiliation(s)
- Dandan Jiang
- Breast Center, The Affiliated Hospital of Qingdao University, Qingdao, Shandong 266003, P.R. China
| | - Yuhua Song
- Breast Center, The Affiliated Hospital of Qingdao University, Qingdao, Shandong 266003, P.R. China
| | - Weihong Cao
- Breast Center, The Affiliated Hospital of Qingdao University, Qingdao, Shandong 266003, P.R. China
| | - Xingang Wang
- Breast Center, The Affiliated Hospital of Qingdao University, Qingdao, Shandong 266003, P.R. China
| | - Danni Jiang
- Imaging Department, The Affiliated Hospital of Qingdao University, Qingdao, Shandong 266003, P.R. China
| | - Zhidong Lv
- Breast Center, The Affiliated Hospital of Qingdao University, Qingdao, Shandong 266003, P.R. China
| | - Zhaochuan Yang
- Breast Center, The Affiliated Hospital of Qingdao University, Qingdao, Shandong 266003, P.R. China
| | - Funian Li
- Breast Center, The Affiliated Hospital of Qingdao University, Qingdao, Shandong 266003, P.R. China
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7
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Dakic A, DiVito K, Fang S, Suprynowicz F, Gaur A, Li X, Palechor-Ceron N, Simic V, Choudhury S, Yu S, Simbulan-Rosenthal CM, Rosenthal D, Schlegel R, Liu X. ROCK inhibitor reduces Myc-induced apoptosis and mediates immortalization of human keratinocytes. Oncotarget 2018; 7:66740-66753. [PMID: 27556514 PMCID: PMC5341834 DOI: 10.18632/oncotarget.11458] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Accepted: 08/11/2016] [Indexed: 01/06/2023] Open
Abstract
The Myc/Max/Mad network plays a critical role in cell proliferation, differentiation and apoptosis and c-Myc is overexpressed in many cancers, including HPV-positive cervical cancer cell lines. Despite the tolerance of cervical cancer keratinocytes to high Myc expression, we found that the solitary transduction of the Myc gene into primary cervical and foreskin keratinocytes induced rapid cell death. These findings suggested that the anti-apoptotic activity of E7 in cervical cancer cells might be responsible for negating the apoptotic activity of over-expressed Myc. Indeed, our earlier in vitro studies demonstrated that Myc and E7 synergize in the immortalization of keratinocytes. Since we previously postulated that E7 and the ROCK inhibitor, Y-27632, were members of the same functional pathway in cell immortalization, we tested whether Y-27632 would inhibit apoptosis induced by the over-expression of Myc. Our findings indicate that Y-27632 rapidly inhibited Myc-induced membrane blebbing and cellular apoptosis and, more generally, functioned as an inhibitor of extrinsic and intrinsic pathways of cell death. Most important, Y-27632 cooperated with Myc to immortalize keratinocytes efficiently, indicating that apoptosis is a major barrier to Myc-induced immortalization of keratinocytes. The anti-apoptotic activity of Y-27632 correlated with a reduction in p53 serine 15 phosphorylation and the consequent reduction in the expression of downstream target genes p21 and DAPK1, two genes involved in the induction of cell death.
