351
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Liu G, Sun Y, Ji P, Li X, Cogdell D, Yang D, Parker Kerrigan BC, Shmulevich I, Chen K, Sood AK, Xue F, Zhang W. MiR-506 suppresses proliferation and induces senescence by directly targeting the CDK4/6-FOXM1 axis in ovarian cancer. J Pathol 2014; 233:308-18. [PMID: 24604117 DOI: 10.1002/path.4348] [Citation(s) in RCA: 96] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 02/08/2014] [Accepted: 02/22/2014] [Indexed: 01/13/2023]
Abstract
Ovarian carcinoma is the most lethal gynaecological malignancy. Better understanding of the molecular pathogenesis of this disease and effective targeted therapies are needed to improve patient outcomes. MicroRNAs play important roles in cancer progression and have the potential for use as either therapeutic agents or targets. Studies in other cancers have suggested that miR-506 has anti-tumour activity, but its function has yet to be elucidated. We found that deregulation of miR-506 in ovarian carcinoma promotes an aggressive phenotype. Ectopic over-expression of miR-506 in ovarian cancer cells was sufficient to inhibit proliferation and to promote senescence. We also demonstrated that CDK4 and CDK6 are direct targets of miR-506, and that miR-506 can inhibit CDK4/6-FOXM1 signalling, which is activated in the majority of serous ovarian carcinomas. This newly recognized miR-506-CDK4/6-FOXM1 axis provides further insight into the pathogenesis of ovarian carcinoma and identifies a potential novel therapeutic agent.
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Affiliation(s)
- Guoyan Liu
- Department of Pathology, University of Texas MD Anderson Cancer Center, Houston, TX, USA; Department of Gynecology and Obstetrics, Tianjin Medical University General Hospital, People's Republic of China
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352
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Modulated expression of genes encoding estrogen metabolizing enzymes by G1-phase cyclin-dependent kinases 6 and 4 in human breast cancer cells. PLoS One 2014; 9:e97448. [PMID: 24848372 PMCID: PMC4029737 DOI: 10.1371/journal.pone.0097448] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Accepted: 04/19/2014] [Indexed: 02/06/2023] Open
Abstract
G1-phase cell cycle defects, such as alterations in cyclin D1 or cyclin-dependent kinase (cdk) levels, are seen in most tumors. For example, increased cyclin D1 and decreased cdk6 levels are seen in many human breast tumors. Overexpression of cdk6 in breast tumor cells in culture has been shown to suppress proliferation, unlike the growth stimulating effects of its close homolog, cdk4. In addition to directly affecting proliferation, alterations in cdk6 or cdk4 levels in breast tumor cells also differentially influence levels of numerous steroid metabolic enzymes (SMEs), including those involved in estrogen metabolism. Overexpression of cdk6 in tumor cell lines having low cdk6 resulted in decreased levels of mRNAs encoding aldo-keto reductase (AKR)1C1, AKR1C2 and AKR1C3, which are hydroxysteroid dehydrogenases (HSDs) involved in steroid hormone metabolism. In contrast, increasing cdk4 dramatically increased these transcript levels, especially those encoding AKR1C3, an enzyme that converts estrone to 17β-estradiol, a change that could result in a pro-estrogenic state favoring tumor growth. Effects on other estrogen metabolizing enzymes, including cytochrome P450 (CYP) 19 aromatase, 17β-HSD2, and CYP1B1 transcripts, were also observed. Interactions of cdk6 and cdk4, but not cyclin D1, with the promoter region of a cdk-regulated gene, 17β-HSD2, were detected. The results uncover a previously unsuspected link between the cell cycle and hormone metabolism and differential roles for cdk6 and cdk4 in a novel mechanism for pre-receptor control of steroid hormone action, with important implications for the origin and treatment of steroid hormone-dependent cancers.
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353
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Witkiewicz AK, Knudsen ES. Retinoblastoma tumor suppressor pathway in breast cancer: prognosis, precision medicine, and therapeutic interventions. Breast Cancer Res 2014; 16:207. [PMID: 25223380 PMCID: PMC4076637 DOI: 10.1186/bcr3652] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
A series of recent studies have demonstrated that the retinoblastoma tumor suppressor (RB) pathway plays a critical role in multiple clinically relevant aspects of breast cancer biology, spanning early stage lesions to targeted treatment of metastatic disease. In ductal carcinoma in situ, multiple groups have shown that dysregulation of the RB pathway is critically associated with recurrence and disease progression. Functional models have similarly illustrated key roles for RB in regulating epithelial–mesenchymal transition and other features contributing to aggressive disease. Invasive breast cancers are treated in distinct fashions, and heterogeneity within the RB pathway relates to prognosis and response to commonly used therapeutics. Luminal B breast cancers that have a poor prognosis amongst estrogen receptor-positive disease are defined based on the expression of RB-regulated genes. Such findings have led to clinical interventions that directly target the RB pathway through CDK4/6 inhibition which have promise in both estrogen receptor-positive and Her2-positive disease. In contrast, RB loss results in improved response to chemotherapy in triple-negative breast cancer, where ongoing research is attempting to define intrinsic vulnerabilities for targeted intervention. These findings support a wide-reaching impact of the RB pathway on disease that could be harnessed for improved clinical interventions.
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354
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Lou X, Zhang J, Liu S, Xu N, Liao DJ. The other side of the coin: the tumor-suppressive aspect of oncogenes and the oncogenic aspect of tumor-suppressive genes, such as those along the CCND-CDK4/6-RB axis. Cell Cycle 2014; 13:1677-93. [PMID: 24799665 DOI: 10.4161/cc.29082] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Although cancer-regulatory genes are dichotomized to oncogenes and tumor-suppressor gene s, in reality they can be oncogenic in one situation but tumor-suppressive in another. This dual-function nature, which sometimes hampers our understanding of tumor biology, has several manifestations: (1) Most canonically defined genes have multiple mRNAs, regulatory RNAs, protein isoforms, and posttranslational modifications; (2) Genes may interact at different levels, such as by forming chimeric RNAs or by forming different protein complexes; (3) Increased levels of tumor-suppressive genes in normal cells drive proliferation of cancer progenitor cells in the same organ or tissue by imposing compensatory proliferation pressure, which presents the dual-function nature as a cell-cell interaction. All these manifestations of dual functions can find examples in the genes along the CCND-CDK4/6-RB axis. The dual-function nature also underlies the heterogeneity of cancer cells. Gene-targeting chemotherapies, including that targets CDK4, are effective to some cancer cells but in the meantime may promote growth or progression of some others in the same patient. Redefining "gene" by considering each mRNA, regulatory RNA, protein isoform, and posttranslational modification from the same genomic locus as a "gene" may help in better understanding tumor biology and better selecting targets for different sub-populations of cancer cells in individual patients for personalized therapy.
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Affiliation(s)
- Xiaomin Lou
- CAS Key Laboratory of Genome Sciences and Information; Beijing Institute of Genomics; Chinese Academy of Sciences; Beijing, PR China
| | - Ju Zhang
- CAS Key Laboratory of Genome Sciences and Information; Beijing Institute of Genomics; Chinese Academy of Sciences; Beijing, PR China
| | - Siqi Liu
- CAS Key Laboratory of Genome Sciences and Information; Beijing Institute of Genomics; Chinese Academy of Sciences; Beijing, PR China
| | - Ningzhi Xu
- Laboratory of Cell and Molecular Biology; Cancer Institute; Chinese Academy of Medical Science; Beijing, PR China
| | - D Joshua Liao
- Hormel Institute; University of Minnesota; Austin, MN USA
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355
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Abstract
Unrestrained growth is the hallmark of cancer, and disrupted cell-cycle regulation is, therefore, common. CDK4 is the key regulator of the G1-S transition. In complex with cyclin D, CDK4 phosphorylates retinoblastoma protein (Rb) and drives cell-cycle progression, a process inhibited by p16. The p16-CDK4-cyclin D-Rb is aberrant in the majority of cancers and is, thus, a logical target for anticancer therapy. Previous attempts to block CDK4 with nonselective cyclin-dependent kinase (CDK) inhibitors led to toxicity and little efficacy. However, the recent development of selective CDK4 inhibitors launched the first successful efforts to target the pathway for cancer therapy. Three oral selective CDK4 inhibitors have entered clinical trials: palbociclib (PD0332991), LEE011, and LY2835219. CDK4 inhibitors have in vitro activity against a broad range of cancers and in patients have shown antitumor activity in breast cancer, lymphoma, sarcoma, and other tumors. Major efforts are under way to develop biomarkers of response, understand potential mechanisms of resistance, and develop rational combinations of CDK4 inhibitors with chemotherapy and other targeted drugs.
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Affiliation(s)
- Mark A Dickson
- Author's Affiliation: Department of Medicine, Memorial Sloan Kettering Cancer Center, Weill Cornell Medical College, New York, New York
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356
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Laine A, Westermarck J. Molecular pathways: harnessing E2F1 regulation for prosenescence therapy in p53-defective cancer cells. Clin Cancer Res 2014; 20:3644-50. [PMID: 24788101 DOI: 10.1158/1078-0432.ccr-13-1942] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Induction of terminal proliferation arrest, senescence, is important for in vivo tumor-suppressive function of p53. Moreover, p53-mutant cells are highly resistant to senescence induction by either oncogenic signaling during cellular transformation or in response to different therapies. Senescence resistance in p53-mutant cells has been attributed mostly to inhibition of the checkpoint function of p53 in response to senescence-inducing stress signals. Here, we review very recent evidence that offers an alternative explanation for senescence resistance in p53-defective cancer cells: p21-mediated E2F1 expression. We discuss the potential relevance of these findings for senescence-inducing therapies and highlight cyclin-dependent kinases (CDK) and mechanisms downstream of retinoblastoma protein (RB) as prospective prosenescence therapeutic targets. In particular, we discuss recent findings indicating an important role for the E2F1-CIP2A feedback loop in causing senescence resistance in p53-compromised cancer cells. We further propose that targeting of the E2F1-CIP2A feedback loop could provide a prosenescence therapeutic approach that is effective in both p53-deficient and RB-deficient cancer cells, which together constitute the great majority of all cancer cells. Diagnostic evaluation of the described senescence resistance mechanisms in human tumors might also be informative for patient stratification for already existing therapies.
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Affiliation(s)
- Anni Laine
- Authors' Affiliations: Turku Centre for Biotechnology, University of Turku and Åbo Akademi University; and
| | - Jukka Westermarck
- Authors' Affiliations: Turku Centre for Biotechnology, University of Turku and Åbo Akademi University; and Department of Pathology, University of Turku, Turku, Finland
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357
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Zhang CY, Bao W, Wang LH. Downregulation of p16(ink4a) inhibits cell proliferation and induces G1 cell cycle arrest in cervical cancer cells. Int J Mol Med 2014; 33:1577-85. [PMID: 24714974 DOI: 10.3892/ijmm.2014.1731] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Accepted: 03/28/2014] [Indexed: 11/05/2022] Open
Abstract
Studies have suggested that p16(ink4a) may be a surrogate biomarker for the diagnosis of cervical cancer; however, the function of p16(ink4a) in human cervical cancer cells remains largely unknown. Therefore, in this study, we aimed to investigate the role of p16(ink4a) in human cervical cancer cells. Immunocytochemistry was used to examine invasive squamous cell carcinoma and its precancerous lesions. p16(ink4a)-siRNA was transfected into SiHa and HeLa cells to deplete its expression. The cellular levels of p16(ink4a) mRNA and protein were detected by qRT-PCR and western blot analysis. Proliferation rates were assessed by methyl thiazolyl tetrazolium (MTT) and plate colony formation assays. Cellular migration and invasion ability were assessed by a wound healing assay and Transwell assay. Cellular apoptosis and the cell cycle were measured by flow cytometry. The protein levels of retinoblastoma (Rb), phosphorylated Rb (phospho-Rb), cyclin D1 and caspase-3 were determined by western blot analysis. The results revealed that p16(ink4a) was overexpressed in the cervical cancer and precancerous lesions (P<0.05). The downregulation of p16(ink4a) in the SiHa and HeLa cells inhibited their proliferation, migration and invasion. In the SiHa cells, p16(ink4a)-siRNA also induced G1 cell cycle arrest and apoptosis. Western blot analysis revealed that the downregulation of p16(ink4a) in the SiHa cells markedly induced caspase-3 activation and decreased cyclin D1 expression. These data suggest that the overexpression of p16(ink4a) appears to be useful in monitoring cervical precancerous lesions, which supports that the hypothesis that p16(ink4a) is a surrogate biomarker for the diagnosis of cervical cancer. The therapeutic targeting of overexpressed p16(ink4a) in the p16(ink4a)-cyclin-Rb pathway may be a useful strategy in the treatment of cervical cancer.
