EpCAM is overexpressed in breast cancer and is a potential target for breast cancer gene therapy

Differential detection of tumor cells using a combination of cell rolling, multivalent binding, and multiple antibodies

Effective quantification and in situ identification of circulating tumor cells (CTCs) in blood are still elusive because of the extreme rarity and heterogeneity of the cells. In our previous studies, we developed a novel platform that captures tumor cells at significantly improved efficiency in vitro using a unique biomimetic combination of two physiological processes: E-selectin-induced cell rolling and poly(amidoamine) (PAMAM) dendrimer-mediated strong multivalent binding. Herein, we have engineered a novel multifunctional surface, on the basis of the biomimetic cell capture, through optimized incorporation of multiple antibodies directed to cancer cell-specific surface markers, such as epithelial cell adhesion molecule (EpCAM), human epidermal growth factor receptor-2 (HER-2), and prostate specific antigen (PSA). The surfaces were tested using a series of tumor cells, MDA-PCa-2b, MCF-7, and MDA-MB-361, both in mixture in vitro and after being spiked into human blood. Our multifunctional surface demonstrated highly efficient capture of tumor cells in human blood, achieving up to 82% capture efficiency (∼10-fold enhancement than a surface with the antibodies alone) and up to 90% purity. Furthermore, the multipatterned antibodies allowed differential capturing of the tumor cells. These results support that our multifunctional surface has great potential as an effective platform that accommodates virtually any antibodies, which will likely lead to clinically significant, differential detection of CTCs that are rare and highly heterogeneous.

Fluorescence- and magnetic-activated cell sorting strategies to isolate and enrich human spermatogonial stem cells

OBJECTIVE

To determine the molecular characteristics of human spermatogonia and optimize methods to enrich spermatogonial stem cells (SSCs).

DESIGN

Laboratory study using human tissues.

SETTING

Research institute.

PATIENT(S)

Healthy adult human testicular tissue.

INTERVENTION(S)

Human testicular tissue was fixed or digested with enzymes to produce a cell suspension. Human testis cells were fractionated by fluorescence-activated cell sorting (FACS) and magnetic-activated cell sorting (MACS).

MAIN OUTCOME MEASURE(S)

Immunostaining for selected markers, human-to-nude mouse xenotransplantation assay.

RESULT(S)

Immunohistochemistry costaining revealed the relative expression patterns of SALL4, UTF1, ZBTB16, UCHL1, and ENO2 in human undifferentiated spermatogonia as well as the extent of overlap with the differentiation marker KIT. Whole mount analyses revealed that human undifferentiated spermatogonia (UCHL1+) were typically arranged in clones of one to four cells whereas differentiated spermatogonia (KIT+) were typically arranged in clones of eight or more cells. The ratio of undifferentiated-to-differentiated spermatogonia is greater in humans than in rodents. The SSC colonizing activity was enriched in the THY1dim and ITGA6+ fractions of human testes sorted by FACS. ITGA6 was effective for sorting human SSCs by MACS; THY1 and EPCAM were not.

CONCLUSION(S)

Human spermatogonial differentiation correlates with increased clone size and onset of KIT expression, similar to rodents. The undifferentiated-to-differentiated developmental dynamics in human spermatogonia is different than rodents. THY1, ITGA6, and EPCAM can be used to enrich human SSC colonizing activity by FACS, but only ITGA6 is amenable to high throughput sorting by MACS.

The role of nuclear EpICD in extrahepatic cholangiocarcinoma: association with β-catenin

After intramembranous proteolysis-mediated loss of the extracellular domain of the epithelial cell adhesion molecule (EpEx) and release of an intracellular domain (EpICD) into the cytoplasm, EpICD sequentially associates with FHL2 to form a nuclear complex with β-catenin and Lef-1. This association induces gene transcription involved in the activation of the oncogenic potential of epithelial cell adhesion molecule (EpCAM). We examined the localization and expression of EpEx, EpICD and β-catenin in surgical specimens of extrahepatic cholangiocarcinoma (ECC) from 79 patients and focused on the relationship between nuclear expression of EpICD and β-catenin. We also examined the role of EpICD by transfecting the EpICD cDNA in cholangiocarcinoma (CC) cell lines. There was a significant correlation between the nuclear expression of EpICD and β-catenin in ECC tissues. Frequent nuclear co-localization of EpICD and β-catenin was observed in cancer cells forming the invasive front. Nuclear expression of EpICD also significantly correlated with histologic grade of tumor. Overexpression of EpICD in the CC cells significantly increased the cell growth and proliferation. The overexpression of EpICD in the CC cells also increased the expression levels of the active form of β-catenin and EpCAM target genes, such as c-myc and cyclin D1. Furthermore, the overexpression of EpICD significantly enhanced the migration and invasiveness of CC cells. Conversely, the inhibition of EpCAM in EpCAM-overexpressing cells by siRNA significantly decreased cell proliferation, migration and invasion. These results indicate that the spatial localization of EpICD and its mutual interaction with β-catenin may be important in ECC progression and invasion.

Epithelial cell adhesion molecule is overexpressed in hypopharyngeal carcinoma and suppresses the metastasis and proliferation of the disease when downregulated

The epithelial cell adhesion molecule (EpCAM) is overexpressed in the majority of human epithelial carcinomas, and its overexpression is associated with proliferation and neoplastic transformation. However, the precise molecular mechanism involved in EpCAM-related proliferation and metastasis in hypopharyngeal carcinoma is unknown. The aim of the present study was to identify the role of EpCAM in the metastasis and proliferation of hypopharyngeal carcinoma. An immunohistochemical staining assay indicated that EpCAM was overexpressed in primary hypopharyngeal carcinoma tissues, and that this overexpression correlated with the tumor size and lymph node metastasis. In the following treatment of the hypopharyngeal carcinoma FaDu cell line with EpCAM, the downregulation of EpCAM was found to significantly suppress cell metastasis and proliferation, as detected by Transwell, clone formation and MTT assays. Additionally, western blot analysis revealed that EpCAM downregulation increased the expression of the adhesion- and proliferation-related factors, E-cadherin, α-catenin and β-catenin, in the cytoskeleton, as well as β-catenin expression in the nucleus. In conclusion, the present study indicated that EpCAM is a potential oncogene and contributes to the metastasis of hypopharyngeal carcinoma. The current study is the first to provide evidence for the potential value of targeting EpCAM in hypopharyngeal carcinoma therapy.

Cancer stem cell marker Musashi-1 rs2522137 genotype is associated with an increased risk of lung cancer

Gene single nucleotide polymorphisms (SNPs) have been extensively studied in association with development and prognosis of various malignancies. However, the potential role of genetic polymorphisms of cancer stem cell (CSC) marker genes with respect to cancer risk has not been examined. We conducted a case-control study involving a total of 1000 subjects (500 lung cancer patients and 500 age-matched cancer-free controls) from northeastern China. Lung cancer risk was analyzed in a logistic regression model in association with genotypes of four lung CSC marker genes (CD133, ALDH1, Musashi-1, and EpCAM). Using univariate analysis, the Musashi-1 rs2522137 GG genotype was found to be associated with a higher incidence of lung cancer compared with the TT genotype. No significant associations were observed for gene variants of CD133, ALDH1, or EpCAM. In multivariate analysis, Musashi-1 rs2522137 was still significantly associated with lung cancer when environmental and lifestyle factors were incorporated in the model, including lower BMI; family history of cancer; prior diagnosis of chronic obstructive pulmonary disease, pneumonia, or pulmonary tuberculosis; occupational exposure to pesticide; occupational exposure to gasoline or diesel fuel; heavier smoking; and exposure to heavy cooking emissions. The value of the area under the receiver-operating characteristic (ROC) curve (AUC) was 0.7686. To our knowledge, this is the first report to show an association between a Musashi-1 genotype and lung cancer risk. Further, the prediction model in this study may be useful in determining individuals with high risk of lung cancer.