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Affiliation(s)
- Aleksandra Dakic
- Department of Pathology, Georgetown University Medical School, Washington, DC 20057, USA.,Center for Cell Reprogramming, Georgetown University Medical School, Washington, DC 20057, USA
| | - Kyle DiVito
- Department of Molecular and Cell Biology and Biochemistry, Georgetown University Medical School, Washington, DC 20057, USA
| | - Shuang Fang
- Department of Pathology, Georgetown University Medical School, Washington, DC 20057, USA.,Center for Cell Reprogramming, Georgetown University Medical School, Washington, DC 20057, USA
| | - Frank Suprynowicz
- Department of Pathology, Georgetown University Medical School, Washington, DC 20057, USA.,Center for Cell Reprogramming, Georgetown University Medical School, Washington, DC 20057, USA
| | - Anirudh Gaur
- Department of Molecular and Cell Biology and Biochemistry, Georgetown University Medical School, Washington, DC 20057, USA
| | - Xin Li
- Department of Biostatistics, Bioinformatics, Georgetown University Medical School, Washington, DC 20057, USA
| | - Nancy Palechor-Ceron
- Department of Pathology, Georgetown University Medical School, Washington, DC 20057, USA.,Center for Cell Reprogramming, Georgetown University Medical School, Washington, DC 20057, USA
| | - Vera Simic
- Department of Pathology, Georgetown University Medical School, Washington, DC 20057, USA.,Center for Cell Reprogramming, Georgetown University Medical School, Washington, DC 20057, USA
| | - Sujata Choudhury
- Department of Pathology, Georgetown University Medical School, Washington, DC 20057, USA.,Center for Cell Reprogramming, Georgetown University Medical School, Washington, DC 20057, USA
| | - Songtao Yu
- Department of Pathology, Georgetown University Medical School, Washington, DC 20057, USA.,Center for Cell Reprogramming, Georgetown University Medical School, Washington, DC 20057, USA
| | - Cynthia M Simbulan-Rosenthal
- Department of Molecular and Cell Biology and Biochemistry, Georgetown University Medical School, Washington, DC 20057, USA
| | - Dean Rosenthal
- Department of Molecular and Cell Biology and Biochemistry, Georgetown University Medical School, Washington, DC 20057, USA
| | - Richard Schlegel
- Department of Pathology, Georgetown University Medical School, Washington, DC 20057, USA.,Center for Cell Reprogramming, Georgetown University Medical School, Washington, DC 20057, USA
| | - Xuefeng Liu
- Department of Pathology, Georgetown University Medical School, Washington, DC 20057, USA.,Center for Cell Reprogramming, Georgetown University Medical School, Washington, DC 20057, USA
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8
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Time-Dependent Effects of POT1 Knockdown on Proliferation, Tumorigenicity, and HDACi Response of SK-OV3 Ovarian Cancer Cells. BIOMED RESEARCH INTERNATIONAL 2018; 2018:7184253. [PMID: 29546066 PMCID: PMC5818924 DOI: 10.1155/2018/7184253] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2017] [Accepted: 12/21/2017] [Indexed: 02/07/2023]
Abstract
The roles of protection of telomeres 1 (POT1) in human ovarian cancer have not been fully elucidated. Here, we investigated the impact of POT1 knockdown (POT1-KD) on in vitro cell proliferation, tumorigenesis, and histone deacetylase inhibitor (HDACi) response in human ovarian cancer-derived SK-OV3 cells. The POT1 gene was knocked down by infection with POT1 lenti-shRNA. POT1, c-Myc, and hTERT mRNA levels and relative telomere length were determined by qRT-PCR; POT1 protein levels were determined by western blot. The relative telomerase activity levels were detected using qTRAP; cell proliferation was assessed using cumulative population doubling (cPD) experiments. Cell tumorigenicity was evaluated by anchorage-independent cell growth assays, and cell response to HDACi was determined by luminescence cell viability assays. Results indicate that lenti-shRNA-mediated POT1-KD significantly reduced POT1 mRNA and protein expression. POT1-KD immediately downregulated c-Myc expression, which led to the inhibition of cell proliferation, tumorigenesis, and HDACi response. However, after brief suppression, c-Myc expression increased in the medium term, which resulted in enhanced cell proliferation, tumorigenesis, and HDACi response in the POT1-KD cells. Furthermore, we discovered that c-Myc regulated cell proliferation and tumorigenesis via hTERT/telomerase/telomere pathway.
