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Paskeh MDA, Ghadyani F, Hashemi M, Abbaspour A, Zabolian A, Javanshir S, Razzazan M, Mirzaei S, Entezari M, Goharrizi MASB, Salimimoghadam S, Aref AR, Kalbasi A, Rajabi R, Rashidi M, Taheriazam A, Sethi G. Biological impact and therapeutic perspective of targeting PI3K/Akt signaling in hepatocellular carcinoma: Promises and Challenges. Pharmacol Res 2023; 187:106553. [PMID: 36400343 DOI: 10.1016/j.phrs.2022.106553] [Citation(s) in RCA: 41] [Impact Index Per Article: 41.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 11/09/2022] [Accepted: 11/10/2022] [Indexed: 11/17/2022]
Abstract
Cancer progression results from activation of various signaling networks. Among these, PI3K/Akt signaling contributes to proliferation, invasion, and inhibition of apoptosis. Hepatocellular carcinoma (HCC) is a primary liver cancer with high incidence rate, especially in regions with high prevalence of viral hepatitis infection. Autoimmune disorders, diabetes mellitus, obesity, alcohol consumption, and inflammation can also lead to initiation and development of HCC. The treatment of HCC depends on the identification of oncogenic factors that lead tumor cells to develop resistance to therapy. The present review article focuses on the role of PI3K/Akt signaling in HCC progression. Activation of PI3K/Akt signaling promotes glucose uptake, favors glycolysis and increases tumor cell proliferation. It inhibits both apoptosis and autophagy while promoting HCC cell survival. PI3K/Akt stimulates epithelial-to-mesenchymal transition (EMT) and increases matrix-metalloproteinase (MMP) expression during HCC metastasis. In addition to increasing colony formation capacity and facilitating the spread of tumor cells, PI3K/Akt signaling stimulates angiogenesis. Therefore, silencing PI3K/Akt signaling prevents aggressive HCC cell behavior. Activation of PI3K/Akt signaling can confer drug resistance, particularly to sorafenib, and decreases the radio-sensitivity of HCC cells. Anti-cancer agents, like phytochemicals and small molecules can suppress PI3K/Akt signaling by limiting HCC progression. Being upregulated in tumor tissues and clinical samples, PI3K/Akt can also be used as a biomarker to predict patients' response to therapy.
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Affiliation(s)
- Mahshid Deldar Abad Paskeh
- Department of Genetics, Faculty of Advanced Science and Technology, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran; Farhikhtegan Medical Convergence sciences Research Center, Farhikhtegan Hospital Tehran Medical Sciences, Islamic Azad University, Tehran, Iran
| | - Fatemeh Ghadyani
- Farhikhtegan Medical Convergence sciences Research Center, Farhikhtegan Hospital Tehran Medical Sciences, Islamic Azad University, Tehran, Iran
| | - Mehrdad Hashemi
- Department of Genetics, Faculty of Advanced Science and Technology, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran; Farhikhtegan Medical Convergence sciences Research Center, Farhikhtegan Hospital Tehran Medical Sciences, Islamic Azad University, Tehran, Iran
| | - Alireza Abbaspour
- Cellular and Molecular Research Center,Qazvin University of Medical Sciences, Qazvin, Iran
| | - Amirhossein Zabolian
- Resident of department of Orthopedics, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Salar Javanshir
- Young Researchers and Elite Club, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran
| | - Mehrnaz Razzazan
- Medical Student, Student Research Committee, Golestan University of Medical Sciences, Gorgan, Iran
| | - Sepideh Mirzaei
- Department of Biology, Faculty of Science, Islamic Azad University, Science and Research Branch, Tehran, Iran
| | - Maliheh Entezari
- Department of Genetics, Faculty of Advanced Science and Technology, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran; Farhikhtegan Medical Convergence sciences Research Center, Farhikhtegan Hospital Tehran Medical Sciences, Islamic Azad University, Tehran, Iran
| | | | - Shokooh Salimimoghadam
- Department of Biochemistry and Molecular Biology, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran
| | - Amir Reza Aref
- Belfer Center for Applied Cancer Science, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, USA; Translational Sciences, Xsphera Biosciences Inc. 6, Tide Street, Boston, MA 02210, USA
| | - Alireza Kalbasi
- Department of Pharmacy, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Romina Rajabi
- Faculty of Veterinary Medicine, Islamic Azad University, Science and Research Branch, Tehran, Iran.
| | - Mohsen Rashidi
- Department Pharmacology, Faculty of Medicine, Mazandaran University of Medical Sciences, Sari, Iran; The Health of Plant and Livestock Products Research Center, Mazandaran University of Medical Sciences, Sari, Iran.
| | - Afshin Taheriazam
- Farhikhtegan Medical Convergence sciences Research Center, Farhikhtegan Hospital Tehran Medical Sciences, Islamic Azad University, Tehran, Iran; Department of Orthopedics, Faculty of medicine, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran.
| | - Gautam Sethi
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117600, Singapore; NUS Centre for Cancer Research, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117599, Singapore.
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Gu Y, Jiang J, Liang C. TFAP4 promotes the growth of prostate cancer cells by upregulating FOXK1. Exp Ther Med 2021; 22:1299. [PMID: 34630654 PMCID: PMC8461620 DOI: 10.3892/etm.2021.10734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Accepted: 01/22/2021] [Indexed: 11/06/2022] Open
Abstract
Transcription factor activating enhancer binding protein 4 (TFAP4) has been indicated to be correlated with the progression of various human malignancies. However, the effect and regulatory mechanism of TFAP4 in prostate cancer (PC) remain unclear. The protein and mRNA expression were detected by western blotting and RT-qPCR. TFAP4 was overexpressed or knocked down in PC cells. The viability, invasion and migration of PC cells were analyzed by CCK-8, Transwell and wound healing assays. The colony formation was also determined. TFAP4 expression was upregulated in PC patients and cells; high TFAP4 expression predicted poor prognosis, and was associated with a range of clinicopathological features, including metastasis, clinical stage and Gleason score. Moreover, overexpression of TFAP4 promoted cell viability, migration, and invasion in vitro, whereas knockdown of TFAP4 revealed the opposite results. TFAP4 also positively regulated forkhead box K1 (FOXK1) expression. In addition, overexpression of FOXK1 reversed the effects of TFAP4 knockdown on PC cells. These findings clarified the biologic significance of TFAP4 in PC progression and revealed an association between TFAP4 and FOXK1, thus providing a new potential target for clinical therapy of PC.
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Affiliation(s)
- Yuan Gu
- Department of Urology, Anhui No. 2 Provincial People's Hospital, Hefei, Anhui 230041, P.R. China
- Department of Urology, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui 230041, P.R. China
| | - Jiujin Jiang
- Department of Urology, Anhui No. 2 Provincial People's Hospital, Hefei, Anhui 230041, P.R. China
| | - Chaozhao Liang
- Department of Urology, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui 230041, P.R. China
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Transcription Factor AP4 Mediates Cell Fate Decisions: To Divide, Age, or Die. Cancers (Basel) 2021; 13:cancers13040676. [PMID: 33567514 PMCID: PMC7914591 DOI: 10.3390/cancers13040676] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 01/31/2021] [Accepted: 02/03/2021] [Indexed: 12/12/2022] Open
Abstract
Simple Summary Here, we review the literature on Activating Enhancer-Binding Protein 4 (AP4)/transcription factor AP4 (TFAP4) function and regulation and its role in cancer. Elevated expression of AP4 was detected in tumors of various organs and is associated with poor patient survival. AP4 is encoded by a Myc target gene and mediates cell fate decisions by regulating multiple processes, such as cell proliferation, epithelial-mesenchymal transition, stemness, apoptosis, and cellular senescence. Thereby, AP4 may be critical for tumor initiation and progression. In this review article, we summarize published evidence showing how AP4 functions as a transcriptional activator and repressor of a plethora of direct target genes in various physiological and pathological conditions. We also highlight the complex interactions of AP4 with c-Myc, N-Myc, p53, lncRNAs, and miRNAs in feed-back loops, which control AP4 levels and mediate AP4 functions. In the future, a better understanding of AP4 may contribute to improved prognosis and therapy of cancer. Abstract Activating Enhancer-Binding Protein 4 (AP4)/transcription factor AP4 (TFAP4) is a basic-helix-loop-helix-leucine-zipper transcription factor that was first identified as a protein bound to SV40 promoters more than 30 years ago. Almost 15 years later, AP4 was characterized as a target of the c-Myc transcription factor, which is the product of a prototypic oncogene that is activated in the majority of tumors. Interestingly, AP4 seems to represent a central hub downstream of c-Myc and N-Myc that mediates some of their functions, such as proliferation and epithelial-mesenchymal transition (EMT). Elevated AP4 expression is associated with progression of cancer and poor patient prognosis in multiple tumor types. Deletion of AP4 in mice points to roles of AP4 in the control of stemness, tumor initiation and adaptive immunity. Interestingly, ex vivo AP4 inactivation results in increased DNA damage, senescence, and apoptosis, which may be caused by defective cell cycle progression. Here, we will summarize the roles of AP4 as a transcriptional repressor and activator of target genes and the contribution of protein and non-coding RNAs encoded by these genes, in regulating the above mentioned processes. In addition, proteins interacting with or regulating AP4 and the cellular signaling pathways altered after AP4 dysregulation in tumor cells will be discussed.
