Amount Of E-cadherin Research Articles

Controlling Cell Organization in 3D Coculture Spheroids Using DNA Interactions.

The role of stromal and immune cells in transforming the tumor microenvironment is a key consideration in understanding tumor cell behavior and anticancer drug development. To better model these systems in vitro, 3D coculture tumor spheroids have been engineered using a variety of techniques including centrifugation to microwells, hanging drop, low adhesion cultures, and culture of cells in a microfluidic platform. Aside from using bioprinting, however, it has remained more challenging to direct the spatial organization of heterotypic cells in standalone 3D spheroids. To address this, we present an in vitro 3D coculture tumor model where we modulated the interactions between cancer cells and fibroblasts through DNA hybridization. When native heterotypic cells are simply mixed, the cell aggregates typically show cell sorting behavior to form phase separated structures composed of single cell types. In this work, we demonstrate that when MDA-MB-468 breast cancer and NIH/3T3 fibroblasts are directed to associate via complementary DNA, a uniform distribution of the two cell types within a single spheroid was observed. In contrast, in the absence of specific DNA interactions between the cancer cells and fibroblasts, individual clusters of the NIH/3T3 cells formed in each spheroid due to cell sorting. To better understand the effect of heterotypic cell organization on either cell-cell contacts or matrix protein production, the spheroids were further stained with anti-E-cadherin and antifibronectin antibodies. While the amounts of E-cadherin appeared to be similar between the spheroids, a significantly higher amount of fibronectin secretion was observed in the coculture spheroids with uniform mixing of two cell types. This result showed that different heterotypic cell distributions within 3D architecture can influence the ECM protein production that can again alter the properties of the tumor or tumor microenvironment. The present study thus describes the use of DNA templating to direct the organization of cells in coculture spheroids, which can provide mechanistic biological insight into how heterotypic distribution in tumor spheroids can influence tumor progression, metastasis, and drug resistance.

In vitro and in vivo effects of a mycotoxin, deoxynivalenol, and a trace metal, cadmium, alone or in a mixture on the intestinal barrier

Deoxynivalenol (DON), one of the most widespread mycotoxins in Europe, and cadmium (Cd), a widespread environmental pollutant, are common food contaminants. They exert adverse effects on different organs including kidney, liver, and intestine. The intestine is a common target of DON and Cd when they are ingested. Most studies have focused on their individual effects whereas their combined toxicity has rarely been studied. The aim of this study was thus to evaluate their individual and combined effects on the intestinal barrier function in vitro and in vivo. In vitro, Caco-2 cells were treated with increasing concentrations of DON and Cd (1–30 μM). In vivo, Wistar rats were used as controls or exposed to DON contaminated feed (8.2 mg/kg feed), Cd-contaminated water (5 mg/l) or both for four weeks. In Caco-2 cells, DON, Cd and the DON+Cd mixture reduced transepithelial electrical resistance (TEER) and increased paracellular permeability in a dose-dependent manner. Impairment of the barrier function was associated with a decrease in the amount of E-cadherin and occludin after exposure to the two contaminants alone or combined. A decrease in E-cadherin expression was observed in rats exposed to the two contaminants alone or combined, whereas occludin expression only decreased in animals exposed to DON and DON+Cd. Jejunal crypt depth was reduced in rats exposed to DON or Cd, whereas villi height was not affected. In vitro and in vivo results showed that the effects of exposure to combined DON and Cd on the intestinal barrier function in the jejunum of Wistar rats and in the colorectal cancer cell line (Caco-2) was similar to the effects of each individual contaminant. This suggests that regulations for each individual contaminant are sufficiently protective for consumers.

