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Belyaeva E, Loginova N, Schroeder BA, Goldlust IS, Acharya A, Kumar S, Timashev P, Ulasov I. The spectrum of cell death in sarcoma. Biomed Pharmacother 2023; 162:114683. [PMID: 37031493 DOI: 10.1016/j.biopha.2023.114683] [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: 03/03/2023] [Revised: 04/01/2023] [Accepted: 04/06/2023] [Indexed: 04/11/2023] Open
Abstract
The balance between cell death and cell survival is a highly coordinated process by which cells break down and remove unnecessary or harmful materials in a controlled, highly regulated, and compartmentalized manner. Cell exposure to various stresses, such as oxygen starvation, a lack of nutrients, or exposure to radiation, can initiate autophagy. Autophagy is a carefully orchestrated process with multiple steps, each regulated by specific genes and proteins. Autophagy proteins impact cellular maintenance and cell fate in response to stress, and targeting this process is one of the most promising methods of anti-tumor therapy. It is currently not fully understood how autophagy affects different types of tumor cells, which makes it challenging to predict outcomes when this process is manipulated. In this review, we will explore the mechanisms of autophagy and investigate it as a potential and promising therapeutic target for aggressive sarcomas.
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Affiliation(s)
- Elizaveta Belyaeva
- Group of Experimental Biotherapy and Diagnostics, Institute for Regenerative Medicine, World-Class Research Centre "Digital Biodesign and Personalized Healthcare", I.M. Sechenov First Moscow State Medical University, Moscow 119991, Russia
| | - Nina Loginova
- Group of Experimental Biotherapy and Diagnostics, Institute for Regenerative Medicine, World-Class Research Centre "Digital Biodesign and Personalized Healthcare", I.M. Sechenov First Moscow State Medical University, Moscow 119991, Russia
| | - Brett A Schroeder
- National Cancer Institute, National Institutes of Health, Bethesda, MD 20814, USA
| | - Ian S Goldlust
- National Cancer Institute, National Institutes of Health, Bethesda, MD 20814, USA
| | - Arbind Acharya
- Laboratory of Cancer Immunology, Department of Zoology, Institute of Science, Banaras Hindu University, Varanasi 221005, Uttar Pradesh, India
| | - Sandeep Kumar
- Laboratory of Cancer Immunology, Department of Zoology, Institute of Science, Banaras Hindu University, Varanasi 221005, Uttar Pradesh, India
| | - Peter Timashev
- World-Class Research Centre "Digital Biodesign and Personalized Healthcare", Sechenov First Moscow State Medical University, Moscow 119991, Russia
| | - Ilya Ulasov
- Group of Experimental Biotherapy and Diagnostics, Institute for Regenerative Medicine, World-Class Research Centre "Digital Biodesign and Personalized Healthcare", I.M. Sechenov First Moscow State Medical University, Moscow 119991, Russia.
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Khan QA, Pediaditakis P, Malakhau Y, Esmaeilniakooshkghazi A, Ashkavand Z, Sereda V, Krupenko NI, Krupenko SA. CHIP E3 ligase mediates proteasomal degradation of the proliferation regulatory protein ALDH1L1 during the transition of NIH3T3 fibroblasts from G0/G1 to S-phase. PLoS One 2018; 13:e0199699. [PMID: 29979702 PMCID: PMC6034817 DOI: 10.1371/journal.pone.0199699] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Accepted: 06/12/2018] [Indexed: 12/27/2022] Open
Abstract
ALDH1L1 is a folate-metabolizing enzyme abundant in liver and several other tissues. In human cancers and cell lines derived from malignant tumors, the ALDH1L1 gene is commonly silenced through the promoter methylation. It was suggested that ALDH1L1 limits proliferation capacity of the cell and thus functions as putative tumor suppressor. In contrast to cancer cells, mouse cell lines NIH3T3 and AML12 do express the ALDH1L1 protein. In the present study, we show that the levels of ALDH1L1 in these cell lines fluctuate throughout the cell cycle. During S-phase, ALDH1L1 is markedly down regulated at the protein level. As the cell cultures become confluent and cells experience increased contact inhibition, ALDH1L1 accumulates in the cells. In agreement with this finding, NIH3T3 cells arrested in G1/S-phase by a thymidine block completely lose the ALDH1L1 protein. Treatment with the proteasome inhibitor MG-132 prevents such loss in proliferating NIH3T3 cells, suggesting the proteasomal degradation of the ALDH1L1 protein. The co-localization of ALDH1L1 with proteasomes, demonstrated by confocal microscopy, supports this mechanism. We further show that ALDH1L1 interacts with the chaperone-dependent E3 ligase CHIP, which plays a key role in the ALDH1L1 ubiquitination and degradation. In NIH3T3 cells, silencing of CHIP by siRNA halts, while transient expression of CHIP promotes, the ALDH1L1 loss. The downregulation of ALDH1L1 is associated with the accumulation of the ALDH1L1 substrate 10-formyltetrahydrofolate, which is required for de novo purine biosynthesis, a key pathway activated in S-phase. Overall, our data indicate that CHIP-mediated proteasomal degradation of ALDH1L1 facilitates cellular proliferation.
