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Charoenkwan P, Chiangjong W, Hasan MM, Nantasenamat C, Shoombuatong W. Review and comparative analysis of machine learning-based predictors for predicting and analyzing of anti-angiogenic peptides. Curr Med Chem 2021; 29:849-864. [PMID: 34375178 DOI: 10.2174/0929867328666210810145806] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 06/17/2021] [Accepted: 06/22/2021] [Indexed: 11/22/2022]
Abstract
Cancer is one of the leading causes of death worldwide and underlying this is angiogenesis that represents one of the hallmarks of cancer. Ongoing effort is already under way in the discovery of anti-angiogenic peptides (AAPs) as a promising therapeutic route by tackling the formation of new blood vessels. As such, the identification of AAPs constitutes a viable path for understanding their mechanistic properties pertinent for the discovery of new anti-cancer drugs. In spite of the abundance of peptide sequences in public databases, experimental efforts in the identification of anti-angiogenic peptides have progressed very slowly owing to its high expenditures and laborious nature. Owing to its inherent ability to make sense of large volumes of data, machine learning (ML) represents a lucrative technique that can be harnessed for peptide-based drug discovery. In this review, we conducted a comprehensive and comparative analysis of ML-based AAP predictors in terms of their employed feature descriptors, ML algorithms, cross-validation methods and prediction performance. Moreover, the common framework of these AAP predictors and their inherent weaknesses are also discussed. Particularly, we explore future perspectives for improving the prediction accuracy and model interpretability, which represents an interesting avenue for overcoming some of the inherent weaknesses of existing AAP predictors. We anticipate that this review would assist researchers in the rapid screening and identification of promising AAPs for clinical use.
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Affiliation(s)
- Phasit Charoenkwan
- Modern Management and Information Technology, College of Arts, Media and Technology, Chiang Mai University, Chiang Mai, Thailand
| | - Wararat Chiangjong
- Pediatric Translational Research Unit, Department of Pediatrics, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok 10400, Thailand
| | - Md Mehedi Hasan
- Tulane Center for Biomedical Informatics and Genomics, Division of Biomedical Informatics and Genomics, John W. Deming Department of Medicine, School of Medicine, Tulane University, New Orleans, LA 70112, United States
| | - Chanin Nantasenamat
- Center of Data Mining and Biomedical Informatics, Faculty of Medical Technology, Mahidol University, Bangkok, Thailand
| | - Watshara Shoombuatong
- Center of Data Mining and Biomedical Informatics, Faculty of Medical Technology, Mahidol University, Bangkok, Thailand
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Laengsri V, Nantasenamat C, Schaduangrat N, Nuchnoi P, Prachayasittikul V, Shoombuatong W. TargetAntiAngio: A Sequence-Based Tool for the Prediction and Analysis of Anti-Angiogenic Peptides. Int J Mol Sci 2019; 20:E2950. [PMID: 31212918 PMCID: PMC6628072 DOI: 10.3390/ijms20122950] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 06/13/2019] [Accepted: 06/14/2019] [Indexed: 11/21/2022] Open
Abstract
Cancer remains one of the major causes of death worldwide. Angiogenesis is crucial for the pathogenesis of various human diseases, especially solid tumors. The discovery of anti-angiogenic peptides is a promising therapeutic route for cancer treatment. Thus, reliably identifying anti-angiogenic peptides is extremely important for understanding their biophysical and biochemical properties that serve as the basis for the discovery of new anti-cancer drugs. This study aims to develop an efficient and interpretable computational model called TargetAntiAngio for predicting and characterizing anti-angiogenic peptides. TargetAntiAngio was developed using the random forest classifier in conjunction with various classes of peptide features. It was observed via an independent validation test that TargetAntiAngio can identify anti-angiogenic peptides with an average accuracy of 77.50% on an objective benchmark dataset. Comparisons demonstrated that TargetAntiAngio is superior to other existing methods. In addition, results revealed the following important characteristics of anti-angiogenic peptides: (i) disulfide bond forming Cys residues play an important role for inhibiting blood vessel proliferation; (ii) Cys located at the C-terminal domain can decrease endothelial formatting activity and suppress tumor growth; and (iii) Cyclic disulfide-rich peptides contribute to the inhibition of angiogenesis and cell migration, selectivity and stability. Finally, for the convenience of experimental scientists, the TargetAntiAngio web server was established and made freely available online.
