Epithelial cell adhesion molecule promotes breast cancer resistance protein-mediated multidrug resistance in breast cancer by inducing partial epithelial-mesenchymal transition.

Overexpression of breast cancer resistance protein (BCRP) plays a crucial role in the acquired multidrug resistance (MDR) in breast cancer. The elucidation of molecular events that confer BCRP-mediated MDR is of major therapeutic importance in breast cancer. Epithelial cell adhesion molecule (EpCAM) has been implicated in tumor progression and drug resistance in various types of cancers, including breast cancer. However, the role of EpCAM in BCRP-mediated MDR in breast cancer remains unknown. In the present study, we revealed that EpCAM expression was upregulated in BCRP-overexpressing breast cancer MCF-7/MX cells, and EpCAM knockdown using siRNA reduced BCRP expression and increased the sensitivity of MCF-7/MX cells to mitoxantrone (MX). The epithelial-mesenchymal transition (EMT) promoted BCRP-mediated MDR in breast cancer cells, and EpCAM knockdown partially suppressed EMT progression in MCF-7/MX cells. In addition, Wnt/ß-catenin signaling was activated in MCF-7/MX cells, and the inhibition of this signaling attenuated EpCAM and BCRP expression and partially reversed EMT. Together, this study illustrates that EpCAM upregulation by Wnt/ß-catenin signaling induces partial EMT to promote BCRP-mediated MDR resistance in breast cancer cells. EpCAM may be a potential therapeutic target for overcoming BCRP-mediated resistance in human breast cancer.

Expression and function of epithelial cell adhesion molecule EpCAM: where are we after 40 years?

EpCAM (epithelial cell adhesion molecule) was discovered four decades ago as a tumor antigen on colorectal carcinomas. Owing to its frequent and high expression on carcinomas and their metastases, EpCAM serves as a prognostic marker, a therapeutic target, and an anchor molecule on circulating and disseminated tumor cells (CTCs/DTCs), which are considered the major source for metastatic cancer cells. Today, EpCAM is reckoned as a multi-functional transmembrane protein involved in the regulation of cell adhesion, proliferation, migration, stemness, and epithelial-to-mesenchymal transition (EMT) of carcinoma cells. To fulfill these functions, EpCAM is instrumental in intra- and intercellular signaling as a full-length molecule and following regulated intramembrane proteolysis, generating functionally active extra- and intracellular fragments. Intact EpCAM and its proteolytic fragments interact with claudins, CD44, E-cadherin, epidermal growth factor receptor (EGFR), and intracellular signaling components of the WNT and Ras/Raf pathways, respectively. This plethora of functions contributes to shaping intratumor heterogeneity and partial EMT, which are major determinants of the clinical outcome of carcinoma patients. EpCAM represents a marker for the epithelial status of primary and systemic tumor cells and emerges as a measure for the metastatic capacity of CTCs. Consequentially, EpCAM has reclaimed potential as a prognostic marker and target on primary and systemic tumor cells.

Cytoplasmic expression of B7-H3 and membranous EpCAM expression are associated with higher grade and survival outcomes in patients with clear cell renal cell carcinoma.

