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Huang Y, Zhen Y, Chen Y, Sui S, Zhang L. Unraveling the interplay between RAS/RAF/MEK/ERK signaling pathway and autophagy in cancer: From molecular mechanisms to targeted therapy. Biochem Pharmacol 2023; 217:115842. [PMID: 37802240 DOI: 10.1016/j.bcp.2023.115842] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 09/28/2023] [Accepted: 10/02/2023] [Indexed: 10/08/2023]
Abstract
RAS/RAF/MEK/ERK signaling pathway is one of the most important pathways of Mitogen-activated protein kinases (MAPK), which widely participate in regulating cell proliferation, differentiation, apoptosis and signaling transduction. Autophagy is an essential mechanism that maintains cellular homeostasis by degrading aged and damaged organelles. Recently, some studies revealed RAS/RAF/MEK/ERK signaling pathway is closely related to autophagy regulation and has a dual effect in tumor cells. However, the specific mechanism by which RAS/RAF/MEK/ERK signaling pathway participates in autophagy regulation is not fully understood. This article provides a comprehensive review of the research progress with regard to the RAS/RAF/MEK/ERK signaling pathway and autophagy, as well as their interplay in cancer therapy. The impact of small molecule inhibitors that target the RAS/RAF/MEK/ERK signaling pathway on autophagy is discussed in this study. The advantages and limitations of the clinical combination of these small molecule inhibitors with autophagy inhibitors are also explored. The findings from this study may provide additional perspectives for future cancer treatment strategies.
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Affiliation(s)
- Yunli Huang
- Sichuan Engineering Research Center for Biomimetic Synthesis of Natural Drugs, School of Life Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China
| | - Yongqi Zhen
- Department of Biotherapy, Cancer Center and State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Yanmei Chen
- Department of Biotherapy, Cancer Center and State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Shaoguang Sui
- Emergency Department, The Second Hospital, Dalian Medical University, Dalian 116000, China.
| | - Lan Zhang
- Sichuan Engineering Research Center for Biomimetic Synthesis of Natural Drugs, School of Life Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China.
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Liu W, Yuan W, Li X, Zhuang J, Mo X, Dai G, Wang Y, Chen J, Wan Y, Li Y, Zhu X, Chen Y, Luo S, Jiang Z, Shi Y, Chen F, Cao L, Ye X, Fan X, Zhu P, Zhang K, Wu X. ZNF424 Induces Apoptosis and Inhibits Proliferation in Lung Carcinoma Cells. Curr Mol Med 2019; 18:109-115. [PMID: 29974829 PMCID: PMC6225340 DOI: 10.2174/1566524018666180705113642] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Revised: 06/29/2018] [Accepted: 07/04/2018] [Indexed: 11/22/2022]
Abstract
Background: Previously, we showed that the Zinc finger-containing transcription factor ZNF424 inhibits p21 transcription, which has been widely associated with various cancers. However, because the roles of ZNF424 in tumorigenesis have not been characterized, we correlated ZNF424 expression with tumorigenesis in lung cancer. Results: The present immunohistochemical analyses show significantly lower ZNF424 expression levels in 43 of 60 lung cancer tissues compared with adjacent tissues. Moreover, flow cytometry assays indicated that overexpression of ZNF424 induces apoptosis in A549 human lung carcinoma cells, and overexpression of ZNF424 significantly increases numbers of G1 phase cells and decreases numbers of S phase cells, suggesting that ZNF424 inhibits proliferation. Western Blot analyses show that overexpression of ZNF424 decreases protein expression levels of the mitogen-activated protein kinase (MAPK) signaling proteins P-P38 and P-ERK in A549 cells. Conclusion: These are the first data to associate ZNF424 with tumorigenesis and demonstrate an inhibitory role in lung cancer, indicating the potential of ZNF424 expression as a diagnostic marker of lung tumorigenesis.
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Affiliation(s)
- W Liu
- The Center for Heart Development, State Key Laboratory of Development Biology of Freshwater Fish, Key Laboratory of MOE for Development Biology and Protein Chemistry, The National & Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, Hunan 410081, China
| | - W Yuan
- The Center for Heart Development, State Key Laboratory of Development Biology of Freshwater Fish, Key Laboratory of MOE for Development Biology and Protein Chemistry, The National & Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, Hunan 410081, China
| | - X Li
- The Second Department of Thoracic Surgery, Hunan Cancer Hospital and The Affiliated Cancer Hospital of Xianga School of Medicine, Central South University, Changsha, Hunan 410013, China
| | - J Zhuang
- Department of Cardiac Surgery, Guangdong Cardiovascular Institute, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong 510100, China
| | - X Mo
- The Center for Heart Development, State Key Laboratory of Development Biology of Freshwater Fish, Key Laboratory of MOE for Development Biology and Protein Chemistry, The National & Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, Hunan 410081, China
| | - G Dai
- The Center for Heart Development, State Key Laboratory of Development Biology of Freshwater Fish, Key Laboratory of MOE for Development Biology and Protein Chemistry, The National & Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, Hunan 410081, China
| | - Y Wang
- The Center for Heart Development, State Key Laboratory of Development Biology of Freshwater Fish, Key Laboratory of MOE for Development Biology and Protein Chemistry, The National & Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, Hunan 410081, China
| | - J Chen
- Department of Cardiac Surgery, Guangdong Cardiovascular Institute, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong 510100, China
| | - Y Wan
- The Center for Heart Development, State Key Laboratory of Development Biology of Freshwater Fish, Key Laboratory of MOE for Development Biology and Protein Chemistry, The National & Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, Hunan 410081, China
| | - Y Li
- The Center for Heart Development, State Key Laboratory of Development Biology of Freshwater Fish, Key Laboratory of MOE for Development Biology and Protein Chemistry, The National & Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, Hunan 410081, China
| | - X Zhu
- Department of Cardiac Surgery, Guangdong Cardiovascular Institute, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong 510100, China
| | - Y Chen
- The Center for Heart Development, State Key Laboratory of Development Biology of Freshwater Fish, Key Laboratory of MOE for Development Biology and Protein Chemistry, The National & Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, Hunan 410081, China
| | - S Luo
- The Center for Heart Development, State Key Laboratory of Development Biology of Freshwater Fish, Key Laboratory of MOE for Development Biology and Protein Chemistry, The National & Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, Hunan 410081, China
| | - Z Jiang
- The Center for Heart Development, State Key Laboratory of Development Biology of Freshwater Fish, Key Laboratory of MOE for Development Biology and Protein Chemistry, The National & Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, Hunan 410081, China
| | - Y Shi
- The Center for Heart Development, State Key Laboratory of Development Biology of Freshwater Fish, Key Laboratory of MOE for Development Biology and Protein Chemistry, The National & Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, Hunan 410081, China
| | - F Chen
- The Center for Heart Development, State Key Laboratory of Development Biology of Freshwater Fish, Key Laboratory of MOE for Development Biology and Protein Chemistry, The National & Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, Hunan 410081, China
| | - L Cao
- The Center for Heart Development, State Key Laboratory of Development Biology of Freshwater Fish, Key Laboratory of MOE for Development Biology and Protein Chemistry, The National & Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, Hunan 410081, China
| | - X Ye
- The Center for Heart Development, State Key Laboratory of Development Biology of Freshwater Fish, Key Laboratory of MOE for Development Biology and Protein Chemistry, The National & Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, Hunan 410081, China
| | - X Fan
- The Center for Heart Development, State Key Laboratory of Development Biology of Freshwater Fish, Key Laboratory of MOE for Development Biology and Protein Chemistry, The National & Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, Hunan 410081, China
| | - P Zhu
- Department of Cardiac Surgery, Guangdong Cardiovascular Institute, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong 510100, China
| | - K Zhang
- The National Clinical Research Center for Geriatrics, Xiangya Hospital of Central South University, Changsha, Hunan 410008, China
| | - X Wu
- The Center for Heart Development, State Key Laboratory of Development Biology of Freshwater Fish, Key Laboratory of MOE for Development Biology and Protein Chemistry, The National & Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, Hunan 410081, China
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Zhang Y, Li G, Liu X, Song Y, Xie J, Li G, Ren J, Wang H, Mou J, Dai J, Liu F, Guo L. Sorafenib inhibited cell growth through the MEK/ERK signaling pathway in acute promyelocytic leukemia cells. Oncol Lett 2018; 15:5620-5626. [PMID: 29552199 PMCID: PMC5840677 DOI: 10.3892/ol.2018.8010] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 10/20/2017] [Indexed: 12/12/2022] Open
Abstract
The present study assessed the mechanism underlying the effect of sorafenib on the proliferation and apoptosis of the acute promyelocytic leukemia (APL) cell line NB4. NB4 cells were treated with different concentrations of sorafenib (0, 1.5, 3, 6, and 12 µM) for 24, 48 and 72 h. Cell proliferation, cell cycle, and apoptosis were analyzed using an MTT assay and flow cytometry analysis, respectively. Reverse transcription-semi-quantitative polymerase chain reaction and western blot analysis were performed to assess the expression of caspase-3, caspase-8, myeloid cell leukemia (MCL)1, cyclin D1, mitogen-activated protein kinase (MEK), phosphorylated (P)-MEK, extracellular signal-regulated kinase (ERK) and P-ERK. The results of the MTT assay demonstrated that, compared with untreated cells, the proliferation of sorafenib-treated NB4 cells was inhibited dose- and time-dependently. Furthermore, cell cycle arrest was induced in the G0/G1 phase and cell apoptosis was promoted in a dose-dependent manner in sorafenib-treated NB4 cells compared with untreated cells. In addition, the expression of the proapoptotic molecules caspase-3 and caspase-8 was significantly upregulated, and the expression of the antiapoptotic molecule MCL1 and the cell cycle-associated cyclin D1 was downregulated in sorafenib-treated NB4 cells compared with untreated cells. Furthermore, the phosphorylation of MEK and ERK was inhibited in sorafenib-treated NB4 cells compared with untreated cells. Sorafenib may inhibit proliferation and induce cell cycle arrest and apoptosis in APL cells. The underlying mechanisms of such effects may be associated with alterations to the expression of apoptosis-associated and cell cycle-associated molecules via MEK/ERK signaling pathway inhibition.
