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1.  Caveolin-1 accumulation in the tongue cancer tumor microenvironment is significantly associated with poor prognosis: an in-vivo and in-vitro study 
BMC Cancer  2015;15:25.
Background
Caveolin-1 (CAV1) may be upregulated by hypoxia and acts in a tumor-dependent manner. We investigated CAV1 in tongue squamous cell carcinoma (TSCC) and its association with clinical outcomes, and studied in vitro possible ways for CAV1 accumulation in the tumor microenvironment (TME).
Methods
TSCC cases (N = 64) were immunohistochemically stained for CAV1. Scores were separately assessed in the tumor and TME and plotted for association with recurrence and survival (univariate analysis with log-rank test). In vitro studies were performed on a 3D myoma organotypic model, a mimicker of TME. Prior to monoculturing HSC-3 tongue cancer cells, the model underwent modifications in oxygenation level (1%O2 hypoxia to upregulate CAV1) and/or in the amount of natural soluble factors [deleted by 14-day rinsing (rinsed myoma, RM), to allow only HSC-3-derived factors to act]. Controls included normoxia (21%O2) and naturally occurring soluble factors (intact myoma, IM). HSC-3 cells were also co-cultured with CaDEC12 cells (fibroblasts exposed to human tongue cancer). CAV1 expression and cellular distribution were examined in different cellular components in hypoxic and rinsed myoma assays. Twist served as a marker for the process of epithelial-mesenchymal transition (EMT). Exosomes isolated from HSC-3 media were investigated for containing CAV1.
Results
Expression of CAV1 in TSCC had a higher score in TME than in the tumor cells and a negative impact on recurrence (p = 0.01) and survival (p = 0.003). Monocultures of HSC-3 revealed expression of CAV1 mainly in the TME-like myoma assay, similar to TSCC. CAV1+, alpha-smooth muscle actin (αSMA) + and Twist + CAF-like cells were observed surrounding the invading HSC-3, possibly reflecting EMT. RM findings were similar to IM, inferring action of HSC-3 derived factors, and no differences were seen when hypoxia was induced. HSC-3-CaDEC12 co-cultures revealed CAV1+, αSMA+ and cytokeratin-negative CAF-like cells, raising the possibility of CaDEC12 cells gaining a CAF phenotype. HSC-3-derived exosomes were loaded with CAV1.
Conclusions
Accumulation of CAV1-TME in TSCC had a negative prognostic value. In vitro studies showed the presence of CAV1 in cancer cells undergoing EMT and in fibroblasts undergoing trans-differentiation to CAFs. CAV1 delivery to the TME involved cancer cell-derived exosomes.
doi:10.1186/s12885-015-1030-6
PMCID: PMC4318139  PMID: 25633184
Tongue cancer; Caveolin-1; Survival; Myoma organotypic model; Tumor microenvironment; Cancer-associated fibroblasts; Exosomes; Epithelial-mesenchymal transition
2.  A novel FoxM1-Caveolin signaling pathway promotes pancreatic cancer invasion and metastasis 
Cancer Research  2011;72(3):655-665.
Caveolin-1 (Cav-1), a principal structural component of caveolar membrane domains, contributes to cancer development but its precise functional roles and regulation remain unclear. In this study, we determined the oncogenic function of Cav-1 in preclinical models of pancreatic cancer and in human tissue specimens. Cav-1 expression levels correlated with metastatic potential and epithelial-to-mesenchymal transition (EMT) in both mouse and human pancreatic cancer cells. Elevated levels in cells promoted EMT, migration, invasion and metastasis in animal models, whereas RNAi-mediated knockdown inhibited these processes. We determined that levels of Cav-1 and the Forkhead transcription factor FoxM1 correlated directly in pancreatic cancer cells and tumor tissues. Enforced expression of FoxM1 increased Cav-1 levels, whereas RNAi-mediated knockdown of FoxM1 had the opposite effect. FoxM1 directly bound to the promoter region of Cav-1 gene and positively transactivated its activity. Collectively, our findings defined Cav-1 as an important downstream oncogenic target of FoxM1, suggesting that dysregulated signaling of this novel FoxM1-Cav-1 pathway promotes pancreatic cancer development and progression.
doi:10.1158/0008-5472.CAN-11-3102
PMCID: PMC3271134  PMID: 22194465
Progression; angiogenesis; transcription factor; EMT; biomarkers
3.  Deguelin Suppresses Pancreatic Tumor Growth and Metastasis by Inhibiting Epithelial to Mesenchymal Transition in an Orthotopic Model1 
Oncogene  2012;32(34):3980-3991.
Deguelin is known to suppress the growth of cancer cells; however, its anti-metastatic effects have not been studied so far in any cancer model. In the present study, we aimed to evaluate the anti-metastatic potential of deguelin in vivo and in TGFβ1-stimulated cells. Our results demonstrate that tumor growth, peritoneal-dissemination and liver/lung metastasis of orthotopically implanted PanC-1-luc cells were significantly reduced in deguelin-treated mice along with the induction of apoptosis. Furthermore, deguelin-treated tumors showed increased epithelial signature such as increased expression of E-Cadherin and cytokeratin-18 and decreased expression of Snail. Similar observations were made when PanC-1, COLO-357 and L3.6pl cells were treated in vitro with deguelin. Moreover, E-cadherin was transcriptionally up-regulated and accumulated in the membrane fraction of deguelin-treated cells as indicated by increased interaction of E-Cadherin with β-catenin. TGFβ1-induced down-regulation of E-Cadherin and up-regulation of Snail were abrogated by deguelin treatment. In addition, deguelin inhibited TGFβ1-induced Smad3 phosphorylation and Smad4 nuclear translocation in PanC-1 cells. Furthermore, when TGFβ1-induced NFkB activation was inhibited, TGFβ1-induced Snail up-regulation or E-Cadherin down-regulation was blocked. Deguelin also significantly down regulated the constitutive phosphorylation and DNA binding of NFkB in a dose dependent manner. Interestingly, overexpression of either NFkB or Snail completely abrogated deguelin-mediated EMT inhibition, whereas overexpression of NFkB but not Snail rescued cells from deguelin-induced apoptosis. Hence, deguelin targets NFkB to induce reversal of EMT and apoptosis but downstream effectors might be different for both processes. Taken together, our results suggest that deguelin suppresses both pancreatic tumor growth and metastasis by inducing apoptosis and inhibiting epithelial to mesenchymal transition.
doi:10.1038/onc.2012.413
PMCID: PMC3530646  PMID: 22986522
NFkB; TGF-β; RKIP; Snail; Metastasis; Apoptosis
4.  Caveolin-1 deficiency induces a MEK-ERK1/2-Snail-1-dependent epithelial–mesenchymal transition and fibrosis during peritoneal dialysis 
EMBO Molecular Medicine  2014;7(1):102-123.