B7-H3 and EpCAM are overexpressed in cancer and play a role in tumorigenesis and metastasis. In this study, the membranous, cytoplasmic and nuclear expression levels of B7-H3 and EpCAM biomarkers were mapped in three major subtypes of renal cell carcinoma (RCC). Expression of B7-H3 and EpCAM were evaluated using immunohistochemistry in RCC samples on tissue microarrays (TMAs), including clear cell RCCs (ccRCCs), type I and II papillary RCCs (pRCCs), and chromophobe RCCs (chRCCs). The association between B7-H3 and EpCAM expression and clinicopathological features as well as survival outcomes was determined. There was a statistically significant difference between B7-H3 and EpCAM expression among the different RCC subtypes. In ccRCC, higher cytoplasmic expression of B7-H3 was significantly associated with increase in nucleolar grade, lymph node invasion (LNI), invasion of the Gerota's fascia, and tumor necrosis, while no association was found with the membranous and nuclear expression. Moreover tumors with cytoplasmic expression of B7-H3 tended to have a worse prognosis for disease-specific survival (DSS) than those with membranous expression. In case of EpCAM, increased membranous expression of EpCAM was associated with nucleolar grade and tumor necrosis in ccRCC. Additionally, membranous EpCAM expression added prognostic value in patients with ccRCC who had high nucleolar grade versus low nucleolar grade. Moreover, membranous EpCAM expression was found to be an independent favorable prognostic marker for progression-free survival (PFS) in ccRCC. Our results demonstrated that higher cytoplasmic B7-H3 and membranous EpCAM expression are clinically significant in ccRCC and are associated with more aggressiveness tumor behavior.

Detection of epithelial specific cell adhesion molecules in colon cancer and the correlation with clinical and pathological characteristics EpCAM expression in colon cancer.

AIM: The aim of this study was to evaluate the correlation between EpCAM expression in colon cancer tissue and the clinico-pathological characteristics of the patients. MATERIAL AND METHODS: This is a prospective, longitudinal, observational study on 80 patients undergoing for colon cancer between January - December 2017. EpCAM expression at tumoral level was analyzed in relation with clinical and pathological variables of the patients using anti-EpCAM specific antibody. RESULTS: EpCAM expression was predominant in tumoral tissue compared to normal colonic mucosa and most of the cases (58.7%) showed increased EpCAM expression. Although increased EpCAM expression was observed in advanced stages and in patients with advanced locoregional disease, there was no statistically significant correlation with the clinical and pathological characteristics of the patients. DISCUSSION: The majority of the analyzed samples showed increased EpCAM expression in tumoral tissue suggesting its involvement in the carcinogenesis process. Numerous studies have identified EpCAM overexpression in colon cancer as a negative prognostic factor, being associated with advanced stage of the disease and a poor prognosis of the patient but results are inconsistent. Nevertheless, assessing a possible correlation between EpCAM expression at tumoral level and clinico- pathological characteristics is dependent on the type of antibody used to identify the molecule of interest. CONCLUSIONS: EpCAM detection in colon cancer using anti-human CD326/EpCAM clone VU-1D9 does not allow the correlation between its expression and the clinico-pathological characteristics of the patients and it should only be used for EpCAM identification in colon cancer tissues. KEY WORDS: Cancer, Colon, EpCAM, Immunohistochemistry.

A meta-analysis and The Cancer Genome Atlas data of prostate cancer risk and prognosis using epithelial cell adhesion molecule (EpCAM) expression.

BACKGROUND: Epithelial cell adhesion molecule (EpCAM) expression has been reported in many types of cancer, including prostate cancer (PCa). However, the role of EpCAM expression remains inconsistent. We conducted a meta-analysis to assess the clinicopathological and prognostic significance of EpCAM expression in PCa. METHODS: Publications were searched online using electronic databases. The available data were obtained from The Cancer Genome Atlas (TCGA). The odds ratios (ORs) or hazard ratios (HRs) with their 95% confidence intervals (CIs) were calculated. RESULTS: We identified seven studies in which immunohistochemistry was used and that included 871 prostatic tissue samples. EpCAM expression was significantly higher in PCa samples than in benign and normal tissue samples (OR = 77.93, P = 0.002; OR = 161.61, P <  0.001; respectively). No correlation of EpCAM overexpression with pT stage and lymph node metastasis was observed; however, EpCAM overexpression showed a significant correlation with Gleason score (OR = 0.48, P = 0.012) and bone metastasis (OR = 145.80, P <  0.001). Furthermore, TCGA data showed that EpCAM overexpression was not closely correlated with age, pT stage, lymph node metastasis, number of lymph node, prostate-specific antigen level, Gleason score, biochemical recurrence, and overall survival. Based on multivariate Cox proportional-hazards regression analysis, a significant correlation was observed between EpCAM overexpression and 5-year worse biochemical recurrence free-survival. CONCLUSIONS: EpCAM overexpression may be correlated with the development of bone metastasis and worse biochemical recurrence free-survival of PCa. Further studies are needed to verify these findings.