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Affiliation(s)
- Yunjie Zhang
- Institute of Hematology, Xi'an Central Hospital, Xi'an, Shaanxi 710003, P.R. China.,Department of Hematology, The First Affiliated Hospital of Xi'an Jiaotong University School of Medicine, Xi'an, Shaanxi 710061, P.R. China
| | - Gangcan Li
- Institute of Hematology, Xi'an Central Hospital, Xi'an, Shaanxi 710003, P.R. China
| | - Xin Liu
- Department of Hematology, The First Affiliated Hospital of Xi'an Jiaotong University School of Medicine, Xi'an, Shaanxi 710061, P.R. China
| | - Yanping Song
- Institute of Hematology, Xi'an Central Hospital, Xi'an, Shaanxi 710003, P.R. China
| | - Jia Xie
- Institute of Hematology, Xi'an Central Hospital, Xi'an, Shaanxi 710003, P.R. China
| | - Guang Li
- Institute of Hematology, Xi'an Central Hospital, Xi'an, Shaanxi 710003, P.R. China
| | - Jingjing Ren
- Institute of Hematology, Xi'an Central Hospital, Xi'an, Shaanxi 710003, P.R. China
| | - Hao Wang
- Institute of Hematology, Xi'an Central Hospital, Xi'an, Shaanxi 710003, P.R. China
| | - Jiao Mou
- Institute of Hematology, Xi'an Central Hospital, Xi'an, Shaanxi 710003, P.R. China
| | - Jinqian Dai
- Institute of Hematology, Xi'an Central Hospital, Xi'an, Shaanxi 710003, P.R. China
| | - Feng Liu
- Institute of Hematology, Xi'an Central Hospital, Xi'an, Shaanxi 710003, P.R. China
| | - Liang Guo
- Institute of Hematology, Xi'an Central Hospital, Xi'an, Shaanxi 710003, P.R. China
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Santulli P, Marcellin L, Tosti C, Chouzenoux S, Cerles O, Borghese B, Batteux F, Chapron C. MAP kinases and the inflammatory signaling cascade as targets for the treatment of endometriosis? Expert Opin Ther Targets 2015; 19:1465-83. [PMID: 26389657 DOI: 10.1517/14728222.2015.1090974] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
INTRODUCTION The pathogenesis of endometriosis, a common benign disease, remains ill-defined, although it is clear that chronic inflammation plays a crucial role through mitogen-activated protein kinase (MAPK) signaling pathways. All current medical therapies for endometriosis are antigonadotropic, and therefore have a contraceptive effect. A concerted research effort is hence warranted with the aim of delivering novel therapeutics that reduces disease symptoms without blocking ovulation. AREAS COVERED The authors review the complex pathogenic mechanisms of chronic inflammation in endometriosis and their relationships with MAPK pathways. The authors conducted a literature search of descriptive and functional targeted validation of MAPK in the pathogenesis of endometriosis. The effects of MAPK inhibitors, which constitute potential agents for future treatments, are also described. EXPERT OPINION Preliminary studies have highlighted a crucial role for MAPK in driving endometriosis-related inflammation. MAPK inhibitors exhibit potent activity in terms of controlling growth of endometriosis lesions both in vitro and in animal models. As MAPK inhibitors are known to have a multitude of undesirable side effects, their use in humans has to be approached with great care. Indeed, use of these drugs would probably be limited to short exposures prior to surgery in cases involving the most severe disease phenotypes.
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Affiliation(s)
- Pietro Santulli
- a 1 Université Paris Descartes, Sorbonne Paris Cité, Faculté de Médecine, Assistance Publique - Hôpitaux de Paris (AP- HP), Groupe Hospitalier Universitaire (GHU) Ouest, Centre Hospitalier Universitaire (CHU) Cochin, Department of Gynecology Obstetrics II and Reproductive Medicine , 75679 Paris, France +33 1 58 41 36 72 ; .,b 2 Université Paris Descartes, Sorbonne Paris Cité, Department "Development, Reproduction and Cancer," Institut Cochin , INSERM U1016, Equipe Pr Batteux, Paris, France
| | - Louis Marcellin
- a 1 Université Paris Descartes, Sorbonne Paris Cité, Faculté de Médecine, Assistance Publique - Hôpitaux de Paris (AP- HP), Groupe Hospitalier Universitaire (GHU) Ouest, Centre Hospitalier Universitaire (CHU) Cochin, Department of Gynecology Obstetrics II and Reproductive Medicine , 75679 Paris, France +33 1 58 41 36 72 ; .,b 2 Université Paris Descartes, Sorbonne Paris Cité, Department "Development, Reproduction and Cancer," Institut Cochin , INSERM U1016, Equipe Pr Batteux, Paris, France
| | - Claudia Tosti
- c 3 University of Siena, Obstetrics and Gynecology, Department of Molecular and Developmental Medicine , Siena, Italy
| | - Sandrine Chouzenoux
- b 2 Université Paris Descartes, Sorbonne Paris Cité, Department "Development, Reproduction and Cancer," Institut Cochin , INSERM U1016, Equipe Pr Batteux, Paris, France
| | - Olivier Cerles
- b 2 Université Paris Descartes, Sorbonne Paris Cité, Department "Development, Reproduction and Cancer," Institut Cochin , INSERM U1016, Equipe Pr Batteux, Paris, France
| | - Bruno Borghese
- a 1 Université Paris Descartes, Sorbonne Paris Cité, Faculté de Médecine, Assistance Publique - Hôpitaux de Paris (AP- HP), Groupe Hospitalier Universitaire (GHU) Ouest, Centre Hospitalier Universitaire (CHU) Cochin, Department of Gynecology Obstetrics II and Reproductive Medicine , 75679 Paris, France +33 1 58 41 36 72 ; .,b 2 Université Paris Descartes, Sorbonne Paris Cité, Department "Development, Reproduction and Cancer," Institut Cochin , INSERM U1016, Equipe Pr Batteux, Paris, France
| | - Frédéric Batteux
- b 2 Université Paris Descartes, Sorbonne Paris Cité, Department "Development, Reproduction and Cancer," Institut Cochin , INSERM U1016, Equipe Pr Batteux, Paris, France.,d 4 Hôpital Cochin, Department of Immunology , AP-HP, 75679 Paris cedex 14, France
| | - Charles Chapron
- a 1 Université Paris Descartes, Sorbonne Paris Cité, Faculté de Médecine, Assistance Publique - Hôpitaux de Paris (AP- HP), Groupe Hospitalier Universitaire (GHU) Ouest, Centre Hospitalier Universitaire (CHU) Cochin, Department of Gynecology Obstetrics II and Reproductive Medicine , 75679 Paris, France +33 1 58 41 36 72 ; .,b 2 Université Paris Descartes, Sorbonne Paris Cité, Department "Development, Reproduction and Cancer," Institut Cochin , INSERM U1016, Equipe Pr Batteux, Paris, France
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Liu H, Jian Q, Xue K, Ma C, Xie F, Wang R, Liao W, Liu Y, Chi S, Li C. The MEK/ERK signalling cascade is required for sonic hedgehog signalling pathway-mediated enhancement of proliferation and inhibition of apoptosis in normal keratinocytes. Exp Dermatol 2014; 23:896-901. [PMID: 25256290 DOI: 10.1111/exd.12556] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/21/2014] [Indexed: 12/24/2022]
Affiliation(s)
- Haiyan Liu
- Department of Dermatology; Xijing Hospital; the Fourth Military Medical University; Xi'an China
- Department of Dermatology; Lanzhou General Hospital, Lanzhou Military District; Lanzhou China
| | - Qiang Jian
- Department of Dermatology; Xijing Hospital; the Fourth Military Medical University; Xi'an China
| | - Ke Xue
- Department of Dermatology; Xijing Hospital; the Fourth Military Medical University; Xi'an China
| | - Cuiling Ma
- Department of Dermatology; Xijing Hospital; the Fourth Military Medical University; Xi'an China
| | - Fang Xie
- Department of Dermatology; Chinese People's Liberation Army General Hospital; Beijing China
| | - Rui Wang
- Department of Dermatology; Chinese People's Liberation Army General Hospital; Beijing China
| | - Wenjun Liao
- Department of Dermatology; Xijing Hospital; the Fourth Military Medical University; Xi'an China
| | - Yufeng Liu
- Department of Dermatology; Xijing Hospital; the Fourth Military Medical University; Xi'an China
| | - Sumin Chi
- Department of Physiology; the Fourth Military Medical University; Xi'an China
| | - Chengxin Li
- Department of Dermatology; Xijing Hospital; the Fourth Military Medical University; Xi'an China
- Department of Dermatology; Chinese People's Liberation Army General Hospital; Beijing China
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You Y, Wen R, Pathak R, Li A, Li W, St Clair D, Hauer-Jensen M, Zhou D, Liang Y. Latexin sensitizes leukemogenic cells to gamma-irradiation-induced cell-cycle arrest and cell death through Rps3 pathway. Cell Death Dis 2014; 5:e1493. [PMID: 25341047 PMCID: PMC4237263 DOI: 10.1038/cddis.2014.443] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Revised: 09/04/2014] [Accepted: 09/08/2014] [Indexed: 11/09/2022]
Abstract
Leukemia is a leading cause of cancer death. Recently, the latexin (Lxn) gene was identified as a potential tumor suppressor in several types of solid tumors and lymphoma, and Lxn expression was found to be absent or downregulated in leukemic cells. Whether Lxn functions as a tumor suppressor in leukemia and what molecular and cellular mechanisms are involved are unknown. In this study, the myeloid leukemogenic FDC-P1 cell line was used as a model system and Lxn was ectopically expressed in these cells. Using the protein pull-down assay and mass spectrometry, ribosomal protein subunit 3 (Rps3) was identified as a novel Lxn binding protein. Ectopic expression of Lxn inhibited FDC-P1 growth in vitro. More surprisingly, Lxn enhanced gamma irradiation-induced DNA damages and induced cell-cycle arrest and massive necrosis, leading to depletion of FDC-P1 cells. Mechanistically, Lxn inhibited the nuclear translocation of Rps3 upon radiation, resulting in abnormal mitotic spindle formation and chromosome instability. Rps3 knockdown increased the radiation sensitivity of FDC-P1, confirming that the mechanism of action of Lxn is mediated by Rps3 pathway. Moreover, Lxn enhanced the cytotoxicity of chemotherapeutic agent, VP-16, on FDC-P1 cells. Our study suggests that Lxn itself not only suppresses leukemic cell growth but also potentiates the cytotoxic effect of radio- and chemotherapy on cancer cells. Lxn could be a novel molecular target that improves the efficacy of anti-cancer therapy.
