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Wang R, Chen Z, Zhang Y, Xiao S, Zhang W, Hu X, Xiao Q, Liu Q, Wang X. Flotillin-1 is a prognostic biomarker for glioblastoma and promotes cancer development through enhancing invasion and altering tumour microenvironment. J Cell Mol Med 2023; 27:392-402. [PMID: 36647700 PMCID: PMC9889621 DOI: 10.1111/jcmm.17660] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 12/18/2022] [Accepted: 12/25/2022] [Indexed: 01/18/2023] Open
Abstract
Flotillin-1(FLOT1) has long been recognized as a tumour-promoting gene in several types of cancer. However, the expression and function of FLOT1 in glioblastomas (GBM) has not been elucidated. Here, in this study, we find that the expression level of FLOT1 in GBM tissue was much higher than that in normal brain, and the expression was even higher in the more aggressive subtypes and IDH status of glioma. Kaplan-Meier survival revealed that high FLOT1 expression is closely associated with poor outcome in GBM patients. FLOT1 knockdown markedly reduced the proliferation, migration and invasiveness of GBM cells, while FLOT1 overexpression significantly increases GBM cell proliferation, migration and invasiveness. Mechanistically, FLOT1 expression may play a potential role in the microenvironment of GBM. Therefore, FLOT1 promotes GBM proliferation and invasion in vitro and in vivo and may serve as a biomarker of prognosis and therapeutic potential in the fight against GBM.
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Affiliation(s)
- Ran Wang
- Department of Colorectal and Anus Surgery, Xiangya HospitalCentral South UniversityChangshaHunanChina,The Hunan Provincial Key Lab of Precision Diagnosis and Treatment for Gastrointestinal Tumor, Xiangya HospitalCentral South UniversityChangshaHunanChina
| | - Zhikang Chen
- Department of Colorectal and Anus Surgery, Xiangya HospitalCentral South UniversityChangshaHunanChina,The Hunan Provincial Key Lab of Precision Diagnosis and Treatment for Gastrointestinal Tumor, Xiangya HospitalCentral South UniversityChangshaHunanChina
| | - Yi Zhang
- Department of Neurosurgery, Dengzhou People's HospitalDengzhouHenanChina
| | - Shihan Xiao
- Department of Colorectal and Anus Surgery, Xiangya HospitalCentral South UniversityChangshaHunanChina
| | - Wuming Zhang
- Department of Colorectal and Anus Surgery, Xiangya HospitalCentral South UniversityChangshaHunanChina
| | - Xianqin Hu
- Department of Colorectal and Anus Surgery, Xiangya HospitalCentral South UniversityChangshaHunanChina
| | - Qun Xiao
- Department of Neurosurgery, Xiangya HospitalCentral South UniversityChangshaHunanChina
| | - Qing Liu
- Department of Neurosurgery, Xiangya HospitalCentral South UniversityChangshaHunanChina
| | - Xiangyu Wang
- Department of Neurosurgery, Xiangya HospitalCentral South UniversityChangshaHunanChina
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2
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Yu C, Zhang H, Liu S, Li R, Zhao X, Chen Y, Li Z, Ma J, Wang W, Ye Z, Liang X, Zhang L, Shi W. Flot2 acts as a novel mediator of podocyte injury in proteinuric kidney disease. Int J Biol Sci 2023; 19:502-520. [PMID: 36632460 PMCID: PMC9830511 DOI: 10.7150/ijbs.78945] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Accepted: 11/30/2022] [Indexed: 12/23/2022] Open
Abstract
Podocyte injury is a common hallmark of chronic kidney disease (CKD). The podocin-nephrin complex localized in lipid rafts of podocyte is vital to reduce podocyte injury and proteinuria, however, the mechanism underlying its localization remains unclear. This study uncovers an important role of Flot2 in stabilizing the podocin-nephrin complex localized in lipid rafts. We first confirmed that Flot2 was expressed in podocyte and demenstrated that podocyte-specific Flot2 deletion worsen albuminuria, podocyte injury and glomerular pathology in LPS/ADR-induced nephropathy mouse models. Meanwhile, podocyte injury, albuminuria and pathologic aberrance were prevented in podocyte-specific Flot2 overexpression transgenic mice when challenged with LPS or ADR. Further found that Flot2 was vital to recruit podocin and nephrin into rafts and ameliorated podocyte injury. Flot2 and podocin directly interacted with each other via their SPFH domain. Meanwhile, we also showed that Flot-2 is a direct target of Krüppel-like factor (KLF15). Importanly, we observed that Flot2 was downregulated in renal biopsies from patients with podocytopathies and its expression negatively correlated with proteinuria and positively correlated with eGFR, indicating that Flot2 may be a novel therapeutic target for proteinuric kidney disease.