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9
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Micocci KC, Moritz MNDO, Lino RLB, Fernandes LR, Lima AGF, Figueiredo CC, Morandi V, Selistre-de-Araujo HS. ADAM9 silencing inhibits breast tumor cells transmigration through blood and lymphatic endothelial cells. Biochimie 2016; 128-129:174-82. [PMID: 27554339 DOI: 10.1016/j.biochi.2016.08.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 08/13/2016] [Indexed: 01/16/2023]
Abstract
ADAMs are transmembrane multifunctional proteins that contain disintegrin and metalloprotease domains. ADAMs act in a diverse set of biological processes, including fertilization, inflammatory responses, myogenesis, cell migration, cell proliferation and ectodomain cleavage of membrane proteins. These proteins also have additional functions in pathological processes as cancer and metastasis development. ADAM9 is a member of ADAM protein family that is overexpressed in several types of human carcinomas. The aim of this study was to investigate the role of ADAM9 in hematogenous and lymphatic tumor cell dissemination assisting the development of new therapeutic tools. The role of ADAM9 in the interaction of breast tumor cells (MDA-MB-231) and endothelial cells was studied through RNA silencing. ADAM9 silencing in MDA-MB-231 cells had no influence in expression of several genes related to the metastatic process such as ADAM10, ADAM12, ADAM17, cMYC, MMP9, VEGF-A, VEGF-C, osteopontin and collagen XVII. However, there was a minor decrease in ADAM15 expression but an increase in that of MMP2. Moreover, ADAM9 silencing had no effect in the adhesion of MDA-MB-231 cells to vascular (HMEC-1 and HUVEC) and lymphatic cells (HMVEC-dLyNeo) under flow condition. Nevertheless, siADAM9 in MDA-MB-231 decreased transendothelial cell migration in vitro through HUVEC, HMEC-1 and HMVEC-dLyNeo (50%, 40% and 32% respectively). These results suggest a role for ADAM9 on the extravasation step of the metastatic cascade through both blood and lymph vessels.
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Affiliation(s)
- Kelli Cristina Micocci
- Departamento de Ciências Fisiológicas, Rodovia Washington Luís, Km 235, CEP 13565-905, São Carlos, SP, Brazil.
| | | | - Rafael Luis Bressani Lino
- Departamento de Ciências Fisiológicas, Rodovia Washington Luís, Km 235, CEP 13565-905, São Carlos, SP, Brazil
| | - Laila Ribeiro Fernandes
- Departamento de Biologia Celular, Rua São Francisco Xavier, 524, Pavilhão Haroldo Lisboa da Cunha - 2nd Floor, Rio de Janeiro, RJ, Brazil
| | - Antonio Gilclêr Ferreira Lima
- Departamento de Biologia Celular, Rua São Francisco Xavier, 524, Pavilhão Haroldo Lisboa da Cunha - 2nd Floor, Rio de Janeiro, RJ, Brazil
| | - Camila Castro Figueiredo
- Departamento de Biologia Celular, Rua São Francisco Xavier, 524, Pavilhão Haroldo Lisboa da Cunha - 2nd Floor, Rio de Janeiro, RJ, Brazil
| | - Verônica Morandi
- Departamento de Biologia Celular, Rua São Francisco Xavier, 524, Pavilhão Haroldo Lisboa da Cunha - 2nd Floor, Rio de Janeiro, RJ, Brazil
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10
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Gargini R, García-Escudero V, Izquierdo M, Wandosell F. Oncogene-mediated tumor transformation sensitizes cells to autophagy induction. Oncol Rep 2016; 35:3689-95. [PMID: 27035659 DOI: 10.3892/or.2016.4699] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Accepted: 05/18/2015] [Indexed: 11/06/2022] Open
Abstract
The process of tumorigenesis induces alterations in numerous cellular pathways including the main eukaryotic metabolic routes. It has been recently demonstrated that autophagy is part of the oncogene-induced senescence phenotype although its role in tumor establishment has not been completely clarified. In the present study, we showed that non‑transformed cells are sensitized to mitochondrial stress and autophagy induction when they are transformed by oncogenes such as c-Myc or Ras. We observed that overexpression of c-Myc or Ras increased AMP-activated protein kinase (AMPK) phosphorylation and the expression of p62, a known partner for degradation by autophagy. The activation of AMPK was found to favor the activation of FoxO3 which was prevented by the inhibition of AMPK. The transcriptional activation mediated by FoxO3 upregulated genes such as BNIP3 and LC3. Finally, the transformation by oncogenes such as c-Myc and Ras predisposes tumor cells to autophagy induction as a consequence of mitochondrial stress and impairs tumor growth in vitro and in vivo, which may have therapeutic implications.
