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Aspriţoiu VM, Stoica I, Bleotu C, Diaconu CC. Epigenetic Regulation of Angiogenesis in Development and Tumors Progression: Potential Implications for Cancer Treatment. Front Cell Dev Biol 2021; 9:689962. [PMID: 34552922 PMCID: PMC8451900 DOI: 10.3389/fcell.2021.689962] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 08/16/2021] [Indexed: 12/15/2022] Open
Abstract
Angiogenesis is a multi-stage process of new blood vessel development from pre-existing vessels toward an angiogenic stimulus. The process is essential for tissue maintenance and homeostasis during embryonic development and adult life as well as tumor growth. Under normal conditions, angiogenesis is involved in physiological processes, such as wound healing, cyclic regeneration of the endometrium, placental development and repairing certain cardiac damage, in pathological conditions, it is frequently associated with cancer development and metastasis. The control mechanisms of angiogenesis in carcinogenesis are tightly regulated at the genetic and epigenetic level. While genetic alterations are the critical part of gene silencing in cancer cells, epigenetic dysregulation can lead to repression of tumor suppressor genes or oncogene activation, becoming an important event in early development and the late stages of tumor development, as well. The global alteration of the epigenetic spectrum, which includes DNA methylation, histone modification, chromatin remodeling, microRNAs, and other chromatin components, is considered one of the hallmarks of cancer, and the efforts are concentrated on the discovery of molecular epigenetic markers that identify cancerous precursor lesions or early stage cancer. This review aims to highlight recent findings on the genetic and epigenetic changes that can occur in physiological and pathological angiogenesis and analyze current knowledge on how deregulation of epigenetic modifiers contributes to tumorigenesis and tumor maintenance. Also, we will evaluate the clinical relevance of epigenetic markers of angiogenesis and the potential use of "epi-drugs" in modulating the responsiveness of cancer cells to anticancer therapy through chemotherapy, radiotherapy, immunotherapy and hormone therapy as anti-angiogenic strategies in cancer.
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Affiliation(s)
| | - Ileana Stoica
- Faculty of Biology, University of Bucharest, Bucharest, Romania
| | - Coralia Bleotu
- Faculty of Biology, University of Bucharest, Bucharest, Romania.,Romanian Academy, Stefan S. Nicolau Institute of Virology, Bucharest, Romania
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Ramadan WS, Zaher DM, Altaie AM, Talaat IM, Elmoselhi A. Potential Therapeutic Strategies for Lung and Breast Cancers through Understanding the Anti-Angiogenesis Resistance Mechanisms. Int J Mol Sci 2020; 21:ijms21020565. [PMID: 31952335 PMCID: PMC7014257 DOI: 10.3390/ijms21020565] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Revised: 12/16/2019] [Accepted: 01/03/2020] [Indexed: 02/07/2023] Open
Abstract
Breast and lung cancers are among the top cancer types in terms of incidence and mortality burden worldwide. One of the challenges in the treatment of breast and lung cancers is their resistance to administered drugs, as observed with angiogenesis inhibitors. Based on clinical and pre-clinical findings, these two types of cancers have gained the ability to resist angiogenesis inhibitors through several mechanisms that rely on cellular and extracellular factors. This resistance is mediated through angiogenesis-independent vascularization, and it is related to cancer cells and their microenvironment. The mechanisms that cancer cells utilize include metabolic symbiosis and invasion, and they also take advantage of neighboring cells like macrophages, endothelial cells, myeloid and adipose cells. Overcoming resistance is of great interest, and researchers are investigating possible strategies to enhance sensitivity towards angiogenesis inhibitors. These strategies involved targeting multiple players in angiogenesis, epigenetics, hypoxia, cellular metabolism and the immune system. This review aims to discuss the mechanisms of resistance to angiogenesis inhibitors and to highlight recently developed approaches to overcome this resistance.
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Affiliation(s)
- Wafaa S. Ramadan
- College of Medicine, University of Sharjah, Sharjah 27272, UAE; (W.S.R.); (D.M.Z.); (A.M.A.); (A.E.)
- Sharjah Institute for Medical Research, University of Sharjah, Sharjah 27272, UAE
| | - Dana M. Zaher
- College of Medicine, University of Sharjah, Sharjah 27272, UAE; (W.S.R.); (D.M.Z.); (A.M.A.); (A.E.)
- Sharjah Institute for Medical Research, University of Sharjah, Sharjah 27272, UAE
| | - Alaa M. Altaie
- College of Medicine, University of Sharjah, Sharjah 27272, UAE; (W.S.R.); (D.M.Z.); (A.M.A.); (A.E.)