Predicting targeted drug combinations based on Pareto optimal patterns of coexpression network connectivity

Background

Molecularly targeted drugs promise a safer and more effective treatment modality than conventional chemotherapy for cancer patients. However, tumors are dynamic systems that readily adapt to these agents activating alternative survival pathways as they evolve resistant phenotypes. Combination therapies can overcome resistance but finding the optimal combinations efficiently presents a formidable challenge. Here we introduce a new paradigm for the design of combination therapy treatment strategies that exploits the tumor adaptive process to identify context-dependent essential genes as druggable targets.

Methods

We have developed a framework to mine high-throughput transcriptomic data, based on differential coexpression and Pareto optimization, to investigate drug-induced tumor adaptation. We use this approach to identify tumor-essential genes as druggable candidates. We apply our method to a set of ER⁺ breast tumor samples, collected before (n = 58) and after (n = 60) neoadjuvant treatment with the aromatase inhibitor letrozole, to prioritize genes as targets for combination therapy with letrozole treatment. We validate letrozole-induced tumor adaptation through coexpression and pathway analyses in an independent data set (n = 18).

Results

We find pervasive differential coexpression between the untreated and letrozole-treated tumor samples as evidence of letrozole-induced tumor adaptation. Based on patterns of coexpression, we identify ten genes as potential candidates for combination therapy with letrozole including EPCAM, a letrozole-induced essential gene and a target to which drugs have already been developed as cancer therapeutics. Through replication, we validate six letrozole-induced coexpression relationships and confirm the epithelial-to-mesenchymal transition as a process that is upregulated in the residual tumor samples following letrozole treatment.

Conclusions

To derive the greatest benefit from molecularly targeted drugs it is critical to design combination treatment strategies rationally. Incorporating knowledge of the tumor adaptation process into the design provides an opportunity to match targeted drugs to the evolving tumor phenotype and surmount resistance.

Genetic variants in the EPCAM gene is associated with the prognosis of transarterial chemoembolization treated hepatocellular carcinoma with portal vein tumor thrombus

The epithelial cell adhesion molecule (EPCAM) is involved in the tumorigenesis and progression of many malignancies, including hepatocellular carcinoma (HCC). Single nucleotide polymorphisms (SNPs) of EPCAM have been reported to be with the risk and prognosis of several malignancies. However, the association of SNPs in EPCAM gene with the prognosis of HCC patients has never been investigated. In this study, two functional SNPs (rs1126497 and rs1421) in the EPCAM gene were selected and genotyped in a cohort of 448 unresectable Chinese HCC patients treated by TACE. The association of the two SNPs with the overall survival (OS) of patients was assessed by univariate and multivariate Cox proportional hazards model and Kaplan-Meier curve. Our data showed that there was no significant association between either SNP and OS of patients. However, in the stratified analysis, the variant-containing genotypes (WV+VV) of SNP rs1126497 exhibited a significant association with poorer OS in HCC patients who had portal vein tumor thrombus (PVTT) in multivariate analysis of Cox proportional hazard model (hazard ratio, 1.71; 95% confidence interval, 1.16–2.53, P = 0.007), and in Kaplan-Meier curve analysis (P = 0.023), comparing to those carrying wild-type genotype. Our results suggest that SNP rs1126497 in the EPCAM gene may serve as an independent prognosis biomarker for unresectable HCC patient with PVTT, which warranted further validating investigation.

Circulating tumour cells: the evolving concept and the inadequacy of their enrichment by EpCAM-based methodology for basic and clinical cancer research

Increasing evidence suggests that circulating tumour cells (CTCs) are responsible for metastatic relapse and this has fuelled interest in their detection and quantification. Although numerous methods have been developed for the enrichment and detection of CTCs, none has yet reached the 'gold' standard. Since epithelial cell adhesion molecule (EpCAM)-based enrichment of CTCs offers several advantages, it is one of the most commonly used and has been adapted for high-throughput technology. However, emerging evidence suggests that CTCs are highly heterogeneous: they consist of epithelial tumour cells, epithelial-to-mesenchymal transition (EMT) cells, hybrid (epithelial/EMT(+)) tumour cells, irreversible EMT(+) tumour cells, and circulating tumour stem cells (CTSCs). The EpCAM-based approach does not detect CTCs expressing low levels of EpCAM and non-epithelial phenotypes such as CTSCs and those that have undergone EMT and no longer express EpCAM. Thus, the approach may lead to underestimation of the significance of CTCs, in general, and CTSCs and EMT(+) tumour cells, in particular, in cancer dissemination. Here, we provide a critical review of research literature on the evolving concept of CTCs and the inadequacy of their enrichment by EpCAM-based technology for basic and clinical cancer research. The review also outlines future perspectives in the field.

EpCAM, a potential therapeutic target for esophageal squamous cell carcinoma

BACKGROUND

Molecular-targeted drugs are not available for esophageal squamous cell carcinoma (ESCC), which has a poor prognosis. We investigated the clinicopathological significance of epithelial cell adhesion molecule (EpCAM) expression and the utility of EpCAM as a potential therapeutic target.

METHODS

The relationship between EpCAM expression and clinicopathological factors was examined by immunohistochemistry in 74 patients with resectable ESCC. A total of ten ESCC cell lines were analyzed for EpCAM expression. The effects of EpCAM knockdown in TE4, TE10, and TE14 cells were examined with regard to cell proliferation and gene expression in vitro and tumor growth in vivo. The antitumor effect of catumaxomab in ESCC cell lines was examined.

RESULTS

EpCAM overexpression was associated with poor survival in ESCC patients (P = 0.026). Multivariate Cox regression analysis showed that EpCAM overexpression was a significant and independent prognostic factor for surgically treated ESCC (P = 0.004). TE4 and TE10 cells showed high EpCAM expression, in contrast to TE14. EpCAM siRNA knockdown in TE4 and TE10 cells downregulated CCND1 and CCNE2 and suppressed cell proliferation. Low EpCAM expression reduced tumorigenesis; TE4 cells initiated tumorigenesis in seven of the ten mice injected, whereas shRNA knockdown resulted in smaller tumors in two of ten mice at 6 weeks after transplantation. Concentration- and time-dependent antitumor effects of catumaxomab were observed in TE4 and TE10 cells.

CONCLUSIONS

EpCAM overexpression is an independent prognostic factor for surgically treated ESCC. EpCAM contributes to cell proliferation and tumorigenesis and may be a useful therapeutic target for ESCC.

An EpCAM/CD3 bispecific antibody efficiently eliminates hepatocellular carcinoma cells with limited galectin-1 expression

There have been several studies suggesting that cancer stem cells (CSCs) contribute to the high rates of recurrence and resistance to therapies observed in hepatocellular carcinoma (HCC). Epithelial cell adhesion molecule (EpCAM) has been demonstrated to be a biomarker of CSCs and a potential therapeutic target in HCC. Here, we prepared two anti-EpCAM monoclonal antibodies (1H8 and 2F2) and an anti-EpCAM bispecific T cell engager (BiTE) 1H8/CD3, which was derived from 1H8, and used them to treat HCC in vitro and in vivo. The results demonstrated that all of the developed anti-EpCAM antibodies specifically bound to EpCAM. Neither anti-EpCAM monoclonal antibody had obvious anti-HCC activities in vitro or in vivo. However, anti-EpCAM BiTE 1H8/CD3 induced strong peripheral blood mononuclear cell-dependent cellular cytotoxicity in Huh-7 and Hep3B cells but not EpCAM-negative SK-Hep-1 cells. Notably, 1H8/CD3 completely inhibited the growth of Huh-7 and Hep3B xenografts in vivo. Treatment of the Huh-7 HCC xenografts with 1H8/CD3 significantly suppressed tumor proliferation and reduced the expression of most CSC biomarkers. Intriguingly, galectin-1 (Gal-1) overexpression inhibited 1H8/CD3-induced lymphocytotoxicity in HCCs while knockdown of Gal-1 increased the lymphocytotoxicity. Collectively, these results indicate that anti-EpCAM BiTE 1H8/CD3 is a promising therapeutic agent for HCC treatment. Gal-1 may contribute to the resistance of HCC cells to 1H8/CD3-induced lysis.