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Liu JN, Kong XS, Sun P, Wang R, Li W, Chen QF. An integrated pan-cancer analysis of TFAP4 aberrations and the potential clinical implications for cancer immunity. J Cell Mol Med 2020; 25:2082-2097. [PMID: 33373169 PMCID: PMC7882993 DOI: 10.1111/jcmm.16147] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 10/07/2020] [Accepted: 11/22/2020] [Indexed: 12/21/2022] Open
Abstract
Studies have shown that transcription factor activating enhancer binding protein 4 (TFAP4) plays a vital role in multiple types of cancer; however, the TFAP4 expression profile is still unknown, as is its value within the human pan‐cancer analysis. The present study comprehensively analysed TFAP4 expression patterns from 33 types of malignancies, along with the significance of TFAP4 for prognosis prediction and cancer immunity. TFAP4 displayed inconsistent levels of gene expression across the diverse cancer cell lines, and displayed abnormal expression within most malignant tumours, which closely corresponded to overall survival. More importantly, the TFAP4 level was also significantly related to the degree of tumour infiltration. TFAP4 was correlated using gene markers in tumour‐infiltrating immune cells and immune scores. TFAP4 expression was correlated with tumour mutation burden and microsatellite instability in different cancer types, and enrichment analyses identified TFAP4‐associated terms and pathways. The present study comprehensively analysed the expression of TFAP4 across 33 distinct types of cancers, which revealed that TFAP4 may possibly play a vital role during cancer formation and development. TFAP4 is related to differing degrees of immune infiltration within cancers, which suggests the potential of TFAP4 as an immunotherapy target in cancers. Our study demonstrated that TFAP4 plays an important role in tumorigenesis as a prognostic biomarker, which highlights the possibility of developing new targeted treatments.
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Affiliation(s)
- Jian-Nan Liu
- Department of Oncology, Yantai Yuhuangding Hospital, Yantai, China
| | - Xiang-Shuo Kong
- Department of Oncology, Yantai Yuhuangding Hospital, Yantai, China
| | - Ping Sun
- Department of Oncology, Yantai Yuhuangding Hospital, Yantai, China
| | - Rui Wang
- Department of Respiratory Oncology, Fushan district people's hospital, Yantai, China
| | - Wang Li
- Department of Medical Imaging and Interventional Radiology, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Qi-Feng Chen
- Department of Medical Imaging and Interventional Radiology, Sun Yat-sen University Cancer Center, Guangzhou, China.,State Key Laboratory of Oncology in South China, Guangzhou, China.,Collaborative Innovation Center for Cancer Medicine, Guangzhou, China
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Propranolol suppresses infantile hemangioma cell proliferation and promotes apoptosis by upregulating miR-125b expression. Anticancer Drugs 2020; 30:501-507. [PMID: 30986805 DOI: 10.1097/cad.0000000000000762] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Propranolol could repress infantile hemangioma cell growth and induce apoptosis. miR-125b could inhibit cell proliferation in some tumors. However, whether propranolol exerts its proliferation inhibition and apoptosis-promoting effect by regulating the expression of miR-125b needs to be further investigated. In tumor tissue and endothelial cells isolated from infantile hemangioma patients, we found that the expression levels of miR-125b were significantly decreased. In-vitro analysis revealed that propranolol increased the expression of miR-125b in hemangioma cells in a dose-dependent and time-dependent manner. Interestingly, it was observed that regression of miR-125b expression by its inhibitor could abrogate the effect of propranolol on hemangioma cell growth and apoptosis. In addition, our data further identified TFAP4 as a direct target of miR-125b. Collectively, our data provided evidence that propranolol may repress infantile hemangioma cell growth and promote apoptosis through upregulating the miR-125b expression, which exerted its suppression of tumor development by targeting TFAP4.
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TFAP4 Promotes Hepatocellular Carcinoma Invasion and Metastasis via Activating the PI3K/AKT Signaling Pathway. DISEASE MARKERS 2019; 2019:7129214. [PMID: 31281549 PMCID: PMC6590577 DOI: 10.1155/2019/7129214] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2018] [Revised: 04/29/2019] [Accepted: 05/06/2019] [Indexed: 12/12/2022]
Abstract
Transcription factor activating enhancer binding protein 4 (TFAP4) is established as a regulator of human cancer genesis and progression. Overexpression of TFAP4 indicates poor prognosis in various malignancies. The current study was performed to quantify TFAP4 expression as well as to further determine its potential prognostic value and functional role in patients with hepatocellular carcinoma (HCC). We identified that the expression of TFAP4 mRNA in 369 tumor tissues was higher than that in 160 normal liver tissues. Upregulated TFAP4 expressions were discovered in HCC cell lines compared to the healthy liver cell line, and similarly, the levels of TFAP4 were higher in tumor tissues than its expression in paratumor tissues. High mRNA and protein expression of TFAP4 was associated with worse overall survival (OS) and disease-free survival (DFS). Additionally, TFAP4 expression emerged as a risk factor independently affecting both OS and DFS of HCC patients. Functional studies demonstrated that TFAP4 increased HCC cell migration and invasion. Further investigations found that TFAP4 promotes invasion and metastasis by inducing epithelial-mesenchymal transition (EMT) and regulating MMP-9 expression via activating the PI3K/AKT signaling pathway in HCC. In conclusion, our study demonstrated that TFAP4 is a valuable prognostic biomarker in determining the likelihood of tumor metastasis and recurrence, as well as the long-term survival rates of HCC patients. Exploring the regulatory mechanism of TFAP4 will also contribute to the development of new prevention and treatment strategies for HCC.
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Mushtaq F, Zhang J, Li J. miR-144 suppresses cell proliferation and invasion in gastric cancer through downregulation of activating enhancer-binding protein 4. Oncol Lett 2019; 17:5686-5692. [PMID: 31186793 DOI: 10.3892/ol.2019.10214] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 12/11/2018] [Indexed: 12/17/2022] Open
Abstract
Gastric cancer (GC) is the most common malignant disease and its incidence rate is increasing rapidly worldwide. The molecular mechanisms underlying GC tumorigenesis require further investigation. The expression and physiological roles of microRNA-144 (miR-144) have been investigated in numerous types of tumor. However, its biological function in GC remains largely unknown. The reverse transcription- quantitative polymerase chain reaction was used to determine the expression of miR-144 in GC cells and normal gastric epithelial cells. An miR-144 mimic was transfected into HGC-27 cells. In addition, bioinformatics analysis was performed to identify the potential targets of miR-144. Protein expression, luciferase and rescue assays were used to confirm the target of miR-144. It was identified that the expression of miR-144 was significantly downregulated in GC cells compared with in normal gastric epithelial cells. Furthermore, overexpression of miR-144 suppressed HGC-27 cell proliferation, migration and invasion. Additionally, bioinformatics analysis suggested that the activating enhancer-binding protein 4 (AP4) is a target gene of miR-144. In addition, it was determined that miR-144 suppresses the expression of AP4 by binding directly to its 3'-untranslated regions. Furthermore, restoration of AP4 partially attenuated miR-144-induced inhibition of cell proliferation, migration and invasion. Therefore, the results of the present study suggest that miR-144 serves an important role in GC progression.