- Sharjah Institute for Medical Research, University of Sharjah, Sharjah 27272, UAE
| | - Iman M. Talaat
- College of Medicine, University of Sharjah, Sharjah 27272, UAE; (W.S.R.); (D.M.Z.); (A.M.A.); (A.E.)
- Pathology Department, Faculty of Medicine, Alexandria University, 21526 Alexandria, Egypt
- Correspondence: ; Tel.: +971-65057221
| | - Adel Elmoselhi
- College of Medicine, University of Sharjah, Sharjah 27272, UAE; (W.S.R.); (D.M.Z.); (A.M.A.); (A.E.)
- Department of Physiology, Michigan State University, East Lansing, MI 48824, USA
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Hu X, Lin J, Jiang M, He X, Wang K, Wang W, Hu C, Shen Z, He Z, Lin H, Wu D, Wang M. HIF-1α Promotes the Metastasis of Esophageal Squamous Cell Carcinoma by Targeting SP1. J Cancer 2020; 11:229-240. [PMID: 31892989 PMCID: PMC6930417 DOI: 10.7150/jca.35537] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2019] [Accepted: 09/08/2019] [Indexed: 02/07/2023] Open
Abstract
Background: In microenvironment of malignant tumors, Hypoxia-Inducible Factors (HIF), most importantly HIF-1α, play an important role in regulation of adaptive biological response to hypoxia, promoting angiogenesis and metastasis. However, the underlying mechanism that HIF-1α regulates metastasis needs to be further clarified. Methods: The expressions of HIF-1α and SP1 were detected in 182 samples of esophageal squamous cell carcinoma (ESCC) and adjacent normal tissues by immunohistochemistry (IHC), and the correlation between the expression levels of HIF-1α and SP1 was analyzed. The expression of HIF-1α in ESCC cell lines TE1 and KYSE30 was then detected using qRT-PCR and western blot. The potential binding sites of HIF-1α on the SP1 promoter were analyzed using UCSC and JASPAR databases, verified by chromosomal immunoprecipitation (ChIP) assay and qRT-PCR. The effects of HIF-1α and SP1 on ESCC cell migration and invasion were then tested with Transwell and Matrigel experiments. Results: The expression of HIF-1α in cancer tissues is higher than adjacent normal tissues, and is correlated with metastasis, recurrence and poor prognosis. Upon silencing HIF-1α by siRNA, the invasion and migration ability of ESCC cells were significantly inhibited, which could be restored by the overexpression of SP1. Hypoxic conditions significantly increased the expression of HIF-1α and SP1 at both protein and mRNA levels in ESCC cells. HIF-1α enhanced SP1 transcription through binding to the promoter region. The expression of protein and mRNA levels of SP1 was decreased by silencing HIF-1α in cells. In contrast, overexpression of HIF-1α significantly increased the mRNA and protein levels of SP1. The expression of SP1 in ESCC was positively correlated with the protein expression of HIF-1α and poor prognosis. Conclusion: The results of our study indicate that HIF-1α promotes metastasis of ESCC by targeting SP1 in a hypoxic microenvironment. Further study on this mechanism may elucidate the possibility of HIF-1α and SP1 as new targets for the treatment of ESCC.