Targeted methylation of the epithelial cell adhesion molecule (EpCAM) promoter to silence its expression in ovarian cancer cells

The Epithelial Cell Adhesion Molecule (EpCAM) is overexpressed in many cancers including ovarian cancer and EpCAM overexpression correlates with decreased survival of patients. It was the aim of this study to achieve a targeted methylation of the EpCAM promoter and silence EpCAM gene expression using an engineered zinc finger protein that specifically binds the EpCAM promoter fused to the catalytic domain of the Dnmt3a DNA methyltransferase. We show that transient transfection of this construct increased the methylation of the EpCAM promoter in SKOV3 cells from 4–8% in untreated cells to 30%. Up to 48% methylation was observed in stable cell lines which express the chimeric methyltransferase. Control experiments confirmed that the methylation was dependent on the fusion of the Zinc finger and the methyltransferase domains and specific for the target region. The stable cell lines with methylated EpCAM promoter showed a 60–80% reduction of EpCAM expression as determined at mRNA and protein level and exhibited a significantly reduced cell proliferation. Our data indicate that targeted methylation of the EpCAM promoter could be an approach in the therapy of EpCAM overexpressing cancers.

Targeted expression of suicide gene by tissue-specific promoter and microRNA regulation for cancer gene therapy

In order to realise the full potential of cancer suicide gene therapy that allows the precise expression of suicide gene in cancer cells, we used a tissue specific Epithelial cell adhesion molecule (EpCAM) promoter (EGP-2) that directs transgene Herpes simplex virus–thymidine kinase (HSV-TK) expression preferentially in EpCAM over expressing cancer cells. EpCAM levels are considerably higher in retinoblastoma (RB), a childhood eye cancer with limited expression in normal cells. Use of miRNA regulation, adjacent to the use of the tissue-specific promoter, would provide the second layer of control to the transgene expression only in the tumor cells while sparing the normal cells. To test this hypothesis we cloned let-7b miRNA targets in the 3’UTR region of HSV-TK suicide gene driven by EpCAM promoter because let-7 family miRNAs, including let-7b, were found to be down regulated in the RB tumors and cell lines. We used EpCAM over expressing and let-7 down regulated RB cell lines Y79, WERI-Rb1 (EpCAM ^+ve/let-7b^{down-regulated}), EpCAM down regulated, let-7 over expressing normal retinal Müller glial cell line MIO-M1(EpCAM ^−ve/let-7b^up-regulated), and EpCAM up regulated, let-7b up-regulated normal thyroid cell line N-Thy-Ori-3.1(EpCAM ^+ve/let-7b^up-regulated) in the study. The cell proliferation was measured by MTT assay, apoptosis was measured by probing cleaved Caspase3, EpCAM and TK expression were quantified by Western blot. Our results showed that the EGP2-promoter HSV-TK (EGP2-TK) construct with 2 or 4 copies of let-7b miRNA targets expressed TK gene only in Y79, WERI-Rb-1, while the TK gene did not express in MIO-M1. In summary, we have developed a tissue-specific, miRNA-regulated dual control vector, which selectively expresses the suicide gene in EpCAM over expressing cells.

Polymorphisms of EpCAM gene and prognosis for non-small-cell lung cancer in Han Chinese

The epithelial cell adhesion molecule (EpCAM) is overexpressed in a wide variety of human cancers and is associated with patient prognosis, including those with lung cancer. However, the association of single nucleotide polymorphisms (SNPs) in the EpCAM gene with the prognosis for non-small-cell lung cancer (NSCLC) patients has never been investigated. We evaluated the association between two SNPs, rs1126497 and rs1421, in the EpCAM gene and clinical outcomes in a Chinese cohort of 506 NSCLC patients. The SNPs were genotyped using the Sequenom iPLEX genotyping system. Multivariate Cox proportional hazards model and Kaplan-Meier curves were used to assess the association of EpCAM gene genotypes with the prognosis of NSCLC. We found that the non-synonymous SNP rs1126497 was significantly associated with survival. Compared with the CC genotype, the CT+TT genotype was a risk factor for both death (hazard ratio, 1.40; 95% confidence interval [CI], 1.02-1.94; P = 0.040) and recurrence (hazard ratio, 1.34; 95% CI, 1.02-1.77; P = 0.039). However, the SNP rs1421 did not show any significant effect on patient prognosis. Instead, the AG+GG genotype in rs1421 was significantly associated with early T stages (T1/T2) when compared with the AA genotype (odds ratio for late stage = 0.65; 95% CI, 0.44-0.96, P = 0.029). Further stratified analysis showed notable modulating effects of clinical characteristics on the associations between variant genotypes of rs1126497 and NSCLC outcomes. In conclusion, our study indicated that the non-synonymous SNP rs1126497 may be a potential prognostic marker for NSCLC patients.

Overview of current standpoints in profiling of circulating tumor cells

The goal of this review is summarizing current technologies developed as the in vitro prognostic/diagnostic systems that can rapidly separate and detect circulating tumor cells (CTCs) from cancer patient's blood (1-10 CTCs of 1 billion red blood cells) by labeled and non-labeled method. The review is focused on three major areas of CTC research (1) Summary of previous research on capturing of CTCs, (2) New development of the in vitro prognostic diagnosis system of cancer that is capable of rapid separation of CTCs, (3) Future direction on development of new technologies for CTC profiling. Current CTC researches have helped on identifying patients who may benefit from chemotherapy before treatment, patients who may benefit from continued chemotherapy, and leading to clinical development of CTC-guided chemotherapy strategies. We analyze the feasibility of clinical application of these current CTC research for the ultimate goal of increasing the survivability of cancer patient. The biomolecular assays of viable CTCs from cancer patient may elucidate the mechanism of metastasis and tumor initiating cells and also may have high impact on the development of personalized medicine to overcome the incurable diseases.

EpCAM controls actomyosin contractility and cell adhesion by direct inhibition of PKC

Epithelial cell adhesion molecule (EpCAM) is a cell-surface protein highly expressed in embryonic tissues and in malignant carcinomas. We report that EpCAM acts as a potent inhibitor of novel protein kinase C (nPKC) in both embryos and cancer cells. We observed dramatic effects of loss of EpCAM on amphibian embryonic tissues, which include sequentially strong overstimulation of PKC activity and of the Erk pathway, leading to exacerbated myosin contractility, loss of cadherin-mediated adhesion, tissue dissociation, and, ultimately, cell death. We show that PKC inhibition is caused by a short segment of the EpCAM cytoplasmic tail. This motif resembles the pseudosubstrate inhibitory domains of PKCs and binds nPKCs with high affinity. A bioinformatics search reveals the existence of similar motifs in other plasma membrane proteins, most of which are cell-cell adhesion molecules. Thus, direct inhibition of PKC by EpCAM represents a general mode of regulation of signal transduction by cell-surface proteins.

Role of fibulin-3 in lung cancer: in vivo and in vitro analyses

Lung cancer was the most commonly diagnosed cancer in 2008 worldwide. The level of fibulin-3 expression was found to be decreased in many cancer types due to aberrant promoter methylation and is correlated with poor survival of patients. However, the role of fibulin-3 and which form of fibulin-3 is expressed in lung cancer cells remain unclear. Therefore, pathologic and functional studies were carried out to determine the role of fibulin-3 in suppressing lung cancer both in vivo and in vitro. In the present study, we found that the levels of fibulin-3 mRNA and protein were lower in cancer tissues than in normal tissues. Downregulation of fibulin-3 mRNA in tumor tissues was associated with an increase in fibulin-3 promoter methylation. Circulating fibulin-3 was significantly associated with tumor progression, survival rate of lung cancer patients, and the number of circulating tumor cells (CTCs). To examine the effects of exogenous expression of fibulin-3 in vitro, lung cancer A549 cells were transfected with the pEGFP-C1-fibulin-3 expression vector. Relative to the untreated cells, fibulin-3-expressing cells exhibited lower proliferation and mobility as determined by MTT and Transwell assays, respectively. To conclude, our results suggest that fibulin-3 negatively modulates the invasiveness of lung cancer cells via regulation of p38-MAPK and MMP-2/9.

Clinicopathologic implications of EpCAM and Sox2 expression in breast cancer

BACKGROUND

The purpose of this study was to investigate the clinicopathologic significance of EpCAM and Sox2 expression in breast cancer and to study their correlation during breast cancer progression.