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Affiliation(s)
- Faheim Mushtaq
- Department of Gastroenterology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, P.R. China
| | - Jinping Zhang
- Department of Gastroenterology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, P.R. China
| | - Jiansheng Li
- Department of Gastroenterology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, P.R. China
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Hou Z, Guo K, Sun X, Hu F, Chen Q, Luo X, Wang G, Hu J, Sun L. TRIB2 functions as novel oncogene in colorectal cancer by blocking cellular senescence through AP4/p21 signaling. Mol Cancer 2018; 17:172. [PMID: 30541550 PMCID: PMC6291992 DOI: 10.1186/s12943-018-0922-x] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 11/21/2018] [Indexed: 12/11/2022] Open
Abstract
Background Cellular senescence is a state of irreversible cell growth arrest and senescence cells permanently lose proliferation potential. Induction of cellular senescence might be a novel therapy for cancer cells. TRIB2 has been reported to participate in regulating proliferation and drug resistance of various cancer cells. However, the role of TRIB2 in cellular senescence of colorectal cancer (CRC) and its molecular mechanism remains unclear. Methods The expression of TRIB2 in colorectal cancer tissues and adjacent tissues was detected by immunohistochemistry and RT-PCR. The growth, cell cycle distribution and cellular senescence of colorectal cancer cells were evaluated by Cell Counting Kit-8 (CCK8) assay, flow cytometry detection and senescence-associated β-galactosidase staining, respectively. Western blot, RT-PCR and luciferase assay were performed to determine how TRIB2 regulates p21. Immunoprecipitation (IP) and chromatin-immunoprecipitation (ChIP) were used to investigate the molecular mechanisms. Results We found that TRIB2 expression was elevated in CRC tissues compared to normal adjacent tissues and high TRIB2 expression indicated poor prognosis of CRC patients. Functionally, depletion of TRIB2 inhibited cancer cells proliferation, induced cell cycle arrest and promoted cellular senescence, whereas overexpression of TRIB2 accelerated cell growth, cell cycle progression and blocked cellular senescence. Further studies showed that TRIB2 physically interacted with AP4 and inhibited p21 expression through enhancing transcription activities of AP4. The rescue experiments indicated that silencing of AP4 abrogated the inhibition of cellular senescence induced by TRIB2 overexpression. Conclusion These data demonstrate that TRIB2 suppresses cellular senescence through interaction with AP4 to down-regulate p21 expression. Therefore, TRIB2 could be a potential target for CRC treatment. Electronic supplementary material The online version of this article (10.1186/s12943-018-0922-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Zhenlin Hou
- Cancer Research Institute, Tongji Hospital, Huazhong University of Science and Technology, Wuhan, China
| | - Kaixuan Guo
- Cancer Research Institute, Tongji Hospital, Huazhong University of Science and Technology, Wuhan, China
| | - Xuling Sun
- Cancer Research Institute, Tongji Hospital, Huazhong University of Science and Technology, Wuhan, China
| | - Fuqing Hu
- Cancer Research Institute, Tongji Hospital, Huazhong University of Science and Technology, Wuhan, China
| | - Qianzhi Chen
- Cancer Research Institute, Tongji Hospital, Huazhong University of Science and Technology, Wuhan, China
| | - Xuelai Luo
- Cancer Research Institute, Tongji Hospital, Huazhong University of Science and Technology, Wuhan, China
| | - Guihua Wang
- Cancer Research Institute, Tongji Hospital, Huazhong University of Science and Technology, Wuhan, China
| | - Junbo Hu
- Cancer Research Institute, Tongji Hospital, Huazhong University of Science and Technology, Wuhan, China
| | - Li Sun
- Department of Oncology, Tongji Hospital, Huazhong University of Science and Technology, 1095 Jiefang Av, Wuhan, Hubei, 430030, People's Republic of China.
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Best BT. Single-cell branching morphogenesis in the Drosophila trachea. Dev Biol 2018; 451:5-15. [PMID: 30529233 DOI: 10.1016/j.ydbio.2018.12.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2018] [Revised: 11/23/2018] [Accepted: 12/01/2018] [Indexed: 12/20/2022]
Abstract
The terminal cells of the tracheal epithelium in Drosophila melanogaster are one of the few known cell types that undergo subcellular morphogenesis to achieve a stable, branched shape. During the animal's larval stages, the cells repeatedly sprout new cytoplasmic processes. These grow very long, wrapping around target tissues to which the terminal cells adhere, and are hollowed by a gas-filled subcellular tube for oxygen delivery. Our understanding of this ramification process remains rudimentary. This review aims to provide a comprehensive summary of studies on terminal cells to date, and attempts to extrapolate how terminal branches might be formed based on the known genetic and molecular components. Next to this cell-intrinsic branching mechanism, we examine the extrinsic regulation of terminal branching by the target tissue and the animal's environment. Finally, we assess the degree of similarity between the patterns established by the branching programs of terminal cells and other branched cells and tissues from a mathematical and conceptual point of view.
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Affiliation(s)
- Benedikt T Best
- Director's Research Unit, European Molecular Biology Laboratory (EMBL), Meyerhofstr. 1, 69117 Heidelberg, Germany; Collaboration for Joint PhD degree from EMBL and Heidelberg University, Faculty of Biosciences, Germany
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Yang J, Ma JP, Xiao S, Zhang XH, Xu JB, Chen CQ, Cai SR, He YL. Evaluating the prognostic value and functional roles of transcription factor AP4 in colorectal cancer. Oncol Lett 2018; 15:7545-7554. [PMID: 29725460 PMCID: PMC5920486 DOI: 10.3892/ol.2018.8290] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Accepted: 09/22/2017] [Indexed: 01/06/2023] Open
Abstract
The basic helix-loop-helix transcription factor AP4 (TFAP4) gene serves an important function in the genesis and progression of tumors. However, few studies to date have defined the role of this gene in colorectal cancer (CRC). The aim of the present study was to assess the expression of TFAP4 in CRC and its impact on the prognosis of patients with CRC. In the present study, the expression of TFAP4 was detected in 30 matched pairs of fresh CRC tissues, 187 cases of clinical paraffin-embedded CRC tissues and CRC cell lines using the reverse transcriptase-quantitative polymerase chain reaction, immunohistochemistry or western blot analysis. Survival analysis was based on TFAP4 expression. The effects of TFAP4 on CRC cell function were investigated by ectopic expression or knockdown of TFAP4 in vitro. TFAP4 expression was revealed to be increased in human CRC tissues and cell lines. The overall survival (OS) time of patients with high TFAP4 expression was significantly decreased compared with patients with low TFAP4 expression (P<0.001). In addition, TFAP4 was revealed to be an independent prognostic factor for the OS time of patients with CRC (hazard ratio, 2.607; 95% confidence interval, 1.469-4.627; P=0.001). Ectopic TFAP4 expression promoted CRC cell proliferation, migration and invasion in vitro, and the silencing of TFAP4 expression resulted in the inhibition of these events. These results demonstrated that TFAP4, which was overexpressed in CRC tissues and cell lines, increased the malignant potential of CRC cells and may serve as an indicator for poor prognosis in patients with CRC.
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Affiliation(s)
- Jie Yang
- Department of Gastrointestinal Surgery, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510080, P.R. China
| | - Jin-Ping Ma
- Department of Gastrointestinal Surgery, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510080, P.R. China
| | - Siyu Xiao
- Department of Clinical Laboratory, The Sixth Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510655, P.R. China
| | - Xin-Hua Zhang
- Department of Gastrointestinal Surgery, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510080, P.R. China
| | - Jian-Bo Xu
- Department of Gastrointestinal Surgery, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510080, P.R. China
| | - Chuang-Qi Chen
- Department of Gastrointestinal Surgery, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510080, P.R. China
| | - Shi-Rong Cai
- Department of Gastrointestinal Surgery, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510080, P.R. China
| | - Yu-Long He
- Department of Gastrointestinal Surgery, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510080, P.R. China
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Differential cellular responses by oncogenic levels of c-Myc expression in long-term confluent retinal pigment epithelial cells. Mol Cell Biochem 2017; 443:193-204. [PMID: 29188535 DOI: 10.1007/s11010-017-3224-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Accepted: 11/23/2017] [Indexed: 01/10/2023]
Abstract
c-Myc is a highly pleiotropic transcription factor known to control cell cycle progression, apoptosis, and cellular transformation. Normally, ectopic expression of c-Myc is associated with promoting cell proliferation or triggering cell death via activating p53. However, it is not clear how the levels of c-Myc lead to different cellular responses. Here, we generated a series of stable RPE cell clones expressing c-Myc at different levels, and found that consistent low level of c-Myc induced cellular senescence by activating AP4 in post-confluent RPE cells, while the cells underwent cell death at high level of c-Myc. In addition, high level of c-Myc could override the effect of AP4 on cellular senescence. Further knockdown of AP4 abrogated senescence-like phenotype in cells expressing low level of c-Myc, and accelerated cell death in cells with medium level of c-Myc, indicating that AP4 was required for cellular senescence induced by low level of c-Myc.