Single-cell transcriptomics reveals the landscape of intra-tumoral heterogeneity and stemness-related subpopulations in liver cancer.

Hepatocellular carcinoma (HCC) is heterogeneous, rendering its current curative treatments ineffective. The emergence of single-cell genomics represents a powerful strategy in delineating the complex molecular landscapes of cancers. In this study, we demonstrated the feasibility and merit of using single-cell RNA sequencing to dissect the intra-tumoral heterogeneity and analyze the single-cell transcriptomic landscape to detect rare cell subpopulations of significance. Exploration of the inter-relationship among liver cancer stem cell markers showed two distinct major cell populations according to EPCAM expression, and the EPCAM+ cells had upregulated expression of multiple oncogenes. We also identified a CD24+/CD44+-enriched cell subpopulation within the EPCAM+ cells which had specific signature genes and might indicate a novel stemness-related cell subclone in HCC. Notably, knockdown of signature gene CTSE for CD24+/CD44+ cells significantly reduced self-renewal ability on HCC cells in vitro and the stemness-related role of CTSE was further confirmed by in vivo tumorigenicity assays in nude mice. In summary, single-cell genomics is a useful tool to delineate HCC intratumoral heterogeneity at better resolution. It can identify rare but important cell subpopulations, and may guide better precision medicine in the long run.

A microwell array platform to print and measure biomolecules produced by single cells.

Here we describe a combined method to monitor the secretion of molecules produced by single cells, followed by a method to isolate the individual cells that produced these molecules. The method is based on a self-sorting microwell chip that is connected to an activated membrane that collects the produced molecules. The produced molecules are printed by diffusion in small spots onto the membrane. The location of the printed spots can be correlated to the microwell number and the cell that produced these molecules. To demonstrate the method, we used the EpCAM antibody producing hybridoma cell line VU1D9 and a genetically engineered CHO cell-line producing Her2. VU1D9 cells produced 4.6 ± 5.6 pg (mean ± SD) of EpCAM antibody per 24 h and CHO cells 6.5 ± 8.2 pg per 24 h of Herceptin antibody.

In situ fluorescent profiling of living cell membrane proteins at a single-molecule level.

We propose a signal amplification method that enables visualization analysis of membrane proteins on living cells at a single-molecule level. Using the proposed method, we achieved imaging of PTK7 membrane proteins on HeLa cells and analyzed the down-regulated expression of EpCAM on the MCF-7 cell surface during epithelial-mesenchymal transition (EMT).

A phenotypical map of disseminated hepatocellular carcinoma suggests clonal constraints in metastatic sites.

AIMS: Access to tissue in patients with hepatocellular carcinoma (HCC) is limited compared to other malignancies, particularly at advanced stages. This has precluded a thorough characterisation of molecular drivers of HCC dissemination, particularly in relation to distant metastases. Biomarker assessment is restricted to early stages, and paired primary-metastatic comparisons between samples from the same patient are difficult. METHODS AND RESULTS: We report the evaluation of 88 patients with HCC who underwent autopsy, including multiregional sampling of primary and metastatic sites totalling 230 nodules analysed. The study included morphological assessment, immunohistochemistry and mutation status of the TERT promoter, the most frequently mutated gene in HCC. We confirm a strong predilection of HCC for lung dissemination, including subclinical micrometastases (unrecognised during imaging and macroscopic examinations) in 30% of patients with disseminated disease. Size of dominant tumour nodule; multinodularity; macrovascular invasion; high histological, nuclear and architectural grades; and cellular crowding were associated with the presence of extrahepatic metastasis. Among the immunohistochemistry markers tested, metastatic nodules had significantly higher K19 and EpCAM expression than primary liver tumours. Morphological and immunohistochemical features showed that metastatic HCC could be traced back to the primary tumour, sometimes to a specific hepatic nodule. CONCLUSIONS: This study suggests limited heterogeneity in metastatic sites compared to primary tumour sites.