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Affiliation(s)
- Chunping Yu
- Department of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, 106 Zhongshan No. 2 Road, Guangzhou, 510080, China.,State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, P. R. China
| | - Hong Zhang
- Department of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, 106 Zhongshan No. 2 Road, Guangzhou, 510080, China
| | - Shuangxin Liu
- Department of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, 106 Zhongshan No. 2 Road, Guangzhou, 510080, China
| | - Ruizhao Li
- Department of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, 106 Zhongshan No. 2 Road, Guangzhou, 510080, China
| | - Xingchen Zhao
- Department of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, 106 Zhongshan No. 2 Road, Guangzhou, 510080, China
| | - Yuanhan Chen
- Department of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, 106 Zhongshan No. 2 Road, Guangzhou, 510080, China
| | - Zhuo Li
- Department of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, 106 Zhongshan No. 2 Road, Guangzhou, 510080, China
| | - Jianchao Ma
- Department of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, 106 Zhongshan No. 2 Road, Guangzhou, 510080, China
| | - Wenjian Wang
- Department of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, 106 Zhongshan No. 2 Road, Guangzhou, 510080, China
| | - Zhiming Ye
- Department of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, 106 Zhongshan No. 2 Road, Guangzhou, 510080, China
| | - Xinling Liang
- Department of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, 106 Zhongshan No. 2 Road, Guangzhou, 510080, China.,✉ Corresponding authors: Xinling Liang, Li Zhang, or Wei Shi. Department of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, 106 Zhongshan No. 2 Road, Guangzhou, 510080, China. E-mail: ; ; ; Phone: +86 13802793488; +86 13202067354; +86 13808819770; Fax: +86-20-83827812-62027
| | - Li Zhang
- Department of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, 106 Zhongshan No. 2 Road, Guangzhou, 510080, China.,✉ Corresponding authors: Xinling Liang, Li Zhang, or Wei Shi. Department of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, 106 Zhongshan No. 2 Road, Guangzhou, 510080, China. E-mail: ; ; ; Phone: +86 13802793488; +86 13202067354; +86 13808819770; Fax: +86-20-83827812-62027
| | - Wei Shi
- Department of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, 106 Zhongshan No. 2 Road, Guangzhou, 510080, China.,Department of Nephrology, Gaozhou People's Hospital, Gaozhou, P. R. China.,✉ Corresponding authors: Xinling Liang, Li Zhang, or Wei Shi. Department of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, 106 Zhongshan No. 2 Road, Guangzhou, 510080, China. E-mail: ; ; ; Phone: +86 13802793488; +86 13202067354; +86 13808819770; Fax: +86-20-83827812-62027
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Abstract
Flotillins 1 and 2 are two ubiquitous, highly conserved homologous proteins that assemble to form heterotetramers at the cytoplasmic face of the plasma membrane in cholesterol- and sphingolipid-enriched domains. Flotillin heterotetramers can assemble into large oligomers to form molecular scaffolds that regulate the clustering of at the plasma membrane and activity of several receptors. Moreover, flotillins are upregulated in many invasive carcinomas and also in sarcoma, and this is associated with poor prognosis and metastasis formation. When upregulated, flotillins promote plasma membrane invagination and induce an endocytic pathway that allows the targeting of cargo proteins in the late endosomal compartment in which flotillins accumulate. These late endosomes are not degradative, and participate in the recycling and secretion of protein cargos. The cargos of this Upregulated Flotillin–Induced Trafficking (UFIT) pathway include molecules involved in signaling, adhesion, and extracellular matrix remodeling, thus favoring the acquisition of an invasive cellular behavior leading to metastasis formation. Thus, flotillin presence from the plasma membrane to the late endosomal compartment influences the activity, and even modifies the trafficking and fate of key protein cargos, favoring the development of diseases, for instance tumors. This review summarizes the current knowledge on flotillins and their role in cancer development focusing on their function in cellular membrane remodeling and vesicular trafficking regulation.