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Affiliation(s)
- Y You
- Department of Internal Medicine, University of Kentucky, Lexington, KY 40536, USA
| | - R Wen
- Department of Internal Medicine, University of Kentucky, Lexington, KY 40536, USA
| | - R Pathak
- Division of Radiation Health, Department of Pharmaceutical Sciences, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - A Li
- Department of Pathology, Harvard Medical School, Boston, MA 02115, USA
| | - W Li
- Department of Internal Medicine, University of Kentucky, Lexington, KY 40536, USA
| | - D St Clair
- Gratuate Center for Toxicology, University of Kentucky, Lexington, KY 40536, USA
| | - M Hauer-Jensen
- Division of Radiation Health, Department of Pharmaceutical Sciences, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - D Zhou
- Division of Radiation Health, Department of Pharmaceutical Sciences, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Y Liang
- 1] Department of Internal Medicine, University of Kentucky, Lexington, KY 40536, USA [2] Gratuate Center for Toxicology, University of Kentucky, Lexington, KY 40536, USA
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Blalock WL, Piazzi M, Bavelloni A, Raffini M, Faenza I, D'Angelo A, Cocco L. Identification of the PKR nuclear interactome reveals roles in ribosome biogenesis, mRNA processing and cell division. J Cell Physiol 2014; 229:1047-60. [PMID: 24347309 DOI: 10.1002/jcp.24529] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Accepted: 12/05/2013] [Indexed: 01/08/2023]
Abstract
The double-strand RNA-dependent protein kinase, PKR, plays a central role in inflammatory/chronic stress-mediated pathologies such as cancer, diabetes, and neuro/muscular degenerative diseases. Although a significant amount of research has been conducted to elucidate the role of PKR signaling in the cytosol, only recently has attention been paid to the role of PKR in the nuclear compartment. Previously our group reported that phosphorylated forms of PKR are present in the nucleus of acute leukemic cell lines, representing a reservoir of active kinase that responds to stress. Using the CCRF-CEM acute T-cell leukemia cell line, a PKR-specific inhibitor, co-immunoprecipitation and a proteomics approach, which included affinity purified mass spectrometry analysis (AP/MS), we identified the proteins present in active and inactive PKR nuclear complexes. Of the proteins identified in the PKR complexes, sixty-nine (69) were specific to the active complex, while thirty-eight (38) were specific to the inactive complex. An additional thirteen (13) proteins associated specifically with both complexes. The majority of the proteins identified are involved in, ribosome biogenesis, RNA splicing, mRNA stability, gene expression, cell cycle, or chromatin organization, including several with known significance to normal hematopoiesis and/or hematological disease. In agreement with the AP/MS data, basal- or over-expression of PKR under normal growth conditions favored cell proliferation in the tested cell lines, whereas pharmacological inhibition of PKR or shRNA-mediated knock-down did not. PKR was also found to influence the isoform and the level of expression of the proto-oncogene MYC.
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Affiliation(s)
- William L Blalock
- CNR-NationalResearch Council of Italy, Institute of Molecular Genetics, Bologna, Italy; SC Laboratory of Musculoskeletal Cell Biology, Rizzoli Orthopedic Institute, Bologna, Italy
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Abstract
Despite the significant advances in clinical research, surgical resection, radiotherapy and chemotherapy are still used as the primary method for cancer treatment. As compared to conventional therapies that often induce systemic toxicity and eventually contribute to tumor resistance, the TNF-related apoptosis-inducing ligand (TRAIL) is a promising anticancer agent that selectively triggers apoptosis in various cancer cells by interacting with its proapoptotic receptors DR4 and KILLER/DR5, while sparing the normal surrounding tissue. The intensive studies of TRAIL signaling pathways over the past decade have provided clues for understanding the molecular mechanisms of TRAIL-induced apoptosis in carcinogenesis and identified an array of therapeutic responses elicited by TRAIL and its receptor agonists. Analysis of its activity at the molecular level has shown that TRAIL improves survival either as monotherapies or combinatorial therapies with other mediators of apoptosis or anticancer chemotherapy. Combinatorial treatments amplify the activities of anticancer agents and widen the therapeutic window by overcoming tumor resistance to apoptosis and driving cancer cells to self-destruction. Although TRAIL sensitivity varies widely depending on the cell type, nontransformed cells are largely resistant to death mediated by TRAIL Death Receptors (DRs). Genetic alterations in cancer can contribute in tumor progression and often play an important role in evasion of apoptosis by tumor cells. Remarkably, RAS, MYC and HER2 oncogenes have been shown to sensitise tumor cells to TRAIL induced cell death. Here, we summarise the cross-talk of oncogenic and apoptotic pathways and how they can be exploited toward efficient combinatorial therapeutic protocols.
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Affiliation(s)
- Eftychia Oikonomou
- Laboratory of Signal Mediated Gene Expression, Institute of Biology, Medicinal Chemistry and Biotechnology, National Hellenic Research Foundation, 48, Vasileos Konstantinou Ave., 11635, Athens, Greece
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Blandino-Rosano M, Alejandro EU, Sathyamurthy A, Scheys JO, Gregg B, Chen AY, Rachdi L, Weiss A, Barker DJ, Gould AP, Elghazi L, Bernal-Mizrachi E. Enhanced beta cell proliferation in mice overexpressing a constitutively active form of Akt and one allele of p21Cip. Diabetologia 2012; 55:1380-9. [PMID: 22327314 PMCID: PMC3646796 DOI: 10.1007/s00125-012-2465-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Accepted: 12/19/2011] [Indexed: 12/31/2022]
Abstract
AIMS/HYPOTHESIS The ability of pancreatic beta cells to proliferate is critical both for normal tissue maintenance and in conditions where there is an increased demand for insulin. Protein kinase B(Akt) plays a major role in promoting proliferation in many cell types, including the insulin-producing beta cells. We have previously reported that mice overexpressing a constitutively active form of Akt(caAkt (Tg)) show enhanced beta cell proliferation that is associated with increased protein levels of cyclin D1, cyclin D2 and cyclin-dependent kinase inhibitor 1A (p21(Cip)). In the present study, we sought to assess the mechanisms responsible for augmented p21(Cip) levels in caAkt(Tg) mice and test the role of p21(Cip) in the proliferative responses induced by activation of Akt signalling. METHODS To gain a greater understanding of the relationship between Akt and p21(Cip), we evaluated the mechanisms involved in the modulation of p2(Cip) by Akt and the in vivo role of reduced p21(Cip) in proliferative responses induced by Akt. RESULTS Our experiments showed that Akt signalling regulates p21(Cip) transcription and protein stability. caAkt(Tg) /p21(Cip+/-) mice exhibited fasting and fed hypoglycaemia as well as hyperinsulinaemia when compared with caAkt(Tg) mice. Glucose tolerance tests revealed improved glucose tolerance in caAkt(Tg)/p21(Cip+/-) mice compared with caAkt (Tg). These changes resulted from increased proliferation, survival and beta cell mass in caAkt(Tg)/p21(Cip+/-) compared with caAkt(Tg) mice. CONCLUSIONS/INTERPRETATION Our data indicate that increased p21(Cip) levels in caAkt(Tg) mice act as a compensatory brake, protecting beta cells from unrestrained proliferation. These studies imply that p21(Cip) could play important roles in the adaptive responses of beta cells to proliferate in conditions such as in insulin resistance.