EpCAM homo-oligomerization is not the basis for its role in cell-cell adhesion.

Cell-surface tumor marker EpCAM plays a key role in proliferation, differentiation and adhesion processes in stem and epithelial cells. It is established as a cell-cell adhesion molecule, forming intercellular interactions through homophilic association. However, the mechanism by which such interactions arise has not yet been fully elucidated. Here, we first show that EpCAM monomers do not associate into oligomers that would resemble an inter-cellular homo-oligomer, capable of mediating cell-cell adhesion, by using SAXS, XL-MS and bead aggregation assays. Second, we also show that EpCAM forms stable dimers on the surface of a cell with pre-formed cell-cell contacts using FLIM-FRET; however, no inter-cellular homo-oligomers were detectable. Thus, our study provides clear evidence that EpCAM indeed does not function as a homophilic cell adhesion molecule and therefore calls for a significant revision of its role in both normal and cancerous tissues. In the light of this, we strongly support the previously suggested name Epithelial Cell Activating Molecule instead of the Epithelial Cell Adhesion Molecule.

The expression of circulating tumor cells in peripheral blood of patients with non-small cell lung cancer and its detection.

This study aimed to investigate the expression of circulating tumor cells (CTCs) in peripheral blood and relevant detection methods as well as the clinical values of determination of CTCs for the diagnosis of non-small cell lung cancer (NSCLC). Peripheral blood specimens were acquired from the patients with NSCLC who came to the Thoracic Surgery Department of Jining No.1 People’s Hospital, Shandong, China for the first visit between January 2015 and November 2016. Whether there was metastasis of CTCs or not was determined by detecting the number of epithelial cell adhesion molecules (EpCAM) which had expression in the CTCs of the peripheral blood with fluorescence polymerase chain reaction. Moreover, the correlation between the expression level of EpCAM of patients with NSCLC during postoperative adjuvant treatment and the efficacy of adjuvant therapy was initially explored. The expression level of EpCAM of the NSCLC patients was remarkably different to that of the patients with benign lung diseases. The expression level of EpCAM of the patients with NSCLC was notably different with that of the healthy volunteers. The expression level of EpCAM of the patients with NSCLC was much higher than that of patients with benign lung diseases and the volunteers. Moreover, the expression level of NSCLC at stages I, II and IIIA had significant differences; the expression level of EpCAM tended to increase as the stage of NSCLC developed. The expression level of EpCAM in CTCs of peripheral blood can be regarded as a reference for the early diagnosis and detection of NSCLC before and after surgery.

Quercetin Inhibits Breast Cancer Stem Cells via Downregulation of Aldehyde Dehydrogenase 1A1 (ALDH1A1), Chemokine Receptor Type 4 (CXCR4), Mucin 1 (MUC1), and Epithelial Cell Adhesion Molecule (EpCAM).

BACKGROUND Quercetin, nature's most common flavonoid, possesses anticarcinogenic properties against various forms of cancer. The aim of this study was to investigate the effect of quercetin on breast cancer stem cells in the MDA-MB-231 cell line, and to elucidate the possible mechanisms for those effects. MATERIAL AND METHODS We evaluated breast cancer stem cell proliferation, clone generation, and mammosphere formation to determine the effect of quercetin treatment on breast cancer stem cells. RESULTS In our study, quercetin suppressed breast cancer stem cell proliferation, self-renewal, and invasiveness. It also lowered the expression levels of proteins related to tumorigenesis and cancer progression, such as aldehyde dehydrogenase 1A1, C-X-C chemokine receptor type 4, mucin 1, and epithelial cell adhesion molecules. CONCLUSIONS These results indicate that quercetin targets and destroys breast cancer stem cells, making it a potential novel drug in the fight against cancer.

