Role of integrated cancer nanomedicine in overcoming drug resistance

Cancer remains a major killer of mankind. Failure of conventional chemotherapy has resulted in recurrence and development of virulent multi drug resistant (MDR) phenotypes adding to the complexity and diversity of this deadly disease. Apart from displaying classical physiological abnormalities and aberrant blood flow behavior, MDR cancers exhibit several distinctive features such as higher apoptotic threshold, aerobic glycolysis, regions of hypoxia, and elevated activity of drug-efflux transporters. MDR transporters play a pivotal role in protecting the cancer stem cells (CSCs) from chemotherapy. It is speculated that CSCs are instrumental in reviving tumors after the chemo and radiotherapy. In this regard, multifunctional nanoparticles that can integrate various key components such as drugs, genes, imaging agents and targeting ligands using unique delivery platforms would be more efficient in treating MDR cancers. This review presents some of the important principles involved in development of MDR and novel methods of treating cancers using multifunctional-targeted nanoparticles. Illustrative examples of nanoparticles engineered for drug/gene combination delivery and stimuli responsive nanoparticle systems for cancer therapy are also discussed.

Challenges in circulating tumor cell detection by the CellSearch system

Enumeration and characterization of circulating tumor cells (CTC) hold the promise of a real time liquid biopsy. They are however present in a large background of hematopoietic cells making their isolation technically challenging. In 2004, the CellSearch system was introduced as the first and only FDA cleared method designed for the enumeration of circulating tumor cells in 7.5 mL of blood. Presence of CTC detected by CellSearch is associated with poor prognosis in metastatic carcinomas. CTC remaining in patients after the first cycles of therapy indicates a futile therapy. Here we review challenges faced during the development of the CellSearch system and the difficulties in assigning objects as CTC. The large heterogeneity of CTC and the different approaches introduced in recent years to isolate, enumerate and characterize CTC results in a large variation of the number of CTC reported urging the need for uniform definitions and at least a clear definition of what the criteria are for assigning an object as a CTC.

In vitro and in vivo evaluation of therapy targeting epithelial-cell adhesion-molecule aptamers for non-small cell lung cancer

Targeted, disease-specific delivery of therapeutic nanoparticles shows wonderful promise for transmitting highly cytotoxic anti-cancer agents. Using the reaction of non-small cell lung cancer (SK-MES-1 and A549 cell lines) as representative of other cancer types', the present study examines the effects of EpCAM-fluoropyrimidine RNA aptamer-decorated, DOX-loaded, PLGA-b-PEG nanopolymersomes that bond specifically to the extracellular domain of epithelial-cell adhesion molecules. Results demonstrate that EpCAM aptamer-conjugated DOX-NPs (Apt-DOX-NP) significantly enhance cellular nanoparticle uptake in SK-MES-1 and A549 cell lines and increase the cytotoxicity of the DOX payload as compared with non-targeted DOX-NP (P<0.05). Additionally, Apt-DOX-NP exhibits greater tumor inhibition in nude mice bearing SK-MES-1 non-small cell lung-cancer xenografts and reduces toxicity, as determined by loss of body weight, cardiac histopathology and animal survival rate in vivo. After a single intravenous injection of Apt-DOX-NP and DOX-NPs, tumor volume decreased 60.9% and 31.4%, respectively, in SK-MES-1-xenograft nude mice compared with members of a saline-injected control group. This study proves the potential utility of Apt-DOX-NP for therapeutic application in non-small cell lung cancer. In the future, EpCAM-targeted therapies might play a key role in treating non-small cell lung cancer, the most common type of lung cancer.

Cancer stem cell markers correlate with early recurrence and survival in hepatocellular carcinoma

AIM: To investigate whether expression of cancer stem cell (CSC) markers is associated with recurrence and survival in hepatocellular carcinoma (HCC) patients.

METHODS: A consecutive series of 90 HCC patients who underwent curative hepatectomy between April 2007 and April 2009 were analyzed. Of the 90 patients, 38 (42%) experienced recurrence within two years of surgery. To adjust for baseline differences between this early recurrence group and the other patients, propensity-score matching was used to generate 25 pairs of patients. Immunohistochemistry was used to compare expression of CD133, CD90, and epithelial cell adhesion molecule (EpCAM) in liver tissues from propensity score-matched patients and from 10 healthy adults. Associations of the three markers with HCC, clinicopathological characteristics, early recurrence, and survival time were explored.