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Affiliation(s)
- Xueting Hu
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China 510120.,Department of Thoracic Surgery, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China 510120
| | - Jiatong Lin
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China 510120.,Department of Thoracic Surgery, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China 510120
| | - Ming Jiang
- Department of Thoracic Surgery, Affiliated Cancer Hospital & Institute of Guangzhou Medical University, Guangzhou, China 510120
| | - Xiaotian He
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China 510120.,Department of Thoracic Surgery, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China 510120
| | - Kefeng Wang
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China 510120.,Department of Thoracic Surgery, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China 510120
| | - Wenjian Wang
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China 510120.,Department of Thoracic Surgery, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China 510120
| | - Chuwen Hu
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China 510120.,Department of Thoracic Surgery, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China 510120
| | - Zhiwen Shen
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China 510120.,Department of Thoracic Surgery, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China 510120
| | - Zhanghai He
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China 510120.,Department of Thoracic Surgery, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China 510120
| | - Huayue Lin
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China 510120.,Breast Tumor Center, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China 510120
| | - Duoguang Wu
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China 510120.,Department of Thoracic Surgery, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China 510120
| | - Minghui Wang
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China 510120.,Department of Thoracic Surgery, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China 510120
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Hrgovic I, Doll M, Kleemann J, Wang XF, Zoeller N, Pinter A, Kippenberger S, Kaufmann R, Meissner M. The histone deacetylase inhibitor trichostatin a decreases lymphangiogenesis by inducing apoptosis and cell cycle arrest via p21-dependent pathways. BMC Cancer 2016; 16:763. [PMID: 27716272 PMCID: PMC5045659 DOI: 10.1186/s12885-016-2807-y] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Accepted: 09/23/2016] [Indexed: 01/05/2023] Open
Abstract
Background The formation of new lymphatic vessels provides an additional route for tumour cells to metastasize. Therefore, inhibiting lymphangiogenesis represents an interesting target in cancer therapy. First evidence suggests that histone deacetylase inhibitors (HDACi) may mediate part of their antitumor effects by interfering with lymphangiogenesis. However, the underlying mechanisms of HDACi induced anti-lymphangiogenic properties are not fully investigated so far and in part remain unknown. Methods Human lymphatic endothelial cells (LEC) were cultured in vitro and treated with or without HDACi. Effects of HDACi on proliferation and cell cycle progress were analysed by BrdU assay and flow cytometry. Apoptosis was measured by quantifying mono- and oligonucleosomes in the cytoplasmic fraction of cell lysates. In vitro lymphangiogenesis was investigated using the Matrigel short term lymphangiogenesis assay. The effects of TSA on cell cycle regulatory proteins and apoptosis-related proteins were examined by western blotting, immunofluorescence staining and semi-quantitative RT-PCR. Protein- and mRNA half-life of p21 were analysed by western blotting and quantitative RT-PCR. The activity of the p21 promoter was determined using a dual luciferase assay and DNA-binding activity of Sp1/3 was investigated using EMSA. Furthermore, siRNA assays were performed to analyse the role of p21 and p53 on TSA-mediated anti-lymphangiogenic effects. Results We found that HDACi inhibited cell proliferation and that the pan-HDACi TSA induced G0/G1 arrest in LEC. Cell cycle arrest was accompanied by up-regulation of p21, p27 and p53. Additionally, we observed that p21 protein accumulated in cellular nuclei after treatment with TSA. Moreover, we found that p21 mRNA was significantly up-regulated by TSA, while the protein and mRNA half-life remained largely unaffected. The promoter activity of p21 was enhanced by TSA indicating a transcriptional mechanism. Subsequent EMSA analyses showed increased constitutive Sp1/3-dependent DNA binding in response to HDACi. We demonstrated that p53 was not required for TSA induced p21 expression and growth inhibition of LECs. Interestingly, siRNA-mediated p21 depletion almost completely reversed the anti-proliferative effects of TSA in LEC. In addition, TSA induced apoptosis by cytochrome c release contributed to activating caspases-9, −7 and −3 and downregulating the anti-apoptotic proteins cIAP-1 and −2. Conclusions In conclusion, we demonstrate that TSA - a pan-HDACi - has distinct anti-lymphangiogenic effects in primary human lymphatic endothelial cells by activating intrinsic apoptotic pathway and cell cycle arrest via p21-dependent pathways. Electronic supplementary material The online version of this article (doi:10.1186/s12885-016-2807-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Igor Hrgovic
- Department of Dermatology, Venereology and Allergology, Goethe University, Theodor-Stern Kai 7, Frankfurt/Main, 60590, Germany. .,Klinik für Dermatologie, Venerologie und Allergologie, Klinikum der J. W. Goethe-Universität, Theodor-Stern-Kai 7, Frankfurt am Main, D-60590, Germany.