High expression of MAGE-A9 contributes to stemness and malignancy of human hepatocellular carcinoma.

MAGE-A9, a well-characterized cancer testis antigen (CTA), belongs to a member of melanoma antigen gene (MAGE) family. In human malignancies, aberrant expression of MAGE genes correlated with poor clinical prognosis, increased tumor growth, metastases, and enrichment in stem cell populations of certain cancers. Cancer stem cells (CSCs) have been proposed to contribute to the major malignant phenotypes of liver cancer, including recurrence, metastasis and chemoresistance. However, expression and potential role of MAGE-A9 in liver cancer stem cells (LCSCs) still remain unclear. In the present study, we first analyzed the expression profiling of MAGE family genes in EpCAM+ and EpCAM- human hepatocellular carcinoma (HCC), based on public Gene Expression Omnibus (GEO) database. Among these examined MAGE members, MAGE-A9 is the only one with significantly higher expression in EpCAM+ HCC specimens as compared with EpCAM- HCC. Quantitative PCR analysis further confirmed that MAGE-A9 expression significantly elevated in a subtype of HCC patients that had features of hepatic stem/progenitor cells with high-level expression of EpCAM and α-fetoprotein (AFP). Moreover, MAGE-A9 displayed remarkably enriched expression in EpCAM+ HCC cells that were sorted by fluorescence-activated cell sorting and cultured HCC cell spheroids with characteristics of stem/progenitor cells. Functional experiments further revealed that MAGE-A9 overexpression promoted cell proliferation, colony formation, migration, chemoresistance, and tumorigenicity in the context of EpCAM+ HCC cells, whereas MAGE-A9 knockdown significantly inhibited anchorage-dependent and spheroid colony formation and in vivo tumorigenicity. Collectively, these data demonstrate that MAGE-A9 functions as an important regulator of LCSCs, and MAGE-A9 may serve as a potential therapeutic target against HCC stem/progenitor cells.

LncRNATCF7 promotes the growth and self-renewal of glioma cells via suppressing the miR-200c-EpCAM axis.

Accumulating evidence has demonstrated that long non-coding RNAs (lncRNAs) are involved in tumor initiation and development. Recent studies illustrated that lncRNATCF7 was highly expressed in lung cancer and liver cancer, however, the expression pattern and function of lncRNATCF7 in glioma remains to be elucidated. Here, we found that lncTCF7 was highly expressed in glioma tissues and cell lines. Overexpression of lncTCF7 promoted the proliferation and migration of glioma cells. Down-regulation of lncTCF7 significantly suppressed the tumorigenesis of glioma. Mechanistically, lncTCF7 enhanced the self-renewal of glioma cells via up-regulating the expression of epithelial cell adhesion molecule (EpCAM). The detailed molecular mechanism uncovered that lncTCF7 bound to miR-200c and decreased the abundance of miR-200c, which consequently attenuated the negative regulation of miR-200c on EpCAM. Collectively, these data provide evidence to demonstrate the critical role of lncTCF7 in the tumorigeneis of glioma, which suggested that lncTCF7 might be a promising target in the treatment of glioma.

Fraction of MHCII and EpCAM expression characterizes distal lung epithelial cells for alveolar type 2 cell isolation.