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Affiliation(s)
- Chu-Yue Zhang
- Department of Obstetrics and Gynecology, International Peace Maternity and Child Health Hospital of China Welfare Institute, Shanghai Jiao Tong University School of Medicine, Shanghai 200030, P.R. China
| | - Wei Bao
- Department of Obstetrics and Gynecology, International Peace Maternity and Child Health Hospital of China Welfare Institute, Shanghai Jiao Tong University School of Medicine, Shanghai 200030, P.R. China
| | - Li-Hua Wang
- Department of Obstetrics and Gynecology, International Peace Maternity and Child Health Hospital of China Welfare Institute, Shanghai Jiao Tong University School of Medicine, Shanghai 200030, P.R. China
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358
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Imai Y, Takahashi A, Hanyu A, Hori S, Sato S, Naka K, Hirao A, Ohtani N, Hara E. Crosstalk between the Rb pathway and AKT signaling forms a quiescence-senescence switch. Cell Rep 2014; 7:194-207. [PMID: 24703840 DOI: 10.1016/j.celrep.2014.03.006] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2013] [Revised: 01/13/2014] [Accepted: 03/03/2014] [Indexed: 12/14/2022] Open
Abstract
Cell-cycle arrest in quiescence and senescence is largely orchestrated by the retinoblastoma (Rb) tumor-suppressor pathway, but the mechanisms underlying the quiescence-senescence switch remain unclear. Here, we show that the crosstalk between the Rb-AKT-signaling pathways forms this switch by controlling the overlapping functions of FoxO3a and FoxM1 transcription factors in cultured fibroblasts. In the absence of mitogenic signals, although FoxM1 expression is repressed by the Rb pathway, FoxO3a prevents reactive oxygen species (ROS) production by maintaining SOD2 expression, leading to quiescence. However, if the Rb pathway is activated in the presence of mitogenic signals, FoxO3a is also inactivated by AKT, thus reducing SOD2 expression and consequently allowing ROS production. This situation elicits senescence through irreparable DNA damage. We demonstrate that this pathway operates in mouse liver, indicating that this machinery may contribute more broadly to tissue homeostasis in vivo.
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Affiliation(s)
- Yoshinori Imai
- Division of Cancer Biology, The Cancer Institute, Japanese Foundation for Cancer Research, Koto-ku, Tokyo 135-8550, Japan; Graduate School of Biomedical Science, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo 113-8510, Japan
| | - Akiko Takahashi
- Division of Cancer Biology, The Cancer Institute, Japanese Foundation for Cancer Research, Koto-ku, Tokyo 135-8550, Japan
| | - Aki Hanyu
- Division of Cancer Biology, The Cancer Institute, Japanese Foundation for Cancer Research, Koto-ku, Tokyo 135-8550, Japan
| | - Satoshi Hori
- Division of Cancer Biology, The Cancer Institute, Japanese Foundation for Cancer Research, Koto-ku, Tokyo 135-8550, Japan
| | - Seidai Sato
- Division of Cancer Biology, The Cancer Institute, Japanese Foundation for Cancer Research, Koto-ku, Tokyo 135-8550, Japan
| | - Kazuhito Naka
- Cancer Research Institute, Kanazawa University, Kanazawa 920-1192, Japan
| | - Atsushi Hirao
- Cancer Research Institute, Kanazawa University, Kanazawa 920-1192, Japan
| | - Naoko Ohtani
- Division of Cancer Biology, The Cancer Institute, Japanese Foundation for Cancer Research, Koto-ku, Tokyo 135-8550, Japan; PRESTO, Japan Science Technology Agency, Saitama 332-0012, Japan
| | - Eiji Hara
- Division of Cancer Biology, The Cancer Institute, Japanese Foundation for Cancer Research, Koto-ku, Tokyo 135-8550, Japan; CREST, Japan Science Technology Agency, Saitama 332-0012, Japan.
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359
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Lu Y, Wu Y, Feng X, Shen R, Wang JH, Fallahi M, Li W, Yang C, Hankey W, Zhao W, Ganju RK, Li MO, Cleveland JL, Zou X. CDK4 deficiency promotes genomic instability and enhances Myc-driven lymphomagenesis. J Clin Invest 2014; 124:1672-84. [PMID: 24614102 DOI: 10.1172/jci63139] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Accepted: 01/10/2014] [Indexed: 12/13/2022] Open
Abstract
The G1 kinase CDK4 is amplified or overexpressed in some human tumors and promotes tumorigenesis by inhibiting known tumor suppressors. Here, we report that CDK4 deficiency markedly accelerated lymphoma development in the Eμ-Myc transgenic mouse model of B lymphoma and that silencing or loss of CDK4 augmented the tumorigenic potential of Myc-driven mouse and human B cell lymphoma in transplant models. Accelerated disease in CDK4-deficient Eμ-Myc transgenic mice was associated with rampant genomic instability that was provoked by dysregulation of a FOXO1/RAG1/RAG2 pathway. Specifically, CDK4 phosphorylated and inactivated FOXO1, which prevented FOXO1-dependent induction of Rag1 and Rag2 transcription. CDK4-deficient Eμ-Myc B cells had high levels of the active form of FOXO1 and elevated RAG1 and RAG2. Furthermore, overexpression of RAG1 and RAG2 accelerated lymphoma development in a transplant model, with RAG1/2-expressing tumors exhibiting hallmarks of genomic instability. Evaluation of human tumor samples revealed that CDK4 expression was markedly suppressed, while FOXO1 expression was elevated, in several subtypes of human non-Hodgkin B cell lymphoma. Collectively, these findings establish a context-specific tumor suppressor function for CDK4 that prevents genomic instability, which contributes to B cell lymphoma. Furthermore, our data suggest that targeting CDK4 may increase the risk for the development and/or progression of lymphoma.
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360
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Haq R, Fisher DE, Widlund HR. Molecular pathways: BRAF induces bioenergetic adaptation by attenuating oxidative phosphorylation. Clin Cancer Res 2014; 20:2257-63. [PMID: 24610826 DOI: 10.1158/1078-0432.ccr-13-0898] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Cancers acquire mutations in cooperating pathways that sustain their growth and survival. To support continued proliferation, tumor cells adapt their metabolism to balance energy production with their augmented biosynthetic needs. Although most normal differentiated cells use mitochondrial oxidative phosphorylation (OXPHOS) as the bioenergetic source, cancer cells have been proposed to rely principally on cytoplasmic glycolysis. The molecular basis for this shift, termed the Warburg effect, is the subject of intense investigation, because mechanistic understanding may lead to novel approaches to target the altered metabolism of cancer cells. Recently, mutations BRAF(V600E) have emerged as a major regulator of metabolic homeostasis. Melanoma cells may use a metabolic shift to circumvent BRAF(V600E)-induced senescence though limiting their reliance on OXPHOS and promote proliferation. Furthermore, BRAF(V600E) acts to suppress expression of the melanocyte master regulator microphthalmia-associated transcription factor (MITF) and the mitochondrial biogenesis coactivator PGC1α. Accordingly, therapeutic inhibition of BRAF(V600E) reverses metabolic reprogramming in melanoma cells and elevates OXPHOS through increased MITF-PGC1α levels. BRAF-targeted drugs modulate the metabolic state of malignant melanoma cells, and counteracting these adaptive responses using pharmacologic agents may prove useful in combinatorial therapeutic strategies. Clin Cancer Res; 20(9); 2257-63. ©2014 AACR.
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Affiliation(s)
- Rizwan Haq
- Authors' Affiliations: Massachusetts General Hospital, Department of Dermatology, Cutaneous Biology Research Center, Harvard Medical School, Charlestown; Center for Melanoma, Massachusetts General Hospital Cancer Center; and Brigham and Women's Hospital, Department of Dermatology, Harvard Skin Diseases Research Center, Harvard Medical School, Boston, Massachusetts
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361
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Schimmel J, Eifler K, Sigurðsson JO, Cuijpers SAG, Hendriks IA, Verlaan-de Vries M, Kelstrup CD, Francavilla C, Medema RH, Olsen JV, Vertegaal ACO. Uncovering SUMOylation dynamics during cell-cycle progression reveals FoxM1 as a key mitotic SUMO target protein. Mol Cell 2014; 53:1053-66. [PMID: 24582501 DOI: 10.1016/j.molcel.2014.02.001] [Citation(s) in RCA: 141] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Revised: 12/23/2013] [Accepted: 01/24/2014] [Indexed: 12/25/2022]
Abstract
Loss of small ubiquitin-like modification (SUMOylation) in mice causes genomic instability due to the missegregation of chromosomes. Currently, little is known about the identity of relevant SUMO target proteins that are involved in this process and about global SUMOylation dynamics during cell-cycle progression. We performed a large-scale quantitative proteomics screen to address this and identified 593 proteins to be SUMO-2 modified, including the Forkhead box transcription factor M1 (FoxM1), a key regulator of cell-cycle progression and chromosome segregation. SUMOylation of FoxM1 peaks during G2 and M phase, when FoxM1 transcriptional activity is required. We found that a SUMOylation-deficient FoxM1 mutant was less active compared to wild-type FoxM1, implying that SUMOylation of the protein enhances its transcriptional activity. Mechanistically, SUMOylation blocks the dimerization of FoxM1, thereby relieving FoxM1 autorepression. Cells deficient for FoxM1 SUMOylation showed increased levels of polyploidy. Our findings contribute to understanding the role of SUMOylation during cell-cycle progression.
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Affiliation(s)
- Joost Schimmel
- Department of Molecular Cell Biology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden, the Netherlands
| | - Karolin Eifler
- Department of Molecular Cell Biology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden, the Netherlands
| | - Jón Otti Sigurðsson
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark
| | - Sabine A G Cuijpers
- Department of Molecular Cell Biology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden, the Netherlands
| | - Ivo A Hendriks
- Department of Molecular Cell Biology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden, the Netherlands
| | - Matty Verlaan-de Vries
- Department of Molecular Cell Biology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden, the Netherlands
| | - Christian D Kelstrup
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark
| | - Chiara Francavilla
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark
| | - René H Medema
- Department of Cell Biology, Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, the Netherlands
| | - Jesper V Olsen
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark.
| | - Alfred C O Vertegaal
- Department of Molecular Cell Biology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden, the Netherlands.
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362
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Miller DM, Flaherty KT. Cyclin-dependent kinases as therapeutic targets in melanoma. Pigment Cell Melanoma Res 2014; 27:351-65. [PMID: 24405945 DOI: 10.1111/pcmr.12211] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Accepted: 01/07/2014] [Indexed: 12/11/2022]
Abstract
Decades of scientific insights have led to a recent expansion of the therapeutic menu for melanoma. Despite these advances, the current targeted therapies and immune checkpoint agents continue to yield suboptimal response and cure rates. Hitherto, the most effective targeted therapy strategies have centered on effectors in the mitogen-activated protein kinase (MAPK) pathway. This review focuses on the emerging evidence of combinatorial approaches targeting both MAPK signaling and dysregulations in cell-cycle checkpoints. We discuss the prospects and limitations of utilizing strategies that promote cellular senescence, such as inhibition of the interphase cyclin-dependent kinases (CDKs) and highlight the current state of CDK drug discovery in melanoma.
