Overexpression Of Caveolin-1 Research Articles

Caveolin 1 restricts Group A Streptococcus invasion of nonphagocytic host cells.

Caveolae are composed of 2 major proteins, caveolin 1 (CAV1) and cavin 1 or polymerase transcript release factor I (CAVIN1). Here, we demonstrate that CAV1 levels modulate invasion of Group A Streptococcus (GAS) into nonphagocytic mammalian cells. GAS showed enhanced internalisation into CAV1-knockout mouse embryonic fibroblasts and CAV1 knockdown human epithelial HEp-2 cells, whereas overexpression of CAV1 in HEp-2 cells reduced GAS invasion. This effect was not dependent on the expression of the GAS fibronectin binding protein SfbI, which had previously been implicated in caveolae-mediated uptake. Nor was this effect dependent on CAVIN1, as knockout of CAVIN1 in mouse embryonic fibroblasts resulted in reduced GAS internalisation. Although CAV1 restricted GAS invasion into host cells, we observed only minimal association of invading GAS (strain M1T15448 ) with CAV1 by immunofluorescence and very low association of invading M1T15448 with caveolae by transmission electron microscopy. These observations suggest that physical interaction with caveolae is not needed for CAV1 restriction of invading GAS. An indirect mechanism of action is also consistent with the finding that changing membrane fluidity reverses the increased invasion observed in CAV1-null cells. Together, these results suggest that CAV1 protects host cells against GAS invasion by a caveola-independent mechanism.

Neuron-specific caveolin-1 overexpression improves motor function and preserves memory in mice subjected to brain trauma.

Studies in vitro and in vivo demonstrate that membrane/lipid rafts and caveolin (Cav) organize progrowth receptors, and, when overexpressed specifically in neurons, Cav-1 augments neuronal signaling and growth and improves cognitive function in adult and aged mice; however, whether neuronal Cav-1 overexpression can preserve motor and cognitive function in the brain trauma setting is unknown. Here, we generated a neuron-targeted Cav-1-overexpressing transgenic (Tg) mouse [synapsin-driven Cav-1 (SynCav1 Tg)] and subjected it to a controlled cortical impact model of brain trauma and measured biochemical, anatomic, and behavioral changes. SynCav1 Tg mice exhibited increased hippocampal expression of Cav-1 and membrane/lipid raft localization of postsynaptic density protein 95, NMDA receptor, and tropomyosin receptor kinase B. When subjected to a controlled cortical impact, SynCav1 Tg mice demonstrated preserved hippocampus-dependent fear learning and memory, improved motor function recovery, and decreased brain lesion volume compared with wild-type controls. Neuron-targeted overexpression of Cav-1 in the adult brain prevents hippocampus-dependent learning and memory deficits, restores motor function after brain trauma, and decreases brain lesion size induced by trauma. Our findings demonstrate that neuron-targeted Cav-1 can be used as a novel therapeutic strategy to restore brain function and prevent trauma-associated maladaptive plasticity.-Egawa, J., Schilling, J. M., Cui, W., Posadas, E., Sawada, A., Alas, B., Zemljic-Harpf, A. E., Fannon-Pavlich, M. J., Mandyam, C. D., Roth, D. M., Patel, H. H., Patel, P. M., Head, B. P. Neuron-specific caveolin-1 overexpression improves motor function and preserves memory in mice subjected to brain trauma.

Enhanced expression of caveolin-1 possesses diagnostic and prognostic value and promotes cell migration, invasion and sunitinib resistance in the clear cell renal cell carcinoma

Caveolin-1 (CAV1) has been identified to be up-regulated in many cancers, including clear cell renal cell carcinoma (ccRCC). However, its potential function is still unclear in ccRCC. In this study, we demonstrated that CAV1 was frequently overexpressed in renal cell carcinoma tissues and cells, and was significantly associated with various clinicopathological parameters. In addition, high CAV1 expression was associated with poor disease-free survival (DFS) rate and could serve as a useful diagnostic indicator in ccRCC patients with different clinicopathological stages. Functional experiments demonstrated that CAV1 knockdown inhibited cell migration and invasion, whereas overexpression of CAV1 promoted cell migration and invasion in ccRCC. Moreover, CAV1 expression was up-regulated in sunitinib-resistant renal cancer cell lines, and its overexpression promoted sunitinib resistance. In general, our results confirm that CAV1 plays an important role in the metastasis of kidney cancer and induces sunitinib resistance, so CAV1 function suppression may become a promising clinical treatment strategy during renal cell carcinoma metastasis and sunitinib resistance.