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Affiliation(s)
- Vishuda Laengsri
- Department of Clinical Microscopy, Faculty of Medical Technology, Mahidol University, Bangkok 10700, Thailand.
- Center for Research and Innovation, Faculty of Medical Technology, Mahidol University, Bangkok 10700, Thailand.
| | - Chanin Nantasenamat
- Center of Data Mining and Biomedical Informatics, Faculty of Medical Technology, Mahidol University, Bangkok 10700, Thailand.
| | - Nalini Schaduangrat
- Center of Data Mining and Biomedical Informatics, Faculty of Medical Technology, Mahidol University, Bangkok 10700, Thailand.
| | - Pornlada Nuchnoi
- Department of Clinical Microscopy, Faculty of Medical Technology, Mahidol University, Bangkok 10700, Thailand.
- Center for Research and Innovation, Faculty of Medical Technology, Mahidol University, Bangkok 10700, Thailand.
| | - Virapong Prachayasittikul
- Department of Clinical Microbiology and Applied Technology, Faculty of Medical Technology, Mahidol University, Bangkok 10700, Thailand.
| | - Watshara Shoombuatong
- Center of Data Mining and Biomedical Informatics, Faculty of Medical Technology, Mahidol University, Bangkok 10700, Thailand.
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IKKβ activates p53 to promote cancer cell adaptation to glutamine deprivation. Oncogenesis 2018; 7:93. [PMID: 30478303 PMCID: PMC6255781 DOI: 10.1038/s41389-018-0104-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2018] [Revised: 11/01/2018] [Accepted: 11/14/2018] [Indexed: 01/08/2023] Open
Abstract
One of the hallmarks of cancer is the ability to reprogram cellular metabolism to increase the uptake of necessary nutrients such as glucose and glutamine. Driven by oncogenes, cancer cells have increased glutamine uptake to support their highly proliferative nature. However, as cancer cells continue to replicate and grow, they lose access to vascular tissues and deplete local supply of nutrients and oxygen. We previously showed that many tumor cells situate in a low glutamine microenvironment in vivo, yet the mechanisms of how they are able to adapt to this metabolic stress are still not fully understood. Here, we report that IκB-kinase β (IKKβ) is needed to promote survival and its activation is accompanied by phosphorylation of the metabolic sensor, p53, in response to glutamine deprivation. Knockdown of IKKβ decreases the level of wild-type and mutant p53 phosphorylation and its transcriptional activity, indicating a novel relationship between IKKβ and p53 in mediating cancer cell survival in response to glutamine withdrawal. Phosphopeptide mass spectrometry analysis further reveals that IKKβ phosphorylates p53 on Ser392 to facilitate its activation upon glutamine deprivation, independent of the NF-κB pathway. The results of this study offer an insight into the metabolic reprogramming in cancer cells that is dependent on a previously unidentified IKKβ–p53 signaling axis in response to glutamine depletion. More importantly, this study highlights a new therapeutic strategy for cancer treatment and advances our understanding of adaptive mechanisms that could lead to resistance to current glutamine targeting therapies.