BACKGOUND: Alveolar type 2 (AT2) cells play important roles in maintaining adult lung homeostasis. AT2 cells isolated from the lung have revealed the cell-specific functions of AT2 cells. Comprehensive molecular and transcriptional profiling of purified AT2 cells would be helpful for elucidating the underlying mechanisms of their cell-specific functions. To enable the further purification of AT2 cells, we aimed to discriminate AT2 cells from non-AT2 lung epithelial cells based on surface antigen expression via fluorescence activated cell sorting (FACS). METHODS: Single-cell suspensions obtained from enzymatically digested murine lungs were labeled for surface antigens (CD45/CD31/epithelial cell adhesion molecule (EpCAM)/ major histocompatibility complex class II (MHCII)) and for pro-surfactant protein C (proSP-C), followed by FACS analysis for surface antigen expression on AT2 cells. AT2 cells were sorted, and purity was evaluated by immunofluorescence and FACS. This newly developed strategy for AT2 cell isolation was validated in different strains and ages of mice, as well as in a lung injury model. RESULTS: FACS analysis revealed that EpCAM+ epithelial cells existed in 3 subpopulations based on EpCAM and MHCII expression: EpCAMmedMHCII+ cells (Population1:P1), EpCAMhiMHCII- cells (P2), and EpCAMlowMHCII- cells (P3). proSP-C+ cells were enriched in P1 cells, and the purity values of the sorted AT2 cells in P1 were 99.0% by immunofluorescence analysis and 98.0% by FACS analysis. P2 cells were mainly composed of ciliated cells and P3 cells were composed of AT1 cells, respectively, based on the gene expression analysis and immunofluorescence. EpCAM and MHCII expression levels were not significantly altered in different strains or ages of mice or following lipopolysaccharide (LPS)-induced lung injury. CONCLUSIONS: We successfully classified murine distal lung epithelial cells based on EpCAM and MHCII expression. The discrimination of AT2 cells from non-AT2 epithelial cells resulted in the isolation of pure AT2 cells. Highly pure AT2 cells will provide accurate and deeper insights into the cell-specific mechanisms of alveolar homeostasis.

EpCAM Expression in Lymph Node Metastases of Urothelial Cell Carcinoma of the Bladder: A Pilot Study.

In this retrospective pilot study, the feasibility of the epithelial cell adhesion molecule (EpCAM) as an imaging target for lymph node (LN) metastatic disease of urothelial cell carcinoma (UCC) of the bladder was investigated. LN metastases and LNs without metastases of patients who underwent pelvic lymph node dissection because of muscle invasive bladder cancer (MIBC) were used. Primary tumors of the same patients were used from cystectomy specimen, transurethral resections, and biopsies. A pathologist, blinded to clinical data, scored EpCAM immunoreactivity. This method determines a total immunostaining score, which is the product of a proportion score and an intensity score. EpCAM expression was observed in 19/20 (95%) LNs with UCC metastases and in 11/12 (92%) of the primary tumors. EpCAM expression was absent in 14/14 (100%) LNs without metastases. Median EpCAM expression (TIS) in LN metastases was 5 (IQR 2.0-8.0) and in the primary tumors 6 (IQR 2.3-11.0). Based on the absence of staining in LNs without metastases, EpCAM show high tumor distinctiveness. EpCAM seems to be a feasible imaging target in LN metastases of UCC of the bladder. Pre- and perioperative visualization of these metastases will improve disease staging and improve the complete resection of LN metastases in MIBC.

A double-negative feedback loop between EpCAM and ERK contributes to the regulation of epithelial-mesenchymal transition in cancer.