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Affiliation(s)
- Ricardo Gargini
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Universidad Autonoma de Madrid, 28049 Madrid, Spain
| | - Vega García-Escudero
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Universidad Autonoma de Madrid, 28049 Madrid, Spain
| | - Marta Izquierdo
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Universidad Autonoma de Madrid, 28049 Madrid, Spain
| | - Francisco Wandosell
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Universidad Autonoma de Madrid, 28049 Madrid, Spain
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Ferrari N, Mohammed ZMA, Nixon C, Mason SM, Mallon E, McMillan DC, Morris JS, Cameron ER, Edwards J, Blyth K. Expression of RUNX1 correlates with poor patient prognosis in triple negative breast cancer. PLoS One 2014; 9:e100759. [PMID: 24967588 PMCID: PMC4072705 DOI: 10.1371/journal.pone.0100759] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Accepted: 05/28/2014] [Indexed: 12/21/2022] Open
Abstract
The RUNX1 transcription factor is widely recognised for its tumour suppressor effects in leukaemia. Recently a putative link to breast cancer has started to emerge, however the function of RUNX1 in breast cancer is still unknown. To investigate if RUNX1 expression was important to clinical outcome in primary breast tumours a tissue microarray (TMA) containing biopsies from 483 patients with primary operable invasive ductal breast cancer was stained by immunohistochemistry. RUNX1 was associated with progesterone receptor (PR)-positive tumours (P<0.05), more tumour CD4+(P<0.05) and CD8+(P<0.01) T-lymphocytic infiltrate, increased tumour CD138+plasma cell (P<0.01) and more CD68+macrophage infiltrate (P<0.001). RUNX1 expression did not influence outcome of oestrogen receptor (ER)-positive or HER2-positive disease, however on univariate analysis a high RUNX1 protein was significantly associated with poorer cancer-specific survival in patients with ER-negative (P<0.05) and with triple negative (TN) invasive breast cancer (P<0.05). Furthermore, multivariate Cox regression analysis of cancer-specific survival showed a trend towards significance in ER-negative patients (P<0.1) and was significant in triple negative patients (P<0.05). Of relevance, triple negative breast cancer currently lacks good biomarkers and patients with this subtype do not benefit from the option of targeted therapy unlike patients with ER-positive or HER2-positive disease. Using multivariate analysis RUNX1 was identified as an independent prognostic marker in the triple negative subgroup. Overall, our study identifies RUNX1 as a new prognostic indicator correlating with poor prognosis specifically in the triple negative subtype of human breast cancer.
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Affiliation(s)
- Nicola Ferrari
- Transgenic Models Lab, Cancer Research UK Beatson Institute, Glasgow, Scotland, United Kingdom
| | - Zahra M. A. Mohammed
- Academic Unit of Surgery, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, Scotland, United Kingdom
| | - Colin Nixon
- Transgenic Models Lab, Cancer Research UK Beatson Institute, Glasgow, Scotland, United Kingdom
| | - Susan M. Mason
- Transgenic Models Lab, Cancer Research UK Beatson Institute, Glasgow, Scotland, United Kingdom
| | - Elizabeth Mallon
- University Pathology Unit, Southern General Hospital, Glasgow, Scotland, United Kingdom
| | - Donald C. McMillan
- Academic Unit of Surgery, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, Scotland, United Kingdom
| | - Joanna S. Morris
- School of Veterinary Medicine, University of Glasgow, Glasgow, Scotland, United Kingdom
| | - Ewan R. Cameron
- School of Veterinary Medicine, University of Glasgow, Glasgow, Scotland, United Kingdom
| | - Joanne Edwards
- Institute of Cancer Sciences, University of Glasgow, Glasgow, Scotland, United Kingdom
| | - Karen Blyth
- Transgenic Models Lab, Cancer Research UK Beatson Institute, Glasgow, Scotland, United Kingdom
- * E-mail:
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12
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Wasylishen AR, Chan-Seng-Yue M, Bros C, Dingar D, Tu WB, Kalkat M, Chan PK, Mullen PJ, Huang L, Meyer N, Raught B, Boutros PC, Penn LZ. MYC phosphorylation at novel regulatory regions suppresses transforming activity. Cancer Res 2013; 73:6504-15. [PMID: 24030976 DOI: 10.1158/0008-5472.can-12-4063] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Despite its central role in human cancer, MYC deregulation is insufficient by itself to transform cells. Because inherent mechanisms of neoplastic control prevent precancerous lesions from becoming fully malignant, identifying transforming alleles of MYC that bypass such controls may provide fundamental insights into tumorigenesis. To date, the only activated allele of MYC known is T58A, the study of which led to identification of the tumor suppressor FBXW7 and its regulator USP28 as a novel therapeutic target. In this study, we screened a panel of MYC phosphorylation mutants for their ability to promote anchorage-independent colony growth of human MCF10A mammary epithelial cells, identifying S71A/S81A and T343A/S344A/S347A/S348A as more potent oncogenic mutants compared with wild-type (WT) MYC. The increased cell-transforming activity of these mutants was confirmed in SH-EP neuroblastoma cells and in three-dimensional MCF10A acini. Mechanistic investigations initiated by a genome-wide mRNA expression analysis of MCF10A acini identified 158 genes regulated by the mutant MYC alleles, compared with only 112 genes regulated by both WT and mutant alleles. Transcriptional gain-of-function was a common feature of the mutant alleles, with many additional genes uniquely dysregulated by individual mutant. Our work identifies novel sites of negative regulation in MYC and thus new sites for its therapeutic attack.