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Affiliation(s)
- David M Miller
- Department of Dermatology, Columbia University Medical Center, New York, NY, USA
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363
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Dok R, Kalev P, Van Limbergen EJ, Asbagh LA, Vázquez I, Hauben E, Sablina A, Nuyts S. p16INK4a impairs homologous recombination-mediated DNA repair in human papillomavirus-positive head and neck tumors. Cancer Res 2014; 74:1739-51. [PMID: 24473065 DOI: 10.1158/0008-5472.can-13-2479] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The p16INK4a protein is a principal cyclin-dependent kinase inhibitor that decelerates the cell cycle. Abnormally high levels of p16INK4a are commonly observed in human papillomavirus (HPV)-positive head and neck squamous cell carcinomas (HNSCC). We and others found that p16INK4a overexpression is associated with improved therapy response and survival of patients with HNSCC treated with radiotherapy. However, the functional role of p16INK4a in HNSCC remains unexplored. Our results implicate p16INK4a in regulation of homologous recombination-mediated DNA damage response independently from its role in control of the cell cycle. We found that expression of p16INK4a dramatically affects radiation sensitivity of HNSCC cells. p16INK4a overexpression impairs the recruitment of RAD51 to the site of DNA damage in HPV-positive cells by downregulating of cyclin D1 protein expression. Consistent with the in vitro findings, immunostaining of HNSCC patient samples revealed that high levels p16INK4a expression significantly correlated with decreased cyclin D1 expression. In summary, these findings reveal an unexpected function of p16INK4a in homologous recombination-mediated DNA repair response and imply p16INK4a status as an independent marker to predict response of patients with HNSCC to radiotherapy.
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Affiliation(s)
- Rüveyda Dok
- Authors' Affiliations: Department of Oncology, Laboratory of Experimental Radiotherapy; Department of Human Genetics, Laboratory for Mechanisms of Cell Transformation; Department of Oncology, Molecular and Digestive Oncology; Department of Imaging and Pathology, Translational Cell and Tissue Research, KU Leuven, University of Leuven; VIB Center for the Biology of Disease; Departments of Radiation Oncology; and Pathology, UZ Leuven, Leuven, Belgium
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364
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Handschick K, Beuerlein K, Jurida L, Bartkuhn M, Müller H, Soelch J, Weber A, Dittrich-Breiholz O, Schneider H, Scharfe M, Jarek M, Stellzig J, Schmitz ML, Kracht M. Cyclin-dependent kinase 6 is a chromatin-bound cofactor for NF-κB-dependent gene expression. Mol Cell 2014; 53:193-208. [PMID: 24389100 DOI: 10.1016/j.molcel.2013.12.002] [Citation(s) in RCA: 109] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Revised: 07/09/2013] [Accepted: 11/26/2013] [Indexed: 12/11/2022]
Abstract
Given the intimate link between inflammation and dysregulated cell proliferation in cancer, we investigated cytokine-triggered gene expression in different cell cycle stages. Transcriptome analysis revealed that G1 release through cyclin-dependent kinase 6 (CDK6) and CDK4 primes and cooperates with the cytokine-driven gene response. CDK6 physically and functionally interacts with the NF-κB subunit p65 in the nucleus and is found at promoters of many transcriptionally active NF-κB target genes. CDK6 recruitment to distinct chromatin regions of inflammatory genes was essential for proper loading of p65 to its cognate binding sites and for the function of p65 coactivators, such as TRIP6. Furthermore, cytokine-inducible nuclear translocation and chromatin association of CDK6 depends on the kinase activity of TAK1 and p38. These results have widespread biological implications, as aberrant CDK6 expression or activation that is frequently observed in human tumors modulates NF-κB to shape the cytokine and chemokine repertoires in chronic inflammation and cancer.
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Affiliation(s)
- Katja Handschick
- Rudolf-Buchheim-Institute of Pharmacology, Justus-Liebig-University Giessen, 35392 Giessen, Germany
| | - Knut Beuerlein
- Rudolf-Buchheim-Institute of Pharmacology, Justus-Liebig-University Giessen, 35392 Giessen, Germany
| | - Liane Jurida
- Rudolf-Buchheim-Institute of Pharmacology, Justus-Liebig-University Giessen, 35392 Giessen, Germany
| | - Marek Bartkuhn
- Institute for Genetics, Justus-Liebig-University Giessen, 35392 Giessen, Germany
| | - Helmut Müller
- Rudolf-Buchheim-Institute of Pharmacology, Justus-Liebig-University Giessen, 35392 Giessen, Germany
| | - Johanna Soelch
- Rudolf-Buchheim-Institute of Pharmacology, Justus-Liebig-University Giessen, 35392 Giessen, Germany
| | - Axel Weber
- Rudolf-Buchheim-Institute of Pharmacology, Justus-Liebig-University Giessen, 35392 Giessen, Germany
| | | | - Heike Schneider
- Institute of Physiological Chemistry, Medical School Hannover, 30625 Hannover, Germany
| | - Maren Scharfe
- Helmholtz Centre for Infection Research, 38124 Braunschweig, Germany
| | - Michael Jarek
- Helmholtz Centre for Infection Research, 38124 Braunschweig, Germany
| | - Julia Stellzig
- Institute of Biochemistry, Justus-Liebig-University Giessen, 35392 Giessen, Germany
| | - M Lienhard Schmitz
- Institute of Biochemistry, Justus-Liebig-University Giessen, 35392 Giessen, Germany
| | - Michael Kracht
- Rudolf-Buchheim-Institute of Pharmacology, Justus-Liebig-University Giessen, 35392 Giessen, Germany.
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365
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Xue J, Lin X, Chiu WT, Chen YH, Yu G, Liu M, Feng XH, Sawaya R, Medema RH, Hung MC, Huang S. Sustained activation of SMAD3/SMAD4 by FOXM1 promotes TGF-β-dependent cancer metastasis. J Clin Invest 2014; 124:564-79. [PMID: 24382352 DOI: 10.1172/jci71104] [Citation(s) in RCA: 143] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Accepted: 10/18/2013] [Indexed: 12/22/2022] Open
Abstract
A key feature of TGF-β signaling activation in cancer cells is the sustained activation of SMAD complexes in the nucleus; however, the drivers of SMAD activation are poorly defined. Here, using human and mouse breast cancer cell lines, we found that oncogene forkhead box M1 (FOXM1) interacts with SMAD3 to sustain activation of the SMAD3/SMAD4 complex in the nucleus. FOXM1 prevented the E3 ubiquitin-protein ligase transcriptional intermediary factor 1 γ (TIF1γ) from binding SMAD3 and monoubiquitinating SMAD4, which stabilized the SMAD3/SMAD4 complex. Loss of FOXM1 abolished TGF-β-induced SMAD3/SMAD4 formation. Moreover, the interaction of FOXM1 and SMAD3 promoted TGF-β/SMAD3-mediated transcriptional activity and target gene expression. We found that FOXM1/SMAD3 interaction was required for TGF-β-induced breast cancer invasion, which was the result of SMAD3/SMAD4-dependent upregulation of the transcription factor SLUG. Importantly, the function of FOXM1 in TGF-β-induced invasion was not dependent on FOXM1's transcriptional activity. Knockdown of SMAD3 diminished FOXM1-induced metastasis. Furthermore, FOXM1 levels correlated with activated TGF-β signaling and metastasis in human breast cancer specimens. Together, our data indicate that FOXM1 promotes breast cancer metastasis by increasing nuclear retention of SMAD3 and identify crosstalk between FOXM1 and TGF-β/SMAD3 pathways. This study highlights the critical interaction of FOXM1 and SMAD3 for controlling TGF-β signaling during metastasis.
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366
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Stressing the cell cycle in senescence and aging. Curr Opin Cell Biol 2013; 25:765-71. [DOI: 10.1016/j.ceb.2013.07.005] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Revised: 07/08/2013] [Accepted: 07/08/2013] [Indexed: 12/31/2022]
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367
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Meierjohann S. Oxidative stress in melanocyte senescence and melanoma transformation. Eur J Cell Biol 2013; 93:36-41. [PMID: 24342719 DOI: 10.1016/j.ejcb.2013.11.005] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2013] [Revised: 11/15/2013] [Accepted: 11/15/2013] [Indexed: 10/26/2022] Open
Abstract
Melanoma is a severe type of skin cancer with a high metastasis potential and poor survival rates once metastasized. The causes of melanoma formation are multifactorial and not fully understood. Several signaling cascades such as the RAS/RAF/ERK1/2 pathway, the PI3K/AKT pathway, RAC1 and NF-κB are involved in melanoma initiation and progression. Reactive oxygen species (ROS) are induced by these signal transduction cascades, and they play a fundamental role in melanomagenic processes. Cells derived from the melanocytic lineage are particularly sensitive to an increase in ROS, and thus, melanoma cells rely on efficient antioxidant measures. This review summarizes the causes and consequences of ROS generation in melanocytes and melanoma and discusses the potential of pro-oxidant therapy in melanoma treatment.
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Affiliation(s)
- Svenja Meierjohann
- University of Wurzburg, Department of Physiological Chemistry I, Biocenter, Am Hubland, 97074, Wurzburg, Germany; Comprehensive Cancer Center Mainfranken, University Clinic Würzburg, 97078, Würzburg, Germany.
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368
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Wierstra I. The transcription factor FOXM1 (Forkhead box M1): proliferation-specific expression, transcription factor function, target genes, mouse models, and normal biological roles. Adv Cancer Res 2013; 118:97-398. [PMID: 23768511 DOI: 10.1016/b978-0-12-407173-5.00004-2] [Citation(s) in RCA: 127] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
FOXM1 (Forkhead box M1) is a typical proliferation-associated transcription factor, which stimulates cell proliferation and exhibits a proliferation-specific expression pattern. Accordingly, both the expression and the transcriptional activity of FOXM1 are increased by proliferation signals, but decreased by antiproliferation signals, including the positive and negative regulation by protooncoproteins or tumor suppressors, respectively. FOXM1 stimulates cell cycle progression by promoting the entry into S-phase and M-phase. Moreover, FOXM1 is required for proper execution of mitosis. Accordingly, FOXM1 regulates the expression of genes, whose products control G1/S-transition, S-phase progression, G2/M-transition, and M-phase progression. Additionally, FOXM1 target genes encode proteins with functions in the execution of DNA replication and mitosis. FOXM1 is a transcriptional activator with a forkhead domain as DNA binding domain and with a very strong acidic transactivation domain. However, wild-type FOXM1 is (almost) inactive because the transactivation domain is repressed by three inhibitory domains. Inactive FOXM1 can be converted into a very potent transactivator by activating signals, which release the transactivation domain from its inhibition by the inhibitory domains. FOXM1 is essential for embryonic development and the foxm1 knockout is embryonically lethal. In adults, FOXM1 is important for tissue repair after injury. FOXM1 prevents premature senescence and interferes with contact inhibition. FOXM1 plays a role for maintenance of stem cell pluripotency and for self-renewal capacity of stem cells. The functions of FOXM1 in prevention of polyploidy and aneuploidy and in homologous recombination repair of DNA-double-strand breaks suggest an importance of FOXM1 for the maintenance of genomic stability and chromosomal integrity.
