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PubMed2003

Naturally occurring antibodies to epithelial cell adhesion molecule (EpCAM).

Epithelial cell adhesion molecule (Ep-CAM) is an epithelial tumor-associated antigen that is expressed by a number of normal tissues and has been used as a target in many immunotherapy studies. The purpose of this study was to determine the incidence of serum anti-EpCAM IgG (immunoglobulin G) antibodies in colon cancer and tumor-free patients and to assess the tumor protective value of anti-EpCAM antibodies. One third of both the cancer (16/48) and the control (9/27) patients had detectable antibodies. Although the mean antibody concentration was higher in cancer patients (0.048 +/- 0.120 U) than in controls (0.038 +/- 0.064 U) the difference was not statistically significant. Western blot analysis revealed reactivity to multiple HT29 cell proteins including a 40-kDa protein (presumed to be Ep-CAM). Monoclonal anti-EpCAM 323/A3 antibody did not have a tumor-protective effect in murine Ep-CAM expressing colocarcinoma. We conclude that Ep-CAM is immunogenic not only for cancer patients, but also for tumor-free individuals.

Adenocarcinoma↗
PubMed2005

Expression of epithelial cell adhesion molecule (EpCam) in renal epithelial tumors.

EpCam is an epithelial adhesion molecule expressed in a broad range of carcinomas. Clinical trials with specific humanized anti-EpCam antibodies have shown promising results and have been inaugurated in renal cell carcinoma (RCC) therapy. To study the EpCam expression profile, primary renal cell neoplasms as well as corresponding metastases were evaluated by immunohistochemistry in tissue microarrays. EpCam expression in oncocytomas and chromophobe RCCs was determined on conventional large sections. Moderate or strong EpCam expression was found in eighteen percent of clear cell (n=147), 75% of chromophobe (n=12), and 55% of papillary RCCs (n=20), but not in oncocytomas (n=3). On large sections, 90% of chromophobe RCCs (n=20) showed a strong and homogeneous positivity, whereas oncocytomas (n=15) revealed EpCam positivity in single tumor cells or small clusters. Fourteen percent of RCC metastases (n=97) showed EpCam expression. Patients with EpCam expressing clear cell RCC showed a trend toward a better prognosis in a Cox regression analysis including stage, grade, and necrosis. The data suggest EpCam as a potential therapeutic target in a subset of patients with RCC. In addition, expression patterns of EpCam could become a helpful tool in the discrimination of chromophobe RCC and oncocytoma.

Adult↗
PubMedDate not supplied

Cloning and characterisation of a 1.1 kb fragment of the carcinoma-associated epithelial cell adhesion molecule promoter.

The epithelial cell adhesion molecule (EpCAM) is a transmembrane protein associated with a variety of carcinomas, where EpCAM is often strongly up-regulated or, as in the case of squamous cell carcinomas, de novo expressed. The molecular mechanisms underlying the transcriptional regulation of EpCAM are poorly understood. So far, a 570 bp fragment has been cloned and shown to have specific transcriptional activity, which was negatively-regulated upon the induction of the transcription factor NF-kappa B. In the present study we have cloned a 1100 bp fragment of the EpCAM promoter containing the 570 bp fragment and additional 550 bp upstream. We demonstrate that both fragments have strong synergistic effects with respect to transcriptional activity in EpCAM-positive cells. Furthermore, the 1100 bp fragment was likewise negatively-regulated upon TNF alpha and IFN alpha treatment, thus retaining silencer sequences.

Antigens, Neoplasm↗
PubMed2005

Expression of epithelial-cell adhesion molecule (Ep-CAM) in small cell lung cancer as defined by monoclonal antibodies 17-1A and BerEP4.

Small cell lung cancer (SCLC) comprises 15-20% of all lung cancer. Despite high initial response to chemotherapy chemoresistance at relapse leads to a less than 5% five-year survival rate. Adjuvant treatment with monoclonal antibodies (Mabs) against SCLC antigens may offer a therapeutic option. Mab 17-1A directed against the epithelial-cell adhesion molecule (Ep-CAM) has been extensively tested for therapy in patients with colorectal carcinoma. Expression of Ep-CAM in SCLC has been earlier described. However, reactivity of Mab 17-1A and another Ep-CAM-binding Mab BerEP4 has not yet been described for SCLC. Using immunohistology first with BerEP4 and confirmatory with 17-1A a homogenous and strong expression of Ep-CAM was seen in all SCLC specimens tested (n = 10). For comparison, heterogenous expression was seen in the non-SCLC tumors tested (n = 15). These findings strongly suggest that Mab 17-1A can be useful for adjuvant immunotherapy in patients with SCLC. For detection of Ep-CAM in tumor tissue in patients that might be considered for immunotherapy with Mab 17-1A, Mab BerEP4 appears to be preferred.