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Affiliation(s)
- Amanda R Wasylishen
- Authors' Affiliations: Department of Medical Biophysics, University of Toronto; Ontario Cancer Institute, Campbell Family Institute for Cancer Research, Princess Margaret Cancer Centre; and Ontario Institute for Cancer Research, Toronto, Ontario, Canada
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13
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Shah SN, Cope L, Poh W, Belton A, Roy S, Talbot CC, Sukumar S, Huso DL, Resar LMS. HMGA1: a master regulator of tumor progression in triple-negative breast cancer cells. PLoS One 2013; 8:e63419. [PMID: 23658826 PMCID: PMC3642138 DOI: 10.1371/journal.pone.0063419] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2013] [Accepted: 04/04/2013] [Indexed: 12/31/2022] Open
Abstract
Emerging evidence suggests that tumor cells metastasize by co-opting stem cell transcriptional networks, although the molecular underpinnings of this process are poorly understood. Here, we show for the first time that the high mobility group A1 (HMGA1) gene drives metastatic progression in triple negative breast cancer cells (MDA-MB-231, Hs578T) by reprogramming cancer cells to a stem-like state. Silencing HMGA1 expression in invasive, aggressive breast cancer cells dramatically halts cell growth and results in striking morphologic changes from mesenchymal-like, spindle-shaped cells to cuboidal, epithelial-like cells. Mesenchymal genes (Vimentin, Snail) are repressed, while E-cadherin is induced in the knock-down cells. Silencing HMGA1 also blocks oncogenic properties, including proliferation, migration, invasion, and orthotopic tumorigenesis. Metastatic progression following mammary implantation is almost completely abrogated in the HMGA1 knock-down cells. Moreover, silencing HMGA1 inhibits the stem cell property of three-dimensional mammosphere formation, including primary, secondary, and tertiary spheres. In addition, knock-down of HMGA1 depletes cancer initiator/cancer stem cells and prevents tumorigenesis at limiting dilutions. We also discovered an HMGA1 signature in triple negative breast cancer cells that is highly enriched in embryonic stem cells. Together, these findings indicate that HMGA1 is a master regulator of tumor progression in breast cancer by reprogramming cancer cells through stem cell transcriptional networks. Future studies are needed to determine how to target HMGA1 in therapy.
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Affiliation(s)
- Sandeep N Shah
- Hematology Division, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
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14
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Wasylishen AR, Kalkat M, Kim SS, Pandyra A, Chan PK, Oliveri S, Sedivy E, Konforte D, Bros C, Raught B, Penn LZ. MYC activity is negatively regulated by a C-terminal lysine cluster. Oncogene 2013; 33:1066-72. [PMID: 23435422 DOI: 10.1038/onc.2013.36] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2011] [Revised: 12/15/2012] [Accepted: 12/17/2012] [Indexed: 12/17/2022]
Abstract
The MYC oncogene is not only deregulated in cancer through abnormally high levels of expression, but also through oncogenic lesions in upstream signalling cascades. Modelling MYC deregulation using signalling mutants is a productive research strategy. For example, the MYC threonine-58 to alanine substitution mutant (T58A) within MYC-homology box 1 is more transforming than wild-type (WT) MYC, because of decreased apoptosis and increased protein stability. Understanding the regulatory mechanisms controlling T58 phosphorylation has led to new approaches for the development of MYC inhibitors. In this manuscript, we have extensively characterized a MYC signalling mutant in which six lysine residues near the highly conserved MYC homology box IV and basic region have been substituted to arginines (6KR). Previous literature suggests these lysines can undergo both ubiquitylation and acetylation. We show MYC 6KR is able to fully rescue the slow growth phenotype of HO15.19 MYC-null fibroblasts, and promote cell cycle entry of serum-starved MCF10A cells. Remarkably, 6KR increased anchorage-independent colony growth compared with WT MYC in both SH-EP and MCF10A cells. Moreover, it was also more potent in promoting xenograft tumour growth of Rat1A and SH-EP cells. Combined, our data identify this region and these six lysines as important residues for the negative regulation of MYC-induced transformation. Mechanistically, we demonstrate that, unlike T58A, the increased transformation is not a result of increased protein stability or a reduced capacity for 6KR to induce apoptosis. Through expression analysis and luciferase reporter assays, we show that 6KR has increased transcriptional activity compared with WT MYC. Combined, through a comprehensive evaluation across multiple cell types, we identify an important regulatory region within MYC. A better understanding of the full scope of signalling through these residues will provide further insights into the mechanisms contributing to MYC-induced tumorigenesis and may unveil novel therapeutic strategies to target Myc in cancer.