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Affiliation(s)
- M. Blandino-Rosano
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan Medical Center, Ann Arbor, MI 48109-0678, USA
| | - E. U. Alejandro
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan Medical Center, Ann Arbor, MI 48109-0678, USA
| | - A. Sathyamurthy
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan Medical Center, Ann Arbor, MI 48109-0678, USA
| | - J. O. Scheys
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan Medical Center, Ann Arbor, MI 48109-0678, USA
| | - B. Gregg
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan Medical Center, Ann Arbor, MI 48109-0678, USA
| | - A. Y. Chen
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan Medical Center, Ann Arbor, MI 48109-0678, USA
| | - L. Rachdi
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan Medical Center, Ann Arbor, MI 48109-0678, USA
| | - A. Weiss
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan Medical Center, Ann Arbor, MI 48109-0678, USA
| | - D. J. Barker
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan Medical Center, Ann Arbor, MI 48109-0678, USA
| | - A. P. Gould
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan Medical Center, Ann Arbor, MI 48109-0678, USA
| | - L. Elghazi
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan Medical Center, Ann Arbor, MI 48109-0678, USA
| | - E. Bernal-Mizrachi
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan Medical Center, Ann Arbor, MI 48109-0678, USA
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10
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Zhang J, Chen YH, Lu Q. Pro-oncogenic and anti-oncogenic pathways: opportunities and challenges of cancer therapy. Future Oncol 2010; 6:587-603. [PMID: 20373871 DOI: 10.2217/fon.10.15] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Carcinogenesis is the uncontrolled growth of cells gaining the potential to invade and disrupt vital tissue functions. This malignant process includes the occurrence of 'unwanted' gene mutations that induce the transformation of normal cells, for example, by overactivation of pro-oncogenic pathways and inactivation of tumor-suppressive or anti-oncogenic pathways. It is now recognized that the number of major signaling pathways that control oncogenesis is not unlimited; therefore, suppressing these pathways can conceivably lead to a cancer cure. However, the clinical application of cancer intervention has not matched up to scientific expectations. Increasing numbers of studies have revealed that many oncogenic-signaling elements show double faces, in which they can promote or suppress cancer pathogenesis depending on tissue type, cancer stage, gene dosage and their interaction with other players in carcinogenesis. This complexity of oncogenic signaling poses challenges to traditional cancer therapy and calls for considerable caution when designing an anticancer drug strategy. We propose future oncology interventions with the concept of integrative cancer therapy.
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Affiliation(s)
- Jiao Zhang
- Department of Anatomy & Cell Biology, The Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA
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11
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Abrams SL, Steelman LS, Shelton JG, Chappell W, Bäsecke J, Stivala F, Donia M, Nicoletti F, Libra M, Martelli AM, McCubrey JA. Enhancing therapeutic efficacy by targeting non-oncogene addicted cells with combinations of signal transduction inhibitors and chemotherapy. Cell Cycle 2010; 9:1839-46. [PMID: 20436269 DOI: 10.4161/cc.9.9.11544] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The effects of inhibition of the Raf/MEK/ERK and PI3K/Akt/mTOR signaling pathways and chemotherapeutic drugs on cell cycle progression and drug sensitivity were examined in cytokine-dependent FL5.12 hematopoietic cells. We examined their effects, as these cells resemble normal hematopoietic precursor cells as they do not exhibit "oncogene-addicted" growth, while they do display "cytokine-addicted" proliferation as cytokine removal resulted in apoptosis in greater than 80% of the cells within 48 hrs. When cytokine-dependent FL5.12 cells were cultured in the presence of IL-3, which stimulated multiple proliferation and anti-apoptotic cascades, MEK, PI3K and mTOR inhibitors transiently suppressed but did not totally inhibit cell cycle progression or induce apoptosis while chemotherapeutic drugs such as doxorubicin and paclitaxel were more effective in inducing cell cycle arrest and apoptosis. Doxorubicin induced a G(1) block, while paclitaxel triggered a G(2)/M block. Doxorubicin was more effective in inducing cell death than paclitaxel. Furthermore the effects of doxorubicin could be enhanced by addition of MEK, PI3K or mTOR inhibitors. Cytokine-dependent cells which proliferate in vitro and are not "oncogene-addicted" may represent a pre-malignant stage, more refractory to treatment with targeted therapy. However, these cells are sensitive to chemotherapeutic drugs. It is important to develop methods to inhibit the growth of such cytokine-dependent cells as they may resemble the leukemia stem cell and other cancer initiating cells. These results demonstrate the enhanced effectiveness of targeting early hematopoietic progenitor cells with combinations of chemotherapeutic drugs and signal transduction inhibitors.
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Affiliation(s)
- Stephen L Abrams
- Department of Microbiology and Immunology, Brody School of Medicine at East Carolina University, Greenville, NC, USA
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12
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Abrams SL, Steelman LS, Shelton JG, Wong EWT, Chappell WH, Bäsecke J, Stivala F, Donia M, Nicoletti F, Libra M, Martelli AM, McCubrey JA. The Raf/MEK/ERK pathway can govern drug resistance, apoptosis and sensitivity to targeted therapy. Cell Cycle 2010; 9:1781-91. [PMID: 20436278 DOI: 10.4161/cc.9.9.11483] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The effects of the Raf/MEK/ERK and PI3K/PTEN/Akt/mTOR signaling pathways on proliferation, drug resistance, prevention of apoptosis and sensitivity to signal transduction inhibitors were examined in FL/DeltaAkt-1:ER*(Myr(+)) + DeltaRaf-1:AR cells which are conditionally-transformed to grow in response to Raf and Akt activation. Drug resistant cells were isolated from FL/DeltaAkt-1:ER*(Myr(+)) + DeltaRaf-1:AR cells in the presence of doxorubicin. Activation of Raf-1, in the drug resistant FL/DeltaAkt-1:ER*(Myr(+)) + DeltaRaf-1:AR cells, increased the IC(50) for doxorubicin 80-fold, whereas activation of Akt-1, by itself, had no effect on the doxorubicin IC50. However, Akt-1 activation enhanced cell proliferation and clonogenicity in the presence of chemotherapeutic drugs. Thus the Raf/MEK/ERK pathway had profound effects on the sensitivity to chemotherapeutic drugs, and Akt-1 activation was required for the long term growth of these cells as well as resistance to chemotherapeutic drugs. The effects of doxorubicin on the induction of apoptosis in the drug resistant cells were enhanced by addition of either mTOR and MEK inhibitors. These results indicate that targeting the Raf/MEK/ERK and PI3K/Akt/mTOR pathways may be an effective approach for therapeutic intervention in drug resistant cancers that have mutations activating these cascades.
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Affiliation(s)
- Stephen L Abrams
- Department of Microbiology and Immunology, Brody School of Medicine at East Carolina University, Greenville, NC, USA
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13
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Steelman LS, Abrams SL, Shelton JG, Chappell WH, Bäsecke J, Stivala F, Donia M, Nicoletti F, Libra M, Martelli AM, McCubrey JA. Dominant roles of the Raf/MEK/ERK pathway in cell cycle progression, prevention of apoptosis and sensitivity to chemotherapeutic drugs. Cell Cycle 2010; 9:1629-38. [PMID: 20372086 DOI: 10.4161/cc.9.8.11487] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The effects of the Raf/MEK/ERK and PI3K/PTEN/Akt/mTOR signaling pathways on cell cycle progression, gene expression, prevention of apoptosis and sensitivity to chemotherapeutic drugs were examined in FL/ΔAkt-1:ER*(Myr(+)) + ΔRaf-1:AR cells which are conditionally-transformed to grow in response to Raf-1 and Akt-1 activation by treatment with testosterone or tamoxifen respectively. In these cells we can compare the effects of normal cytokine vs. oncogene mediated signaling in the same cells by changing the culture conditions. Raf-1 was more effective than Akt-1 in inducing cell cycle progression and preventing apoptosis in the presence and absence of chemotherapeutic drugs. The normal cytokine for these cells, interleukin-3 induced/activated most downstream genes transiently, with the exception of p70S6K that was induced for prolonged periods of time. In contrast, most of the downstream genes induced by either the activate Raf-1 or Akt-1 oncogenes were induced for prolonged periods of time, documenting the differences between cytokine and oncogene mediated gene induction which has important therapeutic consequences. The FL/ΔAkt-1:ER*(Myr(+)) + ΔRaf-1:AR cells were sensitive to MEK and PI3K/mTOR inhibitors. Combining MEK and PI3K/mTOR inhibitors increased the induction of apoptosis. The effects of doxorubicin on the induction of apoptosis could be enhanced with MEK, PI3K and mTOR inhibitors. Targeting the Raf/MEK/ERK and PI3K/PTEN/Akt/mTOR pathways may be an effective approach for therapeutic intervention in those cancers which have upstream mutations which result in activation of these pathways.