Abstract 2503: Metabolomics identifies a caveolin-1-associated plasma glycosphingolipid and sphingomyelin signature that differentiates aggressive from indolent prostate cancer in an active surveillance cohort

Abstract Purpose: To identify a plasma signature that can distinguish aggressive from indolent prostate cancer in patients on active surveillance based on metabolomics profiling. Introduction: The slow growth rate and low likelihood of disease progression in low-risk prostate cancer patients have led to the widely implemented active surveillance (AS) strategy. Given tumor heterogeneity, a clinical challenge is how to expand the pool of patients eligible for AS safely. Consequently, additional markers able to identify patients at increased risk of disease progression are needed. We previously identified plasma caveolin-1 (CAV1) as predictive of aggressive prostate cancer in an AS cohort. Complementary in vitro and in vivo studies demonstrated that CAV1 mediates major reprogramming of lipid metabolism, collectively suggesting that dysregulated lipid biogenesis may be associated with aggressive prostate cancer. Experimental Procedures: An integrated approach was utilized which included multi-assay untargeted metabolomics to characterize alterations in the metabolome and lipidome of conditioned media from prostate cancer cell lines following overexpression of CAV1 (LNCaP) or CAV1 siRNA knockdown (PC3M). In parallel, sera from PBCre+PTENloxp/loxp;PBCav-1+ and PBCre+PTENloxp/loxp;PBCav-1- mice were collected for metabolomics analysis to further delineate signatures related to CAV1-associated aggressive prostate cancer. We further conducted untargeted metabolomic analysis on plasma samples (n=16 per group) prospectively collected from patients with early stage prostate cancer undergoing AS who exhibited early progression (defined as upgrading of Gleason score (GS) and/or increased tumor volume on surveillance biopsy within 18 months after start of AS) or indolent disease (did not progress for a minimum of 5 years after start of AS). Patients were matched with respect to age, clinical stage, prostate-specific antigen, and GS on baseline biopsy at start of AS. We evaluated plasma samples collected at baseline (start of AS) and after 12 months. Results: Analysis of conditioned media identified a metabolomics signature with major alterations in lipid composition highlighted by CAV1-mediated elevations in lipid-raft associated sphingomyelins and glycosphingolipids. This signature was observed in patients who had early progression but not in patients with indolent disease. Importantly, this signature was observed at baseline and at least 18 months prior to disease progression on surveillance biopsy. Conclusions: We have identified a plasma-derived lipid signature that differentiates aggressive versus indolent prostate cancer in an active surveillance cohort. Our findings highlight the potential utility of altered lipid profiles as additional risk markers for aggressive prostate cancer. Citation Format: Johannes Fahrmann, Jody Vykoukal, Spyridon Basourakos, Jianxiang Wang, Jennifer Dennison, Eunice Murage, Jeri Kim, Timothy C. Thompson, Samir Hanash. Metabolomics identifies a caveolin-1-associated plasma glycosphingolipid and sphingomyelin signature that differentiates aggressive from indolent prostate cancer in an active surveillance cohort [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2503. doi:10.1158/1538-7445.AM2017-2503