PATIENTS AND METHODS

EpCAm and Sox2 expression were assessed using immunohistochemistry in ductal carcinoma insitu (DCIS), invasive breast cancer (IBC) and matched lymph node metastasis (LNM), if present.

RESULTS

EpCAM overexpression was found in 63.2% of DCIS, 72.2% of IBC and 74.4% of LNM. In IBC cases, EpCAM overexpression was associated with high grade (P < .001), large tumor size (P = .051), poor Nottingham Prognostic Index (NPI) (P = .006), histological tumor types (P = .044) and the triple negative phenotype (P = .008). LNM frequently reflected the expression phenotype of the matched primary tumors with no significant differences between LNM and their primary tumors (P = .564). Sox2 expression was detected in 47.4%, 33.3% and 54.7% of DCIS, IBC and LNM respectively. In DCIS group, Sox2 expression was significantly associated with comedo type (P = .037), negative ER (P = .012) and PR (P = .037) and the triple negative phenotype (P = .006). In IBC cases, Sox2 expression showed significant associations with high grade (P = .045), nodal spread (P = .037), poor NPI (P = .018) and the triple negative phenotype (P < .001). LNM showed significantly higher Sox2 expression rates than primary tumors (P < .001). Significant positive associations between EpCAM overexpression and Sox2 positivity in DCIS (P = .027), IBC (P = .001) and LNM (P < .001) were found.

CONCLUSION

This study emphasized the potential role of EpCAM and Sox2 in breast carcinogenesis and revealed their involvement during breast cancer progression and LN metastases.

Epithelial cell adhesion molecule (EpCAM) is associated with prostate cancer metastasis and chemo/radioresistance via the PI3K/Akt/mTOR signaling pathway

Prostate cancer (CaP) is the second leading malignancy in men. The role of epithelial cell adhesion molecule (EpCAM), also known as CD326, in CaP progression and therapeutic resistance is still uncertain. Here, we aimed to investigate the roles of EpCAM in CaP metastasis and chemo/radioresistance. Expression of EpCAM in CaP cell lines and human CaP tissues was assessed using immunofluorescence and immunohistochemistry, respectively. EpCAM was knocked down (KD) in PC-3, DU145 and LNCaP-C4-2B cells using small interfering RNA (siRNA), and KD results were confirmed by confocal microscope, Western blotting and quantitative real time polymerase chain reaction (qRT-PCR). Cell growth was evaluated by proliferation and colony formation assays. The invasive potential was assessed using a matrigel chamber assay. Tumorigenesis potential was measured by a sphere formation assay. Chemo-/radiosensitivity were measured using a colony formation assay. Over-expression of EpCAM was found in primary CaP tissues and lymph node metastases including cancer cells and surrounding stromal cells. KD of EpCAM suppressed CaP proliferation and invasive ability, reduced sphere formation, enhanced chemo-/radiosensitivity, and down-regulated E-cadherin, p-Akt, p-mTOR, p-4EBP1 and p-S6K expression in CaP cells. Our findings suggest that EpCAM plays an important role in CaP proliferation, invasion, metastasis and chemo-/radioresistance associated with the activation of the PI3K/Akt/mTOR signaling pathway and is a novel therapeutic target to sensitize CaP cells to chemo-/radiotherapy.

Expression of betapapillomavirus oncogenes increases the number of keratinocytes with stem cell-like properties

Human papillomaviruses (HPV) of genus Betapapillomavirus (betaPV) are associated with nonmelanoma skin cancer development in epidermodysplasia verruciformis (EV) and immunosuppressed patients. Epidemiological and molecular studies suggest a carcinogenic activity of betaPV during early stages of cancer development. Since viral oncoproteins delay and perturb keratinocyte differentiation, they may have the capacity to either retain or confer a "stem cell-like" state on oncogene-expressing cells. The aim of this study was to determine (i) whether betaPV alters the expression of cell surface markers, such as CD44 and epithelial cell adhesion molecule (EpCAM), that have been associated with epithelial stemness, and (ii) whether this confers functional stem cell-like properties to human cutaneous keratinocytes. Fluorescence-activated cell sorter (FACS) analysis revealed an increase in the number of cells with high CD44 and EpCAM expression in keratinocyte cultures expressing HPV type 8 (HPV8) oncogenes E2, E6, and E7. Particularly through E7 expression, a distinct increase in clonogenicity and in the formation and size of tumor spheres was observed, accompanied by reduction of the epithelial differentiation marker Calgranulin B. These stem cell-like properties could be attributed to the pool of CD44(high) EpCAM(high) cells, which was increased within the E7 cultures of HPV5, -8, and -20. Enhanced EpCAM levels were present in organotypic skin cultures of primary keratinocytes expressing E7 of the oncogenic HPV types HPV5, -8, and -16 and in clinical samples from EV patients. In conclusion, our data show that betaPV may increase the number of stem cell-like cells present during early carcinogenesis and thus enable the persistence and accumulation of DNA damage necessary to generate malignant stem cells.

Regulated intramembrane proteolysis and degradation of murine epithelial cell adhesion molecule mEpCAM

Epithelial cell adhesion molecule EpCAM is a transmembrane glycoprotein, which is highly and frequently expressed in carcinomas and (cancer-)stem cells, and which plays an important role in the regulation of stem cell pluripotency. We show here that murine EpCAM (mEpCAM) is subject to regulated intramembrane proteolysis in various cells including embryonic stem cells and teratocarcinomas. As shown with ectopically expressed EpCAM variants, cleavages occur at α-, β-, γ-, and ε-sites to generate soluble ectodomains, soluble Aβ-like-, and intracellular fragments termed mEpEX, mEp-β, and mEpICD, respectively. Proteolytic sites in the extracellular part of mEpCAM were mapped using mass spectrometry and represent cleavages at the α- and β-sites by metalloproteases and the b-secretase BACE1, respectively. Resulting C-terminal fragments (CTF) are further processed to soluble Aβ-like fragments mEp-β and cytoplasmic mEpICD variants by the g-secretase complex. Noteworthy, cytoplasmic mEpICD fragments were subject to efficient degradation in a proteasome-dependent manner. In addition the γ-secretase complex dependent cleavage of EpCAM CTF liberates different EpICDs with different stabilities towards proteasomal degradation. Generation of CTF and EpICD fragments and the degradation of hEpICD via the proteasome were similarly demonstrated for the human EpCAM ortholog. Additional EpCAM orthologs have been unequivocally identified in silico in 52 species. Sequence comparisons across species disclosed highest homology of BACE1 cleavage sites and in presenilin-dependent γ-cleavage sites, whereas strongest heterogeneity was observed in metalloprotease cleavage sites. In summary, EpCAM is a highly conserved protein present in fishes, amphibians, reptiles, birds, marsupials, and placental mammals, and is subject to shedding, γ-secretase-dependent regulated intramembrane proteolysis, and proteasome-mediated degradation.

Role of the EpCAM (CD326) in prostate cancer metastasis and progression

Despite significant advances in surgery, radiotherapy and chemotherapy to treat prostate cancer (CaP), many patients die of secondary disease (metastases). Current therapeutic approaches are limited, and there is no cure for metastatic castration-resistant prostate cancer (CRPC). Epithelial cell adhesion molecule (EpCAM, also known as CD326) is a transmembrane glycoprotein that is highly expressed in rapidly proliferating carcinomas and plays an important role in the prevention of cell-cell adhesion, cell signalling, migration, proliferation and differentiation. Stably and highly expressed EpCAM has been found in primary CaP tissues, effusions and CaP metastases, making it an ideal candidate of tumour-associated antigen to detect metastasis of CaP cells in the circulation as well as a promising therapeutic target to control metastatic CRPC disease. In this review, we discuss the implications of the newly identified roles of EpCAM in terms of its diagnostic and metastatic relevance to CaP. We also summarize EpCAM expression in human CaP and EpCAM-mediated signalling pathways in cancer metastasis. Finally, emerging and innovative approaches to the management of the disease and expanding potential therapeutic applications of EpCAM for targeted strategies in future CaP therapy will be explored.