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Affiliation(s)
- A R Wasylishen
- 1] Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada [2] Ontario Cancer Institute, Campbell Family Institute for Cancer Research, Princess Margaret Hospital, Toronto, Ontario, Canada
| | - M Kalkat
- 1] Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada [2] Ontario Cancer Institute, Campbell Family Institute for Cancer Research, Princess Margaret Hospital, Toronto, Ontario, Canada
| | - S S Kim
- 1] Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada [2] Ontario Cancer Institute, Campbell Family Institute for Cancer Research, Princess Margaret Hospital, Toronto, Ontario, Canada
| | - A Pandyra
- 1] Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada [2] Ontario Cancer Institute, Campbell Family Institute for Cancer Research, Princess Margaret Hospital, Toronto, Ontario, Canada
| | - P-K Chan
- Ontario Cancer Institute, Campbell Family Institute for Cancer Research, Princess Margaret Hospital, Toronto, Ontario, Canada
| | - S Oliveri
- 1] Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada [2] Ontario Cancer Institute, Campbell Family Institute for Cancer Research, Princess Margaret Hospital, Toronto, Ontario, Canada
| | - E Sedivy
- 1] Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada [2] Ontario Cancer Institute, Campbell Family Institute for Cancer Research, Princess Margaret Hospital, Toronto, Ontario, Canada
| | - D Konforte
- Ontario Cancer Institute, Campbell Family Institute for Cancer Research, Princess Margaret Hospital, Toronto, Ontario, Canada
| | - C Bros
- Ontario Cancer Institute, Campbell Family Institute for Cancer Research, Princess Margaret Hospital, Toronto, Ontario, Canada
| | - B Raught
- 1] Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada [2] Ontario Cancer Institute, Campbell Family Institute for Cancer Research, Princess Margaret Hospital, Toronto, Ontario, Canada
| | - L Z Penn
- 1] Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada [2] Ontario Cancer Institute, Campbell Family Institute for Cancer Research, Princess Margaret Hospital, Toronto, Ontario, Canada
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16
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Liu X, Ory V, Chapman S, Yuan H, Albanese C, Kallakury B, Timofeeva OA, Nealon C, Dakic A, Simic V, Haddad BR, Rhim JS, Dritschilo A, Riegel A, McBride A, Schlegel R. ROCK inhibitor and feeder cells induce the conditional reprogramming of epithelial cells. THE AMERICAN JOURNAL OF PATHOLOGY 2011; 180:599-607. [PMID: 22189618 DOI: 10.1016/j.ajpath.2011.10.036] [Citation(s) in RCA: 566] [Impact Index Per Article: 43.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2011] [Revised: 10/06/2011] [Accepted: 10/11/2011] [Indexed: 12/20/2022]
Abstract
We demonstrate that a Rho kinase inhibitor (Y-27632), in combination with fibroblast feeder cells, induces normal and tumor epithelial cells from many tissues to proliferate indefinitely in vitro, without transduction of exogenous viral or cellular genes. Primary prostate and mammary cells, for example, are reprogrammed toward a basaloid, stem-like phenotype and form well-organized prostaspheres and mammospheres in Matrigel. However, in contrast to the selection of rare stem-like cells, the described growth conditions can generate 2 × 10(6) cells in 5 to 6 days from needle biopsies, and can generate cultures from cryopreserved tissue and from fewer than four viable cells. Continued cell proliferation is dependent on both feeder cells and Y-27632, and the conditionally reprogrammed cells (CRCs) retain a normal karyotype and remain nontumorigenic. This technique also efficiently establishes cell cultures from human and rodent tumors. For example, CRCs established from human prostate adenocarcinoma displayed instability of chromosome 13, proliferated abnormally in Matrigel, and formed tumors in mice with severe combined immunodeficiency. The ability to rapidly generate many tumor cells from small biopsy specimens and frozen tissue provides significant opportunities for cell-based diagnostics and therapeutics (including chemosensitivity testing) and greatly expands the value of biobanking. In addition, the CRC method allows for the genetic manipulation of epithelial cells ex vivo and their subsequent evaluation in vivo in the same host.