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369
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Kohrt D, Crary J, Zimmer M, Patrick AN, Ford HL, Hinds PW, Grossel MJ. CDK6 binds and promotes the degradation of the EYA2 protein. Cell Cycle 2013; 13:62-71. [PMID: 24196439 PMCID: PMC3925736 DOI: 10.4161/cc.26755] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Cyclin-dependent kinase 6 (Cdk6) is a D-Cyclin-activated kinase that is directly involved in driving the cell cycle through inactivation of pRB in G1 phase. Increasingly, evidence suggests that CDK6, while directly driving the cell cycle, may only be essential for proliferation of specialized cell types, agreeing with the notion that CDK6 also plays an important role in differentiation. Here, evidence is presented that CDK6 binds to and promotes degradation of the EYA2 protein. The EYA proteins are a family of proteins that activate genes essential for the development of multiple organs, regulate cell proliferation, and are misregulated in several types of cancer. This interaction suggests that CDK6 regulates EYA2 activity, a mechanism that could be important in development and in cancer.
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Affiliation(s)
- Dawn Kohrt
- Department of Biology; Connecticut College; New London, CT USA
| | - Jennifer Crary
- Department of Biology; Connecticut College; New London, CT USA; Department of Developmental, Molecular, and Chemical Biology; Tufts University School of Medicine, and Molecular Oncology Research Institute; Tufts Medical Center; Boston, MA USA
| | - Marc Zimmer
- Department of Chemistry; Connecticut College; New London, CT USA
| | - Aaron N Patrick
- Department of Pharmacology; University of Colorado School of Medicine; Aurora, CO USA
| | - Heide L Ford
- Department of Pharmacology; University of Colorado School of Medicine; Aurora, CO USA
| | - Philip W Hinds
- Department of Developmental, Molecular, and Chemical Biology; Tufts University School of Medicine, and Molecular Oncology Research Institute; Tufts Medical Center; Boston, MA USA
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370
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Barton KL, Misuraca K, Cordero F, Dobrikova E, Min HD, Gromeier M, Kirsch DG, Becher OJ. PD-0332991, a CDK4/6 inhibitor, significantly prolongs survival in a genetically engineered mouse model of brainstem glioma. PLoS One 2013; 8:e77639. [PMID: 24098593 PMCID: PMC3788718 DOI: 10.1371/journal.pone.0077639] [Citation(s) in RCA: 123] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Accepted: 09/13/2013] [Indexed: 12/20/2022] Open
Abstract
Diffuse intrinsic pontine glioma (DIPG) is an incurable tumor that arises in the brainstem of children. To date there is not a single approved drug to effectively treat these tumors and thus novel therapies are desperately needed. Recent studies suggest that a significant fraction of these tumors contain alterations in cell cycle regulatory genes including amplification of the D-type cyclins and CDK4/6, and less commonly, loss of Ink4a-ARF leading to aberrant cell proliferation. In this study, we evaluated the therapeutic approach of targeting the cyclin-CDK-Retinoblastoma (Rb) pathway in a genetically engineered PDGF-B-driven brainstem glioma (BSG) mouse model. We found that PD-0332991 (PD), a CDK4/6 inhibitor, induces cell-cycle arrest in our PDGF-B; Ink4a-ARF deficient model both in vitro and in vivo. By contrast, the PDGF-B; p53 deficient model was mostly resistant to treatment with PD. We noted that a 7-day treatment course with PD significantly prolonged survival by 12% in the PDGF-B; Ink4a-ARF deficient BSG model. Furthermore, a single dose of 10 Gy radiation therapy (RT) followed by 7 days of treatment with PD increased the survival by 19% in comparison to RT alone. These findings provide the rationale for evaluating PD in children with Ink4a-ARF deficient gliomas.
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Affiliation(s)
- Kelly L. Barton
- Department of Pediatrics, Duke University, Durham, North Carolina, United States of America
- Preston Robert Tisch Brain Tumor Center, Duke University, Durham, North Carolina, United States of America
| | - Katherine Misuraca
- Graduate Program in Molecular Cancer Biology, Duke University, Durham, North Carolina, United States of America
| | - Francisco Cordero
- Department of Pediatrics, Duke University, Durham, North Carolina, United States of America
- Department of Pathology, Duke University, Durham, North Carolina, United States of America
- Preston Robert Tisch Brain Tumor Center, Duke University, Durham, North Carolina, United States of America
| | - Elena Dobrikova
- Department of Surgery, Duke University, Durham, North Carolina, United States of America
| | - Hooney D. Min
- Department of Radiation Oncology, Duke University, Durham, North Carolina, United States of America
| | - Matthias Gromeier
- Department of Surgery, Duke University, Durham, North Carolina, United States of America
| | - David G. Kirsch
- Department of Radiation Oncology, Duke University, Durham, North Carolina, United States of America
- Department of Pharmacology and Cancer Biology, Duke University, Durham, North Carolina, United States of America
| | - Oren J. Becher
- Department of Pediatrics, Duke University, Durham, North Carolina, United States of America
- Department of Pathology, Duke University, Durham, North Carolina, United States of America
- Preston Robert Tisch Brain Tumor Center, Duke University, Durham, North Carolina, United States of America
- * E-mail:
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371
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372
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Tumor suppressor p16INK4A is necessary for survival of cervical carcinoma cell lines. Proc Natl Acad Sci U S A 2013; 110:16175-80. [PMID: 24046371 DOI: 10.1073/pnas.1310432110] [Citation(s) in RCA: 123] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The tumor suppressor p16(INK4A) inhibits formation of enzymatically active complexes of cyclin-dependent kinases 4 and 6 (CDK4/6) with D-type cyclins. Oncogenic stress induces p16(INK4A) expression, which in turn triggers cellular senescence through activation of the retinoblastoma tumor suppressor. Subversion of oncogene-induced senescence is a key step during cancer development, and many tumors have lost p16(INK4A) activity by mutation or epigenetic silencing. Human papillomavirus (HPV)-associated tumors express high levels of p16(INK4A) in response to E7 oncoprotein expression. Induction of p16(INK4A) expression is not a consequence of retinoblastoma tumor suppressor inactivation but is triggered by a cellular senescence response and is mediated by epigenetic derepression through the H3K27-specific demethylase (KDM)6B. HPV E7 expression causes an acute dependence on KDM6B expression for cell survival. The p16(INK4A) tumor suppressor is a critical KDM6B downstream transcriptional target and its expression is critical for cell survival. This oncogenic p16(INK4A) activity depends on inhibition of CDK4/CDK6, suggesting that in cervical cancer cells where retinoblastoma tumor suppressor is inactivated, CDK4/CDK6 activity needs to be inhibited in order for cells to survive. Finally, we note that HPV E7 expression creates a unique cellular vulnerability to small-molecule KDM6A/B inhibitors.
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373
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Rader J, Russell MR, Hart LS, Nakazawa MS, Belcastro LT, Martinez D, Li Y, Carpenter EL, Attiyeh EF, Diskin SJ, Kim S, Parasuraman S, Caponigro G, Schnepp RW, Wood AC, Pawel B, Cole KA, Maris JM. Dual CDK4/CDK6 inhibition induces cell-cycle arrest and senescence in neuroblastoma. Clin Cancer Res 2013; 19:6173-82. [PMID: 24045179 DOI: 10.1158/1078-0432.ccr-13-1675] [Citation(s) in RCA: 284] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
PURPOSE Neuroblastoma is a pediatric cancer that continues to exact significant morbidity and mortality. Recently, a number of cell-cycle proteins, particularly those within the Cyclin D/CDK4/CDK6/RB network, have been shown to exert oncogenic roles in neuroblastoma, suggesting that their therapeutic exploitation might improve patient outcomes. EXPERIMENTAL PROCEDURES We evaluated the effect of dual CDK4/CDK6 inhibition on neuroblastoma viability using LEE011 (Novartis Oncology), a highly specific CDK4/6 inhibitor. RESULTS Treatment with LEE011 significantly reduced proliferation in 12 of 17 human neuroblastoma-derived cell lines by inducing cytostasis at nanomolar concentrations (mean IC50 = 307 ± 68 nmol/L in sensitive lines). LEE011 caused cell-cycle arrest and cellular senescence that was attributed to dose-dependent decreases in phosphorylated RB and FOXM1, respectively. In addition, responsiveness of neuroblastoma xenografts to LEE011 translated to the in vivo setting in that there was a direct correlation of in vitro IC50 values with degree of subcutaneous xenograft growth delay. Although our data indicate that neuroblastomas sensitive to LEE011 were more likely to contain genomic amplification of MYCN (P = 0.01), the identification of additional clinically accessible biomarkers is of high importance. CONCLUSIONS Taken together, our data show that LEE011 is active in a large subset of neuroblastoma cell line and xenograft models, and supports the clinical development of this CDK4/6 inhibitor as a therapy for patients with this disease. Clin Cancer Res; 19(22); 6173-82. ©2013 AACR.
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Affiliation(s)
- Julieann Rader
- Authors' Affiliations: Division of Oncology and Center for Childhood Cancer Research; Division of Pathology, Children's Hospital of Philadelphia; Department of Pediatrics; Abramson Family Cancer Research Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania; and Novartis Institutes for Biomedical Research, Cambridge, Massachusetts
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374
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Kollmann K, Heller G, Schneckenleithner C, Warsch W, Scheicher R, Ott R, Schäfer M, Fajmann S, Schlederer M, Schiefer AI, Reichart U, Mayerhofer M, Hoeller C, Zöchbauer-Müller S, Kerjaschki D, Bock C, Kenner L, Hoefler G, Freissmuth M, Green A, Moriggl R, Busslinger M, Malumbres M, Sexl V. A kinase-independent function of CDK6 links the cell cycle to tumor angiogenesis. Cancer Cell 2013; 24:167-81. [PMID: 23948297 PMCID: PMC3743049 DOI: 10.1016/j.ccr.2013.07.012] [Citation(s) in RCA: 203] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2012] [Revised: 05/17/2013] [Accepted: 07/22/2013] [Indexed: 12/20/2022]
Abstract
In contrast to its close homolog CDK4, the cell cycle kinase CDK6 is expressed at high levels in lymphoid malignancies. In a model for p185BCR-ABL+ B-acute lymphoid leukemia, we show that CDK6 is part of a transcription complex that induces the expression of the tumor suppressor p16INK4a and the pro-angiogenic factor VEGF-A. This function is independent of CDK6's kinase activity. High CDK6 expression thus suppresses proliferation by upregulating p16INK4a, providing an internal safeguard. However, in the absence of p16INK4a, CDK6 can exert its full tumor-promoting function by enhancing proliferation and stimulating angiogenesis. The finding that CDK6 connects cell-cycle progression to angiogenesis confirms CDK6's central role in hematopoietic malignancies and could underlie the selection pressure to upregulate CDK6 and silence p16INK4a.