Peritoneal dialysis (PD) is a form of renal replacement therapy whose repeated use can alter dialytic function through induction of epithelial–mesenchymal transition (EMT) and fibrosis, eventually leading to PD discontinuation. The peritoneum from Cav1−/− mice showed increased EMT, thickness, and fibrosis. Exposure of Cav1−/− mice to PD fluids further increased peritoneal membrane thickness, altered permeability, and increased the number of FSP-1/cytokeratin-positive cells invading the sub-mesothelial stroma. High-throughput quantitative proteomics revealed increased abundance of collagens, FN, and laminin, as well as proteins related to TGF-β activity in matrices derived from Cav1−/− cells. Lack of Cav1 was associated with hyperactivation of a MEK-ERK1/2-Snail-1 pathway that regulated the Smad2-3/Smad1-5-8 balance. Pharmacological blockade of MEK rescued E-cadherin and ZO-1 inter-cellular junction localization, reduced fibrosis, and restored peritoneal function in Cav1−/− mice. Moreover, treatment of human PD-patient-derived MCs with drugs increasing Cav1 levels, as well as ectopic Cav1 expression, induced re-acquisition of epithelial features. This study demonstrates a pivotal role of Cav1 in the balance of epithelial versus mesenchymal state and suggests targets for the prevention of fibrosis during PD.
doi:10.15252/emmm.201404127
PMCID: PMC4309670  PMID: 25550395
caveolin-1; epithelial–mesenchymal transition; fibrosis; MEK-ERK1/2 pathway; peritoneal dialysis
5.  Distinct dedifferentiation processes affect caveolin-1 expression in hepatocytes 
Background
Dedifferentiation and loss of hepatocyte polarity during primary culture of hepatocytes are major drawbacks for metabolic analyses. As a prominent profibrotic cytokine and potent inducer of epithelial mesenchymal transition (EMT), TGF-β contributes to these processes in liver epithelial cells. Yet, a distinction between culture dependent and TGF-β driven hepatocyte dedifferentiation has not been shown to date.
Results
Here, we show that in both settings, mesenchymal markers are induced. However, upregulation of Snai1 and downregulation of E-Cadherin are restricted to TGF-β effects, neglecting a full EMT of culture dependent hepatocyte dedifferentiation. Mechanistically, the latter is mediated via FAK/Src/ERK/AKT pathways leading to the induction of the oncogene caveolin-1 (Cav1). Cav1 was recently proposed as a new EMT marker, but our results demonstrate Cav1 is not up-regulated in TGF-β mediated hepatocyte EMT, thus limiting validity of its use for this purpose. Importantly, marking differences on Cav1 expression exist in HCC cell lines. Whereas well differentiated HCC cell lines exhibit low and inducible Cav1 protein levels - by TGF-β in a FAK/Src dependent manner, poorly differentiated cell lines display high Cav1 expression levels which are not further modulated by TGF-β.
Conclusions
This study draws a detailed distinction between intrinsic and TGF-β mediated hepatocyte dedifferentiation and elucidates cellular pathways involved. Additionally, by evaluating the regulation of the oncogene Cav1, we provide evidence to argue against Cav1 as a reliable EMT marker.
doi:10.1186/1478-811X-11-6
PMCID: PMC3598962  PMID: 23339737
6.  CpG island shore methylation regulates caveolin-1 expression in breast cancer 
Oncogene  2012;32(38):4519-4528.
Caveolin-1 (Cav1) is an integral membrane, scaffolding protein found in plasma membrane invaginations (caveolae). Cav1 regulates multiple cancer-associated processes. In breast cancer, a tumor suppressive role for Cav1 has been suggested; however, Cav1 is frequently overexpressed in aggressive breast cancer subtypes, suggesting an oncogenic function in advanced-stage disease. To further delineate Cav1 function in breast cancer progression, we evaluated its expression levels among a panel of cell lines representing a spectrum of breast cancer phenotypes. In basal-like (the most aggressive BC subtype) breast cancer cells, Cav1 was consistently upregulated, and positively correlated with increased cell proliferation, anchorage-independent growth, and migration and invasion. To identify mechanisms of Cav1 gene regulation, we compared DNA methylation levels within promoter ‘CpG islands' (CGIs) with ‘CGI shores', recently described regions that flank CGIs with less CG-density. Integration of genome-wide DNA methylation profiles (‘methylomes') with Cav1 expression in 30 breast cancer cell lines showed that differential methylation of CGI shores, but not CGIs, significantly regulated Cav1 expression. In breast cancer cell lines having low Cav1 expression (despite promoter CGI hypomethylation), we found that treatment with a DNA methyltransferase inhibitor induced Cav1 expression via CGI shore demethylation. In addition, further methylome assessments revealed that breast cancer aggressiveness associated with Cav1 CGI shore methylation levels, with shore hypermethylation in minimally aggressive, luminal breast cancer cells and shore hypomethylation in highly aggressive, basal-like cells. Cav1 CGI shore methylation was also observed in human breast tumors, and overall survival rates of breast cancer patients lacking estrogen receptor α (ERα) negatively correlated with Cav1 expression. Based on this first study of Cav1 (a potential oncogene) CGI shore methylation, we suggest this phenomenon may represent a new prognostic marker for ERα-negative, basal-like breast cancer.
doi:10.1038/onc.2012.474
PMCID: PMC3787796  PMID: 23128390
Cav1; CpG island shore; DNA methylation; breast cancer
7.  Caveolin-1 Protects B6129 Mice against Helicobacter pylori Gastritis 
PLoS Pathogens  2013;9(4):e1003251.
Caveolin-1 (Cav1) is a scaffold protein and pathogen receptor in the mucosa of the gastrointestinal tract. Chronic infection of gastric epithelial cells by Helicobacter pylori (H. pylori) is a major risk factor for human gastric cancer (GC) where Cav1 is frequently down-regulated. However, the function of Cav1 in H. pylori infection and pathogenesis of GC remained unknown. We show here that Cav1-deficient mice, infected for 11 months with the CagA-delivery deficient H. pylori strain SS1, developed more severe gastritis and tissue damage, including loss of parietal cells and foveolar hyperplasia, and displayed lower colonisation of the gastric mucosa than wild-type B6129 littermates. Cav1-null mice showed enhanced infiltration of macrophages and B-cells and secretion of chemokines (RANTES) but had reduced levels of CD25+ regulatory T-cells. Cav1-deficient human GC cells (AGS), infected with the CagA-delivery proficient H. pylori strain G27, were more sensitive to CagA-related cytoskeletal stress morphologies (“humming bird”) compared to AGS cells stably transfected with Cav1 (AGS/Cav1). Infection of AGS/Cav1 cells triggered the recruitment of p120 RhoGTPase-activating protein/deleted in liver cancer-1 (p120RhoGAP/DLC1) to Cav1 and counteracted CagA-induced cytoskeletal rearrangements. In human GC cell lines (MKN45, N87) and mouse stomach tissue, H. pylori down-regulated endogenous expression of Cav1 independently of CagA. Mechanistically, H. pylori activated sterol-responsive element-binding protein-1 (SREBP1) to repress transcription of the human Cav1 gene from sterol-responsive elements (SREs) in the proximal Cav1 promoter. These data suggested a protective role of Cav1 against H. pylori-induced inflammation and tissue damage. We propose that H. pylori exploits down-regulation of Cav1 to subvert the host's immune response and to promote signalling of its virulence factors in host cells.