Ethanolic Ginkgo biloba leaf extract prevents renal fibrosis through Akt/mTOR signaling in diabetic nephropathy

BackgroundRecently, extract of Ginkgo biloba leaves (GbE) have become widely known phytomedicines and have shown various pharmacological activities, including improvement of blood circulation, protection of oxidative cell damage, prevention of Alzheimer's disease, treatment of cardiovascular disease and diabetes complications. This study was designed to investigate the effects of an ethanolic GbE on renal fibrosis in diabetic nephropathy (DN) and to clarify the possible mechanism by which GbE prevents renal fibrosis. Study designWe investigated the protective effects of GbE on renal fibrosis in STZ-induced diabetic rats. Rats were randomized into six groups termed normal control, diabetes mellitus, low dose of GbE (50 mg/kg/d), intermediate dose of GbE (100 mg/kg/d), high dose of GbE (200 mg/kg/d) and rapamycin (1 mg/kg/d). MethodsAfter 12 weeks, the rats were sacrificed and then fasting blood glucose (FBG), creatinine (Cr), blood urea nitrogen (BUN), urine protein, relative kidney weight, glycogen and collagen accumulation, and collagen IV and laminin expression were measured by different methods. The amounts of E-cadherin, α-SMA and snail, as well as the phosphorylation of Akt, mTOR and p70S6K in the renal cortex of rats, were examined by western blotting. ResultsCompared with diabetic rats, the levels of Cr, BUN, urine protein, relative kidney weight, accumulation of glycogen and collagen, and expression of collagen IV and laminin in the renal cortex were all decreased in GbE treated rats. In addition, GbE reduced the expression of E-cadherin, α-SMA, snail and the phosphorylation of Akt, mTOR and p70S6K in diabetic renal cortex. ConclusionGbE can prevent renal fibrosis in rats with diabetic nephropathy, which is most likely to be associated with its abilities to inhibit the Akt/mTOR signaling pathway.

Cell fusion mediates dramatic alterations in the actin cytoskeleton, focal adhesions, and E‐cadherin in trophoblastic cells

The syncytiotrophoblast of the human placenta is a unique epithelia structure with millions of nuclei sharing a common cytoplasm. The syncytiotrophoblast forms by cell-cell fusion of cytotrophoblasts (CTB), the mononuclear precursor cells. The trophoblastic BeWo cell line has been used as a surrogate for CTB since they can be induced to fuse, and subsequently display numerous syncytiotrophoblast differentiation markers following syncytial formation. In this study, we have focused on alterations in the cell-adhesion molecule E-cadherin, actin cytoskeleton, and focal adhesions following BeWo cell fusion, since these entities may be interrelated. There was a dramatic reorganization of the distribution of E-cadherin as well as a reduction in the amount of E-cadherin following cell fusion. Reorganization of the actin cytoskeleton was also observed, which was associated with a change in the globular actin (G-actin)/filamentous actin (F-actin) ratio. Concomitantly, the morphology of focal adhesions was altered, but this occurred without a corresponding change in the levels of focal adhesion marker proteins. Thus, extensive remodeling of the actin cytoskeleton and focal adhesions accompanies cell fusion and differentiation and appears related to alterations in E-cadherin in trophoblastic cells.

Abstract 1498: Alpha-Lipoic acid suppresses migration and invasiveness of thyroid cancer cells through inhibition of epithelial-mesenchymal transition .

Abstract Reactive oxygen species (ROS) are recently known as a contributor to tumor progression and metastasis through several mechanisms including induction of epithelial-mesenchymal transition (EMT), invasion, and tumor angiogenesis. In this study, we investigated the role of alpha-Lipoic acid (ALA), a potential antioxidant, on EMT in thyroid cancer cell lines. Human thyroid cancer-derived cell lines, BCPAP (BRAF V600E), HTH83 (HRAS Q61R), CAL62 (KRAS G12R), BHT101 (BRAF V600E), and FTC133 (PTEN null) were treated with ALA, and changes in ROS generation were measured by DCFH-DA. The expression of E-cadherin, vimentin and Twist were determined by immunoblot analysis. Cell migration and invasion were evaluated by scratch assay and by Boyden chamber assay. ALA significantly decreased intracellular ROS generation in most cell lines. The total amount of E-cadherin increased and those of vimentin and Twist decreased after ALA treatment in 4 thyroid cancer cell lines (BCPAP, HTH83, BHT101 and CAL62) in a dose-dependent manner (0.2∼1.0 mM). But, the changes in E-cadherin, vimentin and Twist were opposite in FTC133 cells. The cell migration and invasion ability decreased after treatment with ALA in all cell lines except FTC133 (PTEN null cell). These results suggest that ALA is a potential agent to inhibit EMT resulting in suppression of migration and of invasiveness in thyroid cancer cell lines with RAS or BRAF mutation, probably through reducing cellular amount of Twist. We suggest that it might be caused by antioxidant effects of ALA, but the exact mechanism of action of ALA is not clear yet. ALA could be a novel, potential agent to suppress metastasis of tumors in patients with thyroid cancer. Citation Format: Ji Min Han, Hyun-Jeung Choi, Ji Hye Yim, Won Gu Kim, Tae Yong Kim, Young Kee Shong, Eui Young Kim, Won Bae Kim. Alpha-Lipoic acid suppresses migration and invasiveness of thyroid cancer cells through inhibition of epithelial-mesenchymal transition . [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1498. doi:10.1158/1538-7445.AM2013-1498