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4
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Increase in fatty acids and flotillins upon resveratrol treatment of human breast cancer cells. Sci Rep 2019; 9:13960. [PMID: 31562347 PMCID: PMC6764983 DOI: 10.1038/s41598-019-50416-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Accepted: 09/06/2019] [Indexed: 12/11/2022] Open
Abstract
Flotillin-1 and flotillin-2 are highly conserved proteins that localize into cholesterol-rich microdomains in cellular membranes. Flotillins are closely related to the occurrence and development of various types of human cancers. Flotillin-1 is highly expressed in breast cancer, and the high expression level of flotillin-1 is significantly correlated with poorer patient survival. Here we studied the relationship between the formation of lipid rafts and the expression of flotillins and lipids in human breast cancer cells. We used the polyphenol compound resveratrol to alter the structure and function of the plasma membrane. Our data revealed an increase in fatty acids in MCF-7 and MDA-MB-231 cells upon resveratrol treatment. Interestingly, we also found an increase in the expression of both flotillin-1 and flotillin-2 in breast tumor cells after treatment. Resveratrol also induced changes in the pattern of flotillin distribution among detergent-resistant lipid rafts fractions in both cell lines and induced the nuclear translocation of flotillin-2. Since resveratrol has been pointed out as a putative cancer therapy agent, our results could have an impact on the understanding of the effects of resveratrol in tumor cells.
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Infection by Anaplasma phagocytophilum Requires Recruitment of Low-Density Lipoprotein Cholesterol by Flotillins. mBio 2019; 10:mBio.02783-18. [PMID: 30914515 PMCID: PMC6437059 DOI: 10.1128/mbio.02783-18] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Anaplasma phagocytophilum is an obligatory intracellular bacterium that proliferates in membrane-bound inclusions. A. phagocytophilum is dependent on cholesterol and acquire cholesterol from low-density lipoprotein (LDL) endocytosed by mammalian host cells. The mechanism of cholesterol transport to Anaplasma inclusions, however, is not fully understood. Flotillin-1 (FLOT1) and FLOT2 are cholesterol-associated membrane proteins that form a heterodimer and/or oligomer complex. Here, we found that Anaplasma infection was significantly reduced by small interfering RNA (siRNA) knockdown of FLOT1 or FLOT2. Anaplasma inclusions were encircled with small vesicles containing endogenous FLOT1 or FLOT2 or with ectopically expressed FLOT1-mCherry and FLOT2-green fluorescent protein (FLOT2-GFP). FLOT1- and FLOT2-containing vesicles were enriched with unesterified cholesterol, as indicated by labeling with filipin and aminomethyl coumarin acetic acid-conjugated theonellamide. Localization of FLOT2 to Anaplasma inclusions was dependent on cholesterol, as FLOT2-GFP bearing two mutations in the cholesterol recognition/interaction motif could not target the inclusions. The cholesterol-sequestering agent methyl-β-cyclodextrin abrogated FLOT1 localization to Anaplasma inclusions and cleared infection. FLOT2-GFP also localized to fluorescent 3,3'-dioctadecylindocarbocyanine (DiI)-LDL-containing vesicles, including those surrounding Anaplasma inclusions. FLOT2 siRNA knockdown blocked DiI-LDL trafficking to Anaplasma inclusions and reduced bacteria-associated cholesterol amount, and therefore inhibiting Anaplasma infection. Vesicles containing acid lipase, which hydrolyzes LDL cholesterol esters to free cholesterol, colocalized with FLOT2 and encircled Anaplasma inclusions, while the acid lipase inhibitor orlistat significantly inhibited Anaplasma replication. Together, the data revealed that FLOTs are crucial for Anaplasma replication in host cells, likely by aiding vesicular traffic of LDL-derived free cholesterol to Anaplasma inclusions, and suggest a new way of inhibiting Anaplasma infection.IMPORTANCE Cholesterol is essential for animal cells, but most bacteria do not depend on cholesterol and instead lack cholesterol. However, the intracellular Gram-negative bacterium Anaplasma phagocytophilum that causes human granulocytic anaplasmosis (HGA) is unusual, as it contains significant amount of cholesterol and depends on cholesterol for survival and infection. A. phagocytophilum lacks genes for cholesterol biosynthesis or modification but acquire cholesterol from host cells exclusively from the LDL uptake pathway by a yet-to-be defined mechanism. Here, we uncovered a role of cholesterol-binding proteins FLOT1 and FLOT2 in LDL-derived cholesterol trafficking to Anaplasma inclusions and cholesterol acquisition by Anaplasma species. Importantly, we found that FLOTs localize to A. phagocytophilum-containing inclusions and the compartments containing LDL, and the acid lipase inhibitor orlistat significantly inhibits Anaplasma replication. Our data suggest a fundamental role of FLOTs in intracellular vesicular transport of LDL-derived free cholesterol and may provide insight regarding a new therapeutic target for HGA treatment.