Presence of EpCAM-positive circulating tumor cells as biomarker for systemic disease strongly correlates to survival in patients with hepatocellular carcinoma

Current imaging technologies do not sufficiently detect micrometastasis and therefore do not allow adequate stratification of patients with hepatocellular carcinoma (HCC) for curative or systemic therapy. In HCC, presence of stem cell-like, epithelial cell adhesion molecule (EpCAM)-positive cells correlates with tumor aggressiveness and formation of metastasis. Therefore, we investigated the prognostic relevance of EpCAM-positive circulating tumor cells (CTCs) in patients with HCC. Blood from 78 patients (19 patients in the control cohort and 59 patients with HCC) was tested for CTCs with the CellSearch™ system. Correlation analysis to overall survival (OS), the Barcelona Clinic Liver Cancer (BCLC) staging system, macroscopic and microscopic vascular invasion and alpha-fetoprotein (AFP) levels were performed. We detected ≥1 CTC in 18/59 HCC patients and in 1/19 patients with cirrhosis or benign hepatic tumor (p = 0.026). OS was significantly shorter (460 vs. 746 days) in the CTC-positive cohort (p = 0.017). Comparing BCLC stages, significant differences in CTC detection rates were also observed: BCLC stages A 1/9, B 6/31 and C 11/19 (p = 0.006). Ten of 18 patients with macroscopic and 10/16 patients with microscopic vascular invasion exhibited positive findings in CTC testing (p = 0.004 and p = 0.006). Furthermore, CTC results correlated to AFP (cutoff > 400 ng/mL) levels (p = 0.050). Our study demonstrates frequent presence of EpCAM-positive CTC in patients with intermediate or advanced HCC and its prognostic value for OS with possible implications for future treatment stratification.

EpCAM overexpression prolongs proliferative capacity of primary human breast epithelial cells and supports hyperplastic growth

Introduction

The Epithelial Cell Adhesion Molecule (EpCAM) has been shown to be strongly expressed in human breast cancer and cancer stem cells and its overexpression has been supposed to support tumor progression and metastasis. However, effects of EpCAM overexpression on normal breast epithelial cells have never been studied before. Therefore, we analyzed effects of transient adenoviral overexpression of EpCAM on proliferation, migration and differentiation of primary human mammary epithelial cells (HMECs).

Methods

HMECs were transfected by an adenoviral system for transient overexpression of EpCAM. Thereafter, changes in cell proliferation and migration were studied using a real time measurement system. Target gene expression was evaluated by transcriptome analysis in proliferating and polarized HMEC cultures. A Chicken Chorioallantoic Membrane (CAM) xenograft model was used to study effects on in vivo growth of HMECs.

Results

EpCAM overexpression in HMECs did not significantly alter gene expression profile of proliferating or growth arrested cells. Proliferating HMECs displayed predominantly glycosylated EpCAM isoforms and were inhibited in cell proliferation and migration by upregulation of p27^KIP1 and p53. HMECs with overexpression of EpCAM showed a down regulation of E-cadherin. Moreover, cells were more resistant to TGF-β1 induced growth arrest and maintained longer capacities to proliferate in vitro. EpCAM overexpressing HMECs xenografts in chicken embryos showed hyperplastic growth, lack of lumen formation and increased infiltrates of the chicken leukocytes.

Conclusions

EpCAM revealed oncogenic features in normal human breast cells by inducing resistance to TGF-β1-mediated growth arrest and supporting a cell phenotype with longer proliferative capacities in vitro. EpCAM overexpression resulted in hyperplastic growth in vivo. Thus, we suggest that EpCAM acts as a prosurvival factor counteracting terminal differentiation processes in normal mammary glands.

Expression of epithelial cell adhesion molecule in paired tumor samples of patients with primary and recurrent serous ovarian cancer

OBJECTIVE

Ovarian cancer (OC) recurrence constitutes a therapeutic dilemma with various novel targeted agents emerging that offer alternative treatment options. The aim of the present study was to evaluate and compare epithelial cell adhesion molecule (EpCAM) expression profiles in paired tumor samples of patients with OC relapse.

METHODS

EpCAM expression was analyzed by immunohistochemistry using the avidin-biotin-complex method on paraffin-embedded OC tissues obtained at primary surgery as well as on corresponding tumor samples of the same patients at relapse. The EpCAM overexpression was defined as 76% to 100% of tumor cells positively stained for EpCAM. Clinical data were collected within the Tumorbank Ovarian Cancer Network.

RESULTS

Nineteen patients with serous OC histology were included in the study (median age at primary diagnosis, 50 years; range, 40-74 years). The majority of the patients (95%) presented with International Federation of Gynecology and Obstetrics stage III/IV, and 68.4% of the tumors were poorly differentiated. A complete macroscopic tumor resection could be achieved in 15 patients (78.9%) at diagnosis. Epithelial cell adhesion molecule overexpression was detected in 17 (89%) of the primary and 16 (84%) of the recurrent tumors (P = 1.0); hence, no significant change of the EpCAM expression profile could be identified over time.

CONCLUSIONS

Epithelial cell adhesion molecule expression profile appears to remain stable during the course from the primary throughout the relapse of serous OC. The results indicate that EpCAM might be an interesting therapeutic target structure in serous OC.

EpCAM: structure and function in health and disease

Injection of tumor cells in mice more than 30 years ago resulted in the discovery of an epithelial antigen, later defined as a cell adhesion molecule (EpCAM). Although EpCAM has since evoked significant interest as a target in cancer therapy, mechanistic insights on the functions of this glycoprotein have been emerging only very recently. This may have been caused by the multitude of functions attributed to the glycoprotein, its localization at different subcellular sites and complex posttranslational modifications. Here, we review how EpCAM modifies cell-cell contact adhesion strength and tissue plasticity, and how it regulates cell proliferation and differentiation. Major knowledge derived from human diseases will be highlighted: Mutant EpCAM that is absent from the cell surface leads to fatal intestinal abnormalities (congenital tufting enteropathy). EpCAM-mediated cell proliferation in cancer may result from signaling (i) via regulated intramembrane proteolysis and/or (ii) the localization and association with binding partners in specialized membrane microdomains. New insight in EpCAM signaling will help to develop optimized cancer therapies and open new avenues in the field of regenerative medicine.

Heterodimeric bispecific single-chain variable-fragment antibodies against EpCAM and CD16 induce effective antibody-dependent cellular cytotoxicity against human carcinoma cells

A heterodimeric bispecific biological recombinant drug was synthesized by splicing DNA fragments from two fully humanized single-chain variable-fragment (scFV) antibody fragments forming a novel drug simultaneously recognizing the CD16 natural killer (NK) cell marker and the cancer marker epithelial cell adhesion molecule (EpCAM). The drug precipitously enhanced the killing of human carcinomas of the prostate, breast, colon, head, and neck even at very low effector:target ratios. The drug EpCAM16 rendered even nonactivated NK cell-proficient killers and activated them to kill via degranulation and cytokine production. Studies show that bispecific antibodies can be used to induce proficient killing of the carcinoma targets that ordinarily are resistant to NK-mediated killing. Apparently, the innate immune system can be effectively recruited to kill cancer cells using the bispecific antibody platform and EpCAM targeting.

EpCAM expression varies significantly and is differentially associated with prognosis in the luminal B HER2(+), basal-like, and HER2 intrinsic subtypes of breast cancer

Background:

Epithelial cell adhesion molecule (EpCAM) is frequently expressed in breast cancer, and its expression has been associated with poor prognosis. Breast cancer can be subdivided into intrinsic subtypes, differing in prognosis and response to therapy.

Methods:

To investigate the association between EpCAM expression and prognosis in the intrinsic subtypes of breast cancer, we performed immunohistochemical studies on a tissue microarray encompassing a total of 1365 breast cancers with detailed clinicopathological annotation and outcomes data.

Results:

We observed EpCAM expression in 660 out of 1365 (48%) cases. EpCAM expression varied significantly in the different intrinsic subtypes. In univariate analyses of all cases, EpCAM expression was associated with a significantly worse overall survival. In the intrinsic subtypes, EpCAM expression was associated with an unfavourable prognosis in the basal-like and luminal B HER2⁺ subtypes but associated with a favourable prognosis in the HER2 subtype. Consistently, specific ablation of EpCAM resulted in increased cell viability in the breast cancer cell line SKBR3 (ER⁻, PR⁻, and HER2⁺) but decreased viability in the breast cancer cell line MDA-MB-231 (ER⁻, PR⁻, and HER2⁻ ).