Effects of Helicobacter pylori Infection on Gastric Parietal Cells and E-cadherin in Mongolian Gerbils

Atrophic gastritis caused by infection with Helicobacter pylori is characterized by parietal cell loss, which is a main risk factor for gastric cancer. Parietal cells play a crucial role in the regulation of cell lineage maturation and proliferation in the gastric units. Among the classical cadherins, E-cadherin plays an important role not only in epithelial cell-cell connections, but also in the maintenance of epithelial polarity and gastric glandular architecture and regulation of cell proliferation. The aim of this study is to elucidate how parietal cells and E-cadherin are altered in gastritis with Helicobacter pylori infection. We studied the effects of Helicobacter pylori on gastric mucosal E-cadherin 2 weeks after inoculation and investigated the relationship between parietal cell loss and the amount of E-cadherin on parietal cells in Mongolian gerbils. The number of parietal cells and amount of staining of E-cadherin below the isthmus were investigated by immunohistochemistry. It was shown that a reduction in intercellular E-cadherin preceded the disappearance of parietal cells. The gastric glands where parietal cells were lost were replaced by mucus secreting cells without E-cadherin. These results suggest that Helicobacter pylori damaged E-cadherin on parietal cells and caused massive parietal cell loss, leading to the deregulation of gastric morphology.

Anti-apoptotic effect of claudin-1 on TNF-α-induced apoptosis in human breast cancer MCF-7 cells

Accumulating evidence reveals that aberrant expression of claudins manifests in various tumors; however, their biological functions are poorly understood. Here, we report on the elevated expression of claudin-1 in human breast cancer MCF-7 cells under tumor necrosis factor (TNF)-α treatment. Interestingly, the increased expression of claudin-1 contributes to an anti-apoptotic role in TNF-α-induced apoptosis. In line with this, upon TNF-α stimulus, downregulation of claudin-1 by siRNA knockdown results in a significant increase in cleavage of caspase-8 and poly (ADP-ribose) polymerase, a decrease of cyclinD1 expression, and DNA fragmentation. Consistently, TdT-mediated dUTP nick end labeling assay also shows that loss of claudin-1 increases the susceptibility of MCF-7 cells to TNF-α-induced apoptosis. However, there is no obvious effect on the expression of Bax and p53 after the treatment aforementioned. In addition, TNF-α increases the amount of claudin-1 and the cytoplasmic accumulation of β-catenin, while claudin-1 siRNA increases the amount of β-catenin in the cell membrane as well as the amount of E-cadherin in the cytoplasm. In conclusion, our data reveal a novel role of claudin-1 in regulating apoptosis in MCF-7 cells.