Author Summary
Infection with the bacterium Helicobacter pylori (H. pylori) mainly affects children in the developing countries who are at risk to progress to gastric cancer (GC) as adults after many years of persistent infection, especially with strains which are positive for the oncogenic virulence factor CagA. Eradication of H. pylori by antibiotics is a treatment of choice but may also alter the susceptibility to allergies and other tumor types. Thus, novel diagnostic or prognostic markers are needed which detect early molecular changes in the stomach mucosa during the transition of chronic inflammation to cancer. In our study, we found that the tumor suppressor caveolin-1 (Cav1) is reduced upon infection with H. pylori, and CagA was sufficient but not necessary for this down-regulation. Loss of Cav1 was caused by H. pylori-dependent activation of sterol-responsive element-binding protein-1 (SREBP1), and this event abolished the interaction of Cav1 with p120 RhoGTPase-activating protein/deleted in liver cancer-1 (p120RhoGAP/DLC1), a second bona fide tumor suppressor in gastric tissue. Conclusively, Cav1 and DLC1 may constitute novel molecular markers in the H. pylori-infected gastric mucosa before neoplastic transformation of the epithelium.
doi:10.1371/journal.ppat.1003251
PMCID: PMC3623771  PMID: 23592983
8.  Progesterone reverses the mesenchymal phenotypes of basal phenotype breast cancer cells via a membrane progesterone receptor mediated pathway 
Introduction
Basal phenotype breast cancers (BPBC) are often associated with apparent epithelial to mesenchymal transition (EMT). The role of progesterone (P4) in regulating EMT of BPBC has not been reported.
Methods
The EMT relevant biology was investigated in vitro using human BPBC cell models (MDA-MB468 and MDA-MB231) with P4, PR agonist (RU486), and PR antagonist (R5020) treatments. The essential role of membrane progesterone receptor α (mPRα) in the P4-regulated EMT was demonstrated by knocking down the endogenous gene and/or stably transfecting exogenous mPRα gene in the BPBC cell models.
Results
The expression of snail and down-stream EMT proteins such as occludin, fibronectin, and E-cadherin was significantly regulated by P4 incubation, which was accompanied by cell morphological reversion from mesenchymal to epithelial phenotypes. In searching for the cell mediator of P4' action in the MDA-MB468 (MB468) cells, it was found that mPRα but not the nuclear PR has an essential role in the P4 mediated EMT inhibition. Knocking down the expression of mPRα with specific siRNA blocked the P4's effects on expression of the EMT proteins. In another BPBC cell line - MDA-MB231 (MB231), which is mPRα negative by Western blotting, P4 treatment did not alter cell proliferation and EMT protein expressions. Introduction of the exogenous mPRα cDNA into these cells caused cell proliferation, but not EMT, to become responsive to P4 treatment. In further studies, it was found that activation of the PI3K/Akt pathway is necessary for the P4-induced EMT reversion. To define the potential inter-mediate steps between mPRα and PI3K, we demonstrated that mPRα, caveolin-1 (Cav-1), and epidermal growth factor receptor (EGFR) are colocalized in the membrane of caveolar vesicle and the P4-repressed EMT in MB468 cells can be blocked by EGFR inhibitor (AG1478) and PI3K inhibitor (wortmannin).
Conclusions
Our data suggest that the signaling cascade of P4 induced mesenchymal repression is mediated through mPRα and other caveolae bound signaling molecules namely Cav-1, EGFR, and PI3K. This novel finding may have great impact on fully understanding the pathogenesis of BPBC and provide an essential clue for developing a targeted therapeutic strategy for treatment of BPBC.
doi:10.1186/bcr2588
PMCID: PMC2917029  PMID: 20540763
9.  E-cadherin determines Caveolin-1 tumor suppression or metastasis enhancing function in melanoma cells 
Pigment cell & melanoma research  2013;26(4):555-570.
SUMMARY
The role of caveolin-1 (CAV1) in cancer is highly controversial. CAV1 suppresses genes that favor tumor development, yet also promotes focal adhesion turnover and migration of metastatic cells. How these contrasting observations relate to CAV1 function in vivo is unclear. Our previous studies implicate E-cadherin in CAV1-dependent tumor suppression. Here we use murine melanoma B16F10 cells, with low levels of endogenous CAV1 and E-cadherin, to unravel how CAV1 affects tumor growth and metastasis, and to assess how co-expression of E-cadherin modulates CAV1 function in vivo in C57BL/6 mice. We find that overexpression of CAV1 in B16F10(cav-1) cells reduces subcutaneous tumor formation, but enhances metastasis relative to control cells. Furthermore, E-cadherin expression in B16F10(E-cad) cells reduces subcutaneous tumor formation, and lung metastasis when intravenously injected. Importantly, co-expression of CAV1 and E-cadherin in B16F10(cav1/E-cad) cells abolishes tumor formation, lung metastasis, increased Rac-1 activity and cell migration observed with B16F10(cav-1) cells. Finally, consistent with the notion that CAV1 participates in switching human melanomas to a more malignant phenotype, elevated levels of CAV1 expression correlated with enhanced migration and Rac-1 activation in these cells.
doi:10.1111/pcmr.12085
PMCID: PMC3695072  PMID: 23470013
E-cadherin; molecular switch; CAV1; tumour suppression; metastasis; melanoma model
10.  The inhibitory effect of heat treatment against epithelial-mesenchymal transition (EMT) in human pancreatic adenocarcinoma cell lines 
Epithelial-mesenchymal transition (EMT) plays a crucial role in cancer metastasis. In this study, we evaluated the effect of heat treatment on tumor growth factor-β1 (TGF-β1)-induced EMT in pancreatic cancer cells and tried to ascertain the mechanism related to any observed effects. Human pancreatic cancer cell lines (BxPC-3, PANC-1 and MIAPaCa-2) were stimulated by TGF-β1, and evaluated for morphological changes using immunofluorescence and EMT-related factors (i.e., E-cadherin, Vimentin, Snail or ZEB-1) using RT-PCR. To examine the effect of heat on EMT, the cancer cells were heat-treated at 43°C for 1 h then stimulated with TGF-β1. We then evaluated whether or not heat treatment changed the expression of EMT-related factors and cell migration and also whether Smad activation was inhibited in TGF-β signaling. After being treated with TGF-β1, pancreatic cancer cells resulted in EMT and cell migration was enhanced. Heat treatment inhibited TGF-β1-induced changes in morphology, inhibited the expression of EMT-related factors, and attenuated TGF-β1-induced migration in pancreatic cancer cells. Additionally, we observed that heat treatment blocked TGF-β1-induced phosphorylation of Smad2 in PANC-1 cells. Our results suggest that heat treatment can suppress TGF-β1-induced EMT and opens the possibility of a new therapeutic use of hyperthermia as a potential treatment for cancer metastasis.
doi:10.3164/jcbn.14-8
PMCID: PMC4078073  PMID: 25120280
pancreatic cancer; epithelial-mesenchymal transition; heat treatment; hyperthermia; TGF-β1
11.  Caveolin-1 Is Up-Regulated by GLI1 and Contributes to GLI1-Driven EMT in Hepatocellular Carcinoma 
PLoS ONE  2014;9(1):e84551.