RESULTS: The expression of all three CSC markers was significantly higher in HCC tissue than in healthy liver tissue (P < 0.001 for all). Among the HCC clinicopathology characteristics examined, the absence of tumor capsule was associated with CD133 expression (P = 0.005); higher histopathology grade and larger tumor size were associated with CD90 expression (P = 0.010 and 0.034, respectively); and elevated serum alpha-fetoprotein levels were associated with EpCAM expression (P = 0.021). Expression of CD90 and EpCAM was significantly higher in the early recurrence group than in other patients (P = 0.001 and 0.045, respectively), whereas CD133 expression was not significantly different between the two groups (P = 0.440). Multivariate analysis identified only CD90 expression as significantly associated with early recurrence. Log-rank analysis identified expression of both CD90 and EpCAM as significantly associated with survival time of HCC patients. Cox regression identified EpCAM expression as an independent predictor of survival time.

CONCLUSION: Expression of CD133, CD90, and EpCAM CSC markers may be linked to HCC tumor onset and/or progression. In addition, EpCAM expression is associated with shorter survival time, while CD90 expression is associated with early HCC recurrence.

Single-walled carbon nanotubes functionalized with aptamer and piperazine-polyethylenimine derivative for targeted siRNA delivery into breast cancer cells

Epithelial cell adhesion molecule (EpCAM) is a glycosylated type 1 membrane protein which is frequently over expressed in most solid tumors and it has recently been identified as a cancer stem cell (CSC) marker. Specific targeting of CSCs using nano-carriers would enhance treatment efficacy of cancer. In this study, we used a RNA aptamer against EpCAM (EpDT3) attached physically to our newly synthesized non-viral vector, based on single-walled carbon nanotube (SWNT) conjugated to piperazine-polyethylenimine derivative. The DNA transfection efficiency and siRNA delivery activity of the synthesized vector was investigated against upregulated BCL9l, which has been associated with breast and colorectal cancers. The complexes of the vector-aptamer/siRNA could specifically induce apoptosis by more than 20% in MCF-7 cell line as a positive EpCAM than MDA-MB-231 cells which are EpCAM negative. The decrease of BCL9l protein level was observed with western blot analysis in MCF-7 cells indicating the targeted silencing activity of the complex.

Concise Review: Aggressive Colorectal Cancer: Role of Epithelial Cell Adhesion Molecule in Cancer Stem Cells and Epithelial-to-Mesenchymal Transition

Colorectal cancer (CRC) is one of the most common malignancies worldwide. In spite of various attempts to ameliorate outcome by escalating treatment, significant improvement is lacking particularly in the adjuvant setting. It has been proposed that cancer stem cells (CSCs) and the epithelial‐to‐mesenchymal transition (EMT) are at least partially responsible for therapy resistance in CRC. The epithelial cell adhesion molecule (EpCAM) was one of the first CSC antigens to be described. Furthermore, an EpCAM‐specific antibody (edrecolomab) has the merit of having launched the era of monoclonal antibody treatment in oncology in the 1990s. However, despite great initial enthusiasm, monoclonal antibody treatment has not proven successful in the adjuvant treatment of CRC patients. In the meantime, new insights into the function of EpCAM in CRC have emerged and new drugs targeting various epitopes have been developed. In this review article, we provide an update on the role of EpCAM in CSCs and EMT, and emphasize the potential predictive selection criteria for novel treatment strategies and refined clinical trial design. stemcellstranslationalmedicine2018;7:495–501

Association of preoperative EpCAM Circulating Tumor Cells and peripheral Treg cell levels with early recurrence of hepatocellular carcinoma following radical hepatic resection

BACKGROUND

This study was carried out to determine the prognostic significance of preoperative peripheral epithelial cell adhesion molecule- positive (EpCAM (+)) circulating tumor cell (CTC) and T regulatory (Treg) cell levels in hepatocellular carcinoma (HCC) patients for the prediction of postoperative recurrence following curative resection.

METHODS

A total of 49 patients about to undergo curative resection for HCC were recruited into the study. PCR and FACS were used to detect the preoperative levels of EpCAM (mRNA+) CTCs and CD4(+)CD25(+)Foxp3(+) Treg cells. The prognostic value of EpCAM (mRNA+) CTCs, CD4(+)CD25(+)Foxp3(+) Treg cells, and other clinicopathological factors were analyzed by applying the Kaplan-Meier method and the multivariate Cox proportional hazards model.

RESULTS

The number of EpCAM (mRNA+) CTCs and Treg/CD4(+) cells showed significant correlation as prognostic factors of postoperative HCC recurrence: EpCAM (mRNA+) CTC ≥ 2.22 (P = 0.001) and Treg/CD4(+) ≥ 5.07 (P = 0.045), with EpCAM (mRNA+) CTC ≥ 2.22 (P = 0.003, HR = 6.668) being the most important indicator. Patients with high CTC/Treg levels showed a significantly higher risk of developing postoperative HCC recurrence than those with low CTC/Treg levels (66.7 % vs. 10.3 %, P < 0.001). The high CTC/low Treg group also presented higher 1-year recurrence rates compared with the low CTC/low Treg level group (50.0 % vs. 10.3 %, P = 0.004).