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Affiliation(s)
- Karoline Kollmann
- Institute of Pharmacology and Toxicology, University of Veterinary Medicine Vienna, 1210 Vienna, Austria
| | - Gerwin Heller
- Clinical Division of Oncology, Department of Medicine I, Comprehensive Cancer Center, Medical University of Vienna, 1090 Vienna, Austria
| | | | - Wolfgang Warsch
- Institute of Pharmacology and Toxicology, University of Veterinary Medicine Vienna, 1210 Vienna, Austria
| | - Ruth Scheicher
- Institute of Pharmacology and Toxicology, University of Veterinary Medicine Vienna, 1210 Vienna, Austria
| | - Rene G. Ott
- Institute of Pharmacology, Center of Biomolecular Medicine and Pharmacology, Medical University of Vienna, 1090 Vienna, Austria
| | - Markus Schäfer
- Research Institute of Molecular Pathology, Vienna Biocenter, 1030 Vienna, Austria
| | - Sabine Fajmann
- Institute of Pharmacology and Toxicology, University of Veterinary Medicine Vienna, 1210 Vienna, Austria
| | - Michaela Schlederer
- Department of Clinical Pathology, Medical University of Vienna, 1090 Vienna, Austria
| | - Ana-Iris Schiefer
- Department of Clinical Pathology, Medical University of Vienna, 1090 Vienna, Austria
| | - Ursula Reichart
- Institute of Animal Breeding and Genetics, University of Veterinary Medicine Vienna, 1210 Vienna, Austria
| | - Matthias Mayerhofer
- Department of Laboratory Medicine, Medical University of Vienna, 1090 Vienna, Austria
| | - Christoph Hoeller
- Department of Dermatology, Medical University of Vienna, 1090 Vienna, Austria
| | - Sabine Zöchbauer-Müller
- Clinical Division of Oncology, Department of Medicine I, Comprehensive Cancer Center, Medical University of Vienna, 1090 Vienna, Austria
| | - Dontscho Kerjaschki
- Department of Clinical Pathology, Medical University of Vienna, 1090 Vienna, Austria
| | - Christoph Bock
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, 1090 Vienna, Austria
| | - Lukas Kenner
- Ludwig Boltzmann Institute for Cancer Research, 1090 Vienna, Austria
| | - Gerald Hoefler
- Department of Pathology, Medical University of Graz, 8036 Graz, Austria
| | - Michael Freissmuth
- Institute of Pharmacology, Center of Biomolecular Medicine and Pharmacology, Medical University of Vienna, 1090 Vienna, Austria
| | - Anthony R. Green
- Cambridge Institute for Medical Research and Wellcome Trust/MRC Stem Cell Institute, University of Cambridge, Cambridge CB2 0XY, UK
- Department of Hematology, University of Cambridge, Cambridge CB2 0XY, UK
- Department of Hematology, Addenbrooke’s Hospital, Cambridge CB2 0XY, UK
| | - Richard Moriggl
- Ludwig Boltzmann Institute for Cancer Research, 1090 Vienna, Austria
| | - Meinrad Busslinger
- Institute of Pharmacology, Center of Biomolecular Medicine and Pharmacology, Medical University of Vienna, 1090 Vienna, Austria
| | - Marcos Malumbres
- Cell Division and Cancer Group, Molecular Oncology Programme, Centro Nacional de Investigaciones Oncológicas (CNIO), 28029 Madrid, Spain
| | - Veronika Sexl
- Institute of Pharmacology and Toxicology, University of Veterinary Medicine Vienna, 1210 Vienna, Austria
- Corresponding author
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375
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Pavey S, Spoerri L, Haass NK, Gabrielli B. DNA repair and cell cycle checkpoint defects as drivers and therapeutic targets in melanoma. Pigment Cell Melanoma Res 2013; 26:805-16. [PMID: 23837768 DOI: 10.1111/pcmr.12136] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Accepted: 07/05/2013] [Indexed: 01/07/2023]
Abstract
The ultraviolet radiation (UVR) component of sunlight is the major environmental risk factor for melanoma, producing DNA lesions that can be mutagenic if not repaired. The high level of mutations in melanomas that have the signature of UVR-induced damage indicates that the normal mechanisms that detect and repair this damage must be defective in this system. With the exception of melanoma-prone heritable syndromes which have mutations of repair genes, there is little evidence for somatic mutation of known repair genes. Cell cycle checkpoint controls are tightly associated with repair mechanisms, arresting cells to allow for repair before continuing through the cell cycle. Checkpoint signaling components also regulate the repair mechanisms. Defects in checkpoint mechanisms have been identified in melanomas and are likely to be responsible for increased mutation load in melanoma. Loss of the checkpoint responses may also provide an opportunity to target melanomas using a synthetic lethal approach to identify and inhibit mechanisms that compensate for the defective checkpoints.
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Affiliation(s)
- Sandra Pavey
- The University of Queensland Diamantina Institute, Translational Research Institute, Brisbane, Qld, Australia
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376
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Du Z, Tong X, Ye X. Cyclin D1 promotes cell cycle progression through enhancing NDR1/2 kinase activity independent of cyclin-dependent kinase 4. J Biol Chem 2013; 288:26678-87. [PMID: 23897809 DOI: 10.1074/jbc.m113.466433] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cyclin/cyclin-dependent kinases (Cdks) are critical protein kinases in regulating cell cycle progression. Among them, cyclin D1/Cdk4 exerts its function mainly in the G1 phase. By using the tandem affinity purification tag approach, we identified a set of proteins interacting with Cdk4, including NDR1/2. Interestingly, confirming the interactions between NDR1/2 and cyclin D1/Cdk4, we observed that NDR1/2 interacted with cyclin D1 independent of Cdk4, but NDR1/2 and cyclin D1/Cdk4 did not phosphorylate each other. In addition, we found that NDR1/2 did not affect the kinase activity of cyclin D1/Cdk4 upon phosphorylation of GST-Rb. However, cyclin D1 but not Cdk4 promoted the kinase activity of NDR1/2. We also demonstrated that cyclin D1 K112E, which could not bind Cdk4, enhanced the kinase activity of NDR1/2. To test whether cyclin D1 promotes G1/S transition though enhancing NDR1/2 kinase activity, we performed flow cytometry analysis using cyclin D1 and cyclin D1 K112E Tet-On inducible cell lines. The data show that both cyclin D1 and cyclin D1 K112E promoted G1/S transition. Importantly, knockdown of NDR1/2 almost completely abolished the function of cyclin D1 K112E in promoting G1/S transition. Consistently, we found that the protein level of p21 was reduced in cells overexpressing cyclin D1 K112E but not when NDR1/2 was knocked down. Taken together, these results reveal a novel function of cyclin D1 in promoting cell cycle progression by enhancing NDR kinase activity independent of Cdk4.
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Affiliation(s)
- Zhaoyang Du
- From the Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101 and
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377
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Abstract
Forkhead box (FOX) proteins are multifaceted transcription factors that are responsible for fine-tuning the spatial and temporal expression of a broad range of genes both during development and in adult tissues. This function is engrained in their ability to integrate a multitude of cellular and environmental signals and to act with remarkable fidelity. Several key members of the FOXA, FOXC, FOXM, FOXO and FOXP subfamilies are strongly implicated in cancer, driving initiation, maintenance, progression and drug resistance. The functional complexities of FOX proteins are coming to light and have established these transcription factors as possible therapeutic targets and putative biomarkers for specific cancers.
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Affiliation(s)
- Eric W-F Lam
- Department of Surgery and Cancer, Imperial Centre for Translational and Experimental Medicine, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London W12 0NN, UK.
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378
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Joshi K, Banasavadi-Siddegowda Y, Mo X, Kim SH, Mao P, Kig C, Nardini D, Sobol RW, Chow LML, Kornblum HI, Waclaw R, Beullens M, Nakano I. MELK-dependent FOXM1 phosphorylation is essential for proliferation of glioma stem cells. Stem Cells 2013; 31:1051-63. [PMID: 23404835 PMCID: PMC3744761 DOI: 10.1002/stem.1358] [Citation(s) in RCA: 152] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2012] [Accepted: 01/29/2013] [Indexed: 12/19/2022]
Abstract
Glioblastoma multiforme (GBM) is a life-threatening brain tumor. Accumulating evidence suggests that eradication of glioma stem-like cells (GSCs) in GBM is essential to achieve cure. The transcription factor FOXM1 has recently gained attention as a master regulator of mitotic progression of cancer cells in various organs. Here, we demonstrate that FOXM1 forms a protein complex with the mitotic kinase MELK in GSCs, leading to phosphorylation and activation of FOXM1 in a MELK kinase-dependent manner. This MELK-dependent activation of FOXM1 results in a subsequent increase in mitotic regulatory genes in GSCs. MELK-driven FOXM1 activation is regulated by the binding and subsequent trans-phosphorylation of FOXM1 by another kinase PLK1. Using mouse neural progenitor cells (NPCs), we found that transgenic expression of FOXM1 enhances, while siRNA-mediated gene silencing diminishes neurosphere formation, suggesting that FOXM1 is required for NPC growth. During tumorigenesis, FOXM1 expression sequentially increases as cells progress from NPCs, to pretumorigenic progenitors and GSCs. The antibiotic Siomycin A disrupts MELK-mediated FOXM1 signaling with a greater sensitivity in GSC compared to neural stem cell. Treatment with the first-line chemotherapy agent for GBM, Temozolomide, paradoxically enriches for both FOXM1 (+) and MELK (+) cells in GBM cells, and addition of Siomycin A to Temozolomide treatment in mice harboring GSC-derived intracranial tumors enhances the effects of the latter. Collectively, our data indicate that FOXM1 signaling through its direct interaction with MELK regulates key mitotic genes in GSCs in a PLK1-dependent manner and thus, this protein complex is a potential therapeutic target for GBM.
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Affiliation(s)
- Kaushal Joshi
- Department of Neurological Surgery, The James Comprehensive Cancer Center, The Ohio State UniversityColumbus, Ohio, USA
| | | | - Xiaokui Mo
- Center for Biostatistics, The Ohio State UniversityColumbus, Ohio, USA
| | - Sung-Hak Kim
- Department of Neurological Surgery, The James Comprehensive Cancer Center, The Ohio State UniversityColumbus, Ohio, USA
| | - Ping Mao
- Department of Neurological Surgery, The James Comprehensive Cancer Center, The Ohio State UniversityColumbus, Ohio, USA
| | - Cenk Kig
- Laboratory of Biosignaling & Therapeutics, Department of Cellular and Molecular MedicineKULeuven, Leuven, Belgium
| | - Diana Nardini
- Cancer and Blood Diseases Institute at Cincinnati Children's Hospital Medical CenterCincinnati, Ohio, USA
- Division of Experimental Hematology and Cancer Biology at Cincinnati Children's Hospital Medical CenterCincinnati, Ohio, USA
| | - Robert W Sobol
- Department of Pharmacology & Chemical Biology, University of Pittsburgh Cancer InstitutePittsburgh, Pennsylvania, USA
- Department of Human Genetics, University of Pittsburgh Cancer InstitutePittsburgh, Pennsylvania, USA
| | - Lionel ML Chow
- Cancer and Blood Diseases Institute at Cincinnati Children's Hospital Medical CenterCincinnati, Ohio, USA
- Division of Experimental Hematology and Cancer Biology at Cincinnati Children's Hospital Medical CenterCincinnati, Ohio, USA
| | - Harley I Kornblum
- Department of Psychiatry, University of California Los AngelesLos Angeles, California, USA
- Department of Molecular and Medical Pharmacology, University of California Los AngelesLos Angeles, California, USA
| | - Ronald Waclaw
- Cancer and Blood Diseases Institute at Cincinnati Children's Hospital Medical CenterCincinnati, Ohio, USA
- Division of Experimental Hematology and Cancer Biology at Cincinnati Children's Hospital Medical CenterCincinnati, Ohio, USA
| | - Monique Beullens
- Laboratory of Biosignaling & Therapeutics, Department of Cellular and Molecular MedicineKULeuven, Leuven, Belgium
| | - Ichiro Nakano
- Department of Neurological Surgery, The James Comprehensive Cancer Center, The Ohio State UniversityColumbus, Ohio, USA
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379
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Targeting cell cycle and hormone receptor pathways in cancer. Oncogene 2013; 32:5481-91. [PMID: 23708653 PMCID: PMC3898261 DOI: 10.1038/onc.2013.83] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2012] [Revised: 01/29/2013] [Accepted: 02/01/2013] [Indexed: 12/21/2022]
Abstract
The cyclin/cyclin-dependent kinase (CDK)/retinoblastoma (RB)-axis is a critical modulator of cell cycle entry and is aberrant in many human cancers. New nodes of therapeutic intervention are needed that can delay or combat the onset of malignancies. The antitumor properties and mechanistic functions of PD-0332991 (PD; a potent and selective CDK4/6 inhibitor) were investigated using human prostate cancer (PCa) models and primary tumors. PD significantly impaired the capacity of PCa cells to proliferate by promoting a robust G1-arrest. Accordingly, key regulators of the G1-S cell cycle transition were modulated including G1 cyclins D, E and A. Subsequent investigation demonstrated the ability of PD to function in the presence of existing hormone-based regimens and to cooperate with ionizing radiation to further suppress cellular growth. Importantly, it was determined that PD is a critical mediator of PD action. The anti-proliferative impact of CDK4/6 inhibition was revealed through reduced proliferation and delayed growth using PCa cell xenografts. Finally, first-in-field effects of PD on proliferation were observed in primary human prostatectomy tumor tissue explants. This study shows that selective CDK4/6 inhibition, using PD either as a single-agent or in combination, hinders key proliferative pathways necessary for disease progression and that RB status is a critical prognostic determinant for therapeutic efficacy. Combined, these pre-clinical findings identify selective targeting of CDK4/6 as a bona fide therapeutic target in both early stage and advanced PCa and underscore the benefit of personalized medicine to enhance treatment response.