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Kessler EL, van Stuijvenberg L, van Bavel JJA, van Bennekom J, Zwartsen A, Rivaud MR, Vink A, Efimov IR, Postma AV, van Tintelen JP, Remme CA, Vos MA, Banning A, de Boer TP, Tikkanen R, van Veen TAB. Flotillins in the intercalated disc are potential modulators of cardiac excitability. J Mol Cell Cardiol 2018; 126:86-95. [PMID: 30452906 DOI: 10.1016/j.yjmcc.2018.11.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 11/12/2018] [Accepted: 11/13/2018] [Indexed: 01/24/2023]
Abstract
BACKGROUND The intercalated disc (ID) is important for cardiac remodeling and has become a subject of intensive research efforts. However, as yet the composition of the ID has still not been conclusively resolved and the role of many proteins identified in the ID, like Flotillin-2, is often unknown. The Flotillin proteins are known to be involved in the stabilization of cadherins and desmosomes in the epidermis and upon cancer development. However, their role in the heart has so far not been investigated. Therefore, in this study, we aimed at identifying the role of Flotillin-1 and Flotillin-2 in the cardiac ID. METHODS Location of Flotillins in human and murine cardiac tissue was evaluated by fluorescent immunolabeling and co-immunoprecipitation. In addition, the effect of Flotillin knockout (KO) on proteins of the ID and in electrical excitation and conduction was investigated in cardiac samples of wildtype (WT), Flotillin-1 KO, Flotilin-2 KO and Flotilin-1/2 double KO mice. Consequences of Flotillin knockdown (KD) on cardiac function were studied (patch clamp and Multi Electrode Array (MEA)) in neonatal rat cardiomyocytes (NRCMs) transfected with siRNAs against Flotillin-1 and/or Flotillin-2. RESULTS First, we confirmed presence in the ID and mutual binding of Flotillin-1 and Flotillin-2 in murine and human cardiac tissue. Flotillin KO mice did not show cardiac fibrosis, nor hypertrophy or changes in expression of the desmosomal ID proteins. However, protein expression of the cardiac sodium channel NaV1.5 was significantly decreased in Flotillin-1 and Flotillin-1/2 KO mice compared to WT mice. In addition, sodium current density showed a significant decrease upon Flotillin-1/2 KD in NRCMs as compared to scrambled siRNA-transfected NRCMs. MEA recordings of Flotillin-2 KD NRCM cultures showed a significantly decreased spike amplitude and a tendency of a reduced spike slope when compared to control and scrambled siRNA-transfected cultures. CONCLUSIONS In this study, we demonstrate the presence of Flotillin-1, in addition to Flotillin-2 in the cardiac ID. Our findings indicate a modulatory role of Flotillins on NaV1.5 expression at the ID, with potential consequences for cardiac excitation.
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Affiliation(s)
- Elise L Kessler
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, the Netherlands.
| | - Leonie van Stuijvenberg
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Joanne J A van Bavel
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Joëlle van Bennekom
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Anne Zwartsen
- Dutch Poisons Information Center (DPIC), University Medical Center Utrecht, Utrecht University, Utrecht, the Netherlands; Neurotoxicology Research Group, Division Toxicology, Institute for Risk Assessment Sciences (IRAS), Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands
| | - Mathilde R Rivaud
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Aryan Vink
- Department of Pathology, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Igor R Efimov
- Department of Biomedical Engineering, George Washington University, Washington, DC, USA
| | - Alex V Postma
- Department of Clinical Genetics, Amsterdam University Medical Center, Location AMC, the Netherlands
| | - J Peter van Tintelen
- Department of Clinical Genetics, Amsterdam University Medical Center, Location AMC, the Netherlands; Department of Genetics, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Carol A Remme
- Department of Clinical and Experimental Cardiology, Academic Medical Center, University of Amsterdam, the Netherlands
| | - Marc A Vos
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Antje Banning
- Institute of Biochemistry, Medical Faculty, University of Giessen, Germany
| | - Teun P de Boer
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Ritva Tikkanen
- Institute of Biochemistry, Medical Faculty, University of Giessen, Germany
| | - Toon A B van Veen
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Utrecht, the Netherlands
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7
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Random Splicing of Several Exons Caused by a Single Base Change in the Target Exon of CRISPR/Cas9 Mediated Gene Knockout. Cells 2016; 5:cells5040045. [PMID: 27983621 PMCID: PMC5187529 DOI: 10.3390/cells5040045] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Revised: 12/03/2016] [Accepted: 12/09/2016] [Indexed: 12/18/2022] Open
Abstract
The clustered regularly interspaced short palindromic repeats (CRISPR)-associated sequence 9 (CRISPR/Cas9) system is widely used for genome editing purposes as it facilitates an efficient knockout of a specific gene in, e.g. cultured cells. Targeted double-strand breaks are introduced to the target sequence of the guide RNAs, which activates the cellular DNA repair mechanism for non-homologous-end-joining, resulting in unprecise repair and introduction of small deletions or insertions. Due to this, sequence alterations in the coding region of the target gene frequently cause frame-shift mutations, facilitating degradation of the mRNA. We here show that such CRISPR/Cas9-mediated alterations in the target exon may also result in altered splicing of the respective pre-mRNA, most likely due to mutations of splice-regulatory sequences. Using the human FLOT-1 gene as an example, we demonstrate that such altered splicing products also give rise to aberrant protein products. These may potentially function as dominant-negative proteins and thus interfere with the interpretation of the data generated with these cell lines. Since most researchers only control the consequences of CRISPR knockout at genomic and protein level, our data should encourage to also check the alterations at the mRNA level.