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Venugopal S, Kao C, Chandna R, Sulochana KN, Subramanian V, Chen M, Kini RM, Ge R. Angio-3, a 10-residue peptide derived from human plasminogen kringle 3, suppresses tumor growth in mice via impeding both angiogenesis and vascular permeability. Angiogenesis 2018; 21:653-665. [DOI: 10.1007/s10456-018-9616-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 04/18/2018] [Indexed: 12/12/2022]
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Xu Z, Zuo Y, Wang J, Yu Z, Peng F, Chen Y, Dong Y, Hu X, Zhou Q, Ma H, Bao Y, Chen M. Overexpression of the regulator of G-protein signaling 5 reduces the survival rate and enhances the radiation response of human lung cancer cells. Oncol Rep 2015; 33:2899-907. [PMID: 25891540 DOI: 10.3892/or.2015.3917] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2014] [Accepted: 01/13/2015] [Indexed: 11/05/2022] Open
Abstract
Regulator of G protein signaling 5 (RGS5) belongs to the R4 subfamily of RGS proteins, a family of GTPase activating proteins, which is dynamically regulated in various biological processes including blood pressure regulation, smooth muscle cell pathology, fat metabolism and tumor angiogenesis. Low-expression of RGS5 was reported to be associated with tumor progression in lung cancer. In the present study, we examined the potential roles of RGS5 in human lung cancer cells by overexpressing RGS5 in the cancer cells and further explored the underlying molecular mechanisms. The RGS5 gene was cloned and transfected into the human lung cancer cell lines A549 and Calu-3. The cells were tested for apoptosis with flow cytometry, for viability with MTT, for mobility and adhesion capacity. The radiosensitization effect of RGS5 was measured by a colony formation assay. The mechanisms of RGS5 functioning was also investigated by detection of protein expression with western blot analysis, including PARP, caspase 3 and 9, bax, bcl2, Rock1, Rock2, CDC42, phospho-p53 (Serine 15) and p53. The present study demonstrated that RGS5 overexpression remarkably induced apoptosis in human lung cancer cells, which was suggested to be through mitochondrial mechanisms. Overexpression of RGS5 resulted in significantly lower adhesion and migration abilities of the lung cancer cells (P<0.01). Furthermore, overexpression of RGS5 sensitized the lung cancer cells to radiation. In conclusion, the present study showed that RGS5 played an inhibitory role in human lung cancer cells through induction of apoptosis. Furthermore, RGS5 enhanced the cytotoxic effect of radiation in the human lung cancer cells. Our results indicated that RGS5 may be a potential target for cancer therapy.
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Affiliation(s)
- Zumin Xu
- Department of Radiation Oncology, Sun Yat-Sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, Guangdong 510060, P.R. China
| | - Yufang Zuo
- Cancer Center, Affiliated Hospital of Guangdong Medical College, Zhanjiang, Guangdong 524000, P.R. China
| | - Jin Wang
- Zhejiang Cancer Hospital, Hangzhou, Zhejiang 310012, P.R. China
| | - Zhonghua Yu
- Cancer Center, Affiliated Hospital of Guangdong Medical College, Zhanjiang, Guangdong 524000, P.R. China
| | - Fang Peng
- Department of Radiation Oncology, Sun Yat-Sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, Guangdong 510060, P.R. China
| | - Yuanyuan Chen
- Zhejiang Cancer Hospital, Hangzhou, Zhejiang 310012, P.R. China
| | - Yong Dong
- Cancer Center, Shilong People's Hospital, Dongguan City, Guangdong 523321, P.R. China
| | - Xiao Hu
- Department of Radiation Oncology, Sun Yat-Sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, Guangdong 510060, P.R. China
| | - Qichao Zhou
- Department of Radiation Oncology, Sun Yat-Sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, Guangdong 510060, P.R. China
| | - Honglian Ma
- Zhejiang Cancer Hospital, Hangzhou, Zhejiang 310012, P.R. China
| | - Yong Bao
- Department of Radiation Oncology, Sun Yat-Sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, Guangdong 510060, P.R. China
| | - Ming Chen
