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
1707 - Clinical utility of precision immunoprofiling and monitoring of the tumor microenvironment using flow cytometry and CyTOF in patients with advanced NSCLC treated with atezolizumab: results from a phase II study for biomarker analysis (EPOC1702)
Presenter: Keisuke Kirita
Session: Poster Display session 3
Resources:
Abstract
3594 - Tumor mutation burden (TMB), PD-L1, IFN-γ signaling identify subgroups of patients (pts) who benefit from durvalumab (D, anti-PDL1) or D and tremelimumab (T, anti-CTLA4) treatment in urothelial bladder cancer (UC)
Presenter: Christophe Massard
Session: Poster Display session 3
Resources:
Abstract
744 - The decrease of TMB, TNB and HLA expression are the Mechanism of Drug Resistance of NSCLC to immunosuppressive PD-1/PD-l1.
Presenter: Sheng Yu
Session: Poster Display session 3
Resources:
Abstract
2350 - Eosinophilia during treatment of immune checkpoint inhibitors (ICIs) predicts succeeding onset of immune-related adverse events (irAEs)
Presenter: Rika Kizawa
Session: Poster Display session 3
Resources:
Abstract
5930 - A transcriptomic immunologic signature predicts favorable outcome in neoadjuvant chemotherapy treated triple negative breast tumors.
Presenter: Javier Pérez-peña
Session: Poster Display session 3
Resources:
Abstract
6127 - Alterations of TMB and TCR repertoires during Chemotherapy in East Asian lung cancer patients without TKI-related driver gene mutations
Presenter: Lele Song
Session: Poster Display session 3
Resources:
Abstract
1310 - Association of SCFA in gut microbiome and clinical response in solid cancer patients treated with andi-PD-1 antibody.
Presenter: Motoo Nomura
Session: Poster Display session 3
Resources:
Abstract
2286 - Extracellular matrix and tissue derived metabolites in a liquid biopsy identifies endotypes of metastatic melanoma patients with differential response to immune checkpoint inhibitor treatment
Presenter: Nicholas Willumsen
Session: Poster Display session 3
Resources:
Abstract
4107 - Pathologic scoring of pre-treatment H&E biopsies predicts overall survival in patients with metastatic clear cell renal cell carcinoma receiving nivolumab monotherapy
Presenter: Julie Stein
Session: Poster Display session 3
Resources:
Abstract
1291 - PD-L1 expression in uncommon EGFR-mutant non-small cell lung cancer and its response to immunotherapy
Presenter: Yun Fan
Session: Poster Display session 3
Resources:
Abstract