Caveolin-1 (Cav-1) has been recently identified to be over-expressed in hepatocellular carcinoma (HCC) and promote HCC cell motility and invasion ability via inducing epithelial-mesenchymal transition (EMT). However, the mechanism of aberrant overexpression of Cav-1 remains vague. Here, we observed that Cav-1 expression was positively associated with GLI1 expression in HCC tissues. Forced expression of GLI1 up-regulated Cav-1 in Huh7 cells, while knockdown of GLI1 decreased expression of Cav-1 in SNU449 cells. Additionally, silencing Cav-1 abolished GLI1-induced EMT of Huh7 cells. The correlation between GLI1 and Cav-1 was confirmed in tumor specimens from HCC patients and Cav-1 was found to be associated with poor prognosis after hepatic resection. The relationship between protein expression of GLI1 and Cav-1 was also established in HCC xenografts of nude mice. These results suggest that GLI1 may be attributed to Cav-1 up-regulation which plays an important role in GLI1-driven EMT phenotype in HCC.
doi:10.1371/journal.pone.0084551
PMCID: PMC3890273  PMID: 24454730
12.  Slug enhances invasion ability of pancreatic cancer cells through upregulation of matrix metalloproteinase-9 and actin cytoskeleton remodeling 
Slug, a member of the Snail family of transcription factors, has a crucial role in the regulation of epithelial-mesenchymal transition (EMT) by suppressing several epithelial markers and adhesion molecules, including E-cadherin. A recent study demonstrated that no relationship exists between Slug and E-cadherin in pancreatic cancer. Another study showed that in malignant mesothelioma effusions Slug was associated with matrix metalloproteinase (MMP) expression, but that there was no association with E-cadherin. F-ascin is an actin-bundling protein involved in filopodia assembly and cancer invasion and metastasis of multiple epithelial cancer types. In this study, we investigated Slug, E-cadherin, and MMP-9 expression using immunohistochemistry in 60 patients with pancreatic cancer and their correlation with carcinoma invasion and metastasis. Additionally, we observed the effects of Slug on invasion and metastasis in the pancreatic cancer cell line PANC-1. Alterations in Slug, MMP-9, and E-cadherin were determined by RT-PCR, western blot, and immunohistochemistry. Alterations in MMP-9 and F-actin cytoskeleton were determined by immunofluorescence staining, flow cytometry (FCM), or gelatin zymography. Slug, E-cadherin, and MMP-9 expression in pancreatic cancer was significantly associated with lymph node metastases and we found a significant correlation between Slug and MMP-9 expression; however, no significant correlation was observed between Slug and E-cadherin expression. Slug transfection significantly increased invasion and metastasis in PANC-1 cells and orthotopic tumor of mouse in vivo, and significantly upregulated and activated MMP-9; however, there was no effect on E-cadherin expression. Slug promoted the formation of lamelliopodia or filopodia in PANC-1 cells. The intracellular F-actin and MMP-9 was increased and relocated to the front of the extending pseudopodia from the perinuclear pool in Slug-transfected PANC-1 cells. These results suggest that Slug promotes migration and invasion of PANC-1 cells, which may correlate with the reorganization of MMP-9 and remodeling of the F-actin cytoskeleton, but not with E-cadherin expression.
doi:10.1038/labinvest.2010.201
PMCID: PMC3125102  PMID: 21283078
E-cadherin; epithelial-mesenchymal transition; F-actin cytoskeleton; matrix metalloproteinase; metastasis; pancreatic carcinoma; Slug
13.  Snail Contributes to the Maintenance of Stem Cell-Like Phenotype Cells in Human Pancreatic Cancer 
PLoS ONE  2014;9(1):e87409.
Snail, a potent repressor of E-cadherin expression, plays a key role in epithelial-to-mesenchymal transition (EMT) in epithelial cancer. Recently, EMT and stemness programs are found linked together. In the current study, the expression of Snail and its contribution to cancer stem cell (CSC) marker expression, invasiveness, self-renewal, clonogenicity, and tumorigenicity of pancreatic cancer cells were studied. Our results showed that Snail was highly expressed in CSChigh cell line Panc-1. Stable, short hairpin RNA (shRNA)-mediated Snail knockdown decreased invasion in Panc-1 cells, in line with increased E-cadherin expression and its translocation from the nucleus to the membrane. Snail silencing in Panc-1 also inhibited CSC marker ALDH expression, together with decreased sphere and colony forming capacity, which was highly consistent with the expression of stem cell associated transcription factors like Sox2 and Oct4. In mouse xenograft models, knockdown of Snail led to a reduced number of tumor-bearing mice and a reduced average size of tumors, which had a stronger membrane staining of E-cadherin and lighter staining of Oct4. Collectively, these findings implicate Snail is required for the maintenance of stem cell-like phenotype in pancreatic cancer, and inhibition of Snail could be an efficient strategy to treat pancreatic cancer by targeting CSCs.
doi:10.1371/journal.pone.0087409
PMCID: PMC3906155  PMID: 24489910
14.  CAV1 Promotes HCC Cell Progression and Metastasis through Wnt/β-Catenin Pathway 
PLoS ONE  2014;9(9):e106451.
Caveolin-1 (CAV1) has significant roles in many primary tumors and metastasis, despite the fact that malignant cells from different cancer types have different profiles of CAV1 expression. There is little information concerning CAV1 expression and role in hepatocellular carcinoma (HCC) progresion and metastasis. The role of CAV1 in HCC progression was explored in this study. We reported that CAV1 was overexpressed in highly invasive HCC cell lines compared with poorly invasive ones. The immunohistochemical staining was obviously stronger in metastatic HCC samples than in the non-metastatic specimens via tissue microarrays. Furthermore, CAV1 overexpression enhanced HCC cell invasiveness in vitro, and promoted tumorigenicity and lung metastasis in vivo. By contrast, CAV1 stable knockdown markedly reduced these malignant behaviors. Importantly, we found that CAV1 could induce EMT process through Wnt/β-catenin pathway to promote HCC metastasis. We also identify MMP-7 as a novel downstream target of CAV1. We have determined that CAV1 acts as a mediator between hyperactive ERK1/2 signaling and regulation of MMP-7 transcription. Together, these studies mechanistically show a previously unrecognized interplay between CAV1, EMT, ERK1/2 and MMP-7 that is likely significant in the progression of HCC toward metastasis.
doi:10.1371/journal.pone.0106451
PMCID: PMC4152279  PMID: 25180681
15.  Regulation of pancreatic cancer cell migration and invasion by RhoC GTPase and Caveolin-1 
Molecular Cancer  2005;4:21.
