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
1122 - Platelets from metastatic cancer patients have increased aggregation and activation
Presenter: Meera Chauhan
Session: Poster Display session 3
Resources:
Abstract
2671 - Luminal B breast cancer prognosis prediction by comprehensive analysis of Homeobox genes
Presenter: Ayako Nakashoji
Session: Poster Display session 3
Resources:
Abstract
2650 - Long non-coding RNA E2F4as promotes tumor progression and predicts patient prognosis in human ovarian cancer
Presenter: Sun-Ae Park
Session: Poster Display session 3
Resources:
Abstract
1462 - FGF19 promotes esophageal squamous cell carcinoma progression by inhibiting autophagy
Presenter: Lisha Ying
Session: Poster Display session 3
Resources:
Abstract
5787 - Proof of concept on the role of ex vivo lung cancer spheroids, cytokines expression and PBMCs profiling in monitoring disease history and response to treatments.
Presenter: Raimondo Di Liello
Session: Poster Display session 3
Resources:
Abstract
5253 - Circulating microRNAs related to DNA damage response as predictors of survival in metastatic non- small cell lung cancer patients treated with platinum-based chemotherapy
Presenter: Dimitris Mavroudis
Session: Poster Display session 3
Resources:
Abstract
5286 - Prognostic value of CTCs in advanced NSCLC patients treated with platinum-based chemotherapy
Presenter: Silvia Calabuig-Fariñas
Session: Poster Display session 3
Resources:
Abstract
5781 - Exosomes in NSCLC as a source of biomarkers
Presenter: Elena Duréndez
Session: Poster Display session 3
Resources:
Abstract
1447 - The role of Pim-1 in the development and progression of papillary thyroid carcinoma
Presenter: Xin Zhu
Session: Poster Display session 3
Resources:
Abstract
1323 - Development and Validation of a RNA-Seq Based Prognostic Signature in Neuroblastoma
Presenter: Jian-Guo Zhou
Session: Poster Display session 3
Resources:
Abstract