Tenascin C Induces Epithelial-Mesenchymal Transition–Like Change Accompanied by SRC Activation and Focal Adhesion Kinase Phosphorylation in Human Breast Cancer Cells

Tenascin C (TNC) is an extracellular matrix glycoprotein up-regulated in solid tumors. Higher TNC expression is shown in invading fronts of breast cancer, which correlates with poorer patient outcome. We examined whether TNC induces epithelial-mesenchymal transition (EMT) in breast cancer. Immunohistochemical analysis of invasive ductal carcinomas showed that TNC deposition was frequent in stroma with scattered cancer cells in peripheral margins of tumors. The addition of TNC to the medium of the MCF-7 breast cancer cells caused EMT-like change and delocalization of E-cadherin and β-catenin from cell-cell contact. Although amounts of E-cadherin and β-catenin were not changed after EMT in total lysates, they were increased in the Triton X-100-soluble fractions, indicating movement from the membrane into the cytosol. In wound healing assay, cells were scattered from wound edges and showed faster migration after TNC treatment. The EMT phenotype was correlated with SRC activation through phosphorylation at Y418 and phosphorylation of focal adhesion kinase (FAK) at Y861 and Y925 of SRC substrate sites. These phosphorylated proteins colocalized with αv integrin-positive adhesion plaques. A neutralizing antibody against αv or a SRC kinase inhibitor blocked EMT. TNC could induce EMT-like change showing loss of intercellular adhesion and enhanced migration in breast cancer cells, associated with FAK phosphorylation by SRC; this may be responsible for the observed promotion of TNC in breast cancer invasion.

Stable Transfection of E-cadherin Gene into Mouse Embryonic Stem Cells and Its Effects on Adhesive Capacity of Differentiated Cells

BACKGROUND: During the embryonic stage, E-cadherin expression plays a critical role in the formation of hepatic tissue. OBJECTIVE: E-cadherin gene was transfected into mouse embryonic stem cells (ESCs) to observe its effects on adhesive capacity of differentiated cells. DESIGN, TIME AND SETTING: A cytological in vitro observation was performed at the Laboratory of Surgery, First Hospital Affiliated to Sun Yat-sen University between December 2007 and December 2008. MATERIALS: BALB/c mice at gestational 13 days, of clean grade, were provided by Laboratory Animal Center, Sun Yat-sen University. BALB/c mouse ESCs were preserved by professor Huang Bing from the Department of Ophthalmology, Sun Yat-sen University. CMV promoter-containing eukaryotic expression plasmid pEGFP-N1 was gifted by doctor Lu Zhi-yue from Medical College, Sun Yat-sen University. METHODS: Total RNA was extracted from BALB/c mouse fresh hepatic tissue and synthesized into cDNA by reverse transcription (RT). The synthesized cDNA was used as a template to perform a polymerase chain reaction (PCR) that amplifies a targeted fragment. Following double enzyme digestion, pEGFP-E-cadherin plasmids were reconstructed and transfected into mouse ESCs. In vitro differentiation of transfected mouse ESCs was performed. AIN OUTCOME MEASURES: Detection of E-cadherin expression in the differentiation system using RT-PCR and immunocytochemistry and observation of adhesive capacity of differentiated cells. RESULTS: E-cadherin gene-transfected ESCs could stably express E-cadherin during differentiational 1-17 days, while non-transfected ESCs expressed a decreasing amount of E-cadherin. The adhesive capacity of differentiated cells that stably expressed E-cadherin was markedly enhanced. Compact cell connection and multi-layer growth state remained at 19 days. While non-transfected ESCs gradually changed from embryoid bodies into noncohesive cell populations. CONCLUSION: Differentiating E-cadherin ESCs exhibit markedly enhanced adhesive capacity and maintain multi-layer growth state.

Increased Internalization of p120-uncoupled E-cadherin and a Requirement for a Dileucine Motif in the Cytoplasmic Domain for Endocytosis of the Protein

E-cadherin is a member of the cadherin family of Ca2+-dependent cell-cell adhesion molecules. E-cadherin associates with beta-catenin at the membrane-distal region of its cytosolic domain and with p120 at the membrane-proximal region of its cytoplasmic domain. It has been shown that a pool of cell surface E-cadherin is constitutively internalized and recycled back to the surface. Further, p120 knockdown by small interference RNA resulted in dose-dependent elimination of cell surface E-cadherin. Consistent with these observations, we found that selective uncoupling of p120 from E-cadherin by introduction of amino acid substitutions in the p120-binding site increased the level of E-cadherin endocytosis. The increased endocytosis was clathrin-dependent, because it was blocked by expression of a dominant-negative form of dynamin or by hypertonic shock. A dileucine motif in the juxtamembrane cytoplasmic domain is required for E-cadherin endocytosis, because substitution of these residues to alanine resulted in impaired internalization of the protein. The alanine substitutions in the p120-uncoupled construct reduced endocytosis of the protein, indicating that this motif was dominant to p120 binding in the control of E-cadherin endocytosis. Therefore, these results are consistent with the idea that p120 regulates E-cadherin endocytosis by masking the dileucine motif and preventing interactions with adaptor proteins required for internalization.