Background
In the current study we investigated the role of caveolin-1 (cav-1) in pancreatic adenocarcinoma (PC) cell migration and invasion; initial steps in metastasis. Cav-1 is the major structural protein in caveolae; small Ω-shaped invaginations within the plasma membrane. Caveolae are involved in signal transduction, wherein cav-1 acts as a scaffolding protein to organize multiple molecular complexes regulating a variety of cellular events. Recent evidence suggests a role for cav-1 in promoting cancer cell migration, invasion and metastasis; however, the molecular mechanisms have not been described. The small monomeric GTPases are among several molecules which associate with cav-1. Classically, the Rho GTPases control actin cytoskeletal reorganization during cell migration and invasion. RhoC GTPase is overexpressed in aggressive cancers that metastasize and is the predominant GTPase in PC. Like several GTPases, RhoC contains a putative cav-1 binding motif.
Results
Analysis of 10 PC cell lines revealed high levels of cav-1 expression in lines derived from primary tumors and low expression in those derived from metastases. Comparison of the BxPC-3 (derived from a primary tumor) and HPAF-II (derived from a metastasis) demonstrates a reciprocal relationship between cav-1 expression and p42/p44 Erk activation with PC cell migration, invasion, RhoC GTPase and p38 MAPK activation. Furthermore, inhibition of RhoC or p38 activity in HPAF-II cells leads to partial restoration of cav-1 expression.
Conclusion
Cav-1 expression inhibits RhoC GTPase activation and subsequent activation of the p38 MAPK pathway in primary PC cells thus restricting migration and invasion. In contrast, loss of cav-1 expression leads to RhoC-mediated migration and invasion in metastatic PC cells.
doi:10.1186/1476-4598-4-21
PMCID: PMC1173138  PMID: 15969750
Pancreatic cancer; RhoC GTPase; caveolin-1; cell migration; metastasis; MAPK
16.  The caveolin proteins 
Genome Biology  2004;5(3):214.
Caveolins are markers of caveolae, invaginations in the plasma membrane, and there are three members of the family in vertebrates. Caveolins participate in many important cellular processes, including vesicular transport, cholesterol homeostasis, signal transduction, and tumor suppression.
The caveolin gene family has three members in vertebrates: caveolin-1, caveolin-2, and caveolin-3. So far, most caveolin-related research has been conducted in mammals, but the proteins have also been found in other animals, including Xenopus laevis, Fugu rubripes, and Caenorhabditis elegans. Caveolins can serve as protein markers of caveolae ('little caves'), invaginations in the plasma membrane 50-100 nanometers in diameter. Caveolins are found predominantly at the plasma membrane but also in the Golgi, the endoplasmic reticulum, in vesicles, and at cytosolic locations. They are expressed ubiquitously in mammals, but their expression levels vary considerably between tissues. The highest levels of caveolin-1 (also called caveolin, Cav-1 and VIP2I) are found in terminally-differentiated cell types, such as adipocytes, endothelia, smooth muscle cells, and type I pneumocytes. Caveolin-2 (Cav-2) is colocalized and coexpressed with Cav-1 and requires Cav-1 for proper membrane targeting; the Cav-2 gene also maps to the same chromosomal region as Cav-1 (7q31.1 in humans). Caveolin-3 (Cav-3) has greater protein-sequence similarity to Cav-1 than to Cav-2, but it is expressed mainly in muscle cells, including smooth, skeletal, and cardiac myocytes. Caveolins participate in many important cellular processes, including vesicular transport, cholesterol homeostasis, signal transduction, and tumor suppression.
PMCID: PMC395759  PMID: 15003112
17.  Autophagy in cancer associated fibroblasts promotes tumor cell survival 
Cell Cycle  2010;9(17):3515-3533.
Recently, using a co-culture system, we demonstrated that MCF7 epithelial cancer cells induce oxidative stress in adjacent cancer-associated fibroblasts, resulting in the autophagic/lysosomal degradation of stromal caveolin-1 (Cav-1). However, the detailed signaling mechanism(s) underlying this process remain largely unknown. Here, we show that hypoxia is sufficient to induce the autophagic degradation of Cav-1 in stromal fibroblasts, which is blocked by the lysosomal inhibitor chloroquine. Concomitant with the hypoxia-induced degradation of Cav-1, we see the upregulation of a number of well-established autophagy/mitophagy markers, namely LC3, ATG16L, BNIP3, BNIP3L, HIF-1α and NFκB. In addition, pharmacological activation of HIF-1α drives Cav-1 degradation, while pharmacological inactivation of HIF-1 prevents the downregulation of Cav-1. Similarly, pharmacological inactivation of NFκB—another inducer of autophagy—prevents Cav-1 degradation. Moreover, treatment with an inhibitor of glutathione synthase, namely BSO, which induces oxidative stress via depletion of the reduced glutathione pool, is sufficient to induce the autophagic degradation of Cav-1. Thus, it appears that oxidative stress mediated induction of HIF1- and NFκB-activation in fibroblasts drives the autophagic degradation of Cav-1. In direct support of this hypothesis, we show that MCF7 cancer cells activate HIF-1α- and NFκB-driven luciferase reporters in adjacent cancer-associated fibroblasts, via a paracrine mechanism. Consistent with these findings, acute knockdown of Cav-1 in stromal fibroblasts, using an siRNA approach, is indeed sufficient to induce autophagy, with the upregulation of both lysosomal and mitophagy markers. How does the loss of stromal Cav-1 and the induction of stromal autophagy affect cancer cell survival? Interestingly, we show that a loss of Cav-1 in stromal fibroblasts protects adjacent cancer cells against apoptotic cell death. Thus, autophagic cancer-associated fibroblasts, in addition to providing recycled nutrients for cancer cell metabolism, also play a protective role in preventing the death of adjacent epithelial cancer cells. We demonstrate that cancer-associated fibroblasts upregulate the expression of TIGAR in adjacent epithelial cancer cells, thereby conferring resistance to apoptosis and autophagy. Finally, the mammary fat pads derived from Cav-1 (−/−) null mice show a hypoxia-like response in vivo, with the upregulation of autophagy markers, such as LC3 and BNIP3L. Taken together, our results provide direct support for the “autophagic tumor stroma model of cancer metabolism”, and explain the exceptional prognostic value of a loss of stromal Cav-1 in cancer patients. Thus, a loss of stromal fibroblast Cav-1 is a biomarker for chronic hypoxia, oxidative stress and autophagy in the tumor microenvironment, consistent with its ability to predict early tumor recurrence, lymph node metastasis and tamoxifen-resistance in human breast cancers. Our results imply that cancer patients lacking stromal Cav-1 should benefit from HIF-inhibitors, NFκB-inhibitors, anti-oxidant therapies, as well as autophagy/lysosomal inhibitors. These complementary targeted therapies could be administered either individually or in combination, to prevent the onset of autophagy in the tumor stromal compartment, which results in a “lethal” tumor microenvironment.