Adenocarcinoma, Bronchiolo-Alveolar↗
PubMed2001

Tumor necrosis factor alpha negatively regulates the expression of the carcinoma-associated antigen epithelial cell adhesion molecule.

BACKGROUND: The epithelial cell adhesion molecule (EpCAM) is a homophilic and Ca2+ independent adhesion molecule that is expressed de novo in squamous cell carcinoma (SCC) but is absent in the majority of healthy squamous epithelia. EpCAM expression correlates with cell proliferation and dedifferentiation along with a progression in tumorigenicity. To date, nothing is known about the molecular mechanisms responsible for the regulation of the EpCAM gene. METHODS: The authors analyzed the regulation of a fragment of the EpCAM promoter. RESULTS: The analyzed fragment has significant activity in EpCAM positive cells, and it is regulated negatively by tumor necrosis factor alpha (TNFalpha). This negative regulation results in diminished mRNA expression and in the down-regulation of EpCAM protein at the cell surface in SCC cells. Both effects can be mimicked by the treatment of cells with the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA). TNFalpha-induced inhibition of the EpCAM expression is mediated by TNF receptor 1 through the TNF receptor-associated death domain protein (TRADD) and by the activation of nuclear factor kappaB (NF-kappaB), and it can be blocked by dominant-negative variants of TRADD and the NF-kappaB inhibitor, IkappaB. The authors provide further evidence that NF-kappaB represses EpCAM expression by competing for the transcriptional coactivator p300/CREB binding protein (p300/CBP). CONCLUSIONS: The current results provide the first insights into the regulation of EpCAM expression, which is regulated negatively by TNFalpha and TPA through the activation of NF-kappaB. The repression may rely on the competition of NF-kappaB for p300/CBP histone acetyl transferase activity, because the overexpression of p300 reverts TNFalpha effects.

Antigens, Neoplasm↗
PubMed2006

Overexpression of epithelial cell adhesion molecule (Ep-CAM) is an independent prognostic marker for reduced survival of patients with epithelial ovarian cancer.

OBJECTIVE: Currently available clinical and molecular factors provide still an insufficient prognostic and predictive assessment for patients with epithelial ovarian cancer (EOC). To identify a potential molecular target and prognostic/predictive factor for EOC, we investigated in a retrospective study the prognostic value of Ep-CAM overexpression in EOC. METHODS: We assessed by immunohistochemistry the expression of the Ep-CAM antigen on tissue microarrays containing paraffin-embedded tissue samples of 199 patients with documented EOC. Patients were operated for ovarian cancer in the period between June 1980 and January 2000. RESULTS: We observed a rate of Ep-CAM overexpression of 68.8%. Ep-CAM overexpression was significantly related to a decreased overall survival (P = 0.036). The prognostic power of Ep-CAM overexpression was particularly strong in patients with stage III and IV disease. In fact, in this subgroup, median overall survival was twofold higher in patients without as compared to patients with Ep-CAM overexpression (46 vs. 23 months, P < 0.01). Univariate analysis revealed a correlation with histologic grade. We observed a significantly higher rate of Ep-CAM overexpression (83.5%) in grade 3 tumors. Histologic subtypes associated with a higher rate of Ep-CAM overexpression were serous carcinoma, squamous cell carcinoma, undifferentiated carcinoma, clear cell carcinoma, and endometrioid carcinoma. Cox regression analysis showed Ep-CAM overexpression to be an independent prognostic marker (P = 0.037, RR = 1.64). CONCLUSIONS: This retrospective analysis demonstrates for the first time an independent prognostic value of Ep-CAM overexpression in patients with EOC. Ovarian cancer patients with Ep-CAM overexpressing tumors are frequent and would qualify for treatment with Ep-CAM-specific immunotherapeutic approaches.

Adult↗
PubMed2005

Expression of epithelial cell adhesion molecule in carcinoma cells present in blood and primary and metastatic tumors.

