Abstract 1782
Background
EpCAM is a type I transmembrane glycoprotein with an extracellular domain (EpEX) and an intracellular domain (EpICD), which have 265 and 26 amino acid residues, respectively. EpCAM is highly expressed in advanced epithelial cancers and tumor-initiating cells, but its role in cancer progression remains to be elucidated.
Methods
To identify cell signaling pathways that are stimulated by EpEX, we used a Human Phospho-RTK Array Kit to screen for phosphorylation of RTKs. Inhibition of EpEX-induced EGFR-PI3K-AKT signaling was analyzed by small molecule inhibitors or shRNA knockdown.
Results
Here, we found that EpEX activated AKT signaling, thereby inducing the phosphorylation and nuclear exclusion of FOXO3a. The EGFR inhibitor, AG1478, and MEK inhibitor, U0126, both decreased the production of EpICD, which was found to be necessary for nuclear accumulation of β-catenin protein and expression of HIF1α target genes in vitro and in mouse xenograft models. We also demonstrated that treatment with an anti-EpCAM neutralizing antibody, EpAb2-6, decreased the ADAM17 and γ-secretase activity, the EpCAM-downstream gene expression, and tumor colony and sphere formation. We also found that EpAb2-6 inhibited EpEX-activated EGFR-PI3K-AKT signaling and induced apoptotic signaling through FOXO3a activation of HTRA2 gene expression. Importantly, we also showed that EpAb2-6 inhibited the nuclear translocation of EpICD and oncogenic signaling through β-catenin. Finally, in both metastatic and orthotopic animal models of colorectal cancer, EpAb2-6 therapy exhibited an antitumor effect and markedly extended the survival time of mice.
Conclusions
Our results demonstrate that EpEX contributes to malignancy by functioning as a growth factor, which activates EpICD-mediated signaling, thereby enhancing colon cancer cell survival. To the best of our knowledge, hEpAb2-6 is the first humanized anti-EpCAM antibody to directly trigger apoptosis in cancer cells. Thus, we provide novel insight into EpEX-EGFR signaling, which can be considered as a promising target for treatment of colon cancer.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Academia Sinica.
Disclosure
All authors have declared no conflicts of interest.
Resources from the same session
5650 - Tissue-based activation of mucosal-associated invariant T (MAIT) cells in combination ipilimumab and nivolumab checkpoint inhibitor (CI) colitis.
Presenter: Sarah Sasson
Session: Poster Display session 3
Resources:
Abstract
5944 - Significance of severe immune-related adverse effects (irAE) on patients with advanced tumors treated with immune checkpoint inhibitors being admitted for secondary toxicity: Clinical relevance and next steps
Presenter: Leyre Zubiri
Session: Poster Display session 3
Resources:
Abstract
5989 - Implementation of a dedicated immuno-oncology toxicity service reduces the acute impact of immune-related adverse events
Presenter: Anna Olsson-Brown
Session: Poster Display session 3
Resources:
Abstract
3267 - Cardiotoxic and pro-inflammatory effects induced by the association of immune checkpoint inhibitor Pembrolizumab and Trastuzumab in preclinical models
Presenter: Nicola Maurea
Session: Poster Display session 3
Resources:
Abstract
3417 - Interstitial lung disease associated with immune-checkpoint inhibitors in malignant diseases
Presenter: Akira Yamagata
Session: Poster Display session 3
Resources:
Abstract
2071 - A Phase 1 Study of Intraperitoneal MCY-M11 Anti-Mesothelin CAR for Women with Platinum Resistant High Grade Serous Adenocarcinoma of the Ovary, Primary Peritoneum, or Fallopian Tube, or Subjects with Peritoneal Mesothelioma with Recurrence after Prior Chemotherapy
Presenter: Christina Annunziata
Session: Poster Display session 3
Resources:
Abstract
4935 - Trial in progress: First-in-human study of a novel anti-NY-ESO-1–anti-CD3, TCR-based bispecific (IMCnyeso) as monotherapy in NY-ESO-1/LAGE-1A-positive advanced solid tumors (IMCnyeso-101)
Presenter: Juanita Lopez
Session: Poster Display session 3
Resources:
Abstract
5613 - Nimotuzumab-Cisplatin-Radiation versus Cisplatin-Radiation in HPV negative oropharyngeal cancer
Presenter: Kumar Prabhash
Session: Poster Display session 3
Resources:
Abstract
2576 - Interim analysis of a single arm phase 2 study of adjuvant nivolumab after salvage resection in head and neck squamous cell carcinoma patients previously treated with definitive therapy.
Presenter: Trisha Wise-draper
Session: Poster Display session 3
Resources:
Abstract
4758 - A Phase I Study of the CDK4/6 Inhibitor, Palbociclib in combination with Cetuximab and Intensity Modulated Radiation Therapy (IMRT) for Locally Advanced Squamous Cell Carcinoma of the Head and Neck (SCCHN); A Result of Dose Escalation Cohort
Presenter: Nuttapong Ngamphaiboon
Session: Poster Display session 3
Resources:
Abstract