- Department of Radiation Oncology, Sun Yat-Sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, Guangdong 510060, P.R. China
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Acidic/neutral amino acid residues substitution in NH2 terminal of plasminogen kringle 5 exerts enhanced effects on corneal neovascularization. Cornea 2013; 32:680-8. [PMID: 23343948 DOI: 10.1097/ico.0b013e3182781ec9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE Recent results showed that plasminogen kringle 5 (K5) has improved inhibitory effect on human umbilical vein endothelial cells (HUVECs) viability when 5 acidic amino acids in NH2 terminal outside kringle domain were replaced by 5 serine residues (mutant K5, mK5). This study was designed to identify the enhanced antiangiogenic activity of mK5 in corneal neovascularization (CNV). METHODS Alkali burn-induced CNV was induced and treated with K5 and mK5 for 11 days. CNV and inflammation were evaluated by the CNV area and the inflammatory index, respectively. At the end of treatment, the corneas were removed for terminal deoxynucleotidyl transferase dUTP nick end labeling detection and immunohistochemistry. The effects of mK5 and K5 on HUVECs apoptosis were tested by MTT, BrdU, and flow cytometry. The expression levels of pigment epithelium-derived factor (PEDF) and vascular endothelial growth factor (VEGF) were detected by Western blot. RESULTS In a rat model of CNV induced by alkali, topical treatment with mK5 significantly decreased the neovascular area and inflammation compared with the wild-type K5-treated group. Meanwhile, mK5 and K5 specifically inhibited the HUVECs proliferation and induced vascular endothelial cell apoptosis in vitro and in vivo, and mK5 exerted higher apoptosis induction. Toward the mechanism of action, both mK5 and K5 significantly upregulated the expression of PEDF and mildly downregulated the expression of VEGF. The elevation of PEDF/VEGF ratio induced by mK5 was higher than that by K5. CONCLUSIONS These findings suggest that mK5 has more effective therapeutic potential in CNV than wild-type K5.
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Cai WB, Zhang Y, Cheng R, Wang Z, Fang SH, Xu ZM, Yang X, Yang ZH, Ma JX, Shao CK, Gao GQ. Dual inhibition of plasminogen kringle 5 on angiogenesis and chemotaxis suppresses tumor metastasis by targeting HIF-1α pathway. PLoS One 2012; 7:e53152. [PMID: 23300882 PMCID: PMC3534244 DOI: 10.1371/journal.pone.0053152] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2012] [Accepted: 11/26/2012] [Indexed: 11/26/2022] Open
Abstract
We had demonstrated that plasminogen kringle 5 (K5), a potent angiogenic inhibitor, inhibited retinal neovascularization and hepatocellular carcinoma growth by anti-angiogenesis. The current study investigated the effects and the underlying mechanisms of K5 on both tumor growth and spontaneous pulmonary metastasis in Lewis lung carcinoma (LLC) implanted mouse model. Similarly, K5 could decrease expression of VEGF in LLC cells and grafted tissues and suppress tumor angiogenesis and growth. K5 had no direct effect on proliferation and apoptosis of LLC. However, K5 could significantly inhibit SDF-1α-induced chemotaxis movement of LLC cells and resulted in a great reduction of surface metastatic nodules and micrometastases in the lungs of LLC tumor-bearing mice. K5 also decreased expression of chemokine (C-X-C motif) receptor 4 (CXCR4) in LLC cells and grafted tissues. Furthermore, K5 down-regulated SDF-1α expression in metastatic lung tissues of LLC-bearing mice. Therefore, K5 may suppress tumor pulmonary metastasis through inhibiting SDF-1α-CXCR4 chemotaxis movement and down-regulation of VEGF. Moreover, the role of hypoxia inducible factor-1α (HIF-1α), a crucial transcriptional factor for both VEGF and CXCR4 expression, was evaluated. The siRNA of HIF-1α attenuated expression of VEGF and CXCR4 and inhibited LLC migration. K5 decreased HIF-1α protein level and impaired nuclear HIF-1α accumulation. These results showed for the first time that K5 inhibits LLC growth and metastasis via the dual effects of anti-angiogenesis and suppression of tumor cell motility by targeting the pivotal molecule, HIF-1α.