The epithelial cell adhesion molecule (EpCAM) is involved in homophilic cell-cell adhesion in normal epithelia and is frequently overexpressed in primary and metastatic adenocarcinomas. It has been postulated that during detachment and dissemination of tumor cells, EpCAM may be down-regulated. Circulating tumor cells (CTC) may demonstrate this phenomenon as they have successfully escaped their local microenvironment and entered the circulation. EpCAM expression of CTC was compared to tumor cells in paraffin-embedded tissue arrays containing various benign diseases and carcinomas. EpCAM expression on CTC was determined by flow cytometry (FCM) and by immunohistochemistry (IHC) in paraffin-embedded tissue. To permit comparison of FCM results to those derived by IHC, EpCAM was quantified on cancer cell lines by FCM and then paraffin-embedded cell-blocks of these lines were used as staining guides for IHC analysis of tissue arrays. By IHC, 97% (384/397) of solid tissues analyzed had detectable EpCAM, with 72% of tissues showing antigen expression levels of > or =400,000 EpCAM molecules per cell. FCM analysis of CTC from 100 metastatic carcinoma patients with > or =2 CTC/90 microl blood showed EpCAM expression ranging from 9,900 to 246,000 (mean 49,700) antigens per cell. EpCAM expression was approximately 10-fold lower on CTC as compared to primary and metastatic tissues, suggesting that EpCAM expression is transient and dependent upon the local micro-environment. This supports the hypothesis that this adhesion molecule is down-regulated on carcinoma cells in the circulation.

Animals↗
PubMed2003

The epithelial cell adhesion molecule (Ep-CAM) as a morphoregulatory molecule is a tool in surgical pathology.

Cell adhesion receptors (CAMs) are actively involved in regulating various cell processes, including growth, differentiation, and cell death. Therefore, CAMs represent a large group of morphoregulating molecules, mediating cross-talk between cells and of cells with their environment. From this perspective, CAMs do contribute to cells and tissue organization, and in diseased tissue, to the disease development and biological characteristics. Therefore, observed changes in expression patterns of adhesion molecules may contribute to establish a diagnosis. A distinct shift in expression patterns in neoplastic epithelium has been described, for example for cadherins, integrins, and CD44. A relatively novel cell CAM, Ep-CAM, was first reported to be a pan-carcinoma antigen, although it is rather a marker of epithelial lineage. Several antibodies directed to Ep-CAM have been generated, and many epithelial tissues and their neoplastic appendages have been studied. This article outlines the results of these studies. Based on the results of these studies, we conclude that Ep-CAM immunohistochemistry can be a useful tool in the diagnosis of disturbed epithelial tissues.

Antigens, Neoplasm↗
PubMed1999

High thermal stability is essential for tumor targeting of antibody fragments: engineering of a humanized anti-epithelial glycoprotein-2 (epithelial cell adhesion molecule) single-chain Fv fragment.

The epithelial glycoprotein-2 is abundantly expressed on many solid tumors and is a suitable target for antibody-based therapy. In the present study, an antiepithelial glycoprotein-2 single-chain Fv (scFv) was derived from the hybridoma MOC31 by phage display. Despite its high affinity (KD = 3.9 x 10(-9) M), however, this antibody fragment failed to significantly enrich at lung tumor xenografts in mice, mostly because of its insufficient thermal stability. To overcome this limitation, the antigen-binding residues of the MOC31 scFv fragment were grafted onto the framework of the highly stable and well-folding anti-c-erbB2 scFv 4D5. Further modification of the resulting 4D5 MOC-A, which was performed by transferring eight additional residues of the heavy chain variable domain core of the parent MOC31 antibody, produced 4D5 MOC-B, resulting in increased serum stability at 37 degrees C and also significantly improved expression behavior while retaining the antigen specificity and affinity of the parent MOC31 scFv. In mice, the scFv 4D5 MOC-B, which was radiolabeled with 99mtechnetium using a new histidine-tag specific labeling method (Waibel et al., Nature Biotechnol., 17: 897-901, 1999), showed favorable blood clearance and efficient enriches at lung tumor xenografts, with a tumor:blood ratio of 5.25 and a total dose of 1.47% injected dose per gram after 24 h. Biophysical properties such as high thermal stability are thus decisive for whether these molecules are useful in vivo, and our approach may provide a general strategy to solve this problem. This is also the first report of using a humanized anti-EGP-2 scFv in vivo for targeting solid tumors, which is a promising targeting moiety for the diagnostics and therapy of EGP-2-positive tumors in patients.