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Affiliation(s)
- Qasim A. Khan
- Nutrition Research Institute, University of North Carolina at Chapel Hill, Kannapolis, North Carolina, United States of America
| | - Peter Pediaditakis
- Nutrition Research Institute, University of North Carolina at Chapel Hill, Kannapolis, North Carolina, United States of America
| | - Yuryi Malakhau
- Nutrition Research Institute, University of North Carolina at Chapel Hill, Kannapolis, North Carolina, United States of America
| | - Amin Esmaeilniakooshkghazi
- Nutrition Research Institute, University of North Carolina at Chapel Hill, Kannapolis, North Carolina, United States of America
| | - Zahra Ashkavand
- Nutrition Research Institute, University of North Carolina at Chapel Hill, Kannapolis, North Carolina, United States of America
| | - Valentin Sereda
- Nutrition Research Institute, University of North Carolina at Chapel Hill, Kannapolis, North Carolina, United States of America
| | - Natalia I. Krupenko
- Nutrition Research Institute, University of North Carolina at Chapel Hill, Kannapolis, North Carolina, United States of America
- Department of Nutrition, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Sergey A. Krupenko
- Nutrition Research Institute, University of North Carolina at Chapel Hill, Kannapolis, North Carolina, United States of America
- Department of Nutrition, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- * E-mail:
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Mishra PJ, Mishra PJ, Merlino G. Integrated Genomics Identifies miR-32/MCL-1 Pathway as a Critical Driver of Melanomagenesis: Implications for miR-Replacement and Combination Therapy. PLoS One 2016; 11:e0165102. [PMID: 27846237 PMCID: PMC5113037 DOI: 10.1371/journal.pone.0165102] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 10/06/2016] [Indexed: 12/03/2022] Open
Abstract
Aims Cutaneous malignant melanoma is among the deadliest human cancers, broadly resistant to most clinical therapies. A majority of patients with BRAFV600E melanomas respond well to inhibitors such as vemurafenib, but all ultimately relapse. Moreover, there are no viable treatment options available for other non-BRAF melanoma subtypes in the clinic. A key to improving treatment options lies in a better understanding of mechanisms underlying melanoma progression, which are complex and heterogeneous. Methods In this study we integrated gene and microRNA (miRNA) expression data from genetically engineered mouse models of highly and poorly malignant melanocytic tumors, as well as available human melanoma databases, and discovered an important role for a pathway centered on a tumor suppressor miRNA, miR-32. Results Malignant tumors frequently exhibited poor expression of miR-32, whose targets include NRAS, PI3K and notably, MCL-1. Accordingly, MCL-1 was often highly expressed in melanomas, and when knocked down diminished oncogenic potential. Forced MCL-1 overexpression transformed immortalized primary mouse melanocytes, but only when also expressing activating mutations in BRAF, CRAF or PI3K. Importantly, both miR-32 replacement therapy and the MCL-1-specific antagonist sabutoclax demonstrated single-agent efficacy, and acted synergistically in combination with vemurafenib in preclinical melanoma models. Conclusions We here identify miR-32/MCL-1 pathway members as key early genetic events driving melanoma progression, and suggest that their inhibition may be an effective anti-melanoma strategy irrespective of NRAS, BRAF, and PTEN status.