Conclusion:

The differential association of EpCAM expression with prognosis in intrinsic subtypes has important implications for the development of EpCAM-targeted therapies in breast cancer.

Epithelial cell adhesion molecule (EpCAM) regulates claudin dynamics and tight junctions

Epithelial cell adhesion molecule (EpCAM) (CD326) is a surface glycoprotein expressed by invasive carcinomas and some epithelia. Herein, we report that EpCAM regulates the composition and function of tight junctions (TJ). EpCAM accumulated on the lateral interfaces of human colon carcinoma and normal intestinal epithelial cells but did not co-localize with TJ. Knockdown of EpCAM in T84 and Caco-2 cells using shRNAs led to changes in morphology and adhesiveness. TJ formed readily after EpCAM knockdown; the acquisition of trans-epithelial electroresistance was enhanced, and TJ showed increased resistance to disruption by calcium chelation. Preparative immunoprecipitation demonstrated that EpCAM bound tightly to claudin-7. Co-immunoprecipitation documented associations of EpCAM with claudin-7 and claudin-1 but not claudin-2 or claudin-4. Claudin-1 associated with claudin-7 in co-transfection experiments, and claudin-7 was required for association of claudin-1 with EpCAM. EpCAM knockdown resulted in decreases in claudin-7 and claudin-1 proteins that were reversed with lysosome inhibitors. Immunofluorescence microscopy revealed that claudin-7 and claudin-1 continually trafficked into lysosomes. Although EpCAM knockdown decreased claudin-1 and claudin-7 protein levels overall, accumulations of claudin-1 and claudin-7 in TJ increased. Physical interactions between EpCAM and claudins were required for claudin stabilization. These findings suggest that EpCAM modulates adhesion and TJ function by regulating intracellular localization and degradation of selected claudins.

A label-free DC impedance-based microcytometer for circulating rare cancer cell counting

Quantification of circulating tumor cells (CTCs) in blood samples is believed to provide valuable evidence of cancer progression, cancer activity status, response to therapy in patients with metastatic cancer, and possible cancer diagnosis. Recently, a number of researchers reported that CTCs tend to lose their epithelial cell adhesion molecule (EpCAM) by an epithelial-mesenchymal transition (EMT). As such, label-free CTC detection methods are attracting worldwide attention. Here, we describe a label-free DC impedance-based microcytometer for CTCs by exploiting the difference in size between CTCs and blood cells. This system detects changes in DC impedance between two polyelectrolytic gel electrodes (PGEs) under low DC voltages. Using spiked ovarian cancer cell lines (OVCAR-3) in blood as a model system, we were able to count the cells using a microcytometer with 88% efficiency with a flow rate of 13 μl min(-1) without a dilution process. Furthermore, we examined blood samples from breast cancer patients using the cytometer, and detected CTCs in 24 out of 24 patient samples. Thus, the proposed DC impedance-based microcytometer presents a facile and fast way of CTC evaluation regardless of their biomarkers.

Bidirectional modulation of endogenous EpCAM expression to unravel its function in ovarian cancer

Background:

The epithelial cell adhesion molecule (EpCAM) is overexpressed on most carcinomas. Dependent on the tumour type, its overexpression is either associated with improved or worse patient survival. For ovarian cancer, however, the role of EpCAM remains unclear.

Methods:

Cell survival of ovarian cancer cell lines was studied after induction or repression of endogenous EpCAM expression using siRNA/cDNA or artificial transcription factors (ATF) consisting of engineered zinc-fingers fused to either a transcriptional activator or repressor domain.

Results:

Two ATFs were selected as the most potent down- and upregulator, showing at least a two-fold alteration of EpCAM protein expression compared with control. Downregulation of EpCAM expression resulted in growth inhibition in breast cancer, but showed no effect on cell growth in ovarian cancer. Induction or further upregulation of EpCAM expression decreased ovarian cancer cell survival.

Conclusion:

The bidirectional ATF-based approach is uniquely suited to study cell-type-specific biological effects of EpCAM expression. Using this approach, the oncogenic function of EpCAM in breast cancer was confirmed. Despite its value as a diagnostic marker and for immunotherapy, EpCAM does not seem to represent a therapeutic target for gene expression silencing in ovarian cancer.

EpCAM modulates NF-κB signaling and interleukin-8 expression in breast cancer

The epithelial cell adhesion molecule (EpCAM) is a 40-kD type I transmembrane protein that is overexpressed in human epithelial cancers and is currently the target of molecular therapy based on its overexpression at the cell surface. Recently, we and others have shown a role for EpCAM in cell signaling and carcinogenesis, and EpCAM expression seems to promote breast cancer invasion. Interleukin-8 (IL-8/CXCL-8) is an inflammatory cytokine that has recently been shown to modulate breast cancer invasion and angiogenesis. In preliminary experiments, we identified a correlation between EpCAM and IL-8 expression in primary human breast cancers. Specific ablation of EpCAM in breast cancer cell lines results in decreased IL-8 expression, and IL-8 contributes to EpCAM-dependent breast cancer invasion. Specific ablation of EpCAM is also associated with decreased NF-κB transcription factor activity, decreased phosphorylation of the NF-κB family member RELA, and increased IκBα protein expression. EpCAM modulates IL-8 expression at baseline, and following IL-1β stimulation, which is known to be a potent inducer of NF-κB in breast cancer. In functional rescue experiments, specific ablation of RELA or forced expression of the NF-κB inhibitor protein IκBα prevented EpCAM-dependent rescue of IL-8 promoter activity. These studies show for the first time that EpCAM can modulate NF-κB transcription factor activity and IL-8 expression in breast cancer and confirm the role of EpCAM signaling in modulating breast cancer invasion. Further study is required to define the molecular mechanism(s) of EpCAM signaling in breast cancer and to direct the rational development of molecular therapies targeting EpCAM.

A phase 1b study of humanized KS-interleukin-2 (huKS-IL2) immunocytokine with cyclophosphamide in patients with EpCAM-positive advanced solid tumors

Background

Humanized KS-interleukin-2 (huKS-IL2), an immunocytokine with specificity for epithelial cell adhesion molecule (EpCAM), has demonstrated favorable tolerability and immunologic activity as a single agent.

Methods

Phase 1b study in patients with EpCAM-positive advanced solid tumors to determine the maximum tolerated dose (MTD) and safety profile of huKS-IL2 in combination with low-dose cyclophosphamide. Treatment consisted of cyclophosphamide (300 mg/m² on day 1), and escalating doses of huKS-IL2 (0.5–4.0 mg/m² IV continuous infusion over 4 hours) on days 2, 3, and 4 of each 21-day cycle. Safety, pharmacokinetic profile, immunogenicity, anti-tumor and biologic activity were evaluated.

Results

Twenty-seven patients were treated for up to 6 cycles; 26 were evaluable for response. The MTD of huKS-IL2 in combination with 300 mg/m² cyclophosphamide was 3.0 mg/m². At higher doses, myelosuppression was dose-limiting. Transient lymphopenia was the most common grade 3/4 adverse event (AE). Other significant AEs included hypotension, hypophosphatemia, and increase in serum creatinine. All patients recovered from these AEs. The huKS-IL2 exposure was dose-dependent, but not dose-proportional, accumulation was negligible, and elimination half-life and systemic clearance were independent of dose and time. Most patients had a transient immune response to huKS-IL2. Immunologic activity was observed at all doses. Ten patients (38%) had stable disease as best response, lasting for ≥ 4 cycles in 3 patients.

Conclusion

The combination of huKS-IL2 with low-dose cyclophosphamide was well tolerated. Although no objective responses were observed, the combination showed evidence of immunologic activity and 3 patients showed stable disease for ≥ 4 cycles.