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380
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Signaling through cyclin D-dependent kinases. Oncogene 2013; 33:1890-903. [PMID: 23644662 DOI: 10.1038/onc.2013.137] [Citation(s) in RCA: 203] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Revised: 02/22/2013] [Accepted: 02/27/2013] [Indexed: 12/13/2022]
Abstract
Research over the past quarter century has identified cyclin D-dependent kinases, CDK4 and CDK6, as the major oncogenic drivers among members of the CDK superfamily. CDK4/6 are rendered hyperactive in the majority of human cancers through a multitude of genomic alterations. Sustained activation of these protein kinases provides cancer cells with the power to enter the cell cycle continuously by triggering G1-S-phase transitions and dramatically shortening the duration of the G1 phase. It has also become clear, however, that CDK4/6 effectively counter cancer cell-intrinsic tumor suppression mechanisms, senescence and apoptosis, which must be overcome during cell transformation and kept at bay throughout all stages of tumorigenesis. As a central 'node' in cellular signaling networks, cyclin D-dependent kinases sense a plethora of mitogenic signals to orchestrate specific transcriptional programs. As the complexity of the cellular signaling network regulated by these oncogenic kinases unfolds, much remains to be learned about its architecture, its dynamics and the consequences of its perturbation.
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381
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Haarberg HE, Paraiso KHT, Wood E, Rebecca VW, Sondak VK, Koomen JM, Smalley KSM. Inhibition of Wee1, AKT, and CDK4 underlies the efficacy of the HSP90 inhibitor XL888 in an in vivo model of NRAS-mutant melanoma. Mol Cancer Ther 2013; 12:901-12. [PMID: 23538902 DOI: 10.1158/1535-7163.mct-12-1003] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The HSP90 inhibitor XL888 is effective at reversing BRAF inhibitor resistance in melanoma, including that mediated through acquired NRAS mutations. The present study has investigated the mechanism of action of XL888 in NRAS-mutant melanoma. Treatment of NRAS-mutant melanoma cell lines with XL888 led to an inhibition of growth, G2-M phase cell-cycle arrest, and the inhibition of cell survival in three-dimensional spheroid and colony formation assays. In vitro, HSP90 inhibition led to the degradation of ARAF, CRAF, Wee1, Chk1, and cdc2 and was associated with decreased mitogen-activated protein kinase (MAPK), AKT, mTOR, and c-jun NH2 kinase (JNK) signaling. Apoptosis induction was associated with increased BIM expression and a decrease in the expression of the prosurvival protein Mcl-1. The critical role of increased BIM and decreased Mcl-1 expression in the survival of NRAS-mutant melanoma cell lines was shown through siRNA knockdown and overexpression studies. In an animal xenograft model of NRAS-mutant melanoma, XL888 treatment led to reduced tumor growth and apoptosis induction. Important differences in the pattern of client degradation were noted between the in vivo and in vitro studies. In vivo, XL888 treatment led to degradation of CDK4 and Wee1 and the inhibition of AKT/S6 signaling with little or no effect observed upon ARAF, CRAF, or MAPK. Blockade of Wee1, using either siRNA knockdown or the inhibitor MK1775, was associated with significant levels of growth inhibition and apoptosis induction. Together, these studies have identified Wee1 as a key target of XL888, suggesting novel therapeutic strategies for NRAS-mutant melanoma.
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Affiliation(s)
- H Eirik Haarberg
- Department of Molecular Oncology, The Moffitt Cancer Center & Research Institute, Tampa, FL 33612, USA
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382
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Alvarez-Fernández M, Medema RH. Novel functions of FoxM1: from molecular mechanisms to cancer therapy. Front Oncol 2013; 3:30. [PMID: 23467617 PMCID: PMC3588610 DOI: 10.3389/fonc.2013.00030] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2012] [Accepted: 02/04/2013] [Indexed: 12/12/2022] Open
Abstract
FoxM1 is a member of the forkhead family of transcription factors. Since its identification 15 year ago, numerous studies have progressively contributed to our current understanding on FoxM1 functions. Early work showed that FoxM1 regulates the transcriptional program of the G2 phase of the cell cycle, and is essential for proper mitotic progression and genomic stability. Moreover, FoxM1 was found to be overexpressed in many different types of human cancer, suggesting a role of FoxM1 in tumor proliferation. In the past years, a significant number of studies have formally demonstrated the involvement of FoxM1 in different aspects of tumorogenesis, including angiogenesis, invasion, and metastasis. In addition to this, recent studies have placed FoxM1 in DNA damage response and senescence pathways, two pathways relevant to tumor progression and the response to cancer therapies. Here, we review and discuss the molecular mechanisms through which FoxM1 executes these new roles, and the implications for the potential use of FoxM1 as a therapeutic target in cancer.
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383
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MacKenzie Ross AD, Cook MG, Chong H, Hossain M, Pandha HS, Bennett DC. Senescence evasion in melanoma progression: uncoupling of DNA-damage signaling from p53 activation and p21 expression. Pigment Cell Melanoma Res 2013; 26:226-35. [PMID: 23253087 PMCID: PMC3963476 DOI: 10.1111/pcmr.12060] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Accepted: 12/15/2012] [Indexed: 01/07/2023]
Abstract
The best-established function of the melanoma-suppressor p16 is mediation of cell senescence, a permanent arrest following cell proliferation or certain stresses. The importance of p16 in melanoma suggests indolence of the other major senescence pathway through p53. Little or no p53 is expressed in senescent normal human melanocytes, but p16-deficient melanocytes can undergo p53-mediated senescence. As p16 expression occurs in nevi but falls with progression toward melanoma, we here investigated whether p53-dependent senescence occurs at some stage and, if not, what defects were detectable in this pathway, using immunohistochemistry. Phosphorylated checkpoint kinase 2 (CHEK2) can mediate DNA-damage signaling, and under some conditions senescence, by phosphorylating and activating p53. Remarkably, we detected no prevalent p53-mediated senescence in any of six classes of lesions. Two separate defects in p53 signaling appeared common: in nevi, lack of p53 phosphorylation by activated CHEK2, and in melanomas, defective p21 upregulation by p53 even when phosphorylated.
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Affiliation(s)
- Alastair D MacKenzie Ross
- Biomedical Sciences Research Centre (Box J2A), St George's, University of LondonCranmer Terrace, London, SW17 0RE, UK
| | - Martin G Cook
- Department of Histopathology, Royal Surrey County Hospital and Division of Clinical Medicine, University of SurreyGuildford, UK
| | - Heung Chong
- Cellular Pathology, Division of Biomedical Sciences, St George's, University of LondonLondon, UK
| | - Mehnaz Hossain
- Biomedical Sciences Research Centre (Box J2A), St George's, University of LondonCranmer Terrace, London, SW17 0RE, UK
| | - Hardev S Pandha
- Postgraduate Medical School, University of SurreyGuildford, UK
| | - Dorothy C Bennett
- Biomedical Sciences Research Centre (Box J2A), St George's, University of LondonCranmer Terrace, London, SW17 0RE, UK
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384
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Abstract
FOXM1 is an oncogenic transcription factor of the Forkhead family and it has a well-defined role in cell proliferation and cell-cycle progression. Expression of FOXM1 is excluded in quiescent or differentiated cells, but its level is highly elevated in proliferating and malignant cells. Overexpression of FOXM1 has been reported in more than 20 types of human cancer. In recent years, FOXM1 has been implicated in diverse cellular processes and also a growing body of experimental data has underlined the relevance of FOXM1 in tumorigenesis. Although FOXM1 is under the control of three major tumor suppressors (RB, p53, and p19(ARF)), it is still active in the majority of human cancers. The oncogenic potential of FOXM1 is mainly based on its ability to transcriptionally activate genes that are involved in different facets of cancer development. In this review, the contribution of FOXM1 to each of the hallmarks of cancer will be summarized and discussed.
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Affiliation(s)
- Marianna Halasi
- University of Illinois at Chicago, Department of Medicine, Chicago, IL 60612, USA
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385
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Lam AKY, Ngan AWL, Leung MH, Kwok DCT, Liu VWS, Chan DW, Leung WY, Yao KM. FOXM1b, which is present at elevated levels in cancer cells, has a greater transforming potential than FOXM1c. Front Oncol 2013; 3:11. [PMID: 23386997 PMCID: PMC3560383 DOI: 10.3389/fonc.2013.00011] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Accepted: 01/11/2013] [Indexed: 01/06/2023] Open
Abstract
The forkhead box (FOX) M1 transcription factor is required to maintain the proliferation of cancer cells. Two transcriptionally active isoforms of FOXM1, FOXM1b and FOXM1c, have been identified, but their functional differences remain unclear. FOXM1c is distinguished from FOXM1b by an extra exon (exon Va) that contains an ERK1/2 target sequence. Based on a literature search and quantitative PCR analysis, we concluded that FOXM1b is the predominant isoform that is overexpressed in cancers. The further characterization of FOXM1b and FOXM1c revealed two interesting differences. First, FOXM1b exhibited a higher transforming ability than FOXM1c in a soft agar assay. Second, the transactivating activity of FOXM1c, but not that of FOXM1b, was sensitive to activation by RAF/MEK/MAPK signaling. Importantly, the MEK1 activation of FOXM1c was associated with proteolytic processing to generate short forms that might represent constitutively active forms missing the N-terminal inhibitory domain; in contrast, the proteolytic processing of FOXM1b did not require MEK1 activation. Our findings suggest that FOXM1b is functionally more active. These results provide novel insights into the regulation of FOXM1 activity and its role in tumorigenesis.
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Affiliation(s)
- Andy K Y Lam
- Department of Biochemistry, The Li Ka Shing Faculty of Medicine, The University of Hong Kong Hong Kong SAR, China
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386
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Sanders DA, Ross-Innes CS, Beraldi D, Carroll JS, Balasubramanian S. Genome-wide mapping of FOXM1 binding reveals co-binding with estrogen receptor alpha in breast cancer cells. Genome Biol 2013; 14:R6. [PMID: 23347430 PMCID: PMC3663086 DOI: 10.1186/gb-2013-14-1-r6] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Revised: 12/24/2012] [Accepted: 01/24/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The forkhead transcription factor FOXM1 is a key regulator of the cell cycle. It is frequently over-expressed in cancer and is emerging as an important therapeutic target. In breast cancer FOXM1 expression is linked with estrogen receptor (ERα) activity and resistance to endocrine therapies, with high levels correlated with poor prognosis. However, the precise role of FOXM1 in ER positive breast cancer is not yet fully understood. RESULTS The study utilizes chromatin immunoprecipitation followed by high-throughput sequencing to map FOXM1 binding in both ERα-positive and -negative breast cancer cell lines. The comparison between binding site distributions in the two cell lines uncovered a previously undescribed relationship between binding of FOXM1 and ERα. Further molecular analyses demonstrated that these two factors can bind simultaneously at genomic sites and furthermore that FOXM1 regulates the transcriptional activity of ERα via interaction with the coactivator CARM1. Inhibition of FOXM1 activity using the natural product thiostrepton revealed down-regulation of a set of FOXM1-regulated genes that are correlated with patient outcome in clinical breast cancer samples. CONCLUSIONS These findings reveal a novel role for FOXM1 in ERα transcriptional activity in breast cancer and uncover a FOXM1-regulated gene signature associated with ER-positive breast cancer patient prognosis.