CONCLUSIONS

Elevated EpCAM (mRNA+) CTC and Treg/CD4(+) levels were associated with early recurrence of HCC, indicative of poor clinical outcome. The combined detection of EpCAM (mRNA+) CTC and Treg/CD4(+) may therefore provide a novel prognostic predictor for HCC patients.

EpCAM as multi-tumour target for near-infrared fluorescence guided surgery

Background

Evaluation of resection margins during cancer surgery can be challenging, often resulting in incomplete tumour removal. Fluorescence-guided surgery (FGS) aims to aid the surgeon to visualize tumours and resection margins during surgery. FGS relies on a clinically applicable imaging system in combination with a specific tumour-targeting contrast agent. In this study EpCAM (epithelial cell adhesion molecule) is evaluated as target for FGS in combination with the novel Artemis imaging system.

Methods

The NIR fluorophore IRDye800CW was conjugated to the well-established EpCAM specific monoclonal antibody 323/A3 and an isotype IgG1 as control. The anti-EpCAM/800CW conjugate was stable in serum and showed preserved binding capacity as evaluated on EpCAM positive and negative cell lines, using flow cytometry and cell-based plate assays. Four clinically relevant orthotopic tumour models, i.e. colorectal cancer, breast cancer, head and neck cancer, and peritonitis carcinomatosa, were used to evaluate the performance of the anti-EpCAM agent with the clinically validated Artemis imaging system. The Pearl Impulse small animal imaging system was used as reference. The specificity of the NIRF signal was confirmed using bioluminescence imaging and green-fluorescent protein.

Results

All tumour types could clearly be delineated and resected 72 h after injection of the imaging agent. Using NIRF imaging millimetre sized tumour nodules were detected that were invisible for the naked eye. Fluorescence microscopy demonstrated the distribution and tumour specificity of the anti-EpCAM agent.

Conclusions

This study shows the potential of an EpCAM specific NIR-fluorescent agent in combination with a clinically validated intraoperative imaging system to visualize various tumours during surgery.

Expression pattern of epithelial cell adhesion molecule on normal and malignant colon tissues

AIM: To investigate the expression pattern of epithelial cell adhesion molecule (Ep-CAM) on normal and malignant colon tissues to evaluate its diagnostic and therapeutic significance.

METHODS: cDNA encoding Ep-CAM extracellular domain was cloned by reverse transcription-polymerase chain reaction (RT-PCR) from excised malignant colon tissues and inserted into a glutathione S-transferase (GST)-tagged vector. Ep-CAM-GST fusion protein was induced by isopropyl-β-D-thiogalactopyranoside (IPTG) and purified with glutathione-sepharose. The Ep-CAM-GST fusion protein was mixed with Freund’s adjuvant and Balb/c mice were immunized with it. Sp2/0 myeloma cells were fused with the spleen cells of the immunized mice. After having selected by indirect ELISA, the anti-Ep-CAM monoclonal antibodies (MAbs) were generated and the corresponding ascites were obtained. Finally, the human colon carcinoma tissue array prepared from seventy individual patients was stained with the anti-Ep-CAM MAbs.

RESULTS: The isolated Ep-CAM cDNA sequence was identical to the data in GenBank. The expressed fusion protein was almost soluble and had a molecular weight (MW) of 53 ku. Four MAbs against Ep-CAM were obtained and designated as FMU-Ep1, FMU-Ep2, FMU-Ep3 and FMU-Ep4 respectively. Among them, FMU-Ep4 could recognize the natural Ep-CAM on Colo205 and SW480 cells, and all of them could be used for immunohistochemical staining of tissue sections. It was found that Ep-CAM was distributed differently in normal and various malignant colon tissues, including squamous cell carcinoma, signet-ring cell carcinoma and adenocarcinoma. In normal colon gland epithelia, Ep-CAM antigen was mainly distributed on the basolateral membrane and in the region between the basolateral membrane and the cytoplastic part near the nuclei, whereas the expression pattern of colon malignancies was mainly on the whole surface of epithelia and the expression was much higher than the normal colon tissues. The staining pattern of tissue array showed in adenocarcinoma and papillary adenocarcinoma, and the expression of Ep-CAM was increased from grade I to grade III.

CONCLUSION: MAbs against Ep-CAM might be useful for research on the structure and function of Ep-CAM and may have diagnostic and therapeutic value to various colon carcinomas.

Epithelial cell adhesion molecule in human hepatocellular carcinoma cell lines: a target of chemoresistence

Background

The low survival rate of hepatocellular carcinoma (HCC) is partly attributable to its resistance to existing chemotherapeutic agents. Until now, there have been limited chemotherapeutic agents for liver cancer. Epithelial cell adhesion molecule (EpCAM) has been found to be over-expressed during stages of carcinogenesis and has been associated with poor overall survival in many cancers. The aim of this study was to evaluate EpCAM expression in HCC and evaluate the effects of EpCAM to established chemotherapy.