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Affiliation(s)
- Linda S Steelman
- Department of Microbiology and Immunology, Brody School of Medicine at East Carolina University, Greenville, NC, USA
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14
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Gaglio D, Soldati C, Vanoni M, Alberghina L, Chiaradonna F. Glutamine deprivation induces abortive s-phase rescued by deoxyribonucleotides in k-ras transformed fibroblasts. PLoS One 2009; 4:e4715. [PMID: 19262748 PMCID: PMC2650790 DOI: 10.1371/journal.pone.0004715] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2008] [Accepted: 02/03/2009] [Indexed: 11/27/2022] Open
Abstract
Background Oncogene activation plays a role in metabolic reprogramming of cancer cells. We have previously shown that K-ras transformed fibroblasts have a stronger dependence on glycolysis and a reduced oxidative phosphorylation ability as compared to their normal counterparts. Another metabolic adaptation of cancer cells, that has long been established, is their propensity to exhibit increased glutamine consumption, although the effects induced by glutamine deprivation on cancer cells are still controversial. Methodology and Principal Findings Here, by using nutritional perturbations and molecular physiology, we show that reduction or complete depletion of glutamine availability in K-ras transformed fibroblasts causes a strong decrease of proliferation ability and a slower re-entry of synchronized cells into the cell cycle. The reduced proliferation is accompanied by sustained expression of cyclin D and E, abortive S phase entrance and is dependent on Ras signalling deregulation, since it is rescued by expression of a dominant negative guanine nucleotide exchange factor. The growth potential of transformed cells as well as the ability to execute the G1 to S transition is restored by adding the four deoxyribonucleotides, indicating that the arrest of proliferation of K-ras transformed cells induced by glutamine depletion is largely due to a reduced supply of DNA in the presence of signalling pathways promoting G1 to S transition. Conclusions and Significance Our results suggest that the differential effects of glutamine and glucose on cell viability are not a property of the transformed phenotype per se, but rather depend on the specific pathway being activated in transformation. For instance, myc-overexpressing cells have been reported to die under glutamine depletion and not under glucose shortage, while the opposite holds for ras-transformed fibroblasts as shown in this paper. These different responses of transformed cells to nutritional stress should be taken into account when designing anti-cancer therapies that aim to exploit metabolic differences between normal and transformed cells.
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Affiliation(s)
- Daniela Gaglio
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Milan, Italy
| | - Chiara Soldati
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Milan, Italy
| | - Marco Vanoni
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Milan, Italy
| | - Lilia Alberghina
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Milan, Italy
| | - Ferdinando Chiaradonna
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Milan, Italy
- * E-mail:
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15
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Crystal structure of human CDK4 in complex with a D-type cyclin. Proc Natl Acad Sci U S A 2009; 106:4166-70. [PMID: 19237565 DOI: 10.1073/pnas.0809645106] [Citation(s) in RCA: 167] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The cyclin D1-cyclin-dependent kinase 4 (CDK4) complex is a key regulator of the transition through the G(1) phase of the cell cycle. Among the cyclin/CDKs, CDK4 and cyclin D1 are the most frequently activated by somatic genetic alterations in multiple tumor types. Thus, aberrant regulation of the CDK4/cyclin D1 pathway plays an essential role in oncogenesis; hence, CDK4 is a genetically validated therapeutic target. Although X-ray crystallographic structures have been determined for various CDK/cyclin complexes, CDK4/cyclin D1 has remained highly refractory to structure determination. Here, we report the crystal structure of CDK4 in complex with cyclin D1 at a resolution of 2.3 A. Although CDK4 is bound to cyclin D1 and has a phosphorylated T-loop, CDK4 is in an inactive conformation and the conformation of the heterodimer diverges from the previously known CDK/cyclin binary complexes, which suggests a unique mechanism for the process of CDK4 regulation and activation.
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16
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McCubrey JA, Steelman LS, Chappell WH, Abrams SL, Wong EWT, Chang F, Lehmann B, Terrian DM, Milella M, Tafuri A, Stivala F, Libra M, Basecke J, Evangelisti C, Martelli AM, Franklin RA. Roles of the Raf/MEK/ERK pathway in cell growth, malignant transformation and drug resistance. BIOCHIMICA ET BIOPHYSICA ACTA 2007; 1773:1263-84. [PMID: 17126425 PMCID: PMC2696318 DOI: 10.1016/j.bbamcr.2006.10.001] [Citation(s) in RCA: 1684] [Impact Index Per Article: 99.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2006] [Revised: 10/02/2006] [Accepted: 10/03/2006] [Indexed: 02/07/2023]
Abstract
Growth factors and mitogens use the Ras/Raf/MEK/ERK signaling cascade to transmit signals from their receptors to regulate gene expression and prevent apoptosis. Some components of these pathways are mutated or aberrantly expressed in human cancer (e.g., Ras, B-Raf). Mutations also occur at genes encoding upstream receptors (e.g., EGFR and Flt-3) and chimeric chromosomal translocations (e.g., BCR-ABL) which transmit their signals through these cascades. Even in the absence of obvious genetic mutations, this pathway has been reported to be activated in over 50% of acute myelogenous leukemia and acute lymphocytic leukemia and is also frequently activated in other cancer types (e.g., breast and prostate cancers). Importantly, this increased expression is associated with a poor prognosis. The Ras/Raf/MEK/ERK and Ras/PI3K/PTEN/Akt pathways interact with each other to regulate growth and in some cases tumorigenesis. For example, in some cells, PTEN mutation may contribute to suppression of the Raf/MEK/ERK cascade due to the ability of activated Akt to phosphorylate and inactivate different Rafs. Although both of these pathways are commonly thought to have anti-apoptotic and drug resistance effects on cells, they display different cell lineage specific effects. For example, Raf/MEK/ERK is usually associated with proliferation and drug resistance of hematopoietic cells, while activation of the Raf/MEK/ERK cascade is suppressed in some prostate cancer cell lines which have mutations at PTEN and express high levels of activated Akt. Furthermore the Ras/Raf/MEK/ERK and Ras/PI3K/PTEN/Akt pathways also interact with the p53 pathway. Some of these interactions can result in controlling the activity and subcellular localization of Bim, Bak, Bax, Puma and Noxa. Raf/MEK/ERK may promote cell cycle arrest in prostate cells and this may be regulated by p53 as restoration of wild-type p53 in p53 deficient prostate cancer cells results in their enhanced sensitivity to chemotherapeutic drugs and increased expression of Raf/MEK/ERK pathway. Thus in advanced prostate cancer, it may be advantageous to induce Raf/MEK/ERK expression to promote cell cycle arrest, while in hematopoietic cancers it may be beneficial to inhibit Raf/MEK/ERK induced proliferation and drug resistance. Thus the Raf/MEK/ERK pathway has different effects on growth, prevention of apoptosis, cell cycle arrest and induction of drug resistance in cells of various lineages which may be due to the presence of functional p53 and PTEN and the expression of lineage specific factors.
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Affiliation(s)
- James A McCubrey
- Department of Microbiology and Immunology, Leo Jenkins Cancer Center, Brody School of Medicine at East Carolina University, Greenville, NC 27858, USA.
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17
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Bockstaele L, Coulonval K, Kooken H, Paternot S, Roger PP. Regulation of CDK4. Cell Div 2006; 1:25. [PMID: 17092340 PMCID: PMC1647274 DOI: 10.1186/1747-1028-1-25] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2006] [Accepted: 11/08/2006] [Indexed: 12/19/2022] Open
Abstract
Cyclin-dependent kinase (CDK)4 is a master integrator that couples mitogenic and antimitogenic extracellular signals with the cell cycle. It is also crucial for many oncogenic transformation processes. In this overview, we address various molecular features of CDK4 activation that are critical but remain poorly known or debated, including the regulation of its association with D-type cyclins, its subcellular location, its activating Thr172-phosphorylation and the roles of Cip/Kip CDK "inhibitors" in these processes. We have recently identified the T-loop phosphorylation of CDK4, but not of CDK6, as a determining target for cell cycle control by extracellular factors, indicating that CDK4-activating kinase(s) might have to be reconsidered.