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Cholinergic transactivation of the EGFR in HaCaT keratinocytes stimulates a flotillin-1 dependent MAPK-mediated transcriptional response. Int J Mol Sci 2015; 16:6447-63. [PMID: 25803106 PMCID: PMC4394542 DOI: 10.3390/ijms16036447] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Revised: 03/06/2015] [Accepted: 03/17/2015] [Indexed: 12/13/2022] Open
Abstract
Acetylcholine and its receptors regulate numerous cellular processes in keratinocytes and other non-neuronal cells. Muscarinic acetylcholine receptors are capable of transactivating the epidermal growth factor receptor (EGFR) and, downstream thereof, the mitogen-activated protein kinase (MAPK) cascade, which in turn regulates transcription of genes involved in cell proliferation and migration. We here show that cholinergic stimulation of human HaCaT keratinocytes results in increased transcription of matrix metalloproteinase MMP-3 as well as several ligands of the epidermal growth factor family. Since both metalloproteinases and the said ligands are involved in the transactivation of the EGFR, this transcriptional upregulation may provide a positive feed-forward loop for EGFR/MAPK activation. We here also show that the cholinergic EGFR and MAPK activation and the upregulation of MMP-3 and EGF-like ligands are dependent on the expression of flotillin-1 which we have previously shown to be a regulator of MAPK signaling.
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Liu Y, Lin L, Huang Z, Ji B, Mei S, Lin Y, Shen Z. High expression of flotillin-2 is associated with poor clinical survival in cervical carcinoma. INTERNATIONAL JOURNAL OF CLINICAL AND EXPERIMENTAL PATHOLOGY 2015; 8:622-628. [PMID: 25755754 PMCID: PMC4348905] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Accepted: 12/24/2014] [Indexed: 06/04/2023]
Abstract
AIMS To investigate the expression and clinical significance of flotillin-2 (FLOT2) in cervical cancer (CC). METHODS We examined FLOT2 mRNA levels in 10 pairs of cervical cancer and adjacent normal tissues. Immunohistochemistry was performed to analyze FLOT2 protein expression in 115 archived cervical cancer samples. The association between FLOT2 levels, clinicopathologic factors and prognosis was analyzed statistically as well. RESULTS The cancer tissues of CC patients had clearly increased expression of FLOT2 at mRNA level as compared to adjacent nontumorous tissues. Survival analysis of CC patients indicated that FLOT2 expression was significantly associated with poor overall and local recurrence-free survival (P = 0.025 and P = 0.028, respectively). Moreover, FLOT2 expression was significantly correlated with clinical stage, tumor differentiation, and lymph nodes metastasis. Multivariate analysis revealed that FLOT2 expression was an independent prognostic factor for overall survival in CC patients. CONCLUSION FLOT2 may serve as an oncogene in the development of CC, and may serve as a clinicopathologic biomarker for prognosis in CC patients.