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Affiliation(s)
- Wei-Bin Cai
- Department of Biochemistry, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Yang Zhang
- Department of Biochemistry, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Rui Cheng
- Department of Biochemistry, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Zheng Wang
- Department of Biochemistry, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Shu-Huan Fang
- Department of Biochemistry, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
- DME Center, Clinical Pharmacology Institute, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Zu-Min Xu
- Department of Biochemistry, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Xia Yang
- Department of Biochemistry, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
- Key Laboratory of Functional Molecules from Marine Microorganisms (Sun Yat-sen University), Department of Education of Guangdong Province, Guangzhou, China
| | - Zhong-Han Yang
- Department of Biochemistry, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Jian-Xing Ma
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America
| | - Chun-Kui Shao
- Department of Pathology, the Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
- * E-mail: (GQG); (CKS)
| | - Guo-Quan Gao
- Department of Biochemistry, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
- China Key Laboratory of Tropical Disease Control (Sun Yat-sen University), Ministry of Education, Guangzhou, China
- * E-mail: (GQG); (CKS)
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Jiang W, Jin G, Ma D, Wang F, Fu T, Chen X, Chen X, Jia K, Marikar FMMT, Hua Z. Modification of cyclic NGR tumor neovasculature-homing motif sequence to human plasminogen kringle 5 improves inhibition of tumor growth. PLoS One 2012; 7:e37132. [PMID: 22590653 PMCID: PMC3349653 DOI: 10.1371/journal.pone.0037132] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2011] [Accepted: 04/14/2012] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Blood vessels in tumors express higher level of aminopeptidase N (APN) than normal tissues. Evidence suggests that the CNGRC motif is an APN ligand which targets tumor vasculature. Increased expression of APN in tumor vascular endothelium, therefore, offers an opportunity for targeted delivery of NGR peptide-linked drugs to tumors. METHODS/PRINCIPAL FINDINGS To determine whether an additional cyclic CNGRC sequence could improve endothelial cell homing and antitumor effect, human plasminogen kringle 5 (hPK5) was modified genetically to introduce a CNGRC motif (NGR-hPK5) and was subsequently expressed in yeast. The biological activity of NGR-hPK5 was assessed and compared with that of wild-type hPK5, in vitro and in vivo. NGR-hPK5 showed more potent antiangiogenic activity than wild-type hPK5: the former had a stronger inhibitory effect on proliferation, migration and cord formation of vascular endothelial cells, and produced a stronger antiangiogenic response in the CAM assay. To evaluate the tumor-targeting ability, both wild-type hPK5 and NGR-hPK5 were (99 m)Tc-labeled, for tracking biodistribution in the in vivo tumor model. By planar imaging and biodistribution analyses of major organs, NGR-hPK5 was found localized to tumor tissues at a higher level than wild-type hPK5 (approximately 3-fold). Finally, the effects of wild-type hPK5 and NGR-modified hPK5 on tumor growth were investigated in two tumor model systems. NGR modification improved tumor localization and, as a consequence, effectively inhibited the growth of mouse Lewis lung carcinoma (LLC) and human colorectal adenocarcinoma (Colo 205) cells in tumor-bearing mice. CONCLUSIONS/SIGNIFICANCE These studies indicated that the addition of an APN targeting peptide NGR sequence could improve the ability of hPK5 to inhibit angiogenesis and tumor growth.