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Affiliation(s)
- Prasun J. Mishra
- Department of Biochemical and Cellular Pharmacology, Genentech Inc., South San Francisco, California, United States of America
- Laboratory of Cancer Biology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail: (PJM); (GM)
| | - Pravin J. Mishra
- Precision Genomics, Intermountain Healthcare, Dixie Regional Medical Center, St. George, Utah, United States of America
| | - Glenn Merlino
- Laboratory of Cancer Biology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail: (PJM); (GM)
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Tan X, Anzick SL, Khan SG, Ueda T, Stone G, Digiovanna JJ, Tamura D, Wattendorf D, Busch D, Brewer CC, Zalewski C, Butman JA, Griffith AJ, Meltzer PS, Kraemer KH. Chimeric negative regulation of p14ARF and TBX1 by a t(9;22) translocation associated with melanoma, deafness, and DNA repair deficiency. Hum Mutat 2013; 34:1250-9. [PMID: 23661601 DOI: 10.1002/humu.22354] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Accepted: 04/29/2013] [Indexed: 12/15/2022]
Abstract
Melanoma is the most deadly form of skin cancer and DiGeorge syndrome (DGS) is the most frequent interstitial deletion syndrome. We characterized a novel balanced t(9;22)(p21;q11.2) translocation in a patient with melanoma, DNA repair deficiency, and features of DGS including deafness and malformed inner ears. Using chromosome sorting, we located the 9p21 breakpoint in CDKN2A intron 1. This resulted in underexpression of the tumor suppressor p14 alternate reading frame (p14ARF); the reduced DNA repair was corrected by transfection with p14ARF. Ultraviolet radiation-type p14ARF mutations in his melanoma implicated p14ARF in its pathogenesis. The 22q11.2 breakpoint was located in a palindromic AT-rich repeat (PATRR22). We identified a new gene, FAM230A, that contains PATRR22 within an intron. The 22q11.2 breakpoint was located 800 kb centromeric to TBX1, which is required for inner ear development. TBX1 expression was greatly reduced. The translocation resulted in a chimeric transcript encoding portions of p14ARF and FAM230A. Inhibition of chimeric p14ARF-FAM230A expression increased p14ARF and TBX1 expression and improved DNA repair. Expression of the chimera in normal cells produced dominant negative inhibition of p14ARF. Similar chimeric mRNAs may mediate haploinsufficiency in DGS or dominant negative inhibition of other genes such as those involved in melanoma.
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Affiliation(s)
- Xiaohui Tan
- DNA Repair Section, Dermatology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892-4258, USA
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Abstract
Since cancer is one of the leading causes of death worldwide, there is an urgent need to find better treatments. Currently, the use of chemotherapeutics remains the predominant option for cancer therapy. However, one of the major obstacles for successful cancer therapy using these chemotherapeutics is that patients often do not respond or eventually develop resistance after initial treatment. Therefore identification of genes involved in chemotherapeutic response is critical for predicting tumour response and treating drug-resistant cancer patients. A group of genes commonly lost or inactivated are tumour suppressor genes, which can promote the initiation and progression of cancer through regulation of various biological processes such as cell proliferation, cell death and cell migration/invasion. Recently, mounting evidence suggests that these tumour suppressor genes also play a very important role in the response of cancers to a variety of chemotherapeutic drugs. In the present review, we will provide a comprehensive overview on how major tumour suppressor genes [Rb (retinoblastoma), p53 family, cyclin-dependent kinase inhibitors, BRCA1 (breast-cancer susceptibility gene 1), PTEN (phosphatase and tensin homologue deleted on chromosome 10), Hippo pathway, etc.] are involved in chemotherapeutic drug response and discuss their applications in predicting the clinical outcome of chemotherapy for cancer patients. We also propose that tumour suppressor genes are critical chemotherapeutic targets for the successful treatment of drug-resistant cancer patients in future applications.