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Affiliation(s)
- Laurence Bockstaele
- Institute of Interdisciplinary Research (IRIBHM), Faculté de Médecine, Université Libre de Bruxelles, Campus Erasme, B-1070 Brussels, Belgium
| | - Katia Coulonval
- Institute of Interdisciplinary Research (IRIBHM), Faculté de Médecine, Université Libre de Bruxelles, Campus Erasme, B-1070 Brussels, Belgium
| | - Hugues Kooken
- Institute of Interdisciplinary Research (IRIBHM), Faculté de Médecine, Université Libre de Bruxelles, Campus Erasme, B-1070 Brussels, Belgium
| | - Sabine Paternot
- Institute of Interdisciplinary Research (IRIBHM), Faculté de Médecine, Université Libre de Bruxelles, Campus Erasme, B-1070 Brussels, Belgium
| | - Pierre P Roger
- Institute of Interdisciplinary Research (IRIBHM), Faculté de Médecine, Université Libre de Bruxelles, Campus Erasme, B-1070 Brussels, Belgium
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18
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McCubrey JA, Steelman LS, Abrams SL, Lee JT, Chang F, Bertrand FE, Navolanic PM, Terrian DM, Franklin RA, D'Assoro AB, Salisbury JL, Mazzarino MC, Stivala F, Libra M. Roles of the RAF/MEK/ERK and PI3K/PTEN/AKT pathways in malignant transformation and drug resistance. ACTA ACUST UNITED AC 2006; 46:249-79. [PMID: 16854453 DOI: 10.1016/j.advenzreg.2006.01.004] [Citation(s) in RCA: 486] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The Ras/Raf/MEK/ERK and PI3K/PTEN/AKT signaling cascades play critical roles in the transmission of signals from growth factor receptors to regulate gene expression and prevent apoptosis. Components of these pathways are mutated or aberrantly expressed in human cancer (e.g., Ras, B-Raf, PI3K, PTEN, Akt). Also, mutations occur at genes encoding upstream receptors (e.g., EGFR and Flt-3) and chimeric chromosomal translocations (e.g., BCR-ABL) which transmit their signals through these cascades. These pathways interact with each other to regulate growth and in some cases tumorigenesis. For example, in some cells, PTEN mutation may contribute to suppression of the Raf/MEK/ERK cascade due to the ability of elevated activated Akt levels to phosphorylate and inactivate Raf-1. We have investigated the genetic structures and functional roles of these two signaling pathways in the malignant transformation and drug resistance of hematopoietic, breast and prostate cancer cells. Although both of these pathways are commonly thought to have anti-apoptotic and drug resistance effects on cells, they display different cell-lineage-specific effects. Induced Raf expression can abrogate the cytokine dependence of certain hematopoietic cell lines (FDC-P1 and TF-1), a trait associated with tumorigenesis. In contrast, expression of activated PI3K or Akt does not abrogate the cytokine dependence of these hematopoietic cell lines, but does have positive effects on cell survival. However, activated PI3K and Akt can synergize with activated Raf to abrogate the cytokine dependence of another hematopoietic cell line (FL5.12) which is not transformed by activated Raf expression by itself. Activated Raf and Akt also confer a drug-resistant phenotype to these cells. Raf is more associated with proliferation and the prevention of apoptosis while Akt is more associated with the long-term clonogenicity. In breast cancer cells, activated Raf conferred resistance to the chemotherapeutic drugs doxorubicin and paclitaxel. Raf induced the expression of the drug pump Mdr-1 (a.k.a., Pgp) and the Bcl-2 anti-apoptotic protein. Raf did not appear to induce drug resistance by altering p53/p21Cip-1 expression, whose expression is often linked to regulation of cell cycle progression and drug resistance. Deregulation of the PI3K/PTEN/Akt pathway was associated with resistance to doxorubicin and 4-hydroxyl tamoxifen, a chemotherapeutic drug and estrogen receptor antagonist used in breast cancer therapy. In contrast to the drug-resistant breast cancer cells obtained after overexpression of activated Raf, cells expressing activated Akt displayed altered (decreased) levels of p53/p21Cip-1. Deregulated expression of the central phosphatase in the PI3K/PTEN/Akt pathway led to breast cancer drug resistance. Introduction of mutated forms of PTEN, which lacked lipid phosphatase activity, increased the resistance of the MCF-7 cells to doxorubicin, suggesting that these lipid phosphatase deficient PTEN mutants acted as dominant negative mutants to suppress wild-type PTEN activity. Finally, the PI3K/PTEN/Akt pathway appears to be more prominently involved in prostate cancer drug resistance than the Raf/MEK/ERK pathway. Some advanced prostate cancer cells express elevated levels of activated Akt which may suppress Raf activation. Introduction of activated forms of Akt increased the drug resistance of advanced prostate cancer cells. In contrast, introduction of activated forms of Raf did not increase the drug resistance of the prostate cancer cells. In contrast to the results observed in hematopoietic cells, Raf may normally promote differentiation in prostate cells which is suppressed in advanced prostate cancer due to increased expression of activated Akt arising from PTEN mutation. Thus in advanced prostate cancer it may be advantageous to induce Raf expression to promote differentiation, while in hematopoietic cancers it may be beneficial to inhibit Raf/MEK/ERK-induced proliferation. These signaling and anti-apoptotic pathways can have different effects on growth, prevention of apoptosis and induction of drug resistance in cells of various lineages which may be due to the expression of lineage-specific factors.
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Affiliation(s)
- James A McCubrey
- Department of Microbiology & Immunology, Brody School of Medicine at East Carolina University, Greenville, NC 27858, USA.
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19
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Chiaradonna F, Sacco E, Manzoni R, Giorgio M, Vanoni M, Alberghina L. Ras-dependent carbon metabolism and transformation in mouse fibroblasts. Oncogene 2006; 25:5391-404. [PMID: 16607279 DOI: 10.1038/sj.onc.1209528] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Mutational activation of ras genes is required for the onset and maintenance of different malignancies. Here we show, using a combination of molecular physiology, nutritional perturbations and transcriptional profiling, that full penetrance of phenotypes related to oncogenic Ras activation, including the shift of carbon metabolism towards fermentation and upregulation of key cell cycle regulators, is dependent upon glucose availability. These responses are induced by Ras activation, being specifically reverted by downregulation of the Ras pathway obtained through the expression of a dominant-negative Ras-specific guanine nucleotide exchange protein. Our data allow to link directly to ras activation the alteration in energy metabolism of cancer cells, their fragility towards glucose shortage and ensuing apoptotic death.
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Affiliation(s)
- F Chiaradonna
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Milan, Italy
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20
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Zhang Z, Li M, Rayburn ER, Hill DL, Zhang R, Wang H. Oncogenes as novel targets for cancer therapy (part II): Intermediate signaling molecules. ACTA ACUST UNITED AC 2005; 5:247-57. [PMID: 16078861 DOI: 10.2165/00129785-200505040-00005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
This is the second part of a four-part review on potential therapeutic targeting of oncogenes. The previous part introduced the new technologies responsible for the advancement of oncogene identification, target validation, and drug design. Because of such advances, new specific and more efficient therapeutic agents can be developed for cancer. This part of the review continues the exploration of various oncogenes, which we have grouped within seven categories: growth factors, tyrosine kinases, intermediate signaling molecules, transcription factors, cell cycle regulators, DNA damage repair genes, and genes involved in apoptosis. Part I included a discussion of growth factors and tyrosine kinases. This portion of the review covers intermediate signaling molecules and the various strategies used to inhibit their expression or decrease their activities.
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Affiliation(s)
- Zhuo Zhang
- Department of Pharmacology and Toxicology and Division of Clinical Pharmacology, Birmingham, Alabama 35294-0019, USA
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21
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Katabami M, Donninger H, Hommura F, Leaner VD, Kinoshita I, Chick JFB, Birrer MJ. Cyclin A is a c-Jun target gene and is necessary for c-Jun-induced anchorage-independent growth in RAT1a cells. J Biol Chem 2005; 280:16728-38. [PMID: 15737994 DOI: 10.1074/jbc.m413892200] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Overexpression of c-Jun enables Rat1a cells to grow in an anchorage-independent manner. We used an inducible c-Jun system under the regulation of doxycycline in Rat1a cells to identify potential c-Jun target genes necessary for c-Jun-induced anchorage-independent growth. Induction of c-Jun results in sustained expression of cyclin A in the nonadherent state with only minimal expression in the absence of c-Jun. The promoter activity of cyclin A2 was 4-fold higher in Rat1a cells in which c-Jun expression was induced compared with the control cells. Chromatin immunoprecipitation demonstrated that c-Jun bound directly to the cyclin A2 promoter. Mutation analysis of the cyclin A2 promoter mapped the c-Jun regulatory site to an ATF site at position -80. c-Jun was able to bind to this site both in vitro and in vivo, and mutation of this site completely abolished promoter activity. Cyclin A1 was also elevated in c-Jun-overexpressing Rat1a cells; however, c-Jun did not regulate this gene directly, since it did not bind directly to the cyclin A1 promoter. Suppression of cyclin A expression via the introduction of a cyclin A antisense sequences significantly reduced the ability of c-Jun-overexpressing Rat1a cells to grow in an anchorage-independent fashion. Taken together, these results suggest that cyclin A is a target of c-Jun and is necessary but not sufficient for c-Jun-induced anchorage-independent growth. In addition, we demonstrated that the cytoplasmic oncogenes Ras and Src transcriptionally activated the cyclin A2 promoter via the ATF site at position -80. Using a dominant negative c-Jun mutant, TAM67, we showed that this transcriptional activation of cyclin A2 requires c-Jun. Thus, our results suggest that c-Jun is a mediator of the aberrant cyclin A2 expression associated with Ras/Src-induced transformation.