Amino Acid Sequence↗
PubMed1997

Epithelial cell adhesion molecule (Ep-CAM) modulates cell-cell interactions mediated by classic cadherins.

The contribution of noncadherin-type, Ca2+-independent cell-cell adhesion molecules to the organization of epithelial tissues is, as yet, unclear. A homophilic, epithelial Ca2+-independent adhesion molecule (Ep-CAM) is expressed in most epithelia, benign or malignant proliferative lesions, or during embryogenesis. Here we demonstrate that ectopic Ep-CAM, when expressed in cells interconnected by classic cadherins (E- or N-cadherin), induces segregation of the transfectants from the parental cell type in coaggregation assays and in cultured mixed aggregates, respectively. In the latter assay, Ep-CAM-positive transfectants behave like cells with a decreased strength of cell-cell adhesion as compared to the parental cells. Using transfectants with an inducible Ep-CAM-cDNA construct, we demonstrate that increasing expression of Ep-CAM in cadherin-positive cells leads to the gradual abrogation of adherens junctions. Overexpression of Ep-CAM has no influence on the total amount of cellular cadherin, but affects the interaction of cadherins with the cytoskeleton since a substantial decrease in the detergent-insoluble fraction of cadherin molecules was observed. Similarly, the detergent-insoluble fractions of alpha- and beta-catenins decreased in cells overexpressing Ep-CAM. While the total beta-catenin content remains unchanged, a reduction in total cellular alpha-catenin is observed as Ep-CAM expression increases. As the cadherin-mediated cell-cell adhesions diminish, Ep-CAM-mediated intercellular connections become predominant. An adhesion-defective mutant of Ep-CAM lacking the cytoplasmic domain has no effect on the cadherin-mediated cell-cell adhesions. The ability of Ep-CAM to modulate the cadherin-mediated cell-cell interactions, as demonstrated in the present study, suggests a role for this molecule in development of the proliferative, and probably malignant, phenotype of epithelial cells, since an increase of Ep-CAM expression was observed in vivo in association with hyperplastic and malignant proliferation of epithelial cells.

Animals↗
PubMed1999

Abnormal thymic expression of epithelial cell adhesion molecule (EP-CAM) in New Zealand Black (NZB) mice.

New Zealand Black (NZB) mice have been well documented to have a variety of thymic epithelial cell microenvironmental abnormalities, including disruption of corticoepithelial cell networks and medullary cell clusters. These abnormalities of the thymic stromal network are particularly important because similar observations have been noted in other models of murine lupus. Thymic epithelial cells, a key component of the microenvironment, play an important role in selection of the mature T cell receptor repertoire. Recently, a homotypic calcium-independent human and murine epithelial cell adhesion molecule, Ep-CAM, has been described which is located at the thymocyto-cortical cell junction. The function of Ep-CAM is still unclear but its unique location within the thymus suggests that it is critical in the process of providing maturation signals. Consequently, we examined the thymic expression of Ep-CAM in a series of autoimmune prone mice by thymic distribution of Ep-CAM in NZB, NZW, NZB/W, BXSB-Yaa, MRL- lpr/lpr, C3H- gld/gld and the control strains BALB/c, C57BL6, C3H and MRL(+/+), by immunohistology and flow cytometry. Interestingly, NZB mice are similar to control mice from day 4 to 2 weeks of age, having a very low expression of Ep-CAM at the thymocyto-cortical junction. In control strains, there is a marked increased in expression of Ep-CAM beginning at 5 weeks of age. In contrast, NZB mice fail to show significant expression of Ep-CAM even well into adulthood. This abnormality of NZB mice was also noted in NZB/W F1 and BXSB mice, but not MRL- lpr/lpr or C3H- gld/gld mice. Given the potential importance of Ep-CAM in thymic selection, this study provides important evidence that a defective stromal microenvironment is likely to be of etiological significance in the susceptibility of NZB to autoimmune disease.

Animals↗
PubMed2007

DNA methylation and histone modification regulate silencing of epithelial cell adhesion molecule for tumor invasion and progression.