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The former annotated human pseudogene dihydrofolate reductase-like 1 (DHFRL1) is expressed and functional. Proc Natl Acad Sci U S A 2011; 108:15157-62. [PMID: 21876184 DOI: 10.1073/pnas.1103605108] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Human dihydrofolate reductase (DHFR) was previously thought to be the only enzyme capable of the reduction of dihydrofolate to tetrahydrofolate; an essential reaction necessary to ensure a continuous supply of biologically active folate. DHFR has been studied extensively from a number of perspectives because of its role in health and disease. Although the presence of a number of intronless DHFR pseudogenes has been known since the 1980s, it was assumed that none of these were expressed or functional. We show that humans do have a second dihydrofolate reductase enzyme encoded by the former pseudogene DHFRP4, located on chromosome 3. We demonstrate that the DHFRP4, or dihydrofolate reductase-like 1 (DHFRL1), gene is expressed and shares some commonalities with DHFR. Recombinant DHFRL1 can complement a DHFR-negative phenotype in bacterial and mammalian cells but has a lower specific activity than DHFR. The K(m) for NADPH is similar for both enzymes but DHFRL1 has a higher K(m) for dihydrofolate when compared to DHFR. The need for a second reductase with lowered affinity for its substrate may fulfill a specific cellular requirement. The localization of DHFRL1 to the mitochondria, as demonstrated by confocal microscopy, indicates that mitochondrial dihydrofolate reductase activity may be optimal with a lowered affinity for dihydrofolate. We also found that DHFRL1 is capable of the same translational autoregulation as DHFR by binding to its own mRNA; with each enzyme also capable of replacing the other. The identification of DHFRL1 will have implications for previous research involving DHFR.
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Kolokythas A, Miloro M, Zhou X. Review of MicroRNA Proposed Target Genes in Oral Cancer. Part II. EJOURNAL OF ORAL MAXILLOFACIAL RESEARCH 2011; 2:e2. [PMID: 24421989 PMCID: PMC3886061 DOI: 10.5037/jomr.2011.2202] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/16/2011] [Accepted: 04/13/2011] [Indexed: 02/07/2023]
Abstract
Objectives Cancer is the product of alterations in oncogenes, tumour suppressor genes
and most recently microRNA genes not as a single event or single change but
rather as a multistep process. The role of microRNA genes in carcinogenesis
is recently explored and appears to be an early event in the pathogenesis of
this as well as other disease processes and occurs via gene regulation by
their own products, the microRNAs. The purpose of this article was to review
the literature concerning MicroRNA proposed target genes in oral cancer. Material and Methods A review of the available literature from 2000 to 2011 regarding the
potential roles assumed by microRNAs in oral cancer was undertaken using
PubMed, Medline, Scholar Google and Scopus. Keywords for the search were:
microRNA and oral cancer and target genes, microRNA deregulation and oral
cancer, microRNA and carcinogenesis in the head and neck/oral cavity.
English language full length articles were reviewed. Results Several microRNAs deregulated in oral cancer have been functionally validated
and their exact target genes have been identified. Furthermore the
carcinogenesis pathways impacted by these alterations has been proposed for
some of these microRNAs. Conclusions The expanding knowledge of specific roles of certain microRNAs is further
contributing to our understanding of the complexity of tumour progression
and behaviour. Consideration of this information and incorporation into
treatment modalities through targeted therapy could potentially enhance our
abilities to improve outcome especially when other established therapies
have failed.