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Affiliation(s)
- Weiwei Jiang
- The State Key Laboratory of Pharmaceutical Biotechnology and School of Stomatology, Affiliated Stomatological Hospital, Nanjing University, Nanjing, People's Republic of China
| | - Guanghui Jin
- The State Key Laboratory of Pharmaceutical Biotechnology and School of Stomatology, Affiliated Stomatological Hospital, Nanjing University, Nanjing, People's Republic of China
- Department of Basic Medical Sciences, Medical College, Xiamen University, Xiamen, People's Republic of China
| | - Dingyuan Ma
- The State Key Laboratory of Pharmaceutical Biotechnology and School of Stomatology, Affiliated Stomatological Hospital, Nanjing University, Nanjing, People's Republic of China
| | - Feng Wang
- Department of Nuclear Medicine, The Affiliated Nanjing First Hospital, Nanjing Medical University, Nanjing, People's Republic of China
| | - Tong Fu
- Department of Nuclear Medicine, The Affiliated Nanjing First Hospital, Nanjing Medical University, Nanjing, People's Republic of China
| | - Xiao Chen
- The State Key Laboratory of Pharmaceutical Biotechnology and School of Stomatology, Affiliated Stomatological Hospital, Nanjing University, Nanjing, People's Republic of China
| | - Xiwen Chen
- The State Key Laboratory of Pharmaceutical Biotechnology and School of Stomatology, Affiliated Stomatological Hospital, Nanjing University, Nanjing, People's Republic of China
| | - Kunzhi Jia
- The State Key Laboratory of Pharmaceutical Biotechnology and School of Stomatology, Affiliated Stomatological Hospital, Nanjing University, Nanjing, People's Republic of China
| | - Faiz M. M. T. Marikar
- The State Key Laboratory of Pharmaceutical Biotechnology and School of Stomatology, Affiliated Stomatological Hospital, Nanjing University, Nanjing, People's Republic of China
| | - Zichun Hua
- The State Key Laboratory of Pharmaceutical Biotechnology and School of Stomatology, Affiliated Stomatological Hospital, Nanjing University, Nanjing, People's Republic of China
- Changzhou High-Tech Research Institute of Nanjing University, Changzhou, People's Republic of China
- * E-mail:
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Ma J, Li C, Shao C, Gao G, Yang X. Decreased K5 receptor expression in the retina, a potential pathogenic mechanism for diabetic retinopathy. Mol Vis 2012; 18:330-6. [PMID: 22355244 PMCID: PMC3283210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Accepted: 02/01/2012] [Indexed: 10/26/2022] Open
Abstract
PURPOSE Plasminogen kringle 5 (K5) is a potent angiogenic inhibitor and specifically binds to the voltage-dependent anion channel believed to function as the K5 receptor (K5R). To investigate the role of K5R in diabetic retinopathy, the present study measured the expression levels of K5R in the retina of diabetic retinopathy models. In cultured retinal Müller cells, K5 inhibited vascular endothelial growth factor (VEGF) expression as shown with enzyme-linked immunosorbent assay and western blot analysis, suggesting that K5 has a direct effect on Müller cells. METHODS To identify K5R in retinal Müller cells, ligand binding and competition assays as well as real-time reverse transcriptional polymerase chain reaction were performed in Müller cells. (125)I-K5 showed saturable binding to cultured Müller cells. The binding can be competed off by an excess amount of unlabeled K5 but not by angiostatin, demonstrating the specificity of the K5 binding to Müller cells. Consistent with the binding assay, reverse transcriptional polymerase chain reaction using voltage-dependent anion channel-specific primers detected the K5R mRNA in the Müller cells. RESULTS Interestingly, K5R mRNA expression in Müller cells was downregulated by diabetic conditions including hypoxia and high glucose medium. Incubation with K5 ligand prevented hypoxia-induced downregulation of K5R. Furthermore, K5R expression was also downregulated in the retina of the oxygen-induced retinopathy model, a model of ischemia-induced retinal neovascularization. In a type 1 diabetic rat model, K5R expression in the retina was significantly suppressed in rats that had diabetes for 5 and 8 weeks. CONCLUSIONS These results suggest that K5R is expressed in retinal Müller cells, which may mediate the inhibitory effect of K5 on VEGF expression. In diabetes conditions, K5R expression levels are decreased in the retina, which could contribute to the VEGF overexpression in diabetic retinopathy. These findings suggest that the decreased levels of K5R may also play a pathogenic role in diabetic retinopathy.