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Affiliation(s)
- Yaqiong Liu
- Department of Obstetrics and Gynecology, Guangzhou Women and Children Medical Center, Guangzhou Medical University Affiliated Women and Children Medical CenterGuangzhou 510120, China
| | - Li Lin
- Department of Obstetrics and Gynecology, Shenzhen Second People’s Hospital, The First Affiliated Hospital of Shenzhen UniversityShenzhen 518000, China
| | - Zijian Huang
- Department of Obstetrics and Gynecology, Guangzhou Women and Children Medical Center, Guangzhou Medical University Affiliated Women and Children Medical CenterGuangzhou 510120, China
| | - Bing Ji
- Department of Obstetrics and Gynecology, Guangzhou Women and Children Medical Center, Guangzhou Medical University Affiliated Women and Children Medical CenterGuangzhou 510120, China
| | - Shanshan Mei
- Department of Obstetrics and Gynecology, Guangzhou Women and Children Medical Center, Guangzhou Medical University Affiliated Women and Children Medical CenterGuangzhou 510120, China
| | - Ying Lin
- Department of Obstetrics and Gynecology, People’s Hospital of Hunan ProvinceChangsha 410005, China
| | - Zhuanxing Shen
- Department of Obstetrics and Gynecology, Guangzhou Women and Children Medical Center, Guangzhou Medical University Affiliated Women and Children Medical CenterGuangzhou 510120, China
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Bodin S, Planchon D, Rios Morris E, Comunale F, Gauthier-Rouvière C. Flotillins in intercellular adhesion - from cellular physiology to human diseases. J Cell Sci 2014; 127:5139-47. [PMID: 25413346 DOI: 10.1242/jcs.159764] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Flotillin 1 and 2 are ubiquitous and highly conserved proteins. They were initially discovered in 1997 as being associated with specific caveolin-independent cholesterol- and glycosphingolipid-enriched membrane microdomains and as being expressed during axon regeneration. Flotillins have a role in a large number of physiopathological processes, mainly through their function in membrane receptor clustering and in the regulation of clathrin-independent endocytosis. In this Commentary, we summarize the research performed so far on the role of flotillins in cell-cell adhesion. Recent studies have demonstrated that flotillins directly regulate the formation of cadherin complexes. Indeed, flotillin microdomains are required for the dynamic association and stabilization of cadherins at cell-cell junctions and also for cadherin signaling. Moreover, because flotillins regulate endocytosis and also the actin cytoskeleton, they could have an indirect role in the assembly and stabilization of cadherin complexes. Because it has also recently been shown that flotillins are overexpressed during neurodegenerative diseases and in human cancers, where their upregulation is associated with metastasis formation and poor prognosis, understanding to what extent flotillin upregulation participates in the development of such pathologies is thus of particular interest, as well as how, at the molecular level, it might affect cell adhesion processes.
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Affiliation(s)
- Stéphane Bodin
- Equipe Labellisée Ligue Contre le Cancer, Universités Montpellier 2 et 1, CRBM, CNRS, UMR 5237, 1919 Route de Mende, 34293 Montpellier, France
| | - Damien Planchon
- Equipe Labellisée Ligue Contre le Cancer, Universités Montpellier 2 et 1, CRBM, CNRS, UMR 5237, 1919 Route de Mende, 34293 Montpellier, France
| | - Eduardo Rios Morris
- Equipe Labellisée Ligue Contre le Cancer, Universités Montpellier 2 et 1, CRBM, CNRS, UMR 5237, 1919 Route de Mende, 34293 Montpellier, France
| | - Franck Comunale
- Equipe Labellisée Ligue Contre le Cancer, Universités Montpellier 2 et 1, CRBM, CNRS, UMR 5237, 1919 Route de Mende, 34293 Montpellier, France
| | - Cécile Gauthier-Rouvière
- Equipe Labellisée Ligue Contre le Cancer, Universités Montpellier 2 et 1, CRBM, CNRS, UMR 5237, 1919 Route de Mende, 34293 Montpellier, France
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Flotillin-1 facilitates toll-like receptor 3 signaling in human endothelial cells. Basic Res Cardiol 2014; 109:439. [PMID: 25204797 PMCID: PMC4330457 DOI: 10.1007/s00395-014-0439-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Revised: 08/22/2014] [Accepted: 09/03/2014] [Indexed: 12/23/2022]
Abstract
Endothelial cells are important elements in the vascular response to danger-associated molecules signaling through toll-like receptors (TLRs). Flotillin-1 and -2 are markers of membrane rafts but their true endothelial function is unknown. We hypothesized that flotillins are required for TLR signaling in human umbilical vein endothelial cells (HUVECs). Knockdown of flotillin-1 by shRNA decreased the TLR3-mediated poly-I:C-induced but not the TLR4-mediated LPS-induced inflammatory activation of HUVEC. As TLR3 but not TLR4 signals through the endosomal compartment, flotillin-1 might be involved in the transport of poly-I:C to its receptor. Consistently, uptake of poly-I:C was attenuated by flotillin-1 knockdown and probably involved the scavenger receptor SCARA4 as revealed by knockdown of this receptor. To determine the underlying mechanism, SILAC proteomics was performed. Down-regulation of flotillin-1 led to a reduction of the structural caveolae proteins caveolin-1, cavin-1 and -2, suggesting a role of flotillin-1 in caveolae formation. Flotillin-1 and caveolin-1 colocalized within the cell, and knockdown of flotillin-1 decreased caveolin-1 expression in an endoplasmic reticulum stress-dependent manner. Importantly, downregulation of caveolin-1 also attenuated TLR3-induced signaling. To demonstrate the importance of this finding, cell adhesion was studied. Flotillin-1 shRNA attenuated the poly-I:C-mediated induction of the adhesion molecules VCAM-1 and ICAM-1. As a consequence, the poly-I:C-induced adhesion of peripheral blood mononuclear cells onto HUVECs was significantly attenuated by flotillin-1 shRNA. Collectively, these data suggest that interaction between flotillin-1 and caveolin-1 may facilitate the transport of TLR3-ligands to its intracellular receptor and enables inflammatory TLR3 signaling.