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Affiliation(s)
- Motoo Katabami
- Department of Cell and Cancer Biology, NCI, National Institutes of Health, Rockville, Maryland 20850, USA
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22
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Akula SM, Ford PW, Whitman AG, Hamden KE, Shelton JG, McCubrey JA. Raf promotes human herpesvirus-8 (HHV-8/KSHV) infection. Oncogene 2004; 23:5227-41. [PMID: 15122343 DOI: 10.1038/sj.onc.1207643] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Human herpesvirus-8 (HHV-8/KSHV) is etiologically associated with Kaposi's sarcoma (KS) and other tumors. Constitutive activation of the mitogen-activated protein kinase (MAPK) signaling pathway has been associated with a variety of tumors, including AIDS-related KS. The oncoprotein Raf is situated at a pivotal position in regulating the MAPK pathway. Hence, we analysed the effect of oncoprotein Raf on HHV-8 infectious entry into target cells. Here we report Raf expression to significantly enhance HHV-8 infection of target cells. These findings implicate a role for Raf not only in the infectious entry of HHV-8 but also in modulating KS pathogenesis.
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Affiliation(s)
- Shaw M Akula
- Department of Microbiology & Immunology, Brody School of Medicine, East Carolina University, Greenville, NC 27858, USA.
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23
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Kehn K, Deng L, de la Fuente C, Strouss K, Wu K, Maddukuri A, Baylor S, Rufner R, Pumfery A, Bottazzi ME, Kashanchi F. The role of cyclin D2 and p21/waf1 in human T-cell leukemia virus type 1 infected cells. Retrovirology 2004; 1:6. [PMID: 15169570 PMCID: PMC420262 DOI: 10.1186/1742-4690-1-6] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2004] [Accepted: 04/13/2004] [Indexed: 11/23/2022] Open
Abstract
Background The human T-cell leukemia virus type 1 (HTLV-1) Tax protein indirectly influences transcriptional activation, signal transduction, cell cycle control, and apoptosis. The function of Tax primarily relies on protein-protein interactions. We have previously shown that Tax upregulates the cell cycle checkpoint proteins p21/waf1 and cyclin D2. Here we describe the consequences of upregulating these G1/S checkpoint regulators in HTLV-1 infected cells. Results To further decipher any physical and functional interactions between cyclin D2 and p21/waf1, we used a series of biochemical assays from HTLV-1 infected and uninfected cells. Immunoprecipitations from HTLV-1 infected cells showed p21/waf1 in a stable complex with cyclin D2/cdk4. This complex is active as it phosphorylates the Rb protein in kinase assays. Confocal fluorescent microscopy indicated that p21/waf1 and cyclin D2 colocalize in HTLV-1 infected, but not in uninfected cells. Furthermore, in vitro kinase assays using purified proteins demonstrated that the addition of p21/waf1 to cyclin D2/cdk4 increased the kinase activity of cdk4. Conclusion These data suggest that the p21/cyclin D2/cdk4 complex is not an inhibitory complex and that p21/waf1 could potentially function as an assembly factor for the cyclin D2/cdk4 complex in HTLV-1 infected cells. A by-product of this assembly with cyclin D2/cdk4 is the sequestration of p21/waf1 away from the cyclin E/cdk2 complex, allowing this active cyclin-cdk complex to phosphorylate Rb pocket proteins efficiently and push cells through the G1/S checkpoint. These two distinct functional and physical activities of p21/waf1 suggest that RNA tumor viruses manipulate the G1/S checkpoint by deregulating cyclin and cdk complexes.
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Affiliation(s)
- Kylene Kehn
- Department of Biochemistry and Molecular Biology, The George Washington University Medical Center, Washington, DC 20037, USA
| | - Longwen Deng
- Department of Biochemistry and Molecular Biology, The George Washington University Medical Center, Washington, DC 20037, USA
| | - Cynthia de la Fuente
- Department of Biochemistry and Molecular Biology, The George Washington University Medical Center, Washington, DC 20037, USA
| | - Katharine Strouss
- Department of Biochemistry and Molecular Biology, The George Washington University Medical Center, Washington, DC 20037, USA
| | - Kaili Wu
- Department of Biochemistry and Molecular Biology, The George Washington University Medical Center, Washington, DC 20037, USA
| | - Anil Maddukuri
- Department of Biochemistry and Molecular Biology, The George Washington University Medical Center, Washington, DC 20037, USA
| | - Shanese Baylor
- Department of Biochemistry and Molecular Biology, The George Washington University Medical Center, Washington, DC 20037, USA
| | - Robyn Rufner
- Center for Microscopy and Image Analysis, The George Washington University Medical Center, Washington, DC 20037, USA
| | - Anne Pumfery
- Department of Biochemistry and Molecular Biology, The George Washington University Medical Center, Washington, DC 20037, USA
| | - Maria Elena Bottazzi
- Department of Microbiology and Tropical Medicine, The George Washington University Medical Center, Washington, DC 20037, USA
| | - Fatah Kashanchi
- Department of Biochemistry and Molecular Biology, The George Washington University Medical Center, Washington, DC 20037, USA
- The Institute for Genomics Research, Rockville, MD 20850, USA
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Liu W, Shen X, Yang Y, Yin X, Xie J, Yan J, Jiang J, Liu W, Wang H, Sun M, Zheng Y, Gu J. Trihydrophobin 1 Is a New Negative Regulator of A-Raf Kinase. J Biol Chem 2004; 279:10167-75. [PMID: 14684750 DOI: 10.1074/jbc.m307994200] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Our previous work indicated that instead of binding to B-Raf or C-Raf, trihydrophobin 1 (TH1) specifically binds to A-Raf kinase both in vitro and in vivo. In this work, we investigated its function further. Using confocal microscopy, we found that TH1 colocalizes with A-Raf, which confirms our former results. The region of TH1 responsible for the interaction with A-Raf is mapped to amino acids 1-372. Coimmunoprecipitation experiments demonstrate that TH1 is associated with A-Raf in both quiescent and serum-stimulated cells. Wild type A-Raf binds increasingly to TH1 when it is activated by serum and/or upstream oncogenic Ras/Src compared with that of "kinase-dead" A-Raf. The latter can still bind to TH1 under the same experimental condition. The binding pattern of A-Raf implies that this interaction is mediated in part by the A-Raf kinase activity. As indicated by Raf protein kinase assays, TH1 inhibits A-Raf kinase, whereas neither B-Raf nor C-Raf kinase activity is influenced. Furthermore, we observed that TH1 inhibited cell cycle progression in TH1 stably transfected 7721 cells compared with mock cells, and flow cell cytometry analysis suggested that the TH1 stably transfected 7721 cells were G(0)/G(1) phase-arrested. Taken together, our data provide a clue to understanding the cellular function of TH1 on Raf isoform-specific regulation.
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Affiliation(s)
- Weicheng Liu
- State Key laboratory of Genetic Engineering and Gene Research Center, Shanghai Medical College of Fudan University, Shanghai 200032, People's Republic of China
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25
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Shelton JG, Moye PW, Steelman LS, Blalock WL, Lee JT, Franklin RA, McMahon M, McCubrey JA. Differential effects of kinase cascade inhibitors on neoplastic and cytokine-mediated cell proliferation. Leukemia 2003; 17:1765-82. [PMID: 12970777 DOI: 10.1038/sj.leu.2403052] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The Raf/MEK/ERK and PI3K/Akt pathways regulate proliferation and prevent apoptosis, and their altered expression is commonly observed in human cancer due to the high mutation frequency of upstream regulators. In this study, the effects of Raf, MEK, and PI3K inhibitors on conditionally transformed hematopoietic cells were examined to determine if they would display cytotoxic differences between cytokine- and oncogene-mediated proliferation, and whether inhibition of both pathways was a more effective means to induce apoptosis. In the hematopoietic model system employed, proliferation was conditional and occurred when either interleukin-3 (IL-3) or the estrogen receptor antagonist 4-hydroxytamoxifen (4HT), which activates the conditional oncoprotein (DeltaRaf:ER), were provided. Thus, upon the addition of the signal transduction inhibitors and either IL-3 or 4HT, the effects of these drugs were examined in the same cell under 'cytokine-' and 'oncoprotein' -mediated growth conditions avoiding genetic and differentiation stage heterogeneity. At drug concentrations around the reported IC(50) for the Raf inhibitor L-779,450, it suppressed DNA synthesis and induced apoptosis in hematopoietic FDC-P1 cells transformed to grow in response to either Raf-1 or A-Raf (FD/DeltaRaf-1:ER and FD/DeltaA-Raf:ER), but it displayed less effects on DNA synthesis and apoptosis when the cells were cultured in IL-3. This Raf inhibitor was less effective on B-Raf- or MEK1-responsive cells, demonstrating the specificity of this drug. MEK inhibitors also suppressed DNA synthesis and induced apoptosis in Raf-responsive cells and the effects were more significant on Raf-responsive compared to cytokine-mediated growth. The PI3K inhibitor LY294002 suppressed Raf-mediated growth, indicating that part of the long-term proliferative effects mediated by Raf are PI3K dependent. Simultaneous inhibition of both Raf/MEK/ERK and PI3K/Akt pathways proved a more efficient means to suppress DNA synthesis and induce apoptosis at lower drug concentrations.