doi:10.4161/cc.9.17.12928
PMCID: PMC3047617  PMID: 20855962
caveolin-1; autophagy; BNIP3; cancer-associated fibroblasts; HIF1; hypoxia; LC3; mitophagy; NFκB; oxidative stress; predictive biomarker; TIGAR; tumor stroma
18.  Knock-down of plasminogen-activator inhibitor-1 enhances expression of E-cadherin and promotes epithelial differentiation of human pancreatic adenocarcinoma cells 
Journal of cellular physiology  2012;227(11):3621-3628.
High levels of plasminogen activator inhibitor-1 (PAI-1), which is produced by stromal, endothelial and cancer cells and has multiple complex effects on cancers, correlate with poor cancer prognosis. To more definitively study the role of endogenously produced PAI-1 in human pancreatic adenocarcinoma (PAC) PANC-1 cell line biology, we used anti-PAI-1 shRNA to create stable PAI-1 deficient cells (PD-PANC-1s). PD-PANC-1s exhibited a heterogeneous morphology. While the majority of cells exhibited a cuboidal shape similar to the parental PANC-1 or the vector-infected control cells, numerous large cells with long filopodia and a neuronal-like appearance were observed. Although both Vector-control cells and PD-PANC-1s expressed mRNAs that are characteristic of mesenchymal, neural and epithelial phenotypes, epithelial marker RNAs were up-regulated (e.g. E-cadherin, 32-fold) whereas mesenchymal marker RNAs were down-regulated (e.g. Thy1, 9-fold) in PD-PANC-1s, suggesting mesenchymal-to-epithelial transition. Neural markers exhibited both up- and down-regulation. Immunocytochemistry indicated that epithelial-like PD-PANC-1s expressed E-cadherin and β-catenin in significantly more cells, while neural-like cells exhibited robust expression of organized β-3-tubulin. PAI-1 and E-cadherin were rarely co-expressed in the same cells. Indeed, examination of PAI-1 and E-cadherin mRNAs expression in additional cell lines yielded clear inverse correlation. Indeed, infection of Colo357 PAC cells (that exhibit high expression of E-cadherin) with PAI-1-expressing adenovirus led to a marked decrease in E-cadherin expression and to enhanced migration of cells from clusters. Our results suggest that endogenous PAI-1 suppresses expression of E-cadherin and differentiation in PAC cells in vitro, supporting its negative impact on tumor prognosis.
doi:10.1002/jcp.24068
PMCID: PMC3469200  PMID: 22331587
Plasminogen activator inhibitor 1; E-cadherin; Differentiation; Human pancreatic adenocarcinoma
19.  Expression of caveolin in trabecular meshwork cells and its possible implication in pathogenesis of primary open angle glaucoma 
Molecular Vision  2011;17:2878-2888.
Purpose
Primary open-angle glaucoma (POAG), which is the most common form of glaucoma, has been associated with a heterogeneous genetic component. A genome-wide association study has identified a common sequence variant at 7q31 (rs4236601 [A]) near the caveolin genes in patients with POAG. Caveolins are a family of integral membrane proteins which participate in many cellular processes, including vesicular transport, cholesterol homeostasis, signal transduction, cell adhesion and migration. The goal of this study was to investigate the expression and regulation of caveolin 1 (CAV-1) and caveolin 2 (CAV-2) in normal and glaucoma trabecular meshwork (TM) cells.
Methods
CAV-1 and CAV-2 protein expression was quantified by immunoblot analysis using lysates isolated from primary and immortalized TM cells or TM tissue dissected from normal and POAG eyes. The localization of caveolins in TM cells was assessed by immunofluorescent microscopy. CAV-1 and CAV-2 protein expression was also investigated in TM cells at various time points after subjecting the cells to known glaucomatous insults like dexamethasone (DEX) and tumor growth factor beta2 (TGF-β2) treatment. Phosphorylation of CAV-1 at tyrosine 14 in normal and glaucoma TM cell lines was evaluated using a specific monoclonal antibody (Ab). The 5′ upstream region of the CAV-1 gene was amplified and the sequence variant rs4236601 (A/G polymorphic site) and several putative transcription factor-binding sites were modified by in vitro mutagenesis. The effect of nucleotide sequence modifications in the CAV-1 upstream region on gene expression was assayed in a luciferase-based system in TM and non-TM cells.
Results
CAV-1 and CAV-2 are expressed in TM cells, with localization to the cytoplasm and perinuclear region. DEX increased CAV-1 expression in immortalized glaucoma TM cells by 2.8±0.1 (n=3) fold at 24 h and 2.5±0.1 (n=3) fold at 48 h, compared to 1.3±0.06 (n=3) fold at 24 and 48 h in immortalized normal TM cells. Phosphorylation of CAV-1 at Tyr14 was reduced by 3.2±0.15 (n=3) fold in glaucomatous TM cells when compared to normal TM cells. In POAG and normal TM tissue, CAV-1 expression was found to be uniform. CAV-2, on the other hand, was variable in independent normal and glaucoma TM tissue. Substitution of a G for an A at base pair −2,388 upstream of the start codon of CAV-1, corresponding to the minor allele rs4236601 [A], increased transcriptional activity in TM and non-TM cells when compared to the native sequence. Deletion analysis of putative transcription factor binding sites in the CAV-1 promoter region caused cell-specific effects on gene expression.
Conclusions
CAV-1 and CAV-2 are expressed in normal and glaucoma tissue and TM cell lines. Phosphorylation of Tyr14 in CAV-1 and transcriptional regulation of CAV-1 expression may have a role in glaucomatous alterations in TM cells.