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Flotillins in receptor tyrosine kinase signaling and cancer. Cells 2014; 3:129-49. [PMID: 24709906 PMCID: PMC3980747 DOI: 10.3390/cells3010129] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Revised: 02/11/2014] [Accepted: 02/12/2014] [Indexed: 01/23/2023] Open
Abstract
Flotillins are highly conserved proteins that localize into specific cholesterol rich microdomains in cellular membranes. They have been shown to be associated with, for example, various signaling pathways, cell adhesion, membrane trafficking and axonal growth. Recent findings have revealed that flotillins are frequently overexpressed in various types of human cancers. We here review the suggested functions of flotillins during receptor tyrosine kinase signaling and in cancer. Although flotillins have been implicated as putative cancer therapy targets, we here show that great caution is required since flotillin ablation may result in effects that increase instead of decrease the activity of specific signaling pathways. On the other hand, as flotillin overexpression appears to be related with metastasis formation in certain cancers, we also discuss the implications of these findings for future therapy aspects.
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Banning A, Regenbrecht CR, Tikkanen R. Increased activity of mitogen activated protein kinase pathway in flotillin-2 knockout mouse model. Cell Signal 2014; 26:198-207. [DOI: 10.1016/j.cellsig.2013.11.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Accepted: 11/04/2013] [Indexed: 10/26/2022]
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Solis GP, Hülsbusch N, Radon Y, Katanaev VL, Plattner H, Stuermer CAO. Reggies/flotillins interact with Rab11a and SNX4 at the tubulovesicular recycling compartment and function in transferrin receptor and E-cadherin trafficking. Mol Biol Cell 2013; 24:2689-702. [PMID: 23825023 PMCID: PMC3756921 DOI: 10.1091/mbc.e12-12-0854] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
In this study reggie-1/flotillin-2 is identified as a component of the tubulovesicular sorting and recycling compartment, where it interacts with and controls the activity of Rab11a and SNX4. Evidence is given that reggie-1 expression is necessary for the proper recycling of transferrin receptor and E-cadherin in HeLa and A431 cells, respectively. The lipid raft proteins reggie-1 and -2 (flotillins) are implicated in membrane protein trafficking but exactly how has been elusive. We find that reggie-1 and -2 associate with the Rab11a, SNX4, and EHD1–decorated tubulovesicular recycling compartment in HeLa cells and that reggie-1 directly interacts with Rab11a and SNX4. Short hairpin RNA–mediated down-regulation of reggie-1 (and -2) in HeLa cells reduces association of Rab11a with tubular structures and impairs recycling of the transferrin–transferrin receptor (TfR) complex to the plasma membrane. Overexpression of constitutively active Rab11a rescues TfR recycling in reggie-deficient HeLa cells. Similarly, in a Ca2+ switch assay in reggie-depleted A431 cells, internalized E-cadherin is not efficiently recycled to the plasma membrane upon Ca2+ repletion. E-cadherin recycling is rescued, however, by overexpression of constitutively active Rab11a or SNX4 in reggie-deficient A431 cells. This suggests that the function of reggie-1 in sorting and recycling occurs in association with Rab11a and SNX4. Of interest, impaired recycling in reggie-deficient cells leads to de novo E-cadherin biosynthesis and cell contact reformation, showing that cells have ways to compensate the loss of reggies. Together our results identify reggie-1 as a regulator of the Rab11a/SNX4-controlled sorting and recycling pathway, which is, like reggies, evolutionarily conserved.