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Affiliation(s)
- Antonia Kolokythas
- Department of Oral and Maxillofacial Surgery, University of Illinois at Chicago USA. ; Center of Molecular Biology and Oral Diseases, College of Dentistry, University of Illinois at Chicago USA. ; Cancer Center, University of Illinois at Chicago USA
| | - Michael Miloro
- Department of Oral and Maxillofacial Surgery, University of Illinois at Chicago USA
| | - Xiaofeng Zhou
- Center of Molecular Biology and Oral Diseases, College of Dentistry, University of Illinois at Chicago USA. ; Department of Periodontics, College of Dentistry, University of Illinois at Chicago USA
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Moroz MA, Kochetkov T, Cai S, Wu J, Shamis M, Nair J, de Stanchina E, Serganova I, Schwartz GK, Banerjee D, Bertino JR, Blasberg RG. Imaging colon cancer response following treatment with AZD1152: a preclinical analysis of [18F]fluoro-2-deoxyglucose and 3'-deoxy-3'-[18F]fluorothymidine imaging. Clin Cancer Res 2011; 17:1099-110. [PMID: 21245090 DOI: 10.1158/1078-0432.ccr-10-1430] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
PURPOSE To determine whether treatment response to the Aurora B kinase inhibitor, AZD1152, could be monitored early in the course of therapy by noninvasive [(18)F]-labeled fluoro-2-deoxyglucose, [(18)F]FDG, and/or 3'-deoxy-3'-[(18)F]fluorothymidine, [(18)F]FLT, PET imaging. EXPERIMENTAL DESIGN AZD1152-treated and control HCT116 and SW620 xenograft-bearing animals were monitored for tumor size and by [(18)F]FDG, and [(18)F]FLT PET imaging. Additional studies assessed the endogenous and exogenous contributions of thymidine synthesis in the two cell lines. RESULTS Both xenografts showed a significant volume-reduction to AZD1152. In contrast, [(18)F]FDG uptake did not demonstrate a treatment response. [(18)F]FLT uptake decreased to less than 20% of control values in AZD1152-treated HCT116 xenografts, whereas [(18)F]FLT uptake was near background levels in both treated and untreated SW620 xenografts. The EC(50) for AZD1152-HQPA was approximately 10 nmol/L in both SW620 and HCT116 cells; in contrast, SW620 cells were much more sensitive to methotrexate (MTX) and 5-Fluorouracil (5FU) than HCT116 cells. Immunoblot analysis demonstrated marginally lower expression of thymidine kinase in SW620 compared with HCT116 cells. The aforementioned results suggest that SW620 xenografts have a higher dependency on the de novo pathway of thymidine utilization than HCT116 xenografts. CONCLUSIONS AZD1152 treatment showed antitumor efficacy in both colon cancer xenografts. Although [(18)F]FDG PET was inadequate in monitoring treatment response, [(18)F]FLT PET was very effective in monitoring response in HCT116 xenografts, but not in SW620 xenografts. These observations suggest that de novo thymidine synthesis could be a limitation and confounding factor for [(18)F]FLT PET imaging and quantification of tumor proliferation, and this may apply to some clinical studies as well.
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Affiliation(s)
- Maxim A Moroz
- Department of Neurology, Memorial Sloan-Kettering Cancer Center, New York, New York 10065, USA
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Childs G, Fazzari M, Kung G, Kawachi N, Brandwein-Gensler M, McLemore M, Chen Q, Burk RD, Smith RV, Prystowsky MB, Belbin TJ, Schlecht NF. Low-level expression of microRNAs let-7d and miR-205 are prognostic markers of head and neck squamous cell carcinoma. THE AMERICAN JOURNAL OF PATHOLOGY 2009; 174:736-45. [PMID: 19179615 DOI: 10.2353/ajpath.2009.080731] [Citation(s) in RCA: 271] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Small noncoding microRNAs (miRNAs) have been shown to be abnormally expressed in every tumor type examined. The importance of miRNAs as potential cancer prognostic indicators is underscored by their involvement in the regulation of basic cellular processes such as cell proliferation, differentiation, and apoptosis. In this study, miRNA expression profiles of head and neck squamous cell carcinoma (HNSCC) tumor and adjacent normal tissue were examined by microarray analysis and validated by quantitative TaqMan real-time polymerase chain reaction. Using TaqMan real-time polymerase chain reaction we measured the quantitative associations between a subset of miRNAs identified on microarrays in primary tumors at diagnosis and cancer survival in a cohort of 104 HNSCC patients undergoing treatment with curative intent. The majority of miRNAs exhibiting altered expression in primary human HNSCC tumors (including miR-1, miR-133a, miR-205, and let-7d) show lower expression levels relative to normal adjacent tissue. In contrast, hsa-miR-21 is frequently overexpressed in human HNSCC tumors. Using univariate and multivariable statistical models we show that low levels of hsa-miR205 are significantly associated with loco-regional recurrence independent of disease severity at diagnosis and treatment. In addition, combined low levels of hsa-miR-205 and hsa-let-7d expression in HNSCC tumors are significantly associated with poor head and neck cancer survival Our results show that miRNA expression levels can be used as prognostic markers of head and neck cancer.