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AP4 modulated by the PI3K/AKT pathway promotes prostate cancer proliferation and metastasis of prostate cancer via upregulating L-plastin. Cell Death Dis 2017; 8:e3060. [PMID: 28981098 PMCID: PMC5680569 DOI: 10.1038/cddis.2017.437] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 07/17/2017] [Accepted: 07/20/2017] [Indexed: 01/06/2023]
Abstract
The transition from androgen-dependent to metastatic castration-resistant prostate cancer (PCa) is a lethal event of uncertain molecular aetiology. Our previous studies demonstrated that L-plastin is involved in PCa invasion and metastasis and is upregulated by androgen and oestrogen in the hormone-dependent PCa cell line LNCaP. We recently found that L-plastin expression is consistently activated even after androgen deprivation, suggesting that androgen-independent transcription factors may regulate its expression. Herein, we performed sequential deletion and luciferase analysis of the L-plastin promoter and found that an androgen-independent regulatory factor prominently located in the region close to the transcription initiation site (−216 to +118) may facilitate L-plastin upregulation. AP4 was then identified as the relevant transcription activator that directly binds to the L-plastin promoter, as confirmed by EMSAs, supershift assays and CHIP-qPCR experiments. Moreover, we determined that the AP4/L-plastin axis is regulated by the phosphatidylinositol 3-kinase (PI3K)/AKT pathway, contributing to PCa metastasis and castration resistance. Furthermore, we found that AP4 promotes PCa metastasis by upregulating L-plastin expression in vitro and in vivo. We collected a total of 136 PCa tissues and corresponding adjacent normal tissues from patients who underwent prostatectomy at Sun Yat-Sen Memorial Hospital from 2005 to 2015 and measured AP4 and L-plastin protein levels by immunohistochemistry. The results showed that AP4 levels strongly correlated with those of its downstream target gene L-plastin, were significantly upregulated in PCa tissues, were positively correlated with lymph node metastasis and Gleason scores over 7, and were an independent prognostic factor for patient survival. In summary, these findings support a plausible mechanism by which the AP4/L-plastin axis is regulated by the PI3K/AKT pathway in human PCa and may represent a novel therapeutic target in PCa treatment.
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Wei J, Yang P, Zhang T, Chen Z, Chen W, Wanglin L, He F, Wei F, Huang D, Zhong J, Yang Z, Chen H, Hu H, Zeng S, Sun Z, Cao J. Overexpression of transcription factor activating enhancer binding protein 4 (TFAP4) predicts poor prognosis for colorectal cancer patients. Exp Ther Med 2017; 14:3057-3061. [PMID: 28912857 PMCID: PMC5585722 DOI: 10.3892/etm.2017.4875] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Accepted: 05/15/2017] [Indexed: 12/28/2022] Open
Abstract
Transcription factor activating enhancer binding protein 4 (TFAP4) is an important regulator in the genesis and progression of human cancers. Overexpression of TFAP4 has been found to be correlated with several malignancies. The present study assessed the clinical importance of TFAP4 in colorectal cancer (CRC). First, immunohistochemistry was used to analyze TFAP4 expression and the association of TFAP4 expression with clinicopathological features on a tissue microarray containing 208 CRC patients. The results revealed that TFAP4 protein expression was significantly upregulated in CRC tissues compared with that in normal colon tissues (P<0.001). Of note, statistical analysis revealed that TFAP4 expression was significantly correlated with a high pathological grade (P=0.034), advanced clinical stage (P=0.024), enhanced tumor invasion (P=0.002) and lymph node metastasis (P=0.041). In addition, the Cancer Genome Atlas dataset further validated that TFAP4 mRNA levels were increased in CRC with advanced clinical stage (P=0.026), lymph node metastasis (P=0.018) and vascular invasion (P=0.046). Kaplan-Meier survival analysis demonstrated that CRC patients with high TFAP4 expression had shorter overall survival compared with those with low TFAP4 expression (P=0.011). Importantly, overexpression of TFAP4 was a valuable independent prognostic factor for CRC patients (hazard ratio, 8.200; 95% confidence interval, 1.838-36.591; P=0.006). In summary, TFAP4 may have an important role in CRC progression and upregulation of TFAP4 may be a predictor of poor prognosis for CRC patients.
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Affiliation(s)
- Jianchang Wei
- Department of General Surgery, Guangzhou Digestive Disease Center, Guangzhou First People's Hospital, Guangzhou Medical University, Guangzhou, Guangdong 510180, P.R. China
| | - Ping Yang
- Department of General Surgery, Guangzhou Digestive Disease Center, Guangzhou First People's Hospital, Guangzhou Medical University, Guangzhou, Guangdong 510180, P.R. China
| | - Tong Zhang
- Department of General Surgery, Guangzhou Digestive Disease Center, Guangzhou First People's Hospital, Guangzhou Medical University, Guangzhou, Guangdong 510180, P.R. China
| | - Zhuanpeng Chen
- Department of General Surgery, Guangzhou Digestive Disease Center, Guangzhou First People's Hospital, Guangzhou Medical University, Guangzhou, Guangdong 510180, P.R. China
| | - Wei Chen
- Department of Pancreatobiliary Surgery, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong 510180, P.R. China
| | - Li Wanglin
- Department of General Surgery, Guangzhou Digestive Disease Center, Guangzhou First People's Hospital, Guangzhou Medical University, Guangzhou, Guangdong 510180, P.R. China
| | - Feng He
- Department of General Surgery, Guangzhou Digestive Disease Center, Guangzhou First People's Hospital, Guangzhou Medical University, Guangzhou, Guangdong 510180, P.R. China
| | - Fang Wei
- Department of General Surgery, Guangzhou Digestive Disease Center, Guangzhou First People's Hospital, Guangzhou Medical University, Guangzhou, Guangdong 510180, P.R. China
| | - Di Huang
- Department of General Surgery, Guangzhou Digestive Disease Center, Guangzhou First People's Hospital, Guangzhou Medical University, Guangzhou, Guangdong 510180, P.R. China
| | - Junbin Zhong
- Department of General Surgery, Guangzhou Digestive Disease Center, Guangzhou First People's Hospital, Guangzhou Medical University, Guangzhou, Guangdong 510180, P.R. China
| | - Zhi Yang
- Department of General Surgery, Guangzhou Digestive Disease Center, Guangzhou First People's Hospital, Guangzhou Medical University, Guangzhou, Guangdong 510180, P.R. China
| | - Huacui Chen
- Department of General Surgery, Guangzhou Digestive Disease Center, Guangzhou First People's Hospital, Guangzhou Medical University, Guangzhou, Guangdong 510180, P.R. China
| | - He Hu
- Department of General Surgery, Guangzhou Digestive Disease Center, Guangzhou First People's Hospital, Guangzhou Medical University, Guangzhou, Guangdong 510180, P.R. China
| | - Shanqi Zeng
- Department of General Surgery, Guangzhou Digestive Disease Center, Guangzhou First People's Hospital, Guangzhou Medical University, Guangzhou, Guangdong 510180, P.R. China
| | - Zheng Sun
- Department of General Surgery, Guangzhou Digestive Disease Center, Guangzhou First People's Hospital, Guangzhou Medical University, Guangzhou, Guangdong 510180, P.R. China
| | - Jie Cao
- Department of General Surgery, Guangzhou Digestive Disease Center, Guangzhou First People's Hospital, Guangzhou Medical University, Guangzhou, Guangdong 510180, P.R. China
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14
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Ross JA, George BJ, Bruno M, Ge Y. Chemical-agnostic hazard prediction: statistical inference of in vitro toxicity pathways from proteomics responses to chemical mixtures. ACTA ACUST UNITED AC 2017; 2:39-44. [PMID: 30345409 DOI: 10.1016/j.comtox.2017.03.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Toxicity pathways have been defined as normal cellular pathways that, when sufficiently perturbed as a consequence of chemical exposure, lead to an adverse outcome. If an exposure alters one or more normal biological pathways to an extent that leads to an adverse toxicity outcome, a significant correlation must exist between the exposure, the extent of pathway alteration, and the degree of adverse outcome. Biological pathways are regulated at multiple levels, including transcriptional, post-transcriptional, post-translational, and targeted degradation, each of which can affect the levels and extents of modification of proteins involved in the pathways. Significant alterations of toxicity pathways resulting from changes in regulation at any of these levels therefore are likely to be detectable as alterations in the proteome. We hypothesize that significant correlations between exposures, adverse outcomes, and changes in the proteome have the potential to identify putative toxicity pathways, facilitating selection of candidate targets for high throughput screening, even in the absence of a priori knowledge of either the specific pathways involved or the specific agents inducing the pathway alterations. We explored this hypothesis in vitro in BEAS-2B human airway epithelial cells exposed to different concentrations of Ni2+, Cd2+, and Cr6+, alone and in defined mixtures. Levels and phosphorylation status of a variety of signaling pathway proteins and cytokines were measured after 48 hours exposure, together with cytotoxicity. Least Absolute Shrinkage and Selection Operator (LASSO) multiple regression was used to identify a subset of these proteins that constitute a putative toxicity pathway capable of predicting cytotoxicity. The putative toxicity pathway for cytotoxicity of these metals and metal mixtures identified by LASSO is composed of phospho-RPS6KB1, phospho-p53, cleaved CASP3, phospho-MAPK8, IL-10, and Hif-1α. As this approach does not depend on knowledge of the chemical composition of the mixtures, it may be generally useful for identifying sets of proteins predictive of adverse effects for a variety of mixtures, including complex environmental mixtures of unknown composition.