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Affiliation(s)
- Deborah A Sanders
- Cancer Research UK, Cambridge Research Institute, Li Ka Shing Centre, Robinson Way, Cambridge, CB2 0RE, UK
| | - Caryn S Ross-Innes
- Cancer Research UK, Cambridge Research Institute, Li Ka Shing Centre, Robinson Way, Cambridge, CB2 0RE, UK
| | - Dario Beraldi
- Cancer Research UK, Cambridge Research Institute, Li Ka Shing Centre, Robinson Way, Cambridge, CB2 0RE, UK
| | - Jason S Carroll
- Cancer Research UK, Cambridge Research Institute, Li Ka Shing Centre, Robinson Way, Cambridge, CB2 0RE, UK
- Department of Oncology, University of Cambridge, Cambridge, CB2 0RE, UK
| | - Shankar Balasubramanian
- Cancer Research UK, Cambridge Research Institute, Li Ka Shing Centre, Robinson Way, Cambridge, CB2 0RE, UK
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
- School of Clinical Medicine, The University of Cambridge, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0SP, UK
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387
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Wierstra I. Cyclin D1/Cdk4 increases the transcriptional activity of FOXM1c without phosphorylating FOXM1c. Biochem Biophys Res Commun 2013; 431:753-9. [PMID: 23333330 DOI: 10.1016/j.bbrc.2013.01.037] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2012] [Accepted: 01/05/2013] [Indexed: 01/17/2023]
Abstract
Anders et al. (2011) [11] reported that cyclinD1/Cdk4 and cyclinD3/Cdk6 enhance the transcriptional activity of FOXM1c by phosphorylating its TAD. They defined 12 Cdk consensus sites as essential for the activation of FOXM1c by cyclinD1/Cdk4 and cyclinD3/Cdk6 and stated that the 12 Cdk-sites are positioned within the TAD of FOXM1c. In contrast, this study demonstrates that all potential cyclin/Cdk phosphorylation sites S/T-P of FOXM1c are located outside its TAD so that the TAD of FOXM1c contains no potential cyclin/Cdk site, which excludes a phosphorylation of the FOXM1c-TAD by cyclinD1/Cdk4 and cyclinD3/Cdk6. This study shows that the activation of FOXM1c by cyclinD1/Cdk4 is lost without removal of any cyclin/Cdk site and gained without addition of any cyclin/Cdk site because it depends on a FOXM1c domain with no potential cyclin/Cdk site, namely on the interaction domain for the tumor suppressor RB, which binds to and represses FOXM1c. CyclinD1/Cdk4 activates FOXM1c because cyclinD1/Cdk4 releases FOXM1c from its repression by RB through removal of RB from FOXM1c. For this purpose, cyclinD1/Cdk4 phosphorylates only RB, but not FOXM1c, so that cyclinD1/Cdk4 increases the transcriptional activity of FOXM1c without phosphorylating FOXM1c and activates FOXM1c independently of cyclin/Cdk phosphorylation sites in FOXM1c. In summary, this study changes the model of Anders et al. (2011) [11] completely because it disproves their central conclusion that cyclinD1/Cdk4 and cyclinD3/Cdk6 enhance the transcriptional activity of FOXM1c by phosphorylating its TAD at the 12 Cdk-sites.
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Affiliation(s)
- Inken Wierstra
- Institute of Molecular Biology, Medical School Hannover, Carl-Neuberg-Str. 1, D-30625 Hannover, Germany.
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388
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Wierstra I. FOXM1 (Forkhead box M1) in tumorigenesis: overexpression in human cancer, implication in tumorigenesis, oncogenic functions, tumor-suppressive properties, and target of anticancer therapy. Adv Cancer Res 2013; 119:191-419. [PMID: 23870513 DOI: 10.1016/b978-0-12-407190-2.00016-2] [Citation(s) in RCA: 136] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
FOXM1 (Forkhead box M1) is a typical proliferation-associated transcription factor and is also intimately involved in tumorigenesis. FOXM1 stimulates cell proliferation and cell cycle progression by promoting the entry into S-phase and M-phase. Additionally, FOXM1 is required for proper execution of mitosis. In accordance with its role in stimulation of cell proliferation, FOXM1 exhibits a proliferation-specific expression pattern and its expression is regulated by proliferation and anti-proliferation signals as well as by proto-oncoproteins and tumor suppressors. Since these factors are often mutated, overexpressed, or lost in human cancer, the normal control of the foxm1 expression by them provides the basis for deregulated FOXM1 expression in tumors. Accordingly, FOXM1 is overexpressed in many types of human cancer. FOXM1 is intimately involved in tumorigenesis, because it contributes to oncogenic transformation and participates in tumor initiation, growth, and progression, including positive effects on angiogenesis, migration, invasion, epithelial-mesenchymal transition, metastasis, recruitment of tumor-associated macrophages, tumor-associated lung inflammation, self-renewal capacity of cancer cells, prevention of premature cellular senescence, and chemotherapeutic drug resistance. However, in the context of urethane-induced lung tumorigenesis, FOXM1 has an unexpected tumor suppressor role in endothelial cells because it limits pulmonary inflammation and canonical Wnt signaling in epithelial lung cells, thereby restricting carcinogenesis. Accordingly, FOXM1 plays a role in homologous recombination repair of DNA double-strand breaks and maintenance of genomic stability, that is, prevention of polyploidy and aneuploidy. The implication of FOXM1 in tumorigenesis makes it an attractive target for anticancer therapy, and several antitumor drugs have been reported to decrease FOXM1 expression.
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389
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Cyclin-dependent kinase 6 phosphorylates NF-κB P65 at serine 536 and contributes to the regulation of inflammatory gene expression. PLoS One 2012; 7:e51847. [PMID: 23300567 PMCID: PMC3530474 DOI: 10.1371/journal.pone.0051847] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Accepted: 11/07/2012] [Indexed: 11/20/2022] Open
Abstract
Nuclear factor kappa-B (NF-κB) activates multiple genes with overlapping roles in cell proliferation, inflammation and cancer. Using an unbiased approach we identified human CDK6 as a novel kinase phosphorylating NF-κB p65 at serine 536. Purified and reconstituted CDK6/cyclin complexes phosphorylated p65 in vitro and in transfected cells. The physiological role of CDK6 for basal as well as cytokine-induced p65 phosphorylation or NF-κB activation was revealed upon RNAi-mediated suppression of CDK6. Inhibition of CDK6 catalytic activity by PD332991 suppressed activation of NF-κB and TNF-induced gene expression. In complex with a constitutively active viral cyclin CDK6 stimulated NF-κB p65-mediated transcription in a target gene specific manner and this effect was partially dependent on its ability to phosphorylate p65 at serine 536. Tumor formation in thymi and spleens of v-cyclin transgenic mice correlated with increased levels of p65 Ser536 phosphorylation, increased expression of CDK6 and upregulaton of the NF-κB target cyclin D3. These results suggest that aberrant CDK6 expression or activation that is frequently observed in human tumors can contribute through NF-κB to chronic inflammation and neoplasia.
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390
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Abstract
Cancer stem cells may be responsible for tumor initiation and maintenance. The molecular mechanisms that control cancer stem cells are related to alterations in various signaling pathways, including the Wnt/β-catenin signaling pathway. The canonical Wnt/β-catenin signaling pathway is one of the major signaling systems in stem and progenitor cells, and aberrant activation of the Wnt/β-catenin signaling pathway is common in human cancers. As with β-catenin, FoxM1 has been found to play important roles in a number of cancers. In this review, we discuss the evidence that FoxM1 affects the expression and function of a variety of genes that are critical to the survival, proliferation, invasion, angiogenesis, and self-renewal of cancer stem cells. We highlight the pivotal roles of the Wnt/β-catenin and FoxM1 signaling pathways in neural stem and progenitor cells and glioma stem cells. We also discuss the evidence for cross-talk between the β-catenin and FoxM1 signaling pathways in the regulation of the stemness and tumorigenicity of glioma stem cells.
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Affiliation(s)
- Aihua Gong
- Department of Neurosurgery, The University of Texas MD Anderson Cancer Center and Program in Cancer Biology, The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, Texas 77030, USA
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391
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Abstract
The cell cycle is regulated in part by cyclins and their associated serine/threonine cyclin-dependent kinases, or CDKs. CDK4, in conjunction with the D-type cyclins, mediates progression through the G1 phase when the cell prepares to initiate DNA synthesis. Although CDK4-null mutant mice are viable and cell proliferation is not significantly affected in vitro due to compensatory roles played by other CDKs, this gene plays a key role in mammalian development and cancer. This review discusses the role that CDK4 plays in cell cycle control, normal development, and tumorigenesis as well as how small molecule inhibitors of CDK4 can be used to treat disease.
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392
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Halasi M, Gartel AL. Targeting FOXM1 in cancer. Biochem Pharmacol 2012; 85:644-652. [PMID: 23103567 DOI: 10.1016/j.bcp.2012.10.013] [Citation(s) in RCA: 364] [Impact Index Per Article: 30.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Revised: 10/15/2012] [Accepted: 10/17/2012] [Indexed: 11/28/2022]
Abstract
Oncogenic transcription factor FOXM1 is overexpressed in the majority of human cancers. In addition, FOXM1 has been implicated in cell migration, invasion, angiogenesis and metastasis. The important role of FOXM1 in cancer affirms its significance for therapeutic intervention. Current data suggest that targeting FOXM1 in mono- or combination therapy may have promising therapeutic benefits for the treatment of cancer. However, challenges with the delivery of anti-FOXM1 siRNA to tumors and the absence of small molecules, which specifically inhibit FOXM1, are delaying the development of FOXM1 inhibitors as feasible anticancer drugs. In this review, we describe and summarize the efforts that have been made to target FOXM1 in cancer and the consequences of FOXM1 suppression in human cancer cells.
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Affiliation(s)
- Marianna Halasi
- Department of Medicine, University of Illinois at Chicago, Chicago, IL, United States of America
| | - Andrei L Gartel
- Department of Medicine, University of Illinois at Chicago, Chicago, IL, United States of America.
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393
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Choi YJ, Li X, Hydbring P, Sanda T, Stefano J, Christie AL, Signoretti S, Look AT, Kung AL, von Boehmer H, Sicinski P. The requirement for cyclin D function in tumor maintenance. Cancer Cell 2012; 22:438-51. [PMID: 23079655 PMCID: PMC3487466 DOI: 10.1016/j.ccr.2012.09.015] [Citation(s) in RCA: 257] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2012] [Revised: 06/24/2012] [Accepted: 09/18/2012] [Indexed: 11/24/2022]
Abstract
D-cyclins represent components of cell cycle machinery. To test the efficacy of targeting D-cyclins in cancer treatment, we engineered mouse strains that allow acute and global ablation of individual D-cyclins in a living animal. Ubiquitous shutdown of cyclin D1 or inhibition of cyclin D-associated kinase activity in mice bearing ErbB2-driven mammary carcinomas triggered tumor cell senescence, without compromising the animals' health. Ablation of cyclin D3 in mice bearing Notch1-driven T cell acute lymphoblastic leukemias (T-ALL) triggered tumor cell apoptosis. Such selective killing of leukemic cells can also be achieved by inhibiting cyclin D associated kinase activity in mouse and human T-ALL models. Inhibition of cyclin D-kinase activity represents a highly-selective anticancer strategy that specifically targets cancer cells without significantly affecting normal tissues.