| | - Monika Doll
- Department of Dermatology, Venereology and Allergology, Goethe University, Theodor-Stern Kai 7, Frankfurt/Main, 60590, Germany
| | - Johannes Kleemann
- Department of Dermatology, Venereology and Allergology, Goethe University, Theodor-Stern Kai 7, Frankfurt/Main, 60590, Germany
| | - Xiao-Fan Wang
- Department of Pharmacology & Cancer Biology, Duke University School of Medicine, C218 LSRC, Box 3813, Durham, NC, 27710, USA
| | - Nadja Zoeller
- Department of Dermatology, Venereology and Allergology, Goethe University, Theodor-Stern Kai 7, Frankfurt/Main, 60590, Germany
| | - Andreas Pinter
- Department of Dermatology, Venereology and Allergology, Goethe University, Theodor-Stern Kai 7, Frankfurt/Main, 60590, Germany
| | - Stefan Kippenberger
- Department of Dermatology, Venereology and Allergology, Goethe University, Theodor-Stern Kai 7, Frankfurt/Main, 60590, Germany
| | - Roland Kaufmann
- Department of Dermatology, Venereology and Allergology, Goethe University, Theodor-Stern Kai 7, Frankfurt/Main, 60590, Germany
| | - Markus Meissner
- Department of Dermatology, Venereology and Allergology, Goethe University, Theodor-Stern Kai 7, Frankfurt/Main, 60590, Germany
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Liu HT, Xing AY, Chen X, Ma RR, Wang YW, Shi DB, Zhang H, Li P, Chen HF, Li YH, Gao P. MicroRNA-27b, microRNA-101 and microRNA-128 inhibit angiogenesis by down-regulating vascular endothelial growth factor C expression in gastric cancers. Oncotarget 2016; 6:37458-70. [PMID: 26460960 PMCID: PMC4741941 DOI: 10.18632/oncotarget.6059] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2015] [Accepted: 09/23/2015] [Indexed: 01/30/2023] Open
Abstract
Vascular Endothelial Growth Factor C (VEGF-C) has critical roles in angiogenesis in human cancers; however, the underlying mechanisms regulating VEGF-C expression remain largely unknown. In the present study, VEGF-C protein expression and the density of blood vessels or lymphatic vessels were determined by immunohistochemistry in 103 cases of gastric cancer tissues. Suppression of VEGF-C by miR-27b, miR-101 and miR-128 was investigated by luciferase assays, Western blot and ELISA. The miRNAs expression levels were detected in human gastric cancers by real-time quantitative PCR. Cell proliferation, migration and invasion assays were performed to assess the effect of miRNAs on gastric cancer cells and human umbilical vascular endothelial cells (HUVECs). Our data showed that high VEGF-C expression was significantly associated with increased tumor size, advanced TNM classification and clinical stage, higher microvessel density (MVD) and lymphatic density (LVD), as well as poor survival in patients with gastric cancer. Furthermore, VEGF-C was found to be a direct target gene of miR-27b, miR-101, and miR-128. The expression levels of the three miRNAs were inversely correlated with MVD. Overexpression of miR-27b, miR-101, or miR-128 suppressed migration, proliferation activity, and tube formation in HUVECs by repressing VEGF-C secretion in gastric cancer cells. We conclude that miR-27b, miR-101 and miR-128 inhibit angiogenesis by down-regulating VEGF-C expression in gastric cancers.
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Affiliation(s)
- Hai-Ting Liu
- Department of Pathology, Qilu Hospital, Shandong University, Jinan, P.R. China
| | - Ai-Yan Xing
- Department of Pathology, Qilu Hospital, Shandong University, Jinan, P.R. China
| | - Xu Chen
- Department of Pathology, Qilu Hospital, Shandong University, Jinan, P.R. China
| | - Ran-Ran Ma
- Department of Pathology, Qilu Hospital, Shandong University, Jinan, P.R. China
| | - Ya-Wen Wang
- Department of Pathology, Qilu Hospital, Shandong University, Jinan, P.R. China
| | - Duan-Bo Shi
- Department of Pathology, Qilu Hospital, Shandong University, Jinan, P.R. China
| | - Hui Zhang
- Department of Pathology, Qilu Hospital, Shandong University, Jinan, P.R. China
| | - Peng Li
- Department of Pathology, Qilu Hospital, Shandong University, Jinan, P.R. China
| | - Hong-Fang Chen
- Department of Pathology, Qilu Hospital, Shandong University, Jinan, P.R. China.,Department of Pathology, Qingzhou Center Hospital, Weifang, P.R. China
| | - Yu-Hong Li
- Department of Pathology, Qilu Hospital, Shandong University, Jinan, P.R. China.,Department of Pathology, Liaocheng Peoples Hospital, Liaocheng, P.R. China
| | - Peng Gao
- Department of Pathology, Qilu Hospital, Shandong University, Jinan, P.R. China
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Choi ES, Nam JS, Jung JY, Cho NP, Cho SD. Modulation of specificity protein 1 by mithramycin A as a novel therapeutic strategy for cervical cancer. Sci Rep 2014; 4:7162. [PMID: 25418289 PMCID: PMC4241519 DOI: 10.1038/srep07162] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Accepted: 11/03/2014] [Indexed: 11/09/2022] Open
Abstract
Cervical cancer is the third most common cancer and the third leading cause of death among women. However, the standard treatment for cervical cancer includes cisplatin, which can cause side effects such as hematological damage or renal toxicity. New innovations in cervical cancer treatment focus on developing more effective and better-tolerated therapies such as Sp1-targeting drugs. Previous studies suggested that mithramycin A (Mith) inhibits the growth of various cancers by decreasing Sp1 protein. However, how Sp1 protein is decreased by Mith is not clear. Few studies have investigated the regulation of Sp1 protein by proteasome-dependent degradation as a possible control mechanism for the regulation of Sp1 in cancer cells. Here, we show that Mith decreased Sp1 protein by inducing proteasome-dependent degradation, thereby suppressing cervical cancer growth through a DR5/caspase-8/Bid signaling pathway. We found that prolonged Mith treatment was well tolerated after systemic administration to mice carrying cervical cancer cells. Reduction of body weight was minimal, indicating that Mith was a good therapeutic candidate for treatment of cancers in which Sp1 is involved in promoting and developing disease.