Methods

Three human hepatocellular carcinoma cell lines—HepG2, Hep3B and HuH-7—were pre- and post-treated with doxorubicin, 5-fluorouracil (5-FU) and cisplatin. Cell viability and EpCAM protein expression were measured by MTT assay and Western Blotting respectively. EpCAM positive cells were analyzed by flow cytometry. To evaluate the effects of doxorubicin efficacy on EpCAM positive cells, a small interfering RNA (siRNA) specific to EpCAM was transfected into the cells and treated with doxorubicin. Results: EpCAM was significantly down-regulated by doxorubicin treatment in all three HCC cell lines (P <0.05 or 0.01). EpCAM expression was down-regulated by the 5-FU and cisplatin in HepG2 cells, however the EpCAM expression was up-regulated by 5-FU and cisplatin in Hep3B cell line. EpCAM expression was down-regulated by 5-FU, and up-regulated by cisplatin in Huh-7 cell line. Flow cytometry assay showed doxorubicin exposure decreased EpCAM positive cell quantities in three HCC cell lines. EpCAM siRNA knock-down attenuated cell mortality after doxorubicin exposure.

Conclusion

All of these findings demonstrate that EpCAM is one of targets of chemoresistence.

Characterization of hepatic progenitors from human fetal liver during second trimester

AIM: To enrich hepatic progenitors using epithelial cell adhesion molecule (EpCAM) as a marker from human fetal liver and investigate the expression of human leukocyte antigen (HLA) and their markers associated with hepatic progenitor cells.

METHODS: EpCAM +ve cells were isolated using magnetic cell sorting (MACS) from human fetuses (n = 10) at 15-25 wk gestation. Expression of markers for hepatic progenitors such as albumin, alpha-fetoprotein (AFP), CD29 (integrin β1), CD49f (integrin α6) and CD90 (Thy 1) was studied by using flow cytometry, immunocytochemistry and RT-PCR; HLA class I (A, B, C) and class II (DR) expression was studied by flow cytometry only.

RESULTS: FACS analysis indicated that EpCAM +ve cells were positive for CD29, CD49f, CD90, CD34, HLA class I, albumin and AFP but negative for HLA class II (DR) and CD45. RT PCR showed that EpCAM +ve cells expressed liver epithelial markers (CK18), biliary specific marker (CK19) and hepatic markers (albumin, AFP). On immunocytochemical staining, EpCAM +ve cells were shown positive signals for CK18 and albumin.

CONCLUSION: Our study suggests that these EpCAM +ve cells can be used as hepatic progenitors for cell transplantation with a minimum risk of alloreactivity and these cells may serve as a potential source for enrichment of hepatic progenitor.

Noninvasive prediction of HCC with progenitor phenotype based on gadoxetic acid-enhanced MRI

OBJECTIVES

To explore the noninvasive prediction of hepatocellular carcinoma (HCC) with progenitor phenotype based on gadoxetic acid-enhanced magnetic resonance imaging (MRI).

METHODS

This retrospective study included 115 surgery-proven HCCs with preoperative gadoxetic acid-enhanced MRI from August 2015 to September 2018. Image features were reviewed. Quantitative image analysis was performed using histogram analysis. HCC with progenitor phenotype was defined as positive for either cytokeratin 19 (CK19) or epithelial cell adhesion molecule (EpCAM) expression. Statistically significant variables for identifying HCCs with progenitor phenotype were determined at multivariate analyses. ROC analyses were used to determined cutoff values and the diagnostic performance of significant variables and combinations. Prediction nomogram was constructed based on multivariate analysis.

RESULTS

At multivariate regression analyses, AFP ≥ 155.25 ng/mL (p < 0.001), skewness on T2WI ≤ 1.10 (p = 0.024), uniformity on pre-T1WI ≤ 0.91 (p = 0.024), irregular tumor margin (p = 0.006), targetoid appearance (p = 0.001), and the absence of mosaic architecture (p = 0.014) were significant predictors of HCCs expressing progenitor cell markers. Combing any three of those significant variables, it provides a diagnostic accuracy of 0.86 (95% CI 0.78-0.92) with sensitivity of 0.97 (95% CI 0.86-1.00), and specificity of 0.74 (95% CI 0.63-0.83). The C-index of the regression coefficient-based nomogram was 0.94 (95% CI 0.91-0.98).

CONCLUSIONS

Noninvasive prediction of HCCs with progenitor phenotype can be achieved with high accuracy by integrated interpretation of biochemical and radiological information, representing a handy tool for precise patient management and the prediction of prognosis.