Caveolin-1 Expression in Upper Tract Urothelial Carcinoma

BackgroundImprovement in postoperative risk stratification of upper tract urothelial carcinoma (UTUC) is required to better predict outcomes and counsel patients on adjuvant treatment. ObjectiveTo validate the association between caveolin-1 and oncological outcomes in patients treated with radical nephroureterectomy (RNU) for UTUC. Design, setting, and participantsCaveolin-1 expression was evaluated via immunochemistry on a tissue microarray from 621 patients. Caveolin-1 was considered overexpressed when at least 50% of the tumor cells stained positive. The median follow-up in this retrospective study was 35 mo (interquartile range 16–65). InterventionRadical nephroureterectomy. Outcome measurements and statistical analysisUnivariate and multivariable Cox proportional hazards regression models were used to assess the association between caveolin-1 expression and recurrence and cancer-specific mortality (CSM). Results and limitationsCaveolin-1 was overexpressed in 150 patients (24%). Overexpression was associated with higher pathological stage (p<0.001) and grade (p<0.001). In univariate analyses, overexpression of caveolin-1 was significantly associated with lower recurrence (hazard ratio [HR] 1.7, 95% confidence interval [CI] 1.2–2.6; p=0.004) and CSM (HR 1.8, 95% CI 1.2–2.7; p=0.005); however, multivariable analyses did not prove its independent association with outcomes. The study is limited by its retrospective nature. ConclusionsDespite overexpression in a quarter of UTUC patients, caveolin-1 was not independently associated with oncological outcomes. Its use could be evaluated to improve clinical staging of biopsy specimens and to help in clinical decision-making regarding a kidney-sparing approach or neoadjuvant systemic treatment. Patient summaryDevelopment of a panel of prognostic and predictive markers is mandatory for patient consultations in the era of personalized medicine. We evaluated the role of caveolin-1 in a large series of patients treated with radical nephroureterectomy for upper tract urothelial carcinoma (UTUC) and found that it was not independently associated with oncological outcomes. Nevertheless, it was associated with adverse pathological features. Considering caveolin-1 in UTUC biopsy specimens could help in improving clinical staging and decision-making regarding a kidney-sparing approach or neoadjuvant systemic treatment.

Abstract 4308: Cordycepin induces apoptosis by caveolin-1-mediated JNK regulation of Foxo3a in human lung adenocarcinoma cells

Abstract Forkhead transcription factor (Foxo3a) is a critical effector of JNK-mediated tumor suppression. However, it is not clear whether the caveolin-1 (CAV1)-mediated JNK/Foxo3a pathway is involved in cancer cell apoptosis. We found that cordycepin upregulates CAV1 expression, which was accompanied by JNK phosphorylation (p-JNK), and, subsequently Foxo3a translocation into the nucleus, resulting in the upregulation of Bax protein expression. Furthermore, we found that CAV1 overexpression upregulated p-JNK whereas CAV1 siRNA downregulated p-JNK. Additionally, SP600125, a specific JNK inhibitor, significantly increased Foxo3a phosphorylation, which attenuated Foxo3a translocation into the nucleus, indicating that CAV1 mediates JNK regulation of Foxo3a. Foxo3a siRNA downregulated Bax protein and attenuated A549 apoptosis, indicating that the CAV1-mediated JNK/Foxo3a pathway induces the apoptosis of A549 lung cancer cells. Cordycepin significantly decreased tumor volume in nude mice. Taken together, these results indicate that cordycepin promotes CAV1 upregulation to enhance JNK/Foxo3a signaling pathway activation inducing apoptosis in lung cancer cells and support its potential as a therapeutic agent for lung cancer. Citation Format: Eunbi Jo, Hyun Jin Jang, Ik-Soon Jang. Cordycepin induces apoptosis by caveolin-1-mediated JNK regulation of Foxo3a in human lung adenocarcinoma cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4308. doi:10.1158/1538-7445.AM2017-4308

Abstract 1924: Caveolin-1 inhibits mammary carcinogenesis via suppressing c-myc-induced metabolism reprogramming in breast cancer stem cells

Abstract Purpose: Caveolin-1(CAV1), a membrane constituent protein, exhibits tumor suppressor activities in multiple malignancies, whereas the underlying mechanisms remain unclear. The current study aimed to determine the significance of CAV-1 in regulating cancer metabolism and its relation to breast cancer stem cells (CSCs). Experimental Design: The anti-carcinogenic function of CAV1 was evaluated by in vitro cell model, CAV1 knockout mice and MMTV-PyMT spontaneous breast cancer xenografts. Glycolysis activity and mitochondrial metabolism were assessed by immunoblotting, oxygen consumption and mitotacker staining analysis. Mammosphere formation, tumorigenic ability, reattachment differentiation and signaling pathway analysis were applied to study the regulation effects of CAV1 on breast CSCs. The clinical significance of CAV1 was also analyzed by human tissue microarray. Results: In both mammary transformed cells and spontaneous breast cancer xenografts, CAV1 is found significantly downregulated and positively correlated to increased glycolysis activity and impaired mitochondrial metabolism. Cav1 knockout results in increased ductal hyperplasia, associating with increased stem cell population and glycolysis metabolism. Breast CSCs exhibits glycolytic phenotype and decreased CAV1 expression compared to normal mammary stem cells, and CAV1 overexpression significantly limits CSCs’ self-renewal via inhibiting c-myc induced glycolysis. Clinical investigation suggests that high CAV1 expression is revealed with better overall survival and decreased CSCs population. Conclusions: CAV1 loss facilitates mammary carcinogenesis via enhancing glycolytic activity in breast CSCs, and CAV1 based therapy might become a novel strategy for breast cancer prevention. Note: This abstract was not presented at the meeting. Citation Format: Zhiyu Wang, Neng Wang, Shengqi Wang, Yifeng Zheng. Caveolin-1 inhibits mammary carcinogenesis via suppressing c-myc-induced metabolism reprogramming in breast cancer stem cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1924. doi:10.1158/1538-7445.AM2017-1924