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Affiliation(s)
- Eun-Sun Choi
- Division of High-risk Pathogen Research, Korea Centers for Disease Control and Prevention, Osong, Republic of Korea
| | - Jeong-Seok Nam
- Lee Gil Ya Cancer and Diabetes Institute, Gachon University, Graduate School of Medicine, Incheon 406-840, Korea
| | - Ji-Youn Jung
- Department of Companion and Laboratory Animal Science, Kongju National University, Yesan 314-701, Republic of Korea
| | - Nam-Pyo Cho
- Department of Oral Pathology, School of Dentistry and Institute of Biodegradable Material, Institute of Oral Bioscience, Brain Korea 21 Project, Chonbuk National University, Jeon-ju 561-756, Republic of Korea
| | - Sung-Dae Cho
- Department of Oral Pathology, School of Dentistry and Institute of Biodegradable Material, Institute of Oral Bioscience, Brain Korea 21 Project, Chonbuk National University, Jeon-ju 561-756, Republic of Korea
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Cheng HT, Hung WC. Inhibition of proliferation, sprouting, tube formation and Tie2 signaling of lymphatic endothelial cells by the histone deacetylase inhibitor SAHA. Oncol Rep 2013; 30:961-7. [PMID: 23754070 DOI: 10.3892/or.2013.2523] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2013] [Accepted: 03/27/2013] [Indexed: 11/05/2022] Open
Abstract
Histone deacetylase (HDAC) inhibitors exert potent inhibitory effects on various types of human cancer. The pioneer drug suberoylanilide hydroxamic acid (SAHA) is currently used in the clinic for cancer treatment. However, the effect of SAHA on tumor lymphangiogenesis is unclear. We recently showed that SAHA suppresses the expression and production of pro-lymphagenic factor vascular endothelial growth factor‑C (VEGF-C) in breast cancer cells. In the present study, the effect of SAHA on lymphatic endothelial cells (LECs) was examined. We generated a lymphatic-like endothelial cell line (named FP01) by overexpressing the master LEC transcription factor PROX1 in EA.hy926 endothelial cells. This cell line exhibited a gene expression pattern and phenotype similar to primarily cultured LECs. SAHA inhibited cell cycle progression and proliferation of FP01 cells. In addition, SAHA suppressed sprouting and tube formation in these cells. Moreover, SAHA attenuated the angiopoietin (Ang)/Tie signaling pathway which plays important roles in the regulation of LEC function. FP01 cells expressed Ang1, Ang2, Tie1 and Tie2, and SAHA dose-dependently reduced the expression of Tie2 in these cells. Tie2 promoter activity was attenuated by SAHA indicating a transcriptional repression. Importantly, Tie2 protein was significantly reduced by SAHA at the concentration in which no alteration of Tie2 mRNA was detected. We found that SAHA enhanced Tie2 protein degradation via the ubiquitin-proteasome pathway, and the expression of c-Cbl, the E3 ligase for Tie2 ubiquitination, rapidly increased after SAHA treatment. Knockdown of c-Cbl reversed SAHA‑induced Tie2 protein degradation. Taken together, our results demonstrate that SAHA impairs the proliferation, sprouting and tube formation of LECs and attenuates Ang/Tie signaling in LECs by downregulating Tie-2 via transcriptional and post-transcriptional mechanisms.
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Affiliation(s)
- Hsueh-Tsen Cheng
- Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung 804, Taiwan, ROC
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