KEY POINTS

• Qualitative image features of irregular tumor margin, targetoid appearance, and the absence of mosaic architecture are significant predictors of hepatocellular carcinoma with progenitor phenotype. • Quantitative analyses using whole-lesion histogram analysis provides additional information for the prediction of hepatocellular carcinoma with progenitor phenotype. • Noninvasive prediction of hepatocellular carcinoma with progenitor phenotype can be achieved with high accuracy by integrated interpretation of clinical information and qualitative and quantitative imaging analyses.

Overexpression of the epithelial cell adhesion molecule is associated with a more favorable prognosis and response to platinum-based chemotherapy in ovarian cancer

OBJECTIVE

Epithelial cell adhesion molecule (EpCAM) has experienced a renaissance lately as a binding site for targeted therapy as well as a prognostic marker in epithelial malignancies. Aim of this study was to study EpCAM as a potential prognostic marker in epithelial ovarian cancer (EOC).

METHODS

EpCAM expression was assessed by immunohistochemistry on paraffin-embedded primary EOC-tissue samples. EpCAM overexpression was defined as an expression of EpCAM of 76% to 100%. Tissue samples and clinical data were systematically collected within the international and multicenter "Tumorbank Ovarian Cancer" network.

RESULTS

Seventy-four patients, diagnosed with EOC between 1994 and 2009, were included in the study (median age, 56 years; range, 31 to 86 years). The majority of the patients (81.1%) presented with an advanced stage International Federation of Gynecology and Obstetrics (FIGO) III/IV disease. Histology was of the serous type in 41 patients (55.4%), endometrioid in 19 (25.6%), and mucinous in 14 (19%). EpCAM was overexpressed in 87.7%. Serous tumors overexpressed EpCAM significantly more often than mucinous tumors (87.8% vs. 78.6%, p=0.045); while no significant difference was noted between the other histological subgroups. EpCAM overexpression was significantly associated with a better progression free survival and higher response rates to platinum based chemotherapy (p=0.040 and p=0.048, respectively). EpCAM was identified as an independent prognostic marker for overall survival (p=0.022).

CONCLUSION

Our data indicate a significant association of EpCAM overexpression with a more favorable survival in EOC-patients. Serous cancers showed a significant EpCAM overexpression compared to mucinous types. Larger multicenter analyses are warranted to confirm these findings.

Tufting Enteropathy with EpCAM Mutations in Two Siblings

Tufting enteropathy is a rare autosomal recessive disorder presenting with early-onset severe intractable diarrhea. The epithelial cell adhesion molecule gene (EpCAM) has recently been identified as the gene responsible for tufting enteropathy. Based on histology, a diagnosis of tufting enteropathy was made in two Korean siblings. They developed chronic diarrhea and failure to thrive. They had a broad nasal bridge and micrognathia. Duodenal and colonic biopsies showed villous atrophy, disorganization of surface enterocytes, and focal crowding resembling tufts. Protracted diarrhea continued and so cyclic parenteral nutrition was supplied. The sister had juvenile rheumatoid arthritis. Mutation analysis of EpCAM identified two compound heterozygous mutations in these siblings: 1) a donor splicing site mutation in intron 5 (c.491+1G>A) and 2) a novel nonsense mutation in exon 3 (c.316A>T, Lys106X). Analysis of EpCAM will be useful for genetic counseling and prenatal diagnosis of tufting enteropathy.

EpCAM+ Liver Cancer Stem-Like Cells Exhibiting Autocrine Wnt Signaling Potentially Originate in Cirrhotic Patients

Hepatocellular carcinoma (HCC) is believed to originate from cancer stem cells (CSCs). While epithelial cell adhesion molecule (EpCAM) is a marker of normal hepatic stem cells (HSCs), EpCAM+ cells from HCC behave like CSCs. Since HCC mostly develops on a cirrhotic background, we sought to determine whether CSC‐like EpCAM+ cells exist in patients with advanced cirrhosis. Both flow cytometry and immunohistochemistry showed that frequency of EpCAM+ cells in advanced cirrhosis was increased as compared to control. To determine whether increased EpCAM population in advanced cirrhosis harbors any CSC‐like cells, we compared molecular and functional features of EpCAM+ cells from advanced cirrhosis (Ep+CIR; n = 20) with EpCAM+ cells from both HCC (Ep+HCC; n = 20) and noncancerous/noncirrhotic (control) (Ep+NSC; n = 7) liver tissues. Ep+CIRs displayed similarity with Ep+HCC cells including upregulated expression of stemness and Notch pathway genes, enhanced self‐renewal in serial spheroid assay and generation of subcutaneous tumors in nonobese diabetic/severe combined immunodeficiency mice. Moreover, transcriptome and miRNome of Ep+CIRs appeared closer to that of Ep+HCC cells than Ep+NSCs. Interestingly, more than 50% micro RNAs (miRNAs) and transcripts specifically expressed in Ep+HCCs were also expressed in Ep+CIRs. However, none of Ep+NSC specific miRNAs and only 7% Ep+NSC specific transcripts were expressed in Ep+CIRs. Further, according to gene expression and in vitro Wnt inhibition analysis, autocrine Wnt signaling appeared to be a distinct feature of Ep+CIR and Ep+HCC cells, which was absent from Ep+NSCs. EpCAM+ cells in advanced cirrhosis possibly include a population of CSC‐like cells which can be explored for early diagnosis of HCC development. Stem Cells Translational Medicine2017;6:807–818