Trial registration

http://NCT00132522

Epithelial cell adhesion molecule-targeted drug delivery for cancer therapy

INTRODUCTION

The epithelial cell adhesion molecule (EpCAM) is abundantly expressed in epithelial tumors, on cancer stem cells and circulating tumor cells. Together with its role in oncogenic signaling, this has sparked interest in its potential for tumor targeting with antibodies and drug conjugates for safe and effective cancer therapy. Recent advances in protein engineering, linker design and drug formulations have provided a multitude of EpCAM-targeting anticancer agents, several of them with good perspectives for clinical development.

AREAS COVERED

This article reviews the biological, therapeutic and technical aspects of EpCAM-targeted drug delivery for cancer therapy. The authors discuss seminal findings, which distinguish EpCAM as a target with oncogenic function and abundant expression in epithelial tumors. Moreover, recent trends in engineering improved anti-EpCAM antibodies, binding proteins that are not derived from immunoglobulins and drug conjugates derived from them are highlighted and their therapeutic potential based on reported preclinical and clinical data, originality of design and perspectives are critically assessed.

EXPERT OPINION

EpCAM has shown promise for safe and efficient targeting of solid tumors using antibodies, alternative binding molecules and novel drug conjugates. Among the myriad of EpCAM-targeting drug delivery systems investigated so far, several could demonstrate therapeutic benefit, other formulations engineered to become tailor-made missiles are on the brink.

Epithelial cell adhesion molecule is an independent prognostic marker in clear cell renal carcinoma

Epithelial cell adhesion molecule (EPCAM) has recently attained a renewed interest as a candidate protein in diagnosis, prognostication and therapy of various tumor entities. The molecular epidemiology and prognostic relevance of EPCAM in renal cell carcinoma (RCC) and amongst the histological subtypes of RCC are unclear. We analyzed the prevalence and prognostic significance of EPCAM in a tumor tissue microarray composed of 1,088 independent RCCs samples by immunohistochemistry (IHC). We found significant variations of EPCAM IHC staining intensities in between the RCC subtypes: in papillary and chromophobe RCC, the majority of tumors (89-93%) showed an at least weak EPCAM protein expression. In the largest subgroup, the clear cell (cc)RCC (n = 767), a negative EPCAM IHC was found in 1/3 of the patients and was associated with high-grade disease and nodal metastases. Kaplan-Meier analyses demonstrated a significant association between positive EPCAM IHC and prolonged overall survival, even in a subset of low-risk ccRCC. In multivariable analyses, EPCAM represented an independent risk factor of survival throughout all subgroups. For localized, low-grade ccRCC, information of EPCAM IHC raised predictive accuracy of a multivariate model by ∼5%, compared to T-stage and grade alone. Our findings indicate that EPCAM is an independent prognostic molecular marker in ccRCC and, especially in localized ccRCC, might be able to provide auxiliary information for a better prognostication.

Drug Resistant Breast Cancer Cell Line Displays Cancer Stem Cell Phenotype and Responds Sensitively to Epigenetic Drug SAHA

Cancer stem cell (CSC) population in solid human breast tumor was identified by CD44(+)/CD24(-) phenotype, characterized by high tumorigenicity, invasiveness and drug resistance. In this study, we characterized drug resistant breast cancer cell line-MCF-7/Adr and a number of breast cancer cell lines using flow cytometry, immunofluorescence, mammosphere formation assay and migration assay, examining their CSC immunophenotypes, presence of CSC proteins, tumorigenicity in vitro and migratory rates, respectively. Our results show that MCF-7/Adr cells uniformly display CSC characteristics yet retain low migratory rate. They are also able to self-renew and differentiate under floating culture conditions. Furthermore, MCF-7/Adr is selectively sensitive to epigenetic drug, suberoylanilide hydroxamic acid (SAHA), losing drug resistance and changes morphology yet retaining CSC immunophenotypes. In conclusion, we show that resistant breast cancer cell line MCF-7/Adr demonstrates uniform CSC like characteristics and are sensitive to epigenetic drug treatment.

MMP7 is a target of the tumour-associated antigen EpCAM

Epithelial cell adhesion molecule (EpCAM) is a single-transmembrane protein, which is involved in numerous cellular processes including cell adhesion, proliferation, maintenance of stemness of embryonic cells and progenitors, migration and invasion. Activation of signal transduction by EpCAM is warranted by regulated intramembrane proteolysis and nuclear translocation of the intracellular domain EpICD. Here, we describe matrix metalloproteinase 7 (MMP7) as a target gene of EpCAM signalling viaEpICD nuclear translocation. EpCAM and MMP7 expression pattern and levels positively correlated in vitro and in vivo, and were strongly elevated in primary carcinomas of the head and neck area. Hence, MMP7 is a novel target of EpCAM signalling.

High expression of epithelial cellular adhesion molecule in peritoneal metastasis of gastric cancer

Intraperitoneally administrated epithelial cellular adhesion molecule (EpCAM) monoclonal antibody is a therapeutic agent in patients with malignant effusion in several types of carcinoma. However, the role of EpCAM in peritoneal metastasis (PM) lesions and primary lesions of gastric cancer (GC) is still unclear. Therefore, in this study, we investigated EpCAM expression in GC patients with PM. We investigated the expression of EpCAM in 35PM lesions and 104 biopsy samples as primary lesions. Immunohistochemical staining was performed using the Ventana Benchmark XT (Roche Diagnostics) system. EpCAM expression was evaluated by calculating the total immunostaining score, which is the product of the proportion score and the intensity score. Overexpression was defined as a total score greater than 4. All PM specimens showed overexpression of EpCAM, and GC cells in both the surface layer and the deep layer of the PM showed a high expression of EpCAM. Meanwhile, in the biopsy sample, the expression of EpCAM ranged from none to strong. The EpCAM score results for PM specimens and biopsy samples were 11.0 ± 2.0 and 6.9 ± 3.9, respectively. The difference between the scores was statistically significant (P < 0.05). The intraperitoneally administrated EpCAM antibody might have a anti-cancer effect in PM lesions of GC. Additionally, it can be assumed that only GC cells which express a high level of EpCAM might metastasize to the peritoneum.

Cytoplasmic Trop-1/Ep-CAM overexpression is associated with a favorable outcome in node-positive breast cancer

OBJECTIVE

Trop-1/Ep-CAM modulates growth and survival of transformed cells, and it is highly expressed in most carcinomas including breast cancer. Only membranous staining is typically considered in evaluating Trop-1/epithelial cell adhesion molecule (Ep-CAM) expression in tumor cells. However, there is evidence of retention of Trop-1/Ep-CAM, as functionally incompetent molecules, in intra-cytoplasmic vesicles. Hence, we investigated whether cytoplasmic immunostaining may have an independent clinical significance with respect to membranous staining.

METHODS

Membranous and cytoplasmic Trop-1/Ep-CAM expression was immunohistochemically investigated in 642 unilateral breast cancers from patients with a 99-month median follow-up. Multiple correspondence analysis was used to investigate the association between Trop-1/Ep-CAM and other biological variables. The impact of Trop-1/Ep-CAM expression on the patient's outcome was evaluated as event-free survival by the Kaplan-Meier method and proportional hazard Cox model.

RESULTS

While tumors with intermediate/strong membranous staining were mostly associated with concomitant cytoplasmic Trop-1/Ep-CAM expression (97%), tumors with weak-to-nil membranous staining showed intermediate/high cytoplasmic expression in 23% of cases. Cytoplasmic overexpression was associated with a favorable outcome, especially in node-positive patients, regardless of the adjuvant therapy received.

CONCLUSION

Trop-1/Ep-CAM expression may have different clinical implications according to its subcellular localization.

Noble polymeric surface conjugated with zwitterionic moieties and antibodies for the isolation of exosomes from human serum

New zwitterionic polymer-coated immunoaffinity beads were developed to resist nonspecific protein adsorption from undiluted human serum for diagnostic applications of exosomes. A zwitterionic sulfobetaine monomer with an amine functional group was employed for simple surface chemistry and antifouling properties. An exosomal biomarker protein, epithelial cell adhesion molecule (EpCAM), was selected as a target molecule in this work. The beads were coated with polyacrylic acids (PAA) for increasing biorecognition sites, and protein G was then conjugated with carboxylic acid groups on the surfaces for controlling EpCAM antibody orientation. The remaining free carboxylic acid groups were modified with sulfobetaine moieties, and anti-EpCAM antibody was finally introduced. The amount of anti-EpCAM on the beads was increased by 40% when compared with PAA-uncoated beads. The surfaces of the beads exhibited near-net-zero charge, and nonspecific protein adsorption was effectively suppressed by sulfobetaine moieties. EpCAM was captured from undiluted human serum with almost the same degree of efficiency as from PBS buffer solution using the newly developed immunoaffinity beads.