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Affiliation(s)
- J G Shelton
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville 27858, USA
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26
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Chang F, Steelman LS, Lee JT, Shelton JG, Navolanic PM, Blalock WL, Franklin RA, McCubrey JA. Signal transduction mediated by the Ras/Raf/MEK/ERK pathway from cytokine receptors to transcription factors: potential targeting for therapeutic intervention. Leukemia 2003; 17:1263-93. [PMID: 12835716 DOI: 10.1038/sj.leu.2402945] [Citation(s) in RCA: 513] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The Ras/Raf/Mitogen-activated protein kinase/ERK kinase (MEK)/extracellular-signal-regulated kinase (ERK) cascade couples signals from cell surface receptors to transcription factors, which regulate gene expression. Depending upon the stimulus and cell type, this pathway can transmit signals, which result in the prevention or induction of apoptosis or cell cycle progression. Thus, it is an appropriate pathway to target for therapeutic intervention. This pathway becomes more complex daily, as there are multiple members of the kinase and transcription factor families, which can be activated or inactivated by protein phosphorylation. The diversity of signals transduced by this pathway is increased, as different family members heterodimerize to transmit different signals. Furthermore, additional signal transduction pathways interact with the Raf/MEK/ERK pathway to regulate positively or negatively its activity, or to alter the phosphorylation status of downstream targets. Abnormal activation of this pathway occurs in leukemia because of mutations at Ras as well as genes in other pathways (eg PI3K, PTEN, Akt), which serve to regulate its activity. Dysregulation of this pathway can result in autocrine transformation of hematopoietic cells since cytokine genes such as interleukin-3 and granulocyte/macrophage colony-stimulating factor contain the transacting binding sites for the transcription factors regulated by this pathway. Inhibitors of Ras, Raf, MEK and some downstream targets have been developed and many are currently in clinical trials. This review will summarize our current understanding of the Ras/Raf/MEK/ERK signal transduction pathway and the downstream transcription factors. The prospects of targeting this pathway for therapeutic intervention in leukemia and other cancers will be evaluated.
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Affiliation(s)
- F Chang
- Department of Microbiology and Immunology, Brody School of Medicine at East Carolina University, Greenville, NC 27858, USA
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27
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Shelton JG, Steelman LS, Lee JT, Knapp SL, Blalock WL, Moye PW, Franklin RA, Pohnert SC, Mirza AM, McMahon M, McCubrey JA. Effects of the RAF/MEK/ERK and PI3K/AKT signal transduction pathways on the abrogation of cytokine-dependence and prevention of apoptosis in hematopoietic cells. Oncogene 2003; 22:2478-92. [PMID: 12717425 DOI: 10.1038/sj.onc.1206321] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The Raf/MEK/ERK kinase cascade is pivotal in transmitting signals from membrane receptors to transcription factors that control gene expression culminating in the regulation of cell cycle progression. This cascade can prevent cell death through ERK2 and p90(Rsk) activation and phosphorylation of apoptotic and cell cycle regulatory proteins. The PI3K/Akt kinase cascade also controls apoptosis and can phosphorylate many apoptotic and cell cycle regulatory proteins. These pathways are interwoven as Akt can phosphorylate Raf and result in its inactivation, and Raf can be required for the antiapoptotic effects of Akt. In this study, the effects of activated Raf (Raf-1, A-Raf and B-Raf) and PI3K/Akt proteins on abrogation of cytokine dependence in FL5.12 hematopoietic cells were examined. Activated Raf, PI3K or Akt expression, by themselves, did not readily relieve cytokine dependence. The presence of activated Raf and PI3K/Akt increased the isolation of factor-independent cells from 400- to 2500-fold depending upon the particular combination examined. The individual effects of activated Raf and Akt on proliferation, apoptosis and autocrine growth factor synthesis were further examined with hormone-inducible constructs (Delta Raf-1:AR and Delta Akt:ER*(Myr(+)). Activation of either Raf or Akt hindered cell death; however, both proliferation and maximal synthesis of autocrine cytokines were dependent upon activation of both signaling pathways. The effects of small molecular weight inhibitors on DNA synthesis and cytokine gene expression were also examined. The PI3K inhibitor, LY294002, inhibited growth and cytokine gene expression. This effect could be synergistically increased by addition of the MEK inhibitor UO126. These cells will be useful in elucidating the interactions between Raf/MEK/ERK and PI3K/Akt cascades in proliferation, apoptosis, and leukemogenesis, as well as evaluating the efficacy of signal transduction inhibitors that target these cascades.
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Affiliation(s)
- John G Shelton
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, NC 27858, USA
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28
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Chang F, Lee JT, Navolanic PM, Steelman LS, Shelton JG, Blalock WL, Franklin RA, McCubrey JA. Involvement of PI3K/Akt pathway in cell cycle progression, apoptosis, and neoplastic transformation: a target for cancer chemotherapy. Leukemia 2003; 17:590-603. [PMID: 12646949 DOI: 10.1038/sj.leu.2402824] [Citation(s) in RCA: 896] [Impact Index Per Article: 42.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The PI3K/Akt signal transduction cascade has been investigated extensively for its roles in oncogenic transformation. Initial studies implicated both PI3K and Akt in prevention of apoptosis. However, more recent evidence has also associated this pathway with regulation of cell cycle progression. Uncovering the signaling network spanning from extracellular environment to the nucleus should illuminate biochemical events contributing to malignant transformation. Here, we discuss PI3K/Akt-mediated signal transduction including its mechanisms of activation, signal transducing molecules, and effects on gene expression that contribute to tumorigenesis. Effects of PI3K/Akt signaling on important proteins controlling cellular proliferation are emphasized. These targets include cyclins, cyclin-dependent kinases, and cyclin-dependent kinase inhibitors. Furthermore, strategies used to inhibit the PI3K/Akt pathway are presented. The potential for cancer treatment with agents inhibiting this pathway is also addressed.
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Affiliation(s)
- F Chang
- Department of Microbiology & Immunology, Brody School of Medicine at East Carolina University, Greenville 27858, USA
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29
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Graichen R, Liu D, Sun Y, Lee KO, Lobie PE. Autocrine human growth hormone inhibits placental transforming growth factor-beta gene transcription to prevent apoptosis and allow cell cycle progression of human mammary carcinoma cells. J Biol Chem 2002; 277:26662-72. [PMID: 11994274 DOI: 10.1074/jbc.m109931200] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Multiple cellular effects of human growth hormone (hGH) are mediated by an indirect mechanism requiring transcriptional activation of genes encoding protein effector molecules such as insulin-like growth factor-1. Such protein effector molecules then act directly to mediate the cellular functions of hGH. We report here that autocrine hGH production by mammary carcinoma cells specifically results in the transcriptional repression of the p53-regulated placental transforming growth factor-beta (PTGF-beta) gene. Transcriptional repression of the PTGF-beta gene does not require the p53-binding sites in the PTGF-beta promoter, and autocrine hGH also desensitized the response of the PTGF-beta promoter to p53 overexpression. Transcriptional repression of the PTGF-beta gene is accompanied by consequent decreases in its protein product, Smad-mediated transcription, and its cellular effects that include cell cycle arrest and apoptosis. PTGF-beta specifically inhibited the autocrine hGH-stimulated expression of cyclin D1 required for autocrine hGH-stimulated mammary carcinoma cell cycle progression. Thus, one mechanism by which autocrine hGH promotes an increase in mammary carcinoma cell number is by transcriptional repression of protein effector molecules that promote cell cycle arrest and apoptosis. Such transcriptional repression of negative regulatory factors, such as PTGF-beta, may also be requisite for direct stimulation of mammary carcinoma cell mitogenesis by hGH.
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Affiliation(s)
- Ralph Graichen
- Institute of Molecular and Cell Biology, 30 Medical Drive, Singapore 117609, Republic of Singapore
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30
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Lee JT, McCubrey JA. The Raf/MEK/ERK signal transduction cascade as a target for chemotherapeutic intervention in leukemia. Leukemia 2002; 16:486-507. [PMID: 11960326 DOI: 10.1038/sj.leu.2402460] [Citation(s) in RCA: 185] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2001] [Accepted: 01/16/2002] [Indexed: 12/17/2022]
Abstract
The Raf/MEK/ERK (MAPK) signal transduction cascade is a vital mediator of a number of cellular fates including growth, proliferation and survival, among others. The focus of this review centers on the MAPK signal transduction pathway, its mechanisms of activation, downstream mediators of signaling, and the transcription factors that ultimately alter gene expression. Furthermore, negative regulators of this cascade, including phosphatases, are discussed with an emphasis placed upon chemotherapeutic intervention at various points along the pathway. In addition, mounting evidence suggests that the PI3K/Akt pathway may play a role in the effects elicited via MAPK signaling; as such, potential interactions and their possible cellular ramifications are discussed.
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Affiliation(s)
- J T Lee
- Department of Microbiology and Immunology, Brody School of Medicine at East Carolina University, Greenville, NC 27858, USA
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