Abstract
Epithelial cell adhesion molecule (EpCAM), a cancer stem cell (CSC) marker is over expressed in epithelial cancers and in retinoblastoma (RB). We fabricated an EpCAM targeting aptamer-siRNA chimera and investigated its anti-tumor property and EpCAM intracellular domain (EpICD) mediated signaling in epithelial cancer. The anti-tumor efficacy of EpCAM aptamer-siEpCAM chimera (EpApt-siEp) was evaluated by qPCR, northern and Western blotting in WERI-Rb1- RB cell line, primary RB tumor cells and in MCF7- breast cancer cell line. Anti-tumor activity of EpApt-siEp was studied in vivo using epithelial cancer (MCF7) mice xenograft model. The mechanism and pathways involved in the anti-tumor activity was further studied using protein arrays and qPCR. EpApt-siEp chimera was processed in vitro by dicer enzyme. Treatment of the WERI-Rb1 and MCF7 cells with EpApt-siEp revealed statistically significant down regulation of EpCAM expression (P<0.005) and concomitant reduction in cellular proliferation. In primary RB cells cultured from RB tumors, EpApt-siEp silenced EpCAM, significantly inhibited (P<0.01) cell proliferation and induced cytotoxicity. Knockdown of EpICD expressed in RB primary tumors led to repression of pluripotency markers, SOX2, OCT4, NANOG, and CD133. In vivo studies showed complete tumor growth regression without any toxicity in animals (P<0.001) and tumor tissues showed significant downregulation (P<0.05) of EpCAM, MRP1, ABCG2, stathmin, survivin and upregulation of ATM (P<0.05) leading to apoptosis by intrinsic pathway with minor alteration in cytokines. Our results revealed that EpApt-siEp potentially eradicated EpCAM positive cancer cells through CSC marker suppression and apoptosis, while sparing normal EpCAM negative adjacent cells.
Highlights
Epithelial cell adhesion molecule (EpCAM) is a well-known cancer stem cell (CSC) marker expressed on cell surface and regarded as a tumor associated antigen[1]
EpCAM is associated with increased proliferation, migration and invasion in both breast cancer and RB[5, 6].EpCAM protein is differentiated into extracellular domain (EpEx), transmembrane domain (EpTM) and intracellular domain (EpICD)
We report for the first time that EpCAM intracellular domain (EpICD) is over-expressed in RB, and knocking down EpCAM leads to the down-regulation of CSC markers such as SOX2, OCT4 and NANOG expression
Summary
Epithelial cell adhesion molecule (EpCAM) is a well-known cancer stem cell (CSC) marker expressed on cell surface and regarded as a tumor associated antigen[1]. EpCAM is associated with increased proliferation, migration and invasion in both breast cancer and RB[5, 6].EpCAM protein is differentiated into extracellular domain (EpEx), transmembrane domain (EpTM) and intracellular domain (EpICD). It plays a vital role in oncogenic signaling by EpCAM proteolysis and EpICD translocation into the nucleus [7, 8].Proteolysis of EpCAM leads EpICD to form complex withFHL2, β-catenin and Lef. To further improve the therapeutic potential of EpCAM targeting, aptamers with greater specificity and higher affinity were sought[13]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