PMCID: PMC3225292  PMID: 22128235
20.  Caffeic Acid Phenethyl Ester Inhibits Epithelial-Mesenchymal Transition of Human Pancreatic Cancer Cells 
Background. This study aimed to investigate the effect of propolis component caffeic acid phenethyl ester (CAPE) on epithelial-mesenchymal transition (EMT) of human pancreatic cancer cells and the molecular mechanisms underlying these effects. Methods. The transforming growth factor β (TGF-β-) induced EMT in human pancreatic PANC-1 cancer cells was characterized by observation of morphology and the expression of E-cadherin and vimentin by western blotting. The migration potential was estimated with wound closure assay. The expression of transcriptional factors was measured by quantitative RT-PCR and immunocytochemistry staining. The orthotopic pancreatic cancer xenograft model was used for in vivo assessment. Results. The overexpression of vimentin was attenuated by CAPE, and the alteration in morphology from polygonal to spindle shape was partially reversed by CAPE. Furthermore, CAPE delayed the TGF-β-stimulated migration potential. CAPE treatment did not reduce the expression levels of Smad 2/3, Snail 1, and Zeb 1 but inhibited the expression of transcriptional factor Twist 2. By using an orthotopic pancreatic cancer model, CAPE suppressed the expression of Twist 2 and growth of PANC-1 xenografts without significant toxicity. Conclusion. CAPE could inhibit the orthotopic growth and EMT of pancreatic cancer PANC-1 cells accompanied by downregulation of vimentin and Twist 2 expression.
doi:10.1155/2013/270906
PMCID: PMC3638595  PMID: 23662124
21.  Loss of Stromal Caveolin-1 Expression: A Novel Tumor Microenvironment Biomarker That Can Predict Poor Clinical Outcomes for Pancreatic Cancer 
PLoS ONE  2014;9(6):e97239.
Aims
Cancer development and progression is not only associated with the tumor cell proliferation but also depends on the interaction between tumor cells and the stromal microenvironment. A new understanding of the role of the tumor microenvironment suggests that the loss of stromal caveolin-1 (Cav-1) as a key regulator may become a potential therapy target. This study aims to elucidate whether stromal Cav-1 expression in pancreatic cancer can be a strong prognosis biomarker.
Methods
Tissue samples from 45 pancreatic cancer patients were studied. Parenchyma and stroma were separated and purified using laser capture microdissection. Stromal Cav-1 expression was measured from pancreatic cancer, paraneoplastic, and normal tissue using immunohistochemistry. We analyzed the correlation of stromal Cav-1 expression with clinicopathologic features and prognostic indicators, such as tumor marker HER-2/neu gene.
Results
Specimens from six patients (13.3%) showed high levels of stromal Cav-1 staining, those from eight patients (17.8%) showed a lower, intermediate level of staining, whereas those from 31 patients (68.9%) showed an absence of staining. Cav-1 expression in cancer-associated fibroblasts was lower than that in paracancer-associated and in normal fibroblasts. Stromal Cav-1 loss was associated with TNM stage (P = 0.018), lymph node metastasis (P = 0.014), distant metastasis (P = 0.027), and HER-2/neu amplification (P = 0.007). The relationships of age, sex, histological grade, and tumor size with stromal Cav-1 expression were not significant (P>0.05). A negative correlation was found between circulating tumor cells and stromal Cav-1 expression (P<0.05).
Conclusion
The loss of stromal Cav-1 in pancreatic cancer was an independent prognostic indicator, thus suggesting that stromal Cav-1 may be an effective therapeutic target for patients with pancreatic cancer.
doi:10.1371/journal.pone.0097239
PMCID: PMC4064978  PMID: 24949874
22.  Differential regulation of cell functions by CSD peptide subdomains 
Respiratory Research  2013;14(1):90.
Background
In fibrotic lung diseases, expression of caveolin-1 is decreased in fibroblasts and monocytes. The effects of this deficiency are reversed by treating cells or animals with the caveolin-1 scaffolding domain peptide (CSD, amino acids 82–101 of caveolin-1) which compensates for the lack of caveolin-1. Here we compare the function of CSD subdomains (Cav-A, Cav-B, Cav-C, Cav-AB, and Cav-BC) and mutated versions of CSD (F92A and T90A/T91A/F92A).
Methods
Migration toward the chemokine CXCL12 and the associated expression of F-actin, CXCR4, and pSmad 2/3 were studied in monocytes from healthy donors and SSc patients. Fibrocyte differentiation was studied using PBMC from healthy donors and SSc patients. Collagen I secretion and signaling were studied in fibroblasts derived from the lung tissue of healthy subjects and SSc patients.
Results
Cav-BC and CSD at concentrations as low as 0.01 μM inhibited the hypermigration of SSc monocytes and TGFβ-activated Normal monocytes and the differentiation into fibrocytes of SSc and Normal monocytes. While CSD also inhibited the migration of poorly migrating Normal monocytes, Cav-A (and other subdomains to a lesser extent) promoted the migration of Normal monocytes while inhibiting the hypermigration of TGFβ-activated Normal monocytes. The effects of versions of CSD on migration may be mediated in part via their effects on CXCR4, F-actin, and pSmad 2/3 expression. Cav-BC was as effective as CSD in inhibiting fibroblast collagen I and ASMA expression and MEK/ERK signaling. Cav-C and Cav-AB also inhibited collagen I expression, but in many cases did not affect ASMA or MEK/ERK. Cav-A increased collagen I expression in scleroderma lung fibroblasts. Full effects on fibroblasts of versions of CSD required 5 μM peptide.
Conclusions
Cav-BC retains most of the anti-fibrotic functions of CSD; Cav-A exhibits certain pro-fibrotic functions. Results obtained with subdomains and mutated versions of CSD further suggest that the critical functional residues in CSD depend on the cell type and readout being studied. Monocytes may be more sensitive to versions of CSD than fibroblasts and endothelial cells because the baseline level of caveolin-1 in monocytes is much lower than in these other cell types.
doi:10.1186/1465-9921-14-90
PMCID: PMC3849990  PMID: 24011378
Caveolin-1; Monocytes; Fibrocytes; Fibroblasts; Scleroderma (SSc); Migration; TGFβ
23.  Divergent control of Cav-1 expression in non-cancerous Li-Fraumeni syndrome and human cancer cell lines 
Cancer Biology & Therapy  2013;14(1):29-38.
Li-Fraumeni syndrome (LFS) is primarily characterized by development of tumors exhibiting germ-line mutations in the p53 gene. Cell lines developed from patients of a LFS family have decreased p53 activity as evidenced by the absence of apoptosis upon etoposide treatment. To test our hypothesis that changes in gene expression beyond p53 per se are contributing to the development of tumors, we compared gene expression in non-cancerous skin fibroblasts of LFS-affected (p53 heterozygous) vs. non-affected (p53 wild-type homozygous) family members. Expression analysis showed that several genes were differentially regulated in the p53 homozygous and heterozygous cell lines. We were particularly intrigued by the decreased expression (~88%) of a putative tumor-suppressor protein, caveolin-1 (Cav-1), in the p53-mutant cells. Decreased expression of Cav-1 was also seen in both p53-knockout and p21-knockout HTC116 cells suggesting that p53 controls Cav-1 expression through p21 and leading to the speculation that p53, Cav-1 and p21 may be part of a positive auto-regulatory feedback loop. The direct relationship between p53 and Cav-1 was also tested with HeLa cells (containing inactive p53), which expressed a significantly lower Cav-1 protein. A panel of nonfunctional and p53-deficient colon and epithelial breast cancer cell lines showed undetectable expression of Cav-1 supporting the role of p53 in the control of Cav-1. However, in two aggressively metastasizing breast cancer cell lines, Cav-1 was strongly expressed suggesting a possible role in tumor metastasis. Thus, there is a divergent control of Cav-1 expression as evidenced in non-cancerous Li-Fraumeni syndrome and some aggressive human cancer cell lines.