PH domain-mediated membrane targeting of Asef

The APC-associated guanine nucleotide exchange factor (GEF) Asef regulates cell morphology and migration. Asef contains a pleckstrin homology (PH) domain in addition to Dbl homology (DH), APC-binding (ABR), and Src homology 3 (SH3) domains. Here we show that the PH domain of Asef binds to phosphatidylinositol 3,4,5-trisphophate [PtdIns(3,4,5)P3] and targets Asef to the cell–cell adhesion sites in MDCK II cells. Furthermore, we demonstrate that overexpression of Asef in MDCK II cells results in increases in the amounts of E-cadherin and the actin filaments at the sites of cell–cell contact. These results suggest that Asef is targeted via its PH domain to the cell–cell adhesion sites and is involved in the regulation of cell adhesion.

Simulated weightlessness changes the cytoskeleton and extracellular matrix proteins in papillary thyroid carcinoma cells

Studies of astronauts, experimental animals, and cells have shown that, after spaceflights, the function of the thyroid is altered by low-gravity conditions. The objective of this study was to investigate the cytoskeleton and extracellular matrix (ECM) protein synthesis of papillary thyroid cancer cells grown under zero g. We investigated alterations of ONCO-DG 1 cells exposed to simulated microgravity on a three-dimensional random-positioning machine (clinostat) for 30 min, 24 h, 48 h, 72 h, and 120 h (n=6, each group). ONCO-DG 1 cells grown under microgravity exhibited early alterations of the cytoskeleton and formed multicellular spheroids. The cytoskeleton was disintegrated, and nuclei showed morphological signs of apoptosis after 30 min. At this time, vimentin was increased. Vimentin and cytokeratin were highly disorganized, and microtubules (alpha-tubulin) did not display their typical radial array. After 48 h, the cytoskeletal changes were nearly reversed. The formation of multicellular spheroids continued. In parallel, the accumulation of ECM components, such as collagen types I and III, fibronectin, chondroitin sulfate, osteopontin, and CD44, increased. The levels of both transforming growth factor beta-1 (TGF-beta(1)) and TGF-beta receptor type II proteins were elevated from 24 h until 120 h clinorotation. Gene expression of TGF-beta(1) was clearly enhanced during culture under zero g. The amount of E-cadherin was enhanced time-dependently. We suggest that simulated weightlessness rapidly affects the cytoskeleton of papillary thyroid carcinoma cells and increases the amount of ECM proteins in a time-dependent manner.

Effects of cadmium on E-cadherin and VE-cadherin in mouse lung

Exposure to Cd 2+ via inhalation or intratracheal instillation results in pulmonary edema, which is followed by the influx of leukocytes, the proliferation of type II pneumocytes and eventual scarring and fibrotic changes. While the general toxic effects of Cd 2+ in the lung have been well characterized, the specific molecular mechanisms underlying these effects have yet to be elucidated. Previously we have shown that Cd 2+ can disrupt the adhering junctions between various types of epithelial and endothelial cells in culture, most likely by perturbing the function of the Ca 2+ dependent cell adhesion molecules E-cadherin and VE-cadherin respectively. The objectives of this study were to determine whether respiratory exposure to Cd 2+ can alter the localization of E-cadherin and VE-cadherin in the lung, and to determine whether this effect may play a role in the acute pneumotoxic response to Cd 2+. Male CF-1 mice were exposed to CdCl 2 (0, 16.25, 32.5, 65 or 130 nmoles in 50 μl saline) via intratracheal instillation. After 24 hours, the lungs were removed and either subjected to bronchoalveolar lavage or analyzed for histopathologic changes. The results showed that Cd 2+ caused an increase in lung weight and in the protein content of the lavage fluid. These effects were accompanied by a pronounced decrease in the amount of E-cadherin in epithelial cells of the alveoli and small bronchioles and of VE-cadherin in vascular endothelial cells. Assessment of cell membrane integrity with ethidium homodimer-1 showed no evidence of severe injury or death in alveolar epithelial cells. These findings suggest that E-cadherin and VE-cadherin may be important early targets of Cd 2+ toxicity in the lung.