EpCAM cellular functions in adhesion and migration, and potential impact on invasion: A critical review

EpCAM has long been known as a cell surface protein highly expressed in carcinomas. It has since become one of the key cancer biomarkers. Despite its high fame, its actual role in cancer development is still controversial. Beyond a flurry of correlative studies, which point either to a positive or a negative link with tumour progression, there has been surprisingly few studies on the actual cellular mechanisms of EpCAM and on their functional consequences. Clearly, EpCAM plays multiple important roles, in cell proliferation as well as in cell adhesion and migration. The two latter functions, directly relevant for metastasis, are the focus of this review. We attempt here to bring together the available experimental data to build a global coherent view of EpCAM functions. We also include in this overview EpCAM2/Trop2, the close relative of EpCAM. At the core of EpCAM (and EpCAM2/Trop2) function stands the ability to repress contractility of the actomyosin cell cortex. This activity appears to involve direct inhibition by EpCAM of members of the novel PKC family and of a specific downstream PKD-Erk cascade. We will discuss how this activity can result in a variety of adhesive and migratory phenotypes, thus potentially explaining at least part of the apparent inconsistencies between different studies. The picture remains fragmented, and we will highlight some of the conflicting evidence and the many unsolved issues, starting with the controversy around its original description as a cell-cell adhesion molecule.

Research progress and prospects of markers for liver cancer stem cells

Liver cancer is a common malignancy and surgery is the main treatment strategy. However, the prognosis is still poor because of high frequencies of postoperative recurrence and metastasis. In recent years, cancer stem cell (CSC) theory has evolved with the concept of stem cells, and has been applied to oncological research. According to cancer stem cell theory, liver cancer can be radically cured only by eradication of liver cancer stem cells (LCSCs). This notion has lead to the isolation and identification of LCSCs, which has become a highly researched area. Analysis of LCSC markers is considered to be the primary method for identification of LCSCs. Here, we provide an overview of the current research progress and prospects of surface markers for LCSCs.

EpCAM-based assays for epithelial tumor cell detection in cerebrospinal fluid

The diagnosis of leptomeningeal metastases (LM) of solid tumors is complicated due to low sensitivities of both magnetic resonance imaging (MRI) and cytology. MRI has a sensitivity of 76% for the diagnosis of LM and cerebrospinal fluid (CSF) cytology has a sensitivity of 44-67% at first lumbar puncture which increases to 84-91% upon second CSF sampling. Epithelial cell adhesion molecule (EpCAM) is expressed by solid tumors of epithelial origin like non-small-cell lung cancer, breast cancer or ovarium cancer. Recently, a CELLSEARCH^® assay and flow cytometry laboratory techniques have been developed to detect circulating tumor cells (CTCs) of epithelial origin in CSF. These laboratory techniques are based on capture antibodies labelled with different fluorescent tags against EpCAM. In this review, we provide an overview of the available laboratory techniques and diagnostic accuracy for tumor cell detection in CSF. The reported sensitivities of the EpCAM-based CTC assays for the diagnosis of LM across the different studies are highly promising and vary between 76 and 100%. An overview of the different EpCAM-based techniques for the enumeration of CTCs in the CSF is given and a comparison is made with CSF cytology for the diagnoses of LM from epithelial tumors.

Silencing of EPCAM suppresses hepatic fibrosis and hepatic stellate cell proliferation in mice with alcoholic hepatitis via the PI3K/Akt/mTOR signaling pathway

Alcoholic hepatitis (AH) is a severe condition developed in patients with underlying alcoholic liver disease. Epithelial cell adhesion molecule (EPCAM) plays a role in hepatitis. Therefore, the current study aimed to explore the effect of EPCAM and its potential mechanism in AH. Bioinformatic analysis was performed to screen differentially expressed genes associated with AH. AH mouse models were established through a Lieber-DeCarli liquid diet containing 4% ethanol, which were co-treated with siRNA against EPCAM or the PI3K/Akt/mTOR signaling pathway inhibitor in order to investigate the effects of EPCAM and the PI3K/Akt/mTOR signaling pathway on hepatic fibrosis, hepatic stellate cell (HSC) proliferation and apoptosis. The relationship between EPCAM and the PI3K/Akt/mTOR signaling pathway was investigated for the purposes of elucidating the potential mechanism of EPCAM in AH. EPCAM was predicted to regulate AH progression through the PI3K/Akt/mTOR signaling pathway. Silencing EPCAM or inhibition of the PI3K/Akt/mTOR signaling pathway inhibited the hepatic fibrosis and HSC proliferation yet induced HSC apoptosis. Moreover, silencing EPCAM was found to repress the PI3K/Akt/mTOR signaling pathway as evidenced by decreased levels of Bcl2 yet increased levels of caspase-3. Collectively, silencing EPCAM could hinder AH progression by inhibiting the PI3K/Akt/mTOR signaling pathway, which might serve as a potential therapeutic target for AH treatment.