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Affiliation(s)
- Jeffrey A Ross
- National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC, 27711
| | - Barbara Jane George
- National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC, 27711
| | - Maribel Bruno
- National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC, 27711
| | - Yue Ge
- National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC, 27711
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15
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Sun X, Feng Z, Qu Y, Shao J, Wei N. Expression of Activating Protein 4 and Its Relationships with Prognosis in Gastric Cancer. Chemotherapy 2017; 62:181-186. [DOI: 10.1159/000455004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Accepted: 11/30/2016] [Indexed: 01/26/2023]
Abstract
Objective: The aim of this work was to investigate the expression of transcription activating protein 4 (AP-4) in gastric cancer (GC) and its impacts on prognosis. Methods: The cancer tissues and normal tissues of 54 GC patients were sampled for the expression detection of AP-4, and the patients were followed up. Results: The positive expression rate of AP-4 in the cancer tissues (68.5%) was higher than the normal tissues (22.2%; p < 0.01). The lower the tumor differentiation degree and the deeper the invasion depth, the higher the expression rate of AP-4. The median survival time of the patients with positive AP-4 expression was significantly shorter than of those without AP-4 expression (26.3/41.3 months), and the accumulative survival rate of the former was also lower than the latter (χ2 = 4.736, p = 0.03). AP-4 was expressed in GC tissues and normal gastric tissues, with the expression in the former being higher. Conclusions: The expression of AP-4 was positively related with the tumor differentiation degree, invasion depth, lymph node metastasis, and pTNM stage, while it was not related with patient gender, age, tumor size, location, or distant metastasis. AP-4 might be used as an indicator for the prognosis prediction of GC.
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16
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Park KI, Park H, Nagappan A, Hong GE, Yumnam S, Lee HJ, Kim EH, Lee WS, Shin SC, Kim JA, Lee SJ, Ma JY, Min T, Heo JD, Kim GS. Polyphenolic compounds from Korean Lonicera japonica Thunb. induces apoptosis via AKT and caspase cascade activation in A549 cells. Oncol Lett 2017; 13:2521-2530. [PMID: 28454429 PMCID: PMC5403260 DOI: 10.3892/ol.2017.5771] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 09/06/2016] [Indexed: 12/16/2022] Open
Abstract
Lonicera japonica Thunb. (L. japonica T.) has historically been used in Korean herbal medicine due to its anticancer and protective effects on the respiratory system. In the present study, the polyphenolic compounds in L. japonica T. were investigated using high-performance liquid chromatography coupled with tandem mass spectrometry, and its anticancer effects on A549 non-small-cell lung cancer cells were studied. Polyphenolic compounds potentially inhibit A549 cells in a dose-dependent manner. Flow cytometry and western blot analysis demonstrated that polyphenolic compounds induce apoptosis by regulating the protein expression levels of caspases, poly-(ADP-ribose) polymerase and the B-cell lymphoma-2-associated X-protein/B-cell lymphoma-extra large ratio. Furthermore, polyphenolic compounds inhibited mitochondrial membrane potential activity. Caspase-3 activity was increased in a dose-dependent manner and polyphenolic compounds inhibited the activation of protein kinase B by dephosphorylation. These results suggest that polyphenolic compounds in A549 cells indicate the anticancer activity through the induction of apoptosis.
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Affiliation(s)
- Kwang Il Park
- Korean Medicine (KM)-Application Center, Korea Institute of Oriental Medicine (KIOM), Daegu, North Gyeongsang 41062, Republic of Korea
| | - Hyeonsoo Park
- Daegu-Gyeongbuk Medical Innovation Foundation (DGMIF), Laboratory Animal Center, Daegu, North Gyeongsang 701-310, Republic of Korea
| | - Arulkumar Nagappan
- Research Institute of Life Science and College of Veterinary Medicine, Gyeongsang National University, Jinju, South Gyeongsang 660-701, Republic of Korea
| | - Gyeong Eun Hong
- Research Institute of Life Science and College of Veterinary Medicine, Gyeongsang National University, Jinju, South Gyeongsang 660-701, Republic of Korea
| | - Silvia Yumnam
- Research Institute of Life Science and College of Veterinary Medicine, Gyeongsang National University, Jinju, South Gyeongsang 660-701, Republic of Korea
| | - Ho Jeong Lee
- Research Institute of Life Science and College of Veterinary Medicine, Gyeongsang National University, Jinju, South Gyeongsang 660-701, Republic of Korea
| | - Eun Hee Kim
- Department of Nursing Science, International University of Korea, Jinju, South Gyeongsang 660-759, Republic of Korea
| | - Won Sup Lee
- Department of Internal Medicine, Institute of Health Sciences, Gyeongsang National University School of Medicine, Gyeongnam Regional Cancer Center, Gyeongsang National University Hospital, Jinju, South Gyeongsang 660-702, Republic of Korea
| | - Sung Chul Shin
- Department of Chemistry, Research Institute of Life Science, Gyeongsang National University, Jinju, South Gyeongsang 660-701, Republic of Korea
| | - Jin A Kim
- Department of Physical Therapy, International University of Korea, Jinju, South Gyeongsang 660-759, Republic of Korea
| | - Sang Joon Lee
- Gyeongnam Department of Environment Toxicology and Chemistry, Toxicity Screening Research Center, Korea Institute of Toxicology, Jinju, South Gyeongsang 52834, Republic of Korea
| | - Jin Yeul Ma
- Korean Medicine (KM)-Application Center, Korea Institute of Oriental Medicine (KIOM), Daegu, North Gyeongsang 41062, Republic of Korea
| | - Taesun Min
- Department of Animal Biotechnology, Jeju National University, Jeju-do 690-756, Republic of Korea
| | - Jeong Doo Heo
- Gyeongnam Department of Environment Toxicology and Chemistry, Toxicity Screening Research Center, Korea Institute of Toxicology, Jinju, South Gyeongsang 52834, Republic of Korea
| | - Gon Sup Kim
- Research Institute of Life Science and College of Veterinary Medicine, Gyeongsang National University, Jinju, South Gyeongsang 660-701, Republic of Korea
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17
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Wang Y. Transcriptional Regulatory Network Analysis for Gastric Cancer Based on mRNA Microarray. Pathol Oncol Res 2017; 23:785-791. [PMID: 28078605 DOI: 10.1007/s12253-016-0159-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Accepted: 12/14/2016] [Indexed: 12/27/2022]
Abstract
We aimed to screen the differential expressed genes (DEGs) and transcriptional factors (TFs) related to gastric cancer. GSE19826 microarray data downloaded from Gene Expression Omnibus was used to identify the differentially expressed genes (DEGs) and PPI network of DEGs were constructed by the Retrieval of Interacting Genes database. Pathway enrichment analysis of DEGs were performed by Gene Set Enrichment Analysis. Then, the transcriptional regulatory network was constructed based on TRANSFAC database. Finally, regulatory impact factor (RIF) of TF was calculated. We identified 446 DEGs including 209 up- and 237 down-regulated genes. These DEGs were mainly significantly enriched in 5 pathways including ECM receptor interaction (p = 0.013899), spliceosome (p = 0.025591), bladder cancer (p = 0.026316), focal adhesion (p = 0.047809) and WNT signaling pathway (p = 0.048077). PPI network with 247 nodes and 913 edges were constructed and COL5A2 was the hub node. Transcriptional regulatory network with 6 differently expressed TFs, 58 non-differently expressed TFs, 44 DEGs and 735 non-DEGs was constructed. Finally, top 5 TFs including CRX, TFAP4, NKX2-1, MYB and RARG with higher ZRIF were screened. The identified DEGs such as COL5A2 and TOP2A, and TFs including EGR2, FOXM1, NKX2-1 and TFAP4 might be the critical genes and TFs for gastric cancer.
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Affiliation(s)
- Yan Wang
- Department of Gastroenterology, Shengjing Hospital, China Medical University, No.36 Sanhao Road, Shenyang, 110004, China.