E-cadherin-mediated cell contact prevents apoptosis of spontaneously immortalized granulosa cells by regulating Akt kinase activity.

The present studies were designed to determine the role that homophilic E-cadherin binding plays in preventing apoptosis of spontaneously immortalized granulosa cells (SIGCs). Although the levels of E-cadherin were similar to serum control levels, the amount of E-cadherin at the plasma membrane was dramatically reduced by 5 h after serum withdrawal. To determine whether disrupting homophilic E-cadherin binding leads to apoptosis, SIGCs were cultured in serum in the presence of either EGTA or an E-cadherin antibody. Treatment with either EGTA, which disrupts all calcium-dependent contacts, or E-cadherin antibody, induced apoptosis. Exposure to EGTA reduced MEK and Akt kinase activity, whereas E-cadherin antibody only attenuated Akt kinase activity. Because Akt kinase controls caspase-3 activity, an important activator of apoptosis, caspase-3 activity was monitored. Caspase-3 activity increased after serum depletion, or EGTA or E-cadherin antibody treatment. Time-series analysis of caspase-3 activity within single cells revealed that during apoptosis cell contact was disrupted then caspase-3 activity was detected. Finally, the caspase inhibitor, Z-VAD-FMK, blocked apoptosis. These data taken together are consistent with the concept that E-cadherin-mediated cell contact, either directly or indirectly, promotes Akt kinase activity, which in turn, inhibits caspase-3 activation and thereby maintains SIGC viability.

IQGAP1 and Calmodulin Modulate E-cadherin Function

Ca(2+)-dependent cell-cell adhesion is mediated by the cadherin family of transmembrane proteins. Adhesion is achieved by homophilic interaction of the extracellular domains of cadherins on adjacent cells, with the cytoplasmic regions serving to couple the complex to the cytoskeleton. IQGAP1, a novel RasGAP-related protein that interacts with the cytoskeleton, binds to actin, members of the Rho family, and E-cadherin. Calmodulin binds to IQGAP1 and regulates its association with Cdc42 and actin. Here we demonstrate competition between calmodulin and E-cadherin for binding to IQGAP1 both in vitro and in a normal cellular milieu. Immunocytochemical analysis in MCF-7 (E-cadherin positive) and MDA-MB-231 (E-cadherin negative) epithelial cells revealed that E-cadherin is required for accumulation of IQGAP1 at cell-cell junctions. The cell-permeable calmodulin antagonist CGS9343B significantly increased IQGAP1 at areas of MCF-7 cell-cell contact, with a concomitant decrease in the amount of E-cadherin at cell-cell junctions. Analysis of E-cadherin function revealed that CGS9343B significantly decreased homophilic E-cadherin adhesion. On the basis of these data, we propose that disruption of the binding of calmodulin to IQGAP1 enhances the association of IQGAP1 with components of the cadherin-catenin complex at cell-cell junctions, resulting in impaired E-cadherin function.

P120-catenin expression in human colorectal cancer.