Levels of effectiveness of gene therapies targeting survivin and its splice variants in human breast cancer cells

In order to develop an effective strategy of breast cancer therapy targeting survivin and its splice variants survivin-ΔEx3 and survivin-2B, the present study constructed four expression vectors by fusing the survivin antisense gene, the survivin (T34A) gene, the survivin-ΔEx3 antisense gene, and the survivin-2B gene with the enhanced green fluorescent protein (eGFP) gene. Each of these vectors was transiently transfected into the B-Cap-37 human breast cancer cell line. The effects of these four vectors with diverse genes on the proliferation and apoptosis of B-Cap-37 breast cancer cells were examined and compared in vitro using MTT and flow cytometry assays. Results of the MTT assay indicated that all four gene therapy plasmids were most effective at inhibiting the proliferation of B-Cap-37 cells 72 h after transfection. However, the four gene therapies had different rates of cell inhibition. pcDNA3.1(+)-egfp-anti-survivin and pcDNA3.1(+)-survivin (T34A)-egfp had almost equivalent or better effectiveness at suppressing cell growth. pcDNA3.1(+)-egfp-anti-survivin-ΔEx3 moderately inhibited the growth of B-Cap-37 cells. In contrast, pcDNA3.1(+)-survivin-2B-egfp had limited inhibition of cell growth. Similar profile of effectiveness of four gene therapies in soliciting cell apoptosis was also observed. These results suggest the relative importance of targeting survivin and its splice variant survivin-ΔEx3 in breast cancer treatment.

Expression and role of epithelial cell adhesion molecule in dysplastic nodule and hepatocellular carcinoma

Epithelial cell adhesion molecule (EpCAM) has been proposed as a marker for cancer stem cells in human hepatocellular carcinoma (HCC). However, the function and clinical significance of EpCAM in HCC is largely unknown. We examined EpCAM expression and localization in 28 dysplastic nodules (DNs) and their corresponding cirrhotic nodules, 79 HCC tissue sections and 132 HCC tissue microarray cores by immunohistochemistry and determined the relationship to clinicopathologic findings. We also examined the role of EpCAM in HCC using synthetic small interfering RNA to silence EpCAM gene expression in Huh-7 cells. EpCAM expression was very rare in DNs but dominantly appeared in a distinctly nodular type of small HCC. Expression of EpCAM was observed in 39% (31/79) of HCC tissue sections and in 34.1% (45/132) of tissue microarray sections. EpCAM expression in HCC was significantly associated with high tumor grade and serum α-fetoprotein level. Silencing EpCAM gene expression significantly decreased the proliferative activity and invasiveness of HCC cells. EpCAM expression was an independent prognostic factor for survival in patients with T1 HCC. The data indicate that EpCAM expression occurs at distinct nodular stage of HCC and could play an important role in HCC progression.

Epithelial cell adhesion molecule regulates tumor initiation and tumorigenesis via activating reprogramming factors and epithelial-mesenchymal transition gene expression in colon cancer

Epithelial cell adhesion molecule (EpCAM) is highly expressed in epithelial-transformed neoplasia and tumor-initiated cells (TICs), but the role that EpCAM plays in the stemness properties of TICs is still unclear. Here we show that EpCAM and reprogramming factors (c-Myc, Oct4, Nanog, and Sox2) were concomitantly elevated in TICs, which were shown to have superior self-renewal, invasiveness, and tumor-initiating abilities. Elevation of EpCAM enhanced tumorsphere formation and tumor initiation. Knockdown of EpCAM inhibited the expressions of reprogramming factors and epithelial-mesenchymal transition genes, thereby suppressing tumor initiation, self-renewal, and invasiveness. In addition, EpCAM, especially intracellular domain of EpCAM (EpICD), bound to and activated the promoter of reprogramming factors. Treatment with the inhibitor of γ-secretase (DAPT) led to the blockage of the expressions of reprogramming factors and epithelial-mesenchymal transition genes, which was accompanied by the reduction of tumor self-renewal and invasion. Furthermore, the increased release of EpEX enhanced production of EpICD and regulated the expression of reprogramming factors. Together, these findings suggest that EpCAM plays an important role in regulating cancer-initiating abilities in TICs of colon cancer. This discovery can be used in the development of new strategies for cancer therapy.

EPCAM-A novel molecular target for the treatment of pediatric and adult germ cell tumors

Germ cell tumors (GCTs) are thought to develop from totipotent primordial germ cells. Although the epithelial cell adhesion molecule (EPCAM) is expressed on embryonic stem cells as well as different tumor cells, it has not yet been extensively studied in GCTs. We analyzed EPCAM expression by quantitative RT-PCR in 48 fresh-frozen GCT specimens of different histology (10 mature teratoma, MT; 6 immature teratoma, IT; 7 dysgerminoma; 6 mixed malignant GCTs; 19 yolk sac tumor, YST) and in the GCT cell lines NCCIT, TE76.T, JAR and 2102Ep, and correlated its expression with AFP and hCG protein levels, histologic differentiation, and clinical follow-up data. EPCAM protein was visualized by immunohistochemistry of selected corresponding paraffin embedded tumor tissues. EPCAM was expressed in malignant but not in benign GCTs irrespective of age, sex, site and clinical stage of tumor (P = 0.001). In primary teratomas, EPCAM expression increased with their grade of immaturity (mean 2(-ΔCt) values: MT 0.23, IT 1.61, P = 0.007) and significantly correlated with serum AFP (P = 0.03) and hCG (P = 0.03) levels in malignant GCTs. Particularly high EPCAM levels were found in nonseminomatous GCTs such as YSTs (8.49) and choriocarcinoma (13.54). Immunohistochemical analysis verified gene expression data showing a distinct EPCAM staining in YST. Similarly in vitro, highest EPCAM expression was measured in GCT cell lines comprising yolk sac (2102Ep: 5.59) or choriocarcinoma (JAR: 10.65) components. This first comprehensive analysis of EPCAM in GCTs revealed high EPCAM expression in YSTs and choriocarcinomas. Thus, these nonseminomatous GCTs may be interesting targets for EPCAM immunotherapy, which has to be evaluated in further studies.

Phase IB study of the EpCAM antibody adecatumumab combined with docetaxel in patients with EpCAM-positive relapsed or refractory advanced-stage breast cancer

BACKGROUND

Targeted therapy options in HER2-negative breast cancer are limited. This open-label, multicenter phase IB dose-escalation trial was conducted to determine safety, tolerability, and antitumor activity of a combination of docetaxel (Taxotere) and increasing doses of adecatumumab, a human IgG1 antibody targeting epithelial cell adhesion molecule (EpCAM), in EpCAM-positive relapsed or primary refractory advanced-stage breast cancer.

PATIENTS AND METHODS

Patients pretreated with up to four prior chemotherapy regimens received increasing adecatumumab doses either every 3 weeks (q3w) or weekly (qw) combined with docetaxel (100 mg/m(2) q3w). Primary end points were safety and tolerability. Antitumor activity was evaluated according to RECIST. Clinical benefit was defined as complete or partial response or stable disease for ≥24 weeks.

RESULTS

Thirty-one evaluable patients were treated. Most adverse events were mild to moderate in severity. Neutropenia, leukocytopenia, lymphopenia, and diarrhea (dose-limiting) were the most frequent toxic effects. Maximum tolerated doses of adecatumumab given in combination with docetaxel were 550 mg/m(2) q3w and 360 mg/m(2) qw. Clinical benefit was observed in 44% of patients treated with q3w adecatumumab and docetaxel, increasing to 63% in patients with high EpCAM-expressing tumors.

CONCLUSION

Combination therapy of adecatumumab and docetaxel is safe, feasible, and potentially active in heavily pretreated advanced-stage breast cancer.