Epithelial cell adhesion molecule (Ep-CAM) is believed to have a critical role in carcinogenesis and cell proliferation. However, the association of Ep-CAM with cancer invasion and progression is less clear. We found that Ep-CAM was highly expressed on low-invasive cells compared with highly invasive cells. Forced expression of Ep-CAM decreased cancer invasiveness, and silencing Ep-CAM expression elevated cancer invasiveness. Ep-CAM expression was associated with promoter methylation. Treatment with a demethylating agent, and/or the histone deacetylase inhibitor reactivated Ep-CAM expression in Ep-CAM-negative cells and inhibited cancer invasiveness. Using a promoter-reporter construct, we demonstrated methylation of the promoter fragment drive Ep-CAM-silenced transcription. Additionally, silenced Ep-CAM gene in cancer cells was enriched for hypermethylated histone 3 lysine 9. When unmethylated and active, this promoter was associated with acetylated histone 3 lysine 9. Furthermore, we observed an increased association of Ep-CAM promoter with repression components as tumor invasiveness increased. In cancer tissues, Ep-CAM expression significantly correlated with tumor progression and associated with promoter methylation. Our data support the idea that modulation of Ep-CAM plays a pivotal role in tumor invasion and progression. Moreover, aberrant DNA methylation of Ep-CAM is implicated in enhancing invasive/metastatic proclivity of tumors.

Antigens, Neoplasm↗
PubMed2003

Identification of epithelial cell adhesion molecule autoantibody in patients with ovarian cancer.

The epithelial cell adhesion molecule (Ep-CAM) exhibited an ovarian cancer:normal human ovarian surface epithelium ratio of 444. For validation studies, real-time quantitative PCR analysis and immunohistochemistry were performed in normal and malignant ovarian epithelial cell lines and tissues. To evaluate the potential of the Ep-CAM autoantibody as a tumor marker, we examined the amount of Ep-CAM autoantibody in serum samples obtained from ovarian cancer patients and normal controls by an ELISA. Real-time quantitative PCR analysis revealed significant overexpression of Ep-CAM mRNA in cancer cell lines (P < 0.001) and microdissected cancer tissues (P < 0.05), compared with that in cultured normal human ovarian surface epithelium and microdissected germinal epithelium, respectively. Immunolocalization of the Ep-CAM autoantibody showed that the sera of ovarian cancer patients expressed higher levels of Ep-CAM autoantibody than benign tumor patients and normal controls (P < 0.05). The levels of Ep-CAM autoantibody found were as follows: 0.132 in 52 patients with ovarian cancer, 0.098 in 26 cases with benign gynecologic disease, and 0.090 in 26 normal women. This investigation has shown that the Ep-CAM autoantibody was found to be associated with ovarian cancer and suggested that future research assessing its clinical usefulness would be worthwhile.

Antigens, Neoplasm↗
PubMed2004

Epithelial cell adhesion molecule (KSA) expression: pathobiology and its role as an independent predictor of survival in renal cell carcinoma.

PURPOSE: Epithelial cell adhesion molecule (EpCAM) is a widely expressed adhesion molecule in epithelial cancers. The purpose of this study is to determine the protein expression patterns of EpCAM in renal cell carcinoma (RCC) using tissue arrays linked to a clinicopathological database to evaluate both its predictive power in patient stratification and its suitability as a potential target for immunotherapeutic treatment strategies. EXPERIMENTAL DESIGN: The University of California, Los Angeles kidney cancer tissue microarray contains specimens from 417 patients treated with nephrectomy. EpCAM protein expression in tumors and matched morphologically normal renal tissues was evaluated using anti-EpCAM immunohistochemistry. The resultant expression reactivity was correlated with clinicopathological variables. RESULTS: EpCAM is consistently expressed in the distal nephron on normal renal epithelium. Clear cell RCCs show minimal and infrequent EpCAM expression, whereas chromophobe and collecting duct RCCs both demonstrate intense and frequent expression. Of 318 clear cell carcinomas used in the analysis, 10% were EpCAM positive in > or = 50% of cells, and 8% of patients would be considered candidates for EpCAM-based therapy, based on high expression [> or = moderate intensity and frequent (> or = 50%) expression] and the need for systemic treatment. EpCAM expression was an independent prognostic factor for improved disease-specific survival, with a multivariate hazard ratio of 0.63 (P = 0.017; 95% confidence interval, 0.43-0.92). CONCLUSIONS: EpCAM is a novel prognostic molecular marker in RCC patients, and its positive expression is an independent predictor associated with improved survival. However, high expression in morphologically normal renal tissues and minimal or absent expression in clear cell carcinomas will likely limit the utility of this epithelial marker in targeted treatments of this most common RCC type.