Fluorescence-guided tumor detection with a novel anti-EpCAM targeted antibody fragment: Preclinical validation

Tumor-specific fluorescent imaging agents are moving towards the clinic, supporting surgeons with real-time intraoperative feedback about tumor locations. The epithelial cell adhesion molecule (EpCAM) is considered as one of the most promising tumor-specific proteins due its high overexpression on epithelial-derived cancers. This study describes the development and evaluation of EpCAM-F800, a novel fluorescent anti-EpCAM antibody fragment, for intraoperative tumor imaging. Fab production, conjugation to the fluorophore IRDye 800CW, and binding capacities were determined and validated using HPLC, spectrophotometry and cell-based assays. In vivo, dose escalation-, blocking-, pharmacokinetic- and biodistribution studies (using both fluorescence and radioactivity) were performed, next to imaging of clinically relevant orthotopic xenografts for breast and colorectal cancer. EpCAM-F800 targets EpCAM with high specificity in vitro, which was validated using in vivo blocking experiments with a 10x higher dose of unlabeled Fab. The optimal dose range for fluorescence tumor detection in mice was 1-5 nmol (52-260 μg), which corresponds to a human equivalent dose of 0.2-0.8 mg/kg. Biodistribution showed high accumulation of EpCAM-F800 in tumors and metabolizing organs. Breast and colorectal tumors could clearly be visualized within 8 h post-injection and up to 96 h, while the agent already showed homogenous tumor distribution within 4 h. The blood half-life was 4.5 h. This study describes the development and evaluation of a novel EpCAM-targeting agent and the feasibility to visualize breast and colorectal tumors by fluorescence imaging during resections. EpCAM-F800 will be translated for clinical use, considering its abundance in a broad range of tumor types.

Downregulation of cytokeratin 18 induces cellular partial EMT and stemness through increasing EpCAM expression in breast cancer

Induction of epithelial-mesenchymal transition (EMT) and cancer stem cell (CSC) characteristics underlie the development of metastasis, chemoresistance, and tumor recurrence in breast cancer. Downregulation of cytokeratin 18 (CK18) is a critical molecular event of EMT; however, its importance in the induction of EMT and CSC features has not been defined to date. This study aimed to investigate the biological significance and underlying molecular mechanisms of CK18 in inducing EMT phenotype and stemness properties of breast cancer cells. Three breast cancer cell lines (i.e., non-metastatic MCF-7, highly metastatic MDA-MB-231, and mitoxantrone (MX)-selected resistant MCF-7/MX cells) and two CK18-knockdown stable cell clones (MCF-7-shCK18-7D and 3C) were used to determine the association between CK18 and EMT and stemness. CK18 expression was extremely low in highly metastatic, resistant, and transforming growth factor (TGF)-β1/tumor necrosis factor (TNF)-α-treated breast cancer cells with mesenchymal phenotype and increased expression of CSC markers. Depletion of CK18 promoted partial EMT and the acquisition of stemness properties in breast cancer MCF-7 cells. Mechanistically, CK18 interference in MCF-7 cells activated the Wnt/β-catenin signaling, resulting in the up-regulation of epithelial cell adhesion molecule (EpCAM). Consistently, the stemness properties and metastasis can be attenuated by further knockdown of EpCAM in CK18-depleted cells. In conclusion, downregulation of CK18 promotes partial EMT and enhances breast cancer stemness by increasing EpCAM expression partly via the Wnt/β-catenin pathway. These findings indicate that CK18 may serve as a potential treatment target for advanced breast cancer.

The O-glycosylated ectodomain of FXYD5 impairs adhesion by disrupting cell-cell trans-dimerization of Na,K-ATPase β1 subunits