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Affiliation(s)
- Yoon Jong Choi
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
- Department of Genetics, Harvard Medical School, Boston, MA 02115
| | - Xiaoyu Li
- Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, Boston, MA 02215, USA
- Department of Microbiology and Immunology, Harvard Medical School, Boston, MA 02115
| | - Per Hydbring
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
- Department of Genetics, Harvard Medical School, Boston, MA 02115
| | - Takaomi Sanda
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
- Division of Hematology/Oncology, Children’s Hospital, Boston, MA 02115, USA
- Department of Pediatrics, Harvard Medical School, Boston, MA 02115
| | - Joanna Stefano
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
| | - Amanda L. Christie
- Lurie Family Imaging Center, Dana-Farber Cancer Institute, Boston, MA 02215, USA
| | - Sabina Signoretti
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
- Department of Pathology, Brigham and Women’s Hospital, Boston, MA 02115, USA
| | - A. Thomas Look
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
- Division of Hematology/Oncology, Children’s Hospital, Boston, MA 02115, USA
- Department of Pediatrics, Harvard Medical School, Boston, MA 02115
| | - Andrew L. Kung
- Lurie Family Imaging Center, Dana-Farber Cancer Institute, Boston, MA 02215, USA
- Department of Pediatrics, Harvard Medical School, Boston, MA 02115
| | - Harald von Boehmer
- Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, Boston, MA 02215, USA
- Department of Microbiology and Immunology, Harvard Medical School, Boston, MA 02115
| | - Piotr Sicinski
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
- Department of Genetics, Harvard Medical School, Boston, MA 02115
- Correspondence:
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394
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Abstract
The mitogen-activated protein kinase (MAPK) pathway has been implicated in the pathophysiology of many cancers. Under normal physiologic conditions, the RAS-RAF-mitogen-activated protein kinase kinase (MEK)-mitogen-activated protein kinase (ERK) signalling cascade interaction is initiated by ligation of a receptor-linked tyrosine kinase by its cognate growth factor. It has been demonstrated in many systems that aberrant autocrine or paracrine stimulation of growth factor receptors is pathogenic in large part because of MAPK activation. As one of the key downstream effector pathways of mutated RAS (KRAS, NRAS and HRAS), pharmacologic inhibition of components of the MAPK pathway has been pursued as a means to indirectly inhibit RAS, which remains a technical challenge for direct pharmacologic inhibition. RAF and MEK are the two non-membrane-bound, serine-threonine and tyrosine-threonine kinases, within the pathway that have been most extensively explored as drug targets. The discovery of activating BRAF mutations in cancer clarified which cancer types and subsets of certain cancers are most dependent on activation of the MAPK pathway for growth and survival. Now, with the successful translation of selective BRAF and MEK inhibitors into validated therapies for BRAF mutant melanoma, the field seeks to resolve the role for these agents in cancers harbouring RAS mutations or those driven by aberrant growth factor receptor activation.
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395
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Liu F, Korc M. Cdk4/6 inhibition induces epithelial-mesenchymal transition and enhances invasiveness in pancreatic cancer cells. Mol Cancer Ther 2012; 11:2138-48. [PMID: 22869556 PMCID: PMC3752412 DOI: 10.1158/1535-7163.mct-12-0562] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Aberrant activation of Cyclin D-Cdk4/6 signaling pathway is commonly found in pancreatic ductal adenocarcinoma (PDAC). Here, we show that PD-0332991, a highly specific inhibitor for Cdk4 and Cdk6, exerted growth inhibitory effects on three human PDAC cell lines. Microarray analysis revealed that PD-0332991 downregulated cell-cycle-related genes, but upregulated genes implicated in extracellular matrix (ECM) remodeling and pancreatic cancer cell invasion and metastasis. Moreover, PD-0332991 enhanced invasion in TGF-β-responsive PDAC cell lines that harbor a wild-type SMAD4 gene (COLO-357, PANC-1), but not in TGF-β-resistant AsPC-1 cells that harbor a mutated SMAD4. PD-0332991 also induced epithelial-mesenchymal transition (EMT) in COLO-357 and PANC-1, but not in AsPC-1 cells. Inhibition of CDK4/6 using shRNA mimicked the effects of PD-0332991 on EMT induction. Furthermore, PD-0332991 increased Smad transcriptional activity in luciferase readout assays and activated TGF-β signaling. SB-505124, an inhibitor of the type-I TGF-β receptor (TβRI) kinase, completely blocked EMT induction by PD-0332991. When combined with PD-0332991, SB-505124 inhibited the growth of COLO-357 and PANC-1 cells. Taken together, these data suggest that anti-Cdk4/6 therapy could induce EMT and enhance pancreatic cancer cell invasion by activating Smad-dependent TGF-β signaling, and that combining PD-0332991 and SB-505124 may represent a novel therapeutic strategy in PDAC.
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Affiliation(s)
- Fang Liu
- Departments of Medicine, Biochemistry and Molecular Biology, Indiana University School of Medicine, the Melvin and Bren Simon Cancer Center and the Pancreatic Cancer Signature Center, Indianapolis, IN 46202, USA
| | - Murray Korc
- Departments of Medicine, Biochemistry and Molecular Biology, Indiana University School of Medicine, the Melvin and Bren Simon Cancer Center and the Pancreatic Cancer Signature Center, Indianapolis, IN 46202, USA
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396
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Jirawatnotai S, Hu Y, Livingston DM, Sicinski P. Proteomic identification of a direct role for cyclin d1 in DNA damage repair. Cancer Res 2012; 72:4289-93. [PMID: 22915759 DOI: 10.1158/0008-5472.can-11-3549] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The human CCND1 gene, which encodes the cell-cycle protein cyclin D1, is one of the most frequently amplified genes in human cancers. Cyclin D1 activates the cyclin-dependent kinases CDK4 and CDK6 and drives cell proliferation. Beyond the cell-cycle role, the full repertoire of cyclin D1 functions in cancer cells is still unclear. Emerging evidence indicates that cyclin D1 may play a role in DNA damage response. In this review, we discuss observations linking cyclin D1 to DNA damage repair and summarize our recent findings, which show a cyclin D1 function in homologous recombination-mediated DNA repair.
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Affiliation(s)
- Siwanon Jirawatnotai
- Department of Cancer Biology, Dana-Farber Cancer Institute, and Department of Genetics, Harvard Medical School, Boston, MA 02215, USA
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397
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Dean JL, McClendon AK, Knudsen ES. Modification of the DNA damage response by therapeutic CDK4/6 inhibition. J Biol Chem 2012; 287:29075-87. [PMID: 22733811 DOI: 10.1074/jbc.m112.365494] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The RB/E2F axis represents a critical node of cell signaling that integrates a diverse array of signaling pathways. Recent evidence has suggested a role for E2F-mediated gene transcription in DNA damage response and repair, as well as apoptosis signaling. Herein, we investigated how repression of E2F activity via CDK4/6 inhibition and RB activation impacts the response of triple negative breast cancer (TNBC) to frequently used therapeutic agents. In combination with taxanes and anthracyclines CDK4/6 inhibition and consequent cell cycle arrest prevented the induction of DNA damage and associated cell death in an RB-dependent manner; thereby demonstrating antagonism between the cytostatic influence of the CDK-inhibitor and cytotoxic agents. As many of these effects were secondary to cell cycle arrest, γ-irradiation (IR) was utilized to examine effects of CDK4/6 inhibition on direct DNA damage. Although E2F controls a number of genes involved in DNA repair (e.g. Rad51), CDK4/6 inhibition did not alter the overall rate of DNA repair, rather it significantly shifted the burden of this repair from homologous recombination (HR) to non-homologous end joining (NHEJ). Together, these data indicate that CDK4/6 inhibition can antagonize cytotoxic therapeutic strategies and increases utilization of error-prone DNA repair mechanisms that could contribute to disease progression.
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Affiliation(s)
- Jeffry L Dean
- Kimmel Cancer Center, Philadelphia, Pennsylvania, USA
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398
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Prolonged early G(1) arrest by selective CDK4/CDK6 inhibition sensitizes myeloma cells to cytotoxic killing through cell cycle-coupled loss of IRF4. Blood 2012; 120:1095-106. [PMID: 22718837 DOI: 10.1182/blood-2012-03-415984] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Dysregulation of cyclin-dependent kinase 4 (CDK4) and CDK6 by gain of function or loss of inhibition is common in human cancer, including multiple myeloma, but success in targeting CDK with broad-spectrum inhibitors has been modest. By selective and reversible inhibition of CDK4/CDK6, we have developed a strategy to both inhibit proliferation and enhance cytotoxic killing of cancer cells. We show that induction of prolonged early-G(1) arrest (pG1) by CDK4/CDK6 inhibition halts gene expression in early-G(1) and prevents expression of genes programmed for other cell-cycle phases. Removal of the early-G(1) block leads to S-phase synchronization (pG1-S) but fails to completely restore scheduled gene expression. Consequently, the IRF4 protein required to protect myeloma cells from apoptosis is markedly reduced in pG1 and further in pG1-S in response to cytotoxic agents, such as the proteasome inhibitor bortezomib. The coordinated loss of IRF4 and gain of Bim sensitize myeloma tumor cells to bortezomib-induced apoptosis in pG1 in the absence of Noxa and more profoundly in pG1-S in cooperation with Noxa in vitro. Induction of pG1 and pG1-S by reversible CDK4/CDK6 inhibition further augments tumor-specific bortezomib killing in myeloma xenografts. Reversible inhibition of CDK4/CDK6 in sequential combination therapy thus represents a novel mechanism-based cancer therapy.
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399
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Postnikoff SDL, Harkness TAA. Mechanistic insights into aging, cell-cycle progression, and stress response. Front Physiol 2012; 3:183. [PMID: 22675309 PMCID: PMC3366476 DOI: 10.3389/fphys.2012.00183] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2012] [Accepted: 05/17/2012] [Indexed: 12/22/2022] Open
Abstract
The longevity of an organism depends on the health of its cells. Throughout life cells are exposed to numerous intrinsic and extrinsic stresses, such as free radicals, generated through mitochondrial electron transport, and ultraviolet irradiation. The cell has evolved numerous mechanisms to scavenge free radicals and repair damage induced by these insults. One mechanism employed by the yeast Saccharomycescerevisiae to combat stress utilizes the Anaphase Promoting Complex (APC), an essential multi-subunit ubiquitin-protein ligase structurally and functionally conserved from yeast to humans that controls progression through mitosis and G1. We have observed that yeast cells expressing compromised APC subunits are sensitive to multiple stresses and have shorter replicative and chronological lifespans. In a pathway that runs parallel to that regulated by the APC, members of the Forkhead box (Fox) transcription factor family also regulate stress responses. The yeast Fox orthologs Fkh1 and Fkh2 appear to drive the transcription of stress response factors and slow early G1 progression, while the APC seems to regulate chromatin structure, chromosome segregation, and resetting of the transcriptome in early G1. In contrast, under non-stress conditions, the Fkhs play a complex role in cell-cycle progression, partially through activation of the APC. Direct and indirect interactions between the APC and the yeast Fkhs appear to be pivotal for lifespan determination. Here we explore the potential for these interactions to be evolutionarily conserved as a mechanism to balance cell-cycle regulation with stress responses.
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Affiliation(s)
- S D L Postnikoff
- Department of Anatomy and Cell Biology, University of Saskatchewan Saskatoon, SK, Canada
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400
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Dividing and conquering: controlling advanced melanoma by targeting oncogene-defined subsets. Clin Exp Metastasis 2012; 29:841-6. [DOI: 10.1007/s10585-012-9488-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Accepted: 05/21/2012] [Indexed: 10/28/2022]
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