Caveolin1 protects against diet induced hepatic lipid accumulation in mice.

Background and aimCaveolin1 (CAV1) is involved in lipid homeostasis and endocytosis, but little is known about the significance of CAV1 in the pathogenesis and development of nonalcoholic fatty liver disease (NAFLD). This study aimed to determine the role of CAV1 in NAFLD.MethodsExpression of CAV1 in the in vitro and in vivo models of NAFLD was analyzed. The effects of CAV1 knockdown or overexpression on free fatty acid (FFA)-induced lipid accumulation in L02 cells and AML12 cells were determined. CAV1 knockout (CAV1-KO) mice and their wild-type (WT) littermates were subjected to a high fat diet (HFD) for 4 weeks, and the functional consequences of losing the CAV1 gene and its subsequent molecular mechanisms were also examined.ResultsNoticeably, CAV1 expression was markedly reduced in NAFLD. CAV1 knockdown led to the aggravation of steatosis that was induced by FFA in both L02 cells and AML12 cells, while CAV1 overexpression markedly attenuated lipid accumulation in the cells. Consistent with CAV1 repression in the livers of HFD-induced mice, the CAV1-KO mice exhibited more severe hepatic steatosis upon HFD intake. In addition, increased cholesterol levels and elevated transaminases were detected in the plasma of CAV1-KO mice. The protein expression of SREBP1, a key gene involved in lipogenesis, was augmented following CAV1 suppression in FFA-treated hepatocytes and in the livers of HFD-fed CAV1-KO mice.ConclusionsCAV1 serves as an important protective factor in the development of NAFLD by modulating lipid metabolism gene expression.

Caveolin-1-Autophagy Pathway Mediated Cardiomyocyte Hypertrophy Induced by Apelin-13.

Apelin, an endogenous ligand for apelin receptor (APJ), is reported to be involved in cardiomyocyte hypertrophy. In this study, we explored the mechanism of cardiomyocyte hypertrophy induced by apelin-13/APJ system. Left ventricular hypertrophy (LVH) rat model was established by constricting the abdominal aorta. Western blots were used for protein expression in LVH rats and cultured H9c2 cardiomyocytes. Transmission electron microscopy (TEM) was used to monitor morphological features of cells. In addition, the diameter and volume of H9c2 cells were detected by Scepter™ Handheld Automated Cell Counter. We found that the APJ was increased, but caveolin-1 was decreased in heart of LVH rats. In addition, caveolin-1 was suppressed by apelin-13, and this effect was reversed by APJ antagonist F13A in cultured H9c2 cardiomyocytes. Apelin-13 not only stimulated the formation of autophagolysosomes, autophagosome, and lysosomes but also increased the expression of autophagic markers Beclin-1 and LC3II/I. Besides, the increase of Beclin-1 and LC3 II/I was reversed by F13A or caveolin-1 overexpression and further enhanced by caveolin inhibitor. Furthermore, the cardiomyocyte hypertrophy index brain natriuretic peptide (BNP) induced by apelin-13 was blunt by F13A or autophagy inhibitor 3-methyladenine and further promoted by caveolin inhibitor. And caveolin-1 overexpression reduced the diameter and volume of H9c2 cells induced by apelin-13. Our study indicates that caveolin-1-autophagy pathway mediated cardiomyocyte hypertrophy induced by apelin-13/APJ system, which might provide a novel therapeutic target for cardiac hypertrophy disease.