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Affiliation(s)
- Geoffrey Childs
- Department of Pathology, Albert Einstein College of Medicine, 1300 Morris Park Ave., Bronx, NY 10461, USA.
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Maguire M, Nield PC, Devling T, Jenkins RE, Park BK, Polański R, Vlatković N, Boyd MT. MDM2 regulates dihydrofolate reductase activity through monoubiquitination. Cancer Res 2008; 68:3232-42. [PMID: 18451149 DOI: 10.1158/0008-5472.can-07-5271] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
MDM2 is a ubiquitin ligase that is best known for its essential function in the negative regulation of p53. In addition, MDM2 expression is associated with tumor progression in a number of common cancers, and in some cases, this has been shown to be independent of p53 status. MDM2 has been shown to promote the degradation of a number of other proteins involved in the regulation of normal cell growth and proliferation, including MDM4 and RB1. Here, we describe the identification of a novel substrate for the MDM2 ubiquitin ligase: dihydrofolate reductase (DHFR). MDM2 binds directly to DHFR and catalyses its monoubiquitination and not its polyubiquitination. In addition, MDM2 expression reduces DHFR activity in a p53-independent manner, but has no effect upon the steady-state level of expression of DHFR. We show that changes in MDM2 expression alter folate metabolism in cells as evidenced by MDM2-dependent alteration in the sensitivity of cells to the antifolate drug methotrexate. Furthermore, we show that the ability of MDM2 to inhibit DHFR activity depends upon an intact MDM2 RING finger. Our studies provide for the first time a link between MDM2, an oncogene with a critical ubiquitin ligase activity and a vital one-carbon donor pathway involved in epigenetic regulation, and DNA metabolism, which has wide ranging implications for both cell biology and tumor development.
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Affiliation(s)
- Maria Maguire
- Division of Surgery and Oncology, University of Liverpool, Liverpool, United Kingdom
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Li Y, He L, Bruce A, Parihar K, Ingram A, Liu L, Tang D. p14ARF inhibits the growth of p53 deficient cells in a cell-specific manner. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2006; 1763:787-96. [PMID: 16764954 DOI: 10.1016/j.bbamcr.2006.04.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2005] [Revised: 03/24/2006] [Accepted: 04/25/2006] [Indexed: 12/27/2022]
Abstract
While p14(ARF) suppression of tumorigenesis in a p53-dependent manner is well studied, the mechanism by which p14(ARF) inhibits tumorigenesis independently of p53 remains elusive. A variety of factors have been reported to play a role in this latter process. We report here that p14(ARF) displays different effects on the anchorage-dependent and -independent growth of p53-null/Mdm2 wild type cells. p14(ARF) blocks both the anchorage-dependent and-independent (soft agar) proliferation of 293T and p53(-/-) HCT116, but not p53-null H1299 lung carcinoma cells. While p14(ARF) had no effect on the anchorage-dependent proliferation of p53(-/-) MEFs and Ras12V-transformed p53(-/-) MEFs, it inhibited the growth of Ras12V-transformed p53(-/-) MEFs in soft agar. Furthermore, ectopic expression of p14(ARF) did not lead to degradation of the E2F1 protein and did not result in the reduction of E2F1 activity detected by two E2F1 responsible promoters, Apaf1 and p14(ARF) promoter, in 293T, p53(-/-) HCT116, and H1299 cells. This is consistent with our observations that p14(ARF) did not result in G1 arrest, but induced apoptosis via Bax up-regulation. Taken together, our data demonstrate that the response of p53-null cells to ARF is cell type dependent and involves factors other than Mdm2 and E2F1.