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Affiliation(s)
- Jianfang Ma
- Department of Medicine, PLA 476th Hospital, Fuzhou, China,Department of Biochemistry, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, Guangdong Province, China
| | - Chaoyang Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Chunkui Shao
- Department of Pathology, The Third Affiliated Hospital, Sun Yet-sen University, Guangzhou, China
| | - Guoquan Gao
- Department of Biochemistry, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, Guangdong Province, China,China Key Laboratory of Tropical Disease Control, Sun Yat-sen University, Ministry of Education, Guangzhou, China
| | - Xia Yang
- Department of Biochemistry, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, Guangdong Province, China,Key Laboratory of Functional Molecules from Marine Microorganisms, Sun Yat-sen University, Department of Education of Guangdong Province, Guangzhou, China
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Anti-tumor activity of CrTX in human lung adenocarcinoma cell line A549. Acta Pharmacol Sin 2011; 32:1397-401. [PMID: 21946324 DOI: 10.1038/aps.2011.116] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
AIM To assess the cytotoxic effect of crotoxin (CrTX), a potent neurotoxin extracted from the venom of the pit viper Crotalus durissus terrificus, in human lung adenocarcinoma A549 cells and investigated the underlying mechanisms. METHODS A549 cells were treated with gradient concentrations of CrTX, and the cell cycle and apoptosis were analyzed using a flow cytometric assay. The changes of cellular effectors p53, caspase-3 and cleaved caspase-3, total P38MAPK and pP38MAPK were investigated using Western blot assays. A549 xenograft model was used to examine the inhibition of CrTX on tumor growth in vivo. RESULTS Treatment of A549 cells with CrTX (25-200 μg/mL) for 48 h significantly inhibited the cell growth in a dose-dependent manner (IC(50)=78 μg/mL). Treatment with CrTX (25 μg/mL) for 24 h caused G1 arrest and induced cell apoptosis. CrTX (25 μg/mL) significantly increased the expression of wt p53, cleaved caspase-3 and phospho-P38MAPK. Pretreatment with the specific P38MAPK inhibitor SB203580 (5 μmol/L) significantly reduced CrTX-induced apoptosis and cleaved caspase-3 level, but G(1) arrest remained unchanged and highly expressed p53 sustained. Intraperitoneal injection of CrTX (10 μg/kg, twice a week for 4 weeks) significantly inhibited A549 tumor xenograft growth, and decreased MVD and VEGF levels. CONCLUSION CrTX produced significant anti-tumor effects by inducing cell apoptosis probably due to activation of P38MAPK and caspase-3, and by cell cycle arrest mediated by increased wt p53 expression. In addition, CrTX displayed anti-angiogenic effects in vivo.
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Hyperactivation of NF-κB via the MEK signaling is indispensable for the inhibitory effect of cAMP on DNA damage-induced cell death. Mol Cancer 2011; 10:45. [PMID: 21510868 PMCID: PMC3095569 DOI: 10.1186/1476-4598-10-45] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2010] [Accepted: 04/21/2011] [Indexed: 12/31/2022] Open
Abstract
With cAMP signaling having a profound inhibitory effect on DNA damage-induced apoptosis in B-cell precursor acute lymphoblastic leukemia (BCP-ALL) cells, understanding how this signaling pathway affects the survival capacity of the cell has important implications for cancer therapy. We have recently shown that p53 is critical for the inhibitory effect of cAMP on genotoxic agents-mediated apoptosis in BCP-ALLs. Here, we show that elevation of cAMP levels in cells exposed to DNA damage enhances the nuclear translocation and DNA binding of NF-κB by accelerating the phosphorylation of IKKβ and thereby phosphorylation and degradation of IκBα. Furthermore, we show that the ability of cAMP to potentiate the ionizing radiation-induced activation of NF-κB requires the activity of MEK. Importantly, pharmacological or genetic ablation of NF-κB reversed the inhibitory effect of cAMP on DNA damage-induced apoptosis, demonstrating that, in addition to p53, cAMP relies on the activity of NF-κB to provide cells with a survival advantage in the face of DNA damage. Collectively, our results uncover a novel and important interaction between the cAMP and NF-κB pathways that may have implications for the targeted treatment of lymphoid malignancies, such as BCP-ALL, in which aberrant NF-κB activity functions as a driving force for treatment resistance.
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