Caveolin-1 as prognostic factor of disease recurrence and survival in patients treated with radical cystectomy for bladder cancer

PurposeOverexpression of Caveolin-1 has been associated with cancer growth, migration, and metastases in several malignancies, but only few data are available on its role in bladder cancer (BCa). The aim of this study is to validate Caveolin-1 as a prognosticator of recurrence-free survival (RFS), overall survival (OS) and cancer-specific survival (CSS) in a large cohort of patients treated with radical cystectomy (RC) for BCa. MethodsCaveolin-1 expression was evaluated by immunochemistry on a tissue microarray from 424 patients treated with RC for UCB at a single institution. Caveolin-1 was considered overexpressed when at least 50% of the tumor cells stained positively. Univariable and multivariable Cox proportional hazards regression models were used to assess the association of Caveolin-1 expression with RFS, OS, and CSS. ResultsOverexpression of Caveolin-1 was observed in 116 (27.4%) patients and was associated with lymph node metastasis (P = 0.003). Median follow-up for patients alive at last follow-up was 129 months (interquartile range [IQR]: 82–178). Patients with overexpression of Caveolin-1 had significant worse RFS, OS, and CSS compared to those with normal expression (log-rank test, P = 0.008, P = 0.001, and P = 0.005, respectively). At multivariable analyses that adjusted for the effects of standard clinicopathologic features, Caveolin-1 remained associated with OS (hazard ratio = 1.47, P = 0.002) and CSS (hazard ratio = 1.42, P = 0.03). Conversely, no association with RFS was found (P = 0.1). Addition of Caveolin-1 in a model for prediction of survival did not improve the accuracy of the prognostic model. Actually, C-index did not differ among models with or without Caveolin-1 (0.72 for a model predicting RFS, 0.65 for OS, and 0.71 for CSS). ConclusionsCaveolin-1 is overexpressed in one-third of patients with BCa treated with RC. Overexpression of Caveolin-1 is significantly associated with OS and CSS, but not with RFS, in patients with BCa treated with RC. However, it is not clinically useful as it does not improve upon the predictive accuracy of survival achieved by pathologic variables alone.

Caveolin-1 Mediates Inflammatory Breast Cancer Cell Invasion via the Akt1 Pathway and RhoC GTPase.

With a propensity to invade the dermal lymphatic vessels of the skin overlying the breast and readily metastasize, inflammatory breast cancer (IBC) is arguably the deadliest form of breast cancer. We previously reported that caveolin-1 is overexpressed in IBC and that RhoC GTPase is a metastatic switch responsible for the invasive phenotype. RhoC-driven invasion requires phosphorylation by Akt1. Using a reliable IBC cell line we set out to determine if caveolin-1 expression affects RhoC-mediated IBC invasion. Caveolin-1 was down regulated by introduction of siRNA or a caveolin scaffolding domain. The ability of the cells to invade was tested and the status of Akt1 and RhoC GTPase examined. IBC cell invasion is significantly decreased when caveolin-1 is down regulated. Activation of Akt1 is decreased when caveolin-1 is down regulated, leading to decreased phosphorylation of RhoC GTPase. Thus, we report here that caveolin-1 overexpression mediates IBC cell invasion through activation Akt1, which phosphorylates RhoC GTPase.

Cardioprotective kinase signaling to subsarcolemmal and interfibrillar mitochondria is mediated by caveolar structures

The demonstration that caveolin-3 overexpression reduces myocardial ischemia/reperfusion injury and our own finding that multiprotein signaling complexes increase in mitochondria in association with caveolin-3 levels, led us to investigate the contribution of caveolae-driven extracellular signal-regulated kinases 1/2 (ERK1/2) on maintaining the function of cardiac mitochondrial subpopulations from reperfused hearts subjected to postconditioning (PostC). Rat hearts were isolated and subjected to ischemia/reperfusion and to PostC. Enhanced cardiac function, reduced infarct size and preserved ultrastructure of cardiomyocytes were associated with increased formation of caveolar structures, augmented levels of caveolin-3 and mitochondrial ERK1/2 activation in PostC hearts in both subsarcolemmal (SSM) and interfibrillar (IFM) subpopulations. Disruption of caveolae with methyl-β-cyclodextrin abolished cardioprotection in PostC hearts and diminished pho-ERK1/2 gold-labeling in both mitochondrial subpopulations in correlation with suppression of resistance to permeability transition pore opening. Also, differences between the mitochondrial subpopulations in the setting of PostC were evaluated. Caveolae disruption with methyl-β-cyclodextrin abolished the cardioprotective effect of postconditioning by inhibiting the interaction of ERK1/2 with mitochondria and promoted decline in mitochondrial function. SSM, which are particularly sensitive to reperfusion damage, take advantage of their location in cardiomyocyte boundary and benefit from the cardioprotective signaling driven by caveolae, avoiding injury propagation.