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Affiliation(s)
- Gonzalo P Solis
- Department of Biology, University of Konstanz, 78467 Konstanz, Germany.
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Monje FJ, Divisch I, Demit M, Lubec G, Pollak DD. Flotillin-1 is an evolutionary-conserved memory-related protein up-regulated in implicit and explicit learning paradigms. Ann Med 2013; 45:301-7. [PMID: 23631399 PMCID: PMC3681089 DOI: 10.3109/07853890.2013.770637] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
INTRODUCTION Studies of synaptic plasticity using the marine mollusk Aplysia californica as model system have been successfully used to identify proteins involved in learning and memory. The importance of molecular elements regulated by the learning- related neurotransmitter serotonin in Aplysia can then be explored in rodent models and finally tested for their relevance for human physiology and pathology. MATERIALS AND METHODS Herein, 2-DE gel-based electrophoresis has been used to investigate protein level changes after treatment with serotonin in Aplysia abdominal ganglia. RESULTS Twenty-one proteins have been found to be regulated by serotonin, and protein level changes of actin depolymerizing factor (ADF), deleted in azoospermia associated protein (DAZAP-1), and Flotillin-1 have been verified by Western blotting. DISCUSSION Flotillin-1, a member of the flotillin/reggie family of scaffolding proteins, has been previously found to be involved in neuritic branching and synapse formation in hippocampal neurons in vitro. However, its importance for hippocampal- dependent learning and memory in the mouse has not been examined. Here, elevated levels of Flotillin-1 in hippocampal tissue of mice trained in the Morris water maze confirmed the relevance of Flotillin-1 for memory-related processes in a mammalian system. Thus, a translational approach-from invertebrates to rodents-led to the identification of Flotillin-1 as evolutionary-conserved memory-related protein.
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Affiliation(s)
- Francisco J Monje
- Department of Neurophysiology and Neuropharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Austria
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Meister M, Tomasovic A, Banning A, Tikkanen R. Mitogen-Activated Protein (MAP) Kinase Scaffolding Proteins: A Recount. Int J Mol Sci 2013; 14:4854-84. [PMID: 23455463 PMCID: PMC3634400 DOI: 10.3390/ijms14034854] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Revised: 02/17/2013] [Accepted: 02/21/2013] [Indexed: 12/20/2022] Open
Abstract
The mitogen-activated protein kinase (MAPK) pathway is the canonical signaling pathway for many receptor tyrosine kinases, such as the Epidermal Growth Factor Receptor. Downstream of the receptors, this pathway involves the activation of a kinase cascade that culminates in a transcriptional response and affects processes, such as cell migration and adhesion. In addition, the strength and duration of the upstream signal also influence the mode of the cellular response that is switched on. Thus, the same components can in principle coordinate opposite responses, such as proliferation and differentiation. In recent years, it has become evident that MAPK signaling is regulated and fine-tuned by proteins that can bind to several MAPK signaling proteins simultaneously and, thereby, affect their function. These so-called MAPK scaffolding proteins are, thus, important coordinators of the signaling response in cells. In this review, we summarize the recent advances in the research on MAPK/extracellular signal-regulated kinase (ERK) pathway scaffolders. We will not only review the well-known members of the family, such as kinase suppressor of Ras (KSR), but also put a special focus on the function of the recently identified or less studied scaffolders, such as fibroblast growth factor receptor substrate 2, flotillin-1 and mitogen-activated protein kinase organizer 1.
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Affiliation(s)
- Melanie Meister
- Institute of Biochemistry, Medical Faculty, University of Giessen, Friedrichstrasse 24, 35392 Giessen, Germany; E-Mails: (M.M.); (A.B.)
| | - Ana Tomasovic
- Department of Molecular Hematology, University of Frankfurt, Medical School, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany; E-Mail:
| | - Antje Banning
- Institute of Biochemistry, Medical Faculty, University of Giessen, Friedrichstrasse 24, 35392 Giessen, Germany; E-Mails: (M.M.); (A.B.)
| | - Ritva Tikkanen
- Institute of Biochemistry, Medical Faculty, University of Giessen, Friedrichstrasse 24, 35392 Giessen, Germany; E-Mails: (M.M.); (A.B.)
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +49-641-9947-420; Fax: +49-641-9947-429
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