FXYD5 (also known as dysadherin), a regulatory subunit of the Na,K-ATPase, impairs intercellular adhesion by a poorly understood mechanism. Here, we determined whether FXYD5 disrupts the trans-dimerization of Na,K-ATPase molecules located in neighboring cells. Mutagenesis of the Na,K-ATPase β1 subunit identified four conserved residues, including Y199, that are crucial for the intercellular Na,K-ATPase trans-dimerization and adhesion. Modulation of expression of FXYD5 or of the β1 subunit with intact or mutated β1-β1 binding sites demonstrated that the anti-adhesive effect of FXYD5 depends on the presence of Y199 in the β1 subunit. Immunodetection of the plasma membrane FXYD5 was prevented by the presence of O-glycans. Partial FXYD5 deglycosylation enabled antibody binding and showed that the protein level and the degree of O-glycosylation were greater in cancer than in normal cells. FXYD5-induced impairment of adhesion was abolished by both genetic and pharmacological inhibition of FXYD5 O-glycosylation. Therefore, the extracellular O-glycosylated domain of FXYD5 impairs adhesion by interfering with intercellular β1-β1 interactions, suggesting that the ratio between FXYD5 and α1-β1 heterodimer determines whether the Na,K-ATPase acts as a positive or negative regulator of intercellular adhesion.

TIM-3 blockade combined with bispecific antibody MT110 enhances the anti-tumor effect of γδ T cells

As ideal cells that can be used for adoptive cell therapy, γδ T cells are a group of homogeneous cells with high proliferative and tumor killing ability. However, γδ T cells are apt to apoptosis and show decreased cytotoxicity under persistent stimulation in vitro and cannot aggregate at tumor sites efficiently in vivo, both of which are two main obstacles to tumor adoptive immunotherapy. In this study, we found that the immune checkpoint T-cell immunoglobulin domain and mucin domain 3 (TIM-3) were up-regulated significantly on γδ T cells during their ex vivo expansion and this up-regulation contributed to the dysfunction of γδ T cells. Although the killing ability of γδ T cells against breast cancer cells which exhibited a high level of epithelial cell adhesion molecule (EpCAM) was enhanced, the level of TIM-3 on γδ T cells was also further up-regulated under the application of the bispecific antibody MT110 (anti-CD3 × anti-EpCAM) which can redirect T cells to target cells. Besides, these γδ T cells with up-regulated TIM-3 exhibited an increased susceptibility to apoptosis. By reinvigorating dysfunctional γδ T cells and promoting them to accumulate at tumor sites, the combined use of TIM-3 inhibitor and MT110 could further enhance the anti-tumor effect of the adoptively transfused γδ T cells. These results may have clinical implications for the design of new translational anti-tumor regimens aimed at combining checkpoint blockade and immune cell redirection.

High sensitive detection of circulating tumor cell by multimarker lipid magnetic nanoparticles and clinical verifications

Tumor cells with heterogeneity and diversity can express different markers. At present, positive separation of circulating tumor cells (CTC) taking EpCAM as the marker was used in most cases which could be one-sided, while this study successfully prepared four antibody-modified magnetic immunoliposomes (MIL) by using the self-assembled liposome with antibody derivatives. This study aims to explore the separation efficiency and clinical detection feasibility of single or combined use of MIL with multi-tumor markers on different tumors. Captured CTC were stained with CK-FITC, CD45-PE and DAPI, and fluorescence microscope was used for the observation, analysis and calculation. The result indicated that the CTC number positive rate in blood samples of four different magnetic balls on the same patient could be up to 87.5% in 32 patients with 14 different kinds tumors. While the effect of directly mixed separation by four kinds of magnetic balls was not satisfying. It suggested that the MIL of multi-tumor markers could be a powerful tool for CTC separation in application of tumor screening and prognosis.

Role of CD56-expressing immature biliary epithelial cells in biliary atresia

AIM: To analyze the clinical and pathological parameters and expression of the neural cell adhesion molecule (CD56) in patients with biliary atresia (BA).

METHODS: Established clinical laboratory markers of hepatic function, including enzyme activity, protein synthesis, and bilirubin metabolism, were evaluated in patients with BA and compared with those in patients with choledochal cysts and neonatal hepatitis. Pathological changes in tissue morphology and fibrosis were examined by histological and tissue collagen staining. Immunohistochemical staining for the biliary epithelial cell markers CD56 and CK19 together with the Notch signaling related molecules Notch1 and Notch2 was performed in the context of alterations in the structure of intrahepatic biliary ducts.

RESULTS: Differences in some clinical laboratory parameters among the three diseases examined were observed, but they did not correlate with the pathological classification of fibrosis in BA. Immunohistochemical staining showed the presence of CD56-positive immature bile ducts in most patients (74.5%) with BA but not in patients with choledochal cysts or neonatal hepatitis. The number of CD56-expressing cells correlated with disease severity, with more positive cells present in the later stages of liver damage (81.8% vs 18.2%). Furthermore, bile plugs were mainly found in CD56-positive immature biliary ducts. Notch signaling was a key regulatory pathway in biliary duct formation and played a role in tissue fibrosis. Notch1 was co-expressed in CD56-positive cells, whereas Notch2 was found exclusively in blood vessels in the portal area of patients with BA.

CONCLUSION: The maturation of biliary epithelial cells and the expression of Notch may play a role in the pathogenesis of BA.