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18
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Lebensohn AM, Dubey R, Neitzel LR, Tacchelly-Benites O, Yang E, Marceau CD, Davis EM, Patel BB, Bahrami-Nejad Z, Travaglini KJ, Ahmed Y, Lee E, Carette JE, Rohatgi R. Comparative genetic screens in human cells reveal new regulatory mechanisms in WNT signaling. eLife 2016; 5. [PMID: 27996937 PMCID: PMC5257257 DOI: 10.7554/elife.21459] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Accepted: 12/07/2016] [Indexed: 12/15/2022] Open
Abstract
The comprehensive understanding of cellular signaling pathways remains a challenge due to multiple layers of regulation that may become evident only when the pathway is probed at different levels or critical nodes are eliminated. To discover regulatory mechanisms in canonical WNT signaling, we conducted a systematic forward genetic analysis through reporter-based screens in haploid human cells. Comparison of screens for negative, attenuating and positive regulators of WNT signaling, mediators of R-spondin-dependent signaling and suppressors of constitutive signaling induced by loss of the tumor suppressor adenomatous polyposis coli or casein kinase 1α uncovered new regulatory features at most levels of the pathway. These include a requirement for the transcription factor AP-4, a role for the DAX domain of AXIN2 in controlling β-catenin transcriptional activity, a contribution of glycophosphatidylinositol anchor biosynthesis and glypicans to R-spondin-potentiated WNT signaling, and two different mechanisms that regulate signaling when distinct components of the β-catenin destruction complex are lost. The conceptual and methodological framework we describe should enable the comprehensive understanding of other signaling systems. DOI:http://dx.doi.org/10.7554/eLife.21459.001 When an embryo is developing, its cells must communicate with one another to coordinate the processes that shape the body’s tissues and organs. Cells often communicate by releasing signaling molecules that engage with proteins called receptors on the surface of other cells. This triggers a series of events that sends the signal along a “pathway” of biochemical reactions inside the receiving cell and leads to the activation of genes. One such signaling pathway is triggered by the WNT proteins and is used extensively in all animals. The WNT pathway instructs cells to grow and divide, establishes the identity of specific cell types and maintains populations of stem cells that can regenerate tissues in adulthood as well. The WNT pathway must be carefully regulated because various types of cancer can develop if the pathway becomes too active. Some signaling pathways are well conserved between different animals. Many genetic studies into the WNT pathway have focused on animals that are easier to work with in the laboratory, like worms or flies. However, there may be differences in the way these pathways are regulated between these model animals and humans. Therefore, to understand how the WNT pathway operates in humans, it was important to study it in human cells too. Lebensohn et al. have now carried out a series of genetic screens in human cells that contain only one copy of each gene instead of the usual two. These cells – referred to as haploid cells – are ideal for genetic studies because only a single copy of a gene has to be disrupted in order to analyze the consequences of that gene’s loss. The screens searched for genes that regulate WNT signaling: those that keep the pathway “off” in the absence of WNT and those that turn the pathway “on” in response to WNT. By comparing the outcomes of these screens, Lebensohn et al. identified previously unknown regulators and uncovered new roles for known regulators of the WNT pathway. For instance, a regulator called TFAP4, which had not previously been linked to the pathway, was shown to activate WNT signaling. In another case, enzymes that make molecules called glycophosphatidylinositol anchors, and cell-surface proteins that are modified with those anchors, were found to amplify WNT signaling. Lebensohn et al. also identified genes that were needed to sustain the uncontrolled WNT signaling in cells that carried cancer-causing mutations in this pathway. Further studies could now explore if drugs can target these genes, or the molecules encoded by them, to treat cancers in which the WNT pathway is excessively activated. Other studies could also use the same methods to explore more signaling pathways and gain new insights into important biological processes in human cells. DOI:http://dx.doi.org/10.7554/eLife.21459.002
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Affiliation(s)
- Andres M Lebensohn
- Department of Biochemistry, Stanford University School of Medicine, Stanford, United States.,Department of Medicine, Stanford University School of Medicine, Stanford, United States
| | - Ramin Dubey
- Department of Biochemistry, Stanford University School of Medicine, Stanford, United States.,Department of Medicine, Stanford University School of Medicine, Stanford, United States
| | - Leif R Neitzel
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, United States
| | - Ofelia Tacchelly-Benites
- Department of Molecular and Systems Biology and the Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth College, Hanover, United States
| | - Eungi Yang
- Department of Molecular and Systems Biology and the Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth College, Hanover, United States
| | - Caleb D Marceau
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, United States
| | - Eric M Davis
- Department of Molecular Cellular, and Developmental Biology, University of Colorado, Boulder, Boulder, United States
| | - Bhaven B Patel
- Department of Biochemistry, Stanford University School of Medicine, Stanford, United States.,Department of Medicine, Stanford University School of Medicine, Stanford, United States
| | - Zahra Bahrami-Nejad
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, United States
| | - Kyle J Travaglini
- Department of Biochemistry, Stanford University School of Medicine, Stanford, United States
| | - Yashi Ahmed
- Department of Molecular and Systems Biology and the Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth College, Hanover, United States
| | - Ethan Lee
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, United States
| | - Jan E Carette
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, United States
| | - Rajat Rohatgi
- Department of Biochemistry, Stanford University School of Medicine, Stanford, United States.,Department of Medicine, Stanford University School of Medicine, Stanford, United States
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19
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Hu X, Guo W, Chen S, Xu Y, Li P, Wang H, Chu H, Li J, DU Y, Chen X, Zhang G, Zhao G. Silencing of AP-4 inhibits proliferation, induces cell cycle arrest and promotes apoptosis in human lung cancer cells. Oncol Lett 2016; 11:3735-3742. [PMID: 27313685 DOI: 10.3892/ol.2016.4451] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2015] [Accepted: 03/15/2016] [Indexed: 12/25/2022] Open
Abstract
Activating enhancer-binding protein (AP)-4 is a member of the basic helix-loop-helix transcription factors, and is involved in tumor biology. However, the role of AP-4 in human lung cancer remains to be fully elucidated. In the present study, the expression of AP-4 in human lung cancer tissues and cells was investigated by reverse transcription-quantitative polymerase chain reaction, and it was observed that the level of AP-4 was increased in tumor tissues and cells compared with their normal counterparts. AP-4 expression was knocked down by transfection with a specific small interfering RNA (siRNA) in lung cancer cells, and this indicated that siRNA-mediated silencing of AP-4 inhibited cell proliferation, arrested the cell cycle at the G0/G1 phase and induced apoptosis by modulating the expression of p21 and cyclin D1. The results of the present study suggest that AP-4 may be an oncoprotein that has a significant role in lung cancer, and that siRNA-mediated silencing of AP-4 may have therapeutic potential as a strategy for the treatment of lung cancer.
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Affiliation(s)
- Xuanyu Hu
- Department of Microbiology and Immunology, College of Basic Medical Sciences, Zhengzhou University, Zhengzhou, Henan 450001, P.R. China
| | - Wei Guo
- Department of Microbiology and Immunology, Henan Academy of Medical and Pharmaceutical Sciences, Zhengzhou University, Zhengzhou, Henan 450052, P.R. China
| | - Shanshan Chen
- Department of Respiratory Medicine, The First Affiliated Hospital, Zhengzhou University, Zhengzhou, Henan 450052, P.R. China
| | - Yizhuo Xu
- Department of Microbiology and Immunology, College of Basic Medical Sciences, Zhengzhou University, Zhengzhou, Henan 450001, P.R. China
| | - Ping Li
- Department of Respiratory Medicine, The First Affiliated Hospital, Zhengzhou University, Zhengzhou, Henan 450052, P.R. China
| | - Huaqi Wang
- Department of Respiratory Medicine, The First Affiliated Hospital, Zhengzhou University, Zhengzhou, Henan 450052, P.R. China
| | - Heying Chu
- Department of Respiratory Medicine, The First Affiliated Hospital, Zhengzhou University, Zhengzhou, Henan 450052, P.R. China
| | - Juan Li
- Department of Respiratory Medicine, The First Affiliated Hospital, Zhengzhou University, Zhengzhou, Henan 450052, P.R. China
| | - Yuwen DU
- Department of Microbiology and Immunology, College of Basic Medical Sciences, Zhengzhou University, Zhengzhou, Henan 450001, P.R. China
| | - Xiaonan Chen
- Department of Microbiology and Immunology, College of Basic Medical Sciences, Zhengzhou University, Zhengzhou, Henan 450001, P.R. China
| | - Guojun Zhang
- Department of Respiratory Medicine, The First Affiliated Hospital, Zhengzhou University, Zhengzhou, Henan 450052, P.R. China
| | - Guoqiang Zhao
- Department of Microbiology and Immunology, College of Basic Medical Sciences, Zhengzhou University, Zhengzhou, Henan 450001, P.R. China
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20
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Hu TZ, Huang LH, Xu CX, Liu XM, Wang Y, Xiao J, Zhou L, Luo L, Jiang XX. Expressional profiles of transcription factors in the progression of Helicobacter pylori-associated gastric carcinoma based on protein/DNA array analysis. Med Oncol 2015; 32:265. [PMID: 26563475 DOI: 10.1007/s12032-015-0711-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Accepted: 11/02/2015] [Indexed: 12/17/2022]
Abstract
Transcription factors (TFs) are crucial modulators of gene expression during the development and progression of gastric carcinoma. Helicobacter pylori (H. pylori) is one of the most significant risk factors of gastric carcinoma, and it is widely known that chronic inflammation with H. pylori infection triggers gastric carcinogenesis through inflammation-carcinoma chain [gastric carcinogenesis stages: non-atrophic gastritis, chronic atrophic gastritis, intestinal metaplasia, dysplasia and gastric carcinoma (GC)], but its mechanism regarding changed TFs remains unknown. In this study, we investigated the expressional profiles of 345 transcription factors in gastric mucosa of healthy volunteers and patients at different gastric carcinogenesis stages using protein/DNA array-based approach. The data demonstrated the up-regulated TFs such as GATA-3, AP4, c-Myc and Pbx1 in the gastric mucosa of GC patients compared with the healthy volunteers, while other TFs, particularly CCAAT and CACC, showed the consistently decreasing trend along the gastric carcinogenesis. The increased expressions of AP4, Pbx1 and C/EBPα were further validated by quantitative real-time PCR and Western blot in various H. pylori-infected models such as clinical gastric tissues, gastric epithelial cell lines and Mongolian gerbils. This study provides insights into and potential laws for gene transcriptional regulation by identifying potential TFs targets against the development of H. pylori-associated gastric carcinoma.
