Abstract 859: Basal Notch4 activation is a druggable marker of aggressiveness in a panel of human cancer cell lines
Authors: Astorgues-Xerri Lucile , Martinet Matthieu , Raymond Eric , Faivre Sandrine , Tijeras-Raballand Annemilaï 
Published: August 2019

Abstract
Background: Notch pathway has been involved in cell differentiation, proliferation, apoptosis, angiogenesis and drug resistance, as well as in epithelial-to-mesenchymal transition. Notch pathway activation leads to a proteolytic cleavage, releasing the Notch intracellular domain (NICD), which translocates to the nucleus and activates target genes, such as HES1 (interacting with Notch for maintenance of stem cells and progenitor phenotype). Our team has demonstrated the involvement of PlGF/VEGFR1/Notch4 axis in the angiogenesis of hepatocellular carcinoma, but what about the role of Notch in other cancer types? The aim of this work is to characterize the basal activation and the role of Notch4 in a panel of human cancer cell lines.
Materials and Methods: We characterized a panel of 8 pancreatic (PDAC), 8 head and neck (H&N), 5 colorectal (CRC), 5 cholangiocarcinoma (CK), and 10 hepatocellular (HCC) human carcinoma cell lines for intracellular domain of the notch protein 4 (NICD4), HES1, E-cadherin, and Vimentin expression by Western Blot. In each tumor type, cell lines with high and low Notch4 activation were selected to assess basal cell proliferation and migration, using MTT and wound-healing assay, respectively. In high versus low Notch4 cell lines, we assessed NUMB expression (involved in NICD proteasomal degradation) and the effect of a Notch inhibitor, PF- 03084014.
Results: Notch4 activation assessed by NICD4 expression was observed in 6 out of 8 (6/8) PDAC, 7/8 H&N, 2/5 CRC, 4/5 CK, and 5/10 HCC cell lines. In PDAC cells, Notch4 activation was correlated with high Vimentin expression. In PDAC-, H&N-, CRC-, and CK-low NICD4 cells, we observed an overexpression of NUMB, suggesting a correlation between low Notch4 activation and proteasomal degradation. In most tumor types, Notch4 activation was associated with an increased proliferation rate and basal migration. PF-03084014 had pronounced antiproliferative effects in high NICD4 cells in comparison to low NICD4 cells, except for HCC. In H&N cells, PF-03084014 displayed no effect on Notch4 activation. We also observed a decrease in HES1 expression (significant in high NICD4 cells) and an increased in AKT phosphorylation (significant in low NICD4 cells). We will further analyze the effect of PF-03084014 on cell signaling and migration in other tumor types to display the results at the conference.
Conclusions: In this study, we demonstrated a correlation between high Notch4 basal activation and increased proliferation/migration in a panel of human cancer cell lines, as well as higher sensitivity to the Notch inhibitor PF-03084014. In highly sensitive H&N cell lines, PF-03084014 inhibited Notch signaling pathway, whereas we observed an activation of AKT survival pathway in the low-sensitive ones. Since Notch inhibition is an interesting topic for antitumor therapy, this study could help to select tumor types that could be good candidate for Notch inhibition in the clinic.
Citation Format: Lucile Astorgues-Xerri, Matthieu Martinet, Eric Raymond, Sandrine Faivre, Annemilaï Tijeras-Raballand. Basal Notch4 activation is a druggable marker of aggressiveness in a panel of human cancer cell lines [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 859.