Adenocarcinoma, Clear Cell↗
PubMed1997

Identification of potential HLA-A *0201 restricted CTL epitopes derived from the epithelial cell adhesion molecule (Ep-CAM) and the carcinoembryonic antigen (CEA).

The altered expression pattern of the Epithelial Cell Adhesion Molecule (Ep-CAM) and the Carcinoembryonic Antigen (CEA) on tumor cells of epithelial origin as compared to normal epithelia may permit T cells to preferentially recognize and lyse these tumor cells. The binding affinity for human leucocyte antigen A2.1 (HLA-A*0201) and the capacity to form stable peptide-major histocompatibility complex (MHC) interactions with this molecule were tested for 410 Ep-CAM-derived sequences, including an overlapping set of 9 amino-acid-long peptides, and 73 CEA-derived peptides fulfilling the HLA-A*0201 motif. Peptides with a high binding affinity and a low peptide-MHC dissociation rate were subsequently tested for their immunogenicity in HLA-A*0201Kb transgenic mice. One Ep-CAM-derived peptide and 1 CEA-derived peptide were able to reproducibly induce peptide-specific cytotoxic T cells (CTL) in these mice. This indicates that EpCAM and CEA are potential target antigens for CTL-mediated immunotherapy of epithelial cancers.

Animals↗
PubMed2003

Tumor-specific glycosylation of the carcinoma-associated epithelial cell adhesion molecule EpCAM in head and neck carcinomas.

The tissue-specific glycosylation of the carcinoma (CA)-associated antigen epithelial cell adhesion molecule (EpCAM) was studied in 60 patients suffering from head and neck CAs, and 26 pairs of autologous healthy thyroid and CA biopsies. EpCAM was glycosylated in all tumor samples in which its expression was detectable (73%). Additionally, in 80.7% of patients, tumor-derived EpCAM was heavily glycosylated while EpCAM derived from autologous thyroid was not (76.2%) or weakly (23.8%). Four cases showed a similar glycosylation pattern (15.3%) and one case displayed a reverse pattern (3.8%). Additionally, the expression and glycosylation of EpCAM were assessed in tumor adjacent and distant tissue. EpCAM was glycosylated in tumor-adjacent while it was not or only weakly expressed in tumor distant tissue where it was unglycosylated. Thus, EpCAM is differentially glycosylated in healthy tissue and tumor cells of the head and neck area.

Adult↗
PubMed2005

Quality of recombinant protein determines the amount of autoreactivity detected against the tumor-associated epithelial cell adhesion molecule antigen: low frequency of antibodies against the natural protein.

The human epithelial cell adhesion molecule (EpCAM) is expressed on normal epithelial cells and is overexpressed in most carcinomas. EpCAM-targeted immunotherapy has been tried in several clinical studies. High titers of autoantibodies against EpCAM have been reported by different authors. We have generated large amounts of purified protein in S2 Drosophila cells (S2-EpCAM) with a purity of >96%. In contrast, the protein produced in baculovirus-dependent systems (baculo-EpCAM) that has been used in previous studies shows a purity of 79%. (1)H nuclear magnetic resonance spectrum of S2-EpCAM is typical of folded protein, whereas the baculo-EpCAM sample shows a spectrum corresponding to a partially unfolded protein. Using S2-EpCAM, denatured S2-EpCAM, and baculo-EpCAM, we measured EpCAM Abs of different isotypes in the serum of healthy controls and cancer patients. We found Ab titers against EpCAM in a much lower percentage of sera as published previously, and support the hypothesis that Ab reactivity in some published studies might be due to reactivity against denatured protein, to contaminating proteins in the baculovirus preparations, and to reactivity with BSA. Tetanus toxoid-reactive IgG Abs are present in 1000-fold higher titers compared with EpCAM-reactive Abs. Only IgA Abs were found in higher proportions and in higher concentrations than tetanus toxoid-specific Abs. Our study shows that EpCAM only rarely induces autoantibodies against native protein and emphasizes the importance of using extremely purified Ag preparations when evaluating Abs against tumor-associated Ags.

Animals↗