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Affiliation(s)
- Ting-Zi Hu
- Department of Gastroenterology, Third Xiangya Hospital of Central South University, 138 Tongzipo Street, Changsha, 410013, Hunan Province, China
| | - Li-Hua Huang
- Center for Medical Experiment, Third Xiangya Hospital, Central South University, Changsha, 410013, Hunan Province, China
| | - Can-Xia Xu
- Department of Gastroenterology, Third Xiangya Hospital of Central South University, 138 Tongzipo Street, Changsha, 410013, Hunan Province, China.
- Hunan Key Laboratory of Nonresolving Inflammation and Cancer, Changsha, 410013, China.
| | - Xiao-Ming Liu
- Department of Gastroenterology, Third Xiangya Hospital of Central South University, 138 Tongzipo Street, Changsha, 410013, Hunan Province, China
| | - Yu Wang
- Department of Internal Medicine, The Third People's Hospital of Huaihua, Huaihua, 418000, Hunan Province, China
| | - Jing Xiao
- Department of Gastroenterology, Third Xiangya Hospital of Central South University, 138 Tongzipo Street, Changsha, 410013, Hunan Province, China
| | - Li Zhou
- Department of Gastroenterology, Third Xiangya Hospital of Central South University, 138 Tongzipo Street, Changsha, 410013, Hunan Province, China
| | - Ling Luo
- Department of Gastroenterology, Third Xiangya Hospital of Central South University, 138 Tongzipo Street, Changsha, 410013, Hunan Province, China
| | - Xiao-Xia Jiang
- Department of Gastroenterology, Third Xiangya Hospital of Central South University, 138 Tongzipo Street, Changsha, 410013, Hunan Province, China
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21
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Wang Y, Wong MMK, Zhang X, Chiu SK. Ectopic AP4 expression induces cellular senescence via activation of p53 in long-term confluent retinal pigment epithelial cells. Exp Cell Res 2015; 339:135-46. [PMID: 26439195 DOI: 10.1016/j.yexcr.2015.09.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2015] [Revised: 09/16/2015] [Accepted: 09/19/2015] [Indexed: 01/09/2023]
Abstract
When cells are grown to confluence, cell-cell contact inhibition occurs and drives the cells to enter reversible quiescence rather than senescence. Confluent retinal pigment epithelial (RPE) cells exhibiting contact inhibition was used as a model in this study to examine the role of overexpression of transcription factor AP4, a highly expressed transcription factor in many types of cancer, in these cells during long-term culture. We generated stable inducible RPE cell clones expressing AP4 or AP4 without the DNA binding domain (DN-AP4) and observed that, when cultured for 24 days, RPE cells with a high level of AP4 exhibit a large, flattened morphology and even cease proliferating; these changes were not observed in DN-AP4-expressing cells or non-induced cells. In addition, AP4-expressing cells exhibited senescence-associated β-galactosidase activity and the senescence-associated secretory phenotype. We demonstrated that the induced cellular senescence was mediated by enhanced p53 expression and that AP4 regulates the p53 gene by binding directly to two of the three E-boxes present on the promoter of the p53 gene. Moreover, we showed that serum is essential for AP4 in inducing p53-associated cellular senescence. Collectively, we showed that overexpression of AP4 mediates cellular senescence involving in activation of p53 in long-term post-confluent RPE cells.
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Affiliation(s)
- Yiping Wang
- Department of Biomedical Sciences, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong
| | - Matthew Man-Kin Wong
- Department of Biomedical Sciences, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong
| | - Xiaojian Zhang
- Institute of Bioengineering, Zhejiang University of Technology, 18 Chaowang Road, Hangzhou 310014, China
| | - Sung-Kay Chiu
- Department of Biomedical Sciences, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong.
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Abstract
AP4 represents a c-MYC-inducible bHLH-LZ transcription factor, which displays elevated expression in many types of tumors. We found that serum-starved AP4-deficient mouse embryo fibroblasts (MEFs) were unable to resume proliferation and showed a delayed S-phase entry after restimulation. Furthermore, they accumulated as tetraploid cells due to a cytokinesis defect. In addition, AP4 was required for c-MYC-induced cell cycle re-entry. AP4-deficient MEFs displayed decreased expression of CDK2 (cyclin-dependent kinase 2), which we characterized as a conserved and direct AP4 target. Activation of an AP4 estrogen receptor fusion protein (AP4-ER) enhanced proliferation of human diploid fibroblasts in a CDK2-dependent manner. However, in contrast to c-MYC-ER, AP4-ER activation was not sufficient to induce cell cycle re-entry or apoptosis in serum-starved MEFs. AP4-deficiency was accompanied by increased spontaneous and c-MYC-induced DNA damage in MEFs. Furthermore, c-MYC-induced apoptosis was decreased in AP4-deficient MEFs, suggesting that induction of apoptosis by c-MYC is linked to its ability to activate AP4 and thereby cell cycle progression. Taken together, these results indicate that AP4 is a central mediator and coordinator of cell cycle progression in response to mitogenic signals and c-MYC activation. Therefore, inhibition of AP4 function may represent a therapeutic approach to block tumor cell proliferation.
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Chen S, Chiu SK. AP4 activates cell migration and EMT mediated by p53 in MDA-MB-231 breast carcinoma cells. Mol Cell Biochem 2015; 407:57-68. [PMID: 26037074 DOI: 10.1007/s11010-015-2454-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Accepted: 05/16/2015] [Indexed: 11/25/2022]
Abstract
Tumor metastasis is the primary cause of mortality in most cancer patients. Before disassociation from the tumors, most of malignant tumor cells undergo the epithelial-mesenchymal transition to break away from the adhesions between the cells and the surrounding extracellular matrix. Recently, activating enhancer-binding protein (AP4) has been shown to be a mediator of EMT in colorectal cancer and high level of AP4 correlates with poor prognosis in cancer patients. It has been found that AP4 upregulates the genes involved in EMT and cell proliferation in colorectal cancer cells and that the aggressive human breast cancer cells MDA-MB-231 are highly metastatic. Therefore, we tested the hypothesis that AP4 may also affect cell migration and EMT in this cell type. Three different assays, including the wound-healing assay, the Boyden chamber assay, and the cell tracking assay, were employed to confirm that AP4 activated both cell migration and invasion. Immunofluorescence staining and Western blot analysis revealed that the cells underwent EMT when AP4 was upregulated. In contrast, overexpression of dominant-negative AP4, lacking the DNA-binding domain, inactivated the DNA-binding ability of endogenous AP4 and led to lower cell motility. Furthermore, we found that AP4 enhanced p53 expression at both transcriptional and translational levels. Knockdown of p53 by siRNA significantly diminished the activation of cell migration by AP4, indicating that AP4 can regulate cell migration via the activity of p53.