Recent data suggest that p120-catenin plays a role in the regulation of functionality of E-cadherin, a protein essential for the establishment and maintenance of cell-cell contacts. Since dysfunction of intercellular adhesiveness is an alteration frequently observed in colon cancer we have studied the expression and distribution of p120-catenin in human colorectal tumors. In normal colon, p120-catenin was observed in the crypt and surface epithelium; the cells showed reactivity both in the membrane and in the cytosol. Thirteen primary tumors were examined for p120-catenin expression: they were graded as uniformly positives (+) (4); heterogeneous (+/-) (6), with a diminished expression, detected mainly in the cytosol; and negatives (-) (3). Although the number of tumors was low, the reduction in p120-catenin correlated with a larger size of the tumors (p = 0.038). Association of p120-catenin to the cytoskeleton was also determined in 5 tumors by detergent extraction and Western blot; this analysis shows that lack of reactivity in the membrane was accompanied by absence of p120-catenin in the cytoskeleton-associated fraction. Analysis of E-cadherin was performed in order to compare the distribution of this protein and p120-catenin. Although no complete correlation was found between the expression of both proteins (p = 0.077), our results showed that alterations in the level or distribution of p120-catenin were accompanied by lack of E-cadherin reactivity in the membrane, whereas absence of p120-catenin in the cytoskeleton fraction was associated with important decreases in the amount of E-cadherin in this same fraction. These results show that alterations in p120-catenin levels are a common event in colorectal tumors, and suggest that the distribution of this protein and E-cadherin is coordinately regulated.

P120-catenin expression in human colorectal cancer

Recent data suggest that p120-catenin plays a role in the regulation of functionality of E-cadherin, a protein essential for the establishment and maintenance of cell-cell contacts. Since dysfunction of intercellular adhesiveness is an alteration frequently observed in colon cancer we have studied the expression and distribution of p120-catenin in human colorectal tumors. In normal colon, p120-catenin was observed in the crypt and surface epithelium; the cells showed reactivity both in the membrane and in the cytosol. Thirteen primary tumors were examined for p120-catenin expression: they were graded as uniformly positives (+) (4); heterogeneous (+/-) (6), with a diminished expression, detected mainly in the cytosol; and negatives (-) (3). Although the number of tumors was low, the reduction in p120-catenin correlated with a larger size of the tumors (p = 0.038). Association of p120-catenin to the cytoskeleton was also determined in 5 tumors by detergent extraction and Western blot; this analysis shows that lack of reactivity in the membrane was accompanied by absence of p120-catenin in the cytoskeleton-associated fraction. Analysis of E-cadherin was performed in order to compare the distribution of this protein and p120-catenin. Although no complete correlation was found between the expression of both proteins (p = 0.077), our results showed that alterations in the level or distribution of p120-catenin were accompanied by lack of E-cadherin reactivity in the membrane, whereas absence of p120-catenin in the cytoskeleton fraction was associated with important decreases in the amount of E-cadherin in this same fraction. These results show that alterations in p120-catenin levels are a common event in colorectal tumors, and suggest that the distribution of this protein and E-cadherin is coordinately regulated.

Human Langerhans Cells Express E-Cadherin

Murine Langerhans cells (LC) synthesize and express E-cadherin, a Ca(++)-dependent homophilic cell adhesion molecule that mediates LC-keratinocyte (KC) binding in vitro. In vivo, E-cadherin expression by LC may promote localization and persistence of LC within the epidermis through LC-KC adhesion. In addition, changes in LC E-cadherin expression or affinity may be an important factor in the egress of LC from the epidermis after exposure to antigen. The aim of the present study was to determine if human LC also express E-cadherin. Suction blister roofs were obtained from normal volunteers and epidermal cell (EC) suspensions were prepared by limited trypsinization in the presence of 1 mM Ca++. EC were then incubated with antibodies to E-cadherin and CD1a or HLA-DR, and examined by two-color analytical flow cytometry or immunofluorescence microscopy. Most (82.9% +/- 7.4% [mean +/- SD], range 67-89%, n = 7) freshly prepared human LC expressed E-cadherin, as did the majority of KC. The amount of E-cadherin (as determined by mean fluorescence intensity) expressed by LC and KC was similar. Trypsin/EDTA treatment of freshly prepared EC abrogated expression of E-cadherin by LC and KC, whereas E-cadherin was not degraded by trypsin in the presence of Ca++. LC expressed lower levels of E-cadherin after 3 d in culture. Thus, human LC, like murine LC, express the homophilic adhesion molecule E-cadherin, which may be important in establishing and maintaining interactions between LC and KC in mammalian epidermis.