Epithelial-mesenchymal transition (EMT) is an important biological process that has been implicated in cancer metastasis. Epithelial cell adhesion molecule (EpCAM) is expressed at the basolateral membrane of most normal epithelial cells but is overexpressed in many epithelial cancers. In our studies on the role of EpCAM in cancer biology, we observed that EpCAM expression is decreased in mesenchymal-like primary cancer specimens in vivo and following induction of EMT in cancer cell lines in vitro. Extracellular signal-related kinase (ERK) is a key regulator of EMT. We observed that EpCAM expression is decreased with activation of the ERK pathway in primary cancer specimens in vivo and in cancer cell lines in vitro. In experimental models, growth factor stimulation and/or oncogene-induced ERK2 activation suppressed EpCAM expression, whereas genetic or pharmacological inhibition of the ERK pathway restored EpCAM expression. In detailed studies of the EpCAM promoter region, we observed that ERK2 suppresses EpCAM transcription directly by binding to a consensus ERK2-binding site in the EpCAM promoter and indirectly through activation of EMT-associated transcription factors SNAI1, SNAI2, TWIST1 and ZEB1, which bind to E-box sites in the EpCAM promoter. Surprisingly, EpCAM appears to modulate ERK activity. Using multiple cell lines, we demonstrated that specific ablation of EpCAM resulted in increased ERK pathway activity and SNAI2 expression, migration and invasion, whereas forced expression of EpCAM resulted in decreased ERK pathway activity and SNAI2 expression, migration and invasion. These observations provide important insights into the regulation of EpCAM expression during EMT, demonstrate an unexpected role for EpCAM in the regulation of ERK and define a novel double-negative feedback loop between EpCAM and ERK that contributes to the regulation of EMT. These studies have important translational implications as both EpCAM and ERK are currently being targeted in human clinical trials.

Intraperitoneal immunotherapy with T cells stably and transiently expressing anti-EpCAM CAR in xenograft models of peritoneal carcinomatosis.

The epithelial cell adhesion molecule (EpCAM) is overexpressed in a wide variety of tumor types, including peritoneal carcinomatosis (PC) from gastrointestinal and gynecological malignancies. To develop a chimeric antigen receptor T (CART) cell therapy approach to treat patients with end-stage PC, we constructed third generation CARs specific to EpCAM using the 4D5MOC-B single chain variable fragment. CART cells were generated with lentiviral transduction and exhibited specific in vitro killing activity against EpCAM-positive human ovarian and colorectal cancer cells. A single intraperitoneal injection of the CART cells eradicated established ovarian xenografts and resulted in significantly prolonged animal survival. Since EpCAM is also expressed on normal epithelium, anti-EpCAM CART cells were generated by mRNA electroporation that display a controlled cytolytic activity with a limited CAR expression duration. Multiple repeated infusions of these RNA CAR-modified T cells delayed disease progression in immunodeficient mice bearing well-established peritoneal ovarian and colorectal xenografts. Thus, our study demonstrates the effectiveness of using anti-EpCAM CAR-expressing T cells for local treatment of PC in mice. The possibility of using this approach for clinical treatment of EpCAM-positive gastrointestinal and gynecological malignancies warrants further validation.

A fluorescence turn-on biosensor based on graphene quantum dots (GQDs) and molybdenum disulfide (MoS2) nanosheets for epithelial cell adhesion molecule (EpCAM) detection.

This paper presents a "turn-on" fluorescence biosensor based on graphene quantum dots (GQDs) and molybdenum disulfide (MoS2) nanosheets for rapid and sensitive detection of epithelial cell adhesion molecule (EpCAM). PEGylated GQDs were used as donor molecules, which could not only largely increase emission intensity but also prevent non-specific adsorption of PEGylated GQD on MoS2 surface. The sensing platform was realized by adsorption of PEGylated GQD labelled EpCAM aptamer onto MoS2 surface via van der Waals force. The fluorescence signal of GQD was then quenched by MoS2 nanosheets via fluorescence resonance energy transfer (FRET) mechanism. In the presence of EpCAM protein, the stronger specific affinity interaction between aptamer and EpCAM protein could detach GQD labelled EpCAM aptamer from MoS2 nanosheets, leading to the restoration of fluorescence intensity. By monitoring the change of fluorescence signal, the target EpCAM protein could be detected sensitively and selectively with a linear detection range from 3nM to 54nM and limit of detection (LOD) around 450pM. In addition, this nanobiosensor has been successfully used for EpCAM-expressed breast cancer MCF-7 cell detection.