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Affiliation(s)
- Yanxia Li
- Department of Medicine, Division of Nephrology, McMaster University, Hamilton, ON, Canada
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12
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Oleinik NV, Krupenko NI, Reuland SN, Krupenko SA. Leucovorin-induced resistance against FDH growth suppressor effects occurs through DHFR up-regulation. Biochem Pharmacol 2006; 72:256-66. [PMID: 16712799 DOI: 10.1016/j.bcp.2006.04.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2006] [Revised: 04/01/2006] [Accepted: 04/06/2006] [Indexed: 10/24/2022]
Abstract
10-Formyltetrahydrofolate dehydrogenase (FDH) converts 10-formyltetrahydrofolate to tetrahydrofolate (THF). Expression of the enzyme in FDH-deficient cancer cells induces cytotoxicity that can be reversed by supplementation with high concentrations of a reduced folate, 5-formyl-THF (leucovorin). In contrast, non-tumor cells are resistant to FDH. The present study was undertaken to investigate mechanisms that could protect cells against FDH suppressor effects. Using 10 microM leucovorin supplementation of FDH-sensitive A549 cells transfected for FDH expression, we selected clones that have acquired resistance against FDH. Resistant cells expressed high levels of FDH and were capable of growing after withdrawal of leucovorin. These cells, however, have increased doubling time due to prolonged S phase. They also have significantly increased levels of total folate pool and THF/5,10-methylene-THF pool while the level of 10-formyl-THF was two-fold lower than in parental FDH-sensitive cells. We have shown that the FDH-catalyzed reaction proceeds at about a three-fold slower rate at the ratio of 10-formyl-THF/THF corresponding to the resistant cells than at the ratio corresponding to parental sensitive cells, due to product inhibition (KI is 2.35 microM). FDH-resistant cells have strongly up-regulated dihydrofolate reductase (DHFR) that is proposed to be a mechanism for the alteration of folate pools and a key component of the acquired resistance. Elevation of DHFR in A549 cells by transient transfection decreased sensitivity to FDH toxicity and allowed selection of FDH-resistant clones. DHFR-induced repression of FDH catalysis could be an S phase-related metabolic adjustment that provides protection against FDH suppressor effects.
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Affiliation(s)
- Natalia V Oleinik
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 173 Ashley Avenue, P.O. Box 250509, Charleston, SC 29425, United States
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Gray T, Morrey EL, Gangadharan B, Sumter TF, Spychala J, Archer DR, Spencer HT. Enforced expression of cytosolic 5'-nucleotidase I confers resistance to nucleoside analogues in vitro but systemic chemotherapy toxicity precludes in vivo selection. Cancer Chemother Pharmacol 2005; 58:117-28. [PMID: 16362297 DOI: 10.1007/s00280-005-0156-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2005] [Accepted: 11/10/2005] [Indexed: 10/25/2022]
Abstract
PURPOSE Retroviral transfer of cDNA sequences that confer drug resistance can be used to protect against chemotherapy-induced hematopoietic toxicity and for the selective expansion of gene-modified cells. To successfully expand genetically engineered cells in vivo, an appropriate balance must be achieved between systemic toxicity induced by the selecting agent and the expansion of modified cells. METHOD In this study, we investigate retroviral transfer of cytosolic 5'-nucleotidase I (cN-I) for protection and selection of gene-modified cells when treated with 2-chloro-2'-deoxyadenosine (2-CdA) and 5-fluorouracil (5-FU) alone and in combination. We also attempt to design a treatment strategy for the potential in vivo selection of cN-I-modified cells by administering 5-FU to mice prior to 2-CdA treatment. RESULTS Our results show that cN-I can be transferred by recombinant retroviruses, and that enforced expression of cN-I protects murine fibroblast and hematopoietic progenitor cells from the cytotoxic effects of 2-CdA and/or 5-FU. Furthermore, we show that the combined administration of 5-FU and 2-CdA potentiates hematopoietic stem cell toxicity. However, the treatment also results in severe myelosuppression. CONCLUSION These results show that while cN-I provides both protective and selective benefits to gene-modified cells in vitro, selection requires a treatment strategy that is likely too toxic to consider cN-I as an in vivo selectable marker.
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Affiliation(s)
- Tasha Gray
- Division of Animal Resources, Emory University, 2015 Uppergate Drive, Room 420, Atlanta, GA 30322, USA
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