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Affiliation(s)
- Xuefeng Liu
- Department of Pathology, Lombardi Comprehensive Cancer Center, Georgetown University Medical School, Washington, DC 20057, USA
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Mechanistic insight into Myc stabilization in breast cancer involving aberrant Axin1 expression. Proc Natl Acad Sci U S A 2011; 109:2790-5. [PMID: 21808024 DOI: 10.1073/pnas.1100764108] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
High expression of the oncoprotein Myc has been linked to poor outcome in human tumors. Although MYC gene amplification and translocations have been observed, this can explain Myc overexpression in only a subset of human tumors. Myc expression is in part controlled by its protein stability, which can be regulated by phosphorylation at threonine 58 (T58) and serine 62 (S62). We now report that Myc protein stability is increased in a number of breast cancer cell lines and this correlates with increased phosphorylation at S62 and decreased phosphorylation at T58. Moreover, we find this same shift in phosphorylation in primary breast cancers. The signaling cascade that controls phosphorylation at T58 and S62 is coordinated by the scaffold protein Axin1. We therefore examined Axin1 in breast cancer and report decreased AXIN1 expression and a shift in the ratio of expression of two naturally occurring AXIN1 splice variants. We demonstrate that this contributes to increased Myc protein stability, altered phosphorylation at S62 and T58, and increased oncogenic activity of Myc in breast cancer. Thus, our results reveal an important mode of Myc activation in human breast cancer and a mechanism contributing to Myc deregulation involving unique insight into inactivation of the Axin1 tumor suppressor in breast cancer.
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He XY, Zheng YM, Lan J, Wu YH, Yan J, He XN, Zhang T, He YL, Zheng YL, Zhang Y. Recombinant adenovirus-mediated human telomerase reverse transcriptase gene can stimulate cell proliferation and maintain primitive characteristics in bovine mammary gland epithelial cells. Dev Growth Differ 2011; 53:312-22. [DOI: 10.1111/j.1440-169x.2010.01236.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Wang X, Cunningham M, Zhang X, Tokarz S, Laraway B, Troxell M, Sears RC. Phosphorylation regulates c-Myc's oncogenic activity in the mammary gland. Cancer Res 2011; 71:925-36. [PMID: 21266350 DOI: 10.1158/0008-5472.can-10-1032] [Citation(s) in RCA: 124] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Expression of the c-Myc oncoprotein is affected by conserved threonine 58 (T58) and serine 62 (S62) phosphorylation sites that help to regulate c-Myc protein stability, and altered ratios of T58 and S62 phosphorylation have been observed in human cancer. Here, we report the development of 3 unique c-myc knock-in mice that conditionally express either c-Myc(WT) or the c-Myc(T58A) or c-Myc(S62A) phosphorylation mutant from the constitutively active ROSA26 locus in response to Cre recombinase to study the role of these phosphorylation sites in vivo. Using a mammary-specific Cre model, we found that expression of c-Myc(WT) resulted in increased mammary gland density, but normal morphology and no tumors at the level expressed from the ROSA promoter. In contrast, c-Myc(T58A) expression yielded enhanced mammary gland density, hyperplastic foci, cellular dysplasia, and mammary carcinoma, associated with increased genomic instability and suppressed apoptosis relative to c-Myc(WT). Alternatively, c-Myc(S62A) expression reduced mammary gland density relative to control glands, and this was associated with increased genomic instability and normal apoptotic function. Our results indicate that specific activities of c-Myc are differentially affected by T58 and S62 phosphorylation. This model provides a robust platform to interrogate the role that these phosphorylation sites play in c-Myc function during development and tumorigenesis.