Cordycepin induces apoptosis by caveolin-1-mediated JNK regulation of Foxo3a in human lung adenocarcinoma

Forkhead transcription factor (Foxo3a) is a downstream effector of JNK-induced tumor suppression. However, it is not clear whether the caveolin-1 (CAV1)-mediated JNK/Foxo3a pathway is involved in cancer cell apoptosis. We found that cordycepin upregulates CAV1 expression, which was accompanied by JNK phosphorylation (p-JNK) and subsequent Foxo3a translocation into the nucleus, resulting in the upregulation of Bax protein expression. Furthermore, we found that CAV1 overexpression upregulated p-JNK, whereas CAV1 siRNA downregulated p-JNK. Additionally, SP600125, a specific JNK inhibitor, significantly increased Foxo3a phosphorylation, which downregulated Foxo3a translocation into the nucleus, indicating that CAV1 mediates JNK regulation of Foxo3a. Foxo3a siRNA downregulated Bax protein and attenuated A549 apoptosis, indicating that the CAV1-mediated JNK/Foxo3a pathway induces the apoptosis of A549 lung cancer cells. Cordycepin significantly decreased tumor volume in nude mice. Taken together, these results indicate that cordycepin promotes CAV1 upregulation to enhance JNK/Foxo3a signaling pathway activation, inducing apoptosis in lung cancer cells, and support its potential as a therapeutic agent for lung cancer.

Root-Securing and Brain-Fortifying Liquid Upregulates Caveolin-1 in Cell Model with Alzheimer's Disease through Inhibiting Tau Phosphorylation.

In order to explore the effect of root-securing and brain-fortifying Liquid- (RSBFL-) mediated caveolin-1 (CAV-1) on phosphorylation of Tau protein and to uncover underlying mechanisms of RSBFL for the prevention and treatment of Alzheimer's disease (AD), hippocampal neurons isolated from neonatal SD rats and cultured in DMEM-F12 medium were induced by exogenous Aβ1–42 to establish a cell model with AD. Meanwhile, pEGFP-C1-CAV1 and CAV1-shRNA plasmids were transfected into hippocampal neurons for CAV-1 overexpression and silence, respectively. The serum containing RSBFL was prepared for the intervention of AD model cells. The expression of CAV-1, GSK-3β, and p-Tau in normal hippocampal neurons and AD model cells in the presence of serum containing RSBFL was evaluated. The model hippocampal neurons with AD induced by Aβ1–42 revealed an obvious CAV-1 inhibition, enhanced GSK-3β activity, and abnormal Tau phosphorylation. In contrast, the treatment with serum containing RSBFL could upregulate CAV-1 in AD hippocampal neurons (P < 0.05) with improved p-GSK-3βSer9 and reduced p-GSK-3βTyr216 (P < 0.01), as well as suppressed abnormal phosphorylation of Tau protein. Therefore, RSBFL has an excellent protective effect on hippocampal neurons through increasing CAV-1 expression, inhibiting GSK-3β activity, and reducing excessive abnormal phosphorylation of Tau protein.

Caveolin-3 is aberrantly expressed in skeletal muscle cells in myasthenia gravis

Caveolin-3 is a muscle-specific membrane protein that localizes to the sarcolemma and T-tubule system. Caveolin-3 is needed for muscle repair and skeletal muscle development. The objective of this study was to compare caveolin-3 expression in myasthenia gravis (MG) and control muscles. Caveolin-3 was abnormally expressed in the MG muscle membrane, with partial loss of expression and overexpression in 5/15 and 10/15 patients, respectively. Caveolin-3 mRNA and protein levels were higher in MG than in control muscles, suggesting that partial deficiency of caveolin-3 is occasionally detected in MG muscle and that caveolin-3 overexpression may be required after MG muscle damage.