doi:10.4161/cbt.22621
PMCID: PMC3566049  PMID: 23114650
Caveolin-1 (cav-1); Li-Fraumeni syndrome (LFS); p53; non-cancerous skin fibroblasts (NSFs)
24.  Inhibition of Epithelial Mesenchymal Transition (EMT) With Immunochemogene Treatment in Metastatic Colorectal Cancer 
Background:
Epithelial to mesenchymal transition (EMT) causes resistance to epidermal growth factor receptor (EGFR) inhibitors. We used immunochemogene treatment composed of a stealth nanoparticle formulation, consisting of clamp PNA against mRNA of FOXC2, anti-CD44 chimeric MAb, and vinorelbine, in an attempt to eradicate metastatic colorectal cancer (mCRC) cells and inhibit metastasis by blocking EMT.
Methods:
Tumor cells from patients with stage IV chemoresistant CRC characterized by upregulation of FOXC2, CD44, and bcl-2 were obtained surgically. We synthesized antisense clamp peptide nucleic acid (PNA) oligomers (DNA analogs), in which the 6 mer homopyrimidine triplex [(PNA)2/RNA)] hybridized to the 5-end (Leader), and the 10 mer purine/pyrimidine duplex (PNA/RNA) hybridized to the 3-end (Trailer) of the AUG start codon region on the mRNA of FOXC2. The uncharged and hydrophilic antisense clamp PNA anti-FOXC2 was incorporated in the polar phase, and the vinorelbine molecules were entrapped in the acyl-chains of the lipid phase. This was surrounded by the stealth/biocompatibility polymer layer and biological recognition layer with linked chimeric MAbs against CD44 of the nanoparticle formulation. This was used to treat xenograft animal models developed from CRC cells obtained from the stage IV patients. Tumor cells were analyzed with microarray, single-nucleotide polymorphism (SNP) assay, polymerase chain reaction (PCR), western blot (WB), Southern blot (SB), immunoblotting (LC-MS/MS), immunofluorescence staining, immunohistochemistry (IHC), fluorescent activated cell sorter (FACS), confocal microscopy, transmission electron microscopy (TEM), bromodeoxyuridine (BrdU), MTT, and flow cytometry.
Results:
Post-treatment, we observed downregulation of CD44 and Fra-2, and induction of antibody-dependent cellular cytotoxicity (ADCC). The clamp PNA inhibited translation of FOXC2, resulting in activation of Jak2/Stat5a genes, which led to suppression of EMT of cancer cells. This blocked CRC metastatic invasion by reversing the mesenchymal phenotype; reconstituted homotypic adhesion; and promoted differentiation in CRC cells. Undifferentiated epithelial cells undergoing EMT exhibited overexpression of FOXC2, and this expression was lost when these cells returned to their initial differentiated epithelial state, blocking invasion and metastasis. Inhibition of EMT downregulated EGFR and inactivated NF-kB, inhibiting its downstream signaling pathway. Epithelial cell junction proteins claudin 4, claudin 7, and E-cadherin were overexpressed, upregulating beta-catenin; while mesenchymal markers vimentin and fibronectin were downregulated. Downregulation of Twist, Snail, and transcription 3 and 5 blocked the migratory potential of tumor cells, inhibiting metastasis. Calcium-independent cell-cell adhesion molecules EpCAM and TROP2 were upregulated. Vinorelbine blocked tumor cells at G2/M cell cycle, and phosphorylated bcl-2. This circumvented resistance to anoikis, inducing apoptosis in tumor cells due to lack of adhesion, inhibiting invasion and metastasis. In addition to the induction of caspase-dependent apoptosis or programmed cell death (PCD) type I in tumor cells, bcl-2 downregulation caused release of beclin-1 and upregulation of bcl-2–interacting mediator of cell death (BIM), inducing type II PCD or autophagy. TEM exhibited bystander killing effect of tumor cells by adjacent cells, and activated phagocytic cells such as macrophages. DNA synthesis and metabolic activity of tumor cells were inhibited according to BrdU and MTT tests, respectively.
Conclusion:
This immunochemogene treatment induced epithelial differentiation by reversing the mesenchymal phenotype, promoted homotypic adhesion, inhibited the multigene signature indicative of EMT, blocking metastatic cell motility/invasiveness, and eradicated mCRC cells resistant to EGFR inhibitors by induction of PCD type-I and type-II, apoptosis and autophagy, leading to a bystander killing effect.
PMCID: PMC3056306
25.  MMTV promoter–regulated caveolin-1 overexpression yields defective parenchymal epithelia in multiple exocrine organs of transgenic mice 
Experimental and molecular pathology  2010;89(1):10.1016/j.yexmp.2010.03.009.
Caveolin-1 (Cav-1) is a major structural protein of caveolae, specialized plasma membrane invaginations that are involved in a cell-specific fashion in diverse cell activities such as molecular transport, cell adhesion, and signal transduction. In normal adult mammals, Cav-1 expression is abundant in mesenchyme-derived cells but relatively low in epithelial parenchyma. However, epithelial Cav-1 overexpression is associated with development and/or progression of many carcinomas. In this study, we generated and characterized a transgenic mouse model of Cav-1 overexpression under the control of a mouse mammary tumor virus (MMTV) long terminal repeat promoter, which is predominantly expressed in specific epithelial cells. The MMTVcav-1+ transgenic mice were fertile, and females bore litters of normal-size with no obvious developmental abnormalities. However, by age 11 months, the MMTVcav-1+ mice demonstrated overtly different phenotypes in multiple exocrine organs when compared with their nontransgenic MMTVcav-1− littermates. Cav-1 overexpression in MMTVcav-1+ mice produced organ-specific abnormalities, including hypotrophy of mammary glandular epithelia, bronchiolar epithelial hyperplasia and atypia, mucous-cell hyperplasia in salivary glands, elongated hair follicles and dermal thickening in the skin, and reduced accumulation of enzymogen granules in pancreatic acinar cells. In addition, the MMTVcav-1+ transgenic mice tended to have a greater incidence of malignant tumors, including lung and liver carcinomas and lymphoma, than their MMTVcav-1− littermates. Our results indicate that Cav-1 overexpression causes organ-specific, age-related epithelial disorders and suggest the potential for increased susceptibility to carcinogenesis.
doi:10.1016/j.yexmp.2010.03.009
PMCID: PMC3881545  PMID: 20399205
MMTV-promoter; Cav-1 overexpression; parenchymal epithelia; exocrine organs

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