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Affiliation(s)
- Shaopeng Chen
- Department of Biomedical Sciences, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong
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GONG HAI, HAN SHAORONG, YAO HUI, ZHAO HUI, WANG YANMING. AP-4 predicts poor prognosis in non-small cell lung cancer. Mol Med Rep 2014; 10:336-40. [DOI: 10.3892/mmr.2014.2209] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Accepted: 04/04/2014] [Indexed: 11/05/2022] Open
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D'Annibale S, Kim J, Magliozzi R, Low TY, Mohammed S, Heck AJR, Guardavaccaro D. Proteasome-dependent degradation of transcription factor activating enhancer-binding protein 4 (TFAP4) controls mitotic division. J Biol Chem 2014; 289:7730-7. [PMID: 24500709 PMCID: PMC3953283 DOI: 10.1074/jbc.m114.549535] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2014] [Revised: 02/04/2014] [Indexed: 11/06/2022] Open
Abstract
TFAP4, a basic helix-loop-helix transcription factor that regulates the expression of a multitude of genes involved in the regulation of cellular proliferation, stemness, and epithelial-mesenchymal transition, is up-regulated in colorectal cancer and a number of other human malignancies. We have found that, during the G2 phase of the cell division cycle, TFAP4 is targeted for proteasome-dependent degradation by the SCF(βTrCP) ubiquitin ligase. This event requires phosphorylation of TFAP4 on a conserved degron. Expression of a stable TFAP4 mutant unable to interact with βTrCP results in a number of mitotic defects, including chromosome missegregation and multipolar spindles, which eventually lead to the activation of the DNA damage response. Our findings reveal that βTrCP-dependent degradation of TFAP4 is required for the fidelity of mitotic division.
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Affiliation(s)
- Sara D'Annibale
- From the Hubrecht Institute-KNAW and University Medical Center Utrecht
| | - Jihoon Kim
- From the Hubrecht Institute-KNAW and University Medical Center Utrecht
| | - Roberto Magliozzi
- From the Hubrecht Institute-KNAW and University Medical Center Utrecht
| | - Teck Yew Low
- the Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, and
- The Netherlands Proteomics Center, 3584 CH Utrecht, The Netherlands
| | - Shabaz Mohammed
- the Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, and
- The Netherlands Proteomics Center, 3584 CH Utrecht, The Netherlands
| | - Albert J. R. Heck
- the Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, and
- The Netherlands Proteomics Center, 3584 CH Utrecht, The Netherlands
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Jackstadt R, Jung P, Hermeking H. AP4 directly downregulates p16 and p21 to suppress senescence and mediate transformation. Cell Death Dis 2013; 4:e775. [PMID: 23949224 PMCID: PMC3763444 DOI: 10.1038/cddis.2013.282] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2013] [Revised: 07/02/2013] [Accepted: 07/04/2013] [Indexed: 12/14/2022]
Abstract
Here we analyzed the function of the c-MYC-inducible basic helix–loop–helix leucine-zipper transcription factor AP4 in AP4-deficient mouse embryo fibroblasts (MEFs). Loss of AP4 resulted in premature senescence and resistance towards immortalization. Senescence was accompanied by induction of the cyclin-dependent kinase inhibitor-encoding genes p16, a known tumor suppressor, and p21, a previously described target for repression by AP4. Notably, AP4 directly repressed p16 expression via conserved E-box motifs in MEFs and human diploid fibroblasts. Senescence caused by AP4-deficiency was prevented by depletion of p16 and/or p21, demonstrating that these factors mediate senescence caused by AP4 loss. As senescence induced by the loss of AP4 was rescued by ectopic AP4, secondary lesions were not involved in causing premature senescence. Activation of c-MYC resulted in repression of p21 and p16 in AP4+/+, but not in AP4−/− MEFs. Furthermore, after combined expression of c-MYC and mutant RAS in MEFs, AP4 was required for colony formation, anchorage-independent growth and tumor formation in mice. In addition, combined ectopic expression of AP4 and mutant RAS in MEFs resulted in colony formation. However, additional loss of the p53 tumor suppressor was necessary for anchorage-independent growth and tumor formation of MEFs by combined AP4 and mutant RAS expression. In conclusion, this study identified AP4 as an oncogenic antagonist of cellular senescence. AP4 achieves this effect by direct repression of p16 and p21, and may thereby critically contribute to c-MYC function and tumor progression.
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Affiliation(s)
- R Jackstadt
- Experimental and Molecular Pathology, Institute of Pathology, Ludwig-Maximilians-Universität München, Thalkirchner Strasse 36, D-80337 Munich, Germany
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Sengupta S, Mitra S, Bhakat KK. Dual regulatory roles of human AP-endonuclease (APE1/Ref-1) in CDKN1A/p21 expression. PLoS One 2013; 8:e68467. [PMID: 23874636 PMCID: PMC3713036 DOI: 10.1371/journal.pone.0068467] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Accepted: 05/29/2013] [Indexed: 01/02/2023] Open
Abstract
The human AP-endonuclease (APE1/Ref-1), an essential multifunctional protein involved in repair of oxidative DNA damage as well as in transcriptional regulation, is often overexpressed in tumor cells. APE1 was earlier shown to stimulate p53's DNA binding and its transactivation function in the expression of cyclin-dependent kinase inhibitor p21 (CDKN1A) gene. Here, we show APE1's stable binding to p53 cis elements which are required for p53-mediated activation of p21 in p53-expressing wild type HCT116 cells. However, surprisingly, we observed APE1-dependent repression of p21 in isogenic p53-null HCT116 cells. Ectopic expression of p53 in the p53-null cells abrogated this repression suggesting that APE1's negative regulatory role in p21 expression is dependent on the p53 status. We then identified APE1's another binding site in p21's proximal promoter region containing cis elements for AP4, a repressor of p21. Interestingly, APE1 and AP4 showed mutual dependence for p21 repression. Moreover, ectopic p53 in p53-null cells inhibited AP4's association with APE1, their binding to the promoter and p21 repression. These results together establish APE1's role as a co-activator or co-repressor of p21 gene, dependent on p53 status. It is thus likely that APE1 overexpression and inactivation of p53, often observed in tumor cells, promote tumor cell proliferation by constitutively downregulating p21 expression.
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Affiliation(s)
- Shiladitya Sengupta
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Sankar Mitra
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas, United States of America
- Sealy Center for Molecular Medicine, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Kishor K. Bhakat
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas, United States of America
- Sealy Center for Molecular Medicine, University of Texas Medical Branch, Galveston, Texas, United States of America
- * E-mail:
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Down-regulation of AP-4 inhibits proliferation, induces cell cycle arrest and promotes apoptosis in human gastric cancer cells. PLoS One 2012; 7:e37096. [PMID: 22615908 PMCID: PMC3353913 DOI: 10.1371/journal.pone.0037096] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2011] [Accepted: 04/18/2012] [Indexed: 01/23/2023] Open
Abstract
Background AP-4 belongs to the basic helix-loop-helix leucine-zipper subgroup; it controls target gene expression, regulates growth, development and cell apoptosis and has been implicated in tumorigenesis. Our previous studies indicated that AP-4 was frequently overexpressed in gastric cancers and may be associated with the poor prognosis. The purpose of this study is to examine whether silencing of AP-4 can alter biological characteristics of gastric cancer cells. Methods Two specific siRNAs targeting AP-4 were designed, synthesized, and transfected into gastric cancer cell lines and human normal mucosa cells. AP-4 expression was measured with real-time quantitative PCR and Western blot. Cell proliferation and chemo-sensitivity were detected by CCK-8 assay. Cell cycle assay and apoptosis assay were performed by flow cytometer, and relative expression of cell cycle regulators were detected by real-time quantitative PCR and Western blot, expression of the factors involved in the apoptosis pathway were examined in mRNA and protein level. Results The expression of AP-4 was silenced by the siRNAs transfection and the effects of AP-4 knockdown lasted 24 to 96 hrs. The siRNA-mediated silencing of AP-4 suppressed the cellular proliferation, induced apoptosis and sensitized cancer cells to anticancer drugs. In addition, the expression level of p21, p53 and Caspase-9 were increased when AP-4 was knockdown, but the expression of cyclin D1, Bcl-2 and Bcl-xL was inhibited. It didn't induce cell cycle arrest when AP-4 was knockdown in p53 defect gastric cancer cell line Kato-III. Conclusions These results illustrated that gene silencing of AP-4 can efficiently inhibited cell proliferation, triggered apoptosis and sensitized cancer cells to anticancer drugs in vitro, suggesting that AP-4 siRNAs mediated silencing has a potential value in the treatment of human gastric cancer.
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