Overexpression of caveolin-1 attenuates brain edema by inhibiting tight junction degradation.

Cerebral edema from the disruption of the blood-brain barrier (BBB) after cerebral ischemia is a major cause of morbidity and mortality as well as a common event in patients with stroke. Caveolins (Cavs) are thought to regulate BBB functions. Here, we report for the first time that Cav-1 overexpression (OE) decreased brain edema from BBB disruption following ischemic insult. Edema volumes and Cav-1 expression levels were measured following photothrombosis and middle cerebral artery occlusion (MCAO). Endothelial cells that were transduced with a Cav-1 lentiviral expression vector were transplanted into rats. BBB permeability was quantified with Evans blue extravasation. Edema volume was determined from measures of the extravasation area, brain water content, and average fluorescence intensity after Cy5.5 injections. Tight junction (TJ) protein expression was measured with immunoblotting. Cav-1 expression levels and vasogenic brain edema correlated strongly after ischemic insult. Cav-1 expression and BBB disruption peaked 3 d after the MCAO. In addition, intravenous administration of endothelial cells expressing Cav-1 effectively increased the Cav-1 levels 3 d after the MCAO ischemic insult. Importantly, Cav-1 OE ameliorated the vasogenic edema by inhibiting the degradation of TJ protein expression in the acute phase of ischemic stroke. These results suggested that Cav-1 OE protected the integrity of the BBB mainly by preventing the degradation of TJ proteins in rats. These findings need to be confirmed in a clinical setting in human subjects.

Caveolin-1-mediated endocytic pathway is involved in classical swine fever virus Shimen infection of porcine alveolar macrophages

Macrophages are at the frontline of defense against pathogenic microorganisms. However, very little is known about the cell invasion mechanism of classical swine fever virus (CSFV) Shimen strain. To elucidate the infective mechanism of this important pathogen, we screened deep-sequencing data derived from macrophages infected with CSFV Shimen and uninfected macrophages, and identified a role of caveolin-1 (CAV1). Digital gene expression profiling showed that CAV1 was differentially expressed in CSFV Shimen-infected macrophages. Quantitative polymerase chain reaction and western blot analyses showed that the transcription and translation of CAV1 were significantly up-regulated in CSFV Shimen-infected macrophages. In addition, immunofluorescent confocal microscopy analysis suggested that CAV1 was temporally colocalized with CSFV E2 throughout the course of the infection. Through the overexpression of recombinant CAV1 or the silencing of CAV1 expression using small interfering RNA in macrophages, we demonstrated that CAV1 expression is beneficial for the replication of CSFV Shimen. However, RNA silencing of CAV1 did not prevent viral replication, which may indicate that CSFV can also enter macrophages by other mechanisms. Our findings suggest that CAV1-mediated endocytosis is advantageous for productive CSFV Shimen infection in macrophages, providing a new insight into the mechanisms of evasion of host immunity for successful viral infection.

Overexpression of caveolin-1 reduces Taxol resistance in human osteosarcoma cells by attenuating PI3K-Akt-JNK dependent autophagy.

Caveolin-1 (CAV-1), which is an oncoprotein and a tumor suppressor, is highly expressed in normal osteoblasts. Although researchers have investigated its role in human osteosarcoma, the mechanism of caveolin-1 action in osteosarcoma remains unknown. In the present study, Saos-2 and U-2 OS cells were cultured with a continuous induction protocol of gradually increasing Taxol concentration for 6 months to establish drug-resistant cell lines. CAV-1 expression levels in osteosarcoma cells were detected via western blotting and quantitative polymerase chain reaction. CAV-1 knockdown was achieved using a short hair-pin RNA lentivirus vector, and cell viability was analyzed by MTT assay. The effect of caveolin-1 on autophagy was investigated, and the downregulation of caveolin-1 and increased autophagy was identified in Taxol-resistant osteosarcoma cells. In addition, the results of the present study demonstrated that downregulation of caveolin-1 promotes autophagy and induces osteosarcoma cell resistance to Taxol. Notably, overexpression of CAV-1 resensitized drug-resistant cells to Taxol via declined autophagy. In conclusion, CAV-1 was demonstrated to be downregulated in Taxol-resistant osteosarcoma cells, and overexpression of CAV-1 in human osteosarcoma cells suppressed Taxol resistance by attenuating PI3K-Akt-JNK-dependent autophagy. The present findings suggest that further investigation into CAV-1's role in Taxol resistance is warranted. In the future, detection of CAV-1 may be used as an indicator to evaluate the treatment and prognosis of patients with osteosarcoma.