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Affiliation(s)
- Xiaoyan Wang
- Molecular and Medical Genetics Department, Oregon Health and Sciences University, Portland, Oregon, USA
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Wang C, Lisanti MP, Liao DJ. Reviewing once more the c-myc and Ras collaboration: converging at the cyclin D1-CDK4 complex and challenging basic concepts of cancer biology. Cell Cycle 2011; 10:57-67. [PMID: 21200143 DOI: 10.4161/cc.10.1.14449] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The c-myc is a proto-oncogene that manifests aberrant expression at high frequencies in most types of human cancer. C-myc gene amplifications are often observed in various cancers as well. Ample studies have also proved that c-myc has a potent oncogenicity, which can be further enhanced by collaborations with other oncogenes such as Bcl-2 and activated Ras. Studies on the collaborations of c-myc with Ras or other genes in oncogenicity have established several basic concepts and have disclosed their underlying mechanisms of tumor biology, including "immortalization" and "transformation". In many cases, these collaborations may converge at the cyclin D1-CDK4 complex. In the meantime, however, many results from studies on the c-myc, Ras and cyclin D1-CDK4 also challenge these basic concepts of tumor biology and suggest to us that the immortalized status of cells should be emphasized. Stricter criteria and definitions for a malignantly transformed status and a benign status of cells in culture also need to be established to facilitate our study of the mechanisms for tumor formation and to better link up in vitro data with animal results and eventually with human cancer pathology.
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Affiliation(s)
- Chenguang Wang
- Department of Stem Cell and Regenerative Medicine, and Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, USA
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Byrne JA, Maleki S, Hardy JR, Gloss BS, Murali R, Scurry JP, Fanayan S, Emmanuel C, Hacker NF, Sutherland RL, Defazio A, O'Brien PM. MAL2 and tumor protein D52 (TPD52) are frequently overexpressed in ovarian carcinoma, but differentially associated with histological subtype and patient outcome. BMC Cancer 2010; 10:497. [PMID: 20846453 PMCID: PMC2949808 DOI: 10.1186/1471-2407-10-497] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2010] [Accepted: 09/17/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The four-transmembrane MAL2 protein is frequently overexpressed in breast carcinoma, and MAL2 overexpression is associated with gain of the corresponding locus at chromosome 8q24.12. Independent expression microarray studies predict MAL2 overexpression in ovarian carcinoma, but these had remained unconfirmed. MAL2 binds tumor protein D52 (TPD52), which is frequently overexpressed in ovarian carcinoma, but the clinical significance of MAL2 and TPD52 overexpression was unknown. METHODS Immunohistochemical analyses of MAL2 and TPD52 expression were performed using tissue microarray sections including benign, borderline and malignant epithelial ovarian tumours. Inmmunohistochemical staining intensity and distribution was assessed both visually and digitally. RESULTS MAL2 and TPD52 were significantly overexpressed in high-grade serous carcinomas compared with serous borderline tumours. MAL2 expression was highest in serous carcinomas relative to other histological subtypes, whereas TPD52 expression was highest in clear cell carcinomas. MAL2 expression was not related to patient survival, however high-level TPD52 staining was significantly associated with improved overall survival in patients with stage III serous ovarian carcinoma (log-rank test, p < 0.001; n = 124) and was an independent predictor of survival in the overall carcinoma cohort (hazard ratio (HR), 0.498; 95% confidence interval (CI), 0.34-0.728; p < 0.001; n = 221), and in serous carcinomas (HR, 0.440; 95% CI, 0.294-0.658; p < 0.001; n = 182). CONCLUSIONS MAL2 is frequently overexpressed in ovarian carcinoma, and TPD52 overexpression is a favourable independent prognostic marker of potential value in the management of ovarian carcinoma patients.
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Affiliation(s)
- Jennifer A Byrne
- Molecular Oncology Laboratory, Children's Cancer Research Unit, The Children's Hospital at Westmead, Westmead, New South Wales, Australia.
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