Overexpression of caveolin-1 in inflammatory breast cancer cells enables IBC-specific gene delivery and prodrug conversion using histone-targeted polyplexes.

Gene therapy platforms offer a variety of potentially effective solutions for development of targeted agents that can be exploited for cancer treatment. The physicochemical properties of nanocarriers can be tuned to enhance their localization in tumors, and cell specificity can also be increased by appropriate selection of gene targets. A relatively underexploited approach to enhance therapeutic selectivity in cancer tissues is the use of nanocarriers whose nuclear targeting and uptake are triggered by the altered expression of specific endomembrane trafficking proteins in cancer cells. Previously, we showed that histone 3 (H3) peptide-targeted DNA polyplexes traffic to the nucleus efficiently through caveolar endocytosis followed by transfer through the Golgi and endoplasmic reticulum (ER). We hypothesized that these polyplexes would exhibit enhanced activity in inflammatory breast cancer (IBC) cells, which overexpress caveolin-1 as part of their invasive phenotype, and we also posited that this targeting effect could be exploited to facilitate IBC-specific transfection and prodrug conversion in the presence of normal breast epithelial cells. Using cellular transfection experiments, function-blocking assays, and confocal imaging in both IBC SUM149 cell monocultures and IBC SUM149 co-cultures with MCF10A normal breast epithelial cells, we found that our H3-targeted polyplexes selectively transfected IBC SUM149 cells at a 4-fold higher level than normal breast epithelial cells. This selectivity and increased transfection were caused by a 2.2-fold overexpression of caveolin-1 in IBC SUM149 cells, which led to increased polyplex trafficking to the nucleus through the Golgi and ER. We also saw similar enhancements in cell selectivity and transfection when cells were transfected with a suicide gene/prodrug combination, as the increased expression of the suicide gene in IBC SUM149 cells led to a 55% decrease in viability in IBC SUM149 cells as compared to a 25% decrease in MCF10A cells. These findings demonstrate that differences in the expression of the endocytic membrane protein caveolin-1 can be exploited for cell-selective gene delivery, and ultimately, these gene-based targeting approaches may be useful in potential treatments for aggressive cancer types. Biotechnol. Bioeng. 2016;113: 2686-2697. © 2016 Wiley Periodicals, Inc.

Inflammatory cytokines induce caveolin-1/β-catenin signalling in rat nucleus pulposus cell apoptosis through the p38 MAPK pathway.

Apoptosis of nucleus pulposus (NP) cells is a major cause of intervertebral disc degeneration. To elucidate relationships between caveolin-1 and cytokine-induced apoptosis, we investigated the role of caveolin-1 in cytokine-induced apoptosis in rat NP cells and the related signalling pathway. Rat NP cells were treated with interleukin (IL)-1β or tumour necrosis factor alpha (TNF-α), and knockdown of caveolin-1 and β-catenin was achieved using specific siRNAs. Then, apoptotic level of rat NP cells and expression and activation of caveolin-1/β-catenin signalling were assessed by flow cytometric analysis, qRT-PCR, western blotting and luciferase assays. The relationship between the mitogen-activated protein kinase (MAPK) pathway and caveolin-1 promoter activity was also determined by luciferase assays. IL-1β and TNF-α induced apoptosis, upregulated caveolin-1 expression and activated Wnt/β-catenin signalling in rat NP cells, while the induction effect of cytokines was reversed by caveolin-1 siRNA and β-catenin siRNA. Promotion of rat NP cell apoptosis and nuclear translocation of β-catenin induced by caveolin-1 overexpression were abolished by β-catenin siRNA. Furthermore, pretreatment with a p38 MAPK inhibitor or dominant negative-p38, blocked cytokine-dependent induction of caveolin-1/β-catenin expression and activity. The results revealed the role of p38/caveolin-1/β-catenin in inflammatory cytokine-induced apoptosis in rat NP cells. Thus, controlling p38/caveolin-1/β-catenin activity seemed to regulate IL-1β- and TNF-α-induced apoptosis in the NP during intervertebral disc degeneration.